7 DAY 2'74; a :7? PACER—Data Entry, Retrieval, I and Update for the National Coal Resources Data System (Phase I) GEOLOGICAL SURVEY PROFESSIONAL PAPER 978 2‘73”, )7. 5‘ LIV. ,“ g i: 4! :4" . g {:58 111376 *1} 3359“ PACER—Data Entry, Retrieval, and Update for the National Coal Resources Data System (Phase I) By S. M. CARGILL, A. C. OLSON, A. L. MEDLIN, and M. D. CARTER GEOLOGICAL SURVEY PROFESSIONAL PAPER 978 A set of programs, written in FORTRAN I V, which. extends the capability of GRASP and which has been developed in response to the need for a computer-based National Coal Resources Data System UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976 rasso UNITED STATES DEPARTMENT OF THE INTERIOR THOMAS S. KLEPPE, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Main entry under title: PACER. (Geological Survey professional paper; 978) Bibliography: p. Supt. of Docs. SI 19.16:978 1. National Coal Resources Data System. 2. PACER (computer program) I. Cargill, S. M. II. Series: United States. Geological Survey. Professional paper; 978. 2699.5.057P3 029.7 75-619422 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock Number 024-001-02768-2 CONTENTS Page Abstract _________________________________________________________________ 1 Introduction ______________________________________________________________ 1 Scope and purpose ________________________________________________________ 2 Acknowledgments _________________________________________________________ 2 Definition of terminology _________________________________________________ 2 System description ________________________________________________________ 3 PACER search and retrieval operation _________________________________ 3 MERIT data file _____________________________________________________ 5 WCOAL data file ____________________________________________________ 5 USALYT data file ___________________________________________________ 11 Entry of new data _______________________________________________________ 12 Use of the update option __________________________________________________ 14 Update procedure 1 __________________________________________________ 17 Update procedure 2 __________________________________________________ 20 Update procedure 3 __________________________________________________ 21 Update procedure 4 __________________________________________________ 22 Update procedure 5 __________________________________________________ 23 Use of tabular summary option ___________________________________________ 23 Example of interactive session ____________________________________________ 24 Programmer’s reference ___________________________________________________ 24 Modifications to GRASP ______________________________________________ 24 Update programs of PACER __________________________________________ 35 References cited __________________________________________________________ 36 Appendix A. Names used with NCRDS files ______________________________ 38 B. Program listings of modified GRASP routines ________________ 52 C. Program listings of PACER subroutines _____________________ 61 ILLUSTRATIONS Page FIGURE 1. MERIT data-entry form _____________________________________ 7 2. Coal provinces of the conterminous United States _______________ 8 3. Coal regions of the conterminous United States ________________ 9 4. Coal regions of the Alaska coal province ______________________ 13 5. Data-entry format for WCOAL ______________________________ 18 6. Data-entry format for USALYT _____________________________ 19 7. Example of an interactive session using PACER ________________ 25 8. Tabular summary of coal resources ___________________________ 30 9. Tabular summary of coal analyses ____________________________ 33 10. Subroutine activity flow _____________________________________ 36 TABLES Page TABLE 1 List of PACER commands ___________________________________ 4 2. List of WCOAL record variables _____________________________ 10 3. Geological age names used with WCOAL and ECOAL __________ 11 4. List of USALYT record variables ____________________________ 15 III Any use of trade names and trademarks in this publication is for descriptive purposes only and does not constitute endorsement by the US. Geological Survey. PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR THE NATIONAL COAL RESOURCES DATA SYSTEM (PHASE I) By S. M. CARGILL, A. C. OLSON, A. LuMEDLIN, and M. D. CARTER ABSTRACT PACER is a set of programs, written in FORTRAN IV, which extends the capability of GRASP and which has been developed in response to the need for a computer-based Na‘- tional Coal Resources Data System (NCRDS). PACER al- lows the user to enter data into one of three files, to search for and retrieve records using specific data elements, and to modify and update existing data records. All coal resource records west of the Mississippi River are grouped into WCOAL, whereas those east of the river are grouped into ECOAL. Each data record in WCOAL and ECOAL reflects a unique tonnage estimate of coal resource in a predefined category of thickness, overburden, and reliability of estimate. The USALYT file contains published coal analytical data and is structured to be as compatible as possible with the coal-resource tonnage files; however, it is not yet separated into east and west. A detailed description of the files is ac- companied by user documentation for the use of the data files. A programmer’s reference is also included to facilitate the installation and use of this software system on other computers. INTRODUCTION When probability of future energy shortages was recognized during the summer of 1973, considerable thought was directed to finding substitute sources of energy. Particular emphasis was given to studying coal in terms of that resource satisfying the energy needs of the United States during the interim period between the present dominant use of petroleum products and the advent of widespread use of fusion, solar, geothermal, and other forms of energy. The U.S. Geological Survey undertook to develop a com- puter-based National Coal Resources Data System (NCRDS) so that better estimates and evaluations could rapidly be made of this huge domestic resource. Development of the NCRDS began in July 1974 along two somewhat parallel paths which have be- come known as Phase I and Phase II. Phase I includes retrieval and analysis software and three data bases: 1. WCOAL, which contains coal-resource tonnage estimates for deposits west of the Mississippi River; 2. ECOAL, which contains coal-resource tonnage estimates for deposits east of the Mississippi River; 3. USALYT, which contains published coal ana- lytical data. Information is stored in these files in an aggregated form, readily accessible for providing resource sum- maries throughout given geographic regions. Phase I data records are stored in files which are accessed by a modified version of the Geological Re- trieval and Synopsis Program (GRASP) (Bowen and Botbol, 1975) known as PACER: this is an acro- nym for Program to Analyze Coal Energy Re- sources. As of December 1975, the data files WCOAL and ECOAL contain nearly 25,000 logical records of coal-resource information for deposits east and west of the Mississippi River. These two data files are from different sources. WCOAL consists of nearly 16,000 records and is a corrected and modified version of the Rocky Moun- tain Coal Reserve file received from the U.S. Bureau of Mines. ECOAL contains coal-tonnage records for the States east of the Mississippi River and probably will contain about 10,000 records when the file is completed in the spring of 1976. Phase II data bases will include geologic informa- tion taken from point sources, such as core samples, field observations, and other forms of analysis. The software associated with Phase II will be designed to process these data so that they may be reduced to an aggregated or summary form amenable to Phase I applications. 2 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS PACER provides the user with access to the data in an interactive timesharing mode. The method of access to the master data records, using a remote terminal, is the main purpose of this report. Some new programming has been done to fill the specific requirements of the N CRDS and its principal users. These new programs are additions to GRASP, as it has been published, and, therefore, are included herein. Examples of data are provided for clarity, and a sample session is included in a later section to help the user understand data relationships in the file. Because the file structures of ECOAL and WCOAL are identical, all references to WCOAL also apply to ECOAL, except Where noted. SCOPE AND PURPOSE The scope of WCOAL, in terms of data elements, is limited to an estimate of coal tonnage for some defined area (State, county, township/range, and section) and contains specific definition of coal field, district, province, region, formation, coal bed, depth to coal coal (overburden), reliability of data, rank, and thickness of coal. Other incidental information includes the source document name from which the tonnage estimates were taken and its year of publi- cation; topographic quadrangle name; base year of the tonnage estimate; and geologic age by System and Series. The scope of USALYT overlaps, to a large extent, the data in WCOAL. Replacing data such as depth, thickness, reliability, and tonnage estimates, are such data elements as sample identifi- cation and type, analysis identification and type, ash, moisture, fixed carbon, oxygen, hydrogen, and nitrogen values. The purpose of this report is to provide a detailed description of how a user may access, enter, modify, and delete the data in the Phase I file. The design philosophy of PACER, as it pertains to WCOAL and USALYT, is also described in detail for the benefit of the programmer who wishes to modify the system or to install the software on his computer. The purpose of the project, development of the NCRDS, has been to provide a means whereby esti- mates of coal resources, by a variety of character- istics, can be made accurately and quickly, and whereby the data may be updated easily with new information. The PACER system was developed on Computer Science Corporation’s INFONET timesharing sys- tem on a UNIVAC 1108 under the company’s Gen- eral Programming System (GPS). Development of PACER took approximately 2 man-years. ACKNOWLEDGMENTS Development of Phase I of the National Coal Re- sources Data System has been facilitated by the use of the Rocky Mountain Coal Reserve file from the U.S. Bureau of Mines MERIT (Mines Energy Re- sources, Information, and Transportation) System. This file of some 5,000 logical records formed the basis of WCOAL, and as such, has been the nucleus for Phase I data development. The authors wish to express their thanks to Roger W. Bowen, particularly for his invaluable help in converting the original data into GRASP formats and generally for his assistance in understanding the GRASP system. We also Wish to thank Joseph Moses Botbol for his continuing encouragement to bring the system into production. DEFINITION OF TERMINOLOGY Definitions of some computer terminology are given to clarify its use in this report. Interactive. This term implies, in a broad sense, reciprocal activity between user and computer. It also implies a response to a user-initiated transac- tion to permit appropriate user action based upon timely computer response. The word is closely as- sociated with a sense of immediacy of response time: interactive is a matter of degree; therefore, a system is less interactive the longer it takes to get a response. Timesharing. This term, in its simplest definition, is a computing technique in which several users may utilize a computer concurrently for input, process- ing, and output functions. Dictionary. The dictionary, or dictionary file, contains the alphanumeric entries which are associated with a data record. The data record contains not the value itself but a “pointer.” The pointer is a num- ber that indicates at which sequential position in the dictionary file may be found the correct char- acter string value for that data field. Master file. The master file contains the records of the data base. The fields within the record contain integer values (for integer data), floating-point values (for decimal data), and integer pointers (for alphanumeric data). The file is structured slightly differently from a conventional GRASP numeric master file in that multiple-choice-type items are not used, nor is the master file compressed. SYSTEM DESCRIPTION 3 Mask file. The “Mask file contains the item names, item types (integer, real, character string, multi- ple choice, and qualified real), and pointers to the first entry in the dictionary file for each character- type item” (Bowen and Botbol, 1975, p. 3). Definitions file. This file contains the acronyms used for data variable and the meaning (definition) of each acronym. Other record length parameters are also defined in this file; however, the reader is re- ferred to the GRASP report (Bowen and Botbol, 197 5) for a detailed description. Additional data processing definitions may be found in “Computer Dictionary” (Sippl and Sippl, 1974), or in Calkins and others (1973). SYSTEM DESCRIPTION A brief description of procedures and commands is provided below for the PACER version of the GRASP system. The reader is referred to the more detailed description of GRASP (Bowen and Botbol, 1975) for further clarification of procedures and commands. A detailed description of the data bases, WCOAL and USALYT, may be found following de- scriptions of the programs. PACER SEARCH AND RETRIEVAL OPERATION After a successful hookup and log-on procedure has been completed, the user requests the program by typing in the word PACER following the system prompt, !. At this point, PACER types a statement in- forming the user which data files are available for use and giving a brief description of the data con- tained therein, and requests the user to name the data file to be accessed. The user may select one of several commands to perform various functions once the system has prompted with, ENTER COMMAND. Table 1 lists these commands and their meanings. The following is a detailed explanation of some of the commands. COND (condition) requires three entries: acro- nym/relation/value. The acronym refers to the data variable name (for example, STATE), and value is the desired value of the variable (for example, ALASKA). The relation between these two may be expressed by one of the following seven operators: EQ ______ equal to. NE ______ not equal to. GT ______ greater than. LT ______ less than. LE ______ less than or equal to. GE ______ greater than or equal to. BE ______ between or equal to. Examples: STATE EQ WYOMING COUNTY EQ JOHNSON YEAR BE 1967,1970 RANK LE SUBBIT TONNAGE GT 350.00 Note that all the relational operators may be used for both alphabetic and numeric data. This is valid for alphabetic data only if they are ordered in such a way that their sequence in a list is significant. For example, rank of coal (RANK) may be logically or- dered in a list so that anthracite (ANTH) tops the list, followed by semi-anthracite (SEMI ANTH), bituminous (BIT), low-volatile bituminous (LV BIT), medium-volatile bituminous (MV BIT), high- volatile bituminous (HV BIT), and lignite (LIG- NITE) . If the condition were set so that RANK EQ LIGNITE, then all lignite records would be re- trieved; if RANK GT MV BIT were entered, then only LV BIT, SEMI ANTH, and ANTH records would be retrieved; if RANK BE MV BIT,ANTH were entered, then all records for anthracite, semi- anthracite, low-volatile bituminous, and medium- volatile bituminous coal would be retrieved. Conditions may reflect repeating acronyms and relational operators, and each condition is prefaced by A, B, C, D, . . ., Z (up to 26 conditions). Thus, CONDition A might be STATE EQ MONTANA, and CONDition B, perhaps STATE EQ WYOMING. It is up to the user to associate these conditions with the proper logic to effect the desired retrieval, as described below in the command, LOGIC. PACER will keep printing the next available al- phabetic character as it expects another condition. If no more conditions are to be entered, the user strikes carriage return (CR) without any entry. LOGI (logic) provides the user with a way to associate any two or more conditions specified in the CONDition command. Three Boolean logical opera- tors are used to connect one condition with another: .AND. or * .OR. or + .NOT. or — Note that the word operators are bracketed by peri- ods, but that the equivalent symbol operators are not. The structure of a LOGIc command allows the user to string together as many as 26 conditions (A,B,C, . . . ,Z) with operators as follows: A.AND.B+C*D 4 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS TABLE 1.—List of PACER commands ENTER COMMAND: HELP THE COMMANDS WHICH MAY BE ISSUED (AND THEIR MEANING) ARE LISTED BELON: (VARIABLE NAMES WILL COND - INITIATES THE REQUEST FOR RETRIEVAL CRITERIA TO BE ENTERED IN THE FORM: NAME REL VALUE LOGI - INITIATES THE REQUEST FOR A LOGICAL EXPRESSION TO BE ENTERED USING LOGICAL OPERATORS. SEAR - INITIATES THE SEARCH OF A FILE BASED UPON PREVIOUSLY ENTERED CONDITIONS AND LOGIC. LIST - ALLOWS THE USER TO LIST SELECTED VALUES BE ASKED FOR) IN A FILE. FILE - ALLOWS THE USER TO SELECT OR CHANGE THE DATA BASE TO BE USED. OUIT - TERMINATES THE SYSTEM. ENTERING ! IN RESPONSE TO A PROMPT WILL ALSO STOP THE SYSTEM. NAME - USED TO PRINT ITEM NAMES. THEIR TYPES AND DEFINITIONS IN A SELECTED SET OF GROUPS. HELP - USED TO OBTAIN THE ABOVE COMMAND DEFINITIONS. REVI - LISTS THE FILES WHICH HAVE BEEN USED AS WELL AS THE CONDITIONS AND LOGIC ENTERED. DUMP - PRINTS ALL ITEMS OR SELECTED ITEMS PRESENT FOR EACH RECORD IN A SELECTED FILE. WAITS AFTER EACH N LINES. FUNC - PROVIDES FOR THE COMPUTATION OF FUNCTIONS ON ITEMS IN A DATA SET (OR FILE). MERG - COMBINES THE CONTENTS OF SEVERAL SELECTED SUBFILES INTO A SINGLE SUBFILE. TABL - PERMITS THE SELECTION OF SPECIALLY SORTED AND FORMATTED TABULAR OUTPUT DISPLAYS. UPDA - PERMITS THE ADDITION» THE DELETION! OR THE MODIFICATION OF RECORDS OR PORTIONS OF RECORDS BELONGING TO THE MASTER FILE; Parentheses may be used to group specific logical relationships, as in the following example: (A.AND.B+ C) *D The order in which conditions are satisfied is given by the Boolean operators: .NOT., .AND., and .OR. If parentheses are used, they take precedence over the order of the operators. In the example above, the expression (A.AND.B+C) is evaluated before it is combined with D. SEAR (search) is a function that allows the user to actually retrieve the desired data records on the basis of the conditions that were logically connected. The user must define a new file name which will con- tain the retrieved records. The new data file thus created is a subfile of WCOAL or USALYT and may be saved for future study or may be deleted at the termination of the session using the QUIT command. If the file is to be deleted after conclusion of the session, the deletion is performed external to PACER execution under control of the operating system: in the case of INFONET, this is done with a EDROP “file-name” command directive. The user may access records in a previously cre- ated subfile. He may also combine records residing in two separate subfiles, each of which were retrieved by two separate searches of the main file, into a single subfile through the use of the MERGe com- mand. The user may refine the data contained in a subfile by generating new conditions and logic and by performing a search of the subfile to satisfy those conditions and that logic. A new subfile is then cre- ated. Future use of any subfile must be preceded with SYSTEM DESCRIPTION 5 a reference to one of the available main files after the ENTER DATA BASE NAME command in order that all dictionaries are properly linked with the data. The UPDA (update) command is described in de- tail in a later section because it is a new and exten- sive modification of the original GRASP system. Other command options available (table 1) are self-explanatory at the time of operation. The user should note that the QUIT command terminates PACER sessions. The computer system will then prompt the user with the names of user files that have been created with a request to specify those files that are to be saved, perform the indicated file maintenance, and followed by a !. The response of OFF breaks the link between the terminal and the computer. MERIT DATA FILE The Rocky Mountain Coal Reserve data file of the MERIT System was acquired from the Bureau of Mines when it contained some 5,200 records of coal resources for States west of the Mississippi River. Data records are entered into the MERIT file in an 80-column card image format, and are put out also in an 80-column card image format. Figure 1 shows that the system requires the data to be entered on four different card types, which are identified in column 9 of the form. The first two cards contain data pertinent to location and stratigraphy, and the third card contains bibliographic data. The fourth card contains multiple DCT codes and tonnage esti- mates. In the DCT code, the D stands for depth to coal, the C stands for class, and the T stands for thickness of the coal seam; these codes are equivalent to Branch of Coal Resources classification nomen- clature, ORT (overburden, reliability, and thick- ness) . The four physical records (card types) consti- tute one logical record. WCOAL DATA FILE The WCOAL file is a modified version of the MERIT file in that several Bureau of Mines data elements have been removed and new Geological Survey data elements have been added. The follow- ing data fields have been retained from the indi- cated cards of the MERIT record: Card No. 1 ________ P.M. TOWNSHIP NO. RANGE NO. E/W SEC. NO. COAL FIELD NAME FORMATION NAME Card No. 2 ________ SEAM NAME RANK NAME Card No. 3 ________ DATA SOURCE YR. OF PUBL. Card No. 4 ________ DCT all 'TONNAGE values. In addition, three other Bureau of Mines variables have been retained, the names of which do not ap- pear in the data entry form shown in figure 1, but which are a part of the MERIT file. From card No. 3, Quadrangle Name (QUAD) and Base Year (BYEAR) have been retained. The first three vari- ables of each card, FIPS State code, FIPS county code, and a record sequence number, have been lumped together to form a single WCOAL variable called ID. All other data fields have been deleted from each of the MERIT records because either the data con- tained in the field are inconsistent, or the data are infrequently, if ever, entered for the variable, or they are anticipated not to be applicable to Phase I of the NCRDS. The remaining data fields and the additional new fields, when strung together, form a single physical and logical record. In the MERIT system, the State code, county code, and sequence number together are repeated from card to card as the logical link between the several physical records. In WCOAL, however, the emphasis has changed from that of location to the use of ORT codes and the corresponding tonnage values as the basis for a unique record. Only one set of ORT codes and one tonnage value are provided per record. The effect of this change has been to create WCOAL as a file of 15,972 unique tonnage records. Each record has been expanded from the abbrevi- ated Bureau of Mines record to include eight new variables: STATE ________ State name (not FIPS code). COUNTY ______ County name (not FIPS code). AAPGPRV _____ AAPG province number. COALPRV _____ Coal province name. REGION ______ Coal region name. DISTRCT ______ Local area designator. SYSTEM ______ Geologic age: System. SERIES _______ Geologic age : Series. 6 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS WCOAL, therefore, is composed of records from Bureau of Mines and Geological Survey files. Each record is organized into four categories: Location information. Geologic designations. Bibliographic information. Resource delimiters. Table 2, list of WCOAL record variables, provides a complete list of the variables, in their proper se- quence, that make up one WCOAL record. Within each category is listed the variable name or mnemon- ic, its data type code, and a description. PACER al- lows one of the three data type codes to be associated with any variable: I = Whole numbers (integer values) R= decimal numbers (real values) A = alphanumeric strings The appropriate type code for each item is shown in table 2. Although each variable is briefly de- scribed in table 2, some further elaboration of the data elements is useful, especially as to the purpose of some of the items. Therefore, each variable is described below, with specific reference to appendix A, which shows the names each variable can assume as listed in WCOAL dictionaries. STATE name is used in preference to the FIPS (U.S. Natl. Bur. Standards, 1973) State code be- cause the name is more readily known to the user. COUNTY name is also used instead of the FIPS county code. A list of all county names and the as- sociated State is available from a US. National Bu- reau of Standards (1973) publication and is not provided. PMERID is the principal meridian from which a township/range survey was begun, and is given as a numeric code in WCOAL records. Appendix A.1 lists the meridians and baselines of the United States rectangular surveys, as provided by the Bureau of Land Management, as well as the Bureau of Mines code associated with each name. TWNSHIP is the township number of the town- ship/range survey. Three digits are provided for the town-ship number, allowing values from 001 to 999. However, no provision has been made for half town- ships. NS is the township direction, north or south. RANGE is the range number, and, like TWN- SHIP, three digits are allowed with no provision for half ranges. EW is the range direction east or west. SECTION is the section number Within a town- ship/range unit. This is a two-digit value usually between 01 and 36. AAPGPRV is the AAPG (American Association of Petroleum Geologists) province number (Meyer, 1970). The purpose of using this number is to pro- vide a link between the National Coal Resources Data System and other national energy data systems. The associated geologic provinces, districts, basins, and so on, do not necessarily correspond from one re- source to another. COALPRV is the coal-province name. Figure 2 shows the coal provinces of the conterminous United States, Alaska being an additional province. REGION is the coal-region name and is a subset of coal provinces. Figure 3 shows the coal regions of the conterminous United States, and figure 4 shows the coal regions for the Alaska province. The coal regions for the lower 48 States correspond to those given by Trumbull (1960), but no previous designa- tions have been given to the regions of the Alaska province as shown in figure 4, although the base map from Barnes (1961) has been used. Appendix A.2 provides a list of the region names available for use with WCOAL. FIELD is the coal-field name. A complete list of coal-field names used in WCOAL may be found in appendix A.3. DISTRCT is a local area designator applicable mainly to the Alaskan areas. These names are, in many cases, interchangeable With field names, im- plying no hierarchical difference between district and field. Appendix A.4 lists all names which are used with WCOAL and which are in the coal district dictionary. FORMATN is the formation name. A complete list of formation names used in WCOAL may be found in appendix A.5. BED is the coal-bed name. A complete list of coal- bed names used in WCOAL is provided in appendix A.6. Neither FORMATN nor BED contains a complete list of formation or coal-bed names. The list current- ly in use is predominantly that compiled by Bureau of Mines engineers using Geological Survey publica- tions, and other documents, for the compilation. This list will be modified for use in NCRDS. SYSTEM is the geological age designation. The following system names are in use with WCOAL: Tertiary, Cretaceous, Jurassic, Triassic, Permian, Pennsylvanian, and Mississippian. SERIES is the name given to a divided system. wen . an. one 2.8 E 35.36 5 358.25 N .a. A .m .37.... a. .33 .v ..~¢ A n ..~T..m~ .~ ..m~u..: ._ "88.05 .Eém tuning BEHEIA auburn 2:85.: 23 8.38: 6 85.5 m 8.8%.: .~ 3.5302 ._ 92:822.: .n 336 8:322... .m .3835 s ssanuu M. 33.3 fl sasnn 6 33.33 .n 33-32 .N 3373 ._ SYSTEM DESCRIPTION mmoOu hue ____._______d;._..._;____._._:____.__._.._.._.____Z_.._i....__..__.PI_.__; ______....___.____.__;I____.._______..227.7.22;_.__....___._____.._.__._ _________::____._::._._:__.._Z_; = 3|. 1 I «I. u _ _ fl — — u .nlfiu- _ _ ~ Quinn — - u NHL. Q—IN. H2222. .5: H3223 ._.8 34:28 ._.8 $5.22. p8 “3228. 5a “2222 .50 I: I .. 7. .In 7. ___—_____———d4 -d_-__-q__—__1d-—-IK-dfi .fi— _Bn—.u_ —_—_lq—_—__InuflI——u__-_—_-:BOM_.—_ a Jan; 38 f 38 52: no...» ooh: 358 5.3 L Oil-h th—h :Ih. (Ola a; O. h; altn IO!“ .0 SIG. ‘0‘ al.- 31“! 3|! __ O. C II. DI- NI. JJJIJIJIJIJIjJIqIJJIJJwI—JVIJIJJJIJI _ . . .lj _ . _ .IAI. _ 1 _ _ . _ _ d u _ _ . _ _ . . . _ . . _ N . _ . _ _ :81 n H.118 n no: _ _ 2 g. s... _ 0.. .2 g. “nan uz)h> QUAD BYEAR H) SOURCE YEAR a) THICKNS I OVRBRDN I RELIABL I RANK A TONNAGE I STATE NAME COUNTY NAME PRINCIPAL MERIDIAN TOWNSHIP NUMBER DIRECTION OF TOHNSHIP (N DR S) RANGE NUMBER DIRECTION OF RANGE (E OR M) SECTION NUMBER AAPG PROVINCE NUMBER COAL PROVINCE NAME COAL REGION NAME COAL FIELD NAME LOCAL AREA DESIGNATOR FORMATION NAME COAL BED NAME GEOLOGIC AGE: SYSTEM GEOLOGIC AGE! SERIES TOPOGRAPHIC QUADRANGLE NAME BASE YEAR FOR TONNAGE ESTIMATES 00 MEANS ORIGINAL DATA 51 MEANS DATA TAKEN AS OF 195! SOURCE DOCUMENT PUBLICATION YEAR OF SOURCE DOCUMENT COAL BED THICKNESS CODE 2 It TO 28 INCHES 26 T0 #2 INCHES GREATER THAN A? INCHES 2.5 TO 5 FEET 5 T0 10 FEET GREATER THAN IO FEET UNCLASSIFIED CLASSIFIED BY ZONE RDEN THICKNESS IN FEET 0 TO 3000 0 TO 2000 0 TO 1000 1000 TO 2000 2000 TO 3000 GREATER THAN 3000 STRIPPABLE UNCLASSIFIED ILITY CODE MEASURED MEASURED AND INDICATED INDICATED INFERRED I UNCLASSIFIED RANK OF COAL OVE B REL A ”IIIZNINMMIMHCIIMIIMI WO‘UNHHGQU‘WOUNFnO‘IO‘mkwNV-d ANTH t ANTHRACITE SEMI ANTH I SEMI'ANTHRACITE BIT I BITUMINOUS LV BIT I LOU-VOLATILE BITUMINOUS MV BIT = MEDIUM-VOLATILE BITUMINOUS HV BIT I HIGH-VOLATILE BITUMINOUS HV BIT A 1 HIGH-VOLATILE BITUMINOUS A HV BIT B I HIGH-VOLATILE BITUMINOUS R HV BIT C 3 HIGH-VOLATILE BITUMINOUS C SUBBIT I SUB-BITUMINOUS SUBBIT A = SUB-BITUMINOUS A SUBBIT B 8 SUB-BITUMINOUS 8 SUBBIT C I SUB-BITUMINOUS C LIGNITE ' LIGNITE COAL RESOURCE IN MILLIONS OF SHORT TONS. .oo A TONNAGE RECORD EXISTS FOR EVERY UNIQUE COMBINA' TION OF THICKNESS CODE! OVERBURDEN CODE. RELI- ABILITY CODE: RANK CODE. AND LOCATION CATEGORY. AS WELL AS CERTAIN STRATIGRAPHIC DESIGNATIONS. SYSTEM DESCRIPTION 11 Series names in use with WCOAL are Eocene, Low- er, Middle, Miocene, Oligocene, Paleocene, Pliocene, and Upper. Table 3 shows the ordered relationship between System and Series. Note that the repetition of Series names from one System to another has no effect on their use, because each requires only one dictionary entry. TABLE 3.—Geologica.l age names used with WCOAL and ECOAL System Series Pliocene Miocene Oligocene Eocene Paleocene Upper Lower Upper Middle Lower Upper Middle Lower Upper Lower Tertiary _______________________ Cretaceous Jurassic Triassic ________________________ Pennsylvanian __________________ Upper Middle Lower Mississippian Upper Lower QUAD is the topographic quadrangle name and refers to the quadrangle for which the resource ton- nage was made. Often the quad name is not known or is not unique to the tonnage record. Therefore, the present list of quadrangle names given in appendix A.7 is very brief. BYEAR is the base year for which estimates were made of the tonnages of coal. As an example, 51 indi- cates that the estimates are for remaining resources as of 1951; 00 indicates that the tonnage estimate is of original coal resources. SOURCE is the publication from which the data were taken. Appendix A.8 lists these publications. YEAR is the publication year of the source document. THICKNS is the coal thickness code. The name of this variable corresponds to the Bureau of Mines “T” for thickness in the DCT code. The possible values of THICKNS are shown in table 2. OVRBRDN is the overburden thickness code. The name of this variable corresponds to the Bureau of Mines “D” for depth in the DCT code, but the categories have been renumbered to permit a search over a range of overburden depths. The possible values of OVRBRDN are shown in table 2. RELIABL is the reliability code given to a ton- nage estimate. The name of this variable corres- ponds to the Bureau of Mines “C” for class in the DCT code. It also has been renumbered to permit a search over a given range. The possible values of RELIABL are shown in table 2. RANK is the name given for the quality of coal in terms of energy content. Fourteen rank categories are provided in the list; they range from anthracite to lignite. The order of these ranks is such that the user may enter ranges of rank (for example, RANK BE HV BIT,SUBBIT) as a condition. TONNAGE is the estimated coal resource in mil- lions of short tons to two decimal places. A tonnage value exists for every unique combination of thick- ness code, overburden code, reliability code, and location. USALYT DATA FILE A review of the published coal analytical data re- vealed that it was not feasible to add this type of data to the existing area/tonnage records of the WCOAL file, as there were few, if any, areas of direct correlation. Therefore, a separate data base of published coal analytical data is maintained as the file USALYT on the PACER system; it is accessed by specifying USALYT for the ENTER DATA BASE NAME command. This file uses the same dic- tionaries as WCOAL; however, it has separate mask and definitions files for the 46 data items, as shown in table 4. The two files were structured as closely alike as possible to facilitate retrieval and correlation of data by the user. A comparison of tables 2 and 4 shows that the location, geologic, and bibliographic fields are the same as in WCOAL, with the exception of the item BYEAR (base year). BYEAR is not ap- plicable to the type of data in USALYT. For this reason, the resource delimiter fields also have been deleted, with the exception of RANK. The following is an expansion of the brief definitions given in table 4 of the additional data items for USALYT: ANIDA is the alphabetic part of the analysis identification number. Some of the reported analyses have alphanumeric identification numbers. Because PACER treats alphanumeric data as dictionary items, the identification number is recorded in two parts. This dictionary contains the 26 letters of the alphabet. 12 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS ANIDN is the numeric part of the reported analy- sis identification number. SAMPTYP is a numeric code to indicate the type of sample on which the analysis was done. ANLYTYP is a numeric code to represent the condition of the sample when it was analyzed. VALREP is a numeric code indicating the type of data that the individual values represent, such as an average of several samples or a single sample. TRACE indicates by Y=yes or N=no whether the analysis included trace-element values. These values are not included in the data file, because their occurrence in the Phase I published analytical data is rare but could be retrieved from the original source. HGRIND represents the result of a Hardgrove grindability test on the sample. OTHER indicates by Y=yes or N=no whether other types of tests were reported in the analysis. Results of these tests are not in the data file but could be retrieved from the data source. BTU is the energy value of the coal reported in British thermal units. If the value is reported in other units it has been converted. ASH: [DEFORM], [SOFT], [FLUID] indicate the temperature in degrees Fahrenheit at which the ash deforms, softens, or fluidizes. If the reported values were in another form, they have been converted. The final 12 items are the proximate and ultimate analysis values. All items are reported in percent to one decimal place. ENTRY OF NEW DATA Since the creation of the initial WCOAL file from the US. Bureau of Mines data tape, data entry has been accomplished using a SYCOR model 340 pro— grammable terminal. The data entry format for WCOAL (fig. 5) is displayed on the terminal CRT, and the data items are entered and checked by pro- grams, as described below. These data—entry con- trols are indicated by the character or number immediately following the data label, which is en— closed in brackets. The SYCOR programming sys- tem reserves symbols W, X, Y, and Z to call user- writer field programs. Therefore, these symbols below may call different programs, according to the data-field name. The data fields have been arranged to allow all data belonging to one record to be dis- played on the screen at one time. The data-entry format is programmed to move the cursor to each data field according to groups of related informa- tion. Data-entry control characters for the WCOAL format include: STATE and COUNTY __5] Alphabetic data must be entered. PMD _________________ X] The cursor skips to the AFC data item, if a blank or zero (0) is en- tered, because it is as- sumed that no township and range information is available if the prin- cipal meridian is un- known. TWN and RNG _________ N] A numeric entry is required. . NS and EW ____________ W] The value entered is compared with a table of acceptable values, and an error message is displayed if no match is found. PRV, FLD, FMN _______ A] The data must be a1- phabetic. RGN, DST, BED _______ W] The cursor skips to the next line in order to maintain logical data entry from reporting forms. THK, OVB, REL _______ W] The cursor skips inter- vening data fields so that these items may be entered consecutively. Format control then passes to the next entry on the reporting form. SYS, SER, RNK _______ W] The cursor skips fields on the screen so that these items can be en- tered consecutively. Each of these items is also compared with a table of acceptable val- ues in order to reduce data-entry errors. QDR __________________ M] An alphanumeric val- ue may be entered. ENTRY OF NEW DATA 13 o 132 168° 16° 0 I36 EXPLANATION 4 160° . o 44° 14° I I 156 152° 148 1 “IRON AcEAN Regions . Alaska Penlnsula Cook Inlet-Susitna Central Alaska Northern Alaska Southeastern Alaska 01%me Shaded areas and X’s indicate | known coal deposits OCEAN INDEX MAP OF ALASKA 190 290 390 490 590 MILES I I I I I 100 200 300 400 500 KILOMETRES FIGURE 4.—Coal regions of the Alaska coal province. (Modified from Barnes, 1961.) BYR __________________ X] The data value is YR ___________________ X] The cursor skips to the checked against an ac- ID field, after the user ceptable range of val- presses the TAB/SKIP ues, and an error mes- key. sage is printed if the comparison fails. ID ____________________ X] The cursor skips to the SRC __________________ A] Some alphanumeric TON field, after the data must be entered in user press the TAB/ this field. SKIP key. 14 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS TON __________________ Z] The data entry will be checked for a value with two decimal places. Any other value range will cause an error message to be printed. [*], [C] These symbols are constant field indi- cators which contain a line feed character for continuous transmis- sion, because the record exceeds the 256-charac- ter buffer available in the SYCOR terminal. Data entry to file USALYT requires a two—page SYCOR format shown in figure 6. Page 1 has data- entry restrictions similar to the WCOAL format. Page 2 data fields include the following controls: ANIDA ______________ A] Only alphabetic data entry is acceptable. ANIDN, S—TYPE _____ N] Only numeric data can be entered. A-TYPE, VAL\REP, HRDGV-AGRIND, TRACE, OTHER. BTU,ASH (DEF SOF N] Numeric data. FLD), FREE-SWELL. MOISTUR, VOL-MAT, Z] The format checks for FIXEDC, ASH, a numeric entry with one HYDROGN, CARBON, decimal place. Any other NITROGN, OXYGEN; entry will result in an SULFUR, SULFATE, error message. The \ SULFPYR, SULFORG. character indicates suc- ceeding data fields with the same “Z” control. A] Alphabetic data only. USE OF THE UPDATE OPTION The update software permits the user to edit and update data in the master file while operating in an interactive mode from a remote terminal. The following update procedures are available for the user to: 1. Add new records to the master file; 2. Delete existing records from the master file; 3. Sequentially review and modify records existing in a subfile of the master file and, upon com- pletion of the review, post the subfile onto the master file; 4. Select, by a key, a record residing in a subfile of the master file, review the contents, modify the data, and post the individual record onto the master file; 5. Modify the value of a given data element for all the records existing in a specific subfile and then post the contents of this subfile onto the master file. To use the update system, the user must first ac- cess the host computer from his terminal. After the appropriate identification has been entered, the computer will begin a new line with the character ! which is the prompt for the user to type in the program name, PACER, followed by a carriage re- turn. This command accesses the PACER program and begins execution with the message: WELCOME TO THE USGS “PACER” VERSION OF THE “GRASP” RETRIEVAL SYSTEM. THE FOLLOWING DATA BASES ARE AVAILABLE: ECOAL—USGS EASTERN US COAL RE- SOURCES DATA WCOAL—USGS WESTERN US COAL RE- SOURCES DATA USALYT—PUBLISHED US COAL CAL DATA The user must specify one of the above data bases at the prompt for a data base name, ENTER DATA BASE NAME. A new master file data base may be selected at any time during a user session by en- tering the word, FILE, following the prompt, ENTER COMMAND. When the prompt, ENTER COMMAND, is again displayed on the terminal, the user may proceed immediately to update, by entering UPDAte, if he has a new data file or a subfile of the master file available for editing. If not, he may select a sub- file of records to be edited by proceeding through the standard search procedure, specifying the se- quence of commands CONDitions, LOGIc, and SEARch, each followed by the appropriate infor- mation as documented in the GRASP literature. Assuming that the user either has a new data file or has generated a subfile of records which re- quire updating, he will respond to the next ENTER COMMAND prompt with the entry of UPDAte. The message, PLEASE PRESS CARRIAGE RE- TURN, will then be displayed. If the user is fa- miliar with the procedures and has knowledge of the code for suppressing the output of user instruc- tions (see programmer’s reference), he may en- ter it at this point before pressing the carriage re- turn. If not, he will be presented with instructions for the updating procedure as well as special ANALYTI- USE OF THE UPDATE OPTION TABLE 4.—Dist of USALYT record variables LOCATION INFORMATION OEOLOOIC DESIGNATIONS BIBLIOGRAPHIC INFORMATION RANK INFORMATION ANALYSIS INFORMATION SECTION AAPOPRV SECTION NUMBER AAPO PROVINCE NUMBER STATE A STATE NAME COUNTY A COUNTY NAME PMERID I PRINCIPAL MERIDIAN THNSMIP I TOHNSMIF NUMBER NS A DIRECTION OF TOMNSMIP (N OR 5) RANOE I RANGE NUMBER E! A DIRECTION OF RANGE (E OR M) I I SYSTEM SERIES OEOLOGIC AGE! SYSTEM OEOLOOIC AGE! SERIES COALPRV A COAL PROVINCE NAME REGION A COAL REGION NAME FIELD A COAL FIELD NAME DISTRCT A LOCAL AREA DESIGNATOR FORMATN A FORMATION NAME BED A COAL BED NAME A A OUAD A TOPOORAPNIC OUAORANCLE NAME SOURCE A SOURCE DOCUMENT YEAR I PUBLICATION YEAR OF SOURCE DOCUMENT RANK A RANK OF COAL ANTM - ANTNRACITE SEMI ANTM - SEMI~ANTMRACITE BIT - BITUMINOUS Lv BIT - LOV-VOLATILE BITUMINOUS MV BIT . MEDIUM-VOLATILE BITUMINOUS NV BIT - NION-VOLATILE BITUMINOUS Nv HIT A - NION-VOLATILE BITUMINOUS A MV BIT B - NION-VOLATILE BITUMINOUS B Nv BIT C . NIGN-VOLATILE BITUMINOUS C SUBBIT - SUB-BITUMINOUS SUBBIT A - SUB-BITUMINOUS A SUBBIT B - SUB-BITUMINOUS a SUBBIT C - SUB-BITUMINOUS c LIGNITE - LIGNITE ANIDA A REPORTED ANALYSIS IDENTIFICATION (ALPHABETIC) ANION I REPORTED ANALYSIS IDENTIFICATION (NUMERIC) SAHPTVP I SAMPLE TYPE I I CHANNEL 2 I RUN OF MINE 3 I DRILL CORE 6 I OTMER ANLYTYP I ANALYSIS TYPE AS RECEIVED AIR DRIED MOISTURE FREE MOISTURE AND ASH FREE 5 OTHER VALREP I VALUES REPRESENT I l SINGLE SAMPLE 2 I AVERAGE OF MORE THAN ONE SAMPLE 3 I RANGE OF SAMPLE VALUES A I OTHER DUN—- III-I TRACE A SAMPLE ANALYZED FOR TRACE ELEMENTS(YIYES NINO) NGRIND I MARDGROVE GRINDABILITY INOEx OTNER A RESULTS OF OTHER TESTS SMORN ON ANALYSIS BTU I BTU VALUE ASNDEF I ASM OEFORMATION TEMPERATURE IN FAMRENMEIT ASNSOF I ASH SOFTENING TEMPERATURE IN FAHRENHEIT ASNFLD I ASH FLUID TEMPERATURE 1N FANRENNEIT FRESNEL R FREE-SRELLING INDEX MOISTUR R MoISTURE VALUE IN PERCENT VOLMAT R VOLATILE MATTER VALUE IN PERCENT FIXEDC R FIXED CARBON VALUE IN PERCENT ASN R ASN VALUE IN PERCENT NVDROGN R HYDROGEN VALUE IN PERCENT CARBON R CARBON VALUE IN PERCENT NITRoeN R NITROGEN VALUE IN PERCENT OXYGEN R OXYGEN VALUE IN PERCENT SULFUR R TOTAL SULFUR VALUE IN PERCENT SULFATE R SULFATE VALUE IN PERCENT SULFPVR R PVRITIC SULFUR IN PERCENT SULFORO R ORGANIC SULFUR IN PERCENT 15 16 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS instructions for any of the five procedures he may select. If the user does not enter the instruction- suppression code, the following message will be displayed: THIS IS “UPDATE” IT IS DESIGNED TO PERMIT THE USER TO ADD RECORDS TO OR DELETE RECORDS FROM THE MASTER FILE, OR TO CHANGE RECORDS OR PORTIONS OF RECORDS IN A SUBFILE OF THE MASTER FILE AND TO POST THESE CHANGES ONTO THE MASTER FILE. THE FIVE PROCEDURES USED TO UPDATE THE MASTER FILE ARE: 1. THE ADDITION OF NEW RECORDS AL- READY WRITTEN INTO A TEMPORARY FILE. UNLIKE THE OTHER UPDATE PRO- CEDURES WHICH OPERATE ON RECORDS IN THE MASTER FILE FORMAT, THIS PROCEDURE OPERATES ON RAW DATA RECORDS AND CONVERTS THESE REC- ORDS TO THE MASTER FILE FORMAT FOR INSERTION INTO THE MASTER FILE. 2. THE DELETION, BY KEY, OF RECORDS ALREADY EXISTING IN THE MASTER FILE. 3. THE SEQUENTIAL REVISION OF REC- ORDS FROM A SELECTED SUBFILE (LE. SELECTED THROUGH A LOGICAL SEARCH) FROM THE MASTER FILE. THIS SUBFILE MAY THEN BE POSTED ONTO THE MASTER FILE AFTER THE DESIRED REVISONS ARE COMPLETED. 4. THE SELECTION, BY KEY, OF ANY REC- ORD BELONGING TO THE SUBFILE FOR REVISION OF ANY SELECTED DATA ELE- MENT. THE DATA MANAGER HAS THE OPTION OF POSTING THE SELECTED RECORD ONTO THE MASTER FILE OR LEAVING IT, AS REVISED, IN THE SUB- FILE FOR FURTHER REVISION. 5. THE BATCH REVISION OF A GIVEN DATA ELEMENT WHICH WILL BE THE SAME VALUE FOR ALL RECORDS IN THE SE- LECTED SUBFILE. WHEN REVISION HAS BEEN COMPLETED ON ANY SELECTED SUBFILE, THE USER MAY THEN ELECT TO POST THE REVISED SUBFILE ONTO THE MASTER FILE, 0R SAVE THE SUBFILE FOR REVIEW AND POSSIBLE FURTHER REVISION BY ANY OF THE 2-5 UP- DATE PROCEDURES. RECORDS DELETED FROM THE MASTER FILE ARE SAVED IN THE “SAVDEL” (SAVE DELETION) FILE FOR FUTURE RECOVERY IF THERE SHOULD ARISE A NEED TO RECONSTITUTE THESE RECORDS. An output display of each record reviewed is pro- vided automatically for the deletion procedure, the sequential revision procedure, and the keyed re- vision procedure. The display of each record for correct data is optional when adding new records, but need not be used because dictionary nonmatches will be displayed to the data manager at the time of record entry. No display is associated with the batch revision because normally this revision will be made to a larger number of records, and such a display would inhibit the speed of the batch re- vision. If a display is desired following the batch revision, the data manager can choose to omit post- ing the revised subfile to the master file. He may then select the sequential or the keyedyrevision pro- cedure to review the record and perhaps further update the subfile before posting it onto the master file. The output display for the editing of records is formatted so that the data-element positions are similar to those positions in the SYCOR formats for data input, as discussed in the section on entry of new data. The example below is the formatted dis- play Which is used for the interactive edit and up- date procedures of PACER when used to operate on records from the WCOAL file: ********** STATE: WYOMING COUNTY: CAMPBELL PMERID: 6 TWNSHIP: 58 NS: N RANGE: 76 EW: W SECTION: 0 AAGPRV: 0 COALPRV: NO DATA ENTERED REGION: NO DATA ENTERED THICKNS: 4 FIELD: SPOTTED HORSE DISTRICT: NO DATA ENTERED OVRBRDN: 3 FORMATN: FORT UNION BED: CANYON RELIABL: 2 SYSTEM: NO DATA ENTERED QUAD: BYEAR: ** SERIES: NO DATA ENTERED SOURCE: USGS BULL 1050 YEAR: 1957 RANK: SUBBIT ID: 56005005 . . . KEY: KEY: 13159 TONNAGE: 11.80 ********** USE OF THE UPDATE OPTION 17 The display of records from the USALYT file is shown in the following example: ********** STATE: NORTH DAKOTA COUNTY: ADAMS PMERID: 5 TWNSHIP: 121 NS: N RANGE: 95 EW: W SECTION: 10 AAPGPRV: 395 COALPRV: N GREAT PLAINS REGION: FORT UNION FIELD: NO DATA ENTERED DISTRICT: NO DATA ENTERED FORMATN: FORT UNION BED: NO DATA ENTERED SYSTEM: TERTIARY QUAD: NO DATA ENTERED SERIES: PALEOCENE SOURCE: NDU DIV MIN CIRC 8 YEAR: 1934 RANK: LIGNITE ANID: NO. 10316 SAMPTYP: 1 ALYTYP: 1 VALREP: 1 TRACE: N HGRIND: O OTHER TESTS: N BTU: 6820 ASH: (DEFORM) 0 (SOFT) 0 (FLUID) 2280 FRESWEL: 0. MOISTUR VOLMAT FIXEDC ASH HYDROGN CARBON NITROGN 35.6 29.6 26.9 0 0 0 0 OXYGEN SULFUR SULFATE SULFPYR SULFORG KEY : 0. 2.7 0. 0. 0. 529 * * * * * * * * * * Procedure 1 is selected for the addition of new 'records to the master file. Before this procedure can be used, a file of new data must be entered into the host computer system. Although there are many ways to create a file of new data, the method used predominantly will be to enter the data records onto a tape cassette through the SYCOR terminal and then to use the terminal to transmit these rec- ords to the host computer. The file containing the new data is structured so that each record is an unformatted, but fixed length, string of characters (including blanks). This char- acter string must be translated through a format to obtain the internal machine language values from the numerical data and to determine whether there is a dictionary match for the alphanumeric data. If a match is found, the numerical pointer to that die- tionary entry is determined. If there is no diction- ary entry match for the given item of alphanu- meric data, the user is given the option of adding that data value to the dictionary or of correcting the data input (that is, a spelling error) so that it will match an existing dictionary entry. After the user has completed the translation phase for the new data, he may elect either to post the translated file directly to the master file or to save it for further editing and revision by means of procedures 3 through 5 before posting it to the master file. UPDATE PROCEDURE 1 Selection of update procedure 1 will produce the following message on the user terminal: THE ADD RECORD PROCEDURE IS DE- SIGNED TO READ A RAW DATA INPUT FILE AND CONVERT THE RECORDS TO THE REC- ORD STRUCTURE THAT IS COMPATIBLE WITH THE MASTER FILE OF “PACER,” CHECKING FOR CORRECT DICTIONARY ENTRIES, AND PROMPTING THE DATA MANAGER TO RE- QUEST ADDITION OF THE NONMATCHING DICTIONARY ENTRIES TO THE DICTIONARY LIST OR TO CORRECT THE INPUT ENTRY SO THAT IT MATCHES A VALUE ALREADY IN THE DICTIONARY LIST. IF THE INPUT FILE DOES NOT CONTAIN RAW DATA, THE DATA MANAGER CAN EXIT THIS REVISION PROCEDURE TO SELECT A DIFFERENT PROCEDURE (3—5) BY ENTER- ING “QUIT,” WHEN PROMPTED FOR A FILE NAME. If the appropriate instruction-suppression code has previously been entered, this message will also be suppressed. Next, the user will be prompted with NAME OF RAW DATA INPUT FILE. The response to this prompt must be either the name of the newly created raw-data file or the word QUIT which will terminate execution of the cur- rent update procedure and will permit the user to PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS 18 Ca nw «e w. coon: {H4003 .3“. pgom khanm-3dn~ln.m "559nm n x z r 3 U main-mum2.33%:cvatvnva—«cvx35ngganmnnungawwnzemmaennnfiwu30.22.»va a: n. 19 USE OF THE UPDATE OPTION Um M.» ND .0 3 on 3 2 .n_ 2:, mu a mu 9w 1%. ”A. n. Na K a mm «.5 an «m .n. 2.. IV we “a 9.» nu. 3 my «a .354me Sm pussy anagrfiamlé “£ch “an 1 un o. "niwnmn~&cn ungnmmmn:gauuhmcmwNQNnNwan awnwg \rcp «93. Gem— < z 0 uqcahémnfiwmfiUnshnnmnrmgom«usuawmvugu~rn.“un—n—huc—mri—ner—rawa. h 20 PACER——DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS select an alternative procedure or return to the search and retrieval operation. If the name of the raw-data file is properly entered, the user will then be prompted for the NAME OF TRANSLATED FILE. This name is selected at the user’s discretion, and care must be taken to ensure that it does not coincide with the name of another file already existing on that user account number. Next, the user will be asked if he wishes to have the contents of every input record, as corrected for any dictionary mismatch, displayed on the terminal. A response of YES will display every record, and a response of NO will suppress the display. If an entry on the record does not match the existing en- tries in that dictionary, the message, THERE IS NO DICTIONARY MATCH FOR DATA NAME is displayed, followed by the name of that data element, the message ALPHANUMERIC DATA, and the displayed data value. The user is prompted with DO YOU WISH TO ENTER THIS DATA IN THE DICTIONARY? “YES” OR “NO.” A YES will place that data value in its dictionary, and subsequent records containing that data value will obtain a dictionary match. If the response is NO, the user is prompted with the message, ENTER DATA VALUE FOR DATA NAME, in order to correct the data value, followed by the data name and the message, DATA VALUE. The newly en- tered data value is again tested for a dictionary match, and if found, the record translation pro- cedure continues. If the new data value does not have a dictionary match, the user is again queried to determine whether he intends to enter that data value in the dictionary, or if he wishes to re-enter the data value. This cycle will continue until a dic- tionary entry exists that will match that data value. When all the new data records have been trans- lated, the following message Will be displayed: THE INPUT FILE IS NOW READY FOR POST- ING ONTO THE MASTER FILE. IF YOU WISH TO MAKE FURTHER CHANGES, TO THIS FILE BEFORE IT IS POSTED, SELECT THE SE- QUENTIAL, BATCH OR KEYED REVISION PROCEDURE AND SPECIFY THE NAME OF THIS FILE. FILE “TEST” HAS BEEN REVISED. DO YOU WISH TO WRITE THIS FILE ONTO THE MASTER FILE? “YES” OR “NO”: where TEST, in this case, is the name of the trans- lated file. If the response is NO, the file is saved, and the prompt, UPDATE PROCEDURE (1—5), is again displayed. If the response is YES, the trans- lated file is added to the master file and the user is queried with, DO YOU WISH TO SAVE THIS FILE? “YES” OR “NO.” A YES will save the translated file, Where a NO Will cause the file to be dropped. Finally, the message: UPDATE OPERATIONS HAVE BEEN COM- PLETED. IF YOU WISH TO CONTINUE WITH THE UPDATE PROCEDURE, ENTER THE NUMBER (1-5). ENTERING A “0” FOR THE PROCEDURE PROMPT OR “QUIT” FOR THE FILE PROMPT WILL RETURN CONTROL TO THE SEARCH AND RETRIEVAL PORTION OF “PACER.” is displayed followed by the prompt, UPDATE PROCEDURE (1—5), to permit further update op- erations (1—5), or to return to search and retrieval (0). UPDATE PROCEDURE 2 Update procedure 2 is the deletion procedure, which is accomplished by specifying the record key of records from the master file. The prompt, DATA FILE TO BE REVISED, will be for a file that has already been selected by a prior logical search for records that are to be deleted from the master file. If the instruction-suppression code has not been set previously, the following message will be dis- played on the terminal: THIS IS THE MASTER FILE RECORD DELE- TION PROCEDURE. WHEN PROMPTED, THE DATA MANAGER WILL SPECIFY THE KEY NUMBER OF THE RECORD TO BE DELETED. THE DELETED RECORD WILL BE WRITTEN, FOR PRESERVATION, ONTO THE “ESAVE,” “WSAVE,” OR “SAVUSA” FILE. THEN, THE DATA ELEMENTS IN THE MASTER FILE WILL BE BLANKED, AND A NEW IDENTIFI- CATION NUMBER WILL BE WRITTEN ONTO THE MASTER FILE. THIS NUMBER WILL BE ENCODED TO CONTAIN THE DATE OF DE- LETION AND THE IDENTIFICATION NUM- BER OF THE DATA MANAGER RESPONSIBLE FOR EXECUTING THE DELETION. IN ADDI- TION, A DELETION MESSAGE WILL BE SUP- ERIMPOSED OVER SEVERAL OF THE DATA FIELDS TO NOTE TO THE USER THAT THAT KEY NUMBER NO LONGER HAS A VALID RECORD IN THE MASTER FILE. WHEN THE DATA MANAGER HAS CON- CLUDED THE DELETION PROCEDURE, USE OF THE UPDATE OPTION 21 ENTRY OF A “—1” AT THE PROMPT FOR “KEY” WILL END THE PROCESS. It is presumed that the user has determined, by examination of the selected file, which record keys will be in the deletion process. He Will enter the key number following the prompt, KEY .NUM- BER OF RECORD TO BE DELETED. This will cause the data elements to be blanked out in that record of the master file having the specified key number. A deletion message is inserted in the RE- GION, DISTRCT, and BED data fields along with a coded ID number giving the year, month, and day of deletion as well as the data manager identifica- tion, as in the following example: ********** STATE: PMERID: ** TWNSHIP: *** NS: COALPRV: REGION : FIELD: DISTRICT: FORMATN: BED: SYSTEM: QUAD: SERIES: SOURCE : RANK: ID: 75090299 . . . KEY: 13158 COUNTY: RANGE: *** EW: ** RECORD DELETED. . . ** SEE “ID” FOR DATE ** AND MANAGER CODE. SECTION: ** AAPGRV: *** ** THICKNS : * ** OVRBRDN : * RELIABL : * BYEAR : ** YEAR: *** TONNAGE : .00 ******.**** For example, the date of deletion is 75 (year), 09 (month), and 02 (date), and 99 is the data man- ager identification. The corresponding record in the selected subfile is eliminated entirely. This prevents that record from being posted onto the master file again after the subfile has been subsequently sub- jected to any of the other (3—5) updating proce- dures. To terminate the deletion procedure, a nega- tive entry, such as ~1, following the prompt, KEY NUMBER OF RECORD TO BE DELETED, will permit the data manager either to select another update procedure or to return to the search and retrieval activity of PACER. UPDATE PROCEDURE 3 Update procedure 3 is designed for the sequential review and revision of records belonging to a sub- file selected from the master file. After the sequen- tial revision has been completed, the data manager may elect to post the subfile back onto the master file or to save the subfile for further update opera- tions. If the user has not previously entered the instruc- tion-suppression code, the first message displayed will be the following instructions: RECORDS FROM THE DESIGNATED SUBFILE WILL BE PRESENTED SEQUENTIALLY FOR REVIEW AND UPDATE. AFTER ALL REC- ORDS HAVE BEEN EXAMINED BY THE RE- VIEWER, HE MAY THEN ELECT TO POST THE RECORDS IN THIS SUBFILE ONTO THE MASTER FILE. WHENEVER YOU WISH TO LEAVE A SE- LECTED DATA ELEMENT UNCHANGED, EN- TER AN ASTERISK, *, FOLLOWED BY A CAR- RIAGE RETURN. IF YOU WISH TO PROCEED TO THE NEXT RECORD IN THE FILE, ENTER THE CHAR- ACTERS “NEXT” FOLLOWING THE PROMPT: “NAME OF DATA E L E M E N T TO BE CHANGED.” THE “NEXT” COMMAND WILL LEAVE THAT RECORD IN ITS ORIGINAL, UN- REVISED STATE AND THE NEXT RECORD WILL BE DISPLAYED, IN SEQUENCE, FROM THE SUBFILE. IF AT ANY TIME YOU DO NOT WISH TO REVIEW THE REMAINDER OF THE FILE, ENTER “QUIT.” Following this message will be a display of the first record in the subfile, as shown in an earlier example. This display will be followed by the prompt, NAME OF DATA ELEMENT TO BE CHANGED. The data manager may either enter a valid data-element name or specify the command NEXT or QUIT. If a proper data-element name has been entered, the next prompt will be either, ENTER VALUE, if it is a whole number, ENTER DECIMAL VALUE, if it is decimal data, or EN- TER DATA, if the value is an alphanumeric value. At this point, the data value may be left unchanged by entering an asterisk, *, for the alphanumeric data, or an asterisk enclosed by apostrophes, ’*’, for the integer and decimal data. If the value is al- phanumeric, a search is made to determine whether the data entry matches an already existing diction- ary entry. If there is a matching dictionary entry, or if the proper type of numerical data has been entered, the data manager will be prompted with, 22 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS DO YOU WISH TO CHANGE ANY MORE DATA ELEMENTS BELONGING TO THIS RECORD? ENTER “YES” OR “NO.” A response of NO will cause all preceding changes to that record to be posted back onto the subfile. A response of YES will again display the prompt, NAME OF DATA ELEMENT TO BE CHANGED. The user can then select another data element to revise, or he may en- ter NEXT or QUIT. The NEXT command nullifies all data changes made to that record and proceeds to display the next record from the subfile. The QUIT command presents the user with the option of posting the subfile onto the master file or leav- ing the subfile available for further activity. If the alphanumeric input does not match a dic- tionary entry, the message, THERE IS NO DIC- TIONARY MATCH FOR DATA NAME, is dis- played, followed by the name of the data element, and the prompt, DO YOU WISH TO ENTER THIS DATA IN THE DICTIONARY? “YES” OR “NO.” An entry of YES will make that alphanumeric value a permanent dictionary entry and then query for further data changes to the record. A NO entry will bring up the prompt, NAME OF DATA ELE- MENT TO BE CHANGED, giving the data man- ager the opportunity to re-enter the correct alpha- numeric value for that data element, or to select a different data-element name for data revision. After all records in the subfile have been re- viewed or after QUIT has been entered in response to the prompt, NAME OF DATA ELEMENT TO BE CHANGED, the prompt, FILE “(subfile name)” HAS BEEN REVISED. DO YOU WISH TO WRITE THIS FILE ONTO THE MASTER FILE? “YES” OR “NO” will appear. A response of NO returns control for selection of another up- date procedure. A response of YES posts the sub- file onto the master file, following with the prompt, DO YOU WISH TO SAVE THIS FILE? “YES” or “NO.” If NO, the subfile is dropped; if YES, the subfile is saved for further use. In either case, the message: UPDATE OPERATIONS HAVE BEEN COM- PLETED. IF YOU WISH TO CONTINUE WITH THE UP- DATE PROCEDURE ENTER THE NUMBER (1—5). ENTERING A “0” FOR THE PROCED- URE PROMPT OR “QUIT” FOR THE FILE PROMPT WILL RETURN CONTROL TO THE SEARCH AND RETRIEVAL PORTION OF “PACER.” is printed followed by the prompt, UPDATE PRO- CEDURE (1-5) , for selection of further update op- erations. UPDATE PROCEDURE 4 Update procedure 4 is designed to permit the user to access a given record from a previously se- lected subfile by means of the record key number. The data contained in that record is displayed in the same format as illustrated earlier. If the in- struction-suppression code has not been set, the fol- lowing instructions will precede the first prompt, KEY. RECORDS FROM THE DESIGNATED SUBFILE WILL BE PRESENTED, AS SPECIFIED BY KEY NUMBER, FOR REVIEW AND UPDATE. AFTER THE REVIEWER HAS EXAMINED THE CONTENTS OF THE RECORD OF INTEREST, HE MAY ELECT TO POST THAT RECORD ONTO THE MASTER FILE. REGARDLESS OF WHETHER OR NOT THE RECORD IS POSTED TO THE MASTER FILE, IT WILL REMAIN, AS REVISED, IN THE SUB- FILE. TO ACCESS THE DESIRED RECORD, RE- SPOND TO THE PROMPT “KEY” BY ENTER- ING THE RECORD’S KEY NUMBER. . . . EN- TERING A “—1” WILL CONCLUDE THE KEYED ACCESS PROCEDURE. IF YOU WISH TO GO ON TO ANOTHER REC- ORD IN THE FILE, ENTER THE CHAR- ACTERS “NEXT” FOLLOWING THE PROMPT: “NAME OF DATA ELEMENT TO BE CHANGED.” THE “NEXT” COMMAND WILL LEAVE THAT RECORD IN ITS ORIGINAL, UN- REVISED STATE AND PROMPT FOR THE NEXT RECORD KEY. WHENEVER YOU WISH TO LEAVE A SE- LECTED DATA ELEMENT UNCHANGED, EN- TER AN ASTERISK, *. After the key number has been specified for the KEY prompt, the selected record is then displayed, followed by the prompt, NAME OF DATA ELE- MENT TO BE CHANGED. The data modification procedure for this record is identical with the se- quential revision procedure (update procedure num- ber 3). The NEXT and the QUIT commands are also used in the same context as in the sequential revision procedure. The asterisk response again is used to leave the data fields unchanged. After revision of the record has been completed, the prompt, DO YOU WISH TO POST THIS REC- ORD TO THE MASTER FILE? “YES” OR “NO,” is displayed. If the response is YES, it is posted to the master file as well as to the subfile. If the re- sponse is NO, it is posted to the subfile only. After USE OF THE UPDATE OPTION 23 the keyed revision is concluded, the data manager can, by means of procedure 3 or 5, make further corrections to the subfile and then post the entire subfile onto the master file. The next prompt after the one for posting the record onto the master file is, DO YOU WANT TO REVIEW ANY MORE RECORDS? “YES” OR “NO.” A response of YES will produce the prompt, KEY, whereas a response of NO concludes the keyed update procedure and returns the prompt, UPDATE PROCEDURE (1—5). Entry of a nega- tive integer value following the KEY prompt will also conclude the keyed update procedure. UPDATE PROCEDURE 5 Update procedure 5 is the batch revision proce- dure. It is used to change all subfile records to the same specified data value for a selected data ele- ment. If the instruction-suppression code has not been set, the following message will be displayed: THIS IS THE BATCH UPDATE PROCEDURE. GIVEN A SPECIFIED DATA ELEMENT NAME AND A SPECIFIED DATA ELEMENT VALUE, THIS PROCEDURE CHANGES ALL RECORDS IN THE GIVEN SUBFILE TO THE DATA VALUE SPECIFIED FOR THAT DATA ELE- MENT NAME. THE BATCH EDIT/REVISION PROCEDURE CAN BE TERMINATED BY ENTERING “QUIT” WHEN A PROMPT FOR THE NAME OF THE DATA ELEMENT IS ENCOUNTERED. This message will be followed by the prompt, NAME OF DATA ELEMENT TO BE CHANGED. The user will respond to this prompt and the ones that follow for the data values in the same manner as when using update procedures 3 and 4. Because of the mass record revision capability of this updating procedure, the batch procedure does not produce a display of any of the records changed. If it is desired to review any records in this sub- file before posting them onto the master file, the sequential or the keyed revision procedure may be selected after the batch revision process has been concluded. To review records with the sequential revision procedure, enter NEXT following the prompt, NAME OF DATA ELEMENT TO BE CHANGED, and the next record from the subfile will be displayed. Entering QUIT will conclude the review. If the keyed revision procedure is selected for review, enter the record key number following the prompt, KEY. If the key number is unknown, enter the value 1. The keyed read accesses the first record with a key greater than or equal to 1. To access the next record in the subfile enter NEXT following the prompt, NAME OF DATA ELE- MENT TO BE CHANGED, and then a key value exceeding by one the key value of the previous record. This will access the record in the subfile with the next higher key. A continuation of this process will have the same effect as a sequential re- view. The user can terminate this procedure at any time, by entering a negative key value for the key prompt, or QUIT in place of NEXT for the data- element name. After the update and posting of a subfile onto the master file, the data manager can conclude the update process by entering a 0 (zero) when prompted with UPDATE PROCEDURE (1—5). At this point, the prompt, ENTER COMMAND, will be displayed, and the user may respond with any one of the standard PACER commands (see table 1). It is also possible at this point to select another subfile to be used for the editing and correcting of the master file. If several corrected subfiles have been saved for future posting to the master file, care must be taken to ensure that if any of the subfiles contain over- lapping records, they will be posted in proper se- quence to avoid negating previously posted record corrections. USE OF TABULAR SUMMARY OPTION Data may be retrieved from either USALYT or WCOAL in a predefined tabular output form on a wide carriage terminal (135 characters per line, or more) by entering the command TABLE. A data file retrieved from WCOAL will be listed showing ton- nage of coal in various thickness categories by rank, coal bed, and overburden. Because the width of paper is a limiting factor and because of the natural break in thickness categories for varying ranks of coal, two summary tables are automatically printed, if required by the data, for thickness categories given in inches or feet. The user is prompted to enter the data file to be printed and a description of the area searched to be printed as a title. As each data record is read in, it is checked for THICKNS equal to “unclassified” or “classified by zone,” or RELIABL equal to “unclassi- fied.” If any of these conditions are true, the tonnage is added to the appropriate one of three subtotals, and the record is skipped. The other data records are then written to one of two files, depending upon whether THICKNS is in feet or inches. 24 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS After all records are read, the inches file is sorted by county, rank, coal bed, overburden, thickness, and reliability. A table is printed in the form shown in figure 8, new lines of subtotals being printed at every change in overburden, bed, rank, or county. A line showing the totals for all thickness columns is printed at the end of the table. If no data are re- ported in inches, or after the first end of file, the program reads, sorts, and prints the table for THICKNS reported in feet, also shown in figure 8. Upon reaching an end of file for the second, or for the only data file, a total line is printed for all tables shown. If any input records have been skipped be- cause of THICKNS or RELIABL conditions, a mes- sage is printed showing the total tonnage omitted, followed by the tonnage of coal excluded by each THICKNS or RELIABL condition. A final total ton- nage for the area under consideration is then printed. When a file of analytical data has been retrieved from USALYT, entering the command TABLE from a wide carriage terminal (135 characters per line, or more) will produce a tabular output as shown in figure 9. The user is prompted to enter the name of the data file to be printed and to enter a description of the area searched, which is to be printed in the title. The input data file is sorted by county, rank, and coal bed. Data records are read and a subtotal computed until a change in coal bed, rank, or county occurs. A separate counter is kept for each variable because a number of incomplete records are antici- pated. The data are then averaged and printed ac- cording to the format shown in figure 8. EXAMPLE OF INTERACTIVE SESSION The questions and requests in figures 7, 8, and 9 provide examples of actual use of the USGS National Coal Resources Data System. Inputs required and prompts and responses by the PACER system util- ized in Phase I studies are illustrated. Questions: 1. What is the total tonnage of bituminous and subbituminous coal in T5—6N, R89—90W of the Yampa coal field in Colorado? 2. What coal chemical analyses are available in this area, and what are the average sulfur, ash, and Btu values? Requests : 1. Tabulate the tonnage of coal in this area by county, rank, coal bed, and thickness of coal bed and overburden. 2. Tabulate the chemical analyses of the coal in this area. PROGRAMMER’S REFERENCE This section includes two topics: 1. Modifications to the GRASP system which are required in order to provide updating and edit- ing capabilities in PACER; 2. New programs which constitute the updating and editing capabilities of PACER, called by the UPDATE command. The user should note that PACER is presently op- erational on the Computer Science Corp. (INFO- NET) timesharing UNIVAC 1108 system in El Segundo, Calif. Some INFONET-dependent pro- grams have been used with the PACER subroutines, and are, therefore, not transferrable to other com- puters. Similar or equivalent programs must be available or written for PACER to operate in its present form. The INFONET-dependent programs are noted at the end of discussion for each PACER subroutine in appendix C. MODIFICATIONS TO GRASP As discussed earlier, PACER is a modified version of the GRASP search and retrieval program. The modifications to the search and retrieval system are minor and involve the tailoring of GETREC, the input and output subroutine, to obtain greater oper- ating efficiency with the particular file structures of WCOAL, ECOAL, and USALYT. Because of the needed capability for editing and updating these three master files, they were created as keyed record files. This permits the random access of records for editing and updating. In addition, very few of the data fields in an NCRDS master record contain blank information; instead, they contain in- teger data or integer pointers for alphanumeric data contained in the dictionaries. Little is to be gained in terms of storage by packing these records. However, a significant proportion of CPU time is saved by storing them in the unpacked mode. Thus, the PACER version of GRASP is structured to handle keyed and unpacked master file records, but all other major features of GRASP are retained. The GRASP documentation, therefore, can be utilized as a user’s guide for the search and retrieval operation of PACER. The principal distinction between PACER and GRASP is the addition of considerable software pro- gramming to permit user updating and editing of PROGRAMMER’S REFERENCE 25 QPACER WELCONE TO THE uses “PACER" VERSION OF THE "GRASP" RETRIEVAL SYSTEM. THE FOLLOWING DATA BASES ARE AVAILABLE: ECOAL - USGS EASTERN US COAL RESOURCES DATA WCOAL — USGS WESTFRN US COAL RESOURCES DATA USALYT - PUBLISHED US COAL AAALYTICAL DATA THE USER MUST SPECIFY CAE OF THE ABOVE DATA BASES FOLLOWING THE PROMPT. A CPANGE OF DATA BASES CAN BE MADE AT ANY TIME BY ENTERING THE WORD ”FILE" FOLLOWING THE PROMPT TO "ENTER COMMAND." ENTER DATA BASE NAME: WCOAL ENTER CCMNAND: CONE A. STATE E0 COLORADO B. FIELD E0 YANPA C. TWNSHIP HE bob D. NS an N E. RANGE BE 89990 F. Ew E0 w G. ENTER COMMAND: LOGIC ENTER LOGIC: A*B*C*D*E*F ENTER CCMHANO: SEARCH ENTER INPUT FILE NAVE: WCOAL ENTER OUTPUT FILE NAME: RYANPA ALL 15972 RECORDS OF WCOAL SEARCHED. 125 RECORDS FOUND WHICH SATISFY THE REQUEST. THEY HAVE BEEN STORED IA RYANPA SRU'S: 140.6 ENTER COMMAND: FUNC ENTER NAME OF FILE: HYAMPA FUNCTIONS AVAILABLE AT THIS TIME ARE: MEAA FIT FIGURE 7.——-Example of an interactive session using PACER. 26 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS ENTER FUNCTION NAMES AND CORRESPONDING ARGUMENTS. I. MEAN TONNAGE 2. MEAN STATISTICS FOR TONNAGE UITH 125 ITEM‘S). MIN8 .2‘ MAXI 570.34 MEANI 3i.24 ROOT MEAN SQ.‘6.#0E*03 SUM! 3904.83 SUM OF SOUARESI 7.996¢005 STD. DEV.! 73.923 VARIANCE! 5A66.6 ENTER COMMANDS COND A. RANK 8E BIT! HV BIT C 2. RANK BE SUBBIT! SUBBIT C O ENTER COMMANDS LOGIC ENTER LOGIC! A EN ER COMM ND! SEAR H EN ER INPU FILE NAM 8 RYAMPA ENTER OUTPUT FILE NAME: BITYAM ALL 125 RECORDS OF RYAMPA SEARCHED. 77 RECORDS FOUND WHICH SATISFY THE REQUEST. THEY HAVE BEEN STORED IN BITYAM SRU'SII.¢ BITYAM FUNCAEINS AVAILABLE AT THIS TIME ARE! ENTER FMEiNITUNNREES AND CORRESPONDING ARGUMENTS. 2. MEAN STATISTICS FOR TONNAGE WITH 77 ITEMS(S). MIN! .30 MAXI 570.34, MEANS 35.31 ROOT MEAN SQ.“ 7.48E‘03 SUMI 2718.72 SUM OF SQUARES! 5.7620005 STD. DEV.‘ 79.#90 VARIANCEI 6318.7 ENTER COMMAND! LOGIC ENTER LOGIC: 8 FIGURE 7.——Example of an interactive session using PACER—Continued PROGRAMMER’S REFERENCE 27 ENTER COMMAND! SEARCH ENTER INPUT FILE NAME! RYAMPA ENTER OUTPUT FILE NAME: SUBYAM ALL 125 RECORDS OF RYAMPA SEARCHED. 58 RECORDS FOUND WHICH SATISFY THE REQUEST. THEY HAVE BEEN STORED IN SUBYAM SRU'S:1.3 ENTER COMMANDS FUNC ENTER NAME OF FILE: SUBYAM FUNCTIONS AVAILABLE AT THIS TIME ARE! MEAN FIT ENTER FUNCTION NAMES AND CORRESPONDING ARGUMENTS. I. MEAN TONNAGE 2o MEAN STATISTICS FOR TONNAGE WITH 48 ITEM(S)¢ MIN' .24 MAX! A48oA9 MEAN: 24.71 ROOT MEAN $0.8 4.65E¢03 SUMI 1186.11 SUM OF SQUARES: 2.234‘005 STD. DEVO‘ 64.257 VARIANCE! ‘129.0 SRU'817ol ENTER COMMAND! FILE ENTER DATA BASE NAMES USALYT N R E.“ STRTEAES'COESRRDO B. FIELD E0 TAMPA Ca TWNSHIP BE 5’6 0. N5 E0 N E. RANGE BE 89990 F. E" E0 H ENTER COMMAND! LOGIC ENTER LOGIC: A*B*C*D*E*F ENTER COMMAND! SEARCH ENTER INPUT FILE NAME; USALYT ENTER OUTPUT FILE NAME: AYAMPA ALL 666 RECORDS or USALYT SEARCHED. 62 RECORDS FOUND HHICH SATISFY THE REQUEST. THEV HAVE BEEN STORED IN AYAHPA FIGURE 7.—Examnle of an intprnr-fivn anuuinn “chan- ‘DA ("F‘D nnmumua 28 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS SRU'S:T.1 ENTER COMMAND! COND A. RANK BE BITOHV BIT C B. RANK BE SUBBITOSUBBIT C C. ENTER COMMAND! LOGIC ENTER LOGIC! A ENTER COMMAND! SEARCH ENTER INPUT FILE NAME? AYAMPA ENTER OUTPUT FILE NAME! ABTYAM ALL 62 RECORDS OF AYAHPA SEARCHED. 59 RECORDS FOUND HHICH SATISFY THE REQUEST. THEY HAVE BEEN STORED IN ABTYAM SRU'581.2 ENTER COMMANDS FUNC ENTER NAME OF FILE! ABTYAN FUNCTIONS AVAILABLE AT THIS TIME ARE: MEAN 'FIT ENTER FUNCTION NAMES AND CORRESPONDING ARGUMENTS. I. MEAN SULFUR! ASH! BTU Z. MEAN STATISTICS FOR SULFUR WITH 50 ITEMTS). MIN. .39 MAX. 3060 MEAN'* .71 ROOT MERN SQO. 080 SUN! 35.50 SUM OF SQUARESa S909 STD. DEV.s .SATBZ VARIANCEI .30010 MEAN STATISTICS FOR ASH WITH 59 ITEM‘S). MINI 2.79 MAXI 26.90 MEANg 3.11 ROOT MEAN SO.‘ 85. SUMs 405.60 SUM OF SQUARESa ‘.257*003 STD. DEV.8 4.4‘10 VARIANCE: 19.722 MEAN STATISTICS FOR BTU WITH 50 ITEM(S). MIN: 8390.00 MAX: 11920.00 MEAN! 11080.29 R001 MEAN su.-1.23:+08 SUM‘ 554010.00 SUM OF SQUARESa 6.1566009 STD. DEV.g 603.16 VARIANCE3 3.63198E‘05 ENTER COMMAND: LOGIC ENTER LOGIC! 8 FIGURE 7.—Examp1e of an interactive session using PACER—Continued PROGRAMMER’S REFERENCE 29 ENTER COMMANDS SEARCH ENTER INPUT FILE NAME! AYAMPA ENTER OUTPUT FILE NAME! ASBYAM ALL 62 RECORDS OF AYAMPA SEARCHED. 12 RECORDS FOUND WHICH SATISFY THE REQUEST. THEY HAVE BEEN STORED IN ASBYAM SRU'Sio7 ENTER COMMAND! FUNC ENTER NAME 0? FILE! ASBYAM FUNCTIONS AVAILABLE AT THIS TIME ARE! MEAN FIT ENTER FUNCTION NAMES AND CORRESPONDING ARGUMENTS. . MEAN SULFUR. ASH! BTU MEAN STATISTICS FOR SULFUR WITH 12 ITEM(S). MIN’ .30 MAX3 1.20 MEANI .63 ROOT MEAN 50.! .66 SUMI 7.60 SUM OF SQUARES! 5.53 STD. DEV.‘ .26‘00 VARIANCE. 6.96970E~02 MEAN STATISTICS FOR ASH WITH 12 ITEM($). MINI 3.20 MAX! 7.50 MEAN. 0.6A ROOT MEAN $0.: 23. SUM! 55.70 SUM OF SQUARES! 273. STD. DEV.‘ 1.1357 VARIANCES 1.2899 MEAN STATISTICS FOR BTU NITH 12 ITEMTS). MINI 9730.00 MAXI 11290.00 MEAN! 1056¢.17 ROOT MEAN $0.! 1.12E008 SUMI 126770.00 SUM OF SQUARES! 1.3410009 STD. 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Geological Survey usage. APPENDIX A A.6.—List of names in the BED dictionary 1—Continued CARBONERA CARBONERO CASS CASTLEGATE A CAVANAL CAVANAUGH NUMBER 2 CEDAR CREEK No 1 CEDAR CREEK N0 2 CEDAR CREEK No 3 CEDAR MTN N0 1 CEDAR MTN NO 2 CHANDLER CHAFFIN CHARLESTON CHERRY CREEK CHESTERFIELD CHRISTENSEN zONE CIRUELA CLIFFLAND COAL No COAL No COAL NO COAL No COAL ND COAL No COAL N0 COAL No COKEDALE COLUMBUS COMO COLBORN COTTDNHOOD CRDCKER CROMEDURG D D AND F 0 BD DALE NUMBER 4 DALE NUMBER 7 DALTON DAWSON DE DELAGUA NO 1 DIETI No 1 DISCOVERY mqomawmw DOLLY VARDEN DRY CREEK DURHAM NUMBER 2 DUTCH E E 80 EIGHT FOOT ELK NUMBER 1 ELK NUMBER 2 ELMO EMERY COAL ZONE EMPIRE ERAM EUREKA F F 80 FELIX FERRON COAL ZONE FF 1 FF 10 FF 11 FF 12 FF 13 FF 14 FF 15 FF 16 FF 17 FF 18 FF 19 FF 2 FF 20 FF 21 FF 22 FF 23 FF 24 FF 3 FF 4 FF 5 FF 6 PF 7 FF 8 FF 9 FF GROUP FIRESTEEL FISH CREEK 1 The shrati r ' - ' ‘ 8 Bphlc nomenclature used m thus report is fromgmsny sources and may not necessarily follow U.S. Geological Survey usage. 45 46 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS A.6.—List of names in the BED dictionary 1——Con1:inued FLEMING FLORESTA FRANKLIN NUMBER 10 FRAZIER FREDERICK FRONTIER BED 1 FRONTIER BED 2 FRONTIER BED 3 FRONTIER BED 4 FRONTIER COAL ZONE FULTON NUMBER 12 G GEM GILSON GLACIER GOFF 1 GOFF Io GOFF 11 GOFF 12 GOFF 13 GOFF 14 GOFF 15 GOFF 16 GOFF 17 GOFF 18 GOFF 19 GOFF 2 GOFF 20 GOFF 21 GOFF 22 GOFF 3 GOFF 4 GOFF 5 GOFF 6 GOFF 7 GOFF 8 GOFF 9 GOLDEN GLow GREEN NUMBER 7 HARRIS HARTSHORNE HASTIE HASTIE PLUS HASTINGS HEALY HENDtRSON COAL ZONE HENDERSON ZONE HENRYETTA HIARATHA IVIE UEFF HILL JOHN HENRY MEMBER JONES K BED KEBLER NO 2 NENILNORTH KEYSTONE KUMMER NUMBER 0 KUMMER NUMBER 1 KUMMER NUMBER 4 L BED LADD NUMBER 2 LADD NUMBER 3 LADD NUMBER 4 LADDSDALE LAKE wHATCOM LANDSBURG NO 1 LAY SECTION LEAVELL LENNox LENox LEXINGTON LION CANYON 1 LION CANYON 10 LION CANYON 11 LION CANYON 12 LION CANYON 13 LION CANYON 14 LION CANYON 15 LION CANYON 16 LION CANYON 17 LION CANYON 18 LION CANYON 19 LION CANYON 2 LION CANYON 20 LION CANYON 21 LION CANYON 22 LION CANYON 23 LION CANYON 24 LION CANYON 3 LION CANYON 4 LION CANYON 5 1The sh‘atlgraphic nomenclature used in this report is from,many sources and may not necessarily follow U.S. Geological Survey usage. APPENDIX A 47 A.6.—List of names in the BED dictionary 1—Con’cinued LION CANYON LION CANYON LION CANYON LION CANYON LION CANYON LION CANYON LION CANYON LION CANYON LITTLE DIRTY LONSDALE LOW CARBONERA LOW GROUP A BED LOW GROUP 8 BED LOW GROUP C BED LOW GROUP D BED LOW GROUP E BED LOW HOLGATE LOWER LOWER ALAMO LOWER BUNKER HILL LOWER CAMERON LOWER COAL FORD COAL LOWER COAL ZONE LOWER CULVER ZONE LOWER DIRTY LOWER GROUP LOWER HARTSHORNE LOWER LUDLOW LOWER MEMBER LOWER MEMBER RATON LOWER MESAVERDE LOWER MYSTIC LOWER PIEDMONT LOWER ROBINSON LOWER RUGBY LOWER SOPRIS LOWER STARKVILLE LOWER SUNNYSIDE LOWER THOMPSON LOWER WITTEVILLE LOWER ZONE 0RD AREA LOWTHIRWF LUCAS CREEK MAJESTIC MAMMOTH onmpomflo l'l'he stratigraphic nomenclature used in this report is from many sources and may MANBECK MARTINEI MAY CREEK MC ALESTER MCKAY MCNEILL MESAVERDE COAL ZONE MEXICAN CREEK MENDOTA MID CARBONERA MID GROUP F ZONE MID GROUP G ZONE MID GROUP H ZONE MID GROUP J BED MID HOLGATE MIDDLE MIDDLE GROUP MIDDLE MEMBER MIDDLE MEMBER RATON MIDDLE MESAVERDE MIDWF MINERAL MITCHELL MINE MONAHAN MONTERVILLE MONUMENT PEAK MORGAN NUMBER 7 MORLEY MORRIS MUDDY NO 1 MUDDY NO 2 MUDDY NOS 1 AND 2 MULBERRY MOLDOON MULKY MURRAY MUTUAL MYSTIC N BED NEW LAKE HOUNGS N0 2 NEW ROUSE NEWCASTLE NEWENHAM NISQUALLY NO 1 not necessarily follow U.S. Geological Survey usage. 48 l The st: PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS N0 1 BED NO 2 N0 2 BED N0 3 NO 3 AND 4 NO 3 BED A.6.—List of names in the BED dictionary 1—Continued NAVY NUMBER 4 NAVY NUMBER 6 NO 4 NO 5 NO 6 N0 7 NODAWAY NONAC NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER 10 NUMBER 11 NUMBER 12 NUMBER 2 5 NUMBER 4 5 NUMBER 7 NUMBER 8 0 BED OCCIDENTAL OCCIDENTAL OCCIDENTAL OCCIDENTAL OCCIDENTAL OCCIDENTAL OCEAN WAVE OTTAWA P BED PALISADE PARIS (”UT-#000)“ N0 N0 N0 N0 N0 PENITENTIARY PIEDMONT PLACITA PLANT NUMBER 6 PLANT NUMBER 7 PDCAHONTAS HO‘UNH PRETIY PRIMERO PROGRESSIVE PRYOR O BED R BED RADIANT RAINeow RAPSON RAVENSDALE NO 3 RAVENSDALE NO 4 RAVENSDALE NO 5 RAVENSDALE No 9 RED ASH REES COAL ZONE RIACH RIDER ROCK CANYON ROCKVALE ROLAND ROSLYN NUMBER 5 RDwE ROYAL OORGE RYAN NUMBER 1 5 BED SAN PEDRO SANTO TOMAS SCHUMAN SCOTT SECOR SENIOR SHOO FLY SIBLEY SILVER LAKE 51x FOOT SLIDE HOLLOu SMIRL COAL ZONE SMITH SMOKY HOLLOW MEMBER SNELL SOPRIS SPRINGBROOK STIGLER STRAIGHT CLIFFS ZONE SUDDUTH 'atigraphic nomenclature used in this report is from many sources and may not necessarily follow U.S. Geological Survey usage. APPENDIX A 49 A.6.—List of names in the BED dictionary 1—Continued SUMMIT SUNBEAM SUNDAY CREEK SUNNYSIDE SUNSET NUMBER 1 SUNSET NUMBER 2 SUNSET NUMBER 7 TANK TAHLOR MINE TEBO THAYER THOMAS THURBER THREE PINES TYSON TIMAR TM GROUP TONO NUMBER 1 TONO NUMBER 2 TOPWF TROPIC DAK INTERVAL UCROSS ULM N0 2 UNCORRELATED UP CARBONERA UP HOLGATE UPPER UPPER ALAMO UPPER AND LOWER UPPER BEAR CANYON UPPER BUNKER HILL UPPER CAMERON UPPER CULVER ZONE UPPER HARTSHORNE UPPER HIAWATHA UPPER IVIE UPPER LUDLOW UPPER MEMBER UPPER MEMBER RAToN UPPER MESAVERDE UPPER PART UPPER ROBINSON llThe stratigraphic nomenclature used in this report is from many sou UPPER RUGBY UPPER STARKVILLE UPPER SUNNYSIDE UPPER THOMPSON VICTORY wADGE WALKER NALL WALSEN MALTERS WASATCH wATTIS WEIR PITTSBURG wHEELER MHITEBREAST WILEY WILKPSON NUMBER WILKESON NUMBER NILKESON NUMBER wILKESON NUMBER WILKESON NUMBER WILKESON NUMBER WILLIAMSBURG WINCHESTER MOLF CREEK NRIGHT NUMBER 8 BEULAH ZAP COTEAU DUNN CENTER FHYBURG HANKS HAYNES HARMON MANHAVEN MIDDLE WILLISTON NOONAN SCRANTUN MEDORA T-CROSS UPPER NILLISTON WILLISTON MILTON “07¢me rces and may not necessarily follow U.S. Geological Survey usage. PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS A.7.—List of quadrangle names in the QUAD dictionary ACOBD LAKES NE DD ACORD LAKEs Nu OD ACORD LAKES SE OD ACORO LAKES sw OD ALTON BALD KNOLL BRYCE POINT CAINEVILLE CANAAN CR OD CARCASS CANYON QD CASTLE DALE NE QD CASTLE DALE Nw OD CASTLE DALE sw OD CASTLEGATE KHUNE ODS CASTLEGATE MATTS SUMMIT DDS CEDAR MOUNTAIN CLIFF RIDGE OD COAL CR T0 ORDERVILLE CANYON COAL CREEK COALVILLE OD COLLET TOP OD cow FLAT CURRANT CR DAVE CANYON OD DEATH RIDGE OD DONKEY FLAT GD DRY FORK VERNAL NW ODS EAST OF NAVAJO QD EMERY EAST EMERY THREE NE EMERY THREE NW EMERY THREE SE EMERY THREE SN FACTORY BUTTE NW FERRON CANYON QD FLAGSTAFF PEAK OD FLOY CANYON SE SW GRIFFIN POINT OD GUNSIGHT BUTTE NE GUNSIGHT BUTTE NW HENRIEVILLE QD HIAWATHA NE OD HIAWATHA NW 00 HIAWATHA SE 00 HIAWATHA SH OD KOLOB PK ORDERVILLE CANYON N LAKE MOUNTAIN OD LOST CREEK MESA BUTTE MOUNT ELLEN NW SW MOUNT PENNELL NW NE MT PLEASANT HUNTINGTON RES NAPLES OD NEEDLE EYE POINT OD NIPPLE BUTTE NE NIPPLE BUTTE SE NOTOM NE SE ORDERVILLE CANYON NE ORDERVILLE CANYON SE ORDERVILLE NE SE ORDERVILLE SW PAGE RANCH STODDARD MOUNTAI PARIA NW PETES COVE OD PINE LAKE 00 RAINBOW POINT RASBERRY KNOLL RASMUSSEN HOLLOW 00 ROCK CREEK SALINA CANYON SCOFIELD NE 00 SCOFIELD NW OD SCOFIELD SE QD SCOFIELD SW OD SEEP FLAT SEGO CANYON SE SE60 CANYON SW SHIP MOUNTAIN POINT OD SKUTUMPAH CREEK PODUNK CREEK SLICK ROCK BENCH-BUTLER VALL SNAKE JOHN REEF OD SOLDIER SUMMIT SE OD STEINAKER RES VERNAL NE ODS STERLING SUNNYSIDE NW OD SUNNYSIDE SE 00 SUNNYSIDE SN 00 TABBY MTN TABIONA OD TROPIC CANYON QD UPPER VALLEY OD WAGON t"OG MESA NE CAVE POINT WALES WELLINGTON MINNIE MAUD W 00 WELLNGTN NE MINNIE MAUD CR E NESTWATER CR N WOODSIDE NE 00 WOOOSIDE SE 00 A.8.-—List of publications in SOURCE dictionary ALTON OPEN FILE PEPT ARIZONA BOM BULL 182 BOOK CLIFFS OPENFILE BULL 70 ses KANSAS BVILLE STRIP REPT COAL RESERVES OF WA COAL RESOURCES IOWA COALVILLE TABBY SEeO EMERY OPEN FILE REPT HENERY MTN COAL FIELD IDAHO MceEOL PHAM 92 KAIPAROWITS OPENFILE KOLOB HARMONY EIELOS LANDIS OPEN FILE MIN L HOH RES OF ARI MISSOURI 65 RI N048 NMBMMR MEMOIR 25 OKLA es TBL 40 To 58 SEVIER GOOSE LOST OF TEX B ECON GEO RI so THE COMPASS SIGGAMEP uses BULL 1042 J uses BULL 1042 O uses BULL 1050 uses BULL 1051 uses BULL 1072 c uses BULL 1072 6 APPENDIX A U565 U565 U565 U565 U565 U565 U565 U563 U565 U565 U565 U565 U565 U363 U565 U565 UTAH UTAH 51 BULL 1072? BULL 1078 BULL 12420 BULL 9828 BULLETIN 12423 CIRCULAR 159 CIRCULAR 226 CIRCULAR S3 CIRCULAR 81 CIRCULAR 89 MAP C 20 MAP C 26 MAP C 4 MAP OM 109 MAP CM 138 MAP OM 149 MONO SERIES 1 MONO SERIES 2 VERNAL OPEN FILE RPT WASATCH OPENFILE RPT NDGS BULL 4 NDU DIV MIN CIRC 2 NDU DIV MIN CIRC 5 NDU DIV MIN CIRC 8 NDU DIV MIN CIRC 11 USBM IECH PAPER 700 52 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS APPENDIX B, PROGRAM LISTINGS OF MODIFIED GRASP ROUTINES SUBROUTINE HELP(WORDS) INTEGER WORDS(13) REAL*8 TEXT(11913) DATA TEXT/% " INITIA'a'TES THE '9'REQUEST 'O'FOR RETR'o'IEVAL CR'v'ITERIA T'fi 9'0 BE ENT'Q'ERED IN '9'THE FORM'9'3 NAME R'y'EL VALUE'9$ " INITIA'9'TES THE 'O'REQUEST 'Q'FOR A LO'Q'GICAL EX'q'PHESSION'fi 0' TO BE E'o'NTERED'p'USING LO'o'GICAL 0P'9'ERATORS.09% " INITIA'Q'TES THE '9'SEARCH 0'9'F A FILE'O' BASED U'v'PUN PREV!» 9'IOUSLY E'a'NTERED'9LCONDITIO'9'NS AND L'0'OGIC.'0% " ALLOWS'Q' THE USE'o‘R TO LIS'Q'T SELECT'v'ED VALUE'O.S (VARIA’fi o'BLE NAME'o'S WILL'o'BE ASKED'o' FOR) IN',' A fILE.'¢% " ALLOWS'D' THE USE'Q'R TO SEL't'ECT OR C'v'HANGE TH'v'E DATA 8" 9'ASE TO B'4'E USEDo'93*' '9% '- TERMIN'o'ATES THE'!’ SYSTEM.'9' ENTERIN'Q‘G 1 IN R'o'EhPONSE '* Q’TO A PRU'g'MPT WILL'Q'ALSO STO'I‘P THE SY'Q'SIEMo'Q% '— USED T','O PRINT'9'ITEM NAM'O'ESO THEI'Q'R TYPES'O'AND DEFI'9% 'NITIONS'Q'IN A'Q'SELECTED'9' SET OF'o'GROUPS.'o$ '- USED T'Q'O OBTAIN'O' THE ABO'D'VE COMMA'o'ND DEFIN'9'ITIONS.'9% 5*. Q,% '- LISTS'Q'THE FILE'v'S WHICH'v'HAVE BEE'v'N USED A'o'S WELL A'!% '5 THE CO'o'NDITIONS'o'AND LOGI'O'C ENTERE',0D.'9% '- PRINTS'!‘ ALL ITE'o'MS PRESE'v'NT FOR E'c'ACH KECO'o'RU IN A'o% 'SELECTED'Q' FILEo'o'NAITS AF'O'TER EACH'D' N LINES'9% '- PROVID'Q'ES FOR T'Q'HE COMPU'Q'TATION 0'9'F FUNCTI'9% 'ONS 0N I'9'TEMS IN.!'A DATA'a'SET (OR'v'FILE).'9% v '9% '- COMBIN'Q'ES THE C'a'ONTENTS '9'0F SEVER'4'AL SELEC'9% 'TED SUBF'9'ILES INT"'0 A 'Q'SINGLE S'Q‘UBFILEO 'O% I u,% '- PERMIT'Q'S THE SE'v'LECTION 'o'OF SPECI'v'ALLY SOR'9% 'TED AND '9'FORMATTE'9'ED 'v'TABULAR 'Q'OUTPUT D'o% 'ISPLAYS.'/ PRINT 5019(W0RDS(J)9(TEXT(IQJ)oI=1911)9J=1913) 501 FORMAT('0THE COMMANDS WHICH MAY BE ISSUED '9% '(AND THEIR MEANING) ARE LISTED BELOW:'///% ('0'4A498A8/7X93A811 PRINT 1001 1001 FORMAT(' UPDA' PERMITS THE ADDITION! THE DELETION! OR THE'% ’ MODIFICATION OF RECORDS'/' 0R PORTIONS 0F RECURDS'% ' BELONGING TO THE MASTER FILE.'//) RETURN END 4100 4101 4102 4103 4104 4105 4106 4107 4108 4109 4110 4111 4112 4113 4114 4115 4116 4117 4118 4119 4120 4121 4122 4123 4124 4125 4126 4127 4123 4129 4130 4131 4132 4133 4134 4135 4136 4137 4138 4139 4140 4141 4142 4143 4144 4145 4146 4147 4148 4149 4150 4151 4152 APPENDIX B 53 SUBROUTINE C0LPNT(NPAGE9*) DOUBLE PRECISION DBLNKoAREAoLINE1201,NAMESsLABEL.% VNAMES(20)cBUFFER‘lSoZO),FMT(3)9FMTS(8)OONAME LOGICAL DISK COMMON NAMESleYPEoPNTSoIDIM COMMON /EXPRNS/ POLISHoICODEoLPS INTEGER PNTST400).HLANK.TANK.USED(201 DIMENSION ITYPE(4OO)vBITEM<15925)91TEMS(20)oLASTDX(15920)gfi IREC‘400}!REC(4OO)9NAMES<4OO>9TANK(3Q)9LABEL(25)9LIST(25)O$ POLISH(1598)oICODE(1598)9LPS(8)oEQUATE(5) EOUIVALENCE (REC(1)9IREC(1))o(IVALoVAL).(TANKC119AREA) DATA NDICT9NBIN9NFILE/999!ll/oBLANKyDBLNK/' '9' 0/ DATA FMTcFMTS/'('9' '9')'0'F8.6'0'F8.5'0'FB.4'0% 'F8.3's'F8.2'9'F8.1‘9'F8.0'9'1PE8.1'/ DATA EQUATE/‘EQUA'vaE 1'9'5'92*' 0/ INTEGER SPACE(31871 COMMON ISCRTCH/ SPACE EQUIVALENCE (SPACE(1)CBUFFER)9(SPACE(691)’LASTDX)9$ (SPACE(901)0BITEM)9(EOUATE(4)9ONAME) KOUNT=O DO 1 K=1920 USED(K)=O DO 1 I=1415 1 LASTOX(IvK)=-999999 46 PRINT 50 50 FORMAT(' ITEMS MAY BE PRESENTED IN A SORTED ORDER.I) READ(59519PROMPT='ENTER 1 FOR A SORT. 0 OTHERWISE.: 'oEND=995)% ISORT 51 FORMAT(II) PRINT b3 59 FORMAT(' THIS LIST CAN BE DIRECTED TO'/% 0 YOUR TERMINAL OR TO A SYSTEM DISK.'/% ' ENTER 1 FOR FORMATTED DISK ONLl: OTHERHISE ENTER 0') READ(5951¢END=995) I DISK=I.NE.0 IF(.NOT.DISK) GO TO 49 IF(ISORT.NE.1) GO To 48 PRINT 47 47 FORMAT(' GRASP IS UNABLE TO SORT OUTPUT 'o% 'DIRECTED TO A DISK. REENTER YOUR CHOICE.') GO TO 46 48 READ(59549PR0MPT='ENTER NAME OF DISK FILE: '9% END=99S) ONAME 54 FORMAT¢A61 CALL OBEY(EQUATE95) 49 CALL VLIST(VNAMESoITEMSoNUMoC990) IF(NUM.EQ.O) GO TO 995 NUM=MIN0(NUM.2O) CALL OBEvt'USAGE4CORY143) IF 60 T0 998 GO TO 801 2 DO 800 JJ=19NUM AREA=DBLNK II=ITEMS(JJ) IF(II.GT.0) GO TO 9 II=-II VAL=EVAL(IRECoICODE(laII)oP0LISH(1911)oLPS(II)9&800) GO TO 20 9 IVAL=IREC(II) IF 10...DATA CONSISTS OF A DICTIONARY 117 S POINTER TO REFERENCE A LDOKUP IN THE 118 S (ITYPE - 10)TH DICTIONARY. 119 S NREC = NUMBER OF RECORDS REVIEVED IN THE SELECTED SUBFILE. 120 S KDIC = INDEX TO IDENTIFY THE MASTER FILE BEING USED AND To 121 S LOCATE THE PROPER MAXREC VALUE FROM THE DICTIONARY 122 S FILE. 123 S IMAGE = INTEGER REPRESENTATION 0F MASTER DATA 124 S ELEMENTS. INCLUDING INTEGER DATA AND 125 S DICTIONARY POINTERS. 126 S OIMAGE a REAL REPRESENTATION OF MASTER DATA ELEMENTS 127 S THROUGH EOUIVALENCE VITH TIMAGE.' 128 S NSTRNG = INTEGER REPRESENTATION OF THE DATA STRING FOR 129 S ALL DATA ELEMENTS (INTEGER S ALPHANUMERICT 130 S BELONGING To A MASTER RECORD. 131 S STRING a REAL REPRESENTATION (THROUGH EQUIVALENCE 132 S STATEMENT) OF THE DATA SIRING FOR ALL REAL- 133 S VALUED DATA ELEMENTS BELONGING TO A 134 S MASTER RECORD. 135 S NAME = ARRAY (UP TO 7 COMPUTER HORDST OF NEH ALPHA- 136 S NUMERIC DATA FOR COMPARISON wITH EXISTING 137 S DICTIONARY ENTRIES To 1) DETERMINE DICT- 138 S IDNARY POINTER OR 2) TO DETERMINE THAT A 139 S DICTIONARY ENTRY DOES NOT EXIST FOR THE 140 S GIVEN DICTIONARY CATEGORY. 141 S LT = NUMBER OF NORDS (LESS THAN OR EQUAL To 71 142 S NEEDED To STORE THE ALPHANUMERIC ENTRY IN 143 S "NAME." 144 S KMORD = AN ARRAY SPECIFYING THE MAXIMUM NUMBER OF 145 S COMPUTER NORDS RESERVED FOR EACH RAW DATA 145 S ELEMENT. 147 S NwOROS = THE TOTAL MAXIMUM NUMBER OF COMPUTER NORDS 143 S NEEDED TO STORE RAH DATA FOR THE IST THROUGH 149 S THE I-TH DATA ELEMENTS. 150 S KBEGIN = THE ToTAL MAXIMUM NUMBER OF MORDS NEEDED To 151 S STORE RAW DATA FOR THE IST THROUGH THE 152 S (I-l)TH DATA ELEMENTS. 70 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 $$$$$$$$$Pfi$afi$$$afi 1009 1 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS KEND = THE MAXIMUM NUMBER OF HORDS NEEDED TO STORE THE I-TH DATA ELEMENT. THIS UNSUBSCHIPTED VARIABLE Is EQUIVALENT TO KMORDTI). NDIC = DICTIONARY CATEGORY REFERENCE NUMBER. NUM = TOTAL NUMBER OF DICTIONARY ENTRIES IN THE "NDIC" DICTIONARY CATEGORY. MAXREC = MAXIMUM RECORD KEY IN THE MASTER FILE. KEYR = KEY NUMBER FOR RECORDS To BE ADDED FOLLOMING THE LAST RECORD ("MAXREC") IN THE MASTER FILE. KwT = TOTAL OF ALL "NELEM" "KMORDNS. ALFIN = DUMMY ARRAY To DESIGNATE INPUT FILE NAME. ALFOUT = DUMMY ARRAY To DESIGNATE NAME OF TRANSLATED FILE To BE POSTED To THE MASTER FILE. QQIN = DUMMY ARRAY To BE ENCODED INTO "ALFIN." OOOUT = DUMMY ARRAY To BE ENCODED INTO "ALFOUT." DIMENSION IMAGE(400)9 NSTRNGTAOO). i ITYPE(400)9 QIMAGE<400); STRINGTAOO). S KNORDT4DO). NAMETT). VLISTT400). S ALFIN(5)9 ALFOUTTS). OOINTS). A QQOUT(5)’ NODATA(4) DOUBLE PRECISION VLIST COMMON NAMED(800)yITYPEvPAD<401)oVLiSToNELEM COMMON /LOG/ MONTH.IDAY.IYEAR.ILOG.MAxREC.KMORD.KDIC.IRITE EQUIVALENCE TIMAGE.OIMAGE)9TNSTRNG.STRING) DATA IBLANK9QBLANK9YE59XNOI' v.' 'o'YES'o'NO'l DATA OOIN/TEOUA'o'TE '.v31 i/.OOOUT/oEOUA'.vTE '.v21 ., DATA QUIT/'QUIT'/ DATA NODATAI'NO Dv.'ATA 'c'ENTE'o'RED 0/ IF(IRITE .EO. 23) GO To I HRITE(691009) FORMAT(/' THE ADD RECORD PROCEDURE IS DESIGNED TO READ A' % - RAw DATA INPUT FILE AND CONVERT'I' THE RECORDS TO TfiE' % RECORD STRUCTURE THAT Is COMPATIBLE wITH THE MASTER FILEv/S OF "PACER." CHECKING FOR CORRECT DICTIONARY ENTRIES; AND' % PROMPTING THE DATAjl' MANAGER To REQUEST ADDITION OF THE' % NONMATCHING DICTIONARY ENTRIES TO THE'/' DICTIONARY LIST! % OR TO CORRECT THE INPUT ENTRY so THAT IT MATCHES A VALUE'/% ALREADY IN THE DICTIONARY LIST.'//' IF THE INPUT FILE DOEsv» NOT CONTAIN RAH DATA. THE DATA MANAGER CAN EXIT THISg/ % REVISION PROCEDURE To SELECT A DIFFERENT PROCEDURE (3-5)v % v BY ENTERING "OUIT."v/v MHEN PROMPTED FOR A FILE NAME.'// ) READ(5910029PROMPT='NAME 0F RAW DATA INPUTS FILES ') QQIN(4)DQQIN(5) FOR 1003 IF(QQIN(4) oEQ. QUIT) GO TO 999 READ(5910029PROMPT='NAME 0F TRANSLATED FILE% POSTING TO MASTER FILE: ') QQOUT(4)QQQOUT(5) IF(QQOUT(4) .EQ. QUIT) GO TO 999 001 = QQOUT(4) 092 = QQOUT(5) FORMAT(A492A39A49A2) ENCODE(ALFIN910039ERR=9981 QQIN ENCODE(ALFOUTOIOO39ERR=998) QQOUT CALL OBEY(ALF1N94) 207 203 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 253 259 260 101 100 % % % 10 H U" H 0‘ Nzfififi O weflafieflzfizfizflzfiafi 40 91 50 51 APPENDIX C CALL OBEY(ALFOUT94) KEYR = MAXREC KWT = 0 DO 2 1=19NELEM KWT = KWT 0 KNORD(I) WRITE(691011) 1 FORMAT(/' DO YOU WISH TO DISPLAY EACH RECORD IN THE 't 'INPUT FILE ON THE TERMINAL?') READ(5910019PR0MPT='"YES" OR "NO"! !) REVIZ IF((REVIZ .NE. YES) oANDo (REVIZ .NE. XNO)) GO TO 5 NREC = 0 NHORDS = 0 IF(KDIC IEQQ 1) CALL REDUSC(NSTRNGDSTRINGOKEYR95999) IF(KDIC 4E0. 2) CALL REDUSA(NSTRNGDSTRINGDKEYPD$999) IF(KDIC CEO. 3) CALL REDUSC‘NSTRNGQSTRINGOKEYP!$999) NREC = NREC + 1 DO 99 I=19NELEM NWORDS = NWORDS 9 KHORD(I) IF(ITYPE(I) - 2) 10920930 LOAD INTEGER DATA INTO THE "PACER" RECORD FORMAT. IMAGE(I) = NSTRNG(NWORD$) IF (KDIC .NE. 1) GO TO 15 IF(I 4E0. 26 oAND. IMAGE(26) .EQ. 0) IMAGE(26) = ILOG IF(KDIC .NEo 2) GO TO 16 IF(1 .EQ. 23 oAND. IMAGE(Z3) .EQ. 0) IMAGE(23) = ILOG IF(KDIC .NE. 3) GO '0 99 IF(I .EQ. 26 OANDO IMAGE(26) .EQ. 0) IMAGE(26) = ILOG GO TO 99 LOAD REAL DATA INTO THE "PACER" RECORD FORMAT. OIMAGE(I) = STRING(NHORDS) GO TO 99 CHECK ALPHANUMERIC ENTRIES FOR DICTIONARY CONSISTENCY. IF ENTRY DOES NOT APPEAR IN THE DICTIONARY...CHECK wITH THE DATA MANAGER TO DETERMINE IF IT IS INTENDED THAT THE ENTRY BE ADDED To THE DICTIONARY. THEN. COMPUTE THE DICTIONARY POINTERs AND LOAD THE DATA INTO THE "PACER" RECORD FORMAT. KEND = KWOR011) KBEGIN = NWORDS - KWORD1I) KPl = KBEGIN + 1 IF11 DEQO 5 oANDo NSTRNG(KP11 DEG. IBLANK) NSTRNG(KPL) IF(I oEQo 7 oANDo NSTRNG(K91) 6E0. IBLANK) NSTRNG(KP1) DO 41 K=197 NAME(K) = IBLANK LT = 9 DO 51 K=19KEND NAME(K) = NSTRNG(KBEGIN 4 K) IF(NAME(K) .NE. IBLANK) LT = LT * 1 71 3 9-. = 'C' 72 PACER—JRATA ENTRY,RETRLEVAL,AND UPDATE FOR NCRDS 261 IFéLT .NE. 0) GO To 54 262 00 52 K=194 263 52 NAME(K) = NODATAtK) 264 LT = 4 265 DO 53 K=19KEND 266 53 NSTRNG(KBEGIN¢K) = NAME(K) 267 54 NDIC = ITYPEtI) - 10 268 CALL MATCH(NAME!NDICQLTOMKFYONUM9$9949$995) 269 IMAGE(I) = MKEY - NDIC*10000 270 GO TO 99 271 994 WRITE(692001) VLIST(I)9NAME 272 2001 FORMAT(/' THERE IS NO DICTIONARY MATCH FOR DATA NAME: '% 273 9A7/' ALPHANUMERIC DATA: '37A4/% 274 ' DO YOU WISH TO ENTER THIS DATA IN THE DICTIONARY?’) 275 55 READ(5910019PROMPT='"YES" OR ”NO": '5 TEST 276 1001 FORMAT(A4) 277 IF((TEST .NE. YES) .AND. (TEST .NE. XNO)) 60 IO 55 278 IF(TEST oNEo YES) GO TO 60 279 NUM = NUM + 1 280 CALL ADDICT(NAME9LT9NDICONUM) 281 IMAGE‘I) = NUM 282 GO TO 99 283 60 WRITE(692002) VLIST(I) 284 2002 FORMAT(/' ENTER DATA VALUE FOR DATA NAME n'gAlv‘"') 285 DO 61 L=197 286 61 NAME(L) = IBLANK 287 READ(5¢10029PROMPT='DATA VALUE: ') NAME 288 1002 FORMAT(7A4) 289 00 62 K=19KEND 290 62 NSTRNG so To 100 NRITE<6.2OOSI FORMAT(/' THE INPUT FILE Is Now READY FOR POSIING 0NTO'/% I THE MASTER FILE. IF YOU WISH TO MAKE FURTHER CHANGES.T/S I To THIS FILE BEFORE IT Is POSTED. SELECT THE SEQUENIIALo'/% . BATCH. 0R KEYED REVISION PROCEDURE AND SPECIFY THE NAME'/% I OF THIS FILE.') REWIND 31 RETURN 1 WRITE(691010) FORMAT(' NAME OF FILE HAS BEEN IMPROPERLY ENTEREO.v> GO To 1 END 74 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS SUBROUTIN E DELREC This subroutine is used for the deletion of the con- tents of a record contained in the master file. A list- ing of subroutine DELREC appears at the end of this discussion. The corresponding record in the reference subfile is deleted in its entirety. The posi- tion of the deleted record, however, is maintained in the master file. A deletion message is inserted in 3 of the alphanumeric data fields, and the ID number is replaced by a coded log number, specifying the date and the identification number of the data manager responsible for the deletion. The COMMON statements contain the same vari- able names as are contained in the COMMON state- ments of subroutine REVISE. The DATA statement (line 170) initializes the variable, IBLANK, to be used for the testing of input. The message providing instructions to the user (lines 172—188) is sup- pressed if IRITE has been previously given the value of 23 (line 171). The master-file index, KDIC, is tested (lines 108—- 194) to determine which master file will be equiva- lenced to file 30 and which “save” file will be equiva- lenced to file 33. Then, both file 30 and file 33 are rewound (lines 195—196) to prepare them to be opened in the update mode by subroutine UPDATE (lines 197—198). The data manager is then prompted to provide the key number for the record to be deleted (lines 199— 200). Key number, KEYR, is tested (line 201) for a negative value which concludes the deletion pro- cedure by transferring execution to statement 999. If the value of KEYR is positive, the record with that key number is read from the master file (line 202) , decoded into the raw data form, and displayed on the output device. The counter for the number of computer words, NWORDS, is set to zero (line 203), and the DO loop (lines 204—224) contains the logic for translating the master record to the raw-data form for display. The DO loop index ranges from 1 to the number of data elements, NELEM, and the ITYPE array is tested to determine the type of each data element. If the data-element type is an integer, control passes to statement 110 (line 206) where the index, in terms of number of computer words, NWORDS, is computed for the position of that element. Then, the integer data is transferred from the I—th master- file element of IMAGE into the NWORDS-th com- puter word of NSTRNG (line 207) with control passing to statement 200, the end of the DO loop. If the data—element type is a real number, control passes from the ITYPE test (line 205) to statement 120 (line 209) where the NWORDS index is then computed for that element. Then, the real data are transferred from the I-th master file element of QIMAGE into the NWORDS position of STRING (line 210). Control then passes to the end of the D0 loop for recycling to the next data-element position. If the data-element type is alphanumeric, control passes from the test of ITYPE (line 205) to state- ment number 130, where the dictionary pointer value is tested for nonblank value (line 212) . If it is blank, the word length of the alphanumeric string, LT, is set to zero (line 213), and the logic then jumps to statement 145 (line 219). If the string is nonblank, control passes to statement 135 (line 215) , where subroutine SCANDC is called to return the value for the alphanumeric string from the dic- tionary entry referenced by the integer value of IMAGE. The dictionary category number is equal to the value of ITYPE minus 10. The LT nonblank words of the alphanumeric string, NAME, which was returned from SCANDC, are then transferred into the appropriate positions of the NSTRNG array (lines 216 and 217). If some of the words at the end of the string are blank (that is, if LT is less than the KWORD value for that data element, line 218), then blanks are substituted into the remaining NSTRING positions reserved for that data element (lines 219-222). The computer word counter, NWORDS, is then incremented by the num- ber of computer words reserved for the next data element (line 223), and the end of the DO loop is reached (line 224). After the DO loop activities have been concluded for all NELEM data elements, the deleted record is displayed in the output format according to the for- mat subroutine determined by the value of the mas- ter-file index, KDIC (lines 225—227) . The deleted record is also written onto the “save” file on file 33. All data elements belonging to the master-file rec- ord are then blanked out (lines 229—230), and a special deletion message is superimposed onto the master-file record (lines 231—240). Parts of the de— letion message are stored in several of the different data-element dictionaries. These data-element posi- tions vary according to the master-file record struc— ture. Therefore, the master-file index, KDIC, must be tested (lines 232—236) to determine the data- element positions for storage of the deletion message. The blanked record containing the deletion infor- mation is then written over its original position on the master file (line 241), and it is deleted in its APPENDIX C 75 entirety from the subfile on file unit 21 (line 242) by means of the INFONET-dependent subroutine DE- LETE. This deletion from the subfile prevents the recreation of the record should the total subfile be posted onto the master file at a later time. Control is then returned (line 243) to statement 100 for a new key number. If a negative value is entered to conclude the deletion procedure, a mes- sage is printed (lines 244-246), files 30 and 33 are rewound (lines 247-248) to remove them from the update mode, and control is returned to subroutine REVISE by the RETURN 1 statement (line 249). If, during the dictionary lookup (subroutine SCANDC), a blank alphanumeric string is encoun- tered, a message is printed (lines 250—254), the master file is closed by a REWIND (line 255), and control is returned to subroutine REVISE (line 256). As in the other subroutines, INFONET-dependent subroutines are used to place data files in the update mode by first calling subroutine OBEY (lines 189— 194) to dynamically equivalence the master file and the subfile to files 30 and 33, respectively, and then, by calling subroutine UPDATE (lines 197—198), to place them in the update mode. The deletion of keyed records from file 21 is accomplished through the use of subroutine DELETE (line 242) . Also, certain of the subroutine logic is data dependent and must be modified to accommodate the addition of new master files. This logic occurs in the testing of KDIC for executing the subroutine OBEY calls (lines 189- 194), the testing of KDIC for calling the output- display routines (lines 225—227), and the logic for inserting the message onto the master record (lines 229—240) with the associated KDIC tests for the different data positions. 76 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS SUBROUTINE DELREC 83875?582$Uiiz'flfifilfidizfliifiefifidiii$$$$$$$$difiefifilfidilfidiifiefiibqtfitfilfififlieflfifi THIS IS SUBROUTINE "DELREC" (DELETE RECORD). IT IS DESIGNED TO DELETE INFORMATION FROM THE RECORDS OF THE MASTER FILE, LEAVING A CODED IDENTIFICATION NUMBER TO SHOW THE DATE OF DELETION AND THE IDENTIFICATION OF THE DATA MANAGER RESPONSIBLE FOR EXECUTING THE DELETION. A DELETION MESSAGE IS ALSO SUPERIMPOSED OVER SEVERAL OF THE DATA FIELDS WITH THE REMAINING DATA FIELDS LEFT BLANK FOR STORAGE IN THE KEYED MASTER FILE. THE RECORD DELETED FROM THE MASTER FILE IS WRITTEN FOR PRESERVATION ONTO A SAVE DELETION ("ESAVE." "HSAVE." OR "SAVUSA" FILE AS wELL AS PRINTED OUT IN HARD COPY ON THE TERMINAL OUTPUT DEVISE. NELEM = NUMBER OF DATA ELEMENTS IN A MASTER RECORD. VLIST = DATA ELEMENT NAMES AS THEY APPEAR IN THE DEFINITION AND MASK FILES. ITYPE = TYPE DESIGNATION OF THE DATA ELEMENTS AS LISTED IN THE MASK FILE. ITYPE = 1...INTEGER TYPE DATA ITYPE = 2...REAL TYPE DATA ITYPE > 10...DATA CONSISTS OF A DICTIONARY POINTER TD REFERENCE A LOOKUP IN THE (ITYPE - IOITH DICTIONARY. NREC = NUMBER OF RECORDS REVIEWED IN THE SELECTED SUBFILE. KDIC = INDEX TO IDENTIFY THE MASTER FILE BEING USED AND TO LOCATE THE PROPER MAXREC VALUE FROM THE DICTIONARY FILE. IMAGE = INTEGER REPRESENTATION OF MASTER DATA ELEMENTS, INCLUDING INTEGER DATA AND DICTIONARY POINTERS. OIMAGE = REAL REPRESENTATION OF MASTER DATA ELEMENTS THROUGH EQUIVALENCE WITH 'IMAGE.’ NSTRNG = INTEGER REPRESENTATION OF THE DATA STRING FOR ALL DATA ELEMENTS (INTEGER & ALPHANUMERIC) BELONGING TO A MASTER RECORD. STRING = REAL REPRESENTATION (THROUGH EQUIVALENCE STATEMENT) OF THE DATA STRING FOR ALL REAL“ VALUED DATA ELEMENIS BELONGING TO A MASTER RECORD. ARRAY (UP TO 7 COMPUTER WORDS) OF NEW ALPHA‘ NUMERIC DATA FOR COMPARISON WITH EXISTING DICTIONARY ENTRIES TO 1) DETERMINE DICT- IONARY POINTER OR 2) TO DETERMINE THAT A DICTIONARY ENTRY DOES NOT EXIST FOR THE GIVEN DICTIONARY CALEGORY. NUMBER OF WORDS (LESS THAN OR EQUAL IO 7) NEEDED TO STORE THE ALPHANUMERIC ENTRY IN "NAME." AN ARRAY SPECIFYING THE MAXIMUM NUMBER OF COMPUTER WORDS RESERVED FOR EACH RAW DATA NAME LT KWORD 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 $$$$ 2001 50 100 APPENDIX C 77 ELEMENT. NWORDS = THE TOTAL MAXIMUM NUMBER OF COMPUTER NORDS NEEDED TO STORE RAW DATA FOR THE IST THROUGH THE I-TH DATA ELEMENTS. COMMON NAMEDZSOO). ITYPEg $ PAD(401)9 VLISTo % NELEM COMMON ILOG/ MONTHo IDAY- % IYEAR’ ILOG. S MAXREC! KWORD! % KDIC- IRITE DOUBLE PRECISION VLIST(400) DIMENSION ITYPE(400)9 KWORD(400)9 S IMAGE(400)9 QIMAGE<4OO)9 S NSTRNGt4OO)9 STRINGI4OO)9 B NAMEIT) EOUIVALENCE (IMAGEOQIMAGE)O(NSTRNGTSTRING) DATA IBLANKl' o/ IF (IMA6E(1).I=1.NELEM) DO 300 1=1.~ELEM IMAGE(I) = IBLANK IMAGE(11) = 2 IF(KDIC oNEo 1 oOR. KDIC oNE. 3) GO TO 305 IMAGE(14) = 2 IMAGE(17) = 523 IMAGE(26) = ILOG IFCKDIC .NE. 2) GO TO 310 IMAGE(131 = 2 IMAGE(15) = 523 IMAGE(23) = ILOG CONTINUE wRITE(39.KEy=KeyR) (IMAGE(I191=19NELEM) CALL DELETEtZl.KEYR.1) so To 109 WRITE(691002) FORMAT(/' YOU HAVE ENTERED A NEGATIVE KEY VALUE T0 TERMINATE'R 1 THE DELETION PROCEDURE.') REHIND 39 RewIND 33 RETURN 1 wRITE(691010) KEYR FORMAT(/' ALPHANUMERIC DATA CONTAINS BLANK ENIRIES F033 5 1 RECORD KEY NUMBER: 0.18/ v RECORD HAS EITHER ALREADX BEENv » ' DELETED DR BEEN INCORRECTLY ENTEREDg/' SELECT PROCEDDREv w . FOUR (KEY REVIEW) TO REVIEW AND CORRECT THIb PROBLEM.' 1 REWIND 30 RETURN 1 END APPENDIX C 79 SUBROUTINE SEQREV Subroutine SEQREV is designed to perform a se- quential review of the records contained in a subfile of the master file. A listing of subroutine SEQREV appears at the end of this discussion. After each rec- ord is read in sequence, subroutine MODIFY is called to perform the revision of the data elements in the subfile and to call for display of the record. The option of posting the subfile to the master file cannot be executed until program control is returned to REVISE. The COMMON statements (lines 122—123) con- tain the variables as listed in the discussion of REVISE. Because the first 405 words in the COM- MON statement labeled LOG are not used in SEQREV, they have simply been lumped into an array called IDUMMY. If the IRITE variable transmitted through COM- MON has a value of 23, instructions for use of the sequential revision procedure are not displayed (lines 125—139). Then, the number of records re- viewed, NREC, is initialized to zero (line 140), and the sequential reading of the subfile begins (line 141). If an end of file is encountered during the read, all of the records in the subfile have been read, and control proceeds to statement 999 (line 144), which returns program control to REVISE. If a record has been read from the subfile, NREC is in- cremented by 1, and subroutine MODIFY is called. If the characters, QUIT, have not been entered for the prompt, NAME OF DATA ELEMENT TO BE CHANGED, program control is returned from MODIFY to statement 500 of subroutine SEQREV for the next sequential read. If QUIT has been en- tered, MODIFY makes a standard return to SEQREV, which, in turn, executes a standard re- turn (line 144) to REVISE. 80 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS SUBROUTINE SEQREV(NREC) THIS IS SUBROUTINE "SEGREV" (SEQUENTIAL REVISION). IT Is DESIGNED TO READ AND DISPLAY RECORDS. IN SEQUENCE. FROM A SUBFILE OF THE MASTER FILE FOR THE REVIEN AND POSSIBLE REVISION OF EACH RECORD. WHEN THE ENTIRE SUGFILE HAS BEEN EXAMINED AND THE NECESSARY REVISIONS COMPLETED. CONTROL HILL BE REIURNED TO SUBROUTINE "REVISE" HHERE THE DATA MANAGER MAY ExERCISE THE OPTION OF POSTING THE REVISED FILE ONTO THE MASTER FILE. NREC IMAGE NUMBER OF RECORDS REVIEMED IN THE SELECTED SUDFILE. INTEGER REPRESENTATION OF MASTER DATA ELEMENTS. INCLUDING INTEGER DATA AND DICTIONARY'POINTERS. REAL REPRESENTATION OF MASTER DATA ELEMENTS THROUGH EOUIVALENCE NITH 'IMAGE.’ DIMENSION VLIST(GOO). ITYPE(400)9 % IMAGE(400). QIMAGE(400) EOUIVALENCE (IMAGE.DIMAGEI DOUBLE PRECISION VLIST COMMON NAMEDtDOOI.ITYPE.PAD(401).VLIST.NELEM COMMON ILOG/ IDUMMY(§05)9KDICTIRITE IF(IRITE .E0. 23) GO To 499 NRITE(691001) 1001 FORMAT(//' RECORDS FROM THE DESIGNATED SUDFILE WILL BE: % v PRESENTED SEOUENTIALLY FOR REVIva/g AND UPDATE. AfiTERv % ALL RECORDS HAVE BEEN EXAM1NED BY THE REVIEHER. HE MAY- S THEN'/' ELECT TO POST THE RECORDS IN THIS SUDFILE ONTO THE!» MASTER FILE.'//' NHENEVER YOU HISH To LEAVE‘A SELECTEDT' % DATA ELEMENT UNCHANGED. ENTER ANT/g ASTERISK9 A,. % FOLLONED BY A CARRIAGE REIPRN.f//f IF YOU HISH TO PROCEDEIR TO THE NEXT RECORD IN THE FILE. ENTER THE CHARACTERS'I S "NEXT" FOLLOWING THE PROMPT: "NAME OF DATA ELEMENT 10 8E0 H CHANGED." THE "NEXT”‘/' COMMAND MILL LEAVE THAT REQORD' % IN ITS ORIGINAL. UNREVISED STATE AND THE NENT'IO RECORD' % MILL BE DISPLAYED. IN SEQUENCE. FROM THE SUUFILE. IF AT'% ANY TIME'/' You DO NOT WISH To REVIEU THE REMAINDER OF' % v THE FILE. ENTER "QUIT."' ) QIMAGE fifiiifiifiiizfiaflzfifliiifi C----------- 499 NREC = 0 500 READ(219END=999) (IMAGECI)OI=19NELEM) NREC = NREC + 1 CALL.MODIFY(SSOOOIMAGEDQIMAGE) 999 RETURN END APPENDIX C 81 SUBROUTINE KEYREV Like SEQREV, most of the record modification is accomplished by a call to subroutine MODIFY. A listing of subroutine KEYREV appears at the end of this discussion. The record selection, however, is ac- complished by specifying the key value for a record from the subfile instead of reading the records sequentially. The variables in the COMMON statements (lines 120-121) are identical with those in the SEQREV discussion. The DATA statement (line 122) initial- izes IYES and NO for testing against user entries. If the value of IRITE is other than 23 (line 123), the instruction message for the keyed revision pro- cedure will be displayed (lines 124—140). The number of records reviewed, NREC, is set to zero (line 141) , and the user is prompted to enter the value for the record key, IKEY (line 142). Then, IKEY is tested for a negative value (line 143), which will lead to termination of the keyed revision procedure by a transfer to statement 999 for the display of a termination message giving the total number of records reviewed (lines 147—150). If the IKEY value is positive, NREC is incre- mented by one (line 144), and the record with that key value is read from the subfile on unit 21 (line 145). Subroutine MODIFY is called (line 146) for the user interactive modification of each record ref- erenced from the subfile. If the QUIT command has not been entered while under the control of MODI- FY, and if modification of the record has been com- pleted, control will be returned to statement 100, where the user is prompted for a YES or NO answer to post the record to the master file (lines 153—156) . If the response is other than a YES or a NO, a test for these values (line 157) will recycle to statement 10 until the appropriate input is entered. If the re- sponse is YES, the record is posted onto the master file on unit 20 (line 158). A prompt is made for intent to review more rec- ords (lines 159—161). Again, a YES or NO response is required. If the test does not match a YES or a NO value (line 162) , control is returned to statement 20 for re-entry of the proper value. A NO value will terminate the keyed revision procedure and return to REVISE (line 163). If the value is YES, control (line 164) is recycled to statement 500 for the entry of the key of the next record to be reviewed. No INFONET-dependent library software is used in this subroutine, nor is there any logic that is de- pendent on the structure of the master file. 82 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS SUBROUTINE KEYREV(“) idifiaflefib‘tdi’flibqiic‘fifiefifi 1001 499 590 999 1002 998 THIS IS SUBROUTINE "KEYREV" (KEYED REVISION). IT IS DESIGNED To READ AND DISPLAY RECORDS. AS SPECIFIED BY RECORD KEY. FROM A SUBFILE OF THE MASTER FILE FOR THE REVIEN AND POSSIBLE REVISION OF EACH RECORD. NHEN A RECORD HAS BEEN REVIERED. THE DATA MANAGER IS GIVEN THE OPTION 0F POSTING THE RECORD ONTO THE MASTER FILE OR LEAVING IT IN THE SUBFILE FOR FURTHER REVIEH. NREC = NUMBER OF RECORDS REVIEWED IN THE SELECTED SQBFILE. IMAGE = INTEGER REPRESENTATION 0E MASTER DATA ELEMENT59 INCLUDING INTEGER DATA AND DICTIONARY POINTERS. QIMAGE 8 REAL REPRESENTATION 0F MASTER DATA ELEMENTS THROUGH EQUIVALENCE WITH 'IMAGE.’ DIMENSION VLISTt400). ITYPEI400). S IMAGEI4OO). QIMAGE(400) EQUIVALENCE (IMAGE.OIMAGE) DOUBLE PRECISION VLIST COMMON NAHED(ROOT.ITYPE.PAD(491).VLIST.NELEM COMMON /LOG/ IDUMMY(4OS)9KDICDIRITE DATA IYES.NO/-YESv.3No-/ IF(IRITE .EO. 23> GO To 499 NRITETS.IOOIT FORMAT(/' RECORDS FROM THE DESIGNATED SUBFILE HILL SE: S v PRESENTED. As SPECIFIED BY KEY'/' NUMBER. PDR REVIEH AND' % UPDATE. AFTER THE REVIEWER HAS EXAMINED THE CONTENTSv/ S OF THE RECORD OF INTEREST. HE MAY ELECT TO POST THAT; A RECORD ONTO THE MASTERv/o FILE.'//v REGARDLESS 0F VHETHERYS THE RECORD Is POSTED TO THE MASTER FILE. IT HILL REMA1N9'/% AS REVISED. IN THE SUBFILE.'//' TO ACCESS THE DESIRED' S RECORD. RESPOND TO THE PROMPT "KEY" BY ENTERING THE;/ S RECORD"S KEY NUMBER. ... ENTERING A "-1" WILL CONCLUDE' % THE KEYED ACCESSo/g PROCEDURE.'//! IF YOU HISH TO GO ON' A TO ANOTHER RECORD IN THE FILE. ENTER THE CHARACTERS: S "NEXT"'/' FOLLOHING THE'PROMPT: "NAME OF DATA ELEMENT Too S BE CHANGED." THE "NEXT" COMMANDo/v HILL LEAVE THAT: % RECORD IN ITS ORIGINAL. UNREVISED STATE AND PROMPT PORo % THE NEXT'/' RECORD KEY.'//' HHENEVER YOU HISH To LEAVE A' $ . SELECTED DATA ELEMENT UNCHANGEO. ENTERv/I AN ASTERISK. *.v) NREC = o READ(59*9PROMPT='KEY§ 0) IKEY IF(IKEY .LT. 0) Go To 999 NREC = NREC + 1 READ(219KEY=IKEY) <1MAGE 10...DATA CONSISTS OF A DICTIONARY POINTER TO REFERENCE A LOOKUP IN THE (ITYPE - 10)TH DICTIONARY. INTEGER REPRESENTATION OF MASTER DATA ELEMENTS. INCLUDING INTEGER DATA AND DICTIONARY POINTERS. REAL REPRESENTATION OF MASTER DATA ELEMENTS THROUGH EQUIVALENCE VITH vIMAGE.' INTEGER REPRESENTATION OF THE DATA STRING FOR ALL DATA ELEMENTS (INTEGER S ALPHANUMERIC) BELONGING To A MASTER RECORD. REAL REPRESENTATION (THROUGH EOUIVALENCE STATEMENT) OF THE DATA STRING FOR ALL REAL- VALUED DATA ELEMENTS BELONGING To A MASTER RECORD. DATA ELEMENT POSITION INDEX FOR EACH RECORD. ARRAY (UP TO 7 COMPUTER WORDS) OF NEH ALPHA- NUMERIC DATA FOR COMPARISON NITH EXISTING DICTIONARY ENTRIES To 1) DETERMINE DICT- IONARY POINTER OR 2) TO DETERMINE THAT A DICTIONARY ENTRY DOES NOT EXIST FOR THE GIVEN DICTIONARY CATEGORY. NUMBER OF NORDS (LESS THAN OR EQUAL To 7) NEEDED TO STORE THE ALPHANUMERIC ENTRY IN "NAME." KHORD = AN ARRAY SPECIFYING THE MAXIMUM NUMBER OF coMPUTER NORDS RESERVED FOR EACH RAH DATA ITYPE IMAGE QIMAGE NSTRNG STRING ITEM NAME LT 153 154 155 156 157 158 159 160 161 162 163 180 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 £80 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 APPENDIX C 87 5 ELEMENT. 5 NMOHDS = THE TOTAL MAXIMUM NUMBER OF COMPUTER 80805 5 NEEDED To STORE RAH DATA FOR THE IST THROUGH 5 THE I-TH DATA ELEMENTS. DIMENSION IMAGEI4OOI9 NSTRNGI4OOI9 5 ITYPEI4OOI9 OIMAGE(4OQ)9 STRINGI4OOI9 5 VLISTI400)9 KNORD<400). NAME17) DIMENSION IDATA(400) DOUBLE PRECISION VLABEL9 5 VLIST9 QNEXT9 OUIT COMMON NAMEDIBOO)9ITYPE9PADI4OII9VLIST9NELEM COMMON /LOG/ MONTH9IOAY9IYEAR9ILOG9MAXREC9KNORD9KDIC9IRITE EQUIVALENCE (ISTAR9STARI9(IMAGE9QIMAGEI9(NSTRNG9STRING) DATA IBLANK’QBLANK9YES9XNOISTAR/' '9' '9'YES'9'NO'9'*'/ DATA QNEXT9OUIT/‘NEXT'9‘QUIT'/ IFIIRITE oEQ. 23) GO TO 60 WRITEI691001) 1001 FORMATII' THIS IS THE BATCH UPDATE PROCEDUREO'/' GIVEN A' S ' SPECIFIED DATA ELEMENT NAME AND A SPECIFIED DATA ELEMENT. % VALUE! THIS'I' PROCEDURE CHANGES ALL RECORDS IN THE GIVEN'% SUBFILE TO THE DATA VALUE SPECIEIED'I' FOR THAT DATA' % ELEMENT NAME.'//' IHE BATCH EDIT/REVISION PROCEDURE CAN‘ 5 BE TERMINATED BY ENTERING "QUIT" NHEN'/' A PROMPT FOR THE'% ' NAME OF THE DATA ELEMENT IS ENCOUNTERED.‘ I 1002 FORMATIA8) 60 READI59IQOZ9PROMPT=INAME OF DATA ELEMENT TO% BE CHANGED: 'I VLABEL IFIVLABEL .EQ. QUIT) GO TO 999 ITEM = 0 DO 70 I=19NELEM ITEM 3 ITEM 9 1 70 IFIVLABEL .EO. VLISTIIII GO TO 80 C--- WRITE(691003T 1003 FORMAT(/' ITEM NOT IN LIST OF DATA ELEMENTS9 HEENTER'I GO TO 60 80 IF(ITYPE(ITEM)-2) 11091209130 % % THE FOLLOWING STATEMENTS PERMII REPLACEMENT OF THE INTEGER % DATA CONTAINED IN THE ‘IMAGE' ARRAY. % 110 READI59*9PR0MPT=IENTER VALUE? ‘1 INPT IFIINPT .EQo ISTARI GO TO 997 IMAGEIITEM) = INPT GO TO 155 % % THE FOLLOWING STATEMENTS PERMIT REPLACEMENT OF THE REAL % DATA CONTAINED IN THE 'IMAGE' ARRAY. % 120 READ(59* 9PROMPT=IENTER DECIMAL VALUE' '1 OPUT IFIOPUT 0E0. STAR) GO TO 997 OIMAGEIITEM) = OPUT GO TO 155 % % THE FOLLOWING STATEMENTS PERMIT REPLACEMENT OF ALPHA- 88 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 ‘246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS % NUMERIC DATA. GENERATE NEw POINTER59 AND UPDATE THE % DICTIONARY IF THE SPECIFIED DATA VALUE DOES NOT % ALREADY RESIDE THERE. % 130 KSUM = 1 ITEM1 = ITEM - 1 DO 140 I=1oITEM1 140 KSUM = KSUM + KMORDTIT KSUMPI = KSUM + KWORD(ITEM) - 1 1006 FORMAT(7A4) READ(SulQOéoPROMPT='ENTER VALUE: 0) (NSTRNG(1)OI=KSUM9KSUMP1) IF(NSTRNG(KSUM) .EO: ISTAR) GO To 99? LAST = KMORDIITEM) KSUMMI = KSUM - 1 Do 145 1:197 145 NAME(I) = IBLANK DO 150 I= 19LAST 150 NAME(I) = NSTRNG NDIC = ITYPE(ITEM) - 10 CALL MATCH (NAME.NOICoLToMKEY.NUMo$995.$996) IMAGE(ITEM) = MKEY - NDIC*10000 THE FOLLOWING STATEMENTS READ! SEQUENTIALLY! ALL OF THE RECORDS IN THE SUBFILE AND APPLY THE CHANGE IN DATA VALUE FOR THE SPECIFIED DATA PARAMETER TO EACH RECORD. AND THEN REWRITE THE RECORD BACK ONTO THE SUBFILE- "IDATA" IS USED AS A DUMMY I/O PARAMETER. v—aiuizfizfiefizfiafiefi UT UT NREC = 0 REWIND 21 CALL UPDATEtZlol) READ(219END=17O) (IDATA(I)91=19NELEM) IDATA(ITEM) = IMAGE(ITEM) NREC = NREC + 1 CALL GETKEY(2191KEY) WRITE(219KEY=IKEY) (IDATATI)9 I=19NELEM) GO TO 100 170 WRITE(691007) 1007 FORMAT(/' DO YOU MISH To CHANGE ANY MORE DATA ELEMENTS' % ' BELONGING TO THIS FILE? ENTER 3) 180 READ(5,19089PR0MPT='"YES" OR "NO": 'ITEST 1008 FORMAT(A4) IF((TEST .NE. YES) .ANO. (TEST .NE. XNO)) GO TO 180 IF(TEST .EO. YES) 60 To 60 RETURN 1 994 WRITE(691010) 1010 FORMAT(/' DICTIONARY KEY EXCEEDS PERMISSABLE CAPACITYA FOR THE GIVEN v/v DATA ELEMENT NAME.'/% ' EXECUTION TERMINATED!'/% ' CONTACT PROGRAMMER.') STOP 995 WRITE(692001) VLABELyNAME 2001 FORMAT(/' THERE IS NO DICTIONARY MATCH FOR DATA NAME: 1% 3—- 0‘ o 261 262 263 264 265 266 267 268 269 270 271 272 £73 274 275 276 277 278 279 280 281 190 996 1009 997 1011 999 1012 APPENDIX C 89 .AT/v ALPHANUMERIC UATA: v!7A4/% v DO YOU NISH T0 ENIER THIS DATA IN THE DICTIONARY?') READ(5919089PROMPT='"YES 0R "N0"§ 1) [EST IF((TEST .NE. YES) ,AND. (TEST .NE. XNO)) so ID 190 IF(TEST .Eo. XNO) GO To so NUM = NUM¢1 CALL ADDICT(NAMEoLTaNDICoNUMo$994) IMAGE(ITEM) = NUM GO TO 155 WRITE(691009) FURMAT(/' BLANK DICTIONARY ENTRIES ARE NOT LEGITIMATEo') GO TO 179 wRITE VLABEL FORMAT(/' you HAVE QNTERED AN ASTERISK. *. TO LEAVE'.% 1X9A79' UNcHANGEo.v/1 GO To so WRITE(691012) FORMAT(/' you HAVE ENTERED "QUIT" T0 TERMINATE THE BAICH' % ' EDIT/REVISION PROCEDURE.' 1 RETURN END 90 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS SUBROUTIN E MODIFY This subroutine is used to change the data values on a single record. A listing of subroutine MODIFY appears at the end of this discussion. It is called from subroutine SEQREV or from subroutine KEYREV. In either case, the record is accessed from the sub- file by reading each record in sequence, as done by SEQREV, or by referencing the record by its key value, as performed in KEYREV. The user may modify as many data values as desired on a selected record. When modification of that record is con- cluded, control is returned to the calling subroutine for selection of the next record to be modified. The major variables are identified and defined in the comments at the beginning of the listing. Those variables listed in the COMMON statements (lines 154—155) are identical With the variables discussed in subroutine REVISE. Again, the integer and real representations of (1) the raw-data strings, N STRNG and STRING, (2) the master-file arrays, IMAGE and QIMAGE, and (3) the asterisk values, ISTAR and STAR, have been equivalenced in each case (line 156). The data fill is initialized (lines 157— 158) for alphanumeric values of YES, XNO, STAR, QNEXT, and QUIT, as well as the variables IBLANK and QBLANK, Which are used for insert- ing blank data fill. The first action by this subroutine is the decoding of the selected record from its master-file format to the raw-data format (lines 159—199) in order to dis- play the record to the data manager for review. This process begins by initializing to zero (line 159) the counter for the number of computer words, N WORDS, used to store the first “I” data elements in the raw-data string. Then, each of the NELEM data elements is translated into its proper position in the raw-data string, beginning with the DO statement (line 160). The I-th data element is tested for type by com- paring the value in the I-th position of the ITYPE array with the integer 2 (line 161). Thus, if the ITYPE value is 1, the data element is an integer, and control passes to statement 10. If the ITYPE value is 2, the data element is real, and control is transferred to statement 20. If the ITYPE value is greater than or equal to 3 (in fact, ITYPE values will be greater than 10 to include pointer codes for the dictionary categories), the data type is alpha- numeric, and control will be transferred to statement 30, where the relevant word string will be accessed from the (ITYPE—10)-th dictionary category. At statement 10 (line 167), the value of NWORDS is again incremented by the number of computer words, KWORD, reserved for the I-th data element. Then, the integer data in the I-th word of the master record array, IMAGE, is substituted into the NWORDS position of the raw-data string, NSTRNG (line 168). Next, control is transferred (line 169) to statement 99 for recycling through the DO loop for the next data element. At statement 20 (line 175) , the value of NWORDS is again incremented by the number of computer words, KWORD. The real data in the I-th word of the master record array, QIMAGE, is substituted into the NWORDS-th position of the raw—data string, STRING (line 176), and control is trans- ferred (line 17) to statement 99 to continue through the DO loop, processing the next data element. Statement 30 begins the logic of translating from the dictionary pointer of the data element to the alphanumeric string referenced by that pointer and contained in the dictionary category associated with that data element though the corresponding value in the ITYPE array. First, the IMAGE value is tested for blank data (line 186). If the value is blank, the length of the alphanumeric string, LT, is set to zero (line 187), and control is transferred (line 188) to statement 45. If the data in IMAGE is nonblank, con- trol is transferred to statement 35, where subrou- tine SCANDC is used to select the corresponding alphanumeric entry from the dictionary (line 189) . The calling sequence provides the dictionary cate- gory index, ITYPE minus 10, and the pointer, IMAGE. The array containing the alphanumeric string, NAME, and the value giving the number of computer words required for that string, LT, are returned from SCANDC through the calling se- quence. If there is a blank dictionary entry corres- ponding to a nonblank integer value of the pointer, control is transferred to statement 996, where a message is displayed. After the contents of the record have been dis- played to the data manager, he is then prompted for the entry of the name of the data element to be changed (lines 205—206). If, instead of the data name, the characters, NEXT, or the characters, QUIT, are entered, action on the displayed record will be terminated. The entered value is first tested against the value of QNEXT (line 207), and if there is equality, the logic proceeds to statement 998, where a message is displayed (lines 283—285), and control is returned to the calling routine by a RETURN 1 statement (line 286) . If the comparison with QNEXT fails, the variable name is next tested APPENDIX C 91 against the value of QUIT (line 208). If equality exists, control is transferred to statement 999, where a message is displayed (lines 287—289), and the record is rewritten onto the subfile (line 290), thus posting all modifications to the record prior to entry of the characters QUIT for the data-element name. A standard return (line 291) is then taken to the calling routine. If the characters, NEXT, have been entered for input of the data-element name, then con- trol is returned to the calling routine without first rewriting the record onto the subfile. Therefore, none of the prior modifications made to that record are posted; instead, the record will remain in the sub- file with its original contents unchanged. If the value of the data-element name, VLABEL, was not entered with the characters NEXT or QUIT, the entry is then tested against all of the data-ele- ment names in the VLIST array to ensure that it is a valid data-element name (lines 209—215). If there is a match with one of the data-element names (line 212) , control is transferred to statement 80 to begin processing the change in data value for that data element. If there is no match, a message is displayed (lines 213—214), and control is returned (line 215) to statement 60 to re-enter the data-element name. The value of ITEM has been determined (line 211) when the DO loop is exited by passing the test against the ITEM-th position of VLIST (line 212) . This value of ITEM is now used to reference the ITYPE value corresponding to the selected data- element name to test for the data-element type (line 216) . If the ITYPE value is 1, the data type is integer, and control proceeds to statement 110 (line 221), where the data manager may input the replacement data value. If, instead, an asterisk is entered, the test against the value of ISTAR (line 222) is passed, and control transfers first to statement 997, where a message is displayed (lines 279—281), and then to statement 60 (line 282) . A prompt is made for a new data-element name without any change to the value of the preceding data element. If a value other than an asterisk has been entered for the integer input, this value is transferred into the position of that data element in the IMAGE array (line 223), and then control is passed to statement 160 for a message query regarding the change of additional data ele- ments for that record (lines 256—258). If the ITYPE value is 2, the data type is real, and control passes to statement 120 (line 229) to prompt for decimal data entry. If, instead, an asterisk is entered, the test against the value of STAR (line 230) is passed, and control again transfers to state- ment 997, leaving the value for that data element unchanged. Otherwise, the decimal data value is transferred into the proper data-element position of the QIMAGE array (line 231), and control passes to statement 160 for the message query regarding further modifications. If the ITYPE value is greater than 10, the data type is alphanumeric, and control passes to statement 130 (line 239) , the start of the logic for the entry of alphanumeric data. The value of KSUM, the number of computer words required for the storage of all data elements prior to the ITEM-th plus the first word of the ITEM-th position, is computed (lines 239—242), as is the value of KSUMPI (line 243), the number of computer words reserved to store all data elements through the ITEM-th position. Next, the data manager is prompted for entry of an alpha- numeric data string in the KSUM through KSUMPI positions of NSTRNG (lines 244—245). The first word of the string is compared with ISTAR (line 246) and, if equal, control is transferred to state- ment 997 , the data element is left unchanged, and an informational message is printed. The value of LAST is set equal to the current value from the KWORD array (line 247) for use as a limit for the DO loop index, and the value of KSUMMl is set to the value of KSUM minus one (line 248) , for use in computing the NSTRNG index (line 252). After all seven words of the NAME array are blanked out (lines 249—250) , the most recent values placed in the NSTRNG array are also transferred into the NAME array (lines 251—252) . The diction- ary category number, NDIC, is computed by sub- tracting 10 from the ITEM-th position of the ITYPE array (line 253). Finally, subroutine MATCH is called (line 254) to search the specified dictionary category for an entry matching the new alphanumeric data input. The al- phanumeric data are communicated through the call- ing sequence by the NAME array, and the dictionary category is communicated by NDIC. If there is a dictionary match, the subroutine returns the number of computer words in the dictionary entry, LT, the key value for the dictionary entry, MKEY, and the number of dictionary entries contained in that cate- gory, NUM. If there is no match, control is trans- ferred to statement 995 or, if the data are blank, to statement 996. If a dictionary match has been found, a standard return is executed from MATCH, and the following statement (line 255) computes the value of the 92 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS pointer to that dictionary entry for storage in the IMAGE array. The user is then prompted for a YES or NO entry for a change of additional data ele- ments belonging to the current record (lines 256— 259). The YES or NO response is tested to ensure that one of the two allowable responses has been entered (line 260), recycling of the YES or NO prompt, if the test fails. If a proper response has been given, the response is then tested for a YES value (line 262) , which will cause control to be trans- ferred to statement 60 (line 205), where a new data- element name will be entered for data-value modifi- cation. If the test fails, the IMAGE array containing changed data values will be rewritten onto the sub- file over the old data for that record (line 263), and a RETURN 1 exit is taken from subroutine MODI- FY (line 264). If there was no dictionary match found for the new alphanumeric input, the user is prompted with a message giving the data-element name and the newly entered data and asking if it is to be added to the dictionary (lines 265—269). Again, the YES or NO response is tested to ensure that one of the two allowable values has been correctly entered (line 270), returning to the prompt at statement 170, if the test fails. If the response is NO, the test (line 271) is satisfied, and control is returned to state- ment 60 for selection of another data-element name for data revision. If the response is YES, the number of entries in the given dictionary category is in- creased by 1 (line 272), and subroutine ADDICT is called (line 273) to enter that alphanumeric data into the dictionary. The following variables are transferred to ADDICT through the calling se- quence: the NAME array, containing the new alpha- numeric data; the length, LT, of the array; the dic- tionary category number, NDIC; and the new num- ber of entries for that category, NUM. The value of NUM, the dictionary pointer for the new entry, is transferred into the ITEM-th position of the IMAGE array (line 274), and control is trans- ferred (line 275) to statement 160 for a prompted response to continue with data revision for that record or to go on to another record. If the new data entered consist only of blank data, the return from subroutine MATCH transfers con- trol to statement 996, where a message is displayed stating that blank data are not legitimate (lines 27 6— 27 7). The blank data value is not substituted for the data element, and control is returned to statement 160 for the user’s selection of additional data ele- ments to be revised. The statements in MODIFY which are master file dependent are the calls to the record display routines (lines 201 and 203) based on the value of the master- file index, KDIC. One INFONET-dependent subrou- tine, GETKEY, is called (line 200) to obtain the key value for the last record read from file 21. 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 APPENDIX C SUBROUTINE MODIFY(*DIMAGEQQIMAGE) % % % % % % % % % % % $ % % % % % % % i % % % % $ % % % % % % % % % % % % % i % % $ % % % % % % SUBROQTINE 'MODIFY' IS DESIGNED TO READ A RECORD FROM AN EXISTING! KEYED, MASTER FILE! OR A SUBFILE OF THE MASTER FILE! AND DISPLAY THE DATA SO THAT THE USER ELEMENTS NELEM VLIST ITYPE IMAGE QIMAGE NSTRNG STRING ITEM NAME LT KNORD NWORDS NDIC NUM DOUBLE VLIST’ DIMENSION ll IS AHLE To MODIFY THE INDIVIDUAL DATA AS REQUIRED. NUMBER OF DATA ELEMENTS IN A MASTER RECORD. DATA ELEMENTS NAMES As THEY APPEAR IN THE DEFINITION AND MASK FILES. TYPE DESIGNATION OF THE DATA ELEMENTS As LISTED IN THE MASK FILE. ITYPE = I...INTEGER TYPE DATA ITYPE = a...REAL TYPE DATA ITYPE > 10...DATA CONSISTS OF A DICTIONARY POINTER TO REFERENCE A LOOKUP IN THE (ITYPE - 10)TH DICTIONARY. INTEGER REPRESENTATION OE MASTER DATA ELEMENTS. INCLUDING INTEGER DATA AND DICTIONARY POINTERS. REAL REPRESENTATION OF MASTER DATA ELEMENTS THROUGH EQUIVALENCE VITH '1MAGE.‘ INTEGER REPRESENTATION OF THE DATA STRING FOR ALL DATA ELEMENTS (INTEGER 5 ALPHANUMERIC) BELONGING TO A MASTER RECORD. REAL REPRESENTATION (THROUGH EOUIVALENCE STATEMENT) OF THE DATA STRING FOR ALL REAL- VALUED DATA ELEMENTS BELONGING TO A MASTER RECORD. DATA ELEMENT POSITION INDEX FOR EACH RECORD. ARRAY (UP TO 7 COMPUTER WORDS) OF NEW ALPHA- NUMERIC DAIA FOR COMPARISON WITH EXISTING DICTIONARY ENTRIES TO 1) DETERMINE DICT- IONARY POINTER OR 2) TO DETERMINE THAT A DICTIONARY ENTRY DOES NOT EXIST FOR THE GIVEN DICTIONARY CATEGORT. NUMBER OF HORDS (LESS THAN OR EOUAL To 7) NEEDED TO STORE THE ALPHANUMERIC ENTRY IN "NAME." AN ARRAY SPECIFYING THE MAXIMUM NUMBER OF COMPUTER WORDS RESERVED FOR EACH RAW DATA ELEMENT. THE TOTAL MAXIMUM NUMBER OF COMPUTER wORDS NEEDED To STORE RAH DATA FOR THE IST THROUGH THE I-TH DATA ELEMENTS. DICTIONARY CATEGORY REFERENCE NUMBER. TOTAL NUMBER OF DICTIONARY ENTRIES IN THE "NDIC" DICTIONARY CATEGORY. PRECISION VLABELQ A ONEXT. OUIT IMAGE(400)o NSTRNG(4OO)9 t ITYPE(400). OIMAGE(400). STRING(400). A 93 94 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 PACER—DATA ENTRY, RETRIEVAL, AND UPDATE FOR NCRDS VLIST(400)9 KNOROI4OO), NAME(7) COMMON NAMED(600)vITYPEoPAD(401)vVLISToNELEM COMMON /LOG/ MONTH.IDAY.IYEAH.ILOG.MA&REC-KH0H09KDICoIHITE EOUIVALENCE (ISTAR.STAR),(IMAGE.OIMAGE).(NSTRN695TRING) DATA IBLANKcQBLANKo7E59XN09STAR/' '9' '9'YES'9'N0'9'*‘/ DATA QNEKToQUIT/'NEXT'9'QUIT’I NwoRos = 0 DO 109 I=1.NELEM IF(ITYPE(I) - a) 10oE0939 THE FOLLOWING STATEMENTS ACCEPT THE DATA ELEMENTS RECORD STRING. % % — ~ ‘ . % WHICH ARE INTEGER HORDS AND ADD THEM TO THE TOTAL ‘5 5 10 Nfiiiiefi 0 Ufizfiiiiafifii 40 45 50 55 99 100 1002 60 NwoROS = NwOROs + KWORD(I) NSTRNG(NNORDS) = IMAGEII) 60 T0 99 THE FOLLOWING STATEMENTS ACCEPT THE DATA ELEMENTS WHICH ARE REAL WORDS AND ADD THEM TO THE TOTAL RECORD STRING. NWORDS = NWURDS + KWORD(I) STRING(NWORDS) = QIMAGE(I) GO TO 99 THE FOLLOWING STATEMENTS BRING THE ALPHANUMERIC ELEMENTS (REFERENCED 3i THE CODED POINTERST FROM THE APPROPRIATE DICTIONARIES AND ADD THESE ELEMENTS TO THE TOTAL HECORO STRING. INCLUDING THOSE PORTIONS OF THE DICTIONARY WORDS WHICH ARE BLANK. IF(IMAGE(I) .NE. IBLANK) 60 To 35 LT = 0 60 To 45 CALL SCANDC(ITYPE(I)-109IMAGE(I)oNAME’LT9S996) Do 40 J=19LT NSTRNG(J+NWORDS) = NAMETJT IF(LT .GE. KWORD(I)) GO To 55 LAST = KWORU(I) LTPl = LT + 1 DO 50 d=LTP1¢LAST NSTRNG(J+NWORDS) = IBLANK NWORDS = NMOROS . KWORD(I) CONTINUE CONTINUE CALL GETKEYtZlyKEYRT IF(KDIC .E0. 1) CALL OUTUSC(NSTRNG.STRINGAKEYHgNWORDS) IF(KDIC .E0. 2) CALL GUTUSA(NSTRNG.STRINGoKEYHoNHORDS) IF(KDIC .E0. 3) CALL OUTUSC(NSTRNGoSTRINsoKEYH.NHORDST FORMAT(A8) READtSclOOZoPROMPT='NAME OF DATA ELEMENT T0$ BE CHANGED: ') VLABEL 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 APPENDIX C 95 IF(VLABEL .EQ. ONEXT) GO To 993 IF(VLABEL .EQ. QUIT) GO To 999 ITEM = 0 DO 70 I=19NELEM ITEM = ITEM # 1 70 IF(VLABEL .EQ. VLIST(I)) 60 To 80 WRITE(691003) 1003 FORMAT(/' ITEM NOT FOUND IN LIST OF DATA ELEMENTSoREENTER') 60 To 50 80 IF(ITYPE(ITEM)-2) 11091209130 % % THE FOLLOWING STATEMENTS PERMIT REPLACEMENT OF THE INTEGER % DATA CONTAINED IN THE 'IMAGE' ARRAY. % 110 READ(59*9PROMPT='ENIER VALUE: 0) INPT IF(INPT .EO. ISTAR) GO TO 997 IMAGE(ITEM) = INPT GO TO 160 % % THE FOLLOWING STATEMENTS PERMIT REPLACEMENT OF THE REAL % DATA CONTAINED IN THE 'IMAGE' ARRAY. % 120 READ(5.*.PROMPT='ENTER DECIMAL VALUE: 0) OPUT IF(QPUT .EQ. STAR) GO To 997 OIMA6E NUM.N 117 NKEY = LKEY o IPOINT 118 IF(NKEY .GT. LKEY + NUM) GO TO 100 119 READ(99KEY=NKEY) LT.(NAME(I).I=1.LTI 120 RETURN 121 100 NHITE<691001) IPOINIoNUMoNDIC 122 1001 FORMAT(/' DICTIONART POINTER ('9189% 123 '1 EXCEEDS NUMBER OF ENTRIES /V 66°00’ FIGURE 17.—Distribution of icings along the trans-Alaska pipeline route in the Bettles quadrangle. 20 ICINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE 149°00’ EXPLANATION w LARGE ICING N CHANNEL ICING 10 MILES 5 10 KILOMETRES EZEZEE CONTOUR INTERVAL 200 FEET DATUM IS MEAN SEA LEVEL FIGURE 18.—Distribution of icings along the trans-Alaska pipeline route in the Tanana and Livengood quadrangles. ICINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE 21 FIGURE 19.—Channel and hillside icings along Aggie Creek in Yukon-Tanana Uplands north of Fairbanks, May 23, 1973. 22 IdINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE 148° 00' I'Mr _ _ \ ‘, it EXPLANATION W LARGE ICING M CHANNEL ICING 65°30' 0 5 10 MILES l—l I—l I—i 5 0 5 10 KILOMETRES EIEZEE CONTOUR INTERVAL 200 FEET DATUM IS MEAN SEA LEVEL 65° 00' 14 \c. e Cveek an»? theological Srikx'fi'ey Livengood. Alask. \ T ’5? anidFaubahks, Alaska, 122 50 0 00 FIGURE 20.—Distribution of icings along the trans-Alaska pipeline route in the Livengood and Fairbanks quadrangles. ICINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE 23 147°00' 65°OO' .146 ,°°' EXPLANATION w LARGE ICING N CHANNEL ICING 5 0 5 10 MILES 5 0 5 10 KILOMETRES EIEZE:E CONTOUR INTERVAL 200 FEET DATUM IS MEAN SEA LEVEL , Ewing FIGURE 21.—Distribution of icings along the trans-Alaska pipeline route in the Big Delta quadrangle. .1..— 64°00" ICINGS ALONG THE TRANS-ALASKA PIPELINE ROU E FIGURE 22.—Therma1 infrared image of icings along Minton Creek, February 4, 1974. Water surfaces (arrows) contrast with snow and vegetation background. FIGURE 23.—Icings in flats north of Shaw Creek, May 22, 1972. ICINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE 145°00' )L I; i K 5' \ EXPLANATION m LARGE ICING M CHANNEL ICING 640 00' 0 5 10MILES I=I I—I r—4 1—— 5 0 5 10 KILOMETRES EZEZE:E CONTOUR INTERVAL 200 FEET DATUM IS MEAN SEA LEVEL o ‘E 63 00’ FIGURE 24.——Distribution of icings along the trans-Alaska pipeline route in the Mt. Hayes quadrangle. 26 ICINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE FIGURE 25.—Flood-plain icings along Delta River. Alluvial fans of Flood, Michael, and Trims Creeks in left foreground. View south (upstream) on May 29, 1973. ' FIGURE 26.——Flood—plain icing in Delta River valley upstream from Miller Creek, April 18, 1974. ICINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE 27 FIGURE 27.—Icing in Phelan and McCallum Creeks, May 29, 1973. DlSTANCE, |N METRES 100 200 300 I I I DU) — Snow IN FEET Ice surface DEPTH, ilt, sand, and grave o co m A N o N p 0) oo o DEPTH, IN METRES d 200 400 600 800 1000 DISTANCE, IN FEET 0 FIGURE 28.—Cross section through icing at mouth of Phelan Creek, April 27, 1972. (See location of section in fig. 2.) 28 ICINGS ALONG THE TRANS—ALASKA PIPELINE ROUTE FIGURE 29.—Icing on Gunn Creek at Richardson Highway and pipeline crossing, June 6, 1970. 63°00' , 62° 00' ICINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE 29 146°00' EXPLANATION w LARGE ICING N CHANNEL ICING 5 0 5 10 MILES 5 0 5 10 KILOMETRES ESE CONTOUR INTERVAL 200 FEET DATUM IS MEAN SEA LEVEL . (igufd’gical Survéy “$2, asks?» .1 =25}, 900-” '; FIGURE 30.—Distribution of icings along the trans-Alaska pipeline route in the Gulkana quadrangle. ICINGS ALONG THE TRAN S-ALASKA PIPELINE ROUTE 30 o146°30 6200 ~ W/ J “I? l ,/4 pf : 0W6; 5 Dal ‘ EXPLANATION @ LARGE ICING N CHANNEL ICING 5 o 5 10 MILES I=I l—I I—I : 3 5 o s lOKILOMETRES N Z CONTOUR INTERVAL 200 FEET DATUM IS MEAN SEA LEVEL 61°00’ ‘ FIGURE 31.—Distribution of icings along the trans-Alaska pipeline route in the Valdez quadrangle. ICINGS ALONG THE TRANS-ALASKA PIPELINE ROUTE 31 FIGURE 32.—Icing fodrme from ground-water seepage at face of gravel pit near Little Tonsina iver, April 1, 1971. I}U.S. GOVERNMENT PRINTING OFFICE: 1976 - 690-036/96 0576' F0 7 DAYS 1/. aeo Effects of the Catastrophic Flood of December 1966, North Rim Area, Eastern Grand Canyon, Arizona 1 GEOLOGICAL SURVEY PROFESSIONAL PAPER 980 .M X MAR l 6 1977 FEB 16 1977‘ Effects of the Catastrophic Flood of December 1966, North Rim Area, Eastern Grand Canyon, Arizona By M. E. COOLEY, B. N. ALDRIDGE, and R. C. EULER GEOLOGICAL SURVEY PROFESSIONAL PAPER 980 UNITED STATES GOVERNMENT PRINTING OFFICE. WASHINGTON : 1977 UNITED STATES DEPARTMENT OF THE INTERIOR THOMAS S. KLEPPE, Serretmj' GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Cooley, Maurice E. Effects of the catastrophic flood in December 1966, north rim area, eastern Grand Canyon, Arizona. (Geological Survey Professional Paper 980) Bibliography: p. 43. Supt. ot‘Docs. no.: I 19.16980 1. Floods—rrArizonaiGrand Canyon. 2. Erosion‘Arizonszrand Canyon. 1. Aldridge, Byron Neil,joint author. II. Euler, Robert C., joint author. III. Title. IV. Series: United States Geological Survey Professional Paper 980. GB1399.4.A6C66 551.4'8 76—608354 For sale by the Superintendent of Documents, U5. Gmernment Printing Office VVa'shington, DC. 20402 Stock Number 024—001—02930—8 CONTENTS Page Page Abstract __________________________________________________ 1 Effects of floods on the Kaibab Plateau, etc—Continued Introduction _______________________________________________ 1 Crystal Creek basin ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22 Purpose of the investigation and scope of the report ,,,,,, 3 Other areas ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22 Reporting of data ______________________________________ 3 Relation of scouring to flood depth ,,,,,,,,,,,,,,,,,,,,,,, 23 Acknowledgments ______________________________________ 3 Effects of floods in the tributary gorges of Grand Canyon—flood Physiographic setting ______________________________________ 3 of December 1966 and previous recent floods ,,,,,,,,,, 28 Hydrology of the flood of December 1966 _____________________ 4 Nankoweap Creek basin _________________________________ 25 Precipitation —————————————————————————————————————————— 4 Kwagunt Creek basin ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27 F100d areas ———————————————————————————————————————————— 6 Chuar Creek basin ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28 Magnitude 0f flOOdS ———————————————————————————————————— 6 Headwaters area ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28 Bright Angel Creek basin —————————————————————————— 10 Confluence of Natchi Canyon and Lava Creek ________ 28 Crystal Creek basin ________________________________ 12 Lava Creek, site 21 ________________________________ 29 Flood damage to modern structures ________________________ 12 Chuar Valley _________________________________________ 29 Relation of prehistoric and historic occupation to flooding ____ 15 Clear Creek basin ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 31 Archeological sites in the flood area ,,,,,,,,,,,,,,,,,,,, 16 Bright Angel Creek basin ______________________________ 31 Clear Creek .___________,"._1 _____________________ 16 Crystal Creek basin ____________________________________ 34 Crystal Creek ____________________________________ 16 Upstream from Hindu Amphitheater ,,,,,,,,,,,,,,,, 35 Shinumo Creek ____________________________________ 17 Hindu Amphitheater ______________________________ 38 Effects of floods on the Kaibab Plateau—flood of December 1966 Downstream from Hindu Amphitheater ____________ 39- and previous recent floods ____________________________ 17 Shinumo Creek basin __________________________________ 39 Clear Creek basin _______________________________________ 18 Mudflow at the mouth of Kanab Canyon ,,,,,,,,,,,, 39 Bright Angel Creek basin _______,Ur_, __________________ 19 Effects of streamflow _______________________________ 41 Thompson Canyon drainage ________________________ 19 Tapeats Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 42 Outlet Canyon drainage ____________________________ 21 Summary ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 42 References cited ____________________________________________ 43 ILLUSTRATIONS iiiiiiiiiii Page PLATE 1, Reconnaissance geology and location of mudflows, debris slides, peak-flow measuring sites, archeological sites, and erosional features, eastern Grand Canyon, Arizona ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, In pocket FIGURE 1. Map showing eastern Grand Canyon area and area of report ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2 2. Map showing location of precipitation stations near the Grand Canyon and precipitation data for December 3—7 in parts of northwestern Arizona, southwestern Utah, and southern Nevada ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5 3- Photograph showing gravel bar at site 15 in Nankoweap Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10 4. Photograph showing Shinumo Creek at site 54 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10 5. Graph showing frequency of annual peak discharges, maximum daily mean flows, and highest mean flows for 3 consecutive days, Bright Angel Creek near Grand Canyon 1, ___ _ ”11"",“1 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11 6 —18. Photographs showing: 6. Edge of the mudflow at the mouth of Crystal Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 12 7. Dragon Creek at site 46 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13 8. Crystal Creek above Dragon Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13 9. Debris slide along the Point Sublime Trail ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 14 10, Damage to structures in Bright Angel Canyon, flood of December 1966 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 14 11. Exposed pipeline near Ribbon Falls ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 14 12. Bright Angel Creek before and after the flood of December 1966 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 15 13. Damage to structures near the Phantom Ranch, flood of December 1966 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 15 14. Damage to the Phantom Ranch Campground, flood of December 1966 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16 15. Mescal pit (Ariz. B:16:6) damaged by the flood of December 1966 along Clear Creek ,,,,,,,,,,,,,,,,,,,, 17 16. Lower part of Dragon Creek (Ariz. 8:16:42) after the flood of December 1966 ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 18 17. Mudflow debris on the terrace on the right bank of Dragon Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 18 18. Walhalla Glades at site 26 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 19 19. Sketch map and photographs showing effects of the flood of December 1966 along Clear Creek tributary 3, Walhalla Plateau ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20 111 IV FIGURES 20-24. TABLE 25. 26. 27. 28. 29—34. 35. 36. 37. 38. 39. 40. 41. .10 CONTENTS Page Photographs showing: 20. Effects of the flood of December 1966 in Fuller Canyon, Kaibab Plateau ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 21 21. Erosion caused by the flood of December 1966 in Outlet Canyon, Kaibab Plateau ,,,,,,,,,,,,,,,,,,,,,,,, 22 22. Debris deposited by mudflows in Hindu Amphitheater and Natchi Canyon ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 24 23. Lobes of the light—colored mudflow that terminate in the vegetation on a low terrace in Natchi Canyon __ 25 24. Scar of the main mudflow~debris slide in Natchi Canyon ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 25 Sketch map and sections, Nankoweap Creek and Nankoweap Creek tributary __________________________________ 26 Photograph showing gravel—floored channel of Nankoweap Creek near site 15 after the flood of December 1966 H" 28 Sections along Kwagunt Creek near site 17 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29 Sections along the Natchi Canyon—Lava Creek drainage ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 30 Photographs showing: 29. Channels of Lava and Chuar Creeks after the flood of December 1966 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32 30. Bright Angel Creek 1,000 ft (305 in) above mouth ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 33 31. Mouth Of Bright Angel Creek after the flood of December 1966 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 33 32. Bright Angel Creek near Phantom Ranch before and after the flood of August 1936 ,,,,,,,,,,,,,,,,,,,, 34 33. Mudflow in Dragon Creek at the mouth of Dragon Creek tributary 2 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 35 34. Effects of the flood and mudflow of December 1966 in Milk and Dragon Creeks ,,,,,,,,,,,,,,,,,,,,,,,,,, 36 Sections along Dragon and Milk Creeks ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 37 Sketch map of main part of Hindu Amphitheater ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 38 Photograph showing Crystal Creek in May 1966 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 38 Photograph showing fan at the mouth of Crystal Creek in April 1967 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 39 Photograph showing mudflow at the confluence of Kanab Canyon and Modred Abyss ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40 Sections along Shinumo Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 41 Section along Tapeats Creek, looking downstream ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 42 TABLES Page Precipitation at selected stations near the Grand Canyon, December 3—7, 1966 __________________________________ 6 Channel conditions and estimated discharge at selected sites in eastern Grand Canyon, flood of December 1966 __ 7 Brief descriptions of the floodAof December 1966 and previous floods in the tributary gorges of the Grand Canyon“ 24 METRIC-ENGLISH EQUIVALENTS Multiply English unit By To obtain metric unit feet (ft) 0.3048 metres (m) square feet (ft2) .0929 square metres (m2) miles (mi) 1.609 kilometres (km) square miles (mi2) 2.590 square kilometres (kmz) acres .4047 hectares (ha) acre-feet (acre-ft) .001233 cubic hectometres (hm3) gallons (gal) .003785 cubic metres (m3) gallons (gal) 01242 cubic metres (m3) minute-foot (min-ft) minute—metre (min-m) feet per second metres per second (ft/s) .3048 (m/s) cubic feet per second cubic metres per second (ft3/s) .02832 (m3/s) inches (in.) 25.4 millimetres (mm) cubic feet per second cubic metres per second per square mile .01093 per square kilometre (ft3/s per mi?) (m3/s per km?) EFFECTS OF THE CATASTROPHIC FLOOD OF DECEMBER 1966, NORTH RIM AREA, EASTERN GRAND CANYON, ARIZONA By M. E. COOLEY, B. N. ALDRIDGE, and R. C. EULER1 ABSTRACT Precipitation from the unusual storm of December 1966 was con- centrated on highlands in northern Arizona, southwestern Utah, southern Nevada, and south-central California and caused widely scattered major floods in the four States. In Arizona the largest amount of precipitation was in the north rim area of eastern Grand Canyon; about 14 inches (360 millimetres) was measured at the North Rim Entrance Station. Evaluation of streamflow and flood-damage data from the Grand Canyon and the Kaibab Plateau indicates four distinct centers of high runoff; the largest area is along the south edge ofthe Kaibab Plateau and includes parts of Bright Angel, Clear, Lava, Kwagunt, and Nan- koweap Creek basins. Although most of the precipitation fell on the Kaibab Plateau, most of the flood damage occurred below the plateau, where the runoff was concentrated in stream channels that carried flow from the high runoff areas to the Colorado River. The other areas of high runoff were (1) Modred, Merlin, and Gawain Abysses in Shinumo Creek basin, (2) near the North Rim Entrance Station, and (3) near the ridge known as Cocks Comb in North Can- yon Wash and South Canyon basins. All the flood damage to structures was in Bright Angel Creek basin. At Phantom Ranch and elsewhere in Bright Angel Canyon, the flood damaged a new pipeline and buildings that had not been affected by previous floods. The largest amounts of streamflow occurred along Bright Angel Creek and the Milk Creek—Dragon Creek part of the Crystal Creek drainage basin. The most spectacular effects of the flood were along Milk Creek—Dragon Creek, where a mudflow caused extensive chan- nel modification and obliterated a prehistoric—about AD. 1100— Pueblo Indian mescal (cooking) pit. The flood event that occurred in the Crystal Creek basin has a recurrence interval of only once in several centuries. The flood in Nankoweap Creek may have been the largest that has taken place during historical times. Considerable flow and erosion took place along Clear Creek and damaged a prehis— toric mescal pit. Near the mouth of Shinumo Creek, an old campsite that was occupied in the 1890’s was not damaged; however, litter from the camp is present about 1 foot (0.3 metre) above the 1966 floodline. The most catastrophic effects of the 1966 flood were caused by two mudflows that extended from the edge of the Kaibab Plateau along Dragon Creek in the Crystal Creek basin and Lava Creek in the Chuar Creek basin to the Colorado River. More than 10 other large mudflows occurred in Nankoweap, Kwagunt, Crystal, and Shinumo Creek basins; possibly one other large mudflow occurred in Bright Angel Creek basin. In addition, about 80 large debris slides left conspicuous scars in the amphitheaters at the heads of the side gorges, and at least 10 small slides occurred on the Kaibab Plateau within the Grand Canyon National Park. The storm was not the first to cause a mudflow since the beginning of the 20th century. An older ‘Prescott College, Prescott, Ariz. mudflow, which may have occurred in 1961, is present along Tapeats Creek. The streamflow that resulted from the December 1966 storm on the Kaibab Plateau caused considerable local scouring and deep— ening of channels, including some renewed arroyo cutting. Before the flood, nearly all channels were mantled by dense stands of grass, which retarded erosion. The 1966 floodflow reopened old scours and formed new ones. The amount of scouring was roughly proportional to the maximum depth of the flow. Renewed arroyo cutting occurred mainly along parts of Walhalla Glades and Outlet Canyon. INTRODUCTION Precipitation during the unusual storm of December 1966 was concentrated on highlands in northern Arizona, southwestern Utah, southern Nevada, and south-central California and caused widely scattered major floods in the four States. In Arizona the largest amount of precipitation was in the north rim area of eastern Grand Canyon (fig. 1; pl. 1). Severe channel erosion accompanied the floods in Grand Canyon and damaged archeological sites dated A.D. 1050—1150 and modern facilities in Bright Angel Canyon. The most spectacular effects of the storm, however, were the mudflows and debris slides that occurred mainly in the amphitheaters at the heads of the gorges along the north rim. Mudflows in the Crystal and Chuar Creek drainage basins transported detritus from the north rim to the Colorado River. In many drainage basins the mudflows—the first documented in modern times in the Grand Canyon—and the extensive channel erosion indicate that the storm of December 1966 was a rare event. In 1967 a series of reconnaissance surveys was made to determine the amount of flood damage and the areal extent of the storm of December 1966 and the amount of channel modification resulting from this and earlier floods. In the Kaibab and Walhalla Plateaus and the platform between Marble Canyon and Kaibab Plateau, drainage areas were inspected where accessible by roads. An aerial reconnaissance was made of the west- ern slopes of Marble Canyon and the north slopes of Grand Canyon from Saddle Canyon on the east to Deer Creek on the west; along the tributaries of the Col— orado River, selected sites were investigated in detail 1 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA 112° l ”9%, Glen A «3); Canyon .Page L% / \ 6) Dam L9, Y W 1 _. ‘ G We .- a 2' . l \ / {.9 M Q 7:- KAIBITO PLATEAU .: "Q: S J K '( w“ 960 \0' C0 1% a 5 ‘e 23, s. x] - 0 Tuba '- 3 Vi” N‘s: . .i < L z/Moenkopt Wash Grand Canyon _/ — 116° 114° 112° Village /‘ F-- o 4' Cameron —— ~ 40° COCONINO 3 a 1‘} _ 38 Virgin. River' Lake Mead Gap 0 O _ 36 h 2 «0% Ii S ,‘0 .~ E \ 0P _ / «‘3‘9}/ 1 «V ' 5‘ _§ M0 lagstaff _ 340 9‘/ ~ ,5 943/ GOLL N\ NEW :3 3° Q’AND HAfigEl “‘ MEXICO U 9 Phoenix .PROV’NCE \thIZ | — 32° \ 0 S " Mega . L" O \___|___L__‘ 0 100 ZOOMILES . Williams 0 100 200 300 KILOMETHES . Flagstaff EXPLANATION —§— MONOCLINE — Showing trace of axial plane I O 10 2O 30 40 MILES IL 1 II I I I l l II J O T 10 20 30 4O 50 60 Kl LOMETRES FIGURE 1.—Easte1"n Grand Canyon area and area of report. PHYSIOGRAPHIC SETTING 3 on the ground, and indirect discharge measurements were made at a few of the sites. PURPOSE OF THE INVESTIGATION AND SCOPE OF THE REPORT The purpose of this investigation was to reconstruct the components of the flood of December 1966 in east- ern Grand Canyon as indicated by field evidence and to obtain the information necessary to document an extreme hydrologic event in a semiarid environment. Although there is evidence of previous mudflows in eastern Grand Canyon, no documentation of the phe- nomenon exists in the literature on hydrology or geomorphology in Arizona. This report describes the distribution and magnitude of precipitation, streamflow, and channel modification that resulted from the storm of December 1966 and documents the mudflows that resulted from the 'flood. The report relates the effects of the flood to those of previous known floods and to the prehistoric and his— toric occupation of the Grand Canyon. REPORTING OF DATA The US. Geological Survey has adopted the policy of reporting data in metric units in combination with English units. For this report, metric units are given in parentheses following English units in the text, and English and metric units are shown on the illustrations. The data in the tables are given in English units only. ACKNOWLEDGMENTS The authors are grateful for the storm-damage in— formation contributed by H. B. Stricklin, former superintendent of the Grand Canyon National Park, and other National Park Service personnel. The au- thors also are grateful to G. L. Beck and P. W. Huntoon, geologists, who furnished many spring loca- tions, and to G. L. Beck who furnished photographs of the flooded area for study. Substantial assistance, especially in the location of mudflows during flights, was given by Wayne Learn and Norman Browning of Tusayan Helicopters. R. C. Euler gratefully acknowl— edges the support of the National Science Foundation (Grant GS—1078) in his Grand Canyon archeological project, of which the present study came to be an unex- pected yet valuable part. PHYSIOGRAPHIC SETTING The eastern Grand Canyon area is in the southwest- ern part of the Colorado Plateaus physiographic prov- ince in Arizona (fig. 1). The area consists of the Grand Canyon, its northeast extension Marble Canyon, and the tributary Little Colorado River Gorge (pl. 1). These physiographic features form a canyon system that is excavated to a maximum depth of about 1 mi (1.6 km) below huge rock terraces called plateaus and plat- forms. The highest terrace is the Kaibab Plateau, which borders the north rim of the Grand Canyon; the altitude of the plateau generally ranges from 7,000— 9,000 ft (2,100—2,700 m) above mean sea level. The Coconino Plateau is south of the Grand Canyon, has a gently sloping surface, and is at altitudes of 6,400— 7,200 ft (1,950—2,190 m). Marble Platform borders the Little Colorado River Gorge on the north and Marble Canyon on the east; the altitude of Marble Platform ranges from 5,400—6,100 ft (1,650—1,860 m) above mean sea level. A similar but smaller platform is pres— ent between Marble Gorge and the Kaibab Plateau. Below the surrounding rock terraces, the Colorado River descends from about 2,870 ft (875 m) at Vaseys Paradise, to 2,700 ft (823 In) at the mouth of the Little Colorado River Gorge, to 1,930 ft (588 m) at the mouth of Deer Creek—a distance of 104 river miles (167 km). Tributaries t0 the Colorado River occupy side gorges that head into the north and south rims of the Grand Canyon, where gigantic amphitheaters have been carved (fig. 2). The floors of the amphitheaters are 2,000—3,000 ft (600—900 m) below the adjacent canyon rims. The gorges of the large drainage areas, such as Nankoweap and Bright Angel Creeks, slope rather uniformly from the amphitheaters to the Colorado River. The eastern Grand Canyon area is characterized by a wide range in climate—from semiarid in the canyon to relatively humid on the Kaibab and Coconino Plateaus. The canyon cuts across an extensive oro- graphic barrier that extends northwestward from west-central New Mexico‘a‘long the Mogollon Rim and Coconino and Kaibab Plateaus to the high plateaus of southern Utah (fig. 1). In the eastern Grand Canyon area the amount of precipitation increases with in- creasing altitude owing to the orographic effect exerted by the Kaibab Plateau; storms tend to be concentrated on the windward southern part of the plateau between Pleasant Valley and the north rim of the Grand Canyon (pl. 1). This part of the area includes the crest of the Kaibab Plateau, and precipitation probably is between 25 and 30 in. (640 and 760 mm) per year. During 1931— 60, the mean annual precipitation at the Grand Canyon National Park station on the south rim, which is at an altitude of 6,890 ft (2,100 m), was 14.77 in. (375.2 mm). (See US. Weather Bureau, issued annually.) 4 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA The classical Grand Canyon section includes Pre- cambrian basement and sedimentary rocks and Paleozoic strata; the Paleozoic strata include the Tapeats Sandstone at the base and the Kaibab Lime- stone that forms the rim of the canyon (pl. 1). The Paleozoic strata are superbly displayed in the eastern Grand Canyon area, where the rocks outline a series of vertical-faced benches of resistant sandstone, lime- stone, or talus-strewn slopes that are on shaly rocks set back at different levels between the Colorado River and the enclosing rock terraces. The entire Paleozoic section is exposed throughout the area and ranges in thickness from about 3,500 ft (1,070 m) at the mouth of the Little Colorado River to 4,000 ft (1,220 m) near Shinumo Creek. The escarpments in Grand Canyon present a favor- able environment for the thawing and freezing action that accelerates mechanical weathering of rocks. Seepage from melting snow furnishes much of the moisture for the frost-wedging action along the canyon rims. The frost action is aided by the highly fractured nature of the rocks, which allows large blocks of rock to fall easily from the cliffs and accumulate as talus on the lower slopes or in the stream channels in the subja- cent gorges. HYDROLOGY OF THE FLOOD OF DECEMBER 1966 The storm that caused the unusual flood of December 1966 in Grand Canyon was the southeastern extension of a regional storm that started December 3 and lasted through December 7. The storm moved northeastward from the Pacific Ocean across the southwestern United States. The large amounts of precipitation caused major floods in the mountainous areas of south-central California (Dean, 1971), in southwestern Utah (Butler and Mundorff, 1970), and in parts of southern Nevada and north-central and central Arizona (Aldridge, 1 97 1). PRECIPITATION Few rainfall data are available for the eastern Grand Canyon area during or immediately preceding the storm of December 1966, because the precipitation gages had been converted to storage gages for the winter at Bright Angel Ranger Station and North Rim Entrance Station—the only stations in the area that had large amounts of precipitation. The precipitation stations along the south rim are not within the area of intense precipitation, which centered along the north rim and the crest of the Kaibab Plateau (fig. 2). From November 1 to December 7, 17 in. (430 mm) of precipitation fell at the North Rim Entrance Station (table 1). National Park Service personnel estimate that a maximum of3 in. (80 mm) was from November storms and that at least 14 in. (360 mm) was from the December storm. The gage at the Bright Angel Ranger Station was not read between October 1966 and May 1967; however, in the period between readings, this gage caught 83 percent of the amount caught at the North Rim Entrance Station in the same period. Ap— plying the same percentage to the storm of December 1966, 11 or 12 in. (280 or 300 mm) probably fell at the Bright Angel Ranger Station. During the storm of December 1966, the operating recording precipitation station closest to the eastern Grand Canyon area was at Tuweep, Ariz., west of the Kaibab Plateau. Precipitation started shortly after 0100 hours on December 3 and continued until 2100 hours (US. Weather Bureau, 1967a); it resumed about 1800 hours on December 4 and, except for about 3 hours, continued until 0400 hours on December 7. The times of rainfall at the Tuweep station, however, may not correspond with those in the eastern Grand Can— yon area, as indicated by radar-echo maps of storm cells during December 3—6, 1966 (Butler and Mundorff, 1970, pl. 2). The maps show only a few small storm cells over the eastern Grand Canyon area, and they were present at times different from those over Tuweep. The cells appear to have remained over the eastern Grand Canyon area for very short periods; the time, location, and description of the cells are given in the following tabulation. TIYIIE (hours! Day 0735 December 3 Description Two cells: One extended from about the North Rim Entrance Station eastward across the Kaibab Plateau to the headwaters of Saddle Canyon, and the other was over the south- eastern tip of Walhalla Plateau. One very small cell near the Bright Angel Ranger Station. One long narrow cell that extended from the Bright Angel Ranger Station to the Utah border. Between 0615 and 0735 hours, the cell over the Bright Angel Ranger Station-Utah bor- der area moved northward, and another cell moved in over the headwaters of Bright Angel Creek. One small cell near Cocks Comb at the head of North and South Canyons. 1 735 December 3 0615 December 5 0735 December 5 0935 December 5 1735 December 5 One very small cell over the north rim. 1135 December 6 One small cell over Powell Plateau. 0800 December 6 No cells in the eastern Grand Canyon area. 0935 December 6 No cells in the eastern Grand Canyon area. Radar-echo data are not available between 1735 hours on December 5 and 0800 hours on December 6 (Elmer Butler, oral commun., 1968), the period of most rapid rise in stage at the Bright Angel Creek gaging HYDROLOGY OF THE FLOOD OF DECEMBER 1966 114° 723° 119° 115° 111° 41" NEVADA 39» 37B CALIFORNIA 306‘ o 35 ARIZONA 33° [/25] U 200 400 MtLES \ "I279! i‘erL1—FL7'L1—‘IJ 2/51; \§§ 152,711”; 2,5,1 0 200 400 600 KILOMETRES § \:§ 51203; ’00:}‘2‘9 ’ c 4’5; § \ © 1012541 10l254l® .3; w I \ a g I \§ I § A St George ‘ 1 Q6‘ = 1 § 3 __Y~ ___UTAH____ Q? *r _ — . ARIZONA g get 3 E’ qé ,4: 611521 11‘: 411021 6 o I \ 50° ‘\\\1 A 4 o 1‘ 0 $130" .1152) §\\§\\®2} W“ 131330) ’//‘ Q§§\~'.J)J»rli’ 2151) 5 “\\\‘\I @5027) /_ \‘S—é/é" DLas Vegas \ \ ‘ «I» O ‘16 0; QVVO O \ .7 “9 vs ®\ '7 a \ \\ Flagstaff ”96 . \\ ) / ljngman EXPLANATION \‘ 317s; LINE OF EQUAL PRECIPITA- TION — Interval 1 inch (2 5 .4 mm) .2 RAINFALL MEASUREMENT SITE — Number corre- sponds to that in table 1 Williams Precipitation lines by U.S. Geological Survey; data from U.S. Weather Bureau. 19 67 11:19 6 7b; and Butler and Mundorff. 1 9 7 0 O I | 0 FIGURE 2.—Location of precipitation stations northwestern A 50 100 MILES 1 1 1 50 100 150 KILOMETRES near the Grand Canyon and precipitation data for December 3—7 in parts of rizona, southwestern Utah, and southern Nevada. EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA TABLE 1,—Precipitation at selected stations near the Grand Canyon, December 3—7, 1966 [T. trace. Data from US. Weather Bureau (19673)] [5:351:19] Altitude Precipitation, in inches ment site (feet above ‘ ~74 1:063:95) Station 5631135221) wig/232:1 Dec. 3 Dec. 4 Dec. 5 Dec. 6 Dec. 7 Total 1 Colorado City ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5,010 Sunset 0 0.51 1.01 1.66 0.27 3.45 2 Fredonia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4,675 Sunset .88 .10 .97 .92 .40 3.27 3 Pipe Springs National Monument ,,,,,,,,,, 4,920 Sunset .61 .10 .56 .21 .54 2.02 4 Mount Trumball ,,,,,,,,,,,,,,,,,,,,,,,,,, 5,560 1900 .35 .33 (1) 1.50 .75 2.93 5 Tuweep ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4,775 2400 .77 .24 1.39 3.57 .08 6.05 6 Jacob Lake ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7,920 1800 (1) (1) (1) 6.60 0 6.60 7 Supai ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3,205 1700 40 .33 .11 .15 59 1.58 8 North Rim Entrance Station ,,,,,,,,,,,,,, 8,780 ___1 W“ W" ,-__ ,___ “u 214 9 Bright Angel Ranger Station ,,,,,,,,,,,,,, 8,400 A", ,,__ ,___ “h ___, __,, 312 1O Phantom Ranch ,,,,,,,,,,,,,,,,,,,,,,,,,, 2,570 k" .04 1.02 36 .32 34 2.08 11 Grand Canyon National Park ,,,,,,,,,,,,,,, 6,965 1700 .30 1.15 1.69 1.01 .50 4.65 12 Grand Canyon Airway ,,,,,,,,,,,,,,,,,,,, 6,971 2400 1.08 .42 1 60 .56 33 3.99 13 Frazier Well ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6,500 H" ,c__ ,___ ___, ___1 __-, 45 14 Page ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4,270 2400 .23 .01 0 .33 12 .69 15 Wahweap ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3,728 1700 .24 .08 .01 0 0 .33 16 Lees Ferry ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3,210 Sunset .12 T .02 .17 .45 .76 17 Cedar Ridge Trading Post ________________ 5,920 1800 .37 T T O 0 .37 1Included with next reading. 2November 1 to December 7, 17 in.; October 1966 to May 1967. 25.6 in. ”October l966 to May 1967. 21.2 in. ‘Novemher l to January 3, 6.05 in. station. Therefore, it appears that the period of most intense rainfall—at least in Bright Angel Creek basin—was not covered by radar-echo maps. The de- termination of flood times along ungaged and uninhab- ited drainages cannot be pinpointed closer than during December 5—7. At the time of the storm, the estimated snow depth was less than half a foot along the north rim of the eastern Grand Canyon, zero at the precipitation sta- tion at Grand Canyon National Park on the south rim, and zero at Jacob Lake. Only a trace of snow fell at the Grand Canyon station during the storm. It can be in- ferred from weather records that the soil probably was moist but not saturated. The last large amount of pre- cipitation preceding the storm fell as snow on November 8—9. Only a few hundredths of an inch of precipitation fell between November 9 and December 3. Daytime temperatures were sufficiently high to cause melting of any snow but not sufficiently high to cause rapid melting, which would saturate the soil. FLOOD AREAS An evaluation of streamflow and flood-damage data for the Grand Canyon and the Kaibab Plateau indi- cates four distinct areas of high runoff (pl. 1). The largest area is a 5—7-mi-wide (8—11-km-wide) band along the southern edge of the Kaibab Plateau. The area extends from the headwaters of Crystal Creek basin eastward along the north rim to the headwaters of Nankoweap Creek basin and includes the upper parts of Bright Angel, Clear, Lava, and Kwagunt ba- sins. Although this area had the largest floodflow, the amount was not uniform throughout the area. The drainages in upper Outlet and Fuller Canyons in the Bright Angel Creek basin had high peak discharges, whereas little flow occurred along the main stems of upper Bright Angel Creek and Crystal Creek upstream from the edge of the Kaibab Plateau (table 2). The other three areas that had high runoff are (1) Modred, Merlin, and Gawain Abysses in Shinumo Creek basin, (2) near the North Rim Entrance Station where the Shinumo Creek, Bright Angel Creek, and North Canyon Wash basinsjoin, and (3) near the Cocks Comb in the North Canyon Wash and South Canyon basins. In the area around the North Rim Entrance Station, high runoff is manifested by the road damage and by evidence of flow in all the channels that drain the area. The area flooded probably was quite small— an estimated 14 mi2 (36 km2)—-—and little runoff reached the rim of the Kaibab Plateau or contributed to the flow in the area below the plateau. Aerial inspection of Unkar, Vishnu, and Saddle Creeks and the many minor tributaries to the Colorado River that head below the rim showed little evidence of flood damage. Little evidence of flow was found in the stream channels in and adjacent to the Coconino Plateau south of the Colorado River. MAGN ITUDE OF FLOODS The unit runoff—the amount of runoff per square mile—that occurred during the flood of December 1966 is relatively small when compared to the unit runoff in other parts of Arizona; however, the unit runoff is ex- tremely high for the eastern Grand Canyon area. An inspection of the general area indicated that some streams had the largest flows of any that have taken HYDROLOGY OF THE FLOOD OF DECEMBER 1966 7 TABLE 2.——Channel conditions and estimated discharge at selected sites in eastern Grand Canyon, Flood of December 1966 [Channel properties were studied in detail at the six slope-area measurement sites; elsewhere, channel width, depth, and discharge values were estimated by visual inspection or ap- proximate measurement. For broad U-shaped channels, top widths were measured at the cross sections that were used to estimate discharge; for narrow U-shaped channels, an average width is given. Channel depth generally is the maximum depth above channel bottom. For channels having shallow overflow areas, the properties listed are for the main channel; at some sites, channel properties were determined using the average of measurements at several sections. Velocities used to compute discharge were estimated from the measured ve- locities of similar streams outside the Grand Canyon area; the values are approximate but are sufficiently accurate to indicate the order of magnitude of flow. Height of terrace or terracelike feature above streambed: B, channel cut in bedrock; D, ditch; H, depth of channel below headcut; J, discontinuous channel; M, channel modified by manmade structure; <, less than; >, more than; /, separates different terrace levels] Estimated discharge 'Height of terrace Site Cubic Cubic feet or terracelike number Drainage Channel Channel feet per second feature above (located area width depth per per square streambed on pl. 1) Stream (mi?) (ft) (ft) second mile (ft) Channel description North Canyon Wash basin 4.11 15 0.3 4 110 Upper North Canyon ,,,,,,, 24.6 10 4 800 132 North Canyon Wash ,,,,,,, (TH—A NH 3 Upper Tater Canyon ,,,,,,,,,,,,,,,, 5.82 25 1.5 . 85 15 3 ,,,,,, do _,,,,__,,,A_,,,,._ Tater Canyon ,,,,,,,,,,,,,, 01% 6 Pleasant Valley outlet ,,,,,,,,,,,,,, 7.24 , ,, (2) ,, <1 Mainly grass»covered flood plain. Channel irregular and controlled by sagebrush and other brushy vegetation. Channel was widened and deepened about a foot during the 1966 flood. Upstream from site 2, gravel bars restrict the channel and cause from 2 to 3 ft of local lateral cutting and overflow on the adjacent flood plain. Discontinuous gully less than 3 ft deep; the 1966 flood caused minor erosion; some gullies in Del Motte Park were extended 173 ft headward. Grass-covered flood plain. Channel irregular and controlled by sagebrush and other brushy vegetation; slightly affected by the 1966 flood. Grass-covered flood plain; few limestone sinkholes. South Canyon Wash basin South Canyon ,,,,,,,,,,,,,,,,,,,,,, 6165 25 1.5 200 30 South Canyon tributary 1 ,,,,,,,,,, 5.83 9 3 250 42 <3/&6/15—16(7) 2/4e5/7/14C7) mu 173/5—6 3‘3 ‘/2/ 8 9 South Canyon tributary 2 ,,,,,,,,,, 3.47 10 1 75 22 10 Fence Canyon ,,,,,,,,,,,,,,,,,,,,,, 5.24 15 2.5 200 38 11 Fence Canyon tributary ,,,,,,,,,,,, 6.25 28 2.2 250 40 4 12 Wildcat Canyon ,,,,,,,,,,,,,,,,,,,, 10.9 20 3 350 29 13 Wildcat Canyon tributary ,,,,,,,,,, 1.3 ,_ c, (2) ,, 2—3/6/8 2—3/5 Channel shows slight effects of the 1966 flood. Channel slightly to moderately affected by the 1966 flood; most of the streamflow in South Canyon Wash basin was along this tributary. Part of the alluvium that forms the 445-ft-high terrace contains abundant charcoal and carbonaceous material. The alluvium was derived from an area denuded by a forest fire in the headwaters of the drainage; the fire occurred in 1960 and burned about 9,000 acres (C. M. Fauley, Park Forester, oral commun., 1968). Channel not affected appreciably by 1966 flood. The flood in the summer of 1967 deepened the channel more than the flood of 1966; in places lateral cutting has removed less than 5 ft of gravel from the sides of the 8-ft terrace; gravel bars in the straighter and wider parts of the channel caused overflow on the 373%»ft-high terrace, Gravel bars were deposited in the channel by the 1966 flood; some vertical banks were cut. Channel moderately affected by the 1966 flood. Channel swept relatively clean by a pre-1966 flood; root crown of a 3-ft-diameter juniper along the streambed indicates that the channel depth has been stable for the last few centuries. Buck Farm Canyon basin 14 Buck Farm Canyon Wash ,,,,,,,,,, 2.57 7 2 100 39 2—3 Channel irregular and controlled largely by sagebrush and juniper. The channel was little affected by the 1966 flood, although some scouring occurred; flow filled a 6—ft-wide channel of a tributary to Buck Farm Canyon Wash to a depth of only a foot. Nankoweap Creek basin 15 Nankoweap Creek ,,,,,,,,,,, 1.. 16.4 80 5 3,000 183 5—6(?)/8/1 4 16 Nankoweap Creek tributary ,,,,,,,, 7,16 50 3.5 800 112 3—4 Channel modified by the 1966 flood. Channel partly modified by the 1966 flood. Channel was straightened and smoothed and loose rocks and brush were removed; in places the flow moved through flood channels or chutes, thereby shortcutting meanders; minor lateral cutting. Kwagunt Creek basin 17 Kwagunt Creek ,,,,,,,,,,,,,,,,,,,, 4.67 50 4.5 1,200 260 4/7‘8/11/17718 Channel modified by the 1966 flood. Chuar Creek basin 18 Chuar Creek 313 <10 0.1 <05 3: 19 Lava Creek ,,,,,,,,,,,,,,,,,,,,,,,, 3,18 40 4 ,, 2—3/5/8/12/30 20 Natchi Canyon ,,,,,,,,,,,,,,,,,,,, 3.45 50 16 , A 4 12/15/23 21 Lava Creek _______________ 9.03 15 6 800 389 5—6/15—18/25 See footnotes at end of table. Channel was not modified by the 1966 flood. The flood of 1966 caused considerable scouring and dep- osition of gravel bars; brush protected the sides of the channel from extensive erosion; century plants grow» ing on the 3-ft and higher terraces indicate that the terraces are not flooded often, Mudflow caused by the 1966 flood severely modified channel. Mudflow caused by the 1966 flood slightly modified channel. 8 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA TABLE 2.—Channel conditions and estimated discharge at selected sites in eastern Grand Canyon, flood of December 1966—Continued Stream area lmin 1ft» Drainage Channel width Estimated discharge 7' ’7 'i 'Height of terrace Cubic Cubic feet or terracelike Channel feet per second feature above depth per per square streambed ifti second mile lftl Channel description Clear Creek basin 22 23 24 25 26 Clear Creek tributary 1 "H ,,,, Clear Creek tributary 2 . ,,,. , H. Clear Creek tributary 3 ,,,,,,, , . ,.. Walhalla Glades". ”W"... H W, 0.15 <1 1 None Grass-covered flood plain, 1 35 41 (1 Grass-covered flood plain: the 1966 flood cut a few ir- regular scours that are 1 ft deep and as much as 4 ft wide and 20 ft long. 2 350 97 2 The 1966 flood deepened old scours, formed new scours, and deposned gravel bars; most scours are less than 2 ft deep, 6 ft Wide, and 20 ft long: two large scours are 100 and 300 it long; one large gravel bar is about 100 ft long and has a maXimum thickness of 1‘: ft. 2 20 15 <2 The 1966 flood Cut a few scours less than '2 it deep and 3 ft long; ponderosa pine root crowns “2—2 ft in diameter occur along the streambed. 1.7 ~‘66 15 1/1‘e—2 The 1966 flood cut shallow scours and deposited a few thin poorly formed gravel bars: the scours generally are from 1 to 1% ft deep, 4 ft wide, and about 6 ft long: however, one scour is 50 ft long. Bright Angel Creek basin 27 28 29 30 31 32 33 34 35 36 Bright Angel Creek ..,,,, . ,,,,, ,, Bright Angel Creek tributary. ,,,,, Thompson Canyon ,,,,, ,,,. ,. ,,,, 0 ,,., ,,,,,,,,,,,,,,,,,,, Thompson Canyon ,,,H.. ,,,.s...,, The Transept tributary ,,,,,,,,,,, Outlet Canyon... .,,,, ,,,,,, ,,., Outlet Canyon tributary 2 ,,,,,,, ., Bright Angel Creek ,,,,,, .,,s.. W .96 2.02 101 80 40 25 60 0.2 0.2 <0,1 <1 Flood plain and channel contain shallow discontinuous depresswns covered by grass; the 1966 flood caused minor erosion but did not cut any new scours. 8 >100 <1 Grass»covered flood plain. 12) 1, <1 Grass-covered flood plain: no appreciable erosion during the 1966 flood or other recent floods. 10 4 3MH The 1966 flood renewed scouring in an old healed gully. 4167 548 5D The 1966 flood caused minor erosion in a grass-covered ditch. 150 6 374/7H The 1966 flood caused some scouring and lateral cutting. A pile of flood debris consists mainly of logs; the logs are at angles ofas much as 45° in the lower part ofthe pile and indicate a conduit or sinkhole in the stream- bed near Bright Angel Spring; the debris pile inter- cepted part of the streamflow, which may have re- charged Roaring S rings. .5 7 7 <1 Grass—covered flood p ain; the effects ofthe1966 flood are negligible. ,, 174MJ During the 1966 flood, grass—covered channels were filled to depths of about a foot, which caused minor scouring and deposition of a few thin bars and some lag gravel: a prominent scour near the head ofthe canyon about 2 mi upstream from site 34 and at least one scour in Upper Little Park were present before the 1966 flood and indicate that this area was less affected by the 1966 flood than by other recent floods. 4 ‘414 644 2'3/5l/2711 The 1966 flood moderately affected the channel, which is fairly straight; the flood cut new scours 1 ft deep and 30 to 50 feet long in the bottom of the grass—covered channel. 2.5 80 160 3 The 1966 flood was confined mainly to gullies eroded before 1966. The flood deepened old gullies, cut new scours, eroded the roadbed of Point Sublime Trail, and deposited some gravel. New scours are present in about 20 percent of the channel; some of the new scours are as much as 5 ft deep. In the broad meadow upstream from where the Point Sublime Trail crosses the channel effects of the 1966 flood are negligible. 6 44,000 40 6—8 The 1966 flood caused major channel modification and lateral cutting. ,_‘ .e 9% vi we. Crystal Creek basin 38 39 40 41 42 43 44 45 46 Dragon Creek ...... H . . ,,,,, MilkCreek ,, ..,., H, "W Milk Creek tributary ,,,,, ,,,, Milk Creek ..... ,,,. ..,,.. Dragon Creek tributary 1 ,. . , ,.,. Dragon Creek tributary 2 Dragon Creek , .. H . . See footnotes at end oftable. 4.58 1.38 .44 6.82 4.19 1.57 19.2 15 45 20 60 15 10 60 2 12 5 1-3 Grass-covered channel and flood plain; the 1966 flood caused minor scouring, and much of the channel and canyon floor was essentially undisturbed. 3 100 9 2/1042 The 1966 flood caused some scouring and deposition of gravel bars in the channel and flood plain, which are covered by vegetation, in places 6-ft-high terraces were inundated; scours generally are #10 ft long and 1—2 ft deep; maximum lateral cutting was 3 ft. 8 1,000 220 7/12/15/25-26 The 1966 flood modified the channel, eroded low flood terraces, and removed vegetation. 2 120 87 <2J The 1966 flood cut a few scours as much as 1% ft deep, 4 ft wide, and 10 ft long in the grass-covered discontinu- ous channel; a Considerable part of the flow was from an east.flowing tributary. 2 30 68 1—2/&4 The 1966 flood caused minor scouring in the partly grass-covered channel. 25 . , . 12/35: Mudflow caused by the 1966 flood severely damaged the channel. 3 40 10 .16 Channel slightly modified by the 1966 flood. <5 10 6 <5 Channel was not modified by the 1966 flood, however, a 12-ft dropoff was cut at the mouth by Dragon Creek. 20 429,200 (7! 14—16/25 ivIudflow caused by the 1966 flood severely damaged the Channel. HYDROLOGY OF THE FLOOD OF DECEMBER 1966 TABLE 2.—Channel conditions and estimated discharge at selected sites in eastern Grand Canyon, flood of December 1966—C0ntinued Estimated discharge Cubic ‘lieight of terrace Site Cubic feet or Lerracelike number Drainage Channel Channel feet per second feature above llocated area width depth per per square streambed on p]. 1) Stream Imi2r ifti (ft) second mile (ft) Channel description Tuna Creek basin 47 Walla Valley Wash ,,,,,,,,,,,,,,,, 8.27 3 0.25 <1 01 <1 Grass-covered flood plain has a local relief of less than 1 ft. 48 Walla Valley tributary ,,,,,,,,,,,,,, .77 3 .1 <5 .6 <2 Channel and flood plain covered by grass and litter. Shinumo Creek basin 49 Big Spring Canyon ,,,,,,,,,,,,,,,,,,, 5.97 25 1.5 25 5 <1 The 1966 fluod cut a few scours in the grass-covered flood plain, which has discontinuous channels less than 2 ft deep. 50 Tipover Canyon ,,,,,,,,,,,,,,,,,,,, 5.42 3 1 4 .8 2 The 1966 flood caused minor scouring and deposition of small gravel bars in the discontinuous pre-1966 ar- royo; in places the arroyo is as much as 6 ft deep. 51 Kanab Canyon ,,,,,,,,,,,,,,,,,,,,,,, 5.16 25 l 15 3 <1 Grass-covered flood plain; effects of the 1966 flood are negligible. 52 Kanabownits Canyon ,,,,,,,,,,,,,,, 9.75 20 1 <100 10 2 The 1966 flood washed out the road in places and scoured the channel. The pre-1966 channel was 1 to 2 ft deep and generally was less than 5 ft wide; the 1966 flood- flow cut scours 3 ft deep, 5 ft wide. and as much as 30 it long. 53 Kanabownits Canyon tributary eeeeee 1.38 H H (21 , <1 Grass-covered flood plain: little evidence of recent streamflow is apparent. 54 Shinumo Creek ,,,,,,,,,,,,,,,,,,,, 67.4 50 6 41,660 “24.7 46/10 The 1966 flood caused only minor scouring because the dense riparian vegetation protected the channel from erosion. 55 White Creek ,,,,,,,,,,,,,,,,,,,,,,,, 14.4 20 2.5 120 8 4—5/8 The 1966 flood was not as large as a previous flood. Tapeats Creek basin 56 Quaking As n Canyon ,,,,,,,,,,,, 9.38 H H (2) ,, 1 31/2H A Fire-1966 arroyo does not show evidence of recent flow. :_ Crazy Jug anyon tributaries. (9) H H H H <5»<5B 07 Browns Canyon eeeeeeeeeeeeeeeeeeee 223 2-5 L5 5 2 <1 Grass and reed-covered flood plain; dense vegetation pro- tected the channel from erosion during the 1966 flood. 58 Tapeats Creek ,,,,,,,,,,,,,,,,,,,,,, 82.7 30 2 400 5 5/8—10/30: The 1966 flood was not as large as previous floods. Deer Creek basin 59 Deer Creek ,,,,,,,,,,,,,,,,,,,,,,,, 16.7 25 3,5 300 18 2fi4/7/10/19720 Channel only slightly modified by 1966 flood owing to the dense riparian vegetation: the flood eroded and enlarged scours from 1 to 3 ft deep and less than 12 ft long. Kanab Creek basin 60 Lookout Canyon ,,,,,,,,,,,,,,,,,,,, 10.3 H H (2) H <1 Grass-covered flood plain. 61 Dry Park Wash ,,,,,,,,,,,,,,,,,,,, 5.96 H H (2) , <1 Do. 1Upper part of basin did not contribute runoff to the flood. Unit runoff from the contributing area probably was at least 60 fth per mi? 2No high watermarks or other flood evidence were found. If flow did occur, the amount was very small. 3All water was from Natchi Canyon and Lava Creek above Natchi Canyon—fa combined drainage area 6.63 mi? Unit runoff from this area probably was more than 120 ft3/s per miz. 4Discharge measurm by slope-area method. 5Most of the flow was from about 0.6 mi2 of the drainage area. Unit runoff was about 300 ft3/s per mi? 6Upper part of the basin contributed very little runoff to the flood. Unit runoff from the contributing area probably was more than 70 fials per miz. 7Unit runoff was not applicable because a large percentage of the flow was rock and mud. BFlow was from the lower half of the basin. Unit runoff from the contributing area ranged from 50 to 100 fth per miz. 5Aerial inspection showed no evidence of high flows in Parissawampits, Locust, or Timp Canyons or in other tributaries to Crazy Jug Canyon.The area was not inspected on the ground. place in the last few hundred years. Gagging-station records for Bright Angel Creek show that the mag- nitude of the peak discharge was not as unusual as the volume of flow during the flood period. Many mudflows and debris slides accompanied the large flows in the uninhabited gorges in Nankoweap, Kwagunt, Lava, Clear, Crystal, and Shinumo basins (pl. 1; table 2). The flood at site 15 in Nankoweap Creek (pl. 1; fig. 3) had an estimated peak discharge of 3,000 ft3/s (85 m3/s) and may have been the largest flood along this drainage in historical times. Mudflows and debris slides that originated in the upper drainage area of Lava Creek caused severe changes in channel geometry. Site 21 in Lava Creek had an estimated peak discharge of 800 ft3/s (20 m3/s), most of which came from the 6 mi2 (16 km2) above the confluence of Lava Creek and Natchi Canyon. Although a large unit runoff occurred from the high headwaters of Kwagunt Creek, the 1966 flood was not an exceptional event in this drainage. Considerable erosion took place along Clear Creek, where the discharge probably greatly ex- ceeded that from Walhalla Plateau (table 2). Little runoff from the headwaters of Big Spring, Kanab, and Kanabownits Canyons reached Shinumo 10 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA FIGURE 3.——Gravel bar at site 15 in Nankoweap Creek. View looking upstream. Height of bar (indicated by lines at base and top of bar) averages 5—6 ft (1.5»18 m). Creek. Flood evidence indicates that less than 10 per- cent of the 1,660 ft3/s (47.0 m3/s) measured at site 54 in Shinumo Creek (fig. 4) came from the Kaibab Plateau. The flows above site 54 were mainly from precipitation on the canyon walls surrounding Modred and Merlin Abysses. At the old campsite of Bass near the mouth of Shinumo Creek (pl. 1), floodmarks indicate a maximum flow depth of only a few feet, but floatable camp debris less than 1 ft (0.3 m) above the floodmarks indicates that the flood may have been the highest since the camp was abandoned in about 1900. Regional flood-frequency studies indicate that a flood of this magnitude has a recurrence interval—the average number of years, during a long period of time, in which a given discharge will be equaled or exceeded—of al- most 20 years. The recurrence interval is a measure of the magnitude of a flood and does not indicate the amount of time between such floods. The recurrence interval may be obtained from an analysis of data col- lected at a particular site or from a regional flood- frequency analysis. In this study the log—Pearson Type III distribution (Benson, 1968) was used for the analysis of station data. Considerable runoff occurred in the area along the Cocks Comb in the drainage basins of North and South Canyons (table 2); however, the height of the flood- marks relative to the height of the low terraces in these canyons indicates that the peak discharge was not unusual. For example, in the Fence Canyon drain- age basin the debris marks of a flood that occurred in the summer of 1967 are at about the same level as those of December 1966. FIGURE 4.—Shinumo Creek at site 54. View looking upstream. The crest of the flood (indicated by level rod) was about 51/2 ft (1.7 In) above the creekbed and did not inundate the terraces 6 ft (1.8 m) above the bed. At this site, the floodflow cleared only the bed be— cause the sides of the channel and the terraces were protected by dense riparian vegetation. BRIGHT ANGEL CREEK BASIN Bright Angel Creek and the Colorado River are the only gaged streams in the flood area. Prior to the flood, recorders were in operation along Bright Angel Creek near the mouth and at Phantom Ranch. The station at Phantom Ranch was destroyed during the flood. The station near the mouth recorded only a part of the rise of the flood. The partial flood hydrograph indicates that the creek began to rise the morning of December 5 and continued in several steps to the peak on December 6. The recorder trace appears to have been rising when the recorder stopped operating about 0700 hours on De- cember 6; the discharge was between 1,500 and 1,800 ft3/s (42 and 51 m3/s). A peak discharge of 4,000 ft3/s (110 m3/s) was determined for Bright Angel Creek by the slope-area method. The peak discharge of Bright Angel Creek during the flood of December 1966 was the second largest in 45 years, having been exceeded by the flood of August 1936. The recurrence interval computed from a log—Pearson Type III distribution (Benson, 196 8) is about 50 years, and that obtained from the regional flood-frequency relation developed by Patterson and HYDROLOGY OF THE FLOOD OF DECEMBER 1966 11 Somers (1966) is about 100 years. The flood-frequency relation derived from the log-Pearson Type III distribu- tion and station data and that derived from the regional analysis of Patterson and Somers (1966) may be com- pared using curves A and B in figure 5. The plotting position of the data points was obtained from the equa- tion ‘ N + 1, where R1 = recurrence interval, in years, N = number of years of record, and M = order number. The order number, M, was assigned as follows. The annual maximum discharge for each water year was arrayed in order of magnitude and assigned an order number—the largest being number 1, the second largest number 2, and so forth. The peak discharge of 4,000 ft3/s (110 m3/s) on De— cember 6, 1966, at the Bright Angel Creek gaging sta- tion was less than that of 4,400 ft3/s (120 m3/s) on Au- gust 19, 1936. The 1966 flood was much more damaging, however, because high flows persisted for a longer time and because the volume of water that flowed past the station during the 1966 flood was several times larger than that during the 1936 flood. The mean flow for August 19, 1936, was only 200 ft3/s (6 m3/s), whereas, the mean flow for December 6, 1966, was estimated to be 2,500 ft3/s or 71 m3/s (US. Geological Survey, 1968). The estimate for 1966 was based on information fur- nished by residents and discharge records for Kanab Creek and the Paria River. A plot of maximum daily means for the 44-year period indicates a recurrence interval of more than 100 years for a daily flow of2,500 ft3/s (71 m3/s). (See fig. 5.) The highest mean flow for 3 consecutive days during the flood of December 1966 was 1,270 ft3/s (36.0 m3/s). The previous recorded maximum 3—day mean was 749 ft3/s (2 1.2 m3/s) in December 1941. Slope-area measurements along Bright Angel Creek near Phantom Ranch at site 37 and in the tributary basins of Outlet Canyon at site 35 and Fuller Canyon at site 31 on the Kaibab Plateau indicate that the average unit runofffor the 1966 flood was between 40 and 48 ft3/s per mi2 (0.44 and 0.52 m3/s per kmz). (See pl. 1; table 2.) Locally, the unit runoff exceeded this amount several times. For example, the flow in Fuller Canyon was mainly from a 0.6 mi2 (1.6 km2) area and the runoff rate was nearly 300 ft3/s per mi2 (3.3 m3/s per kmz). The precipitation from the storm of December 1966 had a marked effect on the flow of the springs near the head ofBri‘ght Angel Canyon. On December 9, 1966, the combined flow of Roaring Springs in Roaring Springs Canyon—a tributary of Bright Angel Canyon—was es— timated to be 150 ft3/s or 4.2 m3/s (J. B. Gillespie and E. H. McGavock, written commun., 1967); the maximum flow was estimated to have been nearly 200 ft3/s (5.7m3/s). The normal discharge of the springs ranges from 5 to 15 ft3/s or 0.14 to 0.42 m3/s (Johnson and Sanderson, 1968, fig. 3). Gillespie and McGavock (writ- ten commun., 1967) estimated that an additional 75 ~150 ——100 ‘50 DISCHARGE, |N CUBIC METRES PER SECOND 6000 l l I _ EXPLANATION D A Z A Peak-discharge frequency computed using a log-Pearson 0 distribution and gaging-station data. Data point repre- 8 sents annual maximum discharge for 1923-69 (I) August 19, 1936 l: B Peak-discharge frequency computed by methods de- A B Lu __ scribed by Patterson and Somers (1966) / n. 4000 b 196 r E C Frequency of daily mean discharge computed using Decem er 6' ‘6} Lu _ gaging-station data u. o D Frequency of the highest mean discharge for 3 consecu- g tnve days computed using gaging-station data Maximum daily\ C 0 0 Data point discharge during 2 flood of > 1 Note: Annual maximum discharge plotted at a recur— December 1966 D Lu 2000 '-—- rence interval RI: N7” /0/ g — / / < I 8 o o / Maximum 3-day mean a 0 ° discharge during flood “ of December 1966 // O _n 0W 5 5 1.01 1.2 2 5 0 10 2 0 100 200 RECURRENCE INTERVAL, IN YEARS FIGURE 5.—Frequency of annual peak discharges, maximum daily mean flows, and highest mean flows for 3 consecutive days, Bright Angel Creek near Grand Canyon, Ariz. 12 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA ft3/s (2.1 m3/s) came from two unnamed springs a short distance downstream from Roaring Springs. Waldo Wilcox (National Park Service, oral commun., 1967) reported that the water emerging from Roaring Springs was red and muddy on December 7, and Gil- lespie and McGavock reported that the water was not muddy but had a yellowish discoloration on December 9. CRYSTAL CREEK BASIN Along Dragon Creek, an undeveloped tributary to Crystal Creek, the peak streamflow during the flood could not be measured by the slope-area method be— cause a mudflow obscured the floodmarks. The mudflow—an aggregate of onrushing water, mud, rocks, and logs derived from soil, colluvium, debris slides, or avalanches—accompanied the high flow. The discharge, however, appears to have been greater in Dragon Creek than in Bright Angel Creek. Near site 46, a mescal pit—an underground pit for roasting Agave (century plant)—used by the Pueblo Indians about AD. 1100 was destroyed or covered by mud; the mudflow lapped along the edge of a stone ring that borders another mescal cooking pit in use during the same period in the Hindu Amphitheater (see sections "Rela- tion of Prehistoric and Historic Occupation to Flooding” and "Effects of Floods in the Tributary Gorges of Grand Canyon—Flood of December 1966 and Previous Recent Floods”). The information collected at these sites indi- cates that the stage of the mudflow of December 1966 was the highest in the last 800 to 900 years. At site 46, a transit survey of the highest level reached by the mudflow showed a surface slope of 15.1 ft (4.60 m) in 256 ft (78.0 m), or 5.9 percent. The cross-sectional area was measured at three places along the channel and ranged from 1,180 to 1,330 ft2 (110 to 124 m2). A flow of 29,000 fth (820 m3/s) was computed using the Manning equation and a roughness coefficient of 0.070. The Man- ning equation is V : 1.486 ——1“:86 R 24* 8.1/2 in which V : mean cross-sectional velocity of flow, in feet per second; R = hydraulic radius at a cross section, which is the cross-sectional area divided by the wet- ted perimeter, in feet; 8.: : energy slope; and n : coefficient of roughness. At the time of the survey, mud and sand were plas- tered more than 1 in. (25 mm) thick on boulders, trees, and high on the sides of the channel. Locally, mud deposited on adjacent terraces appears to have flowed outward from the main body of flow. The edges of the mud stood in lobes about 1/2—1 in. (13—25 mm) above the ground, which indicates that the surface of the mudflow probably had the consistency of cake dough. The mud flowed over ridges and obstructions instead of around them. An air-dried sample of the mud was taken at the mouth of Crystal Creek; in the laboratory the dried mud sample was mixed with enough water to allow it to flow and produce a lobe similar to that at the edge of the mudflow shown in figure 6; the mixed laboratory sample contained about 40 percent water by volume. The mud- flow was 18—20 ft (5.5—6.1 m) deep in the 60-ft-wide (18-m-wide) channel (fig. 7). In most places the depth of sustained flow of the water that followed the mudflow was about two-thirds that of the mudfiow. The mudflow was preceded by a high flow of water, but the magnitude of the streamflow cannot be determined. The flow at site 40 in Dragon Creek above Milk Creek was fairly large—about 8 ft (2.4 m) deep in a box-shaped channel about 15 ft (4.6 m) wide. The discharge was estimated to be about 1,000 ft3/s (28 m3/s) from a drain- age area of 4.58 mi2 (11.9 km2), which is one of the highest discharges per square mile in the flood area. In contrast, little flow passed site 39 in the main stem of Crystal Creek (fig. 8)—-possibly 100 ft3/s (2.8 m3/s) from a drainage area of 12.1 mi2 (31.3 km2). FLOOD DAMAGE TO MODERN STRUCTURES The Bright Angel Creek basin is the only area in eastern Grand Canyon where modern structures exist FIGURE 6.—Edge of the mudflow at the mouth of Crystal Creek where a sample was taken to estimate the consistency of the mud during the flood of December 1966. The mud (dark deposits) flowed over the preflood deposits (light deposits indicated by spade) of the Colorado River. FLOOD DAMAGE TO MODERN STRUCTURES FIGURE 7.—Dragon Creek at site 46. Arrows indicate crest of mud- flow. A, Looking downstream along the slope-area reach. Note channel scoured to clean bedrock, B, Looking across the channel from the east side. The height of the eroded west bank averages about 12 ft (3.7 m). 13 FIGURE 8.—Crystal Creek above Dragon Creek; looking upstream. The channel conditions in this reach probably are representative of those in most of Crystal Creek prior to the flood because the channel was changed little by the flood. near a stream; these structures and roads on the Kaibab Plateau received considerable damage. Most of the road damage was near the Bright Angel Ranger Station, in Kanabownits Canyon, and along the road leading to Saddle Mountain in North and South Canyons. Because the cells of intense precipitation were centered in al— most unpopulated parts of the Grand Canyon area, no loss of life occurred. Many more buildings and campgrounds would have been damaged with possible loss of life if Bright Angel Canyon had been subjected to the extensive mudflow activity that occurred in the undeveloped Crystal Creek area. Flooding was not exceptionally severe in the North and South Canyon areas, but residents reported more washouts than during any other recent storm. Sections of the improved dirt road in the narrow part of Kanabownits Canyon were severly damaged and were almost impassable for automobile travel. Near the Bright Angel Ranger Station, debris slumped across the paved highway in Thompson Canyon and along the Point Sublime Trail east of Outlet Canyon (fig. 9). Sev- eral debris slides took place near Bright Angel Creek 14 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA FIGURE 9.—Debris slide along the Point Sublime Trial 0.25 mi (0.4 km) east of Outlet Canyon. along the paved highway leading to Point Imperial and Cape Royal, and the highway was closed for several months. The pumps at Roaring Springs in Bright Angel Can- yon were damaged when about 21/2 ft (0.8 In) of water from Roaring Springs Canyon rushed through the pumphouse. The powerhouse 0.50 mi (0.8 km) downstream on Bright Angel Creek was demolished (fig. 10). Between the pumphouse and the mouth of Bright Angel Creek, the flood washed out parts of the cross-canyon Kaibab Trail, bridges, and a $2 million pipeline that had just been completed to transport water from Roaring Springs to Phantom Ranch and Grand Canyon village (figs. 11, 12). The pipeline was in a shallow trench along the Kaibab Trail, which crosses Bright Angel Creek at several places between Phantom Ranch and Roaring Springs Canyon. Al- though a part of the pipeline was not washed out by the flood, it was plugged with gravel to such an extent that it was unusable. According to the National Park Serv- ice (written commun., July 1970) 3M2 years and $5 mil- lion were required to rebuild the pipeline and repair the trail. The flood caused severe damage to manmade struc- FIGURE 10.—Damage to structures in Bright Angel Canyon, flood of December 1966. Powerhouse in middle foreground, residence in right center, bridge and pipeline in foreground. The channel of Bright Angel Creek now is established behind the bridge and under the powerhouse. Note the debris on the bridge (arrow). FIGURE 11.—Exposed pipeline (arrow 1) near Ribbon Falls. Prior to the flood, a 40-ft (12—m) bridge crossed Bright Angel Creek in the center of the photograph (arrow 2). The channel is now about 150 Pt (46 In) wide and is bordered by a single terrace. tures near the Phantom Ranch and cut a new channel a few feet west of the recently constructed U.S. Geolog- ical Survey residency at the ranch; although floodwa- ter surrounded the residency, the building was not damaged. The new channel cut through the nearby rec- reational grounds and undercut a corner of the wranglers’ quarters (fig. 13). Near the mouth of Bright RELATION OF PREHISTORIC AND HISTORIC OCCUPATION TO FLOODING FIGURE 12.——Bright Angel Creek before and after the flood of De- cember 1966. A, Stream channel before the flood; poles show the alinement of the pipeline (arrows). B, Exposed pipeline (arrow) after the flood. Angel Creek, a large part of Phantom Ranch Campground was removed by lateral erosion (fig. 14). RELATION OF PREHISTORIC AND HISTORIC OCCUPATION TO FLOODING All the north rim tributary gorges damaged during the flood of December 1966 contained evidence of past human occupation, mainly in the form of ruins. The ruins were occupied by Anasazi Pueblo III Indians— direct ancestors of the Hopi Indians of northern Arizona—between AD. 1050 and 1150. The prehistoric Indians must have experienced flash floods, but the flood of December 1966 probably was greater than any since the general abandonment of eastern Grand Can- yon by the Pueblo Indians; about AD. 1150. At least 15 FIGURE 13.~Damage to structures near the Phantom Ranch, flood of December 1966. Aerial view looking downstream. US. Geological Survey residency is in left center (arrow 1). The new channel of Bright Angel Creek crosses the terrace between the Survey resi- dency and the cottonwoods, and the creek flows under part of the wranglers’ quarters (arrow 2). The undercut corner of the wranglers’ quarters collapsed after this photograph was taken. Before the flood, the channel followed the approximate path indi- cated by the dashed lines. three archeological sites,2 unused and undisturbed since that time, either were obliterated or damaged during the 1966 flood. Archeologists are able to diachronically describe the culture-history of the area in general terms from the surveys and analyses of more than 250 ruins recorded below the rims of the canyon (Euler, 1969, p. 8). Most of the archeological sites in the area affected by the 1966 flood were occupied by the Kayenta Anasazi Indians about A.D. 1050—1150. A few campsites, however, were used by the Southern Paiute Indians between about AD. 1200 and the late 19th century and by the Hopi Indians after AD. 1300; other sites are mine shafts 2In this paper, an archeological site may be considered to be any lasting evidence of human utilization, from a group of surface potsherds marking a former campsite to the clusters ofruined masonry structures, check dams, and mescal pits. Each site is recorded in the Prescott College Archaeological Survey and is given in this paper in parentheses—for example (Ariz. B:16:42). 16 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA we; FIGURE 14,—Damage to the Phantom Ranch Campground, flood of December 1966. Prior to the flood, restrooms were located in the area in the center ofphotograph (arrow 1), and a bridge crossed the creek in the foreground (arrow 2) to provide access to the campground. The fireplace in left center (arrow 3) indicates the former ground level. and cabins of the 19th century prospectors. The fact that more of the hundreds of Pueblo ruins have not been damaged or destroyed in Grand Canyon is due to their location on terraces and cliffs; therefore, it is suggested that the Anasazi were aware of the danger of periodic floods—although not as severe as the flood of 1966—and so built most of their structures in protected places. Mescal pits, such as those discussed in the fol- lowing paragraphs, probably were of little consequence to the Anasazi and were built in unprotected places. ARCHEOLOGICAL SITES IN THE FLOOD AREA All the main gorges that drain from the north rim contain many early Pueblo III Kayenta Anasazi sites. The sites include surface rock shelters, masonry rooms, granaries, and mescal pits. Because most of these sites are away from the stream channels, only a few along Clear and Dragon Creeks (Crystal Creek basin) were damaged by the flood of December 1966. Only one his- torical site, the old campsite of Bass along Shinumo Creek, was endangered by the flood. CLEAR CREEK Evidence of a large flood was noted along Clear Creek, particularly in Ottoman Amphitheater Where there are three archeological sites. The sites consist of surface masonry rooms, granaries, and one mescal pit. The mescal pit (Ariz. B:16:6) was first recorded in May 1966 as being 12 ft (3.7 m) in diameter and 35 ft (11 m) from the bed of Clear Creek. Lateral cutting by the flood of 1966, however, completely removed the west- ern one-eighth of this cultural feature (fig. 15) and ex- posed a sherd (classified as Deadmans Fugitive Red, Cohonina culture) 1.6 ft (0.50 In) below the surface of the pit. Although the sherd was the only artifact re- covered from the site, Euler believes that the mescal pit, like all other sites in Clear Creek Canyon, is a Kayenta Anasazi structure dating from about AD. 1150. CRYSTAL CREEK The drainage area of Crystal Creek—which contains two major tributaries, Dragon and Milk Creeks—is one of the areas most severely affected by the flood of 1966. An early Pueblo III site (Ariz. B16242) is in Dragon Creek Canyon a few hundred yards above its junction with Crystal Creek. The ruins are on both sides of the creek and consist of a rock shelter, surface masonry rooms, and mescal pits. All date from AD. 1100:50 years and were abandoned probably not later than AD. 1150. At site (Ariz. B:16:42), one of the mescal pits on the left bank is about 26 ft (8 In) in diameter. The exact distance from the mescal pit to the stream channel was not measured when the site was originally recorded on May 16, 1966; Euler’s (written commun., 1966) field notes show the pit to have been “about fifteen feet back from the edge of an erosional precipice which dropped away about ten feet to the normal water level of the stream.” After the flood, the edge of the terrace was only 3 ft (0.9 m) from the pit, and the mudflow line touched the stone ring that marks the circumference of the pit (fig. 16). The ring showed no effects of erosion. The stone ring enclosed a shallow depression. A short trench was excavated into the fill from the center of the depression outward through the external limits of the fire—cracked stone ring. It was found that the upper 1.6 ft (0.50 m) of material inside the pit was a sandy loam. The soil showed no interbedded layers of stream-laid sandy or silty material that may have been deposited by Dragon Creek if the pit had been inundated by a large flood since its construction in about AD. 1100. Prior to December 1966, an 81/2—11-ft-diameter (2.6—3.4-m-diameter) mescal pit (Ariz. B216241) was re- corded about 1.25 mi (2.0 km) upstream from site Ariz. B216242 on the right bank of Dragon Creek (fig. 17). Although no diagnostic cultural materials were found, it is assumed that the pit was used about AD. 1050— 1150, as were the other sites in the drainage. When the area was Visited after the flood, all traces of the pit had been eradicated by the mudflow, which extended across the entire canyon floor (fig. 17). KAIBAB PLATEAU— FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS l7 SHINUMO CREEK The perennial flow of Shinumo Creek is fed by White Creek, Flint Creek, and Modred Abyss. About 30 Kayenta Anasazi sites dating from about AD. 1050— 1150 are in the drainage. All the sites are on ledges or terraces above the flood plain and suffered no damage, even in the upper reaches of Modred Abyss where the water and mudflows were deep. The historic winter camp (Ariz. B215z49) of the late William W. Bass—a prospector and early tourist guide in the Grand Canyon—is near the mouth of Shinumo Creek. The camp was in use from about 1890 to 1910 and consisted of gardens, root cellar, tents, and some masonry retaining walls on both sides of the creek. A description of the camp and photographs taken during its use were documented by James (1911, p. 190—203), a noted author of the day. An iron stove at the camp is about 10 ft (3 m) above the bed of the creek, and the maximum height of the floodline, which is only 20 ft (6 m) from the stove, is about 71/2 ft (2.3 m) above the bed. A rock retaining wall was built a short distance downstream from the camp—presumably to retard stream erosion—and the flood of 1966 wetted part of the wall; however, there is no indication of flood dam— age at the site. Although regional frequency analyses ShOW the flood to have a recurrence interval of about 20 years, the flood probably was one of the largest that has occurred since the occupation of this site. EFFECTS OF FLOODS ON THE KAIBAB PLATEAU—FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS The Kaibab Plateau is characterized by broad grassy parks and valleys between forested slopes of pine and spruce. Dense grass not only covers the parks but is present on the sides and bottoms of the stream chan- nels. The parks and valleys are mantled by dark gray generally clayey to silty alluvial or colluvial soil; many of the bordering limestone ridges are deeply weath- ered. In places the weathering is more than 50 ft (15 m) FIGURE 15.—Mescal pit (Ariz. B:16:6) damaged by the flood of De- cember 1966 along Clear Creek. A, Undamaged mescal pit; man is on rim. Clogged channel of Clear Creek (arrows) in May 1966. B, Damaged mescal pit (arrow 1) and cleared channel of Clear Creek (arrow 2) in December 1968. Note that much of the dense vegeta— tion has been removed and that a new pattern of large boulders has been established in the flood area. It appears that no signifi— cant new growth of vegetation occurred during the summer of 1968. C, Cross section ofthe mescal pit exposed mainly by lateral cutting during the flood. Rim of pit is indicated by dashed line. Depth of cutting is about equal to the height of the man. Wood debris (solid line) gives an indication of the flood crest. 18 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA FIGURE 16.—Lower part of Dragon Creek at site (Ariz. B:16:42) after the flood of December 1966. A, Dragon Creek makes a sharp bend to the left at the base of the cliff; piling up of the mudflow accom— panied by splash formed a 30—ft-high (9-m-high) crescent-shaped pattern (upper arrow) on the Vishnu Schist. Note edge of the mud— flow (lower arrow) in foreground. Vegetation on the low terraces is mainly grass, Agave, Mormon tea, and catclaw, some of which indicate semiarid conditions. B, Closeup of mescal pit (dashed line) (Ariz. B:16:42) and edge of mudflow. deep, and the limestone is covered by a loose residual accumulation of chert and limestone fragments. The fragments are used as roadbed material by the Na- tional Park Service and Arizona Highway Depart- ment. In general, the surficial mantle and weathered lime- stone are permeable and tend to absorb precipitation and limit runoff, thereby restricting the formation of large channels. Many valleys display discontinuous channels or shallow channellike features that are gen— FIGURE 17,—Mudflow debris on the terrace on the right bank of Drag- on Creek (arrow). The location of mescal pit (Ariz. B:16:41), which was destroyed by the flood, is near that of the helicopter. Mudflow debris covers this area from canyon wall to canyon wall. erally less than 5 ft (1.5 m) deep and have a roughly trapezoidal cross section. In the southern part of Del Motte Park, in Little Park, along Clear Creek tribu- tary 3, along the lower reaches of Fuller and Outlet Canyons, and in the Tipover Canyon and Quaking Aspen Canyon systems, a few gullies and arroyos were actively eroding before the flood of December 1966. Large parts of all the drainages on the Kaibab Plateau, particularly in the headwater reaches, are devoid of channels or channellike features. CLEAR CREEK BASIN Clear Creek drains the Walhalla Plateau, which is part of the north rim area east of Bright Angel Canyon; of the tributaries to Clear Creek that were inspected, Walhalla Glades and Clear Creek tributary 3 showed the most effects from the flood of 1966. The channel of Walhalla Glades is continuous and is generally from 11/2 to 2 ft (0.5 to 0.6 m) deep and from 5 to 12 ft (1.5 to 3.7 m) wide. The effects of the flood were much more apparent near Cape Royal (site 26) than in the area about 4 mi (6 km) north of the cape (site 25). At site 26 water overlapped the edge of the channel and covered part of the adjacent alluvial valley floor (fig. 18). From the borrow pit (pl. 1) to the edge of the Walhalla Plateau—a distance of about 0.50 mi (0.8 km)—the channel was scoured 1/2 —2 ft (0.2 —0.6 m). The new chan- nel depth is between 21/2 and 4 ft (0.8 and 1.2 m). Gravel from the borrow pit was transported downstream and acted as a cutting tool in deepening KAIBAB PLATEAU— FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS 19 FIGURE 18.—Walhalla Glades at site 26. The‘flood of December 1966 deepened the channel—renewed arroyo cutting—by 1/2-2 ft (0.2— 0.6 m) downstream from site 26; upstream the channel was deepened intermittently by scours. The low bench on the right side of the channel represents the level of the channel prior to the flood. Level rod indicates crest of the flood. the channel; only discontinuous scouring occurred up— stream from the pit (table 2). Clear Creek tributary 3 is the main stream that drains the central part of the Walhalla Plateau. Prior to the flood of December 1966, the channel at site 24 was broad, in places having 2 ft (0.6 m) of relief. The channel displayed a few healed scours, but for the most part the pre-1966 channel was rather smooth. In most places the maximum depth of the flood was between 11/2 and 21/2 ft (0.5 and 0.8 m); the flood inundated the channel and a 50—75—ft—wide (15—23-m-wide) strip of the valley floor (fig. 19). The most conspicuous channel modification was the formation of scours and bars at irregular intervals (fig. 19A). The largest scour is about 300 ft (90 m) long (fig. 19B). The scour probably was being eroded before the flood because remnants of the grass-floored channel are present within the scour. The downstream part of the scour is partly filled by a new gravel bar. Based on the distribution of remnants of the old channel floor and weathered roots of an aspen that appeared to have been exposed before the flood, headward extension of the scour during the flood may have been as much as 125 ft (38.1 m). The gravel bars deposited by tributary 3 have a more limited distribu- tion than the scours. The largest bar had a maximum thickness of 11/2 ft (0.5 m), was 20—30 it (6—9 m) wide, and nearly 100 ft (30 m) long (fig. 19C). BRIGHT ANGEL CREEK BASIN On the Kaibab Plateau, the flow, erosion, and slump- ing that resulted from the flood of December 1966 were most noticeable in Thompson and Outlet Canyons— the main tributaries to Bright Angel Creek. The main stem of Bright Angel Creek, however, drains only a few square miles on the plateau and had only small amounts of flow and erosion (table 2). Before the middle 1930’s, open scours were present in places along the drainages in Bright Angel Creek basin. Erosion control—which consisted mainly of filling the scours with rock aggregate—was attempted by the Civil— ian Conservation Corps in Thompson Canyon, and some of the fills were exposed by the 1966 flood. By 1966, most of the scours and gullies in the Bright Angel basin were covered by a dense mat of grass, which suggests that the scours in Thompson Canyon may have healed naturally without the manmade controls. THOMPSON CANYON DRAINAGE Thompson Canyon drains most of the north rim of the Grand Canyon. Most of the flow in Thompson Can- yon during the flood of December 1966 came from the southern part of the drainage area and from Fuller Canyon—the main tributary to Thompson Canyon. The grassy floors of the Thompson Canyon basin up- stream from site 29 (pl. 1) do not show appreciable recent erosion from runoff. Thompson Canyon tribu— tary 1, which enters Thompson Canyon at site 29, had a flow more than 1 ft (0.3 m) deep, which was sufficient to cause new but minor scouring and the deposition of gravel. In the reach of Thompson Canyon downstream from site 29 and upstream from tributary 2, scours eroded during the flood of December 1966 had a maximum length of 25 ft (7.6 m) and were not more than 1 ft (0.3 m) deep; most were about 1/2 ft (0.2 m) deep. Both sides of Thompson Canyon contributed to the floodflow, as shown by a few small scours along the tributaries and by two small debris slides. The slide at location A (pl. 1) partly blocked the main highway. The east-flowing Thompson Canyon tributary 2 was a major contributor to the floodflow and caused gullying. At the mouth of tributary 2, a gully 5 ft (1.5 m) deep and 60 ft (18 m) long was formed along the stream that drains Thompson Canyon; from there, a narrow gully about 4 ft (1.2 m) wide and 5 ft (1.5 m) deep extended about 200 20 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA \ /Flood crest Maximum depth 1/ n (o. 5 m) a x a x a m a Large scour— Depth 4 n (1 2 ml \ / Wldlh35ft(10.7ml l Length 300 n 1914ml Y l l // (see figure 19m (See figure 19C) Flood crest — Maximum depth 2V2 ft (0.8ml // X h/K/Scour DEpth 3 n (o 9 ml \ \_ Width 7 ft (2.1 ml N V 9“. x. \ Length 8 ft 12. 4 m) \ Clear Geek Tributary 3 \m g ~54sz scours along side i ‘3‘. ? tributary i EN Scour Depth 3ft (09) Width 15 ft (4. 6 m) Length 100 ft 30.5 m) REACH IS ABOUT 3,000 FEET (914. 4 m) LONG ft (60 m) upstream along the tributary and terminated at an outcrop of the Kaibab Limestone. About midway along the tributary gully, part of an older gully, which was filled by rock emplaced by the Civilian Conserva- tion Corps in the 1930’s to check erosion, was exposed during the flood. Except for two large scours, only shal- low scours and small bars interrupt the continuity of the streambed of Thompson Canyon between tributary 2 and Harvey Meadow. One scour, which was exca- vated at a change in gradient of the canyon (pl. 1, 10c. B), is 2 ft (0.6 m) deep, 4 ft (1.2 m) wide, and 20 ft (6 m) long and exposes part of an old rock-filled channel. The other scour is more spectacular—4 ft (1.2 m) deep, 15 ft (4.6 m) wide, and 40 ft (12 m) long—and was carved along the paved highway a short distance downstream from the mouth of Fuller Canyon. On the grassy floor of Fuller Canyon, only a small amount of erosion occurred upstream from location D (pl. 1). At location D, the effects of floodwater from the small east-flowing tributaries can be seen readily; some prefiood gullies 1—3 ft (0.3—0.9 m) deep were ex- tended headward about 1 ft (0.3 m) but were hardly deepened. Near location E (pl. 1), erosion was slightly more severe, and the old channels and gullies were deepened as much as 1/2 ft (0.2 m). Although runoff was received from both sides of Fuller Canyon downstream from Blondy Jensen Spring, substantial flow came from the northwest-flowing tributaries near the spring. Near location F (pl. 1), renewed cutting deepened an old arroyo about 0.25 mi (0.4 km) long by as much as 3 ft (0.9 m). (See fig. 20A.) Prior to the cutting, the arroyo had a maximum depth of 6 it (1.8 m) and was stabilized mainly by grass. The amount of headward extension of the arroyo probably was a few tens of feet. Lateral erosion widened the arroyo, and at one place it cut into the shoulder of the Cape Royal— Point Imperial Road. A diamond-shaped gravel fan 1 ft (0.3 m) thick, 150 ft (46 m) long, and 100 ft (30 m) wide was deposited at the downstream terminus of the ar- royo (fig. 203) where the gradient is low and the can- yon is wide. Between the gravel fan (loc. F) and site 31 (pl. 1), the channel is generally well defined and its lower part forms a ditch along the south side of the Cape Royal—Point Imperial Road. The average deep- FIGURE 19.—Effects of the flood of December 1966 along Clear Creek tributary 3, Walhalla Plateau. A, Diagrammatic sketch of part of Clear Creek tributary 3 showing scours and bars. B, Head of the 300-ft-long (90-m-long) scour in Clear Creek tributary 3, which probably was being eroded prior to the flood. Upstream from the headcut (arrow), the valley was not eroded during the flood. C, Gravel bar deposited downstream from the 300—ft-long (90—m-long) scour. KAIBAB PLATEAU—FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS FIGURE 20.—Ef‘fects of the flood of December 1966 in Fuller Canyon, Kaibab Plateau. Fuller Canyon has a wide grass-covered floor which is bordered by a forest of pine, spruce, and some aspen. A, An old arroyo in Fuller Canyon that was deepened and slightly wid— ened by the flood. B, A diamond-shaped gravel fan that was de- posited at the downstream terminus of the arroyo. The gravel fan is 150 ft (46 m) long and 100 ft (30 m) wide and is the largest single deposit of gravel on the Kaibab Plateau. ening of the ditch was about 1 ft (0.3 m). Near the mouth of Fuller Canyon, a 21/2-ft—thick (0.8-m—thick) deposit of gravel accumulated at the junction of the main highway to the north rim and the Cape Royal— Point Imperial Road; the deposit is the largest known to have accumulated on the Kaibab Plateau during the flood of December 1966. Harvey Meadow is a roughly elliptical depression in the widest part of Thompson Canyon (pl. 1). The roadbed of Point Sublime Trail forms a low dam that further accentuates the depression. The flood of 1966 filled the depression and formed a lake about 500 ft (150 m) wide. Although the overflow from the lake 21 crossed the Point Sublime Trail, it caused only minor erosion because the water was spread out over the meadow. A small poorly formed gravel delta accumu- lated along the edge of the meadow at the northeastern limit of the lake; the delta consists of material trans- ported mainly from Fuller Canyon. Thompson Canyon, between Harvey Meadow and Bright Angel Spring at the edge of the Kaibab Plateau, is narrow, and in places the canyon floor is only 50 ft (15 m) Wide. Upstream from location C (pl.1), the shal- low channel and canyon floor are mantled by a thick stand of grass that remained virtually intact during the flood. Location C marks the head of a preflood ar— royo that extends upstream from the plateau rim near Bright Angel Spring—a distance of less than 0.50 mi (0.8 km). At its head, the arroyo is 7 ft (2.1 m) deep; downstream it is 5—8 ft (1.5—2.4 m) deep and 8—12 ft (2.4-3.7 m) wide. The head of the arroyo apparently has been stabilized by the roots of a 41/2-ft-diameter (1.4-m-diameter) Engelmann spruce. On the upstream side, the roots still partially control headward erosion, but fresh exposures of alluvium indicate that the ar- royo was extended headward about 8 it (2.4 m) and deepened 1/2 ft (0.2 m). Near Bright Angel Spring, several debris slides were caused by the flood. One slide from the left bank blocked the preflood arroyo, which may not have been more than about 4 ft (1.2 m) deep prior to the flood. The floodwater was diverted across a relatively flat area of tall dense grass cover, cascaded over a 15—ft-high (4.6-m-high) vertical cut at the downstream edge of the flat area, and then rejoined the main arroyo. During the flood, the vertical cut was extended headward 40 ft (12 m). OUTLET CANYON DRAINAGE Outlet Canyon drains an area between the northern boundary of the Grand Canyon National Park and the north rim of the Grand Canyon west of the Thompson Canyon drainage. During the flood of December 1966, a peak flow of 414 ft3/s (11.7 m3/s) at site 35 left the north rim through Outlet Canyon and caused substan- tial channel modification. The floodflow in the 1— mi-long (1.6-km-long) reach of Outlet Canyon near the Point Sublime Trail deposited many gravel bars, cut large scours, and renewed trenching of a continuous arroyo (fig. 21). The number, depth, and size of the scours progressively increase downstream until the scours coalesce to form a continuous inner trench cut below the level of the pre—1966 channel. Upstream from the Point Sublime Trail near the confluence of Outlet Canyon and tributary 1, the stream channel is 2—3 ft (0.6-0.9 m) deep and 25—60 ft (7.6—18 m) wide. Some of the banks on the outside 22 FIGURE 21.—Erosi0n caused by the flood of December 1966 in Outlet Canyon, Kaibab Plateau. Renewed arroyo cutting in Outlet Canyon between a point about 0.50 mi (0.8 km) downstream from the Point Sublime Trail and the edge ofthe plateau; the cutting deepened the old channel 1—2 ft (0.3—0.6 m). curves of meanders were accentuated and cut back 1—2 ft (0.3—0.6 In). Many shallow scours about 1 ft (0.3 In) deep were excavated in the grass—floored channel, but only one significant scour—1V2 ft (0.5 m) deep, 5 ft (1.5 m) wide, and 70 ft (21 m) long— was noted upstream from the Point Sublime Trail. Scours were cut below several of the 2-ft-high (0.6-m-high) limestone ledges that cross the channel about 1,000 ft (300 m) north of the Point Sublime Trail. Gravel deposits as much as 2 ft (0.6 m) thick were concentrated in diamond-shaped bars between the limestone ledges and the trail, which indicates that much of the detritus transported from the upper reaches of the Outlet Canyon drainage ac- cumulated in this part of the basin. Between the Point Sublime Trail and the point where the newly formed continuous arroyo begins (pl. 1), deeply scoured reaches alternate with those having bars or shallow scours. Many of the scours are 3 ft (0.9 In) deep, 10 ft (3 m) wide, and 50—60 ft (15—18 m) long; one has a maximum relief of 5 ft (1.5 m) between its base and the top of a nearby gravel bar. Gravel bars between the scours are as much as 2 ft (0.6 In) thick and 50 ft (15 m) long. Spotty lateral cutting adjacent to the gravel bars removed from 2 to 3 ft (0.6 to 0.9 In) of alluvium from the sides of the channel. In places sheets or bars of silty sand nearly 1 ft (0.3 m) thick were deposited along the lower slopes of the channel. In gen- eral, the channel sides were only slightly affected by the flood of 1966, but between 50 and 75 percent of the channel bottom was modified by scours or bars. The reach of Outlet Canyon 0.5 mi (0.8 km) downstream from the Point Sublime Trail was more EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA severely dissected than any other drainage on the Kaibab Plateau (fig. 21). Remnants of the pre-1966 grass—covered channel floor outline a low bench 1—3 ft (0.3—0.9 m) high along one or both sides of the new channel. Gravel bars were deposited downstream from large scours in the new channel and in places along the inside curves of meanders. Although the flood eroded about 75 percent of the channel floor, about 50 percent of the preflood channel sides was left intact. CRYSTAL CREEK BASIN Crystal Creek drains only a small part of the Kaibab Plateau. The creek and its tributaries are in shallow canyons that have alluvial floors. Milk Creek tribu- tary, where crossed by the Point Sublime Trail, passes through a small meadow that has an undulating sur- face caused by grass-covered dolinen formed in the Kaibab Limestone. The floodflow, upon entering the meadow, fanned out and inundated the dolinen and the Point Sublime Trail. As indicated by debris, a tempo- rary lake about 8 ft (2.4 In) deep and 200 ft (60 m) wide was formed. The flow that entered the lake deposited a 2-ft-thick (0.6-m—thick) gravel delta over a 40- by 30-ft (12- by 9-m) area. Along the Point Sublime Trail about 0.10 mi (0.16 km) east of Milk Creek tributary, the flood caused or greatly accentuated the subsidence of a sinkhole in the alluvium. The sinkhole—a nearly vertical-walled depression 10 ft (3 m) wide, 40 ft (12 In) long, and 7 ft (2.1 m) deep—extends across a stream channel and now (1967) can intercept all the flow of the tributary. OTHER AREAS The flood of December 1966 produced relatively minor effects in all other drainage basins on the Kaibab Plateau. The broad undissected meadows in northern Del Motte Park, upper North Canyon, the lower part of Lookout Canyon, Dry Park, and Pleasant Valley show no evidence of recent floods; however, the flood of 1966 caused some damage in Kanabownits Can- yon (table 2). Evidence of recent erosion as a result of floods prior to those of 1966 is recognizable in several isolated places on the Kaibab Plateau. In the southern part of Del Motte Park and in upper Little Park several shal- low discontinuous gullies eroded before December 1966 mar the gentle undulating surface of the parks. The gullies are 2—3 ft (0.6—0.9 m) deep, as much as 30 ft (9 m) wide, and some are a few hundred feet long. A discontinuous arroyo in Tipover Canyon is as much as 6 ft (1.8 m) deep, is generally less than 8 ft (2.4 m) wide, and has sharp banks covered by a scattered stand of grass. A 31/2—4-ft—deep (1.1—1.2-m-deep) arroyo ex- TRIBUTARY GORGES OF GRAND CANYON— FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS 23 tends from near the confluence of Quaking Aspen and Browns Canyons to the rim of the Kaibab Plateau. Another arroyo, which is 3—5 ft (0.9—1.5 m) deep, is present in the lowermost 0.50 mi (0.8 km) of a tribu- tary that enters Quaking Aspen Canyon about 2 mi (3 km) upstream from the mouth of Browns Canyon (pl. 1). Between the two arroyos in Quaking Aspen Canyon, several small sinks 0r depressions intercept all the small flows. Although grass is growing on the sides and bottoms of the sinks, the heads of some are being eroded. Farther north in parts of Dry Park, short narrow arroyos about 2 ft (0.6 m) deep have been trenched along an old wagon road. RELATION OF SCOURING TO FLOOD DEPTH During the flood of December 1966, different amounts of scouring took place along the drainages on the Kaibab Plateau. Integration of the scours caused deepening of the channel or renewed arroyo cutting mainly along parts of Outlet Canyon and Walhalla Glades. Outlet Canyon had the most cutting. The re— newed arroyo cutting in the two drainages was the result of large flows that probably were continuous for 2 or 3 days. The renewed cutting occurred by extension and integration of scours rather than by headward migration of a single knickpoint. For example, in Out— let Canyon the scours are larger and more closely spaced near the upstream end of the new arroyo than they are in reaches farther upstream. As shown in the following tabulation, there is a rough relation between the amount of scouring that occurred during the flood and the maximum depth of the flood crest. The dense grass cover and the alluvium and soil were similar in all the drainages; the grass almost covered the channels, old scours, and valley or canyon floors. For flood depths of 11/2—3 ft (0.5—0.9 m), the depth of the scours usually is 1—3 ft (0.3—0.9 m) below the bottom of the channels or valley floors not having a well—defined channel. The deepest and largest scours—nearly 5 ft (1.5 m) deep—were formed along Outlet Canyon by flood depths of 4—5 ft (1.2—1.5 m). Maximum depth of flood crest Amount of scouring (ft) A few inches of soil was removed locally in channels, which exposed roots of grass and other plants. Almost no erosion on valley floors not having channels ___4 A few small scours formed in the channels. Locally, grass roots were exposed on the valley floors not hav- ing channels ____________________________________ Depends on the depth: Some lateral cutting and scours common in channel. Few to many scours formed on valley floors not having channels. Renewed arroyo cutting occurred in a short reach of Walhalla Glades and Outlet Canyon ______________________________ >1 <1/2 1/2— l EFFECTS OF FLOODS IN THE TRIBUTARY GORGES OF GRAND CANYON—FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS The tributary gorges in eastern Grand Canyon that show channel modification as a result of the 1966 flood include those from Nankoweap Creek to Deer Creek along the southern margin of the Kaibab Plateau (ta- bles 2, 3). Little flow occurred in the side gorges that drain the south rim of the Grand Canyon. The chan- nels in the gorges are lined with gravelly alluvium except where consolidated rocks are exposed in the narrow parts of the gorges. The gravelly alluvium comprises multiple-fill terraces—irregular alluvial terraces of local extent—that have levels ranging from 2 to 50 ft (0.6 to 15 m) above the streambeds. Most of the terraces are 4—6, 8—10, 12—15, and 20—30 ft (1.2—1.8, 2.4—3.0, 3.7—4.6, and 6—9 m) high. Some of the drain- ages, such as Bright Angel Creek, have only one well- defined terrace level, which is between 5 and 7 ft (1.5 and 2.1 m) high. Many of the terraces contain accumu— lations of large boulders, which account for some of the irregularity in their heights. Some of the boulder ac— cumulations are the result of past mudfiow activity. Along several drainages (pl. 1), older alluvial fill deposits—called the reddish-brown unit—have been eroded into terraces higher than the multiple-fill ter- races. In the Nankoweap and Chuar Creek basins, ter- races of the reddish-brown unit are more than 100 ft (30 m) above the streambeds (Springorum, 1965). Many multiple-fill terraces less than 8 ft (2.4 m) above the streambeds are inundated by large floods. Below this level, there may be as many as three ter- races; however, generally only one or two are present at levels of 2—3 or 4—5 ft (0.6—0.9 or 1.2—1.5 m) above most streambeds. In the north rim area many low ter- races were covered by floodwater during the flood. Along some drainages, such as Crystal, Dragon, Lava, and Nankoweap Creeks, terraces higher than 8 ft (2.4 m) above the streambeds were inundated and were modified by the mudflows. Cottonwoods and junipers growing on the low terraces and large bars in the stream channels and on the channel floor help substan- tiate that, with few exceptions, only minor changes in channel depth resulted from the flood of 1966. Mature junipers growing within a few feet of the bottoms of the channels also indicate that little change in channel depth has occurred during the last few centuries. A striking effect of the flood of December 1966 was the movement of mud, rocks, and logs as mudflows and debris slides in the side gorges of Marble and Grand Canyons—principally in the Nankoweap, Chuar, Crys- tal, and Shinumo Creek drainage basins (pl. 1). The 24 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA TABLE 3.—Brief descriptions of the flood of December 1966 and previous floods in the tributary gorges of the Grand Canyon Tributary Brief description of flood of December 1966 Evidence of previous floods Saddle Canyon ,,,,,,,,,,,,,,,,,,,,, Moderate flow; minor scouring of channel. No information available. Nankoweap Creek ,,,,,,,,,,,,,,,, One of the rare large floods along this creek; channel was severely modified; The flood of 1966 removed traces of previous floods. mudflows occurred only in the upper reaches of the watershed. Kwagunt Creek ,,,,,,,,,,,,,,,,,,,,, A large flood but probably one of rather common occurrence; moderate scour- Based on the relation of the 1966 flood peak to the low ter- ing of the channel. Chuar Creek ,,,,,,,,,,,,,,,,,,,,,, One of the major floods in Lava Creek and Chuar Creek below Lava Creek; a mudflow extended from the head of Natchi Canyon downstream along Lava and Chuar Creeks to the Colorado River; severe to moderate modification of the channel affected by mudflow and accompanying streamflow; the chan- nel of Chuar Creek above its confluence with Lava Creek carried only a minor amount of flow. Unkar Creek ,,,,,,,,,,,,,,,,,,,,,, Rather small flow; channel shows only minor effects from flooding. Clear Creek ,,,,,,,,,,,,,,,,,,,,,,,, Large flow; considerable lateral cutting and scouring; lateral cutting removed about halfofa mescal pit used by the Pueblo Indians about A.D. 105(L1150, Bright Angel Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Flood peak was the second highest of record; volume of flow was the largest recorded since monitoring of the creek began in 1922; major modification and scouring of channel; flood channel cut through terrace at Phantom Ranch and removed terraces upstream from Phantom Ranch; a mudflow probably occurred in the upper reach; the tourist trail, campgrounds, pipeline, and a few buildings were damaged. Crystal Creek ,,,,,,,,,,,,,,,,,,,,,, Flood consisted of streamflow and mudflow stages; mudflow covered some of the terraces and destroyed an archeological site used about A.D. 105&1150; major modification of the channel included scouring, deepening, and some deposition; deposition of large boulders at mouth of creek; very little flow from Crystal Creek above Dragon Creek. Tuna Creek ,,,,,,,,,,,,,,,,,,,,,,,, Small flow; minor effect on channel, Shinumo Creek ,,,,,,,,,,,,,,,,,,,, Large flow; considerable scouring in places in the channel; several mudflows in upper part of watershed; probably one of the highest flows since 1890. Tapeats Creek ,,,,,,,,,,,,,,,,,,,,,, Small flow; essentially no effects on channel Deer Creek ,,,,,,,,,,,,,,,,,,,,,,,, Moderate flow; minor scouring in channel, race, older floods have been considerably larger. Debris from a previous large flood is present near the conflu- ence of Lava and Chuar Creeks. Low terraces indicate previous floods much larger than the flood of 1966. No information available. Flood peak of 1936 is the highest of record; the flood caused only moderate channel scouring. Flood of 1966 removed all evidence of previous floods in reaches of Milk, Dragon, and Crystal Creeks traversed by mudflow, A large flood a few years before 1966 removed vegetation and loose rocks from channel. No information available on higher floods, Wood debris and drift from larger floods in channel; evidence of an old mudflow probably formed duringthe flood of 1961 covers parts of terraces. None. mudflows in the Crystal and Chuar Creek drainage basins extended to the Colorado River; at least nine others flowed more than 0.5 mi (0.8 km). These are the first mudflows reported in the Grand Canyon, although an older mudflow was recognized along Tapeats Creek during this investigation. Evidence that mudflows were a major part of the floods of 1966 in Natchi-Lava-Chuar, Milk-Dragon- Crystal, and other drainages includes the following: (1) An aggregate of mud, sand, and small pebbles was plastered on the sides of stream channels in many places (fig. 22). (2) In the reaches having mudflows, preflood gravel bars, 10w terraces, and other features were largely obliterated. (3) Differences in elevation are more than 12 ft (3.7 In) between the highest mudmarks 0n the opposite sides of the channel of Dragon Creek—less along others—where the distance between the mud- marks is only about 150 ft (46 In). (4) Pebbles were transported as suspended sediment and were deposited on large boulders (fig. 22). The FIGURE 22.—Debris deposited by mudflows in Hindu Amphitheater and Natchi Canyon. Muddy debris plastered by the mudflow along the channel of Dragon Creek in Hindu Amphitheater is as much as 3 in. (76 mm) thick, where it has not been removed (arrows) by subsequent streamflow. TRIBUTARY GORGES OF GRAND CANYON— FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS boulders are positioned more than 20 ft (6 m) from the nearest bank, as indicated by the mudmarks that outline the peak of the flow. (5) Silt, sand, and small pebbles were plastered on tree trunks and limbs and on logs that were trans- ported and deposited at the highest level attained by the flood. (6) Fine plant debris is generally absent along the mud- line. (7) Remnants of lobes of muddy material were formed along the borders of the areas affected by the floods (figs. 22, 23). (8) At the confluence of Milk and Dragon Creeks, muddy material from Milk Creek flowed over the low divide between the two creeks and accumu- lated along the bank of Dragon Creek above its floodline. The flood of 1966 also caused at least 80 debris slides or debris avalanches in the area between Saddle Can- yon and Shinumo Creek (pl. 1; fig. 24). This is the greatest number of debris slides known to have occurred in this area during a single storm in' the 20th century. Most of the debris slides originated on the Hermit Shale or on the upper part of the Supai Formation. As indicated by the bedrock exposed in the scarred areas, the slides generally picked up additional detritus en route down the steep Supai slopes and came to rest in the bottoms of the canyons, where most of the material was carried downstream by floodwater. In many places the only evidence of a debris slide is the fresh scar left by the jumbled mass of material as it cascaded down the steep slopes. In other places muddy debris formed small, rounded, partially lobate, discontinuous ridges along the borders of the slide area or in the bottoms of the canyons at the terminus of the slide. The flood of 1966 was not the first to cause debris slides and mudflows in the eastern Grand Canyon area in the 20th century. An older mudflow, which may have occurred in 1961, was recognized along Tapeats Creek; a few debris slides formed prior to the flood of 1966 were noted near the mouth of Deer Creek, and boulder de- posits along Crystal Creek upstream from Dragon Creek indicate a relatively old mudflow along that drainage (pl. 1).Other scars caused by debris slides that formed before 1966 are present in the heads of most of the side gorges. Many slides cannot be seen readily except from the air. The scars are in different stages of healing and indicate that in past decades or centuries debris slides have been rather common along the north rim of the Grand Canyon. Past mudflow activity must have been more common than generally recognized in the eastern Grand Canyon because (1) many debris slides, which have scars partly healed by vegetation, are apparent along the north rim escarpment and (2) accumulations of large boulders at the mouths of Unkar and Bright Angel Creeks, Fossil Canyon, and other 25 FIGURE 23.——Lobes of the light-colored mudflow that terminate (solid line) in the vegetation on a low terrace in Natchi Canyon. The mudflow was a few inches thick and moved in the direction of the arrow. FIGURE 24.—Scar of the main mudflow-debris slide that contributed much debris to the mudfiow in Natchi Canyon. Aerial view. Direc- tion of movement (arrow) was from left to right over the almost vertical cliff at left edge of photograph. drainages are similar in appearance to those deposited by the 1966 mudflow at the mouth of Crystal Creek. NANKOWEAP CREEK BASIN The Nankoweap Creek basin heads in steep-walled amphitheaters, which received large amounts of pre- cipitation during the storm of December 1966 (pl. 1). In two amphitheaters—one on the trunk Nankoweap Creek and the other on a tributary south of Brady Peak—the debris slides were sufficiently fluid to form true mudflows that moved short distances downstream along the canyon floors. The mudflow south of Brady Peak probably was derived from four main slides and extended nearly 0.5 mi (0.8 km) downstream (pl. 1). The 26 mudflow along Nankoweap Creek originated from two slides and extended about 1 mi (1.6 km) downstream. The channels in which these mudflows occurred tend to be straighter than those unmodified by mudflows; they now occupy sharply defined notches 8—10 ft (2.4—3.0 m) deep. The amount of channel deepening is not easily discernible but appears to have been from 1 to 4 ft (0.3 to 1.2 m). Downstream from the reaches affected by the mud- flows, the channel of Nankoweap Creek progressively widens and reaches its maximum width in the area EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA northwest of Nankoweap Butte, where the creek and its major tributaries are bordered by well-developed gravel terraces as much as 100 ft (30 m) high (pl. 1). Farther downstream, the creek flows through narrow Nan- koweap Canyon before it empties into the Colorado River. Although much channel modification occurred in the reaches north ofNankoweap Butte and at the mouth of Nankoweap Creek, no appreciable downcutting or aggradation occurred in Nankoweap Canyon as a result of the flood. The channel of Nankoweap Creek north of Nan- A A. a 3' NORTH SOUTH NORTH METHES SOUTH MEFRES 0 10 20 30 40 5o 50 7g 80 0 10 20 30 40 50 60 70 80 l l | l l | | | l 1 40 l I | l l l | l 5°Il|ll|lll|lI115 IIIIIIIIIIIIII 1.5-ftsdiamerer (4.6m) O N 10 4° 3.0-ft-diameter (0.9 m] — 30 cottonwood growing on 0 E muonwood 10 large Boulder Bar 2 m _ 2° Logsdeposiled by “ 5 (A flood of December _ E 20 — E E 10 1966 _ Q E *5 [I] E Terrace E o Bedrock E m _ e — 0 _E0 Reddlsh-brown - uni‘ g Channels deepened during flood D "b . _. .9 ‘ fi_ 0 of December 1966 and probably Downstream edge of ‘10 aner peak had passed * Boulder Bar 1 .10lIIIIlIIlIlll .IEIIIIIIIIIIIIIIT‘5 ° 2° 4° 6° 5° 10° 12° ”0 '60 13° 20° 27° 24° 250 o 20 40 so so 100 120 140 160 130 200 220 240 260 FEET FEET C C D U NORTH 5 TH METRES 0” NORTH METRES SOUTH 180 190 200 210 o 10 20 so 40 so so 70 80 l | l l l l I I l I I I I 30 k——183m—‘>l | I I I I 1° 30_I I I I I I I I I I I I I ‘0 m m— _ Break in 5 Terrace Reddish-brown unit _ 5 3 SECIIOH I r— 10 33 E 10 ~— — I— o: Bedrock u.I ¥ Terrace ______ m E 2 D ~n-.-. . .. .e. Bd k 0 5 0* __0 Channel probably deepened during 9 '°° Boulder bar early stages and aggraded during '10 waning stages of flood of December 40 _ _ 1966 _5 l I l I I I l I l I l l | _20 Hanan—*4 I I I l | n 20 40 so 100 120 140 160 130 200 240 260 620 640 660 680 700 FEET FEET E F NORTH SOUTH m m Bedrock Dissected 20 Break in Logs deposited by flood alluvial fan __ section of December 1966 ~ 5 m m m — E “J E l E o ——0 Boulder bar deposited malnly .10 during flood of December 1966 E 6 H—Eeoomwaml—fl F F NORTH SOUTH 1 30 r ‘ Ruins of rock terraces 20 — built by Pueblo Indians — '— Slope to Colorado River about A’D' “00 — 5 m mw~ — m m IL ‘_ ______ 5 .eo-epe‘sis. °° ‘ __ o E BMb/f mMn / OH 2 if I r “mo" Dissected -10 — alluvial Ian A L 4 I moor: Isosrnl ,‘ NANKOWEAP CREEK FIGURE 25.—Sketch map and sections, Nankoweap Creek and Nankoweap Creek tributary. TRIBUTARY GORGES OF GRAND CANYON—FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS koweap Butte contains large gravel bars that extend across the channel and give the creek a stepped profile (figs. 3, 25, 26). Each bar consists of gravel deposits dissected by floodwater channels as much as 3 ft (0.9 m) deep and 20 ft (6 m) wide (fig. 26). The bars are rela- tively stable as shown by the scattered cottonwoods and brushy plants. Logs and other recent flood debris indi— cate that the bars were covered by the flood of 1966 (fig. 25, section B-B ’). The downstream ends of the bars are well defined and have a relief of between 2 and 8 ft (0.6—2.4 m). (See fig. 26A.) During the flood of 1966 and previous floods, the main channel shifted laterally along many of the snouts of the bars and caused consid- erable cutting, which may account for much of the high relief at the downstream ends of the bars. Nankoweap Creek has built a rather large alluvial fan into the channel of the Colorado River. Remnants of older alluvial fans are present on both sides of the creek near the river (pl.1). As a result of the flood of December 1966, Nankoweap Creek deposited a small fan of peb- bles to small boulders in the Colorado River along the upstream side of the older alluvial fans. The new fan extends about 150 ft (46 m) into the river and is about 300 ft (90 m) wide. The building of this and older allu- vial fans has confined the channel of the Colorado River to its left bank, where its low-water channel is about 100 ft (30 m) wide. The detritus from the 1966 flood caused only a narrowing of the river channel and did not A A, SOUTHWEST NORTHEAST METRES o 5 To 15 20 I I l I I 4° I I I I l I k—— som.——-I —10 so _ 20 T 3 W 5 (I m E 10 Terrace — o ________ ' 0 Break in SEEIIOH —Io — I I I I I I I I-——— 100 rt——-I I 5 4/ ~... @40 \{Vegp \qeq, tributary '- ‘-/ "J Inset NOTE, See Inset and plate 1 for locations 27 change the configuration of Nankoweap Rapids. Effects of the deposition during the flood of 1966 are apparent for about 0.75 mi (1.2 km) upstream along Nankoweap Creek, where gravel-bar accumulations at- tain heights of about 6 ft (2 m) above the streambed. The south side of the channel of Nankoweap Creek is cut into a 5—7-ft-high (1.5—2.1-m-high) gravel terrace. Rock walls or terraced plots, which probably were built by the Pueblo Indians, are present along the top of the terrace. At sectionE—E’ (fig. 25) the crest of the flood was about 1 ft (0.3 m) below this terrace. Downstream at section F—F’ (fig. 25), where the terrace is slightly lower in relation to the streambed, water inundated the low parts of the terrace but did not cover the terraced plots built by the Pueblo Indians. The relation of the floodline to the terraced plots indicates that the flood of 1966 was one of the largest that has occurred in Nankoweap Creek. KWAGUNT CREEK BASIN Kwagunt Creek drains a narrow watershed between the larger Nankoweap and Chuar Creek drainages. Al— though the peak flow of 1966 was large (table 2), the amount of channel damage was rather moderate. The low-water channel of Kwagunt Creek was smoothed and straightened. At sections A—A ’and B—B' (fig. 27), the channel was not deepened appreciably by the flood, but fresh scars, which are generally less than 4 ft (1.2 m) wide, were cut along the sides and into the B B' NORTHEAST SOUTHWEST METH ES 0 10 20 30 40 50 60 70 80 40 | I I I I I I I I I 30* —I 20— 7 FEET I METRES Reddish- brown unit E_ 0 \ Break In 0 — section ~10~ _ H 5 .20 I I | I | | | I I | I I | o 20 40 so so 100 120 140 150 130 200 220 240 260 FEET 4/0,“,0 A N “’69 T O. “'94 B 5.0—6.0" (Ls—Lam) n» . I” B D A 45 k B' Bar? 2 Bari!“ a Cyee " A “NV" 8.0fr(2.4m) B C’ D' Earl _ A, 3.0—4.0" (0.9-1.2 m) INSET Length of Inset is about 1.0 mi (1.6 km] NANKOWEAP CREEK TRIBUTARY FIGURE 25.—Continued. 28 FIGURE 26.—Gravel-floored channel of Nankoweap Creek near site 15 after the flood of December 1966. A, Looking upstream along Nankoweap Creek across section A—A’. (See fig. 25.) View is from small gravel bar upstream from gravel bar 2 to the lower end of gravel bar 1, where the three men are standing, approximately along section A—A’. B, Looking downstream along Nankoweap Creek. The narrow channel at section C—C’ in figure 25 is in the center of the picture and is where the peak of the flood of December 1966 was 31/2—4 ft (1.1—1.2 m) above the present channel. The low 5-ft-high (1.5-m-high) terrace (arrow) in the left-center of the pho- tograph was not inundated. During the flood peak, the channel at section C—C’ apparently was deepened and was filled by pebble- to small-cobble-size material during the declining stage of the flood. bottom of the channel. The depth of the channel has been nearly stable during the last century or possibly longer, as indicated by the root-crown positions of the 2-ft-diameter (0.6-m-diameter) junipers that are less than 2 ft (0.6 m) above the present streambed. The flood of 1966 inundated only the lowest—2—4 ft (0.6—1.2 m) above the streambed—of multiple-fill ter- races (fig. 27, sec. A—A ’). Debris transported during the EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA flood accumulated as a small gravel fan at the mouth of Kwagunt Creek. The fan protrudes between 50 and 75 ft (15 and 23 m) into the Colorado River and is about 125 ft (38 In) wide along the shoreline. CHUAR CREEK BASIN The Chuar Creek drainage was more affected by the flood of December 1966 than any of the drainages eastward from the Kaibab and Walhalla Plateaus. The greatest amount of channel modification was in Natchi Canyon, where the principal mudflow originated, and along Lava Creek. HEADWATERS AREA Several debris slides joined to form mudflows in the headwaters of Lava Creek and Natchi Canyon. The principal mudflow originated southwest of Naji Point in Natchi Canyon._At least part of the mudflow was rather viscous, as shown by mounds of mud still re— maining at the bases of the cliffs; however, most of the muddy debris entered the channel of the trunk stream that drains N atchi Canyon and continued downstream along Lava and Chuar Creeks to the Colorado River. Near the head of Lava Creek, a viscous mudflow (pl. 1), which was smaller but similar to the one in Kanab Canyon (see the section entitled “Mudflow at the Mouth of Kanab Canyon”), accumulated debris as an elongate mound at the base of the canyon wall. CONFLUENCE OF NATCl-ll CANYON AND LAVA CREEK The channels of the trunk stream in N atchi Canyon and Lava Creek were studied on the ground at their area of confluence south of Poston Butte. In Natchi Canyon above the confluence, muddy debris accumu- lated on the lower terraces that line the channel and was plastered on trees and large rocks as much as 16 ft (4.9 m) above the streambed. Near sections A—A’ and 3—3 ’ in figure 28, the lower boundary of the mudmarks is less than 2 ft (0.6 m) above the present (1967) streambed, which suggests that little deepening of the channel could have occurred after the mudflow. In one place 31/2 ft (1.1 m) above the streambed, the mudflow did not remove the litter that had accumulated under a 2—ft-diameter (0.6-m-diameter) juniper. In other places, however, large scours were gouged in the channel, par— ticularly downstream from large boulders. Near sections A—A’ and B—B’ in figure 28, differ- ences in the height of the mudmarks are about 2 ft (0.6 m) on opposite sides of the channel. By the time the mudflow reached this area, it was more fluid than it was in the upstream reach, where differences in the height of the mudlines on opposite sides of the channel were greater. The mudflow deposited a thin mantle of TRIBUTARY GORGES OF GRAND CANYON—- FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS M ETR ES 0 5 10 15 20 25 30 35 FEET METRES FEET Upstream from site 17 29 M ETR ES 0 5 10 15 20 25 30 35 40 Drift from flood of December 1966 Floodline METRES I I I I I I I I I I I I I I | 100 110 120 130 140 Downstream from site 17 KWAGUNT CREEK FIGURE 27.—Sections along Kwagunt Creek near site 17. debris where it spread out on the terraces (fig. 23). The mudflow was moderately fluid and formed a few ridges and lobes as it moved rather uniformly around rocks and vegetation without bending many of the plants. The flood of December 1966 caused considerable change in the wide part of the canyon that extends 0.25 mi (0.4 km) downstream from the confluence of Natchi Canyon and Lava Creek. The area contained a swamp and supported a heavy growth of reeds and similar vegetation when it was visited by RC. Euler in the summer of 1966. Coarse gravel bars, which have a maximum relief 0f6 ft (1.8 m) deposited by the flood of December 1966 obliterated the swamp (fig. 29A). Along section D—D’ (fig. 28) root crowns of 1— 2-ft-diameter (0.3—0.6-m-diameter) cottonwoods are es- timated to be buried 2 ft (0.6 m) below the present (1967) stream channel. In section D—D’ (fig. 28) the mudline is slightly above the top of the gravel bars and is only 7 ft (2.1 m) above the present streambed. A short distance downstream from section D—D’, mudmarks are not visible along the sides of the channel because the marks left by the mudflow were buried beneath the gravel deposits; therefore, considerable streamflow and gravel deposi- tion apparently occurred after the mudflow. The gravel forms a large bar; the downstream end of the bar is between sections D—D’ and E—E’ (fig. 28). At its ter- minus, the bar is 125 ft (38 m) wide and 10 ft (3 m) high. Natchi Spring now issues from the downstream end of the bar and heads a short reach of perennial streamflow. At the time of Euler’s visit in the summer of 1966, the perennial streamflow extended upstream to about the junction of Natchi Canyon and Lava Creek. LAVA CREEK. SITE 21 At site 21 between Natchi Canyon and Chuar Valley (pl. 1; fig. 29B), large boulders have lodged together and form barriers that drop off 5—10 ft (1.5—3.0 m) on the downstream side and give the longitudinal profile of Lava Creek a step appearance. The flood accen- tuated the drops by removing all the loose material and brush. In a relatively straight reach of the channel within 100 ft (30 m) upstream and downstream from one of these barriers, the mudline was 6 ft (1.8 m) above the streambed and barely above a 5—6-ft-high (1.5~1.8-m-high) terrace. A minimum flow depth of3 ft (0.9 m) occurred at the crest of the barrier, and a maximum flow depth of 9 ft (2.7 m) occurred at the lower side of the barrier where scouring took place. Generally, the scours were 2—3 ft (0.6—0.9 m) deep, but some scours were as much as 5 ft (1.5 m) deep. Lateral cutting was generally less than 2 ft (0.6 m), although in places the channel was widened by as much as 6 ft (1.8 m). The small deposits of vegetal debris at the edges of the flow indicate that the mudflow was much more fluid here than it was near the mouth of Natchi Canyon. (1H ['AR VALLEY Near the confluence of Lava and Chuar Creeks in Chuar Valley, the valley floor is generally more than 150 ft (46 m) wide. The channel is braided and contains broad 3—5-ft-high (0.9—1.5—m-high) gravel bars (fig. 29C and D) that were deposited by the flood of 1966 and previous floods. A short distance downstream from sec- tion F—F’ (fig. 28), marks from mud and debris extend only 3 ft (0.9 m) above root crowns of 4-ft—diameter (1.2-m—diameter) cottonwoods that are at the level of the present (1967) streambed. Generally, less than 2 ft (0.6 m) of lateral cutting took place along the sharp bends and meanders. The sharp bends and some of the large preflood boulder bars formed barriers and di- verted the mudflow around low areas and over some terraces and other large bars. About 0.25 mi (0.4 km) downstream from the confluence of Lava and Chuar Creeks, where Chuar Creek makes several tight bends, the mudflow left marks that are as much as 4 ft (1.2 m) above the streambed on the inside of the bends and 7 ft (2.1 m) on the outside of the bends. 30 At section F—F’ (fig. 28), the mudflow inundated a preflood boulder bar, which is as much as 7 ft (2.1 m) above the channel floor. Freshly battered logs of pon- derosa pine and one weathered ponderosa pine log EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA stranded from a previous flood were left on the summit of the bar; the logs indicate the flood of 1966 and the previous flood were of the same order of magnitude. Although the mudflow inundated the summit of the A. NORTH METRES SOUTH 25 30 35 40 45 50 55 60 65 __W_ 1 1 1 1 1 1 1 ‘ 1 “°‘ 1.724 "1* , 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Mudline16fl 15 m) 710 3° Mudline 141511144 m1 m“ “meme" F above streambed m ,_ 20 . I _ — u w Landshde Break In _____ 7 5 E u. and talus section ____________________ Bedrock "” 10 a 2 o #e o .10 , 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Peon—.1 90 100 110 120 130 140 150 160 no 130 190 200 210 220 FEET Natchi Canyon, 0.4 mi (0.6 km) upstream from mouth of canyon 19 3' N RTH SOUTH 0 METRES 30 35 4o 45 so 55 so 65 50 1 1 1 1 1 1 1 1 y 1 ‘ _15 1&_30m “’11 1 1 1 1 1 1 . 1 1 1‘* 61 m, *1 40 - — . Mudline 8 ft (2.4 m1 _ . . 51935 ”'1 above streambed 2D~ft>dtameter (0.6 rn) iunipar, 7 '0 30 R Seclllon small remnant of thm sotl a , and vegetation debris under m E Mudllne 10 fl (3 "‘1 mud incrustation at root crown W m 20 W above streambed 7 E 1t #5 g 10 _Landslide ‘‘‘‘‘‘‘‘‘‘ Break in Landslide and talus »»»»»»»»»» section and talus o e ee 0 .10 1 1 1 1 1 1 1 1 1 4 1 1‘w100f‘ | 110 120 130 140 150 160 170 180 190 200 210 1.._zoof._;y1 ~ FEET Natchi Canyon, 0.25 mi (0.4 km) upstream from mouth of canyon C c' WEST EAST MFI'RES 45 50 55 so 65 7o 1 1 1 | 1 1 10 30.; 445m1‘7 1 1 1 1 1 1 1 | 1"_46m_~1 ‘ 1— 20P great in ’ —_5 $ m SeCtan K tu ‘ l— LL 1 R / — m Terrace Break in Landslide E 0 _ section and talusg; 0 1 1 1 1 1 1 l 1 .10 $1 15011 1‘. 160 170 130 190 200 210 220 230 1<_150n_..1 FEET Lava Creek, 0.2 mi (0.3 km) downstream from mouth of Natchi Canyon D D, NORTHEAST METRES SOUTHWEST o 5 10 15 20 25 so 35 4o 45 so 55 1 | 1 1 1 1 1 1 1 1 l 2 5° 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ‘5 14176 m 40 e A e 10 so ~ 1 m E 20 _ ~ E ,5 E 2 ‘0 iLandslide Terrace — and talus ‘ v — Break in as o ‘ 1 section 40 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 o 10 20 30 40 50 so 70 so 90 100 no 120 130 140 150 160 170 150 1+772501t7»1 FEET Lava Creek, 0.1 mi(0.2 km) downstream NATCHI CANYON from Natchi Canyon FIGURE 28.—Sections along the Natchi CanyonfiLava Creek drainage. TRIBUTARY GORGES OF GRAND CANYON—FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS bar, a depression, which is part of a side drainage that is from 3 to 4 ft (0.9 to 1.2 m) lower than the bar and between the bar and the left bank, was not inundated by water or mud during the flood of 1966. CLEAR CREEK BASIN Clear Creek basin shows severe erosional effects from the flood of December 1966. The floodflow from Walhalla Plateau funneled through a gorge and caused considerable scouring and lateral cutting. In places Clear Creek flows between alluvial terraces as much as 30 ft (9 m) high; lower terraces support dense stands of cottonwood and other riparian vegetation. In other places the creek is enclosed by a narrow bedrock gorge. Clear Creek was inspected only at its mouth and in the area of archeological sites near Ottoman Amphi— theater. Channel modifications caused by the flood in- cluded the clearing of brush, stripping of the lower limbs of trees, and lateral cutting into terraces. The lateral cutting removed part of a 6—7-ft-high (1.8— 2.1—m-high) terrace and partly destroyed a prehistoric Pueblo Indian mescal pit (fig. 14), which, according to Euler, was complete and well preserved before the 2V0‘ftrdia cot _ Hei Break in m“ section Landslide and talus FEET <——'200 h 1 L _l__L nJ—m 1 J 210 220 230 240 250 250 270 280 31 flood (see section entitled ”Relation of Prehistoric and Historic Occupation to Flooding”). The lateral cutting indicates only that the flood of 1966 was one of the largest along this drainage in several centuries. Only a small amount of debris was transported to the Col- orado River by Clear Creek. A few months after the flood, no evidence of deposits similar to those at the mouths of other streams was present at the mouth of Clear Creek; the Colorado flows at high velocity through a narrow rock gorge past Clear Creek. BRIGHT ANGEL CREEK BASIN In the upper part of Bright Angel Canyon, which was in one of the areas of concentrated precipitation during the storm of December 1966, several debris slides oc— curred in the amphitheaters near Uncle Jim Point (pl. 1). The slides furnished coarse and fine debris to the creek and possibly formed a mudflow that extended downstream slightly beyond the mouth of Roaring Springs Canyon. Evidence in support of a mudflow in the upper part of Bright Angel Canyon includes (1) a large boulder perched on top of a remnant of the rock dam at the confluence of Roaring Springs and Bright METRES 7o 75 1111., i T meter (0.6 m)\0 * (Onwood ght of dflow METRES . '4 Landslide and talus, 1__lIJJ FEET Lava Creek, 0.2 mi (0.3 km) downstream from mouth of Natchi Canyon METR ES 50 55 60 Tributary channel not inundated by flood of 1966 Wood debris from mudflow from flood Terrace cut in reddish brown unit of 1966 and a log from a previous flood North edge of mudilow METRES 40 70 30 90 _l__l._li__L_1__l__J__l___L___L—E:_i no no 130 140 150 160 170 130 190 200 nieoortfiw- FEET Lava Creek, 0.1 mi (0.2 km) upstream from confluence of Lava and Chuar Creeks NATCHI CANYON FIGURE 28.—Continued. 32 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA Angel Canyons (pl. 1) and (2) extensive flood damage to channels restricted mainly to the small tributary draining the amphitheater north of Uncle Jim Point and to Bright Angel Creek downstream from this tributary (G. L. Beck, oral commun., 1967). The mud- flow probably was extremely fluid and did not extend beyond the mouth of Roaring Springs Canyon, because there it was diluted by additional water from Roaring Springs. Between Phantom Ranch and the Colorado River, considerable mud accumulated on rocks and the sides of channels in backwater areas. Visual estima- tion of the amount of mud deposited indicates that Bright Angel Creek carried more sediment than Nan- koweap or Kwagunt Creeks and less than Lava-Chuar Creek. The long duration of high flow during the 1966 flood caused severe modification of the channel and flood plain of Bright Angel Creek. Before the flood in the Cottonwood Camp—Ribbon Falls area and downstream from Phantom Ranch, Bright Angel Creek flowed in a narrow channel that was generally 15-25 ft (4.6—7.6 m) wide and less than 4 ft (1.2 m) deep (fig. 30). The flood plain that adjoined the channel was as much as 200 ft (60 m) wide and was bounded by terraces between 4 and 8 ft (1.2 and 2.4 In) above the streambed. The stream channel was bordered by thick brushy and reedy riparian vegetation. The flood plain consisted chiefly of gravel bars of different heights mantled in places by considerable vegetation (fig. 12A). The flood of 1966 removed the riparian vegetation, rearranged or FIGURE 29,—Channels of Lava and Chuar Creeks after the flood of December 1966. A, Debris deposited around junipers and cotton- woods in the area where a swamp was present prior to the flood. B, Looking downstream along Lava Creek near site 21, where the creek is confined between terraces—few of which were inundated by the mudflow. Approximate height of flood crest is indicated by dashed lines. C, Looking upstream along Lava Creek from near its confluence with Chuar Creek. Note boulder bars deposited by the flood of 1966 and by older floods (fig. 27, section F—F’). D, Looking downstream along Chuar Creek from near its confluence with Lava Creek, which enters from the left. The terrace on the right was not inundated by the flood of 1966. The relation of the root crown of the large cottonwood in the right-center of the photograph (arrow) to the streambed indicates that little change in channel depth has occurred in the last few decades. Bank above cottonwood was eroded by the 1966 flood. TRIBUTARY GORGES OF GRAND CANYON— FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS FIGURE 30.—Bright Angel Creek 1,000 ft (305 m) above mouth. A, Channel in August 1963. N 0 channel changes occurred between 1963 and 1966. B, Channel after flood of December 1966. The arrows in photographsA andB may be used to establish a common reference at the Kaibab Trail. scoured the bars, obliterated the channel, and removed part of the 4—8-ft-high (1.2—2.4—m—high) terrace (fig. 123). The ranch buildings at Phantom Ranch are on a low terrace on the left bank of Bright Angel Creek and are 6—8 it (1.8—2.4 m) above the present (1967) streambed. The buildings are along the insides of a broad bend that tends to keep the flow of the creek along its right bank. Along the downstream part of the terrace, the floodflow was diverted by gravel bars formed during the flood and by bedrock protrusions that affect only high flow, causing the stream to cut a flood channel (fig. 13) from the right bank to the left bank. Between Phantom Ranch and the Colorado River, lateral cutting into the 4—8-ft-high (1.2—2.4-m-high) terrace gouged crescent- shaped scours that, in places, were more than 30 ft (9 33 FIGURE 31.—Mouth ofBright Angel Creek after the flood ofDecember 1966. The only remaining undamaged bridge over Bright Angel Creek is in lower right (arrow 1). Trail at left center (arrow 2) connects Colorado River suspension bridge with Phantom Ranch, which is behind the viewer. Channel boundaries before the flood were approximately as outlined by the dashed lines. m) wide. Much of the Phantom Ranch Campground was eroded (fig. 14). The alluvial fan at the mouth of Bright Angel Creek is several hundred feet wide. The flood deposited peb- bly to bouldery sediment on the fan and as far as 1,000 ft (305 m) upstream from the mouth. At the foot bridge near the gaging station, the channel was filled to a depth of 4—6 ft or 1.2—1.8 m (R. J. Starkey, oral com- mun., 1967). The boulder riffle formed by the front edge of the fan in Bright Angel Creek is the control for the gaging station on the Colorado River. Prior to the flood of De— cember 1966, the head of the riffle was opposite the upstream side of the fan. Bouldery debris deposited by Bright Angel Creek during the flood caused the head of the riffle to move downstream several hundred feet to a point opposite the downstream side of the fan (fig. 31). Personnel familiar with this gaging station have esti— mated a drop of 6—9 ft (1.8—2.7 m) in channel elevation from the head of the riffle to the mouth of Bright Angel Creek; a 1924 profile of the Colorado River indicates a drop of about 6 ft (1.8 m). The stage-discharge relation at the station had remained almost constant since the station was installed in 1922. In the Colorado River the stage required for a given discharge after the flood was 4 ft (1.2 In) higher than that required for the corre- 34 FIGURE 32.——Bright Angel Creek near Phantom Ranch before and after the flood of August 1936 (see figs. 12, 13, 14). A, Channel of Bright Angel Creek in May 1936. The trail to Phantom Ranch is bounded by line of rocks in left foreground. B, Looking upstream after the flood. Trees in center background are the ones shown near the center of fig. 13. C, The preflood channel is indicated by the bridge and gaging station. Looking upstream from a site near the footbridge shown in figure 31. sponding discharge before the flood, which indicates that the new deposit of gravel and boulders at the mouth of Bright Angel Creek accumulated to a depth of at least 10 ft (3.0 m). EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA Although the peak discharge of the flood of August 19, 1936, in Bright Angel Creek was higher, the dam— age and channel modification caused by the flood of 1936 along most of the channel was much less than that caused by the flood of 1966 owing to the relatively short period of high flow. The flood of 1936 removed part of the vegetation on the flood plain and caused only minor lateral cutting into the 4—8—ft-high (1.2—2.4-m—high) terrace (fig. 32). The channel was se- verely modified in 1936 but was not destroyed as it was during 1966. Near the mouth of the creek and up- stream from the present gaging station, the flood of 1936 deposited a large gravel bar, which caused a di- version of the channel from the left to the right bank (fig. 32C); the channel remained in this position through the flood of 1966. CRYSTAL CREEK BASIN When viewed from the air, the reach of Crystal Creek basin that was inundated and modified by the flood of December 1966 is marked by mud and debris which extends as a continuous buff band along Milk and Dragon Creeks downstream to the confluence of Crystal Creek with the Colorado River. The band of mud, which shows the maximum extent of the flood, is particularly conspicuous on the dark schist in the gorge of Crystal Creek below Dragon Creek. In con- trast, only a moderate amount of flow and minor ero- sion occurred along Crystal Creek upstream from its junction with Dragon Creek (fig. 8; table 2). The flood of December 1966 in Crystal Creek is con- sidered to have consisted of three main stages: (1) the streamflow before the mudflow, (2) the mudflow, and (3) the streamflow after the mudflow. As indicated by the mudline, the mudflow formed the crest of the flood. Downstream from the confluence of Milk and Dragon Creeks, the evidence can be interpreted to indicate that the mudflow may have consisted of either a single pulse or multiple pulses. The muddy debris was plastered in layers as much as 3 in. (about 80 mm) thick on the sides of the channel (fig. 22) and on large boulders and trees throughout the banded reach. Parts of the channel sides were smoothed, the edges of the terraces were rounded by the mudflow, and the channels of the tributaries were left several feet above the bed of the main stream (fig. 33). The muddy detritus is pale reddish brown to light brown and consists of a heterogeneous mixture of silt, very fine to fine sand and sandstone, chert, and limestone fragments less than 1 in. (about 25 mm) wide. The sand is principally subrounded to subangu- lar clear and stained quartz similar to that in the Supai Formation and Coconino Sandstone. TRIBUTARY GORGES OF GRAND CANYON—— FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS 35 FIGURE 33.—Mudflow in Dragon Creek at the mouth ofDragon Creek tributary 2 in the upper Hindu Amphitheater. The mud flowed from left to right over the terrace at the right side of the photograph and smoothed and rounded the edge of the terrace back as much as 3 ft (0.9 m). Although the crest of the mudflow (dashed line) was 28 ft (8.6 m) above the bed of Dragon Creek, the mudflow did not move laterally into tributary 2. The bed of tributary 2 (arrow) was left “hanging” 12 ft (3.7 m) above the postflood bed of Dragon Creek where the man is standing. The net change in the channels of Milk, Dragon, and Crystal Creeks, which were traversed by the mudflow, is one of deepening, except where aggradation took place in the short reaches upstream about 0.25 mi (0.4 km) from inner gorge 1, at location R in inner gorge 2, and at the mouth of Crystal Creek (pl. 1). Although the amount of downcutting is difficult to de- termine in most places, 1.2 ft (3.7 m) occurred at the mouth of Dragon Creek tributary 2 (fig. 33). In many places the downcutting probably was more than 5 ft (1.5 In) but in general probably was not more than 10 ft (3.0 111). Narrow 10-15-ft-deep (3.0—4.6-m-deep) trenches were cut downstream from two knickpoints on Dragon Creek. Part of the trenching may have taken place before 1966. The lowest mudmarks are within 5 ft (1.5 m) above the streambed near site 46, near the mouth of Dragon Creek tributary 2, and in the « Hindu Amphitheater. Therefore, it appears that most of the channel deepening was caused by the floodflow that preceded the mudflow and (or) by the mudflow rather than by the streamflow that occurred after the mudflow. The amount of lateral cutting that took place during the flood of December 1966 seems to have been slight—— generally less than 10 ft (3.0 m)——and places where lat- eral cutting exceeded 25 ft (7.6 m) are uncommon. The muddy debris was deposited on the channel sides and formed a general protective mantle against erosion by postmudflow streamflow; fresh scars that would indicate postmudflow cutting, caving, or slumping of the banks were observed only in a few places. UPSTREAM FROM HINDU AMPHITHEATER In the Milk Creek drainage area 12 fresh scars from debris slides or avalanches were noted during a helicop- ter reconnaissance flight (pl. 1). The amount of debris that composed a single slide was not sufficient to form the mudflow that moved downstream along Milk, Drag— on, and Crystal Creeks. Therefore, the mudflow proba- bly was formed by the coalescing of several debris slides and the picking up of considerable material in the stream channel en route. Along Milk Creek upstream from its junction with Dragon Creek, the flood radically changed the charac- teristics of the channel—more than in any other reach in the Crystal Creek basin—and the mudflow cleared the channel and canyon floor of loose rock and vegeta- tion (fig. 34A; fig. 35, section A—A ’) by as much as 25 ft (7 .6 m) above the present streambed. It is difficult to delineate the multiple-fill terraces in the reach because their edges were rounded and in places were covered by a layer of muddy detritus. Scours that are a few feet deep and large boulders stranded from the mudflow are common on the channel bottom. In contrast with Milk Creek, the channel of Dragon Creek above its conflu- ence with Milk Creek was not modified by a mudflow and shows only the effects of flowing water (fig. 35, section A—A ’). At the mouth of Milk Creek, the channel of Dragon Creek is fairly smooth and does not contain large scours. However, about 0.10 mi (0.16 km) downstream, the channel is interrupted by a 10—15-ft-high (3.0—4.6-m- high) knickpoint, which probably formed violent rapids during the flood. The knickpoint consists of uncemented coarse alluvium that includes boulders more than 10 ft (3 m) long. The boulders are wedged so tightly that they restrict rapid downcutting. Mudmarks are preserved in the lower end of the trench, but none were found in the upper end of the trench adjoining the knickpoint, al- though the top of the mudflow was 7—12 ft (2.1—3.7 In) higher than the lip of the trench. It appears, therefore, that the upper end of the trench was excavated and that the knickpoint advanced several tens of feet during the streamflow that followed the mudflow. Downstream from the knickpoint at section B—B’ (fig. 35), the gradient flattens slightly, the channel widens (fig. 34B), and mud is plastered on the channel sides between 6 and 12 ft (1.8-3.7 m) above the streambed. Large boulder bars having as much as 5 ft (1.5 m) of relief suggest that some deposition took place during the flood. Perhaps part of the material removed from the EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA channel, as the knickpoint was advancing upstream, was deposited in this reach. The lowest terrace, which is 11 ft (3.4 m) above the present channel and was barely inundated, is capped by a thin soil (fig. 35, sectionB—B ’). Between sections B—B’ and C—C’, the channel of Drag- on Creek widens progressively, the amount of gravel deposited by the flood decreases downstream, and the height of the mudline decreases from 12 ft (3.7 m) to 61/2 ft (2.0 m) above the streambed. At section C—C’ (fig. 35), a 1,000-ft-long (304.8—m-long) reach of Dragon Creek was aggraded during the flood, and gravel was depos- ited in broad irregular bars as much as 6 ft (1.8 m) high. A remnant of a 6-ft-high (1.8-m-high) terrace, which was somewhat protected along the inside of a bend and was barely flooded, is mantled by a soil that supports upright reeds and brush. Mudmarks across the streambed on the outside of the bend, where the velocity of the current was at a maximum, were at least 10 ft (3 In) above the channel; however, splashing made the exact placement of the mudline difficult. Below section C—C’ in the 0.30 mi (0.5 km) reach upstream from inner gorge 1, the channel of Dragon Creek is entrenched between 20—30-ft-high (6—9-m- high) terraces composed of material that includes boul- ders as much as 10 ft (3 m) in diameter. The channel depth is accentuated by a sharply defined knickpoint, which probably was present before the flood but was deepened and extended by the flood into the lower part of the aggraded reach centered at section C—C’. The trench formed at the knickpoint has nearly vertical walls, is 15—20 ft (4.6—6.1 m) deep, and contains large scours. The intensive scouring and differences in the height of the mudmarks, which in one place are 17 and 33 ft (5.2 and 10.1 m) above the bed of the creek on opposite sides of the channel, indicate that turbulent and shooting flow occurred across and near the knickpoint. Between inner gorges 1 and 2, the channel of Dragon FIGURE 34.—Effects of the flood and mudflow of December 1966 in Milk and Dragon Creeks. A, Cleared and smoothed channel ofMilk Creek after the mudflow. Note that the mudfiow cleared the channel of gravel, loose boulders, and vegetation. B, Channel of Dragon Creek looking downstream from section 373’ (fig. 35). Terraces along both banks were damaged but not destroyed. The lower 4 ft (1.2 m) ofthejuniper in the right foreground is plastered with mud. Crest ofmudflow is indicated by arrow. C, Channel ofDragon Creek looking downstream in the main part of the Hindu Amphitheater toward the mescal pit (Ariz. B:16:42), where the men are standing (arrow). Muddy debris deposited by the mudflow in left foreground extends downward to within 3 ft (0.9 In) of the present streambed. Cutting by the mudflow and streamflow stages ofthe flood formed a benchlike feature on the left bank 6-7 ft (1872.1 m) above the streambed. TRIBUTARY GORGES OF GRAND CANYON— FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS A A. T M ETRES EAS —60 6.0 ft (1.8 m) or more of mud on tree from flood l 8 Lott-diameter (0.3 ml juniper l N O METRES Terrace modified by flood o FEET Milk Creek, 0.3 mi (0.5 km) upstream from mouth B 3' EAST METRES 140 l l I I l ‘Wllllllilliiiil 1.0—ft-diameter (0.3 m) juniper 160 180 FEET FEET Dragon Creek, 0.50 mi (0.8 km) downstream from mouth of Milk Creek 37 M ETH ES 0 10 20 30 40 50 Multi le-fill 5° " Multiple-fill p terrace Floodline .. 10 s n ' FEET to m METRES 150 100 FEET Dragon Creek, 0.3 mi (0.5 km) upstream from mouth of Milk Creek 100 — Gravel bar formed by flood debris Riparian vegetation 20 — Mudline 6.5—7.0 ft (2.0-2.1 m) METRES FEET 8 METRES 200 FEET Dragon Creek, 1 mi (1.6 km) downstream from the mouth of Milk Creek NOTE: See plate 1 for section location FIGURE 35.—Sections along Dragon and Milk Creeks. Creek is 50—70 ft (15-21 m) wide and adjoins prominent vertical-faced terraces that generally are between 15 and 35 ft (4.6 and 10.7 m) high (fig. 7). Limestone is exposed in the streambed for a few tens of feet at inner gorge 1 and for about 0.75 mi (1.2 km) between inner gorge 2 and tributary 2. The mudline between inner gorges 1 and 2 is as much as 44 ft (13.4 m) high, which is the highest mark measured along the entire drainage. The high mudline resulted from shooting flow that swung around a bend. The mudline lowered pro— gressively as the channel straightened downstream from the bend; in a distance of 150 ft (46 m), the height of the mudline decreased to 21 ft (6.4 m). At the mouth of tributary 2, the mudline on the right bank of Dragon Creek is as low as 16 ft (4.9 m) above the streambed, whereas, the mudline on the left bank is 28 ft (8.5 m) above the streambed. In places the mudflow covered parts of the enclosing terraces; for the most part, how- ever, the mudlines are 1 or 2 ft (0.3 or 0.6 m) below the tops of the terraces. Near site 46 (figs. 7, 17), the flood inundated most of the terrace that was 14—16 ft (4.3 —4.9 m) above the streambed and destroyed or modified be- yond recognition the mescal pit (Ariz. B216141) that had been located the previous summer; the mudflow covered the entire canyon bottom. (See the sections entitled "Magnitude of Floods, Crystal Creek Basin” and “Rela- tion of Prehistoric and Historic Occupation to Flood- ing.”) The bed of tributary 2 at its mouth was 12 ft (3.7 m) above the bed of Dragon Creek when the site was Visited in February 1967; the tributary now must flow over a newly cut vertical dropoff before it enters the channel of Dragon Creek (fig. 33). The material from which the dropoff is cut is continuous with the material that forms the adjacent alluvial terraces and not with the material deposited by the flood. If the hanging bed of tributary 2 represents the pre—1966 flood level of the bed of Dragon Creek, then the bed of the creek was lowered 12 ft (3.7 In) during the flood. The waterline that defines an area of ponding at the mouth of tributary 2 is additional evidence that trenching took place during the flood; the waterline is 8 ft (2.4 m) above the bed of the tributary. It seems unlikely that the mudflow in Dragon Creek dammed the tributary and caused the ponding because the rate of flow of tributary 2 was estimated to be insuf— ficient to fill a pond 8 ft (2.4 m) deep and 40 ft (12 m) wide during the extremely short time that it probably took the mudflow to pass the mouth of the tributary (table 2). Therefore, the waterline probably represents the maximum level of Dragon Creek before the mudflow and before much erosion of the dropoff at the mouth of tributary 2 had taken place. 38 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA HINDU AMPHI'I‘HFA'I‘ER Dragon Creek flows in an alluvial-floored channel through nearly all of inner gorge 2 in the northeastern part of the Hindu Amphitheater. Bedrock is exposed in the bed of the creek at the head of the gorge, where the gorge is less than 20 ft (6 m) wide in places. At a spring in inner gorge 2, the mudline is 151/2 ft (4.7 m) above the present streambed. The flood covered and mildly scoured a terrace 7 ft (2.1 m) above the bed ofthe creek; a 3-ft-diameter (0.9-m-diameter) cottonwood growing on the terrace was left standing upright. The height of the mudline above the channel gradu— ally decreases downstream, and, at location R (pl. 1), mudmarks are not present on the walls of the gorge. An alluvial terrace at this location is only 61/2 ft (2.0 m) above the streambed (pl. 1). The terrace is capped by a grayish-brown soil less than 1 ft (0.3 m) thick that contains substantial organic material. Reeds and other swampy type plants growing on the terrace indicate that they were situated at or near the level of the streambed prior to the flood. The plants remained up- right; neither they nor the top of the terrace were in- undated by mud or water. An equally high gravel bar that occupies most of the channel was deposited by the flood along the terrace. A hypothesis as to what may EXPLANATION V Area inundated by mudflow X Data point 58(158) Height of flood—carved bench above streambed, in feet (metres) 51T(15.5TJ Height of terrace above streambed, in feet (metres) 14ML(4.3MLI Maximum height of mudmarks of mudflow above streambed, in feet (metres) 8V2FL(2.6FL) Maximum height of streamflow i. V that occurred after mudflow pulse, in feet (metres) FIGURE 36.—Main part of Hindu Amphitheater showing distribution of mudflow and alluvial terraces along Dragon Creek. have caused the mudflow and streamflow to pass this point without inundating the 61/2-ft-high (2.0-m-high) terrace is that (1) the channel was deepened by pre- mudflow streamflow, (2) the mudflow passed by in the newly deepened channel, and (3) the channel was aggraded to its present (1967) level, including the burying of marks left by the mudflow, by postmudflow streamflow. Downstream from location R, the mudmarks gradu- ally increase in height to 11 ft (3.4 m) above the streambed. Conspicuous mudmarks were seen on the walls of the gorge between location R (pl. 1) and the main part of the Hindu Amphitheater. In this reach, remnants of old barlike features mantled by small cot- tonwoods and other vegetation remain slightly above the mudline. Gravel was deposited at places in the channel and overlapped onto the heads of the barlike features. In the main part of the Hindu Amphitheater mul— tiple-fill terraces are the best developed of any in the Crystal Creek basin (fig. 36). A prehistoric mescal pit (Ariz. B:16:42) along the edge of the mudflow is on a 15-ft—high (4.6-m—high) terrace (figs. 17, 35C, 37). (See section entitled “Relation of Prehistoric and Historic Occupation to Flooding”) The terrace is protected from stream erosion by part of a 19-ft-high (5.8-m-high) ter— race that generally diverts high flows diagonally to the opposite side of the channel (fig. 36). The height of the mudline increases progressively from about 10 ft FIGURE 37.—Crystal Creek in May 1966. Looking upstream along Crystal Creek about 0.5 mi (0.8 km) downstream from its confluence with Dragon Creek. TRIBUTARY GORGES OF GRAND CANYON—- FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS 39 (3.0 m) upstream from the mescal pit to 201/2 ft (6.2 m) in a narrow channel at the downstream end of the reach (figs. 16A, 36). DOWNSTREAM FROM HINDU AMPHITHEATER Dragon Creek enters a narrow canyon downstream from the main part of the Hindu Amphitheater near its confluence with Crystal Creek. The mudfiow and floodwater swept the canyon clear of previously depos— ited debris (fig. 37) and transported it to the mouth of Crystal Creek, where part was added to a boulder fan that extended into the Colorado River prior to the flood (fig. 38). The detritus deposited by the mudflow of 1966 includes boulders as much as 8 ft (2.4 m) in diameter and is the coarsest deposit at the mouth of Crystal Creek. People familiar with the area—R. C. Euler; Wayne Learn, a helicopter pilot; and rivermen (oral commun., 1967)—report that the boulder fan is much larger and extends closer to the opposite bank of the Colorado River than it did before the flood of 1966 and that Crystal Rapids are much rougher and probably higher than they were before the flood. The Colorado River survey topographic map (sheet C) printed in 1924 and the topographic map of the Bright Angel quadrangle completed in 1962 also indicate that the fan of Crystal Creek extends about 200 ft (60 m) farther into the channel of the Colorado River than it did before the flood, narrowing the channel of the river to about 100 ft (30 m). (See pl. 1.) FIGURE 38.—Fan at mouth of Crystal Creek in April 1967. Flow of the Colorado River is from right to left. Light-colored materials were deposited during the flood of December 1966; the fan deposits (Qf) are composed of gravel, including large boulders. Note terrace and dissected alluvial fan (Qr) above the Colorado River. SHINUMO CREEK BASIN As a result of the flood of December 1966, at least seven large mudflows occurred in the northeastern part of the Shinumo Creek drainage basin (pl. 1). The mudflows and several debris slides originated princi- pally from the Hermit Shale at the head of Merlin Abyss, along the main stem of Shinumo Creek, and in Modred Abyss. From aerial reconnaissance, all the mudflows appeared to have been rather fluid except for the one in Kanab Canyon. At least four mudflows moved downstream 1 mi (1.6 km) or more along the canyon floor after debouching from the steep canyon sides. Two of the mudflows in Modred Abyss traveled more than 1.5 mi ( 2.4 km). The mudflows cut conspicu— ous scars along channels on the long steeply forested slopes. Although the stream channels were? swept rather clear of loose boulders, muddy debris was depos- ited along the upper parts of the channel sides and on the adjoining terraces. MUDFLOW AT THE MOUTH OF KANAB CANYON A spectacular mudflow that terminated at Modred Abyss—noted originally by Norman Browning, a heli- copter pilot (oral commun., 1967)——collected as a 1,000-ft-long (300-m-long) mass at the mouth of the stream that drains Kanab Canyon (fig. 39A). From all appearances, this mudflow and the short mudflow in Lava Canyon upstream from its confluence with Natchi Canyon were much more viscous than the other mudflows in the north rim area. Most of the material composing the mudflow probably was picked up en route along the stream channel in Kanab Canyon. The stream channel, except where it cascades over cliffs, was smoothed out. In places the channel was scoured to bedrock and largely cleared of detritus and brush, forming a huge scar on the side of the canyon. One small slide below Galahad Point occurred after the mudflow; the base of the slide is in the channel of Kanab Creek and is almost undissected. The mudflow deposits are an unsorted reddish-brown mixture that ranges from clay to boulders; grain sizes including and smaller than coarse sand make up the bulk of the material. Much of the coarse fraction is limestone. Most of the boulders are less than 3 ft (0.9 m) in diameter, and a few are as much as 5 ft (1.5 m) in diameter (fig. 393, C). Trunks and large branches of conifers are present in the detritus, and a large amount of wood debris accumulated along the top of the mud- flow (fig. 39D). When dry, the muddy debris is ex- tremely hard; the drying was rather uniform, and few shrinkage cracks are apparent. The mudflow material at the mouth of Kanab Can- yon is as much as 15 ft (4.6 m) thick and 75—100 ft 40 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA FIGURE 39,—Explanation 0n facing page TRIBUTARY GORGES OF GRAND CANYON— FLOOD OF DECEMBER 1966 AND PREVIOUS RECENT FLOODS (23—30 m) wide. The snout of the mudflow temporarily ' dammed the stream channel in Modred Abyss (fig. 39E). Mud on boulders and tree trunks indicates that the mudflow in the stream channel was between 8 and 10 ft (2.4 and 3.0 m) thick and that the mudflow ex- tended 15 ft (4.6 m) beyond the channel. Along the stream in Kanab Canyon, poorly formed lobes of the mudflow covered the dense brushy vegetation on the low terraces adjacent to the channel to a depth of 8 ft (2.4 In). The cross-sectional profile of the mudflow was U— to V—shaped (fig. 39F), forming an 8-13—ft—deep (2.4—4.0-m—deep) notch in the central part of the flow; the location of the notch probably coincided with the premudflow channel. Marks left by the streamflow that occurred after the mudflow are displayed only in the bottom 11/2—2 ft (0.5—0.6 m) of the notch. EFFECTS OF STREAM FLOW In general, the effects of the flood of December 1966 are much less prominent along Shinumo Creek than along most other creeks. Along the Shinumo Creek tributary that drains Modred Abyss, the flood cleared the channel of brush and changed the shapes of boul— dery gravel bars. Near the mouth of Kanab Canyon, large scours that now contain pools of water were ex- cavated in the gravelly streambed (fig. 39E). In the wider parts of the stream channel and downstream from bends, root crowns of cottonwoods were buried by 3 ft (0.9 m) of gravel. Because of the abundance of boulders, irregular debris marks are from 3—6 ft (0.9— 1.8 m) above the streambed and cover a 20—60-ft—wide (6—18—m-wide) strip of the canyon floor. Riparian vege- tation protected the sides of the channel from severe FIGURE 39.-—Mudflow at the confluence of Kanab Canyon and Modred Abyss. A, Terminus of mudflow that moved down Kanab Creek (leader 1) and ended along the stream in Modred Abyss (leader 2). Looking downstream and across at terminus of mudflow. Arrows indicate direction of flow. Effects of the streamflow that followed the mudflow are evinced by the clean gravel in the notchlike channel.B , View looking upstream along the mudflow that originated in Kanab Canyon. Photograph taken just left ofA. Photographs/1 andB show almost the entire mudflow deposit. C, Right edge of Viscous mudflow that flowed downstream in Kanab Canyon. Man is standing on mudflow. Photograph taken between the helicopter and the stream in Modred Abyss. D, Wood debris on top of mudflow at mouth of Kanab Canyon. E, Mudflow debris near the mouth of Kanab Can- yon. The light-colored or clear boulders were cleaned by stream- flow that occurred after the mudflow event. The log in the middle foreground was carried by the mudflow. The mudflow is concave upward and forms a notch or channellike feature that was downcut only slightly by the streamflow. Note lateral extent of mudflow (dashed lines). F, View looking downstream along Modred Abyss at confluence with Kanab CanyOn. Mudflow that originated from the left in Kanab Canyon crossed the channel but was subsequently eroded out during the flood. 41 erosion, but, where the streamflow was directed against the bank, lateral cutting removed as much as 5 ft (1.5 m) of sediment. Shinumo Creek near its confluence with White Creek flows on a 200—300-ft—wide (60—90-m-wide) can- yon floor. Minor cutting took place during the flood at site 54 (fig. 40, section A—A ’) and resulted only in root exposure of some of the riparian vegetation (fig. 4). For 0.3 mi (0.5 km) downstream from its junction with White Creek, the channel of Shinumo Creek contains coarse-gravel bars. At section B—B’ (fig. 40), a boulder METRES Break in 5 section FEET 8 ‘fi TWTF METR ES Terrace Shallow flood Channel riot used dUiirig flood J -iD i ' i LAVA of December 1966 0 2D 40 60 BO *mtmf’j—L '5 100 12 140 ‘50,<——ioon FEET Shinumo Creek, 010 mi (0.16 km) upstream from mouth of White Creek [1' MET R ES SOUTH \ . Eveak in section FEET 3 METRES Landslide and talus [Terrace Boulder bar built and Lower iloodirne aftev boulder eroded dumg iiood -10 F i= bar was eroded of Decembev 1965 '5 -zo ‘ L,_l_1_,u__l# . X icon 120 no ieo 130 200 220 240 260 230 300 FEET Shinumo Creek, 0.10 mi (0.16 kmldownstream from mouth of White Creek C C' SOUTH METRES 1 0 20 30 40 50 60 70 Debris, riicmdii’ig iron stove. of liistoiit Bass campsite (Aviz. B 15 49) FEET METRES Floodline 160 Bass campsite near mouth of Shinumo Creek NOTE: See plate l forsection location FIGURE 40.——Secti0ns along Shinumo Creek. 42 EFFECTS OF THE FLOOD OF DECEMBER 1966, GRAND CANYON, ARIZONA bar has an average height of 4 ft (1.2 In) between ter- races that are 10 and 12 ft (3.0 and 3.7 m) high. Wood and other debris left by the flood of 1966 accumulated at two levels—7 ft (2.1 m) and 31/2 ft (1.1 m) above the present streambed. The higher debris level represents the crest of the flood, which was probably concurrent with the maximum buildup of the gravel bar. During the waning stage of the flood, water probably deposited debris at the lower level and trenched the present channel of the creek partly into the gravel bar. After all this aggradation and subsequent cutting, the pres- ent channel has nearly the same depth as that of the preflood channel. Shinumo Creek flows through a narrow canyon— from 50 to 200 ft (15-60 m) wide—downstream from section B—B’to its mouth. In this reach the flood erosion consisted mainly of the lateral cutting of alluvial ter- races. Downcutting was slight because in places Shinumo Creek flows on bedrock. Small gravel bars formed, which are not as large or extensive as the ones near section B—B’. At section C—C’ (fig. 40), the flood- water encroached along the edge of the historic site (Ariz. B215z49) that was occupied by William W. Bass about 1890—1910 (see section entitled “Relation of Pre- historic and Historic Occupation to Flooding”). TAPEATS CREEK The flood of December 1966 was a minor event in the history of Tapeats Creek, but the creek shows effects of older floods. Wood debris from one period of high streamflow was recognized about 5 ft (1.5 m) above the level of the creek. According to R. C. Euler, a much larger flood occurred in the summer of 1961, and it is represented by mud debris and logs left on the 7— 11-ft-high (2.1—3.4-m-high) terrace (fig. 41). Recon- struction of the mudline from remnants of the debris gives a height of 10—11 ft (3.0—3.4 m) above the present bed of the creek. In places the muddy debris formed lobes and lobelike masses that are composed of un— sorted silty sand and some small pebbles. The composi- tion and configuration of the debris indicate that it was deposited during a mudflow. Dead fully grown cheat grass from the previous summer was on the muddy debris when the area was visited in May 1967, which proves that this mudflow antedates the flood of 1966. The 1961(?) mudflow and accompanying streamflow apparently caused some lateral cutting that is not fully healed by vegetation. In places the mudflow moved straight along the canyon floor without regard to the sinuous channel that is incised into the 5-ft-high (1.5-m-high) terrace. The terrace was not badly eroded, although it was submerged 5—6 ft (1.5—1.8 m) by the mudflow. The terrace supports many 1—2-ft-diameter (0.3—0.6-m-diameter) cottonwoods, some of which may have been growing at the time of the mudflow. 59011071 A A. EAST MEFRES WEST o 5 1o 15 20 ‘ l l l 50‘ '7 j 4L, ' 7' TA '7" if" 7' if. 77 L77" 7 if if 7' if i V '77 7' _,7,’7 15 Qafumnmetev “ _h¥ 35"” *‘l j 40L 5 <0 6 m) Cottonwood 4 i f l—m 304 Mudflow daposmed DUO? to me Wes! etrge ol ‘ “ ( / flood of December 1966 mudflow 20 4 r k , w ‘ LU E i l l ‘ ... 4 5 E it i A l . .. m ‘ w 101’ g """ 4 ”””””””””””” i; 3: ;-- / \g a E % i“ l ' Break in g ‘ w . , 5 ‘ V Flood prior [0 that of December 1966 ‘ ‘ quod 01 Decemner 1966 ,n ,71 , . u n. 7,. 7. L_., .+,, U 10 20 30 40 50 60 r77 i 74 “~77” i474 .5 fi—»fi~125 n H FIGURE 41.—Section along Tapeats Creek, looking downstream. SUMMARY The formation of mudflows, extensive channel ero- sion, damaged archeological sites, and high flood peaks indicate that the flood of December 1966 was a rare event in the eastern Grand Canyon area. The storm deluged part of the Kaibab Plateau with as much as 14 in. (360 mm) of rainfall. In general, the storm was con- centrated on the windward southern part ofthe Kaibab Plateau. High flows as a result of the storm caused extensive channel damage in Nankoweap, Kwagunt, Chuar, Clear, Bright Angel, Crystal, and Shinumo Creek basins. The most spectacular event of the storm was the formation of mudflows and debris slides—avalanches. Two of the mudflows in Crystal and Chuar Creek ba— sins were especially fluid and extended from the sides of the Kaibab Plateau to the Colorado River, a distance of more than 7 mi (11.3 km). At least nine other mud- flows moved more than 0.5 mi (0.8 km). Although these are the first mudflows to be documented in the eastern Grand Canyon area, remains of an older mudflow were recognized along Tapeats Creek. More than 80 debris slides occurred in the amphitheaters of the side tribu- tary gorges bordering the Kaibab Plateau, and about 10 occurred on the summit of the plateau. Record flows occurred along Bright Angel Creek, the only creek that is gaged in Grand Canyon. The peak flow of 4,000 ft3/s (about 110 m3/s) was slightly lower than the peak flow in 1936, but the flow volume and duration were much greater. The recurrence interval obtained from regional flood—frequency relations is about 100 years for the peak discharge. The flood discharge along Dragon Creek, a tributary to Crystal Creek, appears to have been of greater mag- nitude than that in Bright Angel Creek. The flood components consisted of streamflow before the mud- flow, the mudflow that composed the crest of the flood, and streamflow after the mudflow. A mescal pit that had been utilized by prehistoric Pueblo Indians about REFERENCES CITED 43 AD. 1100 was destroyed or covered by mud, which indicates that the flood of December 1966 was the largest flood in the last 800 years. The flood of 1966 damaged or destroyed two prehis- toric mescal pits that were constructed by the Anasazi Pueblo Indians between AD. 1050 and 1150—the pre- viously mentioned pit along Dragon Creek and one along Clear Creek. The crest of the mudflow barely wetted part of another mescal pit along Dragon Creek. The Indians probably were well aware of flash floods because their permanent structures were built high on terraces or along cliffs. The flood damage to cultural features was mainly to a pipeline, the cross-canyon Kaibab Trail, buildings, and campgrounds in Bright Angel Canyon and to roads on the Kaibab Trails. Most of the road damage was caused by slides near Bright Angel Creek along the paved highway leading to Point Imperial and by wash- outs along dirt roads in Kanabownits Canyon and in the North and South Canyon drainages. On the Kaibab Plateau, the flood of 1966 affected mainly the grass—covered parks and valleys, which contained few active scours or discontinuous gullies before the flood. The flood enlarged the old scours and gullies and cut many new scours in Bright Angel and Clear Creek basins. Scouring was particularly notice- able where the flow was more than 1 ft (0.3 In) deep. Renewed arroyo trenching occurred along two drain- ages—in the lower part of the Walhalla Glades and in Outlet Canyon. The arroyos were deepened and wid- ened as a result of coalescing of large scours. In the tributary gorges of the eastern Grand Canyon the flood of 1966 affected mainly the channels of Nankoweap, Chuar-Lava, Clear, Bright Angel, and Crystal-Dragon Creeks. The alluvial fans at the mouths of Bright Angel, Crystal, Nankoweap, and Kwagunt Creeks were en- larged by the flood and now extend into the channel of the Colorado River. Debris deposited by the flood at the mouth of Bright Angel Creek changed the stage- discharge relation at the Colorado River near Grand Canyon gaging station; this relation was nearly con- stant for 1922—66. The fan in Crystal Creek was en- larged by about 200 ft (60 m), and the flood deposited large boulders in the channel of the Colorado River, which greatly increased the roughness of Crystal Rapids. $95. GOVERNMENT PRINTING OFFICE: 1976 - 789-025/21 REFERENCES CITED Aldridge, B. N., 1971, Northwestern Arizona, in Summary of floods in the United States during 1966, by J. O. Rostvedt and others: U.S. Geol. Survey Water-Supply Paper 1870—D, p. 63—69. Benson, M. A., 1968, Uniform flood-frequency estimating methods for Federal agencies: Water Resources Research, v. 4, no. 5, p. 891—908. Butler, Elmer, and Mundorff, J. C., 1970, Floods of December 1966 in southwestern Utah: US Geol. Survey Water-Supply Paper 1870—A, 40 p. Cooley, M. E., Harshbarger, J. W., Akers, J. P., and Hardt, W. F., 1969, Regional hydrogeology of the Navajo and Hopi Indian Reservations, Arizona, New Mexico, and Utah, with a section on Vegetation, by O. N. Hicks: U.S. Geol. Survey Prof. Paper 521~A, 61 p. Dean, W. W., 1971, Floods of December 1966 in the Kern-Kaweah area, Kern and Tulare Counties, California: US. Geol. Survey Water—Supply Paper 1870—C, 79 p. Euler, R. C., 1969, The archeology of the Canyon Country, in Fowler, D. D., Euler, R. C., and Fowler, C. S., John Wesley Powell and the anthropology of the Canyon Country: US. Geol. Survey Prof. Paper 670, 30 p. James, G. W., 1911, In and around the Grand Canyon: Boston, Little Brown and Co., 352 p. Johnson, P. W., and Sanderson, R. B., 1968, Spring flow into the Colorado River——Lees Ferry to Lake Mead, Arizona: Arizona State Land Dept. Water-Resources Rept. 34, 26 p. Maxson, J. H., 1966, Geologic map of the Bright Angel quadrangle, Grand Canyon National Park, Arizona: Grand Canyon Nat. His- tory Assoc, scale 1:48,000, text. 1967, Preliminary geologic map of the Grand Canyon and vi- cinity, Arizona—eastern section: Grand Canyon Nat. History Assoc, scale 1:62,500. Metzger, D. G., 1961, Geology in relation to availability of water along the south rim, Grand Canyon National Park, Arizona: US. Geol. Survey Water-Supply Paper 1475—0, p. 105—138. Noble, L. F., 1914, The Shinumo quadrangle, Grand Canyon district, Arizona: US Geol. Survey Bull. 549, 100 p. Patterson, J. L., and Somers, W. P., 1966, Magnitude and frequency of floods in the United States, Part 9, Colorado River basin: U.S. Geol. Survey Water-Supply Paper 1683, 475 p. Springorum, Dirk, 1965, Spatpleistozane Schotterablagerungen im Grand Canyon des Colorado River, Coconino County, Arizona: Wiirzburg [Germany] Univ., unpub. thesis, 78 p. US. Geological Survey, 1968, Water resources data for Arizona, 1967—Part 1. Surface water records: U.S. Geol. Survey dupli- cated report, 237 p. US. Weather Bureau, issued annually, Climatological data, Ari- zona: US. Dept. Commerce. 1967a, Climatological data, Arizona, December 1966: US. Dept. Commerce, v. 70, no. 12, p. 201-220. 1967b, Climatological data, Nevada, December 1966: US. Dept. Commerce, v. 81, no. 12, p. 129—144. UNITED STATES DEPARTMENT OF THE INTERIOR V PROFESSIONAL PAPER 980 GEOLOGICAL SURVEY PLATE 1 3557 iii 111° 45' 3,75 (BIG SPRM/GS) 36°30' 3557 H {JACOB LAKE) ‘00 ‘01 36°30’ ,s/I .6 Wile"? I, «e a ’A . xx" (“Burnt Corral , , Pomr , Std ‘ . ,, 7. 7.717447%; _ K37 fgi'o'rsushoe ‘ 57mm I {csertroir Bufnt Corrfl/v ' " "Pom fl/ / iRoad Helm-v» 3 ' Point Bee Spr ng Point A ' .js I \' "581g Saddle Point Siavfi: .’ Inst (DCrIzMz y Slug "5‘ Dry Par fl Lirkeg 19 . M 00000000 09 ,4 {SHI’JUI‘VI‘O ALT/4;?) POUFJL » 'V .' ~\ 7 Spun» T 1 pi):!“[ Great how ‘ ‘j‘yBig Sheep ; “Corral , . _ 20. Sum m u ' ,il’qffee 'Lttkr/ ‘V Pkc// "e ‘ 1 itt'le Park \ . G" ' ' Lprzng [Mb ,I I / Q 40} zoom". N ;15’ J - 5 J a; 7* [topper/f » ”JD? fl / , .1/(’ r’ 401; N 1' ‘ f AVAJO’ é” ,, 4010 Hotauta \ Sin/On 2'; . ”“Araahmtfie 9 o “Tire w _/ 4009 1900 000 N : T _ \g‘ _ Brigbfjln 35,3 "a; LEE, E1 . b; I . Li- I, 5 Bright Angel K Ranger Station ‘ 4008 is; x , < ~e “ I K. ‘n " "’07 m A L. , i‘ e, , <1 L; 2 ”06 g _ ,1 \ . a ‘ 3 s. \ ‘ :E <1 ‘2 < ° 5‘ ‘/FL 0 .Area °f L ‘ E A ‘9, L3 :5 i. . , ”05 FIgure 19A “ <1: w» ‘ 3 ‘ ,7 , , _ . 7 _ .7 . , , 5‘ _ \ .‘ , , / ; g 3 I / , , _ \ ‘ ‘ . , . _ ’_ , A , x . ‘ h : , , 3935mm” _l_ _L_L Main areas containing archeological sites /=Separates terrace levels ,, ,, ' ' L ‘ 4 I‘ - j ’ I , x . . ~ 3 , , j ' 7, 7 . , , _ ‘_ 1 1 ‘ . __ . N ,f. - ,. _ ,j. ‘ I ‘ ’ _ - fl‘ ’ -' “ > f ‘ g I I . ' i ; ' 5" ' " fl.— > _ ********** ' ' """" APPROXIMATE MEAN , ’\ \ ‘ / . , ' . , , ' , 7 « . ‘ ' r ' ' , - ' t, \ f; ‘ , , ~ , "x ' , ,/ DECLINATION.1976 «. , v . f _ 1;" ’ , p , EM " :2 I i K A 1* B A 13 Yes, I N A T 1 O N A L 46m , - ’ ‘ ‘ * ' ‘ 7 w ' - ' “ 36°OO' 112 15, 110, «35 egg i9; 4Is RAE 1 955.419 620 IGRANDVIEW POINT) 422 A23 ‘24 50’ ‘35 ‘ ‘27 iiflis£~flifiib> “momma?Interior—Geological Survey, Menlo 111045. 3555' ’V Park, CA.~1976—W76l41 Stratigraphy of the consolidated rocks modified from Noble, 1914; SCALE 1562 500 Metzger, 1961; Maxson, 1966—67; and Cooley and Others, 1 y: o 1 2 3 4 5 MILES l969;by M. E. Cooley, 1967 il—l H H H ‘ : Stratigraphy of the surficial deposits modified from Springorum, 1 '5 0 1 2 3 4 5 6 7 KILOMETRES 1965; and Maxson, 1967; by M. E. Cooley, 1967 H H H H H I—-I ‘l—-—l I——I i——I » CONTOUR INTERVAL 80 FEET DOTTED LINES REPRESENT 40-FOOT CONTOURS DATUM IS MEAN SEA LEVEL RECONNAISSANCE GEOLOGY AND LOCATION OF MUDFLOWS, DEBRIS SLIDES, PEAK-FLOW MEASURING SITES, ARCHEOLOGICAL SITES, AND EROSIONAL FEATURES, EASTERN GRAND CANYON AREA, ARIZONA fl»— ;536— 7 DAYS; LlBRJ“ qugl The Rinconada and Related Faults in the Southern Coast Ranges, California, and Their Tectonic Significance —7 GEOLOGICAL SURVEY PROFESSIONAL PAPER 981 U BRAHY umvmsm 0F cafeteria The Rinconada and Related Faults in the Southern Coast Ranges, California, and Their Tectonic Significance By THOMAS W. DIBBLEE, JR. GEOLOGICAL SURVEY PROFESSIONAL PAPER 981 A study of the Rinconada fault and its relation to other nearby major faults and to the tectonics of the southern Coast Ranges UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1976 UNITED STATES DEPARTMENT OF THE INTERIOR THOMAS S. KLEPPE,S:'U1'/rln‘ GEOLOGICAL SURVEY V. E. McKelvey, [)Il‘t‘t’lm' Library of Congress Cataloging in Publication Data Dibblee, Thomas Wilson The Rinconada and related faults in the southern coast ranges, California, and their tectonic significance. (Geological Survey Professional Paper 981) Bibliography: p. 53—55. Supt. of Docs. no: I 19.16z981 1. Faults (Geology)~Ca1ifornia—Coast Range. 1. Title: The Rinconada and related faults in the southern coast ranges, California. . . II. Series: United States Geological Survey Professional Paper 981. QE606.5.U6D5 551.8’7 76—608324 For sale by the Superintendent of Documents, Us. Government Printing Office Washington, DC. 20402 Stock Number 024—001—02908-1 x CONTENTS Page Abstract __________________________________________________ 1 Introduction ______________________________________________ 1 Location of the Rinconada fault ________________________ 1 Purpose and scope ____________________________________ 2 Acknowledgments ______________________________________ 2 Major geologic relations of the Rinconada fault ______________ 2 Nomenclature and definition ____________________________ 2 Regional relations ____________________________________ 6 Concealed position of southwestern border of the Salinian block ________________________________________________ 8 Rock units ________________________________________________ 9 Crystalline rocks ______________________________________ 9 Franciscan rocks ______________________________________ 9 Upper Jurassic(?) and Cretaceous marine sedimentary se- quence ______________________________________________ 12 Upper Cretaceous and lower Tertiary marine sedimentary sequence ____________________________________________ 12 Middle Tertiary sedimentary sequence __________________ 13 Upper Tertiary sedimentary sequence __________________ 16 Valley sediments ______________________________________ 16 Surficial deposits ______________________________________ 19 Segments of the Rinconada fault ____________________________ 19 Rinconada fault (N acimiento segment) from San Rafael Mountains to Pozo area ______________________________ 19 Other faults near and possibly related to the Nacimiento segment of the Rinconada fault ______________________ 20 Rinconada fault (Rinconada segment) from Rinconada mine to Paso Robles ______________________________________ 21 Rinconada fault (San Marcos segment) from Paso Robles to Page Segments of the Rinconada fault—Continued Relationship of Rinconada fault to Jolon and related faults _______________________________________________ 29 Geophysical expression of the Rinconada fault __________ 32 Reliz fault _________________________________________________ 32 King City fault ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32 Reliz fault in Arroyo Seco area ,,,,,,,,,,,,,,,,,,,,,,,,,, 33 Reliz fault at base of Sierra de Salinas ,,,,,,,,,,,,,,,,,, 34 Possible northwestward extension of the Reliz fault ______ 34 Regional evidence of large strike-slip movement on the Rin- conada—Reliz fault zone ______________________________ 36 Movements in Quaternary time ________________________ 36 Movements in Pliocene time ____________________________ 36 Movements since early Miocene time ____________________ 36 Movements in Oligocene(?) time ________________________ 38 Possible movements in pre—Late Cretaceous time ,,,,,,,, 38 Strike-slip movement as suggested by configuration of buried surface of basement complex __________________ 40 Regional tectonics along and near the Rinconada—Reliz fault zone _________________________________________________ 40 Concepts of tectonic evolvement of the Coast Ranges -H- 40 Tectonic pattern ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 42 Tectonic features of the east strip ______________________ 44 Tectonic features of the west strip _______________________ 44 Regional tectonic analysis ______________________________ 46 Regional significance of the Rinconada-Reliz fault zone ,_ 48 Effect of Rinconada-Reliz fault zone on physiography and drain— age ____________________________________________________ 52 Possible seismic activity ______________________________________ 52 San Antonio Reservoir ______________________________ 23 References cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 53 Rinconada fault (Espinosa segment) from San Antonio Res- ervoir to Reliz Canyon ______________________________ 25 ILLUSTRATIONS Page FIGURE 1. Index map showing positions of the Rinconada and Reliz faults relative to the Salinian block and the San Andreas fault __________________________________________________________________________________________________ 2 2. Map showing physiographic features and drainages along and near the Rinconada and Reliz faults ______________ 3 3. Map showing nomenclature of some major faults in part of southern Coast Ranges ______________________________ 5 4. Map showing geologic setting of the Rinconada and Reliz faults ________________________________________________ 7 5. Diagram showing major rock units of the Coastal block within area of figures 1, 2 and 4 ________________________ 10 6. Diagram showing major rock units of the Salinian block within area of figures 1, 2 and 4 ________________________ 11 7—21 Maps showing: 7. Geology along and near the Rinconada fault (Nacimiento segment) from Big Pine Mountain to Timber Peak ____________________________________________________________________________________________ 17 8. Geology along and near the Rinconada fault (Nacimiento segment) from Timber Peak to Pozo ____________ 18 9. Geology along and near the Rinconada fault (Rinconada segment) from the Rinconada mine to Paso Robles __,- 22 10. Geology along and near the Rinconada fault (San Marcos segment) from Paso Robles to San Antonio Reser- voir ______________________________________________________________________________________________ 24 11. Stream-channels deflected possibly by right-lateral movement on the Rinconada fault (San Marcos segment) northwest of Paso Robles __________________________________________________________________________ 26 12. Geology along and near the Rinconada fault (Espinosa segment) between Lockwood and Salinas Valleys __ 27 III IV CONTENTS FIGURES 7—21. Maps showing—Continued 22. 23. 24. 13. Geology along and near the Rinconada fault (Espinosa segment) and Reliz fault, near King City and Greenfield ______________________________________________________________________________________ 14. Stream channels of canyons deflected possibly by right-lateral movement of the Rinconada fault (Espinosa segment) near Lockwood ________________________________________________________________________ 15. Geology of the northern Santa Lucia Mountains, a segment of the Salinian block elevated on the Reliz fault and many other parallel faults __________________________________________________________________ 16. Inferred displacement of lower Pliocene (unit 1, Pancho Rico Formation) and upper Miocene (unit 2, Santa Margarita Formation) by right lateral strike-slip movement on the Rinconada fault", ________________ 17. Pre-Oligocene rocks of the Salinian block, possibly displaced by right-lateral movement of the Rinconada- Reliz fault zone ____-___________-____-__-______--____________,______-__-__,_, ___________________ 18. Inferred configuration of buried surface of crystalline basement complex along Rinconada—Reliz fault zone from Paso Robles to Greenfield __________________________________________________________________ 19. Right-slip tectonics and compressive upheaval along the Espinosa segment of the Rinconada fault ________ 20. Major tectonic features of the southern Coast Range region in vicinity of the Rinconada—Reliz fault zone __ 21. Geology of the upper Nacimiento River area and vicinity ______________________________________________ Block diagram illustrating mechanics of conversion of strike-slip movement along a high angle fault into compressive uplift of one block as fault terminates ____________________________________________________________________ Map showing inferred tectonic movements in vicinity of northern Santa Lucia Mountains showing conversion of right-slip movements near ends of Rinconada-Reliz fault zone and San Gregorio fault into crustal compression and uplift of intervening area to form these mountains ____________________________________________________ Map showing inferred tectonic movements in vicinity of Sierra Madre Mountains and Pine Mountain, showing inferred conversion of right-slip movements near ends of the Rinconada and San Gabriel faults to crustal com- pression to form these ranges ____________________________________________________________________________ Page 28 30 35 37 39 41 42 43 47 48 50 51 THE RINCONADA AND RELATED FAULTS ., IN THE SOUTHERN COAST RANGES, CALIFORNIA, AND THEIR TECTONIC SIGNIFICANCE B‘y THoMAs W. DIBBLEE, jR. ABSTRACT The Rinconada fault near Santa Margarita, as depicted on the Geologic Map of California, is a northwest-trending high—angle fault about 40 km (26 mi) long that in part separates terranes with differ- ent basement complexes. The terrane on the northeast is part of the Salinian block, which is composed of a Mesozoic and older crystalline basement complex of plutonic and metamorphic rocks, overlain un- conformably by a thick Upper Cretaceous and lowar Tertiary marine sedimentary sequence. In contrast, the terrane on the southwest is part of the Coastal block, compased of a basement complex of Fran- ciscan eugeosynclinal rocks overlain depositionally or tectoniCally by a thick Cretaceous marine sedimentary sequence. These blocks are separated by the Sur-Naciniiento fault zone to the northwest. Southeastward frOm Santa Margarita the Rinconada fault extends continuously into a fault formerly thought to be the Nacimiento fault across the Cuyama River gorge to intersect the Big Pine fault in the San Rafael Mountains. Northwestward, the Rinconada fault passes concealed near Paso Robles into high-angle faults, locally called the San Marcos and Espinosa faults, nearly to Reliz’ Canyon West of King City, and is within the Salinian block. All these alined faults are now mapped as parts of a major fault 250 km (160 mi) long; The name Rinconada is applied to the entire fault. It is 3 km (2 mi) from the alined Reliz fault to the northwest along the northeastern base of Sierra de Salinas. The Rinconada fault, as herein defined, is nearly parallel to and is located about 34 km (22 mi) southwest of the San Andreas fault. Southeastward from Santa Margarita the Rinconada fault presuma; bly coincides with the southwestern boundary of the Salinian block, but northwestward from that town it extends into this block. The Coastal and Salinian blocks were juxtaposed along the Sur- Nacimiento fault zone, possibly by subduction, probably in Late Cre- taceous or possibly early Tertiary time. The Rinconada-Reliz fault zone formed largely within the Salinian block in late Cenozoic time, although the southern part of the Rinconada fault followed the former Sur-Nacimiento fault zone. The Rinconada-Reliz fault zone is not presently active. Major movement on the Rinconada fault is interpreted to have been right lateral strike slip. This is suggested by numerous severely compressed drag folds in the sedimentary rocks along and near the fault and the persistent slightly more east-west trend of their axes as compared to the northwest trend of the fault. This movement is also suggested by displaced stratigraphic units; those of late Miocene and early Pliocene ages are about 18 km (11 mi) apart near Paso Robles, and those of Late Cretaceous and early Tertiary age nearly 60 km (40 mi) apart. Movement on the Reliz fault is in part right lateral, as suggested by structural relations similar to those along the Rinconada fault, and in part vertical, having elevated the southwest block to form the Sierra de Salinas uplift. The northern part of the strip within the Salinian block east of the Rinconadwfieliz fault zone reacted to stress during late Cenozoic time as a rigid block of crystalline basement that was tilted slightly southwestwar‘d from an axis adjacent to the San Andreas fault to form the Gabilan uplift and Salinas Valley. The southern part of this east strip, where the basement complex deepens southward under a thick sedimentary cover, was compressed to form the La Panza, Caliente, and Sierra Madre Ranges. In contrast, the strip that includes part of the Salinian and Coastal blocks west of the Rinconada-Reliz fault zone yielded to stress during late Cenozoic time as a series of parallel compressive uplifts and is deformed throughout to form the San Rafael and Santa Lucia Moun- tains and related hills. The northern part of this west strip, despite its rigid crystalline basement, was upheaved by severe compression to form the high northern Santa Lucia Mountains. The crustal shor- tening involved in this part, compared to nearly none on the east strip, presumably has absorbed the large amount of right-lateral movement on the fault zone as it dies out northwestward near Salinas. The Rinconada fault and other geologic features were probably displaced about 14 km (9 mi) by left slip on the east-trending Big Pine fault. The Pine Mountain fault north of Sespe Creek may be the reactivated displaced counterpart of the Rinconada fault south of the Big Pine fault. INTRODUCTION LOCATION OF THE RINCONADA FAULT Mapping of the regional geology of the southern Coast Ranges of California Within 46 km (30 mi) west of the San Andreas fault has revealed the presence of a major high—angle fault, traceable for some 250 km (160 mi) or possibly 290 km (190 mi), nearly parallel to and about 34 km (22 mi) southwest of the San Andreas fault (fig. 1). Various segments of this parallel major fault have been mapped at different times, by different workers, who did not recognize their continuity, and so each segment was designated by a local name. The present investigation reveals that all or most of these segments are parts of a nearly continuous single major fault, designated herein as the Rinconada fault extending from the San Rafael Mountains on the southeast into the hills west of King City. The physio- graphic features of this and associated major faults are shown in figure 2. 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HOW .32: was 3:353 .820 “EN 38032 uD TIC /\_ 052098 “EN 863 Eazonzmgmg :8 ///H $23.5 258330 was 328.; 8.33 7/? mmmFmEOixov om ON ow o mmn___>_om ON OF 0 com 8 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA CONCEALED POSITION OF SOUTHWESTERN BORDER OF THE SALINIAN BLOCK Between the Santa Margarita area, where Francis- can rocks west of the Rinconada fault are very near the granitic basement of the Salinian block on the east side of this fault, and the northern Santa Lucia Mountains about 25 km (15 mi) west of Jolon, where Franciscan rocks are in contact along the Nacimiento fault with the crystalline basement complex of the Salinian block, the position of the boundary between the Sali- nian and Franciscan rocks is not known because it is concealed beneath younger sedimentary rocks for a distance of about 100 km (62 mi). This concealed boun- dary could not be detected by gravity geophysical sur- veys, owing to lack of density contrast between these two basement complexes (Burch, 1971; Hanna, 1970) and its depth below sedimentary rocks. Where the boundary between the Franciscan and crystalline basement is exposed in the northern Santa Lucia Mountains along the Nacimiento fault west of J olon (fig. 21), the fault dips steeply northeast to verti- cal. On the northeastern block I found that the crystal- line basement complex is overlain unconformably by the southward-dipping Upper Cretaceous and lower Tertiary sedimentary sequence. Southeastward this sequence conceals the crystalline basement complex on the Salinian block and is in contact along the fault with Franciscan rocks of the relatively elevated southwestern or Coastal block for 50 km (31 mi). These conditions suggest, if not indicate, that the concealed boundary of the crystalline basement of the Salinian block with Franciscan rocks of the Coastal block is along the entire northern Nacimiento fault, as generally believed. However, Burch and Durham (1970, p. B13), Burch (1971, p. A12), and Durham (1974, p. 59) suggested that this boundary may be cross-faulted far to the east, to their postulated Jolon fault near the San Antonio River, because of gravity gradients in that area and almost none along the Nacimiento fault. This interpretation, although it cannot be ruled out, is considered improbable. From the geologic relations described and as shown in figure 21, it is more probable that this concealed boundary continues southeastward along the length of the Nacimiento fault (fig. 1) from the segment along which it is exposed, or along the fault within 2 km (1.3 mi) northeast, because of the following structural evidence: Franciscan and overlying rocks exposed southwest of these faults in the central Santa Lucia Mountains are severly deformed throughout and ele- vated along these faults against the Upper Cretaceous and lower Tertiary sequence and the middle Tertiary sedimentary sequence of the Nacimiento River area to the northeast, which are much less deformed except adjacent to the fault zone. These conditions suggest that the zone of weakness along which the Santa Lucia Mountains were elevated, including the Nacimiento fault zone, formed presumably along this concealed boundary and that the comparatively less deformed sedimentary sequences to the northeast are probably underlain by the crystalline basement complex that is comparatively more rigid than the Franciscan base- ment and more resistant to deformation. There is no structural discordance either at the sur- face (fig. 21), or in the gravity pattern (Burch, 1971, pl. 1; Hanna, 1970, p. B72), to indicate that the bound- ary of the basement complex with Franciscan rocks is cross—faulted or deviated from its exposed position along the Nacimiento fault eastward to Lockwood Val- ley as suggested by Burch and Durham (1970) and Durham (1974). If it is, it would underlie the Upper Cretaceous and lower Tertiary sedimentary sequence, and if it is a fault contact, it would predate that se- quence. It is difficult to interpret the position of this concealed boundary from the geophysical data. Along the Nacimiento fault, including the segment along which the Franciscan and crystalline rocks are in contact at the surface west of J olon, there is little if any gravity gra- dient, other than the regional one of progressively de— creasing gravity values northeastward as shown by Burch (1971, pl. 1) and Hanna (1970, p. B72—B73). The very slight gradient at the segment along which Francis— can rocks are in contact with the thick Upper Cretaceous and lower Tertiary sedimentary sequence suggests that there is very little density contrast between this se— quence, the Franciscan rocks, and the crystalline rocks. Only where one or all of these three rock units are over- lain by thick middle and late Cenozoic sedimentary rocks of lower density, such as in the Lockwood Valley area, is there a defined gravity gradient. Burch (1971, p. B12), Hanna (1970, p. B74), and Loney (1970) suggested that the concealed Franciscan—crystalline basement bound— ary may be slightly east of the Nacimiento fault or that the contact dips northeastward, but it is probably too deep to be detectable in any geophysical pattern. An airborne magnetometer survey (Hanna, 1970, p. B68—B69) did not definitely detect the position of the concealed Franciscan—crystalline basement boundary, but magnetic variations are locally very strong where Franciscan rocks are exposed, especially over serpen- tine bodies, and are almost nonexistent eastward to the Rinconada fault. This condition suggests that the con- cealed boundary is near the easternmost exposures of Franciscan rocks, although Hanna (1970, p. B74) ROCK UNITS 9 suggested that it may be within 8 km (5 mi) east of these exposures. Beyond the southeast end of the Nacimiento fault (fig. 10), the position of this concealed boundary is a matter of speculation. Presumably it may continue to extend southeastward (fig. 1), possibly under the syn- cline axis north of the Las Tablas fault (fig. 10) to join the Rinconada fault near Atascadero (fig. 9). Southeastward from Santa Margarita the concealed boundary of the crystalline basement of the Salinian block with Franciscan rocks is presumably along the Rinconada fault to and possibly beyond the Big Pine fault (fig. 1), because east of the Rinconada fault the thick Upper Cretaceous and lower Tertiary sedimen- tary sequence is underlain by the crystalline basement in the La Panza Range (figs. 4, 8, 9) and presumably throughout the extent of this sequence, whereas west of this fault the Cretaceous sedimentary sequence is underlain by Franciscan rocks and is comparatively more intensely deformed. ROCK UNITS The rock units of the Salinian and Coastal geologic blocks within the area of figures 1 and 2 are shown in figures 5 and 6. Their areal distribution is shown generalized in figure 4 and in more detail in figures 7, 8, 9, 10, 12, 13, 15, and 21. The basement complexes of the two blocks are totally different. The overlying sedimentary sequences now recognized (Dibblee, 1973) are similar in general but different in detail. CRYSTALLINE ROCKS The crystalline basement complex (Dibblee, 1973) of the Salinian block is composed of granitic plutonic rocks that engulf pendants of metamorphic rocks (Wiebe, 1970a, 1970b; Compton, 1966b; Ross, 1972, 1974, 1976). The granitic rocks range in composition from quartz diorite to quartz monzonite, with grano- diorite predominant. They locally include small bodies of fine-grained or aplitic alaskite granite, and hornblende diorite or gabbro. The more widespread plutonic rocks of the Santa Lucia and La Panza Mountains have been radiome- trically dated (K—Ar method) at about 70 to 80 my. (million years) or Late Cretaceous (Curtis and others, 1958; Evernden and Kistler, 1970). However, it is doubtful that this is the age of emplacement or crystal- lization of the rocks dated, because the overlying unmetamorphosed sedimentary rocks are also Late Cretaceous, from paleontologic evidence. Compton (1966b, p. 287) and Evernden and Kistler (1970, p. 22) suggested that this may be the age of the earliest uplift since emplacement, or some other postemplacement event, and that the plutons were emplaced probably in mid-Cretaceous time. The metamorphic rocks are sedimentary rocks re- gionally metamorphosed under high temperature and pressure. They are older than the plutonic rocks of Mesozoic age that engulf them. Two lithologic units are recognized. The most widespread is micaceous schist to gneiss of great thickness that includes many lenses of marble, hornfels, and feldspathic quartzite. These rocks are intricately intruded by plutonic rocks in most exposures. This metamorphic unit, originally designated the Sur Series by Trask (1926), is extensive in the northern Santa Lucia Mountains from the Big Sur area southeastward (Ross, 1976) and in most expo- sures dips steeply northeastward. It is present also in the Gabilan Mountains as small scattered pendants (Ross, 1972). It is similar to metasedimentary rocks of Paleozoic and early Mesozoic age in the western Mojave Desert and Tehachapi Mountains (Dibblee, 1967). The less widespread metamorphic unit is more homogeneous and is composed almost entirely of mica-plagioclase-quartz schist. It is injected by plu- tonic rocks at its margins but not internally. These metamorphic rocks are exposed in much of the Sierra de Salinas, where they dip regionally southwest, and at the south end of the Gabilan Range (Ross, 1972, 1974) just north of Greenfield. FRANCISCAN ROCKS Franciscan rocks (the Franciscan Complex of Berk- land and others, 1972) form the basement complex of the Coastal block in which these rocks are extensively exposed in the central and southern Santa Lucia and southwestern San Rafael Mountains. This complex is composed of severely deformed slightly metamor- phosed eugeosynclinal rocks characteristic of Francis- can rocks as described by Bailey, Irwin and Jones (1964). In the central Santa Lucia Mountains (Vicinity of Alder Peak and northwestward, fig. 21) the Francis- can is composed of massive to bedded flyschlike hard graywacke sandstone and minor interbedded mica- ceous shale. Elsewhere the Franciscan in most places is composed ofa melange (mixture) of numerous mono- lithic fragments of graywacke, greenstone, varicolored layered chert, jasper, and blue glaucophane schist in a pervasively sheared “matrix” of dark claystone. Small intrusions of ultramafic rocks such as pyroxenite and gabbro are locally present. Lenticular sill-like injec- tions of serpentine or serpentinite are common within and at the top of the Franciscan complex, especially in the melange. 10 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA LITHOLOGY SEQUENCE FORMATION AND AGE THICKNESS - - Alluvium Holocene >_ Sdlimcrliiifi and older 0-150 ft and late I se me alluvium Pleistocene <21 I m WWW l- < 8 ' Pl ' to ne Valley Paso Robles TESS?“ :lrfd ce sediment5* F°rma“°“ 0—1200 ft Pliocene ? _.\._ WW , Marine $32231r Mzgfjjrrita sandstone % m 600—5000 ft Late 3‘ Miocene 2 Lu 0 Marine siliceous 7 E Middle Monterey Shale shale ‘ it Ter‘iarv 600—5000 ft . *- sedimentary Middle E, sequence“ Miocene 1— VO'CaniC Tuff, dacite, and 7 rocks basalt, 0—2000 ft M _ d Early arine san stone - Vaqueros Formation 0—3200 ft Miocene ? Red beds, Terrestrial deposits Oligocene conglomerate 0—600 ft W Sanhdsltone,d Marine deposits Late 5 a e, an 10 0001 ft Cretaceous Cretaceous conglomerate ’ m (and Upper 8 Jurassic?)+ LLI marine 2 sedimentary Early l— sequence Shale and Marine deposits Cretaceous g o sandstone 0—3000 ft (and Late 0 6 Jurassic ?) g u: u.| E Basalt and chart Cretaceous A h. Franciscan Franciscan and ‘5 Complex rocks¢ Graywacke, Late 5 shale, Jurassic U! chert, and E greenstone 2 “ Regional unconformity at base #lnjected by serpentine, mafic rocks +Ages in parentheses apply to only very small part of unit and only local FIGURE 5.—Major rock units of the Coastal block within area of figures 1, 2 and 4. ROCK UNITS 1 1 LITHOLOGY AND SEQUENCE FORMATION THICKNESS AGE Surficial AlIuvium and Holocene ' . _ 0—300 ft and late [I >- dep05it5* older alluwum . LU n: Pleistocene I; < WWW . :> Z ‘ | t n Valley Paso Robles Terrestrial P eisdoce e O sediments* Formation gravel, sand, and an. wh'fl clay 0—3000 ft Pliocene WW’Mflam Morales Terrestrial Formationx gravel, sand, and clay 0—5000 ft ___————«\f\f\fb Pliocene Quatal Terrestrial Upper FormationX glaroggdftsand Tertiary W sedimentary sequence Upper Marine sandstone unitx 0—700 ft . W Pancho Rico Marine Farly Formationx Lower mudstone, Pliocene 2 unitx diatomite, and O sandstone 3 0—2000 ft >_ 2 “E ”0‘ Santa Marine S - Late l— Margarita sandstone Miocene 0: Formation 0-2000 ft E Marine Late, middle siliceous shale and early Monterey 0—7000 ft Miocene Shale Middle Branch Canyon Marine sandstone Tertiary Sandstone 0—3000 ft Middle sedimentary Miocene sequence“t . Basalt Flows and dikes Va eros Marine Early Fortirilation sandstone and Miocene and shale 0—7000 ft late Oligocene Simmler and Berry Tertresttrial Oligocene Formations S ra a WWW 0-3000 ft Upper w E g t . . D O Cre aceous Undifferentiated _ Eocene, O S < 5 and Iower sandstone Marine Paleocene, LLl E 9 N Tertiary shale and, strata and 3: Lu 0 0 marine con l’omerate 25'000 ft Late ii] i- 8 E sedimentary g Cretaceous n: g a 0 sequence* WM 0 < 2 Granite to g p| ' diorite and Cretaceous S utonic abbro, Crystalline rocks gnainly and older(?) g basenlent granodiorite 5 comp ex . Metamorphic Mitigate Misrozmc rocks schist, and gneiss older j * Regional unconformity at has x Unconformity at base along b e asin margins 'l' lntertongued with Monterey Shale ll Only lowest part in few places of this age 4= Includes Caliente Formation, easternmost terrestrial equivalent of all marine units of this sequence FIGURE 6.—Major rock units of the Salinian block within area of figures 1, 2 and 4. 12 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA The age of the Franciscan rocks of the Coastal block is inferred to range from latest Jurassic (Tithonian) to early Late Cretaceous (Turonian) by Bailey, Irwin, and Jones (1964). Near Stanley Mountain (fig. 6) these rocks yielded fossils considered diagnostic of Late Jurassic (Tithonian) age (Easton and Imlay, 1955). Shale samples from Franciscan rocks west of the Nacimiento River yielded spores and dinoflagellates inferred to be Early Cretaceous (W. R. Evitt, in Page, 1970a, p. 674, 687). A predominantly volcanic unit at the top of or above the Franciscan is exposed in two areas: one in the vicin- ity of Stanley Mountain (fig. 6) as mapped by Hall and Corbato (1967) who included it in the Franciscan, and the other north of San Luis Obispo (fig. 9) as mapped by Fairbanks (1904) and Page (1972). In both areas this unnamed unit is composed of basaltic to an- desitic volcanic rocks partly altered to greenstone, as thick as 610 m (2,000 ft), associated intrusive diabase and peridotite partly serpentinized, and an interval up to 92 m (300 ft) thick oflight-gray chert, and locally by a little shale and graywacke at the top. This igneous unit is excluded from the Franciscan by Taliaferro (1943a), Gilbert and Dickinson (1970), and Page (1972). It is now regarded as the ophiolite~ultramafic succession of igneous rocks as recognized by Bailey, Blake, and Jones (1970). The age of this volcanic unit is either latest Jurassic or earliest Cretaceous. In both areas this unit may be in fault contact on top of Fran- ciscan rocks or serpentine and is overlain by the lower unit (shale) of the Cretaceous (and Upper Jurassic?) marine sedimentary sequence. UPPER JURASSICG) AND CRETACEOUS MARINE SEDIMENTARY SEQUENCE In the Coastal block, the Franciscan rocks are over- lain by, or in fault contact (Brown, 1968; Page, 1970a, 1970b) with a thick marine sedimentary sequence of shale, sandstone, and local conglomerate, primarily if not entirely of Cretaceous age. Although Taliaferro (1943a, 1944) recognized within this sequence three major units separated by unconformities, only two units (fig. 6) have been mapped by Page (1970a, 1970b, 1972), who referred to this sequence as the "Great Valley-type Mesozoic rocks,” Hall and Corbato (1967), and by myself (Dibblee, 1971). The lower unit of this sequence is as thick as 1,219 m (4,000 ft) and is predominantly dark-gray shale that contains thin interbeds of dark-brown wacke sand- stone. This unit was called the Toro Formation by Fairbanks (1904) and Page (1972) in the San Luis Obispo quadrangle; "Knoxville shales” and Marmolejo Formation by Taliaferro (1944) in the Santa Lucia Mountains; Jollo Formation by Hall and Corbato (1966) in the Nipomo quadrangle; and Espada Forma- tion (of Dibblee) by Vedder, Gower, Clifton, and Durham (1976) and Vedder and Brown (1968) in the San Rafael Mountains. Near Stanley Mountain (fig. 8), and also west of Santa Margarita (fig. 9), this unit lies depositionally (unconformably?) on the unnamed vol- canic unit at the top of or above Franciscan rocks (Hall and Corbato, 1967; Page, 1972). Near Stanley Moun- tain and elsewhere the lower unit contains fossils con- sidered diagnostic of Early Cretaceous age (Tiliaferro, 1943a; Easton and Imlay, 1955; Hall and Corbato, 1967; Vedder and Brown, 1968, p. 248). Elsewhere it contains fossils of that age and of inferred Late J uras- sic age in a few places. The upper unit of this sequence consists of interbed- ded gray micaceous shale, buff arkosic sandstone, and locally dark-gray cobble conglomerate with clasts of granitic rocks, andesitic porphyry, and quartzite. This unit is as thick as 4,572 m (15,000 ft). Shale predomi— nates in the lower part, and sandstone in the middle and upper parts. It is exposed extensively in the San Rafael and Santa Lucia Mountains southwest of the Rinconada fault. In the Santa Lucia Mountains this unit was named the Atascadero Formation by .Fair- banks (1904). Taliaferro (1943a, 1944) did not adopt this name but divided this unit in ascending order, into the Jack Creek Formation (mostly shale) and Asuncion Group (mostly sandstone), which he thought were separated by an unconformity. In the Nipomo quad- rangle (fig. 8) this unit was named the Carrie Creek Formation by Hall and Corbato (1967). Other workers (Vedder and others, 1967; Vedder and Brown, 1968; Page, 1970a, 1970b) applied no names to this unit. Fos- sils found in this unit are diagnostic of Late Cretaceous age, as reported by all the authors mentioned above. In the San Rafael Mountains (fig. 7) the upper unit (unnamed) has a thick basal conglomerate that lies without discordance on the lower unit (Espada Forma- tion of Dibblee, 1966). Near Stanley Mountain (fig. 8), as mapped by Hall and Corbaté (1967), the upper unit (Carrie Creek Formation) lies unconformably on the lower unit (Jollo Formation). In the Santa Lucia Mountains the upper unit is either unconformable on both the lower unit and Franciscan rocks (Fairbanks, 1904; Taliaferro, 1943a, 1944) or is thrust presumably westward over them (Page, 1970a, 1970b). UPPER CRETACEOUS AND LOWER TERTIARY MARINE SEDIMENTARY SEQUENCE In the Salinian block, the deeply eroded surface of the basement complex on both sides of the Rinconada fault is overlain unconformably by a thick marine clas- tic sedimentary sequence of Late Cretaceous and early Tertiary age, designated as the Upper CretaCeous and ROCK UNITS 13 lower Tertiary marine sedimentary sequence (Dibblee, 1973, p. 9—10; 1974a). Because of the scarcity of fossils, continuous deposition, and lithologic similarity, the position of the Cretaceous-Tertiary boundary within this sequence is questionable. This sequence is com- posed of interbedded light-buff arkosic sandstone, micaceous gray shale, and some cobble conglomerate. The conglomerate is composed of rounded cobbles mostly of hard granitic rocks, porphyritic to aphanitic rhyolite to andesite, and quartzite. This sequence is exposed extensively in the La Panza and Sierra Madre Mountains east of the Rinconada fault, and in the Nacimiento River and San Marcos Creek drainage areas west of this fault, or between this fault and the Nacimiento fault. East of the Rinconada fault this sequence is esti- mated to be about 9,144 m (30,000 ft) thick and con- tains a basal conglomerate as thick as 610 m (2,000 ft), resting on granitic basement in the La Panza Range (Dibblee, 1973, p. 9—10). According to Vedder and Brown (1968) the lowest 1,524 m (5,000 ft) of this se- quence just east of this fault yielded fossils diagnostic of Late Cretaceous age, the overlying strata in the La Panza Range yielded fossils of probable Paleocene age, and in the Sierra Madre Mountains, fossils of Eocene age. Taliaferro (1943a, 1944) included exposures of this sequence in the La Panza Range in his Upper Creta- ceous Asuncion Formation. Chipping (1972, p. 485, 492) informally called the whole sequence the Sierra~ Madre sequence. In the Nacimiento River—San Marcos Creek area west of the Rinconada fault this sequence is at least 2,454 m (8,000 ft) thick and also has a basal conglom— erate locally, in places more than 305 m (1,000 ft) thick, on the crystalline rocks in exposures north of the Nacimiento River. Fossils found at a few localities in this sequence are diagnostic of Late Cretaceous age, and at other places of Paleocene age (Taliaferro, 1943a; Durham, 1965a). Taliaferro (1943a, 1944, p. 512—517) mapped the inferred Late Cretaceous part of this se- quence as the Asuncion Formation and the inferred Paleocene part as the Dip Creek Formation. However, the position of the Cretaceous-Tertiary boundary within this continuously deposited sequence has not been ascertained, because of the scarcity of fossils, structural complications, and partial cover by younger rock units. The similarity of this sequence in lithology, strati— graphic relations, and age in the La Panza Range area east of the Rinconada fault and in the Nacimiento River—San Marcos Creek area west of the fault suggests that these two widely separated areas of these rocks on opposite sides of the fault may have been dis- placed by large right-slip movement on the fault. This is discussed in more detail under "Regional Evidence of Large Strike-Slip Movement on the Rinconada-Reliz Fault Zone.” I In the northern Santa Lucia Mountains the crystal- line basement complex is overlain unconformably by remnants of this seuqence at a number of places. In the mountains north of the upper Nacimiento River area the largest remnant contains about 1,829 m (6,000 ft) of predominantly sandstone, with sparse fossils of Late Cretaceous age in the lower part and of Paleocene and Eocene age in the upper part (Compton, 1966a, 1966b). Other remnants occur farther northwest adjacent to the Sur and Palo Colorado faults (fig. 15) and are thought to be of Late Cretaceous age (Trask, 1926; Reiche, 1937). Northward in these mountains small remnants (fig. 15) that contain less than 610 m (2,000 ft) of sandstone and shale strata include those of Eocene age in the vicinity of J unipero Serra Peak (Thorup, 1943; Compton, 1966a, 1966b), the southwest side of the Church Creek and Miller Creek faults (Dick- inson, 1959), and small ones of Paleocene age near Carmel (Bowen, 1965; Clark and others, 1974). These remnants suggest a gradual northward thinning of the whole sequence probably by wedging out of the lower strata against the basement complex. MIDDLE TERTIARY SEDIMENTARY SEQUENCE Throughout both the Salinian and Coastal blocks, the pre-Oligocene rock units are overlain unconform- ably by the middle Tertiary sedimentary sequence (figs. 5, 6) (Dibblee, 1973). The unconformity at the base of this sequence is of regional extent and indicates that almost the entire region within the area of figures 2 and 4 northward from the Santa Ynez Mountains was affected by a great orogenic episode of uplift and erosion probably during Oligocene time. In the Saliw nian block, the middle Tertiary sequence rests with great angular discordance upon the beveled surface of the Upper Cretaceous and lower Tertiary marine sedimentary sequence, overlapping it northward onto the crystalline basement complex. On the Coastal block the middle Tertiary sequence rests on the eroded surface of the » Upper Jurassic(?) and Cretaceous marine sedimentary sequence and Franciscan rocks, both of which had been severely deformed previously. The lower or basal unit‘of the middle Tertiary sedi- mentary sequence is composed of terrestrial deposits, mostly red to gray sandstone and conglomerate, of in- ferred Oligocene age. In the Coastal block it is only locally present, mostly southward from Santa Mar— garita, and is not more than a few tens of metres thick. In the Salinian block east of the Rinconada fault the basal terrestrial unit is widespread. It crops out in the Caliente Range and underlies the Carrizo Plain, where 14 it is called the Simmler Formation (Hill and others, 1958; Dibblee, 1973), which is as thick as 1,067 m (3,500 ft) and is composed primarily of bedded reddish-gray sandstone. In the La Panza and Sierra Madre Mountains this unit, also called the Simmler Formation, is composed of coarse conglomerate and sandstone derived from the underlying older rocks and is only locally present but is as thick as 914 m (3,000 ft) at the Cuyama River gorge (fig. 8). Northwestward from these. areas this unit thins to only a few tens of kilometres of red beds under the Salinas Valley and eventually thins out northward, as indicated from well data. In the part of the Salinian block west of the Rin- conada fault the basal terrestrial unit is absent in outcrop except in the Santa Lucia Mountains west of King City, where it was called the Berry Conglomerate by Thorup (1943), and later the Berry Formation by Durham (1974). It is as thick as 335 m (1,100 ft) and is composed of buff-gray to locally red arkosic sandstone and conglomerate. Small isolated exposures of basal red beds that are either equivalent to or younger than the Berry Formation occur near the Nacimiento River, northwest of the reservoir, and in the northern Santa Lucia Mountains west of Greenfield and south of Carmel. The presence of the basal terrestrial unit farther north on the west side of the Rinconada-Reliz fault zone than on the east side is somewhat suggestive of right-lateral displacement on this fault zone. The basal terrestrial unit is overlain by a marine unit of probable late Oligocene to middle Miocene age. It is generally called the Vaqueros Sandstone or For- mation where its age is within the Zemorrian and Saucesian Stages, of late Oligocene and early Miocene age. Where the basal terrestrial unit is absent, this marine predominantly sandstone unit forms the basal unit of the middle Tertiary sedimentary sequence and rests unconformably on the pre-Tertiary rocks. On the Coastal block the basal marine sandstone unit attains a maximum thickness of about 610 m (2,000 ft) in a large syncline in the San Rafael Moun- tains (fig. 7), where it includes some claystone and ranges in age from the Zemorrian to Relizian Stages, late Oligocene to middle Miocene (Vedder and Brown, 1968). Northward this unit thins to a few tens of metres of sandstone in the Huasna Creek area and southern Santa Lucia Mountains. On the Salinian block east of the Rinconada fault the lowest marine unit attains its maximum thickness of about 2,134 m (7,000 ft) in the Caliente Range and Carrizo Plain, where it is called the Vaqueros Forma- tion. It is divided into three members and contains faunas diagnostic of the Zemorrian and Saucesian RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA Stages (Vedder, 1970; Dibblee, 1973). In the La Panza Range this unit is about 518 m (1,700 ft) thick, is nearly all sandstone on the northeast flank, and is lo- cally absent on the southwest flank. Northwestward under the Salinas Valley this sandstone thins to only a few tens of metres, and together with the basal terres- trial unit abuts northeastward against the basement complex along an imaginary line that extends east- southeast and northwest from Bradley (fig. 2). In the Salinian block west of the Rinconada—Reliz fault zone the basal marine sandstone unit is present nearly throughout, although its agermay vary. South- ward from Arroyo Seco Creek to Lockwood Valley it contains fossils diagnostic of the Zemorrian and Saucesian Stages and is generally called the Vaqueros Formation (Thorup, 1943; Bramlette and Daviess, 1944; Compton, 1966a; Dibblee, 1973; Durham, 1974). From Arroyo Seco Creek to the Nacimiento River it is from 310 (1,000) to 671 m (2,200 ft) thick. Southward from Lockwood Valley to Paso Robles this sandstone is thin in outcrop, generally less than 100 m (300 ft). However, west of the San Antonio Reservoir it is as thick as 800 m (2,400 ft) and contains lenses of granitic boulder conglomerate in the upper part (figs. 10, 21). . In the Santa Lucia Mountains northwest of Arroyo Seco Creek to Monterey the basal marine sandstone unit of the middle Tertiary sedimentary sequence may be younger than the Vaqueros Sandstone to the south- east, but its stratigraphic position above red beds, where present, and below the Monterey Shale is similar. The middle Tertiary sequence is the only one besides the Franciscan that contains volcanic rocks in this re- gion. The oldest are the dacitic and rhyolitic plugs and dikes in the San Luis Obispo area in the Coastal block and the rhyolitic plugs, dikes, and tuff-breccia (Pinna- cles Formation of Andrews, 1936, p. 9—22; Wilson, 1943, p. 217—218) of the Pinnacles area of the Gabilan Range in the Salinian block. Those in the San Luis Obispo area yielded K—Ar radiometric dates between 24 and 26.9 m.y. or Oligocene (Turner and others, 1970b). Those in the Pinnacles area yielded K—Ar dates of about 22 m.y. (Turner and others, 1970a). On the Coastal block rhyolitic tuff-breccia (Obispo Tuff of Bramlette, 1946, p. 22—23; Obispo Formation of Hall and Corbato, 1967, p. 569—570), together with flows of dacitic felsite, basalt, and sills of diabase, is extensive just below the Monterey Shale in the San Luis Obispo—Huasna area and is assigned to the upper Saucesian and Relizian Stages, Miocene by the above authors. The Obispo Formation yielded K—Ar radio- metric dates of about 16.5 m.y. or early Relizian (Turner and others, 1970b). On the Salinian block the middle Tertiary sedimen- ROCK UNITS 15 tary sequence contains volcanic rocks in several other areas. East of the Rinconada fault these are flows, sills, and dikes of basalt, mostly in the Miocene part of this sequence, in the Caliente and eastern La Panza Ranges (Dibblee, 1973). West of the Rinconada fault these include flows of basalt near the base of the Mon- terey Shale a few kilometres west of Paso Robles and flows of basalt and andesite near the top of the basal marine sandstone unit in and near the Carmel Valley in the northern Santa Lucia Mountains. The Monterey Shale, an unusual marine formation of siliceous and organic shale primarily of middle and late Miocene age, overlies the Vaqueros or basal sandstone unit where present and makes up the major part of the middle Tertiary sedimentary sequence. This distinctive shale formation is present on and once cov- ered nearly the entire Coastal block and most of the Salinian block. On both blocks this formation varies greatly in thickness, indicating that the sea floor upon which it accumulated was undergoing movements. On the Coastal block the Monterey Shale attains a maximum thickness of about 1,524 m (5,000 ft) in the San Rafael Mountains and Huasna area, but elsewhere to the northwest it is much tinner. On the Salinian block the Monterey Shale is very thin or locally absent in western Cuyama Valley and southwestern La Panza Range but is very extensive under and west of Salinas Valley (fig. 2), where it is about 914 m (3,000 ft) in average thickness. Eastward under the southern part of this valley it extends nearly to the San Andreas fault, thinning eastwardfiln the central part from Bradley to Greenfield (fig. 2) it abuts northeastward through strandline sandstones against the basement complex along the King City hinge line described by Gribi (1963). Under this valley north- westward from Greenfield, the Monterey Shale pre— sumably intertongues with arkosic sandstone and ter- restrial deposits that likewise abut northeastward against the basement complex, as suggested from logs of several wells and from exposures in the hills south- west of Salinas. The thickness of the Monterey Shale within the Salinian block varies greatly along both sides of the Rinconada-Reliz fault zone, as indicated from outcrop and well data. On the east side of the Rinconada fault near Bradley, this shale is as much as, if not more than, 2,134 m (7,000 ft) thick but is much thinner west of this fault. On the west side of the Reliz fault in the Arroyo Seco Creek area the Monterey Shale is about 1,829 m (6,000 ft) thick but is much thinner east of this fault. This condition suggests possible displacement of the very thick section, if once continuous, by right slip on the Rinconada-Reliz fault zone. From the Arroyo Seco Creek area the Monterey Shale extends northwestward as remnants in the northern Santa Lucia Mountains into the Monterey Bay. In most areas on both blocks the Monterey Shale is composed of two distinct parts, the lower part, of argil- laceous to siliceous shale, and the upper part, of hard siliceous shale. The lower part (Sandholdt Shale of Bramlette and Daviess, 1944; Sandholdt Member of Durham, 1974; Point Sal Formation of Hall and Corbato, 1967) of the Monterey Shale is generally about 610 m (2,000 ft) thick or less and is locally absent. In some areas of the Salinian block the lowest 185 m (600 ft) is claystone (Sandholdt Formation of Thorup, 1943) that contains a microfauna of the upper Saucesian and Relizian Stages. The remainder is composed of thin-bedded fis- sile organic shale, siliceous shale, and thin carbonate strata and contains a rich microfauna of the Relizian and Luisian Stages, middle Miocene. This part (Saltos and Whiterock Bluff Shale Members of Hill and others, 1958) makes up all the Monterey Shale in the Cuyama Valley and the Caliente and La Panza Ranges east of the Rinconada fault, and the major part west of this fault from Atascadero northwestward to the San An- tonio River (fig. 2), suggesting possible right-laternal displacement of this unit of the fault. The upper part (Hames Member of Durham, 1974) of the Monterey Shale is composed of white-weathering hard platy brittle porcelaneous siliceous shale. It aver- ages about 610 m (2,000 ft) in thickness but in some areas is as thick as 2,029 m (6,000 ft). It contains a microfauna of the Mohnian Stage, late Miocene. East of the Rinconada-Reliz fault zone this part makes up the major part of the Monterey Shale in areas north- westward from the Paso Robles area and in areas northwestward from Lockwood Valley west of this fault zone. Accordingly, the areas in which the thick- ness of the upper part far exceeds that of the lower part extend farther south on the east side of the Rinconada fault zone than on the west side, suggesting displace- ment by right slip on the fault. The upper part of the Monterey Shale presumably grades laterally southeastward and eastward into the Santa Margarita Sandstone in the southern part of the Salinas Valley, on both sides of the Rinconada fault. Farther southeast in the Cuyama Valley, Caliente Range, and Carrizo Plain, the lower part of the Mon- terey Shale intertongues laterally eastward into the Branch Canyon Sandstone. In those areas that sand- stone, together with the overlying Santa Margarita and much of the underlying Vaqueros Formation, intertongue eastward with red beds of the terrestrial Caliente Formation (Hill and others, 1958; Vedder, 1970; Dibblee, 1973) toward the San Andreas fault. 16 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA The Santa Margarita Sandstone overlies the Mon- terey Shale in the southeastern parts of both the Coastal and Salinian block and is composed of white sandstone from 310 (1,000 ft) to 457 m (1,500 ft) in thickness. It contains bioclastic reefs of fossils diagnos- tic of late Miocene age. East of the Rinconada fault it extends from the Cuyama Valley to the Paso Robles area (fig. 2). West of this fault this sandstone extends about 18 km (11 mi) farther northwest to the San An- tonio River, suggesting right-lateral displacement of this sandstone on the fault (fig. 18). The Santa Mar- garita Sandstone is not definitely known to occur farther northwest except in exposures east of Monterey (Bown, 1965) and possibly in the San Ardo oil field. UPPER TERTIARY SEDIMENTARY SEQUENCE With the exception of exposures south of San Luis Obispo and in Santa Barbara County, the upper Ter- tiary sedimentary sequence is present only on the Salinian block. In the Salinas Valley this sequence is marine, as thick as 610 m (2,000 ft). Its stratigraphy has been interpreted in various ways and is much con- fused as reviewed by Durham and Addicott (1965, p. A3—A6) because of lack of adequate geologic map- ping. On the east side of the Salinas Valley this se- quence was casually called the Poncho Rico Formation by Reed (1925, p. 591, 606), and Clark (1929), with no reference to a type section. Later Durham and Addicott (1965, p. A2) formally defined this entire marine se- quence as the Pancho Rico Formation and considered the fauna throughout as early Pliocene. However, many other investigators and I recognized two distinc- tive lithologic units: a lower mudstone unit and an upper sandstone unit, as indicated below and in figure 5. The lower unit (Santa Margarita or McLure Shale of Taliaferro, 1943a, 1943b; McLure Formation of Kil- kenny, 1948, p. 2260; Pancho Rico Formation of Bald- win, 1950; Pancho Rico Shale of Gribi, 1963, p. 18; Pancho Rico Formation of Dibblee, 1971), is a creamy-white fine-grained chalky diatomaceous mud- stone about 363 m (1,200 ft) thick. It is widespread northeast of the Salinas River where it is primarily diatomaceous mudstone that rests with a basal sand- stone on the basement complex over much of this area. Elsewhere it is conformable, and commonly grada- tional, on the Monterey Shale. Northwest of Jolon the lower unit is diatomaceous to sandy siltstone. Near and southeast of Jolon, and west and southwest of Bradley, this unit becomes impure chalky diatomite. This diatomite was included in the Monterey F orma- tion by Durham (1965a, 1974) as the Buttle Member, but its lithology and stratigraphic position indicate that it is probably the lower unit of Pancho Rico Formation. The upper unit (Etchegoin of Taliaferro, 1943b; Jacalitos of Taliaferro, 1943a; Pancho Rico Formation of Kilkenny, 1948, p. 2260; Etchegoin Formation of Gribi, 1963, p. 18; unnamed sandstone of Dibblee, 1971) is composed of yellowish-gray fossiliferous sand- stone and is included in the Pancho Rico Formation by Durham and Addicott (1965). It is thickest (about 185 m (600 ft) in Salinas Valley in the vicinity of San Ardo, where it is gradational through interbeds into both the underlying lower unit (of the Pancho Rico Formation) and into the overlying Paso Robles Forma- tion. However, beyond this area, stratigraphic rela— tions change rapidly toward the margins of Salinas Valley. Northward this sandstone unit thins to only a calcareous fossil reef that together with the Paso Ro- bles Formation, laps over the lower unit onto granitic basement north of King City. Eastward this sandstone grades laterally into terrestrial gravel like that of the Paso Robles Formation and unconformably overlaps the lower unit onto the middle Tertiary sedimentary sequence near the San Andreas fault. Southwestward to and beyond the San Antonio River, this sandstone thins to less than 61 m (200 ft) and, together with the Paso Robles Formation, unconformably overlaps dia- tomite of the lower unit onto the Monterey Shale (fig. 10). This unconformable relation was recognized by Taliaferro (1943b, p. 460), but not by Durham and Ad- dicott (1965). I mapped and designated the upper unit as an un- named sandstone (Dibblee, 1971) and excluded it from the Pancho Rico Formation, despite the lower Pliocene fossils it contains, because of the stratigraphic reasons indicated above, and as pointed out by Gribi (1963, p. 16), "it certainly is a recognizable formation.” How- ever, because this unit is included in the Pancho Rico Formation by Durham and Addicott (1965, p. A—2) it is herein reluctantly included within that Formation. In the Carrizo Plain, Caliente Range, and Cuyama Valley, the upper Tertiary sedimentary sequence is all terrestrial (Dibblee, 1973). It is as thick as 1,676 m (5,500 ft) and is composed of two units. A lower unit, the Quatal Formation, of Pliocene age, is about 152 m (500 it) thick and is mostly claystone, and an upper unit, the Morales Formation, of Pliocene age, is as thick as 1,524 m (5,000 ft) and is interbedded alluvial conglomerate, sandstone, and clay. This sequence rests unconformably on the Santa Margarita Sandstone or on older formations and is overlain unconformably by the Paso Robles Formation. VALLEY SEDIMENTS Through the Salinas Valley the upper Tertiary sedimentary sequence is overlain by a widespread se- verely dissected valley formation as thick as 310 m (2,000 ft) known as the Paso Robles Formation (Fair- 7 1 ROCK UNITS .Evm d £me ,Esogm «Em EEE> 89¢ woaflvcav xwmm “mafia. 8 53552 wEm mwm 89¢ quzbmmm Bammcfiomz. :53 mwmcoofim 2: Em: min Mao? zmflomwls 559m .Omom: .mv om: oONF mmewEOJU. w o v N O mmJZE m _ oazcomuom §§ m 22: .l I m $88320 5564 IE1. W. 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QDOOOODO a $830M o ,4 nfiEflvoo _// o < souanbes Awwauxypas [(121119 J. alppm % k E ZOHH:U< “.m..u‘.mqomm Evidence of the direction of r lative vertical slip or movement on the San Marcos segment of the Rin- conada fault is conflicting. Bet een Paso Robles and San. Marcos Creek, as shown 'n figure 10, granitic basement exposed on the nort east side against the middle Tertiary sedimentary s quence on the south- west side indicates relative u lift of the northeast block. However, the southwest b ock is topographically higher. Northwest of San M rcos Creek, Miocene strata of the southwest block a in fault contact with the Paso Robles Formation o the topographically lower northeast block. These onditions indicate, if movements were vertical, that the earliest displace- ment since Miocene time was 11 on the northeast, then in late Pleistocene time, up on he southwest. These suggested reversals 0 vertical displacement may be more apparent than rea . Physiographic, struc- tural, and stratigraphic evide ces suggest that the dominant movement was strik slip, right lateral, as indicated in the following para raphs. Physiographic evidence of ri ht-lateral movement, mainly on the northeast stran , is suggested by the southeastward deflection or p rtial deflection of the San Antonio and Nacimiento Rivers, San Marcos Creek, and several small inter ening channels, where they cross the fault (fig. 11). Structural evidence of righ -1ateral movement is suggested by the axial trends 0 numerous folds along and near the faults as shown i figure 10. A few axes are almost parallel to the f ults, but most trend slightly more west than do the faults. Adjacent to the faults, these folds are nume ous and tightly com- pressed, especially in the Monterey Shale. These condi- tions appear to be the effect of right-lateral drag movement along this fault seg ent, combined with se- vere compression. A large amount of right-late al displacement on the Rinconada fault is suggested b the presence west of the San Marcos segment of the hick Upper Cretaceous and lower Tertiary marine sed'mentary sequence and absence of this sequence east 0 this segment. Several wells drilled for oil east of it e ter granitic basement below the middle Tertiary se imentary sequence. A well drilled west of it, on a larg anticline in the Upper Cretaceous and lower Tertiar marine sedimentary sequence about 3 km (2 i) southeast of the Nacimiento Reservoir (fig. 10) bottomed in that se— quence at a depth of 1,585 (5,200 ft). This thick sandy sequence may have been displaced from that se- quence east of the Rinconada egment (fig. 9), either before or after deposition 0 the middle Tertiary sedimentary sequence, or in bo h times. Post-Miocene lateral displacement is suggested by different stratigraphic relations on opposite sides of SEGMENTS OF THE RINCONADA FAULT 25 this fault segment, especially on the northeast strand. On the northeast side of that strand, a great thickness of the upper part of the Monterey Shale (upper Miocene) is overlain by diatomite of the Pancho Rico Formation, and both these units are overlain uncon— formably together by the thin marine sandstone of the Pancho Rico Formation (Pliocene) and by the Paso Ro- bles Formation. On the southwest side, the lower part of the Monterey Shale (middle Miocene) is overlain by a thin unit of the upper part (upper Miocene), which in turn is overlain by the Santa Margarita Sandstone, and all these units are overlain unconformably by the Paso Robles Formation which is generally much less deformed than the Miocene units. These adjacent blocks must have been juxtaposed by right slip from areas once separated. This evidence is further dis- cussed under “Regional Evidence of Large Strike-Slip Movement on the Rinconada-Reliz Fault Zone.” RINCONADA FAULT (ESPINOSA SEGMENT) FROM SAN ANTONIO RESERVOIR TO RELIZ CANYON The San Marcos segment was extended northwest- ward from San Antonio Creek by Kilkenny (1948). Re- connaissance mapping by the author in the hills on the west side of the Salinas Valley in search of petroleum revealed the presence of a major fault zone alined be- tween the San Marcos and Reliz faults. This was shown by Hill and Dibblee (1953, pl. 1; p. 454—455) as the Reliz Canyon—San Marcos fault, branching southward from the supposed King City fault and interpreted to be among “many important northwest-trending steep faults—parallel to the San Andreas—probably also characterized by right-lateral components of displace- ment.” On the geologic map of California the northern part (north of San Antonio Reservoir) 0f the San Marcos fault shown by Hill and Dibblee (1953, pl. 1) is shown as the Espinosa fault (fig. 3A) by Jennings and Strand (1958) and Jennings (1959). On a geologic map (scale 1:125,000) of this area com- piled by Walrond and Gribi (1963) as well as on a sub- surface map by Gribi (1963, p. 26) major northwest- trending faults designated as the Reliz, Espinosa, San Marcos, San Antonio and Jolon faults are shown. The first three mentioned are alined and coincide with the Reliz Canyon—San Marcos fault zone recognized inde- pendently by Hill and Dibblee (1953) and are alined with the Rinconada fault to the southeast. Gribi (1963, p. 23) stated that "the Reliz and Espinosa faults are nearly continuous” and “all folds abutting this fault demonstrate drag indicating marked right lateral movement.” The most extensive large-scale mapping to date of the geology of the hills from San Marcos Creek to Ar- 26 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA 1 20° o 1 2 3 4 MILES l—l—‘L‘l—FLfi—LI"—Fl o 2 4 6 KILOMETRES FIGURE 11.—Stream channels deflected possibly by right—lateral movement on the Rinconada fault (San Marcos segment) northwest of Paso Robles. See Bradley and Adelaida, U.S.G.S. 71/2-minute quadrangles for topography. royo Seco Canyon was by Durham (1963, 1966, 1968a, 1968b, 1970). He inferred faults along or near much of the Espinosa, San Antonio, and San Marcos faults mapped independently by Walrond and Gribi (1963), but he applied only the names San Marcos, San An- tonio, and Jolon to parts of these. He also inferred numerous other vertical faults, forming a random pat- tern of intersecting dashed lines through these hills. On the basis of field checking and additional map- ping of the geology of these hills, I conclude that the Espinosa fault shown on the maps mentioned above is continuous with the Rinconada fault (San Marcos seg- ment) to the southeast and thereby designate the Es- pinosa fault as the Espinosa segment of the Rinconada fault. The geology of the Espinosa segment of the Rin- conada fault is shown in figures 12 and 13. An arbi- trary division between the Espinosa segment and the San Marcos segment to the southeast is designated at a point where a minor fault splays off northward east of San Antonio Reservoir (fig. 10). From that point the Espinosa segment extends northwest for 40 km (25 mi), then dies out at the surface in Monroe Canyon about 12 km (7 mi) west of King City. The Espinosa segment of the Rinconada fault tran- sects the length of the unnamed range of hills, some- times called San Antonio Hills (Reed, 1933, p. 44; Kilkenny, 1948, p. 2261), between the Salinas and Lockwood Valleys (figs. 10, 12, 13). Along and north- west of San Antonio Reservoir (fig. 10) the southwest strand of the San Marcos segment becomes the San Antonio fault, a northeast-dipping reverse or thrust 27 SEGMENTS OF THE RINCONADA FAULT .mhwEwS mmczmw can woogxuoq :83qu Sawawmm «moaammv flag mvmcoofim 2E 5mm: “EN 98? mwfiomw‘.mfi HEDGE mmmFm—EOJEV m N p o lJEJLIL 84:2 m N _ o AHVILHHI ‘EDIJ AHVILHELL AXVNHEILVHD | I £08 cum—“EU uwa ocooom mo ocoamvcam noznfiuom >58”.— oqouufiwm 8.83:3 22m >28=o2 sonagom 8mm enema socaefiom 330% Sam 5.532 ZOHH.o . 0 H 0 5532’ 0 >. E'O o o 2 g t: '5 = S gum M a Z .9 3 O Eta o ‘5 O 1?: N 08 ° 2 E F E E “385 2 :3 < S O a) H 3: g m o 2 w L“ <1 262“ w a o E o .: 5 i5 .2 w ‘“ 85 “’ a“ 3 9" E '0 91 >‘ 8 11'3“: 2 a.) N X 5 ° 0 E o = “S? o E .2 m m ‘5 m a v u 0‘5 o *5 8 fix 0 "’ “3 "‘ 0 u o o >a 3 o s: 'U> o H o ,_. o a :1 Q g o gvl-LU ELY-1 3 H 6 < m 9.. E m m 9.. w v . .. ' r: .' o ‘ \l” "" O .- ’/\/ M / 3 °a° [3‘ I)". D O \ ‘ orJ _\ fi. '2 8 S m «9/ 5 L” 01: 93. m m 1/ a hi 2 / 2 9 / L“ Q ,\ v <9 m ‘0 co V q o 59/ g, N m NVQY/ IE. / / V: \ \ Q . ‘ "’ ’//\— I \_ ‘— N E ~'/I\/’.\‘/':/\‘/l\'>\’4)/\\ \ / /_ /\\; \\ \ 5 a s Point Sur 6 KILOMETRES fl a segment of the Salinian block elevated on the Reliz fault and many other parallel faults. FIGURE 15.—Geology of the northern Santa Lucia Mountains, 35 36°37'30" 36 36°22'30" — 36 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA 22), but none in the bay area underlain by Pliocene and Pleistocene sediments through which the Reliz (or King City) fault has been projected. REGIONAL EVIDENCE OF LARGE STRIKE-SLIP MOVEMENT ON THE RINCONADA-RELIZ FAULT ZONE From the data recorded I concluded that movement on the Rinconada fault was predominantly strike slip by which the terrane to the southwest has moved northwestward relative to that on the northeast, with local or apparent relative vertical displacements, and that movement on the Reliz fault was probably oblique slip with the southwestern block elevated and dis- placed northwestward relative to the northeast block. Right-slip movement is strongly suggested by the se- vere deformation of the sedimentary rocks into folds with axes that persistently trend slightly more east- west than the faults along nearly the entire course of the Rinconada fault and the part of the Reliz fault that transects those rocks. MOVEMENTS IN QUATERNARY TIME There are no indications that the Rinconada and Reliz faults are active presently or were during Holo- cene time. Evidence of the inferred Holocene move- ment on the Rinconada fault north of Santa Margarita is slight and inconclusive. Deflection of canyons, possi- bly by right-lateral movement on the San Marcos and Espinosa segmentsof this fault, as mentioned, may have happened in very late Pleistocene time, just prior to Holocene time, because there are no breaks in the alluvium. At the west base of Williams Hill there is suggestive evidence that the Monterey Shale was ele- vated along the east strand of this segment against older alluvium to the southwest. Elsewhere in this area both strands are in places covered by this alluvium. The Paso Robles Formation, primarily of Pleistocene age, is the youngest formation definitely involved in displacements and deformation along both the Rin- conada and Reliz faults. Therefore these faults were active in late Pleistocene time. Along the Rinconada fault, vertical displacements that involve this forma- tion are not large, generally less than a few hundred metres (1,000 ft). Along the Reliz fault north of Arroyo Seco they are greater. The amount of lateral displace- ment of this formation is not measurable. MOVEMENTS IN PLIOCENE TIME The unconformable relation of the Paso Robles For- mation (and of the Pliocene upper sandstone unit of the Pancho Rico Formation where present) to the more se- verely deformed Miocene formations along and near the Rinconada fault suggests that this fault was strongly active in Pliocene time. A large amount of lateral displacement since early Pliocene time is suggested on the San Marcos segment by differences in the Miocene and Pliocene stratigra- phy on opposite sides of that segment. Durham (1965b) pointed out that the northernmost extent of the Santa Margarita Formation and southernmost extent of the Pancho Rico Formation nearly coincide and that both have been displaced about 18 km (11 mi) by right-slip movement on an undesignated northwest-trending fault. This interpretation of that amount of right-lateral movement is accepted herein, but it applies to the San Marcos segment of the Rinconada fault, as shown in figure 16. On the northeast side of this fault, logs of exploratory wells drilled for oil or gas indicate that the Pancho Rico Formation extends far south of the north- ern limits of the Santa Margarita Formation. From these relations (fig. 16) it is probable that the San Mar- cos segment, if not adjacent) segments, of the Rin- conada fault were active since early Pliocene time with right-lateral movement that amounted to as much as 18 km (11mi). Most of this movement probably pre- ceded deposition of the Paso Robles Formation and pos- sibly the upper sandstone unit of the Pancho Rico For- mation. Additional evidence of right-lateral displacement on the Rinconada fault since deposition of the Monterey Shale is suggested by the areal extent farther north- west of the thick upper part of the Monterey Shale. The absence of the Santa Margarita Sandstone, overlying the Monterey Shale, on the west side of the fault also suggests this displacement. MOVEMENTS SINCE EARLY MIOCENE TIME The occurrence of the basal terrestrial unit of the middle Tertiary sedimentary sequence farther north- west on the west side of the Rinconada fault than on the east side could be the result of right-lateral dis- placement on the Rinconada fault (see "Rock Units”). More data on the subsurface extent of this unit are needed to test this hypothesis. At Harris Valley about 3 km (2 mi) west of San An- tonio Reservoir west of the Rinconada fault, the sandstone of the upper part of the Vaqueros Formation contains several thick lenses of conglomerate com- posed of unsorted cobbles and boulders almost entirely of granitic detritus (fig. 10). These lenses pinch out southwestward, and their northeastward extent is con- cealed. They must have been derived from a granitic terrane, despite the fact that the exposed Vaqueros Formation throughout this area is underlain by the 37 REGIONAL EVIDENCE OF LARGE STRIKE .omomm | ‘ SLIP MOVEMENT ON THE RINCONADA-RELIZ FAULT ZONE 1233 .Bmme “Swat—#0 (“can @2558 flan n: flaw“ mvmaoofim was no image: mzm$fihm Em? ma Eofiwfiioh mfihmwhmz macaw .N £5: 98032 gang: «in EOENESQ 03m osunmm .H £55 @2325 $32 we 39:86.3va vwhomfiuléa "559m F oON F V wo has: so: @823“. >535 x N ”:55 MO wfiOwXD meEEHOHmOBSHHO—u Unuuowfi— O o 0 O o o o o M «mg! 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SEE 283on ,U m God «5an .m6 hammom £2an0 22:83 05 :o 8:253 ififizfimow F833,.“ $32 93 308320 Saab mo Bauufiofimng Ewan mo 38:8 ofin—mfiuoéoonb ,< ©2260 3E: Moon U C020 \/ /\% \ «Ea 33835 3.08 oEmHoESoE \/ A/\3;th 532 can $08880 Saab \/\ z \/ \ \/ / MUOAQ Z<~Z~A z, x , \x / . _ $ / / /\ \ Q y \/ \/,_ // \ \ ©va 92%? \/,\//W //\\/,<\A //\//\ \ \ /\// //\ $ I >9 # _ wmemEOfiv. ow om ON OF 0 fiLlllLlllL mmiE om ON or o \\ omm 40 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA and Reliz faults is composed mostly of metamorphic rocks with the exception of the northern Santa Lucia Mountains where the basement is plutonic, whereas that exposed and struck in many deep wells east of those faults is mostly plutonic. This condition is suggestive of large displacement, either vertical or lat- eral, on a possible fault zone that may have existed prior to Late Cretaceous time and that evolved into the Rinconada and Reliz fault alinement, as suggested by Nilsen and Clarke (1975, p. 35). Work on the crystalline basement complex of the Salinian block is in progress (Ross, 1972; 1974). STRIKE-SLIP MOVEMENT AS SUGGESTED BY CONFIGURATION OF BURIED SURFACE OF BASEMENT COMPLEX The inferred configuration of the surface of the crys- talline basement complex under the sedimentary cover of the central Salinas Valley region is about as shown in figure 18. The positions of contours near wells and basement exposures are deemed moderately accurate but elsewhere are inferred from the geology. It should be noted that this is one of several alterna- tive contour interpretations, some of which show no displacement on the Rinconada fault zone (Durham, 1974, pl. 3). In my opinion the one shown seems to be the most probable interpretation on the basis of the available data. As shown in figure 18, the partly exposed basement high near Paso Robles (or possibly the basement expo- sure of the La Panza Mountains to the southeast) east of the Rinconada fault may have been displaced at least 38 km (25 mi) right laterally on the fault from the buried shallow basement high (Lockwood high of Durham, 1974, p. 13, pl. 3) near Lockwood. The estimated 3,658-km (12,000-ft)-deep trough west of Bradley on the east side of the Rinconada fault may be displaced by that same amount from the 3,048 km (10,000-ft)-deep trough in the Arroyo Seco area west of the Rinconada-Reliz fault alinement. If this interpretation is correct, these faults are continuous at depth, even though there is a gap between the Rin- conada and Reliz faults at the surface. The inferred continuous southward increase in depth to the basement complex on the west side of the Rin- conada fault northwest of Paso Robles (fig. 18) is the effect of the southward slope of the basement surface under the thick regionally southward-dipping Upper Cretaceous and lower Tertiary sedimentary sequence. A similar condition must exist east of this fault south- eastward from the La Panza Range (southeast of Paso Robles). Displacement of this southward-sloping basement surface is nearly 60 km (38 mi), in accord- ance with the offset shown in figure 17. REGIONAL TECTONICS ALONG AND NEAR THE RINCONADA-RELIZ FAULT ZONE CONCEPTS OF TECTONIC EVOLVEMENT OF THE COAST RANGES The tectonic evolvement of the Coast Ranges and intervening valleys to their present form has been in- terpreted in Various ways by geologists who have done or directed extensive geologic work within them. Willis (1925, p. 270—271) interpreted the Coast Ranges as crustal segments elevated primarily by northeastward thrusting on major faults that bound some of the ranges on the northeast and curve southwestward under them to eventually extend under the Pacific Ocean at depth. He interpreted the San Andreas and Sierra Nevada faults as two of these southwest-curving faults. Clark (1929) interpreted the coast ranges and valleys to have been formed as fault blocks bounded by high angle faults, with the elevated blocks forming the ranges and the depressed blocks the valleys, and sup— posed that each block acted independently. Reed (1933, p. 55—58) questioned Clark’s fault-block theory and suggested that the ranges were elevated primarily by folding and then became faulted along one or both margins as deformation progressed. Taliaferro (1943a, p. 157—158) concurred with Reed (1933) that the Coast Ranges, such as the Santa Lucia Mountains, were formed by uplift on one or both sides by compressive folding and eventually by thrusting outward toward the adjacent valley or valleys. Hill and Dibblee (1953, p. 455) hypothesized that the Coast Range structures are genetically related to the San Andreas and other high-angle faults along which movements have been strike slip during late if not all of Cenozoic time, in accordance with the law of uni- formitarianism, with as much as 560 km (350 mi) of cumulative right-lateral movement on the dominating San Andreas fault. They asserted that the folds and accompanying thrust and reverse faults in the Coast and Transverse Ranges are shallow structures gener- ated by strike-slip movements on the deep-seated high-angle faults. Crowell (1952, 1962) independently arrived at similar conclusions regarding large strike- slip movements on the San Andreas, San Gabriel, and other major high-angle faults in southern California. Christensen (1965, p. 1118—1119) interpreted the Coast Ranges to have been elevated vertically as the result of forceful plutonic intrusions at depth and suggested that the folding and thrust faulting along their margins may be the effect of downward move- ment of the elevated mountain masses by gravity. During the last decade many publications have ap- peared, including those by Crowell (1968), Atwater (1970), and Nilsen and Clarke (1975), that relate tec- REGIONAL TECTONICS ALONG AND NEAR THE RINCONADA-RELIZ FAULT ZONE EXPLANATION I / \\ \\ / / / /\ Exposed basement complex —— -2000— Contours on top of buried basement complex Contour interval 2000 feet Datum is mean sea level 0 Well that reaches basement complex L FIGURE 18.—Inferred configuration of buried sur Paso Robles to Greenfield. In part based on we and much modified from Gribi (1963, p. 26). face of crystalline basement complex a1 121° \ \ , Paso Robles O 5 10 MILES 0 5 10 15 KILOMETRES I 11 data from Burch and Durham (1970), Burch (1971), and Durham l fl ong Rinconada-Reliz fault zone from (1974), 41 42 RINCONADAND RELATED FAULTS, COAST RANGES, CALIFORNIA tonics along the San Andreas fault system to the global theory of plate tectonics and continental drift. In so doing, nearly all accept the concept of large cumulative right-lateral movement on the San Andreas fault sys- tem and related tectonics advanced by Hill and Dibblee (1953) and Crowell (1962). From the extensive geologic mapping I have done since 1938 within 50 km (35 mi) of much of the San Andreas fault, including the geologic data presented in the foregoing sections of this report, I conclude that the Coast Ranges have evolved in accordance with the tec- tonic genesis postulated by Hill and Dibblee (1953) and Crowell (1952, 1962). This concept therefore serves as a basis for the tectonic interpretations presented in this section. TECTONIC PATTERN The tectonic pattern along the Rinconada-Reliz fault zone is fairly well defined. The tectonic pattern and upheaval along the Espinosa segment of the Rinconada fault are shown diagramatically in figure 19. This con— dition is general in varying degrees along the entire course of the Rinconada-Reliz fault zone. The persist- ent slightly more east-west trend of folds in the sedimentary rocks as compared to the trend of both faults is interpreted to be the drag effect of right- lateral movement on the faults in the underlying basement complex. Thrust and reverse faults that dip inward toward the Rinconada fault from one or both sides probably evolved from large ruptured folds and, together with the intensity of the associated folding, indicate severe compression of one block against the other, or resistance to lateral slip. This resulted in severe squeezing along one or both sides of the Rinconada-Reliz fault zone. On a regional scale, the major tectonics of the south- ern Coast Ranges are basically similar to the smaller scale tectonics along the Rinconada-Reliz fault zone. The major tectonic features of the area of figures 1 to 5 are as interpreted in figure 20. All the present uplifts shown were formed during late Cenozoic (primarily Quaternary) time. Throughout this area, in both the Salinian and Coastal block, the axes of major uplifts (except the Gabilan uplift) and the intervening troughs trend slightly west of northwest, as do the thrust faults and fold axes. The consistency of this trend indicates crustal squeezing or shortening normal to this trend from a compressive stress that acted accordingly. EXPLANATION /——~ Sedimentary rocks Basement complex FIGURE 19.—Right-slip tectonics and compressive upheaval along the Espinosa segment of the Rinconada fault. REGIONAL TECTONICS ALONG AND NEAR THE RINCONADA—RELIZ FAULT ZONE These parallel structures are contemporaneous with and may be subsidiary to right-lateral movements of blocks on the major faults, such as the San Andreas, Rinconada, Reliz, and other lesser faults shown in figure 20 which trend slightly north of northwest. The Rinconada-Reliz fault zone divides the region southwest of the San Andreas fault into two geologic blocks of strips, the east strip and the west strip, which 36° 43 differ somewhat structurally and physiographically. The east strip, wholly within the Salinian block, is structurally and physiographically simple, in general. The northern part is almost unfaulted and includes the major part of the Salinas Valley, which merges east— ward into extensive areas of hills and low mountains including the Gabilan Range, which rises to about 650 m (2,000 ft). The east strip becomes increasingly flirt EXPLANATION \\§\\\ \ ; Exposed Franciscan basement complex of Coastal block Exposed crystalline basement complex of Salinian block _.> ______——— (— High-angle strike-slip fault _A__A_-L— Reverse or thrust fault 1 (sawteeth on elevated block) \ MAJOR FAULTS RE Reliz fault S] San Juan fault RI Rinconada fault '1 BP Big Pine fault NA Nacimiento fault /// A i HHHIH /// Approximate crest line of late ‘7 Quaternary uplift ( not neces- / 0 sarily anticlinal) ( ._' '— ‘ ' . \\ )‘ Approxlmate trough line of areas between uplifts (gener- ally synclinal) (—— Direction of extensive late Quaternary tilt UPLIFTS TROUGHS / “\fiv ’. Northeast of Rinconada-Reliz fault zone //_\ \\\\\ é! \ \ A. Gabilan 1. North Salinas \ B. Caliente 2. South Salinas / C. La Panza 3. Cuyama o D. Sierra Madre 4. Madulce syncline 35 E. Pine Mountain (pre-Miocene) Southwest of Rinconada-Reliz fault zone ‘\ F. Sierra de Salinas 5. Arroyo Seco N //\\ G. North Santa Lucia 6. Lockwood \/ / 1 /\ H. Junipero Serra Dome 7. Nacimiento / 1. Coast Ridge (largely pre-Miocene) // / K. South Santa Lucia 8. Huasna L. San Rafael Mountain ‘ “ ‘ III/HM] HMHH \ ////l / \\\111¢HI|1|||\\ /|\\// “I \\\\ 0 1O 20 30MILES llllll|\\\ i w/‘HIHHHHWHL O 10 20 3O 4O KlLOMETRES x 122° 121° 120° 119° FIGURE 20,—Major tectonic features of the southern Coast Range region in Vicinity of the Rinconada-Reliz fault zone. 44 complex southeastward as parts of it were elevated along faults to form the La Panza and Caliente Ranges, which separate the Carrizo Plain from Cuyama Valley, and the Sierra Madre Range, elevated on faults south of that valley. The Sierra Madre Range, the highest of this strip with altitudes of more than 1,600 m (5,000 ft), is physiographically part of the west strip, but it lies east of the Rinconada fault. The east strip includes Mount Pinos at its easternmost tip with an altitude of 2,600 m (8,000 ft). In contrast, the west strip, which includes parts of both the Salinian and Coastal blocks, is structurally complex nearly throughout. It is an area of ranges of mountains and hills and includes only a few very small valleys. It is made up largely of the Santa Lucia—San Rafael Mountain belt, which is structurally the most complex and mobile part of the southern Coast Range province west of the San Andreas fault. The northern part of the west strip is elevated along the Reliz fault against the Salinas Valley part of the east strip. The southwest border of the west strip is poorly defined, but it is arbitrarily placed at the southwestern base of the Santa Lucia—San Rafael Mountain belt because this is the only continuous physiographic lineament. North- ward this strip terminates at the high northern Santa Lucia Mountains with altitudes of more than 1,600 m (5,000 ft). Southward it terminates either at the high part of the San Rafael Mountains north of the Big Pine fault with altitudes of more than 2,000 m (6,500 ft) or farther southeast at the Santa Ynez fault. This strip thereby attains its greatest altitudes at its northern and southern extremities. TECTONIC FEATURES OF THE EAST STRIP The northwestern part of the east strip is made up primarily of the Gabilan uplift (A, fig. 20). This is a stable mass of crystalline basement complex (mostly plutonic) in large part overlain by a thin cover of mid- dle and late Cenozoic sedimentary deposits. This uplift is slightly arched along an axis near the San Andreas fault and is tilted gently southwest toward the Salinas trough (1 and 2, fig. 20). The thin sedimentary cover is generally undeformed, except along the margins where it is folded probably by inferred right-lateral drag on the San Andreas and Rinconada-Reliz fault zones. In the southeastern part of the east strip the surface of the basement complex deepens southward as the middle and late Cenozoic sedimentary cover thickens. The narrow wedge east of the San Juan fault within this part of the east strip was dragged southward along this fault and compressed into several southward- leaning and southward-thrust large anticlinal folds to form the Caliente Range uplift (B, fig. 20). RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA The La Panza uplift (C, fig. 20) was formed by arch— ing and northeastward tilt on the northeast-dipping La Panza thrust fault. South of the La Panza and Caliente uplifts the east strip is increasingly deformed south- ward, as the top of the basement complex deepens even more so under a great thickness of the Upper Creta- ceous and lower Tertiary sedimentary sequence, now exposed in the Sierra Madre Mountains where it is synclinally folded adjacent to the Rinconada fault. A long wedge of this thick sequence adjacent to this fault was severely compressed and elevated along the southwest-dipping south Cuyama and Ozena thrust faults toward Cuyama Valley to form the Sierra Madre uplift (D, fig. 20) during late and possibly middle Cenozoic time. The east-trending Big Pine fault was active in Quaternary time as indicated by left-lateral displace— ment and deflection of some canyons that cross it (Hill and Dibblee, 1953) and may have been active earlier. Major left-lateral movements on this transverse fault dispalced the Sierra Madre uplift (D, fig. 20), Madulce trough (4, fig. 20), Ozena fault, and possibly the Rin- conada fault, all about 14 km (9 mi), indicating that this transverse fault is in large part younger than all those features. The Pine Mountain uplift (E, fig. 20), the probable displaced counterpart of the Sierra Madre uplift, was elevated in Quaternary time on the north- east-dipping Pine Mountain fault. This fault may have been reactivated on an earlier, displaced extension of the Rinconada fault on which there may have been much right-lateral movement in late Tertiary time. Evidence suggesting this movement is the similarity of the Eocene stratigraphy of the Pine Mountains uplift to that of the southeastern part of the Sierra Madre uplift and its dissimilarity to that of the area south of the Pine Mountain fault. TECTONIC FEATURES OF THE WEST STRIP The northern part of the west strip is made up of a wedge of the Salinian block that is severely deformed to form the high northern Santa Lucia Mountains from which several major ridges extend southeastward to- ward the Rinconada-Reliz fault zone. This wedge is the most intensely deformed part of the Salinian block and is composed of four major uplifts and two intervening troughs (F, G, H, I, 5 and 6, fig. 20). The middle Ter- tiary sedimentary sequence that once covered this area is preserved only as remnants in the troughs, which indicates that the uplifts formed after deposition of this sequence, or in late Cenozoic time. The Sierra de Salinas uplift (F, fig. 20; fig. 15) was formed largely as a southwest-tilted block of basement _ complex elevated on the Reliz fault. On its southwest REGIONAL TECTONICS ALONG AND NEAR THE RINCONADA-RELIZ FAULT ZONE flank it merges through complex structures as shown in figure 20 with the north Santa Lucia uplift. The Arroyo Seco trough (5, fig. 20; fig. 13) preserves much of the thick middle Tertiary sedimentary se- quence that is compressed into a complex synclinal structure that plunges east toward the Reliz fault. This trough might have been displaced on the Rinconada- Reliz fault from the south Salinas trough (2, fig. 20; fig. 18) of the east strip. Northwestward the Arroyo Seco trough once extended into a shallow syncline in Carmel River valley south of Monterey and into Mon- terey Bay. The middle Tertiary sedimentary sequence of this trough has been severely folded, disrupted by faulting, and involved with the adjacent uplifts to form part of the northern Santa Lucia Mountains during Quaternary time and is now undergoing erosion. The north Santa Lucia uplift (G, fig. 20; fig. 15) con- stitutes the major mass of the northern Santa Lucia Mountains. It is in large part bounded on the northeast by the southwest-dipping Tularcitos fault and the Arroyo Seco trough and on the southwest by the northeast—dipping Sur fault zone. Northward it termi- nates in the granitic mass on the Monterey Peninsula and undersea to the northwest. Southeastward it ex- tends into the J unipero Serra Dome (H, fig. 20). Struc— turally the north Santa Lucia uplift is primarily a group of subparallel northeast—tilted fault blocks, each elevated on a fault at its southwest border. At least two of these faults (Miller Creek and Church Creek faults, fig. 15) dip steeply northeast; two others to the north- west near the coast seem to deflect canyons right later- ally. This uplift was apparently elevated on these internal faults as well as on those that bound it. The position of the north Santa Lucia uplift, together with the Sierra de Salinas uplift, west of the Reliz fault may be tectonically significant. Because the Reliz fault is at the northwest end of the Rinconada—Reliz fault zone and because this mass of mountains is directly across it from the little disturbed part at Salinas Val- ley and the Gabilan uplift, it appears that these moun- tains formed by severe crustal compression or as a pile—up of basement terrane on only the west side of this fault zone as it dies out northwestward. If this is so, the Rinconada-Reliz fault zone acted somewhat as a tear fault between the stable, rigid east strip and the relatively northward moving west strip, and the crust- al compression or shortening that formed the moun— tains on the west side has absorbed the right-lateral movement at the northwest end of its extensive fault zone, as shown in figure 22. Southeast of Arroyo Seco the north Santa Lucia up- lift narrows into a localized mass of high mountains, or the Junipero Serra Dome of Compton (1966a, p. 1367; H, fig. 20). This uplift, which includes the highest 45 peaks of the Santa Lucia Mountains, is structurally similar to the main part of the north Santa Lucia uplift and was elevated as several parallel northeast-tilted blocks on northeast-dipping reverse faults, as mapped by Compton (1966a). Although these elevated blocks and the structure of the metamorphic basement rocks within them trend northwest, the long axis of this mountain uplift trends east-west nearly through its highest peaks. This indicates an overall north-south crustal shortening. The northwest trend of the fault blocks and their somewhat west-east en echelon ar— rangement suggests a possible right-lateral component of movement on the bounding faults, but proving evi- dence is lacking. Only the eastermost of these faults shows structural evidence of small right—lateral drag movement (fig. 13). The position of the Junipero Serra Dome and its fault blocks nearly west of the “gap” between the Rin- conada and Reliz faults (figs. 13, 20) suggests that this uplift formed as a secondary crustal compression or pile—up of basement terrane and that the 18 km (11 mi) of right-slip movement on the Rinconada fault during the late Cenozoic time was absorbed by the crustal shortening involved in the Junipero Serra uplift west of the area where the Rinconada. fault dies out north- westward. At the “gap,” what remains of this strike- slip movement was absorbed by intense folding of the sedimentary rocks. Lockwood Valley, the largest valley within the west strip, has remained depressed and little deformed rela- tive to the adjacent areas. This valley is structurally a trough, designated as the Lockwood trough (6, fig. 20), in the middle and upper Cenozoic sedimentary se- quences, which are underlain directly by the crystal- line basement complex, according to well data (fig. 18). The sedimentary sequences are intensely folded along the northern margin of this valley as the result of impingement by the Junipero Serra Dome and by the hills elevated along the Rinconada fault (Espinosa segment, fig. 12), and the sequences are moderately folded along the southwestern margin of this valley. The western extension of the trough has become involved in up'lift of the northern Santa Lucia Mountains. The Lockwood trough separates the Junipero Serra Dome from the south spur of the north Santa Lucia uplift, designated here as the Coast Ridge uplift (J, fig. 20). The Sur-Nacimiento fault zone may be taken as the southwest geologic boundary of this uplift, but it does not form a distinct physiographic boundary with the adjacent south Santa Lucia uplift (K, fig. 20). The Coast Ridge uplift forms a high crest of crystalline basement but decreases rapidly in height southeast— ward as it passes between the Lockwood and 46 Nacimiento troughs and as the basement complex be- comes covered by the overlying sedimentary rocks of these troughs. The structure of this uplift is complex but appears to be in large part arched. This uplift may have been displaced from the La Panza uplift (C, fig. 20) of the east strip, if originally continuous, on the Rinconada fault. The Nacimiento trough (7, fig. 20) is a synclinal structure composed of several en echelon axes in the thick Upper Cretaceous and lower Tertiary sedimen- tary sequence that overlies crystalline basement. It is so named for the conspicuous syncline along much of the upper Nacimiento River (fig. 10, 21). This sequence was deformed and eroded prior to deposition of the unconformably overlying middle Tertiary sedimentary sequence. During late Cenozoic time both sequences were deformed when the Rinconada fault was active and the Nacimiento trough became involved with the adjacent uplifts to form an extensive area of hills. Only the southeastern part of this trough remained some- what depressed to form the narrow valley through Templeton and Santa Margarita (fig. 9). The synclinal structure in the Upper Cretaceous and lower Tertiary sedimentary sequence might have been displaced as much as 60 km (38 mi) on the Rinconada fault from the Madulce syncline in that sequence (figs. 4, 7, 20) of the east strip, if originally continuous. The southern part of the west strip is part of the coastal block of Franciscan basement and forms a structurally complex belt of mountains, designated as the Santa Lucia—San Rafael Mountain belt, composed of the central and southern Santa Lucia Mountains, San Rafael Mountains, and intervening lower ranges of hills. The south Santa Lucia uplift (K, fig. 20) consists of intensely deformed Franciscan rocks and overlying Cretaceous sedimentary rocks squeezed up southwest of the Nacimiento and Las Tables faults and farther south against the Nacimiento trough and the Rin- conada fault. Near San Luis Obispo the south Santa Lucia uplift divides southeastward into two narrow uplifts of hills separated by the Huasna trough (8, fig. 20), a complex synclinal structure in the middle Tertiary sedimentary sequence that unconformably overlies the previously deformed Cretaceous sedimentary sequence and Fran- ciscan rocks. This trough probably formed a valley in early Quaternary time but has since become involved with the adjacent uplifts to form part of the Santa Lucia—San Rafael Mountain belt. The San Rafael Mountain uplift (L, fig. 20) rises south of the Huasna trough to more than 2,000 m (6,000 ft) against the Big Pine and other faults to the south. RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA REGIONAL TECTONIC ANALYSIS The Salinian and Coastal blocks were juxtaposed, presumably by a large amount of movement along a great shear plane, such as the, Sur-Nacimiento fault zone. How theyjuxtaposed is not known. It might have been by a large amount of lateral slip (Curtis and others, 1958). However, Page (1970a, 1970b) postu- lated that it was by thrusting (subduction) of the oceanic Coastal block northeastward under the Sali- nian block, which he interpreted as part of the conti- nental plate, in accordance with the plate tectonic theory. This inferred plane of underthrusting was des- ignated as the Coast Ranges subduction zone by Hill (1971, p. 2959). If this postulation is correct, this movement resulted presumably from a direct north- east-southwest compressive stress normal to the sub- duction zone. The time of subduction, or Whatever mechanism by which these blocks were juxtaposed, was prior to Oligocene time (Page 1970b). As suggested by Hill (1971, p. 2959), it may have been just before or during deposition of the coarse sandy sediments of Late Cre- taceous age, because these are the oldest arkosic sedi- ments on both blocks and because they lie unconform- ably on the basement rocks of the Salinian block and also on the Lower Cretaceous shale unit of the Coastal block near Stanley Mountain (Hall and Corbaté, 1967) and possibly in the San Rafael Mountains. In the Santa Lucia Mountains the Upper Cretaceous unit may be unconformable on this shale unit and the Franciscan rocks (Taliaferro, 1944) or may have been, but now in most if not all places is, in fault relation (Brown, 1968; Page, 1970a, 1970b, 1972) possibly by later or con- tinued subduction. Eventually, the Franciscan rocks of the Coastal block, which presumably were deposited in an offshore trench in Mesozoic time, became squeezed and up- heaved against the advancing continental block of crystalline rocks by Oligocene time. During that time, the supposed subduction tectonics, if they were the actual mechanism, were converted to right-lateral strike—slip tectonics on high—angle northwest-trending shear zones such as the San Andreas fault, as sug- gested by Atwater (1970, p. 3525—3529), along which blocks were carried past each other laterally as well as compressed against each other. These tectonics pre- vailed throughout middle and late Cenozoic time; they may have started before Oligocene time if the San An- dreas fault first formed as a strike-slip fault before that time, as suggested by Wentworth (1968, p. 139—140), Ross (1970, p. 3661—3662), and Clarke and Nilsen (1973, p. 302). Within the area of figures 1 and 20 west of the San REGIONAL TECTONICS ALONG AND NEAR THE RINCONADA-RELIZ FAULT ZONE 012 3 4 5 6 7K|LOMETRES \ ‘” ‘ "WWW/W . %////Z//7///7//%////é/9%/ -: 2 ails 8 a/flM/MW //// Ca°l\\‘f§////////ZA //' // ”7/ 723.1%) / / ”/, /. // w%W/% ////4/// / _ Lower Tertiary and \\ \\\\\\\\ b — and Pliocene Upper Cretaceous _ Cretaceous and Upper Jurassic 0 a _ 7/4??? Pancho Rico Formation _- Pliocene Tm Holocene — Miocene _ Miocene and Oligocene _ Mesozoic and Paleozoic(?) A Pleistocene EXPLANATION ed beds (Tvr) rine sedimentary equence; basal onglomerate (cg) Franciscan rocks and serpentine, gabbro (g) _ Sur Series Alluvium var/:0 // ; queros Sandstone . Monterey Shale / % W // 7 ///// ‘r/W/ / W/ / 2'.;g/////////// / / l/Z// ’ M ”-11.6“: -. ‘ - r o a as\\ u I\\ /_ 0 191' ° Paso Robles Formation O O m > '2. a _ _/ — . <\ \Z‘ Plutonrc rocks and 121°30' FIGURE 21,—Geology of the upper Nacimiento River area and vicinity (in part modified from Page, 197021). 48 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA Andreas fault, the Rinconada-Reliz fault zone is the largest strike-slip shear zone along which right-lateral movement took place in middle(?) and late Cenozoic time, as indicated by the evidence presented herein. Much of this movement was distributed and taken up by other lesser faults of similar trend, as well as by folding and thrust faulting within this area. In Cenozoic time right—lateral movements on the southern part'of the Rinconada fault followed the old Mesozoic Sur-Nacimiento fault zone or Coast Ranges subduction zone of Hill (1971). In this respect, the Rin- conada fault bears the same relation to that zone as the late Cenozoic Newport-Inglewood zone bears to the Mesozoic southern California subduction zone as pos- tulated by Hill (1971, p. 2959). Since Oligocene time, the Sur-Nacimiento fault zone was apparently inactive northwestward from the Rin— conada mine where the Rinconada fault veers north- ward from that zone, except for small local movements. This inactivity is indicated by the burial of that zone by the middle Tertiary sedimentary sequence between that point and the southeast end of the Nacimiento fault. The Rinconada-Reliz fault zone is inferred to have formed along the old Mesozoic subduction(?) zone as far northwest as the Rinconada mine and then to have veered away northward into the Salinian block, paral— lel to the San Andreas fault and slipped laterally in the same manner. Thereby, during late Cenozoic time, the west strip was carreid northward relative to the east strip along the Rinconada-Reliz fault zone. The east strip of the Salinian block between the San Andreas and Rinconada-Reliz fault zones reacted to stress as a generally rigid mass, compared to the adja- cent blocks. The northern part, along which the crys- talline basement is exposed in the Gabilan Range and buried under a thin middle and late Cenozoic sedimen- tary cover elsewhere, resisted deformation and crustal shortening during middle and late Cenozoic time to form a stable area with a surface near sea level. The only deformation of this strip was partial uplift by arching along an axis near the San Andreas fault to form the Gabilan Range (fig. 20). The southern part of the east strip, where the buried basement surface deepens southward under sedimen- tary sequences, yielded somewhat to become increas- ingly deformed southward and was impinged south- ward against part of the Transverse Ranges. This may account for the intense compressive deformation of the very thick sedimentary sequences of those ranges. The west strip, in contrast to the east strip, yielded to stress almost throughout its length during the mid- dle and late Cenozoic diastrophism to form the complex series of parallel uplifts along the Santa Lucia—San Rafael mountain belt, as described. The southern part of this strip, that within the Coastal block, is the most intensely deformed part because much of the Francis— can basement is melange with little internal strength. The overlying Cretaceous marine strata are severely shattered and broken, forming poor exposures in con- trast to the prominent unshattered exposures of the Upper Cretaceous and lower Tertiary marine sedimen— tary sequence on the Salinian block. The northern part of the west strip, even though it is within the Salinian block which has a rigid crystalline basement, is nearly as intensely deformed as the southern part. The northwesternmost part was com- pressed and upheaved between the Reliz and Sur faults and on a number of reverse faults within it to form the high, rugged northern Santa Lucia Mountains during late Cenozoic time. This upheaval formed by crustal compression or pile-up west of where the Rinconada- Reliz fault zone dies out and involves several kilometres of north-south crustal shortening of the west strip compared to almost none of the east strip across this fault zone. This shortening on only one side of this fault zone thereby presumably absorbed the large right-lateral slip on the Rinconada-Reliz fault zone as it dies out northwestward, as demonstrated in figure 22. The lowlands and Monterey Bay north of this com- pressive uplift were only slightly affected by crustal movements and thereby remained compartively stable to form part of the still-depressed North Salinas trough (1, fig. 20). REGIONAL SIGNIFICANCE OF THE RINCONADA-RELIZ FAULT ZONE I conclude that the Rinconada-Reliz fault zone is the most extensive late Cenozoic transcurrent fault zone in the southern Coast Ranges west of the San Andreas fault and that the tectonic and physiographic features of the area traversed by the Rinconada—Reliz fault zone BLOCK B f __; ‘— BLOCK A FIGURE 22.—Block diagram illustrating mechanics of conversion of strike-slip movement along a high angle fault into compressive uplift of one block as fault terminates. Block B, which moved to the right along fault (0 relative to block A was compressed and bulged upward at C near end of fault. Northern Santa Lucia Mountains were elevated probably in large part in this manner as the Rinconada-Reliz fault zone dies out northward. REGIONAL TECTONICS ALONG AND NEAR THE RINCONADA-RELIZ FAULT ZONE 49 (figs. 2, 20) are probably drag features formed by or controlled in part by northwestward movements of the west strip relative to the east strip of the fault zone, together with right-lateral movements of the more ac- tive San Andreas fault. The Rinconada-Reliz fault zone is therefore a major subsidiary or companion fault of the San Andreas, but with a somewhat different his- tory of movement. The position of the Rinconada fault is en echelon to two other major faults of similar extent, trend, and movement: the San Gregorio fault to the northwest and the San Gabriel fault to the southeast. The en echelon position of the Rinconada-Reliz fault zone be- tween these two major faults and the similar move- ment history of all of them suggest that all are tectoni— cally related as faults subsidiary to the San Andreas as indicated in the interpretations that follow. Northwestward the Rinconada-Reliz fault zone dies out probably south of Monterey Bay, but the San Gre- gorio fault (Branner and others, 1909; Jennings and Burnett, 1961) along the southwestern margin of the Santa Cruz Mountains is nearly parallel to and north- west of the Reliz fault zone but is farther west. The San Gregorio fault had a comparably large amount of right-slip movement, as suggested by dissimilarity of rock units and structures mapped on opposite sides (Brabb, 1970; Clark, 1970; fieldwork by myself in 1948—49). According to recent work by Greene, Lee, McCullock, and Brabb (1973), that fault extends southeastward offshore across subsea Monterey Can— yon and onshore into either the Palo Colorado or Sur fault or both (fig. 15), along which its right-slip move- ment eventually dies out. Consequently, the right—slip movement of the Rinconada—Reliz fault zone must have been transferred through the many large northwest- trending faults in the northern Santa Lucia Mountains to the San Gregorio fault northwestward, and so the right-slip movement on both faults was absorbed in the crustal compression or pile-up that formed these mountains between the extremities of these two en echelon major faults (fig. 23). A small part of this movement was probably absorbed by the many small right-slip faults in Monterey Bay (Greene and others, 1973). Southeastward the Rinconada fault terminates against the Big Pine fault, but its extension beyond that fault may be the Pine Mountain fault (fig. 4), as suggested previously, even though the Pine Mountain fault is a north—dipping reverse fault on which Pine Mountain was elevated. If the Pine Mountain fault were once part of the Rinconada fault, it may have originally trended southeastward, but since it was dis- placed by left slip on the Big Pine fault, it probably has been dragged into a more easterly trend by left slip on that fault to become parallel to the more easterly trending part of the San Andreas fault and evolve into a north-dipping reverse fault as the Pine Mountain block was squeezed upward on it. The Pine Mountain fault curves southeastward and dies out near the San Gabriel fault to the east. The San Gabriel fault extends about 144 km (90 mi) and dips steeply northeast. This fault was active dur- ing late Cenozoic time but mostly during Pliocene time, with an inferred maximum cumulative right slip of about 40 km (25 mi) (Crowell, 1952; Dibblee, 1968). It is therefore related to the San Andreas fault, but its history of movement was similar to that of the Rin- conada fault. Consequently, the inferred right-lateral movements on both faults may have been absorbed by conversion to compressive vertical movements be- tween or near their extremities to form the Sierra Madre Mountains and Pine Mountain—Alamo Moun- tain uplift (fig. 24), in much the same way that the northern Santa Lucia Mountain were formed between the Reliz fault and the probable southeastern exten- sion of the San Gregorio fault. During Quaternary time left slip on the Big Pine fault, which is apparently younger than the Rinconada fault, not only offset the Rinconada fault but also prob- ably impeded or locked right-slip movements on it, and so as stress continued the lateral movements became converted to thrusting movements on the South Cuyama, Ozena, Pine Mountain, and Little Pine faults. The influence of lateral movements of the blocks or strips bounded by the San Andreas fault, Rinconada— Pine Mountain fault combination, and the San Gabriel fault during late Cenozoic time extended far to the southwest. Assuming that the east strip of the Salinian block, which has a relatively rigid crystalline base- ment complex, between the San Andreas fault and the Rinconada, Pine Mountain, and San Gabriel faults was stationary relative to the adjacent blocks, the block east of the San Andreas fault was moving relatively southeastward, and the block west of the Rinconada, Pine Mountain, and San Gabriel faults was moving relatively northwestward (fig. 24), or actually north- ward, against this intervening strip. The continued irresistable force of these movements caused severe impingement northward against this strip of the Salinian block by the Coastal block which contains the very thick sedimentary accumulations of the Santa Barbara trough that in large part overlie Franciscan basement. This impingement resulted in intense buckling and upthrusting of this thick sedimentary crust to form the San Rafael, the Santa Ynez—Topatopa, and Santa Susana Mountains, and possibly the Santa Monica Mountains. The north- 50 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA dipping thrust or reverse faults under Frazier Moun- tain, Pine Mountain, Topatopa Mountains, and the Santa Susana Mountains (fig. 24) may be the effect of counterimpingement from the east strip of the Sali- nian block, as well as compressive movements along the San Gabriel fault. Rinconada-Reliz fault zone, together with other major right lateral faults, is their elongation of the Salinian block. Johnson and Normark (1974, p. 11—14) pos- tulated that prior to early Tertiary time the Salinian block, which is part of the borderland of the North American plate, fitted into the 300 km (185 mi) gap Another significant tectonic effect of the between the Sierra Nevada and Peninsular Ranges 123° 122° 121° | J EXPLANATION 38° — . . . ‘ Elevated area Half arrows indicate direction of inferred lateral movement of fault-bounded blocks relative to the block bounded by the San Andreas, Rinconada-Reliz, and San Gregorio faults that is assumed to be relatively stationary 37° * — Monterey Bay); § // and Canyon\\,‘\ 3/) \ II: ".\I“I . .- . NORTHERN SANTA LUCIA MOUNTAINS 36° ‘ ‘ O 10 20 30 Ml LES O 20 40 Kl LOMETRES I I FIGURE 23,—Inferred tectonic movements in vicinity of northern Santa Lucia Mountains showing conversion of right-slip movements near ends of Rinconada-Reliz fault zone and San Gregorio fault into crustal compression and uplift of intervening area to form these mountains. REGIONAL TECTONICS ALONG AND NEAR THE RINCONADA-RELIZ FAULT ZONE 51 basement terranes and that it bulged westward; dur- ing Neogene time, the Salinian block was displaced northwestward to its present position by right slip on the San Andreas fault and the block has been sliced and elongated to about 600 km (370 mi) or about twice its orginal length by right slip on the Rinconada—Reliz and other major longitudinal faults Within this block as it became attached to the relatively northward mov— ing Pacific plate. They also claimed that there is no need for a proto-San Andreas fault within the Salinian block. These views differ SOmewhat from those by Nilsen and Clarke (1975, p1, 48—52), who postulated, from their sedimentology studies of early Tertiary strata l EXPLANATION _A._A_A_ . Reverse or thrust fault ELEVATED AREAS (s awteeth on elevated block) LP La Panza Range All other faults CR Caliente Range are high-angle SL Santa Lucia Mountains SR San Rafael Mountains SA Sierra Madre Mountains MP Mount Pinos PM Pine Mountain AM Alamo Mountain SY Santa Ynez Mountains TM Topatopa Mountains SS Santa Susana Mountains SM Santa Monica Mountains SG San Gabriel Mountains 35° — 34° — — LOS ANGELES Half arrows indicate direction of inferred lateral movement of 0 1O 20 30 MILES fault-bounded blocks relative to the block bounded by the San Andreas, Rinconada, Pine Mountain, and San Gabriel 0 10 20 30 40 KI LOMETRES faults that is assumed to be relatively stationary | | 121° 120° 119° 118° FIGURE 24,—Inferred tectonic movements in Vicinity of Sierra Madre Mountains and Pine Mountain, showing inferred conversion of right-slip movements near ends of the Rinconada and San Gabrel faults to crustal compression to form these ranges. 52 RINCONADA AND RELATED FAULTS, COAST RANGES, CALIFORNIA and the comparatively greater displacement of base- ment rocks of the Salinian block than the lower Ter- tiary sedimentary rocks, that the Salinian block was displaced northwestward from the continental land- mass on a proto-San Andreas fault prior to early Ter- tiary time; and that clastic sediments were being deposited in early Tertiary time in deep marine basins formed perhaps as rhombochasms between rising source areas within the Salinian block from move- ments related presumably to right-lateral movements on the proto-San Andreas fault. Evidence of pre-early Tertiary displacement of the Salinian block presented by Nilsen and Clark (1975) is reasonably convincing. If there is a proto-San Andreas fault in the Salinian block, it is probably close to or at the present San Andreas fault. The slicing or dis- placement of at least one large sedimentary basin, the Sierra Madre basin, in the Salinian block during Neogene time by the Rinconada fault is one evidence that the Salinian block has been elongated during Neogene time by faults parallel to the San Andreas as postulated by Johnson and Normark (1974), even though parts of the fault strips have been shortened by compressive movements as indicated. EFFECT OF RINCONADA-RELIZ FAULT ZONE ON PHYSIOGRAPHY AND DRAINAGE The physiographic features and drainage of the area of figure 2 evolved directly from the tectonic features (fig. 20) formed in late Cenozoic time. These in turn are genetically related in large part to movements on the Rinconada-Reliz fault zone and related faults. The ele- vated areas evolved into the present ranges of moun- tains and hills and are undergoing erosion. The inter- vening troughs that remained depressed are the valley areas through which the major streams from the ele- vated areas drain. These conditions indicate that the tectonic features are very young and are still forming. The mountain ranges uplifted adjacent to or near the Rinconada-Reliz fault zone form one of the major drainage divides of the southern Coast Ranges (fig. 2). Southeastward from the Rinconada mine, the principal divide is formed by the Sierra Madre and La Panza Ranges elevated northeast of the fault. Northwestward from that point, the Santa Lucia Mountains elevated west of the Rinconada-Reliz fault zone from a drainage divide adjacent to the coast for 170 km (110 mi). The drainage pattern of the two strips opposite the Rinconada-Reliz fault zone are notably different (fig. 2). On the east strip, the major streams such as the Salinas and Cuyama Rivers drain northwestward, and most of their tributaries normally drain directly into them. In contrast, the major streams on the west strip that drain the east slope of the Santa Lucia Mountains, such as the Arroyo Seco, San Antonio, and Nacimiento Rivers, drain southeastward or eastward through structural troughs. Farther south, as this range de- creases in height and as the principal drainage divide shifts east of the fault, drainage is normally south- westward to the sea. The southeastward-draining San Antonio and Nacimiento Rivers are considered by Baldwin (1963) to be remnants of a drainage system in southern Salinas Valley that emptied eastward into San Joaquin Valley. However, I consider this theory improbable because both these streams follow troughs between uplifts of the West strip, and after crossing the Rinconada fault, both turn abruptly northeastward to flow directly to the northwestward-flowing Salinas River, which was established probably either during or after deposition of the Paso Robles Formation. POSSIBLE SEISMIC ACTIVITY No earthquakes attributed to the Rinconada or Reliz faults, faults branching from them, or thrust or reverse faults considered related to the Rinconada fault haVe been recorded during historic time. The area north- ward from Greenfield has been seismically monitored from 1969 to 1972 (Greene and others, 1973). The re- sults of this work showed numerous minor epicenters in the Gabilan Range just southwest of the San An- dreas fault. Only a few with magnitudes up to 4 (Rich— ter scale) were located on or jost southwest of the Reliz fault southwest of Gonzales. If these are located accu- rately, they suggest possible minor activity on this fault. The area of the Rinconada fault has not been monitored. Compared to the San Andreas fault, the Rinconada and Reliz faults pose little if any Seismic hazards and are probably inactive because no trenches, scarps, shutter ridges, or recently offset minor drainage chan- nels in the alluvium or even in the older alluvium have been positively identified along them. The Paso Robles Formation, the youngest geologic unit definitely trun- cated by the faults, is probably not younger than sev- eral hundred thousand or possibly a million years old. Except possibly at a few places, there are no surface indications that either fault has moved since deposi- tion of the older alluvium, which is estimated to be about 50,000 to 500,000 years old. Suggestive evidence of the latest movements on the Rinconada and Reliz faults are (1) deviation of canyons and stream channels locally on the Rinconada fault (figs. 11, 14) (2) possible fault contact of the Monterey Shale against older alluvium on Rinconada fault near Williams Hill (fig. 13); (3) shallow depression on Rin- REFERENCES CITED 53 conada fault 4 km (21/2 mi) north of Santa Margarita, due either to fault movement or to former stream ero- sion; (4) northwest-facing low scarps in older alluvium on Reliz fault southwest of Chualar (fig. 15), due either to vertical fault displacement or to erosion by a former course of the Salinas River; and (5) southwest-facing scarp on older alluvium on a minor fault near Reliz fault east of Paraiso Spring (fig. 15). Inasmuch as the Rinconada and Reliz faults pre- sumably have been inactive so long, it is not likely that they would generate an earthquake, although the pos- sibility exists. It is possible that some of the related thrust or reverse faults may generate an earthquake because several of these, such as the Los Lobos thrust, San Antonio fault, South Cuyama, Ozena, and Pine Mountain faults, as well as those at the base of the La Panza and Caliente Ranges, are at the base of steep probably actively rising mountain fronts. The Pine Mountain fault is potentially active be- cause it offsets left laterally some canyons that cross it (Hill and Dibblee, 1953, p. 452) and could generate an earthquake. The Sierra Madre and Pine Mountain areas are potential earthquake areas because these mountains are probably actively rising on the faults that bound them. Another likely area in which a major earthquake may originate is in the northern Santa Lucia Moun- tains, because this is an area of rigid basement com— plex that is being elevated on a number of major faults (fig. 15). 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Mines and Geology, p. 183—270, scale 1262,500. 0575 7 DAYS Analog-Model Analysis of Regional Three-Dimensional Flow in the Ground-Water Reservoir of Long Island, New York GEOLOGICAL SURVEY PROFESSIONAL PAPER 982 Prepared in cooperation with the Nassau County Department of Public Works, the Sufiolk County Department of Environmental Control, the Sufiolk County Water Authority, and the New York State Department of Environmental Conservation 1.13.5.1)? FEB 5:; 1977 Analog—Model Analysis of Regional Three—Dimensional Flow in the Ground-Water Reservoir of Long Island, New York By RUFUS T. GETZEN GEOLOGICAL SURVEY PROFESSIONAL PAPER 982 Prepared in cooperation with the Nassau County Department of Public Works, the Suffolk County Department of Environmental Control, the Suflolk County Water Authority, and the New York State Department of Environmental Conservation UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1977 UNITED STATES DEPARTMENT OF THE INTERIOR THOMAS S. KLEPPE, Serretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Getzen, Rufus T. Analog-model analysis of regional three-dimensional flow in the ground-water reservoir of Long Island, New York (Geological Survey Professional Paper 982) Bibliography: p. 47—49. Supt. of Docs. no.: I 19.162982 1. Groundwater flow~New York (State)—Long Island—Electromechanical analogies. 2. Groundwater flow—New York (State)— Long Island—Data processing. 3. Water, Underground—New YOrk (State)—Long Island—Electromechanical analogies. 4. Water, UndergroundiNew York (State)—Long Island—Data processing. 1. Nassau Co., N. Y. Dept. of Public Works. 11. Title: Analog-model analysis of regional three-dimensional flow in the groundwater reservoir of Long Island. . . II. Series: United States Geological Survey Professional Paper 982. TC176.G48 551.4'9‘0974721 76-608323 For sale by the Superintendent of Documents, U.S. Government Priming Office Washington, DC. 20402 Stock Number 024-001-02936—7 CONTENTS Page Page Abstract ____________________________________________________ 1 Hydrogeology of Long Island—Continued Introduction ________________________________________________ 1 Boundaries between saltwater and fresh ground water ,“1 13 Background ____________________________________________ 1 Water table ____________________________________________ 18 Purpose and scope ______________________________________ 1 Model design ______________________________________________ 19 Previous work __________________________________________ 2 Basic analog concepts and similarity coefficients __________ 19 Location and general physiography of study area __________ 3 Model matrix __________________________________________ 22 Acknowledgments ______________________________________ 3 Boundary conditions ____________________________________ 27 Units of measure ______________________________________ 4 Summary of design criteria ______________________________ 31 Hydrogeology of Long Island ________________________________ 4 Model-prototype comparisons ________________________________ 31 Prominent physiographic features and their role in the hy- Performance criteria ____________________________________ 31 drology of Long Island ________________________________ 6 Steady—state evaluation ________________________________ 32 Geologic features ______________________________________ 6 Unsteady-state evaluation ______________________________ 37 Distribution of hydraulic conductivity and storage coefficient 8 Summary and conclusions __________________________________ 45 Surface water __________________________________________ 11 References cited ____________________________________________ 47 Lakes ______________________________________________ 11 Streams ____________________________________________ 12 ILLUSTRATIONS Page FIGURE 1. Index map of Long Island, N.Y., showing area of investigation ________________________________________________ 3 2. Cross—sectional diagram showing major components of the hydrologic cycle on Long Island ______________________ 4 3. Map showing physiographic features that influence Long Island hydrology ______________________________________ 7 4. Hydrogeologic sections through the Long Island ground-water reservoir and map locating sections _______________ 8 5—12. Map showing: 5. Saturated thickness of the upper glacial aquifer on Long Island ________________________________________ 12 6. Thickness of the Jameco aquifer ______________________________________________________________________ 13 7. Saturated thickness of the Magothy aquifer ____________________________________________________________ 14 8. Confining bed overlying the Magothy aquifer __________________________________________________________ 14 9. Estimated hydraulic conductivity of the upper glacial aquifer __________________________________________ 15 10. Estimated hydraulic conductivity of the Magothy aquifer ______________________________________________ 15 11. Estimated hydraulic conductivity of the J ameco aquifer ________________________________________________ 16 12. Values of specific yield estimated for the water table __________________________________________________ 17 13. Diagram of section across a stream valley ____________________________________________________________________ 17 14. Map showing major Long Island streams ____________________________________________________________________ 18 15. Schematic hydrologic section of seaward boundary of fresh ground water ________________________________________ 18 16. Diagram showing finite-difference representation and notation of hydrologic section through the Long Island ground-water reservoir __________________________________________________________________________________ 21 17. Map View of finite-difference grid ____________________________________________________________________________ 23 18—22. Map showing distribution of transmissivity about each node in: 18. Level 1 of the model ________________________________________________________________________________ 24 19. Level 2 of the model ________________________________________________________________________________ 25 20. Level 3 of the model ________________________________________________________________________________ 26 21. Level 4 of the model ________________________________________________________________________________ 26 22. Level 5 of the model ________________________________________________________________________________ 27 23. Map showing distribution of estimated values of (AZ/KB) between nodes in levels 1 and 2 0f the model __________ 27 24. Map showing distribution of estimated values of (Az’/KB) between nodes in levels 2 and 3 of the model __________ 28 25. Map showing distribution of estimated values of (Az’/KB) between nodes in levels 3 and 4 and 4 and 5 of the model _-,_ 28 26. Schematic representation of method for producing transient analog stresses ____________________________________ 30 27. Circuit diagram of model stream (A) and prototype stream channel (B) ________________________________________ 31 28. Map showing distribution of prototype mean annual precipitation, 1951—65, and of steady-state recharge to the model __________________________________________________________________________________________________ 32 29. Profiles showing simulated, steady-state, water table on western Long Island compared with 1903 prototype water- table profiles and map locating profiles __________________________________________________________________ 33 ill IV FIGURE TABLE Bacon»- Omh>>3>h> cm cm‘1 cm/s cm/d coul E ft ft/d ft3/s (gal/d)/ft2 R aaagaaNe car“ E N N aasaa b CONTENTS Page 30. Map showing comparison of steady-state model water table with 1903 water table in central Long Island ________ 34 31. Map showing comparison of steady-state model water table with 1970 water table in eastern Long Island ________ 34 32. Map showing comparison of steady-state model head with 1971 prototype head at base of Magothy aquifer in eastern Long Island ____________________________________________________________________________________________ 35 33. Distribution of head and bed-parallel components of ground-water flow along two hydrologic sections through the model Long Island ground-water reservoir ________________________________________________________________ 36 34. Graph of changes in annual recharge used to simulate the 1962-66 drought on Long Island ______________________ 37 35. Map showing distribution of the decline in net recharge used to simulate the 1962—66 drought on Long Island _._1 38 36. Map showing comparison of observed and simulated water-table declines as a result of the 1962—66 drought ______ 38 37. Graph of estimated islandwide changes in pumping, manmade recharge, and net stress between 1903 and 1963 __ 44 38. Map showing comparison of simulated decline in water table between 1903 and 1961 on western Long Island with observed decline _________________________________________________________________________________________ 45 39. Map showing simulated decline in water table due to pumping on western Long Island between 1903 and 1942 __ 46 40. Map showing locations of wells used for water level changes in table 4 ________________________________________ 47 TABLES Page 1. Hydrogeologic units of Long Island __________________________________________________________________________ 11 2. Streamflow comparisons ____________________________________________________________________________________ 37 3. Net recharge (positive) and withdrawal (negative) at each model node used to simulate manmade historical stresses between 1903 and 1963 __________________________________________________________________________________ 39 4- Comparison of model and prototype water-level changes for selected wells between 1951 and 1963 ________________ 47 SYMBOLS AND ABBREVIATIONS [Basic physical dimensions given in parentheses] K 3 minimum principal hydraulic conductivity (length! similarity coefficients for relating hydrologic quan- time) tities to their electronic counterparts m metres (length) m3/s cubic metres per second—volumetric discharge amperes (length3/time) capacitance (coulombs/volt) mA milliamperes (10‘a Xcoulombs/sec) centimetres (length) Mgal/d million gallons per day (length3/time) reciprocal centimetres (1/length) (Mgal/d)/mi2 million gallons per day per square mile—volumetric centimetres per second—Darcy velocity (length/time) recharge rate (length/time) centimetres per day (length/time) pf picofarads (10'12Xc0ulombs/volt) coulombs Q volumetric discharge rate (length3/time) electromotive potential (volts) q electric charge (coulombs) feet (length) qx feet per day (length/time) qy components of Darcy velocity (length/time) cubic feet per second (length3/time) qZ gallons per day per square foot (= 1 Meinzer Unit; unit R resistance (ohms) gradient and prevailing ground-water temperature SS specific storage; storage per unit volume (l/length) presumed) Sy specific yield (dimensionless) head, ground-water potential (length) 5 second (time) electric current (coulombs/time) T transmissivity (length2/time) hydraulic conductivity (length/time) t time hydraulic conductivity in x, y, 2 directions, respec- t’ model time (as opposed to real time) tively; gradient and discharge are assumed to be V volume (length3) measured in same direction (length/time) x hydraulic conductivity in various directions; first y dimensions in arbitrary directions (length) subscript denotes direction of discharge, second 2 subscript direction of gradient. K is a symmetric x’ tensor, so no change in quantity results from re- y' dimensions corresponding to principal conductivities versing subscript (length/time) 2’ A finite-difference operator, A7c=x1 —x0 maximum principal hydraulic conductivity (length/ time) CONTENTS CONVERSION TABLE [The followingconversions are given to four significant digits. Equivalent metric and English units in the text, however, have the same relative accuracy] Metric centimetres (cm) centimetres (cm) centimetres per second (cm/s) centimetres per second (cm/s) centimetres per year (cm/yr) Multiply by 3.937><10‘1 3.281 X 10" 2.835>< 10‘3 2.223X 104 1.868>< 10'2 English inches (in.) feet (ft) feet per day (ft/d) gallons per day per square feet [(gal/d)/ft2] million gallons per day per square mile [(Mgal/d)/mi2] Metric cubic metres per second (m3/s) cubic metres per second (m3/s) kilometres (km) metres (in) square kilometres (km2) square metres (m2) metres per kilometre (m/km) Multiply by 3.531 X 10 2.282X10 6.214X 10'1 3.281 3.861 X 10'1 1.076>< 10 5.280 English cubic feet per second (ft3/s) million gallons per day (Mgal/d) miles (mi) feet (ft) square miles (mi?) square feet (ftz) feet per mile (ft/mi) ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW IN THE GROUND-WATER RESERVOIR OF LONG ISLAND, NEW YORK By RUFUS T. GETZEN ABSTRACT A three-dimensional analog model of the ground-water system be- neath Long Island, N.Y., provides a practical means for studying anisotropic flow on a regional scale. Constructional and operational techniques influence the simulation almost as much as model design does. Usefulness and accuracy of the model depend on (1) inherent and practical limitations of the finite-difference method, (2) accuracy and completeness of the data base, and (3) accuracy of the assump- tions and approximations that were made in applying the simulation technique to this particular ground-water reservoir. Reliable data used in design of the model are (1) horizontal hy- draulic conductivity and thickness of three major aquifers, (2) extent of confining beds, (3) specific yield, and (4) locations of streams. Es- timates of vertical hydraulic conductivity and specific storage were applied to the model. Most spatially fixed model boundaries are good representations of prototype (real-world) boundaries. Most dynamic boundaries are only approximately represented, and some dynamic boundaries require application of unproved assumptions. The simu- lated ground-water reservoir generally agrees with prototype hy- drology, and the model is being used for predictive studies. INTRODUCTION BACKGROUND More than one-third of the 7.3 million people on Long Island are wholly dependent on ground water as a source of water, and the remaining two-thirds use some ground water. More significantly, Nassau and Suffolk Counties, which together constitute more than 85 percent of the land area of Long Island, depend en- tirely upon ground water for all their water needs. The populations of Nassau and Suffolk Counties are grow- ing rapidly, and the governing bodies of these counties are already planning for a time in the foreseeable fu- ture when the consumptive-use rate will reach the rate of total recharge to the ground-water reservoir. Use of ground-water resources presents several prob- lems that differ from those encountered in use of surface-water supplies. Most of these problems arise from or can be reduced to three basic conditions: (1) The properties of ground—water reservoirs, or aquifers, are fundamentally geologic and their investigation proceeds with great expense, great difficulty, and much guesswork; (2) ground-water reservoirs are intercon- nected over large areas, and seemingly isolated human activities and natural events can influence water quantity and quality over Wide areas; (3) ground water moves at such slow rates that movement from the point of recharge to the point where the water is ulti- mately discharged typically requires decades or cen- turies, and direct observation of this movement is usu- ally impossible. One of the most powerful tools available to the ground-water hydrologist for predicting the behavior of large, complex aquifer systems such as the one on Long Island is a model—a mathematical or physical- mathematical technique for simulating the physics of ground-water flow. Such models require much simpli- fication of the geometry and properties of the aquifers. The most frequent simplification is that the aquifer material is isotropic; that is, its hydraulic conductivity is the same in all directions at any given point. This simplification is seldom even approximately correct (Hubbert, 1940, p. 826), but because of flow geometry, it is commonly assumed to have little adverse effect on the accuracy of flow predictions. The present study, investigating ground-water flow on Long Island, indicates that the anisotropy of the aquifers is a major factor controlling the effects of ground-water development and that these effects must be considered in managing Long Island’s water re- sources. One of the principal goals of this report is to provide a physically sound practical basis for analyz- ing anisotropic flow on a regional scale. PURPOSE AND SCOPE This report discusses design, construction, and oper- ation of a three-dimensional electrical analog model of the ground-water system beneath Long Island, N.Y. Because the streams of Long Island are important as boundaries within the aquifer system, some aspects of stream hydrology are also represented by this model, but the design of the model limits its major uses to predicting regional or general changes in ground- water head or flow. This report describes sources and types of data used in designing the model, some of the 1 2 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK basic concepts and assumptions that underlie its oper- ation, calibration of the model in terms of historical hydrologic data, probable sources of inaccuracy in its results, and certain conclusions on the behavior of anisotropic aquifers. A prime use of the model will be to anticipate the response of the flow system to various expected and proposed stresses. These stresses can take the form of pumping or recharge through wells, streams, or basins. A model of this type cannot be used for water-quality predictions, although crude estimates and general trends in water quality can be derived from hydrologic information gained from the model. Several of the proposed water-management schemes have been mod- eled; results of some of this modeling are the subject of additional reports in this series of publications. PREVIOUS WORK Previous research, on which this study is dependent, is of two types: (a) Development of theory and techniques for analysis of ground-water flow; and (b) studies of Long Island’s water resources, which have provided (1) information on the geologic background, (2) hydrologic data, and (3) general understanding of the hydrologic situation on Long Island. The geology of Long Island has been studied exten- sively since the mid-nineteenth century, and a massive literature has accumulated. Some of the more impor- tant early papers are those by Mather (1843), Upham (1879), Dana (1890), Hollick (1893, 1894), Woodworth (1901), and Salisbury (1902). DeVarona (1896) and Freeman (1900) studied the water resources of the western part of Long Island. The report by Veatch, Slichter, Bowman, Crosby, and Horton (1906) is a com- prehensive study of the geology and the water re- sources of the entire island but does not include quan- titative data on the hydrologic properties of the ground-water reservoir. Few quantitative data on aquifer properties were available before 1950, but some controlled pumping tests were made by C. E. Jacob, J. G. Ferris, W. V. Swarzenski, M. A. Warren, and N. J. Lusczynski at various times between 1935 and 1950 (Jacob, 1939, 1941, 1945; McClymonds and Franke, 1972) and yielded data of varying quality and quantity. McClymonds and Franke (1972), working with litho- logic logs and acceptance tests from about 1,300 wells, compiled estimates of the transmissivity and the bed— parallel hydraulic conductivity for the major aquifers of Long Island. These estimates have been used in the current study. Geologic and hydrogeologic features of Long Island have been described in comprehensive reports by other authors since the 1906 report by Veatch, Slichter, Bowman, Crosby, and Horton (Fuller, 1914; Suter and others, 1949). Detailed geology of smaller areas is de- scribed in reports by Isbister (1966), Lubke (1964), Perlmutter and Geraghty (1963), Pluhowski and Kan- trowitz (1964), Swarzenski (1963), Soren (1971), and Jensen and Soren (1974). The present investigation is not the first US. Geological Survey study of Long Island’s water re- sources to use analog modeling techniques, but with some exceptions, the previous studies were not pub- lished, largely because of inadequacies or inaccuracies in the models. In October 1964, plans were begun for constructing an analog model of Long Island’s aquifers. These plans resulted in the construction of a two—layer regional flow model of the western half of Long Island. Attempts to verify this model against historical and synthetic data produced inconsistent results. Ex- perimentation over a period of 2 years with this model failed to bring it into tolerable agreement with all known aspects of Long Island’s hydrology. This model indicated that a two-layered concept was inadequate for describing the ground-water flow system beneath Long Island. Part of the difficulty in obtaining an adequate representation of the hydrologic system was insufficient data on the confining beds that overlie parts of the Magothy aquifer. In 1966, a steady-state axisymmetric analog of flow to a single well was used in the interpretation of pump- ing tests at Bay Park, Long Island. Experimentation with cross-sectional models of the aquifer system was begun in 1968. Results from a model of this type were used by Franke and Cohen (1972) to compute regional rates of ground-water movement. Additional cross- sectional modeling‘was done by Franke and Getzen (1975). A series of modeling experiments, in which the vertical and the horizontal conductivities of aquifers and confining beds, rates of recharge, and other hydro- logic parameters were varied systematically, demon- strated the importance of anisotropy in controlling re- gional ground-water flow on Long Island. Some of the results of this series of experiments serve as basic starting points for the design of the three-dimensional model discussed in this report. In 1971, work was begun on the model that is the subject of the present report. Construction of the model was completed in less than 4 months, but testing and modification of the model were not completed until early 1974. This analog model represents three- dimensional regional flow in the ground-water reser- vior on Long Island. The digital modeling techniques that were available at the time this model was begun could not supply the needed accuracy and resolution when used on computers of the size commonly avail- INTRODUCTION able. Existing analog techniques could be easily adapted to simulate three-dimensional, anisotropic flow; because development of an adequate digital model would require much experimentation, the au- thor chose the analog approach. Two Long Island modeling studies that were not done by the Geological Survey were (a) a cross- sectional Hele-Shaw model (Wilson, 1970) and (b) a single—aquifer digital model of the southeastern part of Long Island (Fetter, 1971). The Hele-Shaw model is sophisticated in concept and design and uses composite anisotropic permeabilities (Collins and others, 1972; Collins and Gelhar, 1970). LOCATION AND GENERAL PHYSIOGRAPHY OF STUDY AREA Long Island is bounded on the north by Long Island Sound, on the east and south by the Atlantic Ocean, and on the west by New York Bay and the East River (fig. 1). The island parallels the New York and Connec- ticut coasts for about 190 kilometres (120 miles) and has an area of about 3,600 square kilometres (1,400 square miles), including several smaller islands that are within the same political boundaries. The eastern end of Long Island is divided into two narrow forks by the Peconic Bay, and the southern edge of the island is fringed with an almost continuous line of barrier beaches. The forks and barrier beaches are not in— cluded in the primary study area shown in figure 1. 3 Data from the barrier beaches were used in designing and testing the model, but no predictive capability was developed for these areas. The area of the two forks (east of Shinnecock Canal and Mattituck Creek) was not used. The island is divided into four counties, two of which (Kings and Queens Counties) are within the political boundaries of New York City. Kings, Queens, Nassau, and Suffolk Counties have areas of 202, 298, 754, and 2,390 square kilometres (78, 115, 291, and 923 square miles), respectively. ACKNOWLEDGMENTS Parts of this report were included in the author’s Ph.D dissertation, Department of Geology, University of Illinois. Publication rights have been given to the Geological Survey. Prof. O. L. Franke of City College, New York City University, assisted the author in gathering the data for this report. Prof. Franke also examined the report for technical accuracy. Mr. D. E. Vaupel provided unpublished stream data. He and several of his assistants provided qualitative and quantitative information about Long Island streams, both orally and written, on several occasions during 1971—73. Laboratory assistants B. H. Cohen, M. E. Eskenazi, Daniel Gillen, Natale Guadagnino, and R. F. Lingner built the model; they and A. W. Harbaugh and Donald 74 73° 72 I i WU Wl \ ' r \ \ / ’ _ / ) CONNECTICUT D / ‘ ‘ SoUN f \\ NEW YORK ISLAND ORIENT POINT \ \ \’ L0N % MONTAUK \ \ \ \ Mattituck Creek 410 _ , OIN‘_I'__ 0 ’ / 6i .5 1 <2, NEW JERSEY a: ,>/ ecofl" k t g9 ,/ SUFFOLK .2? we? I ‘COUN’I‘Y SHINNECOCK CANAL q? NASSAU EXPLANATION COUNTY I QUEENS m Project area COUNTY 94’ Seward extension 99 of model 4900 \ o o 5 1o 15 20 25 MILES New - " ' _ York Bay TLANTIC OCEAN o 15 30 Kl LOMETRES - ’ ’ I I | Base from US. Geological Survey, 1:250,000 series: Scranton, Hartford, 1962; New York, 1957; Newark, Providence, 1947 FIGURE 1,—Long Island, N.Y., showing area of investigation. 4 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK Hockheiser assisted in testing and modifying the model. UNITS OF MEASURE Metric units were used in this study, but not for field data and not until after most of the model design and construction were completed. Metric units have been given preference in the text, but some illustrations, adapted from other sources, could not be easily mod- ified and are reproduced here in their original units. Where these illustrations are referred to in the text, the original units in the illustrations are mentioned first. This inconsistency seems unavoidable. HYDROGEOLOGY OF LONG ISLAND The hydrologic cycle on Long Island, as in most places, tends towards a state of dynamic equilibrium. That is, the naturally occurring outputs of water tend to balance the inputs, and the pattern of flow remains fairly constant over long periods of time. The sun pro- ® Vides the energy to maintain the hydrologic cycle by evaporating water at low altitudes and releasing it at higher altitudes in the form of precipitation. Precipita- tion is indicated by (A) in figure 2, which outlines the major components of the hydrologic cycle; evaporation is shown by (B). Rates of evaporation are greatest where bodies of surface water are directly exposed to sun and wind, but some evaporation occurs across the entire surface of the island. Some of the precipitation occurs over bodies of sur- face water or Within such a short distance from them that the water reaches these surface-water bodies without infiltrating the soil. Such direct runoff ac- counts for a small percentage of the total precipitation on Long Island, and, except in areas with storm sewers, is an infrequent event. Water is also transpired to the atmosphere by plants (C). On Long Island, the sum of the quantities of tran- spiration and evaporation is almost always less than precipitation. Net natural recharge to the ground- NOT TO SCALE FIGURE 2.—Major components of the hydrologic cycle on Long Island: (A) precipitation, (B) evaporation, (C) transpiration, (D) unsatu- rated ground-water flow, (E) surface seepage, (F) salty water, (G) saturated ground-water flow, (H) glacial aquifer, (I) Magothy aquifer, (J) Lloyd aquifer, (K) dispersion into salty ground water, (L) deep pumpage returned to surface, and (M) deep pumpage returned to salty water. Arrows show inferred direction of water movement. _ HYDROGEOLOGY OF LONG ISLAND 5 water reservoir is the difference between precipitation and the sum of evaporation and direct runoff. The ground-water reservoir is that part of Long Island’s rocks and sediments that is saturated with freshwater (G), but recharge does not usually enter this saturated zone without first passing through an unsaturated zone (D) in which the interstices (openings between sedimentary particles) are only partly filled with liquid water. Part of the interstitial volume is occupied by water vapor and other gases. The ground—water reser- voir is separated from the unsaturated zone by the water table—a surface along which the interstitial pressure is equal to atmospheric pressure. The top part of the reservoir (H), the glacial aquifer, is a water-table aquifer; its upper surface is the water table. Some of the water in the water-table aquifer is discharged di— rectly to the surface as springs and as seepage to streams, lakes, and marshes. Collectively, these dis- charge points (E) are known as seeps. The remainder of the water in the water-table aquifer flows into other hydrogeologic units (1 and J). The Magothy aquifer (I) and the Lloyd aquifer (J) are distinguished from the glacial aquifer (H) by differences in lithology and geologic origins, by differences in physical properties, or by the fact that water flows within each aquifer more readily than from one aquifer to another. Water from all three aquifers (H, I, and J) is eventu— ally discharged to salty surface water, either directly or through intervening sediments containing mixed freshwater and salty water (K). This discharge and most other components of the hydrologic cycle are inputs and outputs in relation to the ground-water res- ervoir. These inputs and outputs form the natural stresses and boundary conditions to the reservoir. Flow within the ground—water reservoir is controlled by three factors—driving forces, resistive forces, and changes in storage. A flow system in dynamic equilib- rium maintains a constant flow rate and a flow pattern that does not change with time; hence, there are no changes in storage. Although the Long Island flow sys— tem tends towards dynamic equilibrium, such equilib- rium is not perfectly achieved. There are small, local changes in flow patterns (and in storage) resulting from waves and tides and daily fluctuations in precipi- tation. There are larger changes in flow resulting from climatic changes and human activities; these are dis- cussed later in this section. Driving forces within the reservoir result from differences in the potential energy at different points within the reservoir. Two sources of potential energy are pressure and direct ac- tion of gravity. The sum of the gravitational potential and pressure potential at any point is the ground- water head at that point, and the driving force equals the gradient of head. Both the direction and the mag— nitude of the driving force differ from point to point within the reservoir. On a macroscopic scale (a scale that includes a statistically significant number of in- terstices), the spatial variation in head can be de- scribed by piecewise continuous functions. Resistive forces result from friction between the moving fluid and the surfaces of the sedimentary parti- cles. The forces are described by the term hydraulic conductivity, which includes such factors as density and viscosity of the water and microscopic geometry of the sedimentary fabric. Not only does the geometry of the sedimentary fabric differ from point to point in the reservoir, but the fabric usually has a directional as- pect, so that the hydraulic conductivity perpendicular to bedding at any point is less than the conductivity parallel to bedding. The first characteristic is described as nonhomogeneity, the second as anisotropy; both characteristics are true of the sediments that compose the Long Island ground-water reservoir. The glacial aquifer (H in fig. 2) shows the least nonhomogeneity and the least anisotropy of any Long Island aquifer. At the other extreme, the hydraulic conductivity in the direction of bedding in the Magothy aquifer ranges through an order of magnitude or more along any bedding plane and through several orders of magnitude from top to bottom. The conductivity of the latter aquifer is also significantly lower perpendicular to bedding than it is along the bedding. Very little is known about the hydraulic conductivity of the Lloyd aquifer (J), but very little water flows through this aquifer (Franke and Getzen, 1975). Properties of the water throughout a reservoir are usually assumed to be constant, and differences in hy- draulic conductivity are assumed to be the result of differences in the medium (the sediments); but these assumptions cannot always be made. Salty water has a density different from that of freshwater; hot water is less dense and less viscous than cool water, and water flowing through sanitary landfills may have a viscosity and density quite different from those of the native ground water. Flux (flow per unit area) through any part of the reservoir is equal to the product of the hydraulic gra— dient and the hydraulic conductivity. For isotropic aquifers, direction of flow is directly downgradient; but for anisotropic aquifers, such as those that constitute the Long Island ground—water reservoir, direction of flow may diverge from the direction of the gradient. More than half the natural discharge from the reser- voir is through seepage to streams and marshes. The remainder of the natural discharge is to salty surface water, either directly or through mixing with the salty ground water that surrounds Long Island. The mechanism through which this mixing occurs is poorly 6 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK understood; theoretical models, such as Cooper (1959) and the Gheyben-Herzberg theory (Glover, 1959), do not seem to fit the Long Island situation (Upson, 1966). Beneath the barrier islands along Long Island’s south shore, fresh ground water is found at depths where it should be salty according to both equilibrium models. Two explanations for this have been proposed—( 1) that the salty ground water is not in equilibrium with present-day heads along Long Island’s south shore and that the fresh ground water there is a relic of the is- land’s last glaciation; or (2) that the salty water is in equilibrium with the heads but that the conditions for equilibrium are modified by the osmotic effects of clay within the lower part of the reservoir. Neither of these explanations can be wholly proved or disproved. Other possible explanations are that presently observed heads reflect human influences or that Long Island’s climate is significantly drier than it was a few cen- turies ago. However, observed heads in the water-table aquifer indicate little or no change during the past 70 years throughout most of the eastern half of Long Is- land, and there is very little evidence to support the hypothesis of much greater precipitation at any time since the last major glaciation. Human influences on the hydrologic cycle are of three types: (1) Reduction of recharge through paving and storm sewers, (2) removal of water from deeper aquifers through wells and recharge to the water-table aquifer through cesspools and basins, and (3) removal of ground water through wells and discharge to the ocean through sewers. These last two are shown as new components to the hydrologic cycle (L and M, fig. 2). All three human influences result in immediate changes in the amount of ground water in storage, followed by spreading changes in head and flow patterns as the system seeks a new equilibrium. All three human in- fluences were active in Kings and western Queens Counties from the mid-nineteenth century until the early 1940’s. The flow system responded to this stress by (1) reduced heads, (2) reduced streamflow, and (3) intrusion of salty water into the more highly conduc- tive parts of the reservoir. Human influences of all three types have been active in Queens and Nassau Counties since the 1940’s, and the system has re- sponded by (1) reduced heads and (2) reduced stream- flow. Seepage to the bottoms of the surrounding salt- water bodies has been reduced somewhat, but to date (1975) little saltwater intrusion has been observed. Human influences in Suffolk County have generally been limited to removal of water from deep aquifers and recharge to the water-table aquifer. The only ob- served response has been a decline of head at depth in the western one-third of Suffolk County. Human activities have also affected quality of ground water on Long Island. Cesspool effluent, in- dustrial wastes, road salt, contaminated runoff from highways and parking lots, decomposing wastes in sanitary landfills, chemical fertilizers and pesticides, animal feces, and leaking sewer mains have all de- graded the quality of recharge water. Large parts of the ground-water reservoir now contain water of less than desirable quality. The glacial aquifer is affected over most of the western half of the island and the Magothy aquifer in the west-central part of the island where the movement of ground water is predominantly in a downward or down-and-lateral direction. Pumping from the lower part of the Magothy aquifer is ac- celerating the downward movement of the contami- nated recharge water. This study, although it analyzes movement of ground water, does not attempt to explain or predict changes in water chemistry. PROMINENT PHYSIOGRAPHIC FEATURES AND THEIR ROLE IN THE HYDROLOGY OF LONG ISLAND The physiographic features of Long Island are a re- sult of its geologic history; there is a conspicuous geo- graphic relationship between many of these features and the hydrologic features of Long Island, not only because of their role in determining the gross geometry of the flow system but also because of the close connec- tion between the topographic features and the underly- ing geology. The most prominent physiographic fea- tures are related to Pleistocene glaciation. These are (1) the east-west trending hills in the northern and central parts of the island and their eastward exten- sions, which form the north and south forks, (2) the gently sloping plain that extends southward from the hills, and (3) the deeply eroded headlands along the north shore. Other important features are the barrier beaches along the south shore, the shoreline, and the major streams. The Harbor Hill Moraine, which forms the northern line of east-west trending hills, extends from Kings County to Orient Point on the north fork (fig. 3). The southern line of hills, which make up the Ronkonkoma Moraine, extends from northwestern Nassau County eastward to Montauk Point. These moraines were de- posited near the southern terminus of glacial ice sheets and have an altitude ranging from 70 to 90 m (210 to 270 ft) in most places. GEOLOGIC FEATURES The consolidated bedrock that underlies Long Island in overlain by a wedge-shaped body of unconsolidated sediments (fig. 4). The bedrock is at or near land sur- HYDROGEOLOGY OF LONG ISLAND 7 74 73° 72° I? l\ w / \ \ —/’ —/— ) CONNECTICUT ’ ‘ / NEWYORK / ISLAND W0 RIENTPOINT )2? MONTAUK is», N 41° “& x6?” O'INT / SH/NNECOCK CANAL 5 LONG ISLAND Outwash \plain ., 32/ ' / BaY/ area. .Egut/ Do »u ’../ ,f lajfi‘- 1:? '9’ 0 51015 20 25M|LES New -— , YorkBay ATLANTIC OCEAN o 15 30 KILOMETFIES n - r' I I I Base from US. Geological Survey, l:250,000 series: Scranton, Hartford, 1962; New York, 1957; Newark, Providence, 1947 FIGURE 3.—Physiographic features that influence Long Island hydrology. face in the northwestern part of Long Island and has a regional southeastward slope of about 0.7 degrees (about 12 m/km or 63 ft/mi). The bedrock has an ex- tremely low hydraulic conductivity (not measured); the contact between it and the Cretaceous sediments can be considered to be the lower boundary of the ground- water flow system. The Cretaceous sediments and overlying deposits that are saturated with fresh, mov- ing ground water constitute the ground—water reser- voir. Pertinent information on the reservoir rocks is sum— marized in table 1. Figures 4—8 show what was known of the gross geometry of the reservoir rocks at the time the three-dimensional model was constructed (1971). These illustrations are regional, hydrogeological in- terpretations used in the current study. Additional geologic data were acquired after the study began; im- proper model performance suggested some discrepan- cies in the geologic data before the new data were ac- quired. Other recently acquired geologic data are in- significant to the regional hydrology but would have to be considered in hydrologic analyses of small areas. The lowermost aquifer, the Lloyd, directly overlies the bedrock. The Lloyd consists mainly of gravelly sand with lenses of silty sand and clay. Seepage into the Lloyd aquifer is limited by the overlying Raritan clay, which has a fairly uniform thickness of 60—90 m (200—300 ft) and probably has a very low hydraulic conductivity (Franke and Getzen, 1975). The Raritan clay, even though silty and sandy in places, appears dense and well-compacted almost everywhere it has been seen, but it has been seen at only a few widely scattered localities. The Raritan is penetrated by only a few wells and is exposed in only a few places on the north shore of western Long Island. The clay is missing from the sequence in small areas of northwestern Long Island. The Magothy aquifer, which probably includes parts of several poorly defined Cretaceous formations (Perlmutter and Todd, 1965), consists of a series of beds of fine to medium sand interbedded with clay and sandy or silty clay. Several of these beds seem to be fairly extensive, but none, apparently, can be traced for more than a few kilometres. The degree of consoli— dation of the sand beds varies from loose to moderately indurated, and their texture varies from silty to gravelly. Only rarely does the thickness of a single sand bed exceed 15 m (47 ft), but the thickness of some sandy zones that have only a few thin clay beds scat- tered through them are 50 m (160 ft) or more. Thick- ness of the clay beds range from a few millimetres to 20 m (66 ft); in many places, the beds are thicker in the upper part of the sequence than in the lower part. The Magothy aquifer is overlain by several Creta- ceous and post-Cretaceous units of low to very low hy- draulic conductivity. Among these units are silty, sandy clay beds of the Monmouth Group along the south shore of Long Island. The beds thicken seaward. 8 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK Clays of the Monmouth Group are not found on west- ern Long Island. There, the Magothy aquifer is over- lain by the Jameco Gravel, evidently a fluvio-glacial deposit on an erosional surface in the Magothy. A fringe of Pleistocene clay that surrounds the island ex- tends a few kilometres inland along much of the south shore and in several places on the north shore. This fringing clay is almost always referred to as the Gar- diners Clay but may include material of diverse geologic origins (Upson, 1970). Material identified in well logs as Gardiners Clay generally ranges in thick- ness from 2 to 120 m (6 to 400 ft). The areas of the thickest parts of the clay are very small. The clay in the subsurface near the south shore seems to thicken slightly in a seaward direction, but its seaward extent is largely unknown. The upper glacial aquifer consists primarily of sand and gravel, which is glaciofluvial and glaciodeltaic in origin. Even the end-morainal features on much of Long Island seem to be associated with deformed de- posits of stratified drift rather than till (Mills and Wells, 1974). Several tills within and above the stratified drift have been identified in the northern part of the island, and several extensive clays, evi- dently glaciolacustrine in origin, are found within the stratified drift. DISTRIBUTION OF HYDRAULIC CONDUCTIVITY AND STORAGE COEFFICIENT Regional trends in the hydraulic conductivity of the upper glacial and Magothy aquifers on Long Island have been mapped by McClymonds and Franke (1972). These trends, shown in figures 9 and 10, are suffi- ciently accurate for a regional ground-water model, al- though the ground-water reservoir is not completely defined by them. The Jameco aquifer, which is highly conductive, is important in western Long Island. Fig- ure 11 shows the areal extent and estimated hydraulic conductivity of the Jameco aquifer. Although the Jameco aquifer is a distinct geologic unit (Soren, 1971), it is continuous with the Magothy aquifer over much of its area and has been considered in this study as a high-permeability zone at the top of the Magothy aquifer. Several additional but minor hydrogeologic units are also part of the Long Island ground-water reservoir and are lumped here with major units. Estimates of hydraulic conductivity mapped in figures 9—11 are for flow parallel to bedding (bed paral- lel) (McClymonds and Franke, 1972, p. E11). Similar estimates for flow perpendicular to bedding (bed nor- mal) within each aquifer have not been published. Franke and Getzen (1975), in working with steady- state, cross-sectional models, conclude that an 74 l k \ \ ) CONNECTICUT \ NEw YORK / ’ \ \ \\ \\ 41° -— § NEW JERSEY '$ e o 6’ .Q. _ l‘b/ . I A TLAN TIC OCEAN O 1 5 0 5 1O 15 20 25 MILES l—I—l‘l—rl—r_Llfi'l—l 30 KILOMETRES I l Base from US. Geological Survey, l:250,000 series: Scranton, Hartford, 1962; New York, 1957; Newark, Providence, 1947 FIGURE 4.—Locations of and typical sections through the Long Island ground-water reservoir showing major hydrogeologic units. (Geology after Swarzenski, 1963; Isbister, 1966; Jensen and Soren, 1974.) HYDROGEOLOGY OF LONG ISLAND 9 g A' B 3 3' FEET : g 2 L s .2. f. 400 _ 3 o g .E _ g .S. E _ METRES % = 2 a l .= 2 X2 o —100 O 8 W H o > C! I... g 3 <3 E 0 20°“ ‘5 5 5 _ 5 m o —50 I: Water table m 3 SEA _ . _SEA 'ZUpper LEVEL LEVEL glacial aquifer — 50 —100 I; .3/ — 150 ;«::E$EEEZ::5:EE’3:E:£»,’ ’ - “-' Bedrock Egfifiéfih‘ ' “WE' VF — {fr/z,” ’ - 200 — 250 C' D «3 D. 400 1 a: n E — A; E 3 METRES .9" E E 5 S o .5: 11. _ 100 a 3 E a o E x .. '0 E E 8 E E 2 8 E E 200 — g .g 2 — '25 a a: (2 2 _ 50 3 m 0 ~ SEA _ L O _ SEA LEVEL ‘ LEVEL 200 — ' 5° — 100 400 - . — 150 600 ~ — ,, — 200 800 L 250 E :5'17 x? FEET g 3 K 5 400' E. 35 __ a“ 2 m — METRES 5 u = '" 1: 8 — 100 E E S = g is z o- a a s 3—“ 8 'EE ”— 20 5 Ln. 0 w E g g ‘3‘ — 50 m a: 315: SEA W. _____ _ SEA LEVEL _ . LEVEL — 50 — 100 — 150 — 200 am . . . .__ . .. . sz o 5 1o 15 MILES : I I I I I I 41 o 5 1o 15 20 KILOMETRES VERTICAL SCALE GREATLY EXAGGERATED FIGURE 4.——Continued. 10 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK TABLE 1.——Hydrogeologic units of Long Island [From McClymonds and Franke, 1972, p. E5—E6] imate from land (metres) Character of deposits Water-bearing properties Sand, gravel, clay, silt, organic mud, peat, loam, and shells, Colors are gray, brown, green, black, and yel- low. Recent artificial-fill deposits of gravel, sand, clay, and rubbish Permeable sandy beds beneath barrier beaches yield fresh water at shallow depths, brackish to salty water at greater depth. Clay and silt beneath bays retard saltwater encroachment and confine underlying aquifers. Stream floodplain and marsh deposits may yield small quantities of water but are generally clayey or silty and much less permeable than the under- lying upper glacial aquifer. Till (mostly along north shore and in moraines) composed of clay, sand, gravel, and boulders forms Harbor Hill and Ronkonkoma terminal moraines. Outwash deposits (mostly between and south of terminal moraines, but also interlayered with till) consist of quartzose sand, fine to very coarse, and gravel, pebble to boulder sized. Glaciolacustrine de~ posits (mostly in central and eastern Long Island) and marine clay (locally along south shore) consist of silt, clay, and some sand and gravel layers; in- cludes the "20-foot clay” in southern Nassau and Queens Counties. Colors are mainly gray, brown, and yellow; silt and clay locally are grayish green. Contains shells and plant re- mains, generally in finer grained beds; also contains Foraminifera. Contains chlorite, biotite, muscovite, hornblende, olivine, and feldspar as accessory minerals; "20-foot clay” commonly contains glauconite. Till is poorly permeable; commonly causes perched-water bodies and im- pedes downward percolation of water to underlying beds. Outwash deposits are moderately to highly permeable: specific capacities of wells tapping them range from about 10 to more than 200 gal/min per ft (gallons per minute per foot) of drawdown. Good to excellent infiltration characteristics. Glaciolacustrine and marine clay de- posits are mostly poorly permeable but locally have thin, moderately permeable layers of sand and gravel; generally retard downward percola- tion of ground water, Contains fresh- water except near the shore lines. Till and marine deposits locally retard saltwater encroachment. Clay, silt, and few layers of sand and gravel. Colors are grayish green and brown. Contains marine shells, Foraminifera, and lignite; also loc- ally contains glauconite. Altitude of top generally is 5080 feet below mean sea level, Occurs in Kings, Queens, and southern Nassau and Suffolk Counties; similar clay occurs in buried valleys near north shore. Poorly permeable; constitutes confining layer for underlying Jameco aquifer, Locally, sand layers yield small quantities of water. Sand, fine to very coarse, and gravel to large-pebble size; few layers of clay and silt. Gravel is composed of crys- talline and sedimentary rocks. Color is mostly dark brown. Contains chlo- rite, biotite, muscovite, hornblende, and feldspar as accessory minerals. Occurs in Kin 5, Queens, and south- ern Nassau Counties; similar de- posits occur in, buried valleys near north shore. Moderately to highly permeable; con- tains mostly freshwater, but brackish water and water with high iron con- tent occurs locally in southeastern Nassau and southern Queens Coun- ties. Specific capacities of wells in the Jamecc range from about 20 to 150 gal/min per ft of drawdown. Approx- Hydro- maximum geologic thickness System Series Geologic unitl unit (metres) Recent deposits: Artificial fill, salt marsh deposits, stream Holocene alluvium, and shoreline de- Recent 15 posits. deposits Upper Pleistocene deposits Upper 180 glacial aquifer Quaternary Plesitocene Unconformity? Gardiners Clay Gardiners 90 Clay Unconformity? Jameco Gravel Jameco 90 aquifer Unconformity adequate representation of aquifer properties near the center of Long Island must include a substantial de- gree of anisotropy; bed-normal conductivities one- tenth to one-twenty-fourth of bed-parallel conductivity are suggested for the upper glacial aquifer, and bed- normal conductivities one-thirtieth to one-sixtieth of bed-parallel conductivity are suggested for the Magothy aquifer. These ranges of anisotropy are sup- ported by four recent aquifer tests. One test in the Magothy aquifer indicated an anisotropy of 1:30; three in the upper glacial aquifer indicated anisotropy rang- ing from 1:1.8 to 122.8. These tests, however, are incon- clusive and may not be representative of the aquifers. Reliable data for the conductivity of the confining beds (Gardiners Clay and other clays in the deposits of Cretaceous-Quaternary age that overlie the Magothy aquifer) are not available. A vertical conductivity of 2.5x 10‘5 cm/s (0.07 ft/d), characteristic of similar clay beds in Connecticut and Maryland, is reasonable for these units. Subsequent sensitivity tests conducted on the cross-sectional models of Long Island (Franke and Getzen, 1975) indicate that this estimate may be about one order of magnitude too high but that relative to the other parameters tested regional flow is insensitive to the conductivity of these beds. On a regional scale, horizontal flow in the confining beds is probably neg- ligible. Field data for storage coefficients of Long Island aquifers are meagre. The few data that are available indicate that the specific yield of the unconfined HYDROGEOLOGY OF LONG ISLAND TABLE 1.—Hydrogeologic units of Long I sland—Continued 11 Approxv Depth imate from land Hydro- maximum surface geologic thickness to top System Series Geologic unitl unit (metres) (metres) Character of deposits Water-bearing properties (Commonly 90 0—35 Gravel, fine to coarse, and lenses of Highly permeable, but occurs mostly Tertiary (7’ Pliocene(?) Mannetto Gravel included sand; scattered clay lenses. Colors are above water table. Excellent infiltra- with upper white, yellow, and brown. Occurs tion characteristics. glacial only near Nassau-Suffolk County aquifer.) border near center of island. Unconformity Sand, fine to medium, clayey in part; Most layers are poorly to moderately interbedded with lenses and layers of permeable; some are highly per- coarse sand and sandy and solid clay. meable locally. Specific capacities of Gravel is common in basal 5&200 wells in the Magothy generally range feet. Sand and gravel are quartzose. from 1 to about 30 gal/min per ft of Lignite, pyrite, and iron oxide concre- drawdown, rarely are as much as 80 tions are common; contains musco- gal/min per ft of drawdown. Water is vite, magnetite, rutilé, and garnet as ulnconhfined in fiupplervrvnost parts; 7 340 0430 accessory minerals. olors are gray, e sew ere is con ne . ater is gen- Igifilgmhl Mifiifil}; white, red, brown, and yellow. erally of excellent quality but has high iron content locally along north and south shoresr Constitutes princi- pal aquifer for public-supply wells in western Long Island except Kings County, where it is mostly absent. Has been invaded by salty ground water locally in southwestern Nassau and southern Queens Counties and in small areas along north shore. Unconformity Cretaceous Upper Clay, solid and silty; few lenses and Poorlyto very poorlypermeable;consti- Cretaceous , layers of sand; little gravel. Lignite tutes confining layer for underlying Clay Member Raritan Clay 90 20-460 and pyrite are common, Colors are Lloyd aquifer. Very few wells produce gray, red, and white, commonly var~ appreciable water from these de» iegated. posits. Sand, fine to coarse, and gravel, com- Poorly to moderately permeable. . monly with clayey matrix; some Specific capacities of wells in the Raritan lenses and layers of solid and silty Lloyd generally range from 1 to about Formation clay; locally contains thin lignite 25 gal/min perftofdrawdown,rarely layers and iron concretions. Locally are as much as 50 gal/min per ft of Llo d Sand Lloyd has gradational contact with over- drawdown. Water is confined under My mber a uifer 150 60—550 lying Raritan clay. Sand and most of artesian pressure by overlying Rari- e q gravel are quartzose. Colors are yel» tan clay; generally of excellent qual- low, gray, and white: clay is red loc- ity but locally has high iron content. ally. Has been invaded by salty ground water locally in necks near north shore, where aquifer is mostly shal- low and overlying clay is discontinu- ous, Called "deep confined aquifer" in some earlier reports. Unconformity Crystalline metamorphic and igneous Poorly permeable to virtually imper- rocks; muscovite-blotite schist, meable; constitutes virtually the gneiss, and granite. A soft, clayey lower boundary of ground-water res- zone of weathered bedrock locally is ervoir. Some hard, freshwater is con- Precambrian Bedrock Bedrock 0—820 more than 100 feetrthick. tained in joints and fractures but is impractical to develop at most places; however, a few wells near the western edges of Queens and Kings Counties obtain water from the bedrock. INames are those used in reports by the Geological Survey. . _ 2The use of the term "Magothy(?l Formation” has been abandoned. The post-Raritan. Cretaceous deposits are div1ded into the Magothy Formation and Matawan Group undiffer- entiated and the Monmouth Group undifferentiated. aquifer north of the Harbor Hill terminal moraine is generally less than it is in the outwash plain south of the moraine (unpublished data in Geological Survey files). A specific yield (water-table storage coefficient) of 0.10 was estimated for the area north of the line shown in figure 12 and a coefficient of 0.18, south of this line. Water-table storage coefficients were as- sumed for the upper glacial aquifer throughout most of Long Island. In two small areas in the north-central part of the island, the top of the saturated zone is below the glacial deposits and the top of the Magothy aquifer is unconfined with a storage coefficient of 0.10. These specific yields are minimal for sediments with a poros- ity of 25—30 percent. A minimal value of 2X10”8 cm’1 (6X 10'7 ft'l) for compressive storage was also assumed. These estimates were based on a general appraisal of the lithology; subsequent aquifer tests tend to corrobo- rate these values. SURFACE WATER LAKES As described by Veatch, Slichter, Bowman, Crosby, and Horton (1906), lakes and ponds on Long Island odcur in three different hydrologic environments. Lake Success is an example of a perched lake. This type of lake is separated from the main water table by nearly impervious strata and is common on the ground- morainal deposits that form the more elevated parts of 12 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK ATLANTIC 5 10 15 2O 25 MILES I I l | l 0 I I | I I l O 15 20 25KILOMETRES I 5 10 EXPLANATION 60 Line of equal thickness of saturated ma- terial, October 1965 Intervals, 30 and 60 metres (100 and 200 feet) Unsaturated area Base from US. Geological Survey, 1:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 5.—Saturated thickness of the upper glacial aquifer on Long Island. the island. These lakes do not influence, nor, for the most part, are they influenced by the main water table. A second type of lake, one that is dependent on the regional water table, is much more abundant on east— ern Long Island. Lake Ronkonkoma is the largest lake of this type, but Artist Lake, Long Pond, Deer Pond, Swan Pond, Great Pond, Big Fresh Pond, and Form— bogue Pond are other examples (Veatch and others, 1906, p. 63). Water is exchanged more or less freely between this type of lake and the ground-water reser- voir, and when water is pumped from a lake of this type or evaporates from its surface, the lake becomes a ground-water sink; it is a large “natural well.” Both types of lakes are unimportant to the regional ground-water system. Dammed streams constitute a third class of lakes (fig. 13). Depending on whether the water level in such lakes is maintained above or below the surrounding ground-water table, such lakes can function as either ground-water sources or sinks of a local nature. Figure 13 shows that dammed streams retard the seepage of ground water into the streams along the lakeshore. The basic effect of these lakes on the ground-water reservoir is to modify the regional gradients in their Vicinities—decreasing the shorewards gradients in the areas above the dams and increasing gradients below the dams. Such a lake causes a reversal in the water table slope adjacent to the stream, which prevents ground-water seepage into the stream, but the effect on both streamflow and the water table is small a short (After McClymonds and Franke, 1972, pl. 1.) distance upstream or downstream of the lake. In the regional analysis, each lake of this type is treated as a stream reach with little or no ground-water seepage. STREAMS The Nissequogue River, which has the highest aver- age flow of any Long Island stream, had an average discharge of 1.18 m3/s (40.3 ft3/s) between 1943 and 1970 (US. Geological Survey, 1972, p. 37). There are four other major streams with discharges greater than 0.5 m3/s (17 fi3/s)—Peconic, Carmans, Connetquot, and Carlls Rivers. Most of the larger streams and all those with an average discharge greater than 0.3 m3/s (10 ft3/s), except the Nissequogue and Peconic Rivers, discharge along the south shore. Except for a few in the western part of the island, the streams of Long Island receive most of their flow from ground—water seepage (Cohen and others, 1968, p. 62). Seventy-five of these streams (fig. 14) are large enough so that each affects the water table and patterns of flow within the ground-water reservoir over an area greater than 2 kmz; all together, these streams drain more than 13.4 m3/s (300 Mgal/d) from the ground—water res- ervoir. The streams are of interest because of the way in which they are affected by changing ground-water levels and because of their changing rates of seepage from the ground-water reservoir. Even small fluctua- tions in water-table elevation can cause pronounced changes in stream discharge. Changes in stream dis- HYDROGEOLOGY OF LONG ISLAND 13 74000‘ 45' 73°30: ‘ ,‘ EXPLANATION 15 Line of equal thickness Intervals, 15 and 30 metres (50 and 100 feet) afioo‘ O SMILES 0 5 KILOMETRES 45’ Base from . . Geological Survey, 1:250,000 series: New York, 1957; Newark, 1947 FIGURE 6.——Thickness of the J ameco aquifer. (After McClymonds and Franke, 1972, fig. 13). charge are of interest because of (a) recreational uses of streams to wells where pumping of the wells causes a freshwater lakes, (b) the influence of stream discharge slight lowering of the regional water table. on the salinity of the brackish-water bodies surround- ing Long Island and the resulting effects on shell fish- BOUNDARIES BETWEEN SALTWATER ing and general marsh ecology, and (c) the large AND FRESH GROUND WATER amounts of ground water that are diverted from Fresh ground water comes into contact with both 14 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK 73045: + o ATLANTIC 40 30. 0 5 1O 15 20 25 MILES l I I I I | I I I I | ‘I O 5 10 15 20 25 KILOMETRES EXPLANATION 270 Line of equal thickness of saturated material, October 1965 Interval, 30 metres (100 feet) Base from US. Geological Survey, 1:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 7.—Saturated thickness of the Magothy aquifer. (After McClymonds and Franke, 1972, pl. 2.) .V )4?" ,/’/ // aye/@912); 13m” n: ’ 5'» ’.’~' '7‘” '0’ / { )[i/(é‘fgfii W) o, ’o '6. / // " NASSAU 1 COUNTY , I We, //;,.,, , / f . . I/«In ééfifir / M / . // / ; fitfiyy/I’fX/gfléfifl/flffi ~) , /-' u/fly/l/I/ , l W W ATLANTIC + 15 2O 25 MILES I I I | I | | | I 10 15 20 25KILOMETRES l l,’ UFFO W '2/ /7%/% l ’ a , Kg; . , a, : g/V 0M aw! i OCEAN EXPLANATION Contact, dashed where approximately located Confining beds Base from US. Geological Survey, 1:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 8.—Extent of Gardiners Clay and other Cretaceous-Pleistocene deposits that constitute a composite confining bed overlying the Magothy aquifer. (Geology after Perlmutter and Geraghty, salty surface water and salty ground water. The salty surface water surrounding Long Island is a significant boundary to the ground-water reservoir. Any fluctua- tions in head along the bottoms of the surface-water bodies are independent of head Within the ground- 1963 and N. E. McClymonds, written commun., 1970.) water reservoir; the bottom is said to be a specified- potential boundary. Waves and tides fluctuate so rapidly that the fluctuations are usually ignored, and the boundary is treated as one along which the head is constant, or invariant with time and horizontal direc- HYDROGEOLOGY OF LONG ISLAND 15 A TLAN TIC 0 5 10 15 20 25 MILES | | I l I l l I l | O 5 1O 15 20 25KILOMETRES V EXPLANATION OCEAN 1500 - Line of equal hydraulic conductivity Interval, 500 gallons per day per square foot (20 metres per day) Unsaturated area Base from US. Geological Survey, 1:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 9.—Estimated hydraulic conductivity of the upper glacial aquifer. (After McClymonds and Franke, 1972, pl. 1.) 73°45: .. + 40 ATLANTIC 30' + 5 1 O 1 5 20 25 MILES | | l | J l | | | I 5 10 15 2O 25KILOMETRES O—u—O SUFFOLK COUNTY OCEAN EXPLANATION ——300 Line of equal hydraulic conductivity Interval, 100 gallons per day per square foot (4 metres per day) Approximate limit of Magothy aquifer Base from US. Geological Survey, l:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 10.—Estimated hydraulic conductivity of the Magothy aquifer. (After McClymonds and Franke, 1972, pl. 2.) tion. Because salty water is more dense than fresh- water, the head along the boundary is a function of saltwater depth. At the bottoms of bays and oceans, freshwater heads at the sediment-water interface must balance the head resulting from the density difference—about 2.5 percent of the surface-water depth if the body is seawater, proportionately less if the surface water is less dense than seawater. The head condition just described must always be met along the boundary between fresh ground water and salty surface water, regardless of whether the system is in equilibrium. The same head condition must be 16 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK 41000, 74 ’no 45' 73°30' EXPLANATION 1500 Line of equal hydraulic conductivity Interval, 500 gallorfs per day per square foot (20 metres per day) Approximate limit of Jameco aquifer 0 SMILES 0 5 KILOMETRES 45' Base from U.S. eo ogical Survey, l:250,000 series: New York, 1957; Newark, 1947 FIGURE 11.—Estimated average hydraulic conductivity of the Jameco aquifer‘ (After McClymonds and Franke, 1972, fig. 14.) met for the boundary between fresh ground water and salty ground water if dynamic equilibrium is to be maintained, if the salty ground water is assumed to be static, and if the only net forces acting on the ground water are head gradients arising from gravitational forces (Hubbert, 1940, p. 868—870, 924—926). Figure 15 is a diagram of the seaward boundary of fresh ground-water flow on Long Island showing (A) the surface along which freshwater head must balance the head caused by density differences between fresh- water and saltwater and (B) the surface along which freshwater head seems to balance saltwater heads and HYDROGEOLOGY OF LONG ISLAND 17 ’I/ a + . ATLANTIC 40 3G 0 5 10 15 20 25 MILES l | l I l I l I ' | l l 0 5 1O 15 20 25 KILOMETRES LONG Base from U.S. Geological Survey, 1:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 12.—Values of specific yield estimated for the water table. Former stream surface Sand and gravel FIGURE 13.—Section across a stream valley showing water table be- fore (A—B) and after (A—B’) pond is created by damming a stream. The pond causes a reversal in the water-table slope which prevents ground-water seepage into the stream. (After Veatch and others, 1906.) meets conditions for a classical equilibrium interface as described by Hubbert (1940, p. 868—870); (C) indi— cates that surface along which freshwater head seems not to balance saltwater head and along which condi— tions for a classical equilibrium interface are not met. An earlier discussion (p. 6) indicated that failure of heads along surfaces marked (C) to meet the conditions for a classical equilibrium interface could result from either (1) nonequilibrium conditions or (2) modification of the conditions for equilibrium by osmotic effects of the clays at and below the top of the Magothy aquifer. The difference in density between fresh and salty water tends to keep the two separated with the fresh ground water on top; under steady-state conditions, the interface is represented by limiting flowlines of the fresh and salty water flow systems. A limiting flowline is mathematically equivalent to a no-flow or imperme- able boundary, although there is no physical imperme- able boundary. Fresh or salty ground water can move across the interface through two processes—(a) bulk displacement of one type of fluid by the other or (b) dispersion or mixing of the two fluids. Under nonsteady flow conditions, either process can cause movement of the interface, but the interface would move at velocities several orders of magnitude less than the velocity at which potential transients are transmitted through the confined parts of the ground-water reservoir. Transient changes in head are transmitted across the interface as though the inter- face were nonexistent, but because the interface is generally some distance offshore in the confined aqui— fers of Long Island, head changes at the interface re- sulting from human activities on the island will gener- ally be small. Movement of the interface resulting from onshore pumping would accordingly be slow. Cooper (1959) provides a useful discussion of the physics of saltwater intrusion, and Lusczynski and Swarzenski (1966) describe the occurrence of intrusion on Long Island. Although the preceding conclusion is true for the interface in the confined aquifer along most of the south shore of Long Island, it is not true everywhere. In parts of Kings, Queens, and Nassau Counties, the interface is landward of the shoreline and adjacent to 18 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK BA COUNTY AR BM BS B NASSAU BI BJ BR ' BP COUNTY Ac BT QU ENS ’ AD AH AM N AB KINGS COUNTY Ag G I U V AE AN A As AU COUNTY ) BU :_ c D JK R T AA AG AKAL Q AT 1' ' I BB l SUFFOLK HI s F LMO .1 E PQ , A TLANTIC OCEAN 4O 30. + Note: See table 2 for explanation of let- tering on streams. Some of the 0 5 1° 15 2° 25 MILES streams (mostly in Queens County) | 1 I | | I I I l I *I have been replaced by sewers and are 0 5 1O 15 20 25 Kl LOMETR ES not listed in the table Base from US. Geological Survey, 1:250,000 series: Hartford, 1 9 SOUTH Saline surface water 62; New York, 1957; Newark, 1947 FIGURE 14.—Locations and letter designations used for major Long Island streams. NORTH Water table major pumping centers, the aquifers are thinner and more highly permeable than average for Long Island, and the confining unit is discontinuous; consequently, the interface can move rapidly (locally in excess of 10 m/yr or 33 ft/yr) in response to onshore pumping. GLACIAL AQUIFER WATER TABLE The water table, or free surface, is a boundary to the ground-water reservoir that can move in time. In re- charge areas on Long Island, the flux (rate of flow per area) to the water table generally occurs as unsatu- rated flow and, therefore, is not affected by heads within the reservoir. In discharge areas, the rate at which water leaves the reservoir at the water table is related to heads within the reservoir but is ultimately controlled by evapotranspiration rates. One way of treating the water table is to ignore the how and the why of changes in flux across it and to treat it as a surface across which the flux is entirely controlled by events external to the aquifer except at points where GARDINERS CLAY MAGOTHY AQUI FER RARITAN CLAY FIGURE 15.—Schematic hydrologic section of seaward boundary of fresh ground-water flow on the south shore of Long Island showing (A) the surface along which freshwater head must balance the NOT To SCALE head caused by the density difference between freshwater and salty surface water, (B) the surface along which freshwater head seems to balance saltwater head in the aquifer, and (C) the surface along which freshwater head seems not to balance static saltwater head. LLOYD AQUIFER MODEL DESIGN the water table intersects seeps (streams and springs). At those seeps, flow out of the upper surface of the aquifer is a linear function of the gradient towards the seep; the seep is maintained at a potential defined by its altitude. MODEL DESIGN BASIC ANALOG CONCEPTS AND SIMILARITY COEFFICIENTS The sediments of the Long Island aquifer system are clearly anisotropic in their hydraulic conductivity, which is maximum parallel to the bedding and minimum at right angles to it. They are likewise heterogeneous, with extreme variations in hydraulic conductivity from place to place. The flow of ground water of uniform density and viscosity through a medium of this sort can be described in terms of two equations, as follows: K x. K ., K ,2 ah/ax qx K y, K yy K y, Bh/By = qy (1) [Kat sz K22 (ah/62 (12 and 0a. 6q aq. Ssah ‘ ‘1 + ~ = — ’ (2) 3x 33’ 02 at Where Km KW.) . . ., are the components of the hydraulic conductivity tensor; h represents hydraulic head; qx, qy, and q, are the components of the Darcy velocity, or flow per unit area; It is time; and SS is the specific storage. In this formulation, both the hydraulic conductivity ten- sor and the specific storage are considered functions of position—that is, the medium is considered heterogeneous as well as anisotropic. The coordinate directions, x, y, and z, are chosen arbitrarily. (See, for example, Collins, 1961, p. 63 and 72.) Direct electrical simulation of ' equations 1 and 2 could be accomplished by using complex circuitry; for example, by using certain negative resistance ele- ments. But this would be a difficult and costly proce- dure. A considerable simplification is possible if the medium can be considered orthotropic—that is, having three perpendicular principal axes of conductivity along at least one of which the conductivity attains its maximum value and along at least one of which the conductivity has its minimum value—and if the coor— dinate axes can be taken along these principal axes of conductivity. In the Long Island system, two of the principal axes can be taken parallel to the bedding. In these directions, designated x’ and y’, the hydraulic conductivity has its maximum value, K A. The third principal axis, designated 2’, can be taken at right an- gles to the bedding. In this direction, the conductivity 19 has its minimum value, KB. If the coordinate axes are taken along x', y', and 2’, equations 1 and 2 can be reduced to: 1(1922 + 3. we 6x’ 6x’ By’ By’ + 1 KB ah S,6h 62' az' _ 31: Equation 3, which is easily simulated electrically, accounts for the heterogeneity of the system—that is, variation of K A, KB, and S, with position—but assumes that the directions of maximum and minimum conduc- tivity remain the same throughout the system. This is not strictly true in the Long Island aquifers because the dip of the sediments varies slightly with map loca- tion and with depth. The electrical simulation used in this analysis approximates equation 3 at each indi- vidual point in the aquifer but also partly accounts for variation in direction of the principal axes. In this sense, the simulation represents the ground-water sys- tem more accurately than does equation 3. In the proc- ess, however, additional errors are introduced. The er- rors are described later in this section. Electrical simulation is accomplished by dividing the aquifer into blocks as shown in figure 16. Figure 16A represents a typical hydrologic section through the island; figure 16B illustrates the division of the aquifer into blocks along this section. The two upper- most layers of blocks represent the upper glacial aquifer, and the three lower layers represent the Magothy aquifer. The layers are aligned along the high-conductivity axes; that is, they are parallel to the bedding at all points. Because of the exaggeration of the vertical scale, both the dip of the various layers and the differences in dip between the layers seem to be much greater in figure 16 than they are. All dips are on the order of 1 degree. Figure 160 shows one of the blocks of figure 16B and an array of seven nodal points in the neighborhood of this block. The head at each nodal point is indicated by the subscript notation shown in the figure. The central node lies at the centroid of the block shown in the figure, and the surrounding nodes are assumed to lie at the centroids of the six surrounding blocks. In terms of finite differences in head, the equation for approximate inflow along the x’ axis is (3) h —h , Qxl' 2: KAI (—:x’—)]O- (Ay’AZ )1 , (4) 20 where the subscript 1 indicates that the various terms are taken between node 1 and node 0. The hydraulic conductivity, K A, , is an average value for this interval, as is the flow area (Ay’Az’)1. The symbol (Ax’)1 is sim- ply the distance between node 1 and node 0. Equation 4 can be obtained by applying Darcy’s law to flow through the right face of the block, expressing the de- rivative ~6— by a Taylor series expansion, and neglect- x ing terms of higher order than the first in the resulting series. The equation for approximate outflow along the x' axis is ho‘hz (Ax')2 sz, x K442 (AylAzlh a (5) where subscript 2 indicates values for the interval be- tween node 0 and node 2. Therefore, inflow minus out- flow in the x’ direction is approximately (h1*ho)) (ho—h2)> Similar expressions, using parallel subscript notation, can be developed for inflow minus outflow in the y'and 2' directions. When this is done, the total inflow minus outflow may be equated approximately to the rate of §A1(Ay/AZ')1 _ KA2(Ay’A2’)2 (Ax’)2 (6) accumulation of fluid in storage in the block, SS(AV) 2-? where AV represents the volume of the block. This leads to the equation KA1(AZ/Ay,)1 KA2(AZIA3’I)2 h h) (Ax/)1 l_ 0 (Ax/)2 ( 0 2 KA3(A2’Ax’)3 KA,(A2'Ax’)4 ‘ h _h — E h —h my» ( 3 0) (AM ( ° 4) K 5(Ax’Ay’) K (Ax’A ’) ¥ 025— 0 _ M 0,04%) (Az’)5 (Az’)6 z 830 (Mix + (Ax-[)2 X (Ag/[)3 + (Ay,)4 2 2 (Az’)5 + (A2’)6 6h 2 6_t ' (7) Equation 7 is simplified considerably by making Ax’=Ay’ for all blocks. In this case, ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK KA1 (A291 (h1—ho) ‘ KA2 (A292 010*}12) + KAg (A233 (ks—ho) _ KA4 (A2»; (ho—’14) K35 (Ax’Ay’) (Az’)5 K36 (Ax’Ay’) 0‘54”) _ (Az’)e (ho 4%) , , (AZ')5 + (AZ/)6 3h “SSOAxAy f 3t- (8) Equation 8 may be regarded as a finite-difference (in space) approximation to equation 3, using the block configuration shown in figures 16 and 17 and keeping Ax’=Ay’ throughout. As suggested previously, how- ever, equation 8 simulates conditions in the aquifer (equations 1 and 2) more closely than it simulates equation 3. Equation 3 requires that the principal con- ductivity axes remain fixed throughout the system, whereas in reality they do not. A simulation of field conditions that is superior in certain ways to one that would be given by a direct, finite-difference approxima- tion of equation 3 can be obtained by changing the orientation of the blocks to follow approximately the changing directions of maximum and minimum con- ductivity. Errors associated with a finite-difference approxima- tion using a uniform rectangular mesh have received extensive attention in the literature; for example, Karplus, (1958, p. 103—108). If, as in this example, the mesh is not perfectly rectangular, additional errors are introduced. The increase in A2’ in the downdip direc- tion implies that the downdip flow through a block must diverge, rather than remain entirely parallel to x'; thus, it cannot be completely accounted for by a term approximating only%, In addition, the upper or lower surface of a block may not be perfectly perpen- dicular to a line between the centroid of the block and that of the overlying or underlying block. In this case, flow across the surface cannot be exactly described in terms of a head difference between the centroids. Mag- nitude of the errors generated by these causes is dif- ficult to estimate and would vary from place to place in the system. However, because the dip is very low and the changes in dip are both small and very gradual, errors of this sort would probably be negligi- ble throughout the system. A direct electrical analog of equation 8 is easily con- structed. Karplus and Soroka (1959), Skibitzke (1961), Bermes (1960), and Walton and Prickett (1963) discuss both the theoretical basis and the technique of such electrical simulation. Figure 16D shows an electrical configuration in which six resistors are used to connect a central node, or junction, with six surrounding nodes. MODEL DESIGN ' 2 l A . SOUTH NORTH A A' EET F400 METRES 7 — 100 200‘ ‘ SEA LEVEL — g- — SEA LEVEL ' pper glacial aquifer: 200 " '. .. . . ' )5; .. .. -. ,Zéfi’ésf,» —100 40° — H . . l - -. . A :32” ’1’!” 3561/ __ ' - -*€,§5§f/”::,;;Lé’"y 600 - / $12,339 gagg’ _ - 200 800 — ,gggjcéjéifii’éfiiteffi‘b’lay ‘ 1000 — ’ - — 300 1200 — .. 1400 "' 400 0 5 MILES 0 5 KILOMETRES B Average flow area=(Ay’AZ'), Average flow area=(Ay’Az‘)2 FIGURE 16.—Finite-difference representation and notation of hydrologic section through the Long Island ground-water reservoir (thickness greatly exaggerated): A, A typical hydrologic section. B, This section divided into blocks, or finite-differences. C, Expansion of one block from this section showing the princi- pal conductivity axes, x', y’, and 2'; also head at the centroid of this block, ha, and at the centroids of six surrounding nodes, h1, h2, . . . he. D, An electrical analogy for flow in this block with voltages E0 . . . E6 analogous to heads ho . . . he, resistances R1 . . .RG, and capacitance Co. 22 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK A capacitor connected to the central node provides electrical storage at this point. Voltage at the central node is designated E0, and voltages at the surrounding nodes are designated E1, . . . E6, respectively, which parallels the notation used for heads in equations 4 through 8. The current (11) toward the central node through resistor R1 is given by Ohm’s law as l 1=R—1(E1—Eo), (9) where R1 is the resistance between the central node and node 1. The current (12) from the central node to node 2 is similarly given by 1 12: E2— (E0_E2)- (10) Expressions similar to equations 9 and 10 can be obtained for the currents toward and away from the central node in the other directions. The algebraic sum of these currents must equal the rate of accumulation of charge on the capacitor at the central node, which is . C dE . glven by %‘1 where C represents the capac1tance. This leads to the equation 1 1 1 —(E —E)———E —E +‘E —E R1 1 0 R2( 0 2) 3( 3 0) 1 1 ‘ F4(E0‘E4) + E;(E5—EO) “If __1. _ z 2 R6(E° Es) Codt' (11) Equation 11 is of the same form as 8, where voltage is analogous to head, the terms ]—'. . . —1—are analogous R 1 R 4 to the terms KA1(AZ,)1. . . KA4(A2’)4,the terms R5 and KB5(Ax’Ay’)and K36(Ax’Ay’) (Az')5 (AZ')6 (Az')5+(A2')§ ' 2 R6 are analogous to ,and Co is analogous to SSOAx’Ay’ Thus, if a three-dimensional network of resistors and capacitors is constructed and subjected to electrical stresses that are proportional to hydraulic stresses in the ground-water system, the voltage of each node of the network should vary in proportion to the head in the corresponding block of figure 16B. Equation 11 provides a means by which head changes in response to proposed or assumed stresses can be predicted without resort to extended field experiment. For the uppermost layer of a three-dimensional - analog network, the term K 35 of equation 8 is zero; the termRLof equation 11 is similarly taken as zero. For 5 the lowermost layer, the terms K 36 and Riare zero. If 6 the uppermost layer corresponds to a water-table zone, the capacitance C at each node in this layer is taken to represent the term Sy Ax’Ay’, where 8, represents specific yield, rather than the specific storage term of equation 8; in an interval that includes the water ta- ble, virtually all withdrawal from storage is sustained by dewatering rather than by release from compressive storage. The electrical analogy may be summarized in terms of four similarity coefficients, any three of which may be considered independent. These are as follows: V = A1 ‘1 Q = A3] t = A4 t’, where the quantities left of the equal sign are pro- totype1 (real world) quantities and those on the right are model quantities. V is volume of water, q is electri- cal charge, h is head, E is electrical potential, Q is rate of discharge of water, I is electrical current, t is pro- totype time compared with model time t’; and the coef- ficients Al—A4 have the dimensions necessary for the appropriate conversions. The model study is described in terms of the following units: V (cubic metres) 2.484X 1013(m3/coul)Xq (coulombs) 2.0(m/Volt)>.D. D DDD D D D.D.D.D.D D.- rrrrr D D D D D D D D D D D D D D D D D D D D D D D D D D D r rDr.D.D.DDDvD.D.D+DDD D.D.D.D D.D.DDDDD.D.D.D.D.D.D.D¢DVD., D D D D r D D D D D D D D D D D D D D D D D D D D D D D D D D D , D D DD.D.DVD.D+DDDDD.D.D.D.DDD.D.D.D.D.D.D.DrD.D.D.D.DVD.D.D.D.D.D 7 D r r D D D D D D D D D D D D D D D D D D D D D D D D D D D D D . D . D D o D .- D a D.D.D.D.D.D.D.D.D.D.D.D D D D r r.r r r.r gned storage would have to be modified during cient that was assumed. The author considered that model testing, so one value of capacitor was used Four aquifer tests after the construction of the model indicate a specific storage for these semiconfined aqui- (Getzen, 1974, p. 53), at least one order of magnitude greater than the values used in the model design. Even with the larger values, the effects of elastic storage on with water-table storage for most of the Long Island The large size of the model caused some concern about the effects of stray capacitance on performance of reservoir. Around the fringes of the island, where the sensitivity is one reason to question the model’s predic- throughout. During testing, this assignment of storage fers ranging from 10'7 to 10'6 cm'1 (3 X 10'6 to 3 x 10—5 ft 1) confining unit is thickest and more nearly continuous and where the overlying units are saturated with sea- water, model accuracy is more sensitive to the accu- racy of the assumed value for specific storage. This tive capability in the offshore area. the model. The mechanics of construction require large amounts of wire connecting nodes on each level to the corresponding nodes on the levels above and below, and much of this wire (more than 70,000 ft or 21,000 because of the lack of data to support the storage coeffi- seemed adequate. (uppermost level) of the model. y. he the assi quifer quifer and ; long-term response are insignificant when compared -term re- g Is- pro- two proportional to his was not done «Dart Btav rv[vfieB'EVAVAVn§R¢RVR‘R‘ ‘A’S'ava~s~sv v(¢(9(9(¢(r(‘(9(.9GOGOGOG‘6‘(0(v(~(9(OBQE‘BVBOEVEOQVB : .¢ ((BBF ERRAARRARRRR E ((~((((CC 6666013¢§~ ((rr: rEflhflRRRlAflhl B (((C(((( 665666£rvto[v[s[orvAvonyrupanncnvAcavnoa¢a¢a~avsv ~(e(c(0(¢(v(v(9(9(969606060GOGQFVBOBOB¢B~atseataéavaoseas (frFEEFFflAARRRflAHRRR SB 3 fl¢!tsv5eaeavstsvfivaoatatstaeto(e 9(v(b(¢(v(~(v('('('6v6'696*69V‘rrl’tr'rvaf0(‘[‘rrrt(0[0rf rrrrrzrtreaasaaeaas 88(k (<((<(¢ VCQ{6(9(t(0(fi6‘GOG‘fi'fi‘G'G‘G'G‘G'GOGOGVGOGO6960G'G‘V’r’ (EBBBB((((DDDDDD((C(C((Cl L(((((at-(IGGGGbGGSQGGBEEGfl-(IGGV "B'E‘Boaoascvcv(¢(oDvD‘DtD'DtD‘C‘L’(‘<9('(etz¢1¢>ozom- x 1 z z z \ 1+zsx¢1.:«—+xa,a-.-qn¢m+a+m4 m~n n EXPLANATION ' Modetnode . t Transmissivity=l ,200 square metres per day n Specrfled-potentlal boundary r Transmissivity=1,500 square metres per day I Impermeable boundary (no transmissivity) ‘ Transmissivity=1,700 square metres per day a Transmissivity=370 square metres per day " Transmissivity=3,000 square metres per day 5 Transmissivity=500 square metres per day I Transmissivity=3,700 square metres per day < Transmissivity=930 square metres per day : Transmissivity=5,300 square metres per day a Transmissivity=990 square metres per day n Transmissivity=5,900- square metres per day FIGURE 19.—Distribution of transmissivity (product of thickness and bed-parallel hydraulic conductivity) about each node in level 2 of the model. ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK 26 I I D D D D I D4EeE4E4E4E4E4E D I I D D D D E E E E E E E E4E+ E+E E E E E+ E4: E E E E. E+E E E E E4 E4 E E E 4 E4 E E E4 E E E4 E E E. D E :4 D D 4 D D 4 D D o D D D D D D D D D D 4E4E+E~E+D+D4D4D4D4D4D+D4D4D4D4D4D4D+D+E~E~E4E4E4E4D D +E4E4E4E4D+D4D4D4D4D4D4D4D4D4D4D4D4E4E4E4E+E4E4E4E4D E E E a s E E E E c c c D 4ate4a.<4c4c4c4c+: ”.34 E E E D D E E E D E D D D D D D D D D D D D D D D D D D D D D D D I D D D D D D D D D D D D D D D 4E4E4E4E+E+E4E+E+E¥E+E4E+D4D4D+D4D4D4D4DrDcDeD4DrD4D4D+D E E E E E E E E E E E E E D E4E4E4E4E+E+E+l4E4E454E+E4E4D4D+D4D4D494D4D4DeD+D4D+D D +E+E+E+[*E+ErD+DthDfD+D¢D+D‘D?D*D+D+D+DDD+D+:1E+E+E+n D D D D D D D D D D D D E E E D D D 500 square metres per day 6,300 square metres per day 9,100 square metres per day E E E E D E E E D D ! 1,740 square metres per day 2,200 square metres per day 3,600 square metres per day 15,000 square metres per day S W I 'tY= 'ty= Ivity= ity= 'ty= 'tY= .ty= E E E E E D lSSlVl lSSlVl lSSlVl . iss1v1 issrvr issrv E D E D 4c4ceE4D4D4E4E4E E+r r4r4r4r4rHE Transm a Transmiss Transm , rTransm x Transm Transm E E 4E4E4EvE4E4E4E4E4EcE+E4E4E4D+D4D4DrD+D+D+D+D+D l: 0 U r Transm l L D a EXPLANATION ity (product of thickness and bed-parallel hydraulic conductivity) about each node in level 3 of the model. 310 square metres per day 620 square metres per day 990 square metres per day ISSIV tY tY tY ity=1,550 square metres per day ity=120 square metres per day issiv ivr issivi issiv1 issiv . Model node . Impermeable boundary Transm Transmiss Transm Transm Transm n e E D E FIGURE 20.—Distribution of transm D D D E D D D D D D D 4E4E~E4E4D+D+D4D+D4D4D4D+D4D4D4 D D D D E D D D I D.D 4E4E4E4E4E4E4D4D+D4D+D4D4D+D4D+D4DvD D D D 4D4D4D4DDD4I4D4D4I4D D D D D4D I D 4IoD I D D I 404D. D4 D D D D I 4D.D4 E4I+ I D D E D 404D4 D4I4 D D D D D .D4D4 D404 I D D D D 4040. D4D+ D D D D I D 404D. D4D'D+ E D D D D D.D4 D4D+D4 E D D D OLCr D DID c D D D4E4 D4I E E D D4E4 D.D D E D 4 4 E D + 4 E D + s 4 4 + D D D 4 D 4 E D D 4 4 4 E D D I + 4 4 4 c D D D I c .D4D 4 DD. E D D D D I 4E4D D D.D D4D4 E D D D D .E4D D D4D D4D4 E D D D I 4E.D D D4D D+D4D E D D D D 4E+D E E4E D4D4I E D E E E 4EDD E E4E EvE4D E D E E E 4E4D E E4: E4E4D c D E E E 4C4D E E4E E4E4D E E E E E .E4D E E+E E4E4D E c E n E E 4E+E E ETE+E4E4I E E E E E E 4E.E E E4E4E4E4D c E E E E E E +E4E E+E4E4E+E+D E E E E E E E E4 r+E+E¢E4EsD E r E E 4 r4r4E4E E D r r E r4r4E4E E D r r E r4r4E4E E D r r E r4r4E+E E D r E r4r E.E E D E4E E E E r+E E E E E E D D E 10*0*0*l*O’Cr:‘£*[*£?£r[+[ D D E 4 r E . 4 r E . 4 r E 4 4 r r E 4 4 s r E E E 4 4 4 4 r E E E 4 + 4 4 r E E E 4E4E4 . 4 D E E E E E «E4E4EDD4 E E E E D 4E4E4D4D+I E D D D D mD4D4DeD4D D D D D D 4D4D+D4D4D D D D D D 4D+D4D4D4D D D D D I 4D4D4D4D4 D D D D D 4D4DDD4D4 D D D D D 4D+D+D+D4 D D D D D tD.D.D¢D4 D D D D D .D¢D4D+D+ E E E E D 4E4E+E4D4 E E E E E D 4 4E4E4E4D4 E E E E E D 4 4E4E4E4D4 E E EVD D 4:+e+E4E4D4D4D4D4D+D4E4E4E E+E.E4 4 s n D E E E D D D D D D D E\ E E D _4D4D.E4E.E4E.D4D4DDD4D4D4E4 EvE.D4 E E D E4E4D4 E E D D4E4D4 D D D4D¢ D D D4D4 D D 4D4 D D D D D D E D , some varia- 1gn f, most of the nodes in the interior part of the model have a total capacitance of ty) about each node in level 4 26-31 pf with respect to ground. Therefore 1 IV 700 square metres per day 1,600 square metres per day 620 square metres per day 990 square metres per day 1 'ty= .tY: ty= ty= ifer storage is not accounted for in des issivr issivr lSSiVl 1ssiv1 1n aqu c Transm v Transm E Transm r Transm Although some nodes near boundaries show a total tlon capacitance to ground of 45 p ty) 1. 120 square metres per day of the model. EXPLANATION issiv1 ity (product of thickness and bed-parallel hydraulic conduct . Postconstruc- 310 square metres per day ‘ty ty issiv lSSlVl lSSlVl I Impermeable boundary (no transm indicated that stray capac * Model node n Transm a Transm m) must be bundled into tight cables. Preconstruction FIGURE 21.—Distribution of transm estimates of the capacitance between adjacent nodes were on the order of 3—10 pf (picofarads) tion measurements have tance may be as high as 15 pf between some nodes 27 MODEL DESIGN \1 535E565555.555 cancunoopozccc EXPLANATION 620 square metres per day < Transmissiv'rty 1,500 square metres per day 1,700 square metres per day 990 square metres per day Ivity= : Transmissivity r Transmissivity a Transmiss of the model. a q a anaaoc J LNNN aa55acADoDDo a 5 5 HDDG saver r A Male BBDF H 501)r DEDD o D D 5950500000 EXPLANATION W N 130 days P 170 days a 220 days 5 290 days I 57 days K 68 days L 81 days '1 99 days = 22 days 7 26 days 6 39 days " 48 days divided by bed—normal hydraulic conductivity. * 5.6 days a 6.8 days ‘ 10 days ° 15 days ogy, all specified-flux boundaries are referred to as "stresses.”) IS flow boundaries—The top of the Raritan clay 1. N0- is the interface between freshwater and salty water in IS if it were a boundary at all for unsteady flow. Even in the Magothy irtually unknown. The assumpt is that int beyond which freshwater 1011 lSV ifer incorporated (3) the Magothy aquifer. Unfortunately, the interface ? and (5) stream boundary, the position of the interface 1 120 square metres per day 310 square metres per day ty= ty= B H H D E 955555 DBEBABDBEE 5559555 hDrEflHRAADDHDNOAAD BDBDEEDRDBDDDDDDDD issrvi issivr Bed-normal thickness] bed-normal hydraulic conductrvr 10115 are t' 1 uaaasescccccu uééééézéétacé a. cassaauns . Model node ' Impermeable boundary (no transmissivity) n Transm 9 Transm FIGURE 22.—Distribution of transmissivity (product of thickness and bed-parallel hydraulic conductivity) about each node in level 5 optcnscnnnnnsssansa EEDDDDDEBBEBBDBD 5555 [EGDDE‘DDFEBD 0555 JGDDEDDEBDD E6ElEDEDEEDEDDDBDBBEEEBDDnABF Gsnooaoeeoaaaossabor EEEED EEGDJ GGDBDEB (:6: 5590555 FIGURE 23.—Distribution of estimated values of(A2’/KB) between nodes in levels 1 and 2 of the model, where (Az'/K3) is thickness criteria, but the discrepancy seems negligible when differences between a boundary of type 3 and one of compared with the design capacitance of 27 pf per type4 are size and position. In other authors’ terminol- node. BOUNDARY CONDITIONS Five types of boundary cond into model des (1) Boundaries across which no flow assumed to be an impermeable or no-flow boundary as lgn (2) boundaries along which the potential is de- ’ OCCUI‘S ial sources external to the model fined by potent boundaries across wh ich the flow is defined by external not a fixed boundary for steady-state flow and is no (4) internal stresses whose magnitude and lo- 7 sources cation are defined by external sources boundaries across which the flow is controlled by both aqu internal and external events. (As used here, the only somewhere offshore is apo ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK 28 EXPLANATION Bed-normal thickness/bed-normal hydraulic conductIVIty 500 days 900 days 3 x 3, 5 1,000,000 days v 15,000 days 1 26,000 days 3 150,000 days w 480,000. da is u 200 days P 1,300 days a 1,600 days 5 1,900 days 1 2,300 days u 2,900 days v 3,200 days n 1 v 120 days 130 days r 180 days 6 220 days I 500 days K 640 days L 750 days H 950 days I: FIGURE 24.—Distribution of estimated values of (A2'/KB) between nodes in levels 2 and 3, of the model, where (A2’/KB) is thickness divided by bed-normal hydraulic conductivity. EXPLANATION Bed-normal thickness/ bed-normal hydraulic conductiwty N 1,500 days a 6,200 days a 220 days 800 days 7,400 days U 9,000 days v 9,900 days u 12,000 days 6 s ,900 days « 2,600 days L 3,200 days " 3,900 days n 4,800 days P 5,700 days 1 J 230 days C 290 days D 350 days E 430 days i r 900 days I 1 3,000 days 1,100 days 5 FIGURE 25.—Distribution of values of (Az’/KB) between nodes in levels 3 and 4 and between nodes in levels 4 and 5 of the model, where (A2’/KB) is thickness divided by bed-normal hydraulic conductivity. iles offshore during construction of the ion of this termination was then adjusted nated several m model. Locat flow and the effect of head changes on the island are negligible. The Magothy aquifer was simply term i- MODEL DESIGN during calibration and verification procedures until the steady—state heads and vertical gradients resem- bled the prototype heads and gradients beneath the barrier beaches—as far seaward as prototype data permit. 2. Known-potential boundaries—The shoreline around the island is a specified-potential boundary for the upper glacial aquifer. This potential is determined by external voltage sources and serves as a reference altitude for most model measurements. The upper sur- face of the Gardiners Clay offshore is maintained at the same potential as the shoreline. This is equivalent to assuming that (a) the density of seawater is not sig— nificantly different from that of freshwater and (b) that head losses in the sea-bottom sediments above the clay are negligible. These assumptions are acceptable be— cause the depths of salty water above the clay are small and because the quantity of freshwater leaking through the offshore part of the Gardiners Clay is small. 3. Specified-flux boundaries—Recharge to the upper surface of the model can be either steady-state or steady—state with superposed transients. In each of these recharge modes, this surface is a specified-flux boundary. The flux into each node is equal to the long- term average recharge for the area in the first mode, but in the second the flux varies with time as well as space. Flux across the water table is controlled by ex— ternal current sources and resistor networks that di- vide the current into the proper proportions for each water-table node. Steady-state rates of recharge are controlled by current-regulated power supplies; re- charge rates that vary with time are achieved by superposing a transient current on the steady-state current. In the latter case, op amps (operational amplifiers) with diode-protected low-impedence output and resistance networks are used to isolate the trans— ient electronic sources from the steady-state source. Most models are designed to analyze response to transient stresses without reference to steady-state re- charge. The way in which the streams are simulated in the experiments described herein rendered such opera- tion undesirable, as explained in (5). 4. Internal stresses—Sources and sinks at nodes that are not on a bounding surface of the model are referred to as internal stresses. Stresses of this type include pumping from the aquifer system and (or) injection through wells and basins. These stresses are supplied by pulse generators and function generators, whose output is buffered by op amps. The op amps isolate the outputs of the pulse generators from each other so that it is possible to produce “step” and “ramp” approxima- tions for stresses that vary with time. "Step” and “ramp” approximations, in which stresses change 29 either in discrete steps or as a linear function of time, can be good approximations for many stresses. Al- though "ramp” and “step” functions may be gross rep- resentations of historical prototype stresses that vary irregularly in time and space, the model reservoir, as the prototype, tends to smooth out the response to rapidly changing stresses. The results are usually ac— ceptable. The electrical stress is provided by currents (equivalent to rates of recharge and discharge) that vary with time. The low output impedence of the op amps makes this possible. Figure 26 shows the system for producing transient stresses. The slow-rate generator shown in figure 26 provides a common reference time for measuring instruments as well as the signal generating equipment. Delay units start different pulse generators at various times after this reference time. 5. Stream boundaries—Streams are nonlinear boun- daries on the system; their effect varies as a function of head within the model. Streams in the model have been represented by several different types of electrical circuits, all of which have been developed empirically without any attempt to represent the equations for open—channel flow. For the steady-state calibration studies, the streams were modeled by simple resistor networks as is shown in figure 27. In order for these steady-state streams to represent the prototype streams, two conditions must be met at each stream node: (1) Flow out of the model network through each node must represent seepage into the stream reach represented by the node, and (2) head at the node must represent an “average” elevation of the water table in the area represented by the node. (This average elevation is assumed to be equal to the eleva- tion of the stream surface). In the model (fig. 27A), a string of resistors was connected in parallel with the stream nodes. Thus, the voltage drop across each resis- tor in the string equalled the voltage drop between successive stream nodes of the model. The current flow— ing into each junction along the string of resistors (that is, leaving each stream junction of the model network) represents the ground-water seepage into the stream reach. Current (IR in fig. 27A) carried by any resistor in the string represents the sum of all the seepage cur- rents upstream from that point. In Long Island, where streams derive almost all their flow from ground-water seepage, this current must increase downstream in a normal, steady-state configuration. Each resistor was chosen so that when the voltage drop across the resistor (E l-Ez) was proportional to the head drop (hi—hz) between successive node points in the steady-state prototype system (fig. 273), the cur- rent I R1 through the resistor was proportional to the cumulative discharge Q31 in the stream reach. This 30 1 Slow-rate garner-for waveform- dalav generator Variable delay units @J, @Tb V ‘ ANALOG~MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK Waveform- delay generator Variable- pulse generator Variable- pum generator Variable- pulse generator Veriablr pulse generator Variable» pulse generator Variable- pull. generator @fi. @fi @ © Pulse amplifier Pulse amplifier Fulea amplifier Pulse ampl ifiar Pulse amplifier Pulse amplifier Pulse amplifier Pulse amplifier Pulse amplifier Pulia amplifier Pulse amplifier Pulse amplifier .3 V LTRIGGEH FOR MEASURING INSTRUMENTS %_ TO DISCHARGING NODES ON MODEL———j DISTRIBUTION NETWORKS ”g _J I— TO RECHARGING NODES Note: Typical waveforms are :hown In circles FIGURE 26.—Method for producing transient analog stresses. The distribution networks allow superposition of waveforms so that com- plex patterns of pumping and recharge can be approximated. insured that, at every junction, the seepage currents I S would be proportional to the ground-water seepage Q S into the stream in the block represented by the junc— tion. The configuration in figure 27A assures that, when the steady-state voltages,E1,E2, . . . En, correctly represent steady-state heads, h1, h2, . . . hn, along the channel, the current out of each stream node will be proportional to the seepage into the stream in that re- ach. The type of circuit in figure 27A can only represent ground-water seepage to a stream in the steady-state configuration for which the circuit was specifically de- signed, not in a transient situation in which heads be- neath the stream may change with time. In the pro- totype system, seepage to streams rapidly decreases to zero as heads decline; when heads fall below stream level, the direction of seepage is reversed. If the flow in the affected stream reach is sustained by inflow to the stream in upstream areas, this seepage into the aquifer may continue; however, if the head in all upstream areas has similarly dropped below stream level, the stream will simply dry up everywhere above the first point at which ground-water head exceeds stream level. In the dried-up part of the stream, there will be no seepage in either direction between the stream and the ground-water system. Behavior of this type was observed in nearly all streams on Long Island during the drought of the 1960’s. To simulate the type of stream-aquifer condition ob- served during the drought, the circuit in figure 27 was modified by replacing each stream resistor with a re- sistor and diode in series. The diodes and resistors were chosen so that with potentials E1, E2, . . .E" represent- ing the prototype steady-state heads h1, h2, . . . h" , the forward resistance of each diode-resistor combination would be the same as the resistance of the resistor alone in figure 27A. If downstream gradients (that is, the voltage drop between successive nodes) were to de- crease as a result of transient stresses, the diode resis- tance would increase and would effectively stop streamflow in the affected reach. If, for example, E1 were to decline while E2 remained constant, when El—E2 dropped below the junction threshold voltage for the diode between nodes 1 and 2, the current 1R1 would drop to zero. Reduction OfIRl 'would result in a reduc- tion in 132 and in the current carried by each sub- sequent reach of the simulated stream. As heads throughout the model aquifer continued to decline in MODEL-PROTOTYPE COMPARISONS Stream network lR1 Aquifer network FIGURE 27.—Circuit diagram of a model stream (A) showing voltages E1, E2, . . . En and currents 1R1 , I“, . . . IR, along the stream and currents Is], 1.5-2, . .. 15,, into the stream. A prototype stream channel (B) indicates the values of head (h1, h2, . . . h,,), repre- sented by the voltages, and discharges QR and QS represented by the currents in the model. Each junction in the model network represents one of the aquifer blocks in the prototype. response to a simulated drought, E2 would eventually decline until Eg—E3 was less than the threshold voltage for that diode and 1R2 would decrease to zero. The stream would be shortened at its head. Although model operation with the two stream cir- cuits, as well as model operation without streams, proved useful for the model-performance analyses de- scribed in the section “Model-Prototype Comparisons,” they were not adequate for some predictive studies. A third circuit, different in concept and more difficult in execution, has been used for predictive studies. Be- cause the third circuit was not used in any of the analyses described in this report, a description of that circuit will be deferred to a later report (A. W. Har- baugh and R. T. Getzen, written commun., 1975). SUMMARY OF DESIGN CRITERIA Conditions of the ground-water reservoir that must 31 be correctly represented by the model are as follows: (1) Geometry and distribution of hydraulic conduc- tivity in the reservoir rocks. For Long Island, distribu- tion of conductivity is three dimensional, and mag- nitude of conductivity is direction dependent. The finite-difference network must be alined with the di— rections of the principal conductivities. (2) Average magnitude of the specific storage of the reservoir rocks and spatial distribution of storage. (3) Location of boundaries of the hydrologic system and nature of the boundaries. Where this is not com- pletely possible, the boundaries were designed to have minimal effect on the internal parts of the model. The lower boundary of the Magothy aquifer and the saltwater—freshwater interface are not exactly repre- sented by the model. The model attempts to minimize the effects of these boundaries. (4) Historical data on internal stresses to the reser- voir and electronic-exciting circuitry capable of repre- senting these stresses. (5) Ground-water discharge to surface-water bodies. Where this seepage is to streams and its magnitude is likely to change drastically as a function of small head changes within the ground-water reservoir, the model must be capable of correctly representing the change in seepage. If the model can reproduce observed and calculated distributions of head in response to observed (histori- cal), stresses and synthetic stresses, all the preceding conditions are assumed to have been met. The model is then said to be “calibrated” or "verified.” Such a verifi- cation procedure does not prove that the model ground-water reservoir will respond correctly to all stresses; it only shows that the representation of re— sponses to a certain range of stress situations seems to correlate with observed prototype response. MODEL-PROTOTYPE COMPARISONS PERFORMANCE CRITERIA Model performance is generally evaluated in terms of the preceding design criteria. Most of these criteria cannot be adequately defined by prototype data. The best known of these criteria on Long Island is the gen- eral configuration of the water table. Historical data describing the water table are shown from Burr, Her- ring, and Freeman (1904); Veatch, Slichter, Bowman, Crosby, and Horton (1906); Jacob (1945); Isbister (1959); and Kimmel (1971). In a thin, isotropic aquifer, the configuration of the water table would be adequate for defining correct steady-state operation of the model. The same cannot be said for regional flow systems in thick, anisotropic sedimentary sequences (Freeze and Witherspoon, 1967, p. 632-633). Sufficient data to 32 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK permit description of the head distribution at other depths have been acquired only recently (Kimmel, 1971; Jensen and Soren, 1974). Because measurements are almost never made before ground-water develop- ment begins, data that reflect human as well as climatological influences on the ground-water system must be used to estimate and extrapolate the distribu- tion of steady-state head. Model performance is measured by two types of tests—steady-state tests, which measure the model’s ability to represent average or predevelopment hydro- logic conditions, and unsteady-state tests, which com- pare the model’s response to transient stresses with prototype response to historical stresses. Evaluation of unsteady (transient) model perform- ance requires two types of data—quantitative meas- urements of the stress (pumping, recharge, fluctuating lake levels, and other boundary conditions) and histor- ical responses (changes in head and discharge over long periods of time) of the system to those stresses. Two types of unsteady stresses were considered in evaluating model performances: (1) Changes in net re- charge that resulted from the severe drought of the early 1960’s and (2) historical pumping records from major wells or well fields in western Long Island. Data for magnitude of the type 1 stresses are from Cohen, Franke, and Foxworthy (1968), and for type 2 from records compiled by New York State Water Power and 20 d0 60 Base from U.S. Geological Survey, l:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 Recharge, in centimetres per year VA El RN 46—49 49—52 52-55 43—46 Control Commission and by county agencies. Simu- lated response to the climatological stress was com- pared with the observations by Cohen, Franke, and McClymonds (1969). Response and recovery of the simulated water table to pumping stresses was com- pared with water-table data compiled by Lusczynski (1952) and from other sources cited in the preceding paragraph. Data from several of these sources are re- produced in subsequent illustrations for comparison with model response. In addition to stress and head data, records of stream discharge are compared with simulated stream dis- charge. Streams on Long Island are seldom gaged at more than one point along their length; except for a few seepage runs and qualitative information about tidal fluctuations and location of the heads of streams in varying hydrological circumstances, there is only one point on each stream at which the model can be compared with prototype data. STEADY-STATE EVALUATION The average annual ground-water recharge has been estimated to be 58 cm (23 in.) for a water-budget area that excludes the highly urbanized areas and low-lying coastal areas of Long Island (Cohen and others 1968, p. 44—45). This value was used as a starting point for steady-state calibration of the model but yielded un- satisfactory results. The estimate of Cohen, Franke, 86 100 120 140 150 5 10 15 MILES 1o 15 KILOMIiTRES r l . , l , . EXPLANATION 722 Line of equal annual average precipitation Interval, 5 centimetres per year (2 inches per year) FIGURE 28.——Distribution of prototype mean annual precipitation, 1951—65, and of steady-state recharge to the model. (Mean annual precipitation modified from Miller and Frederick, 1969.) MODEL-PROTOTYPE COMPARISONS 60 Base from U.S. Geological Survey, 1:250,000 series: Hartford, 1962; New York, I957; Newark, 1947 80 100 120 140 150 0 5 10 15 MILES o 5 1o 15 KILOMETRES“, FIGURE 29.—Simu1ated, steady-state, water-table profiles and locations on western Long Island compared with 1903 prototype water- table profiles. Major production wells near profiles in 1903 are also shown. Prototype data from Burr, Hering, and Freeman (1904). and Foxworthy (1968) seems to be too high if applied to the entire island. Several factors influence the rates of recharge; the most important seem to be (a) rate and duration of precipitation, (b) infiltration characteris- tics of the surficial sediments, (c) thickness of the un- saturated zone, and (d) local relief. Precipitation is not uniformly distributed over Long Island (fig. 28) but is noticeably greater near the center of the island than elsewhere. The soils of the morainal parts of Long Is- land tend to be less permeable than the soils of the outwash areas. Thus, there is a tendency for a greater proportion of the precipitation to run off near the north shore. Steep slopes, like those on the north shore, tend to cause precipitation to run off faster than it does on gentle slopes. Much more of the water that infiltrates the soil is lost to plant roots and to evaporation where the water table is close to the surface; a smaller propor- tion of rainfall becomes part of the ground-water re— servoir in low—lying, swampy areas than in areas of greater altitude. The combination of all these factors does not reduce to an equation from which the steady- state recharge values shown in figure 28 could be calculated. These known factors make the recharge distribution in figure 28 seem reasonable, but other factors, unknown or misunderstood, could influence re- charge rates in entirely different ways. The distri- bution of model recharge shown in figure 28 was ob— tained through a “tuning” process. The gross estimate by Cohen, Franke, and Foxworthy (1968) was assumed to be acceptable; distribution of this recharge was mod- ified by trial and error until a reasonable water table was obtained. With the recharge distribution shown in figure 28, SOUTH NORTH A A’ . 150 Pumping center m 40 E 1: Model steady-state u.l .I-I-J 30 100 LL 2 E z ui 120 o g 50 g D L". 10 I; l- < 2' o v . o B B’ 150 :15 4° - E '1 E '— 1“ 30 — 1002 2 _ z ‘5’ "220 — u.l D o 50 l'.‘ D I- 10 ‘ '3 ; <12 .1 0 0 < I I I ' C' 50 - m 150 n: ,_40 — Lu 2 E 30 — 100 ui D 20 — E 50 I- 10 - _I < 0 . o O 5 10 MILES l7 I I I II I II I ' I 0 5 10 KILOMETRES FIGURE 29,—Continued. 33 ALTITUDE, IN FEET 34 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK KINGS QUEENS " COUNTY COUNTY I ' r . 0 A TLANTIC 4 O 30; + 5 10 15 2O 25 MILES | I | | I I I I I I 5 1O 15 20 25KILOMETRES O——O EXPLANATION OCEAN _ ,5 — Line of equal prototype head —20 Line of equal simulated head Intervals, 5 and 10 metres (16.4 and 32. 8 feet) Base from US. Geological Survey, l:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 30.—Comparison of steady-state model water table with 1903 water table in central Long Island. (Prototype data from Veatch and others, 1906.) NASSAUQ COUNTY QUEENS ’ KINGS COUNTY COUNTY l l a A TLANTIC 40 30: + 0 5 10 15 20 | I | | 15 20 25K|LOMETRES 25 MILES I O 5 1O 7 UFFQLK 7‘, ‘ 2' COUNTY OCEAN EXPLANATION 15 Line of equal prototype head 20 Line of equal simulated head Intervals, 5 metres (16.4 feet) Base from US. Geological Survey, l:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 31.—Comparison of steady-state model water-table with 1970 water table in eastern Long Island. (Prototype data from Kimmel, 1972.) the model produced the steady-state, water-table con- figuration that is compared with observed prototype water-table data in figures 29—31. Figure 29B shows water-table profiles along three lines of section in western Long Island; locations of these lines of section are shown in figure 29. Pumpage and other manmade hydrologic disturbances began in western Long Island and gradually spread eastward. The 1903 water levels for the westernmost part of the island reflect these manmade disturbances. The steady-state model analysis did not simulate these manmade effects, and, therefore, agreement between the model results and MODEL-PROTOTYPE COMPARISONS 35 NASSAU COUNTY KINGS QUEENS ’ , COUNTY COUNTY l ' ‘1“ 40°30 o 5 1o 15 20 25 MILES l l l I I W l I I I I o 5 10 15 20 25 KILOMETRES EXPLANATION 10 Line of equal prototype head 20 Line of equal model head Interval, 5 metres (16.4 feet) Base from US. Geological Survey, 1:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 32.——Comparison of steady-state simulated head near the base of the Magothy aquifer with 1971 prototype head. (Prototype data from Jensen and Soren, 1974.) the 1903 water levels is poor for the westernmost line of section A—A’ in figure 29. The agreement improves progressively to the east as the manmade effects di- minish. The poor agreement along line A—A’ may also reflect that the model design is based on saturated thickness of the glacial aquifer in 1970; the saturated thickness in 1903 was considerably greater than it was in 1970 for part of Kings County. Model performance in the westernmost part of Long Island could not be justified by the preceding comparison but was justified by unsteady-state performance (next section). For the eastern two-thirds of the modeled area, agreement between the prototype water table and model results was good, as shown by the maps of figures 30 and 31. Figure 30 shows a comparison of steady-state model results with a water-table map by Veatch, Slichter, Bowman, Crosby, and Horton (1906) covering eastern Nassau and western Suffolk Coun- ties. Effects of pumpage were negligible in these areas at that time. Because the map by Veatch, Slichter, Bowman, Crosby, and Horton (1906) does not include the easternmost one-third of the modeled area, figure 31 shows a comparison of model results with 1970 water-table contours by Kimmel (1972) for Suffolk County. Again, the effects of pumpage on water levels in Suffolk County were small in 1970. Comparison of heads near the base of the Magothy aquifer in 1971 with simulated steady-state head in model level 5 is shown in figure 32. Data for only the eastern half of the island are shown; heads in the lower part of the Magothy aquifer have been noticeably af- fected by pumping in the western half of the island. Extent of agreement between prototype and model heads is not perfect but is within a few metres for most of the reservoir for which reliable data are available on undisturbed natural (predevelopment) potential. Some of the disagreement is probably due to differences in data interpretation; for example, other water-table maps such as that by Cohen, Franke, and Foxworthy (1968, plate 2E), do not show the same pronounced high in southeastern Suffolk County as that indicated by the 15—m (49-ft) closed contour in this area in figure 31. Distribution of normal, steady-state head along two typical model hydrologic sections is shown in figure 33. Although there are no satisfactory prototype data for comparison, model head and flow data given in the hydrologic sections are useful for understanding the flow system. Table 2 compares long-term average stream dis- charge with values of steady-state stream discharge from the model. Where a range of discharge is given for the simulated stream discharge, the prototype gage is near the division between two stream reaches on the model. Most pairs of model and prototype stream dis- charges agree within :5 percent, and all pairs except for about ten streams agree within :10 percent. Only short streams and streams that have extremely high or extremely low gradients have model discharges that differ significantly from prototype discharges. The dif- ference between total stream discharge as modeled and the long-term average for all prototype streams com- 36 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK D 0' SOUTH NORTH FEET 200 — _ Level 1 METRES SEA _ 68 _— 100 60 _ SEA LEVEL “—19”, FLEVEL 200 — Level 3 360 ' 100 400 — 4/ _ N 600 — 850 S - _ 0° " — 200 270 <0 e 560 80° _ Level 4 — EXPLANATION 1000 — 70 _ — 300 Head, in metres 1200 ‘ 270 592 _ 1/ Bed-parallel flow components in cubic L I 5 metres per day per kilometre of width — 400 1400 - eve (bed-normal components not shown) — 1600 — 500 F F' SOUTH NORTH FEET 200 — METRES SEA LEVEL F SEA LEVEL 200 — _ 100 400 - 600 — — 200 800 — 1000 — — 300 1200 — Level 5 — — 400 1400 - _ 1600 o 2000 4000 6000 8000 10,000 FEET ‘ 50° L l i l L I l l I fir 0 1000 2000 3000 METRES FIGURE 33.—Distribution of head and bed-parallel components of ground-water flow along two hydrologic sections through the model Long Island ground-water reservoir. Rates of flow are for a 1-kilometre—wide strip. Locations of sections are shown in figure 4. MODEL-PROTOTYPE COMPARISONS 3 7 TABLE 2.-—Streamflow comparisons Average Model Code shown for discharge discharge streams in (cubic metres (cubic metres figure 14‘ Stream name per second) per second) B Valley Stream ,,,,,,,,,,,,,,,,,,,,,, 0.165 0.186 C Pines Brook ,,_, _,_ .141 .15 D South Pond ,,,,,, , .083 .094 E Parsonage Creek“ 117 .100 F Milburn Creek ,,,,,,,, 242 .271 G East Meadow Brook _, .473 .575 H Cedar Swamp Creek ,,,,,, .239 .265 I Newbridge Creek ,,,,,,,, .066 1.048 to .070 J Bellmore Creek ,,,,,,,,,,,, .310 .435 L Seamans Creek _, .054 .050 to .058 M Seaford Creek _,_, .054 .064 to .084 N Massapequa Creek _, .339 .304 to .438 0 Carman Creek ,,,,,, .120 .136 to .154 P Amityville Creek .110 .059 to .102 Q Great Neck Creek .071 .075 to .142 R Strongs Creek a, .054 .052 to .082 S Neguntatogue Cre .108 .066 T Santapogue Creek a, .126 .165 U Carlls River ,,,,,,,,,,,,,,,,,,,,,,,, .772 1.01 .967 1.05 V Sampawams Creek ,,,,,,,,,,,,,,,,,, .342 .397 W Shookwams Creek _,_ .031 .034 to .055 X Willets Creek _,_ .071 .074 to .100 Y Trues Creek ., .051 .058 Z Cascade Creek“ .071 .048 to .080 AA Penataquit Creek ,,,,,,, .175 .185 to .212 AB Awixa Creek _ ....... .054 .063 AC Orowoc Creek _, ,,,,,,, .074 .080 AD Pardees Pond _, .174 .066 to .107 AE Cham lin Creek .207 .247 to .343 AF West rook ,,,,,, .120 .096 AG Rattlesnake Brook _, .262 .248 to .277 AH Connetquot River _, 1.10 1.02 Al Green Creek ,,,,,,,,,, .128 .131 AJ Brown Creek (west) ., .231 .245 AK Brown Creek (east) .231 .245 AL Tut Hills Creek ,_ .174 .116 to .171 AM Patchogue Creek .595 .528 to .653 AN Swan River , .365 .354 A0 Mud Creek ,1 .153 .145 to .154 AP Motts Brook , .051 .013 to .070 AQ Beaverdam Cr .046 .039 AR Carmans River .048 .055 .678 .518 AS Forge River ,,,,,,,,,,,,,,,,,,,,,,,, .274 .298 AT Terrel River “A ,,,_ 071 .069 AU Little Seatuck 1., 128 .135 AV Seatuck Creek _, , .162 205 AW East River ,,,,,,,,, .071 .082 AX Beaverdam Creek _ , .068 .055 to .057 AY Aspatuck Creek ,,,,,,, _ .063 .070 AZ Quantuck Creek ,_, ...... .060 .069 BA Whitney Lake (A .071 .061 BB Roslyn Brook _., .051 .066 BC Glen Cove Creek.“ .202 .206 BD Island Swamp Brook 1 .026 .031 BE Mill Neck Creek ,, , .268 .121 BF Cold Spring Brook , .126 .130 BG Mill Creek ,0, .085 .047 BB Stony Hollow Ru , .034 .046 BJ NE Nissequogue H. .051 .086 .111 .114 1.18 1.28 BK Wading River ,,,,,,,,,,,,,,,,,,,,,, .028 .026 BL Saw Mill Creek ,,,,,,,, , .077 .042 BM Peconic River ,,,,,,,,,,,, .986 1.00 BN Little River ,_, ,,,,,,,, .125 .137 to .168 B0 White Brook ,,,,,,,,,,,,,,,,,,,,,,,, .077 .086 1Codes for only 64 of 75 streams plotted in figure 14 are listed, Eleven ofthe 75 streams, most of them in Queens County, have been replaced by sewers. 2A range of discharge indicates that prototype gage falls at or near division between two reaches on model. bined is less than 5 percent. The ability of the simu— lated streams to represent prototype discharge cor- rectly at one or two points (the gages) on each stream does not mean that the overall representation is cor- rect. There are no prototype data relating changes in seepage along the entire length of each stream to changes in the water table, but the general agreement of the model response with the available historical data strongly suggest that the response of the pro- totype system is closely simulated by the model. /Long—term average recharge 10— 15— 30- 35— 40L 1965 1966 PERCENTAGE BELOW AVERAGE RECHARGE to O I FIGURE 34.—-Changes in annual recharge used to simulate the 1962-66 drought on Long Island. UNSTEADY-STATE EVALUATION Two historical stresses were used for unsteady-state evaluation. The first of these, the drought of 1962-66, was simulated by using estimates of the reduction in recharge during the drought (Cohen and others, 1968, plate 4E). Yearly deviation from the long—term, aver— age annual rechar'ge, derived from the estimates, is shown in figure 34. This stress has two causes: (1) Re- duced precipitation and (2) sporadically occurring pre- cipitation. During the drought, intense storms were the source of much of the precipitation. Although most precipitation on Long Island is rapidly absorbed by the soil, intense storms contribute large amounts of runoff to streams and fill surface ponds that evaporate. Very little of the storm precipitation becomes ground-water recharge. The intensity of the drought stress, as given by Cohen, Franke, and Foxworthy (1968) and in figure 34, is a net or total stress. Just as was the case with aver- age recharge distribution (fig. 28), the areal distribu- tion of drought shown by the map in figure 35 was derived by a trial—and-error procedure aimed at repro- ducing the prototype response. Distribution of stress, mapped in figure 35 in terms of deviation from the islandwide areal average stress, was assumed to be constant from year to year during the drought. The trial-and—error method involved trying three different stress distributions: (1) Drought stress was uniformly distributed over the entire island; (2) stress in the low- lying parts of the island was five times greater than that in the higher, central part of the island; and (3) stress in the low-lying parts of the island was twice as great as that in the center of the island as depicted in figure 35. In each of these three stress distributions, 38 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK 20 40 60 Base from US. Geological Survey, 1:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 10 percent greater than 25 percent greater than average stress average stress Average stress 80 100 120 150 5 10 15 MILES 1o 15 KILOMETRES‘, , l , , , I EXPLANATION W 25 percent less than average stress 10 percent less than average stress FIGURE 35.—Distribution of the decline in net recharge used to simulate the 1962—66 drought on Long Island. The distribution is given in terms of deviation from the islandwide areal average of the stress. ATLANTIC + 0 5 10 15 20 25 MILES II I I l I O I l | l l ‘1 5 10 15 2O 25K|LOMETHES OCEAN EXPLANATION Line of equzfl prototype head decline, 1962-66 2.5 Line of equal simulated head decline, 1962-66 Intervals, 1 and 0.5 metres~ (3.3 and 1.6 feet) Base from US. Geological Survey, 1:250,ooo series: Hartford, 1962; New York, 1957; Newark, 1947 FIGURE 36.—Comparison of observed and simulated water-table declines as a result of the 1962—66 drought. (Prototype water-table decline from Cohen and others, 1969.) the total stress during each time period was equal to the quantity indicated in figure 34. Simulated response to the assumed stress situation is compared with the net-change map (fig. 36) pre- sented by Cohen, Franke, and McClymonds (1969, fig. 10), who mapped the change in the water table be- tween 1961 and 1966. Their map does not show net changes in New York City and western Nassau County because changes in water levels there are the result of other influences. Changes in recharge caused by pav- MODEL-PROTOTYPE COMPARISONS 39 TABLE 3.-—Net recharge (positive) and withdrawal (negative) at each model node used to simulate manmade historical stresses in. western Long Island during the periods 1903—33, 1934—42, 1943—50, and 1951—63. Unstressed nodes are not listed [Accuracy of these measurements is about :2 percent or :40 cubic metres per day, whichever is greater] LEVEL 1 LEVEL 2 LEVEL 3 VEAns..-1903-33 193s-s2 19A3-so 1951-63 1903-33 1936-62 1943-50 1951-63 1903-33 193e-o2 19.3-50 1951-63 iofiff— nooe CUBIC usraes PER DAV CUBIC METRES pea DAV CUBIC HETRES PER DAV 10 ex -12920. -99Ao. ~59oo. -2980. o. o. o. o. o. o. o. o. 12 as -99Ao. -se9o. -~91o. -2vo. o. o. o. o. o. o. o. o. 14 ac -aaoo. -7150. -#620. -179o. o. o. o. o. o. o. o. o. 14 a: -22150. -1s9ao. -1oeao. -¢91o. o. o. o. o. o. o. o. 0. 1A as -7bso. —79so. -e9so. -1~9o. o. o. o. o. o. o. o. 0. 1A 31 -5oo. -6950. -5960. o. o. -5so. -5~6o. -119o. o. o. o. o. 16 ac -2os1o. -111ao. -9eao. -Aezo. o. o. o. o. o. o. o. o. 16 a: -1oso. -6950. -391o. -1er. o. o. o. o. o. o. o. 0. 16 as -5Aeo. -99~o. -79so. -9oo. o. o. o o. o. o. o. o. 16 31 o. o. o. o. -990. -19so. -3Aao. -2oo. o. o. o. o. 16 an —5oao. -A520. -3530. -soo. o. o. o. o. o. o. o. o. 16 an '6460. o. o. o. o. o. o. o. o. o. o. o. 17 BA -12520. -1o9ao. -6160. -2eao. o. o. o. o. o. o. o. o. 15 aa -1oieo. -aaao. -so1o. -2o9o. o. o. o. o. o. o. o. o. 13 ac o. o. o. o. o. -eAso. -1o930. -11920. 0. o. o. o. is as o. o. o. o. 0. -‘so. -A~1o. -1A9o. o. o. o. o. 18 as o. o. o. o. -199o. -12920. -391o. -5oo. o. o. o. o. 15 ex -Z9610. -1391o. -1o93o. -199o. o. o. o. o. o. o. o. o. 19 A2 -92oo. -aoso. -~ezo. -1e9o. o. o. o. o. o; o. o. o. 19 36 -A920. -~Azo. -3o30. -5oo. o. o. o. o. o. o. o. o. 20 An -3430. -1940. -1190. -19.o. o. o. o. o. o. o. o. o. 20 AV -3s3o. -2o~o. -1a‘o. -2o‘o. o. o. o. o. o. o. o. o. 20 9A -9o9o. -19so. -Aszo. -1a.o. o. o. o. o. o. o. o. o. 20 ac -easo. -7aoo. -s17o. -1¢90. o. o. o. o. o. o. o. o. 20 as o. o. o. o. -3910. -2oeeo. -99¢o. -99o. o. o. o. o. 20 81 o. o. o. o. -5120. o. o. o. o. o. o. o. 22 Au -3230. -1a~o. -1690. -1840. o. o. o. o. o. o. o. o. 22 AH -e9Ao. -A~1o. -4A1o. -~A10. o. o. o. o. o. o. o. o. 22 AV -3a80. -1990. -1aAo. -199o. o. o. o. o. o. o. o. o. 22 3A -3~ao. -199o. -ia~o. -199o. o. o. o. o. o. o. o. o. 22 Be -990. o. o. o. o. o. o. o. o. o. o. o. 24 Au -3eao. -2oeo. -19~o. -2o9o. o. o. o. o. o. o. o. 0. 2A BA -3130. o. o. o. o. o. o. o. o. o. o. 0. 2A as o. o. o. o. o. o. o. o. -99Ao. -600. -3oo. o. 26 BA -1640. o. o. o. o. o. o. o. o. o. o. o. 26 ac -3130. o. u. t. o. o. o. o. o. o. o. o. 26 as -easo. -909o. -12120. -1151o. o. o. o. o. -3a1o. -l9§0. o. o. 26 a: o. o. o. o. o. o. o. o. -3e1o. -l940. o. 0. 2a ac -1eso. o. o. o. o. o. o. o. o. o. o. o. 25 as -2~a~o. -~91o. -13Aio. -13910. 0. o. o. o. -soo. -aAo. -1vo. -2o9o. 25 as -sovo. -13oo. -9140. -929o. o. o. o. o. o. o. o. o. as ex -aAso. o. o. o. o. o. o. o. o. o. o. o. 30 ac -213ao. -1990. -990. o. o. o. o. o. o. o. o. 0. 30 a: -1950. -11920. -12420. -1e39o. o. o. o. o. o. o. o. 0. 30 as -A91o. -19so. -89Ao. -11920. 0. o. o. o. o. o. o. o. 30 ex 0. o. o. o. o. o. o. o. -eoso. -3oo. -3oo. o. 31 31 -1A9o. o. o. o. o. o. o. o. o. o. o. o. 32 ac o. o. o. o. o. o. o. o. -ooo. -a;o. -ivo. -2ooo. 32 as o. o. o. o. o. o. o. o. -199o. -990. -1290. -2aao. 32 91 o. o. o. o. o. o. o. o. -1sooo. -59eo. -3Tao. -99o. 32 an o. o. o. o. o. o. o. o. -3910. -sseo. -AA10. -5560. 34 AV -391o. -o970. o. o. o. o. o. o. o. o. o. 0. 3A as -11920. -1950. -avo. -99Ao. o. o. o. o. o. o. o. o. 3; 31 -199o. -soo. -soo. o. o. o. o. o. -eAso. -sovo. -119o. o. 36 AV 0. o. o. o. -sezo. o. o. o. o. o. o. 0. ing and building, ground-water withdrawals through pumping wells, and sewering have strongly affected the water table in the western part of Long Island. Considering the assumptions that underlie the re- charge estimates (Cohen and others, 1968, p. 44), the extent of agreement between simulated and observed changes in the water table is quite satisfactory. Although direct measurements of net recharge are not avaflable——only gross esthnates based on other components of the hydrologic cycle, some of which can only be approximated—the decline in recharge during a drought would probably be distributed unequally. The assumed distribution of stress (fig. 35) is not un- realistic because the erratic frequency and intensity of precipitation during the drought (Cohen and others, 1969, p. F8) resulted in much greater runoff than nor- 40 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK TABLE 3.—Net recharge (positive) and withdrawal (negative) at each model node used to simulate manmade historical stresses in western Long Island during the periods 1903—33, 1934—42, 1943—50, and 1951—63. Unstressed nodes are not listed—Continued LEVEL 1 LEVEL 2 LEVEL 3 YEARS-~ 1903-33 1936-62 1963-50 1951-63 1903-33 1936-62 1963-50 1951-63 1903-33 1936-62 1963-50 1951-63 N L NODE CUBIC METRES PER DAY CUBIC NEYRES PER DAY CUBIC NETBES PER DAY 36 BC -350. -6320. -5120. -6950. 0. 0. 0. 0. 0. 0. 0. 0. 36 BE -5960. -5960. -6950. '7950. 0. 0. 0. 0. ~790. ~2960. '3830. '6350. 36 SG -350. -6220. -5020. -6010. 0. 0. 0. 0. 0. -2960. '6170. '0650. 36 B! 0. 0. 0. 0. 0. 0. 0. 0. -700. ~2900. -500. 100. 36 BK -1690. '500. '500. 0. 0. 0. 0. 0. '700. '3970. '6970. -500. 36 BP 0. 0. -1290. -2160. 0. 0. 0. 0. 0. 0. 0. 0. 3B 8C 0. 0. 0. 0. 0. 0. 0. 0. 0. -990. -990. '990. 36 BE -350. -6370. -5170. -7050. 0. 0. 0. 0. '790. -2960. '3830. -0350. 3G 86 0. 0. 0. 0. 0. 0. 0. 0. -700. ~2530. ~3200. '7200. 38 81 200. 990. 1090. 600. 0. 0. 0. 0. -790. -2980. -3970. -5960. 36 BK -16900. '6970. -7650. 860. 0. 0. 0. 0. -1990. -2700. -3000. -5560. 36 BM -9960. 6620. 6970. 6620. 0. 0. 0. 0. -500. -3680. -6720. -10930. 60 AS 0. 0. 0. 0. 0. 0. 0. 0. -200. -500. -500. ~600- 60 AU 0. 0. '1690. -2830. 0. 0. 0. 0. -1990. -6970. -6970. -5960. 60 BA -3680. 0. 0. 0. 0. 0. 0. 0. -9960. -9960. -7950. -6970. 60 86 650. 2190. 2980. 100. 0. 0. 0. 0. -1690. -6970. -5960. '6950. 60 81 250. 1160. 1690. -300. 0. 0. 0. 0. 0. 0. 0. 0. 60 BK 3380. 2060. 2930. 2780. 0. 0. 0. 0. -250. -1§90. -1390. '5120. 60 BM -l6900. -5960. -3970. -5960. 0. 0. 0. 0. 0. 0. 0. 0. 60 80 2630. 600. 650. 890. 0. 0. 0. 0. 0. 0. 0. 0. 62 A! 0. 0. 600. 2680. 0. 0. 0. 0. 0. 0. -650. -2730. 62 AV 0. 0. 600. 2560. 0. 0. 0. 0. 0. 0. -350. -2260. 62 BA 0. 550. 1660. 2160. 0. 0. 0. 0. 0. 0. 0. 0. 62 BC 500. 2260. 2830. 0. 0. 0. 0. 0. -600. -2290. -2660. '3600. 62 BE 500. 2260. 2800. 0. 0. 0. 0. 0. 0. 0. 0. ‘2190. 62 BG 0. 0. 0. 1790. 0. 0. 0. 0. 0. 0. 0. 0. 62 81 650. 2190. 2930. 0. 0. 0. 0. 0. -600. -2330. ~2760. '3580. 62 BK ~2680. 0. 0. 0. 0. 0. 0. 0. -250. -1660. '1660. -5170. 62 BM 3330. 600. 0. 1660. 0. 0. 0. 0. 0. 0. 0. 0. 66 A0 0. 350. 350. 550. 0. 0. 0. 0. 0. 0. 0. 0. 66 A0 0. -990. ~1690. —2660. 0. 0. 0. 0. 0. 0. '650. '1690. 66 AV 0. 650. 1660. 1760. 0. 0. 0. 0. 0. 0. 0. 0. 66 BA 350. 1690. 1960. 0. 0. 0. 0. 0. -500. -1590. -1S90. '2660. 66 BE 0. 600. 200. 650. 0. 0. 0. 0. 0. -600. -600. -1190. 66 BI 50. 1560. 2190. 1590. 0. 0. 0. 0. -250. -1560. -1360. '6970. 66 BK 0. -1660. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 66 BM 0. 1660. 1060. -500. 0. 0. 0. 0. 0. 0. 0. 0. 66 BO 0. 0. 0. 0. 0. 0. 0. 0. -700. -3630. -3030. -6970. 65 BB 0. 650. 1590. 1690. 0. 0. 0. 0. 0. 0. 0. 0. 66 AS 500. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 66 AU 0. 0. 600. 2630. 0. 0. 0. 0. 0. 0. 0. 0. 66 AV 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -550. '1090. 66 AH 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -250. -990. 66 AX 0. 550. 2730. 6670. 0. 0. 0. 0. 0. 0. 0. 0. 66 AY 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -350. '1290. 66 BA 0. 0. 0. 0. 0. 0. 0. 0. -600. -1790. -2960. '3560. 66 BC 0. 0. 0. 0. 0. 0. 0. 0. -600. -1690. -30|0. '7950. 66 80 100. 1090. 150. 250. 0. 0. 0. 0. 0. 0. 0. 0. 66 BE 0. 0. 0. 0. 0. 0. 0. 0. -100. -1290. -1690. -3600. 66 81 50. 1590. 2830. 1960. 0. 0. 0. 0. 0. 0. 0. 0. 66 8K 0. -1560. 0. 0. 0. 0. 0. 0. -790. -6520. -6570. -5960. 66 BM -2680. -500. ~1990. -2680. 0. 0. 0. 0. 0. 0. 0. 0. 67 AZ 0. 1660. 3280. 2600. 0. 0. 0. 0. 0. 0. 0. 0. 67 88 0. 790. 1060. 1690. 0. 0. 0. 0. 0. 0. 0. 0. 67 BO —990. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. mal. Most of the increased runoff was near the coast because the water table there is near land surface and closely spaced streams give good surface drainage. Also, storm-sewer systems near the coast route storm runoff directly to the surrounding bays. Inland, where streams are fewer and where there is a thick unsatu- rated zone, runoff and natural evapotranspiration are minor. In the central part of the island, even storm water quickly infiltrates beyond the reach of plant roots and solar heat, and runoff from buildings and paved areas is disposed of through dry wells and re- charge basins; consequently, the irregular frequency of precipitation does not result in increased runoff. Thus, on the basis of observations, the assumed distribution MODEL-PROTOTYPE COMPARISONS 4 1 TABLE 3.——Net recharge (positive) and withdrawal (negative) at each model node used to simulate manmade historical stresses in western Long Island during the periods 1903—33, 1934—42, 1943—50, and 1951—63. Unstressed nodes are not listed—Continued LEVEL 1 LEVEL 2 LEVEL 3 YEARS-- 1903-33 1936-62 1963-50 1951-63 1903-33 1936-62 1963-50 1951-63 1903-33 1936-62 1963-50 1951-63 NODEL NODE CUBIC NETHES PER DAY CUBIC METRES PER DAY CUBIC NETRES PER DAY 68 A” 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. '2580. 68 Ad 100. 700. 960. 0. 0. 0. 0. 0. -200. -600. -B60. '2290. 68 AV 0. 0. 0. 0. 0. 0. 0. 0. -200. -600. -750. -2190. 68 BC 250. 2630. 1690. 3280. 0. 0. 0. 0. -600. -26B0. -3360. -5960. 68 BE 150. 1090. 200. 100. 0. 0. 0. 0. -150. -1290. -l690. -3660. 6B 56 0. 0. 0. 0. 0. 0. 0. 0. -1790. -6960. -12620. -16900. 68 BK 50. 1660. 2290. 1690. 0. 0. 0. 0. -250. -1590. -1390. -5070. 68 BM 100. 1760. 2380. 1690. 0. 0. 0. 0. '500. -3680. -5220. -11920. 68 BO 0. 0. 0. 0. 0. 0. 0. 0. -6950. -3970. -6970. -6950. 69 AY 100. 500. 500. 0. 0. 0. 0. 0. 0. 0. 0. 0. 69 BE 0. 1160. 1760. 2330. 0. 0. 0. 0. 0. 0. 0. 0. 69 HG 1660. 8150. 11280. 11230. 0. 0. 0. 0. 0. 0. 0. 0. 69 BM 0. 1660. 1090. 600. 0. 0. 0. 0. 0. 0. 0. 0. 50 AS -500. -2980. '2680. '2980. 0. 0. 0. 0. '5960. -2580. '1990. '2580. 50 AU 0. 0. '500. -500. 0. 0. 0. 0. 0. 0. 0. 0. 50 AI 0. 0. 0. 0. 0. 0. 0. 0. -650. -990. -1390. -3680. 50 AV 0. 250. 350. 0. 0. 0. 0. 0. 0. '600. -600. '600. 50 BC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 50 BE 0. 0. 0. 0. 0. 0. 0. 0. -150. -1390. -1660. -3730. 50 BK 100. 1760. 2330. 1660. 0. 0. 0. 0. -250. -1660. -1660. -5170. 50 B" 0. 0. 0. 0. 0. 0. 0. 0. -500. -2730. -3230. -3970. 51 AI 300. 1160. 1990. 0. 0. 0. 0. 0. 0. 0. 0. 0. 51 BC 0. 0. -50. 1660. 0. 0. 0. 0. 0. 0. 0. 0. 52 A0 0. 0. 0. 0. 0. 0. 0. 0. -600. '690. -1190. -1660. 52 A0 0. 0. 0. 0. 0. 0. 0. 0. -600. -890. -1090 -1560. 52 AU 0. 0. '550. -1590. 0. 0. 0. 0. -150. -550. -550. -1660. 52 AV -300. -2730. ‘300. -300. 0. 0. 0. 0. 0. 0. 0. 0. 52 BC 550. 1160. 1690. 5370. 0. 0. 0. 0. -750. -1690. -2190. -6670. 52 BI 0. 0. 0. 3560. 0. 0. 0. 0. 0. 0. 0. -6B70. 52 BK 0. B90. 1690. 5960. 0. 0. 0. 0. 0. 0. 0. -6870. 52 BM -5960. -3970. -3970. -3970. 0. 0. 0. 0. -500. -2730. -3230. -3970. 53 SH -300. -2680. -300. -300. 0. 0. 0. 0. 0. 0. 0. 0. 53 BJ 0. 0. 0. 1690. 0. 0. 0. 0. 0. 0. 0. 0. 56 AN 100. 600. 6670. 1060. 0. 0. 0. 0. 0. 0. 0. 0. 56 AU 0. 0. '650. '1390. 0. 0. 0. 0. -150. -600. '600. '1190. 56 AH 100. 600. 300. 1660. 0. 0. 0. 0. -150. -500. ~500. -1690. 56 AV 0. 550. 700. 0. 0. 0. 0. 0. 0. -650. -790. '1290. 56 BA 0. 0. 0. 0. 0. 0. 0. 0. -600. -650. -B90. -2330. 56 8C 0. 0. 0. 0. 0. 0. 0. 0. -600. -550. -790. -2160. 56 BI 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -7650. 56 BM 0. 0. 0. 0. 0. 0. 0. 0. -1160. -650. -1060. -200. 56 80 -15900. '11920. '12620. -2980. 0. 0. 0. 0. -5020. -2060. -6720. ~890. 55 AT -250. -1990. -250. -250. 0. 0. 0. 0. 0. 0. 0. 0. 55 BB 550. 1160. 1660. 3870. 0. 0. 0. 0. 0. 0. 0. 0. 55 BF -250. -2330. -250. -250. 0. 0. 0. 0. 0. 0. 0. 0. 55 BM 0. 0. 0. 7650. 0. 0. 0. 0. 0. 0. 0. 0. 56 AL 100. 600. 3730. 990. 0. 0. 0. 0. 0. 0. 0. 0. 56 AH 100. 600. 6520. 1060. 0. 0. 0. 0. 0. 0. 0. 0. 56 A0 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -600. 56 AT -300. -2680. -300. -300. 0. 0. 0. 0. 0. 0. 0. 0. 56 AZ 0. 750. 860. 3080. 0. 0. 0. 0. 0. 0. 0. 0. 56 BA 0. 0. 0. 0. 0. 0. 0. 0. -300. -500. -500. -2980. 56 BB 0. 0. -150. 6770. 0. 0. 0. 0. 0. 0. 0. 0. 56 BC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -250. -6920. 56 BE 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. '1990. (fig. 35) is defensible, and the simulated response shown in figure 36 provides a better comparison with prototype head decline than the other two cases that were tried. However, figure 36 indicates that a better match to observed water-table decline could have been obtained with a stress distribution intermediate be- tween the one shown in figure 35 and a perfectly uniform distribution. The second historical stress was obtained from pumping records that show a large increase in ground-water withdrawals in Kings County between 1899 and 1919. A similar increase occurred in Queens County during the mid 1930’s and in Nassau County during World War II and the Korean War. Because of 42 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK TABLE 3.—Net recharge (positive) and withdrawal (negative) at each model node used to simulate manmade historical stresses in western Long Island during the periods 1903—33, 1934—42, 1943—50, and 1951—63. Unstressed nodes are not listed—Continued deteriorating water quality, many wells in Kings County were abandoned during the periods 1932—36 and 1940—42. For simulation, changes in pumping were assumed to occur instantaneously at 1903, 1934, 1943, and 1951. The complexity of this model stress (228 pumping areas in model levels 2 and 3, each changing discharge rates at four different times, table LEVEL 1 LEVEL 2 LEVEL 3 YEARS-- 1903-33 1936-62 1963-50 1951-63 1903-33 1936-62 1963-50 1951-63 1903-33 1936-62 1963-50 1951-63 NODE CUBIC METRES PER DAY CUBIC METRES PER DAY CUBIC “ETRES PER DAY 56 86 0. 0. 600. 3970. 0. 0. 0. 0. 0. 0. -350. ~3380. 56 BI 0. 0. 0. 990. 0. 0. 0. 0. 0. 0. 0. -650. 56 80 -9390. -l3060. -6260. '1560. 0. 0. 0. 0. -600. -600. -2780. -1990. 57 BE 0. 0. 250. 1660. 0. 0. 0. 0. 0. 0. 0. 0. 58 AR 100. 600. 600. 1690. 0. 0. 0. 0. 0. 0. 0. 0. 55 AV 100. 600. 350. 1290. 0. 0. 0. 0. '150. -500. '500. '1690. 5! BA 0. 0. 0. 0. 0. 0. 0. 0. 0. 0o 0. -l990. 56 BE 0. 0. 350. 5510. 0. 0. 0. 0. 0. 0. ~250. -5020. 56 86 0. 0. '990. 1390. 0. 0. 0. 0. 0. 0. -350. -3530. 56 81 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. '600. '3970. 58 8K 0. 0. 0. 0. 0. 0. 0o 0. 0. 0. 0. '9960. 56 BN 0. 0. '100. 9690. 0. 0. 0. 0. 0. 0. 0. -5370. 55 BO ~6690. -11770. '5660. -1660. 0. 0. 0. 0. 0. 0. 0. 0. 59 81 0. 0. 300. 2680. 0. 0. 0. 0. 0. 0. 0. 0. 60 A0 250. -990. -990. -1690. 0. 0. 0. 0. 0. 0. 0. 0. 60 AV 100. 600. 350. 1360. 0. 0. 0. 0. ~100. -600- -600. -1090. 60 BA 0. 0. 600. 7310. 0. 0. 0. 0. 0. 0. 0. ~6970. 60 81 0. 0. 0. 550. 0. 0. 0. 0. 0. 0. ~500. ~66T0. 60 BK -300. -2630. '300. ~300. 0. 0. 0. 0. 0. 0. 0. 0. 60 OH -11920. -11920. -0650. -990. 0. 0. 0. 0. 0. 0. 0. -2190. 60 El 0. 0. 0. 0. 0. 0. 0. 0. '200. -890. -600. -1060. 61 GM '10960. '11970. -6690. '2680. 0. 0. 0. 0. 0. 0. 0. 0. 62 BA 0. 0. 0. 1660. 0. 0. 0. 0. 0. 0. 0. '1560. 62 BC 0. 0. 0. 3630. 0. 0. 0. 0. 0. 0. 0. 0. 62 81 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. '600. 62 DJ 0. 0. 0. 1060. 0. 0. 0. 0. 0. 0. 0. 0. 62 BK 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -350. 62 BL -250. -2330. '250. -250. 0. 0. 0. 0. 0. 0. 0. 0. 62 BM 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -1190. 62 BO 0. 0. 0. 0. 0. 0. 0. 0. -200. -200. -600. -200. 62 DH 0. 0. 0. 0. 0. 0. 0. 0. '200. -860. ‘600. '960. 63 BF 0. 0. 350. 0. 0. 0. 0. 0. 0. 0. 0. 0. 63 EL 0. 0. 0. 2630. 0. 0. 0. 0. 0. 0. 0. 0. 63 ON ~10600. ~11670. -8600. -2660. 0. 0. 0. 0. 0. 0. 0. 0. 66 A0 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. '650. 66 A“ 100. 600. 600. 1690. 0. 0. 0. 0. -200. -600. -600. -1860. 66 AV 0. 0. 0. 0. 0. 0. 0. 0. -200. -600. -600. -1790. 66 BA 0. 0. 0. 1760. 0. 0. 0. 0. 0. 0. 0. ~790. 66 BC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -550. 66 BE 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -990. 66 86 0. 650. 790. 750. 0. 0. 0. 0. 0. -650. '790. '1290. 66 B” 0. 0. 500. 1360. 0. 0. 0. 0. 0. 0. 0. 0. 66 81 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -200. -990. 66 8K 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -960. 66 BM 0. 0. 0. 2730. 0. 0. 0. 0. 0. 0. 0. -3630. 66 80 -11920. -13910. '8960. -990. 0. 0. 0. 0. 0. 0. 0. '6720. 66 DP 0. 690. 1690. 1160. 0. 0. 0. 0. 0. 0a 0. 0. 66 ON 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -100. 65 BO 0. -2660. -2680. 1660. 0. 0. 0. 0. 0. 0. 0. 0. 66 AS 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -1590. 66 AT 0. 0. 0. 2630. 0. 0. 0. 0. 0. 0. 0. 0. 66 AV 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -l390. 66 Al 0. 0. 0. 1090. 0. 0. 0. 0. 0. 0. 0. -l360. 66 AV 100. 600. 650. 1560. 0. 0. 0. 0. 0. 0. 0. 0. 66 BE 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. '990. 3) cannot be adequately represented on a map. Nevertheless, the complexity of the prototype stress is considerably greater than the model stress. After being used for cooling, water from many wells was returned to the ground through basins or shallow wells. Before 1961, most sewage in Nassau County was disposed of through cesspools and septic tanks. Water MODEL-PROTOTYPE COMPARISONS 43 TABLE 3.—Net recharge (positive) and withdrawal (negative) at each model node used to simulate manmade historical stresses in western Long Island during the periods 1903—33, 1934—42, 1943—50, and 1951—63. Unstressed nodes are not listed—Continued LEVEL 1 LEVEL 2 LEVEL 3 YEARS-- 1903-33 193Q-b2 19‘3-50 1951-63 1903-33 l93o-‘2 19b3-50 1951-63 1903-33 193‘-¢2 19‘3-50 1951-63 WE— NODE CUBIC METRES PER DAY CUBIC IETRES PER DAY CUBIC METRES PER DAY 66 IO 0. 0. 0. -150. 0. 0. 0. 0. 0. 0. 0. 0. 66 OK 0. 0o 0. 1190. 0. 0. 0. 0. 0. 0. 0. -6§0. bl AU 0. 0. 0. 2030. 0. 0. 0. 0. 0. 0. 0. 0. 70 AV 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -960. 70 IA 0. 0. 0. 1190. 0. 0. 0. 0. 0. 0. 0. -9§0. 70 06 0. 0. 0. 50. 0. 0. 0. 0. 0. 0. 0. 0. 10 OK 0. 0. 0. 250. 0. 0. 0. 0. 0. 0. 0. 0. 70 IN 0. 0. 0. 10°. 0. 0. 0. 0. 0. 0. 0. 0. 71 AV 0. 0. 0. 9‘0. 0. 0. 0. 0. 0. 0. 0. 0. 72 AI 0. 0. 0. 11‘0. 0. 0. 0. 0. 0. 0. 0. '1090. 72 AV 0. 0. 100. 5170. 0. 0. 0. 0. 0. 0. 0. -‘970. 72 l" 0. 0. 0. 0. 0. 0- 0. 0. 0. 0. 0. '600. 73 BL 0. 0. 0- 700. 0. 0. 0. 0. 0. 0. 0. 0. 15 AI 0. 0. 0. 3330. 0. 0. 0. 0. 0. 0. 0. O. 16 AS 0. 0o 0. 0. 0. 0. 0. 0. 0. 0o 0. '3280. 76 OK 0. 0. 0. 13b0. 0. 0. 0- 0. 0. 0. 0. -960. 7| AS 0. o. 0. 15°. 0. 0. 0. 0. 0. 0. 0. '100. 7| DE 0. 0. 0. 1290. 0. 0. 0. 0. 0. 0. 0. '1190. 1. BK 0. 0. 0. 100. 0. 0. 0. 0. 0. 0. 0. -100. no AI 0. 0. 0. 300. 0. 0. 0. 0. 0. 0. 0. -350. 00 UK 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -100. 00 SI 0. 0. 0. 350. 0. 0. 0. 0. 0. 0. 0. -700. 01 IL 0. 0. 0. 150. 0. 0. 0. 0. 0. 0o 0. 0. .2 AS 0. 0. 0. 650. 0. 0. 0. 0. 0. 0. 0. -6§0. .2 IC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -350. 02 ID 0. 0- 0. 250. 0. 0. 0. 0. 0. 0. O. 0. I! 81 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -100. 53 BA 0. 0. 0. 150. 0- 0. 0. 0. 0. 0. 0. 0. 00 EL 0. 0. 0. 150. 0. 0. 0. 0. 0. 0. 0. 0. 5‘ SI 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -150. 0‘ BY 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. '150. 06 AT 0. 0. 0. 700. 0. 0. 0. 0. 0. 0. 0. 0. 56 AU 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -650. I. 91 0. 0. 0. 150. 0. 0. 0. 0. 0. 0. 0. '150. B. BY 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -1§0. 90 BY 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. '150. was returned to the ground in the model through 112 recharge areas, whose rates of recharge changed simultaneously with changes in pumping rate. Esti- mates of recharge are much less precise than estimates of pumping. On the basis of available information, the folloWing assumptions were made: (a) Recharge from cooling water equals 90 percent of water pumped for this purpose; (b) recharge from domestic and commer- cial water equals 20 percent of water pumped for these purposes in sewered areas; (c) recharge from domestic and commerical water equals 75 percent of water pumped for these purposes in unsewered areas; (d) the remaining water is lost to evaporation or discharged to tidewater and does not return to the ground-water res- ervoir; and (e) all recharge water goes to the shallow aquifer. Changes in islandwide recharge, pumping, and net stress are given for the period 1903—63 in figure 37. Pumping and recharge were simulated without streams. On western Long Island, where most of the pumping was done, the streams were mostly small; many of them had already disappeared by the time a regular stream-gaging program was begun. Thus, the contribution to ground water from diverted streamflow is largely unknown but is probably small. Inclusion of streams in this simulation was considered unneces— sary, but ommission of streams adversely affected model accuracy in some areas. Response to historical pumping and recharge is mapped in figures 38 and 39. Figure 38 and table 4 compare observed head changes with those measured on the model. Figure 38 shows good general agreement between model and prototype head changes, but many details are lost because of the coarse grid of the model. Local defects in simulation also result from the large time steps between changes in pumping rates. The dif- ference between prototype and model drawdown in northwest Queens County (fig. 38) indicates some type 44 200 I I I I -— 40 100 _ Recharge - 20 o o + + o F o o _ <>t x - o >. < — 20 E, D 100 — n. I: (I) Z 31' — 40 8 fi 200 — <1: E —60 o L“ z 5 o 9 300 - 80 3 m _I 8 Net stress\ _ 100 E Z 400 - r—— r ————— E '2 l ‘ m I - 120 "’ 3 I 8 I 500 — .————- E '- | — 140 u, w I 500 ' —————————————— Withdrawal — 160 700 I I I I I I 180 1900 1910 1920 1930 1940 1950 1960 1970 YEAR FIGURE 37.—Estimated islandwide changes in pumping, manmade recharge, and net stress between 1903 and 1963. These estimates were used in unsteady-state calibration of the model. They do not include water returned to the same node from which it is pumped. of model or data deficiency. Comparison of figures 38 and 39 suggests that this deficiency is due to in- adequate pumping data. Prototype data for 1961 (fig. 38) shows localized drawdown of 8 m (26 ft) and more in northwest Queens County. This drawdown is not seen in the model data for 1961 but is seen in the model data for 1942 (fig. 39). Apparently, pumping data for 1942—61 are incomplete, probably because drainage pumped from railroad tunnels was not in- cluded in pumping data. Model and prototype draw- downs for 1942 cannot be compared because of insuffi- cient prototype data for that year. The author did not attempt to modify the stress to obtain a better com- parison between model and prototype drawdowns. Near the north shore (northeastern Queens County, for example) are many localized faults in the simulation, which can be seen in most model tests. These faults result from inability of the coarse model grid to match the fine-scale variations in boundaries. However, ice- margin deformation of the sediments along the north shore creates local barriers to ground-water flow that were not modeled. The general trend of model drawdown in Kings and Queens Counties, where most of the pumping on Long Island was done, matches the overall pattern in pro- ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK totype drawdown quite well, not only in 1961 (fig. 38) but also at several other times as well. If the differ- ences between the 1903 prototype water table and the steady-state model results in these counties (fig. 29) had been the result of poor model design, one would expect the unsteady-state model response to differ from prototype response by 50—100 percent, as was seen in the steady-state comparison. Averaging prototype drawdowns over areas of several square miles results in better agreement between prototype and model drawdowns than is shown in figure 38. Good compari- son of unsteady-state model and prototype response is evidence that the discrepancy in the comparison of steady-state model and prototype response is chiefly the result of pre—1903 pumping, which the steady-state model did not simulate. In the preceding test, the model was operating in the unsteady-state mode without natural recharge. Model streams were not flowing. The simulation is noticeably inaccurate where it does not account for diverted streamflow. In prototype situations, where wells were close to streams, they received part of their discharge from diverted streamflow. Wells 36, 37, 45, and 47 (table 4; fig. 40) are examples ofthis type of inaccuracy. SUMMARY AND CONCLUSIONS Problems in water resources evaluation that cannot be analyzed directly can be analyzed through model simulation. The Long Island ground-water reservoir was simulated by a three-dimensional analog model. Experience has shown that ground-water flow in thick, anisotropic aquifer systems such as the system on Long Island cannot be adequately described by two- dimensional methods but can be satisfactorily de- scribed by a three-dimensional model. Boundaries of the Long Island ground-water reser- voir are three dimensional, and the resulting natural patterns of ground-water flow are three dimensional. When wells and other human influences affect only the upper surface of the ground-water reservoir, some of the three-dimensional aspects of the natural flow sys- tem can be ignored; but the present state of ground- water development on Long Island, which superposes a new three-dimensional flow pattern on the preexisting, three-dimensional, natural flow system, requires three-dimensional analysis. Three-dimensional analysis is not only more difficult than two- dimensional analysis; it is less certain because data on hydraulic conductivity normal to the strata are much less abundant than data on hydraulic conductivity parallel to the strata and because compensating errors make evaluation of three-dimensional simulation more uncertain than evaluation of two-dimensional SUMMARY AND CONCLUSIONS 45' 41000, 74 I00' EXPLANATION 6 I 1 Line of equal prototype water-table decline, E 1903-61 Interval, 2 metres (6.56 feet) i .__—-4.__——— l Line of equal simulated water-table decline, 1903—61 ; Interval, 2 metres (6.56 feet) i 0 5 MILES Hw—e—r—‘r-P—J 0 5 KILOMETRES 45' 40°3 ' v . 0 Base from US. Geological Survey, series: New York, 1957; Newark, 1947 ed decline in water table between 1903 and 1961 on western Long Island with observed decline. FIGURE 38.——Comparison of simulat (Prototype data modified from Perlmutter and Soren, 1962.) simulations. when stresses cause significant changes in saturated Model-prototype comparisons indicate that this thickness of the ground-water reservoir. Any change in saturated thickness causes a change in an aquifer’s model simulates the Long Island ground-water reser- transmissivity that this modeling technique cannot voir adequately, but that care is required in modeling some types of stresses. Good results cannot be obtained simulate; when the change exceeds 10—15 percent of 46 ANALOG-MODEL ANALYSIS OF REGIONAL THREE-DIMENSIONAL FLOW, LONG ISLAND, NEW YORK o , 45‘ 4 1o 00, 74 1mo EXPLANATION 2 Line of equal head decline, 1903—42 Intervals, I and 2 metres (3.3 and 6.6 feet) 0 SMILES l l E l g 2 l l 5 KILOMETRES 45’ o 40 30’ Base from US. Geological Stir , ,(lOVO New York, 1957; Newark, 1947 S. FIGURE 39.—Simulated decline in water table due to pumping on western Long Island between 1903 and 1942. the total saturated thickness (about 15 m or 50 ft of drawdown for most of Long Island), the error resulting from the divergence of prototype and simulated transmissivity becomes significant. Offshore head measurements in the model are not reliable; boundary conditions there are not well understood. Several dif- ferent circuits were used to simulate stream-aquifer relationships, but because these circuits were de- veloped empirically, not on the basis of open-channel flow equations, the usefulness of each type of stream circuit is limited to a few stress situations. Extremely localized stresses near the mouths of streams can give REFERENCES CITED 47 50 30 190 . 120 I40 150 LONGQW" SLANDT'W 'ffiii" """ ..... . ,_i ..,.i,.,~S‘0u.vD. .. Weak. £1. » - 73.332 «4H .n._y_\/§7/mw\g ,3“; ,..,An ,. .1 Wm ' . ,.W_.. ~30. .. 2._. . . 1.1 429,3401.411.3549" % C " . ’28: ‘ W3; Qif mil”; 1o 15 MILES AIIlLANT 5 10 15 KlLOMETRES‘. l .i . , , A, l r .. Base from U.S. Geological Survey, l:250,000 series: Hartford, 1962; New York, 1957; Newark, 1947 EXPLANATION .10 Location of well 10 FIGURE 40.—Locations of wells used for water—level changes in table 4. tion, and calibration is predictive capability. The ulti— mate purpose of the model is to predict response of the TABLE 4.—Comparison of model and prototype water-level changes for selected wells between 1951 and 1.963 Prototype Prototype change Model change change Model change Well1 (m) (m) Well (m) (m) 1.7 26 _____ —2.0 —1.8 to —2.4 4.4 .10 to —.40 0 to 31.0 0 to .80 4.0 41.2 2.0 to 3.0 . -.60 4.8 to 5.8 . —1.8 4.0 to 5.0 . — 50 to .60 1.2 to 2.0 . 0 to <40 .80 to 1.0 . 0 to 4.20 .10 to 7.60 . 1.0 to 1.8 0 to <60 . 1.0 to 1.8 7.60 to v.80 . .80 to 1.2 — 1.8 to —3.0 . .80 —1.4 to -2.4 . .40 to .50 —1.4 to -1.6 40 __________ .0 .20 to .40 —2.2 to —2.6 41 __________ .40 0 to .40 -.24 42 __________ .30 .20 0 to —.24 .40 .20 to .30 0 to v.18 .30 .20 to .30 —1.0 —.40 .20 —2.4 to —2.6 .0 0 to .02 ~ 6 —.03 .22 to .26 —1.2 .03 .14 to .16 —2.0 .10 .12 to .14 —1.4 to —2.0 .80 .04 ‘Well locations shown in figure 40. 2Positive changes indicate increasing water changes indicate decreasing water levels. 3Range of values indicates that prototype well lies between two model nodes having different changes in water level. levels between 1951 and 1963; negative a distorted picture of stream discharge with almost any stream circuit. The apparent inability of the steady-state model to match the 1903 water table in western Queens County is shown (by good unsteady performance in that area) to result from pumping interference in 1903, not from incorrect conductivities or boundaries in the model. This model, however, cannot simulate the fine struc— ture of the hydrologic features in the north shore area; predictive results near the north shore may not be satisfactory. The desired end product of model design, construc- ground-water flow system to future stresses. Three types of stresses are considered: (a) Natural stresses, such as prolonged drought; (b) stresses caused by human activity, which are unforeseen or unplanned, including changes in recharge rate that result from paving and other construction activities such as dams, quarries, landfills, and recharge basins; and (c) planned water-management schemes. Examples of water-management alternatives are discussed briefly by Cohen, Franke, and Foxworthy (1968, p. 94—105); two plans are discussed exhaustively in Greeley and Hansen (1971) and Holzmacher, McLendon, and Mur- rell (1968). Several examples of each type of stress have been modeled. Results of these model tests and a description of the hydrologic and electrical assump- tions underlying the tests are contained in other re— ports. REFERENCES CITED Bermes, B. J ., 1960, An electric analog model for use in quantitative hydrologic studies: U.S. Geol. Survey open-file rept. Burr, W. H., Hering, Rudolph, and Freeman, J. R., 1904, Report of the Commission on additional water supply for the city of New York: New York, Martin B. Brown Co., 980 p. Cohen, Philip, Franke, O. L., and Foxworthy, B. L., 1968, An atlas of Long Island’s water resources: New York Water Resources Comm. Bull. 62, 117 p. Cohen, Philip, Franke, O.L., and McClymonds, N. 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Survey Water-Supply Paper 1768, 119 p. Salisbury, R. D., 1902, Description of New York City: U.S. Geol. Survey, Geol. Atlas, Folio 83. Skibitzke, H. E., 1961, Electronic computers as an aid to the analysis of hydrologic problems: Internat. Assoc. Sci. Hydrology, Pub. 52, p. 706—742. Soren, Julian, 1971, Ground-water and geohydrologic conditions in Queens County, Long Island, New York: U.S. Geol. Survey Water-Supply Paper 2001—A, 39 p. Suter, Russell, de Laguna, Wallace, and Perlmutter, N. M., 1949, Mapping of geologic formations and aquifers of Long Island, New York: New York State Water Power and Control Comm. Bull., GW—18, 212 p. Swarzenski, W. V., 1963, Hydrogeology of northwestern Nassau and REFERENCES CITED 49 northeastern Queens Counties, Long Island, New York: US. Veatch, A. C., Slichter, C. 8., Bowman, Isaiah, Crosby, W. 0., and Geol. Survey Water-Supply Paper 1657, 90 p. Horton, R. W., 1906, Underground water resources of Long Is- Upham, Warren, 1879, Terminal moraines of the North Atlantic ice land, New York: US. Geol. Survey Prof. Paper 44, 394 p. sheet: Am. Jour. Sci., 3d ser., v. 18, p. 81—92, 197—209. Walton, W. C., and Prickett, T. A., 1963, Hydrogeologic electric Upson, J. E., 1966, Relationships of fresh and salty ground water in analog computers: Am. Soc. Civil Engineers Proc., Jour. Hy- the northern Atlantic Coastal Plain of the United States: US. draulics Div., v. 89, no. HY6, p. 67—91. Geol. Survey Prof. Paper 550—C, p. C235—C243. Wilson, J. W., III, 1970, A Hele-Shaw model for the study ofthe Long 1970, The Gardiners Clay of eastern Long Island, New Island ground water system: Cambridge, Mass, Massachusetts York—a reexamination: U.S. Geol. Survey Prof. Paper 700—B, Inst. Technology, unpub. M.S. thesis, 89 p. p. B157—B160. Woodworth, J. B., 1901, Pleistocene geology of portions of Nassau UHS Geological Survey, 1972, Water resources data for New York, County and Borough of Queens; New York State Mus. Bull” 110, Part 1, Surface water records, 1971: US. Geol. Survey open-file 48, p. 618—679. rept., 302 p. :>U.s. GOVERNMENT PRINTING OFFICE: 1976 - 789-025/26 $5676 7 DAYS M] U,c]€3 The Structure of a Turbulent Flow in a Channel of Complex Shape # GEOLOGICAL SURVEY PROFESSIONAL PAPER 983 {WWW ‘ CH * 1'???“ kun~ “x e ‘ 'v Q ‘976 if q 1B The Structure of a Turbulent Flow in a Channel of Complex Shape By H. J. TRACY GEOLOGICAL SURVEY PROFESSIONAL PAPER 983 UNITED STATES GOVERNMENT OFFICE, WASHINGTON:1976 UNITED STATES DEPARTMENT OF THE INTERIOR THOMAS S. KLEPPE, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Tracy, Hubert Jerome, 1918- The structure of a turbulent flow in a channel of complex shape. (Geological Survey Professional Paper 983) Bibliography: p. 24. Supt. of Docs. no.: I 19.16z983 1. Turbidity. 2. Channels (Hydraulic engineering) 1. Title. II. Series: United States Geological Survey Professional Paper 983. QE75.P9 no. 983 [GB665] 557.3'08s [532’.517] 76—608249 For sale by the Superintendent of Documents, US. Government Printing Office Washington, DC. 20402 Stock Number 024—001—02875—1 CONTENTS Page Abstract __________________________________ i ____________________________________________ 1 Introduction __________________________________________________________________________ 1 Acknowledgments __________________________________________________________________ 1 Preliminary considerations ____________________________________________________________ 2 Equipment ____________________________________________________________________________ 2 Procedure ____________________________________________________________________________ 3 Results ________________________________________________________________________________ 5 Distribution of longitudinal mean velocity __________________________________________ 5 Distribution of normal turbulent stresses ____________________________________________ 7 Distribution of turbulent shear stress ______________________________________________ 7 Secondary motion pattern __________________________________________________________ 15 Origin of the secondary motions ________________________________________________________ 16 Role of the secondary motions __________________________________________________________ 19 Conclusions __________________________________________________________________________ 23 References cited _______________________________________________________________________ 24 ILLUSTRATIONS Page 1. Schematic drawing showing components of turbulent stress on an elementary particle ________________________________ 1 2. Schematic drawing of test conduit ________________________ ,_ _______________________________________________________ 2 3. Schematic drawing of channel section ____________________________________________________________________________ 4 4. Graph showing mean pressure along channel ______________________________________________________________________ 4 5. Graph showing distribution of longitudinal velocity near wall ______________________________________________________ 5 6. Graph showing distribution of longitudinal velocity away from wall _________________________________________________ 6 7.—12. Graphs showing distributions of turbulence quantities: 7. u’/U _______________________________________________________________________________________________________ 8 8. v’/U _________________________________________________________________________________________________________ 9 9. w'/U _______________________________________________________________________________________________________ 10 10. WIU>1<2 _____________________________________________________________________________________________________ 11 11. W/U>1<2 _____________________________________________________________________________________________________ 12 12. WUJ _____________________________________________________________________________________________________ 13 13. Graph showing comparison of velocity gradient, turbulent shear-stress, and correlation coefficient ____________________ 15 14. Graph showing distributions of correlation coefficients W/u’v’ ______________________________________________________ 16 15. Graph showing distributions of correlation coefficients W/u’w’ ______________________________________________________ 17 16. Chart showing secondary motions in channel ______________ ' _________________________________________________________ 18 17. Graph showing distribution of diff -__.‘ ______________ -_ ___________________________________________________________ 20 . . . (92 (v2—w2) 18. Graph showmg variatlon of 6y dz __________________________________________________________________________ 21 19. Graph showing balance of first eduation of motion at y/d=0.08‘ ______________________________________________________ 22 20. Graph showing distribution of sum of turbulent shear forces __\ ______________________________________________________ 23 SYMBOLS C =constant used to describe velocity variation d=half height of channel, 6 in. (15.2 cm) D=height of channel p=piezometric pressure; Pm is pressure of measuring station R=hydraulic radius, ratio of cross-sectional area to section peri- meter t=time U, V, W=mean velocity parallel to x, y, z directions, respectively Ua=maximum value of longitudinal mean velocity in the channel U* =“friction” velocity, VTo/p ufv, w=instantaneous values of velocity fluctuations parallel to the x, y, 2 directions, respectively u’, v’, w’=root mean square of velocity fluctuations u, v, w, respec- tively x =longitudinal coordinate along channel, x=0 correspondents to test section y=vertical coordinate, y=0 corresponds to channel floor z=1ateral coordinate, z=0 corresponds to channel sidewall §=rotation in y—z plane ,u.=dynamic viscosity p = density To=average shear stress on boundary v=kinematic viscosity, 14./p III THE STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE ABSTRACT Measurements of the Reynolds stresses and the mean motion pat- tern were made in a uniform turbulent motion in a conduit consist- ing of a large, nearly square section joined by a smaller rectangular section. The results indicate that the boundary shearing stress is nearly constant over large segments of the boundaries. It is shown that the magnitudes of the lateral and the vertical components of turbulence are not the same near a boundary and that the compo- nent normal to the boundary is smaller than the component parallel to the boundary. The difference in the two components in the corner regions of the channel produces secondary mean motions in the plane of the channel section. The strength of the motion depends upon the angle subtended by the corner. V The magnitude of a component of turbulent shearing stress is a function of boundary proximity. In the corner regions, the effect of the combination of the two walls is to create large shear stress gra- dients, or forces. The forces are frequently larger than those of the pressure. Depending upon the variation of the mean streamwise ve- locity, the shear force may either oppose or act in the same direction as the pressure force. A principal function of the secondary motions is to transfer momentum into the corner regions and, elsewhere, to compensate for the excess force due to the shear gradients. In the absence of the secondary motions, the fluid must stagnate and separate from the boundaries in certain regions and be greatly accelerated in others. The secondary motions are conventionally described in terms of symmetrical rotations in cells bounded by the corner bisectors. The measured motion pattern is at variance with this View, unless the symmetry is confined to a very local region. INTRODUCTION The mean flow characteristics are usually the ulti- mate concern of those who deal with the movement of fluids in open channels and in closed conduits. Often, engineering solutions of satisfactory accuracy may be obtained from equations of the Manning or Chezy type, or from one—dimensional energy and momentum con— siderations. As the body of experimental information grows, however, it becomes increasingly evident that the rational interpretation of many of the phenomena that are encountered depends upon a better knowledge of the internal structure of the flow than is presently available. In particular, much of the current work in this field is devoted to an understanding of the role of the turbulent fluctuations in shaping the mean flow field. Presently, comprehensive data are limited to simple examples of turbulent flow. These include (1) a two- dimensional flow (Laufer, 1951), (2) an axially sym- metrical flow (Laufer, 1954), and flow in (3) a square conduit (Brundrett and Baines, 1964), (4) a rectangu- lar conduit (Tracy, 1965), and in (5) a trapezoidal con- duit (Rodet, 1960); all examples are for a uniform flow condition. The present study was carried out in a channel having a boundary form more complex in con— figuration than any of those listed above. Its principal added feature is a corner subtending an angle greater than 180 degrees. In section, the test channel consisted of a larger rec- tangular channel joined by a smaller rectangular overbank channel. The selection of this arrangement was influenced by the procedures commonly used in natural stream channel flow computations. The section of natural stream channels is frequently subdivided, and each subchannel is subsequently treated as an in- dependent entity for flow computation purposes. The subdivisions are usually made at major changes in boundary alignment and at points on the boundary at which the boundary roughness changes significantly. The test data, though restricted in application by the somewhat idealized shape and uniformity of the labo- ratory channel, and by its smallness, should neverthe- less yield information relevant to the validity of the subdivision procedure. The objective of the investigation was a study of the turbulent and the secondary mean motions generated in the larger of the two channels, and an evaluation of the effect of the various corners of the section in terms of the momentum transport engendered by the mo- tions. To this purpose, measurements were made of the mean motions, both primary and secondary, and of the relevant statistical quantities of the turbulence over the section. These, when substituted into the equations of motion, can be expected to show the manner in which a given flow adjusts to the configuration of its boundaries, even though many of the mechanisms by which this is accomplished are yet unknown. ACKNOWLEDGMENTS The study was carried out in a test facility located in 2 STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE the hydraulics laboratory of the Georgia Institute of Technology, under a cooperative agreement with the Geological Survey, U.S. Department of the Interior. D. W. Hicks assisted in the collection of the test data. PRELIMINARY CONSIDERATIONS The continuity equation and the Reynolds equation in rectangular coordinates for incompressible flow may be written as follows: 311%; 3—?= pg: 345+ vzv prggg 2.2:... <3) 3—3V=—— -p<8> The abbreviated equations describe the motion to be considered here and, except possibly for the terms in- volving the Viscosity, may not be further simplified. The viscous terms are of relative significance in a fully p? plW va _‘_ pW p? pm d _ _ Y )‘ puw PUW va’ Y dz 2 _L | x I‘ dx l FIGURE 1.——Components of turbulent stress on an elementary particle. developed turbulent flow only in regions very close to a boundary. EQUIPMENT Test Conduit.—The experimental measurements were made in the closed—circuit air tunnel shown schematically in figure 2. A cross section of the test channel is shown in figure 3. The test channel was constructed of commercial aluminum plate and standard aluminum structural shapes. The transition section at the entrance to the channel and at its end were formed from aluminum sheet. The return section and the upstream and downstream turn boxes were constructed of interior grade plywood. The measurement cross section was lo- cated 84 ft (25.6 m) downstream from the end of the upstream transition section. Air was supplied to the tunnel from a centrifugal blower powered by a 15 horsepower (11.2 kW) variable-speed direct-current motor. Blower speed, over a continuous range, was controlled by variations in the current supplied to the motor. The variable speed feature of the motor and blower was utilized for inplace calibration of the hot-wire probes used during the investigation. Hot-wire equipment.—A commercially available two-channel DISA Electronics1 constant-temperature hot-wire instrument was used during the study. Each channel consisted of a 55 D 01 anemometer unit, a 55 D 10 linearizer, and a 55 D 25 auxiliary unit. Outputs were measured with a 55 D 30 DC meter and a 55 D 35 RMS meter. A model 823 Fluke voltmeter, in conjunc- tion with a wave generator, was used as a voltage ‘The use of brand names in this report is for identification purposes only and does not imply endorsement by the US. Geological Survey. PROCEDURE 3 ’_ Turn vanes on / _/ 9" radius / Screens Turn vanes on Return section 24" x 24" Transition section P|enum chamber FIGURE 2.—Schematic of test conduit. standard for the calibration of both the AC and the DC DISA meters. The hot wires were either 0.0001 in. (0.0025 mm) or 0.0002 in. (0.0051 mm) diameter platinum wire and were used either singly or in x arrays depending upon the variable to be measured. Wire length for the single-wire probes was 0.030 in. (0.76 mm), and for the x arrays, 0.042 in. (1.06 mm). The x array wires sub- tended a central angle of 90 degrees and were sepa- rated by a distance of about 0.020 in. (0.51 mm). The wires, in both cases, were supported by fine sewing needles projecting from one end of short lengths of small diameter brass tubing. Traversing device—The probes were traversed over the channel section by independent vertical and hori- zontal mechanisms. Vertical movement was registered on scales attached to rack-and-pinion mounted plates inserted into the two vertical faces of a transparent working section on one side of the channel at the measurement station. Horizontal movement was measured on a sliding scale extending through and perpendicular to the plates. The probe support was fas— tened to the end of the sliding scale. Zero readings of the traverse scales were found by placing the probe tip arbitrarily close to the vertical and horizontal walls and by then measuring the dis— tance between the tip and its image in the appropriate wall on an ocular micrometer. The traversing scale reading corresponding to one-half of the observed dis- tance marked the location of the wall. PROCEDURE The test channel was constructed so that its axis of symmetry ‘was vertical, with the smaller channel above the larger. Cartesian coordinates are used for point location and are orientated with x along the length of the channel, y in the vertical direction, and z horizontally directed. For economy in the required number of figures and for ease of comparison, the measurements in the upper and in the lower halves of the larger channel are often shown together. For this purpose only, the origin of coordinates for y andz for all data in the upper half of the channel is located at the upper left corner of the channel. For data in the lower half, the origin for y and z is the lower right corner. For any other purpose, only the lower origin is used, and y increases continuously from the lower to the upper boundary. For x, the origin is at the measuring station and is positive in the downstream direction. The root-mean-square values of the turbulent components in the x, y, and 2 directions are denoted by u’, v’, and w’. The height of the lower channel is D. The half- height, d, is used as a reference length to nondimen- sionalize the location of the points at which data were taken. The channel was Sufficiently long (L/D greater than 80) for full development of the flow at its downstream end. Velocity measurements were made on each side of the axis of symmetry to verify that the motion was symmetrical with respect to the axis. All tests were made with the maximum channel velocity maintained constant at 75 ft/s (22.9 m/s), corresponding to a Reynolds number of about 440,000, usingD as the ap- propriate length. The longitudinal mean pressure was measured from piezometer taps located every 3 ft (0.91 m) along the channel for the last 45 ft (13.7 m) of length. The results are shown in figure 4. The pressures are referenced to the pressure at the measuring station, pm. Mean velocities were measured by small diameter total head tubes used .in conjunction with wall piezometers and by hot wires. The total head tubes 4 STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE Va" aluminum plate 4" x 158" X Vs" aluminum channel \\\\\\\\\\\\\\‘ ’ \\\\\\\\\\\‘ § § N Dimensions are in feet and inches—1 inch=25.4 mm 1‘/a" x1‘/z"x'/a" aluminum angle ,L 12%" FIGURE 3.—Channe1 section. were either 0.035 in. (0.89 mm) or 0.020 in. (0.51 mm) in diameter. The smaller diameter tubes were used for measurements in the vicinity of the' wall. The longitudinal mean velocity measurements were corrected for the effect of the turbulent velocity fluctu- ations by the relation _2' _2 —2 U (corrected) 2 U(measured)\/1_ll‘]1 2 (measured) Hot-wire measurements, except those for V and W, were obtained by standard techniques described by Schubauer and Klebanoff (1946), Hinze (1954), and 150 100 / P-Pm , IN PASCALS 5° / 0 -10 ‘20 -30 —40 -50 x/2d FIGURE 4.—Mean pressure along channel. Rodet (1960). The measurement of V and W follows from the geometric relationships between U, V, and W and their relative magnitudes and from certain characteristics of the hot wire. These are outlined below. The secondary velocities are at right angles to the velocity, U, and are ’small relative to U. Their effect is a change in the local direction of the mean flow from the direction parallel to U. The angular deviation, in radian measure, from the U direction is V/U in the x-y plane and W/U in the x-z plane. The heat loss from a hot wire is a function of the magnitude of the component of velocity normal to the wire. The heat loss from each of two wires which are arranged in an x configuration and which are inde- pendently maintained at a constant temperature thus depends upon the degree to which each wire is normal to the flow, or upon the angle which each subtends to the flow. Since the position of each wire relative to the other is fixed, a rotation of the array to increase the exposure of one of the wires will decrease the exposure of the other and thus change the heat-loss characteris- tics of each wire. Correspondingly, a change in the di- rection of the flow with the array in an unchanged angular position will have the same effect. Hence, a given array may be calibrated to sense a change in the angular direction of the flow by a procedure in which the heat loss difference between the two wires is de- termined as a function of flow angle and velocity. After calibration in this manner, the probe may be inserted into the flow and traversed throughout the section, maintaining the array in an invariant angular orien- tation. The difference between the losses can be related to V/U for the array placed in the x-y plane and to W/U for the array in the x-z plane by the results of the cali- bration. On the other hand, the directional sensitivity of the x array probe type was a source of considerable incon- RESULTS 5 venience during the measurement of the turbulent shearing stresses pit—1;, pm, and pm. The measure- ments require that each wire of the array subtend the same angle with respect to the mean flow direction at each measurement point, which necessitated a point- to-point alinement of the angular position of the array to correspond to the variations in mean flow direction due to the superposed secondary motions. Equal volt- ages through each of the two matched wires indicated the proper setting to place each wire at the same angle to the mean flow. The response of the arrays to the normal stresses pfiandpfiis less critically dependent upon probe orientation. Hot wires placed close to a boundary are affected by heat transfer into the boundary. The transfer is vari- able, depending upon boundary distance. Some com- pensation for the effect is provided by the constant- temperature feature of the mode of operation, which allows the transfer, and therefore the slope of the voltage-velocity relationships upon which the turbu- lence computations depend, to remain somewhat con- stant at a given wall distance, irrespective of velocity variation. Also, the large mean velocity gradients near a boundary are also a source of error. When parallel to the boundary, the wires of a two-wire array are ex- posed to velocity differences which may be quite large for wires separated by even small distances. When normal to a wall, the mean velocity distribution along the wires of single and two-wire arrays alike is nonuniform. Adjustments have not been made to the hot—wire data to account for the boundary effects. The data closer to the wall than about 3 mm must thus be con- sidered less reliable than elsewhere. RESULTS DISTRIBUTION OF LONGITUDINAL MEAN VELOCITY The variation of the mean longitudinal component of velocity over the left one-half of the nearly rectangular portion of the test channel is shown in figures 5 and 6. Each curve represents a traverse horizontally outward from the vertical wall. Velocity measurements close to the wall are shown in figure 5 and the remainder of the traverse to the channel centerline is shown in figure 6. The vertical location (y/d) of each traverse with respect to distance from the upper horizontal boundary or from the lower horizontal boundary is shown in the legend. Velocities in the lower quadrant of the channel are identified by open symbols. A slash mark through the symbol designates an observation in the upper quad- rant. The half-channel height, d, is 6 in. (152.4 mm). The distributions shown in figure 5 in the two parts of the channel superpose on the basis of y/d, except 0.7 I 06 IQ/ B/ e//8 / 0.5 ”ii (/8 13/ 0.4 —4 0 VALUE OF fin Us \K {gs OED\ “’f ll \. \ 0.3 I /, ° / ./// I 8 y/d O 1 .0 0 0.050 0 0.833 0 0.0333 A 0.500 ll 0.0167 0,2 A 0.333 0 0.00833 D 0.167 0 0.00500 0 0.00291 I 0 0.0833 Open symbol—origin at lower channel corner / Line symbol—origin at upper channel corner 0.1 0 0.01 0.02 0.03 VALUE OF z/d FIGURE 5.—Distribution of mean velocity near wall. near y/d = 1.0. The variation, to a good approx1mation, can be represented by the equation U _ y 3 U0 C( d) i with n equal to about 7.5. The curves in the two quad- rants of the channel diverge farther from the wall (fig. 6). The relatively greater number of observations near the horizontal boundaries tend to emphasize the differences in the flow in the two quadrants, whereas the differences are actually minimal outside a limited VALUE 0F% 0 1.0 0.90 0.80 0.70 0.60 0.50 0.40 STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE Prlojection 0f upper (Lerner—i i =4. 0 —o I 993-6 2 g——__-g 5% / fir /2{g—/2’”° ° ° ° —— —— 6 /WE . e '9‘“? / @fi—g \é:~\g 11/, 0 \ §:3\;a\ , 8/ /’é'— \é:\\4 N ‘—:g / [3/ A \A B/'51 \~ \\A \~ a/Q/ /e—~e\ \A\ ~a~-.§:;g / 8% /9/ I \a‘ /57'& /g O/f—Jk ,3 %§ /fl// 0 \G\ , a '_ _ \\ //: Q 9 699 /_ /— /,_./ m 99%. MHz/,6 / | "e / é/ 6/ /e/://'° : ° \ ‘6‘6\ ,9 / / 8 o/ l 0\ 9‘ é___e/ 9/ 9 \3‘ / 4/5, 9/ /’9 x e I \‘O ‘0 D / ,—-—-o\ ——e ‘ / I // 9/8» /8><<§LO: \8/ . _/ Q? A/ e/ | 9 9 _ 7 6’ My Aye/HR.-- / M o M 0/8‘ . o’eéégag/\\o\ e/ ,, -°\_0 _. 8/9 8 '0 /A//6 // / / /.e/ I O o // 8 37-0/0 Kwk 9 . m 44/ °\. _ _ l ’9 _ 8a a/8 O S/—el/ I /- / 9489-0 C'] /3‘> /<>’/ e \ 1 O (D ~9\ l ’ / 0 §;\\ O/é/O‘ ’v‘—\ G /— 9/ -—-O r \\ ©—-—-—=8<\ / ‘0 e\ / _® 9 e .0 O \ A Q \ / O 0/ e j?\&\ / 9" Q‘eAge 0\ \\\g /o / \ \e \ \ 0/0 e O\$§§ /’ e/ 6.3% /‘ A i, \ \‘\§ / /4/’ d\>§:\:~e‘ ¢// /4/ __A \g \ 1 A /6 g>< k :7 ‘ *6 al/ 6/? (Q\‘ ‘kéfi'b /Q Qfiié—r—A——-e— —- , . 5% L: ==-e-—-8 §\ © © 8 \ a a ______ _____9 CB 0\—% 9‘3 o 0 0.2 0.4 0.6 0.8 1.0 VALUE OF z/d FIGURE 7 .—Distribution of u’/U. RESULTS 9 0.09 O 1.0 CI 0.167 D 0.833 b 0.125 O 0.667 <7 0.0833 A 0.500 0 0.0417 A 0.333 0 0.0167 symbol-origin at lower channel symbol-origin at upper channel 0.08 0.07 0.06 1' VALUE OF U 0.05 0.04 0.03 of upper VALUE OF z/d FIGURE 8.—Distribution of v’/U. at the upper and lower corners, as for figures 5—8. The signs of the stresses, Where they depend upon the ver- tical coordinate, are assigned on the basis of the lower origin, with y increasing continuously from the lower to the upper boundary. The quantities pfipflw, and pm- are physically sig- l I x l nificant as tangential, or shearing, stresses, which re- sult from the turbulent interchanges of mass and momentum between neighboring flow regions. The concept, and its details, are well documented in hy- draulic literature. The exchanges, in all directions, lead to the stress system shown in figure 1. The sign of 10 W, lD VALUE OF 0.10 0.09 0.08 0.07 0.06 0.05 0 .04 0.03 STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE VALUE OF z/d FIGURE 9.—Distribution of w’/U. l | 1 A 0 Projection of upper corner—: A I r 6 A A I l] 6 A A A a a A [J o o o r 0 o o o’ O o 0 o A ‘6’”: 1:! \\g ’ \ l c! 9" \e / / \ l \\ / e\ o o e O/fioi'o‘fi O O‘\ O 0 0"/ i V / \e‘ \ O ‘\‘ 0 /\e 29” ° / O , O o 2/0 O \ 9\‘ 3,7 ,/0 IV a K. _D 0 —fl 9 0/8 9~—_9___9“>.\ // }/ ,1 y @ y e7 “ "e_'—‘e~~_~ 0‘,e/ g/”e— *3 ‘8 ‘ ’49‘ , ‘§$.¢>;;g 0/0/ /e/ 4/’ \\\% / / \‘\9 __—O/ -// /4/ 6 \9 “ \.__Q -’//6' [96’ 1:! /g ’— A \ Q‘ 'A .. \té A / ’0/ A A j ’ ’5— §~53 I /9/ A y/d : \9—9' 0 1.0 a 0.167 \\\/L\ 1: 0.833 0 0.125 _ __ ____ v 0 0.667 0 0.0833 \ ‘6 _e _— e 2————-<>———<> A 0.500 0 0.0417 \a-\O 0,—— A 0.333 0 0.0167 ‘\ [I 0.0083 *\o-——° D X a —0.8 v . 0\ V5“ . b b ‘ /|> /; (Ar A \ J 0/ > / ’g—AA§¥0\ A A 0 ga\ 4n / /a // \gy> : a :2? -0 4 / 2: A 0 0 $0 I g /D/ /”/_O~|fl/“’/ // \\ ° \‘ / / 0 °\ 0 _ f—u o b a /@ N/ / D \o a, \ k4) <4 // a/ fl/éal/ L/ u/qybAt 0301M.“ T\~° ::8 b / ’A a v unctlon / /A A/ ”:2/ /l D’/ ’6 o e] /————»-o -o ge/ 52:; / -0 E, 4% o ”wéfifé o a—v/O D/r o/o A ’9 A "___ — @gafia—IK/MzfiéNN-Nx n O U \ \ I \ D G U \o a a 0\ \ \ \0\ +04 (i \ \ 4 A x . \ \ [l \ \NO 0 \ 4 , \ \A \d \ ~<> —<> \\ é 0\ \Z \ \A 4 \A \ \a \ \~ O\\) \ \ a \A\ A- _A \ \ A +0.8 (3 ‘6 \\ \CL. \0\ \K_A \ 0\ o \Q\:A\\fl\ ‘\°\A \Tx§°~\\7& “Ah—2 V\\O m /8/ L, v 4; Lower halflof channel “'20 0.2 0.4 0.6 0.8 1.0 VALUE OF z/d FIGURE 10,—Distribution of mm 2. 12 M ‘0-4 0 0.667 VALUE OF—U STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE 1.2 Projection of upper | corner—ll I Upper half of channel Y/d O 1 .00 D 0.833 A 0.500 A 0.333 [I 0.250 CI 0.167 b 0.125 0 0.0833 0 0.0417 a 0.0167 I .° 00 0.8 §\0\ d\\§\\ D/ D/ 5/ .4. / ©/ / 0—0 0’ / l>/ I> 066 5/ \A\ 3\ Lower half of channel /n /u / / .r, g I 2% .L , l7 /0 \\ \ \ “\ \ 9 \A A Q\\ B\ O 3&&'\Q§\°\ \B\ § \<>\:Z:_9 - ?\§:§§E§R.A/;3/7 E\\;::g,4: o O 0.2 0.4 0.6 VALUE OF z/d FIGURE 11.—Distribution of IE/U* 2, 0.8 1.0 RESULTS 1 3 0.2 I l % v/d § 0 1.0 A 0.667 [1 0.333 0 0.0833 g CI 0.833 A0500 V 0.157 ¢> 0.0417 Open symbol-origin at lowerchannel corner 0 1 % Line symbol—c rigin at upper channel corner "2* V X g a 9 '5 a 6’“ a. a I l Cl '5 0 0 Q g A % 9 uJ G OB 0 By _I $ D g < C] > 'ffi I —0.1 ”v A % G \ — 0.2 0 0.2 O 4 0.6 0.8 1 .0 VALUE OF z/d FIGURE 12.—Distribution 0f 0.11—2/ U* 2. the stress is a function of the mean velocity gradient in the direction of the transfer. The nature of the transfer process is to produce a negative correlation between the two members of the shearing-stress terms for a positive gradient—that is, a velocity increasing in a positive direction outward from a boundary. The signs of the tangential stresses are related, also, to the rotational aspects of the stresses. Thus, each of the tangential stresses—and as well, the normal stresses—is opposed by its counterpart on the opposite, parallel face of figure 1. The tangential components in opposite directions along parallel faces are stress couples which tend to rotate the particle. The sign of the stress component indicates the angular direction of the rotational tendency, which can be shown to be a function of the velocity gradient normal to the stress couple. Because the stresses are negative for a positive gradient, they are shown with negative signs on figures 10, 11, and 12. The surface force due to a stress is the product of the stress intensity and the area of the face over which it acts. The resultant surface force on the particle of figure 1 due to a given stress component is the differ- ence between the oppositely directed forces on the op- posite, parallel faces, and is conveniently expressed in gradient form. The resultant surface force, per unit of volume, of a tangential stress is its gradient normal to the stress couple. For a normal stress, the resultant, also per unit of volume, is the gradient of the stress in the direction of the stress. The resultant of all surface forces due to the turbulent exchanges, per unit of vol- ume, in the x, y, and 2 directions are the turbulence terms on the right side of equations (2), (3), and (4). For the case of a uniform motion, they are given by the right side of equations (6), (7), and (8). The total intensity of shear is the sum of the turbu- lent stress and that due to direct Viscous action. The second is small relative to the first, except at locations where the mean velocity gradients are large. In the test channel, the gradients are large near the bound— aries. Elsewhere, the turbulent stresses are a close ap- proximation to the total stress. By ignoring the de— creasing portion of the turbulent stress distributions near the boundaries, the distributions of figures 10 and 11 may be projected to the boundaries to obtain an estimate of the value of the total stress at the bound- ary. The value of {7117/ U*2 projected in this manner to the vertical boundary of the larger section is remark- ably constant over almost the entire length of the boundary (the immediate corner regions are the ex- ception) and equal to 1.13. A corresponding projection of El U *2 to the upper and lower boundaries is simi- larly constant and equal to 1.17 and 1.11, respectively. Measurements made in the upper channel (not shown) yield boundary values smaller than these, equal to 0.61 on the horizontal boundary and 0.76 on the verti- cal wall. An average, obtained by weighing the bound- ary stresses for the large and small channel against peripheral length, is 1.01, which is a favorable com- parison between the average boundary stress com- puted from the hot—wire measurements and from the piezometric grade line. The comparison serves as a 14 general check on the hot-wire techniques used during the study and on the magnitude of the stress terms. It is suggested, moreover, that the apparent constancy of the boundary shear stress over large segments of the test channel periphery may be typical of flow in more complex channels. This observation is substantiated by the successful use of equations of the Manning or Chezy type in the large variety of channels to which they have been applied. Because of the dependency of the sign of the stresses upon a mean velocity gradient and because of the anal- ogy with laminar flow, in which the stress is directly proportional to the gradient, attempts have been made to relate the magnitude of the turbulent stresses to the magnitude of the velocity gradients, without complete success. An example is shown in figure 13, on which is plotted the variation of H/Uk 2, 6U/6y, and W/u’v’ for y/d = 0.167 in the upper half of the channel. The vari— ables are imperfectly correlated, and over a part of the length of the curves, 6U/6y actually is decreasing while EU is increasing. In explanation, Schubauer and Klebanoff (1951), point out that a fundamental difference between lami- nar and turbulent flow is the scale of the mixing, that for turbulent flow being much larger. Their measure- ments of correlation distance show that the large-scale components of the eddies occupy a large portion of the width of the channel. Their simplified model describes a transfer of energy from larger to successively smaller eddies, the action of viscosity becoming progressively greater with diminishing size. Because the largest ed- dies thus make the greatest contribution to the aver- age shearing stress, they suggest that the stress should be expected to depend upon a velocity gradient aver- aged over a distance, rather than upon the local gra- dient at a point. While the foregoing is reasonable, the selection of an averaging distance to reconcile the velocity gradients with observed values of the turbulent stress is not ob— vious. According to figure 13, the distance is evidently variable, depending upon location. It is also frequently __ 1") zero. In figure 11 and figure 6, for example, uw and 8—2] are perfectly correlated in the numerous instances where both are equal to zero (in addition to the obvious case at z/d = 1.0) at identical locations. It thus appears that a simple method of predicting the magnitude of the turbulent stress from the mean velocity variation ' is not at hand. The variation of 17w— and u_v over the section creates force components that frequently act in the same direc- tion as the pressure force—that is, a “negative” shear- ing force. Reversals in the direction of the forces occur (9W arm at changes in the sign of the gradients E and 72‘ STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE . . 6— Figure 11 shows many such locations for “gig for 0.7 \gx/ 3V vain: \hD / Isl-3 \C] A “'- 50 /A D\__/ \ O A’ zg\\o g /A”"A_—A/ O/m‘f—xmmo \_O\-A _l h g n— /e/ O -_O./ \. O/" —— / O// /A’/ N/0 00 0.2 0.4 0.6 0.8 1.0 VALUE OF z/d FIGURE Iii—Comparison of velocity gradient, turbulent shear-stress, and correlation coefficient at y/d = 0.167 in upper half of channel. coefficients are dependent upon Reynolds number (Laufer, 1951). The maximum values in figures 14 and 15 (about 0.4) are close to those obtained by Laufer at a similar Reynolds number in a one-dimensional flow, except at the 270-degree corner, where they are great— er in the case of LTB/u’v'. SECONDARY MOTION PATTERN The secondary motions in the section of the nearly square lower channel are shown in figure 16. The vec- tors of the figure are the combination of separate evaluations of V and W. The untipped end of each vec- tor represents the point at which the measurements were made, and the length of the vector is proportional to the velocity. A reference vector equal to 0.0133 U0 (1 ft/s, 0.305 m/s) is shown on the figure. The secondary velocity components are difficult to measure accurately because of their small magnitude. On the other hand, the measurements are relatively easy to obtain, and so each was repeated several times to minimize error sources, such as voltage drift. The void space in the center of the figure is an acknowledgment of a lower limit to the velocity signal separable from instrument noise and normal voltage drift. Although they probably are not zero, the motions in the region are small enough to be inconsequen- tial. Elsewhere, the components were compared on the basis of continuity, using the relationship BV/6y=—6W/62. From this standpoint, the measured motion pattern was reasonable everywhere except at the upper 90-degree corner, where the motions are small, and probably wall influenced, resulting in poor definition in this area. The secondary motions consist of one large cell in the upper and in the lower part of the channel and a small- er cell alongside each of the larger eddies. The adjacent cells are counterrotating. The magnitude of the mo- tions in the lower half of the channel are comparable to those of an earlier study (Tracy, 1965) in a narrow, rectangular channel at a Reynolds number of 96,000 and to those in a square channel at a Reynolds number of 83,000 (Brundrett and Baines, 1964). The Reynolds number of the present study is about 450,000. From this data, and the fact that the motions in the upper large cell near the 270-degree corner are larger than those in the lower cell by a factor of almost three, it appears that the boundary configuration in the vicin- ity of the motion is a more decisive influence upon the strength of the motion than is Reynolds number. It may be conjectured, also, that the effects of a given boundary feature are not entirely local. The differences between the secondary motions in the upper and lower 90-degree corner regions are probably an indication that the strong motions in the vicinity of the 270- degree corner affect those of the upper 90-degree corner. In any event, the measured pattern is at variance with the conventional View held of the motions. They are usually described in terms of symmetrical rota— tions in cells bounded by the corner bisectors, the rota- tion having the opposite sense in adjacent cells. The measured motions are symmetrical only in a local re- gion about the bisector of the lower corner, and because of the poor definition at the corresponding upper corner, they may also be locally symmetrical there. The motions at the 270-degree corner are divided into 16 STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE W u’v' VALUE OF- O.2 0.4 Upper half of channel Y/d a 0.167 0 0.0833 0 0.0417 a 0.0167 Lower half of channel 0.6 0.8 1.0 VALUE OF z/d FIGURE 14.—Correlation coefficient (IU/u’v’. two distinct circulations; interestingly, they are di- rected toward the corner along the boundaries and outward elsewhere, in contrast to the motions at the interior corners. The bisector, however, only approxi- mately divides the cells. The peculiarities in the distributions of longitudinal velocity of figure 6 are consistent with the measured secondary motion pattern. The exchange of fluid between the two parts of the channel of their junction is not zero. Fluid is trans- “ ported out of the larger channel at the center, and an equal amount is returned near the boundary. ORIGIN OF THE SECONDARY MOTIONS The secondary motions are believed to have their origin in the characteristic behavior of the normal stress componentsWandW in the corner regions of noncircular conduits. The typical unbalance of the components near a boundary has been outlined in an earlier section of the report. A connection between the normal stresses and the secondary motions can be established by a minipula- tion and combination of equations (7) and (8), which describe the forces and the resultant accelerations in the plane of the secondary motions. The pressure terms may be eliminated by the differentiation of each equa- tion with respect to the direction of action of the other and by the subsequent subtraction of one from the “other. A further use of equation (5) produces the follow- ing result: V5_y§+ 0§ 62 E92 +pW—z=g—:2pvu— 6y —2pv—w+a—yaz p(v2— w2) 2 2 +u(9—+ 5 ‘9 6—45 22,) (9) 6y2 whereg =g—W {gland 1s a measure of the rotation of a y z fluid particle about an axis normal to the y—z plane. Equation (9) may be obtained in an alternative fash- ion. Brundrett and Baines (1964) suggest that it can be derived directly by equating the rate of change of an- gular momentum of a volume of fluid—the terms on the left side—to the moments of the surface forces on the volume, which are the terms on the right side. A laminar, uniform state of motion is described by ORIGIN OF THE SECONDARY MOTIONS l7 0.4 0 VA\\‘9 k 0.3 O\ \ \4 \ \\\o o (a \ \\ \A \\O\\ 0.2 - (I §\ \0 \ \ \o\ \o 0.1 \\ A \ \\ 8 :\ a a ‘ \<> \o o-¥&—_ >*@ g \\ \\o O §\%\\6)\\:\\0\:8% -0 1 2:\ A?\ A \:2/_: I Upper half of channel ‘ Q\E>=’é> ~ —o.2 '5': We! (”5 o 1.0 o 0.250 .. m 33-22: 33-32;. 3 :- 2‘ ‘—= \\ . . :. éxe g =§o§< \\ 23::33 233:3 > 03 \V\A —D \ 0 \ \\A ‘0 D\ I h~o a o o 0‘2_”\ \ \ \0\ \ \ “x // :\ <> o 0 ' 0.1 \0\ K O\ \ . / // ,/ \ \ \o \ , 0 \b2: U\>K 0 8‘\® Q) (h a) g g\ 0/ [37410 ‘0 0 lfi =/ 3/ \:\ \\ égéfi -0.1 \ \ \.\\\A\7§ F O -0.2 \:“\\\2\'Z/ar/ .03 Lower halflofchannel \07 0.2 0.4 0.6 0.8 1.0 VALUE OF z/d FIGURE l5.—Correlation coefficient W/u’w’. the accelerative terms on the left of equation (9) and by the last term on the right. Using the laminar condition as a starting point, Maslen (1958) demonstrated math- ematically that if the secondary components are zero anywhere in a viscous motion, they are zero everywhere. Because they are zero at a boundary, the transverse velocities must vanish in a uniform, lami- nar flow. The terms involving the viscosity are thus counterproductive to the generation of the secondary motions. The relative importance of the terms containing (H—the first and second terms on the right of equation (9)—are difficult to assess experimentally because of the small magnitude of W and the probable measure- ment error. For the purpose of eliminating W as a possible cause of the secondary motions, it probably suffices to remark that the stress depends upon the existence of V and W (or, more strictly, upon their gra- dients) and not the reverse. It is to be noted, moreover, that the (W terms of equation (9) are the turbulent counterparts of the viscous terms and may reasonably be expected to behave in a parallel manner—that is, to retard the rotation of the fluid particles. To the extent that the latter conclusion is justified, the remaining term on the right side of equation (9), which is descriptive of the action due to the forces 172 18 STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE EXPLANATION ‘ ¢ i . ‘ ‘ ‘ 1 \ § 1 T Length ofvectorequal to 0.0133Uo . ' J J ' (1 ft/s or 0.305 m/s) \ \/ I f 1 l \ 1 . . . .\\\—~// 1 '1 I " —’ —‘ N ——————r”'\;—. / q. x ‘ x v x /' y» a,» \ /' 5 , I /' / / a>\ \ A J‘ , § f / / / / __. \ ' 0.2—H \ \ / f / / ~ H ‘ f f \ \ \ £ ‘ I f T 1 \ K t \‘ 4 J X l 0.4— \ H _ 4 + \ K x , x J I 1 . . K \ ‘\ - Q i ‘ ‘ I l ‘ l A \ d 05—“ ‘ ' * ‘ ‘ I I J J .. _ ‘ L \ K \ v. ._ I ’ I ‘ ,. . ‘ ~ t \ K \ o , ’ f . 0.8- .. . . . ~ » x ‘ - . , , . E >. LL 0 LU 1.0— ~ - v - w A 4 . , y 3 < > 0.8- 4 v > A ‘ ' , , - - \ i ‘ f t . . ‘ v , , , - x i 0 0.6 —f , ‘ ‘ * 4 ‘ I , ‘ \ \ t 1 a , \ i ‘ ' , , ‘ \ Q ? 04 j 4 ‘ ‘ J I J l ‘ \ h ‘ 1 I ‘ p p, / I ' I . 0 § 1 1 I i I / I I ' ‘ ‘ I f f 1 0.2 _T . / I I . ‘ __ _. I I f : ‘ / / / I § Q / I ‘ ‘ ‘ .. _. .. a I I 9 011'.-L.;;.a~».»».»~ .-E 0 0.2 0.4 0.6 0.8 1.0 VALUE OF z/d FIGURE 16.——Secondary motions in channel. ROLE OF THE SECONDARY MOTIONS 19 and 52—2, is evidently responsible for the existence of nonzero values of the accelerative terms on the left and thus for nonzero values of V and W. The magnitude of 5‘2 and W is a function of location, Reynolds number, and boundary configuration and roughness. It is re- 62 ('9sz equivalent in cylindrical coordinates) precludes a non- zero value of the term in an axially symmetric or two— dimensional flow. The observation that secondary mo- tions are not present in these types of flow is support for the conclusion just drawn. The variation of 172—? over the section of the large channel is shown in figure 17. The measurements of 172 at y/d=0.0016 in both the upper and the lower half of the channel appear erroneous, and the probable value of W—W at these locations is indicated as a dashed line. The principle function of figure 17 is to show that the velocity fluctuations in the plane of the channel section—v and w——vary in a consistent manner near a boundary, with the component of turbulence normal to the wall always being smaller than the component which is parallel to the wall, and that the typical vari- atzion will always produce a nonzero value of 6 6y02 The result of the combination of boundary effects on the variation of 62 63/62 the upper one-half of the larger channel. The correla- tion of the magnitude of the derivative with the mag- nitude of the secondary motions is good (see fig. 16). (UL—W) (or of its marked that the structure of (vz—wz) in a corner region. (ll—2—zU—é) is shown in figure 18 for ROLE OF THE SECONDARY MOTIONS The turbulent shear gradients, and thus the turbu- lent shear forces, become very large in the corner re- gions of the channel. Without the secondary motions, which compensate for the force excess, the motion pat- tern in the channel would be greatly different from that which actually exists. The role of the motions is thus an essential one. It is described by equation (6) which expresses the longitudinal force balance in the channel: fl) = _ 3_P 6U P(Vw+wa 62U 62U z 6x+M(ay_2+g) (6) (Bu—0+6W). 6y The terms on the left, excluding p, are the longitudi- nal acceleration of a volume of fluid. The terms on the right, in order, are the forces due to pressure, viscosity, and turbulent shear, all per unit of volume. The nega- tive pressure gradient indicates a decreasing pressure in the downstream direction. The negative turbulent shear terms are in recognition of the forementioned fact that the turbulence components normally corre- late in the negative sense. Despite their accelerative significance, and like the turbulent products, the terms on the left side of equa- tion (6) can also be interpreted as forces due to momen- 6U W, in which V is a volume rate of vertical flow per unit of area. As the volume is carried from one region to another—the U velocity generally being different in the two regions—it undergoes a momentum change per tum transport. Consider, for example, the term p V unit of volume equal to pg—Udy in the distance dy. In y contrast to a turbulent fluctuation, which is assumed to retain its U velocity throughout its migration, the volume transported by V undergoes a continuous change in U. The integral of the product of V and p%]dy is thus the rate of transport of momentum per unit of area as a result of the secondary motion V and is equivalent to the stress intensity due to the momen- tum exchange. The resultant surface force per unit of volume is the differential, with respect to y, of the inte- gral, which is pVg—U and which is the first term of 3’ equation (6). The viscous forces are small relative to the other forces except near a boundary where the velocity de- rivatives upon which they depend are large. At a boundary distance equal to 0.07d, the viscous forces are typically less than 3 percent of the pressure force. The viscous forces have been omitted from considera- tion at greater distances. Thus, not too close to the boundaries, equation (6) is a balance between the momentum transfer due to tur- bulence, the transfer due to the secondary motions, and the pressure force. Because the pressure force is everywhere constant over the section, a variation in one of the transfer forces must be accompanied by an opposite variation in the other. The forces have been evaluated from experimental data at y/d=0.0833 in the upper and in the lower parts of the section and are shown in figure 19. To facilitate comparison, the negative of the secondary motion trasnport forces have been plotted in the figure. (To be noted, also, is the division of each term of equation (6) by, the mass density, p, so that the force significance of each is lost. The result, however, is proportional to force.) 20 IN METRES SQUARED PER SECOND SOUARED W—wz, VALUE OF 1.0 0.8 0.6 0.4 0.2 —1.0 1.0 0.8 0.6 0.4 0.2 STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE VALUE OF z/d FIGURE 17.—-Distribution of 15—727. 51 0 Upper half of channel \A\\\B . \ z o e. 4E2. \N \ a \ \% \\\ CI %D\ \ \O\ a \\2\~D\D on \ \ | M I I l L D n H \ \Cl \‘~9 | __ Ox \ \a a—r—‘A —/63\ A a / \4\-a _A Mex \.\.; 4/34 .gw‘ \ ./ -o\—O \ \0\ \o \1‘0 / \=9<'0 \ \ >0\ I ‘0) o\ O\ K!) o'/ / \ \o / O \ /]Ch 0 \ O \‘O —/ / \ ‘ o o 8 O \\ / Y/d O 1.00 O D 0.833 . Lower half of channel g giggg ‘4 CI 0.167 A O 0.088 0 \ 0 0.0417 \4\\\ 0 0.0157 °\\‘9‘\ \ a A \R O\ \ \d\\o 5 L'\ \\ \‘A\\U (I \ \.o \ \n \\ \A \o o A \ 41\ \\ I\0‘*C n O O \ ‘O\ \\d ()\l \~ A _\A X \C]\ A\4IJ\A A Q Q A «A 0 \ a /| \O\ O\° \ a A] a a d 4 \ \o \\\v \\ a O \ a G a \\\D\\ \O\_O l O A A " o \o\ N‘O \O\ _ o\.2\ G/Sg—fla S U Q \\ \~__’_____ __ —_ —_ _—_— 0.1 0.2 0 3 0.4 0 5 0.6 0.7 0.8 0.9 1.0 1.1 ROLE OF THE SECONDARY MOTIONS 400 as\ 0 o'\ IS A . >4? 8\\ A O ‘A fin-s. =-- = \ -0 0 <5- 1» ‘9‘\ ‘\§ki‘0x_\_¢lb§& 87 o 5‘ D\ §~@\ §$M \D \ A ,0 \- I D\:\\f\ . / $6 \ /é /:§ 0‘ 0 \\> L\ —400 l\ \xt/ ~ 0 '5 ‘ I 5 ‘f g —800 5 / < > Y/d / o 1.0 0 0.667 A 0.503 332:. D O 167 0 00833 o 0 0.0417 \J/ O —1600 / —1700 0 0.2 0.4 0.6 0.8 1.0 VALUE OF z/d 2 (35—10 ). FIGURE 18.-—Variation of 6 6y62 22 STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE 60 A 0 l 6h 40 “ \ B \\ A\ A"'\A r: \ \ 5‘ \ 0 A ,x ___A\ 8 20 \\\ \ ’A‘ “ g (vw+2u)A?\ 0‘ ‘l 8 av 31 0\_ \‘ 0‘ \ 3W m a \%\ 0-\0\‘ (371'32 ) ,A n: E o \ \ \ o l/aA if; - / E ANear upper boundary 0 \ O\“ \fik “g 0 Near lower boundary \ \ / o A ‘0 Y/d=0.0833 \ ‘7\ I -20 A . 0 \ O ‘\ / / \A/ A \' / 4,1/ —40 0 0.1 0.2 0.3 0.4 0.6 0.7 0.8 0.9 1.0 1.1 0.5 VALUE OF z/d FIGURE 19.—Balance of first equation of motion at y/d=0.0833. The force variation shown in figure 19 is a function of the details of the motion pattern in the vicinity of the variation. The motion pattern is described primar- ily by boundary geometry, with Reynolds number of secondary importance. The extremes of variation of figure 19 occur near points of change in boundary alignment, or corners. To the extent that the corners are isolated from the direct influence of other corners, the motions and the resulting forces near each are “mostly” representative of the corner, although they are affected to some degree by every element of the boundary, however distant. The 90—degree corners, for example, are charac— terized by large positive values of turbulent shear force, which are opposed by the pressure and the sec- ondary motion transport forces. The large shear forces are the result of the typical variation of the turbulent shear stress components in such regions, illustrated by the lowermost 0f the curves of both parts of figure 11, which detail, for example, the variation of LE)— at small values of y/d. Near the corner, the magnitude of the component of shear stress at a point is a function of the relative proximity of the two walls to the point, the closer wall having the greater effect. The stress at a point close to one wall is not greatly affected by the opposite wall until the point is located equally as close to the latter. As the opposite wall becomes effective, the stress changes rapidly. To be noted in figure 11 are the large stress gradients near the vertical wall. Simi— lar gradients of IE in the vertical direction account for the large shear force values in figure 19. The secondary motions, and the forces therefrom, are the consequence of the difference in 172 and 1127 at the boundaries and the reversal in the sign of the difference at the corner. A “typical” force variation near the 270-degree corner is more difficult to describe, because of the in- fluence of the other boundary elements on the more complex motion pattern. The effect of such an isolated corner may be approximated, however, as the differ- ence between corresponding force distributions in the upper and in the lower part of the section at the same value of y/d. This assumes that the force distributions in the upper part of the section would be identical to those in the lower in the event that the junction be- tween the two channel sections—the upper, smaller rectangular section and the lower, nearly square CONCLUSIONS larger section—were formed of a solid, smooth mate- rial; a further assumption is that the distributions in the lower half of the larger channel would not be greatly affected by such a procedure. The first assump- tion is completely reasonable; the second is reasonable enough to indicate without serious error the trends and magnitudes of the forces for the replaced-boundary condition. When compared in this manner, the trends shown by the distributions of figure 19 in the upper part of the section are largely unchanged. The effect of the corner is thus to cause a large change in the magnitude of both sets of the variable forces and to reverse the direc- tion of each from one to the other side of the corner. At the left, the shear forces are large and are opposed by the pressure force. The momentum transport forces due to the secondary motions act in the direction of the pressure. Both forces are larger than the pressure force. At the right side, the roles are reversed: the shear forces now act in the same direction as the pres- sure, and the secondary motion force opposes each. Farther to the right, the forces again reverse. At increased values of y/d, the corner influences les- sen, and the forces decrease. At y/d=1.0, a two- dimensional flow pattern is approximated, and the secondary motions are small or nonexistent. The two-dimensional counterpart of figure 19 is a straight horizontal line representing the value of —g% and is z 23 located a constant distance equal to —% 3—5: above the line corresponding to a zero force. The force variation for y/d>0.0833 in the upper half of the channel is illustrated in figure 20. The sum of the turbulent exchange forces only is shown in the figure. The sum of V% and W—gTU differ from corres- ponding values of these forces by the constant value of 4: 91%" which is equal to 8.6 m/s/s. Figures 19 and 20 graphically depict the role of the secondary motions—that of an agency to equalize the large turbulent exchange forces in the corner regions. The turbulent forces can be much larger than the pres- sure force. If the motions did not exist, the fluid must stagnate and separate from the boundaries in the 90- degree corners and would be greatly accelerated in the Vicinity of the 270-degree corner. CONCLUSIONS The experimental work reported herein is devoted to the internal details of a fully developed turbulent mo- tion in a conduit of complex boundary form. The prin- cipal feature of the boundary configuration is a corner subtending an angle greater than 180 degrees. The re- sults are principally concerned with the production and effect of the secondary motions in the conduit. D 30 LIJ E a 3 _G/ U) D 20 /f1 / s a \ o 0: / ___4 . E 10 O'ZCA ”T'— —*'9§14\\ \\ w [5'19 — 3:935}; \ _ LIJ U ~ 8“ E 3 \~8\‘3 —*:8 LIJ E . z o k: <§~w7 Q _~ \‘A .A A \\A El” “d a \- -A a a o 1.00 A ./ 1; CI 0.833 "A / 3'? O 0.667 / V —10 A 0.500 u. d 0.333 \ / o A 0.250 \0 m a 0.167 3 < > -20 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 VALUE OF Z/d FIGURE 20.—Distribution of sum of turbulent shear forces. 24 The following are the major results: 1. The variation of the turbulence components v and w in the corner regions of the conduit is the most probable cause of the secondary motions. 2. The magnitude of the secondary motions produced in a given corner region is a function of the angle subtended by the corner. The function may not be defined with the limited data at hand. 3. The secondary motions are an effective mechanism for the transfer of momentum in the plane of the channel cross section. The forces due to the momentum transfer are of the same order of magnitude as those due to turbulent shear and to pressure. 4. The combination of boundary effects at a corner produce turbulent shearing forces which are fre— quently larger than the force due to pressure. The shearing forces may oppose the pressure force or act in the direction of the pressure force, depend- ing upon the corner configuration. 5. The secondary motions transfer an appropriately directed momentum into the corner regions to compensate for the excess of shearing force and, thus, to prevent flow separation or acceleration of the flow in the regions. 6. The secondary motions also, apparently, act to equalize the boundary shear stress over consider- able portions of the boundary, accounting in large measure for the success of equations of the Man- ning or Chezy type applied to channels of complex form. STRUCTURE OF A TURBULENT FLOW IN A CHANNEL OF COMPLEX SHAPE 7. The transfer of fluid across the line separating the larger from the smaller channel is small. The shear stress at the line is also small, indicating that the channel subdivision practices commonly used are probably applicable, at least to the channel of this study. REFERENCES Brundrett, E., and Baines, W. D., 1964, The production and diffusion of vorticity in duct flow: Jour. Fluid Mechanics, v. 19, part 3, p. 375—392. Hinze, J. 0., 1954, Turbulence: New York, McGraw-Hill, p. 73—119. Laufer, John, 1951, Investigation of turbulent flow in a two- dimensional channel: Natl. Advisory Comm. Aeronautics report 1053, Washington, DC. 1954, The structure of turbulence in fully developed pipe flow: Natl. Advisory Comm. Aeronautics report 1174, Washington, DC. Maslen, S. H., 1958, Transverse velocities in fully developed flows: Appl. Mathematics Quart, V. 16, p. 173—175. Rodet, E., 1960, Etude de l’écoulement d’un fluide dans un tunnel prismatique de section trapézoidale: Ministére L’Air scien- tifiques et techniques Pub. no. 369. Schubauer, G. B., and Klebanoff, P. S., 1946, Theory and application of hot-wire instruments in the investigation of turbulent bound- ary layers: Natl. Advisory Comm. Aeronautics report W—86, Washington, DC. 1951, Investigation of separation of the turbulent boundary layer: Natl. Advisory Comm. Aeronautics report 1030, Washington, DC. Tracy, H. J ., 1965, Turbulent flow in a three-dimensional channel: Am. Soc. Civil Engineers Proc., Jour. Hydraulics Div., paper 4530, v.91, no. Hy 6, p. 9—35. 9575' x. 615’4 mm acimces LIBRARY 7 DAYS, Geology of an Upper Cretaceous Copper Deposit in the Andean Province, Lassiter Coast, Antarctic Peninsula GEOLOGICAL SURVEY PROFESSIONAL PAPER 984 Work done in cooperation with the National Science Foundation U.$, Utr‘vu: c u. .. APR 2 5 1977 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT IN THE ANDEAN PROVINCE, LASSITER COAST, ANTARCTIC PENINSULA Physiographic setting of the Copper Nunataks (circled). View west- Guettard Range in the middleground. The narrow RARE Range southwest toward the Antarctic Peninsula ice plateau in the lies beyond the well-defined 6-km-wide Irvine Glacier, and it is background. Western part of the Hutton Mountains in the for- separated by the Wetmore Glacier from several nunatak clusters ground; Johnston glacier separates these mountains from the of the Latady Mountains in the left background. Geology of an Upper Cretaceous Copper Deposit in the Andean Province, Lassiter Coast, Antarctic Peninsula By PETER D. ROWLEY, PAUL L. WILLIAMS, and DWIGHT L. SCHMIDT GEOLOGICAL SURVEY PROFESSIONAL PAPER 984 Work done in cooperation with the National Science Foundation A discussion of the southernmost known circum-Pacific copper deposit, which has afinities to the porphyry copper class but has no present economic potential UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1977 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Dirwtor Library of Congress Cataloging in Publication Data Rowley, Peter D. Geology of an Upper Cretaceous copper deposit in the Andean Province, Lassiter Coast, Antarctic Peninsula. (Geological Survey Professional Paper 984) Bibliography: p. 1. Copper ores—Antarctic regionsiLassiter Coast. 2. Geology—Antarctic regions—Lassiter Coast. 3. Geology, Stratigraphic— Cretaceous. 1. Williams, Paul Lincoln, 1932— joint author. II. Schmidt,Dwight Lyman, 1926— joint author. 111. United States, National Science Foundation. IV. Title: Geology of an Upper Cretaceous copper deposit in the Andean Province... V. Series: United States Geological Survey Professional Paper 984. QE390.2.C6R68 549'.23 76—45929 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, DC. 20402 Stock Number 024-001-02955-3 CONTENTS Page Page Abstract ____________________________________________________ 1 Older shear fracturing, hydrothermal alteration, and mineraliza- Introduction _________________________________________________ 1 tion _____________________________________________________ 20 Acknowledgments ______________________________________ 2 Younger shear fracturing, hydrothermal alteration, and mineral- Igneous rocks ______________________________________________ 4 ization _________________________________________________ 25 Medium-grained granodiorite pluton ____________________ 4 Mineralization ___________________________________________ 27 Aplite and pegmatite dikes ______________________________ 8 Phyllic and argillic alteration ____________________________ 28 Dacite dike ____________________________________________ 8 Propylitic alteration ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29 Copper Nunataks pluton ________________________________ 8 Epidote alteration _______________________________________ 30 Aplite and pegmatite dikes ______________________________ 14 Silicification _____________________________________________ 31 Granodiorite porphyry dikes ____________________________ 15 Mineralized and altered rock elsewhere in the Lassiter Coast and Interpretation of the chemical and modal data ____________ 17 southern Black Coast ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 31 Trends of systematic joints __________________________________ 20 Conclusions ________________________________________________ 35 References cited ____________________________________________ 35 ILLUSTRATIONS Page FRONTISPIECE. Photograph showing physiographic setting of the Copper Nunataks. FIGURES 1—4. Maps of: 1. West Antarctica showing location of Lassiter Coast project area and Copper Nunataks ____________________ 1 2. Lassiter Coast and southern Black Coast showing locations of known mineralized and hydrothermally altered rock ______________________________________________________________________________________________ 3 3. The Copper Nunataks showing generalized geology ____________________________________________________ 4 4. Three of the Copper Nunataks showing the geologic features ____________________________________________ 5 5. Ternary diagram showing modal distribution of quartz, K-feldspar, and plagioclase from igneous rocks in the Copper Nunataks _______________________________________________________________________________________________ 6. Maps showing sample localities and outcrops in the Copper Nunataks __________________________________________ 7 7. Photograph of Nunatak B __________________________________________________________________________________ 8 8. Photomicrograph of granodiorite pluton ______________________________________________________________________ 14 9. Photograph of mafic inclusion, aplite dikes, and gray shear fractures cutting granodiorite pluton ________________ 14 10. Photomicrograph of dacite dike ______________________________________________________________________________ 15 11. Photograph showing a typical outcrop of Copper Nunataks pluton, Nunatak A __________________________________ 15 12. Photograph showing a typical outcrop of Copper Nunataks pluton, Nunatak D __________________________________ 16 13. Closeup photograph of outcrop of Copper Nunataks pluton, Nunatak D ________________________________________ 16 14. Photomicrographs of Copper Nunataks pluton, Nunataks B and E ______________________________________________ 17 15. Photograph of aplite dikes in a stoped block in the granodiorite pluton, Nunatak A ______________________________ 19 16. Photomicrograph of chilled margins of granodiorite porphyry dike ______________________________________________ 21 17. Photomicrograph of interior of granodiorite porphyry dike ____________________________________________________ 21 18. Variation diagram of common oxides, selected trace elements, and differentiation index plotted against Si02 in specimens from igneous rocks in the Copper Nunataks ____________________________________________________ 22 19. Ternary plots of selected normative minerals, Barth’s cations, and oxides in specimens from igneous rocks in the Copper Nunataks ______________________________________________________________________________________ 23 20. Rose diagram of strikes of systematic steeply dipping joints in rocks in the Copper Nunataks ____________________ 24 21. Photograph of granodiorite pluton and pegmatite dikes offset by several black shear fractures ____________________ 24 22. Photomicrograph of black shear fracture ______________________________________________________________________ 24 23. Photographs of sheared phyllic-arg'illic zones, Nunataks A, B, and C ____________________________________________ 26 24—29. Photomicrographs of altered rock: 24. Phyllic altered rock of the granodiorite pluton ________________________________________________________ 29 25. Phyllic altered rock of the granodiorite porphyry dike __________________________________________________ 29 26. Sheared and phyllic altered rock of the Copper Nunataks pluton ________________________________________ 30 27. Argillic altered rock of the Copper Nunataks pluton ____________________________________________________ 30 28. Propylitic altered rock of the granodiorite pluton ______________________________________________________ 31 29. Silicified rock of the granodiorite pluton ______________________________________________________________ 31 V VI TABLE .10 CONTENTS TABLES Page Modes of fresh igneous rocks in Copper Nunataks, Antarctica __________________________________________________ 10 Chemical and modal data of selected fresh rocks from the major rock units from the Copper Nunataks, Antarctica ______ 12 Semiquantitative spectrographic analyses of selected fresh, altered, and mineralized rock from the Copper Nunataks, Antarctica ______________________________________________________________________________________________ 18 Results of X-ray determination of sheet silicates from hydrothermally altered rocks of the Copper Nunataks, Antarc- tica _____________________________________________________________________________________________________ 20 Semiquantitative spectrographic analyses of biotite-hOrnblende separates from fresh igneous rocks in the Copper N unataks, Antarctica 28 Semiquantitative spectrographic analyses of selected fresh, altered, and mineralized rock from scattered locations elsewhere in the Lassiter Coast and southern Black Coast ________________________________________________ 32 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT IN THE ANDEAN PROVINCE, LASSITER COAST, ANTARCTIC PENINSULA By PETER D. ROWLEY, PAUL L. WILLIAMS, and DWIGHT L. SCHMIDT ABSTRACT Mineralization with affinities to the porphyry copper class termi- nated two Upper Cretaceous episodes of similar igneous-tectonic events in the Copper Nunataks area of the Lassiter Coast, Antarc- tica. The first episode, at about 105 m.y. (million years), began with intrusion of a medium-grained granodiorite batholith, followed by emplacement of thin hornblende dacite dikes, and ended with two events of fracturing accompanied by minor hydrothermal alteration and pyrite mineralization. The second episode, at about 95 m.y., began with intrusion of a coarse-grained and mostly porphyritic, concentrically zoned quartz monzonite stock (Copper Nunataks plu— ton), followed by emplacement of 1- to 20-m-wide granodiorite por- phyry dikes, and ended with extensive shearing accompanied by major hydrothermal alteration and copper mineralization (Lassiter Coast copper deposit). Altered rock associated with the second episode occurs along northwest-striking sheared phyllic—argillic zones, between which is propylitic-altered rock. Mineralization, in the same location as propylitic, argillic, and phyllic rock, produced quartz veins, fist-size clots of chalcopyrite and pyrite, and dissemi- nated crystals of chalcopyrite and pyrite. The main ore minerals are chalcopyrite, pyrite, and magnetite; malachite, molybdenite, hema- tite-limonite, and apparently chalococite are less abundant. Average mineral grade of exposed rock probably does not exceed 200 ppm Cu, 100 ppm Pb, and 50 ppm Mo. Thus there is no evidence that the deposit is of ore grade even if it were feasible to be mined, but its discovery demonstrates that the Antarctic Peninsula may be placed within the circum-Pacific copper province. The presence of the oc- currence suggests the possibility of undiscovered copper deposits of economic grade elsewhere in the peninsula. INTRODUCTION The world’s southernmost occurrence of significant copper minerals was discovered in the Lassiter Coast area of Antarctica by D. L. Schmidt and L. E. Brown during the 1969—70 austral summer field season. Ex- posures occur in the Copper Nunataks,1 a small cluster of rock hills about 10 km west of the RARE (Ronne Antarctic Research Expedition) Range near the crest of the ice plateau (2,000 In elevation) of the Antarctic Peninsula about 130 km west of the Weddell Sea (fig. 1). A more detailed field study was conducted during 5 days of the 1970—71 season by P. L. Williams (party leader), P. D. Rowley, R. L. Reynolds, and A. B. Ford. lName recommended for initial approval by Advisory Committee on Antarctic Names. This report presents the results of field studies, de- tailed petrographic studies, and chemical analyses. The Antarctic Peninsula is a geologic continuation of the Chilean and Patagonian Andes (Adie, 1955, 1964; Halpern, 1971; Ford, 1972; Dalziel and Elliot, 1973), but the continuation of this Andean orogen south of the Antarctic Peninsula is more uncertain. Evidence such as a sharp westward bend in the structure at the south base of the Antarctic Peninsula (Laudon, 1972; Laudon and others, 1969) and some similarities between the rocks of the peninsula and those of western Ellsworth 0 09v 70° \ LARSEN 1CE°~ v. SHELF ‘3 90° E AMUNDSEN BELL INGSHA 1/ SEA on w ‘ o AFRICA 7O SNIViNnOW OILOHVLNVSNVHJ. SOUTH ED SEA AUSTRALIA / NEW 0 ZEALAND 0 180° 0 200 400 600 MILES 0 200 400 600 KILOMETERS FIGURE 1.—West Antarctica, showing location of Lassiter Coast project area (diagonal ruling) and Copper Nunataks (black square). 2 Land and Marie Byrd Land (for example, Wade, 1969) suggests that the orogen passes through these parts of West Antarctica (Craddock, 1970a, 1972; Halpern, 1971). Geologic similarities suggest that this belt, which is the southern loop of the great circum-Pacific mountain chain, may extend through New Zealand (Craddock, 1970b; Elliot, 1972; Bradshaw and An- drews, 1973) and into the western Pacific area. The geology of the Antarctic Peninsula has been summarized by Adie (1964, 1969). He and other work- ers noted that calc-alkaline stocks and batholiths of the Cretaceous and Tertiary Andean intrusive suite (Adie, 1955) dominate the geology of the Antarctic Peninsula. Plutons of this suite intrude (1) a lower Paleozoic(?) basement complex of igneous and meta- morphic rock (Adie, 1954), (2) a thick sequence ofblack sedimentary rock of the Carboniferous(?) to lower Mesozoic(?) Trinity Peninsula Series (Adie, 1957) that were probably folded in Triassic or Jurassic time, and (3) a thick sequence of black Upper Jurassic and Lower Cretaceous sedimentary rock and associated volcanic rock (Upper Jurassic) that were probably folded in Cre— taceous time. Gently folded to horizontal Upper Cre- taceous sedimentary rock (Bibby, 1966) and Cenozoic sedimentary and volcanic rock unconformably overlie the older rocks. Rowley and others (1975) compared the Lassiter Coast copper deposit to other metal occur- 3 rences in the Antarctic Peninsula and concluded that ‘ metallization is associated with Andean plutonic rock and that the peninsula belongs to the circum—Pacific copper province. Reconnaissance geologic investigations over about 30,000 km2 of the Lassiter Coast, northern Orville Coast, and southern Black Coast (Williams, 1970; Wil- liams and Rowley, 1971, 1972; Williams and others, 1972; Rowley, 1973) show that the area is part of the Andean orogen. The oldest known rocks consist of black fine-grained sedimentary rocks (Latady Forma- tion) of Late Jurassic age (R. W. Imaly and E. G. Kauffman, written commun., 1975); these rocks have been tightly folded around northeast to north- northeast axes (Kellogg and Rowley, 1974) prior to in- trusion of numerous stocks and batholiths. Metamor- phic aureoles, containing grades as high as andalusite hornfels, surround the plutons (Plummer, 1974). The plutons belong to a calc-alkaline suite (Rowley and Williams, 1974) consisting largely of quartz diorite, granodiorite, and quartz monzonite but they range from gabbro to granite. Numerous occurrences of minor hydrothermally altered rock, copper sulfides, and other ore minerals are associated with the Andean plutonic rocks (fig. 2); these occurrences are discussed in the section on “Mineralized and altered rock else- GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA Where in the Lassiter Coast and southern Black Coast.” Biotite-hornblende pairs from five plutons in the southern and central Lassiter Coast yield K-Ar ages ranging between 119 and 99 my (Mehnert and others, 1975). Potassium-argon ages of biotite and hornblende from eight samples of plutonic rocks in the northern Lassiter Coast and southern Black Coast range be- tween 114 and 98 my. (Rowley and others, 1976). The ages agree with three K—Ar ages given below (see pp. 4, 8, and 15) for rocks from the Copper N unataks, deter- mined by A. H. Clark, Edward Farrar, and S. L. McBride of Queen’s University, Ontario, Canada. The Lassiter Coast copper deposit is by far the high- est grade and most extensive of the mineral occur- rences on the Lassiter Coast, and it is the only one that received any detailed field and laboratory investiga- tion. It has affinities with the porphyry copper class of mineral deposits. However, the average copper content of samples from the limited exposures is probably no more than 200 ppm, well below present economic grade even for United States domestic deposits. The bedrock in the Copper N unataks (fig. 3) consists entirely of igneous rocks of Late Cretaceous age. The geologic history of these rocks may be divided into two broad episodes consisting of a nearly identical series of events; both episodes terminated with mineralization. Each episode consisted of intrusion of a pluton followed by emplacement of aplite and pegmatite dikes, intru- sions of northwest-trending mafic porphyritic dikes, and faulting or “crackling” accompanied by minerali- zation and hydrothermal alteration. The mineraliza- tion and alteration during the younger episode were more intense and resulted in the Lassiter Coast copper deposit. The well—exposed bedrock (fig. 3) in the Copper Nunataks is fresh because it was scoured during higher ice stands. Summer air temperatures extend to —30°C and rarely exceed 0°C; the humidity is ex- tremely low, so megascopic organisms are limited to sparse patches of lichens on the rocks. Rock tempera- tures, however, have been recorded at above +20°C for several hours a week during several weeks at mid- season. Under these conditions, chemical weathering takes place very slowly (Boyer, 1975); therefore super- gene minerals are scarce and most alteration and mineralization products discussed below are consid- ered to be hypogene. ACKNOWLEDGMENTS This work is part of a US. Geological Survey geologic study of the Lassiter Coast area done under INTRODUCTION 66° 00' 73 0° EXPLANATION x Locality exhibiting mineralized rock I Locality exhibiting hydrothermally altered rock 0 Other locality men— tioned in table 5 73° 30‘ 74° 00' COPPER NUNATAK 74° 30' x? 4Q Q s $ 75°00' RONNE ICE SHELF 75°30‘ * ‘ 0 20 40 60 MILES If V I I l l 4‘ O 20 40 60 KILOMETERS FIGURE 2.——-Lassiter Coast and southern Black Coast showing locations of known mineralized and hydrother- mally altered rock. 4 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA T 74°20's :- I Fig.4C i; Nunatak D 65 00 W nadir). Q ‘3 Nunatak C Inferred contact ‘ ofCopper Nunataks; pluton\ . Nunatak E 6 Nunatak B S I '. Copper Nunataks pluton 3; 8 ' (quartz monzonite) a g D 33' _ _ 5 Granodionte pluton __“__ Contact— Dashed where con~ cealed by snow or ice ‘uu Fault — Dotted where con- cealed by snow or ice 0 1 2 MILES O 1 2 KILOMETERS FIGURE 3.—Generalized geology of the Copper Nunataks. the auspices of, and financed by, the National Science Foundation (NSF) (Grant AG—187). The US. Antarctic Research Program of the National Science Foundation and the US. Navy Operation Deep Freeze provided logistic support in Antarctica. Many persons made the study possible. The memory of the late Prof. Duncan Stewart VII of Carleton College, a former teacher, col- league, and friend, provided inspiration for this report. M. D. Turner, Program Manager of Polar Earth Sci- ences, Division of Polar Programs of NSF, approved the program and provided logistic help. L. E. Brown, A. B. Ford, and R. L. Reynolds of the US. Geological Survey aided the writers with the field mapping of the Copper Nunataks. Copper sightings elsewhere in the Lassiter Coast area were made by the other geologists during the field seasons: C. C. Plummer during the 1969—70 season, W. H. Nelson during the 1970—71 sea- son, and S. J. Boyer, E. N. Kamenev, K. S. Kellogg, W. R. Vennum and R. B. Waitt, Jr., during the 1972— 73 season; all were affiliated with the US. Geological Survey except Kamenev, who is at the Research Insti- tute of the Geology of the Arctic, Leningrad, USSR. Potassium-argon age dating was done by A. H. Clark, Edward Farrar, and S. L. McBride of Queen’s Univer- sity, Ontario, Canada. L. G. Schultz of the US. Geolog- ical Survey aided the senior author in X-ray identifica- tion of clay minerals and interpreted the data. Discus- sions with A. V. Heyl and R. U. King of the US. Geological Survey helped form conclusions. G. A. Des- borough and D. P. Cox reviewed the manuscript. IGNEOUS ROCKS Rocks in the Copper Nunataks are discussed in age sequence from oldest to youngest; their distribution is shown on the geologic sketch map (fig. 4). The modal classification (fig. 5) follows Bateman (1961, fig. 2). Sample localities and outcrops are shown in figure 6. Anorthite content of plagioclase was determined by the a-normal method using the low-temperature curves of Wahlstrom (1947, fig. 21, curve D). MEDIUM-GRAINED GRANODIORITE PLUTON The first event in the earliest igneous episode was intrusion of the older of two large plutons in the area. This granodiorite body is characterized by its uniform composition and texture, light- to medium-gray color due to abundant ferromagnesian minerals and dioritic inclusions, and at least minor alteration in nearly all exposures. The rock is generally nonfoliated, but in several places a vague flow foliation of ferromagnesian minerals strikes northwest. It is mostly medium grained (1—5 mm), but in some places it is gradational to fine grained. Studies by A. H. Clark, Edward Farrar, and S. L. McBride (written c0mmun., 1974) give a K—Ar biotite determination of 104.9: 1.6 m.y. for this pluton (specimen M308a). The granodiorite is exposed at Nunataks A and B (figs. 4, 5, 7) as massive resistant outcrops cut by medium spaced to finely spaced joints; it underlies at least 15 km2 in the area of the five largest nunataks of figure 3. No contacts with older rocks are exposed in the area, but on the basis of similar petrology (table 1) and chemistry (table 2), the granodiorite is probably correlative with a batholith (West RARE pluton) in the western nunataks of the RARE Range about 8 km to the northeast. The West RARE batholith discordantly intrudes folded slate and sandstone of the Upper Jurassic Latady Formation (Williams and others, 1972), and contact metamorphism reaches andalusite hornfels grade (Plummer, 1974). Pluton contacts are commonly chilled and are accompanied by igneous apophyses in the metamorphic country rock; as else- IGNEOUS ROCKS TNunatak A Nunatak B Nunatak c EXPLANATION \ \ \ w Granodiorite porphyry dike qu », Copper Nunataks (quartz monzonite) pluton V Kgd Dacite dike CRETACEOUS Granodiorite pluton Contact ' ...... wwwx Sheared phyllic-argillic zone — L 042 0.4 0.6 MILE Dashed where location un- | w ‘ A certain; dotted where covered 02 0,4 0.6 0.8 KILOMETER by ice or show —————— Nunatak ridge crest Outer edge of snow- and ice»covered nunatak 07-0 FIGURE 4.—Geology of three of the Copper Nunataks (fig. 3). 6 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA Quartz Quartz Granodmnte monzonita (rhyodaclre) A Quartz diome (dacitel Duome, Svsnodlorlte Monzonite gabbro Trend line for rocks of older episode “AA Trend line for racks of younger episode l A. EXPLANATION a? .2) Plagioclase K~feldspar (including perthite) Cretaceous Younger igneous episode Aplite of granodiorite porphyry dike Granodiorite porphyry dike Aplite of Copper Nunataks pluton Quartz monzonite of Copper Nunataks pluton +oI>¢ Assimilated rocks ~ Of same age as Copper Nunataks pluton Older igneous episode Dacite dike Aplite of granodiorite pluton Granodiorite pluton West RARE pluton — Of same age as granodiorite pluton oouz> FIGURE 5.—Modal distribution of quartz, K—feldspar, and plagioclase in fresh rocks from the major igneous units, Copper Nunataks. Calculated from data in table 1. Insert shows igneous classification used. where in the Lassiter Coast, evidence supports the con- clusion that the plutons originated by magmatic proc- esses of passive to forceful intrusion. If the petrologic and age correlations are correct, the medium-grained granodiorite is at least 20 km long in a northeast direc- tion and 10 km wide in a northwest direction. Modal analyses for 10 samples from the medium- grained granodiorite and their averages are presented in table 1. Plagioclase, hornblende, and biotite are subhedral in most thin sections; quartz and K-feldspar are anhedral (fig. 8). Minerals are equigranular except for scattered large inconspicuous light-gray poikilitic K-feldspar crystals which are as much as 2 cm long and which enclose other minerals. Crystals other than K-feldspar average about 1 mm and rarely exceed 3 mm. K-feldspar is rarely grid-twinned; perthite is rare to absent. Most plagioclase is zoned, anorthite content in most thin sections ranges from sodic lab- radorite cores to calcic oligoclase rims. Nonzoned crystals have an average composition of intermediate andesine. In some places, the boundaries between pla- gioclase and K-feldspar 0r plagioclase and quartz con- tain small areas of myrmekite. Smoky quartz is abun- dant and has undulatory extinction in irregular masses as large as 5 mm across. Biotite is strongly pleochroic (X=pale yellow, Z=dark brown to dark red- dish brown). Most biotite shows at least some altera- tion to chlorite (penninite?) along cleavage planes and to a much lesser degree to epidote. Hornblende is also markedly pleochroic (X=yellowish green, Y= grass green, Z=olive green to dark yellowish green). Content of biotite is relatively uniform, whereas the content of hornblende is quite variable. Magnetite is the most abundant opaque mineral; minor amounts of pyrite and ilmenite are present. Sphene is rare and occurs as small poorly developed crystals. Apatite and zircon are present. A triangular plot of plagioclase, K—feldspar, and quartz (fig. 5) shows that most rocks fall in a tight cluster in the granodiorite field near the boundary with quartz monzonite. Similar data for four samples from the West RARE pluton plot in the same area in figure 5 add further support to the proposed correlation of these two rock bodies. Three rapid rock chemical analyses and three semi- quantitative spectrographic analyses of fresh rock of the granodiorite pluton and West RARE pluton are presented in tables 2 and 3. The analyses from the granodiorite are somewhat lower in potassium and sodium and higher in calcium than the average hornblende-biotite granodiorite of Nockolds (1954). Sample W144a, representative of the West RARE plu- ton and from 15 km northwest of Nunatak C, is only slightly more silicic; it is lower in potassium and sodium and higher in calcium than Nockolds’ average granodiorite. Trace elements of sample W144a have concentrations similar to those of the medium-grained granodiorite. The plutonic rock contains many medium- to dark- greenish-gray, ovoid to subspherical inclusions that average 5 cm in diameter; some exceed 1 m in diame- ter (fig. 9). Exposures average three or four inclusions per m2 of outcrop face, but in some places inclusions constitute more than 5 percent of rock volume. Mafic inclusions are remarkably uniform in texture, compos- ition, and size within each pluton; most inclusions are fine-grained rocks (average crystal size less than 1 mm), with or without phenocrysts of plagioclase, hornblende, and (or) biotite. Inclusion edges are mostly IGNEOUS ROCKS Nunatak A Nunatak B Nunatak C EXPLANATION Outcrops and sample localities not shown M429 at Nunatak D M430 at Nunatak E 0.2 0.4 0.6 MILE | l 0,2 0,4 0.6 0.8 K|LOMETER O——O FIGURE 6.—Samp1e localities and outcrops (patterned) in the Copper Nunataks. 8 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA FIGURE 7.—Southwestern face of Nunatak B. Black curved line ex- tending from one end of the nunatak to the other just below the crest is the dacite dike. sharp, but some exhibit narrow gradational contacts with the enclosing igneous rock. Two thin sections (table 1) are of a hypidiomorphic-granular to allotrio- morphic-granular hornblende diorite and hornblende syenodiorite; minerals are the same as those of the enclosing granodiorite, consisting mostly of abundant euhedral hornblende and uncommon biotite with in- terstitial plagioclase (calcic andesine), K-feldspar, and quartz. APLITE AND PEGMATITE DIKES Light pink, or less commonly white, aplite and peg- matite dikes are abundant (to 10 percent of rock vol- ume in some areas) end-stage products of the intrusive activity that produced the medium-grained granodior- ite (fig. 9). Most aplite dikes, are 2—15 cm wide, but several are more than 10 m wide. Coarse-grained (5 mm to 3 cm) to very coarse grained pegmatite dikes are intimately associated with, and in some places gradational into, aplites; they have the same dimen- sions and attitudes as the aplite dikes but are signific- antly less abundant. The dominant strike of aplite- pegmatite dikes is northwest; dips range from 40° to vertical with no apparent preferred orientation. Two thin sections (table 1) have a typical fine—grained allotriomorphic-granular texture and consist chiefly of K-feldspar (rarely grid-twinned), quartz, and less abundant plagioclase; perthite and myrmekite are rare. The rocks are in the quartz monzonite and gran- ite fields of the plagioclase, K-feldspar, and quartz diagram (fig. 5). DACITE DIKE A single thin (1—4 m wide) subvertical north-north- east- to west-northwest-striking, dark-green to black dike cuts the medium—grained granodiorite, associated aplites, and pegmatites at Nunatak B (figs. 4, 7). In most places it is a hornblende dacite, with finer grained chilled margins; at several places where it is thicker, the interior is a lamprophyre of small (1— 3 mm) hornblende phenocrysts in a fine-grained phaneritic matrix. Small pyrite crystals as much as 2 mm across are conspicuous in hand specimen. Contained minerals (3 thin sections, table 1) are the same as those in the medium-grained granodiorite. The seriate or porphyritic rock consists mainly of euhedral green hornblende in a groundmass of mostly anhedral crystals of abundant plagioclase and hornblende. Minor K-feldspar, quartz, biotite, and opaque minerals are present (fig. 10). Ferromagnesian minerals are moderately to extensively altered to chlo- rite and epidote; anorthite content of plagioclase can- not be determined, owing to saussuritization. This al- teration is probably deuteric, because the adjacent granodiorite wallrock is fresh. The ternary diagram (fig. 5) shows that the rocks fall in the dacite field and in the lower right part of the rhyodacite field. A single chemical analysis of a dacite dike is given in tables 2 and 3. COPPER NUNATAKS PLUTON The dominant rock type in the Copper Nunataks is that of the younger stock, which has an average com- position of quartz monzonite and underlies an area of at least 40 km2. It is here named the Copper Nunataks pluton. It represents the first event in the younger igneous episode. Specimens are easily distinguishable from the older granodiorite by (1) lack of alteration, (2) considerably coarser grain size, and (3) light-gray or pinkish-gray color which, owing to the sparseness of ferromagnesian minerals and dark inclusions, is sig— nificantly lighter in color than the granodiorite pluton (fig. 11). In contrast to the older batholith, the Copper Nunataks pluton exhibits considerable internal vari- ety in texture and composition. At N unataks A, B, and C (fig. 3), the pluton is mostly granodiorite to quartz monzonite, at N unatak E it is quartz monzonite, and at Nunatak D it is granite (figs. 12, 13). Thus the pluton appears to be concentrically zoned from a more mafic marginal zone to a silicic interior at Nunatak D. A K—Ar biotite date of 952i 1.5 m.y. was determined for the stock (specimen M430a) by A. H. Clark, Edward Farrar, and S. L. McBride (written commun, 1974). Sharp intrusive contacts are exposed at Nunataks B and C; here the older granodiorite body and the dacite dike are sheared and slightly altered in the area from the contact to a distance of several centimeters. The Copper N unataks pluton is somewhat finer grained at the margin than elsewhere in the body. At one location along the contact at Nunatak B, the rock is gneissic for a width of several meters. The light-gray, medium- grained gneissic bands, 5—50 cm wide, vary in quartz and feldspar content, grain size, and amount of fer- IGNEOUS ROCKS 9 romagnesian minerals; the rock in different bands var- ies from quartz diorite to granodiorite. The foliation is considered to be‘primary, strikes parallel to the con— tact, and dips east under the older rock. The Copper Nunataks pluton occurs as resistant, massive outcrops that in places have a slightly crum— bly weathered surface. Microscopic study of 17 thin sections (table 1) shows that different sizes (as much as 3 cm long) and shapes (anhedral, less commonly sub- hedral) of pink or gray K—feldspar crystals result in different textures that are most commonly porphyritic but may be equigranular (hypidiomorphic-granular), poikilitic, or seriate (fig. 14); the three latter textures appear to predominate in the interior (Nunataks D and E). K-feldspar is rarely grid-twinned and perthite is scarce to absent. Plagioclase, hornblende, and biotite are subhedral and quartz is anhedral; these minerals average 2—3 mm in size and few exceed 1 cm. Most pla— gioclase crystals are zoned and have an anorthite con- tent that is slightly lower than that of the granodiorite pluton: most zoned crystals range from calcic andesine cores to calcic oligoclase rims; most unzoned crystals range from sodic to intermediate andesine. Rare amounts of myrmekite occupy small areas near the boundaries of plagioclase and K-feldspar or plagioclase and quartz. Quartz has undulatory extinction, and in some places it exhibits either sutured boundaries or mortar texture suggestive of late-stage plutonic movement. Green hornblende and brown biotite have the same pleochroic formulas as those in the granodior— ite pluton. The hornblende content varies considerably whereas the content of biotite is more uniform. Most biotite is slightly altered to chlorite (penninite?) along cleavages and is much less commony altered to epidote. Opaque minerals are abundant and most are magne- tite; pyrite is virtually absent. Sphene is abundant and occurs as large, conspicuous euhedral crystals as much as several millimeters long; apatite is relatively abun— dant, but zircon and other nonopaque accessory miner- als are rare. On the ternary diagram (fig. 5), the rocks of the Cop- per Nunataks pluton occupy an elongate belt spanning the quartz monzonite field extending from just inside the granodiorite field to the edge of the granite field. Specimens collected close to the contacts are more mafic and contain more biotite, hornblende, and sphene, and have a higher hornblende-to-biotite ratio (table 1) than those collected farther inward from the contact. In comparison with rocks of the granodiorite batholith, the rocks of the Copper Nunataks pluton are characterized by a higher content of K—feldspar, opaque minerals, and sphene; a higher hornblende-to- biotite ratio; and a lower content of plagioclase, quartz, hornblende, and biotite. Rapid rock chemical analyses and semiquantitative spectrographic analyses of fresh samples collected from the Copper Nunataks pluton (tables 2 and 3) show a systematic increase inward towards Nunatak D in 8102, K20, Sr, V, Ga, Ce, Y, Cr, 00, Yb and a system- atic decrease in A1203, Fe203, FeO, MgO, CaO, Ti02, P205, MnO, and perhaps Pb. Proceeding inward from the contacts, sample M315a is comparable to Nockolds’ hornblende-biotite granodiorite; M321i is somewhat higher in Ca0 and lower in K20 than Nockolds’ aver- age granodiorite; M421 is somewhat higher in CaO than Nockolds’ average hornblende-biotite adamellite; M318a and M430 are somewhat higher in CaO than Nockolds’ average adamellite; and M429c is somewhat higher in Ca0 and lower in Na20 and K20 than Noc- kolds’ calc-alkali granite. Specimen B25a is from as- similated material near a stope block and is somewhat higher in Ca0 and lower in K20 than Nockolds’ aver- age granodiorite. Dark inclusions in the Copper Nunataks pluton are much less abundant (about 1 per In2 of rock area), lighter colored, and smaller (average diameter about 2 cm and maximum length about 10 cm) than those in the medium-grained granodiorite. The abundance of inclusions increases slightly toward the intrusive con- tact. The included rock is a syenodiorite (table 1) with both porphyritic texture (subhedral to euhedral plagio- clase and green hornblende phenocrysts as much as 5 mm long) and poikilitic texture (sparse K-feldspar as much as 3 mm) in a fine-grained (about 0.4 mm) ma- trix of subhedral plagioclase, hornblende, and opaque minerals and of anhedral quartz. Anorthite content of twinned, zoned plagioclase phenocrysts ranges, from calcic oligoclase to calcic andesine; anhedral, slightly zoned groundmass plagioclase is mostly sodic to inter— mediate andesine. The contrast in relative amounts of minerals between the Copper Nunataks and grano- diorite plutons is paralleled by those in their contained inclusions; inclusions in the Copper Nunataks pluton contain less hornblende and more K-feldspar, quartz, opaque minerals, and sphene than inclusions in the granodiorite pluton. Intrusion of the Copper Nunataks pluton was largely passive. Large-scale stoping and partial assimilation of the rock of the older granodiorite is apparent at many locations at Nunatak A (fig. 15). Some stoped blocks, as much as 8 m in diameter, have sharp contacts with quartz monzonite of the Copper Nunataks pluton; more commonly, however, contacts are gradational over sev- eral tens of meters, and the rock in these zones is com- positionally and texturally transitional between that of the two plutonic rock types. 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II II II II II II II II II II II II II .mHmumEHE nowumuwuam umnuo II II N .H II II II II II II . 5 II N .3 N. q. II IIIIIIIII 303.5 C. <.N w.H II N. N. N. N. N. q.N N. w.m m. N.H N. IIIIIIII wuwuoanu N. N. N. N. C. .HH .HH .HH ¢. a. .HH II II .uH II IIIIIIIIII muwnaw N.H N.H q. q.H ¢. q. N.H w. w. m. C. m. .VH N. q. Imamumcafi msvmmo w.w w.¢ O.m w.¢ C.c O. O.m w.N O.C w.m w.m N.mN C.w q.HN N.w IIIIII mvfiwaacuom O.m w.m .HH q.m N.m N.H m.¢ C.H N.N q.H N.m II N.¢H w.m «.N IIIIIIIII wufluowm w.m w.N m.N m. N.wN m.mm C.ON C.ON C.mN O.mN N.mN II m.mN N.Cm m.NN IIIIIIIIII Nuumdc .uH .HH II II «.ma m.mm q.¢m m.Cm w.wN «.MN C.ON II m.HH O.HH H.NH IIIIII umnmwawwIM o.C¢ O.wm m.mm m.Nm O.C¢ w.HN w.CN m.mq N.Nm w.Oq O.mm II «.mm N.om N.o¢ IIIII mmmauoflwmam Auamuwmm QEDHO>V mmwoS MNm.wm #HC.mm me.wm OHO.mm www.mm mmq.mm CCN.CC oqq.mm Noc.wm «mC.mC Nmm.mm MNo.Nm HwO.mC CCm.mm dNH.mo I IIIIII Hauoa moo. Owe. mmN. ¢oo. qu. mwa. mNm. CN¢. mom. Ono. owe. qu. «HN. «N¢. can. 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CCN OCN OCN OCN CCC.H CCm OCm CON CON OCN OCN OOO.H OCm OCN OCm IIIIIIIIIIIIII um OH CH OH CH CH N CH N N CH ON Om CH CH CH IIIIIIIIIIIIII om z z z z z z 2 II 2 z z I. m II II IIIIIIIIIIIIII up |\| 14 FIGURE 8.—Mostly fresh rock of the granodiorite pluton: small anhedral crystals of quartz (Q) and small subhedral crystals of plagioclase (pl), hornblende (hb), and biotite (bi) poikilitically en- closed in a large crystal of untwinned K-feldspar (K). Specimen M309a. Crossed polars. a contaminated quartz monzonite melt that was perhaps a border phase of the Copper N unataks pluton. The rock is medium—grained hypidiomorphic-granular or hypidiomorphic-seriate. Some rocks have a bimodal grain size containing small, commonly—altered crystals similar to those of the older granodiorite, and larger fresh crystals derived from the quartz monzonite melt. Partly assimilated stoped blocks exhibit strongly un- dulose quartz with sutured boundaries or mortar tex- ture; some crystals are bent and broken. One sample is a1lotriOmorphic-granular. Most assimilated rocks plot between the fields of the granodiorite and Copper Nunataks plutons on the triangular diagram (fig. 5). APLITE AND PEGMATITE DIKES Gray or pink aplite dikes and associated pegmatite dikes are volumetrically abundant end-stage products of the Copper Nunataks pluton intrusive episode (figs. 9, 15); they are especially abundant near the pluton contacts where they may make up 10 or 20 percent of GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, AN TARCTIC PENINSULA FIGURE 9.—Aplite dikes of several ages in granodiorite pluton near the Copper Nunataks pluton intrusive contact, outcrop M201, Nunatak B. Pocketknife lies on an older aplite dike that is in- truded into its parent granodiorite and a mafic inclusion (black) in the granodiorite. This aplite dike and the inclusion are offset by a thin gray shear fracture. Several younger aplite dikes, of the Cop- per Nunataks pluton episode, cut the gray shear fracture. Note offset of the older aplite dike by the fracture occupied by one of the younger aplite dikes, just above and to the right of the knife. the rock. Pegmatite bodies may occur with aplitic material or as separate masses; they are significantly more abundant than the pegmatites of the granodiorite pluton. Most pegmatite or aplite dikes are a few cen- timeters to 25 cm wide, but some are more than 10 m wide. Crosscutting relations indicate at least two events of aplite-pegmatite intrusion. One event pro- duced an older subhorizontal to gently dipping, non- rooted series of pod-form masses and dikes and the sec- ond, a younger one, produced a steeply dipping set, rooted to deeper parts of the pluton. Crosscutting rela- tions also are exhibited within the younger dike set. The steeply dipping dikes have numerous trends. Small masses of tourmaline and garnet occur within some pegmatites. Seven thin sections show that, with the exception of one microgranite, most rocks are typi- cal aplites (table 1). Grid-twinned K-feldspar and perthite are'rare. Most aplites are classified as granites (fig. 5); paralleling the differences between the two plutonic rock types, the aplites of the Copper N unataks stock contain less quartz than those of the granodiorite batholith. IGNEOUS ROCKS 15 FIGURE 10,—Fresh dacite dike: a lamprophyric texture of subhedral to euhedral hornblende crystals of all sizes in a fine-grained groundmass of anhedral feldspar and lesser quartz, hornblende, biotite, and opaque minerals. Specimen M101. Plane light. GRANODIORITE PORPHYRY DIKES The youngest igneous rock in the area is granodior- ite porphyry exposed in distinctive dikes. Two of these are as narrow as 1 m, but most are 5—20 m wide; all are subvertical and strike from north—northwest to west- northwest. The four smallest dikes are at Nunataks A and C, but the largest and best exposed are at Nunatak B (fig. 4). A K-Ar biotite determination of 95.61- 1.5 m.y. (specimen M311a) by Clark, Farrar, and McBride (written commun., 1974) suggests that the dikes are related to the igneous activity of the Copper Nunataks pluton. All dikes have medium-gray to black chilled mar- gins that are as much as several meters thick. The country rock is sheared and slightly to moderately al- tered for several centimeters outward from the intru- sive contacts, and the chilled margins also commonly show similar shearing and deuteric(?l alteration. Thin coatings or disseminated crystals of epidote occur loc— ally in the chilled rock and at the contacts in the coun— try rocks. The chilled margins are aphanitic, with rare FIGURE 11.-Typical outcrop of Copper Nunataks pluton, outcrop M425, Nunatak A. Snow—filled ravine on left about 3 m wide at base of nunatak. phenocrysts; inward, phenocryst abundance and size of both phenocrysts and groundmass increase; the dike interiors are light gray. The transition is most com- monly gradational, but in several places it is sharp across less than a 5-mm width, indicating a younger pulse of more crystal-rich rock. The rock is fresh in most places. However, the 5—8 m wide dike at Nunatak A is entirely altered to saussu- rite and chlorite; altered rock does not continue for more than 1 or 2 m into the country rock. This altera— tion is most probably caused by deuteric 0r hydrother- mal solutions very closely tied in time and origin to dike intrusion. Petrography, clay mineralogy (table 4), and the results of semiquantitative spectrographic analyses (table 3) show that the altered rock is similar to hydrothermally altered argillic rock of the copper deposit. This similarity, and the presence of dissemi- nated sulfides in some chilled dike margins, adds sup— port to our belief that the main period of copper mineralization is related to and shortly followed emplacement of granodiorite porphyry dikes. Modes of 17 thin sections are presented in table 1, and four chemical analyses are given in tables 2 and 3. Minerals are identical to those of previously described rocks, but their size, shape, and relative abundances 16 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA FIGURE 12.—Typica1 outcrop of massive Copper Nunataks pluton, Nunatak D. Rock is a fresh coarse-grained granite in presumed interior of pluton; note lack of aplite-pegmatite dikes and mafic inclusions. FIGURE 13.—Fresh coarse-grained granite in presumed interior of ; Copper, Nunataks pluton, Nunatak D. Granite contains 0.5— 1.5 mm biotite books and hornblende crystals as well as abundant smoky quartz. ‘ are different. The most common phenocryst is euhedral and subhedral plagioclase; the phenocrysts average 2 or 3 mm in length with a maximum of more than 7 mm; less abundant euhedral hornblende crystals av- erage 1 or 2 mm in length with a maximum of 1 cm, and euhedral or subhedral biotite grains average 1 mm in length with a maximum of 4 mm. Deeply embayed "beta” quartz as much as 3 mm across and untwinned K—feldspar as much as 1 or 2 mm long, as well as small crystals of opaque minerals, are present but uncom- mon. The groundmass consists of tiny anhedral crys- tals that are less than 0.1 mm at the chilled margins of the dikes (fig. 16) and commonly reach 0.2—0.3 mm in the interior; the interiors of the larger dikes contain a micrographic groundmass texture (granophyric) and the crystals have myrmekitic to cuneiform inter- growths up to 0.6 mm across (fig. 17). The main groundmass minerals are K-feldspar (no grid— twinning) and less abundant quartz; plagioclase, hornblende, biotite, and opaque minerals are generally minor. Most plagioclase phenocrysts are zoned; their anorthite content generally ranges between inter- mediate labradorite cores and sodic andesine rims. Hornblende and biotite have the same pleochroic for- mulas as those in the plutonic rocks. The hornblende content has a relatively wide range. Pyrite and magne- tite are moderately abundant. Sphene is uncommon as small anhedral to subhedral crystals. Phenocryst and groundmass contents of plagioclase, hornblende, and opaque minerals are generally grea- ter in the granodiorite dikes than in the Copper Nunataks pluton, but K-feldspar, quartz, biotite, and Sphene are less abundant (table 1). The granodiorite porphyry dike rock occupies a linear belt on the modal ternary diagram (fig. 5); this belt extends across the quartz monzonite field to a low-quartz position in the granodiorite field. The belt is parallel to, and displaced below and slightly to the left of, the field for the Copper Nunataks pluton. The rather wide compositional scat- ter within the belt largely reflects the relatively lower precision in point counting the fine-grained ground- mass; generally the best modal data are those from coarser rocks of the interior of the dikes, and these lie toward the upper left part of the belt. Rather inconspicuous, medium-gray fine-grained in- clusions as much as 10 cm long rarely are present in the granodiorite dikes. A thin section of one specimen (table 1) shows a hypidiomorphic-seriate rock with grain size averaging 0.4 mm and a maximum of 1.5 mm. The minerals are the same as those in the other igneous rocks and the other inclusions; the pleochroic formulas of hornblende and biotite are also the same. The larger crystals are plagioclase and hornblende. K-feldspar exhibits no grid-twinning. The IGNEOUS ROCKS 17 FIGURE Dir—Rocks of the Copper Nunataks pluton. A, From rock: Medium- to coarse—grained hypidiomorphic granular texture of K—feldspar (K), plagioclase (pl). quartz (Q), hornblende (hb), and minor opaque minerals and sphene (sp). Specimen M311d. Nunatak B. Crossed polars. commonly zoned plagioclase crystals are generally carlsbad twinned or untwinned; anorthite content of zoned crystals ranges from sodic andesine to sodic lab— radorite. The rock is modally classified in the low quartz and high plagioclase part of the quartz monzo— nite field, but it is more silicic than inclusions from the Copper Nunataks pluton. INTERPRETATION OF THE CHEMICAL AND MODAL DATA The major oxides are shown on a silica variation diagram (fig. 18). Plotted against increasing silica, the oxides of the combined igneous units exhibit a regular trend that is typical of the calc—alkaline rock series. Average alkali—lime index (Peacock, 1931) is slightly greater than 62. Ternary diagrams of selected chemi- cal constituents (fig. 19) also show trends characteris- tic of the calc-alkaline rock series. The data points of the combined igneous rocks define an overall system- atic trend on the variation diagram and the ternary plots; the smoothness of the overall curve further sup- B, Mostly fresh rock: Medium—grained hypidiomorphic-granular tex— ture of untwinned K-feldspar (K), plagioclase (pl), quartz (Q), hornblende (hb)y chlorite (chl), and biotite (bi). Feldspar is slightly sericitized and some biotite is altered to chlorite. Specimen M430, N unatak E. Crossed polars. ports the proposal that all rocks are genetically related to a single magma series. Each igneous rock unit occupies a distinct and gen- erally separate position on the various modal and chemical diagrams. The data points for individual rock units may form a tight cluster or a broad belt. Rocks of the Copper Nunataks stock occupy the longest belt; samples obtained nearer the intrusive contacts of this pluton lie progressively closer in all diagrams to the mafic end of the overall field, as defined by the granodiorite porphyry dike rocks. The consistent trends for this pluton are interpreted as formation by igneous differentiation of a single magma body. Another smaller belt of data points is defined by rocks of the medium-grained granodiorite pluton and rocks of the presumably equivalent West RARE pluton; these data, too, are interpreted to reflect differentia- tion of a single magma. Assimilated rock occupies a position between the fields of the granodiorite pluton and Copper Nunataks pluton. Mafic dike rocks are GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA 18 cmg ...... aggmz mmmmm>< ......... mmg ...... mmomz wmg ...... omomz umg yyyyyy amom: mg ....... NmNgmz mg ....... gmNHm: mg ....... ggom: mg ....... 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Each of the two magmatic episodes displayed the same sequence of plutonism, related late-stage aplite— pegmatite dike intrusion, and emplacement of rela— tively mafic dikes. Both the dacite dike and the granodiorite porphyry dikes show similar chemical trends away from their respectively older pluton. Both dikes are higher than their parent pluton in Fe203, FeO, MgO, CaO, TiOz, MnO, Co, Ni, Cu, Sc, Sr, V, Y, Ga, and Yb, and lower in SiOQ, K20, Ba, and differentiation index (Thornton and Tuttle, 1960). However, the dacite dike is more mafic than the granodiorite porphyry dikes, and thus its magma doubtless proceeded farther along the trend line from the parent pluton than did that of the granodiorite porphyry dikes. The differences between the two trend lines are clear but not profound: the younger Copper Nunataks pluton trend line reflects less quartz but generally higher al- kalies and lower contents of MgO and CaO. The chemi- cal and petrographic differences between the two episodes may be explained largely by differentiation of . a magma. The 10-m.y.-age difference between the granodiorite and Copper Nunataks plutons suggests the time frame during which differentiation produced these changes. The lower position of the Copper Nunataks pluton trend line with respect to quartz however, may partly reflect the tapping of magma from a lower level in a compositionally zoned magma chamber as compared with the level of the magma of the granodiorite episode. I I l TRENDS OF SYSTEMATIC JOINTS Steeply dipping systematic joints cut all rocks in the Copper Nunataks. As in rocks of the overall Lassiter Coast (Kellogg and Rowley, 1974), joints may be di~ I TABLE 4.——Results of X-ray determination of sheet silicates from [Sample localities shown in figure 6. Kgd, granodiorite porphyry dike; Kc, Copper Nunat Numbers given in estimated percent by volume of total rocks. rounded to nearest 5. Tr equal to; 3, greater than or equal to] GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PE NINSULA I vided into two groups: barren joints and less common epidote-coated joints. Most barren joints (fig. 20) strike north—northeast and east-west; they are probably shear joints. In contrast, most epidote-coated joints strike be- tween north-northwest and west—northwest. They are interpreted as extension joints and mark the position parallel to the direction of maximum principal com— pressive stress. This strike direction is paralleled by the dacite and granodiorite porphyry dikes and the main mode of aplite-pegmatite dikes of the Copper Nunataks pluton intrusive event; the parallelism suggests intrusion along the extension position and in- dicates that the stress field direction was long lived. The sheared phyllic—argillic zones (p. 25) also have an average strike of northwest and may reflect vertical movement along the previously established trend of open joints. The direction of maximum principal com- pressive stress interpreted from trends of Upper Cre- taceous dikes and Upper Cretaceous and post(?)-Upper Cretaceous joints is not far removed from that which produced the period of northeast- to north-northeast- striking tight folds sometime between Late Jurassic and Late Cretaceous time (Williams and others. 1972; Kellogg and Rowley, 1974). OLDER SHEAR FRACTURING, HYDROTHERMAL ALTERATION, AND MINERALIZATION The medium—grained granodiorite of Nunataks B and C was sheared with accompanying minor hydro- thermal alteration and mineralization prior to intru- sion of the Copper Nunataks pluton. This took place during two events, described by their field names as an early set of crisscrossing ”gray shear fractures” and a late set of crisscrossing "black shear fractures;” the late set out across the early set. The black shear frac- tures cut the dacite dike; presumably the gray shear fractures also cut the dacite dike, but this was not ver- ified by the field evidence. The gray shear fractures consist of numerous individual fault planes; in most places they are 1—5 cm wide but locally are as wide as 50 cm. The rock has been mylonitized to a light- to hydrothermally altered rocks of the Copper N unataks, Antarctica aks pluton; Kg, granodiorite pluton. Inter ,, significant trace, probably s pretation of X»ray data by Leonard G, Schultz, everal perce nt: Tr.?, possible significant trace; S, less than or Rock Sample Total sheet Alteration type unit No. Scricite Montmorillonite Kaolinite Chlorite silicates Phyllic ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Kgd M303e 40 S5 Tr.? Tr.? 45 KC M3011 S35 5 T1? 210 50 Kg M309h 30 10 5 5 5O Argillic ................................. Kg M309c 25 >5 Tn? 5 40 Argillic (deuteric) ,,,,,,,,,,,,,,,,,,,,,, Kgd M314a 15 Tr. Tr.? S15 30 Propylitic ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Kgd M303c 10 Tr. Tr.? S10 20 KC M301h S15 Tr. Tn? S5 20 OLDER SHEAR FRACTURING, HYDROTHERMAL ALTERATION, AND MINERALIZATION FIGURE 16.~Fresh contact phase (chilled margin) of granodiorite porphyry dike: sparse phenocrysts of plagioclase (p1) and embayed "beta” quartz (Q) in a groundmass of fine—grained anhedral K—feldspar, quartz, and lesser plagioclase and hornblende. Speci» men M404c. Crossed polars. medium—gray, fine-grained rock (fig. 9). The black shear fractures consist of numerous individual fault planes that are generally less than 5 cm wide, but in many places are more than 1 m wide. The rock has been mylonitized to a black fine—grained rock (fig. 21). Typically, the shear planes of both types of fractures are spaced at intervals of about one-half to several meters. Shear-fracture planes of both the gray and black sets dip steeply and strike in many directions; relative displacement is difficult to determine in this igneous terrane, but where it could be measured, the displacement is from several centimeters to over sev- eral meters in a predominantly vertical component. The relatively widespread extent, minor size, and small amount of offset suggest that both shear-fracture sets are probably best considered as the results of crackling or breaking. These two sets occur in the same areas on Nunatak B and are best developed within about 100 m of the quartz monzonite intrusive con— tacts; they also overlap each other over most of 21 FIGURE 17.——Fresh interior phase of a granodiorite porphyry dike: abundant phenocrysts of mostly zoned plagioclase (pl), embayed "beta” quartz (Q), hornblende (hb), partly chloritized biotite (bi), and accessory magnetite (mag) and sphene (sp) in a groundmass of myrmekitic K-feldspar and quartz and lesser hornblende, plagio- clase, and opaque minerals. Specimen M311c1. Crossed polars. Nunatak C. Similar shear fractures cut the stoped blocks of granodiorite within the Copper Nunataks pluton at Nunatak A. Minor hydrothermal alteration affects both sets although shearing and alteration is greater along the black shear fractures and is accom- panied by minor pyrite mineralization. Microscopically the mylonite of the gray shear- fracture set consists of very fine grained (mostly 10 or 20am or less) equant anhedral crystals of quartz, less abundant feldspar, minor green hornblende, and traces of magnetite (fig. 22). The wallrock, from the megas- copic edge of the shear fracture outward to about 5 mm, exhibits partial recrystallization of much of the feldspar and quartz creating a fine-grained rock simi- lar to that within the shear fracture. Most relic quartz has sutured boundaries, relic green hornblende is fresh but ragged and anhedral, and biotite has recrystallized to clusters of small (less than 0.3 mm) randomly oriented brown biotite. This alteration zone rapidly grades into an outer zone 5 cm wide where only clus— 22 PERCENT GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA N V m E m 2 0'7, N 5t E MD (imam~ mm o '\ FLU 1—1—me V000 0" 0 FN FFNOLD VF” N 0') mm mmmmm v-mst ~ o O U) 2 2 0 10 8 0 e 8 4 2 O 10 O 8 ¥ 6 + \ G ‘1 4 \\ (V . . Z _ 2 index PERCENT O CALC’ALKAL'C I CALC'C 16 Trend line for rocks of younger episode 4 14 O _____ ‘ \\ £6. 2 A ————— 12 0 DJ. 10 /,/ \fis / / / 6 8 ,// Trend line for rocks 0 4 M 6 /// of Older eDESOde IV / ¥ __ /\,_ 5/ 2 A—l—_—I_——l———_l_——J I WI I I 4 I I I I | I I | I 54 56 58 60 62 64 66 68 70 72 74 54 56 58 60 62 64 66 68 7O 72 74 s: o, EXPLANATION 5' 02 Cretaceous Cretaceous Younger igneous episode A Granodiorite porphyry dike O Quartz monzonite of Copper Nunataks pluton + Assimilated rocks — Of Same age as Copper Nunataks pluton FIGURE 18.—Variati0n in common oxides (weight percent), selected tr sro2 ( percentage content) for specimens from fresh rocks from the Older igneous episode A Dacite dike O Granodiorite pluton 0 West RARE pluton a Of same age as granodiorite pluton ace elements (ppm), and differentiation index plotted against major igneous units, Copper Nunataks. From data in table 2. RACTURING, HYDROTHERMAL ALTERATION, AND MINERALIZATION 23 OLDER SHEAR F K of older episode Trend line for rocks of younger episode A Or Ab+An A=Al1 O; -(Na; 0+K2 O) F=Fe”+Fe” +Mn M=Mg C=CaO-(3P2 05 +002) D F=FeO+MnO+M90+2Fe1Og-Tioz A|k=Na+K C EXPLANATION Cretaceous Cretaceous Older igneous episode Younger igneous episode A Granodiorite porphyry dike A Dacite dike Quartz monzonite of Copper 0 Granodiorite pluton Nunataks pluton 0 West RARE pluton — Of‘same + Assimilated rocks — Of same age as granodiorite pluton age as Copper Nunataks pluton arth’s cations, and oxides from fresh rocks from the major igneous FIGURE 19.—Ternary plots of selected normative minerals, B Normative quartz-orthoclase-plagioclase (Ab+An), units, Copper Nunataks. From data and recalculation of data in table 2. (A) (B) Na-K—Ca (cation percent), (C) Alk-F-M (cation percent), (D) A-C—F (weight percent), 24 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA O 5 10 JOINT READING PER 50 OF COMPASS BEARING EXPLANATION Epidote joints Barren joints FIGURE 20.—Rose diagram of strikes of systematic steeply dip- ping joints in rocks of the Copper Nunataks. ters of recrystallized biotite distinguish it from fresh rock. Hydrothermally altered rock consists of chloriti- zation of biotite and light to moderate saussuritization of relic feldspars. It occurs within parts of the shear fractures and the adjacent wallrock, but is not neces- sarily axial to the shear features. A semiquantitative FIGURE 21.—Pegmatite and aplite dikes at outcrop M300, Nunatak B. The dikes crosscut their parent granodiorite pluton and are offset by a series of parallel small black shear fractures. FIGURE 22.—Edge of a black shear fracture. Sheared and recrystal- lized fine-grained anhedral crystals of quartz, feldspar, hornblende, and, in smaller amounts, magnetite and pyrite in con— tact with a partly sheared relic quartz crystal. Specimen S57h. Partly crossed polars. spectrographic analysis (table 3, sample B26g) reveals that the gray shear-fractures are almost completely devoid of element additions. The rock shows a possible increase in V and depletions in Fe, Mg, Ca, Ti, Mn, Cr, Sc, Sr, Y, Zr, and apparently Ba, Be, Co, Cu, and Ni relative to fresh rock. The black shear fractures have significantly more recrystallized and altered rock within their wallrocks than do the gray shear fractures. Furthermore, in sev- eral places pyrite veins as much as 5 mm wide occur in or adjacent to black shear fractures. Microscopic study of nine thin sections reveals that the mylonitized rock in the core of the shear fracture is in large part recrys- tallized to equant anhedral crystals of quartz, feldspar, hornblende, and opaque minerals that average 10— 100,um in size. Both hornblende and opaque minerals are more abundant (as much as 50 percent by volume) and commonly occur as larger crystals (as much as 1 mm) in black shear fractures than in the gray shear YOUNGER SHEAR FRACTURING, HYDROTHERMAL ALTERATION AND MINERALIZATION 25 fractures. In many rocks pyrite makes up most of the opaque minerals, and the abundance of ferromagne- sian minerals undoubtedly causes the black color in the shear fractures. In some places the shear fractures contain sparse to abundant, sheared and recrystallized fragments of wallrock and coarse-grained quartz. The feldspar and quartz in the wallrock is partially but extensively recrystallized to a fine-grained quartz- feldspar rock similar to that within the shear fractures for at least 3 cm outward from the shear fracture. Relic wallrock in and about 5 mm beyond this zone lacks biotite and contains introduced pyrite and possibly magnetite. Hornblende occurs as fresh anhedral poikilitic crystals, either relic or replacing biotite; pla— gioclase is at least slightly saussuritized. Rock about 1 cm beyond this zone is relatively fresh but, like the wallrock near the gray shear fractures, original biotite has been recrystallized into clusters of randomly oriented, small (maximum 0.3-0.4 mm) crystals. This rock in turn grades into fresh wallrock 4 or 5 cm be- yond the edges of even the smallest shear fractures. The shear fractures are commonly hydrothermally al- tered, but maximum alteration does not necessarily coincide with the central part of the shear fracture. Alteration within the shear fracture results in exten- sive saussuritization of feldspar, chloritization of bio- tite, and occasionally moderate epidotization of plagio- clase and biotite. Hydrothermal alteration is presumed synchronous with crackling. Semiquantitative spec— trographic analyses of nine black shear fractures (table 3) shows some changes in elements by alteration solu- tions relative to that of fresh rock. The analyses show that Fe, Mg, Mn, Co, Cr, Cu, M0, Ni, Pb, and V have been introduced, and Al, Na, Ca, Ba, Sr, Y, Yb, and Zr have been lost. YOUNGER SHEAR-FRACTURING, HYDROTHERMAL ALTERATION, AND MINERALIZATION Following intrusion of the granodiorite porphyry dikes, rocks at scattered places in Nunataks A, B, and C were sheared to various degrees with accompanying hydrothermal alteration and mineralization. The end result of these associated events, which terminated the Copper Nunataks pluton intrusive episode, was the Lassiter Coast copper deposit. Shearing took place along narrow linear “sheared phyllic-argillic zones” that crosscut all igneous rocks in the area (figs. 4, 23A, B, C, D). Mineralization con- sisted mostly of copper and iron sulfides and oxides occurring both as disseminations and as concentrated masses (as much as 10 cm across) in veins of coarse- grained quartz and in altered wallrock. Most mineralized rock occurs at Nunatak C, with a lesser amount at Nunatak B, and a minor amount at Nunatak A. Mineralized rock is most abundant where sheared phyllic-argillic zones are most abundant; how- ever, it rarely occurs within such zones but is usually found adjacent to them. Most mineralized rock is in the granodiorite batholith within several hundred meters of the Copper Nunataks pluton contact. This localiza- tion of mineralized rock probably is caused by two factors—the great abundance here of sheared phyllic- argillic zones and the great amount of fracturing (in- cluding both gray and black shear-fracturing) that this rock has undergone; both factors provide pathways for mineralizing solutions. Mineralization and alteration are considered to be genetically related to, and roughly simultaneous with, each other. Sheared phyllic-argillic zones are made up of light- tan to medium-brown hydrothermally altered rock. They range in width from less than a centimeter to at least 20 m, averaging 1—2 m. All sheared phyllic— argillic zones are vertical to steeply dipping and most strike west-northwest (the dominant direction at Nunataks A and B) to north—northwest (at Nunatak C) (fig. 23D). Unlike the gray and black shear fractures characterized by mylonite and only lesser altered rock, sheared phyllic-argillic zones are recognized by in— tensely altered rock with only minor volumes of ob- served slickensides or mylonite. Phyllic and argillic altered rock (terminology of Lowell and Guilbert, 1970) and minor silicified rock characterize the zones. The contact between zones and less intensely altered propylitic rock (Lowell and Guilbert, 1970) is grada— tional within 10 cm in most places, and thus it is well defined. Propylitic altered rock extends for several meters to several tens of meters beyond the edges of the zones, and there it grades into fresh rock. Sheared phyllic-argillic zones are best developed at Nunatak C. Here all rock is transected by zones of various widths occurring at intervals of from several meters to about 10 m; thus all rock at Nunatak C is altered to some degree by either sheared phyllic-argillic zones or in- tervening propylitic rock. Phyllic—argillic altered rock at Nunataks A and B is restricted to several zones less than 3 m wide. Where offset could be determined for the sheared phyllic-argillic zones, it is vertical and commonly less than several meters (fig. 23D); some aplite-pegmatite dikes cut by sheared phyllic-argillic zones are not offset. However, two zones at Nunatak B have rela- tively large measurable displacement. The west- northwest-striking fault at the northwestern part of the nunatak (fig. 4) cuts the subvertical dacite dike, subvertical granodiorite dike, and east-dipping quartz monzonite contact with right-lateral apparent offset of 26 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA FIGURE 23.—Sheared phyllic-argillic zones. A, Narrow (10 cm) northwest-striking zone cutting lighter colored C , Dark, relatively crumbly rock of a sheared zone near the ice ax, at rock of Copper N unataks pluton, outcrop M301, Nunatak B. outcrop M317, Nunatak A. Lighter, more resistant, fresh to prop- ylitic altered rock of the Copper Nunataks pluton makes up the jointed northwest-trending face. B, Darker and mostly weaker rocks of several bifurcating 1—3 m wide D, A series of small parallel sheared phyllic-argillic zones, striking zones that transect rock of the Copper Nunataks pluton. View is to the upper left (northwest) and dipping steeply to the right southeast along strike of the zone from outcrop M301, Nunatak B. (northeast) at outcrop M326, N unatak C. Note offset of a subverti- The areas of lowest relief and the rock fragments of smallest size cal pegmatite dike by several sheared zones, left and above the mark the axial, most intensely altered parts of the zones. The man’s head. Most of the outcrop is rock of the granodiorite pluton. freshest rock shown is the lighter colored propylitic altered rock in the upper left corner. Ice ax in center of photograph for scale. YOUNGER SHEAR FRACTURING, HYDROTHERMAL ALTERATION AND MINERALIZATION about 10 m, 20 m, and 100 m, respectively. The best estimate of actual displacement is that the north block was upthrown relative to the south block at least 50— 100 m. The north—northeast-striking fault near the eastern end of the nunatak requires one of the follow- ing: at least 50—100 m of vertical component displace— ment, about 20 m of left—lateral strike-slip movement, or a combination of both in order to offset the subverti— cal dacite dike as shown on the map (fig. 4). Elsewhere on the Lassiter Coast, significant high-angle faulting has not been found. Therefore we consider offset as- sociated with the sheared phyllic-argillic zones to be a localized breaking due to late-stage igneous move— ment; it probably does not represent regional tec- tonism. MINERALIZATION The Lassiter Coast copper deposit consists of coarsely disseminated hypogene sulfide and oxide min- erals and quartz veins containing hypogene sulfide and oxide minerals. Minerals are most abundant in nunataks where sheared phyllic-argillic zones are most abundant; minerals usually occur in propyliti- cally altered rock and are sometimes found in the sheared phyllic-argillic zones themselves. Field evi— dence on the relative ages of minerals and sheared phyllic-argillic zones is unequivocal in four locations at Nunatak C. Here quartz veins and minerals appear to cut sheared phyllic-argillic zones in some places, but in two outcrops sheared phyllic-argillic zones cut quartz veins. We conclude that mineralization and shearing— alteration probably were nearly concurrent, but mineralization locally may have predated shearing and alteration slightly. Mineralized quartz veins do not appear to have al- teration envelopes of their own. They have an average width of 2 cm and may be more than 10 cm Wide, which is unusually wide for veins of porphyry deposits. Most mineralized quartz veins occur at Nunatak C and the western half of Nunatak B, where they are irregularly spaced at intervals of from several meters to a dozen meters. Thus they are generally widely scattered, another feature dissimilar to those of porphyry de- posits; more than one quartz vein rarely crops out within an area of a square meter. Most veins consist largely of quartz, with few or no megascopic sulfide and oxide minerals. Some veins, however, consist largely of opaque minerals. The principal opaque vein minerals are magnetite, pyrite, chalcopyrite, and molybdenite; in some places lenticular masses as much as several tens of centimeters long consist of fine- to coarse- grained epidote. Minor hornblende may accompany magnetite. Disseminated sulfides and oxides are slightly more abundant than veins and occur as either single crystals 27 or elongated masses as much as 10 cm long. These sulfides and oxides are found mostly at Nunatak C and in the western half of Nunatak B. They occur as bodies of disseminated crystals or clots several cubic meters in size or as widely distributed crystals or clots irregu- larly spaced anywhere from several to 20 m. Finely disseminated minerals also occur locally in the chilled margins of the granodiorite porphyry dikes. Thus dis- seminated minerals also are much coarser grained and more widely scattered than those in commercial por- phyry copper deposits; nowhere did we find large out- crops comprised of finely disseminated sulfides. Chal- copyrite and pyrite are the most common ore minerals, whereas molybdenite is uncommon. In some places clots are concentrically zoned with chalcopyrite more abundant near the center and pyrite and limonite more abundant on the margins. Most disseminated crystals or clots are surrounded by halos of rusty limonite and (or) bright-yellow oxide stains extending 10 cm or more beyond the edges of the sulfide minerals. Supergene minerals are rare in this extremely arid region where ground water is absent. Malachite and possibly chrysocolla, however, are conspicuous in many places adjacent to concentrations of hypogene copper minerals and occur as small crusts that rarely exceed several square centimeters in size. Limonite and hematite occur in cracks or surround magnetite, pyrite, and chalcopyrite. Examination of 7 thin sections and 13 polished sec— tions shows that the major copper mineral is chalcopy- rite; malachite, chalcocite, and possibly bornite are rare. Pyrite crystals and leafy masses (as much as sev- eral centimeters long) of molybdenite are commonly intimately associated with the copper minerals. Magnetite is one of the most abundant opaque miner- als in the veins and occurs either in massive form as much as 10 cm in diameter or as small to medium- grained plates or radiating plates. Magnetite masses may occur alone or may be associated with all or some of the other minerals. Limonite and hematite are mostly secondary and form rims in cavities adjacent to magnetite, pyrite, and chalcopyrite. In many places the wallrock adjacent to ore minerals is remarkably fresh with only minor epidotization of plagioclase and minor chloritization of biotite. In other places feldspar is moderately to highly altered to seri- cite and clay minerals, biotite is altered to chlorite and epidote, hornblende is altered to uralite, magnetite is partially altered to hematite, and rutile and limonite are present. In some areas biotite is recrystallized to clusters of tiny, randomly oriented crystals, and feld- spar is partly recrystallized to fine-grained anhedral quartz-feldspar masses; quartz is increased in volume by addition of rims of fine-grained quartz crystals. Al- 28 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA tered rock generally grades into fresh rock within 1 or 2 cm from the ore minerals. Most rocks from mineralized areas (table 3, 19 semiquantitative spectrographic analyses) show in- creases in Fe, Ag, Bi, Co, Cu, Mo, Ni, Pb, and Zn, and depletions in Al, Mg, Ca, Na, K, Mn, Ti, Ba, Be, Cr, La, Sc, Sr, Y, Yb, and Zr. Trace element changes are simi- lar to, but greater than, those due to sheared phyllic- argillic zones. Highest values were recorded for the quartz veins. A few of these quartz veins locally con— tain over 10 percent Fe by weight, 3 percent Cu, 0.7 percent Pb, 0.15 percent M0, 700 ppm Zn, 700 ppm Bi, 500 ppm W, and 300 ppm Ag. The grade of the rock at Nunatak C, where sulfides are most abundant, proba— bly does not average over 200 ppm Cu or 100 ppm Pb, and averages less than 50 ppm Mo—and such values are well below ore grade for commercial porphyry cop- per deposits. In line with recent studies of copper content in bio- tites of plutons associated with copper deposits (for example, Lovering and others, 1970; Banks, 1974), semiquantitative spectrographic analyses were deter- mined for a biotite-hornblende separation from three samples each of the granodiorite batholith, Copper Nunataks pluton, and granodiorite porphyry dikes. All samples were fresh rocks collected from three of the major nunataks (fig. 6). The results of the nine analyses (table 5) show that neither copper nor any other minor elements added during mineralization are concentrated to any significant degree in the biotite or hornblende of the associated fresh igneous units. PHYLLIC AND ARGILLIC ALTERATION Most sheared phyllic-argillic zones contain a medium-brown, completely sericitized rock and a less altered rock in which feldspar is tan or brownish pink owing to various stages of alteration and biotite is al- tered to green chlorite. The former rock type (mostly "phyllic alteration” of Lowell and Guilbert (1970); "sericitic alteration” of Meyer and Hemley (1967)) generally occupies the more central parts of the zones, and the latter rock (mostly “argillic alteration”) oc- cupies the outer parts; but the two are mutually grada- tional and were not differentiated in the mapping or in this discussion. “Potassic” altered rock may occur loc- ally in some or most sheared phyllic-argillic zones but it does not appear to make up significant parts of the zones. Phyllic altered rock generally weathers easily to medium-brown pebble- or sand-size grus and produces long linear “trenches” on the outcrop. The grade of a1- teration in some small shear fractures is only argillic. Eleven thin sections of phyllic and argillic rock (five from the granodiorite, four from the Copper Nunataks TABLE 5.—Serniquantitatiue spectrographic analyses of biotite» hornblende separates from fresh igneous rocks in the Copper Nunataks, Antarctica [Sample localities shown in figure 6. Kg, granodiorite pluton; Kc, Copier Nunataks luton: gd. granodiorite porphyry dike. Analyses by L. A. Bradley. Not erected or at imit of detection: Ag, As, An, B, Bi, Cd, Eu, Ge, Hf, In, Li, P, Pd, Pf, Re, Sb, Sm, Ta, Te. Th. T1, U, W. \ Estimated volume of A] Fe Mg Ca Na K Ti biotite: \ hornblende Rock Sample unit No. in sample Welght percent Kg .. . J , M308a 80:20 7 10 '3 5 0.7 3 l M321c 80:20 7 10 3 3 ,7 5 1 S5711 80:20 7 10 3 3 .7 5 1 Kc ,, , , , M30011 50:50 7 10 7 7 1 2 5 M321j 60:40 7 10 7 5 .7 3 .7 M42213 70:30 5 7 5 5 1 3 .7 Kgd . H , .. M311b 50:50 5 7 5 7 .7 1.5 .7 M3256d 60:40 7 7 5 7 .7 3 1 M404d 60:40 5 10 5 7 7 3 7 1 O O 01 O a L L 50 30 20 N 3,000 N5 300 N L 50 50 7 20 50 3,000 N5 300 N L 30 70 15 20 N 3,000 N5 70 2 L 30 15 3 20 50 3,000 15 700 2 L 50 15 3 20 70 5,000 N5 500 3 L 30 15 7 20 50 3,000 N5 150 L L 20 15 30 20 70 3,000 N5 150 1.5 200 30 50 30 20 100 3,000 N5 700 L L 30 15 7 20 70 3.000 N5 \ Nb Nd Ni Pb Sc Sr V Y Yb Zr 15 L 0 N 70 70 500 50 7 70 20 100 30 N 70 70 300 70 7 100 2 L 30 15 70 70 500 '30 7 70 10 L 15 N 70 70 300 30 e 70 15 L 15 10 100 30 300 30 5 150 20 L 15 15 70 70 200 30 7 100 1:) 150 10 L 70 150 300 70 7 100 20 150 15 10 70 300 300 70 7 100 15 150 10 20 70 150 300 70 7 70 pluton, two from the studied. Phyllic rock is mostly intensely altered, and it con- sists almost entirely of quartz and fine-grained sericite and clay (figs. 24, 25, 26). Most quartz forms relic crys- tals containing some secondary growth on the outside of the crystals, and it has undulose extinction and ir- regular to vaguely sutured boundaries. All feldspars have been recrystallized to fine-grained sericite and clay. Biotite alters to mostly fine- or medium-grained sericite; the sericite commonly is associated with minor leucoxene and limonite. Hornblende changes to fine-grained sericite and lesser leucoxene, rutile(?), limonite, and hematite; the oxide minerals sometimes occur as a rim around the sericitized crystals. Hema- tite blades lace some altered hornblende crystals. Cal- cite may be present in the rock. Opaque minerals con- sist of minor magnetite-limonite and pyrite; sphene is altered to leucoxene. Tiny sericite veins are locally Vis- ible in some thin sections. In less altered rocks, patches of fresh K-feldspar show through the sericite and clay. granodiorite porphyry) were YOUNGER SHEAR FRACTURING, HYDROTHERMAL ALTERATION AND MINERALIZATION FIGURE 24.—Phyllic altered rock of the granodiorite pluton: all feldspar (light gray in photo) is converted to fine—grained sericite and clay, and relic quartz (white) remains. Hornblende crystal is converted to medium-grained sericite spotted with leucoxene and is surrounded by a dark limonite-hematite rim. Specimen M309h. Plane light. In argillic rock, plagioclase is moderately to com- pletely converted to sericite, clay minerals, and minor calcite, and K-feldspar is slightly altered to sericite and clay (fig. 27). Biotite is moderately to totally al— tered to chlorite (penninite?), minor leucoxene, and rare epidote. Hornblende is either fresh or moderately altered to chlorite and subordinate leucoxene, hema- tite, limonite, sericite, and minor epidote. Accessory minerals include magnetite, hematite, and pyrite; sphene may be totally altered to leucoxene. Relic quartz with secondary growth and uralite after hornblende develops with more intense alteration. X-ray studies (table 4) show that total sheet-silicate content is greater in the phyllic rocks than in the argil- lic rocks. Sericite is most abundant in both alteration types. Montmorillonite is significantly higher and kaolinite may be higher in phyllic rocks than in argil- 29 FIGURE 25.——Phyllic altered rock of the granodiorite porphyry dike: all feldspar, which occurs as phenocrysts and in the groundmass, is altered to fine—grained sericite and clay (light gray in photo), whereas relic embayed ”beta” quartz phenocryst (upper left) and quartz in the groundmass remain largely unchanged. The biotite phenocryst (lower left) is altered to medium-grained sericite spot- ted with leucoxene and limonite-hematite. Two large dark hornblende phenocrysts (center) are altered to fine-grained sericite—leucoxene and are largely rimmed by limonite-hematite. Several small crystals of magnetite (mag) are laced with hematite. Specimen M303e. Plane light. lic rocks. Chlorite is less abundant in phyllic rocks than in argillic rocks. Semiquantitative spectrographic analyses of 20 samples from sheared phyllic—argillic zones (table 3) show that Cu, Pb, Mo, and probably Ni, Ag, and Bi were introduced, and that Al, Na, Ba, and probably Mg, Sr, Y, and Zr were depleted. PROPYLITIC ALTERATION Phyllic-argillic altered rock grades sharply into propylitic rock over several centimeters or even over several millimeters. Study of six thin sections (two of the granodiorite, two of the Copper Nunataks pluton, two of the granodiorite porphyry) shows that altered 30 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA FIGURE 26.—Sheared and phyllic altered rock of the Copper Nunataks pluton: feldspar is sheared and almost totally altered to fine-grained sericite and clay (ser). Ferromagnesian minerals are totally altered to darker sericite, chlorite (chl), leucoxene (leu), and epidote (ep). Several of the shear planes are filled with chlo— rite. Relic quartz (Q) is sheared and broken, and it commonly has sutured boundaries. Specimen M301c. Plane light. plagioclase contains tiny crystals of sericite and clay minerals and minor epidote and calcite (fig. 28). Biotite is slightly to largely altered to chlorite (penninite?) and is altered to less abundant epidote and leucoxene; altered minerals are concentrated along mineral cleavage planes. Hornblende is generally fresh, but it may be slightly altered to chlorite or sericite, either of which may contain minor leucoxene and hematite. Some opaque crystals are rimmed by hematite or limo- nite. In most rocks K—feldspar is not altered. X-ray studies (table 4) show that sheet silicates are significantly lower in concentration in propylitic rocks than in more intensely altered rocks. Sheet silicates consist mostly of sericite; montmorillonite and kaoli- nite are uncommon. Chlorite is somewhat less abun- dant than in argillic rocks. .3- FIGURE 27.—Argillic altered rock of the Copper Nunataks pluton: plagioclase is completely replaced and K-feldspar (K) moderately replaced by fine-grained sericite and clay (ser). Hornblende and biotite are completely replaced by chlorite (chl) and leucoxene spots. Quartz(Q) is unchanged. Magnetite (mag), laced with hema- tite, and apatite (ap) are present. Specimen M301i2. Partly crossed polars. EPIDOTE ALTERATION Epidote occurs as a replacement mineral in the form of small irregular masses and coatings along fractures not only in the Copper Nunataks but also in plutonic rock throughout the Lassiter Coast. Its occurrence is almost universally confined to subvertical joints (see p. 20) cutting plutonic rocks and striking in the exten- sion direction to the northwest. Crosscutting relations show that some epidote-coated joints developed follow- ing intrusion of the granodiorite pluton and prior to intrusion of the Copper N unataks pluton, but most ap- pear to postdate the Copper N unataks pluton. Presum- ably epidote is related to very late-stage igneous solu- tions on a regional scale and is not confined to any alteration or mineralization event, such as those as- sociated with the copper deposit. However, some epi- dote masses and coatings are abundant in and adjacent MINERALIZED AND ALTERED ROCK ELSEWHERE IN THE LASSITER COAST 31 FIGURE 28.——Propylitic altered rock of the granodiorite pluton: pla— gioclase (pl) is lightly to moderately altered to fine-grained sericite and clay, especially along mineral cleavage, but K-feldspar (K) is only slightly altered. Biotite is totally altered to chlorite (chl), and minor epidote (ep) is spotted with leucoxene, but hornblende (hb) is fresh. Quartz (Q) is unchanged. Specimen M301e. Plane light. to the sheared phyllic-argillic zones and thus probably result from a low-intensity hydrothermal event. Microscope examination of three epidotized rocks shows that most biotite and hornblende in the rock are altered to chlorite and fine- to medium-grained epi- dote. Plagioclase may be altered to sericite and clay minerals or it may be fresh with the exception of some contained fine epidote grains. Locally, all minerals ex- cept quartz are replaced by epidote. SILICIFICATION Masses of pale—green silica, as much as several cubic meters in volume, were mapped within part of a single 3-m-wide sheared phyllic—argillic zone at Nunatak B. The rock in one thin section (M309g) consists almost entirely of introduced fine—grained (mostly less than 0.4 mm) quartz as anhedral to subhedral prismatic crystals (fig. 29). Some sericite, and minor hematite FIGURE 29.—Si1icified rock from the interior of a sheared phyllic- argillic zone that cuts the granodiorite pluton. Most of the rock consists of small prismatic crystals of hydrothermal quartz, grown largely along two preferred directions. Two large crystals of relic quartz (Q) are visible, and minor sericite and clay minerals have replaced small amounts of remaining feldspar and ferromagnesian minerals. Specimen M309g. Crossed polars. and limonite, and some original relic quartz crystals constitute the rest of the rock. Semiquantitative spec- trographic analysis shows that this same specimen (table 3) is similar to other rocks from the sheared phyllic—argillic zones. MINERALIZED AND ALTERED ROCK ELSEWHERE IN THE LASSITER COAST AND SOUTHERN BLACK COAST Other sightings of mineralized‘ and hydrothermally altered rock were made in the LassiterCoast and southern Black Coast (figs. 1, 2) by all members of the three field parties. No occurrences were found that were as rich as or as extensive as the Lassiter Coast copper deposit; they were noted during our reconnais- sance geologic studies and were not investigated in de— tail. Many of these were sampled, however, and the 32 Host rock type Sample no. Rol3abc—-—— Ro75bc ————— RolSOb ————— R0198de—--— R0199bc— -— R0215c ————— W150ze ————— Wa17b1— ——- Wa37b —————— C) {.4 F‘L—‘l—‘r‘ UL—‘r‘U'U R0315d ----- L R0315h ----- 6 Average (311)—- PQM PQD PG 8064b ------ Re37b—- - Rol49b ----- PG PG PQD S41b ------- w139d2 ----- Average (a11)—— A1 r—‘bc‘o‘ 0‘th bxnomb wuoow: uv (In—4m Fe Nu—kuvw wNNr—I bwu‘ox >—‘ D—‘ mmom L‘NNN .b we» wmow ,_. b \JD—‘U‘O N NM HLnH \1 H ,_. UI unvxnoso unwrvmo vubwu‘w L‘bO‘mH U-bw Weight percent Mg [“0 ,_. H‘H 0‘ m PIH #40:» ,_. HM men: ,_.,_4 Hb NHHHO 0;wa ouow 0.20000 ooouvmm menLn wor—Iu‘ Nb—‘U‘IN boob: owou \aownm r—u—‘r—‘wr—I moomo w mmxlom ouvowo OOH .01 ,_. '1‘ H ww L» >—4 Ca Na K Ti Ag B Pegmatite 0.3 >0.3 2 0.01 0.1 <10 . —- —— -— N L Hydrothermally altered 3 >0.3 5 0.2 <0.1 <10 6 >.3 5 .6 <.1 <10 2 -— —- .1 N 100 4 >.3 2 .2 .1 <10 .3 .03 >1 .2 .5 20 5 >.3 5 .1 <.1 <10 3 >.3 1 .1 <.1 <10 3 >.3 2 .1 .1 <10 3 >.3 3 .4 <.1 <10 1 >.3 4 2 <.1 <10 3 >.3 3 1 <.1 <10 1 >.3 5 1 < 1 <10 4 >.3 5 2 1 <10 4 >.3 5 .1 <.1 <10 3 >.3 3 ,1 <.1 <10 3 >.3 5 .2 .3 <10 4 >.3 >1 .2 <.1 <10 2 —— -— 5 N L 2 —- -— 3 N L .1 —— —- 2 N 15 2 —- —— 2 L L 3 >.3 5 .2 <.1 <10 2 —- —- .2 N 10 .1 -- —— .3 N L 2 >.3 3 .1 <.1 <10 3 >.3 3 .4 .1 <10 2 >.3 4 .2 <.1 <10 3 >.3 5 .1 .1 18 3 >0.3 4 0.2 >O.1 >6 Barren vanadium 15 —- —— 0.1 N L .2 —— -— .5 N 30 .3 -- -- .1 N L L —- -— .1 N L 2 -— -- .2 .5 L 10 —— —- .02 N L .1 -— —- .1 N L 1 -- -— .2 1.5 10 4 -- -— 0.2 >0.3 >5 Mineralized rock 0.2 —- —— 0.1 0.5 L .1 H >1 .1 1.3 14 1 3 7 .1 1.2 <10 1 4 6 .1 <.1 <10 1 02 1 .04 <.1 <10 .4 .2 >1 .2 <.1 17 6 >.3 >1 .5 <.1 <10 8 >.3 >1 .3 .4 <10 1 >.3 4 .5 <.1 22 3 >.3 2 .2 <.1 <10 <.1 >.3 .1 .03 7 <10 7 >.3 2 .2 <.1 <10 1 >.3 5 .1 <.1 <10 1 >.3 >1 .2 <.1 36 5 >.3 3 .3 <.1 <10 .2 <.Ol < 1 .003 1.2 <10 2 -- —— .2 2 L .2 -- —— .01 N L .1 .2 l .004 <.1 <10 5 -- -- .3 N L 6 1 .2 .3 1.8 <10 .1 1 1 .02 <.1 <10 4 > 3 3 .1 5 <10 1 .04 1 .1 .1 33 2 >.3 3 .1 >10 <10 2 -- -— 0.2 >1.2 >5 Epidote rock 7 >0.3 1 0.4 <0.1 <10 4 >.3 4 .2 <.1 <10 8 >.3 2 1 .5 <10 .2 -- -— .02 N L 1 —- -- .2 N L 3 >.3 1 .1 <.1 <10 4 >0 3 2 O 2 O 1 <10 Ba 400 150 700 20 100 300 >160 1,500 300 400 Parts per million Be D—‘N A A NNN b—‘l—‘D—‘N r‘r‘NN mmbw NH v ,_. n—u—H—‘r‘ ZZNN >1 HPJN H22 A Bi 2 Z Z Z Z Z Z Z 2 Ce <20 <20 50 100 40 .4 >40 <20 >20 80 <20 60 40 >40 Co NH o weer-dun PAH b \lbbl‘ 4.11me ‘lew \nwom mmvvuu ,_‘ oo bmax 5 50 L 1 1,500 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA mm: 10 300 30 20 60 <3 <3 <3 >1 <3 >2 TABLE 6.—Semiquantitative spectrographic analyses of selected fresh, altered, and mineralized <1 <1 <1 >1 <1 MINERALIZED AND ALTERED ROCK ELSEWHERE IN THE LASSITER COAST 33 rock from scattered locations elsewhere in the Lassiter Coast and southern Black Coast lower limits: As, Au, Cd, Cs, Er, Ge, Hf, Hg, In, lr, Li, Lu, Os, Pd, Pt, Rb, Re, Rh, Rn, Sb, Sm,Ta,Tb,Te,Th,T1,Tm, U; value (1de for spec. B0449: 15 ppm;value ofEr for spec. Ke7g: 3 ppm: value of Ge for spec. B0711): 2 ppm; value of Li for spec. Ka316—4: 45 ppm; value of Li for speci V32c: 38 ppm. G, greater than 10 percent; H, interference; leaders (;l, not looked for; N, not detected or at limit of detection; L, detected but below limit of determination, Symbols for rock type of host rock: L, sedimentary rocks of Latady Formation; V, volcanic rocks; DL, dike cutting Latady Formation; PD, plutonic rocks of diorite com position; PQD. plutonic rock of quartz diorite composition; PG, plutonic rock of granodiorite composition: PQM, plutonic rock of quartz monzonite composition] Parts per million——Continued Sample 132:1: Ga Gd Ho La Mn '10 Nb Nd Ni Pb Pr Sc Sn Sr V W Y Yb Zn Zr no ' type Pegmatite——Continued 15 <3 2 <15 2,000 <1 16 <15 2 30 <2 3 9 5 <1 <10 170 >15 <15 30 —---R0103b PG —- —— —- N N €2,000 N -— L 50 -- N -- N N N N —— N N —————— S343 PG Hydrothermally altered rock——Continued 18 3 <1 30 500 3 4 <15 3 40 5 5 <3 500 70 <10 20 2 50 200 PQM 23 4 <1 30 3,000 5 5 30 3 10 8 15 8 400 200 <10 50 6 90 300 PQM -- -- -— N N N -- 30 N -- 15 —- N 500 N L -— N 70 DL 17 11 2 30 1,300 2 <2 <15 3 10 6 10 <3 800 100 <10 20 5 70 200 PG 15 7 1 3O 50 4 20 8 30 4 7 <3 30 100 <10 60 4 30 100 --Ro13abc PG 3 7 <1 <15 1,000 2 <2 20 20 3 H 20 <3 400 100 <10 7 1 60 30 -——-Ro75bc PQD 13 4 1 <15 1,100 1 <2 30 3 3 5 7 <3 600 70 <10 15 2 60 100 — 9 <3 <1 20 1,000 1 2 20 5 3 6 5 3 200 50 <10 10 1 20 50 — 18 13 3 50 900 7 9 50 2 10 13 10 4 700 150 <10 70 7 50 300 -—-—R0150b PG 19 6 <1 30 400 3 3 4O 1 10 5 5 <3 200 30 <10 20 3 <15 200 ——-Rol98de PG 9 4 <1 15 700 1 3 5O 10 10 5 10 <3 300 70 <10 10 2 20 3O ——-Rol99bc PG 9 <3 <1 40 400 <1 3 40 7 3 6 7 <3 200 70 <10 10 1 <15 200 —--—Rol99g PG 17 <3 <1 <15 900 2 5 <15 3 20 4 7 <3 500 50 <10 15 3 30 70 —--—R0215c PG 23 < 1 <15 600 8 6 <15 2 30 <2 7 3 600 30 <10 20 4 30 200 --——R0225a PG 11 <3 <1 30 500 2 5 30 6 3O 5 10 <3 400 50 <10 30 4 30 150 -——-R0228b PG 20 4 2 30 600 3 8 20 2 40 6 5 4 600 30 <10 30 5 40 100 —---Ro313a PQM 21 4 2 50 1,100 3 5 <15 11 3O <2 7 <1 500 70 <10 20 3 40 200 —---Ro313b PQM -- -— —— 30 1,500 N 10 —- L 20 —- 20 —- 500 150 N 50 —— N 300 —————— S313 PG —— —— —- 30 1,500 10 10 -— L 30 -- 15 —— 500 150 N 30 —- N 200 — —-S34d PG —— —- -- 20 200 N N -— L 30 —- 7 —— N 100 N 15 —- N 70 - —-S38k L -- -- -- N 700 N N -— L 10 -— 7 -- 300 150 L 15 —— N 70 —--—S7lca3 DL 14 <3 <1 <15 700 2 7 <15 3 30 <2 10 <1 400 70 <10 30 6 40 200 ------ V16b PG -- -- -- N 1, 500 N N -— 3O 30 -- 7 -— 200 50 N 20 —- L 70 - —w39aa L -- -— -— 50 300 N 10 —— 20 10 -- 15 —— 200 200 N 30 —— N 200 - -w87c3 PQD 9 <3 <1 20 700 4 <2 20 10 5 4 7 <3 200 70 <10 10 1 20 100 ----- W144b PG 17 12 23 50 1,000 2 7 7O 2 10 10 15 6 700 100 <10 50 7 40 300 ———-W150ze PG 15 <3 <1 40 1,000 10 4 20 5 15 7 7 <3 600 50 <10 20 3 40 100 —— Wa17b1 DL 18 <3 <1 20 1,500 3 6 15 3 20 4 4 <3 150 30 <10 20 3 30 100 ----- Wa37b PQM 15 >4 >1 >30 1,000 >4 >4 >24 >7 >17 >5 10 >1 >400 100 <10 >25 4 >30 150 "Average (all) Barren vanadium——Continued -- —— —- 50 200 N N -— L 20 -- 5 -— N 70 N 15 -— N 50 ------ B21d PG -- -- -- 50 300 N 15 —- 5 30 —— 15 -— 100 150 N 30 —- N 200 L -- -— —— N 70 N N -- L N -— N —- N 10 N L -— N 70 L —- -- —- N 100 N N —— N N -- 5 -— N 10 N 30 —- N 15 ------ S39b DL —— —- —- 20 1,500 N N -- 15 N -- 15 -— 300 50 N 50 —— N 300 —————— S42f L —— —— -— N 2,000 N N —— 7O 50 —- 5 -— 300 N I 15 —— N 20 ————— S45h L -- -- -— N 700 N N —- 7 15 —— 5 —- N 30 N 20 -- N 70 —--SSOg L —— —— —— 20 1,000 N L —— 50 50 —- 10 —— N 70 N 20 -— L 200 ----- $59de L -— -- -- >20 700 N >2 —- >20 >20 -— >10 —— >90 >50 N >25 -‘ N 100 "Average (all) Mineralized rock——Concinued -- —- -- 20 300 N N —- 5 20 -— N —— N 20 N 10 —- <2 <3 <1 20 8,000 3 8 <15 4 2,000 3 2 <3 40 20 <10 15 l 13 <3 <1 20 200 3 9 <15 15 20 11 3O <3 700 200 <10 50 6 14 <3 <1 <15 300 <1 14 <15 2 5 <2 1 <3 150 2 <10 20 3 5 3 <1 <15 2,000 6 6 <15 5 20 2 2 <3 15 7O <10 30 2 3 <3 <1 <15 300 <1 10 <15 7 20 <2 <1 <3 70 30 <10 10 1 12 _5 <1 <15 2,500 6 5 <15 15 7 <2 30 <3 1,000 300 <10 20 3 14 <3 <1 <15 2,000 2 <2 <15 20 8 <2 20 <3 800 200 <10 10 2 20 6 1 50 700 <1 4 50 5 15 8 8 <3 200 150 <10 15 2 13 5 <1 <15 1,000 2 <2 20 7 3 3 7 8 300 100 <10 10 2 <2 5 <1 <15 150 20 <2 <15 2 2 <2 <1 <3 30 <10 <3 <.7 13 5 <1 <15 1, 500 8 <2 <15 7 10 5 20 <3 500 150 <10 20 3 - 7 <3 <1 <15 4,000 2 6 <15 5 70 3 4 14 150 30 <10 20 3 100 150 -——-Ro251b PG 7 5 <1 30 2,500 3 7 30 20 15 6 5 6 150 50 <10 20 3 50 200 —---R0256c L 17 5 <1 30 1,500 6 9 30 2 10 8 10 <3 600 150 <10 50 6 70 200 —--—Ro315d DL <2 5 <1 <15 100 300 6 <15 10 5 <1 <3 3 3 <20 <3 < 2 20 <3 —— —- -- N 500 N N -— 100 N —- 7 —— N 50 50 15 —— 1,500 50 -- -- -- N 70 N N -- N —— —- N 15 L N -- N <2 <3 <1 <15 1,000 3 3 <15 15 50 <2 <1 30 10 10 <10 7 l 150 30 -- —- —- 20 1,500 N N —— 150 30 -— 20 -- 300 200 L 20 —— N 100 <2 3 <1 <15 2,000 4 3 H 80 7 <2 >70 <3 70 >200 <10 7 2 150 30 ----W113de PD <2 4 <1 <15 30 100 <2 <15 1 1 <2 <1 5 7 50 150 <3 <17 <15 10 ----- W139h PQD 22 6 <1 20 3,000 3 <2 20 10 40 5 5 <3 200 100 <10 7 1 150 30 --- -W144c PG <2 <3 <1 <15 300 2 5 <15 9 10 <2 1 <3 70 10 <10 5 1 20 70 PG 10 4 <1 <15 1,000 4 6 <15 3 400 3 10 <3 100 50 <10 10 2 200 100 PQM >8 >3 <1 >9 1,500 >17 >4 >7 >20 >100 >3 >8 >3 >200 >90 >8 >14 >4 >250 >80 --Average (all) Epidote rock-—Continued 27 3 <1 30 2,000 4 9 <15 15 20 11 30 5 700 200 <10 50 6 100 200 ----- B064b PQM 15 6 <1 15 1,000 2 <2 40 4 2 5 9 10 300 100 <10 15 3 30 70 ----- Re37b PQD 70 <3 <1 40 2,500 4 2 <15 <1 15 9 8 17 800 >200 <10 20 4 50 150 ---—Rol49b PG -- —- -- N 30 N N -- N N -- N —- N 30 N N -- N 10 PG -- -- -- L 700 N N —— L 20 -- 10 —- 300 100 N 20 -— N 70 PG 12 <3 <1 30 700 2 <2 <15 5 5 4 6 <3 500 100 <10 10 1 30 15 ———-w139dz PQD 31 >2 <1 >17 1,000 >2 >2 >9 >4 >10 7 >10 7 >400 >100 <10 >15 3 30 100 «Average (all) 34 GEOLOGY OF AN UPPER CRETACEOUS COPPER DEPOSIT, ANTARCTIC PENINSULA results of about 70 semiquantitative spectrographic analyses of these specimens (table 6) reveals that, in overall families of trace elements, the mineralized rock is similar to that of the Lassiter Coast copper deposit, and that the hydrothermally altered rock is similar to that of the sheared phyllic-argillic zones. The main element additions consisted of Cu and less abundant Fe, Zn, Mo, Pb, and perhaps Ag. Essentially all occur- rences were within or immediately adjacent to stocks or batholiths that are probably similar in age (Mehnert and others, 1975; Rowley and others, 1976) to the plu- tons at the copper deposit. The number of occurrences appears to increase somewhat to the north, paralleling the northward increase in the proportion of igneous rock to metamorphosed sedimentary and volcanic rock. Quartz veins are a major locus of mineralized rock and are abundant at many outcrops in the Lassiter Coast. The results of semiquantitative spectrographic analyses of numerous veins reveal two categories of quartz veins. Those veins that occur in sedimentary rocks far from igneous contacts do not contain sulfide minerals and almost invariably do not exhibit any high values of minor elements. They undoubtedly are veins related to metamorphic and tectonic processes during deformation of the sedimentary and volcanic rock; many of the veins do not have roots and are met- amorphic quartz segregations. Quartz veins in or adja- cent to igneous rocks, on the other hand, may contain macroscopic sulfide minerals and most exhibit an addi- tion of some minor elements. Semiquantitative spectrographic analyses of the sulfide—bearing quartz veins reveal moderately high Cu from the eastern Werner Mountains (specimen R0256c), southern Playfair Mountains (Ke7g), and the western RARE Range (S54c). High to moderate values of Cu and Zn occur in unnamed mountains of the southern Black Coast (Ka316—4), Werner Mountains (R0251b), Ferguson Nunataks (V32c), and chal- copyrite-bearing rock from the northern Latady Moun- tains (S6). Pyrite-bearing rock (Wa9a) from the east- ern Werner Mountains and rock (Ro54a) from the east- ern Guettard Range show anomalous As and moderate Cu. High Mo and moderate Cu characterize pyrite- bearing rock in the southern Black Coast (R0315h), and high Mo and W occur in chalcopyrite-molybdenite bearing rock from the western RARE Range (W139h). High Zn and Pb and moderate Cu values were deter- mined for altered and silicified rock in the western Werner Mountains (Bo44e). Sulfides also occur as pods or disseminated crystals in localized areas. A zone con- taining pyrite, chalcopyrite, malachite-chrysocolla(?), and azurite, and containing high values of Cu, Pb, Zn, Bi, and apparently Ag occurs in plutonic rock (Wa21) in the northern Dana Mountains. A possible malachite stain was noted at Mount Poster (B28d) west of the Latady Mountains. Several pyrite zones were found in plutonic rock (S53) in the northern Latady Mountains. Veins and disseminated crystals of pyrite in silicic por- phyry dikes occur at outcrops in the southern Black Coast (R0315d) and Scaife Mountains (W41d); malachite-chrysocolla(?) stains occur at the contact of a silicic porphyry dike cutting plutonic rocks in the northern Dana Mountains (Wa20). Molybdenite was observed in pegmatites in the eastern Hutton Moun- tains (R0168e) and Latady Mountains (834a). Malachite-chrysocolla(?), occasionally accompanied by chalcopyrite and quartz veins, commonly occurs in more mafic (mostly pyroxene and hornblende diorite or gabbro) plutonic contact phases in the southeastern Dana Mountains (R0303), Werner Mountains (Ke37g, Ke41de, Ke41fg, Ro24lb), Watson Peaks (V3le), Riv- era Peaks (Ke20gk), southwestern Playfair Mountains (F1, V3, V5), and Guettard Range (W113de); semiquantitative spectrographic analyses of samples for some of these outcrops reveal high to moderate val- ues of Cu, Zn, and for some rocks Pb. Hydrothermally altered igneous rock of argillic and phyllic facies was sampled in numerous areas in the Lassiter Coast and southern Black Coast. Such altered rock commonly occurs at igneous contacts, as in the southern Dana Mountains (R0225a), northern Hutton Mountains (R0198de), Guettard Range (R012a, R013abc), RARE Range (Ro75bc, R086a), and Latady Mountains (834d, 838k, W87c). Some silicic dike rocks are intensely hydrothermally altered, as in the south- eastern Werner Mountains (Wa17b1), northeastern Latady Mountains (P9b), and western Scaife Moun- tains (S71ca3). Poorly defined areas of hydrothermally altered rock within plutons were observed in the southern Black Coast (Bo71b), southwestern Dana Mountains (R0228b), southern Hutton Mountains (Rol50b, W1502e), and Latady Mountains (S31a). In some places the altered rock follows narrow linear zones as much as several meters in width that cut plutonic rocks. These are similar in appearance and petrology to the sheared phyllic-argillic zones of the copper deposit; this similarity and their linearity indi- cate that they also were the sites of fracturing and perhaps of shearing. Such sheared phyllic-argillic zones were mapped in the southern Black Coast (B068c, Ro313a, Ro313b, Wa37b), Rivera Peaks (R0215c), northern Playfair Mountains (V16b), and northwestern RARE Range (R0113b, R0199bc, R0199g, W144b). Ore minerals occur adjacent to the zones at two of these locations; semiquantitative spectrographic analyses prove that samples containing pyrite (B068b) and pyrite and malachite-chrysocolla(?) (W144c) have been enriched in Cu and Zn. REFERENCES CITED 35 CONCLUSIONS The Lassiter Coast copper deposit evolved during a complex series of igneous and structural events. The Late Cretaceous history in the immediate vicinity of the deposit consists of two essentially identical broad episodes, both of which were initiated by batholith in- trusion of granodiorite and by stock intrusion of quartz monzonite (Copper Nunataks pluton) into a terrane of tightly folded Upper Jurassic eugeosynclinal sedimen- tary and volcanic rocks. Each of these plutonic events was followed by intrusion of hypabyssal, mostly por- phyritic, more mafic dikes, and each broad episode was terminated by shear—fracturing, hydrothermal al- teration, and weak mineralization. The major copper mineralization occurred during the younger quartz monzonite episode. At this time phyllic and argillic altered rock was formed along linear sheared zones between which is a broad propylitic zone. Mineralized rock occurs over a broad area and is not confined to the sheared phyllic-argillic zones; however, it is most in— tensely developed in the wallrock where the zones are most abundant. The Lassiter Coast copper deposit bears many sim— ilarities t0 the typical porphyry copper deposit de- scribed by Lowell and Guilbert (1970). The associated and slightly older porphyry dikes are similar in petrology, chemistry, and age to those that preceded mineralization in the typical porphyry deposits of the circum—Pacific province. The alteration and minerali— zation assemblages also have many similarities in pe- trology and chemistry. Probably the chief departures of the Lassiter Coast deposit from the typical commercial porphyry deposit are the coarseness and relatively low grade of the mineralized rock and the linear pattern of altered and mineralized rock instead of the typical con- centric zones of altered and mineralized rock. Using the porphyry model (Lowell and Guilbert, 1970; Sillitoe, 1973) we can speculate on the location of a possible zone of higher grade. The coarseness of the quartz veins and disseminated sulfides, the presence of magnetite, and the lack of a significant potassic altera- tion zone suggest a site marginal to a higher grade deposit. Reconnaissance geologic mapping of numerous plutons elsewhere in the Lassiter Coast area suggests that it is unlikely that the roofs of the plutons in the area of the copper deposit were more than 1,000 m above the present peaks of the nunataks. This may suggest that erosion has not removed any significant ore deposit. Richer deposits may lie below the present erosion surface at the Copper Nunataks site or they may occur adjacent to the copper deposit described. The Lassiter Coast is part of the circum-Pacific igneous-tectonic province, which contains most of the world’s economic porphyry deposits. The existence of the Lassiter Coast copper deposit and the numerous other occurrences of similar metallized and hy- drothermally altered rock nearby prove that the southern Antarctic Peninsula locally contains anomal- ous copper concentrations. And from what can be de- termined by a review of the literature of other types of mineralized rock farther north (Rowley and others, 1975), we conclude that the Antarctic Peninsula is a copper province and that at least locally there are affinities with the porphyry type of copper deposit in this province. A tie between the copper provinces of Antarctica and South America has been proposed by Sillitoe (1972, p. 193); this proposal is not surprising in light of the geologic similarities already mentioned. The discovery of the Lassiter Coast copper deposit pro— vides the first geologic data for completing the south— ern extension of the circum-Pacific copper province. 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D., 1971, Geologic studies of the Las- siter Coast: Antarctic Jour. U.S., v. 6, no. 4, p. 120. 1972, Composition of Jurassic sandstones, Lassiter Coast: Antarctic Jour, U.S., V. 7, no. 5, p. 145—146. Williams, P. L., Schmidt, D. L., Plummer, C. C., and Brown, L. E., 1972, Geology of the Lassiter Coast area, Antarctic Peninsula—preliminary report, in Adie, R. J., ed., Antarctic geology and geophysics, Symposium on Antarctic geology and solid earth geophysics, Oslo, August 6—15, 1970: Internat. Union Geol. Sci., ser. B, no. 1, p. 143—148. 9 9 521576 ”’0 7 DAYS qu’s Biostratigraphy and Regional Relations of the Mississippian Leadville Limestone in the San Juan Mountains, Southwestern Colorado GEOLOGICAL SURVEY PROFESSIONAL PAPER 985 uocumams ‘fi’éfimfitfi JAN 1918/1 LIBRARY “KNERSITY 0F (‘ALIFORHM Biostratigraphy and Regional Relations of the Mississippian Leadville Limestone in the San Juan Mountains, Southwestern Colorado By AUGUSTUS K. ARMSTRONG and BERNARD L. MAMET GEOLOGICAL SURVEY PROFESSIONAL PAPER 985 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1976 UNITED STATES DEPARTMENT OF THE INTERIOR THOMAS S. KLEPPE, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Armstrong, Augustus K. Biostratigraphy and regional relations of the Mississippian Leadville limestone in the San Juan Mountains, southwestern Colorado. (Geological Survey Professional Paper 985) Bibliography: p. 24~2 5. Supt. of Docs. no. I 19.161985 1. Geology, Stratigraphic~Mississippian. 2. Geology—Colorado—San Juan Mountains. 1. Mamet, Bernard L.,joint author. II. Title: Biostratigraphy and regional relations of the Mississippian Leadville limestone... II. Series: United States Geological Survey Professional Paper 985. QE672.A68 551.7’51'0978838 76—608257 For sale by the Superintendent of Documents, US. Government Printing Office Washington, DC. 20402 Stock Number 024—001—02910—3 CONTENTS Page Page Abstract __________________________________________________ 1 Tuberendothyra Skipp in McKee and Gutschick 1969 —Con. Introduction —————————————————————————————————————————————— 1 Genus Spinoendothyra Lipina 1963 emended ____________ 12 Previous studies —————————————————————————————————————————— 1 Contact between Devonian and Mississippian rocks __________ 13 Stratigraphic sections —————————————————————————————————————— 3 Contact between Mississippian and Pennsylvanian rocks I... 14 ROCkWOOd Quarry sections 65A-12A, 660-4 —————————————— 3 Correlation of the Leadville Limestone in the San Juan Moun- Coalbank Hill section 660—1 ____________________________ 6 tains ____________________________________________________ 14 Molas Creek section 660—2 and Molas Lake section Regional correlations and paleogeography __________________ 15 660—213 ———————————————————————————————————————————— 6 Redwall Limestone, Grand Canyon, Arizona ____________ 15 Ouray section 660—5 —————————————————————————————————— 8 Arroyo Penasco Group, north-central New Mexico ________ 15 Vallecito 59013011 660-3 ———————————————————————————————— 9 Kelly Limestone of the Ladron Mountains, west-central New Piedra River section 65A—10 ____________________________ 9 Mexico ______________________________________________ 17 Kerber Creek 660—6 and 660—6B ______________________ 10 Caloso Member ________________________________________ 18 Microfossils of the Leadville Limestones ____________________ 11 Ladron Member ________________________________________ 18 Tuberendothyra Skipp in McKee and Gutschick 1969 and Taxo- Microfossfls ____________________________________________ 19 nomic emendation of Spinoendothyra Lipina 1963, by Late Osagean marine transgression _________________________ 19 Bernard L- Mamet ———————————————————————————————————— 12 Location of stratigraphic sections and fossil localities ________ 21 Genus Tuberendothyra Skipp in McKee and Gutschick 1969 References cited __________________________________________ 24 emended ____________________________________________ 12 ILLUSTRATIONS [Plates 1 and 2 follow references. Plate 3 is in pocket] PLATE 1. Photomicrographs of Leadville Limestone and microfossils. 2. Photomicrographs of Leadville Limestone and microfossils. 3. Location of stratigraphic sections and biostratigraphic correlation chart of Leadville Limestone, SanJuan Mountains, southwestern Colorado. Page FIGURE 1. Index map showing location of major Mississippian rock outcrops, San Juan Mountains _______________________________ 2 2. Photograph of outcrop of Mississippian Leadville Limestone north of Rockwood Quarry, southwestern Colorado ________ 4 3. Photograph showing outcrop of Leadville Limestone, just north of Rockwood Quarry _________________________________ 4 4. Photograph showing red shale and limestone band at base of Leadville Limestone ___________________________________ 4 5. Photograph of outcrop of Leadville Limestone in Molas Creek section (660-2) _________________________________________ 6 6. Photograph of top of Leadville Limestone at Molas Creek section (660—2) _____________________________________________ 6 7. Photograph of solution-rounded boulder of Leadville Limestone at Molas Lake section (66C—2B) _______________________ 7 8. Photograph showing angular unconformity in Box Canyon near Ouray, Colo _________________________________________ 8 9. Stratigraphic column of Mississippian Arroyo Penasco Group at Tererro, N. Mex _____________________________________ 16 10. Stratigraphic column of Mississippian Caloso and Ladron Members of the Kelly Limestone, Ladron Mountains, west- central New Mexico _________________________________________________________________________________________ 18 11 Regional correlation diagram of Leadville Limestone of San Juan Mountains, 0010., and Mississippian rocks in adjacent areas _______________________________________________________________________________________________________ 20 12. Biostratigraphic correlation and facies relation diagram of Mississippian rocks from the San Juan Mountains, south- western Colorado, to the Ladron Mountains of west-central New Mexico _________________________________________ 22 13.‘ Idealized Late Devonian paleogeologic map of southern Colorado and northern New Mexico ___________________________ 23 14. Paleogeographic map of northern New Mexico, southern Colorado, and Four Corners area at the end of Osagean, Mississippian time ___________________________________________________________________________________________ 23 15. Idealized pre-Pennsylvanian sedimentation paleogeologic map of southern Colorado and northern New Mexico __________ 24 III BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE IN THE SAN JUAN MOUNTAINS, SOUTHWESTERN COLORADO By AUGUSTUS K. ARMSTRONG and BERNARD L. MAMET ABSTRACT In the San Juan Mountains, southwestern Colorado and adjacent areas, the Leadville Limestone, of Mississippian age, disconformably overlies the Ouray Limestone of Late Devonian (Famennian) age. Generally the Leadville Limestone can be divided into two parts. The lower part, 2—50 m thick, is unfossiliferous dolomite and lime mud- stone of uncertain age that were deposited in a subtidal to supratidal environment. Overlying these is 2—26 m of pellet-echinoderm-ooid- foraminifer packstone-wackestone that contains a microfossil as- semblage of zone 9, which is Osagean, late Tournaisian age. This fossiliferous limestone was deposited in open, shallow marine water. A regional unconformity and pre-Pennsylvanian erosion surface at the top of the Leadville Limestone represent a stratigraphic hiatus encompassing Meramecian, Chesterian, and probably part of early Morrowan time. The lowest beds of the overlying Pennsylvanian Molas Formation were deposited on the Leadville Limestone as a residuum composed of nonmarine mudstone, solution-rounded lime- stone, and chert. A major marine transgression occurred in zone 9, late Osage time, in northern Arizona, southern Colorado, New Mexico, and southern Utah. The crinoid-foraminifer limestone of the Leadville Limestone of the San Juan Mountains is part of a once extensive carbonate cover. Open-marine carbonate rocks that are time-stratigraphic equivalents of the Leadville include to the west the Mooney Falls Member of the Redwall Limestone of the Grand Canyon, Ariz., and to the south the Ladron Member of the Kelly Limestone of west-central New Mexico. The Espiritu Santo Formation, to the southeast in north-central New Mexico, is a subtidal-supratidal facies of zone 9 of the Leadville Limestone. INTRODUCTION The field studies (fig. 1) for this report were done in 1965 and 1966 in southern Colorado. The sections in the Nacimiento Mountains and north-central New Mexico were sampled in 1965, 1966, 1972, and 1973. The Mississippian outcrops of west-central New Mexi- co were sampled in 1956, 1970, and 1973. The stratigraphic sections were measured with a Jacobs staff and tape. Lithologic samples were col- lected at 1- to 3-m intervals. The lithologic samples were made into thin sections for petrographic and mi- crofossil study. The primary objectives of this study were to date the Leadville Limestone in the San Juan Mountains and the hiatus that separates the Mississippian rocks from the Devonian Ouray Limestone. The regional strati- graphic relations of the Leadville Limestone of the San Juan Mountains to other Mississippian rocks of the region are shown by correlation charts and regional paleogeographic maps. Durham’s (1962) carbonate rock classification is used in this report. We wish to express our appreciation to Dr. Frank Kottlowski, Director of the New Mexico Bureau of Mines and Mineral Resources, who suggested this study in 1964 and who supported the field studies in New Mexico in 1965. We acknowledge with pleasure the help and encouragement given us in this study by US. Geological Survey geologists J. Thomas Dutro, J r., and William J. Sando. We are indebted to Dutro for the identification of the Devonian brachiopods and to John W. Huddle for the conodont data. PREVIOUS STUDIES The Leadville Limestone was named by Eldridge (Emmons and Eldridge, 1894) for outcrops in the Lead- ville mining district of Lake County, Colorado. Spencer (1900) designated the type locality of the Ouray Limestone, at the junction of Canyon Creek with the Uncompahgre River just south of Ouray, in the San Juan Mountains, Colo. The name was origi- nally applied to beds in which only Devonian fossils were then known. Girty (1903) found that the megafos- Sils from the upper part of the Ouray Limestone of the San Juan Mountains were of Early Mississippian age and were similar to faunas from the type Leadville Limestone at Leadville and to the Madison Limestone of Yellowstone National Park. 2 BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE 112° 111° 110° 109° 108° 107° 106° 105° f «I I E II LII—VI I I x _ I11 J I K . I— _ _ — _ 38° _ / Lisbon I t E 1 _ oil field K ’ \ " / ,. I-__m a . ~ Y“ 1——« / 1,9 I 3/ 4/V ( L _ 1__ ._ -—I / «:7 F__ 42:04 I | V ~ — ‘ _ ‘ " "’ ‘9/4’ + rdiscifzrgnagan I 4’ | ’ Alamos/a .2 2 1:1 “)5; Juan Mountains! /\ I—-‘I____.I.I—— _ ,/_/ I // VI Rockwood \ l I I/ I Quarry \ l . i ~ / I . \ 37 —————— __ __ __UTAH__ __ LIQQLORAQQ _ 5 _ __ __1J———-— I I ARIZONA I NEW MEXICO \ ‘ I f H 'I I / (I I Mississippian I/ // T\\ I I | I g outcrop in | SAN JUAN I 0 Grand Canyon fl/ \I l I BASIN I t; I: S‘— __.l // I I I I I— — —II San 0 36.. _ / BLACK MESAI \ I _ _ _ I _ II P171? 5’ — I\ I BASIN I /) I I I // g I" Te/\rerro / “I III _ I i I " u Mississippian \\ I ,/ II _/ ————\ / 59% E D outcrop in /' |\ '/ \ Arroyo m | Sangre de \ I \ / Penasco Z I FE Cristo i \v v/ /I I I I Mountains _ _ _ J—I_ _ a, '\ I I I \ _ ——‘_ v: I — . I o“ §:I I 35., : _ l I I I mos ALBUQUERQUE a; s _ I _ _ _I_ Hoibrookn i I— — — l‘1 -I — _ " ‘71—; | c | I I e 2 I ' 'UE IJ __ I; I ‘ P—‘—“—‘ Kgrfi‘ \ . I I I I I Limestone \I __I Q _ L; I ' I l .5 «n “ —‘ " J- ' o ( I I I Iv E2 34 — K g _, DSocon‘o a: | __ In "’ l ) “I I I I 3% [.1 ,_ In 1 \ I I r —'.i I 2 . I I I 0 50 100 150 MILES IL 1 I | I I I I | I I I I I O 50 100 150 200 KILOMETFIES EXPLANATION G) Major Mississippian outcrop discussed in this report FIGURE 1.—L0cation of major Mississippian rock outcrops and localities discussed in this report. Kindle (1909) described the Upper Devonian fauna Mississippian rocks and restricted the Ouray Lime- from the Ouray Limestone and recognized a Mississip- stone to Devonian rocks of the San Juan Mountains. pian fauna in the upper part of the formation Kirk Armstrong (1955,1958b) considered the Leadville (1931) restricted the Ouray Limestone to the lower Limestone at Piedra River and Rockwood Quarry in part of what had previously been called Ouray to that the San Juan Mountains to be Kinderhookian on the part that is Upper Devonian and assigned the Missis- basis of microfossil evidence. sippian part of the original Ouray Limestone to the Knight and Baars (1957) accepted Stainbrook’s Leadville Limestone. Bass (1944), Wood, Kelley, and (1947) conclusion that the fauna of the Percha Shale of MacAlpin (1948), and Steven, Schmitt, Sheridan, and southern New Mexico was Early Mississippian and Williams (1969) used the term Leadville Limestone for similar to the Ouray Limestone fauna, which they con- STRATIGRAPHIC SECTIONS 3 sidered also to be Early Mississippian. They therefore concluded, because the Ouray fauna was both Devo- nian and Mississippian and the contact between the Ouray and Leadville Limestones showed gradational aspects, that the Ouray Limestone was transitional both stratigraphically and faunally with the overlying Leadville Limestone. However, they did note that the Ouray fauna is distinct from the Leadville fauna. With the Leadville Limestone of Kinderhookian and Osa- gean age directly overlying the Ouray Limestone, the time available for the development of any major uncon- formity at the top of the Ouray was limited. Knight and Baars (1957, p. 2280) recognized two new members in the Leadville Limestone—the Beta Member for its lower dolomitic facies and the Alpha Member for its upper limestone facies—from the subsurface of the Paradox basin of Utah to the outcrops in the San Juan Mountains. Knight and Baars (1957) gave a detailed account of the regional aspect of the Leadville Limestone and considered it Kinderhookian. Parker (1961) considered the Leadville Limestone of southwestern Colorado to be Kinderhookian and early Osagean. Merrill and Winar (1958) show the Leadville Limestone of the San Juan Mountains as Osagean and early Meramecian. Parker and Roberts (1963) published a detailed study of the Leadville Limestone of the San Juan Mountains and in the subsurface of the Paradox, Black Mesa, and San Juan basins of the Four Corners region. They suggested that the subdivision of the Leadville Limestone in the San Juan Mountains, based on changes from dolomite, below, to limestone, above (the Beta and Alpha Members of Knight and Baars, 1957), be abandoned. Their subsurface studies indicated very complex patterns of dolomitization that affected the Mississippian limestone of the region, and these pat- terns were not related to specific horizons over broad geographic regions. In a series of papers Baars (1965, 1966) and Baars and See (1968) developed the concept of pre-Pennsyl- vanian positive areas in the Paradox basin of Utah and the San Juan Mountains of southwestern Colorado. Baars and See (1968, p. 333) suggested the following sequence of events (pl. 3). The Grenadier highlands, a northwest-trending graben-faulted anticline involving all pre-Pennsylvanian rocks is exposed in the core of the San Juan Mountains near Silverton, Colo. The feature was formed before Late Cambrian time when younger Precambrian quartzites were extensively downfaulted into juxtaposition with the older Precambrian basement complex. The quartzites emerged to- pographically high and supplied local talus to Ignacio deposits (Late Cambrian) adjacent to the faults. Ignacio rocks do not cover the fault block, but thicken and become finer grained away from the feature. As the Late Devonian seas advanced, the McCracken Sandstone Member of the Elbert Formation was deposited along the flanks of the structural feature, but apparently did not cross it. The upper Elbert intertidal dolomites were the first sediments to be deposited across the faulted fold where they lie directly on Precambrian quartzites. Latest Devonian or earliest Mississippian stromatolitic dolomites of the Ouray Formation overlie Elbert strata on the flanks of the old feature, and equivalent normal marine limestones are locally present within the downfaulted block. The Early Mississippian Leadville Formation thins abruptly onto the flanks of the graben-faulted anticline, where the lithologic aspect is one of stromatolitic dolomite formed in an intertidal zone. Within the graben, Leadville strata are thin or missing except as remnants in the overlying Molas regolith, suggesting that intense post- Leadville weathering removed those rocks across the regionally high structure. A small horst is present within the large graben where Pennsylvanian sedimentary rocks rest directly on upturned Precam- brian quartzites. The graben was again downfaulted at some unde- termined post-Desmoinesian time, for Middle Pennslyvanian beds are now in fault contact with Precambrian rocks along the flanking fauls. A similar ancient fault block south of Ouray, 0010., [the Sneffels horst] extends northwestward into the subsurface of the eastern Paradox basin. This feature parallels the nearby Uncompahgre up- lift and may be genetically related to it. STRATIGRAPHIC SECTIONS ROCKWOOD QUARRY SECTIONS 65A—12A AND 660—4 The excellent exposures at and adjacent to Rockwood Quarry in the southern San Juan Mountains are easily accessible (figs 2, 3). The carbonate rocks of both the Devonian Ouray Limestone and the Mississippian Leadville Limestone have not been extensively dolomitized here as is common elsewhere in the San Juan Mountains. Also the boundary between the Ouray and Leadville Limestones can be easily located by lithologic differences. It cannot be defined by paleontologic methods. The Leadville Limestone at Rockwood Quarry is 34.8 m thick (figs. 3, 4) and has a sharp lithologic con- tact with the underlying Ouray Limestone. The Ouray Limestone 5 m below the contact is massive, brown to gray dolomite composed of 50-p.m hypidiotopic dolo- mite rhombs. Above this is a 2-m-thick bed of crinoid- bryozoan-brachiopod packstone from which a brachiopod fauna was collected. The brachiopods were identified by J. Thomas Dutro, Jr. (written commun., 1973) (USGS 9206—SD): echinoderm debris, indet. Schizophoria australis Kindle Schuchertella coloradoensis Kindle Leioproductus coloradoensis (Kindle) Paurorhyncha endlichi (Meek) rhynchonellid, undet. Cyrtospirifer cf. C. whitneyi (Hall) Cyrtospirifer? animasensis (Girty) Cyrtospirifer sp. Syringospira prima (Kindle) reticulariid, indet. bellerophontid gastropod, indet. 4 BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE FIGURE 2.—Outcrop of Mississippian Leadville Limestone, north end of Rockwood Quarry, southwestern Colorado. View is to the west from US. Highway 550. Prominent notch at base of the Leadville Limestone is the contact with Devonian Ouray Limestone. The high trees on the center and left of the photograph are on the shaly and arenaceous carbonate beds of the Devonian Elbert Formation. Massive outcrop in the center of the photograph is the Upper Cam- brian Ignacio Quartzite. Rubble slope covers the Precambrian— Cambrian contact. Dutro stated, “This is the fauna described from the Rockwood quarry by Kindle (1909), it is of probable mid-Famennian age.” Above the brachiopod beds com- posed of echinoderm-brachiopod packstone is a 0.6-m- thick lime mudstone overlain by a 1.7-m-thick bed (figs. 3, 4) of breccialike material composed of silt- to boulder—size lime mudstone and wackestone. The ma- trix between the clasts is filled by calcite, argillaceous calcite, reddish-brown-gray iron-rich shale, and shale clasts. This unit has a very irregular contact with the underlying beds and a regular contact with the overly- ing beds. The thickness of this breccia varies, and 1—2 km north of Rockwood Quarry it is represented by FIGURE 3.—Leadville Limestone just north of Rockwood Quarry. Red shale and limestone band in lower part of Leadville Limestone is just above the breccia zone. ' W was. _ ‘ 2.5‘mtoa.o m Thin-bedded lime mudstone Lime mudstone l .7 m 'eddigh-brown calcareous shale ' Limcsmnem‘eccié Space between clasts filled wlth calcite, argillaceous calcite. red (0 .brown Iron-rich shale. Contact with Devonian brachxopowbearing beds very irveguiar. FIGURE 4.—Limestone breccia and red shale and limestone band at base of Leadville Limestone. what appears to be an interformational conglomerate 0.5—1 m thick. At about 3.5—4 m above the base of the Leadville Limestone is a 0.5- to 0.7-m-thick fine- grained brownish—gray dolomite with laminations 20 mm to 2 cm thick; subrounded intraformational clasts are a few millimetres to 3 cm in size. Birdseye struc- tures and low—relief stromatolites are common, with some bioturbation. These features clearly indicate deposition in an intertidal-supratidal environment. From about 4.2 to 20 m above the base, the Leadville Limestone contains lime mudstone and pellet packstone with minor interbeds of dolomite composed of hypidiotopic, 10- to 30-Mm dolomite rhombs. From 20 to 33 m, the unit is composed of crossbedded massive, ooid-f0raminifer-echinoderm-brachiopod packstone and grainstone. From 33 to 35.3 m crinoid wackestone predominates. The top of the Leadville Limestone is an erosion surface marked by extensive solution activity, terra rossa clay, and large rounded cobbles and boul- ders of limestone and chert in the basal beds of the Molas Formation. STRATIGRAPHIC SECTIONS 5 MICROFOSSILS, ALGAE, AND FORAMINIFERS Sample number 65A—12A + 18; 3 In below the top of the Ouray Limestone. USGS loc. M1180. Kamaena Sp. Kamaena itkillikensis Mamet and Rudloff Age: Late Devonian or Mississippian. Sample number 66C—4 + 130; 1 m above base of Lead- ville Limestone. USGS loc. M1181. Calcisphaera laevis Williamson Parathurammina sp. Vicinesphaera Sp. Age: Late Devonian or Mississippian. Sample number 65A—12A + 41; 4.6 m above base of the Leadville Limestone. USGS loc. M1182. Calcisphaera Sp. Kamaena Sp. Parathurammina Sp. Proninella sp. Vicinesphaera sp. Age: Late Devonian 0r Mississippian. Sample number 65A—12A + 95; 21 m above base. USGS loc. M1183. Calcisphaera laevis Williamson “Globoendothyra” trachida (Zeller) I nflatoendothyra sp. Kamaena sp. Latiendothyra sp. Latiendothyra of the group L. parakosvensis (Lipina). Medioendothyra sp. “Nostocites” sp. Palaeoberesella sp. Septabrunsiina sp. Septabrunsiina parakvainica Skipp, Holcomb, and Gutschick Septaglomospiranella sp. Septatournayella Sp. Septatournayella aff. S. pseudocamerata (Lipina in Lebedeva) Spinoendothyra paracostifera (Lipina) Spinoendothyra spinosa (Chernysheva) Spinoendothyra tenuiseptata (Lipina) Tournayella sp. Vicinesphaera sp. Age: Zone 9, late Tournaisian. Sample number 65A—12A + 105; 24.1 m above base. USGS loc. M1184. Kamaena sp. Proninella sp. Septabrunsiina sp. Septaglomospiranella sp. Spinoendothyra Sp. Tournayella Sp. Age: Zone 9, Late Tournaisian. Sample number 65A—12A + 115; 27 m above base. USGS loc. M1185. Calcisphaera Sp. Earlandia Sp. Kamaena sp. Latiendothyra sp. Palaeoberesella sp. Septabrunsiina sp. Septaglomospiranella sp. Septatournayella sp. Spinoendothyra Sp. Spinotournayella Sp. Vicinesphaera Sp. Age: Zone 9, late Tournaisian. Sample number 65A—12A + 125; 30.2 m above base. USGS loc. M1186. Calcisphaera Sp. Earlandia Sp. Kamaena sp. Latiendothyra sp. Septabrunsiina sp. Septatournayella sp. Spinoendothyra Sp. Tournayella Sp. Age: Zone 9, late Tournaisian. CONODONTS Samples were collected from the lower part of the Leadville LimestOne at Rockwood Quarry in 1973 for conodonts. The samples were sent to John W. Huddle who reported that the samples from 9.8, 10, 11.6, 12.8, 13.7, and 17.1 m above the base of Leadville Limestone did not contain conodonts (written commun., 1974). Two samples contained conodonts. 73C—12A+50; about 7.5 m above the base of the Lead- ville Limestone. (USGS 25447—PC). Number of speczmens F alcodus Sp. 1 H indeodella sp. 2 73C—12A+36; about 2 m above base of Leadville Lime- stone. Limestone cobbles in red shale. (USGS 25448— PC) Number of speczmens Apathognathus? sp. 1 Hindeodella sp. 1 H. sp. 1 Neoprioniodus sp. 1 bar fragments All of the species reported are bar-type conodonts and not very useful in correlation. All the genera occur in the Devonian and Mis- sissippian. I examined a collection that I made in 1969 with Poole, Sandberg, land Uyeno from the top of the bed you place at the top of the Ouray Limestone. Neither Sandberg nor I are ready to commit ourselves on the age of the bed but we think it is Late Devonian, probably Polyg- nathus styriacus Zone or somewhat younger. There are some new species and perhaps a new genus in the fauna. It has not been de- scribed. 6 BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE COALBANK HILL SECTION 66C—1 The Coalbank Hill section 66C—1 is the same as Baars’ (1966, 1968) Mill Creek Lodge section and Mer- rill and Winar’s (1958) Coalbank Hill section. The out- crop is well exposed in a roadcut 2.1 km north of the Mill Creek Lodge on US. Highway 550 (pl. 3). The contact between the Ouray and Leadville Lime- stones was picked at the top of the gray to tan-gray dolomite composed of 0.5— to 1-mm dolomite rhombs, with thin 0.5-cm yellowish-green shale partings. The upper 1.5 m of this dolomite has vugs as much as 2 cm in diameter that are filled with gray to light-green shale. The overlying dolomite, arbitrarily assigned by ‘ lithology to the Leadville Limestone, is pale yellowish orange to olive gray having weakly developed lamina- tion and intraformation clasts. The dolomite is com- posed of 30- to IOO-Mm rhombs. The dolomite from 0 to 8.2 above the base contains no recognizable mega- or microfossils. The rocks from 0 to 8.2 m we consider, provisionally on the basis of lithologic characteristics, to be basal Leadville Limestone. Merrill and Winar (1958), on the basis of insoluble residue, considered this dolomite to be the Ouray Formation. The rocks between 8.2 and 20.4 m have been strongly affected by solution activity, have chaotic bedding and collapse structure, and are filled by a reddish-brown matrix of shale and silt. The limestone is gradational at its base with nearly solid limestone that is only slightly af- fected by solution activity. The limestone in this unit is primarily crinoid packstone with microfossils of zone 9, Osagean age. The crinoid limestone of this unit was included by Merrill and Winar (1958) in their Coalbank Hill Member of the Molas Formation. As these rocks repre- sent a post-Leadville vadose-weathering zone, it may be correct to consider them as the basal member of the Molas Formation, but for purposes of regional correla- tion and rock type distribution, we consider them to be a highly altered part of the Leadville Limestone. MICRO FOSSILS Sample number 660—1 + 165; 15.8 m above the base of the Leadville Limestone. USGS loc. M1187. Earlandia sp. Kamaena sp. Septaglomospiranella dainae Lipina Age: Zone 9, late Tournaisian. Sample number 660—1 + 175; 18.9 m above the base. USGS loc. M1188. Kamaena sp. MOLAS CREEK SECTION BBC—2 AND MOLAS LAKE SECTION 66C—2B The Molas Creek and the Molas Lake sections were measured about 1 km apart. The Molas Creek section was measured along Molas Creek (pl. 3, figs. 5, 6) which drains Molas Lake, 0.5 km south of Molas Lake. This section exposes rocks from the Cambrian Ignacio Quartzite to the Molas Formation. The Molas Lake section was measured along the roadcut on the north shore of Molas Lake (fig. 7) where the upper crinoidal facies of the Leadville Limestone and the contact with the overlying Molas Formation are well exposed. The contact between the Ouray Limestone and the Leadville Limestone was picked at the top of a massive FIGURE 5.—Leadville Limestone at the Molas Creek section (660—2). The steep cliffs are formed by dolomite. FIGURE 6.—Top of the Leadville Limestone at the Molas Creek sec- tion (660—2). The Leadville here has been strongly affected by pre-Pennsylvanian vadose weathering and is now rounded lime- stone boulders and terra rossa soil. STRATIGRAPHIC SECTIONS 7 FIGURE 7.——Large solution—rounded boulder of Leadville Limestone showing cavities with terra rossa clay. Top of Leadville Limestone Molas Lake section 66C—2B. 2.8-m-thick light-gray chert bed. The Ouray Limestone below the chert bed is massive, yellowish-gray to light-olive-gray dolomite composed of 80-um rhombs. The Leadville Limestone, above the chert bed, is yellowish-gray, massive, laminated dolomite with chert pseudomorphs of gypsum at 10.7 m above the base (pl. 1, fig. 1). The uniform dolomite from 0 to 20 m above the base is composed of hypidiotopic dolomite rhombs in the 40— to 100-;um size. The fine-grained dolomite, lamination, and chert pseudomorphs all suggest that the rocks in the interval between 0 and 20 m were deposited in an intertidal to supratidal environment. The contact between Leadville dolomite and under- lying Ouray dolomite is difficult to pick because of the lack of fossils in either formation and the similar types of dolomite in both. Baars (1965, p. 134) did not pick a boundary and lumped the strata into a Leadville- Ouray Formation at this outcrop. Resting directly on the massive Leadville dolomite (fig. 5) is 3 m of foraminifer-algal-pellet packstone of zone 9, Osagean age. A covered interval exists between 20.6 and 27.5 m where a large remnant of the upper Leadville Limestone is found within the Molas Forma- tion regolith. This remnant is bryozoan—crinoid-coral- brachiopod packstone that has been subjected to exten- sive vadose weathering (fig. 6). The Molas Lake section contains an excellent expo- sure of the crinoidal facies of the Leadville Limestone and the Molas Formation. The base of the section is at water level at the edge of the lake. The Leadville Limestone from 0 to 6 m above the base is lump to pellet-brachiopod—foraminifer packstone and grain— stone. The section is covered from 6 to 13 m and is a crinoid packstone-wackestone from 13 to 26 m. The highest 10 m has been strongly affected by post-Lead- ville vadose weathering and solution activity (fig. 7). MICROFOSSILS Sample number 660—2 + 176; 21.6 m above the base of the Leadville Limestone. USGS loc. M1189. Calcisphaera laevis Williamson I nflatoendothyra sp. Kamaena sp. Latiendothyra sp. Latiendothyra of the group L. parakosvensis (Lipina) “Nostocites” sp. Parathurammina sp. Proninella sp. Radiosphaera sp. Septabrunsiina sp. Septabrunsiina parakrainica Skipp, Holcomb, and Gutschick Septaglomospiranella dainae Lipina Spinoendothyra sp. Spinoendothyra spinosa (Chernysheva) Tournayella sp. Vicinesphaera sp. Age: Zone 9, late Tournaisian. Sample number 66C—2B + 0; 0.0 In above base of sec- tion. USGS loc. M1190. Spinoendothyra sp. Spinoendothyra spinosa (Chernysheva) Age: Zone 9, late Tournaisian. Sample number 66C—2B + 5; 1.5 m above base of sec- tion. USGS loc. M1191. Calcisphaera sp. Calcisphaera laevis Williamson Kamaena sp. “Globoendothyra” trachida (Zeller) Palaeoberesella Sp. Proninella sp. Septabrunsiina sp. Septabrunsiina parakrainica Skipp, Holcomb, and Gutschick Septaglomospiranella sp. Spinoendothyra sp. Spinoendothrya spinosa (Chernysheva) Spinotournayella sp. Spinotournayella tumula (Zeller) Age: Zone 9, late Tournaisian. Sample number 66C—2B + 20; 6.1 m above base of section. USGS loc. M1192. Calcisphaera sp. Kamaena sp. Parathurammina sp. 8 BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE Proninella sp. Vicinesphaera sp. Age: Zone 9, late Tournaisian. OURAY SECTION 66C—5 The Elbert Formation, Ouray Limestone, and Lead- ville Limestone are magnificently exposed west of the town of Ouray (pl. 3; fig. 8). The Precambrian Uncompahgre Formation is over- lain with an angular unconformity by the Elbert Formation, 11.5 m thick, above which is the Ouray Formation, 14.6 m thick. The Ouray is a pale-olive- gray calcareous dolomite composed of 30- to 50-,u.m dolomite rhombs that have been calcified (dedolomi- tized) on their margins. Kindle (1909, p. 7) reported, from beds that are now recognized to embrace both the Ouray and Leadville Limestones as defined by Bass (1944) and Steven, Schmitt, Sheridan, and Williams (1969), that “Al- though no fossils were found by me in the lower part of the Ouray limestone at Ouray, its position and FIGURE 8.—Angular unconformity between nearly horizontal Elbert Formation and Precambrian Uncompahgre Formation in Box Canyon near Ouray, Colo. lithologic characteristics clearly show its identity with beds holding a Devonian fauna at localities both to the south and north.” Baars (1965, 1968) did not find any fossils in the type section of the Ouray Limestone. Our studies also failed to find any fossils in the beds we assigned to the Ouray Limestone. The boundary be- tween the Ouray and Leadville Limestones was chosen at the base of a 1.2-m-thick bed of 1- to 2-cm rounded to angular pebbles of dolomite in a dolomite matrix. The very fine grained dolomite is composed of 5-,um dolo- mite rhombs. The matrix contains some silt-size quartz grains. Some of the material may be broken and re- worked algal mats as indicated by the laminations. The dolomite-pebble conglomerate is overlain by al- most 1.5 m of fine-grained dolomite in 4- to 6-cm-thick beds with thin gray shale partings. A thick—bedded massive unit composed of 10- to 15-,u.m hypidiotopic dolomite occurs at 2.5 m above the base of the Leadville Limestone. Sedimentary struc- tures are weakly developed stromatolites, intraforma- tional lithoclasts, and lamination, which indicate dep— osition in an intertidal environment. At 5.8—7.6 m the dolomite is replaced by ostracode-pellet lime mudstone. A fine-grained gray dolomite is present from 7.6 to 13.7 m, and from 13.7 to 20.7 m is a lime- stone composed of neomorphic calcite crystals in the 10- to 30-um size. The unit was probably deposited as lime mud. A lime mud lump to pellet lime mudstone is present from 20.7 to 29.6 m. A massive-bedded gray crinoid-bryozoan-ooid-foraminifer packstone and wackestone is present from 29.6 to 38.4 m (pl. 2, figs. 1, 2, 3; pl. 1, fig. 6). Crinoid packstone and grainstone comprise the highest beds from 38.4 to 65.2 m. The contact of the Leadville Limestone with the overlying Molas Formation is sharp. The crinoid lime- stone shows little evidence of vadose weathering or so- lution activity. The basal beds of the Molas Formation are pale-brown to pale-gray chert pebble conglomerate, with clay and calcite cement, which grades upward into pale-brown poorly bedded shale. MIC ROFOSSILS Sample number 66C—5 + 115; 8.8 m above the base of the Leadville Limestone. USGS loc. M1193. Calcisphaera sp. Parathurammina sp. Vicinesphaera sp. Age: Late Devonian or Mississippian. Sample number 66C—5 + 185; 30.2 m above the base. USGS loc. M1194. Brunsia? sp. Calcisphaera laevis Williamson Earlandia sp. Earlandia of the group E. clavatula (Howchin) STRATIGRAPHIC SECTIONS 9 Earlandia of the group E. elegans (Rauzer-Cher- noussova and Reitlinger) Exvotarisella cf. E. index (Ehrenberg sensu von M'oller) Kamaena Sp. Kamaena maclareni Mamet and Rudloff Latiendothyra Sp. Latiendothyra of the group L. parakosvensis (Lipina). Palaeoberesella sp. Proninella Sp. Septabrunsiina Sp. Septabrunsiina parakrainica Skipp, Holcomb, and Gutschick Septaglomospiranella Sp. Septatournayella sp. Spinoendothyra Sp. Spinoendothyra spinosa (Chernysheva). Spinoendothyra tenuiseptata (Lipina) Spinotournayella Sp. Age: Zone 9, late Tournaisian. Sample number 66C—5 + 210; 37.8 m above the base. USGS 10c. M1195. Latiendothyra Sp. Septabrunsiina Sp. Septaglomospiranella sp. Spinoendothyra sp. Age: Zone 9, late Tournaisian. Sample number 66C—5 + 220; 40.8 m above the base. USGS loc. M1196. Exvotarisella index (Ehrenberg emend von Moller) Kamaena Sp. Pseudoissinella Sp. Age: Zone 9, late Tournaisian. Sample number 660—5 + 225; 42.4 m above the base. USGS loc. M1197. Calcisphaera laevis Williamson Kamaena Sp. Palaeoberesella Sp. Parathurammina Sp. Age: Zone 9, late Tournaisian. VALLECITO SECTION 66C—3 The Vallecito section (pl. 3) was measured about 0.3 km north of the Vallecito Campground. The Ignacio(?) Quartzite, Elbert Formation, and Ouray Limestone are together only 11 m thick. The Ouray Limestone is a pale-bluiSh—gray to light-gray argillaceous arenaceous dolomite composed of 20— to 40-p.m dolomite rhombs with some Silt—Size quartz grains. The top of the Ouray Limestone was picked at the occurrence of a 3- to 5—cm-thick calcareous brownish-red Shale. The overly- ing Leadville Limestone is a crinoid-brachiopod bryo- zoan packstone. A quartz sand crinoid packstone about 0.8 m thick occurs 19 m above the base. The section from 21 to 25.9 m iS a gray limestone composed of neomorphic calcite crystals in the 0.3- to 0.5-mm Size. The poorly exposed contact of the Leadville Limestone with the Molas Formation iS covered in part by soil and forest. The basal beds of the Molas Formation are peb- ble and cobble conglomerate and maroon shale and Siltstone. MICROFOSSILS Sample number 66C—3 + 100; 19.5 m above the base of the Leadville Limestone. USGS loc. M1198. cf. Atractyliopsis Sp. Calcisphaera laevis Williamson “Radiosphaera” Sp. Age: Probably zone 9, late Tournaisian. Sample number 66C—3 + 120; 25.6 m above the base. USGS loc. M1199. Calcisphaera laevis Williamson Kamaena Sp. Palaeoberesella sp. Proninella sp. Parathurammina Sp. Vicinesphaera Sp. Age: Zone 9, late Tournaisian. PIEDRA RIVER SECTION BSA—10 The Piedra River section is well exposed in the box canyon of the Piedra River near the junction with Davis Creek (pl. 3), San Juan Mountains, Colo. The Cambrian lgnacio(?) Quartzite and the Devonian El- bert Formation and Ouray Limestone is only about 12 m thick and rests with an angular unconformity on the Precambrian Uncompahgre Formation. The Ouray Limestone is 6 m thick and is fine-grained arenaceous brownish-gray dolomite. No micro- or megafossils were found in this unit. The contact between the Ouray and Leadville Limestones was picked at a Slightly undula— tory surface that is overlain by 3—5 cm of reddish- brown Shale; this shale is overlain by gray lime mudstone that contains reworked chips and pebbles of the reddish—brown Shale. The Leadville Limestone from 1 to 3.4 m above itS base is a fine-grained cherty microdolomite composed of 10- to 15-um dolomite rhombs. An ooid-foraminifer packstone to grainstone, from 3.5 to 6.2 m above the base, contains abundant Spinoendothyra spinosa. The section is from 10 to 12.5 m above the base lime mudstone and wackestone, and from 12.5 to 17.7 m it is pellet-algal—foraminifer packstone and grainstone. The section from 17.7 to 19.8 m above the base iS algal wackestone. The top of the Leadville Limestone is an irregular erosion surface marked by extensive solution cavities filled by terra rossa clay from the overlying Molas Formation. 10 BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE MICROFOSSILS Sample numbers 65A—10 + 54 to 74 ft; within the Leadville Limestone 3.5 to 6.2 m above its base. USGS loc. M1226. Brunsiina sp. Calcisphaera laevis Williamson Earlandia sp. Eotuberitina sp. I nflatoendothyra sp. Issinella sp. Kamaena sp. Kamaena maclareni Mamet and Rudloff Latiendothyra parakosvensis (Lipina) Medioendothyra sp. Parathurammina sp. "Polydermofl sp. Proninella Sp. Radiosphaera sp. Septabrunsiina sp. Septaglomospiranella sp. Septatournayella sp. . Septatournayella pseudocamerata Lipina in Lebedeva Spinoendothyra sp. Spinoendothyra spinosa (Chernysheva) Spinotournayella sp. Tournayella sp. Tournayella discoidea Dain Age: Zone 9, late Tournaisian. Sample numbers 65A—10 +85—104 ft; within the Lead- ville Limestone 12.5 to 18 In above its base. USGS loc. M1226. Brunsiina sp. Calcisphaera Zaevis Williamson Earlandia sp. Eotuberitina sp. I nflatoendothyra sp. Kamaena sp. Kamaena maclareni Mamet and Rudloff Latiendothyra sp. Parathurammina sp. Proninella sp. Septabrunsiina sp. Septaglomospiranella sp. Spinoendothyra sp. Spinoendothyra spinosa (Chernysheva) Spinotournayella sp. Tournayella sp. Age: Zone 9, late Tournaisian. KERBER CREEK SECTION 66C—6 AND 66C—6B The pre-Mississippian Paleozoic section (pl. 3) in the Kerber Creek section is dissimilar to those in the cen- tral parts of the San Juan Mountains. Burbank (1932, p. 12, 13) originally applied the name Leadville Lime- stone to these rocks solely on the basis of lithologic correlation and stratigraphic position as compared with other Devonian and Mississippian sections in Colorado. He admitted that, with the exception of one fish tooth, no fossils were found in the Leadville Lime- stone of the Kerber Creek section. Ordovician dolomite underlies the Devonian and Lower Mississippian(?) Chaffee Group. The lower 12 m of the Chaffee is gray, brown, and maroon clastic shale, sandstone, and siltstone of intertidal origin. Fish bones are abundant. These are overlain by 27.5 m of argil- laceous gray to olive-gray thin-bedded dolomite with abundant birdseye structure, lithoclasts, stromato- lites, and cut-and-fill structures. No fossils were found in this dolomite. The contact between the Chaffee Formation and the Leadville Limestone (pl. 3) was picked at an undula- tory surface on the argillaceous dolomite that is over- lain by dark-gray massive dolomite that contains large stromatolites and intraformational clasts. The basal 30 m of the Leadville Limestone is gray slightly argil- laceous dolomite. From 0 to 18 In above the base the dolomite rhombs are 5—10 Mm in size; from 18 to 26 In above the base the dolomite rhombs are 10—70 am in size; and from 26 to 30 In the dolomite is coarser grained with rhombs in the 0.1 to 0.5 mm size. The fine-grained microdolomite from O to 18 m preserves many of the original depositional structures and fabric. The rock was deposited as lime mud, and pelletoid structure is preserved in laminations that are abun- dant between 14 and 16 m above the base. Quartz sand admixtures are found at 5 In and from 18 to 20 In above the base. The environment of deposition for the lower 30 In of the Leadville Limestone is interpreted as sub- tidal to intertidal marine. The beds from 30 to 39.5 In above the base are siliceous-spiculitic-dolomite. The dolomite is composed of rhombs that range in size from 10 ,um to 1 In at different stratigraphic levels. The microdolomite has relic pelletoid structures, and the coarser dolomite has crinoid packstone relic structures. A massive-bedded chert occurs from 39.5 to 42.7 In above the base. Relic textures and fabric within the chert suggest that it is silicified lime mudstone. The interval between 42.7 and 53.3 In above the base is covered. The siliceous and dolomitic beds in the lower 53.3 m of the Leadville Limestone contain no known mega- or microfossils, and the assignment of these beds to the Leadville Limestone is based on lithologic simi- larity and stratigraphic position. The sedimentary structures and microdolomite suggest that most of the beds in this interval were deposited in subtidal to in- tertidal environments, and this may explain the lack of fossils. MICROFOSSILS OF THE LEADVILLE LIMESTONE 11 The Leadville Limestone from 53.3 to 65 m above the base is a sequence of lime mudstone, pellet packstone, and dolomite capped by 2 m of foraminifer-ooid packstone of zone 9, Osagean age. This unit is litholog- ically similar to the Leadville Limestone 153 km to the southwest at the box canyon of the Piedra River, San Juan Mountains. The ooid packstone is unconformably overlain by massive ferruginous coarse-grained to pebble quartz conglomerate of Pennsylvanian age. MICROFOSSILS Sample number 660—6B + 321; 58.2 m above the base of the Leadville Limestone. USGS 10c. M1200. Calcisphaera laevis Williamson Palaeocancellus sp. Parathurammina sp. Vicinesphaera sp. Age: Probably Mississippian. Sample number 66C—6B + 838; 63.4 m above the base. USGS 10c. M1201. Calcisphaera laevis Williamson Earlandia sp. Earlandia of the group E. elegans (Rauzer— Chernoussova and Reitlinger) Earlandia of the group E. moderata (Malakhova) primitive Eoforschia sp. cf. Garwoodia sp. I nflatoendothyra sp. Latiendothyra sp. “Nostocites” sp. Ortonella sp. Priscella sp. Septabrunsiina sp. Septabrunsiina parakrainica Skipp, Holcomb, and Gutschick Septaglomospiranella sp. Septatournayella sp. Spinoendothyra sp. Spinoendothyra spinosa (Chernysheva) Tournayella sp. Vicinesphaera sp. Age: Zone 9, late Tournaisian. MICROFOSSILS OF THE LEADVILLE LIMESTONE The following taxa of algae and foraminifers have been recognized in the Leadville Limestone of the San Juan Mountains. cf. Atractyliopsis sp. Brunsia sp. Calcisphaera sp. Calcisphaera laevis Williamson Earlandia sp. Earlandia of the group E. clavatula (Howchin) Earlandia of the group E. elegans (Rauzer- Chernoussova and Reitlinger) Earlandia of the group E. moderata (Malakhova) primitive Eoforschia sp. Exvotarisella index (Ehrenberg emend von Moller) Exvotarisella aff. E. index (Ehrenberg emend von Moller) Inflatoendothyra sp. Kamaena sp. Kamaena awirsi Mamet and Roux Kamaena maclareni Mamet and Rudloff cf. Garwoodia? sp. "Globoendothyra” trachida (Zeller) Latiendothyra sp. Latiendothyra of the groupL. parakosvensis (Lipina) “Nostocites” sp. Ortonella sp. Palaeoberesella sp. Palaeocancellus sp. Parathurammina sp. Priscella sp. Proninella sp. Pseudoissinella sp. “Radiosphaera” sp. (Radiosphaerina, etc.) Septabrunsiina sp. Septabrunsiina parakrainica Skipp, Holcomb, and Gutschick Septaglomospiranella sp. Septatournayella sp. Septatournayella aff. S. pseudocamerata (Lipina in Lebedeva) Spinoendothyra sp. Spinoendothyra paracostifera (Lipina in Grozdilova and Lebedeva) Spinoendothyra spinosa (Chernysheva) Spinoendothyra tenuiseptata (Lipina) Spinotournayella sp. Spinotournayella tumula (Zeller) Tournayella sp. Vicinesphaera sp. This microfauna closely resembles that reported by Skipp (in McKee and Gutschick, 1969) from the middle part of the Mooney Falls Member of the Redwall Lime- stone of northern Arizona and corresponds to her zone 4 (“Endothyra spinosa assemblage zone”). The only ap— parent discrepancy with the Redwall distribution is the presence of Tournayella in the Osagean Leadville Limestone. This is also true for most Tournaisian car- bonate rocks of the American Cordillera (see Sando and others, 1969). The microfossils are indicative of zone 9 in the Mamet classification (see Mamet and Skipp, 1970b). 12 TUBERENDOTHYRA SKIPP IN McKEE AND GUTSCHICH 1969 AND TAXONOMIC EMEN- DATION OF SPINOENDOTHYRA LIPINA 1963 By BERNARD L. MAMET When Skipp erected the new taxon Tuberendothyra (1969), she was unaware of the publication of the Sec- ond Colloquim on the Systematics of endothyroid foraminifers (Commission of micropaleontological co- ordination, Academy of Sciences of the USSR, 1963) in which numerous new endothyroid taxa had been pro- posed. She included in Tuberendothyra endothyroids “with unconnected thick secondary mounds of tuber- cles, ridges and crests. . .some of the deposits have re- sorbed bases and have an apostrophe shape in cross section” (1969, p. 211). She designated as type species, Endothyra tuberculata Lipina which she emended. In- cluded in the taxon were: Plectogyra tumula Zeller part (renamed T. paratumula), Endothyra tuberculata magna Lipina (renamed T. safanovae), Chernyshinella tumulosa Lipina, and Endothyra tuberiformis Durkina (which is not an Endothyridae and should be removed from the list). However, the original diagnosis of Spinoendothyra (1963) stated that the discontinuous secondary de- posits are ”spines, hooks or tubercles (tumuli) . . .” (p. 225). Thus, should Tuberendothyra be considered a junior synonym of Spinoendothyra? Both have similar morphology, the same disconnected secondary deposits throughout their whole life, and rather similar strati- graphic distribution and age. The question is further complicated by the fact that many forms described by Skipp as Tuberendothyra (for example, pl. 18, figs. 14—16, pl. 19, figs. 13—19, pl. 20, figs. 21, 23, 26, 27) have spinose projections, not tumuli. Furthermore, Skipp emended Lipina’s tubercu- lata to include forms with “apostrophes” and suggested that the shape was due to resorption; this is certainly not the Russian usage. Finally, Skipp believed that “Endothyra spinosa possesses secondary deposits as thin ridges, while the spinoendothyrids have thin, iso- lated, anteriorly curved projections, not parachomati- cal ridges.” It appears, however, that the distinction between Tuberendothyra and Spinoendothyra is feasible and useful in stratigraphy, if both genera are redefined as follows. GENUS TUBERENDOTHYRA SKIPP IN McKEE AND GUTSCHICK 1969 EMENDED Diagnosis.—Test free, irregularly discoidal, slightly compressed laterally. Proloculus followed by an irregu- BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE larly coiled spirotheca. Deviation of the coiling axis constant. Chambers irregular, subglobular. Septa ir- regular, anteriorly directed. Number of chambers in the last coil ranging from 6 to 10. Secondary deposits as discrete discontinuous tubercles present in all the chambers. N0 continuous floor thickening. Irregular septal thickenings. Wall calcareous secreted, a single layered microcrystalline tectum. Aperture, a low slit at the base of the apertural face. Type of the genus.—Endothyra tuberculata Lipina 1948. Akad. Nauk SSSR Geol. Inst. Trudy, V. 62, no. 19, p. 253, pl. 9, figs. 1—2. Taxa included in the genus.— 1955 ?crassitheca Lipina 1955 magna Lipina (OBJ, preoccupied by 1948 magna Rauzer-Chernoussova) 1969 sofonovae new name for magna Skipp in McKee and Gutschick 1957 superlata Malakhova 1957 ”tumula” Zeller (part) 1959 ?turbida Durkina Stratigraphic distribution and Cosmopolitan in the Northern Hemisphere North Africa, North America). Appears at the top of zone 7 Where it is scarce, abounds in zone 8, and disappears in the late Tournai- sian (zone 9). Usually present in pellet-algae or in pellet-calci- sphere grainstone and packstone. Absent in crinoid- bryozoan grainstone or in encrinite. range.— (Eurasia, GENUS SPINOENDOTHYRA LIPINA 1963 EMENDED Diagnosis—Test free, irregularly discoidal, com- pressed laterally. Proloculus followed by an irregularly coiled spirotheca. Deviation of the coiling axis constant or by sudden changes. Chambers irregular, subglobu- lar to subquadratic. Septa irregular, anteriorly di- rected. Number of chambers in the last coil ranging from 7 to 11, exceptionally 6 to 12. Secondary deposits as discrete, disconnected spines, present in all the chambers. N 0 continuous floor thickenings. No ridges. Wall calcareous secreted, a single layered microcrys- talline tectum, showing some differentiation in the most evolved forms. Aperture a low slit at the base of the apertural face. Type of the genus.—End0thyra costifera Lipina in Grozdilova and Lebedeva (1954). (VNIGRI, V. 81, p. 86, pl. 10, fig. 15.) Taxa included in the genus.— 1954 accurata Vdovenko 1956 ?analoga Malakhova 1956 apta Malakhova 1956 bellicosta Malakhova 1960 brevivoluta Lipina CONTACT BETWEEN DEVONIAN AND MISSISSIPPIAN ROCKS 1954 1956 1956 1954 1967 ?calmiussi Vdovenko concava Malakhova corona Malakhova costifera Lipina in Grozdilova and Lebedeva hirsuta Conil and Lys 1956 mammata Malakhova 1954 media Vdovenko (OBJ, preoccupied 1928 media Warthin) 1963 ?morr0ensis McKay and Green 1955 multicamerata Lipina 1954 paracostifera Lipina in Grozdilova and Lebedeva 1969 paraspinosa Skipp in McKee and Gutschick 1969 paratumula Skipp in McKee and Gutschick (part) 1954 ?paraukrainica Lipina in Grozdilova and Lebedeva 1960 ?piluginensis Lipina 1964 plagia Conil and Lys (OBJ, infrasubspecific) 1955 recta Lipina 1961 1940 speciosa Shlykova spinosa Chernysheva 1954 tenuiseptata Lipina in Lebedeva 1960 volgensis Lipina Stratigraphic distribution and range.— Cosmopolitan in the Northern Hemisphere (Eurasia, North Africa, North America). In North America wide- spread in the Cordillera and much scarcer in the mid- continent. Occurs for the first time in zone 8, very abundant in zone 9, disappears slowly in early Viséan time. Usually present in pellet-algae or pellet-calcisphere grainstone or packstone. Absent in crinoid-bryozoan grainstone or in encrinite. Remarks—If our interpretation is correct, Tuberen- dothyra is the most evolved known latiendothyrid and is the ancestral form from which Spinoendothyra is derived. Spinoendothyrids, by resorption of their pro- jections, will give the I nflatoendothyra and are there- fore the ancestral forms from which the dainellids are derived at the zone 9—10 junction. CONTACT BETWEEN DEVONIAN AND MISSISSIPPIAN ROCKS Kindle (1909, p. 7—8) reported “no trace of the Ouray fauna above the base of the large quarry south of Rockwood, although it is abundant a few feet below the floor of the quarry. . . In the section at the quarry. . . 5-10 feet of drab or rusty shale and shaly limestone separate the Devonian and Carboniferous beds. . . but this convenient lithologic boundary marker of the two horizons is not recognizable in some of the other nearby sections.” 13 Knight and Baars (1957) believed that the typical Ouray Limestone fauna has both Devonian and Mis- sissippian aspects and that the contact is gradational with the overlying Leadville Limestone. They suggested that the Ouray Limestone is transitional be— tween the Upper Devonian Elbert Formation and the Lower Mississippian Leadville Limestone. The boundary between the Ouray Limestone and the Leadville Limestone as yet cannot be dated by paleon- tologic methods at Rockwood Quarry or elsewhere in the San Juan Mountains. We have chosen the contact (pl 3; fig. 3, 4) at a marked lithologic break; it is the same contact as picked by Kindle (1909). The Ouray Limestone, 7 m below the contact, is brown to gray massive dolomite that is overlain by a 2-m-thick bed of crinoid-bryozoan-brachiopod packstone that contains a brachiopod fauna identified as Late Devonian, proba- bly mid-Famennian (see p. 4). A 5- to 10-cm-thick shale parting is overlain by a 2.1-m-thick bed of pellet-bryozoan—pelecypod-packstone that contains, in addition to Late Devonian brachiopods, the algal species Kamaena awirsi Mamet and Roux and the in- certae sedis Proninella sp. and Parathurammina sp. John Huddle also reports a Late Devonian condodont fauna from the top of this bed (see p. 5). No diagnostic conodonts or other microfossils were found from 2 to 17.1 m above the base of the Leadville Limestone at Rockwood Quarry. The lowest diagnostic foraminifers found are at 21 m above the base. The carbonate strata in the Leadville Limestone at Rockwood Quarry from 0 to 21 m above the base are considered to be Mississippian on the basis of microfacies. Nor can the contact between the Ouray and Lead- ville be picked with accuracy in the other measured sections of the Leadville Limestone discussed in this report. The Ouray Limestone at most localities is a fine-grained dolomite with sedimentary structures suggesting subtidal-intertidal deposition, and the basal beds of the Leadville Limestone are a similar rock type deposited in a similar environment. Both dolomites are devoid of diagnostic fossils. The lithologic criteria used in these sections to differentiate the Ouray from the Leadville are: (1) a change in color of the dolomite from brownish gray in the Ouray to gray or light gray in the Leadville; (2) a marked de- crease in argillaceous material in the Leadville; (3) the occurrence of intraformational conglomerates in the Leadville; (4) strongly developed stromatolites, lami- nations, and thin-bedded maroon shale in the Lead- ville; and (5) evidence of vadose weathering beneath the shale, on a supposed Devonian surface. The Coalbank Hill section, 66C—1, has 8.5 m of fine— grained dolomite that we assign on lithologic grounds 14 to the Leadville Limestone. These beds were assigned by Merrill and Winar (1958, fig. 4) to the Ouray Lime- stone on the basis of differences in insoluble residue between the two formations. Baars (1966, 1968) did not try to separate these dolomites and considered the unit as Leadville-Ouray, undifferentiated. A similar problem exists in the Molas Lake section 66C—2B. The Ouray section, 66C—5, contains 5.5 m of unfossiliferous dolomite at its base that we assign to the Leadville Limestone (pl. 2). Burbank (1932), in the Kerber Creek region of the Bonanza mining district in the extreme northeastern part of the San Juan Mountains, separated his Chaffee Formation from the Leadville Limestone on lithologic evidence. The limestone member of the Chaffee is about 27.5—31 m thick and is thin-bedded argillaceous dolomite that weathers a grayish orange. Burbank’s (1932) definition of the base of the Leadville Limestone is used in this report. It is argillaceous lime mudstone with lithoclasts and stromatolites, overlain by 40 m of black massive dolomite and black nodular chert, none of which contains recognizable fossils. The assignment of the Leadville to the Mississippian(?) and Mississip- pian is based solely on stratigraphic position and lithologic correlation with other Mississippian sections in Colorado. Burbank did not find any diagnostic Mis- sissippian fossils. Our study found microfossils, which indicate zone 9, only in the upper 2.5 m of the section. CONTACT BETWEEN MISSISSIPPIAN AND PENNSYLVANIAN ROCKS A regional unconformity at the top of the Leadville Limestone represents at least Meramecian, Chester- ian, and probably early Morrowan time. Meramecian and possibly lower Chesterian strata may have been present in the San Juan Mountains above the Osagean beds but were possibly removed by the regional uplift and subsequent erosion that occurred in Chesterian and Early Pennsylvanian time. In' the San Juan Moun- tains, the Molas Formation is 15—30 m thick and over- lies the Leadville Limestone. Merrill and Winar (1958) published a detailed study of the Molas and associated formations. They divided the Molas Formation into three parts: Coalbank Hill, Middle, and Upper Mem- bers. Their lowest unit, the Coalbank Hill Member, was formed as a residual deposit of nonmarine mud- stone and siltstone containing solution-rounded lime- stone, dolomite, and chert fragments. It accumulated as a result of uplift, erosion, and solution of Devonian and Mississippian carbonate rocks that occurred dur- ing Late Mississippian and Early Pennsylvanian time. The contacts between the Leadville Limestone and Molas Formation in the Rockwood Quarry (65A—12A), Coalbank Hill (66C—1), Molas Creek (660—2), and BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE Molas Lake (660—2B) sections are well exposed and typical. At these locations the contact between Merrill and Winar’s (1958) Coalbank Hill Member of the Molas Formation and limestone of the underlying formation is unconformable and gradational. Red mud and silt from the Coalbank Hill Member have sifted into open- ings in the limestone below. The solution of the lime— stone and development of the mantle apparently pro- gressed downward with time. Definition of the contact between the Molas Forma— tion and the Leadville Limestone is difficult. Merrill and Winar (1958, p. 2116) included most of the crinoid limestone from 7 to 20.4 m above the base of our Lead- ville Limestone at the Coalbank Hill section (66C—1) (pl. 3) in their type section for the Coalbank Hill Member. They (p. 2115, fig. 4) showed no Coalbank Hill Member in the Molas Lake section, 66A—2B, and located the contact as we indicate in our plate 3. The contact between the Leadville Limestone and the Molas Formation at the Ouray section 66C—5 is very sharp, with little evidence of solution activity in the limestone. The Molas Formation is absent from the Kerber Creek section (66C—6B) in the northeast San Juan Mountains where ferruginous pebble quartz conglom— erate and bedded black shale of the Pennsylvanian Kerber Formation unconformably overlie the Lead- ville Limestone. CORRELATION OF THE LEADVILLE LIMESTONE IN THE SAN JUAN MOUNTAINS Baars (1966) and Baars and See (1968) developed, for the San Juan Mountains area, an ancient tectonic framework in which the Grenadier highland and the Sneffels horst (pl. 3) were active before the Late Cam- brian Ignacio Quartzite was deposited. These high— lands created peninsular features that extended into the Cambrian sea. The positive topographic relief on the structural horsts persisted into Late Devonian time. They believed that downfaulting adjacent to the Grenadier highland was renewed during deposition of the Devonian Ouray Limestone. Baars (1966, p. 2103) believed that “crinoidal bioherms and stromatolitic dolomites occur in the Early Mississippian Leadville Limestone along the structurally high parts of these paleotectonic features, but no deeper-water sedimentary rocks were found in the ancient grabens. Renewed movement along the an- cient faults occurred in post Mississippian time.” The only rocks that are definitely known to be Mis- sissippian, and can be separated from the Ouray car- bonate rocks without question, are the crinoid-pellet- foraminifer limestone that occurs above the dolomite. REGIONAL CORRELATIONS AND PALEOGEOGRAPHY The dolomite beneath the crinoid limestone appears to represent intertidal-subtidal environments and con-. tain no recognizable microfossils, and thus it may well be a part of the Ouray Limestone. Our studies indicate, for the San Juan Mountains region, only weak residual bottom topographic influence on the distribution of Mississippian fossiliferous carbonate facies. The supposed Mississippian dolomites at the Coal- bank Hill and Molas Creek sections were correlated by Baars (1965; 1966, fig. 14) with his lower member of the Leadville Limestone in the subsurface of the east- ern Paradox basin. According to Baars, cores from the subsurface of the eastern Paradox basin, in the Lisbon oil field 430 km to the west, have yielded a microfauna of Kinderhookian age from the lower member. In the subsurface, Baars recognized an intraformational dis- conformity between his dolomitic lower member and his predominantly limestone upper member. We have assigned the unfossiliferous dolomite above the Ouray Limestone and beneath the fossiliferous Mississippian beds to the Leadville Limestone. It is best developed in the Coalbank Hill and Molas Creek sections (pl. 3). The Kerber Creek section, 150 km northeast of the Piedra River section, contains a 39.5-m-thick sequence of thin— to medium-bedded ar- gillaceous gray unfossiliferous dolomite. The interval is assigned to the Leadville Limestone on the basis of stratigraphic position and lithology. Parts of Baars and See’s (1968, pl. 1) detailed Missis- sippian facies and paleogeographic analysis for the San Juan Mountains region is open to question as it is based on the unfossiliferous dolomite beneath the Molas Formation adjacent to and across the Grenadier highland. Reconstruction of the regional facies distribution of the Leadville Limestone in the San Juan Mountains is complicated by the strong tectonic activity that oc- curred at the end of Leadville deposition and continued into Pennsylvanian time. This resulted in differential uplift and uneven removal of the fossiliferous crinoidal facies of the Leadville Limestone over large areas, and its complete removal over the Uncompahgre uplift. It is evident that the fossiliferous pellet-mud-lump- crinoid-ooid wackestone and packstone in the upper parts of the Leadville Limestone represent a regional transgression of zone 9, late Osagean age. The crinoidal carbonate rocks and associated rock types represent sedimentation on a shallow shelf with localized areas of lime mud accumulation or ooid sands developed in shoaling waters. No evidence of crinoidal bioherms was found in outcrops of the Leadville Lime- stone of this area. The present thickness or isopach distribution of the fossiliferous crinoidal beds of the Leadville Limestone 15 in the San Juan Mountains appears to reflect the ex— tent of Late Mississippian and Pennsylvanian erosion and may not be directly related to the original thick— ness at the end of Early Mississippian time. REGIONAL CORRELATIONS AND PALEOGEOGRAPHY REDWALL LIMESTONE, GRAND CANYON, ARIZONA Parker and Roberts (1963) correlated the Leadville Limestone of the San Juan Mountains and the subsur— face of the San Juan and Paradox basins with the Red— wall Limestone of the Grand Canyon region of Arizona. They considered the lower half of our Leadville Lime- stone at Rockwood Quarry to be equivalent to McKee’s (1963) Thunder Springs Member and the upper part equivalent to the Mooney Falls Member. Their correla- tions were based on analysis of subsurface electric logs from eastern Arizona and Utah. McKee and Gutschick’s (1969, fig. 26) monograph of the lithology and paleontology of the Redwall Lime- stone indicates that the Mooney Falls Member repre- sents the maximum eastward transgression of the Redwall Limestone. Mamet’s microfossil study in this report of the Leadville Limestone of the San Juan Mountains shows the Leadville Limestone to be equiv- alent to the middle part of the Mooney Falls Mem- ber of the Redwall Limestone of northern Arizona. Numerous oil tests drilled in the Black Mesa basin of Arizona and the Paradox basin of Utah show continu- ous Mississippian carbonate beds in the subsurface from the east end of the Grand Canyon to the outcrops in the San Juan Mountains (Parker and Roberts, 1963, figs. 12—15). ARROYO PENASCO GROUP, NORTH-CENTRAL NEW MEXICO A detailed account of the Arroyo Penasco Group, its lithology, microfossils, and geologic history can be found in Armstrong and Mamet (1974). The following description is, in part, abstracted from that report. The Arroyo Penasco Group includes two formations, the Espiritu Santo Formation and the overlying Tererro Formation. Its basal unit, the Del Padre Sandstone Member of the Espiritu Santo Formation (Sutherland, 1963), 05-15 m thick, is composed of quartz conglomerate, sandstone, siltstone, and thin shale (fig. 9). The Del Padre interfingers with carbo- nate rocks in the Espiritu Santo and should be consid- ered as the basal unit of a normal transgression; thus it is probably late Tournaisian. It rests unconformably on Precambrian rocks. A similar unit is present at the base of the transgres- sive late Tournaisian (zone 8) Caloso Member of the Kelly Limestone (Armstrong, 1958a, b) in west-central New Mexico. 16 BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE E .1 I“: m 05”, g z_ 0: mm _ -u 0 “In: 1: l- 2 P2 “- z.— Lu < Lu 2—3 0 >41,” to E n‘ .— O>_ 1"” Q 3 m 000: oz -5 E “7 0 >- 9!:qu ‘0 Iz E 0 n: (I) 2mm EN |-— LL 0 E Z c 5 '5; E s E O 3 5 u >. t to 0: ° E z 5 3 Z n. g 35 In .1 16i . I) E C G) g 30 2 ._. In 2 '1”! ° 2 o o 16i 25 C .9 c I“ a; E .n o E u. 0 E O D. 20 g 5 3 3: a 9 Z 3 I— 0 J S c E t E 2 g 7) a) In 9 {5' 5 U) - l 1’ s" 2 15 a 3. .. g ,5, < E o .C U Q E 10 C O 33 E 5 s , .. 3 5 g .9 IV 04 E In in I! O 13 w :5 mm :1 mg E 90 é 35 m l 3 0 z < uJE mm “-2 < 0 *1 FIGURE 9.—The Mississippian Arroyo Penasco Group at Tererro, west side of the Pecos River, Sangre de Cristo Mountains. N. Mex. The remainder of the Espiritu Santo Formation con- sists of dolomite, dedolomite, and coarse-grained poikilotopic calcite with corroded dolomite rhombs. Where the rocks are not dolomitized, such features as stromatolitic algal mats, Spongiostromata mats, echinoderm wackestone, kamaenid birdseye-rich lime mudstone, and oncholitic-bothrolitic mats are recog- nizable. This association suggests very shallow water intertidal to supratidal carbonate sedimentation. The carbonate rocks are 26.2 m thick at the Arroyo Penasco section in the Nacimiento Mountains and 8 m thick at the type section of the Tererro Formation in the Sangre de Cristo Mountains. The microfauna is usually destroyed or unrecogniza- ble in the dolomite and dedolomite; however, chert usually preserves the outline of foraminiferal tests, and stratigraphically useful microfossil assemblages can be detected. The most important taxa are: abun- dant Calcisphaera laevis Williamson, Endothyra sensu stricto, Latiendothyra of the group L. parakosvensis (Latiendothyra skippae of Armstrong), Septabrunsiina parakrainica Skipp, Holcomb, and Gutschick, Sep- tatournayella pseudocamerata Lipina in Lebedeva, and Spinoendothyra spinosa (Chernysheva). The as- semblage is zone 9 and is late Tournaisian. Carbonate rocks of the Espiritu Santo Formation are an eastward and southward, more shallow water facies of the zone 9 open-marine shallow-water foraminifer packstone- wackestone beds of the Leadville Limestone of the San Juan Mountains. . The Late Mississippian Tererro Formation of the Ar- royo Penasco Group is younger than the Leadville Limestone of the San Juan Mountains. The absence of Meramecian beds in the San Juan Mountains is un- doubtedly due to their removal by late Chesterian and Early Pennsylvanian erosion. Meramecian carbonate rocks are present in the subsurface of the Paradox basin of southeastern Utah and the Black Mesa basin of northeastern Arizona (McKee, 1972). The Tererro Formation includes in ascending order the Macho, Turquillo, Manuelitas, and Cowles Mem- bers. The lower 4.5 m of the Macho Member at Tererro, Pecos River, Sangre de Cristo Mountains, contains blocks of foraminifer-pellet wackestone that yield Tournaisian Spinoendothyra assemblages, whereas the matrix of the blocks yield Viséan Eoendothyranop- sis, notably Eoendothyranopsis macra (Zeller) and Eoendothyranopsis of the group E. ermakiensis (Lebedeva). In this instance, the formation of the brec- cia coincides with a hiatus that spans zones 10, 11 and 12. In other sections (e.g., Turquillo), the breccia is overlain by algal mudstone that contains zone 12—13 microfossils. At all localities, the upper parts of the breccia contain collapsed blocks, derived from the over- KELLY LIMESTONE OF THE LADRON MOUNTAINS, WEST-CENTRAL NEW MEXICO 17 lying Turquillo Member, which contains a middle Vis- éan microfauna.1 The origin of the Macho Member, a breccia, is diffi- cult to assess. It could have been formed by subaerial exposure after deposition of the Espiritu Santo Forma- tion (Baltz and Read, 1960; Sutherland, 1963). Or it could be the result of dissolution by meteoric ground water of interbedded carbonate rocks and gypsum (Armstrong, 1967) during Late Mississippian and Early Pennsylvanian. Armstrong and Mamet (1974) proposed the name Turquillo Member for a thick-bedded mudstone- wackestone, rich in foraminifers and bothrolites, that overlies either the Macho Member or, where missing, the Espiritu Santo Formation. The Turquillo Member is 2.5 m thick at the Ponce de Leon Springs section east of Taos. Elsewhere in the Sangre de Cristo Mountains it may be as much as 4.5 m thick. It is absent in the Pecos River Canyon. Foraminifers in the Turquillo Member indicate the passage of zone 12—13, which is the age equivalent of the Salem-St. Louis boundary (Armstrong and Mamet, 1974). The Manuelitas Member (Baltz and Read, 1960) is composed of thick-bedded oolitic-bothrolitic grainstone and a silty pellet fine-grained grainstone-packstone with minor calcareous silt. The oolite ranges in thick- ness from 0 to 10 In. It is clearly transgressive and rests on the Espiritu Santo Formation, or in the inter- vening Macho or Turquillo Members of the Tererro Formation. The oolitic unit is rich in foraminifers and is a St. Louis age equivalent (zone 14). The pelletoidal facies is poorer in microfossils; most of the foraminifers are minute archaediscids. The Cowles Member (Baltz and Read 1960), known only in the Sangre de Cristo Mountains, rests everywhere in the study region on the Manuelitas Member. The contact appears paraconformable. The top of the formation is eroded and unconformably over- lain by Pennsylvanian clastic rocks in all known expo- sures. Its apparent thickness ranges from 0.5 to 10 In. As in the Manuelitas Member, the Cowles mi- crofauna is composed almost exclusively of very small, rolled, abraded, and commonly mud—filled foramini— fers; these are mostly Archaediscidae with a few En- dothyridae and Eostaffellidae. The presence of primi- tive Neoarchaediscus and Zellerina clearly indicates that the formation is younger than Meramecian and should be regarded as an early Chesterian equivalent. There is, therefore, no proof of the existence of a Ste. Genevieve fauna between the Manuelitas Member and the Cowles Member. The Log Springs Formation (Armstrong, 1955) is ‘Thus the breccia could only be formed by postburial dissolution of the gypsum. If Baltz and Read’s hypothesis were correct, there would be no Turquillo blocks in the breccia. only known in the Sandia, J emez, Nacimiento, and San Pedro Mountains. The Log Springs Formation occupies a similar stratigraphic position in relation to the car- bonate rocks of the Arroyo Penasco Group as the Molas Formation does to the Leadville Limestone. The Log Springs is .2—5 m thick and rests with a marked uncon- formity on various beds of the Arroyo Penasco Group. It contains continental clastic red beds composed of oolitic hematite, shale, arkosic sandstone, and con- glomerate. It is post zone l6inf, and because it is over- lain with hiatus by zone 20, it must be late Chesterian. On the other hand, the Molas Formation is primarily marine in origin, well stratified, and contains Pennsylvanian Marine fossils in its upper parts (Mer- rill and Winar, 1958). KELLY LIMESTONE OF THE LADRON MOUNTAINS, WEST-CENTRAL NEW MEXICO The nearest outcrop exposure of brachiopod—bearing Osagean rocks south of Rockwood Quarry is the Kelly Limestone,composed of the zone 8 Caloso Member and the zone 9 Ladron Member of the Ladron Mountains, about 310 km away. The two members have a com- bined thickness in excess of 25 m. The name Kelly Limestone was applied by Gordon (1907) to Mississippian strata in the vicinity of Kelly in the Magdalena Mountains. The type section of the Kelly Limestone is defined as the outcrop on the crest of the Magdalena Mountains (NEMLSWM; sec. 31, T. 2 S., R. 3 W.). Kelley and Silver (1952) proposed the name Caloso Formation for the Mississippian rocks of the Ladron Mountains 41 km north of Kelly. Arm- strong (1955, 1958a) restricted the Caloso Formation to the lower part and the Kelly Formation to the upper part of the Mississippian section in the Lemitar, Mag- delena, and Ladron Mountains. His study (1958a) of the brachiopod faunas from these two formations indi- cated that the Caloso Formation was probably of early Osagean age and that the Kelly Formation contained a rich brachiopod fauna of late Osagean age. The Kelly Limestone in this paper is redefined as consisting of two members, the lower, the Caloso Member (the Caloso Formation of Armstrong, 1958a, 1967), and the upper crinoidal unit, the Ladron Member. The name Kelly Limestone is restricted to west-central New Mexico, in the Lemitar, Ladron, and Magdalena Moun- tains and Coyote Hills. The Caloso Member uncon- formably overlies Precambrian metamorphic and igneous rocks. A disconformity that probably repre- sents a short hiatus separates the» Caloso Member from the Ladron Member. The Ladron Member is uncon- formably overlain by elastic rocks of the Pennsylva- nian Sandia Formation. 18 BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE CALOSO MEMBER The Caloso Member (fig. 10) at its type locality, Caloso Arroyo in El/s sec. 30, T. 2 N., R. 2 W., Ladron Mountains, northern Socorro County, is 11.6 m thick. The lower 3—3.5 m is arkosic sandstone and shale. The limestone, about 6 m thick, is composed in the lower part of stromatolitic lime mudstone overlain by pellet-echinoderm-foraminifer wackestone and packstone. The brachiopod fauna from the Caloso Member’s type locality was described by Armstrong (1958a) and is Beecheria chouteauensis (Weller) and Spirifer cen- tronatus ladronensis Armstrong. Examination by Mamet 0f the thin section from limestone of the Caloso Member shows that it contains a microfossil as- semblage of zone 8. The Endothyridae are represented mostly by Latiendothyra, Medioendothyra, and Tuberendothyra. LADRON MEMBER The Ladron Member at its type locality in the Mag- dalena Mountains, NElfliSWlflr, sec. 31, T. 2 S., R. 3 W., is 21.5 m thick. It is gray crinoid-bryozoan wackestone and packstone with gray nodular chert. It is uncon- formably overlain by shale and conglomerate of the Pennsylvanian Sandia Formation. It is separated from the underlying Caloso Member by a disconformity. In the Ladron Mountains the Ladron Member is 0 to in excess of 15 In thick. The basal 0.1—0.3 m is arenaceous lime mudstone to quartz sandstone overlain by 15 m of light-gray bryozoan-echinoderm-brachiopod wacke- stone and packstone. The megafossil fauna of the Ladron Member of the Ladron Mountains was described by Armstrong (1958a) and contains the following taxa. Brachiopoda Rhipidomella sp Linoproductus sp. Chonetes cf. illinoisensis Worthen Tetracamera cf. subtrigona (Meek and Worthen) Tetracamera subcuneata (Hall) Rhynchopora persinuata (Winchell) Spirifer tenuicostatus Hall Spirifer grimesi Hall Brachythyris suborbicularis (Hall) Athyris aff. lamellosa (Leveille) Cleiothyridina hirsuta (Hall) Cleiothyridina obmaxima (McChesney) Dimegelasma neglectum (Hall) Blastoidea Pentremites conoideus Hall Coelenterata MIDCONTINENT PROVINCIAL SERIES MICROFOSSIL ZONE THICKNESS, IN METRES MEMBER FORMATION PENNSYLVANIAN SYSTEM M o rrowa n "UH-l 'O" O MISSISSIPPIAN Osagean * a a . a 8 4E :'-'O5QFZC'S.Q:§_Q§. . .. 8 * T >1— ‘3 * O a —3 ' . a+a >y z:a %5***a 8—8. dad-c.1305. PRE CAMBRIAN + + + + + + + + + —30 —25 —2O —15 Sandia Formation Member Ladron Member Caloso Limestone Kelly FIGURE 10.—Mississippian (Osagean) Caloso and La- dron Members of the Kelly Limestone, Ladron Moun- tains, west-central New Mexico. Zaphriphyllum casteri Armstrong Armstrong (1958a, p. 4), on the basis of the LATE OSAGEAN MARINE TRANSGRESSION brachiopods, considered the Ladron Member to be late Osagean (Keokuk). Microfossils found in thin sections from the Ladron Member are of zone 9. In spite of the fact that not a single Spinoendothyra could be identified, a latest Tournaisian age was established on the first occur- rence of Priscella, Pseudotaxis, and Tetrataxis. Brenckle, Lane, and Collinson (1974) have recently suggested that most of the Keokuk Limestone in its type region was younger than zone 9 because no Spinoendothyra could be detected. However, the Keokuk Limestone was deposited as an encrinite, and the Spinoendothyra fauna could not thrive in such a facies. In addition, spinose Endothyridae are scarce everywhere in the midcontinent, even in pellet grain- stone. As the Keokuk Limestone exhibits the first occurrence of Endothyra sensu stricto, Priscella, Tet- rataxis, Pseudotaxis, and Eoforschia, it may safely be considered to be late Tournaisian. Earliest Globoen- dothyridae are present in the upper part of the forma- tion and indicate the Tournaisian-Viséan passage. MICROFOSSILS The following taxa of algae and foraminifera have been recognized in the Kelly Limestone section 70N-8, Rio Salado, Ladron Mountains; all material is from USGS 10c. M1227. Caloso Member: Specimen numbers 70N—8 + 28—38 ft; 8.5 to 11.6 rn above Precambrian contact. Calcisphaera Sp. Calcisphaera laevis Williamson Earlandia Sp. Kamaena Sp. Kamaena of the group K. delicata Antropov Medioendothyra Sp. Latiendothyra sp. Palaeoberesella Sp. Parathurammina Sp. Proninella Sp. Septabrunsiina Sp. Septabrunsiina parakrainica Skipp, Holcomb, and Gutschick Septaglomospiranella Sp. Septaglomospiranella dainae Lipina Septatournayella Sp. Tuberendothyra Sp. Tuberendothyra safanovae Skipp in McKee and Gutschick Tuberendothyra tuberculata (Chernysheva) Age: Zone 8, early late Tournaisian. Lowest part of Ladron Member: Specimen number 70N—8 + 40 ft; 12 m above Precam- brian contact Calcisphaera Sp. 19 Calcisphaera laevis Williamson Earlandia of the group E. elegans (Rauzer-Cher- noussova) Earlandia of the group E. clavatula (Howchin) cf. Earlandinella? Sp. Kamaena Sp. Latiendothyra Sp. Latiendothyr‘a of the group L. latispiralis (Lipina) Latiendothyra parakosvensis (Lipina) Palaeoberesella Sp. Parathurammina Sp. Proninella Sp. Pseudokamaena Sp. Septabrunsiina Sp. Septaglomospiranella dainae Lipina Spinoendothyra sp. Spinoendothyra spinosa (Chernysheva) Tuberendothyra Sp. Tuberendothyra afT. T. tuberculata (Chernysheva) Vicinesphaera Sp. Age: Zone 8—9 boundary, late Tournaisian. Ladron Member: Specimen number 70N—8 + 68—77 ft; 21 to 23.5 m above the Precambrian contact. Calcisphaera sp. Calcisphaera laevis Williamson Earlandia Sp. Earlandia clavatula (Howchin) Latiendothyra Sp. Priscella Sp, Priscella prisca (Rauzer-Chernoussova and Reit- linger) Pseudotaxis Sp. Septaglomospiranella dainae Lipina Tetrataxis Sp. Age: Zone 9, late Tournaisian. LATE OSAGEAN MARINE TRANSGRESSION The stratigraphic record clearly Shows that a major regional marine transgression occurred in southwest— ern Colorado and New Mexico during zone 9, of late Osagean and late Tournaisian age (figs. 11, 12). It is represented in northern Arizona (McKee and Gutschick, 1969) by the Mooney Falls Member of the Redwall Limestone and in southwestern Colorado by the foraminifer—pellet-crinoid wackestone and packstone of the Leadville Limestone (pl. 3). In west- central New Mexico, disconformably overlying the subtidal-algal—foraminifer-pellet wackestone and packstone of the Caloso Member, of zone 8 age, is the high-energy shoaling-water crinoid packstone of the Ladron Member of zone 9 age (figs. 11, 12). In north- central New Mexico, the transgression iS represented in the Arroyo Penasco Group by the Espiritu Santo Formation, of zone 9 age (fig. 12). Armstrong and BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE ARIZONA COLORADO NEW MEXICO m E - :': Z O E 3,’ Lu 2 :> i- i; z' 8 "4 C! U) I Z to D O ‘0 O — (D m < l— .4 E . — 2' L” x < o a, z I E a: 2 g u w ‘1) _. u. )_ q u.| 0 . D ‘ '— _, _ Lu E A O l— l“ l- 2 (n 0 (a 2 U) 0 q to z 2 N D o l— u: w z z w _ w m < E O E o _ E in 3 2 U 0 O l U V y\ 2 II 2 O _1 < .1 g I“ < E 2 IL” 0 2‘” (E DLiJZ<0 “L40 2 z w w 3 3 0% 530i 32 35“" 525° 8‘54 3 _. _ .. ’— — _ ’u'; u: o 5< F<03 23 20§z>< 232x o§< n: > m u: —.l 3mm; <0 <<3 1’ Supai Molas Sandia and Sandia ‘2’ E g 1: Formation Formation Formation Flechado Formation Z < 5 P3 Formations c m E” > 3'5 , , ’P’f‘r—r ow r K WWW i: M 19 i'i ‘5 ? .v 7 E ' .2 18 Log Springs c Formation .‘2 £3 17 II) .C U 165 VI 1’ L g n 16i o E in E c ,7 ? Q 15 3 A I) m . L J 2 . +0 3 E a B N L 3 In 0 :x in Z 14 J ,j/J/J Elf figé a ”- Egg 0 3 E S Horseshoe '— 2 E S ’2‘; ‘8 n. / ~ 0 o ._ .,, (1. Mesa 0 t = g S ._ w ._ U) E 13 Member % o 5 :1 E m U U a, a 3 m 9 a F s 2 w E 0 c «bx/x. E E a o a E 12 § 5 ‘g 2 a A g m a: o E I) n. : W\ 11 g Mooney o < u > a: Falls 9 .E <2 10 —l Member , =m JJJJJJJN u, JAN 3 Lad on 9 '5’, Leadville 8 Merrfber D: Limestone Eng fi Thunder 7 7 j :2 E m g 8 Springs ' ' Del Padre Del Padre 4— Caloso g 3 a W Sandstone Sandstone J Member IE 3 O W Itmore Member Member 2 3 Wash 5 7 Mbr. o ’— —?-—? Pre ? 7 { ROCKS beneath Temple Butte Ouray ‘— the Mississippian Limestone Limestone _ (Devonian) (Devonian) Precambrian Precambrian Precambrian rocks rocks rocks FIGURE 11.—Regiona1 correlation diagram of the Leadville Limestone of the San Juan Mountains, 0010., and Missis- sippian rocks in adjacent areas. LOCATION OF STRATIGRAPHIC SECTIONS AND FOSSIL LOCALITIES Mamet (1974) reported that carbonate rocks of the Es— piritu Santo Formation consist of dolomite, dedolomite, and coarse-grained poikilotopic calcite with corroded dolomite rhombs. Associated with these carbonate rocks are stromatolitic algal mats, Spongiostromata mats, echinoderm wackestone, kamaenid mudstone with birdseye structure, oncholitic-bothrolitic mats, and calcitic pseudomorphs after gypsum. These indi- cate very shallow water sedimentation in subtidal to supratidal environments. The Espiritu Santo Formation represents, in part, subtidal to supratidal sabkha carbonate rocks depos- ited on part of the Paleozoic transcontinental arch in northern New Mexico. The relation of these sabkhalike deposits to the open-marine Leadville Limestone of the San Juan Mountains and Four Corners region and the crinoid-brachiopod of the Ladron Member of the Kelly Limestone of west—central New Mexico is shown in figures 11 and 12. Calcite pseudomorphs of gypsum are common in the carbonate rocks of the Espiritu Santo Formation. Armstrong (1967) and Armstrong and Mamet (1974) suggested the possibility that the Macho Member, a breccia, may represent a collapse breccia formed by the solution, in Early Pennsylvanian time, of interbedded gypsum and limestone that represent the upper part of the Espiritu Santo Formation in the Sangre de Cristo Mountains of New Mexico. These subtidal to supratidal beds began as the distal ends of the zone 9 transgression. They represent pro- tected, shallow—water carbonate sedimentation. Within a short time they became carbonate offlap re- gressive facies to the open-marine, higher energy car- bonate bioclastic sand of the Leadville Limestone of the San Juan Mountains and the Kelly Limestone of the Ladron and Magdalena Mountains of west-central New Mexico (Armstrong, 1967, fig. 6). Shallow—water subtidal carbonate regressive sediments may at one time have overlain the bioclastic carbonate rocks of the Leadville Limestone and the Kelly Limestone and were subsequently removed by pre-Pennsylvanian erosion. An idealized Late Devonian paleogeologic map is shown in figure 13 and a paleogeographic map of southern Colorado and northern New Mexico at the end of Osagean (zone 9) time is shown in figure 14, Which also presents an analysis and reconstruction of the carbonate environments. Armstrong and Mamet (1974) showed that the youngest known Mississippian marine deposits in the region are zone >161, lower Chesterian. In Chesterian and earliest Pennsylvanian time, the thin Mississippian carbonate sediments over the region were subjected to uplift, folding, and fault— ing. The consequent extensive erosion and weathering 21 over much of Arizona, Utah, New Mexico, and Col- orado (McKee and Gutschick, 1969; Merrill and Winar, 1958; Armstrong, 1958b) resulted in the removal of ex- tensive areas of Mississippian carbonate rock. The pres- ent-day disjunct nature of Mississippian outcrops is in large part due to this erosion. An idealized pre-Penn- sylvanian paleogeologic map is shown in figure 15. LOCATION OF STRATIGRAPHIC SECTIONS AND FOSSIL LOCALITIES US. Geological Survey fossil locality numbers: Those with an M prefix refer to locality numbers on file at the Pacific Coast Center of the Geological Survey at Menlo Park, Calif.; all others are Washington, DC, numbers. Rockwood Quarry sections 65A—12A, 66C—4; SW14 sec. 12, T. 37 N., R. 9 W., La Plata County, Colo. USGS loc. 9206-SD and USGS loc. M1180—M1186; USGS loc. 9206 D; USGS loc. 25447—PC, 25448—PC. Ouray section 66C—5; 1,207 m south of Box Canyon, on west side of Uncompahgre Gorge; sec. 6, T. 43 N., R. 7 W., Ouray County, Colo. USGS loc. M1193— M1197. Molas Lake section 66C—2B; section is a roadcut on the north side of the road and begins at lake level; sec. 7, T. 40 N., R. 7 W., San Juan County, Colo. USGS loc. M1190—M1192. Molas Creek section 660—2; section is on the north side of Molas Creek, 550 m south of Molas Lake, below and beside where Molas Creek cascades over the Leadville Limestone; sec. 7, T. 40 N., R. 7 W., San Juan County, Colo. USGS 10c. M1190—M1192. Coalbank Hill section 66C—1; north side of US. High- way 550, 1,500 m north of Mill Creek Lodge; sec. 6, ' T. 39 N., R. 8 W., San Juan County, Colo. USGS loc. M1187—M1188. Vallecito section 66C-3; 200 mi north of the north end of Vallecito Campground; NW% sec. 16, T. 37 N., R. 6 W., La Plata County, Colo. USGS 10c. M1198—M1199. Piedra River section 65A—10; 200 m north of the junc- tion of Davis Creek and the Piedra River; SE14 sec. 22, T. 36 N., R. 3 W., Archuleta County, Colo. USGS loc. M1226—1226a. Kerber Creek section 660—6 and 66—6B; near crest of hill about 1,000 m south of the road and Kerber Creek; sec. 25, T. 46 N., R. 8 E., Saguache County, Colo. USGS loc. M1200, M1201. Southern Ladron Mountain section 70N—8, in Caloso Arroyo, in 13% sec. 30, T. 2 N., R. 2 W., Ladron Mountains, Socorro County, N. Mex. (See Armstrong, 1958b, pl. 6, for photographs of out- crop.) METRES Tererro Formation 22 BIOSTRATIGRAPHY AND REGIONAL RELATIONS OF THE MISSISSIPPIAN LEADVILLE LIMESTONE 109° 108° 107° 106° 105° I I II Hockwood Otérry SAN ‘LUAN MITS I ’ l I II ’ Vallecito .h . ‘ ___- __ ,~/ 1 I — l .1 l" I L IA CO NTY BERNALILLO Z VA ENC U COUNTY E D TORRANCE <: 8 ___—___ ____ 1 COUNTY J 8 IF 1 \ :I I . . I Ladron _ Mountains I _l ‘ CATRON COUNTY '—‘ _ _ ' I I I SOCORRO ' Magdalena Socorro COUNTY I LINCOLN COUNTY 34° I Mountains I I I I O 25 50 75 MILES O 25 50 75 100 KI LOMETRES SANGRE DE CRISTO SAN JUAN MOUNTAINS SAN PEDFIO MOUNTAINS MOUNTAINS 2 § .5 ': E IE I‘,} K 3 <1: 0 5 c z _ E g o 0 a. 4 o >‘ h '2 e a) 5 g 3 ,3 D: g ‘D g o E 8 9 m 8 a s o = '0 1: 1: o .— ° § 3 a 8 E 3 [It I “I' I Manuelitas Member of I I I 0 Zone 14 10 / Leadville Limestone Arroyo . . 20 Penasco Espmtu e _ Group Santo Formation 30 4O 50 FIGURE 12.—Biostratigraphic correlation and facies relations of Mississippian rocks from the San Juan Mountains, southwestern Colo- rado, southeastward to the San Pedro and Sangre de Cristo Mountains of north-central New Mexico to the Ladron Mountains in west-central New Mexico. Detailed location maps of the stratigraphic sections shown in this diagram for New Mexico are given in Armstrong (1958b, 19767). Stratigraphic sections for the New Mexico outcrops are given by Armstrong and Mamet (1974). LOCATION OF STRATIGRAPHIC SECTIONS AND FOSSIL LOCALITI'ES 110° 109° 108° 107° 106° I 1 1 ‘ ’ PENNSYLVIXNIANQ ’ UPLIF o 38 #("Sneffels orst”) OurayILimestone / I (Dvonian) ,1 ,1 37° UITZPBENA t133111173131E13380/- 1’15”: /, a11/1117/T1 Mm: 1/4/11////¢ 11:,\‘ ”//“// Hie 11”, ‘1. w =44L/l¢11l1/\\//"//\\:1\T \§ ”4; , \ / «M’é/L/u/ 4:1111:’//1‘§“ “ II Il=\\l|\\ \\'\\§n\ ‘\\ \\\\:\ ,§\,1 VI” 0”“ \\Y"\\l\\ e“ \111//\\// I’//\/l'//”\\|1\\\,,\\II\\// II ¢11 «7/1 \11 JIJJ. ////1//11’/ ,,// \\\§u“\ ' 1/\\\/“,\\/‘" \\K,,”‘///”‘/,:/ 11, \\\\eflfl " e sL/ / \ .z a 36 ” l‘111|//\\~\\/ :Im/ffl< “§j/L//L\\//‘ = ’/ :lu/ //\1“111// /// \1, \\\\I/, ’11 06/7"’/a/II:11\//I”//\\‘ft:‘1{//\\=\II/:H=W 1‘“ /~/\\‘\\1111‘\'\“//I”/1\\ }\ ”=11I/ k1,?” / /~// \\\// 11/ )1” :/\11 \\\\ §\\ “\\/ /\(I“”II’/\\///’§ //\\. \\\’§\\/1III”11//\11,,, \ ’ré — //\\ /11//// 1 [y/ //4 21111111 /\\ ,,,/,\ 7;~«11~1F,/ ’//I¢//11”’/ ¢;/,,,Hgn// =// 11 11/ ,1 1,4 \\ awe/,4 \1 011 \\I§§ 11 \\ // ,, a 11 L1” II\\C11~I1 /V/. \//:I1 =/“/‘::://§//\‘/\\\ // 1 ” '=\\ \\1r11//11\11/11/11 /U.I//4H/,§1‘ iF'omation J E :,,/I////1///1=4¢ 4¢//:a.11///,11’/ (b V0ni;rfl,’11:1////\1 11;\\ 111/,\\//11/,71Ii_1_\ Percha Shale 0 50 100 MILES (Devonian) O 50 100 150 KILOMETRES EXPLANATION \ \ \ e 11 = 11 e I1 \\ I/ \\ 11 Precambrian highlands of low relief Devonian a Paleozoic deposits Area where Devonian and lower Paleozoic rocks were removed during Chesterian and Early Pennsylvanian time SANGRE DE CRISTO MOUNTAINS VI 55 .E 'o L E 9- :1 "’ e C o g 3 fl 0 E f, E o E m 2 E E 8 E. S 0 g I o e 1: ,. g “- fi g 2 32‘ e 9 o 2 '5 :1 0 g a ‘16 n. I .I I- : 3 I- D Zone 1 Zone 16i Cowles Member Tererro Formation 10 0 E nd lower marine SANDIA MOUNTAINS — Placitas 4 Manuelltas Memberouocgauy ‘ ...: an a - 'ho Me E? a on Espiritu Slanto 20 o 37 36° 23 105° 4 FIGURE 13. —Idea1ized Late Devonian paleogeologic map of southern Colorado and northern New Mexico. debosits 109° 108° 107° : a1 11 em 1,»- ~~~~~~~~~~ m1; 5M.” » 1 ’4‘ 4’ . ix x I 1 Pellethinoid \W ‘3 I) 2 packstone aqgawaclseesmn M ”wk I 1 ,1 1 jLead ilie'Lime tone / 3 w. 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E C; E E L ._. 9 (D I G) ,5 9 E 3 11 E 5 / 122 Z w 8 E'E D 8 5 E; < I 0 I ._ > g 2 E Z E” g; E 11> I <11) g g ES 5 I7,- 3 22 g 1 O I X —I £13 3 Q 3‘ E 20— °° ‘5 X I X :3 5'2 W 8 g. 3- 1374/0}: ‘- 8 O A_ )— IX I 19- S E m «I X I X Egg 2 “5 a I X I s 2% 3 =3 — — - —_— D ,2 -L—’ 2‘ e *— ‘_ _—_ X I x 451% g L were — o (I: :LI’X:I S2 §15_E:va H o o a. 4,: VI X X “’ ‘ LITHOLOGIC SYMBOLS I09 I08 -~ ‘3 l X l 29 I \ g, a/«m ,zvv: E I m i \ MON \\ T_ _ _ E .5 / o z m COMPOSITION, IN PERCENT CARBONATE PARTICLES OTHER THAN FOSSILS I TROSE \ GUNNISON 2 II, c; E E I \ COUNTY \\\ T--.\ OURAY COUNTY ‘13 f: f g 2 0 10 50 90 100 Dolomite Coated particles \ \\\ “ COUNTY I g g o ,2 L E~ ,""— T ‘ _ _ 9 ‘- F E I I l/ I/ I/ I/ I/ / More than i— _____ ‘\‘\\ 91:) g D I i/ I i/ I 1/ 1/ 1/ Size mm Mud one 'aye’ one layer I s 1 66C 5 1 q E IO _ if I I, I/ I/ I/ I/ I/ I SAN MIGUEL COUNTY ’IIE F1: Hg \ I .o e E Silt I do O 38° — L POM paIeootfigSTI /HINSDALE 5 g 100 90 5O 10 O Limestone 0.063 Gold \ ‘29": 3/ COUNTY .AJ’V‘K [3/7 .2 . Dolomitic Calcitic . Sand I d> ‘& SAN JUAN K \ f / E M I-Imesmne IImesIone dolomite DOIom'te 2.0 Superficial I’O' /'——'——— ———— COUNTY / c3 . I _ \ i .— Granule 4IO (D 001d @ SIS: \v/E/‘C. 2 Sllvertont \ o , , I . Pisoid 6 \ I ‘7 9 06,9000 -—-I <9: : 1 I [X] I «v 52 M1 IRA”, 23 I m V I i 5 g Shale Sandstone Conglomerate Bedded chert Covered interval IO \660-1 5/?&l\ \ I; M — .9 -E in limestone SYMBOLS FOR FOSSIL PARTICLES I2———————— —— —— — /eaI/Q _____ I RANDE COUNTY IALAMOSA 3 & E w +1 ‘ ROG COUNTY 6; WE _ d I: MONTEZUMA COUNTY o .— 1x I I o z o (I) V E - - o. m {D g N “)> \ L) — — 1*) mg U) o 2 to .- z 8 W . I 8 E w _ w o Algal mats Solltary coral Caicareous algae I j \ E,l / . g: $ <2 ‘5 Nodular chert Carbonate lithoclast Irregular bedding I EXPLANATION / 65A~12A ’Ns \\ Alamosa II - 9.: g E D O : {33 T A E 623:1 P—1—-—- T—“__‘ 1. _.l__ 88 8 6 —— '0 Br ozoans Sponge spicules Brachiopods 0 / 65A-10 I 0 — _ _— _ y . I _ _ D Calcite pseudomorphs after Crossbedding Vugs I Me_asurefi seetlon de- l D I I :__/4_ 5 3 QVDSum and anhydrite é ZS Q i scnbed 1" ”“5 report / Durango ARCHULETA COUNTY\\ l\ I 75 E I; g \ : _, g Foraminifera Pelecypods Ostracodes I r/IV-q LA PLATA COUNTY CONEJOS COUNTY I '—:-’r g E g TEXTURE . . . . S I I /=——7—‘ E? Z V, A I M1551551pplan outcrop l 2 —_ B E g. Z s e M W P 1 / I 1 grv-A- 13% o 4 -— D Echinoderm I L RADO _ _ _ M_ - >1; L — g —I g 5 Lime mudstone Wackestone Packstone 37° —I—I - — — — — '— - — —; — — - -I— — - NCE(TV_CI\)TEW " — — ‘ — —— — "J'A" _ — 5 _ ‘1— gel; (9 Z > > .§ 5 . _ . O ‘ Ex: :3 a g 2 Lou g £39 G D X USGS fOSSIl locaIItIes 12::ter :aars IISSSI W d 2;; —- S g fi 3 — [er aars , anger : _ a; L _: O I: E Grainstone Dolomite Crystalline gig, W 4:59 (1962), and Mallory (1972) (ID ID 410 5'0 é: a: O "' o __ a, . . Conodonts Al ae I ' I I I I 3L -—/f o «91 U USIIfIsIglgc‘ 9 O 10 2O 50 60 70 80 90 100 KlLOMETRES t if E .— 19} E 75: — es Foraminifera Brachiopods LOCATION OF SECTIONS —10 :_¢ ('3 if? InteriorEGeological Survey, Menlo Park, CA.—1976—G76174 LOCATION OF STRATIGRAPHIC SECTIONS AND BIOSTRATIGRAPHIC CORRELATION CHART OF LEADVILLE LIMESTONE, SAN JUAN MOUNTAINS, SOUTHWESTERN COLORADO @575 Pa, U- 0"?" 7 DAYS East-Trending StruCturaLl ' Lineam ents in Central Nevada GEOLOGICAL SURVEY PROFESSHNYAL PAPER 986‘ MUMEWS 0‘3”me Jnfila \BKARY TLY OF M OB“ 3.7.33.3. JAN 4 1977 East-Trending Structural Lineaments in Central Nevada By E. B. EKREN, R. C. BUCKNAM, W. J. CARR, G. L. DIXON, and -W. D. QUINLIVAN GEOLOGICAL SURVEY PROFESSIONAL PAPER 986 A description of four east-trending structural lineaments inferred to be deep-seated crustal features UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976 UNITED STATES DEPARTMENT OF THE INTERIOR THOMAS S. KLEPPE, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Main entry under title: East-trending structural lineaments in central Nevada. (Geological Survey Professional Paper 986) Bibliography: p. Supt. of Docs. no.: I 19.162986 1. Geology—Nevada. 2. Magnetism, Terrestrial—Nevada. 3. Faults (Geology)—Nevada. 4. Landforms—Nevada. I. Ekren, Einar Bartlett, 192 3— II. Series: United States Geological Survey Professional Paper 986. QE137.E24 551.8’09793'34 76—23287 For sale by the Superintendent of Documents, US. Government Printing Office Washington, DC 20402 Stock Number 024—001—02924-3 PLATE 1. FIGURE 1. 2. 3. 4. CONTENTS Page Abstract .......................................................................................................................... 1 Introduction .............................................................. 1 Timpahute lineament ........ 2 Warm Springs lineament .................................................................... 4 Hot Creek Range—Kawich Range area... ............................................ 5 Monitor Range and adjacent areas ........ 5 Tonopah area .................................................................. 5 Area west of Tonopah.... ............................................ 5 Pancake Range lineament .......................................................... 6 Pancake Range, Moores Station area, and Morey Peak ............. 6 Morey Peak to Toiyabe Range ......................................................... 9 Toiyabe Range to Pilot Mountains. 9 Pilot Mountains to Mono Lake .............................................. 9 Probable extension of lineament east of Pancake Range... ........... 11 Pritchards Station lineament ................................................................... 11 Expression west of the Monitor Range ...................................... 12 Extension of lineament in ranges east of Pritchards Station... ..................... 13 Intersection of the lineaments with the Walker Lane ......................................... 14 Summary and discussion ......................................................... 15 References cited ................................................................................................................... 15 ILLUSTRATIONS Page Geologic strip map of west—central Nevada showing trace of the Warm Springs and the Pancake Range lineaments .................................................................................... In pocket Map of Nevada showing lineaments described or referred to in this report ........................................ 3 Landsat photograph of Lincoln County, Nev., and part of western Utah showing Timpahute lineament and adjacent Basin and Range topography .................................................................. 4 Raised-relief map of eastern California and western Nevada showing parts of the Warm Springs, Pancake Range, and Pritchards Station lineaments ................................................................... 6 Aeromagnetic map of the Warm Springs region showing magnetic discontinuity or interruption along the eastern part of Warm Springs lineament .................................................................... 8 Aeromagnetic map of the region between Lone Mountain and Mono Lake showing the westward projection of the Warn} 'Springs lineament ............................................................................... 10 Aeromagnetic map of the Hot Creek Valley region showing the Pancake Range and Pritchards Station lineaments .................................................................................................. 12 Generalized geologic map of the Wood Canyon area, northern Pancake Range, showing contrasting structure and stratigraphy north and south of Wood Canyon ............................................... 13 III EAST-TRENDING STRUCTURAL LINEAMENTS IN CENTRAL NEVADA By E. B. EKREN, R. C. BUCKNAM, W. J. CARR, G. L. DIXON, and W. D. QUINLIVAN ABSTRACT Several east-trending topographic and structural lineaments in central Nevada coincide locally with lithologic boundaries, range and valley termini, caldera boundaries, and strong magnetic interruptions. Most of the observed magnetic anomalies or interruptions along the lineaments can reasonably be attribut- ed to the deposition of volcanic rocks against easterly trending topographic highs, to the juxtaposition by faulting of rocks having different magnetic properties, or to plutonic rocks intruded into structures within the lineament trend. The tangential association of volcanic centers and cauldrons with the lineaments implies a deep-seated crustal control. Two of the lineaments can be traced from central Nevada into easternmost California; another extends into western Utah. Two lineaments appear to cross the Walker Lane without offset and bound a block of ground that is not greatly displaced by strike-slip faults of the Walker Lane system. Whether the lineaments are partly a result of conjugate faults developed at the inception of the Walker Lane and other major northwest- trending faults in the southwestern Great Basin, or whether they owe their origin to an even more regional or even continentwide fracture system is an unresolved question. INTRODUCTION Several throughgoing east-trending structures in central Nevada are suggested on the basis of lin- eaments expressed primarily by alinement of top- ographic features. Aeromagnetic data indicate that the topographic features coincide closely with east-trending magnetic lineaments in many areas, and recent mapping in Nevada by the authors and others has defined a local geologic basis for parts of these lineaments. The purpose of this paper is to call attention to the probable length, number, and importance of these features. Field studies have shown that structures associ- ated with the lineaments appear to (1) influence, if not control, the location of many volcanic centers; (2) consist of old zones of weakness, structural hinge lines, or strike-slip faults; (3) commonly exhibit strike-slip displacement that is almost everywhere left-lateral; (4) have strike-slip movements ranging in age from middle to late Tertiary; (5) be at least surficially discontinuous; and (6) coincide along parts of their lengths with marked magnetic disconti- nuities. The possible regional extent of these structural lin- eaments is inferred largely from coincident topogra- phic and aeromagnetic lineaments. The authors recognize that such speculation about regional structures is hazardous, as has been so aptly stated by King (1970): Drawing great linear and more or less hypothetical faults across a map is a favorite pastime of many geologists.*** One of the most troublesome problems of line drawings is the age relations of the features. Often, the lines “put too many eggs in one basket,” connecting features whose ages might be anywhere from Precam- brian to Cenozoic, depending on locality. The dedicated drawer of lines dismisses the problem by saying that the lines represent deep, fundamental crustal fractures, which might be manifested in the upper crust or at the surface by faults of different ages or different kinds, or even by no break at all. E ast—west lineaments in the Basin and Range prov- ince are not confined to the area described herein. Zietz and others (1969) and Affleck (1970) discussed magnetic interruption north of 40° latitude as possible continuations of the Mendocino fracture zone of California. Slemmons (1967) briefly described three transverse trends in Nevada that are marked by low topography, appear to influence the pattern of faulting, and affect the regional patterns of tilting produced by faulting. The transverse trends des- cribed by Slemmons strike east-southeast and do not correspond to the lineaments described in this report. Cook and Montgomery (1974) described several east- . west structural trends in Utah, based on topographic and gravity data from the eastern Basin and Range province, that they felt extend into Nevada. The most southerly of the east-trending lineaments described by Cook and Montgomery is at the approximate latitude of 382/3 °, the same as our Pancake Range lineament, and conceivably could be the same structural feature. If this is the case, the lineament in Nevada is at least surficially discontinuous with the lineament in Utah. The eastern part of the Great Basin, principally in Utah, has not been considered 1 2 EAST-TRENDING STRUCTURAL LINEAMENTS IN CENTRAL NEVADA here, and it may or may not fit the structural pattern described in this report. Burke and McKee (1973) described two large, west-trending troughs in north- central Nevada that are pre—Basin and Range in age and are filled with extremely thick sections of Tertiary volcanic rocks. These troughs are as much as 72 miles'(116 km) in length. Anderson (1973) has documented a major northeast-trending, left-lateral, strike-slip fault zone in southeastern Nevada. In our view the lineaments discussed here are not lines of finite width but zones varying from a few miles to as much as 16 miles (25 km) wide. Itis not our intent to address or solve all the problems associated with these complex structures in Nevada or those described by other authors but, rather, to document in detail the geologic evidence of the existence of a pervasive pattern of easterly trending structures in the central Great Basin. The easterly trending structures of centralNevada appear to us to be concentrated in four zones, named from south to north: 1. Timpahute lineament, 2. Warm Springs lineament, 3. Pancake Range lineament, and 4. Pritchards Station lineament. TIMPAHUTE LINEAMENT The Timpahute lineament extends across Lin- coln County, Nev., into Utah (fig. 1). In western Lincoln County, the lineament is expressed by discontinuous east-northeast-trending topography from the Timpahute Range through the North and South Pahroc Ranges. In eastern Lincoln County, the lineament is expressed by easterly elongated and faulted rhyolite masses in the vicinity of the Utah State line. These features are conspicuous on Landsat (formerly called ERTS) photography (fig. 2). The Timpahute lineament is inferred to be a deep- seated structure that (1) controlled east-trending ranges or the relatively uplifted ground that extends from Sand Spring Valley eastward to Dry Lake Valley, (2) interrupts north-trending valleys and ranges, (3) separates areas of contrasting structural style, (4) controlled the location of several intrusive masses, (5) localized strike-slip faulting, and (6) is the locus of recent seismicity in the southern part of the North Pahroc Range. Importance of the topographic lineament in eastern Lincoln County as a structural element is also indicated by a marked magnetic discontinuity or interruption (US. Geological Sur- vey, 1973) and by contrasting structural styles to the north and south. North of the lineament, discrete northerly trending basins and ranges dominate the topography; to the south, in contrast, for a distance of 20 miles (32 km), a broad platform of volcanic rocks is present. A west-southwest—trending zone of seismic activity (fig. 1) extending from the Intermountain seismic belt (Smith and Sbar, 1974) in Utah lies within this area. Gravity data (Department of Defense, 1975) show a very broad region of east- trending contours south of Caliente, having the gravity gradient down to the north, that contrasts with a pattern of highs and lows at the latitude of Caliente and northward. Contrasting structural styles are apparent also across the lineament between the North and South Pahroc Ranges (E. B. Ekren, P. P. Orkild, K. A. Sargent, and G. L. Dixon, unpub. mapping, 1976). The North Pahroc Range is anticlinal and the range is complexly and intricately faulted by closely spaced north-striking faults. The South Pahroc Range dips consistently to the west and is only moderately faulted; east-trending normal faults are conspicuous here, but they are absent in the North Pahroc Range. In addition to contrasting structure north and south of the Timpahute lineament, numerous igne- ous intrusive masses occur on or near the feature. These masses, from west to east (fig. 2), are rhyolite and granite plugs exposed at the north end of the Groom Range, the granite of Tempiute in the Timpahute Range, the diorite and granodiorite intrusives of the Chief Range near Caliente, and the dioritic and granitic masses of the Cedar Range. Still farther to the east, extending into Utah, are the previously mentioned large rhyolite masses that are elongated easterly and were undoubtedly fed from east-trending fissures. The lineament is tangential to the northern boundary of a large cauldron complex in the vicinity of Caliente (fig. 2) that has previously been called the FIGURE 1.—Map of Nevada showing lineaments described or referred to in this report. 1, Timpahute lineament: GR, Groom Range; T, Tempiute; PR, North and South Pahroc Ranges; CR, Chief Range; CRA, Cedar Range. 2, Warm Springs lineament: QV, Queen Valley; BJ, BlairJunction; LM, LoneMountain; RM, Red Mountain; SMR. Southern Monitor Range; WS, Warm Springs. 3, PancakeRange lineament: AH, Anchorite Hills; EM, Excelsior Mountains; GF, Garfield Flat; GVR, Gabbs Valley Range; PM, Pilot Mountains; CM, Cedar Mountain; TY, Toiyabe Range; TQ, Toquima Range (Manhattan); MR, Monitor Range; MP, Morey Peak; MS, Moores Station; PA, Pancake Range; C, Currant. 4, Prichards Station lineament: LV, Lodi Valley; UC, East and West Union Canyons (Shoshone Range); TR, North Twin River (Toiyabe Range); MV, Monitor Valley (drill hole UCE-16); TC, Tulle Creek (Monitor Range); HC, Hot Creek Range; PS, Pritchards Station; PO, Portuguese Mountain (Pancake Range); H, Horse Range; WPR, White Pine Range. 5, RawhideYerington lineament of Bingler (1971): Y, Yerington; WR, Wassuk Range; RH, Rawhide. TIMPAHUTE LINEAMENT 120° 119° 118° 117° 116“ 115° /1_"______7r_______|—__—'_ .26‘ H Western branch‘of Death Valley— 4] Furnace Creek .. Z ’ lntermountain seismic zone fault zone "-Q/VE I ..... 4....... I \ ‘ . ..... QEARK \ E V ...... I as egaS/ \ / \— o \\ 36 \ \ \ I 0 100 200 MILES q \ 1 1 1 A \ I o 100 200 KILOMETRES \1 EXPLANATION —— --- — ---- ——® Lineament— Dotted where not present at sur'face >l< Intrusive on lineament 4 EAST-TRENDING STRUCTURAL LINEAMENTS lN CENTRAL NEVADA Caliente depression (Noble and others, 1968; Noble and McKee, 1972). The depression is considered to be related to extensive eruptions of tuffs and lavas that range in age from about 24 m.y. to 15 mCy. (Noble and McKee, 1972). The cauldron complex is centered farther south than the volcano—tectonic depression of the above authors and is considerably wider east to west. Strike-slip faulting has occurred locally along the Timpahute lineament. It has been well documented only in the vicinity of the Timpahute Range. On the north flank of the range, two prominent faults occur. On the basis of drag, one fault (the more northerly) has moved left-laterally; the other has moved right-laterally. Major east-trending faults on the south side of the Timpahute Range probably also have significant strikeslip components (Tschanz and Pampeyan, 1970, p. 84), but their direction of lateral movement has not been determined. The Timpahute lineament appears to be ex- 10 l o——o I 10 pressed seismically by an east-trending swarm of epicenters located across the south end of the North Pahroc Range from the south end of Coal Valley to Dry Lake (fig. 2; F. G. Fisher, written commun., 1973). The epicenters do not correlate well with mapped structure, and we feel that the seismic activity may be related to a deep-seated structure along the line- ament. WARM SPRINGS LINEAMENT A pronounced east-trending structural and strati- graphic discontinuity, the Warm Springs lineament (fig. 1, No. 2), extends from Queen Valley, just north of Boundary Peak in the White Mountains on the Nevada-California border, eastward to the pass between the Hot Creek and Kawich Ranges south- west of Warm Springs in Nye County (fig. 3; pl. 1). US. Highway 6 follows this lineament rather closely. The lineament coincides with an east-trending magnetic interruption (fig. 4). F. J. Kleinhampl and ntrusives of the 4‘ Cedar Range 1‘ , 20 I I 30 KILOMETRES 3'0 MILES I 20 APPROXIMATE FIGURE 2. —— Landsat photograph (NASA E—1106—17492—1, Nov. 6, 1972) of Lincoln County, Nev., and part of western Utah showing Timpahute lineament and adjacent Basin and Range topography. WARM SPRINGS LINEAMENT 5 J. I. Ziony (oral commun., 1963) noted the marked geologic discontinuity in the course of mapping northern Nye County. They considered the possibili- ty that the feature was a strike-slip fault but found no evidence to confirm this concept or to define a possible direction of movement(oral commun., 1974). HOT CREEK RANGE-KAWICH RANGE AREA Reconnaissance mapping of the northern Kawich Range by E. B. Ekren and C. L. Rogers (unpub. data, 1966) suggested that the northern bulbous end of the Kawich Range was the resurged part of a large cauldron (pl. 1) whose northern boundary appears to coincide with the east-trending discontinuity sug- gested by F. J. Kleinhampl and J. I. Ziony (oral commun., 1974). The lineament along US. Highway 6 (pl. 1) contains irregular bodies of rhyolite and andesite. North of the lineament the exposed rocks along the east flank of the Hot Creek Range are middle Paleozoic in age, including Devonian strata in a lower plate and Mississippian and Devonian strata in an upper plate (Kleinhampl and Ziony, 1967). Volcanic rocks north of the lineament include cooling units assigned to the Shingle Pass Tuff (Cook, 1965). These units form extensive outcrops on the west flank of the Hot Creek Range. South of the lineament there are no Paleozoic outcrops, and the Shingle Pass Tuff occurs only in brecciated masses that have slid or have been thrust over ash-flow tuffs that form the northern terminus of the Kawich Range. The autochthonous tuffs include the Monot- ony Tuff (Ekren and others, 1971) and younger tuffs of the Kawich Range. The Monotony Tuff in the vicinity of the lineament strikes nearly east-west and dips steeply to the south or stands vertically. Whether the steep dips in the Monotony Tuff and the occurrence of detached or thrust-faulted masses south of the lineament relate to caldera collapse or to possible strike-slip movements along the east- trending discontinuity is undetermined, but these occurrences are strikingly similar to relationships observed elsewhere in central Nevada in proximity to strike-slip faults (Ekren, Quinlivan, and Marvin, 1974; Ekren, Rogers, and Dixon, 1973). The relation- ships that have been described suggest to us that the zone is a fault, probably a strike-slip fault. MONITOR RANGE AND ADJACENT AREAS No single east-trending fault or discontinuity comparable to the lineament between the Kawich and Hot Creek Ranges is known to occur in the ranges to the west between Tonopah and the Hot Creek-Kawich Ranges, but marked stratigraphic discontinuities strongly suggest that an east- trending lineament projects through this area. For example, near the southern terminus of the Monitor Range (pl. 1) in the vicinity of US. Highway 6, basalt outcrops are abundant south of about 38°07’ and are virtually absent north of this latitude (Kleinhampl and Ziony, 1967; R. E. Anderson, written commun., 1966). In addition, several large outcrops of pre- Tertiary rocks occur south of the lineament but are virtually absent to the north. North of the lineament in the Monitor Range area, the Tertiary volcanic sequence appears to be very thick but large exotic blocks of quartzite and other Paleozoic rocks occur there that appear to be intercalated in the volcanic strata (R. E. Anderson, oral commun., 1966; F. J. Kleinhampl, oral commun., 1974; H. F. Bonham, J r., 1975). According to Bonham the large blocks of Paleozoic rocks are as much as a city block in length; they are entirely enclosed in ash- flow tuff, and they probably owe their origin to landsliding during caldera collapse. Therefore, if Bonham’s analysis is correct, the lineament coin- cides closely with the southern boundary of a large caldron complex (pl. 1). The boundary cannot project much farther south than the lineament because of the apparent thinness of the volcanic sequence there as indicated by the occurrence of large bedrock expo- sures of pre—Tertiary rocks. TONOPAH AREA The Warm Springs lineament is inferred to pro- ject nearly due west of the Silver Leaf mine (Han- napah mining area) to the vicinity of Red Mountain, north of Tonopah (pl. 1). In this area the lineament is expressed as the south boundary of a north-trending belt of pre—Tertiary rocks. North of the line, Mesozoic granite and Paleozoic rocks are exposed in a broad area, but to the south they are deeply buried beneath voluminous Tertiary lavas and tuffs that have been mineralized with silver ores and have been mined to depths in excess of 2,000 feet (610 m) (Bonham and Garside, 1974). AREA WEST OF TONOPAH West of Tonopah several options are open to the “dedicated drawer of lines.” These options include the following: (1) On the basis of topography and magnetics, the lineament occupies a fairly wide zone that passes north of Lone Mountain and trends west- southwest toward Columbus Salt Marsh and Mono Lake (figs. 3, 5; pl. 1); (2) the lineament either ends at the Walker Lane west of Lone Mountain (fig. 1) or it is offset to some position north of the Columbus Salt Marsh; and (3) the Walker Lane is offset by the . lineament (Albers and Stewart, 1972). If the line- ament is drawn to follow the most prominent topographic break (option 1), it would parallel a set of 6 EAST-TRENDING STRUCTURAL LINEAMENTS IN CENTRAL NEVADA 119° 118u FIGURE 3. — Raised-relief map of eastern California and western Nevada showing parts of the Warm Springs, Pancake Range, and direction of relative movement along faults; dashes show traces of proposed lineaments. Base from US. Geological east-trending faults at Blair Junction and in the Volcanic Hills that were mapped by Albers and Stewart (1972) and would appr0ximately coincide with the south edge of the Adobe Hills volcanic center. Thus, most currently available evidence favors option 1, which implies no large offset by Walker Lane structures. The lineament shown on plate 1 is drawn to coincide approximately with the southern margin of the broad magnetic zone (fig. 5). If the Walker Lane faults have large strike-slip displacements north and south of this latitude (38°), then the possibility exists that the lane itself is offset along this latitude, presumably as a result of large strike-slip displacements along the projectién ’of the Warm Springs lineament. However, as will be explained later, this does not seem to be the case, because both the Death Valley—Furnace Creek fault zone (fig. 1) and the faults in the vicinity of Soda Spring Valley (pl. 1) appear to die out or splay out toward the proposed lineament, rather than end abruptly against it. Therefore, we do not concur with Albers and Stewart (1972, p. 42—44, fig. 9) that the Walker Lane is offset right-laterally at this latitude. PANCAKE RANGE LINEAMENT This lineament (fig. 1, No. 3) is partly defined by range and valley termini and shows as a distinct line on the raised-relief topographic map (fig. 3) and on Landsat photography. (See Aerial Photographers of Nevada, 1973.) In the Moores Station and Portu- guese Mountain quadrangles, it coincides with a marked magnetic interruption (fig. 6). Several lines of evidence suggest that the lineament also coincides with deep-seated structural boundaries. As will be discussed on later pages, the lineament probably extends east of the Pancake Range as far as Currant, Nev. (fig. 1), and west of the P1lot Mountalns as far as Mono Valley in California. The lineament is des- cribed from east to west. PANCAKE RANGE, MOORES STATION AREA, AND MOREY PEAK The lineament, on the basis of both geologic and magnetic data (fig. 6, pl. 1) strikes about due west from Wood Canyon in the Pancake Range (pl. 1) through the Moores Station quadrangle (Ekren and others, 1973) to the southeast flank of Morey Peak. At PANCAKE RANGE LINEAMENT 7 Pritchards Station lineaments. Four strike-slip faults in the Walker Lane east of Walker Lake are also shown. Arrows show Survey Walker Lake, 1957—69, and Tonopah, 1956—71,1° by 2° topographic quadrangles, scale 1:250,000. Wood Canyon a major east-trending fault zone places Mississippian and Upper Devonian rocks on the north against a block containing older Paleozoic rocks (Ordovician through Devonian) on the south (fig. 7). The most striking feature, however, is not the obvious stratigraphic throw across the fault zone but the marked difference in tectonic style across the zone. South of Wood Canyon the rocks are broken into a mosaic of small blocks by abundant normal faults, only a few of which are shown in figure 7. North of Wood Canyon, in contrast, few normal faults occur. Quinlivan, Rogers, and Dodge (1974; W. D. Quinlivan, oral commun., 1974) favored a strike-slip interpretation for the fault zone in order to account for the contrasting tectonic styles north and south of Wood Canyon. The strike-slip faulting occurred prior to the development of the north- trending horst that forms the backbone of the range in this area. East-trending faults are absent from volcanic rocks of late Oligocene and early Miocene age that crop out east and west of Wood Canyon. However, the east-trending aeromagnetic discon- tinuity (fig. 6) projects in both directions from Wood 117° 113;, Canyon across areas occupied by these volcanic rocks. The discontinuity is defined by terminations or reductions in amplitude of various magnetic anomalies. These anomalies and their associated discontinuity perhaps could be partly induced by nearly east-west contacts between surface volcanic rocks or between these rocks and alluvium for 8-13 miles (5—8 km) east and west of Wood Canyon (fig. 7). However, no changes in rock type or character are present in volcanic rocks of late Oligocene age exposed across the discontinuity west of Wood C anyon in much of the western half of the Portuguese Mountain quadrangle. We believe, therefore, that the discontinuity must largely reflect the influence of buried igneous rocks, either older volcanics or intrusives, the distribution of which has been topographically or structurally controlled by a prominent east-trending feature continuous with the fault at Wood Canyon. The Wood Canyon fault and its buried lateral extensions in the Pancake Range thus appear to have been inactive since at least late Oligocene time, unless strike-slip movements at depth have not affected the exposed volcanic rocks. 38° EAST-TRENDING STRUCTURAL LINEAMENTS IN CENTRAL NEVADA 116°15’ m 135“ I a \ '2,« g/L—% \ \\\ 2)) if: d ‘ ,9! /. . , 5/ try-‘E‘YV J; . \V//fi ‘ "s45 / / l A \q \j'. V m ‘. ‘U \ r1] / 43‘:le _ l l 10 MILES ' Em _ Lu 7 ,‘LJ ) 1 § fi Jr- \ l £ l 10 KILOMETRES a 6R: {K/ ewes? K K \ ‘ffifi H l)! l a“ m- mg 3 E, 2E5 g o_ ‘*\‘ sienna ,1 _ x ‘ U l ”WEE-I wily!!! ; ‘ _ mad/4 ( K ’ , ,3 24"‘% < w , 5335‘“ k¢11E:-:$Z§KZ:$X mi . 5.; , 7/5‘ ~ , 2 i e ,.w E45 , . = 37%;; $2: ,_ _r: . . ,/\‘2—: l »—-.‘.’ :e g l I I , x 30in We EXPLANATION 0 Check point ——_— Flight path — Showing number, location, and spacing 0 Magnetic high I Magnetic low intensity magnetic field of the earth in g mmas relative —ssoo— Magnetic contours — Showing tota of data 0 indicate closed y, dashed where y to arbitrary datum. Hachured H areas of lower magnetic intensi data are incomplete. Contour ‘nterval 20 gammas FIGURE 4. — Aeromagnetic map of the Warm Springs region showing magnetic discontinuity or interruption along the eastern part, of Warm Springs lineament. From US. Geological Survey (1968). PANCAKE RANGE LINEAMENT 9 A major east-trending fault in the Moores Sta- tion quadrangle occurs at about lat. 38°37’ within the Williams Ridge—Hot Creek Valley cauldron complex (Ekren and others, 1973) (pl. 1), essentially on the magnetic discontinuity, and displaces volcanic rocks of late Oligocene and early Miocene age. The fault could be a splay or an en echelon segment of the zone causing the aeromagnetic discontinuity. The aeromagnetic discontinuity ex- tends along the southeast and south boundary of the Morey Peak resurged mass. There the anomaly is due to the southward termination of the welded tuffs of Morey Peak against Paleozoic rocks. This boundary trends nearly east-west, and, although it is undoubt- edly an old cauldron wall, it is also associated, as at Wood Canyon, with a significant north-to-south change in Paleozoic rocks. Mapping by H. W. Dodge, Jr. and W. J. Carr (oral commun., 1974) indicates that several facies and thickness changes are apparent in Paleozoic rocks that are exposed north and south of Morey Peak. The most striking of these changes is the drastic thinning of rocks of Devils Gate Lime- stone age (Middle and Late Devonian) from 2,000 feet (610 111) north of Morey Peak to only about 100 feet (30 m) in Hot Creek Canyon, a few miles south of Morey Peak. This thinning appears to be most easily explained by strike-slip faulting, but more regional data are necessary to determine the sense and amount of displacement. MOREY PEAK TO TOIYABE RANGE Very little detailed geologic mapping has been done in the ranges west of Morey Peak (pl. 1), and some east-west structures may have been overlooked; however, the topographic and photographic expres- sion of the lineament is locally pronounced. West of Morey Peak the lineament coincides with the south ends of Little Fish Lake Valley and Monitor Valley and the north ends of Stone Cabin and Ralston Valleys and Willow Creek and parallels a major east- trending fault in the Monitor Range west of Little Fish Lake Valley. R. E. Anderson (written commun., 1968) mapped this area in reconnaissance and considered that the broad bulbous part of the Monitor Range south of the lineament was a resurged segment of a large cauldron complex (pl. 1). If this is the case, the lineament coincides with the northern boundary of the cauldron segment, which appears to be outlined along half its perimeter by rhyolite domes and intrusive masses. Near the south end of the Toquima Range the lin- eament has no topographic expression, but it shows as a distinct east-trending line on Landsat photography. The line appears to be due principally to contrasting colors between Paleozoic rocks to the south at Manhattan and volcanic rocks to the north. This contact zone trends nearly east-west (Kleinhampl and Ziony, 1967). Although mapped as a depositional contact rather than a fault, the contact must at least express a prevolcanic east-trending topographic high. The lineament forms the south terminus of the Toiyabe Range (fig. 3, pl. 1), where only one east- trending fault has been mapped (pl. 1) but where other buried east-trending faults undoubtedly occur that control the range terminus. F. J. Kleinhampl and J. I. Ziony (oral commun., 1966) regard the southern domical part of the Toiyabe Range as a major center of ash-flow tuff volcanism, perhaps, in part, a resurged cauldron. TOIYABE RANGE TO PILOT MOUNTAINS Where the lineament projects across Cedar Mountain the range doglegs in a left-lateral sense (fig. 3, pl. 1); and the lineament separates a broad high range segment to the north from two narrow, topographically subdued segments to the south. In the vicinity of the line, both the pre—Tertiary and Tertiary rocks strike principally easterly. (Note the east-trending outcrop patterns on plate 1.) West of Cedar Mountain, the lineament forms the east-trending topographic low between the Pilot Mountains and the Gabbs Valley Range (fig. 3; Ross, 1961). The pass is of both structural and erosional origin. Tertiary volcanic rocks, principally in- termediate lavas but including a narrow zone of brecciated welded tuffs (not shown on plate 1), are faulted down in the pass against Mesozoic sedimen- tary rocks that make up the high rugged Pilot Mountains. Additional evidence of an east-trending structure between the Pilot Mountains and Gabbs Valley Range is found at the intersection of the lineament with the northwest-trending fault in Soda Spring Valley (pl. 1), which may be offset about 1 mile (2 km) by the lineament. PILOT MOUNTAINS TO MONO LAKE On both Landsat photography and the raised- relief map (fig. 3), the lineament appears to project west-southwestward from the Pilot Mountains across Soda Spring Valley and the Garfield Hills, along the northern boundary of the Excelsior Mountains, and thence through the Anchorite Hills to the north side of Mono Valley. If this is the case, the Pancake Range lineament merges with the north boundary of the broad Warm Springs lineament suggested by the magnetic data (fig. 5). This topographic and photographic lineament coincides with the northern part of a wide zone of west- southwest—trending geologic structure (pl. 1). For example, Gilbert and others (1968) have mapped 10 EAST-TRENDING STRUCTURAL LINEAMENTS IN CENTRAL NEVADA 30' We” 9 ‘ " i > its? 7 Lthis l :l mu MOUNTAIV' \ “9m ' .1 ‘ cuss momeA / l/I23 Sawmill Meadow / <5 KElTV PEAK ~ ,. . \’ s "n: \ \‘ ’ U"? ’ N x #ACKOUMMNQUxJ§-/ “cu at"); . “L. L 741} Vi, , , a) [lg 2: AW EXPLANATION 2200 Magnetic contours — Showing total intensity magnetic field of the earth in gammas relative to arbitrary datum. Hachured to indicate closed areas of lower magnetic intensity. Contour intervals are 20 and 100 gammas 7 Flight path — Showing location and spacing of data FIGURE 5. — Aeromagnetic map of the region between Lone Mountain and Mono Lake showing the westward projection of the Warm Springs lineament (patterned). From parts of three aeromagnetic maps (U.S. Geological Survey, 1971a, 1971b, 19710). colinear faults trending about S. 60° W. in the Anchorite Hills (pl. 1) east of Mono Lake, which they feel may have had as much as 985 feet (300 m) of left- lateral slip in the last 2.5 m.y. Along the north flank of the Excelsior Mountains, a prominent fault occurs that extends for 11 miles (17.7 km) on a trend of S. 75° W. (pl. 1). This fault has been studied recently by R. C. Bucknam (unpub. data, 1974), who determined that the fault forms rifts in basaltic andesite lava flows that have been dated at 5.6 m.y. (million years) (R. F. Marvin, written commun., 1974) and forms scarps in alluvium of probable Quaternary age. However, the occurrence of mylonite of prebasaltic andesite age in granitic rock adjacent to the fault indicates that the fault has been active for a long time. Other than the evidence of vertical movement shown by scarps in the alluvium, direct evidence of the sense of move- ment on this fault is lacking, but its relatively straight trace and the fact that no consistent upthrown side exists suggest that it is principally a strike—slip fault. Additional easterly and northeaster- ly trending fault segments and topographic lineaments (pl. 1) that probably are also strike-slip faults occur within and on both sides of the Excelsior Mountains (Ferguson and others, 1954). Correlation of the lineament with geologic features east of Garfield Flat in the Garfield Hills (pl. 1) is equivocal. The lineament, as defined, coincides with an east- trending thrust fault mapped by Ferguson, Muller and Cathcart’(1954). 11 PRITCHARDS STATION LINEAMENT ., ‘ é,“ A v \ , \\\\\s\\>\‘ - ‘\ _\\\\‘ S <\§\\\\\\§\\\\\: “\Ws‘xfi w , \ .-grg\M\{\\\\\\~ , \ \\ 7 7 EIKO‘ VlNi :' \\_‘\ ,\\ t , V, -‘ -- m- — ea , \ \7 HRR . _‘ _ \\ \®\\‘ 4“) . 0 . kw" AKA \ I “\ _ i A ., x (4.: 4' 0 )y ‘ me: k'\\ \ ‘ ( " "5‘" A: "\ ' ' 37°49 o 5 10 15MILEs l . . I ll 1 0 5 10 15 KILOMETRES Epicenters deteTIYiined’by Alan Ryall and K. F. Priestly (written commun., 1974) using a dense seismograph network in the Excelsior Mountains area do not show well-defined alinements; however, composite focal mechanisms determined for the area by Ryall and Priestly and by Gumper and Scholz (1971) include an east-trending or northeast-trending fault plane having a component of left-lateral strike- slip displacement. PROBABLE EXTENSION OF LINEAMENT EAST OF PANCAKE RANGE We infer that the lineament extends east of the Pancake Range to coincide with faults in the Grant and Horse Ranges that occur about 7 miles (11 km) southeast of Currant (fig. 1). We suggest that the lineament there reflects several en echelon faults, including the following faults of Moores, Scott, and Lumsden (1968) (from north to south): the Ragged Ridge—Stone Cabin fault zone, the Blind Spring fault zone, and the Red Ridge fault zone. The overall strike- slip displacement along this system is left-lateral and may be as much as 5 miles (8 km). The Blind Spring fault, however, is inferred by Moores, Scott, and Lumsden (1968) to have right-lateral displacement, and this inference seems soundly based. Nearly the entire area mapped by Moores, Scott, and Lumsden (1968) appears to be strongly affected by the east- trending, strike-slip fault zones, including, in addi- tion to the faults named above, the Currant Summit fault zone, which we consider to be an eastward continuation of the Pritchards Station lineament. PRITCHARDS STATION LINEAMENT This feature (fig. 1, No. 4) shows as a marked magnetic discontinuity in the Hot Creek Valley region (fig. 6), where it has been described in considerable detail (Ekren, Bath, and others, 1974); however, its expression west and east of the Hot Creek Valley region has not been described and will be briefly outlined here. 12 EAST-TRENDING STRUCTURAL LINEAMENTS IN CENTRAL NEVADA 116°00’ 115°45' m7 MTG—.fi i ( 1-? g .l, g a, 6) _ i g! . > i I . .0 v- a MQOVRESASIAIION . \/3 g ‘.. .m- r — \ , — — r .4 n \‘f a— L R‘ANGE K. LINEAMEN". " ' ' ‘° l _ _ __ - “w \ n J MEL _ m e cf? videos we? — _ '\ v .9 i \t be NY \. Q g 0 r -~ w a -,._ » /\ Q‘ a . a \_ u. _ _ i _ ..,ii i» t- _ i “ APT ————— ‘3 3}“ 4%?v...\_ fl 4.“: “ ‘ QV' GE) 1 , u . h _ g - f s 6 U ”if # 0 i x '" [\ i (l) 5 10 MILES i i J i . 0 5 10 KILOMETRES EXPLANATION fl: Magnetic contours — Showing total intensity ——— Flight path — showing number, location, and spacing of magnetic field of the earth in gammas relative data to arbitrary datum. Hachured to indicate closed 0 Magnetic high areas of lower magnetic intensity, dashed where ‘ data are incomplete. Contour interval 20 gammas I Magnetic 10W 0 Check point FIGURE 6. — Aeromagnetic map of the Hot Creek Valley region showing the Pancake Range and Pritchards Station lineaments. The northern discontinuity is caused by the presence north of the line of thick andesitic lavas with normal polarity. These lavas are absent south of the line. The southern discontinuity cannot be explained by outcrop patterns of volcanic rocks, but it coincides locally with major east-west fault zones. From US. Geological Survey (1968). The eastern part of the Pritchards Station lin- south coincides exactly with any of the features eament is fairly close to a marked east-trending described by Zietz and others (1969). lineament visible on the high-altitude aeromagnetic EXPRESSION WEST OF THE MONITOR RANGE map 0f Zietz and others (1969), blit neither this The Pritchards Station lineament is inferred to lineament nor the Pancake Range lineament to the pass due west of Tulle Creek in the Monitor Range PRITCHARDS STATION LINEAMENT 13 38°371/2/ RAILROAD VALLEY 0 3 MILES O 3 KILOMETRES EXPLANATION Crysta|»poor quartz Iatite tuff Quartz latite lava Tuff of Pritchards Station TERTIARY . Stone Cabin Formation — Welded tuff Tov Older nonwelded tuff and quartz-free rhyolite lava _: Principally Mississippian and Upper and Middle Devoni— an rocks 3 Lower Devonian, Silurian, and Ordovician rocks Contact —‘.;—-1—- Faults—Bar and ball on downthrown side. Arrows show direction of relative movement /5 ——|— Strike and dip of bedding in sedimentary rocks 20 —A— Strike and dip of primary foliation in volcanic rocks FIGURE 7.——Genera1ized geologic map of the Wood Canyon area, northern Pancake Range, showing contrasting structure and stratigraphy north and south of Wood Canyon. Modified from Quinlivan, Rogers, and Dodge (1974). and projects toward drill hole UCE—16 (fig. 3), which was drilled for the US. Atomic Energy Commission (now US. Energy Research and Development Administration) in Monitor Valley. This drill hole encountered crystal-rich rhyolite at a depth of 1,471 feet (448.4 m) and bottomed in rhyolite at a depth of 4,353 feet (1,326.8 m). Rhyolite is absent in the immediately adjacent ranges and possibly is localized in Monitor Valley along the Pritchards Station lineament. The lineament crosses the To- quima Range just north of Mount Jefferson at about 38°50’ N. latitude, where there is a change in the strike of the range (from north to slightly east of north) and where the range abruptly narrows. Although no east-trending geologic structures have been mapped in this part of the range (Kleinhampl and Ziony, 1967), Mount Jefferson, a major volcanic center and possibly a resurged caldera (F. J. Kleinhampl, oral commun., 1966; D. L. Hoover, written commun., 1967), is tangent on the north to the projection of the lineament (fig. 3). In the Toiyabe Range to the west, the lineament coincides with an abrupt narrowing, a slight change in strike of the range, and an east-trending fault at North Twin River (fig. 3). This fault has about 2 miles (3 km) of left-lateral displacement according to Ferguson and Cathcart (1954). This area, however, has recently been studied by R. C. Speed (oral commun., 1975), who believes that the fault at North Twin River is the northern boundary of a caldera and is not a strike- slip fault. If this is the case, the lineament would be tangential to the north boundary of the caldera. In the Shoshone Range, due west of the fault at North Twin River in the Toiyabe Range, an east- trending fault is present at East and West Union Canyons (fig. 3). Very large normal-fault displace- ment or about 1 mile (2 km) of left-lateral displace- ment can be inferred along this fault (Ferguson and Muller, 1949). Tertiary strata in the Shoshone Range do not appear to be displaced by this fault. Examina- tion of the Landsat photographs suggests that the lineament projects west into the Paradise Range, where it bends northwestward, and thence into Lodi Valley (fig. 3). There are no obvious alinements of topographic or photographic features west of this area, but Bingler (1971) described an alinement of east-trending faults, small intrusives, and major metallic ore deposits extending west of Rawhide into the Mountainview district in the northern Wassuk Range (fig. 1). Possibly, therefore, the Pritchards Station lineament is continuous with the Yerington- Rawhide lineament of Bingler (1971). EXTENSION OF LINEAMENT IN RANGES EAST OF PRITCHARDS STATION On the basis of a marked aeromagnetic anomaly (fig. 6), we infer that the lineament continues eastward across the Pancake Range just north of 38°45’ latitude. No important east-striking faults have been mapped in this area, but the lineament in the Pancake Range separates a broad area of pre- Tertiary outcrops to the south from a broad area of Tertiary volcanic rocks to the north. The volcanic rocks north of the lineament include thick sections of andesite lavas and the Windous Butte Formation (welded tuff). The lineament projects east of the Pancake Range and terminates the White Pine and Horse Ranges northeast of Currant (fig. 1). As mentioned previously, we infer that it coincides there with a major fault zone called the Currant Summit fault zone by Moores, Scott, and Lumsden (1968), who 14 EAST-TRENDING STRUCTURAL LINEAMENTS IN CENTRAL NEVADA believed that it is (1) a wrench fault having ap- proximately 8,000 feet (2,400 m) of left-lateral displacement; or (2) a structural discontinuity separating two areas that developed differently in response to different stress configurations. The Currant Summit fault appears to be the easternmost obvious expression of the Pritchards Station lineament. There are no major photographic or topographic lines along the trend of the Currant Summit fault (38°48’). Widely spaced left-lateral faults span a considerable area both to the north and south of 39° latitude (Brokaw and Shawe, 1965; AL. Brokaw, oral commun., 1974) in the Egan Range, which is east of the White Pine Range, but they are probably best interpreted as conjugate shears that formed simultaneously with right-lateral strike-slip movements (Shawe, 1965). These left-lateral faults are possibly not controlled by preexisting zones of weakness analogous to the lineaments described herein. INTERSECTION OF THE LINEAMENTS WITH THE WALKER LANE We have discussed the probable projections of the Pancake Range and the Warm Springs lineaments from central Nevada into western Nevada and California without consideration of their relations with the Walker Lane. We have done this because the lineaments reasonably may be projected across the lane without obvious offsets. Such a projection appears to be justified because there is little indication that any of the Walker Lane right-lateral strike-slip faults in the vicinity of the two lineaments have sufficiently large dis- placements to cause obvious offsets of the lineaments. For example, recent mapping by Ekren R. F. Hardyman, and F. M. Byers, Jr. (unpub. data, 1974), in the Gillis and Gabbs Valley Ranges north of Soda Spring Valley (just north of fig. 4 and within the Walker Lane as defined by Locke and others, 1940) shows that four northwest-trending strike-slip faults are present there (fig. 3), each of which has at least 1 mile (2km), and probably as much as 4—10 miles (6-16 km), of right-lateral displacement. The two westerly faults splay and die out abruptly in the Garfield Hills north of the projection of the lineament (fig. 3; pl. 1). The other two faults may die out in a similar manner, but this has not yet been conclusively determined. Nielsen (1965) theorized that one of the latter faults forms the east boundary of Soda Spring Valley (fig. 3; pl. 1), Where it has a right-lateral displacement of possibly as much as 10 miles (16 km). If Nielsen (1965) is correct, then this fault in the Walker Lane should displace the lineament across Soda Spring Valley if this fault is younger than the lineament. Studies by R. C. Speed that are still in progress (oral commun., 1974), however, show that this much displacement is unlikely. Speed suggests that the pre- Tertiary rocks across Soda Spring Valley are not displaced right laterally more than a few miles. For example, the Jurassic Dunlap Formation (pl. 1) crops out in a broad arcuate belt centered on Mina in Soda Spring Valley, and this belt is not significantly offset across the valley. The Dunlap belt is considered to lie within a major deformational feature resulting from vertical rather than lateral propagation (Wetterauer, 1974). In contrast, however, the Walker Lane, as conceived of by Albers (1967), is a broad zone characterized by arcuate mountain ranges or “oroflexes,” which he considered to result from right- lateral deformation. Albers (1967) and RC. Speed and R. H.Wetterauer (oral commun., 1974) considered that the arcuate deformation (whether a result of vertical or lateral forces) is Mesozoic in age. The fourth fault, which Nielsen termed the Bat- les Well fault (pl. 1), appears to project into the Pilot Mountains from the Gabbs Valley Range. Nielsen considered that this fault has at least 1 mile (2 km) of right-lateral displacement where it enters the Pilot Mountains. Recent mapping by F. M. Byers, Jr. (unpub. data, 1975), suggests that the main splay of this fault projects into Stewart Valley several miles north of the lineament and that there it has at least 2 miles (3 km) of right-lateral displacement (pl. 1). This displacement, together with the displace- ment of the fault at Battles Well, however, is not sufficient to offset the topographically low area that separates the Gabbs Valley Range from the Pilot Mountains. Similarly, in the vicinity of Tonopah, Blair J unc- tion, and Boundary Peak, no large strike-slip dis- placements of Tertiary age are indicated along the Walker Lane (pl. 1). The Death Valley—Furnace Creek fault zone, which we regard as part of the broad Walker Lane system, has large displacement farther south but dies out northward before the Warm Springs lineament is reached. We speculate that the apparent lack of obvious offsets on either the Walker Lane or the lineaments in the area between Tonopah and Hawthorne could be accounted for by one or a combination of the following: (1) The Walker Lane is segmented in this area by conjugate shears (Shawe, 1965) that coincide, in part, with the lineaments; (2) some complex interaction takes place at the intersections of the structures, possibly in a manner similar to the intersection of the San Andreas fault and the Garlock fault in California or to the intersection of the San Andreas and the Mendocino escarpment in the oceanic crust; (3) fractures along the lineaments are REFERENCES CITED 15 younger than most of the northwest-trending strike- slip movements along the Walker Lane and, therefore, give rise to topographic lines that cross the lane without offset. Certainly some of the east- northeast-trending fractures are very young; for example, faults along the north and south flanks of the Excelsior Mountains that displace basaltic andesite dated at 5.6 my and alluvium of probable Pleistocene age. Significantly, seismicity is currently concentrated in an east-northeast—trending belt between the two lineaments (Gumper and Scholz, 1971). When more facts are in hand, it probably can be demonstrated that the two systems in the Walker Lane region tend to offset one another and are thus part of a conjugate system. In any case, the structural block roughly bounded by the Pancake Range lineament on the north and the Warm Springs lineament on the south did not favor throughgoing strike-slip faults of the northwest-trending Walker Lane system. SUMMARY AND DISCUSSION We believe the evidence presented in this report shows that an important series of east-northeast- trending structural lineaments is present in south- central Nevada. In most areas the lineaments appear to predate the Tertiary volcanism, but, locally, they have controlled the location of Cenozoic volcanic centers and faulting and probably influence the location of current seismicity. The presence of these lineaments athwart the major structural grain of the Great Basin and their possible continuity across the Walker Lane raise important questions about the tectonic framework of the entire region. It seems relatively certain that the Nevada lin- eaments are an expression of fairly old, probably pre-Oligocene, structural trends. Most of the observ- ed magnetic anomalies can reasonably be attributed to the deposition of volcanic rocks against easterly trending topographic highs, to the juxtaposition by faulting of rocks having different magnetic proper- ties, or to plutonic rocks intruded into structures within the lineament trend. The tangential associa- tion of volcanic centers with the lineaments also implies a deep-seated crustal control. The authors speculate that the apparent outward spread of volcanism from a “core” area in central Nevada (Armstrong and others, 1969) may actually have occurred in a series of 30—60-mile (50—100-km)—wide belts bounded and controlled by the lineament system described in this paper. J. H. Stewart, W. J. Moore, and Isidore Zietz (written commun., 1975) have independently reached similar conclusions regarding the control of east-trending belts of volcanic strata and intrusive masses. The lineaments and belts between them have trends that are nearly at right angles to the axes of Miocene volcanism proposed by Noble (1972). It seems possible that the general southwestward migration of volcanism with time (Noble, 1972) in the southern Great Basin may have been a progression of diapirs or mantle plumes tracking already established deep- seated structural discontinuities. The distinct tendency toward younger faulting at the west and southwest ends of the lineaments near or west of the Walker Lane agrees in general with the southwestward decrease in the age of silicic volcanism. The onset of basin and range faulting throughout the Great Basin, however, appears to have been virtually simultaneous (Ekren, Bath, and others, 1974). Whether the lineaments are partly a result of conjugate faults developed at the inception of the Walker Lane and other major northwest-trending faults in the southwestern Great Basin, or whether they owe their origin to an even more regional or even continentwide fracture system is an unresolved question. In any case, their presence should be considered in future attempts to integrate plate tectonics, local structure, and volcanism in the Great Basin. REFERENCES CITED Aerial Photographers of Nevada, 1973, Photo mosaic, State of Nevada, compiled from Earth Resources Technology Satellite (ERTS), Multispectral Scanner Imagery, height of orbit 494 miles, September 1972: Reno, Nevada Univ., Remote Sensing Lab., Renewable Resources Center, scale 1:1,000,000. Affleck, James, 1970, Definition of regional structures by magnetics, [Chapter] 1, in Johnson, Helgi, and Smith, B.L., eds., The megatectonics of continents and oceans: New Brunswick, N.J., Rutgers Univ. Press, p. 3—11. Albers, J .P., 1967, Belt of sigmoidal bending and right-lateral faulting in the western Great Basin: Geol. Soc. America Bull., v. 78, no. 2, p. 143—156. Albers, J .P., and Stewart, J .H., 1972, Geology and mineral deposits of Esmeralda County, Nevada: Nevada Bur. Mines and Geology Bull. 78, 80 p. Anderson, RE, 1973, Large-magnitude late Tertiary strike-slip faulting north of Lake Mead, Nevada: US. Geol. Survey Prof. Paper 794, 18 p. [1974]. Armstrong, R.L., Ekren, E.B., McKee, E.H., and Noble, D.C., 1969, Space-time relations of Cenozoic silicic volcanism in the Great Basin of the western United States: Am. J our. Sci., v. 267, no. 4, p. 478—490. Bingler, EC, 1971, Major east-west lineament in west—central Nevada: Geol. Soc. America Abs. with Programs, v. 3, no. 2, p. 83. Bonham, H.F., Jr., and Garside, L.J., 1974, Tonopah mining district and vicinity, in Guidebook to the geology of four Tertiary volcanic centers in central Nevada: Nevada Bur. Mines and Geology Rept. 19, p. 42—48. Brokaw, AL, and Shawe, DR, 1965, Geologic map and sections of the Ely 3 SW quadrangle, White Pine County, Nevada: US. Geol. Survey Misc. Geol. Inv. Map I—449. 16 EAST-TRENDING STRUCTURAL LINEAMENTS IN CENTRAL NEVADA Burke, D.B., and McKee, E.H., 1973, Mid-Cenozoic volcano- tectonic features in central Nevada: Geol. Soc. America Abs. with Programs, v. 5, no. 1, p. 18. Cook, E.F., 1965, Stratigraphy of Tertiary volcanic rocks in eastern Nevada: Nevada Bur. Mines Rept. 11, 61 p. Cook, K.L., and Montgomery, J .R., 1974, Crustal structure and east-west transverse structural trends in eastern Basin and Range province as indicated by gravity data: Geol. Soc. America Abs. with Programs, v. 6, no. 3, p. 158. Department of Defense, 1975, Bouguer gravity map of the Caliente 2O quadrangle, Nevada: Dept. Defense, Gravity Services Div., Defense Mapping Agency, Aerospace Center, St. Louis Air Force Station, MO 63125, scale, 1:250,000. Ekren, E.B., Anderson, R.E., Rogers, CL, and Noble, D.C., 1971, Geology of northern Nellis Air Force Base Bombing and Gunnery Range, Nye County, Nevada: U.S. Geol. Survey Prof. Paper 651, 91 p. ' Ekren, E.B., Bath, G.D., Dixon, G.L., Healey, D.L., and Quinlivan, W.D., 1974, Tertiary history of Little Fish Lake Valley, Nye County, Nevada, and implications as to the origin of the Great Basin: U.S. Geol. Survey Jour. Research, v. 2, no. 1, p.105r—118. Ekren, E.B., Hinrichs, E.N., Quinlivan, W.D., and Hoover, D.L., 1973, Geologic map of the Moores Station quadrangle, Nye County, Nevada: U.S. Geol. Survey Misc. Geol. Inv. Map I—756 [1974]. Ekren, E.B., Quinlivan, W.D., and Marvin, R.F., 1974, Pre—Basin and Range strike-slip faulting in the Reveille and Hot Creek Ranges, central Nevada: Geol. Soc. America Abs. with Programs, v. 6, no. 3, p. 172. Ekren, E.B., Rogers, CL, and Dixon, G.L., 1973, Geologic and Bouguer gravity map of the Reveille quadrangle, Nye County, Nevada: U.S. Geol. Survey Misc. Geol. Inv. Map I—806[1974]. Ferguson, H.G., and Cathcart, S.H., 1954, Geology of the Round Mountain quadrangle, Nevada: U.S. Geol. Survey Geol. Quad. Map GQ-40. Ferguson, H.G., and Muller, S.W., 1949, Structural geology of the Hawthorne and Tonopah quadrangles, Nevada: U.S. Geol. Survey Prof. Paper 216, 55 p. Ferguson, H.G., Muller, S.W., and Cathcart, S.H., 1954, Geology of the Mina quadrangle, Nevada: U.S. Geol. Survey Geol. Quad. Map GQ—45. Gilbert, C.M., Christensen, M.N., Al-Rawi, Yehya, and Lajoie, KR, 1968, Structural and volcanic history of Mono Basin, California-Nevada, in Studies in volcanology — A memoir in honor of Howel Williams: Geol. Soc. America Mem. 116, p. 275—329. Gumper, F.J ., and Scholz, Christopher, 1971, Microseismicity and tectonics of the Nevada Seismic Zone. Seismol. Soc. America Bull., v. 61, no. 5, p. 1413—1432. King, P. B., 1970, Tectonics and geophysics of eastern North America, [Chapter] 5, in Johnson, Helgi, and Smith, B.L., eds., The megatectonics of continents and oceans: New Brunswick, N.J., Rutgers Univ. Press, p. 74—112. Kleinhampl, F.J ., and Ziony, J .I., 1967, Preliminary geologic map of northern Nye County, Nevada: U.S. Geol. Survey open-file map, scale 1:200,000. ‘ Locke, Augustus, Billingsley, RR, and Mayo, E.B., 1940, Sierra Nevada tectonic patterns: Geol. Soc. America Bull., v. 51, no. 4, p. 513—540. Moores, E.M., Scott, R.B., and Lumsden, W.W., 1968, Tertiary tectonics of the White Pine—Grant Range region, east-central Nevada, and some regional implications: Geol. Soc. America Bull., V. 79, no. 12, p. 1703—1726. Nielsen, R.L., 1965, Right-lateral strike—slip faulting in the Walker Lane, west-central Nevada: Geol. Soc. America Bull., v. 76, no. 11, p. 1301—1308. Noble, D.C., 1972, Some observations on the Cenozoic volcano- tectonic evolution of the Great Basin, western United States: Earth and Planetary Sci. Letters, v. 17, no. 1, p. 142—150. Noble, D.C., and McKee, E.H., 1972, Description and K-Ar ages of volcanic units of the Caliente volcanic field, Lincoln County, Nevada, and Washington County, Utah: Isochron/ West, no. 5 p. 17—24. Noble, D.C., McKee, E.H., Hedge, GE, and Blank, H.R., Jr., 1968, Reconnaissance of the Caliente depression, Lincoln County, Nevada, in Abstracts for 1967: Geol. Soc. America Spec. Paper 115, p. 435—436. Quinlivan, W.D., Rogers, C.L., and Dodge, H.W., Jr., 1974, Geologicmap of the Portuguese Mountain quadrangle, Nye County, Nevada: U.S. Geol. Survey Misc. Inv. Ser. Map I—804. Ross, D.C., 1961, Geology and mineral deposits of Mineral County, Nevada: Nevada Bur. Mines Bull. 58, 98 p. Shawe, DR, 1965, Strikeslip control of Basin-Range structure indicated by historical faults in western Nevada: Geol. Soc. America Bull., v. 76, no. 12, p. 1361—1377. Slemmons, D.B., 1967, Pliocene and Quaternary crustal movements of the Basin-and-Range province, USA, in Sea level changes and crustal movements of the Pacific during the Pliocene and post-Pliocene time — Pacific Sci. Cong, 11th. Tokyo 1966, Symposium 19: Osaka City Univ. J our. Geoscien- ces, v. 10, art. 1, p. 91—103. Smith, R.B., and Sbar, M.L., 1974, Contemporary tectonics and seismicity of the western United States with emphasis on the Intermountain seismic belt: Geol. Soc. America Bull.,v. 85, no. 8, p. 1205—1218. Stewart, J .H., and Carlson, J.E., compilers, 1974, Preliminary geologic map of Nevada: U.S. Geol. Survey Misc. Field Studies Map MF— 609. Tschanz, C.M., and Pampeyan, E.H., 1970, Geology and mineral deposits of Lincoln County, Nevada: Nevada Bur. Mines Bull. 73, 187 p. U.S. Geological Survey, 1968, Aeromagnetic map of the Hot Creek Range region, south-central Nevada: U.S. Geol. Survey Geophys. Inv. Map GP—637, scale 1:250,000. 1971a, Aeromagnetic map Qf parts of the Walker Lake, Reno, Chico, and Sacramento 1° by 2° quadrangles, Nevada- California: U.S. Geol. Survey Geophys. Inv. Map GP—‘751, scale 1:250,000. 1971b, Aeromagnetic map of parts of the Tonopah and Millet 10 by 20 quadrangles, Nevada: U.S. Geol. Survey Geophys. Inv. Map GP-752, scale 1:250,000. 1971c, Aeromagnetic map of parts of the Goldfield, Mariposa, and Death Valley 1° by 2° quadrangles, Nevada- California: U.S. Geol. Survey Geophys. Inv. Map GP—753, scale 1:250,000. 1973, Aeromagnetic map of southeastern part of Lund and eastern half of Caliente 10 by 20 quadrangles, Nevada: U.S. Geol. Survey open-file map, scale 1:250,000. Wetterauer, R. H., 197 4, Structural analysis of theJ urassic Dunlap Formation, western Nevada: Geol. Soc. America Abs. with Programs, v. 6, no. 3, p. 275. Zietz, Isidore, Bateman, P.C., Case, J.E., Crittenden, M.D., Jr., Griscom, Andrew, King, E.R., Roberts, R.J., and Lorentzen, GR, 1969, Aeromagnetic investigation of crustal structure for a strip across the Western United States: Geol. Soc. America Bull., v. 80, n0. 9, p. 1703—1714. Y} U.S. GOVERNMENT PRINTING OFFICE 1976-777-034/25 UNITED STATES DEPARTMENT OF INTERIOR GEOLOGICAL SURVEY Little Pilot EY QTa K" m M‘ It”? ‘ ‘ “12‘ re / / fl . "(i' VJLCre / i / l”V/ALL , e . Ev I , “Ll“ /’ ‘3‘“ Wt DEC 20 «1976 S. D. Physical, Chemical, and Biological Aspects of Subsurface Organic Waste Injection near Wilmington, North Carolina By] A. LEENHEER, R. L. MALCOLM, and W. R. WHITE GEOLOGICAL SURVEY PROFESSIONAL PAPER 987 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1976 UNITED STATES DEPARTMENT'OF THE INTERIOR THOMAS S. KLEPPE, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Leenheer, J. A. Physical, chemical, and biological aspects of subsurface organic waste injection near Wilmington, North Carolina. (Geological Survey Professional Paper 987) Supt. of Docs. no.: I 19.16:987 Bibliography: p. 1. Waste disposal in the ground—North Carolina—Wilmington region. I. Malcolm, R. L., joint author. II. White, W. R., joint author. 111. Title: Physical, chemical, and biological aspects of subsurface organic waste injection . . . IV. Series: United States Geological Survey Professional Paper 987. TD761.L43 628'.36 76—608225 For sale by the Superintendent of Documents, US. Government Printing Office Washington, DC. 20402 Stock Number 024-001-02915-4 CONTENTS Page Page English-metric equivalents IV Waste-aquifer interactions — Continued Abstract ______ 1 Site study — Continued Introduction 2 Possible flow systems associated with injection Acknowledgments 4 M'aCtL‘fltlles. l t d " :2 mm 10 0 ma s u y Hy dr°$e°l°gy ’ By H' M; Peek and R‘ C‘ Heath """""""""""""""""" 5 Laboratory waste-aiuifer reactivity studies ________________________________________ 27 Case hlstory of waste Injection 6 Introduction 27 Installatlon and operation of 1n1t1a1 well system ........................ 6 Methods and materials 27 Constructlon and operation of expanded injectlon system ........ 9 Aquifer material 27 Field sampling methods 11 Characterization of aquifer material .................................... 27 Industrial waste analysis... 12 Waste constituent analyses .................... _ 27 Organic analysis 12 Modified Hassler sleeve core holder . 28 Inorganic analysis 15 Pressurization core-testing apparatus __________________________ _ 28 Physical properties 17 Experimental design ........ 28 Hydrochemistry of native ground water ................................................ 17 Testing the pressurization core-testing apparatus ...................... 29 Waste-aquifer interactions 18 Leak testing Site study 18 Packing the Teflon sleeve with aquifer material ............. 29 Initial conditions 18 Experiment l—kinetic study of waste .............................. 30 Initial conceptual model of injected-waste reactivity Experiment 2—core solubilization study ...................................... 34 and movement 19 Experiment 3—waste saturation study ........................................ 37 Reactions observed at wells 1, 2, 3, 4, and 5 .......................... 19 Final conceptual model of waste movement and reactivity .............. 39 Reactions observed at well 9 ............................ .. Summary and conclusions __ 41 Reactions observed at wells 11, 14, and 15 ............................ 20 Selected references .. 42 ILLUSTRATIONS Page FIGURE 1 Hercules Inc. DMT Plant, Wilmington, North Carolina 3 Location of Hercules Inc., plant site 4 3 Diagram showing hydrogeologic conditions and injection-well construction for well I-7A ............................................................... 5 4 Map of waste-injection and observation wells 7 5. Monthly average injection rate 7 6. Graph of highest wellhead injection pressures 8 7 Location of wells in initial system and pressure surface, January 1969 8 8 Map of pressure surface, September 1970 9 9. Map of pressure surface and approximate limits of waste travel, October 1972 10 10. Map of pressure surface with no injection, April 1973 10 11. Construction features of observation well 14 11 12. Analytical scheme of organic waste analysis 13 13. Gas chromatogram of acetic and formic acids 13 14. Gas chromatogram and mass spectra of methylated-acid ether extract 14 15. Gas chromatogram of alkaline ether extract 14 16. Gas chromatogram of neutral, volatile, waste constituents 15 17. Initial conceptual model of injected-waste reactivity and movement 19 18. Variations in pH and residue on evaporation from samples taken during observation of waste front in wells 1 and 5.... 20 19. Variables observed during passage of waste front in well 14 21 20. Constituents measured during passage of waste front in well 11 23 21. Hypothetical areal distribution of waste at the upper and lower boundaries of the injection zone ...................................... 24 22. Probable internal circulation of ground water within well 14 .. 25 23. Comparison of number of bacteria per millilitre (as colony-forming units) in waste front (well 14) and in uncontaminated aquifer (well 1 1) 26 24. Diagram of modified Hassler sleeve core holder 28 III IV CONTENTS FIGURE 25. Schematic diagram of pressurization core-testing apparatus 28 26. Specific conductance breakthrough curve during leak-testing of Hassler sleeve core holder ................................................ 29 27. Sodium, chloride, and DOC breakthrough curves for experiment 1 (flow rate=2 mllhr) 31 28. Sodium, chloride, and DOC breakthrough curves for experiment 2 (flow rate=4 nil/hr) 31 29. Iron and silica dissolution during experiment 2 33 30. Iron and silica dissolution during experiment 1 33 31. Relative sorption of formaldehyde, acetic acid, and formic acid during experiment 2 34 32. Relative sorption of phthalic, terephthalic, and p—toluic acids during experiment 1 35 33. Hypothetical movement of injected waste within injection subzones 39 34. Final conceptual model of injected-waste reactivity and movement 39 TAB LES Page TABLE 1. Chronology of significant events during injection 6 ' 2. Injection-system well data 7 3. Average organic analysis of waste 16 4. Inorganic waste analysis 16 5. Inorganic analysis of native ground water found in aquifers at waste-injection site 17 6. Change in water composition with waste contamination 19 7. Well 14 gas analyses 21 8. Relative organic composition of injected waste found in wells 11, 14, and 15 22 9. Observation well flow-test data 24 10. Identification of isolates from well 11 26 11. Laboratory chemical data for waste-aquifer reactivity experiment 1 (flow rate=2 mI/hr) .................................................... 31 12. Laboratory chemical data for waste-aquifer reactivity experiment 2 (flow rate=4 ml/hr) .................................................... 32 13. Organic chemical data during waste-effluent monitoring of experiment 2 34 14. Organic chemical data during waste-effluent monitoring of experiment 1 35 15. Sorptive capacities of aromatic organic acids on aquifer material during experiment 2 ........................................................ 36 16. Organic and inorganic carbon analyses of fractionated and unfractionated injection-zone aquifer material .................... 36 17. Particle size analysis of injection-zone aquifer material 37 18. Fe, Al, and Mn analyses by graphite furnace technique of selected waste effluent fractions during experiment 2 .......... 37 19. Chemical data during waste effluent monitoring of experiment 3 ‘ 38 20—36. Basic-data tables 20. Organic waste analyses 46 21. Waste inorganic analyses —sample collected 1 1-7-73 46 22. Inorganic analyses of water from surficial sand aquifer 46 23. Inorganic analyses of water from 300-ft zone 46 24. Inorganic analyses of water from 500-ft zone 46 25. Inorganic analyses of water from 700-ft zone 47 26. Inorganic analyses of water from well 7 47 27. Inorganic analyses of water from well 11 48 28. Inorganic analyses of water from well 1 2 49 29. Inorganic analyses of water from well 14 48 30. Inorganic analyses of water from well 15 50 31. Inorganic analyses of water from well 16 51 32. Inorganic analyses of water from wells 2, 3, 4, and 5 51 33. Gas analyses 50 34. Organic analyses of water from well 1 1 51 35. Organic analyses of water from well 14 51 36. Organic analyses of water from well 15 51 ENGLISH-METRIC EQUIVALENTS foot (ft) = 0.3048 metre (m) inch (in) = 25.4 millimetres (mm) mile (mi) = 1.609 kilometres (km) pound per square inch (psi) = .068947 bar gallon (gal) = 3.785 litres (l) PHYSICAL, CHEMICAL, AND BIOLOGICAL ASPECTS OF SUBSURFACE ORGANIC WASTE INJECTION NEAR WILMINGTON, NORTH CAROLINA By]. A. LEENHEER, R. L. MALCOLM, and W. R. WHITE ABSTRACT From May 1968 to December 1972, an industrial organic waste was injected at rates of 100 to 200 gallons per minute (6.3 to 12.6 litres per second) into a sand, gravel, and limestone aquifer of Late Cretaceous age by Hercules Inc. located near Wilmington, North Carolina. This report presents both field and laboratory data per- taining to the physical, chemical, and biological effects of waste injection into the subsurface at this particular site, a case history of the operation, predictions of the reactions between certain organic wastes and the aquifer components, and descriptions of the effects of these reactions on the subsurface movement of the wastes. The case history documents a situation in which subsurface waste injection could not be considered a successful means of waste dis- posal. The first injection well was used only for 1 year due to exces- sive wellhead pressure build-up above the specified pressure limit of 150 pounds per square inch (10.3 bars). A second injection well drilled as a replacement operated for only 5 months before it too began to have problems with plugging. Upward leakage of waste into shallower aquifers was also detected at several wells in the injection-observation well system. The multiple problems of plug- ging, high pressures, and waste leakage suggested that the reactive nature of the waste with the aquifer into which it was injected was the primary reason for the difficulties experienced with waste injec- tion. A site study was initiated in June 1971 to investigate waste- aquifer interactions. The first stage of the study determined the hy- drogeologic conditions at the site, and characterized the industrial waste and the native ground water found in the injection zone and other aquifers. The injection zone consisted of multiple permeable zones ranging in depth from about 850 to 1,000 feet (259 to 305 metres) below land surface. In addition to the injection zone, aquifers were found near depths of 60, 300, 500, and 700 feet (18, 91, 152, and 213 metres) below land surface. The aquifers from 300 feet (91 metres) down to the injection zone were flowing artesian with the natural pressure of the injection zone being 65 feet (20 metres) above land surface at the site. The dissolved solids concentration in the native ground water increased with depth to an average value of 20,800 mg/l (milligram per litre) (two-thirds that of seawater) in the water from the injection zone. Sodium chloride was the major dissolved solid, and all of the ground water below 300-feet (91-metres) depth was slightly alkaline. Dissolved organic carbon of the industrial waste averaged 7,100 mg/l and 95 percent of the organic carbon was identified and quan- tified. The major organic waste constituents in order of decreasing abundance were acetic acid, formic acid, p-toluic acid, formaldehyde, methanol, terephthalic acid, phthalic acid, and benzoic acid. Prior to injection, the waste was neutralized with lime to pH 4 so that the major inorganic waste constituent was calcium at a concentration of 1,300 mg/ 1. The second stage of the site study involved the observation of waste-aquifer interactions at various wells as the waste arrived and passed by the wells. Water samples obtained from three observation wells located 1,500 to 2,000 feet (457 to 607 metres) from the original injection well gave evidence for biochemical waste transformations at low waste concentrations. Gas that efl‘ervesced from these water samples contained up to 54 percent methane by volume. Ferrous iron concentrations as high as 35 mg/l, hydrogen sulfide gas, and sulfide precipitates were additional indicators of biochemical reductive pro- cesses in the subsurface environment. Approximately 3,000 or- ganisms per millilitre were found in uncontaminated ground water from the injection zone whereas in waste-contaminated wells, the number increased to levels as high as 1,000,000 organisms per mil- lilitre. High concentrations of waste were found to be toxic to mi- croorganisms. Most of the organisms isolated from uncontaminated wells were facultative, aerobic genera whereas the population changed to anaerobic strains in the contaminated wells. Methanogenic bacteria of the genus Methanobacterium and genus Methanococcus were isolated in pure culture from ground-water samples in which methane was found. The relative ratios of formic acid, p-toluic acid, and terephthalic acid to acetic acid were lower in these ground-water samples than in the injected waste indicating degradation or sorption of formic, p-toluic, and terephthalic acids relative to acetic acid during the period of waste travel to these observation wells. The construction of the screened section of the observation wells allowed dilution of the waste and internal circulation of ground water so that it was impos- sible to determine quantitative waste concentrations in the various waste-receiving zones within the injection zone. Highly contaminated ground-water samples obtained from five observation wells located near (50 to 150 feet) (15 to 46 metres) the injection wells gave evidence for waste dissolution of aquifer carbon- ates and iron oxides. These samples contained carbon dioxide gas, calcium concentrations to 3,900 mg/l, and iron concentrations to 310 mg/l. Organic complexation as well as acid dissolution was suspected to be the cause for the high iron concentrations. There was no microbiological activity apparent in these wells and samples. Concurrent with and after the site study, a laboratory study was conducted in which waste was injected into cores of aquifer material obtained from the injection z‘one. The laboratory injection pressure was that of the hydrostatic pressure found in the injection zone. When a known volume of waste was injected into a core, the acidic 1 2 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA waste initially dissolved the carbonates, and sesquioxide coatings on the primary minerals as evidenced by high concentrations of iron, aluminum, silica, and manganese. Iron concentrations as high as 200 mg/l were’obtained, but this dissolved iron was eventually repre- cipitated further on in the core when the pH of the waste rose to 5.5 to 6.0 because of neutralization of the waste by aquifer carbonates . and oxides. Exhaustive leaching of a core by the acidic waste quan- titatively dissolved the aquifer carbonates and removed approxi- mately 12 percent of the extractable iron. Sorption of the waste organic compounds upon the aquifer mineral constituents was found for all the waste organic acids. Formaldehyde was not sorbed. Sorption increased as the pH of the waste decreased with the exception of phthalic acid. Phthalic acid was complexed with dissolved iron, and its concentration decreased as the pH of the waste increased because it coprecipitated with the iron hydroxide precipitate. The waste solution was supersaturated with respect to terephthalic acid, and this constituent was found to be both highly adsorbed and precipitated in the core. At the conclusion of this study, a conceptual model was con- structed which by combining the results of the field and laboratory studies, detailed the various stages of injected waste reactivity and movement in the subsurface from the injection well to the edge of the waste front. The excessive pressure build-up in the injection wells was thought to be the result of a number of factors: reprecipitation of aquifer constituents initially dissolved by the acidic waste, precipita- tion of terephthalic acid, formation of carbon dioxide and methane gases, and the relatively low permeability and porosity of the injec- tion zone. The leak problems were thought to arise from the dissolu- tion of the cement grout around the casing by the waste acids of the injection wells and certain observation wells. INTRODUCTION Injection of liquid wastes into subsurface strata is a concept in waste management which has found wide- spread use in industry only since 1960. A recent survey by Warner and Orcutt (1973) noted that only 22 waste injection wells were constructed before 1960, and by 1964, the number of injection wells had doubled. In spite of growing opposition to subsurface waste injec- tion because of its largely unknown long-term en- vironmental effects, the number of waste-injection wells has continued to increase until there are pres- ently (1973) about 278 industrial waste-injection wells which have been constructed in 24 states. Wells used to reinject brines brought to the surface during oil and gas production were not included in this survey. In 1973, chemical, petrochemical, and pharmaceutical companies accounted for 57 percent of the industrial waste-injection wells. This study is part of a nationwide effort by the US. Geological Survey to evaluate the environmental ef- fects of subsurface waste injection. The specific objec- tives of this study were to: (1) Predict the reactions and interactions between certain organic wastes and aquifer components when organic wastes are placed in the subsurface environment and (2) define the effects that physical, chemical, and biological reactions have upon the distribution and movement of organic wastes in the subsurface. In January 1971, the subsurface waste-injection sys- tem operated by Hercules Inc. near Wilmington, N.C., was selected for study. The site had several distinct advantages for this study: First, the industrial waste being injected into the subsurface contained high con- centrations of several water-soluble organic com- pounds which were liable to react and be transformed in the subsurface environment. Prior to this study, problems with an injection well pressure build-up after a period of waste injection indicated that the reactivity of the injected waste with the injection zone was an important aspect concerning the operation of this waste-injection system. Secondly, a network of 14 ob- servation wells located at various distances from the injection wells, and drilled to different depths, enabled the monitoring of waste movement and the collection of waste samples in both horizontal and vertical direc- tions from the points of waste injection. Third, the relatively shallow depth to the waste-injection zone (1,000 feet or 300 metres) facilitated chemical and mi- crobiological experimentation under the simulated pressures of the injection zone without the use of very high pressure equipment. Last but not least, excellent cooperation and support was provided by the Company and various state and federal agencies. Disadvantages of this site were that the two injec- tion wells and complex hydrogeologic nature of the injection zone made it very difficult to predict the rate and direction of waste movement. Therefore, no at- tempt was made to model the hydrological effects of waste injection. Second, because this study was in- itiated after the waste-injection system was planned, constructed, and brought into operation, there was no chance to influence the design, construction, place- ment, coring, and logging of the injection and observa- tion wells which might have increased their utility as a research facility. At the inception of this study, it was recognized that an interdisciplinary approach, which included organic chemistry, inorganic chemistry, microbiology, and hydrogeology, was necessary to understand and de- scribe the several aspects of subsurface organic waste injection. Therefore, in this report, the organic and inorganic chemistry is the work of the authors; the microbiology and the hydrogeology are based on the work of others. (See section, “Acknowledgments”.) The Hercules Inc. plant is located on the Atlantic Coastal Plain approximately 4 miles northwest of Wilmington, N.C. A photograph of the plant is shown in figure 1, and its location is shown on the map of figure 2. The product of the plant is dimethyl terephthalate (DMT), which is used in the production of synthetic polyester fibers. The organic byproducts of DMT manufacture were injected into the subsurface from May 1968 until December 1972. “| 3 .35 3333* no $3.58 30:3 .0. Z dcawfifimg 555 RED .3: $398! I A "5563 INTRODUCTION 4 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA 79°00’ 77°30, 34° 30' c um ‘5. A 3; SITE Wilmington NORTH CAROLINA f Q 93 5‘ 00‘} 33° 45' 0 10 MILES O 10 KILOMETRES NORTH CAROLINA Area of report FIGURE 2. — Location of Hercules Inc., plant site. When this study was initiated in January 1971, the first injection well had been abandoned because of low input at maximum permitted pressure, and the drill- ing of the second injection well was under way. The first step of this study was to predict the chemical and microbial reactions which were probably occurring in the waste after injection. The predictions and some of the initial findings were given in a report to the Insti- tute of Environmental Sciences (Leenheer and Mal- colm, 1973a). A sampling and analytical program based on the hypothesized reactions was instituted, and additional findings were presented before the Sec- ond International Symposium on Underground Waste Management and Artificial Recharge (Leenheer and Malcolm, 1973b). Reports on the microbiological as- pects (DiTommaso and Elkan, 1973) and a concurrent study on hydrogeological aspects (Peek and Heath, 197 3) were also presented before this symposium. Other reports which cover a period prior to and con- current with this study are a status report by the North Carolina Department of Water and Air Re- sources (1971), and an engineering report on the injec- tion well system by Black, Crow, and Eidsness, Inc. (1971). A discussion of the geology and ground-water hydrology of the Wilmington area is in a report by LeGrand (1960). ACKNOWLEDGMENTS The original interest and counsel of Raymond L. Nace, and the late Charles L. McGuinness, were bene- ficial in establishing goals and providing direction dur- ing the initial stages of this study. Leonard A. Wood provided direction during the middle and latter stages of this study. Dr. Gerald Elkan and Anthony DiTommaso con- ducted the microbiological studies at the Department of Microbiology, North Carolina State University, Raleigh. Their work was financed in part by the US. Geological Survey. Harry M. Peek, Chief, Ground Water Division, North Carolina Office of Water and Air Resources, and the North Carolina Board of Water and Air Resources were very helpful in facilitating the conduct of this study, and providing historical and background information. The drilling of the observa- tion wells and the hydrogeological studies at the waste-injection site resulted from waste-monitoring requirements of the Office of Water and Air Resources. Ralph C. Heath, US. Geological Survey, Raleigh, N.C., gave valuable assistance in coordinating the efforts of the authors with the company, state, and federal agen- cies. He also assisted in the interpretation and writing of the hydrogeological study. Much of the material contained in the hydrogeology, case history, and mi- crobiology sections of this report was previously pub- lished (Peek and Heath, 1973; DiTommaso and Elkan, 1973), and is reproduced in this report with the per- mission of the authors and the American Association of Petroleum Geologists. Issac J. Winograd, US. Geological Survey, Reston, Va., assembled and organized data and records which predated the beginning of this study. The cooperation and assistance of officials at Her- cules Inc., Frank Parkinson, plant manager, J. Gale Wendle, Jr., and Al Lister, technical superintendents, and John Humphries, chemical engineer, are greatly appreciated. Charles Sever, consulting geologist with Black, Crow, and Eidsness, Inc., supplied the well logs and served as a consultant to Hercules Inc. on the well engineering and geohydrology at the injection site. Dr. Louis Adcock, Professor of Chemistry at the University of North Carolina at Wilmington, periodically col- lected samples at the injection site regardless of weather conditions and other obstacles. Donald F. Goerlitz, US. Geological Survey, Menlo Park, Calif, lent invaluable aid and experience to the organic analysis phase of this study. Everett A. J enne and Vance C. Kennedy, US. Geological Survey, Menlo Park, Calif, provided analytical assistance in trace- HYDROGEOLOGY 5 metal analysis. Donald W. Fisher, US. Geological Survey, Reston, Va., determined dissolved gases in the water samples. HYDROGEOLOGY By H. M. PEEK and R. C. HEATH The Wilmington Area is underlain by coastal-plain sedimentary units more than 1,000 ft (305 m) thick. The sediments are predominantly of Late Cretaceous age and include ascending the Cape Fear, Middendorf, Black Creek, and Peedee Formations. The Castle Hayne Limestone of Eocene age overlies the Peedee in much of the area, but does not extend as far west as the Hercules site. Undifferentiated sands (probably of Pleistocene age), about 75 to 100 ft (23 to 30 m) thick, overlie the Cretaceous strata at the Hercules site. As shown in figure 3, these units generally consist of in- terbedded sand, silty sand, clay, and some thin beds of limestone. The sediments are fine grained, with clay the predominant lithic unit. The beds of sand are thin and generally fine grained. The surficial sand is the only freshwater aquifer beneath the site. The sand is very permeable and is a productive source of water. The rate of recharge is high as most of the precipitation enters the sand. Individual wells yield about 300 gal/min (1,136 l/min), and the total withdrawal at the site is more than 6 million gal/day (23 million l/day). There are several relatively permeable artesian aquifers in the Cretaceous sediments, but none are very productive and all of them contain brackish wa- ter. The principal aquifers occur at depths of 300 to 350 ft (91 to 107 m), 475 to 500 ft (145 to 152 m), 660 to 700 ft (201 to 213 m), 850 to 1025 ft (259 to 312 m), as indicated in figure 3. The “300-ft” zone was sampled and the head Was measured at several well sites during construction. Well 13 is the only well completed in this zone. The water from this well had a chloride concentration of 2,600 mg/l. The head is about 29 ft (8.8 m) above sea level. No wells have been constructed in the “500-ft” zone; however, samples for water analysis were collected during construction of wells 14 and 15, and the chloride concentration of water from this zone was near 7,000 mg/l. The artesian head was not measured. Three wells have been constructed in the “700-ft” zone and, in addition, water—quality and water-level data were obtained during the construction of deeper wells. The chloride concentration of the water in this zone is about 10,000 mg/l and the natural head in this zone was about 38 ft (12 m) above sea level. The zone between depths of 850 and 1,025 ft (259 to 312 m) is the injection zone. The water from this zone Geologic Chloride Water Injection well '09 (mg/l) level l—7A (ref LS) 0__ 0 g Iggy—Concrete pad : 6 -12 y g ‘ $5: V—Cement grout 100 —~ 30 £5 £3 g \Q 18 Steel pipe _ / § / 200 —— 60 Z § _ \ 0 Z s o / t; . :2 ? s 300 —>— 90 + — ; % Centralizers - +8 é \ lu / § u: U — — / \ u < / \ < ' u g b LL —— E v .. I; 400 ‘20 a g +6 Stainless steel pipe (n § § - D o / \ D Z o / § .2. - 5 2 ¢ s 500 —— 150 ;’ — a + §< § 9 _ d g ’— g {-—12” Steel pipe Lu _ CO / § :9 0, § § ,_ 600 ——180 m g \ m _ cc 0 / § "” E 8 o g § u. _ . _ 2 2 3' g S Cement grout + + \ —— —— §< >§ 5 \ / \ \ é \ \ l ; \ \ ¢ \ / Stainless steel and /, \\ Teflon packer Stainless steel screen 3 Gravel pack + 1000 —_ 300 1010 TD __ fl — Gravel Shell FIGURE 3.—Diagram showing hydrogeologic conditions and injection-well construction for well I-7 A. has a chloride concentration of nearly 12,000 mg/l. The ‘ artesian head in this zone is unusually high, about 65 ft (20 m) above land surface at the site, or about 90 ft (27 In) above sea level. This zone was selected for waste injection for reasons of its greatest depth below the fresh ground-water zone, the high salinity of the ground water in this zone, and permeability which would permit waste injection at the rate of 200 gal/min (757 l/min). The artesian conditions appear to be regional as in- dicated by the presence of freshwater to only very shal- low depths over a large area along the Cape Fear arch, as first observed by LeGrand (1955), and more directly by recent exploration. The injection zone and the thick overlying confining bed are identifiable in a well near 6 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA Calabash, about 45 mi (72 km) southwest of the Her- cules site, which is approximately along the line of strike. The elevation of the artesian head is about 100 ft (30 m) above sea level at Calabash. The water from this well has a chloride concentration of about 4,000 mg/l. The artesian head of a well completed at a depth of about 650 ft (198 m) at the Calabash site has an elevation of about 35 ft (11 m) above sea level, and the water has a chloride concentration of about 650 mg/l. The aquifer serving as the injection zone at the Her- cules site consists of multiple layers of sand, silty sand, clay, and some thin beds of limestone. The overall permeability of this section, which is about 150 to 175 ft (45 to 43 m) thick, is very low although the permea- bility of the salty zones is relatively high. A tempera- ture survey indicated that much of the waste entered a thin subzone at a depth of about 1,000 ft (305 m) in the initial injection well (I—6). No long-term pumping test was made on the injec- tion well prior to placing the system in operation. The injection rates fluctuated so greatly during the initial injection period that the data cannot be used to evaluate the hydraulic characteristics of the sub-zones. Tests on wells drilled later could not be made properly as the system was in operation and injection rates were not stable. The high artesian pressure, particularly in the deep- er aquifers, the generally low permeabilities of the aquifers, the thick zones of clay and silty sands, and the shallow depth to brackish water suggest slow natural circulation of water in the Cretaceous beds. CASE HISTORY OF WASTE INJECTION A chronology of the significant events which oc- curred during the four and one-half years of waste injection is given in table 1. A map showing locations of injection and observation wells is given in figure 4. INSTALLATION AND OPERATION OF INITIAL WE LL SYSTEM The initial well system consisted of one injection well (I—6) and four observation wells (numbers 1, 2, 4, and 5) completed at a depth of about 855-1025 ft (260—312m). Well 3 was completed in the first aquifer above the injection zone at about 660—690 ft (201— 213m) depth. The wells were cased with a special 10-in. (250-mm) diameter fiberglass casing and equipped with stainless steel screens of 6-in. (150-mm) diameter. The screens were set at the depths shown in table 2. The deep observation wells were equipped with plastic sampling tubes extending from the wellhead to the injection zone. Each well was equipped with a pressure gage on the wellhead and a manometer located at a central station. As shown in figure 4, the observation wells were only located at a maximum distance of 150 ft (45 m) from the injection well, which was too close to indicate the magnitude and pattern of pressure change or to permit a reliable measurement of the travel time of the waste. The injection of waste into the system was begun in TABLE 1.—Chronology of significant events during waste injection Date Event May 1968 Injection well I—6, and observation wells 1, 2, 4, and 5 completed to 1,025-fi: depth. Observation well 3 completed to 700-ft depth. May 1968 Waste injection begun through injection well I—6. September 1968 Waste was detected in wells 1, 2, 4, and 5. June 1969 Waste injection shified from well I—6 to wells 4 and 5 because of excessive injection pressures in well November 1969 Injection well I—6 damaged during an attempt to reclaim the well. Waste injection continued through well 5. December 1970 Observation well 8 completed to 700-ft depth. January 1971 Observation well 9 completed to 700-ft depth. February 1971 Leakage of waste into the 700-ft zone was detected at well 3. April 1971 Injection well I—7A was completed to 1,050-ft depth. May 1971 Waste injection shifted from wells 4 and 5 to well — A. May 1971 Observation wells 7 and 11 completed to 1,050-ft depth. May 1971 Wells 1 and I—6 were cemented to stop waste- leakage into the 700-ft zone. June 1971 Observation well 12 completed to 1,050-ft depth. October 1971 Waste injection renewed throu h well 4 because well I—7A was not accepting a 1 the waste at the specified injection pressure imit. November 1971 Observation well 13 completed to BOO-fl; depth. December 1971 Waste detected in well 9 indicated waste leakage into the 700-ft zone in that area. December 1971 Pressure decrease in well 5 indicated possibility of waste leakage into an aquifer above the injec- tion zone. March 1972 Pressure decrease in well 2 indicated possibility of upward leakage of waste. May 1972 Observation wells 14, 15, and 16 were completed to 1,050-ft depth. June 1972 Waste was detected in well 14, and a weekly sam- pling pro am was instituted to monitor the passage 0 the waste front. October 1972 Wells 2 and 5 were cemented to stop waste-leakage into the 700-ft zone. November 1972 Waste injection was gradually phased over to sur- face treatment of the waste. December 1972 Waste injection terminated. January 1973 Waste disappeared from well 14 after injection termination. CASE HISTORY OF WASTE INJECTION TABLE 2.—Injection-system well data Well Date drilled Total Screened No. Purpose (mo-day-yr) depth (ft) interval (ft) Water Level1 Remarks 1 Observation 6-1-67 1,025 855—1025 93 Abandoned 5/71 2 Observation 7-27L67 1,025 855—1025 93 Abandoned 10/72 3 Observation 8-8-67 690 660—690 40 4 Observation 3-13-68 1,025 854—1025 93 Also used as injection well 6/68—8/68 and 10/ 71—12/ 72 5 Observation 1-27-68 1,025 854—1025 93 Also used as injection well 6/68—5/ 71. Abandoned 10/72 6 Injection 2-3-68 1,025 855—1025 93 Abandoned 5/71 7 Observation 5-7-71 1,040 805—1036 1 1 1 7A Injection 4-29-71 1,110 830—1008 195 8 Observation 12—3-70 709 694—704 41 9 Observation 1-28-71 743 727—737 32 11 Observation 5-28-71 1,043 855—1035 127 12 Observation 6-23-71 1,015 838—974 150 13 Observation 11-16-71 300 283—293 29 14 Observation 5-23-72 1,010 843—972 — 15 Observation 5-23-7 2 1,030 843—97 7 — 16 Observation 5-23-7 2 1,010 843—983 — ‘In feet above mean sea level on date drilled. Water levels need to be considered in light of injection history. the latter part of May 1968 by intermittently inject- ing batch quantities at a rate of about 200 gal/min (757 l/min). As the volume of waste increased and the A A A15 2:” \ / \\ A16 / 7MB \\ / \ E t SE 0 75 150 FEET Ewl E 0 20 40 METR ES 0 1000 2000 FEET 0 300 600 METRES EXPLANATION Injection well Observation well O Observation well used as injection well Plant location - Lat 34°19’ N.; Long 77°58, W. FIGURE 4.—Map of waste-injection and observation wells. periods of injection lengthened, the pressure rose sharply in the injection well and in the aquifer. The average monthly injection rate and the highest well- head injection pressures, measured monthly or more frequently, are plotted on the graphs in figures 5 and 6 and reflect the early history of the system. By September 1968, the waste was detected in sam- ples collected from all existing observation wells (wells 1, 2, 4, and 5) in the injection zone. Only pH and dissolved solids were determined on samples collected during the passage of the waste front through the observation wells. There were no determinations of any gas constituents evolved from subsurface waste reactions, and no measurement of organic waste con- tent. By May 1969, pressure in the injection well had reached the equivalent of 400 ft (91 m) above sea level, and about 165 ft (50 m) in the observation wells. . 77‘, WELLS USED FOR WASTE INJECTION 240 I45 I | I-7A I-7A +4 +4a5 5 GALLONS PER MINUTE May June July Aug Sept Oct Nov Dec .0 u u. Mar Apr Jan 70 11 1 . to ‘ \l ‘ FIGURE 5.—Monthly average injection rate. Injection ceased December 1972. 8 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA INJECTION PRESSURE IN FEET ABOVE LAND SURFACE 200 300 400 500 June I | l July Aug Sept I I I | Oct I I l | I l 8961. Nov Dec _Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec 6961 I Shifted injection from well 4 to well 5 I Injection well (6) out of service I _ I Jan I Feb Mar Apr May June July Aug Sept Oct Nov Dec Recirculation during work on Injection well No. 6 OLGI (339) 978) (I‘d 05L) OJI'ISSSJO alqemcne umlugxew Jan Feb Mar Apr Mav Began injection through / June well |A7A July lL6I Aug Sept Oct Nov Dec _ Jan‘ Injection stopped in well 5 Began injection through well 4 Feb Mar Apr May June ZLSI. July Aug Sapt Oct Nov I | l I | I | I | I Injection ceased December 1972 4 FIGURE 6.—Graph of highest wellhead injection pressures. Dec Figure 7 shows the oval pattern of the pressure sur- face in the injection zone in January 1969 which suggested the greatest waste movement to the north- west from well I—6. The injection pressure continued to rise to a high of more than 450 ft (137 m) by June 1969. Because of the pressure build-up in the injection well, it was not possible to continue injection of waste at the rate of 300,000 gal/day (1,136,000 l/day), with- out exceeding the allowable limits of 150 psi (10.3 bars) specified by the injection permit. As the obser- vation wells were of limited benefit after the waste had passed, the North Carolina Board of Water and Air Resources granted permission to the company for injection of the waste through wells 4 and 5 as an emergency measure to allow the plant to continue operating. In November 1969, an attempt was made to reclaim the injection well by replacing the screened section, but this reclamation attempt was not successful and apparently damaged the casing because of subsequent 100 FEET O 10 20 30 METRES EXPLANATION 0 Injection well A Observation well — injection zone A Observation well — 700-foot zone 5 Upper number is well number 153 Lower number is altitude of the pres- sure surface; in feet above mean sea level. Contour interval variable FIGURE 7.—Location of wells in initial system and pressure surface, January 1969. waste leakage at this well. The pressure surface in late September 1970, is shown in figure 8. Well 6, the injection well, was out of service and well 5 was serv- ing as the injection well. As may be noted, the low pressure at well I—6 indicates leakage from the injec- tion zone through this well. In February 1971, a sud~ den pressure increase was noted in well 3 which is screened in the aquifer at a depth of 660—690 ft (201— 210 m) and one month later in March, waste was detected in this well. A caliper log taken in May 1971 just prior to the cementing, the injection well 6 showed a break in the casing of the well near 500 ft (152 m) depth. Appar- ently leakage of the waste had occurred for a long period of time into the aquifer at a depth of 500 ft ( 152 m). This leakage had not been detected previously because of the absence of wells in the zone. A sonic log taken at this time indicated poor bonding between the CASE HISTORY OF WASTE INJECTION 9 cement casing and the formation between the injection zone and the 700-ft zone; therefore, the leak into the 700-ft zone most likely originated from the injection zone with the waste rising into the 700-ft zone around the outside of the well casing (C. Sever, oral commun., 1973). Well 1 in addition to injection well 6 was sealed with cement in May, 1971 because low pressure in well 1 indicated possible waste leakage also at this point. After cementing, the leakage apparently stopped be- cause the pressure in the 700-ft zone returned to nor- mal within a few weeks, with most of the decline occur- ring within hours. A request by the company to double the waste injec- tion rate from 300,000 gal/day to 600,000 gal/day was denied by the North Carolina Office of Water and Air Resources in March, 1970. After a review of the opera- A2 311 A4 312 Injection weHA333 100 FEET 0 ‘IO 20 30 METR ES EXPLANATION Injection well — out of service Observation well — injection zone ’D. Observation well — 700-foot zone 5 Upper number is well number 153 Lower number is altitude of the pressure surface; in feet above mean sea level. Contour interval 10 feet FIGURE 8.—Map of pressure surface, September 1970. tion of the system, in July 1970 the North Carolina Office of Air and Water Resources concluded that the operation of the system had not been successful, and that continued waste injection would require the in- stallation of at least one new injection well and a larger network of observation wells. CONSTRUCTION AND OPERATION OF ’ EXPANDED INJECTION SYSTEM The second injection well, I—7A, was drilled approx- imately 2,500 ft (762 m) northeast of injection well I-6 (fig. 9). The second injection well was to be located at the present site of observation well 7; however, the permeability was too low for injection at this site and well 7 was completed as an observation well. During the development of well I—7A, waste and gas were pulled into the well. The gas was accidentally ignited by welding equipment, and later analysis by Hercules Inc. indicated the gas to be predominantly methane. Identification of formic acid in water samples con- firmed the presence of waste. Waste injection through well I—7A began in May 1971 at an average rate of 120 gal/min (454 l/min), and injection of waste through well 5 ceased. By October 1971, this new well was not accepting all the waste within the specified pressure limit, and waste injection was resumed in well 4. Waste injection continued through both well 4 and injection well I—7A until the termination of injection in December, 1972. The spacing of the second observation-well network installed to monitor waste movement from both the old and new injection wells was 10—15 times the distance used in the original network. Observation wells 1 1, 12, 14, 15, and 16 were installed during the period from May 1971 to May 1972, to monitor pressure and waste movement in the injection zone. Observation wells 8 and 9, which were completed into the 700-ft (213 m) aquifer, were operational when the second injection well was completed. In December 1971, waste was detected in well 9 concurrent with an increase in pressure, indicating the leakage of waste into the 700-ft aquifer at the new injection site. This leak apparently was through the annular space around the casing of well I—7A. Pressure decreases in well 5 during December 1971, and in well 2 during March 1972, indicated that these wells also had possibly become channels for leakage of the waste into shallower zones. Wells 2 and 5 were later sealed with cement to prevent leakage, but well I—7A has not yet been sealed (April, 1974). Figure 9 shows the well system, the reduced pres- sure surface of the injection aquifer, and the approxi- mate limits of waste travel in October 1972. At this time, the areal extent of the waste in the subsurface does not coincide with the pressure surface because although the major quantity of waste was injected 10 through wells LG, 4, and 5, the highest injection pres- sure at this time was at Well I—7A thus biasing the pressure surface to the northeast of the waste- contaminated area. The waste had apparently passed well 14, about 1,500 ft (457m) north of the initial injection site, by the time it was completed, and also had passed well 15, about 3,000 ft (914 m) west of the initial injection site. During August 1972, the waste was detected in Well 11 as indicated by the dissolved organic carbon (DOC) content, which has proved to be RAILROAD O 1000 2000 FE ET 0 300 800 METR ES EXPLANATION 0 Injection well A Observation well — Injection zone A Observation well A 700-foot zone 0 Observation well — 300-foot zone © Observation well used as injection well ———— Original system — — — Approximate limits of waste travel —150— Pressure~surface contour - -140 - - Estimated pressure-surface contour 124 Upper number is altitude of the pres- sure surface, in feet above mean sea level. Contour interval 20 or 40 feet 7 Lower number is well number FIGURE 9.—Map of pressure surface and approximate limits of waste SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA the best index for monitoring waste movement in the subsurface at this site. In July 1971 the North Carolina Office of Air and Water Resources stipulated that the waste-injection permit would not be extended beyond the July 1, 1973 deadline. Therefore, in November 197 2, a conventional surface waste-treatment facility was completed by the company and the injection of the waste was gradually reduced as the new facility was placed in operation. During December 1972, injection of waste ceased, al- though injection of freshwater continued at a rate of about 15—20 gal/min (57—76 l/min) in both wells I—7A RAILROAD 0 1000 2000 F E ET 0 300 600 METRES EXPLANATION Injection well Observation well — Injection zone A Observation well — 700~foot zone 0 Observation well — SOD—foot zone © Observation well used as injection well ————— Original system —115— Pressure-surface contour —— 700 — - Estimated pressure-su rface contour 5 Lower number is well number 116 Upper number is altitude of the pressure surface, in feet above mean sea level. Contour inter- val 5 feet travel, October 1972. FIGURE 10.—Map of pressure surface with no injection, April 197 3. FIELD SAMPLING METHODS 11 and 4 to maintain both wells operable in case they would be needed for waste injection before July 1973. Injection of freshwater was stopped for a period of about 9 days in March and April 1973, and figure 10 shows the pressure surface of the aquifer at the end of the 9-day period. Freshwater injection ceased in May 1973. At present (April 1974), waste injection through wells is prohibited by law in North Carolina. FIELD SAMPLING METHODS The collection of ground-water samples can best be explained by first considering the construction of ob- servation well 14 as shown in figure 11. The construc- tion of this well is representative of most of the obser- vation wells which are completed in the injection zone. Because the natural artesian head of the water in the injection zone is about 65 ft (20 In) above land surface, water samples were collected by simply opening the valve at the top of the plastic sampling tubing. The small diameter (64 mm ID) sampling tubing enabled collection of a representative water sample after only a 30-minute flush period with minimal wastage dis- charge of ground water. Roughly three void volumes of water pass through the plastic sampling tube at a flow rate of 1,200 ml/min during the 30-minute flush peri- od. The twin sampling tubes were placed for the pur- pose of water collection from the well in the center of the screened injection zone at 935 ft (285 m) depth and from above the screened zone at 822 ft (251 m). Water samples obtained from above the screened section of the observation well were of little value as they did not represent water present in the injection zone. A 3-foot section of tygon tubing was connected to each outlet of the two sampling valves to facilitate sample collection. Sampling methods were designed to be applicable to uncontaminated ground water as well as the concen- trated waste for both organic and inorganic parame- ters. Dissolved organic carbon (DOC) was used to esti- mate the waste concentration because it is a quantita- tive organic parameter, and most of the organic waste constituents are water soluble. Water samples for DOC were pressure filtered on site immediately after collec- tion through a silver membrane filter with 0.45-um (-micrometre) porosity. The DOC sample was collected in a 50 ml glass serum bottle sealed with an aluminum-foil-covered rubber septum stopper. An ex- tensive discussion of the merits of the DOC parameter and the method of DOC sample collection is given in a paper by Malcolm and Leenheer (1973). Two samples were collected for standard inorganic water analysis: one litre of filtered water acidified to pH 2 with nitric acid for analysis of the cations, Al, Ca, Fe, K, Na, Mg, and Zn; and one litre of filtered non-l acidified sample for analysis of the anions, Cl, F, 804, 4” Gate valve Valve for M _—_\ lower sample ,— Valve for flfl'l upper sample I K Sampling tube outlets Valve for sampling casing water . Concrete pad 0- - , ao~F——— Concrete casings Valve for pressure gaugefi/ ' l 15" hole AV //l/’ /l,;' ¥10" ID:steel 4L pipe casing 4" ID steel pipe casing %" OD x y." ID Impolene tubing 10" hole 20' of %"stainless steel pipe 2" PVC screen 2"PVC pipe Silica sand Guide plug, back pressure valve and wash plug assembly 1010‘ 3%” hole FIGURE 11.—Construction features of observation well 14. NOz-NOs, and SiOz. The water was pressure-filtered on site through a vinyl metricell membrane filter of 0.45-p.m porosity in a plexiglass filtration assembly (Skougstad and Scarbro, 1968). Compressed carbon- free nitrogen was used to pressurize the filter because ferrous iron will oxidize and precipitate as ferric hy- droxide during filtration if air is used to pressurize the filter. Both the acidified and non~acidified samples were collected in acid-washed, 1-litre polyethylene bot- tles. A filtered l-gallon (3.8-1) sample for trace elements was collected in an identical manner as the sample for standard inorganic analysis. After collection in an acid-washed, gallon plastic jug, high purity nitric acid 12 \ was added to acidify the sample to pH 2. The amount of nitric acid pipetted into the sample was recorded for the purpose of acid blank analyses. The last type of water sample collected was a litre of unfiltered sample which was used to characterize the organic compounds. This sample was not filtered be- cause filtration may introduce low-level adsorption and contamination problems, and filtration will also remove organic compounds of low solubility which are adsorbed and occluded on sediments. This sample was collected in a litre glass bottle previously heated to 350°C (Celsius) to free it of organic contamination, and was sealed with a metal screw cap with a teflon liner. After collection, the glass bottle was placed in a molded styrofoam packer for shipment, and was chilled in crushed ice to minimize sample degradation. Blank samples of uncontaminated ground water were col- lected as well as waste-contaminated samples to test for the presence of organic compounds such as phtha— late esters originating from the plastic sampling tub- ing. Organic contamination arising from the sampling tubing did not prove to be a problem in comparison with the high concentrations of organic waste con- stituents in the contaminated ground water. When gas was present in the observation wells, gas which effervesced from the ground water because of changes in pressure, temperature, and solubility, was collected in the following manner. The outflow from the tygon outlet tube was directed into an inverted 100-ml graduate cylinder filled with water, and the rate of gas collection was determined over a timed period at a measured flow rate. After measurement of the rate of gas effervescence, the inlet of a 250-ml cylindrical glass gas collector tube was attached to the tygon outlet tube, and the well water was allowed to flow through and displace the air in the collector tube which was held in the vertical position with both the inlet and outlet stopcocks open. After all the air was displaced, the gas collector tube was placed in the hori- zontal position, and well water was allowed to flow through the tube until 5 to 10 ml of gas had been collected in the upper portion of the tube. The gas and water were sealed in the tube by simply closing the inlet and outlet stopcocks. After all the samples were collected, measurements of pH, alkalinity, and specific conductance were per- formed on site. Alkalinity was determined by titrating the water sample with standard acid to pH 4.5.The water samples were shipped air freight to Denver in a large ice chest filled with crushed ice. Most of the organic analyses were performed by the authors. The gas samples were sent by parcel post to the US. Geological Survey, Washington, DC. where Donald W. Fisher performed the gas analyses. The samples for standard inorganic analysis and trace metal analysis SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA were shipped to the Geological Survey’s Central Labo- ratory, Salt Lake City, Utah. The samples were col- lected on a periodic basis by trained observers at the site. INDUSTRIAL WASTE ANALYSIS ORGANIC ANALYSIS The major emphasis in the industrial waste analysis was upon the organic analysis because the chemical constituents of the waste were predominantly organic in nature. An analysis of the organic waste and methodology were used whereby one could test for the presence or absence of these organic waste compounds in waste-contaminated ground-water samples. Com- parisons of the organic analyses of waste-contaminated ground water sampled at various points in the subsur- face with the organic waste analysis indicated what reactions and transformatins were occurring between the waste and the injection zone for different periods after waste injection and for different distances of waste migration in the subsurface. The organic waste constituents are thought to be more reactive than the inorganic waste constituents because of ease by which they are transformed and broken down by microbiolog- ical reactions. Certain organic waste acids are thought . to be active in the formation of organic-metal complex- es, and thus injection of these organic complex-forming compounds causes the translocation of inorganic aquifer constituents. The parameter used to quantify organic waste con- centrations was DOC which is defined as that portion of total organic carbon which passes through a silver membrane filter of O.45-p.m porosity. DOC was deter- mined on the total carbon channel of a Beckman 915 Carbon Analyzer1 after inorganic carbon had been re- moved from the sample by acidifying with phosphoric acid followed by nitrogen gas purge. Losses of volatile organic carbon during the nitrogen gas purge were found to be minimal for the water-soluble organic waste constituents. A number of analytical methods were used to iden- tify and quantify the organic waste constituents such that nearly all of the organic carbon in the waste was accounted for. The analytical scheme used to separate and identify organic waste constituents is given in figure 12. The recovery and efficiency of each step in the analytical scheme was measured by determining the DOC which was separated or remained in the waste solution. Steam distillation was used to separate acetic and formic acids from other dissolved constituents. A 100-ml sample acidified to pH 1 with sulfuric acid was steam distilled until 200 ml of condensate was col- 1 The use of brand names in this report is for identification purposes only and does not imply endorsement by the US. Geological Survey. INDUSTRIAL WASTE ANALYSIS l3 lected. Recovery studies with acetic and formic acid standards indicated that 55 percent of the acetic acid and 45 percent of the formic acid was steam distilled. The pH of the distillates was adjusted to pH 10 with sodium hydroxide to render the acetic and formic acids non-volatile, and the samples were concentrated by evaporation on a hot plate. The concentrates were acidified with concentrated phosphoric acid and injected into a Varian Aerograph 2700 gas chromatograph equipped with a flame ioniza- tion detector. The column was glass (4 ft x 2 mm ID.) and was packed with 100/120 mesh Porapak Q coated with 3 percent phosphoric acid. The gas chromatogram showing the separation of acetic and formic acids is given in figure 13. Formaldehyde, methanol, and p-toluic acid in the waste were also found to be steam volatile, but these compounds did not interfere in the quantification of acetic and formic acid by gas chromatography. A more complete discussion of a new method for the gas chromatographic analysis of acetic and formic acid is given in a report by White and Leenheer (1975). The majority of the organic waste constituents were identified and measured in ethyl ether extracts. A 100-ml sample was first adjusted to an alkaline pH by adding 3—5g of sodium carbonate. Extractable bases and neutral compounds were then extracted by two successive 100-ml portions and followed by one 50-ml portion of ether. All of the extractions were performed in a 500 ml separatory funnel. The extracts were col- lected in a 250-ml Erlenmeyer flask and dried with 40 g of anhydrous sodium sulfate for four hours. Organic acids were extracted in an identical manner using the same samples which were previously extracted for neutral and basic compounds after acidification to pH 1 with concentrated sulfuric acid. Recovery studies using WASTE SOLUTION Direct GC IC d-tormvnuionol lcid momyl fermna. m-myl .c-uu, mun-om Add Nn,c0,.umn win» or y.| emu Ether soluuon w-m llv-v Dry with N.,so. Add H,so. , mm: wvlh «rm Kuaunn-Danish c nnnnn union Emu mluuon Drv with N550. in nu: compounds) Kuaama a u l, mamvl-p-mluna Vmuhv! b-nzvu slcoholl momyl-p-iovmy! benzene, dlmuhyl mophm-m- Mflhvlllian Wm. CH, N, 6:: dumminniun ul FIGURE 12. ——- Analytical scheme of organic waste analysis. I A. Air B. Formic acid (0.7 mg/ml) C. Acetic acid (0.7 mg/ml) (Attenuation—32X 10'” amps/mv) m AA B[\ C (I) Z 0 | l l l l J 3, o 1 2 3 4 5 m It a: II Lu 0 D: O 0 Lu I A B C 42 -12 Atten- 16X| 10 amDS/"IIV—g—64 X1 10 amps/mlv—éfiioln O 1 2 3 4 5 TIME, IN MINUTES FIGURE 13. — Gas chromatogram of acetic and formic acids. standards indicated that this ether extraction obtained 86 to 98 percent of the compounds of interest in the gas-chromatographic analysis. The ether extracts were concentrated by 250 m1 Kuderna-Danish evaporative concentrators equipped with 3-ball Snyder columns. The concentrators were placed in a fluidized-bed sand bath at 69°C. A time period of 30 minutes was required to concentrate 250 ml of ether to 5 ml. The ether concentrate containing the neutral and basic compounds was directly injected into the gas chromatograph for analysis. The concen- trate containing the organic acids was esterified with diazomethane to produce the methyl esters of the or- ganic acids. The methyl esters of the waste organic acids possessed sufficient volatility for gas-chromato- graphic analysis whereas the free organic acids, with the exceptions of acetic and formic acids, are non- volatile. The methylation procedure using diazomethane is given in the Methods Manual for Analysis of Organic Substances in Water (Goerlitz and Brown, 1972, p. 37). The majority of organic compounds extracted by 14 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA ethyl ether were found in the acid extract. A 10 ft x 2mm I.D. glass column packed with 10 percent dieth- yleneglycol succinate on Gas-Chrom Q was used to separate the esterified acids in the methylated acid extract. The gas chromatogram is shown in figure 14 of the esterified acid extract. Mass spectra were obtained on each peak of the gas chromatogram by using an equivalent column in a Finnigan GC—MS Model 150 system. The mass spectra of methyl-p-toluate and di- methyl terephthalate shown in figure 14 is correlated with the gas chromatogram by the spectrum numbers. Spectrum numbers are points in the time of the analy- sis where complete mass spectra can be obtained in the GC—MS system. “Background spectra” were subtracted 100 IIIIIIIrrIII4IIIIIIIIIIIIIIIIIIIIIIII 80 _ 1. Dimethyl methvlsuccinate 2. Methyl benzoate 3. Dimethyl succinate - g 60 4. Methyl-p-toluate __ 3 5. Dimethyl terephthalate S _ 6. Dimethyl phthalate — n. g 40— — < 20— - s 6 a O I I I l I I I l I I I l I I lrl I I I 0 20 40 60 80 100 120 140 I60 180 SPECTRUM NUMBER I I I l I | I I I l I l I I I I I I I I I 2 4 6 8 10 12 14 16 1B 20 MINUTES 100 I I I I I I I I I I I I I I I g _ _ g Spectrum Number 68—65 a. 80— Methyl-p-toluate — III :0 - _ <2 ‘1' 60— — u. 0 _ _ m 0 _ < I- z - u.I U _. CE LIJ u. _ J I I II I I I I I I I I I I 20 4O 60 80 100 120 140 160 180 200 ATOMIC MASS/ELECTRONIC CHARGE 100 I I I I I I I I I I I I I I I I I 5‘ — _ fi Spectrum Number 154—151 a 80— Dimethylterephthalate — In In -‘ _ < m 60— — u. 0 _ _ Lu 0 _ _ < 40 I. 2 " _ 3 I 20r— I _ III I. - I I 0 II II ll I. l l| l I I | I I I l I I I I 20 40 60 80 100 120 140 160 ATOMIC MASS/ELECTRONIC CHARGE 180 FIGURE 14.—Gas chromatogram and mass spectra of methylated-acid ether extract. by the computer in the system to give the mass spectra of the pure component. Characteristic mass spectra fragmentation patterns were used along with appro- priate standards to identify the organic compounds separated in the gas chromatograph. An electronic dig- ital integrator was used to determine the peak areas of each organic component in the gas chromatogram. Quantitative analysis was accomplished by compari- son of peak areas with standard curves. The ether extract for neutral and basic compounds was injected on the same diethyleneglycol succinate column as was used for the methylated acids, and the gas chromatogram of this fraction is shown in figure 15. There were no basic organic compounds found in the waste, and the neutral compounds identified in the ether extract accounted for less than one percent of the organic carbon in the waste. After comparing the quantity of organic carbon iden- tified in the steam distillate and ether extracts with the total DOC found in the waste, only about 75 per- cent of the organic carbon was identified. Identified organic carbon was determined by summing the prod- ucts of the concentration times the percentage carbon of the determined organic constituents. Because cer- tain volatile compounds were lost during extraction and concentration, direct injection of the waste itself into a column packed with 10 percent Ethofat on Chromosorb W was used to identify and quantify methyl formate, methyl acetate, and methanol. The gas chromatogram of this separation is shown in figure 16. A few organic compounds do not give a sufficient response on the flame ionization detector to be mea- sured; therefore another analytical method must be employed. Formaldehyde is such a compound and its presence was suspected by its characteristic odor in the waste residue after the other organic components had Dimethvl succinate Methyl-p—toluate p-Methyl benzyl alcohol Methyl-p-formyl benzoate Dimethyl terephthalate $599!“? 12 14 16 18 20 22 MINUTES FIGURE 15. — Gas chromatogram of alkaline ether extract. INDUSTRIAL WASTE ANALYSIS l5 Waste sample Standards 1. Methyl formats 2. Methyl acetate 3. Methanol MINUTES MINUTES FIGURE His—Gas chromatogram of neutral, volatile, waste constit- uents. been removed by ether extraction and steam distilla- tion. Formaldehyde was subsequently identified quan- tified by its color reaction with chromotropic acid (Bricker and Vail, 1950). None of the other organic waste compounds interfere in the formaldehyde de- termination. Formaldehyde was the last compound to be identified in the waste, and its inclusion with the other previously identified compounds accounted for 95 percent of the DOC in the waste. This scheme of organic analysis which was applied to the industrial waste prior to subsurface injection was also applied to ground-water samples which were con- taminated by the injected waste. The only changes in the analytical scheme were that the initial sample size was larger and the degree of concentration was greater. Three waste samples were collected during 1972—7 3, and the average analysis of these three samples is given in table 3. The data of the individual analyses are given in basic-data table 20. The DOC of these waste samples ranged from 6300 to 7800 mg/l; how- ever, there were only minor variations in the relative concentrations of the various organic constituents. All of the organic waste constituents can be thought of as reactants, impurities, byproducts, products, and (or) catalysts directly related to the industrial process- es. The overall process at the Hercules plant is to oxidize p-xylene to terephthalic acid in the presence of methanol and acetic acid to give the primary product, dimethyl terephthalate (DMT). There is also a small formaldehyde plant which produces formaldehyde from the oxidation of methanol. In the waste analysis, methanol is a primary reactant; benzoic acid and phthalic acid most likely result from the oxidation of toluene and o-xylene impurities in the p-xylene feedstock; p-toluic acid, p-methyl benzyl alcohol, and methyl-p-formylbenzoate are incomplete oxidation products of p-xylene oxidation; succinic acid, methyl- succinic acid, and propionic acid are probably the fragments resulting from cleavage of the aromatic ring during p-xylene oxidation; formic acid is a byproduct of methanol oxidation; formaldehyde, terephthalic acid, and dimethyl terephthalate are products; and acetic acid is a catalyst. The dimethyl terephthalate product is purified after p-xylene oxidation and methylation by distillation and recrystallization with the extraneous organic constituents going to the waste. Most of the organic acids found in the waste exist in chemical equilibria with the methyl, monomethyl, and dimethyl esters. These esters were generally found only in trace quantities in the waste because the aque- ous waste solution tends to favor hydrolysis of the esters to the acids. No distinction was made between the monomethyl esters and the free acids for the dicar- boxylic acids in the waste because both types of com- pounds were extracted in the acid fraction, and methy- lation with diazomethane converted both the mono- methyl ester and free acid to the same dimethyl ester. For example, what is identified as terephthalic acid may actually be monomethyl terephthalate in the waste because methylation of both compounds will produce dimethyl terephthalate. The fact that mono- methyl terephthalate is much more water soluble than terephthalic acid strongly suggests that the monomethyl ester of terephthalic acid predominates in the waste. The organic waste analysis demonstrated that an industrial organic waste can be characterized by using a logical analytical scheme, by conducting a materials balance with DOC, and screening for organic com- pounds which are likely to be found in the waste as the result of the industrial process. INORGANIC ANALYSIS Table 4 summarizes the inorganic constituents found in the waste prior to injection. This table gives averages of two inorganic waste analyses performed by the WRD Central Laboratory, Salt Lake City, Utah, with a few miscellaneous analyses performed elsewhere. The data of the individual analyses are given in Basic Data table 21. The elements determined by atomic adsorption were Al, Mn, Ca, Mg, Na, K, Sr, Mo, Ni, Cd, Cr, Co, Hg, Zn, and Cu. Automated co- lorimetric methods were used to determine Si02, Fe, 804, Cl, NOz-NOa, and P04, and manual colorimetric methods were used to determine As, Se, and F. 16 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA TABLE 3.—Average organic analysis of waste Structural Concentration Concentration Percentage Trace organic compounds (less than 0 S m l . g DOC Compound formula (mg/l) as DOC (mg/1) of DOC / ) 0 Compound Structural formula Acetic acid CH3—c’ -0H 9,350 3,740 52.6 0 *c-ocn; Dimethyl phthalate [0 aC-OCH3 Formic acid H_c’ -0” 3,110 812 11.4 0 o _ o 0 Dimethyl succinate CH30-E-CH2-CH2-Ch-OCH3 “ -0H 0 p-Toluic acid 1,140 805 11.3 °C'0CH3 Dimethyl terephthalate CH3 0000013 40 O Formaldehyde H—C -H 1,800 720 10.1 Methyl acetate CH3—c‘ -0CH3 CHZOH p-Methylbenzyl alcohol Methanol CHSOH 757 284 4.0 CH3 0 Methyl formate H-C//0-OCH3 °c-0H 0“ OCH . . 4 257 . _ 3 Terephthallc ““1 59 3 6 Methyl-p-formyl benzoate ,c-on H 0, 4 _ a0 0 c -0H CH3 ' ,0 Phthalic acid (1 76 43 .6 Methylsuccinic acid HO- QC-CHZ-CH-C' -0H \ -0H t 0“ o c-ocn3 ‘ -0H Methyl-p-toluate © Benzoic acid 54 37 .5 C. 3 Propionic acid CH3-CH2-c‘0-0H on 110 Waste DOC-7110 mg/l Total 6,698 94.1 Succinic acid 310- C-CHZ-CHz-C -0H Of the inorganic parameters commonly found in mg/l levels in ground water, only Ca, SiOz, and NOz-NOa were significantly higher in the waste than in the native ground water present in the injection zone. TABLE 4.—Inorganic waste analyses Concentration Dissolved constituent . . _ Dissolved constituent Concentration Milligrams per litre Micrograms per litre silicg(sioi) Aluminum (A1) total 6200 Calcnm'i (Ca) .. 1300 Arsenic (As) ~ 3 mesnfim)(Mg) 3% 7 Cadmium (CV -- 4 urn a ~ Chmmium(Cr)it0t81-~~ 26° Potassmm (K) 3-8 Cobalt (Co) ..................... Sulfate (so ) . 25 Chloride (cl) . 5.4 0°99" ‘0“) """ 100 , Iron (Fe), total. 5500 Fluoride (F) ..... 2.1 Le d (Pb) 7 Nitrite-nitrate moi-Nos). 3.9 M a """ g M izo Orthophosphatea’od ............ ‘28 M235”??? ) méai 1 Hardness as CaCOa (Ca, Mg). 3400 my 3‘ ’ " ., _———-— Molybdenum (Mo) .. 2 Nickel (Ni) ........ 50 skinning; ““““““““““““““ 4 553‘s Se‘eniPm‘se’ ' 33 (micromhos at 25°C). Effi’ét‘fl‘sf’ mi: 290 Prior to injection, the waste moved through a settling basin, was passed through a filter to remove particles over 20 am in size, and was treated with lime to adjust the pH to 4. The high levels of calcium and silica in the waste undoubtedly come from the pre-injection lime treatment in which the organic waste acids act to sol- ubilize calcium and silica. The levels of NOz-NOs can only be considered high in comparison to the native ground water in which there is practically no nitrate or nitrite. However, the presence of nitrate or nitrite in the waste may be significant because it is an available source of nitrogen for microorganisms that may be degrading the waste in the subsurface environment. Aluminum and cobalt were found in mg/l concentra- tions in the waste whereas they are usually found in lug/1 concentrations in ground water. The source of aluminum is probably from the pre-injection lime HYDROCHEMISTRY OF NATIVE GROUND WATER 17 treatment, and its high concentration points out the potential of the waste for dissolution of alumina- silicate minerals. The high cobalt concentration is of interest because cobalt salts are frequently used as catalysts in the oxidation of p-xylene. None of the major inorganic waste solutes—calcium, magnesium, silica, iron, aluminum, and sulfate—can serve as satisfactory tracers of waste movement in the subsurface. These solutes are common constituents of the minerals in the injection zone, and their source cannot be differentiated between the waste and the injection zone. Nitrite-nitrate are assimilated by the microorganisms in the injection zone because they are essential nutrients in limited supply. Lastly, cobalt might initially seem to be an ideal inorganic tracer for waste movement because it is an element not com- monly found in significant concentrations in ground water or as a common constituent in aquifer minerals. However, cobalt is a divalent cation which participates in cation-exchange reactions with the minerals within the injection zone, and is more strongly held and re- tained by exchange complexes on the aquifer minerals than is calcium or sodium which are the predominant cations in the native ground water. The law of mass action in ion-exchange reactions also indicates that cobalt will be removed from the waste solution and replaced by calcium and sodium from the exchange complex because the ratio of calcium to cobalt is 100 times greater in the ground as compared to the waste, and the ratio of sodium to cobalt is 10 million times greater in the ground water than in the waste. In summary, the dissolved ionic solutes of the indus- trial waste solution consist primarily of calcium and hydrogen as cations, and of acetate, formate, p-toluate, and terephthalate as anions. All combinations of these ionic species appear to be present in concentrations below saturation solubilities except for calcium and terephthalate which forms a precipitate when the waste solution is cooled to 20°C. PHYSICAL PROPERTIES The waste prior to injection is a clear straw-colored liquid with an acrid odor which is a combination of the odors of acetic acid, formic acid, formaldehyde, and p-toluic acid. The temperature at which the waste was injected was about 45°C, and when the waste was cooled to the temperature of the injection zone (22°C), a white precipitate very slowly formed which was primarily the calcium salt of terephthalic acid. This precipitate may not appear until the waste is refriger- ated or agitated because the waste is apparently easily supersaturated with respect to terephthalic acid and its inorganic salts. The density of the waste at 20°C was determined to be 1.006 g/ml, and the density of the ground water at this temperature was 1.0142 g/ml. The injection tem- perature was 45°C and the density of the waste at this temperature is 0.9951. This density difference may indicate that the lighter waste may tend to gravitate to the upper part of the injection zone and move outward from the injection well at a faster rate in the upper portion of the injection zone if the injection zone has a constant T (transmissivity) value throughout the 150- foot injection interval. Most likely the T value varies and the waste preferentially moves out into the zone of the highest T value regardless of whether this zone is at the top or bottom of the injection interval. HYDROCHEMISTRY OF NATIVE GROUND WATER The mean chemical analyses of the native ground water found in the five water-bearing zones at the waste injection site are given in table 5. Most of the inorganic water analyses were performed in the Geological Survey’s Water Resources Division Laboratories in Raleigh, N.C., and Salt Lake City, Utah. Each individual inorganic water analysis per- formed on water samples obtained from observation wells during the course of this study is found in basic- data tables 22—32. Water samples from the surficial sand aquifer were collected from wells 14, 15, and 16 during well con- TABLE 5.—Inorganic analysis of native ground water found in aquifers at waste-injection site Dissolved constitumt Depth of aquifer below land surface 25-66 it 275-330 0: 500-520 R 660-740 R BOO—1,025 fl; (7 6—20m) (84-101m) (152-158m) (201—226m) (244-312m) 5H ........................................... 6.2 8.2 7.8 7. 7 7.4 pecific conductance (micmmhos at 25°C)....... 43 8,890 19,800 27,200 31,300 Temperatme(°C ) ................. 18.5 20.1 20.0 20. 9 22.7 Density (g/ml at 20°C) ......... 1.0000 1.0042 1.0042 1.0089 1.0142 , Milligrams per litre W Silica (SiOz) ...... 4.9 8.1 7.2 9.5 9 3 Calcium (0a).. 2.6 28 130 260 333 esium 1.3 40 177 267 309 um (Na) 3.6 1,900 4,520 6, 6,750 Potassium (K) ....... 8 73 121 182 186 Bicarbonate (11003)" 6.5 578 354 303 230 Sulfate te(SO4. 2.9 214 763 595 273 Chloride (01).. 6.0 2,610 6,970 9,990 12,100 Fluon de (F) ...... .0 1. .8 .5 Nitrite-nitrate (NQ-NOa). 1.21 . .05 .30 05 DOI‘tholphosphate CPO4) ......... 006 005 .000 .047 045 ved orgamc carbon 1 3 5 Residue) on evaporation — ' t1.80°C 35 3,980 13,100 17,300 20,800 Hardness as CaOOa (CaMg) 12 231 1,050 1,740 2,110 , Micrgarmls per litre Aluminum (Al) total ........... 109 280 613 343 242 As — — — 9 2 — — 300 425 — — — 60 — — 4 10 18 — — — 2 1 40 173 -— 75 73 76 1,450 — 2,640 2,260 _ ._ — 3 2 — — —— — 285 12 112 — 165 356 —— -— — 14 10 _ _ — 2 1 — — — 3 " 2 p _ _ .. 2 8 Strontium (Sr) — 1,200 — 16,000 18,600 18 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA struction, and from Company supply well C. Water was obtained between depths of 25—65 ft (76—20 m) below land surface, and data in table 4 for this aquifer were averaged from the individual analyses. Data were also averaged to characterize water found in the 300-ft, 500-ft, 700—ft, and injection zones. Water samples from the 300-ft zone were obtained from wells 14, 15, and 16 during construction, and from well 13 which is screened in the 300—ft zone. The only water samples which were available to characterize water found in the 500—ft zone were obtained from wells 14 and 15 during construction. For the 700-ft zone, uncontami- nated water samples were obtained from well 8 and from well 14 during construction. Well 3 which is com- pleted in this zone was contaminated with waste before samples were obtained. Well 9 in this zone produced water with the same chemical composition as water from the injection zone before it became contaminated with waste. Uncontaminated ground water from the injection zone was obtained from wells 7, 11, 12, and 16. Wells 2, 3, 4, and 5 were contaminated before sam- ples could be obtained, and the injection zone was found to be contaminated with waste when wells 14 and 15 were completed. On the basis of dissolved solids content determined by residue on evaporation at 180°C, water from the surficial sand aquifer is classified as nonsaline, water from the 300-ft zone is moderately saline, and water in the 500-ft, 700-ft, and injection zones is very saline (Swenson and Baldwin, 1965). Just as dissolved solids increase with depth, so do calcium, magnesium, sodium, potassium, strontium, manganese, chloride, hardness, specific conductance, density, and tempera- ture. The parameters which do not increase with depth are pH, bicarbonate, and sulfate. Bicarbonate and pH attain their maximum values in ground water from the 300-ft zone, whereas sulfate content is the highest in the 500-ft zone. Below the 300-ft zone, both bicarbon- ate and pH decrease with depth, and sulfate content decreases with depth below the 500-ft zone. This varia- tion of sulfate content with depth may reflect varia- tions in aquifer mineral constituents, bacterial reduc- tion of sulfate in an anaerobic environment, or forma- tion of barium and strontium sulfates. Water from the 700-ft zone and the injection zone contains a small amount of hydrogen sulfide, as evidenced by its odor and the formation of black sulfide precipitates; there- fore, sulfate may be reduced in these zones by bacterial reductive processes. Hem (1970, p. 168) states that water containing 1 mg/l of barium should contain no more than a few milligrams per litre of sulfate, and water containing 10 mg/l of strontium should contain no more than a few hundred milligrams per litre of sulfate. The water from the injection zone contains about 10 mg/l of strontium and about 0.4 mg/l of barium; therefore, the concentrations of these two con- stituents may well be the solubility controls on the concentration of sulfate. The change in bicarbonate and pH with depth may also reflect variations in aquifer mineral constituents; however, the decrease observed in the more highly mineralized water may well be an artifact caused by the precipitation of calcite during the sampling, stor- age, and shipment of the samples before the analyses were performed. The only significant concentration of nitrite-nitrate was found in the surficial sand aquifer where nitrite- nitrate probably infiltrates from surface sources. Phosphate concentrations were very low in all aqui- fers. These low concentrations of essential nutrients for microbial activity may be important in limiting the amount of microbial waste degradation in the subsur- face. Lastly, the concentration of dissolved iron and dis- solved organic carbon (DOC) is of interest because these parameters are most affected by waste injection. Above pH 4.8, the solubility of ferric iron is less than 10 Mg/l unless there are significant concentrations of organic substances capable of forming soluble com- plexes (sequesterization) with ferric iron (Hem, 1970, p. 116). Because the DOC concentrations are quite low and the pH is slightly alkaline, it is probable that most of the dissolved iron exists in solution in the more soluble reduced form, ferrous iron. WASTE-AQUIFER INTERACTIONS After postulating a number of probable waste- aquifer interactions at the inception of this study in January, 1971, a two-fold study was undertaken to test the predicted transformations of the waste after sub- surface injection. A site study based on analysis of water samples obtained from the observation well sys- tem was initiated in June 1971 and terminated in November 1973. A laboratory study which simulated waste injection into cores of aquifer material was con- ducted following the site study, and was terminated in March 1974. SITE STUDY INITIAL CONDITIONS The water-quality situation at the waste-injection site at the beginning of this study in 1971 is shown in table 6. Water samples from wells 2, 3, 4, and 5 had analyses very similar to the inorganic analysis of the waste given previously in table 2, and all of the ex- pected reactions had apparently stopped or slowed to rates where they were not observable. At this time, native water samples from the injection zone could be obtained from the recently constructed wells 7 and 11, WASTE-AQUIFER INTERACTIONS 19 TABLE 6.—Change in water composition with waste contamination Concentrations of dissolved constituents, in mg/ l Well Spfg‘fguignjsnagfgie Date pH so, A] Fe Mn Ca Mg Na K HCOa so. Cl F P N03 DOC 7 32,500 11/3/71 7.3 11 0.3 1.8 0.2 705 107 6800 330 230 280 12,000 0.9 0 0 1.2 11 32,000 11/3/71 7.2 8.6 .2 1.8 .3 537 195 6600 330 230 210 12,000 0.6 0 0 0.7 4 8,280 6/15/71 4.0 23 6.8 8.3 .3 2500 34 2.9 2.2 0 8.0 230 1.3 1.3 3.9 10,600 5 8,080 6/15/71 4.0 34 7.1 8.0 3 2400 49 3.2 2.3 0 19 140 1.3 1.1 39 11,200 avg'°°“cnwe“34and5 2.9 28 5.1 1.0 3.9 0.27 .00046 .0068 0 0.055 0.02 1.7 - - 11,500 avg. concn wells 7 and 11 which were outside the area of waste contamination and water obtained from these wells were complete- ly free of waste. The data in table 6 represents the two extremes between wastes and native ground wa- ter. An objective of the site study was to observe the organic and inorganic changes in the ground-water analyses in going from an uncontaminated to a con- taminated state and to relate these changes to the initial hypothesized waste transformations (fig. 17) so that the initial hypotheses could be confirmed or re- jected, new hypothesis made and tested, and to formu- late final conclusions concerning waste transforma- tions as presented in this report. INITIAL CONCEPTUAL MODEL OF INJECTED-WASTE REACTIVITY AND MOVEMENT The initial conceptual model of the various stages of the waste in the subsurface environment is dia- grammed in figure 17. This model is diagrammed for a certain point in time after the beginning of waste injec- tion when the various components of the model have had a chance to form due to various waste-aquifer interactions. With increasing time during waste injec- tion, the dimensions of this model will expand and move to the right. The leading volume of waste moving outwards from the injection well is mixed and dis- persed with the native aquifer fluids, and this area of dispersion is called the waste front in this conceptual model. The waste area which extends between the in- jection well and the waste front is called the waste INJECTION WEI-I- WASTE FRONT o WASTE INTERIOR I o o m o I n o m o I a o I Flelative percentage of waste to percentage of groulnd water a o I m o an o PERCENTAGE OF GROUND WATER PERCENTAGE OF INJECTED WASTE 8 | l I I I I l I I I I I | | I I I I I I I l | | I l I I I I I I 1 I 1oo IMICROEIAL ACTIVITY ZONE FASTvREACTION ZONE TRANSITION ZONE 0 WASTEI SLOWVREACTION POOL zone WASTE MOVEMENT _' FIGURE 17 .—Initial conceptual model of injected-waste reactivity and movement. interior where the native ground water has largely been replaced by the injected waste. The waste front and waste interior are divided into five zones which are labeled to describe the predominant types and mechanisms of waste transformations within each zone. Microbial waste degradation is thought to occur only at the leading edge of the waste front, and this zone is called the microbial activity zone. The area behind the microbial activity zone is called the transition zone because it is speculated to be a region of transition between predominantly mi- crobiological and chemical reactions which occur in the injected waste. Few chemical reactions are thought to occur in the transition zone because the reactions be- tween the waste and the injection zone components are essentially completed by the time the waste reaches the transition zone. However, decreasing microbial ac- tivity is expected throughout this zone because of in- creasing concentrations of certain toxic organic com- pounds such as formaldehyde, and because of the dis- appearance of limiting nutrients such as nitrate and phosphate. The zone trailing behind the transition zone is called the fast-reaction zone in which neutralization type reactions occur between the waste acids and the aquifer mineral constituents. Such reactions include the acidic dissolution of aquifer carbonates and iron oxide coatings. The pH of the waste solution changes from four at the trailing edge of the zone to seven at the boundary with the transition zone. Reactions which occur in what is defined as the slow-reaction zone are the slow solubilization of silica, aluminum, and iron from the aluminosilicate minerals in the injection zone. The last zone which is adjacent to the injection well is called the waste pool because there are no apparent reaction or changes with time going on in the waste in this area. REACTIONS OBSERVED AT WELLS 1, 2, 3, 4, AND 5 At the beginning of this study, limited data were available from the Company concerning waste con- tamination of wells 1, 2, 4, and 5 during the first few months of waste injection. Residue on evaporation and pH data for water samples obtained from wells 1 and 5 during waste contamination are shown in figure 18. When the first samples were taken in July 1968, lower 2O SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA M A B 1 Well 5 ‘ 5 1 1 G 1 l 6 1 1 Well 1 to l l m l l RESIDUE ON EVAPORATION, AT 1800 C (THOUSANDS mg/I) U ,_ he ,_ ,_ Well 5 pH Well 1 8»20 979 DATE (1968) FIGURE 18.—Variations in pH and residue on evaporation from sam- ples taken during observation of waste front in wells 1 and 5. residue on evaporation values indicated that waste was already present in observation well 1, which was only 50 ft (15 m) from injection well I—6, whereas ob- servation well 5, at a distance of 150 ft (46 m), was waste-free. Observation well 5 remained waste-free until the beginning of October, when both the pH and residue on evaporation started to decrease. The pH decreased be- cause of the acidity in the waste and the residue on evaporation decreased because the native ground water was replaced by the waste which had a lower dissolved solids content. The fast-reaction zone in which the waste acids are neutralized is shown by the data from observation well 1. From July 28 to October 15, 1968, the pH remained between 5 and 6, during which time carbonates and iron oxides within the injection zone were reacting with the waste. The mixture of free organic acids and organic-acid salts from the neutralization reaction re- sulted in a pH between 5 and 6. When the fast waste- neutralization reactions stopped, the pH abruptly de- creased to the pH of the injected waste (pH 4) on Oc- tober 18, and has remained near this level to the pres- ent. Residue on evaporation in this well also decreased at this time to levels found in the injected waste. Water samples collected while the waste was react- ing with carbonate minerals contained large amounts of dissolved carbon dioxide, which is a product of the acid-carbonate reaction. A sample of gas which effer- vesced from a water sample collected from well 3 con- tained 70 percent carbon dioxide by volume as shown in basic-data table 33. REACTIONS OBSERVED AT WELL 9 The first opportunity to observe an aquifer during the process of waste contamination occurred at well 9 in which waste suddenly appeared in high concentra- tions in December 1971. The first inorganic analysis determined on a sample collected on June 15, 1971 (basic-data table 25), indicated that the composition of samples obtained from this well (screened in the 700-ft zone) was essentially the same as water obtained from the injection zone. This was an indication that ground water from the injection zone had somehow leaked into the 700-ft zone before waste injection was begun in the second injection well I—7A; therefore, it was not very surprising when waste appeared in this well after waste injection had started in well I—7 A. By June 1972, a sample collected from well 9 con- tained 5,800 mg/l DOC, 78 mg/l iron, 3,900 mg/l cal- cium, with a pH of 5.8. These high concentrations of calcium and iron were indicators of waste dissolution of aquifer carbonates and iron oxides. The analysis of a sample collected almost a year later (basic-data table 25) showed that the DOC concentration had increased only slightly to 6,300 mg/l, the pH was 4.5, the calcium concentration had decreased to 3,100 mg/l, and the iron concentration had increased to 310 mg/l, which is an extremely high concentration of iron in natural water. These changes observed in two samples collected a year apart indicate that the reaction of the waste with aquifer carbonates occurs previous to, and at a higher pH than, dissolution of iron oxides. Carbon dioxide gas was also present in the June 1972 water sample (basic-data table 33), whereas no gas at all was present in the June 1973 sample. The very high concentration of iron in the June 1973 sample indicates that the phthalic acids found in the waste were probably form- ing water-soluble complexes with iron. The indications of the carbonate and iron oxide dis- solution reactions found in the 700-ft zone tend to con- firm the hypothesized reactions found in the fast- reaction zone; however, these reactions occurred in an aquifer overlying the injection zone as the result of a leak, and well 9 was not regarded as a completely satisfactory sampling point to obtain information con- cerning reactions in the waste-injection zone. REACTIONS OBSERVED AT WELLS 11, 14, AND 15 The major share of information concerning waste- aquifer interactions was derived from analysis of water samples obtained from wells 11, 14 and 15 during the time the waste front could be sampled in these wells. Waste was found in wells 14 and 15 at the time (May 1972) they were completed in the injection zone as WASTE-AQUIFER INTERACTIONS shown by the high biological oxygen demand (BOD) values determined by company analysis not given in this report. Waste appeared in well 11 in December 1972, detected on the basis of DOC concentrations being above background levels. Well 11, 14, and 15 were sampled on a periodic basis from June 1972 to October 1973 by trained observers at the site. Data obtained on water samples from wells 11, 14, and 15 during this period are found in basic-data tables 34, 35, and 36, respectively. Waste was present in well 15 for only a short time after it was completed. The DOC data in basic-data table 36 shows that all except a trace of the waste was gone from this well by December 1972. The presence of acetic acid, p-toluic acid, and terephthalic acid defi- nitely confirmed the presence of waste in this well during the period of elevated DOC levels. Waste was present in well 14 in much higher con- centrations than well 15, and it did not disappear until January 1973. The significant variable parameters de- termined during the period when waste was present in this well are plotted in figure 19. The waste concentra- tions never became sufficiently high to cause detecta- ble effects on pH, alkalinity, specific conductance, and the inorganic anions and cations with the exception of iron. Pressure changes measured at wellhead were plotted to establish a possible relation between (1) the | | I I ~ 80 . Dissolved organic carbon , —— SO 0 Pressure difference ~40 DISSOLVED ORGANIC CONCENTRATION (mg/l) DIFFERENCE (psl) . Dissolved Iron 0 Gas efflrvescenm_ ‘ GAS EFFERVESCENCE WELL HEAD PRESSURE (ml gas/ml water) DISSOLVED IRON . Acetic acid 0 Formic acid — 12 FORMIC ACID . p4To|uic acid 0 Tevaphmalic acid— 3_ —a D4TOLU|C ACID ACETIC ACID CONCENTRATION (mg/I) CONCENTRATION (mg/l) CONCENTRATION {mg/I) TEREPHTHALIC ACID CONCENTRATION (mg/l) CONCENTRATION (mg/II 4- —4 7410 ~ 948 6420 7430 8419 2 1-26 " 2 15 '— 12417 DATE (197241973) FIGURE 19.—Variables observed during passage of waste front in well 14. 21 decreases in wellhead pressure difference in the injec- tion zone between the injection well I—7A and well 14 and (2) the decrease in DOC in well 14. Gas efferves- cence was defined as the volume of gas which evolved from an equivalent volume of water under atmospheric pressure at the sampling site. From June through October 1972, the waste content (DOC) in well 14 appeared to be increasing (fig. 19); however, the waste content abruptly decreased at the beginning of November and there was no sign of waste in the well by late January 197 3. Although there were large pressure variations caused by variations in the injection rate during conversion to surface treatment, the DOC tended to decrease as the pressure difference decreased. This direct relationship between DOC and pressure difference indicated some change in the ground-water flow system with the cessation of waste injection. The first period (June 20 to August 1) of increasing waste concentration showed only an increase in DOC as evidence of waste in the well. No gas was found in a sample collected on August 1, but gas appeared ab- ruptly in a sample collected only 2 days later. For the period August 3 to October 31, the amount of gas con- tinued to increase as DOC increased, and throughout November, the amount of gas decreased as DOC de- creased until there was no gas present in the well early in December. A summary of the gas analyses obtained during this period is given in table 7. TABLE 7. — Well 14 gas analyses [N .d., not detected] Percent of total gas volume Date of sampling Ha N2 CH4 CO: HnS 8-1-72 N.d. 25 50 11 N.d. 8-7-72 N.d. 21 54 11 N.d. 8-14-72 0.2 36 40 11 0.8 10-11-72 N.d. 68 6.0 4.8 N.d. 11-2-72 N.d. 64 33 3.8 N.d. 1 1-22-72 N.d. 68 12 1.5 N.d. The appearance of gas, which contained methane concentrations up to 54 percent of the total gas vol- ume, was the first indication of anaerobic microbial decomposition of the organic waste. The following reactions show how acetic and formic acid are con- verted to methane by the microorganisms: a. CH3000H +H20 ——)CH4 +H2003 (Lawrence and McCarty, 1969) b. 4HCOOH +H20 ——)CH4 +3HzCOa (Siebert and Hattingh, 1967) The most probable reason why microbial degrada- tion of the waste did not begin immediately with the appearance of the waste is because there is a time lag during which the microbes are building up numbers large enough to significantly degrade the waste. 22 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA The total iron concentration plotted in figure 19 is very closely related to the waste concentration. Oborn and Hem (1961) suggest that microbial activity re- sulting from organic substrates can indirectly in- crease the iron concentration by a two-stage process: (1) Microbial oxidation of waste to carbon dioxide and water lowers Eh by oxygen depletion and lowers pH by solution of carbon dioxide; (2) lowering of Eh and pH converts insoluble ferric iron to more soluble fer- rous iron. Iron may also be brought into solution by complexation with the aromatic dicarboxylic acids found in the waste (Ringbom, 1963). A likely com- plexation reaction is shown below: _ 2 — 2 O O 0 “(2-0 \\c—o\ lo—c” 2 Ci 9 CE )3 c—o c —o’ ‘o—c /, x/ \\ O O 0 phthalic acid phthalic acid-ferrous iron anlon complex anion In samples collected up to September 4, 1972, there was considerable evidence of microbial sulfate reduc- tion to sulfide in the form of black sulfide precipitates and the hydrogen sulfide gas found during the gas analysis. In later samples, sulfide precipitates and hydrogen sulfide gas were absent, and the level of dissolved iron increased, possibly because insoluble ferrous sulfide precipitates were no longer forming. Waksman (1952) showed how sulfate can be reduced with the microorganisms using acetic acid as a source of energy: CaSO4 +CHaCOOH ——) H2S +CaCOs +002 +HzO. Methane production, iron reduction, and sulfur re- duction are believed to be indicators of anaerobic mi- crobial activity induced by waste concentrations in the ground water. These waste degradation reactions are a strong confirmation of the microbial activity zone in the waste front which was postulated in the initial conceptual model. One of the most important aspects of this study was to define changes in the organic composition of the waste as it traveled from the injection well to an observation well. Acetic acid, formic acid, p-toluic acid, and terephthalic acid were determined on water samples collected from wells 11, 14, and 15 during waste contamination. Formaldehyde and phthalic acid were not found in samples obtained from these wells, and methanol was not determined because there was no way to quantitatively concentrate or extract methanol from the ground-water samples for its determination. Benzoic acid, succinic acid, and methylsuccinic acid were found in trace amounts in several samples, but were not quantitatively deter- mined. The concentration curves for acetic acid, p-toluic acid, and terephthalic acid closely follow the DOC concentration curve in figure 19 for well 14. However, the formic acid concentration curve did not peak at the October 31 sample as did the other parameters. To determine the changes in the relative composi- tion of the organic waste constituents, the percentage of DOC was computed for acetic acid, formic acid, p-toluic acid, and terephthalic acid for each individual analysis in wells 11, 14, and 15; then the percentages were averaged for each well and compared with the averaged waste percentage DOC composition for these constituents. The results are shown in table 8. TABLE 8.—Relative organic composition of injected waste found in wells 11, 14, and 15 [N.d., not detected] Percentage of DOC Constituent Waste Before injection Well 11 Well 14 Well 15 Acetic Acid .................... 52.6 73.5 78.7 72.5 Formic Acid .............. 11.4 N.d. .4 N.d. p-Toluic Acid ................ 11.3 N.d 2.7 5.9 Terephthalic Acid ........ 3.6 1.9 .9 1.5 Of the four organic compounds determined in well 14, the inorganic salts of acetic and formic acids are the most soluble in the ground water, and they should not be significantly adsorbed by aquifer constituents after waste injection. Acetic acid (sodium acetate) comprises the majority of the DOC found in well 14, but formic acid (sodium formate) only constitutes 0.4 percent whereas it constitutes 11.4 percent of the DOC in the injected waste. Assuming that the rela- tive composition of the injected waste was fairly con- stant during the 41/2 years of waste injection, formic acid must have decomposed during the time it traveled from the injection well to well 14. The non- characteristic formic acid concentration curve in fig- ure 19 also indicates formic acid degradation within well 14. Siebert and Hattingh (1967) stated that for- mic acid appears to play a central part in the forma- tion of methane, and is the organic compound most readily converted to methane by anaerobic bacteria. The percentage composition for p—toluic acid and terephthalic acid also decreases in samples obtained in well 14 as compared to the injected waste (table 8). Because aromatic acids are much less biodegradable than aliphatic acids, it is likely that p-toluic acid and terephthalic acid are depleted during waste move- ment in the subsurface by adsorption on the aquifer sediments rather than being depleted by microbiolog- ical degradation. Terephthalic acid and p-toluic acid are much less water soluble than acetic and formic acid and therefore are more easily adsorbed. Indications of waste in well 11 appeared in De- cember 1972 and samples were collected for analysis WASTE-AQUIFER INTERACTIONS 23 from January through July 1973. The waste concen- tration as represented by the DOC curve increased very slowly in almost a linear manner during this period as shown in figure 20. Plots of concentration versus time are also given for acetic acid, terephthalic acid, and dissolved iron in figure 20. Formic acid, formaldehyde, and p-toluic acid were not detected in water samples from this well. There was no gas pro- duced or evidence of sulfate reduction. The dissolved iron concentration curve does not show any discerna- ble correlation with the waste concentration. Dis- solved iron was essentially constant while the waste concentration was increasing. Apparently the waste concentration did not become sufficiently high to induce microbial waste degrada- tion as was found in well 14. In well 14, the first evidence of microbial waste degradation, methane gas, occurred when the DOC concentration was at about 25 mg/l. The highest DOC concentration in well 11 was only 18 mg/l. Therefore, as in well 14, mi- crobiological waste degradation does not seem to occur below a threshold level of waste concentration. Both the acetic acid and terephthalic acid concen- tration curves increase in the same manner as the DOC curve in figure 20. Acetic acid constitutes about the same percentage of the DOC in well 11 as in well z _ 9 s— - z i- —15 o < 7— m A E - m s a s- ' SE 2 9 g A — Z 0 q 5— —10 < F. o a: . . q 0 <1 2 E 4 O Dissolved Iron CE I g 0 Dissolved organic d g E ‘ 3_ carbon _ Lu I“) D > 2 Lu _5 _| O > 2._ O U -‘ ' m 0 . 9 .8 1-— . D D 40— 30— . Acetic acid 0 Terephthalic acid ACETIC ACID CONCENTRATloN (mg/l) TEREPHTHALIC ACID CONCENTRATION (mg/I) I | | | l | I I | | I | 3—21 4—30 6-9r 7—19 8—28 4-10 5-20 6—29 8—8 DATE (1973) FIGURE 20.—Constituents measured during passage of waste front in well 11. 14; however, terephthalic acid was present in greater relative amounts, whereas p-toluic acid was not even detected (table 8). The relative abundance of terephthalic acid to p-toluic acid was reversed for the few samples collected from well 15 although the per- centage of DOC due to acetic acid was about the same as for wells 11 and 14. The different ratios of terephthalic acid to p-toluic acid in each of these three wells leads one to question the assumption that the waste composition was essen- tially constant during the 4% years of waste injection. It is most probable that the organic waste collected from wells 11, 14, and 15 was injected at three differ- ent points in time and contained different ratios of terephthalic to p-toluic acid. It is remarkable that the acetic acid contribution to DOC is about the same in these three wells as is shown in table 8. Regardless of the wide variations of the ratio of terephthalic acid to p-toluic acid in samples obtained from these three wells, both terephthalic and p-toluic acids were below concentrations at which they were found in the in- jected waste. It is likely that these compounds were adsorbed by aquifer sediments during their travel from the injection well to the observation well. POSSIBLE FLOW SYSTEMS ASSOCIATED WITH INJECTION ACTIVITIES The history of waste concentrations in wells 11, 14, and 15 suggests that the ground-water flow system associated with injection activities is very complex both vertically and areally in the injection zone. In addition, a true measure of waste concentrations could not be obtained because the 150-ft (45-m) screened section of the observation wells permitted cross-circulation and dilution of waste-contaminated ground water with uncontaminated ground water, and it is very unlikely that the injected waste moved in uniform directions and rates in all permeable zones within the injection interval. Examination of the driller’s logs (Black, Crow, and Eidsness, Inc., 1971) of wells 7, I—7A, 11, and 12 show that from two to four permeable zones may exist at different points within the injection interval. Insuffi— cient hydraulic data exist at this site to define the natural, preinjection flow system, and it is unknown whether the multiple permeable zones within the in- jection interval are interconnected and have the same artesian head, or whether they are independent and there is a differential, vertical distribution of head through the injection interval. The complex hy- drogeology, the lack of hydraulic data, sampling lim- itations imposed by observation well construction, and the complexity introduced by waste injection at various rates and pressures at multiple sites all pro- hibit the modeling of injected-waste movement, and 24 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA only various possibilities can be presented in this re- port. A realistic hypothetical portrayal of the limits of waste movement at the upper and lower boundaries of the injection zone is represented in figure 21. The amoebic shapes of the areal waste distributions is intended to represent waste movement in directions of highest permeability. Non-coincidence of the lower boundary with the upper boundary shows that waste at the bottom of the injection zone may be moving in a different lithologic unit in directions independent of the waste in the upper part of the injection zone. The areal extent of the waste is represented to be much greater at the upper boundary of the injection zone because the specific gravity of the waste is less than the native ground water. However, if the permeabil- ity of the injection zone is greater near the lower HA [Ll-TOAD 0 1000 2000 FEET 0 300 600 M ETR ES EXPLANATION Injection well A Observation well — Injection zone ‘ Observation well — 700»foot zone 0 Observation well ‘— SOD-foot zone © Observation well used as injection well Original system Limit of waste travel (upper boundary) — —— — Limit of waste travel (lower boundary) FIGURE 21.—Hypothetical areal distribution of waste at the upper and lower boundaries of the injection zone. boundary, the relative sizes of the areas invaded by the waste may be opposite from that shown in figure 21. Because the major quantity of waste was injected through wells LG, 4, and 5, the areal waste distribu— tion is biased around this cluster of injection wells rather than around injection well I—7 A, where a lesser quantity of waste was injected. Lastly, because waste injection occurred at multiple sites, the formation of “pools” of uncontaminated ground water surrounded by waste is also shown in figure 21. Changes which occurred in the waste content in samples obtained from wells 11, 14, and 15 during the 2 months after the cessation of waste injection indi- cated either a major change in waste distribution, or a change in water being sampled by these wells. Therefore, the last experiment performed for the site study was to allow wells 11, 14, and 15 to flow on November 1—2, 1973, to determine if waste could be drawn into these wells. It was hypothesized that if waste did not reappear after withdrawing a limited quantity of ground water, the waste distribution had likely changed. However, if waste appeared after a short period of well flow, it is likely that the disap— pearance of waste with termination of injection re- sulted from changes in internal circulation of ground water within and adjacent to the observation well. This internal circulation is diagrammed in figure 22. Allowing the well to flow should withdraw water from all the permeable zones within the injection zone, which is screened from 850 to 1,000 ft (259—305 In) in the observation wells. The wells were allowed to flow by disconnecting the pressure gages and opening the 1-inch ball valve on the wellhead assemblies. The results of this flow test are summarized in table 9. TABLE 9. — Observation well flow-test data [Nd., not detected] Flow Total Acetic Fannie p-Toluic Terephthalic Sample period flow DOC acid acid acid acid No. (min) (gal) (mg/l) (mg/l) (mg/1) mg/l) (mg/l) Well-11 (flow rate = 25 gal/min) 1 0 0 18 38 N.d. N.d. 0.58 2 235 5,875 75 107.4 2.16 2.71 2.75 3 400 10,000 90 160.1 2.76 2.16 2.61 4 1,050 26,250 170 201.3 3.61 4.43 3.44 5 1,190 29,750 185 348.0 6.63 5.07 3.74 Well-14(flow rate = 10 gal/min) 1 0 0 1.0 — — — - 2 270 2,700 1.0 —— — —— — 3 435 4,350 1.0 — — — - 4 1,075 10,750 1.0 — — — — 5 1,255 12,550 2.0 — — — - Well-15(flow rate = 60 gal/min 1 0 0 1.0 — — ._ _ 2 160 9,600 5.0 — — — — 3 375 22,500 47.0 73.45 1.54 1.24 1.06 The flow from well 15 was stopped after 375 minutes because of concern about the withdrawn saltwater in- filtrating to the supply wells. Because this well had the highest flow rate of about 60 gal/min (227 l/min), enough water was withdrawn from this Well in this period of time to pull the waste into the well. The last WASTE—AQUIFER INTERACTIONS 25 sample taken had a DOC of 47 mg/l and contained acetic acid, formic acid, terephthalic acid, and p-toluic acid in the amounts shown in table 7. Well 11 initially contained a small amount of waste at the beginning of the flow period, and the amount of During waste injection After waste injection saw—g." 2" PVC screens 5-mi- L \\\\\\\\\\\V fillllflfllllljml Silica sand Bedroc //// EXPLANATION Sand and gravel Clay Pressure gradient Direction of ground water flow W Injected waste FIGURE 22.—Probable internal circulation of ground water within well 14. waste increased steadily during the flow period to the last sample, which had a DOC of 185 mg/l. The relative composition of the organic constituents changed in each successive sample. Formic acid and p-toluic acid appeared in sample two, whereas they were not de- tected at the beginning of flow. By the end of the flow period, the ratio of terephthalic acid to p-toluic acid had reversed with p-toluic acid being present in the greater concentration. A gas sample obtained during the period the well was flowing contained methane at a concentration of 18 percent of the gas volume (basic- data table 33). The presence of methane indicated that microbiological waste degradation was occurring in the injection zone near well 11, although the waste concentrations were not high enough in well 11 to induce methane formation before flow was started. Waste was not drawn into well 14 during the period of flow. The flow rate of well 14 was only 10 gal/min (38 l/m) and table 7 shows that only about half as much water was withdrawn from well 14 as was withdrawn from wells 11 and 15. A gas sample was obtained which contained methane at 30 percent by volume (basic-data table 33), but this methane only indicated that waste had been present at a previous period in the injection zone. Methane apparently exists as a gas at the pres- sure found in the injection zone, and this gas was entrapped by the aquifer sediments and did not move away from the well with the waste when internal cir- culation displaced waste from the well. It is quite likely that waste would have been drawn into well 14 if it had been allowed to flow for another day and a volume of ground water equivalent to wells 11 and 15 had been withdrawn. The results of the observation well flow experiment tended to confirm the hypothesis that waste was in the immediate vicinity of wells 11, 15, and most likely well 14. It is still possible that after injection stopped, the areal distribution of waste as shown in figure 21 changed because of the influence of the natural, re- gional flow system in moving the waste away from the observation wells. However, it would be unlikely that the waste would move in such a manner that it would quickly reappear when the wells were allowed to flow. In the opinion of the authors, the disappearance of waste was a result of internal circulation changes within the screened section of the observation wells, thus preventing waste from being drawn into the sam- pling tube. This experiment shows that in a study of this type an observation well which has its screened section opened to several water-bearing zones may not serve its purpose as an observation well because it may not yield injected waste at low-flow rates of the sam- pling tubes; thus when the dominant proportion of the waste is present in one of the zones, the samples ob- tained may not be representative. 26 MICROBIOLOGICAL STUDY The results of the microbiological study are in a report by DiTommaso and Elkan (1973), and only the significant findings will be discussed in this report. The waste, prior to injection, was found to be void of any bacterial contamination. Likewise, samples ob- tained from observation wells containing high levels of waste did not support microbial flora. Approximately 3,000 organisms per millilitre were present in water samples obtained from the uncontaminated injection zone, and this count remained constant for the dura- tion of the study. This count was somewhat high ac- cording to G. G. Ehrlich (oral commun., 1973), who cited a range of 10—1,000 microorganisms per millilitre as representative for uncontaminated ground waters. These native organisms were isolated and identified as shown in table 10. Although anaerobic, methanogenic bacteria were found in certain waste-contaminated wells, most of the organisms isolated from the uncon- taminated wells were facultative or aerobic genera rather representative of the normal microflora of aquatic environments. The most common genera found included Agrobac- terium, Pseudomonas, Proteus, Bacillus, Aerobacter, Corynebacter, Arthrobacter, and M icrococcus. In labo- ratory studies, isolates of these genera, either singly or in combination, were inoculated into a medium in which various dilutions of the waste served as the sole carbon and energy source. None of these well isolates were able to grow and decompose waste under these conditions. In addition to these microorganisms, a very low number of obligate anaerobes were detected. Be- cause there is little or no organic-energy substrate in the uncontaminated injection zone, these obligate anaerobes can be present only in limited number. When a readily available carbon and energy source was added in the form of the injected waste, these anaerobes increased in number and constituted the waste-decomposing microflora. On July 7, 1972, a 20-week study was initiated to study bacterial decomposition of waste which was oc- curring at that time in well 14 as was evidenced by SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA methane gas formation. A rapid increase in the micro- bial population resulting from the presence of dilute concentrations of waste in well 14 occurred during the 20-week period, and this increase is shown graphically in figure 23. The colony-forming units per millilitre in the control well (well 11) remained approximately con- stant at 3,000 organisms per millilitre, whereas in well 14, the population increased to approximately 1,000,000 organisms per millilitre. I 10"— WaIl 14 (in waste front) COLONY FORMING UNITS/ml 10‘ Well 11 I | I I | 12 16 20 TIME, IN WEEKS 24 FIGURE 23.—Comparison of number of bacteria per millilitre (as colony-forming units) in waste front (well 14) and in uncontami- nated aquifer (well 11). Methanogenic bacteria were isolated in pure culture from water samples obtained from well 14 during the 20-week study. Gram stains were performed in an at- tempt to classify these bacteria according to genus. Two different morphologic types were observed. The first was a gram-negative, slightly-curved rod, which was tentatively placed in the genus Methanobacte- TABLE 10.—Identification of isolates from uncontaminated deep well 11 [— , negative reaction; + , positive reaction; A, acid produced; A", weak positive reaction; AG, acid and gas produced] Carbohydrate utilization Organism Sulfide RedUCtiOD Catalase Starch Indole Identified Gram stain Morphology Motility production of nitrate production hydrolysis production Sucrose Mannitol Lactose Glucose Maltese Agrobacterium — Rod + — — + — — — — — A A* Pseudomonas — Rod + — + + — — A AG AG AG AG Proteus — Red + — + + - — A AG AG A AG Bacillus + Rod — — + + + — — A* A* A A Aerobacter — Rod — — + + — — A AG AG AG AG Corynebacter + Rod — — + + — — A A A — Arthrobacter — Rod — + + + A A A A A Micrococcus + Cocci — — + + — — — — A A A Pseudomonas fluorescens — Rod + — + + + — —— — — — A* group LABORATORY WASTE-AQUIFER REACTIVITY STUDIES 27 rium. The other was a coccus which was gram positive and occurred in masses; it was tentatively placed in the genus Methanococcus. Although the waste was found to be decomposable by microorganisms, the system appeared to have low effi- ciency. Laboratory studies showed the waste to be toxic even in moderate concentrations. The major localization of waste decomposition was found in wells located at the periphery of the waste front where the waste is highly dilute. The site study of waste-aquifer interactions provided qualitative evidence for a number of reactions and waste-decomposition processes which have occurred in the subsurface as the result of waste injection. A labora- tory study was conducted which simulated waste injec— tion into cores of aquifer material obtained from the injection zone. The objectives of this study were: (1) To better define the waste-aquifer interactions in a quan- titative manner, (2) to substantiate in the laboratory waste-aquifer interactions which were observed on-site, and (3) to test for waste-aquifer interactions which could not be observed on-site because of the construction and placement of the observation wells. LABORATORY WASTE-AQUIFER REACTIVITY STUDIES INTRODUCTION The disposal site at Wilmington, N .C., offered a de- sirable and somewhat unique situation to study the chemical and microbial aspects of subsurface waste injection because of the large number of observation wells. The movement and the reactions occurring be- tween the waste and the disposal aquifer could be studied at various stages of the passage of the waste through or past observation wells. Most injection-well systems do not have observation wells which can be used for waste monitoring; therefore other means must be employed to gain an insight on waste movement and reactivity. A possible means of evaluating waste reactivity is to conduct waste-aquifer reactivity studies in the labora- tory. Such studies are usually conducted during the initial stages of injection-well construction to evaluate the “compatibililty” of the waste with the receiving zone. These tests are essentially engineering oriented, are usually simplistic in nature, and are somewhat analogous to comparative permeability testing with the native ground water and the waste. A positive compatibility is achieved if the permeability of the waste saturated core is the same as or greater than that of the native ground water. A negative compati- bility, or a decrease in permeability of the waste- saturated core could result from precipitation or coagu- lation of the waste, a reduction in porosity due to dis- persion and plugging with aquifer or waste solids, the swelling of aquifer solids, or other reactions which decrease the porosity of the core matrix. The laboratory waste-aquifer reactivity tests in this study were designed to evaluate organic and geochem- ical reactions instead of the ordinary compatability testing such as changes in permeability and hydraulic conductivity. The general objectives of the laboratory tests were to determine (1) if the passage of the waste front through the injection zone could be simulated in the laboratory; (2) if the chemical and physical reac- tions which were predicted to occur between the waste and the aquifer materials in the receiving zone at the injection site would occur under laboratory conditions; and (3) to determine how well laboratory findings cor- related with field data and observations. METHODS AND MATERIALS AQUI FER MATERIAL During the drilling of observation well 12, cores were taken from various depths. Coring of the poorly consolidated, sandy receiving zone at 960 ft (293 m) was difficult, but several kilograms of aquifer material was obtained by screening. This material was sealed in a plastic container and remained moist until labora- tory studies were conducted. CHARACTERIZATION OF AQUIFER MATERIAL The chemical and physical properties of the aquifer material from the receiving zone were characterized by several methods. Particle size analysis was ac- complished by wet-sieving and sedimentation after mechanical dispersion at pH 9.5 with NaOH. Aquifer pH was determined on duplicate 10-gram samples in deionized water with a solidzliquid ratio of 1:1. The suspensions were allowed to stand for 1 hour and stirred during reading of pH. Free iron was determined by the citratedithionite method of Mehra and Jackson (1960), total Kjeldahl nitrogen by the method of McKenzie and Wallace (1954), and organic and inor- ganic carbon by the method of Malcolm and others (1973). Mineralogical analyses were accomplished by X-ray diffraction and thin-section techniques. X-ray diffrac- tion analyses were conducted by the authors on size- fractionated, K-saturated and Mg—saturated samples placed on ceramic mounts by the method of Kunzie and Rich (1959). Thin-section analyses and porosity and specific gravity determinations were performed by the US. Geological Survey Hydrologic Laboratory in Den- ver, Colo. WASTE CONSTITUENT ANALYSES A bulk sample of the industrial organic waste was obtained from Wilmington, N .C., on November 7, 1973. The organic and inorganic analyses of this sample as 28 presented in tables 3 and 4 show that the sample is representative of the injected waste. All the methods for specific organic component identification and DOC in the original waste and the reacted effluent waste from the laboratory aquifer-waste reactivity tests were performed as described in the previous method section. The identification of organic components sorbed on the aquifer material during testing was accomplished by placing 10 grams of aquifer-core material into a 250-ml glass Erlenmeyer flask, acidification to pH 1 with H2304, and triple extraction with 100-ml portions of ether after 24—hour equilibration at room temperature. Specific conductance and pH were determined on standardized laboratory equipment. Total iron, silica, and sulphate were determined by the authors by stan- dardized Technicon Autoanalyzer procedures. Sodium, calcium, magnesium, and chloride were determined on the reacted waste effluent by the US. Geological Sur- vey Central Laboratory in Salt Lake City, Utah. MODIFIED HASSLER SLEEVE CORE HOLDER The laboratory waste-aquifer reactivity studies were conducted in a modified Hassler sleeve core holder as shown in figure 24. The core tester was designed ac- cording to the general specifications as supplied by Charles D. Haynes of Austin, Texas. The advantages of this design include the testing of large amounts of core material of various sizes and lengths, the use of rubber, plastic, or Teflon sleeves, and the implementation of confining pressure, which is analogous to overburden pressure and (or) hydrostatic pressure, if Teflon sleeves are used. This design also enables the maintenance of a pressure differential between the confining pressure and the internal core pressure. PRESSURIZATION CORE-TESTING APPARATUS The schematic of the pressurization core-testing ap- paratus is shown in figure 25. The apparatus is pres- surized with nitrogen gas from a large reservoir tank. The conversion of gas pressure to hydrostatic pressure in the hydraulic separator and the liquid accumulator End cap 6 Confining Pressure FIGURE 24.—Diagram of modified Hassler sleeve core holder. SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA E Liquid Collection FIGURE 25.—Schematic diagram of pressurization core-testing appa- ratus. tank prevents possible problems with entrained gases within the core or possible air leaks from the confining pressure reservoir into the sleeve core holder. The driv- ing force for the movement of liquid through the aquifer material is hydraulic pressure from the hy- draulic separator. The maintenance of a constant and accurate gas pressure to within 2 psi at 500 psi was accomplished by a Grove pressure regulator and a United States mirrored scaled gage. Adequate valving arrangements enabled the refill- ing of the hydraulic separator from a plastic liquid refilling reservoir while maintaining a constant high pressure within the core holder. The conductivity and temperature of the core effluent were monitored with inline sensors at the outlet of the core holder. All com- ponents were connected with 0.125 inch (3.17 mm) stainless steel tubing except the tygon tubing for col- lection and monitoring of the reacted waste effluent from the core holder. EXPERIMENTAL DESIGN In order to accomplish the laboratory waste-aquifer reactivity experimental objectives, three experiments were conducted. Experiments 1 and 3 emphasized chemical changes which were manifested by changes in the liquid waste, whereas experiment 2 emphasized chemical reactivity which could be manifested by chemical and physical changes within the aquifer core material. Experiment 1 was designed to simulate the passage of the waste front through an observation well or a given static point within a waste-receiving zone. The Teflon sleeve of the core holder was packed with aquifer material and the waste injected into the pres- surized core at a rate of 2 ml/hr which approximated a waste movement under field conditions of 0.6 ft/day (0.2 m/day). Experiment 2 was designed to simulate changes which would be manifested within the aquifer core LABORATORY WASTE-AQUIFER REACTIVITY STUDIES 29 material with passage of the waste front extending into the slow-reactivity zone. To accomplish this, waste was injected into a pressurized aquifer core at a flow rate of 4 ml/hr, which approximated a waste movement under field conditions of 1.25 ft/day (0.38 m/day). The organic and inorganic composition of the reacted waste effluent was monitored as in experiment 1. At the end of experiment 2, the reacted core was fractionated into eight equal sections and analyzed for physical and chemical changes. Experiment 3 was designed to simulate changes which a unit of the very front edge of the injected waste would undergo as it moved outward through the injec- tion zone from the injection well. To accomplish this objective, a given amount of waste was passed or injected through successive fresh cores of aquifer material. TESTING THE PRESSURIZATION CORE-TESTING APPARATUS LEAK TESTING The Hassler sleeve core holder was designed to ac- cept Teflon sleeves. It was assumed that a confining pressure, simulating overburden pressure, greater by 150 to 200 psi (pounds per square inch) than the inter- nal core pressure, simulating bottom hole injection pressure, would facilitate the seal between the end of the Teflon sleeve and the core-holder plug. The appli- cation of appropriate confining pressure greater than internal core pressure may also prevent channeling at the interface between the core material and the Teflon sleeve. The core-testing apparatus was first tested with sand in the core holder. Internal core pressure and confining pressure were adjusted to 450 and 600 psi, respectively. Chloride breakthrough curves, conductiv- ity breakthrough curves, and the drop in water level within the accumulator tank indicated leakage. With confining pressure exceeding the internal core pres- sure by 150 psi, the 1.5-inch (38.1-mm) Teflon sleeve with 0.094-inch (0.38-mm) wall thickness was slightly deformed, which probably added to the leakage at the plug seal. An increase in the milled thickness of the Teflon sleeve, variation in packing and tightening of the core holder, and the reduction of confining pressure to that of internal core pressure at 450 psi failed to solve the initial leakage problem. The leakage problem was resolved by milling a 2 degree undersize taper on both ends of a thicker walled (0.187 inch or 4.75 mm), more rigid Teflon sleeve with confining and internal pressures both at 500 psi. A sodium chloride solution conductivity breakthrough curve for medium sand in this sleeve at a flow rate of 100 ml/hr is shown in figure 26. After the specific conductance of the effluent salt solution was essentially the same as the input solution, the flow was stopped, and the core allowed to stand under pressure for a 15-hour period. After standing, the specific conductance of the effluent remained con- stant at the value of the specific conductance of the input salt solution. This test insured a leakproof sys- tem for the waste-aquifer core reactivity experiments. During the initial pressurization of the core holder with confining and internal pressure, it is essential to increase both pressures at the same rate or possible leakage will occur at the junction of the end plug and the Teflon sleeve. It is also essential that during the refilling of the hydraulic separator with fresh waste during experiments 1 and 2 that the confining pressure and internal core pressure remain constant at 500 psi. Adequate valving isolates the core holder from the hydraulic separator. After filling the hydraulic separator, that portion of the system is first returned to 500 psi before simultaneously returning the confining and internal core pressure to the entire system. PACKING THE TEFLON SLEEVE WITH AQUIFER MATERIAL The aquifer material used in the laboratory studies was maintained in a moist condition (approximately 11 percent moisture by weight) in a sealed plastic con- tainer until used for experimentation. The moisture in the aquifer sample was diluted native ground water. In preparation for sleeve packing, the top tightening ring was placed on the top end plug. The Teflon sleeve was fitted snugly to the end plug and held in place by a ring stand clamp. Small portions of representative aquifer material were packed into the Teflon sleeve with a glass rod until the sleeve was approximately 24,000 I 18,000— 12.000— SPECIFIC CONDUCTANCE. IN MICROMHOS PER CENTIMETRE AT 25° C 01 O O O I FORE VOLUMES 1 2 3 4 I I | 0 I I I I U 75 150 225 300 EFFLUENT VOLUME, IN MILLILITRES FIGURE 26.—Specific conductance breakthrough curve during leak- testing of Hassler sleeve core holder. 30 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA one-fourth filled. In experiments 1 and 2, native ground water was slowly introduced into the sleeve from the bottom through the end plug displacing most of the air within the column. Ground water addition was stopped when the water level reached the upper- most surface of the aquifer material. This process was repeated several times until the Teflon sleeve was filled with aquifer material. A stainless steel screen was then placed on top of the aquifer material. The packed sleeve was inserted into the body of the core holder and both ends screwed tight. The core holder with packed sleeve in place was inverted and secured into place such that the screen was then at the bottom of the column. In experiments 1 and 2, the packed core was equili- brated with over 500 ml of native ground water before introduction of the industrial waste. A minimum dilution of the injected waste by native ground water was desired in experiment 3. The four cores in this experiment were packed only with firm tapping with a glass rod. The reacted waste from each successive pass through previous cores was slowly in- troduced into the bottom of the new core at low pres- sure. The waste slowly filled the packed core displacing the entrained air. After the column was filled, the stainless steel screen centered into place, the end plug inserted and tightened, the core holder was inverted and then pressurized. All experiments were conducted with confining pres- sure and internal core pressure remaining constant at 500 psi. The same Teflon sleeve, which was 13 inches (330 mm) in length, 1.25 inches (3.17 mm) inside diameter, and 0.187 inches (4.75 mm) in thickness, was used in all experiments. The packed core of aquifer material in each experiment was approximately 11.75 inches (295 mm) in length, 410 grams in weight on an oven dry basis having a specific gravity of 2.68 g/cm3, and a pore space of 33 percent, which resulted in a calculated pore volume of 76 ml. The compressibility at 500 psi was approximately 2 percent. The dead volume in the effluent end of the column was approximately 5 ml. All laboratory experiments were conducted at room temperature, which fluctuated within i3°C of 25°C. This temperature approximated the temperature within the receiving zone at the injection site. EXPERIMENT l—KINETIC STUDY OF WASTE This experiment was designed to simulate the pas- sage of a waste front through an observation well or a static point within a waste-receiving zone. Sampling during experiment 1 as shown in table 11 was con- ducted by collecting increment samples at 5-hour intervals over a 6-day period at an average flow rate of 2 ml/hr. The actual flow rate during the 10-ml sample collection was approximately 15—20 ml/hr. Analyses were performed on the waste effluent, but no analyses were performed on the core material at the end of the experiment. The inorganic aspects of experiment 1 were essen- tially duplicated in the waste effluent monitoring por- tion of experiment 2 with the exception that the flow rate was 4 ml/hr with the collection of a 20-ml sample every 5 hours. The inorganic waste effluent composi- tion of experiment 2 will be discussed along with ex- periment 1. The breakthrough data and breakthrough curves for DOC, chloride, and sodium as shown in tables 11 and 12 and figures 27 and 28, respectively, indicate that the pore volume of each experiment is between 70 and 80 ml, which verifies the calculated value of 76 ml. The experimental pore volume is substantiated by the coin- cidence of the inflection point of the breakthrough curves and the 50 percent concentration factor, both of which are suggestions of pore volume. The break- through curve for chloride should be the same or pre- cede the DOC breakthrough, because some organic material is sorbed, whereas chloride is not. This ap- pears to be the case in experiment 2, but both chloride and sodium lag DOC in experiment 1. The apparent discrepancy may be due to the fact that most parame- ters such as DOC, chloride, and sodium can be more accurately determined at low to moderate concentra- tions than at high concentrations. DOC concentrations are low and chloride concentrations are high at the initial portion of the breakthrough curve. The insen- sitivity of the chloride data is also suggested by large changes in pH and DOC while the chloride concentra- tion remains constant. The DOC breakthrough lags the chloride and sodium breakthrough throughout experiment 2 and for the greater portion of experiment 1. The lag of the DOC is much more pronounced with decreasing pH of the effluent waste. Increased sorption of organics on the core with decreasing pH is expected as physical sorp- tion and anion exchange is facilitated at lower pH’s. The marked solubilization of Fe and Si02 is shown in tables 11 and 12 and figures 29 and 30. Silica dissolu- tion precedes Fe dissolution and then reaches a steady state concentration of near 70 mg/l. Silica solubiliza- tion appears to be somewhat independent of Fe sol- ubilization, is independent of pH effects in the pH range of 5-7 in the experiments, and appears to be initially dependent only on the concentration of the waste. Fe dissolution on the other hand appears to be more dependent on pH than DOC concentration be- cause no solubilization occurs until the pH of the aquifer core material is reduced to approximately pH 6. Below pH 6, Fe solubilization appears to be pH independent, but is dependent upon the kinetics of LABORATORY WASTE-AQUIFER REACTIVITY STUDIES TABLE 11.——-Laboratorv chemical data for waste-aquifer reactivity experiment 1 (flow rate =2 mllhr). 3 1 Specific Concentration in mg/l Cumulative Conductance Time Fraction volume (nmhos/cm (hr) number (ml) at 25°C) pH DOC Fe Si Na Ca Mg Cl 0 1 10 31,100 6.70 190 0.3 12 7000 490 290 12,000 5 2 20 32,000 7.60 76 0.3 13 7100 430 300 12,000 10 3 30 31,200 7.65 170 0.5 14 7000 450 310 12,000 15 4 40 30,500 7.30 590 1.1 16 7200 580 310 12,000 20 5 50 30,000 7.20 1100 0.6 22 6700 730 330 12,000 25 6 60 28,100 7.15 1900 0.3 27 6300 920 340 11,000 30 7 70 26,900 7.00 2500 1.6 34 — — —- — 35 8 80 25,000 6.85 3200 0.4 39 5200 1500 330 7,600 40 9 90 22,500 6.80 4100 1.4 43 — — — —— 45 10 100 21,100 6.80 4400 0.8 47 3900 2200 310 5,400 50 11 110 19,200 6.20 5000 29 51 3090 2300 278 4,200 55 12 120 18,000 6.10 5600 — 54 — — — — 60 13 130 16,900 6.10 5800 48 57 2190 — 238 2,900 65 14 140 15,600 6.10 6100 — 60 — — — 70 15 150 14,600 5.90 6500 73 63 — — — — 75 16 160 14,200 5.85 6800 —-— 63 1290 3200 188 1,600 80 17 170 13,700 5.80 6800 90 61 ——- — — — 85 18 180 13,600 5.75 6900 94 64 — — — — 90 19 190 13,200 5.70 7100 112 66 — — — 95 20 200 12,800 5.60 7200 121 68 720 3900 158 753 100 21 210 12,600 5.55 7200 129 69 — — — — 105 22 220 12,700 5.50 7100 139 70 — — — — 110 23 230 12,600 5.45 7400 142 70 — — — — 115 24 240 12,400 5.40 7500 151 71 310 4200 128 353 120 25 250 12,000 5.35 7500 161 72 — — — — 125 26 260 12,500 5.30 7600 167 71 — — — — 130 27 270 11,900 5.30 7600 167 72 — — — 135 28 280 12,000 5.28 7600 180 72 110 4200 108 133 140 29 290 11,750 5.28 7700 183 73 — — — — 145 30 300 11,600 5.25 7700 202 73 40 4300 100 83 dissolution as shown by flow rate relationships. At the high flow rate during experiment 2, the Fe concentra- tion reached a steady state of approximately 115 mg/l. During experiment 1 at low flow rate, the Fe concent- ration kept increasing in a curvilinear fashion to above 200 mg/l. Total and corrected values for Fe and Si concentra- 8000 — 6000 — 2000 4000 — 4000 0 Doe I Chloride 2000 —/ x Sodium _ I PORE VOLUMES 1 2 3 I | | 0 I I 0 100 200 EFFLUENT VOLUME, IN MILLILITRES 9000 — 6000 12,000 300 DOC CONCENTRATION, IN MILLIGRAMS PEFI LITFIE CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITRE | SODIUM CONCENTRATION, IN MILLIGFIAMS PER LITRE FIGURE 27.—Sodium, chloride, and DOC breakthrough curves for experiment 1 (flow rate=2 mllhr). tions in the reacted waste during Experiments 1 and 2 are shown in tables 11 and 12. The background con- centration of Fe within the unreacted waste was 6 mg/l. While standing in the stainless steel lines and hydraulic separator, the waste very slowly solubilized Fe from these components of the pressurization core- testing apparatus. This rate was determined to be 0.02 E I LIJ I- o: LU - I: 8000 [I ,l ! [XL x I [X o _.—0 I; t IX X. x 0 000° tr 4 _I . 0 00 ° LLI Dc 0: x 00 00 00° 0 o l “J Lu ; 0° 00 00 m n. u. o 2 ‘0 ' E <0 0 < 5 6000 — x 0° — 3000 5— 1750 g < 0000 .. a: _I 9 g 2 .I _I _I O E 1’ .1 o E _ x z 2 o — z z 4000— —6000 2‘- 3500 j T o z 2 *0 r— 9 9 0 Doc ; I; 0': X I Chlorlde Z I- ; 2000— — 9000 3 — 5250 E Lu X Sodium Z L) o o 2 2 IO 0 O 8 X PORE VOLUMES I404 0 U 5 1o 15 20 E g 8 o I' II I I 1 I 12,0000 — 7000 5 _I o 400 800 1200 1600 5 8 EFFLUENT VOLUME, IN MILLILITFIES FIGURE 28.—Sodium, chloride, and DOC breakthrough curves for experiment 2 (flow rate=4 mllhr). 32 TABLE 12. —Laboratory chemical data for waste-aquifer reactivity, experiment 2 (flow rate =4 ml/hr) SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA S cific Cumulative con uctance Concentration in mg/l Time Fraction volume (#mhos/cm (hr) number (ml) at 25°C) pH DOC Fe Si Na Ca Mg S04 Cl 0 1 20 27,800 7.50 1.5 0.3 11 6100 490 250 420 10,200 5 2 40 26,900 6.30 1270 0.3 20 5000 1100 240 400 8,200 10 3 60 22,500 5.90 2820 2.0 32 3900 1800 210 350 6,600 15 4 80 17,500 5.60 3510 9.5 53 3000 2100 180 330 — 20 5 100 16,100 5.30 4320 12 56 2500 2500 170 300 3,800 25 6 120 15,300 5.10 4700 16 59 — — — 290 —— 30 7 140 14,900 5.00 5050 24 63 1600 2800 140 280 2,200 35 8 160 13,730 4.90 5050 — 64 —- — — — — 40 9 180 12,380 4.85 5750 37 —— 1100 2800 120 220 1,460 45 10 200 11,000 4.75 5850 — 64 — — — —— — 50 11 220 10,750 4.70 5800 41 — 780 2800 110 160 — 55 12 240 10,500 4.65 5800 — 65 — —- — — 880 60 13 260 10,150 4.60 6000 48 — 670 2800 110 90 — 65 14 280 10,250 4.55 6200 — 68 — —— — — — 70 15 300 9,940 4.50 6300 49 — — — — 20 600 75 16 320 9,850 4.48 7000 — 68 400 2600 95 — — 80 17 340 9,690 4.45 7000 58 —- -— — —- — — 85 1 8 360 9,560 4.40 6600 — 70 — — — — 90 19 380 9,170 4.35 7150 67 — 340 2600 92 -— - 95 20 400 9,170 4.35 7100 — 68 — — — — 360 100 21 420 9,050 4.35 7050 70 —— —— — — —- — 105 22 440 9,050 4.35 6950 —— 66 230 2400 80 < 1 — 110 23 460 8,290 4.30 7150 79 — — — — — — 115 24 480 7,900 4.30 7250 — 65 — —- — — — 120 25 500 8,040 4.30 6900 80 — 170 2400 78 — 180 125 26 520 8,160 4.25 6900 — 67 —— — — — — 130 27 540 7,000 4.20 7450 — — —— — — —- — 135 28 560 8,160 4.15 7200 — 72 — — — — — 140 29 580 7,720 4.15 7200 — — 140 2400 74 <1 — 145 30 600 7,460 4.15 7300 — 69 — —— — — 160 150 31 620 7,720 4.20 7400 90 — —- — —- — — 155 32 640 7,7 20 4.15 7400 — 72 — —— — — — 160 33 660 7,650 4.15 7200 95 — 120 2300 70 — — 165 34 680 7,710 4.10 7550 — 72 -— — — 170 35 700 7,800 4.10 7200 93 — — - — — — 175 36 720 8,040 4.10 7500 — 69 — — — — — 180 37 740 7,780 4.10 7600 96 —— 100 2300 66 —— — 185 38 760 7,630 4.10 7600 — 71 — -- —— — — 190 39 780 7,360 4.10 7500 97 — — — — — — 195 40 800 7,600 4.08 7550 — 60 — —— 120 200 41 820 7,580 4.05 7350 102 — 88 2200 66 —— — 205 42 840 7,400 4.05 7400 — 69 — — — - — 210 43 860 7,420 4.00 7 400 96 — — — —— —— —- 215 44 880 7,160 4.00 —— -—- 56 —- — -— — - 220 45 900 7,150 4.00 7600 99 — 78 2100 62 —— — 225 46 920 7,120 4.00 — —— 56 — — — — — 230 47 940 7,080 4.00 — 99 — — — — — — 235 48 960 6,810 4.00 — — 54 —— — — — — 240 49 980 6,840 4.00 — 112 — — — — — — 245 50 1000 6,910 4.00 — — 56 75 2000 59 <1 100 250 51 1020 6,920 4.00 7700 113 — — - 255 52 1040 7,000 4.00 — — 57 — —— - — — 260 53 1060 6,740 4.00 — — — - 265 54 1080 5,150 3.95 Sample sacrificed for gas analysis 270 55 1 100 6,740 3.95 7800 — -- 275 56 1120 6,760 3.95 — 109 —- — — — — — 280 57 1140 6,630 3.95 — — 58 — — —- — —— 285 58 1160 6,370 3.90 — 108 — — — — — — 290 59 1180 6,440 3.90 — — 54 38 1900 56 <1 — 295 60 1200 6,310 3.90 7850 110 — — — — — — 300 61 1220 6,120 3.90 — — 56 — — — — — 305 62 1240 5,990 3.90 —— 1 14 — — — — — — 310 63 1260 5,940 3.90 — — 54 — — — —-— — 315 64 1280 6,190 3.90 7850 115 — — —— —— —- — 320 65 1300 5,990 3.90 — — 55 — — — — ~— LABORATORY WASTE-AQUIFER REACTIVITY STUDIES 33 TABLE 12. —Laboratory chemical data for waste-aquifer reactivity, experimentZ (flow rate =4 ml/hr) —Continued ' ' Cumulative cox? uctfailcice Concentration in mg/l 3:09 $113533? “3:113“! mfigg/C‘lm pH DOC Fe Si Na Ca Mg 804 Cl 325 66 1320 5,990 3.85 — 108 —— — —— _ _. _ 330 67 1340 5,940 3.85 — — 54 — —— __ _ _ 335 68 1360 5,940 3.85 7850 110 — —— — _ _ __ 340 69 1380 5,810 — — —— —-— _ _ _ _ 345 70 1400 5,680 3.80 108 — 23 1700 49 <1 — 350 71 1420 5,860 3.80 — — 52 — —_ _ _ _ 355 72 1440 5,860 3.80 — 112 — —— _. _ _ _ 360 73 1460 5,630 3.80 — —- 54 — — — — —— 365 74 1480 5,660 3.80 7900 110 — — _ _ _ _ 370 75 1500 5,800 3.80 —— —- 58 — — — — — 375 76 1520 5,800 3.80 — 109 — — _ _ _. _ 380 77 1540 5,740 3.80 —— —— 53 — — — — —— 385 78 1560 5,660 3.80 — 109 — — _ _ _ _ 390 79 1580 5,660 3.80 -— — 56 20 1700 50 < 1 — 395 80 1600 5,610 3.80 — 112 — - _ _ _ _ 400 81 1620 5,550 3.75 — 56 — —— _, _. _ 405 82 1640 5,590 3.75 — — — _ _ _ _ _ 410 83 1660 5,525 3.75 — — 57 — — — — — 415 84 1680 5,525 3.75 7900 110 —- — _ _ _ _. mg/l/day in three independent measurements during experiments 1 and 2. The reported values of Fe are corrected for background and solubilization within the apparatus. This small concentration of background Fe concentration should have no effect upon the rate of Fe solubilization from aquifer material. The high background concentration of Si in the injected waste probably had an effect upon Si dissolution of aquifer material. The high initial Si concentration probably decreased the rate of Si dissolution and probably de- creased the total amount of Si dissolution because the high background enabled pseudo-equilibrium concen- trations of Si to be attained more quickly than if no Si were present in the initial waste. Specific conductance and pH are gross chemical indi- cators which are affected by a number of interdepen- dent chemical parameters. Therefore, pH and specific 3 8° I I | I I 12° ” l- I 3 o '. Q o t m ‘ AA“ ' .o.o .0.°.oo _l :4 AA A ‘ ‘ ‘ l.. 5 U) ‘A‘ ..00 . 3 5 so- . A —90 E < A ‘ A A < 5 A A‘.‘ . ‘4 ‘ AA‘ u: j A o. ‘ 5 .‘ A 9 J :‘ _J 2 .° 3 E 40._ 60 Z i ' _ ‘ z E A 0' 9 I'- E ' < I- . E E zo-A 0 "0“ ~30 2 U . 1:1) 3 A Silica g o A c U S .0 POHE VOLUMES z 3 5 10 15 20 g a o ' I | I I I I I o _ I l 300 600 900 1200 1500 EFFLUENT VOLUMES, IN MILLlLITRES 1800 FIGURE 29.—Iron and silica dissolution during experiment 2. conductance are of limited usefulness except as general continuous monitoring indicators. The initial appearance of gas at the outlet of the core holder at fraction 11 during experiment 1 was accom- panied with a large drop in pH from 6.80 to 6.20 and an abrupt appearance of dissolved Fe. The initial appear- ance of gas during experiment 2 occurred in fraction 3 accompanied by incipient Fe dissolution. The pH was lower at pH 5.9 due to the rapid flush of unreacted waste acids. Although all the 002 gas produced during carbonate dissolution Within the core was believed to have remained in solution while within the core, out- gassing of 002 during sampling was an immediate so I l 200 E g ‘A '2 I— ““o 'J _, ‘AA‘ 5 I: ‘ o. D- 5 AA“ ' g m 60—- A ' —150 < 2 ‘ a: g . °' 9 .1 9 A . —I _J o " _l ‘ E _ . Z .. 4 — _. _ n g . 100 g z ' p E ‘ g < 0 ,. o: A 0 Iron 2 1- Lu 2 A ST 3 3 20- o ‘ "ca —50 o s . U A z A 3 ‘ - g o PORE VOLUMES — j _l a 1 2 3 4 5 0000000010.]. | I l I] o e 0 100 200 300 EFFLUENT VOLUME. IN MILLILITRES FIGURE 30.—Iron and silica dissolution during experiment 1. 34 manifestation of carbonate dissolution. The marked increase in Ca content of the waste effluent as high as 4,300 mg/l during experiment 1 was an accurate indi- cator of carbonate dissolution. Gas effervescence dur- ing sample collection at the end of experiment 1 and at fraction 20 of experiment 2, occupied over 50 percent by volume of the collection tube. During experiment 2, gas effervescence declined with Ca concentration. Only small amounts of gas re- mained at fraction 50,Vand gas was essentially absent after fraction 75. Ca concentrations did not approach zero during experiment 2 becaue the concentration of the injected waste was 1,400 mg/l. The carbonate in the injection zone was probably low in dolomite because the Mg concentration constantly decreased at the expense of Ca. Magnesium and sodium, which were competitive with Ca for the ex- change sites on the native aquifer material, were gradually leached from the core with Ca and hydrogen becoming the dominant exchange ions. EXPERIMENT 2 — CORE S0 LUBILIZATION STUDY Experiment 2 was designed to simulate changes which would be manifested within the aquifer material with the passage of the waste front extending into the slow-reaction zone. Sampling of the waste effluent dur- ing this experiment as shown in tables 13 and 14 was conducted at 5-hour intervals over an 18—day period at an average flow rate of 4 ml/hr. At the termination of experiment 2, the waste in the pore space within the core was displaced by passing 180 ml of native ground . water through the core. At this volume, the specific SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA conductance of the effluent was constant at the specific conductance of the native ground water. The core hold- er was then disassembled, the aquifer core material extruded from the Teflon sleeve, and the core fraction- ated into eight equal sections of 1.5 inches (38 mm). Sections 1 through 8 were numbered from the top (waste entry end) of the column. The lag in the DOC breakthrough curve behind chloride during experiments 1 and 2 as shown in fig- ures 26 and 27 indicates that organic components are being sorbed onto the aquifer material throughout the entire duration of both experiments. In addition to DOC, six specific organic compounds (formaldehyde, acetic acid, formic acid, phthalic acid, terephthalic acid, and p-toluic acid) were monitored. These com- pounds collectively comprised over 80 percent of the DOC in the waste. All of these compounds except for- maldehyde were sorbed onto the aquifer core material. The breakthrough curve and breakthrough data for formaldehyde during experiment 2 as shown in figure 14,000 I I I I r 3000 10,000 - 2000 6000' X Formaldehyde 0 Acenc acId ‘ 1°00 0 Formic aCId ACID CONCENTRATIONS, IN MILLIGRAMS PER L|TRE 2000 PORE VOLUMES 5 10 15 I I I ACETIC ACID CONCENTRATION, IN MILLIGRAMS PER LITRE FORMALDEHVDE AND FORMIC I I I I 0 300 600 900 1200 EFFLUENT VOLUME, IN MILLILITHES 1 500 FIGURE 31.—Re1ative sorption of formaldehyde, acetic acid, and for- mic acid during experiment 2. TABLE 13.—0rganic chemical data during waste effluent monitoring of laboratory experiment 2 Concentration (mg/l) Concentration (mg/1) Acetic/formic Phthalic: Time Fraction Cumulative Formic Acetic acid Phthalic Terephthalic p-Toluic terephthalic: (hr) number volume DOC Formaldehyde acid acid ratio acid aci acid p-toluic ratio 0 1 20 1.5 0 — — — — — — 5 2 40 1270 370 340 1980 5.8 36 56 58 1:15:16 10 3 60 2820 745 780 3620 4.6 45 75 103 1:1.6:2.3 15 4 80 3510 925 735 4410 5.9 95 145 188 1:1.5:1.8 20 5 100 4320 1200 863 5840 6.7 119 162 204 1:1.4:1.7 30 7 140 5050 1520 1050 6510 6.2 179 209 226 1:1.2:1.3 40 9 180 5750 1840 1210 6870 5.6 191 295 399 1:1.5:2.1 50 11 220 5800 1840 1710 7620 4.4 160 280 407 111.8226 60 13 260 6000 2080 1660 8140 4.9 180 302 435 1:1.7:2.4 75 16 320 7000 2120 1700 8610 5.1 177 364 606 1:2.0:3.4 90 19 380 7150 2100 1890 8440 4.8 152 357 563 1:2.3:3.7 105 22 440 6950 2150 2170 8290 3.8 153 343 571 1:2.2:3.7 120 25 500 6900 2100 2030 8660 4.2 157 348 557 1:2.2:3.5 140 29 580 7200 2050 2110 8190 3.9 184 303 524 1:1.6:2.8 160 33 660 7200 2120 2410 8890 3.7 190 453 803 1:2.4:4.2 180 37 740 7600 2100 2110 9480 4.5 157 334 551 1:22:35 200 41 820 7350 2020 2470 10,500 4.2 171 315 539 1:1.9:3.1 220 45 900 7600 2080 2280 9130 4.0 140 356 639 1:2.5:4.5 245 50 1000 7675 — 2320 10,700 4.6 134 355 618 1:2.7:4.6 270 55 1100 7750 — 2280 9690 4.2 225 289 392 1:1.3:1.8 295 60 1200 7850 - 2800 9160 3.2 226 352 512 1:1.5:2.3 320 65 1300 7850 — 2640 10,200 3.8 168 330 517 1:1.9:3.1 Waste analysis — — 7900 2100 2780 10,200 3.6 169 358 596 1:2.1:3.5 LABORATORY WASTE-AQUIFER REACTIVITY STUDIES 35 31 and table 13, respectively, indicate that formal- dehyde is not sorbed because its breakthrough curve is essentially the same as for chloride. After fraction 16, the formaldehyde concentration is constant at 2,100 mg/l, which is the formaldehyde concentration of the injected waste. This finding suggests that formal- dehyde may be used as an organic tracer under similar chemical conditions as existed in this experiment and that the degree of sorption of all other organic con- stituents can be measured as a difference between their concentration in the reacted effluent waste and that of the original injected waste. Formic acid was the most strongly sorbed organic compound on a percent by weight basis as shown in figure 31 and table 13. Formic acid was sorbed during most of the experiment with the exception of the very latter stages. At fraction 16, the formic acid concentra- tion was only 60 percent of its concentration in the injected waste. Formic acid sorption was marked not only at the initial portion of the experiment, but was also considerable during the middle to latter portion of the experiment after considerable Fe and Si02 dissolu- tion when the pH was between 4.10 and 4.00. The formic acid molecule is quite liable or subject to chemical and (or) catalytic decomposition. It is possi- ble that the apparent sorption of formic acid was not sorption, but decomposition of a portion of the formic acid. This possible chemical or catalytic decomposition could have occurred with the diverse components of the core material until the incompatible chemical core constituents were consumed or possible catalytic sites were exhausted or hindered by sorption of other or- ganic constituents. A possible data interpretation is that formic acid concentration in the waste effluent gradually approached its concentration within the ini- tial waste only after the possible chemical or catalytic activity ceased within the core. Acetic acid was the second most strongly sorbed or- ganic compound on a percent by weight basis. At frac- tion 16, the acetic acid concentration was 84 percent of its concentration in the injected waste. Acetic acid is not initially strongly sorbed as its breakthrough curve parallels the non-sorbed formaldehyde component. From fraction 8 through fraction 30, acetic acid is strongly sorbed coincident with marked Fe and Si02 solubilization. After fraction 30, acetic acid is less strongly sorbed and gradually attains the same con- centration as in the injected waste. The sorption of phthalic and terephthalic acids are only vaguely suggested during the initial waste monitoring portion of experiment 2 as shown in table 13. The sorption of p-toluic acid is indicated by the phthalic:terephthaliczp-toluic acid ratio inclusive of fraction 16. The relative sorption of these three aromat- ic acids by waste effluent monitoring is dramatically manifested during the slow flow rate of experiment 1. As shown in figure 32 and table 14, there is initial sorption of all three aromatic acids. The flow rate of experiment 2 was too rapid to obtain the necessary detail for aromatic acid sorption. Phthalic acid is strongly sorbed only during the first 150-ml of waste input. This sorption is suggested by pH 8.2 6.8 5.6 5.2 g | | ': _J O: LIJ D. U) 500— _ E . 3:1 p-Tolu‘c E? _l _l E E ____ . / (I; “‘“£\C// Z {Bla‘L’ 9 300~ ,,/ — ._ / <1 / / ”3 / ._ z / m / Q / g // Phthalic _ _ > __ o / ' D / / 6 // I 4 100— / / — 2 / . ,_ < // . /PORE VOLUMES g x’_ /1 2 3 m 0 1 I | < I I 100 200 O 300 EFFLUENT VOLUME, IN MILLILITRES FIGURE 32.—Relative sorption of phthalic, terephthalic, and p-toluic acids during experiment 1. TABLE 14. — Organic chemical data during waste effluent monitoring of laboratory experiment 1 Concentration in mg/l Percent of fraction DOC accounted for by compound Pht ' : Time Fraction Cumulative Phthalic Terephthalic p-Toluic tereplliltzlhlaclic: Phthalic Terephthalic p-Toluic (hr) number volume DOC acid acid acid p-toluic ratio acid acid acid 30 7 70 2500 24 81 124 1:3.2:5.0 0.010 0.032 0.050 40 9 90 4100 42 113 193 1:2.7:4.6 .010 .028 .047 55 12 120 5600 65 186 304 1:2.8:4.6 .012 .033 .054 70 15 150 6500 150 273 428 1:1.8:2.9 .023 .042 .065 90 19 190 7100 160 390 450 1:1.8:2.8 .021 .030 .048 105 22 220 7100 217 324 481 1:1.5:2.2 .030 .045 .068 125 26 260 7600 142 350 600 1:2.4:4.2 .018 .046 .078 140 29 290 7700 164 338 591 1:2.1:3.6 .021 .044 .076 Waste 7900 169 358 596 1:2.1:3.5 .021 .045 .075 analysis. 36 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA the aromatic acid ratio in table 14 and confirmed by the percentage of fraction DOC accounted by phthalic acid. Aproximately 50 percent of the phthalic acid in the waste effluent had been sorbed. Terephthalic acid is sorbed during the first 220-ml of waste input. The most marked sorption occurs after phthalic acid sorption as indicated by the plateau in the breakthrough curve between 150 and 250 ml in figure 31, by the low aromatic acid ratio in this region of the breakthrough curve, and by the percentage of fraction DOC accounted by terephthalic acid in table 4. Approximately 30 percent of the terephthalic acid in the effluent waste through fraction 22 was sorbed onto the aquifer material. The sorption of p-toluic acid during the initial por- tion of experiment 2 is strongly supported by the p-toluic acid breakthrough curve during experiment 1 as shown in figure 32 and table 14. p-Toluic acid is sorbed in the same region of the breakthrough curve as terephthalic acid with continued sorption in the 220- to 260-ml region. Strong sorption of p-toluic acid is indi- cated by the plateau in the 150- to 250-ml region of the breakthrough curve, by the low aromatic acid ratios in this region, and by the percentage of fraction DOC accounted by p-toluic acid. Approximately 30 percent of the p-toluic acid in the effluent waste was sorbed onto the aquifer material up through fraction 26. The sorption of phthalic, terephthalic, and p-toluic acids were also confirmed by sediment extraction at the termination of experiment 2. The sorptive capacities as determined on four sections of the reacted core are listed in table 15. Exclusive of section 1, the sorptive capacities are in a ratio of 1.0:5.5:4.7. This ratio as compared to the ratio of these compounds in the injected waste (1.0:2.1:3.5), indicate a sorptive pref- erence for terephthalic and phthalic acids with the greatest preference for terephthalic acid. TABLE 15.—Sorptive capacities of aromatic organic acids on aquifer material during experiment2 Milligrams of acid sorbed per gram of sediment Phthalic: Core " be hthalic: number Phthalic Terephthalic p-Toluic p-to uic ratio 1 0.011 0.090 0.0059 19:06 3 .025 .117 .116 1:4.7:4.6 6 .020 .106 .106 1:5.3:5.3 8 .019 .127 .081 1:66:43 The sorptive capacities as shown in table 15 should be considered as minimal sorptive capacities because some portion of the organic acids were desorbed during the saturation of the aquifer core material with native saline water at the end of the experiment. This ex- change or desorption of organic compounds is assured by mass action theory and supported by the extremely low sorptive capacities in section 1 at the input end of the column which was in contact with the saline water for the longest time period. The conclusion is limited by the fact that the clay fraction which would be ex- pected to sorb most of the organic substances was somewhat depleted from section 1. The overwhelming concentration of these com- pounds in the waste saturating the interstitial pore liquid would have precluded the analysis of sorbed material without flushing with native ground water. The ratio of the sorptive capacities suggests some lim- ited validity of the sorptive capacities as determined because the ratio of the sorbed acids is markedly dif- ferent from that of the injected waste. The relative meaning of the sorptive capacities will be discussed in detail after the presentation of supporting data ob- tained during experiment 3. Carbonate dissolution was evident during experi- ment 2 by the high levels of Ca in the waste effluent (table 12) and by 002 gas effervescence during waste effluent collection. Gas first appeared at fraction 3 and was present until fraction 75. Carbon dioxide gas per- sisted in the waste effluent much longer than expected for the low carbonate percentage of the aquifer mate- rial (table 16, 0.98 percent CaC03=0.12 percent inor- ganic carbon) and the high organic acid concentration of the injected waste. TABLE 16.—0rganic and inorganic carbon analyses of fractionated and unfi'actionated injection-zone aquifer material DC 101 CaCOa‘ (percent) (percent) (percent) Whole aquifer material, ground .................... 0.15 0.12 0.98 Clay fraction (<2microns) .............. 1.40 .14 1.18 Silt fraction (2—64 microns) ............................ .52 .22 1.82 Fine sand (0.064—0.4 mm), unground .......... .10 .84 Medium sand (0.4—1.0 mm), unground ________ .05 .40 Combined sand (0.064—2 mm), unground... .08 .65 Combined sand (0.064—2 min), ground ........ .03 .09 .71 ‘ Analysis by modified Van Slyke method. Temperature, pressure, the concentration of weak acid solutions, and the distribution of carbonate within the aquifer material are obviously important consid- erations for carbonate dissolution. The addition of the injected waste solution, acid concentration of approxi- mately 2 percent by weight, to a sample of finely ground (less than 60 mesh) aquifer material at room temperature produced no observable gas effervescence. Upon standing at room temperature for 24 hours, only 1A; of the carbonate was dissolved from the sample. The remainder of the carbonate in the sample was con- verted to CO2 gas upon boiling for a period of 10 min- utes. On the other hand, addition of 3 percent HCl, a strong acid, at room temperature produced strong gas effervescence. Upon standing for 3 hours over 90 per- cent of the carbonate was converted to 002 gas. A large portion of the carbonate in the aquifer mate- rial is secondary cementation carbonate because no detrital carbonates and few carbonaceous shells are LABORATORY WASTE-AQUIFER REACTIVITY STUDIES 37 observed with either the binocular microscope or thin- section analysis. Approximately 15—20 percent of the carbonate in the aquifer material is contained within the primary mineral sand grains which comprise over 75 percent of the aquifer material (table 17). As shown in table 16, the carbonate percentage for the unground combined sand fraction is approximately 10 percent less than the ground combined sand fraction. This car- bonate would only be available to react with the acid waste by slow diffusion processes and with breakdown of the mineral grains. TABLE 17.—Particle size analysis of injection—zone aquifer material Percentage by weight Gravel (> 2 mm) ........................................ 1 Coarse Sand (1—2 mm) ...................... 4 Medium Sand (0.4—1.0 mm) ______ 28 Fine Sand (0.064—0.4 mm). _ 43 Silt (2—64 microns) . 20 Clay (< 2 microns) ..... 4 With the previously discussed supporting experi- mental evidence, it is readily understood why carbon- ate dissolution was slow during experiment 2. The experiment was conducted at room temperature, not elevated temperatures, carbonate dissolution was slow in the presence of the weak acid composition of the waste, and a portion of the carbonates were contained as primary mineral grains within sand grains. The 500 psi experimental pressure may have a positive effect upon carbonate dissolution because the 002 gas pro- duced would remain in solution at that pressure which would increase the carbonic acid or hydrogen ion con- centration of aquifer fluids. Carbonate analyses of the core sections at the termi- nation of experiment 2 indicated that only a trace amount of carbonate was present in the aquifer core material. This trace carbonate level (less than 2 per- cent of the total carbonate percentage) represented the carbonate within the center portion of undecomposed sand grains. With passage of the waste through the aquifer mate- rial, the pH of the core decreased from 8.2 to 3.73, the pH of the injected waste. The cation exchange complex was changed from a mixed population of Ca, Mg, and Na to a predominantly Ca-H system at the end of the experiment. It was hoped that the marked dissolution of Si02 and Fe during experiment 2 would be manifested in the analyses of the core material at the end of the experi- ment. The core material was the same reddish-brown color both at the beginning and the end of the experi- ment. Waste effluent analysis indicated that only 12 percent of the total extractable iron (0.4 percent of the sample weight) was removed during the experiment. The redistribution of the clay fraction within the core and the low amount of Fe solubilized during the exper- iment precluded Fe analyses of the core material. The iron which was dissolved from the core material was believed to have been amorphous sesquioxide coatings. This conclusion is supported by the associated Mn analyses in table 18, because Mn, Fe, and Al ses- quioxides are common coatings of aquifer grains. TABLE 18.—Fe, Al, and Mn analyses by graphite furnace technique of selected waste effluent fractions during experiment 2 Concentration in mg/l Sample Designation Fe Al Mn Native ground water ...... <2 <7 0.17 Injected waste _____ 6.3 6.2 .5 Fraction 40 ....... 116 8.7 6.7 50 _______ 77 5.0 3.6 60 ....... 1 16 8.7 4.7 90 .............................................. 182 9.7 4.5 The small amount of Si02 dissolved during the ex- periment as compared to the overwhelming amount comprising primary and secondary minerals certainly precluded computation of Si02 losses by core analysis. The high values for dissolved silica could result from dissolution of amorphous and crystalline clay miner- als. The solubilization of Al-containing clay minerals is supported by the high Al values for fractions 40, 50, 60, and 90 as shown in table 18. The clay mineralogy of the original aquifer sample was approximately 25—40 percent 2:1—2:2 intergrade and mixed layered montmorillonite-intergrade, 25—35 percent montmorillonite, 5—10 percent illite, 5—10 per- cent amorphous clay minerals, and 2—4 percent quartz. X-ray diffraction data at the termination of experi- ment 2 showed only a slight change in the stability of the 2:1—2:2 intergrade clay mineral. This suggested some removal of hydroxy Al and Fe polymers from interlayer space. A detailed discussion of the mineral- ogy of the waste-injection zone and mineralogical changes associated with waste injection is given by Malcolm, Leenheer, and Weed (1976). EXPERIMENT 3 —— WASTE-SATURATION STUDY Experiment 3 was designed to simulate a unit of injected waste at the very edge of the waste front as it moved outward from the injection well. A 300-ml sam- ple of waste was repeatedly reacted with fresh aquifer material until the waste was neutralized and “satu- rated” with dissolved aquifer constituents. The flow rate for the entire experiment was approximately 20 ml/hr. The waste was passed twice through each of the four consecutive cores. A 2-ml sample of the waste effluent was taken for specific conductance, pH, DOC, Si02, and Fe analyses after each pass through the aquifer material. At the end of the experiment the waste effluent was analyzed for phthalic, terephthalic, and p-toluic acids. The moisture content of the aquifer material was 11 percent by weight. This resulted in a 15 percent dilu- 38 tion of the waste when introduced into each fresh core, and a total dilution of 60 percent for the entire experi- ment. This calculated dilution factor agrees well with the DOC experimental data (table 19), which indicates an actual dilution factor of 57 percent. Specific conduc- tance cannot be used to calculate the dilution factor because conductance is increased with carbonate dis- solution. TABLE 19.—Chemical data during waste effluent monitoring of Lab- oratory experiment3 Contact time per pore volume (hr) S ecific con uctance (mnho) Concentration (mg/1) DOC 6400 64.00 5600 5600 4400 4350 3500 3400 Sam 1e Laboratory num er identification Core l—Run 1 Core 1—Run 2 Core 2—Run 1 Core 2-Run 2 Core 3—Run 1 Core 3—Run 2 Core 4—Run 1 Core 4—Run 2 ,_. oaqoosn g m .. mpps papa «3 N o o Robbin ki'oinoo P 4.30 4.65 5.10 5.30 5.95 6.30 7.15 7 20 WQQUI AWNH 9900 . The monitoring data for experiment 3 is shown in table 19. The pH data suggested that carbonate disso- lution was initially rapid during the first pass of the waste through the core. Only small incremental changes in waste pH were observed with the second pass through the same core. The Fe data again showed the dramatic effect of pH on Fe solubilization. At pH values below 5, Fe dissolution was rapid, was moderate between pH 5 and 6, and was essentially zero above pH 6. Silica solubilization by the waste showed the typical U-shaped curve for silica solubility (Jones and Hand- reck, 1967). Silica solubility was high at low pH and decreased gradually with increasing pH. Silica solubil- ity would be expected to again increase with pH above pH 10. The concentration of phthalic, terephthalic, and p-toluic acids at the end of the experiments were 27, 87, and 151 mg/l, respectively. The resultant ratio of these three compounds were 1.0:3.2:5.6, which is very different from the 1.0:2.1:3.1 ratio that they appear in the injected waste. The low concentrations of all acids indicate sorption on the aquifer material and the ratio indicated preferential sorption of phthalic acid. An additional experiment was designed to test the hypothesis that Fe complexed with phthalic acid pre- cipitated above pH 6.5. Solutions of phthalic acid (0.001 M (molar)=164 mg/l) and FeCla (0.01 M =590 mg/l) were mixed at pH 2.8. These concentrations are similar to phthalic acid concentrations in the waste and the experimental concentration range of Fe with waste passage within the aquifer as determined in the previously discussed laboratory experiments. The pH was increased to 6.5 by small additions of dilute NaOH. Iron and Fe-phthalic acid complex precipitated from solution. Gas chromatographic analysis on the supernatant solution indicated that over 50 percent of the phthalic acid was removed from solution into the precipitated phase. SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA The sorptive capacities for phthalic, terephthalic, and p-toluic acids during experiment 3 are 0.01, 0.02, and 0.03 mg/g of aquifer material. These sorptive capacities are relative and not absolute sorptive capacities because they were computed on the basis of 1,600 g of aquifer core material (four cores) used dur- ing the experiment. A more correct sorptive capacity is believed to be 0.02, 0.02, and 0.03 because phthalic acid was only sorbed on the last two cores of the exper- iment (800 g of sediment) when the pH was above pH 6; whereas terephthalic and p-toluic acids were sorbed by all the cores. This conclusion is also supported by the sorptive data and curves as shown in table 12 and Figure 32, respectively, where phthalic acid is only sorbed between pH 6—7, but terephthalic and p-toluic acids are sorbed over the entire pH range of experi- ment 1. The sorptive capacities of phthalic, terephthalic, and p-toluic acids as determined during experiment 3 (0.02, 0.02, and 0.03 mg/g) by waste monitoring, during ex- periment 2 (0.02, 0.10, and 0.10) by sediment extrac- tion, and the sorptive curves in figure 31 during exper- iment 1 may mistakenly be interpreted to be in con- flict. The differences really reflect the dependence of sorptive capacity on pH, the nature of the sorptive site, and the charge on the organic molecule. The composi- tion of the reactive surface, its charge, and charge density, change with dissolution of Fe, Si02, and Al. The reactive surfaces are primarily amorphous coat- ings of Fe, A1, Mn, and 8102 at the beginning of the experiments when pH is high. With dissolution of these coatings and carbonates, the reactive surface gradually becomes a more crystalline alumino-silicate clay mineral and crystalline sesquioxide surface. The pH within the core also gradually becomes more acidic. The solubility of the aromatic acids, their hy- drophilic character, and negative charge (acid dissocia- tion) decreases with decreasing pH. The relative rate of magnitude of these changes are dependent on the con- figuration of the molecule and the relative changes in the reactive surface. All data indicate that phthalic acid is preferably sorbed at high pH whereas p-toluic and terephthalic acids are preferably sorbed at lower pH with less Fe on the reactive surfaces. The 0.15 percent organic carbon component of the native aquifer material is also an important factor in organic waste acid sorption by the core. Many organic compounds have a profound affinity or attraction for like or similar compounds. The amphoteric nature of natural organic substances would facilitate organic acid sorption through the entire pH range of the exper- iments _(pH 3.7—8.2) by hydrogen bonding, Van der Waals forces, or direct exchange processes. The bridge bonding of Fe, Al, and Mn on the core colloids to organic acids in the interstitial waste liquid FINAL CONCEPTUAL MODEL OF WASTE MOVEMENT AND REACTIVITY 39 was also an important possibility of organic acid sorp- tion. The acidic functional group on the organic acid could actively participate in initial Fe solubilization by surface complexation with Fe. With time, decreasing pH (increased protonation potential), and increasing organic acid concentration, the Fe would leave the surface of the colloid and become sequestered by the organic acid. The active solubilization period or time which the organic acid was in contact with the Fe on the surface site would be manifested as organic acid sorption. FINAL CONCEPTUAL MODEL OF WASTE MOVEMENT AND REACTIVITY The final conceptual model of waste movement and reactivity was more complex and detailed than the initial hypothetical model. The initial model assumed waste movement within a single permeable injection zone; however, the logs and the observation well flow- test indicated that the injection zone consists of multi- ple subzones. Assuming independent subzones within the injection zone as shown in figure 33, the waste possibly moved preferentially into the upper subzones because of favorable permeability and because the den- sity of the waste is less than that of the ground water. This density effect is shown in figure 33 by having the lighter waste solution overriding the heavier ground water in the lower two receiving subzones within the injection zone. The flow system diagrammed in figure 33 is but one of many possibilities discussed in connec- tion with figure 21. Therefore, waste obtained from observation wells may be diluted by the ground water within the waste-contaminated subzone because of the density separation. Most of the variance in the waste concentrations in samples obtained from wells 11, 14, and 15 is believed to have been due to changing dilu- tion factors caused by changing circulation patterns between the waste-receiving subzones within the ob- servation wells. Injection well Observation well Sand Gravel é E Clay m Waste ‘4 7 . fl DEPTH, IN FEET FIGURE 33.—Hypothetical movement of injected waste within injection subzones. Evidence that all the receiving subzones within the injection zone were accepting waste was obtained from wells 1, 2, 4, and 5. Samples obtained from these wells which were located only 150 ft (46m) from injection well I—6 were essentially free of ground water. The large distance gap between the observation wells of the initial injection network and the observation wells of the expanded system did not allow observation of the injection zone in regions where the injected .waste in- terfaced with the native ground water in the lower receiving subzones. Therefore, the distance of injected-waste travel in these lower subzones is purely speculative in figure 33. Many of the postulations in the initial conceptual model (fig. 17) are valid for the final conceptual model shown in figure 34. This model, based on the findings of this study, shows features of waste movement and reactivity within an individual waste-receiving sub- zone in the injection zone. Figure 34 does not show vertical distribution of waste in an aquifer, but the percentage of waste at a particular distance from the injected well. Therefore, this model probably has dif- ferent quantitative dimensions for each receiving sub- zone depending on the distance and rate of waste travel Within each subzone. However, the relative dimensions and order of reactivity should have validity for each subzone. As with the initial model, the dimensions of this model expand to the right with increasing time during waste injection. This final model is divided into a “waste front” and “waste interior” at the point where the pH of the in- jected waste begins to rise through neutralization reac- tions. Most, but not all of the ground water has been displaced from the receiving subzone at this point. The curve, relative percentage of waste to percentage of groundwater, was drawn with the ground water ex- tending the waste-contaminated region because the density difference between the injected waste and the INJECTION pH pH pH pH WELL WASTE ONTERIOH 4 v 5.5 6 7 WASTE FRONT we I I I Relatlve percentage of waste to percentage at ground water 80 — 20 60 — 40 CI rtauon 40 -— 60 20— PERCENTAGE OF INJECTED WASTE lronh droxide re m o D WASTE POOL 100 TRANSITION [MICRO lDlLUTION ZONE BIAL ZONE ZONE SLOW'HEACTION ZONE FAST REACTION ZONE WASTE MOVEMENT ——5 FIGURE 34.—Final conceptual model of injected-waste reactivity and movement. 40 native ground water would cause stratification and prevent rapid mixing. The leading zone of the waste front prior to the appearance of methane gas indicative of microbial ac- tivity is called the “dilution zone” because the neu- tralized (pH 7) waste appears as a very dilute solution in ground water. Data from samples obtained from wells 11 and 14 indicated that waste concentrations had to attain a certain threshold value before there was microbial waste decomposition. This zone may also represent a lag time during which the microorganisms are multiplying to numbers where they become sig- nificant in waste decomposition. The waste showed no detectable reactions within this zone, and had little effect on the chemical quality of the ground water. The zone which follows the dilution zone is called the “microbial activity zone” because of indications of anaerobic waste transformations within this zone. Methane gas, sulfur reduction, and iron reduction were observed either singly or in combination at various periods in wells 11, 14, and 15. Two strains of methane-producing organisms were isolated in sam- ples obtained from well 14 during methane production. However, the microbiological study revealed that the waste was toxic to microorganisms in moderate con- centrations, and waste decomposition occurred only at the periphery of the waste front where waste concen- trations were low. The zone called the “transition zone” follows the microbial activity zone. When the waste attains toxic concentrations and when limiting nutrients such as nitrogen are gone, there will be a die-off of microor- ganisms in the injection zone and microbial activity will cease. This zone is transitional between the zone of microbial waste transformations and the zone in which chemical reactions predominate. Most of the chemical waste-aquifer interactions were found to occur within the zone defined as the “fast- reaction zone”. The boundaries of this zone are defined by pH. The pH changes from pH 4 at the trailing boundary to pH 7 at the leading boundary. One of the main features of this zone is the neturalization of the . acidic, injected waste at pH 4 by the aquifer carbonates and sesquioxide minerals. Observations on site at well 9 and in experiments 1 and 2 of the laboratory waste- aquifer reactivity studies indicate that at a given point in receiving zone, the maximum rate of dissolution of carbonate coatings occurs first followed by dissolution of sesquioxide coatings of which the iron oxides pre- dominate. Dissolution of both carbonates and Al, Si02, Fe, and Mn contained within the grains of primary minerals occurs at a much slower rate than the disso- lution of the coatings. High concentrations of dissolved calcium and carbon dioxide are features of carbonate dissolution, and sesquioxide dissolution is indicated by SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA elevated concentrations of aluminum, iron, and man- ganese. Iron solubilization data from experiments 1 and 2, and iron precipitation data from experiment 3, suggest a region of iron hydroxide precipitation within the fast-reaction zone. As the pH of a unit of waste moving outwards from the injection well changes from pH 5.5 to 6.0, hydroxide concentration increases to the point where precipitation of iron hydroxide occurs. This re- gion of iron hydroxide precipitation may be a signific- ant factor in the chemical plugging of the waste- receiving subzones because very high concentrations of organically complexed iron were observed in the fast- reaction zone below pH 5.5, and this dissolved iron was essentially quantitatively reprecipitated as the pH of the injected waste rose during its outward movement and neutralization. Phthalic acid complexed with the dissolved iron was found to be coprecipitated with the iron hydroxide, and this is most likely the reason why phthalic acid was not found in the neutralized waste samples obtained from wells 11, 14, and 15. The corre- lation of iron concentration with waste concentration in well 14 most likely resulted from bacterial waste decomposition processes; not from organic acid dissolu- tion of iron oxide coatings because acid-solubilized iron should have reprecipitated before the waste reached well 14. The laboratory waste-aquifer study substantiated the “slow-reaction zone” of the initial conceptual model which follows the fast-reaction zone. Reactions which occur in this zone are the slow solubilization of silica, aluminum, and iron from the crystalline primary min- erals found in the waste-receiving subzones. Prior pas- sage of acidic waste has dissolved most of the secon- dary coatings found on the aquifer minerals, and the only significant reactions which remain are the slow- dissolution reactions of the primary minerals them- selves. The pH in this zone is essentially the same as the pH of the injected waste, pH 4, because the flow rates and types of reactions do not significantly neu- tralize the waste and affect the pH. The reaction rates in the slow-reaction zone were found to decrease as the quantity of injected waste increased until no further reactions could be observed between the waste and the aquifer constituents. The area in the subsurface in the immediate environs of the waste-injection well where there were no observable reactions was called the “waste pool.” Samples ob- tained from wells 1, 2, 4, and 5 at the beginning of this study were taken from the waste pool because their elemental composition was essentially the same as the injected waste. Only after the cessation of all observa- ble reactions can the subsurface environment be re- garded as a waste storage area because it is only in this waste pool that the waste could be reclaimed in unal- SUMMARY AND CONCLUSIONS 41 tered form after subsurface injection. The various zones and interactions presented in this final conceptual model of waste movement and reactiv- ity cannot be considered to be well defined at all times during waste injection. At the beginning of injection of waste similar to that from the Hercules plant, it is not likely that there is a microbial activity zone because conditions change too suddenly within the waste front for an establishment of a viable waste-degrading mi- crobial population. It is only after the waste front has moved a significant distance from the injection well that its rate of movement will decrease to the point which allows the formation of a microbial activity zone. At the opposite extreme of the model, a waste pool cannot form until a sufficient volume of waste has been injected and enough time has passed so that all the reactive aquifer constituents have been dissolved and removed from the vicinity of the injection well. In summary, this model is a static representation of a dynamic situation. Specifically, this model was drawn to represent the various stages of reaction of the in- jected waste thought to exist in the subsurface after 4 years of waste injection at which time most of the findings of this study were obtained. SUMMARY AND CONCLUSIONS The Hercules waste injection site near Wilmington, N.C., has provided an opportunity for studying the physical, chemical, and biological aspects of subsurface organic waste injection. Most of the waste-aquifer in- teractions which were predicted to occur at the incep- tion of this study were verified by the site and labora- tory studies. Differences between the initial and final conceptual models of waste movement and reactivity show however that the initial predictive model had to be tested with data and modified to fit the findings of this study. Evidence was obtained at the site and in laboratory studies to substantiate the following waste-aquifer in- teractions: 1. Dissolution of the carbonate minerals in the injec- tion zone by the waste organic acids. 2. Dissolution of the sesquioxide coatings on the pri- mary minerals in the injection zone by waste organic acids. 3. Dissolution of the primary aluminosilicate minerals in the injection zone by the waste organic acids. 4. Dissolution and complexation of iron and man- ganese oxides by the waste organic acids. 5. Reprecipitation of complexed dissolved iron during waste neutralization. 6. Coprecipitation of phthalic acid complexed with iron during iron hydroxide precipitation. 7. Methane gas production resulting from anaerobic microbial waste degradation. 8. Microbial reduction of sulfates to sulfides. 9. Reduction of ferric to ferrous iron resulting from decreases in Eh and pH due to microbial waste deg- radation. 10. Retention of organic waste acids by adsorption and anion exchange on the mineral constituents in the injection zone at low pH values. These waste-aquifer interactions prove that this in- dustrial organic waste cannot be regarded as an inert fluid which does not react after injection into the sub- surface environment. The history of the plugging of both injection wells after a period of waste injection strongly indicates that serious consideration should be given to the chemical compatibility of the waste with the fluid and minerals of the zone into which injection is planned. Problems of injection zone plugging may be due in part to the reprecipitation of aquifer con- stituents initially dissolved by the waste acids, and due to the formation of gaseous reaction products such as carbon dioxide and methane. Dissolution of aquifer solids by the complexing organic acids in the waste may be significant in the leakage problems at the in- jection and observation wells. These organic acids may dissolve the bond between the cement grout surround- ing the well casing and the aquiclude confining beds to allow upward leakage of waste into shallower zones. If the waste leakage was due to dissolution reactions, this problem would be accentuated at the injection wells where the waste is the most acid (pH 4), the warmest (45°C), the density difference with the native ground water the greatest, and where the highest pressure head occurs in the injection zone. This study has shown the importance of conducting compatibility tests of the injected waste with the aquifer material before the initiation of waste injec- tion. The data obtained by conducting three experi- ments with the pressurization core-testing apparatus demonstrated that field hydraulic conditions of waste injection can be simulated within the laboratory. Most of the chemical interactions which occurred on-site were observed in the laboratory simulation of waste injection into cores of material from the injection zone. The laboratory study demonstrated precipitation and dissolution reactions which pointed to problems of aquifer plugging and leakage at the waste-injection site. It also better defined waste-aquifer interaction in a quantitative manner than did the site study. Such laboratory tests should also be of considerable in- terpretive value in waste-injection systems where monitor wells are absent or are determined to be a financially impractical part of the total injection sys- tem. A major limitation of the site study was imposed by the construction features of the observation wells be- cause they were open to various subzones within the 42 injection zone. In any future study it would be desira- ble to install packers in the observation wells to isolate each subzone, so that undiluted samples could be ob- tained from each. The case history of the Hercules waste-injection sys- tem is a documentation of a system which is no longer used for several reasons. The major problem with the waste appears to be its reactivity. Because the overall permeability of the waste-injection zone _was low, the formation of coatings, precipitates, and (or) gases, even in small quantities, decreased the permeability of the injection zone to the point where plugging of the injec- tion well occurred. If wastes of this type were neu- tralized prior to injection, the injected neutralized waste would not dissolve aquifer constituents such as iron which is later reprecipitated. Carbon dioxide gas would, therefore, not be formed which may constitute part of the plugging problem other than the small quantity produced by microbioal waste degradation. The neutralized salts of organic acids are not nearly adsorbed on aquifer sediments to the extent of free acids which may form coatings and precipitates on aquifer sediments. Cooling the neturalized waste prior to its filtration and injection would allow precipitate formation of any insoluble waste constitutents which could be filtered from the waste before injection. These actions would have made the waste more inert in the subsurface environment, thus minimizing problems with aquifer plugging and well leakage. The microbiological study has shown that this in- jected waste is very slowly biodegradable in the sub- surface environment. Although the addition of nitro- gen to the injected waste may greatly increase the amount of microbial waste degradation and sub- sequent methane formation, a large amount of methane gas would undoubtedly be formed and would plug the injection zone under site conditions similar to that studied. SELECTED REFERENCES Black, Crow, and Eidsness, Inc., 1971, Engineering report on drilling and testing of additions to the disposal well system for Hercules Incorporated, Hanover Plant, Wilmington, NC: 103 p. Bricker, C. E., and Vail, W. A., 1950, Microdetermination of formal- dehyde with chromotropic acid: Anal. Chemistry, v. 22, no. 5, p. 720—722. DiTommaso, Anthony, and Elkan, G. H., 1973, Role of bacteria in decomposition of injected liquid waste at Wilmington, North Carolina, in J. Braunstein, ed., Sept. 1973, Underground Waste Management and Artificial Recharge: New Orelans, v. 1, p. 585—599. Goerlitz, D. F., and Brown, Eugene, 1972, Methods for analysis of organic substances in water: U.S. Geol. Survey Techniques Water-Resources Inv., book 5, chap. A3, 40 p. SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA Hall, C. W., and Ballentine, R. K., 1973, U.S. Environmental Protec- tion Agency policy on subsurface emplacement of fluids by well injection, in J. Braunstein, ed., Sept. 1973, Underground Waste Management and Artificial Recharge: New Orleans, v. 2, p. 783—789. Hem, J. D., 1970, Study and interpretation of the chemical charac- teristics of natural water [2d ed.]: U.S. Geol. Survey Water- Supply Paper 1473, 363 p. Jones, L. H. P., and Handreck, K. A., 1967, Silica in soils, plants and animals: Advances in Agronomy, v. 19, p. 107—147. Kunzie, G. W., and Rich, C. I., 1959, Certain properties of some Southeastern United States soils and mineralogical procedures for their study: Blackburg, Va., Virginia Agr. Exp. Sta., South- ern Cooperative Series Bull. 61. Lawrence, A. W., and McCarthy, P. L., 1969, Kinetics of methane fermentation in anaerobic treatment: Water Pollution Control Federation Jour., v. 1, part 2, p. 1—17. Leenheer, J. A., and Malcolm, R. L., 1973a, Chemical and microbial transformations of an industrial organic waste during subsur- face injection: Anaheim, Calif., Inst. Environmental Sci. Proc., April 1973, p. 351—360. 1973b, Case history of subsurface waste injection of an indus- trial organic waste, in J. Braunstein, ed., Sept. 1973, Under- ground Waste Management and Artificial Recharge: New 0r- leans, v. 1, p. 565—584. Le Grand, H. E .; 1955, Brackish water and its structural implica- tions in Great Carolina Ridge, North Carolina: Am. Assoc. Pe- troleum Geologists Bu11., v. 39, no. 10, p. 2020—2037. 1960, Geology and ground—water resources of Wilmington— New Bern area: North Carolina Dept. Water Resources Ground-Water Bull. 1, 80 p. Malcol‘m,R. L., Leenheer, J. A., 1973, The usefulness of organic carbon parameters in water quality investigations: Anaheim, Calif, Inst. Environmental Sci. Proc., April 1973, p. 336—340. Malcolm, R. L., Leenheer, J. A., McKinley, P. W., and Eccles, L. A., 1973, Supplement II—Dissolved organic carbon, in D. F. Goer- litz and Eugene Brown, eds., Methods for analysis of organic substances in water: U.S. Geol. Survey Techniques Water- Resources Inv., book 5, chap. A3, 34 p. Malcolm, R. L., Leenheer, J. A., and Weed, S. B., 1976, Dissolution of aquifer clay minerals during deep-waste disposal of industrial organic wastes: Mexico City, Internat. Clay Conf. Proc., 1975, p. 477—493. McKeague, J. A., and Cline, M. G., 1963, Silica in soil solutions, Parts I and II: Canadian Jour. Soil Sci., v. 43, p. 70—96. McKenzie, H. A., and Wallace, H., 1954, The Kjeldahl of nitrogen: A critical study of digestion conditions: Australian Jour. Chem., v. 7, p. 55—60. Mehra, O. P., and Jackson, M. L., 1960, Iron-oxide removal from soils and clays by a dithionite-citrate system buffered with sodium bicarbonate: Clays and Clay Minerals, 7th Natl. Conf. on Clays and Clay Min. Proc., 1960, p. 317—327. North Carolina Department of Water and Air Resources, 1971, Satus report on the feasibility of the injection of liquid waste into saline ground water at Wilmington, North Carolina: Raleigh, North Carolina, 26 p. Oborn, E. T., and Hem, J. D., 1961, Microbiologic factors in the solution and transport of iron: U.S. Geol. Survey Water-Supply Paper 1459—H, p. 213—235. Peek, H. M., and Heath, R. C., 1973, Feasibility study of liquid-waste injection into aquifers containing salt water, Wilmington, North Carolina, in J. Braunstein, ed., Sept. 1973, Underground Waste Management and Artificial Recharge: New Orleans, v. 2, p. 851—875. Ringbom, A., 1963, Complexation in analytical chemistry: New York, Interscience Publishers, 395 p. Siebert, M. L., and Hattingh, W. H. J., 1967, Estimation of methane-producing bacterial numbers by the most probable number (MPN) technique: Pergammon Press, Water Research, v. 1, p. 13—19. SELECTED REFERENCES 43 Skougstad, M- W., and Scarbro, G- F., Jr-. 1963, Water sample filtra- Warner, D. L., and Orcutt, D. H., 1973, Industrial waste-water wells tion unit: Environmental Sci. and Technology, v. 2, p. 298—301. in United States—Status of use and regulation, 1973, in J. Swenson, H. A., d B 1d - ’ A. L., 1965, A - te l't : Braunstein, ed., Sept. 1973, Underground Waste Management WashingMna%.S.8Go‘:t:nPrinting Office 13:71:” on wa r qua l y and Artificial Recharge: New Orleans, v. 2, p. 687—697. ’ _ ’ White, W. R., and Leenheer, J. A., 1975, Determination of free formic Waksman, S. A., 1952, S011 microbiology: New York, John Wiley & and acetic acids by gas chromatography using the flame ioniza- Sons, 356 p. tion detector: J our. Chromatographic Sci., v. 13, p. 386—389. BASIC-DATA TABLES 20-36 46 TABLE 20. — Organic waste analyses SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA TABLE 23.—Inorganic analyses of ground water from 300-fi‘ zone Collection date (moday-y‘r) 9-14—72 7-6-73 11-7-73 we“ N°' Milligrams per litre 13 14 15 16 Zone (feet below 283—293 320-330 279—299 305—325 6,700 6,400 7,900 land surface). 9500 3500 10,000 Collection date 1145-71 2-25-72 2—26-72 4.1572 F ld h (1 i688 i’igo 2138 g“ 8 8 1 8 2 8 orma e y e , , , """"""""" ‘ ' ' ‘ peelfic conductance 9550 9000 7500 9500 Methanol ........ 260 0 2,000 (“has at 25.0). -Toluic acid _______ 1,200 1,100 1,000 Milligrams per litre erephthalic acid . 430 400 360 Silica (si02) 2.3 9.7 9.5 11 Phthalic acid . 36 22 170 Calcium (Ca) . 32 19 13 47 Benzoic acid 35 32 95 Ma esium (Mg 34 46 32 45 Sodgillm (Na) . 1850 2000 1650 2100 Potassium (K) ..... 20 58 50 63 . . B' be te HCO 61 1 587 634 480 TABLE 21. — Waste inorganic analyses—cam le collected 1 1 -7— 73 Silflte (lsaoli a) 45 350 130 330 [Analéls-ed b WRD Central Laboratory Salt Lake City Ut , excefi where noted b (a), Chloride (Cl) 2820 2730 2350 2430 Hu. an laboratory, Wheatridge, Co 0., or by (b), V. C. Kennedy, .S.G.S., Menlo ark, Fluoride (F) 1 1,4 1.3 Cahfil Nitrite—ultra .02 .6 .05 Analysis date Orti- ‘ L ,L ‘ (P04) . .000 0 .000 12. 18—73 3.2744 Residggggl evaporation 5220 5560 4560 5970 H ..................... 3.8 3,8 3" ' Specifi c con du 4,560 4,530 Hardness as CaCOa (Ca, Mg) 200 ' 236 1.64 303 (umhos at 25°C). Mlcrograms per litre » - - Aluminum (Al) .. 81 269 225 543 Silica (Si02) 31 Mllllgrams ‘1)" litre Copper (01)“ 173 — — — . 3 Iron (Fe)... 5253 15 0 522 Calc1unl (Ca) . 1,300 1.300 Lithium (L1) 77 — — — M89991“ (M8) 30 32 Manganese (Mn) 112 _ — — 153331"? Wild" 1‘8 1-5 Strontium (Sr) 1200 — _ _ “"11“ — 3-8 Zinc (Zn) __________ 10 _ — —- 31:11:31): (38;)... 11 41 o ' e 5.2 . . Fluogde (F)? 1.4 32 TABLE 24.—Inorgamc analyses ofground water from 500-fl zone Nitrite-nitrate (N02-N04) — — 3.9(8) Orthophospate (P04) ........ 0.28 — W 11 N Hardness as CaCOa (Ca, Mg) .. 3,400 3,400 14 e 0' 15 Micrograms per litre . Zone (feet below land surface) 500—520 500—520 Aluminum (AD: W31 — — 6120007) Collection date ............................................................ 34—72 35—72 .mc (A9) 3 — H 7.9 7.6 B21313? (Ba) 0 — Specific conductance 20,000 19,500 gamulnwuiiiijg) total 260 2 (“mm at 25°“ ’ ’ ' _ Milligrams per litre Cobalt (Co) 1,600 — Silica (SiOz) 6.2 8 1 Copper (Cu)... — 10 Calcium (Ca) ,. 14B 111 Iron (Fe), total . 20 80 5,500(b) Ma esium (Mg) 169 185 Lead (Pb) ........... — Sufism (Na) 4,600 4,430 Manganese (Mn) . 160 80 Potassium (K) 123 118 Mercury (Hg), total. 1.0 — Bicarbonate (HCOa) .. 337 371 Mollybdenum (Mo) 2 — Sulfate (804).... 765 760 Nic e1 (Ni) ....... 100 2 Chloride (C1) 6,990 6,950 Selenium (Se) 24 — Fluoride (F) ...... .8 .7 Strontium (Sr) . 820 — Nitrite-nitrate (NO2-NOa) .00 .09 Zinc (Zn) ....... — 590 0mm , ' . (P04) .000 .000 Relsidue on evaporation at ........................................ 13,300 12,800 TABLE 22. — Inorgamc analyses at ground water from surficuzl sand Hardness as 08003 (C a, M g) __________________________________ 1,060 1,040 aqlufer Micrograms per litre Well Aluminum (Al), total . 613 613 Hercules Iron (Fe), total ......... 0 0 Supply well C 14 15 16 Zone (feet below 30-60 28—48 33—53 33—53 land surface). Collection date . 6—15—71 2-25«72 2-26—72 5—19-72 H ................... . 6.6 6.1 6.0 Specific conductance 29 46 85 31 (lunhos at 25°C). Milligrams per litre Silica (Si02) .. 5.0 4.8 5.7 4.1 Calcium (Ca) 1.8 2.0 5.0 1.5 Ma esium (Mg) .. .4 1.0 3.0 .9 mm (Na) .. 3.0 4.9 4.5 2.1 Potassium (K) .. .5 .6 1.4 .5 Bicarbonate (HCOa) 4 10 5 7 Sulfate (504).. 4.0 2.4 2.6 4.4 Chloride (CI). 5.2 6.4 9.0 3.4 Fluoride (F).... 0 .0 .0 .0 Nitfite—lutrate .2 .3 4.3 .02 Orthophosphate (POq) .......................... .00 .000 .013 .010 Residue on evaporation 22 33 56 29 at 180°C. Hardness as CaCOa (Ca, Mg) 6 9 25 7 Micrograms per litre Aluminum (Al), total 53 107 37 239 Iron (Fe), total 57 115 0 131 Manganese (Mn) 12 — _ _ Copper (Cu). 40 _ _ _ Zinc (Zn) 10 _ _ _ TABLE 25 —Inorganic analyses of ground water from 700—ft zone [Values in parentheses are from analysis by E. A. J enne, U.S.G.S., Menlo Park, Calif.] BASIC-DATA TABLES 47 Well No. 8 8 8 9 9 9 14 Zone (feet below 694—704 694—704 694-704 727—737 727—737 727—737 637-693 land surface). Collection date .. 6—15-71 6-13-73 10—31-73 6-15-71 6-20-72 6—14-73 3-8—72 pH .................... . _ — 7.4 5.8 4. 7.8 Specific conductance 27,100 28,300 28,241 31,100 17,900 17,900 25,000 (amhos at 25°C). Milligrams per litre Silica (Si02) . 8.8 12 11 8.0 60 27 6.2 Calcium (Ca) 265 270 280 321 3,870 3,100 223 Magnesium (Mg . 321 280 280 438 219 190 186 Sodium (Na) ..... 5,900 5,900 6,300 6,750 1 ,700 — 5,900 Potassium (K) . 212 170 200 230 120 140 145 Bicarbonate (HCOa) 358 — — 244 6,910 — 247 Sulfate (304) ..... 610 540 550 740 145 150 680 Chloride (Cl). 9,650 10,000 1 1,000 11,400 2,550 3,000 9,300 Fluoride (F)... .5 .4 .4 .4 3.6 3.2 .6 Nitrite-nitrate .8 — .6 1.8 ~— .3 Orthophosphate (P04) ....................... .02 —- .02 .12 — 0 Res'idllgzgél evaporation 17,800 — — 21,000 22,100 — 16,700 a . Hardness as CaCOa (Ca, Mg) 1,980 1,800 1,900 2,600 10,600 8,500 1,270 Micrograms per litre Aluminum (Al), total . 495 20 0 305 1,260 0 (<1) 858 Arsenic (As) . — 9 — — — o — Barium (Ba) . — 300 —— — —— 2,300 — Cadmium (Cd) . — 60 — -—— — 170 (<.2) — Chromium (Cr), total . — 10 — — — 150 — Cobalt (Co) — 200 —- — — 930 (20) _ Copper (Cu). 120 30 269 90 (1.0) — Iron (Fe), total 2,150 3,400 5,000 12,000 77,800 310,000 (205,000) 0 Lead (Pb) ...... — 4 — — 15 (<3.5 — Manganese (Mn) 180 150 — 179 — 5,200 (3300) —— Mercury (Hg), total —— 14 — — — . — Molybdenum (Mo) .. — 2 —- — — 2 (<1.2) Nickel (Ni) ...... — 230 — — — 880 (67) — Selenium (Se) .. — 2 — — — 250 — Strontium (Sr) —— 16,000 — — — 19,000 — Zinc (Zn) .......... 35 130 110 40 — 200 (160) — TABLE 26.—Inorganie analyses of ground water from well 7, 805—1036 feet below land surface Collection date H 6-15-71 5 11-3-7; 6-13-73 10-31-73 gpééiiié'ééiiéfiéfifiéé: 31,800" 32,500' 31,500 32,635 (umhos at 25°C). Milligrams per litre Silica ($102) 9.4 11 11 Calcium (Ca) . 353 346 330 Ma esium (M 370 315 300 00 S lum (Na) 6,900 6,750 6,700 7,000 Potassium (K 22 155 190 210 Bicarbonate (HCOa) . 233 231 — Sulfate ($04) 385 280 270 Chloride (Cl) 12,000 12,000 12,000 12,000 Fluoride (F). . .09 .5 Nitrite-nitrate (N02-N03) 0 — Orthophosphaie (P04) .03 — Residue on evaporation 21,100 20,700 — — Hardness as CaCOa (Ca, Mg) . 2,400 2,200 2,100 2,100 Micrograms per litre Aluminum (Al), total 502 335 0 10 Arsenic (As) —— — 6 — Barium (Ba) — — 400 — Cadmium (Cd) — — 80 — Chromium (Cr), total — —— 20 — Cobalt (C0) . —— — 250 — Copper (Cu). 211 40 — Iron (Fe), total 314 1,792 1,400 1,300 Lead (Pb) — — ' 3 0 Lithium (Li) ....... — 292 — — Manganese (Mn) 222 190 250 — Mercury (Hg), total .. — — 8.2 -— Molybdenum (Mo) — —— 3 — Nickel (Ni) — — 250 — Selenium (Se) — — 10 — Strontium (Sr) .. — 17,300 2,500 — Zinc (Zn) ............ — 20 60 100 48 SUBSURFACE ORGANIC WASTE INJECTION, NORTH CAROLINA TABLE 27. —Inorganic analyses of ground water from well 11, 855-1035 feet below [Values in parentheses are from analysis by E. A. Jenne] Collection date 11-3-71 1-15-73 1-26—73 2-9-73 2-23-73 3-16—73 3—30—73 4-13-73 5-10-73 6-16-73 SHUT ................................................................ 7.2 — 7.7 — 7.3 7.4 7.6 —— — — peeific conductance 32,000 31,800 32,100 32,200 32,100 32,100 31,200 20,600 31,100 30,100 (umhos at 25°C). Milligrams per litre Silica (Si02).. 8.6 10 11 10 14 10 10 10 11 11 Calcium (Ca). 345 330 320 330 320 330 320 340 330 330 lsfloaignesium (Mg 308 290 290 290 290 300 280 290 290 300 mm (Na)... 6,600 6,600 6,700 7,400 6,600 6,600 6,800 ,900 6,700 6,600 Potassium (K) 155 200 170 170 180 200 160 180 190 180 Bicarbonate (HCOa) . 232 — _ _ _ _ _ _ _ _ Sulfate ($04)... 210 210 220 220 200 180 2 210 210 190 Chloride (Cl) 12,000 12,000 12,000 12,000 12,000 12,000 12,000 11,000 12,000 12,000 Fluoride (F) ..... .6 .7 .5 .8 .6 .5 .4 .3 .5 N itrite-nitrate ( .0 0 .01 .03 — . 10 -— — — — Orthophosphate (P04) .................................. .00 06 03 — — .04 — — - —~ Residue on evaporation 20,400 — — — _ _ _ __ _ at 180°C. Hardness as CaCOa (Ca, Mg) 2,140 2,016 2,000 2,000 920 2,100 2,000 2,000 2,000 2,100 Micrograms per litre Aluminum (Al), total 186 30 10 20 10 0 10 O 0 0 (9.5) Arsenic (As) __ _ _ _ _ _ _ _ _ o Barium (Ba) — — _ _ ._ _ _ _ _ 500 Cadmium (Cd) — — — — — — — — — 80 (<.2) Chromium (Cr), total _ _ _ _ _ _ _ _ _ 20 Cobalt (Co) .. — — — — — — - — — 280 (.4) Copper (Cu). 251 _ _ _ _ _ _ _ _ 40 (1.2) Iron (Fe), total 1,730 1,700 1,300 1,400 1,200 1,100 1,200 1,300 1,100 590 (1900) Lead (Pb) .......... — 1 2.0 l 0 1 0 2 1.0 4 (<3.5) Lithium (Li) ........ 284 _ _ _ _ _ _ _ _ _ Manganese (Mn) 325 — — ~ — — — — — 420 (350) Mercury (Hg), total _ _ _ _ _ _ _ _ 7. Molybdenum (Mo) ...... — — — — — — -— — — 0 (1.4) Nickel (Ni) ...... — — — — -— — — — — 330 (<.5) Selenium (Se) .. _ _. ._ _ _ _ _ _ 9 Strontium (Sr) 16,600 — — — — — — -— — 25,00 Zinc (Zn) .......... 110 270 30 30 30 20 30 150 20 0 (4.2) TABLE 29. —Inorganic analyses of ground water Collection date 6—20-72 8-1-72 8—3-72 87-72 8-14-72 8-28-72 9-4-72 9-11-72 9—19-72 10-11-72 10-31-72 7.0 — — — — — — — — — pe 30,500 31,600 31,900 32,000 31,600 32,100 31,900 32,100 32,000 31,400 32,600 (nmhos at 25°). ‘ Milligrams per litre Silica (Si02) ..... 6.9 11 10 10 10 10 10 10 10 10 9.5 9.5 Calcium (Ca) 663 465 330 330 330 340 320 330 330 330 340 380 esium (Mg). 252 209 270 280 280 270 280 270 270 280 280 280 Maium (Na) ..... 5,550 6,800 6,600 6,400 6,500 6,600 6,700 6,500 6,600 6,400 6,500 6,200 Potassium (K). 17 160 150 180 17 180 170 180 160 160 170 200 Bicarbonate (HCOa) 307 — — — — — — — — — — Sulfate ($04). 215 1 180 17 1 1 0 170 1 Chloride (Cl). 11,500 12,000 11,000 11,000 12,000 12,000 12 000 12,000 12,000 11,000 11,000 Fluoride (F)... .8 .6 . . . .6 . . .6 . ‘ .5 Nitrite-nitrate (NOz-NOa). .2 — .01 0 0 0 .02 0 01 0 0 0 Orthophosphate (P04) .............. . .000 —- — -— — .05 —- — — -—- —— Residue on evaporation 19,400 20,800 — — — —- — — — — — — at Hardness at CaCOa 2,690 2,020 1,900 1,975 1,975 1,959 2,000 1,934 1,900 1,975 2,000 2,100 (C 8, Mg) Micrograms per litre Aluminum (Al), total _ 2,200 631 10 20 (3.4)1 0 10 10 o o o o o Arsenic (As) . — — 0 — 0 1 1 0 1 0 0 0 Barium (Ba) . — — 1,200 — 500 500 0 1,200 500 700 0 0 Chromium (C , . — —- 10 — 20 10 10 10 10 20 20 20 Cobalt (Co) ............... — — l — 0 2 1 1 2 l 1 0 Copper (Cu)... — — 20 — (15)1 20 20 20 20 2 (30)1 30 30 Iron (Fe), tota .. 327 2,090 5,100 3,600 4,200 5,300 5,400 8,100 13,000 7,500 35,000 34,000 Lead (Pb) ........ — — 1 2 1 1 4 2 2 2 2 O Manganese ( — — 610 — (8.9)1 660 (1.7)1 950 2,300 610 950 860 2,300 2,500 Mercury (Hg), total .. — — 0 — 0 0 0 0 0 0 0 0 lbdenum (Mo) — — 1 — 0 l 0 1 — 2 0 0 Nic e1 (Ni) — — 2 —— 4 2 2 2 2 12 15 0 Selenium (Se) — — 0 — 3 0 0 0 0 0 0 3 Strontium (Sr) — — 18,000 — 18,000 18,000 18,000 18,000 18,000 8,000 18,000 17,000 Zinc (Zn) —- — 10 20 5 40 3 90 3 7 Bromine (B — — — — (96)l — (83)‘ — — — — (95)1 — — — Vanadium (V).. .. — — — — —— (.4)l — — — — — —- — 1Analyst: L. Thatcher,U S. G. 8., Denver Colo. “Analyst: E. A. Jenne, U s G. s., Menl o n1,13ark Calif. BASIC-DATA TABLES 49 land surface TABLE 28. —— Inorganic analyses of ground water from well 12, 838— 974 feet below land surface [Values in parentheses are from analysis by E. A, Jenne] 7-3-73 7-20-73 914-73 10-31-73 Collection date _ _ _ _ 11-3-71 6-16-73 10-31-73 31,600 31,300 30,500 33,300 H _______________________________________________________ 7.2 __ _ gpecific conductance 32,000 31,400 32,100 (umhos at 25°C). 11 11 11 33(1) Milligrams per litre 32° 33° 32° Silica (SiOa) 9.0 7.7 3.6 290 290 290 300 Calcium (Ca 333 310 130 6300 6:800 7,000 6,300 Magnesium (Mg 310 300 300 17° 1'70 19° 21° Sodium (Na) .. 6,650 6,600 7,000 _ __ Potassium (K) 150 190 210 200 210 160 170 - 2 _ _ 12,000 12,000 12,000 14,000 3333391008) 233 240 220 -7 ~7 -4 ~30 Chloride (01).. 11,900 12,000 12,000 - — ~04 ~1 Fluoride (3).... .6 .2 _ _ _ 90 Nitrite-nitrate(NOa-NOa)-- ‘0 _ .03 _ “ _ Onllophosphate (P04) ...................... .03 — .13 2,000 2,000 2,000 2,100 Ref§%35.on evaporatmn at 20,600 — Haxdness as 0300:: (Ca, Mg) .......... 2,150 2,000 1,900 0 20 10 10 Micrograms per litre - : : : Aluminum (Al), total .. 445 3 (<10) 0 - — - - : 500 : - - - — _ 30 (.2) — _ _ _ _ _ 20 — 48—0 51—0 35—0 293 25—6 228 “(:33 I 1 2 3 2 .. 5,253 31,100 (31,000) 37,000 _ _ _ _ Lead (Pb) ........ — 5 (<35) 0 - ~ - — Lithium (Li) ...... 278 — —- — — — — Manganese (Mn) .. 265 610 (320) — - - - — Mercury (Hg), total .. — 10 — __ _ __ _ Molybdenum (M0) —— 0 (<1.2) — — — — — hsleifkel (mesa. _ g _ — ‘“ _ _ enium — — 2° 9° 6° 4° Strontium (St) . 16,600 23,000 — Zinc (Zn) _______ 49 30 (2.3) 40 from well 14, 843—972 feet below land surface. Collection date 11-7-72 11-13-72 11-22-72 11-3072 12-5-72 12.1372 12-19-72 12-2972 1-1573 1—26—73 29-73 2-23-73 6—16-73 1031-73 — — — — — — — — — 7.5 — 7.3 _ — 32,700 32,000 31,900 31,700 32,300 30,700 31,963 31,458 20,300 21,500 31,000 31,400 29,400 31,395 Milligrams per litre 10 1o 10 10 10 10 9.7 9.0 11 11 11 12 11 9.9 330 330 330 330 310 330 330 330 310 330 320 320 320 320 230 230 230 230 230 270 230 230 230 290 270 230 230 230 6,400 6,400 6,900 6,000 6,600 6,100 6,900 6,900 6,300 6,200 6,500 6,500 6,500 6,600 170 170 190 170 2 130 170 170 180 160 170 130 180 200 17—0 1'5 24—0 24-0 223 23—0 21-0 25—0 19—0 1_ 21—0 21—0 19~o 23— 12,000 6 11,000 4 12,000 7 11,000 6 12,000 7 12,000 12,000 6 12,000 6 11,000 5 12,000 5 12,000 11,000 11,000 12,000 :02 0' 101 :03 ‘ 0‘ :02 :01 ' :04 .11 —' — :03 _. _ _. _ _ 0 _ _ _ _ _ _ .07 42,000 1,975 2,000 2,000 1,900 1,934 2,000 2,000 1,900 2,000 1,900 910 2,000 2,000 Micrograms per litre 1o 0 10 20 o 0 0 o 10 10 0 0 10 (2.5)2 10 0 _ _ _ 0 — o o 10 1 0 0 — — 1,000 — — — 700 — — — — 300 — 400 _ — 20 _ _ — 10 — — — — 1o — 10 — (<2)2 — 1 _ — — 0 — — -— -— o — o — —— 30 _- _ _ 30 _ _ -. —- 30 — 30 — (.6)2 — 13,000 11,000 8,300 3,900 3,400 4,200 1,400 3,600 1,300 880 910 1,200 _ (.2)= — 1 o o 0 2 2 1 0 3 0 2,800 (6,500)2 5,400 650 — — -— 230 — — — — 300 — 250 3 (1.0)2 0 0 — — — o — — — — — o — (620)z — 1 —- _ _ 1 _ _ _ _ _ 1 _ _ _ 5 _ _ _ o _ _ _ _ — 1 — (<1.2)‘ - o — — — 4 — — — — — 4 _ (<5)! _ 13,000 — — —- 1,900 —- —- — -— 13,600 — 19,000 — _ 60 30 40 100 90 20 70 2o 30 20 30 40 _ -— — — — — — — — — — — — 60 80 (5.7)2 EEO Jam 3:02 ..m.U.m.D dawm .m A. 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BASIC-DATA TABLES TABLE 31.—Inorganic analyses of ground water from well 16, 843—983 51 TABLE 32.——Inorganic analyses of ground water from wells 2, 3, 4, feet below land surface and 5 [Values' in parentheses are from analysis by E. A. Jenne] Well No. ~ 2 3 4 5 Collection date Zone (feet below land surface) 855—1025 660-690 854—1025 854—1025 5-18-72 7 620-72 6- 14-73 103133 Collection date 6-15-71 6-15-71 6167i 0 615-711 0 gnawing; """"""""""" 31,000' 31,800 31,600 32,118 gpégiggggggfi 65633 11,000‘3 8380‘ 8,085 (#thB at 25" C) (mine at 25°C). Milligrams per litre Milligrams per litre Silica (SiOI) 9.8 10 9.7 9.8 Silica ($02)" 41 34 23 34 Calcium (Ca) 330 369 340 350 Calcium (Ca) 1,760 3,186 2,525 2,364 Wamifim (Mg 323 311 300 310 Magnesium (Mg) 24 85 34 49 (N a)" 71350 61750 61600 71000 Sodium (Na) 12 198 2.9 3.2 Potassium (K) 175 175 190 220 potassium (K 4.1 56 2.2 23 Bicarbonate (H003) . 228 220 — —— B' te ‘ o 0 _ _ Sulfa? (504% 615 255 24° 23° 81110133303300“) ‘ 9.6 35 8.0 19 Chloride (Cl) 12,200 12,200 12,000 13,000 Chloiide (Cl) 64 _ 230 144 Fluoride (F) »»»»» 5 -6 - Fluoiide (F). 3.2 1.1 1.3 1.3 Nitrite-nitrate (N01-N03)..07 .00 — .01 Nitrite-nitra 3.9 5.6 3'9 3'9 Oflhophosphate (P04) ------------------ -000 000 — -11 Orthophosphate (p01) ______________________ 1.5 4.2 1.3 1.1 Reggilggga evaporation 21,300 21,000 — — Residuce: on evaporation at 6,800 1,330 9,590 9,160 80" . Hacldnefis as 08008 2:150 2200 21100 21200 Hardness 111 011001 (Ca, Mg). 4,500 8,300 6,440 6,100 ( a, g) M' 0 er lit e Micrograms per litre m grams P 1- Aluminum (Al), total 6,900 3,250 6,800 7,100 Aluminum (Al). 1,120 10 0 Copper ( u) ______ 900 167 110 Arsenic (As). — 3 - Iron (Fe), total 8,780 31,000 8,280 8,000 1032;111:211 uifgéd) -— — 398 (< 1) : Manganese (Mn) 450 3,600 230 232 Chromium (Cr), Mal .. _ _ 10 _ Z1n0(Zn> ............. 167 5.900 1 6 Cobalt (Co). — — 280 (.6) — Copper (Cu) — — 30 (14) Iron (Fe), total 0 0 2,400 (5800) 2,600 Lead (Pb ........ — — 2 (<3.5 Manganese (Mn) .. — — 480 (390) — Mercury (Hg), total. — — 13 — Mol bdenum (Mo) — — 4 (<1.2) — Nic e1 (Ni) — — 300 (<.5) — Selenium (Se) — _ 11 _ Strontium (Sr —— — 24,000 — Zinc (Zn) — — 0 (80) 40 TABLE 34. — Organic analyses of ground water from well 1 1 [ND, not detected] Date 1-15-73 1-26-73 2-973 2-23-73 3-16-73 3-30-73 4-13-73 5-10-73 6-16—73 7-3-73 7-20-73 Milligrams per litre Acetic acid 13.85 4.37 9.65 18.52 20.97 22.45 24.07 26.32 29.42 41.52 24.24 Fonnic acid ND ND ND ND ND ND ND ND ND ND ND 1}- ND ND ND ND ND ND ND ND ND ND ND .283 .301 .306 .19 .269 .49 .422 .538 .578 .488 .573 TABLE 35.—0rganic analyses of ground water from well 14 [ND, not detected] Date 8-1-72 8-7-72 8—14—72 8-28-72 9-4-72 9-11-72 919-72 1011-72 10-31-72 11-2-72 Milligrams per litre Acetic acid. 19.67 55.38 71.98 101. 35 85. 94 138.6 59.61 474.70 758.85 60.23 Formic acid ND ND ND 16 1.42 1.38 1.10 1.27 ND 1FToluic aci .462 1.78 1.528 1. 688 1. 508 1.449 .949 6.648 16.69 .856 erephthalic .227 .856 .754 .930 .790 .332 .182 3.327 7.45 .398 Date 11-7-72 11-13-72 11-22-72 11-30-72 12-5-72 12-13-72 12-19-72 12-29-72 1-15-73 29-73 Milligrams per litre 63.81 84.07 20.00 4.90 11.66 21.07 — 5.71 — ND 3.08 .657 ND ND 95 ND ND — ND p-Toluic acid 1.258 1.386 .468 .131 3.01 .493 .161 .151 -— Terephthalic acid- .617 .723 .200 .062 .187 .157 .051 .042 .044 — TABLE 36.—0rganic analyses of ground water from well 15 [ND, not detected] Date 8-3-72 8-7-72 8-14—72 10-31-72 12-5-72 Milligrams per litre Acetic acid... 9.20 4.13 5.09 ND ND Formic acid . ND ND ND ND ND If“ -Toluic acid .25 .242 .245 ND ND erghthahc ac1d . .15 .064 .059 ND ND 5.5 5.0 5.5 3.0 1.5 2' U5. GOVERNMENT PRINTING OFFICE 1976—777-034/20