EAR'D 7 DAVj 2__ Perennial-Streamflow Characteristics Related to Channel Geometry and Sediment in Missouri River Basin GEOLOGICAL SURVEY PROFESSIONAL PAPER 1242 U.S. OEPO<=>'TO»V MAY 14 1382 Perennial-Streamflow Characteristics Related to Channel Geometry and Sediment in Missouri River Basin By W. R. OSTERKAMP and E. R. HEDMAN GEOLOGICAL SURVEY PROFESSIONAL PAPER 1242 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1982UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging in Publication Data Osterkamp, W. R. Perennial-streamflow characteristics related to channel geometry and sediment in the Missouri River basin. (Geogical Survey Professional Paper 1242) Bibliography: p. 19 Supt. of Docs. No.: 1 19.16 1. Stream measurements—Missouri Valley. 2. River channels—Missouri Valley. 3. Sediment transport—Missouri Valley 1. Hedman, E. R. II. Title. III. Series. GB1227.M7084 551.48'3'0978 81-607905 AACR2 For sale by the Branch of Distribution, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304CONTENTS Page Conversion factors..................................................................... IV Abstract ............................................................................... 1 Introduction............................................................................ 1 Purpose and scope................................................................ 1 Previous investigations.......................................................... 2 Data collection and analysis............................................................ 3 Onsite procedures................................................................ 3 Laboratory techniques and data analysis.......................................... 6 Results................................................................................. 7 Computer analyses................................................................ 7 Implications of the computer analyses.......................... 11 Effect of sediment......................................................... 11 Effect of gradient and other variables on width-discharge relations........ 13 Variability and error analysis............................................. 17 Utility and conclusions................................................................ 18 References cited ...................................................................... 19 Supplemental information............................................................... 22 ILLUSTRATIONS Page Figure 1. Diagram showing commonly used reference levels................................ 2 2. Map showing location of measurement and sampling sites..................... 4 3. Graph showing structural relations between active-channel width and mean discharge for stream channels of specified sediment characteristics.... 11 4. Graph showing structural relations between active-channel width and discharge characteristics for selected streams of the Sand Hills area, Nebraska................................................................... 13 5-11. Graphs showing structural relations between active-channel width and discharge characteristics for: 5. High silt-clay bed channels........................................... 13 6. Medium silt-clay bed channels......................................... 14 7. Low silt-clay bed channels............................................ 14 8. Sand-bed, silt-banks channels......................................... 15 9. Sand-bed, sand-banks channels......................................... 15 10. Gravel-bed channels................................................... 16 11. Cobble-bed channels................................................... 16 12. Graph showing width-gradient-discharge relations for mean discharges and the 25-year floods for sand-bed, sand-banks channels using representative values of gradient......................................................... 17 IIIIV CONTENTS TABLES Page Table 1. Descriptions of data groups based on channel material....................... 8 2. Width-discharge relations for channels of specified sediment properties.... 8 3. Width-discharge relations resulting from analysis of all data.............. 10 4. Width-gradient-discharge relations for channels of specified sediment properties.........................*1................................. 10 5. Width-gradient-discharge relations resulting from analysis of all data .. 11 6. Width-discharge relations for selected stream channels of the Sand Hills area, Nebraska......................................................... 12 7. Width-discharge and width-gradient-discharge relations for sand-bed, sand-banks channels of differing discharge variability................... 17 8. Discharge characteristics of selected streams ........................... 22 9. Geometry measurements and sediment characteristics of selected streams ... 29 10. Width-discharge and width-gradient discharge relations expressed in inch-pound units......................................................... 36 CONVERSION FACTORS The International System (SI) of Units is used in this report, although approximate conversions to inch-pound units are provided where practical. The coefficients of all power-function equations provided here are calculated from data expressed in SI units; conversions using inch-pound units are given in table 10. SI units used in this report may be expressed as inch-pound units by use of the following conversion factors: To convert SI units millimeter (mm) meter (m) kilometer (km) cubic meter per second (m3/s) Multiply by To obtain inch-pound units 0.0394 3.28 0.622 35.3 inch (in) foot (ft) mile (mi) cubic foot per second .(ft Vs)PERENNIAL-STREAMFLOW CHARACTERISTICS RELATED TO CHANNEL GEOMETRY AND SEDIMENT IN MISSOURI RIVER BASIN By W. R. Osterkamp and E. R. Hedman ABSTRACT Geometry, channel-sediment, and discharge data were collected and compiled from 252 streamflow-gaging stations in the Missouri River basin. The stations, with several exceptions, have at least 20 years of streamflow records and represent the complete ranges of hydrologic and geologic conditions found in the basin. The data were analyzed by computer to yield simple and multiple power-function equations relating various discharge characteristics to variables of channel geometry and bed and bank material. The equations provide discharge as the dependent variable for the purpose of making estimates of discharge characteristics at ungaged sites. Results show that channel width is best related to variables of discharge, but that significant improvement, or reduction of the standard errors of estimate, can be achieved by considering channel-sediment properties, channel gradient, and discharge variability. The channel-material variables do not have uniform effects on width-discharge relations and, therefore, are considered as sediment-data groups, or stream types, rather than as terms in multiple power-function equations. Relative to streamflow, narrowest channels occur when streams of steady discharge transport sufficient silt and clay to form stable, cohesive banks but have a small bed-material load of sand and coarser sizes. Stable channels also are associated with relatively large channel gradients, relatively large channel roughness, and armoring of bed and bank by coarse particle sizes. The widest, most unstable channels are ones that apparently transport a large bed-material load of sand sizes. The downstream rates of change of width with discharge reflect these trends, indicating that a given bed-material load necessitates a minimum width for movement of tractive material. Comparisons of standard errors of estimate given here with similar results from regional studies are variable. It is assumed, however, that a benefit of this study is that the use of the equations is not limited to the Missouri River basin. Besides the principal utility of estimating discharge characteristics of ungaged streams, the equations given here can be used for the design of artificial channels and can be used as a basis of predicting channel changes resulting from upstream alterations of the basin or channel. INTRODUCTION Numerous studies have related the geometry of alluvial stream channels to the amount and variation of discharge, sediment characteristics, climate and vegetation, and various basin characteristics. In recent years, a practical result of these studies has been the use of channel-geometry measurements to estimate the discharge characteristics of ungaged streams. By correlating variables of channel size and shape to specified flows at gaged sites, the relations, generally expressed as power-function equations, can provide estimates of discharge for the same recurrence frequencies at ungaged sites. Because a value of streamflow is determined, discharge is treated as the dependent variable. Therefore, the channel-geometry technique is the use of channel measurements as an indirect means of evaluating streamflow characteristics at a site. The channel-geometry technique differs from that of hydraulic geometry by relying on measurements taken from an identifiable geomorphic reference point or level in the channel section rather than from the water surface. The size and shape of the channel cross section are assumed to be the integrated resultant of all discharges, water and sediment, conveyed by that channel (Pickup and Rieger, 1979, p. 41; Osterkamp, 1979a, p. 2). Because it is based on channel rather than basin characteristics, the technique provides discharge estimates more closely related to the measured variables than do many of the older indirect techniques of estimating discharge. Most of these older methods use either drainage area, precipitation, and other basin characteristics as a means of- evaluating discharge, or they rely on correlation methods of transferring data from gaged sites to ungaged sites in contiguous or nearby basins. PURPOSE AND SCOPE Most published channel-geometry equations relate discharge to width or to width and depth. This study was initiated with the recognition that width-discharge relations vary significantly with channel-sediment properties (that is, the size characteristics of material forming the channel perimeter). Thus, numerical consideration of the sediment characteristics offers a means of refining the channel-geometry technique, as well as contributing to the understanding of fluvial processes. The purposes of the study were to: (1) eval- l2 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN uate which, if any, characteristics of channel sediment significantly affect channel morphology, (2) describe these effects quantitatively, thereby providing equations useful for discharge estimates, (3) gain further understanding of the processes that form and continually alter the shape of perennial stream channels, and (4) provide a basis for anticipating the results of natural or imposed upstream changes in the variables that determine channel size and shape. The hydrologic, geometry, and sediment data (see “Supplemental Information,” tables 8, 9) on which this paper is based were collected at or near 252 stream-flow-gaging stations in the Missouri River basin. The various gaging sites and drainage basins are representative of the wide range of hydrologic, geologic, topographic, and climatic conditions found in the Missouri River basin. The data were collected primarily at perennial streams, but several of the small channels have intermittent streamflow. Most of the streams have unregulated discharge; many of the relatively large streams, however, are partly regulated by one or more upstream reservoirs. PREVIOUS INVESTIGATIONS Relative to the numerous alluvial stream channels of the United States and elsewhere, streamflow-gaging stations provide current and historical discharge information on a small part of those channels from which such information is desirable. The increasing demand for current, inexpensive hydrologic information led to the development of the various indirect methods for estimating discharge characteristics from ungaged basins. The earlier methods relied on precipitation records and comparisons of streamflow and basin-characteristic data from nearby basins and generally were applied to relatively humid regions. In those areas, variations in precipitation and runoff are less significant than in arid areas (Riggs, 1978). Because the channel-geometry method relies only on channel properties, its use is less restricted by climate and other basin variables than the earlier indirect methods. Among the early papers dealing with the effect of discharge on channel shape were articles on regime theory (no net erosion or deposition) by Kennedy (1895) and Lacey (1930). Though not the first to apply the dynamic-equilibrium concept to rivers, Leopold and Mad-dock (1953) published the first widely accepted benchmark paper of the relations between perennial discharge and channel properties. They established power-function equations between mean discharge and stream width, mean water depth, and mean velocity. For practical purposes, a shortcoming of the study by Leopold and Maddock (1953), and of several subse- quent papers, was that a relatively permanent, observable datum from which channel width and depth could be measured was not used. Instead, measurements were related to the level of the water surface at mean discharge. Hence, the technique was termed hydraulic geometry. A study of the Brandywine Creek drainage by Wolman (1955) reduced the problem by the use of measurements determined for bankfull stage (fig. 1), a readily observable feature in that drainage basin. Other hydrologists in England and Wales (Nixon, 1959), central Pennsylvania (Brush, 1961), Illinois (Stall and Fok, 1968), Alaska (Emmett, 1972), and elsewhere made similar measurements at bankfull stage. Other workers have used reference levels for channel measurements taken at the top of the “main channel” (Riggs, 1974; Lowham, 1976) or “whole channel” (Riggs and Harenberg, 1976); these levels were defined similarly to and are virtually coincident with the bank-full stage. From 1953 to recent years, a variety of hydraulic-geometry studies resulted in numerous power functions relating width with variables of discharge for the “downstream” case (Leopold and Maddock, 1953). In 1966, at the suggestion of W. B. Langbein, attention within the U.S. Geological Survey was turned to in- BANKFULL (C-C‘) ACTIVE-CHANNEL (B-B'I Figure 1.—Commonly used reference levels.DATA COLLECTION AND ANALYSIS 3 channel reference levels for discharge-geometry correlations. Langbein recognized that active, short-term geomorphic features might be identifiable in all alluvial stream channels and that they are indicative of recent (decades or less) rather than historic stream dynamics. The suggestion was advanced as a possible means of estimating flow characteristics of ungaged basins; the intent was to determine discharge from channel characteristics. The first paper using this suggestion was by Moore (1968), who estimated mean runoff from Nevada basins on the basis of channel width and mean depth measured from the top edge of inchannel, or depositional, bars (fig. 1, A-A'). The bars were regarded as the highest channel features shaped by annual bed-material movement and the lowest prominent bed forms. The same technique was used in California by Hedman (1970); in western Georgia, U.S.S.R., by Kopaliani and Romashein (1970); in Kansas by Hedman and Kastner (1972); in Colorado by Hedman, Moore, and Livingston (1972); in New England by DeWalle and Rango (1972); and throughout the Missouri River basin by Hedman and Kastner (1977). Experience has shown, however, that measurements based on bar geometry are subject to the same problem as is the bankfull stage method of Wolman (1955) the lack of a universally recognizable datum. Many slow-moving streams, for example, that have a well-defined bankfull stage (flood plain) do not exhibit bar geometry. In addition, deposition of material forming inchannel bars occurs principally during recession of relatively large discharges. Thus, a spurious relation is possible between bar geometry and all discharge rates exceeding that required for movement of point-bar material. An alternative in-channel reference level, therefore, was proposed by Hedman, Kastner, and Hejl (1974), the active channel. This feature (fig. 1, B-B') is described by Osterkamp and Hedman (1977, p. 256) as ***a short-term geomorphic feature subject to change by prevailing discharges. The upper limit is defined by a break in the relatively steep bank slope of the active channel to a more gently sloping surface beyond the channel edge. The break in slope normally coincides with the lower limit of permanent vegetation so that the two features, individually or in combination, define the active channel reference level. The section beneath the reference level is that portion of the stream entrenchment in which the channel is actively, if not totally, sculptured by the normal process of water and sediment discharge. Recent studies that used the active-channel reference level, or a similarly defined level, include those of Scott and Kunkler (1976), Hedman and Kastner (1977), and Osterkamp (1977, 1979a). Except for a large number of papers concerning the hydraulics of sediment transport and the behavior of various sediment types in laboratory flumes, literature relating sediment characteristics to properties of channel morphology is much less extensive than for that of streamflow characteristics. Among the papers that have considered the effect of sediment on channel morphology are those of Schumm (1960a, b, 1963, 1968). These papers related a weighted mean percentage of bed and bank silt-clay to width-depth ratios of alluvial channels, but the papers did not consider discharge directly. The final study of this sequence (Schumm, 1968) provided a basis of prediction of the changes in morphology that might occur as a result of a significant change in the regimen of sediment transport of a stream, whether natural or induced. Combining the channel-geometry techniques of Hedman, Kastner, and Hejl (1974) with the use of channel silt-clay content (Schumm, 1960b), Osterkamp (1977) developed simple and multiple power-function equations relating mean discharge to channel width and sediment characteristics of Kansas streams. The equations assumed that mean discharge exerts a fixed effect on channel width that is modified by other variables, particularly the particle sizes of channel material. The relations described herein evolved from techniques developed during the study of perennial stream of Kansas. DATA COLLECTION AND ANALYSIS Sites at or near streamflow-gaging stations where channel-geometry and channel-sediment data were collected for this study are shown in figure 2. The site numbers in figure 2 refer to lists of the discharge (table 8) and channel-properties (table 9) data from which the power-function equations were developed. ONSITE PROCEDURES Measurement and sampling procedures at channel-geometry sites were developed using several basic assumptions. Among these are that: (1) A channel section generally is narrowing toward a minimum width corresponding to the recent discharge characteristics of the stream; (2) a section below the active-channel reference level can be recognized at all sites and is indicative of those discharge characteristics; (3) the sediment load of a stream, both suspended and bed material, has a quantitative effect on geometry-discharge relations; and (4) the particle sizes of bank material are indicative of the suspended sediment, whereas the bed material is indicative of the traction-force load. Thus, the principal data collected at each gage were those of geometry and of the variables inferred to be most closely related to the geometry—characteristics of4 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN dakota MONTANA J^nor t h issouJLL River 7 DAKOTA s 0 U T Grand River Morea“i River JUVER 8' i NEBRASKA^ *74 nSt'-' • NORTH WYOMING COLORADO n of station 8 and 9 RIVER 0 200 KILOMETERS 0 100 MILES Figure 2 (above and facing pages).— Location of measurement and sampling sites.DATA COLLECTION AND ANALYSIS 5 906 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN water and sediment discharge. Other variables affecting the width-discharge relations that were not directly considered in this study include discharge variability (including the effects of streamflow regulation), climate and riparian vegetation, and other upstream channel or basin changes resulting from water-use and land-use activities. In all instances, geometry and bed-and-bank data were collected at or near gage sites where discharge data were available. To the extent practical, measurements were made in a generally straight reach where flow velocities were relatively uniform across the channel width. If a stream had pool-riffle sequences, a site normally was selected a short distance upstream or downstream from a riffle. Sites were avoided if bedrock was apparent in the channel bed, if bank instability occurred in or directly above the active-channel section, or if there was local evidence of recent scour or deposition. Channel reaches altered by riprap or other types of natural or unnatural linings or obstructions were avoided, as were reaches where bank surfaces were ero-sional rather than depositional. At each site, width and mean-depth measurements were made from the active-channel reference level (fig. 1, B-B'). Integrated or composite sediment samples were obtained by collecting sediment at equally spaced intervals across the channel bed and up each bank. Thus, three separate composite samples, representing the bed and each bank, were collected at each measurement site. If the channel material was mostly gravel or coarser sizes, in situ pebble-count techniques or other suitable methods were used to describe the bed-and-bank material (Wolman, 1954). For all sites, care was taken not to sample those parts of the channel transitional between bed and banks; thereby, contamination of samples by material from other parts of the channel section largely was avoided. In general, sites were selected to insure that the bed samples were typical of bed-material movement during periods of normal discharge rates and that the bank samples were representative of material taken from suspension. Specific procedures for channel measurement and sampling are given by Osterkamp (1979b). LABORATORY TECHNIQUES AND DATA ANALYSIS Discharge data (table 8) were compiled from the records of the various gage sites. All discharge data were computed using established techniques of the U.S. Geological Survey. Values for the discharge characteristics (table 8) are based on a minimum of 20 years of continuous steamflow records, although several excep- tions were made in order to expand the ranges of stream size and geographic coverage. A standard particle-size analysis (dry sieve, VA tube, and wet sieve) was made of each of the three sediment samples from each site (Guy, 1969). Summary results of the analyses are listed in table 9 as the median particle sizes and the silt-clay percentages of the bed-material samples and as the values of the silt-clay percentages for the two bank-material samples. Channel gradients (table 9) were computed from 7 Vi-minute topographic maps. Except where significant tributary inflow or diversion was apparent near a gage, the gradient measurements were centered at or near the gaging stations. For large streams, the calculated gradient represents a reach of as much as 20 km (12 mi) in length, whereas reaches as short as 1.0 km (0.62 mi) were used to calculate the gradient of small streams. Most equations given in this report are simple or multiple power functions of the form: Qv= aWb, (1) Qv=aWbGc, (2) where Qv is a discharge characteristic (such as a flood discharge with a 2-year recurrence interval); a is a coefficient; W and G, respectively, are channel width and gradient; and b and c are exponents. The equations were developed by use of a stepwise regression program (BMD02R) from the Biomedical Computer Programs of the School of Medicine, University of California (Dixon, 1965). The program forms a sequence of linear regression equations in a stepwise manner. In the first step, a simple relation is defined with the independent variable that most effectively explains the site-to-site variation of a selected flow characteristic. In each subsequent step, one variable is added to the equation. For those computer analyses yielding simple-regression (power-function) equations (one independent variable), the program was modified to convert the result to a structural analysis (Mark and Church, 1977; Osterkamp, McNellis, and Jordan, 1978). This statistical technique distributes error to both the dependent and independent variables. The closely related technique of least-squares regression differs by ascribing all error to the independent variable. Because errors must be assumed for all the variables considered in this study, structural analysis is considered the better method of developing simple power-function equations. The two techniques, however, when applied to groups of data presented here, provide results that do not differ markedly. The standard errors of estimate (SE), the correlation coefficient (R), and the F-ratios are provided as outputRESULTS 7 of program BMD02R. The standard error of estimate of a regression or structural analysis is a measure of the deviation or scatter of the dependent variable about the linear relation; the correlation coefficient is an indicator of data scatter relative to the range of the data. The F-ratio is the ratio of the explained to unexplained variance in the dependent variable. The level of significance can be determined from the F-ratio and the numbers of cases and variables. The levels of significance provided in tables of this report are given as decimal fractions, expressing the likelihood that the observed F-ratio has occurred by chance. Thus, a significance level of 0.01 indicates that the probability of the observed relation occurring randomly is no greater than 1 percent. RESULTS Previous studies (Schumm, 1960a, b, 1968; Hedman and Kastner, 1977; Osterkamp and Hedman, 1977; Os-terkamp, 1977, 1979a) provided evidence that channel-sediment characteristics have a measureable effect on geometry-discharge relations. The initial computer analyses of this study, therefore, were designed to identify geometry and sediment variables that effectively provide a basis for defining stream-channel types from the entire data set (tables 8, 9). These preliminary analyses produced the following deductions: 1. Except for some braided streams, the size distribu- tion of fluvial sediment generally has a greater effect on channel morphology than does sediment discharge. 2. Multiple power-function equations need to be used cautiously because the effects of complicating variables on width-discharge relations generally are not linear. 3. Because channel shape is partly the result of the sediment sizes transported by a stream, indiscriminate use of geometry and channel-material variables in multiple power-function equations results in redundency. 4. Variables other than channel sediment, such as dis- charge variability and riparian vegetation, have significant effects on geometry-discharge relations and, therefore, account for part of the observed standard errors of estimate. The principal purpose of the relations given in this paper is to provide rapidly calculated estimates of discharge characteristics. Therefore, the stream classes or groups used here were defined to include the range of sediment conditions normally found in natural alluvial channels, and the equations developed for the groups require only data that are quickly and easily measured or estimated. COMPUTER ANALYSES The 252 sites in the Missouri River basin at which data were collected (fig. 2; tables 8, 9) were selected using criteria previously discussed. Criteria for site selection were not imposed rigidly, however, but were relaxed in some cases to extend the range of data. Accordingly, the data used for this paper include very small channels with less than 20 years of streamflow records and some large streams (particularly the Missouri River), which are partly regulated and may be affected by nearby channel modifications or stabilization structures. It is assumed that the use of these data, however, increases the confidence that can be placed in the resulting power functions, although they increase the standard errors of estimate. Mean discharges (table 8) of the data used in the computer analyses range from 0.00402 to 2,260 m3/s (0.142-79,800 ft3/s), and measured active-channel widths range from 0.762 to 430 m (2.50-1,410 ft). These ranges comprise about 5.75 log cycles for mean discharges and 2.75 log cycles for active-channel widths. Similarly, the channel-material characteristics of streams sampled in the Missouri River basin range from those having as much as 92 percent silt and clay in the bed material to alpine streams with median particle sizes as great as 250 mm (9.8 in.). Measured gradients range from 0.000060 to 0.028 (nondimensional), or about 2.7 log cycles. No attempt was made to quantify and consider the effects of riparian and channel vegetation as independent variables, although qualitative evidence indicates that changes in riparian vegetation, in particular, can have a pronounced effect on width-discharge relations. Discharge variability also is known to have substantial effects on channel morphology (Schumm and Lichty, 1963; Burkham, 1972; Osterkamp, 1978, p. 1267). Limited attention is given to discharge variability here, however, because normally it is a variable that cannot be measured or estimated well at ungaged sites. Previous investigations and the preliminary computer analyses led to the classification of channels into seven groups according to channel-sediment properties for further analysis. The sediment properties on which the groups are based (silt-clay content and median particle size of the bed material, and silt-clay content of the bank material) led to simple power-function equa-8 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Table 1.—Descriptions of data groups based on channel material [Channel types used for identification purposes are not intended to be descriptive of the stream types. SCbd is silt-clay content of bed material in percent, SCbk is the higher silt-clay content, in percent, of the two bank-material samples; and d50 is the diameter size of particles, in millimeters, for which equal parts of the sample are of greater or smaller weight] Channel No. of Channel-sediment types sampling sites characteristics High silt-clay bed. . . 15 SCbd = 61-100 dso<2.0 Medium silt-clay bed.............. 17 SCbd = 31-60 d„„<2.0 Low silt-clay bed ... 30 SCbd = 11-30 d50<2.0 Sand bed, silt banks.......... 33 SCbd = l-10 SCbk =70-100 d50<2.0 Sand bed, sandbanks........... 96 SCbd = l-10 SCbk = l-69 dso<2.0 Gravel bed............ 42 d50 = 2.0-64 Cobble bed............ 19 d60>64 tions relating width to discharge for the entire ranges of each group. The sediment properties are not expressed as independent variables of a multiple power-function equation because such a relation would necessarily be either too complex for general use or would be oversimplified and inaccurate. Specifically, none of the three channel-sediment properties on which the channel types are defined (table 1) have a linear or even consistent effect on width-discharge relations. Relative to discharge, active-channel width increases with increasing sandiness (decreasing silt-clay content) because the cohesiveness afforded by the silt and clay produces relatively stable banks not easily eroded by floods. If a significant amount of fine material is present in the bed material, cohesive banks are virtually assured. If, however, the bed material is largely sand, the silt and clay (taken from suspension) in the banks can be correlated with width-discharge relations. For streams of similar discharge characteristics, minimum channel widths generally occur if the median particle size of the bed material is very small (high silt-clay content). Width tends to increase with increasing median particle size, reaching a maximum when the bed material is well-sorted, medium- to coarse-grained sand (Osterkamp, 1977). For median particle sizes increasingly greater than about 2 mm (0.08 in.), the course fraction of the bed material provides an armoring or stabilizing effect similar to that provided by the cohesiveness of silt and clay. The result is narrower, more stable channels than those that have sand beds. The effects of particle-size ranges are considered indirectly because the channel types (table 1) are defined in terms of both silt-clay content and median particle size. Equations relating discharge characteristics to active-channel width for the seven channel types (table 1) are listed in table 2. Casual inspection of the equations for mean discharge shows that, for channels of similar width, the greatest mean discharges occur in channels of fine-grained bed-and-bank material. As the sandiness of the channel material increases, the mean discharges decrease to the extent that the predicted mean discharge of a sand-bed, sand-banks channel 20 m (66 ft) in width is only 21 percent of the predicted discharge for a high silt-clay bed channel of similar width. As median particle sizes, and the resulting armored effect, increase from about 2 mm (0.08 in.), the trend is Table 2.—Width-discharge relations for channels of specified sediment properties [SCbd is silt-clay percentage of bed material; SCbk is silt-clay percentage of bank material; and dM is median particle size of bed material, in millimeters. Q is mean discharge, in cubic meters per second; Qt through Ql00 are flood discharges, in cubic meters per second, of recurrence intervals 2 through 100 years; and W is active-channel width, in meters] Channel type (table 1) Equation Standard error of estimate, SE (percent) Coefficient of correlation, R Level of significance (from F-ratio for width) High silt- Q = 0.031W212 35 0.98 0.001 clay bed Q, = 2.0W1'86 52 .94 .001 (SCM = Q5 = 5.3W1'77 54 .93 .001 61.100; Q,„ = 8.1W1'74 57 .92 .001 dso<2.0) Q„ = 13W171 62 .90 .001 Q10 = 16W171 65 .89 .001 Qioo = 19W1'74 69 .88 .001RESULTS 9 Table 2.—Width-discharge relations for channels of specified sediment properties—Continued Standard Level of Channel error of Coefficient significance type Equation estimate, of correla- (from (table 1) SE tion, R F-ratio (percent) for width) Med. silt- Q = 0.033W176 56 0.92 0.001 clay bed Q2 = 2.6W1'27 118 .63 .01 64) Q2 = 0.82W143 80 .90 .001 Q6 = 3.1W116 74 .87 .001 Qlo = 6.0W1,03 72 .85 .001 Q26 = 12W0'89 74 .80 .001 Q5„ = 20W°-80 81 .74 .001 Q,oo = 28W0'75 91 .66 .005 reversed, and predicted mean discharges increase for channels of similar width. The predicted mean discharge of a 20-m (66-ft) wide channel armored with cobbles and boulders is 60 percent greater than that of the sand-bed, sand-banks channel. In general, the results in table 2 for a given channel type show increasing coefficients and decreasing exponents as magnitudes and recurrence intervals of the floods increase. The causes of the decreasing exponents are (1) the tendency for increased attenuation of flood discharges in the downstream direction with increase in recurrence interval and (2) the tendency for decreased peak rates of precipitation and runoff, per unit area of a drainage basin, with increasing basin size. In other words, for most alluvial streams, the ratio of the 10-year flood to mean discharge (QJQ) decreases as mean discharge, drainage area, and flood-plain size increase in the downstream direction. For example, a greater rate of decrease generally occurs for the ratio QJQ than for QJQ. The result is a smaller exponent associated with Qb0 than with Q10. The relations for each stream type of table 2 are based on differing discharges (mean discharge or flood discharges of specified recurrence interval) but on the same active-channel widths. Thus, the relatively large exponents associated with mean discharges indicate that mean discharge commonly increases at a greater rate in the downstream direction than do, for example, the 50-year floods, which have relatively small associated exponents. As comparisons to the various channel-type relations of table 2, structural analyses of the discharge characteristics with active-channel width were made for the entire file of 252 data sets (tables 8, 9). The results (table 3) demonstrate the differences that occur when the data are not separated into the sediment-characteristics groups (table 1). The standard errors of estimate for these relations indicate considerable data scatter, particularly for the large flood discharges, and the possibility of large errors if the equations were to be used for predictive purposes. As examples, if very silty bed channels and cobble-bed channels of 20-m (66-ft) width are considered, the discharges predicted by the equation for mean discharge of table 3 are 74 percent (silty bed) and 24 percent (cobble bed) less than those given by the corresponding equations in table 2. As median particle sizes of bed material decrease from very course to very fine, associated channel gradients also decrease (Lane, 1957; Osterkamp, 1978). The relation is not uniform, however, particularly for sand channels. Therefore, gradient cannot be incorpo-10 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Table 3.—Width-discharge relations resulting from analysis of all data [Q is mean discharge, in cubic meters per second; Q2 throughQ100 are flood discharges, in cubic meters per second, of recurrence intervals 2 through 100 years; and W is active-channel width, in meters.] Equation Standard error of estimate, SE (percent) Coefficient of correlation, R Level of significance (from F-ratio for width) Q = 0.027W1'71 79 0.93 0.001 Qi = 1.9W1 22 109 .81 .001 Q, = 5.8W110 112 .77 .001 Q,„ = 9.9W104 116 .74 .001 Q25 = 18W0'97 120 .71 .001 Qj0 = 25W° 94 124 .68 .001 = 0.27W° 94G-0'46 117 .82 .001, .005 SCbk<70; Q10 = 0.47W°'88G _0'46 125 .80 .001, .005 dt„<2.0) Q25 = 0.91W°'83G-0'44 134 .77 .001, .01 Qso II It- © bo 0 O 1 p CO 140 .74 .001, .025 Q100 = 2.2W°'77G_0'42 146 .72 .001, .025 Gravel bed Q (d50= Q2 2.0.64) Q* = 1.9W°'75G-0'27 77 0.79 0.001, 0.05 Q10 = 2.8W°'63G-0'32 79 .74 .001, .025 Q25 = 4.6W°'50G-0'36 85 .68 .001, .025 Qso = 6.6W°'42G-0'36 91 .63 .005, .025 Q100 = 9.3W°-35G-0-37 97 .57 .025 .025, Cobble bed Q = 0.024W1-82G“001 25 0.99 0.001, (d5„>64) q2 = 0.14W139G_o-34 69 .93 .001, .025 q5 = 0.40W113G 038 58 .92 .001, .005 Q.o = 0.79W°'"G""0'38 55 .91 .001, .005 = 1.8W°'85G-0'36 60 .87 .001, .01 Qbo = 3.3W° 76G-0'34 70 .82 .001, .025 Q100 = 5.8W°'68G-0'31 83 .74 .001, .10 cent of that for all data (table 5). A general improvement in precision, as indicated by the standard errors, is evident also for the flood relations, although it is less pronounced than that for mean discharge.RESULTS 11 Table 5.—Width-gradient-discharge relations resulting from analysis of all data (Q is mean discharge, in cubic meters per second; Q2 through Ql00 are flood discharges, in cubic meters per second, of recurrence intervals 2 through 100 years; W is active-channel width, in meters; and G is channel gradient (nondimensional)] Equation Standard error of estimate, SE (percent) Coefficient of multiple correlation, R Level of significance (from F-ratio for width, gradient) Q = 0.0074W1'54G-0'26 73 0.94 0.001, 0.001 Q2 = 0.24W°'96G-0'40 98 .84 .001, .001 Q5 = 0.53W°'82G-0'45 98 .82 .001, .001 Qi„ = 0.85W°'75G-0'47 101 .80 .001, .001 Q2S = 1.5W°'69G-0'48 105 .77 o o o o Q5„ = 2.1W065G _0-48 110 .75 .001, .001 Ql00 = 2.9W°’61G-0'48 114 .73 .001, .001 The width-gradient discharge relations of tables 4 and 5 are difficult to compare directly with similar width-discharge relations of tables 2 and 3. Owing to weak intercorrelation of gradient with width and discharge, a width exponent from table 4 or 5 must differ from the corresponding exponent of table 2 or 3. IMPLICATIONS OF THE COMPUTER ANALYSES The practical result of this study is the presentation of sediment-dependent equations for the purpose of general (nonregionalized) estimates of discharge characteristics (tables 2, 4). Of perhaps greater consequence, however, is the demonstration that sediment variables of the channel perimeter have a quantitative, statistically significant correspondence with active-channel width. Previously cited studies have demonstrated that correspondence, but because the data were of limited number or of regional scope, the results have been subject to question. Owing to the extensive range of hydrologic, climatic, and geologic-topographic conditions represented by the data in tables 8 and 9, the differences among corresponding discharge equations of tables 2 and 4 principally appear to be the result of differences in fluvial-sediment conditions. Local or regional differences in variables, such as climate and geology, no doubt account for a part of the standard errors, but it appears unlikely that they are the major cause of the differences among the equations. EFFECT OF SEDIMENT Comparisons of the equations of tables 2 and 4 indicate several generalizations regarding the effect of channel sediment on geometry-discharge relations of alluvial stream channels. The generalizations are advanced as observations only, with little attempt to relate them to theoretical considerations of hydraulics and sediment movement. It is noted, however, that the observations generally are consistent with established theory. (1) Just as the widest streams, relative to discharge characteristics, occur in highly sandy channels, the smallest exponent for the width-mean-discharge relation is associated with highly sandy channel material. These trends are illustrated in figure 3, a graphical representation of the equations that relate active-channel width and mean discharge for the seven channel types (table 1). For channels of similar width, the largest discharges and exponents occur for the high silt-clay bed channels; discharges and exponents steadily decrease for channels of increasing sandiness and increase again as increasing median particle sizes and armoring provide channel stability (table 2; fig. 3). The coefficients, of course, reflect the changes in width relative to discharge, but they are difficult to compare owing to the variable exponents. ACTIVE-CHANNEL WIDTH (W), IN FEET Figure 3.—Structural relations between active-channel width and mean discharge for stream channels of specified sediment characteristics.12 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN (2) The general instability of the sandiest channels is reflected by relatively large standard errors of estimate; whereas, the relations for the most stable channels (high silt-clay bed and cobble-bed channels) tend to have the smallest standard errors (table 2). It is inferred that flood discharges generally have minimal effect on widths of the relatively stable channels but cause substantial erosion and widening of the sand channels. Depending on recent discharge histories, therefore, the widths of the sand channels show significant variation relative to discharge characteristics, causing large standard errors of estimate. (3) The exponents for the mean-discharge equations (table 2) show an apparent inverse relation with the sand content of the channel material. The results of this study and previous studies (Hed-man and Kastner, 1977; Osterkamp, 1979a), however, indicate that variation in the exponents principally is the result of differences in the amount of bed-material load transported by the stream. This conclusion is supported also by a variety of laboratory (flume) studies, particularly an exhaustive study of channel morphology by Khan (1971). Streams that transport a small amount of sediment as bed load, such as the high silt-clay bed streams and well-armored (cobble-bed) streams, give relatively large exponents for the width-mean-discharge relation. Because sand sizes generally account for a large part of the bed-material movement (of those streams in which bed load is a significant part of the total sediment load), channels formed primarily of sand ordinarily have relatively small exponents for width-mean-discharge relations. Exceptions occur where stream flow on sand but are largely incapable of moving the sand. An example is many spring-effluent channels that have very steady discharges, a lack of erosive flood peaks, relatively narrow and stable geometries, and an exponent for the width-mean-discharge relation of about 2.0 (Osterkamp, 1979a). (4) For streams of specified discharge characteristics, the widths of stable channels in large part appear to be a function of the sediment that is moved by traction forces. Streams that discharge relatively large amounts of sand as bed-material load, therefore, require a large channel width to maintain sediment movement. As extreme examples of streams that convey a large part of the total sediment discharge as bed-material load, structural analyses were made for two small groups of data from the Sand Hills area of Nebraska (table 6; fig. 4). The two groups of data both represent highly sandy (dune sand) basin conditions but are treated separately owing to differences in the content of silt sizes in the soils and, therefore, in the runoff characteristics. Consistent with the observations presented here, most of the Sand Hills channels are very wide relative to discharge, and the data have relatively small exponents for the width-mean-discharge equations (table 6). Table 6.—Width-discharge relations for selected stream channels of the Sand Hills area, Nebraska [Q is mean discharge, in cubic meters per second; Q2 through Ql00 are flood discharges, in cubic meters per second, of recurrence intervals 2 through 100 years; and W is active-channel width, in meters] Data source Equation Standard error of estimate, SE (percent) Coefficient of correlation, R Level of significance (from F-ratio for width) North and Q = 0.46W°f° Middle 10 0.98 0.001 Loup Q,= 0.031 Wf Qs=o.i3W118 26 .97 .001 Rivers. 35 .97 .001 Q,„=0.0075W^ 40 .96 .001 Q„=0.0040W^® 47 .96 .001 Q,„=0.0025W^ 52 .95 .001 Q100= 0.0016W2’90 56 .95 .001 Calamus, Cedar, Elkhorn, North Fork Elkhorn, and South Loup Rivers. Q=0.27W°86 16 .95 .001 (5) Owing to increases of basin size and attenuation of flood discharges in the downstream direction, exponents of width in table 2 for the various channel types of table 1 typically decrease as the recurrence interval increases. Thus, for a specified channel type, the percentage differences among the various flood magnitudes generally are greatest for floods with a small recurrence interval and progressively decrease as the flood magnitudes increase (table 2). These trends for the seven channel types (table 1) are represented in figures 5-11. Exceptions to these generalizations are provided by streams of the Sand Hills (table 6; fig. 4). Owing largely to the unique geology of the area, streams of the Sand Hills have (1) increasing discharge variability, (2) an increasing tendency for braided channel patterns, and (3) increasing exponents with flood magnitudes in the downstream direction (Osterkamp, 1978).RESULTS 13 ACTIVE-CHANNEL WIDTH (W), IN FEET O o o LU 0) cc LU Q. UJ LU U. O CD 3 O a LU O DC < X o CO a ACTIVE-CHANNEL WIDTH (W), IN METERS Figure 4.—Structural relations between active-channel width and discharge characteristics for selected streams of the Sand Hills area, Nebraska. EFFECT OF GRADIENT AND OTHER VARIABLES ON WIDTH-DISCHARGE RELATIONS In tables 4 and 5 channel gradients are treated as independent variables, although it is acknowledged that they are dependent chiefly on the water and sediment discharge of a channel. Previous studies (Lane, 1957; Osterkamp, 1978) have established gradient-discharge relations and the manner in which they vary according to differences in bed-material sizes. If channel-sediment characteristics were presented as power functions in the equations of this paper instead of as ranges or groups of width-discharge data, the insertion of a gradient expression would be redundant. Within each channel-type group (table 1), however, no sediment-size distinctions are made, and the use of a gradient term is valid. For each channel type, it is assumed that gradient has an approximately linear effect (after logarith- mic transformations) on the width-discharge relations; although, as previously noted, this assumption is invalid when applied to the spectrum of sediment conditions (table 5). It was established (Osterkamp, 1978) that: G=aQ-°'25, (3) or, in terms of mean discharge (Q) as the dependent variable, Q=a’G-40, (4) thereby indicating that with an increase of mean discharge in the downstream direction a general decrease in channel gradient (G) occurs. The coefficients, a and a', in large part vary with the characteristics of channel sediment (Osterkamp, 1978). When included in a multiple power-function equation, the gradient exponent is reduced, of course, in absolute value, but it must retain a negative value to provide a meaningful physical relation to discharge estimates. In general, Figure 5.—Structural relations between active-channel width and discharge characteristics for high silt-clay bed channels.DISCHARGE (Q), IN CUBIC METERS PER SECOND 14 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN ACTIVE-CK.VNEL WIDTH (W), IN FEET Figure 6.—Structural relations between active-channel width and discharge characteristics for medium silt-clay bed channels. the gradient exponents (table 4) range from —0.3 to —0.7, regardless of flow frequency. These exponents result in as much as a three-fold variation for typical ranges in gradient within the several channel-type groups. As examples, width-discharge equations for sand-bed, sand-banks channels (table 4) are illustrated in figure 12 for mean discharges and floods of 25-year recurrence intervals using representative values of gradient for that channel type. These examples show about a two-fold difference in predicted discharges for the range of gradients selected (fig. 12). Numerous studies of downstream hydraulic geometry and_ channel geometry demonstrate that mean depth (d), like width, has a general power-function relation with discharge characteristics: Q = df, (5) where f is a positive exponent. For most channel types, mean depth increases with mean discharge but at a slower rate than does width. Mean depths were depths that were measured (or, in some instances, estimated) at all sites included in this study, and the depths are listed in table 9. Channel depth, however, can be variable within relatively short reaches, as well as through time at the same section. Hence, representative depths cannot be defined reliably; thus, depth shows little statistical significance (Schumm, 1961; Hedman, Kastner, and Hejl, 1974). Despite this difficulty, a number of computer analyses that included considerations of depth were made to determine whether mean depth could provide improvement to the width-discharge relations. The resulting relations are not shown because the exponent for depth was not statistically significant and was unrealistically negative. Two variables that can have a large effect on width-discharge relations but which receive limited attention here are climate, particularly as reflected by riparian vegetation, and stream flashiness. The amount, type, and maturity of riparian vegetation are known to have measurable effects on the sizes and shapes of alluvial channels (Schumm and Lickty, 1963; Burkham, 1972; Osterkamp, 1977). Because the stablizing effect that a ACTIVE-CHANNEL WIDTH (W), IN FEET ACTIVE-CHANNEL WIDTH (W), IN METERS Figure 7.—Structural relations between active-channel width and discharge characteristics for low silt-clay bed channels. DISCHARGE (Q), IN CUBIC FEET PER SECONDRESULTS 15 ACTIVE-CHANNEL WIDTH (W), in feet Figure 8.—Structural relations between active-channel width and discharge characteristics for sand-bed, silt-banks channels. community of riparian vegetation has on channel banks is virtually the same regardless of channel size, the relative effect on width-discharge relations decreases as mean discharges increase. Quantative techniques for measuring the effects of vegetation have not been developed yet, and therefore vegetation is not considered in the equations of this paper. In general, unregulated stream channels are widened only during erosive discharge and have a tendency to narrow at all other times of discharge (Burkham, 1972; Osterkamp, 1977, 1979a). Relatively stable, narrow channels, therefore, are more likely to occur for streams of steady discharge than for those of highly variable and periodically erosive discharge. Natural examples of the two extremes are the channels of very steady spring effluent and the channels of highly ephemeral streamflow in an arid or semiarid region. Because the discharge characteristics of most partly regulated streams do not differ greatly from many natural streams of discharge with small variability, data from some partly regulated streams are incorporated into this study. Except to provide examples, the relations presented here are not separated into groups based on discharge variability because: (1) additional grouping within most of the channel-type classes (table 1) would result in data sets too small to provide dependable results, (2) the use of discharge characteristics as a basis (independent variable) for estimating other discharge characteristics is a questionable practice, and (3) commonly, little is known of the discharge characteristics when the channel-geometry equations are used in practical manner. The results of computer analyses for sand-bed, sandbanks channels when the data are divided into two groups according to discharge variability are given in table 7. Sand-channel streams are used to illustrate the effect of stream flashiness because sufficient data (96 sets) are available. They represent a wide range of geologic and hydrologic conditions. Results (tables 2, 4) show general instability and large standard errors of estimate, and the channels are easily widened by erosive discharges. The data were separated into two groups, those that have low variability of discharge and those that have highly variable discharge, which are defined as having ratios of the 10-year flood to active-channel width (W), in feet 4 10 100 300 ACTIVE-CHANNEL WIDTH (W), IN METERS Figure 9.—Structural relations between active-channel width and discharge characteristics for sand-bed, sand-banks channels.16 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN ACTIVE-CHANNEL WIDTH (W), IN FEET Figure 10.—Structural relations between active-channel width and discharge characteristics for gravel-bed channels. mean discharge (QJQ) of less than or equal to 60, and more than 60, respectively. Comparisons of the results in table 7 with the corresponding results of tables 2 and 4 show significant differences in both the equations and standard errors of estimate. Relative to the equations of tables 2 and 4, relations for the low-variability streams have larger width exponents and smaller coefficients, indicating slower transport rates of bed-material load, and the high-variability streams have smaller width exponents and larger coefficients, indicating faster transport rates of bed-material sizes. Thus, the equations confirm the expected result that little discharge variability favors relatively narrow channels, whereas increased variability and erosive flood discharges produce wider channels. It is inferred that the width exponents for the low-variability data would be even larger if the somewhat anomalous data from the Sand Hills area, Nebraska, were not disproportional in that group. Probably because of the unusual geologic condi- Figure 11.—Structural relations between active-channel width and discharge characteristics for cobble-bed channels. tions of the Sand Hills, channels there convey very low-variability discharge yet tend to be relatively wide. For this reason, the standard errors of estimate for the low-variability streams (table 7) remain large, being only moderately smaller than those of the sand-bed, sand-banks’ channels in general (tables 2, 4). The highly variable discharge streams, however, appear to yield a representative set of data and show standard errors substantially less (table 7) than those of the entire data set for sand-channel streams (tables 2, 4). Width-discharge and width-gradient-discharge relations no doubt are affected by other variables that are not considered here. Among these complicating variables are land-use practices (for example, the effect of livestock), water salinity (and its potential for flocculation of clay particles), and particularly the elapsed time since the last erosive flood. Suitable methods presently are not available to evaluate quantitatively the effects of these or other potential effects of geometry-discharge relations. DISCHARGE (Q), IN CUBIC FEET PER SECONDRESULTS 17 ACTIVE-CHANNEL WIDTH (W), IN FEET Figure 12.—Width-gradient-discharge relations for mean discharges (Q) and the 25-year floods (Q26) for sand-bed, sandbanks channels using representative values of gradient (G). VARIABILITY AND ERROR ANALYSIS Statistical summaries for the equations given in tables 2, 4, 6, and 7 show large ranges for the standard errors of estimate, correlation coefficients, and levels of significance. Numerous causes or sources of error appear to contribute to the standard-error values; these include: (1) inaccurate or misleading discharge data, (2) inconsistent geometry data resulting from improper site selection or differences in measuring technique between sites, (3) discharge variability and elapsed time since the previous erosive flood, (4) improper collection and analysis techniques for the channel-material samples, (5) grouping of channels by ranges of channel-sediment properties, and (6) other complicating variables, only some of which have been mentioned. Of these, the first three sources of error appear to be the most significant. As previously mentioned, most measurement sites for this study were selected at streamflow-gaging stations that have at least 20 years of continuous discharge records. For this length of record, it is calculated for Kansas streams, as an example, that the standard errors of estimate for accuracy of mean discharge is about 0.10 log unit, or roughly 25 percent (average) (Jordan and Hedman, 1970, p. 16). Thus, a similar part of the standard error for each equation in tables 2, 4, Table 7.-Width-discharge and width-gradient-discharge relations for sand-bed, sand-banks channels of differing discharge variability (Q is mean discharge, in cubic meters per second; Q2 through Q100 are flood discharges, in cubic meters per second, of recurrence intervals 2 through 100 years; W is active-channel width, in meters; and G is channel gradient (non-dimensional)] Discharge variability Equation Percentage Standard reduction of error average SE of esti- from corre-mate, SE sponding (percent) value in table 2 or 4 Low, Q = 0.035W162 71 2 QJQ^eo Q= 0.0044W136G“0-42 65 0 (55 data Q2=0.32W151 94 13 sets) Q2=0.029W118G_o 49 86 15 Q5 = 0.60W1'50 101 23 Q5=0.038W113G_056 91 26 Q,„=0.92W1 47 104 28 Q,„=0.055W1 09G-0'58 94 31 Q25= 1.5W1'43 110 30 Q25 = 0.088W105G~°'58 99 35 Q5„=2.1W1 41 115 31 Q5O=0.12W101G“°-58 105 35 Q100=2.6W140 121 31 Qloo=0.17W099G-0-58 111 35 High, Q=0.047W1 36 59 14 «?,„/ 100-year flood discharge. All discharges are in cubic meters per second] Map No. Station No. Station Name Q Q. Q, Qto <3„ Qso QlOO 1 06018500 Beaverhead River near Twin Bridges, Mont 11.6 30.3 41.9 49.8 60.0 67.6 75.4 2 06025500 Big Hole River near Melrose, Mont 32.5 207 309 374 456 518 578 3 06027200 Jefferson River at Silver Star, Mont 55.9 183 342 383 424 448 468 4 06050000 Hyalite Creek at Hyalite Ranger Station near Bozeman, Mont 1.89 11.6 16.0 18.9 22.5 25.3 28.1 5 06052500 Gallatin River at Logan, Mont 29.6 141 188 217 251 275 299 6 06115200 Missouri River near Landusky, Mont 262 850 1389 1868 2647 3375 4250 7 06120500 Musselshell River at Harlowton, Mont 4.57 30.3 57.8 78.5 106 128 151 8 06123500 Musselshell River near Ryegate, Mont 5.01 38.8 81.3 118 175 225 280 9 06126500 Musselshell River near Roundup, Mont 5.61 50.7 95.8 132 185 229 278 10 06127500 Musselshell River at Musselshell, Mont 5.64 46.5 92.3 132 185 234 278 11 06185500 Missouri River near Culbertson, Mont 297 683 1000 1320 1820 2320 2890 12 06191500 Yellowstone River at Corwin Springs, Mont 88.4 487 620 697 785 844 898 13 06192500 Yellowstone River near Livingston, Mont 107 584 720 802 892 958 1017 14 06197500 Boulder River near Contact, Mont 10.8 105 125 137 150 159 167 15 06200000 Boulder River at Big Timber, Mont 17.6 173 215 239 268 289 309 16 06205000 Stillwater River near Absarokee, Mont 27.6 192 245 277 314 343 368 17 06233000 Little Popo Agie River near Lander, Wyo 2.27 17.5 28.9 37.1 47.9 56.4 64.9 18 06235500 Little Wind River near Riverton, Wyo 17.0 139 217 272 345 402 460 19 06244500 Fivemile Creek above Wyoming Canal, near Pavillion, Wyo .064 2.89 7.65 12.7 21.8 31.0 42.5 20 06258000 Muddy Creek near Shoshoni, Wyo .555 12.1 23.6 33.5 48.6 61.9 76.8 21 06270000 No wood River near Ten Sleep, Wyo 3.14 34.0 59.0 78.5 106 130 155 22 06290500 Little Bighorn River below Pass Creek, near Wyola, Mont 6.03 38.2 58.6 73.4 92.4 107 123 23 06294000 Little Bighorn River near Hardin, Mont 8.81 58.6 102 136 182 220 259 24 06294700 Bighorn River at Bighorn, Mont 112 407 577 683 809 898 983 25 06305500 Goose Creek below Sheridan, Wyo 5.21 46.4 75.4 97.2 127 151 177 26 06308500 Tongue River at Miles City, Mont 12.5 130 219 286 377 448 518 27 06309000 Yellowstone River at Miles City, Mont 326 1544 1952 2184 2439 2612 2768 28 06317000 Powder River at Arvada, Wyo 7.76 214 416 599 898 1176 1506 29 06318500 Clear Creek near Buffalo, Wyo 1.78 19.1 30.0 38.5 50.1 59.8 70.0 30 06323500 Piney Creek at Ucross, Wyo. . 2.48 28.6 45.3 56.9 79.3 99.2 109 31 06326500 Powder River near Locate, Mont 17.6 266 538 776 1020 1220 1420 32 06329200 Burns Creek near Savage, Mont .094 6.83 37.4 88.7 218 385 637 33 06332000 White Earth River at White Earth, N. Dak .816 17.1 39.1 59.0 90.7 118 149 34 06334500 Little Missouri River at Camp Crook, S. Dak 3.82 70.2 132 182 256 317 385 35 06335000 Little Beaver Creek near Marmarth, N. Dak 1.12 96.6 168 221 292 346 402SUPPLEMENTAL INFORMATION 23 Table 8.—Discharge characteristics of selected streams in the Missouri River basin—Continued Map No. Station No. Station Name Q Q, Q, Qio e.. Qto Q100 36 06335500 Little Missouri River at Marmarth, N. Dak 9.63 268 516 711 991 1218 1459 37 06336000 Little Missouri River at Medora, N. Dak 13.4 289 578 810 1144 1416 1705 38 06336500 Beaver Creek at Wibaux, Mont .632 25.5 98.3 193 391 606 898 39 06337000 Little Missouri River near Watford City, N. Dak 17.0 428 793 1074 1462 1770 2093 40 06339500 Knife River near Golden Valley, N. Dak 2.73 90.7 199 289 416 521 629 41 06340000 Spring Creek at Zap, N. Dak. Knife River at Hazen, N. Dak. 1.24 51.0 98.9 135 184 223 261 42 06340500 5.10 139 297 428 623 782 955 43 06341400 Turtle Creek near Turtle Lake, N. Dak .0213 1.39 3.71 5.92 9.43 12.5 16.0 44 06341800 Painted Woods Creek near Wilton, N. Dak .212 8.30 23.4 38.2 62.6 84.4 109 45 06343000 Heart River near South Heart, N. Dak .790 44.5 104 156 234 297 368 46 06345000 Green River near Gladstone, N. Dak 1.01 42.5 100 149 223 283 351 47 06345500 Heart River near Richardton, N. Dak 2.92 105 217 295 392 459 521 48 06347000 Antelope Creek near Carson, N. Dak .456 28.3 80.7 133 219 297 385 49 06348000 Heart River near Lark, N. Dak 6.06 109 276 436 693 922 1183 50 06349000 Heart River near Mandan, N. Dak 7.16 127 336 526 812 1049 1304 51 06349500 Apple Creek near Menoken, N. Dak .960 16.9 47.6 77.6 127 171 221 52 06350000 Cannonball River at Regent, N. Dak 1.26 52.3 148 248 416 569 748 53 06351000 Cannonball River below Bentley, N. Dak 2.47 77.6 228 382 637 872 1142 54 06352000 Cedar Creek near Haynes, N. Dak .731 30.6 96.9 170 300 428 583 55 06354000 Cannonball River at Breien, N. Dak 6.82 141 337 504 742 935 1136 56 06354500 Beaver Creek at Linton, N. Dak 1.15 30.6 81.6 130 208 276 351 57 06355500 North Fork Grand River near White Butte, S. Dak 1.57 38.5 172 363 784 1269 1943 58 0635600 South Fork Grand River at Buffalo, S. Dak .233 18.1 41.3 63.2 98.6 131 168 59 06356500 South Fork Grand River near Cash, S. Dak 1.56 48.4 117 183 295 397 516 60 06357800 Grand River at Little Eagle, S. Dak 6.51 143 258 334 426 488 546 61 06359500 Moreau River near Faith, S. Dak 3.82 104 262 422 619 949 1258 62 06394000 Beaver Creek near Newcastle, Wyo .929 31.5 57.8 80.2 114 144 179 63 06395000 Cheyenne River at Edgemont, S. Dak 2.86 83.8 185 289 476 668 915 64 06402500 Beaver Creek near Buffalo Gap, S. Dak .199 3.40 15.8 38.0 103 204 385 65 06406000 Battle Creek at Hermosa, S. Dak .270 9.06 29.7 52.1 90.9 127 169 66 06409000 Castle Creek above Deerfield Reservoir, near Hill City, S. Dak .286 1.78 4.11 6.43 10.6 14.7 19.8 67 06410500 Rapid Creek above Pactola Reservoir, at Silver City, S. Dak 1.14 6.77 15.8 26.1 47.0 69.8 102 68 06414000 Rapid Creek at Rapid City, S. Dak 1.76 11.2 33.4 74.2 210 457 993 69 06421500 Rapid Creek near Farmingdale, S. Dak 1.56 18.5 40.8 64.4 108 154 213 70 06430500 Redwater Creek at Wyo.- S. Dak.State line 1.04 8.35 23.1 39.1 68.5 98.7 137 71 06431500 Spearfish Creek at Spearfish, S. Dak 1.45 7.84 20.2 35.4 67.7 106 16224 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Table 8.— Discharge characteristics of selected streams in the Missouri River basin—Continued Map No. Station jsjo Station Name Q ft ft ft. ft. ft. ft» 72 06433000 Redwater River above Belle Fourche, S. Dak.. . 3.82 23.4 55.5 87.8 144 198 265 73 06437000 Belle Fourche River near Sturgis, S. Dak 7.73 105 214 307 450 573 712 74 06444000 White River at Crawford, Nebr .572 10.2 23.8 38.5 66.8 97.2 138 75 06447000 White River near Kadoka, S. Dak 7.87 274 436 569 768 941 1130 76 06447500 Little White River near Martin, S. Dak .541 5.15 12.1 20.0 35.7 53.2 77.3 77 06448000 Lake Creek above Refuge, near Tuthill, S. Dak .549 2.26 3.03 3.60 4.36 5.01 5.69 78 06449100 Little White River near Vetal, S. Dak 1.48 9.15 17.4 25.0 37.7 50.1 65.7 79 06449500 Little White River near Rosebud, S. Dak 3.12 20.9 45.6 72.2 123 177 250 80 06450500 Little White River below White River, S. Dak 3.57 48.2 109 179 323 488 724 81 06453500 Ponca Creek at Anoka, Nebr. 1.40 48.1 94.9 140 218 295 391 82 06453600 Ponca Creek at Verdel, Nebr. 2.19 53.2 122 197 337 487 688 83 06454000 Niobrara River at Wyo.-Nebr. State line .123 2.14 7.42 15.4 35.7 63.7 110 84 06454100 Niobrara River at Agate, Nebr .413 1.81 2.97 3.96 5.52 6.91 8.58 85 06454500 Niobrara River above Box Butte Reservoir, Nebr .872 6.03 14.0 23.1 41.1 60.9 88.4 86 06461000 Minnechaduza Creek at Valentine, Nebr .963 6.06 10.2 14.0 20.0 25.7 32.3 87 06462500 Plum Creek at Meadville, Nebr 3.03 11.7 20.4 28.3 41.4 53.5 68.3 88 06464500 Keya Paha River at Wewela, S. Dak 1.93 19.4 45.0 74.8 134 201 295 89 06464900 Keya Paha River near Naper, Nebr 3.77 58.6 111 161 244 323 422 90 06466500 Brazile Creek near Niobrara, Nebr 2.47 134 433 759 1340 1898 2561 91 06467600 James River near Manfred, N. Dak .0818 2.92 8.78 14.9 25.1 34.6 45.6 92 06469500 Pipestem Creek near Pingree, N. Dak .552 11.8 43.8 77.7 133 179 228 93 06470000 James River at Jamestown, N. Dak 1.65 17.0 42.4 65.2 100 129 160 94 06470500 James River at La Moure, N. Dak 2.53 22.1 57.9 92.7 150 201 260 95 06471500 Elm River at Westport, S. Dak 1.31 21.0 80.7 153 292 428 600 96 06473000 James River at Ashton, S. Dak 4.39 10.9 28.5 45.6 73.3 98.1 128 97 06477000 James River near Forestburg, S. Dak 7.87 32.1 94.8 172 331 512 764 98 06477500 Firesteel Creek near Mount Vernon, S. Dak .654 11.3 42.2 83.0 168 265 397 99 06478500 James River near Scotland, S. Dak 10.6 56.1 126 192 297 391 501 100 06480000 Big Sioux River near Brookings, S. Dak 4.33 60.9 172 282 462 623 804 101 06481000 Big Sioux River near Dell Rapids, S. Dak 7.16 87.5 234 377 603 804 1031 102 06481500 Skunk Creek at Sioux Falls, S. Dak 1.31 41.1 118 198 331 456 600 103 06483500 Rock River near Rock Valley, Iowa 8.50 166 456 736 1190 1589 2040 104 06485500 Big Sioux River at Akron, Iowa 23.8 274 615 904 1323 1668 2034 105 06486000 Missouri River at Sioux City, Iowa 904 963 1643 1870 2125 2380 2550 106 06600100 Floyd River at Alton, Iowa . . . 1.33 48.4 137 299 388 538 717 107 06600300 West Branch Floyd River near Struble, Iowa .864 51.8 124 188 283 365 453 108 06600500 Floyd River at James, Iowa . 5.07 97.1 224 348 561 765 1011 109 06601000 Omaha Creek at Homer, SUPPLEMENTAL INFORMATION 25 Table 8.—Discharge characteristics of selected streams in the Missouri River basin—Continued Station Name Q Q, Qs Qio Q*o Q.™ Nebr 1.02 166 227 314 436 533 635 110 06606600 Little Sioux River at Correctionville, Iowa 19.9 193 360 479 631 748 861 111 06607000 Odebolt Creek near Arthur, Iowa .445 29.2 57.2 79.0 109 132 156 112 06607200 Maple River at Mapleton, Iowa 6.60 182 320 416 538 629 719 113 06608000 Tekamah Creek at Tekamah, Nebr .188 52.1 113 163 237 297 362 114 06608500 Soldier River at Pisgah, Iowa 3.57 258 419 530 666 768 869 115 06609500 Boyer River at Logan, Iowa . . 8.86 354 510 603 711 785 853 116 06610000 Missouri River at Omaha, Nebr 830 1811 2341 2729 3265 3696 4157 117 06628900 Pass Creek near Elk Mountain, Wyo 1.16 13.4 21.2 26.9 34.7 41.0 47.5 118 06632400 Rock Creek above King Canyon Canal near Arlington, Wyo 2.33 41.9 60.9 73.6 90.1 102 114 119 06639000 Sweetwater River near Alcova, Wyo 3.57 19.4 31.4 40.2 51.3 59.8 68.5 120 06649000 La Prele Creek near Douglas, Wyo 1.14 16.1 36.9 58.5 97.6 138 189 121 06670500 Laramie River near Fort Laramie, Wyo 4.08 24.5 54.6 81.9 125 162 205 122 06671000 Rawhide Creek near Lingle, Wyo .609 5.78 14.5 24.0 42.1 61.3 88.4 123 06677500 Horse Creek near Lyman, Nebr 1.87 19.1 36.3 52.1 78.7 104 135 124 06678000 Sheep Creek near Morrill, Nebr 1.55 5.49 7.65 9.12 11.1 12.5 13.9 125 06679000 Dry Spottedtail Creek at Mitchell, Nebr .963 9.72 20.3 31.4 51.5 72.8 100 126 06680000 Tub Springs near Scottsbluff, Nebr 1.05 14.4 23.8 32.0 48.7 66.6 90.4 127 06681000 Winters Creek near Scottsbluff, Nebr 1.51 10.9 17.8 23.0 30.0 35.4 41.1 128 06684000 Red Willow Creek near Bayard, Nebr 2.46 22.7 38.8 50.7 66.8 79.3 92.6 129 06685000 Pumpkin Creek near Bridgeport, Nebr .869 4.67 12.1 20.8 38.5 58.6 86.9 130 06687000 Blue Creek near Lewellen, Nebr 1.97 6.20 9.46 12.1 16.1 19.6 23.5 131 06692000 Birdwood Creek near Hershey, Nebr 4.33 11.7 17.1 21.3 27.5 32.9 38.5 132 06712000 Cherry Creek near Franktown, Colo .251 21.7 68.5 124 232 348 498 133 06776500 Dismal River at Dunning, Nebr 9.09 14.6 17.0 18.6 20.6 22.1 23.7 134 06779000 Middle Loup River at Arcadia, Nebr 18.2 79.3 126 166 227 283 348 135 06782500 South Loup River at Ravenna, Nebr. 5.44 102 230 374 651 955 1368 136 06783500 Mud Creek near Sweetwater, Nebr 1.17 31.7 65.7 92.1 128 156 185 137 06784000 South Loup River at St. Michael, Nebr 6.88 96.9 230 382 688 1031 1510 138 06785000 Middle Loup River at St. Paul, Nebr 34.0 235 402 555 799 1028 1310 139 06786000 North Loup River at Taylor, Nebr 13.0 39.3 52.1 61.2 74.2 84.4 95.4 140 06787500 Calamus River near Burwell, Nebr 8.47 16.9 22.8 27.2 33.4 38.5 43.9 141 06788500 North Loup River at Ord, Nebr 24.4 75.1 115 147 196 238 286 142 06790500 North Loup River near St. Paul, Nebr 27.4 181 340 490 751 1008 1328 143 06791500 Cedar River near Spalding, Nebr 4.33 16.4 30.0 42.5 64.2 84.7 110 144 06792000 Cedar River near Fullerton, Nebr 6.82 83.8 179 279 467 666 92626 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Map No. Station No. Station Name Q 0. e. Qio Qn QlOO 145 06794000 Beaver Creek at Genoa, Nebr. 3.57 62.3 142 231 402 592 850 146 06795500 Shell Creek near Columbus, Nebr 1.20 43.3 84.3 116 161 196 232 147 06797500 Elkhorn River at Ewing, Nebr 4.90 32.3 84.1 148 283 442 674 148 06798500 Elkhorn River at Neligh, Nebr 7.99 45.6 103 193 357 544 813 149 06799000 Elkhorn River near Norfolk, Nebr. 14.3 108 238 377 643 929 1314 150 06799100 North Fork Elkhorn River near Pierce, Nebr 2.51 49.6 119 182 278 360 450 151 06799500 Logan Creek near Uehling, Nebr 5.21 166 329 459 640 782 935 152 06800000 Maple Creek near Nickerson, Nebr 1.71 70.0 143 201 283 351 419 153 06803000 Salt Creek at Roca, Nebr 1.20 75.3 194 300 459 586 725 154 06803555 Salt Creek at Greenwood, Nebr 7.65 297 762 1176 1787 2292 2827 155 06804000 Wahoo Creek at Ithaca, Nebr 2.17 111 233 338 456 555 654 156 06806500 Weeping Water Creek at Union, Nebr 2.31 99.4 227 331 482 598 719 157 06807000 Missouri River at Nebraska City, Nebr 990 2554 3377 3970 4776 5418 6097 158 06808500 West Nishnabotna River at Randolph, Iowa 15.6 484 674 787 921 1011 1096 159 06809500 East Nishnabotna River at Red Oak, Iowa 10.6 275 484 637 836 989 1142 160 06813000 Tarkio River at Fairfax, Mo.. . 5.24 189 334 436 558 643 728 161 06814000 Turkey Creek near Seneca, Kans 3.48 136 295 431 637 819 1014 162 06817000 Nodaway River at Clarinda, Iowa 9.09 278 470 598 753 864 969 163 06817500 Nodaway River near Burlington Junction, Mo. .. 14.9 382 685 895 1153 1337 1516 164 06818000 Missouri River at St. Joseph, Mo 1100 2790 5635 6790 8578 9447 10624 165 06819190 East Fork One Hundred and Two River near Bedford, Iowa 1.43 57.7 163 206 265 299 338 166 06819500 One Hundred And Two River at Maryville, Mo 5.83 209 334 422 535 620 705 167 06820500 Platte River near Agency, Mo 24.5 409 688 904 1195 1428 1672 168 06821500 Arikaree River at Haigler, Nebr .697 69.4 186 331 649 1028 1589 169 06823000 North Fork Republican River at Colo.-Nebr. State line . . 1.37 8.36 16.8 25.4 40.8 56.7 77.3 170 06823500 Buffalo Creek near Haigler, Nebr .221 .934 1.56 2.15 3.06 3.94 4.96 171 06824000 Rock Creek at Parks, Nebr. .402 1.25 2.29 3.31 5.01 6.66 8.72 172 06824500 Republican River at Benkelman, Nebr 2.56 40.5 106 186 357 558 853 173 06825500 Landsman Creek near Hale, Colo .108 42.2 96.3 148 235 317 414 174 06827500 South Fork Republican River near Benkelman, Nebr 1.54 80.2 201 297 425 518 609 175 06828500 Republican River at Stratton, Nebr 3.91 104 235 357 550 725 926 176 06831500 Frenchman Creek near Imperial, Nebr 1.93 7.59 16.3 25.5 42.8 61.2 85.5 177 06835000 Stinking Water Creek near Palisade, Nebr 1.21 10.1 22.3 35.7 60.9 88.4 125 178 06836000 Blackwood Creek near Culbertson, Nebr .188 12.1 28.9 48.2 86.7 130 191 179 06838000 Red Willow Creek near Red Willow, Nebr .892 11.5 23.2 34.8 55.5 76.2 102 180 06841000 Medicine Creek above Harry Strunk Lake, Nebr 1.94 59.8 145 245 448 677 1000 181 06844500 Republican River near Orleans, Nebr 9.29 110 195 263 360 442 530 182 06845000 Sappa Creek near Oberlin, SUPPLEMENTAL INFORMATION 27 Table 8.—Discharge characteristics of selected streams in the Missouri River basin—Continued Map Station Station Name Q Q, <3. 0,. Qn <3.. Q.oo No. No. 183 06845200 Sappa Creek near Beaver City, Nebr 1.08 39.9 83.6 122 180 231 289 184 06846500 Beaver Creek at Cedar Bluffs, Kans .632 17.0 40.2 63.5 103 142 187 185 06847000 Beaver Creek near Beaver City, Nebr .770 16.1 41.6 66.3 111 153 203 186 06847500 Sappa Creek near Stamford, Nebr 1.93 37.7 89.5 139 221 297 385 187 06848500 Prairie Dog Creek near Woodruff, Kans 1.17 66.6 143 213 326 425 544 188 06851000 Center Creek at Franklin, Nebr .200 7.79 30.3 60.3 124 195 292 189 06853500 Republican River near Hardy, Nebr 17.7 130 235 340 538 736 991 190 06855800 Buffalo Creek near Jamestown, Kans 2.28 66.3 164 261 425 578 759 191 06855900 Wolf Creek near Concordia, Kans .357 30.3 57.5 79.3 111 137 166 192 06856000 Republican River at Concordia, Kans 22.0 224 397 538 765 991 1246 193 06859500 Ladder Creek below Chalk Creek near Scott City, Kans .241 21.0 75.1 145 289 450 671 194 06860000 Smoky Hill River at Elkader, Kans .974 55.0 203 397 802 1250 1870 195 06861000 Smoky Hill River near Arnold, Kans 2.04 144 368 558 821 1023 1227 196 06862700 Smoky Hill River near Schoechen, Kans .977 58.1 170 287 490 682 911 197 06863500 Big Creek near Hays, Kans. . . 1.19 51.8 102 150 227 300 391 198 06864050 Smoky Hill River near Bunker Hill, Kans 5.81 193 397 538 765 963 1133 199 06864500 Smoky Hill River at Ellsworth, Kans 7.42 238 482 623 765 906 1020 200 06866500 Smoky Hill River near Mentor, Kans 12.4 130 238 340 482 562 821 201 06867000 Saline River near Russell, Kans 3.37 107 249 380 578 753 952 202 06867500 Paradise Creek near Paradise, Kans .549 26.0 88.9 167 326 499 725 203 06869500 Saline River at Tescott, Kans 6.26 88.7 197 297 459 606 776 204 06870200 Smoky Hill River at New Cambria, Kans 18.2 167 410 722 1520 2630 4390 205 06871000 North Fork Solomon River at Glade, Kans .957 65.1 185 317 561 810 1125 206 06871500 Bow Creek near Stockton, Kans .436 38.2 93.5 148 240 329 433 207 06872500 North Fork Solomon River at Portis, Kans 4.11 113 255 368 567 736 906 208 06873000 South Fork Solomon River above Webster Reservoir, Kans 2.04 126 354 598 1031 1456 1977 209 06874000 South Fork Solomon River at Osborne, Kans 3.80 51.0 155 272 482 680 906 210 06876700 Salt Creek near Ada, Kans.. . . 1.58 35.7 127 235 439 646 901 211 06876900 Solomon River at Niles, Kans 15.9 192 397 589 912 1218 1586 212 06877600 Smoky Hill River at 213 Enterprise, Kans 45.7 281 544 790 1200 1600 2080 06878000 Chapman Creek near Chapman, Kans 2.40 107 204 281 394 487 586 214 06878500 Lyon Creek near Woodbine, Kans 3.06 183 510 853 1450 2030 2720 215 06879900 Big Blue River at Surprise, Nebr .830 48.1 123 191 295 380 473 216 06880000 Lincoln Creek near Seward, Nebr 1.28 34.6 75.1 108 154 191 229 217 06880500 Big Blue River at Seward, Nebr 3.17 81.3 194 291 433 550 674 218 06880800 West Fork Big Blue River near Dorchester, Nebr 5.01 89.2 162 214 281 331 38228 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Table 8.—Discharge characteristics of selected streams in the Missouri River basin—Continued Map No. Station No. Station Name Q Q, e. Q„ Q„ QlOO 219 06881000 Big Blue River near Crete, Nebr 9.94 195 408 578 813 1000 1187 220 06883575 Little Blue River near Alexandria, Nebr 6.74 182 343 459 612 728 841 221 06884200 Mill Creek at Washington, Kans 2.82 132 258 363 516 643 782 222 06884400 Little Blue River near Barnes, Kans 18.6 346 660 923 1314 1652 2028 223 06885500 Black Vermillion River near Frankfort, Kans 3.88 210 487 739 1142 1496 1898 224 06887500 Kansas River at Wamego, Kans 138 1080 2080 2920 4109 5300 6520 225 06888000 Vermillion Creek near Wamego, Kans 2.57 141 297 425 612 768 935 226 06889000 Kansas River at Topeka, Kans 155 1312 2465 3399 4787 5977 7252 227 06891000 Kansas River at Lecompton, Kans 200 1561 2889 3881 5326 6459 7677 228 06891500 Wakarusa River near Lawrence, Kans 5.61 184 360 496 688 841 1002 229 06892000 Stranger Creek near Tonganoxie, Kans 6.17 164 312 431 598 734 875 230 06892350 Kansas River at DeSoto, Kans 196 1420 2830 3680 4530 5670 6800 231 06894000 Little Blue River near Lake City, Mo 3.82 113 180 226 286 329 371 232 06895500 Missouri River at Waverly, Mo 1370 3200 6955 8389 10458 11484 12773 233 06897500 Grand River near Gallatin, Mo 32.3 700 1105 1380 1720 1969 2212 234 06898100 Thompson River at Mount Moriah, Mo 15.6 419 623 753 915 1028 1139 235 06898400 Weldon River near Leon, Iowa 2.07 109 360 471 623 724 833 236 06899500 Thompson River at Trenton, Mo 26.3 640 1074 1371 1739 2011 2272 237 06899700 Shoal Creek near Braymer, Mo 7.39 199 300 368 450 507 567 238 06902000 Grand River near Sumner, Mo 108 1513 2340 2889 3626 4136 4674 239 06902200 West Yellow Creek near Brookfield, Mo 3.09 87.8 144 184 234 271 309 240 06905500 Chariton River near Prairie Hill. Mo 32.4 394 561 663 785 870 949 241 06907700 Blackwater River at Valley City, Mo 12.8 683 1263 1702 2297 2759 3229 242 06908000 Blackwater River near Blue Lick, Mo 20.5 283 499 666 901 1096 1306 243 06909000 Missouri River at Booneville, Mo 1640 2148 8167 10521 12748 16477 19328 244 06910500 Moreau River near Jefferson City, Mo 10.3 385 521 603 697 762 824 245 06911900 Dragoon Creek near Burlingame, Kans 1.95 153 245 309 394 456 521 246 06913500 Marais Des Cygnes River near Ottawa, Kans 18.4 314 711 1110 1810 2501 3371 247 06914000 Pottawatomie Creek near Garnett, Kans 6.54 303 561 779 1105 1388 1705 248 06925200 Starks Creek at Preston, Mo. . .101 21.9 34.3 42.8 53.0 60.6 68.0 249 06930000 Big Piney River near Big Piney, Mo 15.5 342 581 751 969 1133 1300 250 06931500 Little Beaver Creek near Rolla, Mo .154 38.8 66.0 85.5 111 131 151 251 06932000 Little Piney Creek at Newburg, Mo 4.30 177 357 504 722 906 1108 252 06934500 Missouri River at Hermann, Mo 2260 4941 111716 14452 18413 20570 23193SUPPLEMENTAL INFORMATION 29 Table 9.—Geometry measurements and sediment characteristics of selected streams in the Missouri River basin [ACW, active-channel width, in meters; DEP, average depth, in meters, BUS, silt-clay content of the bed, in percent, dt0, median particle size of the bed, in millimeters; BSH, bank silt-clay content, in percent (high); BSL, low bank silt-clay content, in percent; GRA, channel gradient, dimensionless] Map No. Station No. Station Name ACW DEP BDS dio BSH BSL GRA 1 06018500 Beaverhead River near Twin Bridges, Mont 16.2 1.07 2 6.0 51 51 0.0016 2 06025500 Big Hole River near Melrose, Mont 51.8 1.73 1 150 50 50 .0028 3 06027200 Jefferson River at Silver Star, Mont 64.0 1.68 1 38 50 50 .00080 4 06050000 Hyalite Creek at Hyalite Ranger Station near Bozeman, Mont 10.7 1.07 1 250 70 70 .028 5 06052500 Gallatin River at Logan, Mont 44.2 1.46 1 25 5 5 .0018 6 06115200 Missouri River near Landusky, Mont 190 6.33 15 .18 40 40 .00049 7 06120500 Musselshell River at Harlowton, Mont 18.3 .74 1 130 40 19 .0029 8 06123500 Musselshell River near Ryegate, Mont 22.9 .64 1 14 33 25 .0020 9 06126500 Musselshell River near Roundup, Mont 20.4 .98 1 10 34 34 .0018 10 06127500 Musselshell River at Musselshell, Mont 30.5 .91 12 8.6 29 13 .00097 11 06185500 Missouri River near Culbertson, Mont 320 10. 7 10 .19 55 55 .00016 12 06191500 Yellowstone River at Corwin Springs, Mont 82.3 3.05 1 130 70 70 .0023 13 06192500 Yellowstone River near Livingston, Mont 88.4 3.66 1 100 60 60 .0027 14 06197500 Boulder River near Contact, Mont 31.4 .61 1 150 36 30 .0018 15 06200000 Boulder River at big Timber, Mont 36.6 1.46 1 130 50 50 .0110 16 06205000 Stillwater River near Absarokee, Mont 33.5 1.37 1 230 60 60 .0062 17 06233000 Little Popo Agie River near Lander, Wyo 14.0 .88 1 51 30 30 .0054 18 06235500 Little Wind River near Riverton, Wyo 46.6 1.37 1 120 66 44 .00096 19 06244500 Fivemile Creek above Wyoming Canal, near Pavillion, Wyo 2.99 .27 1 11 35 17 .0052 20 06258000 Muddy Creek near Shoshoni, Wyo 6.86 .74 1 6.8 33 33 .0039 21 06270000 No wood River near Ten Sleep, Wyo 11.3 1.98 43 .074 51 51 .0016 22 06290500 Little Bighorn River below Pass Creek, near Wyola, Mont 22.6 1.74 1 38 40 40 .0028 23 06294000 Little Bighorn River near Hardin, Mont 42.7 1.42 1 19 50 50 .0020 24 06294700 Bighorn River at Bighorn, Mont 82.3 3.2 1 10 77 22 .00045 25 06305500 Goose Creek below Sheridan, Wyo 22.6 1.28 1 25 60 60 .0027 26 06308500 Tongue River at Miles City Mont 47.2 1.10 2 4.2 47 47 .00066 27 06309000 Yellowstone River at Miles City, Mont 219 7.30 5 10 33 33 .00068 28 06317000 Powder River at Arvada, Wyo 45.7 1.92 12 .16 54 25 .00087 29 06318500 Clear Creek near Buffalo, Wyo 10.7 .54 1 20 31 31 .024 30 06323500 Piney Creek at Ucross, Wyo. . 16.3 .62 1 50 34 34 .0043 31 06326500 Powder River near Locate, Mont 62.5 1.79 3 .35 30 30 .00095 32 06329200 Burns Creek near Savage, Mont 3.32 .63 13 8.3 38 14 .0032 33 06332000 White Earth River at White Earth, N. Dak 5.18 .88 4 3.0 41 34 .00069 34 06334500 Little Missouri River at Camp Crook, S. Dak 17.7 .68 3 1.4 57 25 .0008030 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Table 9.—Geometry measurements and sediment characteristics of selected streams in the Missouri River basin—Continued Map No. Station No. Station Name ACW DEP BDS dt o BSH BSL GRA 35 06335000 Little Beaver Creek near Marmarth, N. Dak 9.30 1.02 3 12 28 9 .00090 36 06335500 Little Missouri River at Marmarth, N. Dak 57.9 1.28 3 .62 32 32 .00071 37 06336000 Little Missouri River at Medora, N. Dak 61.0 1.43 1 .60 29 25 .00063 38 06336500 Beaver Creek at Wibaux, Mont .6.40 .65 7 4.8 12 11 .0018 39 06337000 Little Missouri River near Watford City, N. Dak 70.1 1.73 3 .17 65 65 .00078 40 06339500 Knife River near Golden Valley, N. Dak 13.7 1.22 2 .50 41 17 .00040 41 06340000 Spring Creek at Zap, N. Dak. 6.71 .79 11 .26 33 29 .00090 42 06340500 Knife River at Hazen, N. Dak. 16.2 1.36 2 .46 32 26 .00050 43 06341400 Turtle Creek near Turtle Lake, N. Dak .762 .049 76 .02 95 58 .0011 44 06341800 Painted Woods Creek near Wilton, N. Dak 3.05 .19 1 100 27 16 .0014 45 06343000 Heart River near South Heart, N. Dak 2.59 .58 12 .47 55 39 .00050 46 06345000 Green River near Gladstone, N. Dak 6.10 .38 1 15 24 23 .0010 47 06345500 Heart River near Richardton, N. Dak 10.4 .90 1 50 40 25 .00056 48 06347000 Antelope Creek near Carson, N. Dak 5.79 1.28 3 5.6 46 40 .0014 49 06348000 Heart River near Lark, N. Dak 29.0 1.09 1 .42 41 34 .00093 50 06349000 Heart River near Mandan, N. Dak 30.5 1.38 5 .22 40 33 .00045 51 06349500 Apple Creek near Menoken, N. Dak 6.40 .79 23 .18 42 26 .00028 52 06350000 Cannonball River at Regent, N. Dak 6.40 .50 15 .40 48 24 .00054 53 06351000 Cannonball River below Bentley, N. Dak 14.9 1.40 5 .29 22 22 .00046 54 06352000 Cedar Creek near Haynes, N. Dak 7.32 .82 5 1.4 49 46 .0014 55 06354000 Cannonball River at Breien, N. Dak 30.5 1.58 11 .14 42 36 .00056 56 06354500 Beaver Creek at Linton, N. Dak 8.53 .79 5 1.5 78 59 .0016 57 06355500 North Fork Grand River near White Butte, S. Dak 10.1 .85 1 8.1 8 8 .0010 58 0635600 South Fork Grand River at Buffalo, S. Dak 5.18 .87 9 .51 16 16 .0014 59 06356500 South Fork Grand River near Cash, S. Dak 7.92 .70 20 1.7 41 41 .0012 60 06357800 Grand River at Little Eagle, S. Dak 42.7 .38 4 .24 18 2 .00046 61 06359500 Moreau River near Faith, S. Dak 18.6 .69 5 .35 27 18 .00043 62 06394000 Beaver Creek near Newcastle, Wyo 7.62 1.09 10 25 68 64 .00066 63 06395000 Cheyenne River at Edgemont, S. Dak 21.3 .48 1 .65 28 24 .0014 64 06402500 Beaver Creek near Buffalo Gap, S. Dak 3.20 .46 6 17 55 47 .0054 65 06406000 Battle Creek at Hermosa, S. Dak 3.51 .22 1 180 10 1 .0022 66 06409000 Castle Creek above Deerfield Reservoir, near Hill City, S. Dak 3.66 .40 5 1.8 61 57 .0082 67 06410500 Rapid Creek above Pactola Reservoir, at Silver City, S. Dak 7.92 .37 1 100 73 66 .0052 68 06414000 Rapid Creek at Rapid City, S. Dak 10.7 .54 2 130 53 28 .0072 69 06421500 Rapid Creek near Farmingdale, S. Dak 7.92 .44 1 60 50 50 .0031 70 06430500 Red water Creek at Wyo.— S. Dak. State line 6.40 .92 8 3.4 44 39 .0022Map No. 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 SUPPLEMENTAL INFORMATION 31 Table 9.—Geometry measurements and sediment characteristics of selected streams in the Missouri River basin—Continued Station Station Name ACW DEP BDS d„ o BSH BSL GRA 06431500 Spearfish Creek at Spearfish, S. Dak 10.4 .44 i 110 5 5 .014 06433000 Redwater River above Belle Fourche, S. Dak 13.4 .53 i 40 64 53 .0029 06437000 Belle Fourche River near Sturgis, S. Dak 25.9 .55 i 50 70 58 .0011 06444000 White River at Crawford, Nebr 4.57 .84 3 .28 70 44 .0043 06447000 White River near Kadoka, S. Dak 47.2 .56 9 .32 81 81 .00093 06447500 Little White River near Martin, S. Dak 4.88 .61 11 .21 69 63 .0018 06448000 Lake Creek above Refuge, near Tuthill, S. Dak 3.66 .38 1 .30 24 10 .0017 06449100 Little White River near Vetal, S. Dak 11.6 .52 1 .31 50 22 .0013 06449500 Little White River near Rosebud, S. Dak 15.2 .73 1 .28 36 23 .0021 06450500 Little White River below White River, S. Dak 16.8 .24 1 .44 66 52 .0010 06453500 Ponca Creek at Anoka, Nebr. 13.7 .63 1 .58 43 17 .0018 06453600 Ponca Creek at Verdel, Nebr. . 21.6 .68 1 .51 42 40 .0014 06454000 Niobrara River at Wyo.-Nebr. State line 3.66 .66 17 .16 31 28 .0055 06454100 Niobrara River at Agate, Nebr 4.57 .70 9 .25 27 27 .0024 06454500 Niobrara River above Box Butte Reservoir, Nebr 5.79 .60 1 .35 41 40 .0013 06461000 Minnechaduza Creek at Valentine, Nebr 10.7 .70 18 .25 22 13 .0038 06462500 Plum Creek at Meadville, Nebr 25.3 1.22 4 .31 39 36 .0018 06464500 Keya Paha River at Wewela, S. Dak 15.8 .79 1 .33 35 32 .0012 06464900 Keya Paha River near Naper, Nebr 35.7 .89 1 .29 36 24 .0012 06466500 Brazile Creek near Niobrara, Nebr 36.3 1.06 1 .41 49 25 .0015 06467600 James River near Manfred, N. Dak 1.83 .20 40 100 30 24 .00047 06469500 Pipestem Creek near Pingree, N. Dak 3.96 .36 1 2.9 39 32 .00042 06470000 James River at Jamestown, N. Dak 12.5 1.03 5 1.8 28 28 .00044 06470500 James River at La Moure, N. Dak 21.3 1.52 3 8.0 48 48 .000094 06471500 Elm River at Westport, S. Dak 10.7 .29 1 2.1 5 4 .00035 06473000 James River at Ashton, S. Dak 18.3 .53 55 .059 61 40 .000072 06477000 James River near Forestburg, S. Dak 31.1 1.58 5 .26 57 16 .000060 06477500 Firesteel Creek near Mount Vernon, S. Dak 8.53 .95 2 .99 32 21 .00060 06478500 James River near Scotland, S. Dak 33.5 1.92 47 .055 39 39 .000082 06480000 Big Sioux River near Brookings, S. Dak 22.0 1.27 5 1.6 54 10 .00028 06481000 Big Sioux River near Dell Rapids, S. Dak 22.9 1.86 1 .40 82 62 .00058 06481500 Skunk Creek at Sioux Falls, S. Dak 14.0 1.52 5 .95 22 22 .00069 06483500 Rock River near Rock Valley, Iowa 34.4 1.52 1 .89 38 14 .00049 06485500 Big Sioux River at Akron, Iowa 54.9 2.70 31 .17 63 48 .00025 06486000 Missouri River at Sioux City, Iowa 350 17 1 .34 60 60 .00021 06600100 Floyd River at Alton, Iowa . . . 20.1 .52 19 .27 57 47 .00066 06600300 West Branch Floyd River near Struble, Iowa 9.75 .50 6 .44 58 37 .0012 06600500 Floyd River at James, Iowa . . 24.7 1.10 3 .52 86 67 .0003232 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Table 9.—Geometry measurements and sediment characteristics of selected streams in the Missouri River basin—Continued Map No. Station No. Station Name ACW DEP BDS dt0 BSH BSL GRA 109 06601000 Omaha Creek at Homer, Nebr 8.53 1.01 49 .067 82 70 .0012 no 06606600 Little Sioux River at Correctionville, Iowa 33.8 2.44 20 .18 75 44 .00023 in 06607000 Odebolt Creek near Arthur, Iowa 7.32 .35 32 .29 77 60 .0014 112 06607200 Maple River at Mapleton, Iowa 35.0 1.01 5 .35 79 55 .00083 113 06608000 Tekamah Creek at Tekamah, Nebr 5.73 .51 24 .68 79 75 .0012 114 06608500 Soldier River at Pisgah, Iowa . 29.3 1.46 2 .37 82 76 .00074 115 06609500 Boyer River at Logan, Iowa . . 32.9 2.29 1 .42 90 86 .00058 116 06610000 Missouri River at Omaha, Nebr 290 11.6 1 .18 65 65 .00016 117 06628900 Pass Creek near Elk Mountain, Wyo 8.69 .98 1 150 23 20 .0092 118 06632400 Rock Creek above King Canyon Canal near Arlington, Wyo 11.9 .79 1 230 50 50 .017 119 06639000 Sweetwater River near Alcova, Wyo 24.4 .80 1 1.7 33 25 .0010 120 06649000 La Prele Creek near Douglas, Wyo 9.30 .53 1 180 60 60 .0030 121 06670500 Laramie River near Fort Laramie, Wyo 19.2 1.02 10 .41 28 14 .0018 122 06671000 Rawhide Creek near Lingle, Wyo 3.93 .82 3 .17 50 49 .0026 123 06677500 Horse Creek near Lyman, Nebr 17.1 1.01 7 .11 45 39 .0017 124 06678000 Sheep Creek near Morrill, Nebr 5.64 .92 1 .25 43 24 .00079 125 06679000 Dry Spottedtail Creek at Mitchell, Nebr 7.01 .64 1 .32 42 37 .0043 126 06680000 Tub Springs near Scottsbluff, Nebr 5.94 .65 3 6.6 50 29 .0041 127 06681000 Winters Creek near Scottsbluff, Nebr 5.33 .86 1 9.2 42 23 .0015 128 06684000 Red Willow Creek near Bayard, Nebr 14.0 .59 1 7.3 60 51 .00091 129 06685000 Pumpkin Creek near Bridgeport, Nebr 5.49 .24 10 .16 44 17 .0013 130 06687000 Blue Creek near Lewellen, Nebr 11.7 .57 1 .38 46 40 .0039 131 06692000 Birdwood Creek near Hershey, Nebr 15.2 .80 1 .29 42 28 .0024 132 06712000 Cherry Creek near Franktown, Colo 3.96 .22 8 1.0 44 44 .025 133 06776500 Dismal River at Dunning, Nebr 26.2 .91 1 .26 61 50 .0010 134 06779000 Middle Loup River at Arcadia, Nebr 62.5 1.22 1 .20 53 39 .0015 135 06782500 South Loup River at Ravenna, Nebr 38.4 1.25 1 .19 54 42 .0010 136 06783500 Mud Creek near Sweetwater, Nebr 10.4 1.52 38 .16 86 61 .00051 137 06784000 South Loup River at St. Michael,Nebr 45.1 1.19 1 .18 76 67 .00086 138 06785000 Middle Loup River at St. Paul, Nebr 134 1.07 1 .32 58 51 .0010 139 06786000 North Loup River at Taylor, Nebr 47.2 1.19 1 .27 46 45 .0013 140 06787500 Calamus River near Burwell, Nebr 70.7 .25 1 .28 38 24 .0010 141 06788500 North Loup River at Ord, Nebr 75.6 .98 1 .38 63 36 .0013 142 06790500 North Loup River near St. Paul, Nebr-. 85.3 1.52 1 .27 70 43 .0011 143 06791500 Cedar River near Spalding, Nebr 24.7 .26 1 .27 21 15 .00083 144 06792000 Cedar River near Fullerton, Nebr 31.1 1.37 2 .26 63 46 .00085SUPPLEMENTAL INFORMATION 33 Table 9.—Geometry measurements and sediment characteristics of selected streams in the Missouri River basin—Continued Map No. Station No. Station Name ACW DEP BDS di0 BSH BSL GRA 145 06794000 Beaver Creek'at. Genoa, Nebr. 16.0 1.28 i .28 84 84 .0014 146 06795500 Shell Creek near Columbus, Nebr 6.86 1.00 25 .30 66 65 .00054 147 06797500 Elkhorn River at Ewing, Nebr 32.0 .97 1 .34 22 13 .00073 148 06798500 Elkhorn River at Neligh, Nebr 54.9 .92 1 .28 15 7 .00094 149 06799000 Elkhorn River near Norfolk, Nebr 80.8 1.01 2 .24 24 15 .00069 150 06799100 North Fork Elkhorn River near Pierce, Nebr 12.8 .90 11 .25 63 17 .00052 151 06799500 Logan Creek near Uehling, Nebr 23.2 1.31 1 .24 79 48 .00039 152 06800000 Maple Creek near Nickerson, Nebr 15.7 .68 2 .31 64 50 .0014 153 06803000 Salt Creek at Roca, Nebr 7.01 1.30 77 .03 77 68 .00066 154 06803555 Salt Creek at Greenwood, Nebr 51.8 1.56 1 .59 66 64 .00051 155 06804000 Wahoo Creek at Ithaca, Nebr 10.2 1.06 1 .38 73 70 .00063 156 06806500 Weeping Water Creek at Union, Nebr 8.23 1.58 29 .50 79 75 .00086 157 06807000 Missouri River at Nebraska City, Nebr 270 10 1 .43 65 59 .00024 158 06808500 West Nishnabotna River at Randolph, Iowa 62.5 1.07 13 .34 75 72 .00051 159 06809500 East Nishnabotna River at Red Oak, Iowa 41.2 1.52 1 .42 80 61 .00040 160 06813000 Tarkio River at Fairfax, Mo.. . 29.3 1.49 2 .41 77 71 .00090 161 06814000 Turkey Creek near Seneca, Kans 9.14 1.83 14 .42 82 81 .00073 162 06817000 Nodaway River at Clarinda, Iowa 43.3 1.43 1 .46 68 54 .00056 163 06817500 Nodaway River near Burlington Junction, Mo. . . 60.4 1.37 3 .35 70 66 .00072 164 06818000 Missouri River at St. Joseph, Mo 270 10 1 .40 83 76 .00021 165 06819190 East Fork One Hundred and Two River near Bedford, Iowa 14.3 .87 22 .40 69 35 .00080 166 06819500 One Hundred and Two River at Maryville, Mo 24.7 1.04 2 .50 66 59 .00049 167 06820500 Platte River near Agency, Mo 41.2 2.35 6 .33 51 30 .00036 168 06821500 Arikaree River at Haigler, Nebr 5.94 .61 1 .36 33 25 .0015 169 06823000 North Fork Republican River at Colo.-Nebr. State line . . . 5.79 .55 1 .48 47 37 .0011 170 06823500 Buffalo Creek near Haigler, Nebr 1.92 .47 4 .34 29 13 .0025 171 06824000 Rock Creek at Parks, Nebr. . . 2.74 .37 2 .30 41 25 .0025 172 06824500 Republican River at Benkelman, Nebr 36.8 .30 1 .30 22 22 .0018 173 06825500 Landsman Creek near Hale, Colo 3.81 .71 24 .34 37 14 .0027 174 06827500 South Fork Republican River near Benkelman, Nebr 35.1 .30 1 .34 30 30 .0020 175 06828500 Republican River at Stratton, Nebr 38.1 .30 1 .30 30 30 .0020 176 06831500 Frenchman Creek near Imperial, Nebr 11.0 .50 11 2.4 45 39 .0014 177 06835000 Stinking Water Creek near Palisade, Nebr 8.23 .70 19 .47 88 71 .0023 178 06836000 Blackwood Creek near Culbertson, Nebr 3.84 1.08 40 .090 79 50 .0013 179 06838000 Red Willow Creek near Red Willow, Nebr 5.49 1.04 51 .058 55 37 .0013 180 06841000 Medicine Creek above Harry Strunk Lake, Nebr 12.3 .65 17 .72 68 64 .0011 181 06844500 Republican River near Orleans, Nebr 43.9 1.71 1 .59 58 56 .0006634 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Table 9.—Geometry measurements and sediment characteristics of selected streams in the Missouri River basin—Continued Map No. Station N0 Station Name ACW DEP BDS d BSH BSL GRA 182 06845000 Sappa Creek near Oberlin, Kans 4.88 .62 2 .80 89 89 .0013 183 06845200 Sappa Creek near Beaver City, Nebr 7.92 .65 5 .45 94 94 .00080 184 06846500 Beaver Creek at Cedar Bluffs, Kans 4.11 .64 92 .02 98 98 .0010 185 06847000 Beaver Creek near Beaver City, Nebr 4.27 .43 34 .56 58 26 .0013 186 06847500 Sappa Creek near Stamford, Nebr 8.08 .38 8 .56 46 35 .00067 187 06848500 Prairie Dog Creek near Woodruff, Kans 4.88 .40 62 .030 80 67 .00064 188 06851000 Center Creek at Franklin, Nebr 6.00 .75 1 .28 30 29 .0048 189 06853500 Republican River near Hardy, Nebr 42.7 .86 1 .71 43 43 .00072 190 06855800 Buffalo Creek near Jamestown, Kans 7.32 .47 82 .03 94 94 .00028 191 06855900 Wolf Creek near Concordia, Kans 3.35 .29 88 .02 96 96 .00061 192 06856000 Republican River at Concordia, Kans 57.9 2.9 1 .46 62 13 .00066 193 06859500 Ladder Creek below Chalk Creek near Scott City, Kans 2.74 .17 4 1.7 63 33 .0026 194 06860000 Smoky Hill River at Elkader, Kans 6.86 .40 19 .74 34 32 .0028 195 06861000 Smoky Hill River near Arnold, Kans 37.2 .40 1 .80 30 30 .0012 196 06862700 Smoky Hill River near Schoechen, Kans 6.71 .18 1 1.2 30 8 .0010 197 06863500 Big Creek near Hays, Kans. 7.01 1.01 29 .41 66 54 .00081 198 06864050 Smoky Hill River near Bunker Hill, Kans 33.5 .47 1 .78 69 66 .00074 199 06864500 Smoky Hill River at Ellsworth, Kans 30.5 .65 1 .77 55 52 .00055 200 06866500 Smoky Hill River near Mentor, Kans 33.2 1.27 10 .33 90 52 .00021 201 06867000 Saline River near Russell, Kans 13.7 .63 4 .64 62 58 .00058 202 06867500 Paradise Creek near Paradise, Kans 6.10 .50 27 .51 78 59 .0013 203 06869500 Saline River at Tescott, Kans 13.0 1.29 37 1.7 52 52 .00038 204 06870200 Smoky Hill River at New Cambria, Kans 24.4 2.44 5 .20 77 70 .00027 205 06871000 North Fork Solomon River at Glade, Kans 7.01 .14 7 .47 86 73 .0013 206 06871500 Bow Creek near Stockton, Kans 7.01 .16 1 .72 33 33 .0019 207 06872500 North Fork Solomon River at Portis, Kans 15.5 .38 1 .57 85 45 .00054 208 06873000 South Fork Solomon River above Webster Reservoir, Kans 11.0 .25 2 .59 28 9 .0015 209 06874000 South Fork Solomon River at Osborne, Kans 11.6 .28 9 .88 18 11 .0010 210 06876700 Salt Creek near Ada, Kans.. . 7.01 .45 51 .04 87 59 .00038 211 06876900 Solomon River at Niles, Kans 23.5 1.74 13 .58 57 36 .00016 212 06877600 Smoky Hill River at Enterprise, Kans 59.4 2.29 2 .43 94 57 .00031 213 06878000 Chapman Creek near Chapman, Kans 9.75 1.98 52 .05 97 83 .00054 214 06878500 Lyon Creek near Woodbine, Kans 7.92 .61 90 .02 92 46 .00079 215 06879900 Big Blue River at Surprise, Nebr 6.10 .59 44 1.2 76 42 .00044 216 06880000 Lincoln Creek near Seward, Nebr 7.62 1.12 74 .03 74 63 .00046 217 06880500 Big Blue River at Seward, Nebr 11.0 1.01 42 .22 82 75 .00039SUPPLEMENTAL INFORMATION 35 Table 9.—Geometry measurements and sediment characteristics of selected streams in the Missouri River basin—Continued Map No. Station No. Station Name ACW DEP BDS d„ o BSH BSL GRA 218 06880800 West Fork Big Blue River near Dorchester, Nebr 16.5 1.28 2 .27 74 73 .00025 219 06881000 Big Blue River near Crete, Nebr 26.8 1.37 1 .35 84 23 .00028 220 06883575 Little Blue River near Alexandria, Nebr 39.6 2.00 1 .62 70 65 .0012 221 06884200 Mill Creek at Washington, Kans 11.1 .84 9 .42 73 58 .00062 222 06884400 Little Blue River near Barnes, Kans 52.4 1.22 10 .66 91 81 .00052 223 06885500 Black Vermillion River near Frankfort, Kans 12.8 .92 78 .03 84 60 .00049 224 06887500 Kansas River at Wamego, Kans 223 11.0 1 .65 12 12 .00025 225 06888000 Vermillion Creek near Wamego, Kans 7.47 .75 64 .04 79 63 .00072 226 06889000 Kansas River at Topeka, Kans 159 8.0 1 .80 90 64 .00027 227 06891000 Kansas River at Lecompton, Kans 171 8.5 1 .86 93 75 .00027 228 06891500 Wakarusa River near Lawrence, Kans 12.8 1.54 84 .03 95 95 .00039 229 06892000 Stranger Creek near Tonganoxie, Kans 12.8 1.22 87 .03 76 76 .00018 230 06892350 Kansas River at DeSoto, Kans 165 8.5 1 .55 83 82 .00034 231 06894000 Little Blue River near Lake City, Mo 8.84 1.16 65 .03 73 52 .00034 232 06895500 Missouri River at Waverly, Mo 320 13 1 .38 61 60 .00015 233 06897500 Grand River near Gallatin, Mo 51.8 2.6 1 .27 62 40 .00034 234 06898100 Thompson River at Mount Moriah, Mo 43.9 2.01 1 .43 61 38 .00076 235 06898400 Weldon River near Leon, Iowa 21.0 .58 9 .35 70 65 .00079 236 06899500 Thompson River at Trenton, Mo 82.3 2.13 1 .32 42 21 .00076 237 06899700 Shoal Creek near Braymer, Mo 11.9 2.01 28 .43 45 39 .00089 238 06902000 Grand River near Sumner, Mo 70.1 3.96 26 .36 62 12 .00013 239 06902200 West Yellow Creek near Brookfield, Mo 11.4 1.37 10 .48 47 41 .00052 240 06905500 Chariton River near Prairie Hill. Mo 53.3 2.17 1 .41 57 50 .00032 241 06907700 Blackwater River at Valley City, Mo 18.0 2.44 38 .50 61 57 .00027 242 06908000 Blackwater River near Blue Lick, Mo 18.3 3.66 80 .03 97 65 .00035 243 06909000 Missouri River at Booneville, Mo 430 17.2 1 .35 58 58 .00016 244 06910500 Moreau River near Jefferson City, Mo 33.5 2.23 44 1.0 56 52 .00028 245 06911900 Dragoon Creek near Burlingame, Kans 9.14 .70 1 80 81 8 1 .00063 246 06913500 Marais Des Cygnes River near Ottawa, Kans. 33.5 1.74 19 .19 70 70 .00039 247 06914000 Pottawatomie Creek near Garnett, Kans 9.75 1.16 83 .03 93 93 .00020 248 06925200 Starks Creek at Preston, Mo. . 2.29 .18 2 8.6 32 30 .0056 249 06930000 Big Piney River near Big Piney, Mo 44.2 1.77 1 17 37 17 .0011 250 06931500 Little Beaver Creek near Holla, Mo 4.27 .28 1 18 9 2 .0056 251 06932000 Little Piney Creek at Newburg, Mo 15.2 .85 1 15 9 6 .0014 252 06934500 Missouri River at Hermann, Mo 424 17.0 1 .48 44 44 .0001336 CHANNEL GEOMETRY AND SEDIMENT, MISSOURI RIVER BASIN Table 10.—Width-discharge and width-gradient-discharge relations expressed in inch-pound units [ SCbd is silt-clay percentage of bed material; SCbk is silt-clay percentage of bank material; and d60 is median particle size of bed material, in millimeters. Q is mean discharge, in cubic feet per second; Q2 through Q100 are flood discharges, in cubic feet per second, of recurrence intervals 2 through 100 years; and W is active-channel width, in feet] Channel type Equation Channel type Equation T able 2 High silt- Q = 0.088W212 Sand bed Q = 0.15W1'62 clay bed Q2 = 7.7W186 sand banks Q2 = 7.1W1'32 scbd= Qs = 23W1'77 (SCM<10; Q5 = 19W126 61.100; Q10 = 36W1'74 SCbk<70; Q,„ = 34W1'21 d60<2.0). Q2S = 60W1'71 dso<2.0). Q25 = 68W115 Qbo = 74W1'71 Qs0= 100W1'12 Q10„ = 85W1-74 Q10„ = 130W112 Med. silt- Q = 0.14W1,76 Gravel bed Q = 0.095W1'81 clay bed Q2 = 20W1'27 (d6„= Q2 — 17W115 64). Q2 = 5.3W1'43 2.0). Qu = 330W° 96 Q50 = 470W°'93 Q10„ = 600W°-92 Channel type Equation Table 3 All data Q = 0.13W1'71 Q2 = 16W1'22 Qs = 55W1'10 Q10 =100W104 Q25 = 200W°'97 Qs„ = 290W0'94 Qioo= 370W0'94 Table 10.—Width-discharge and width-gradient-discharge relations expressed in inch-pound units—Continued Channel type Equation Channel type Equation Table 4 Low silt- Q = 0.0084W1'36G-0'59 Sand bed, Q = 0.023W1'34G-0'4' clay sand bed Q2 = 0.89W°'8°G-0'69 banks Q2 = 1.4W102G_a42 scbd= Qs = 3.8W°'68G-0'66 (SCbd< 11-30; Q,0 = 9.4W° 64G-0'61 10; Qs =3.1W° 94G-0'46 scbk< d50<2.0). Q25 = 28W°’60G-0'54 70; Q,„ = 5.8W°'88G-0'46 Qs„ = 58W°'58G _0'49 d50<2.0). Q2S = 12W° 83G “°-44 Q,„„ = 120W056G~°-43 Qs„ = 19W°'80G-0'43 Qioo = 31 W°'77G-0'42 Sand bed, Q = 0.012W‘43G_0'49 Gravel bed Q5 = 28W° 75G“a27 silt banks Q2 = 6.4W°'96G-0'34 (dso= Q,„ = 47W°'63G-0'32 (®^bd^ 10; Qs = 20W°'87G-0'33 2.0-64). Q25 = 90W°'5°G _0-35 SCbk = 70-100; Q10 = 39W°'81G~°'33 Qso=140Wa42G“°-36 ds„<2.0). Q25 = 78W°'75G-0'32 Q100 = 220W°'35G-0'37 Qso = 130W°'72G_0'30 Q,„0 = 190W°’68G-0'31 Cobble bed Q = 0.098WL82G-0-01 (d50>64). Q2 = 0.95W1-39G“034 Qs = 3.7W113G-0'38 Q.o^s.ew0-9^-0-38 Q26 = 23W°'85G-0'36 Qso = 47 W°'76G -0'34 Q,„„ = 91W°'68G-0'31 Data source Equation Table 5 All data Q = 0.042W1'54G-0'26 Q2 = 2.7W°'96G~0'40 Qb = 7.1 W°'82G-0'45 Q10 = 12W°’75G~0'47 Q25 = 23W°'69G-0'48 Q5„ = 34W0,65G-0'48 Q100 = 50Wa61G~°-48 Data source Equation Data source Equation Table 6 North and Q = 5.6W0'90 Calamus, Cedar, Q = 3.4W°'86 Middle Q2 = 0.12W1’86 Elkhorn, North Loup Qs = 0.34W218 Fork Elkhorn, Rivers. Q,„ = 0.016W2'37 and Q2s = 0.0065W2'59 South Qs„ = 0.0034W2'74 Loup Q,oo = 0.0018W2 90 Rivers.SUPPLEMENTAL INFORMATION 37 Table 10.—Width-discharge and width-gradient-discharge relations expressed in inch-pound units—Continued Discharge variability Equation Discharge „ variability E4Uatl0n Ti ible 7 Low, Q = 0.18W1'62 High, Q=0.33W136 Q10/Q< 60 Q = 0.031W136G-0'42 QJQ>60 Q = 0.044W103G a49 (55 data Q2 = 1.9W1'51 (41 data Q2 = 40W104 sets). Q2 = 0.25WL18G 049 sets). Q2 = 22W°'81G 023 Q5 = 3.6W1'50 Qs = 180W089 Q5 = 0.35W113G-0'56 q5 = how°-69g-°19 Q10 = 5.7W147 Q10 = 400W0'81 QIO = 0.53W109G °'58 Q,„ = 290W0'62G-016 Q26 = 9.7W1'43 Q26 = 970W°-71 Q2S = 0.89W105G_0-58 Q26=840W°-55G 012 Q60 = 14W141 Q60 = 1,600W°'66 Q60 = 1.3W101G 058 Oso = 1,700W0'50G-009 Qioo= 17W140 Q,„0 = 2,300W° 64 Qioo = 1.9W°'"G 058 Q,„0 = 3,300W°45G 006 Equation No. Equation Equations for Muddy Stream Channels 6 Q = 0.098W20 7 Q2 = 12W15 8 Q5 = 47W1'4 9 Q10 = 110W1'3 10 Q25 = 190W1'2 11 Qs„ = 290W1'1 12 Q,„„ = 350Wl1 *U.S. GOVERNMENT PRINTING OFFICE: 1982—576-034/122 . •  y DAYS Possible Origins of Till-Like Deposits Near the Summit of the Front Range in North-Central Colorado GEOLOGICAL SURVEY PROFESSIONAL PAPER 1243 LIBRARY UNIVERSITY SF CALIFORNIA .; U.S. DEPOSITORY APR 9 1982 Possible Origins of Till-Like Deposits Near the Summit of the Front Range in North-Central Colorado By RICHARD F. MADOLE GEOLOGICAL SURVEY PROFESSIONAL PAPER 1243 A description of two diamictons previously mapped as till and a reinterpretation of their origin. Periglacial mass wasting, landslide, glacial, and alluvial-colluvial origins are considered UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1982UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging in Publication Data Madole, Richard F. Possible origins of till-like deposits near the summit of the Front Range in north-central Colorado (Geological Survey Professional Paper 1243) Bibliography: p. 30 1. Drift—Front Range (Colo, and Wyo.) I. Title. II. Series. QE579.M3 551.3'14 81-6616 AACR2 For sale by the Branch of Distribution, U.S. Geological Survey 604 South Pickett Street, Alexandria, VA 22304CONTENTS Page Abstract............................................................................... 1 Introduction........................................................................... 1 Acknowledgments ................................................................... 2 Study sites............................................................................ 2 Sedimentary characteristics of the diamictons.......................................... 2 Distribution, contacts, and thickness ............................................. 2 Composition........................................................................ 4 Texture............................................................................ 5 Boulder-size range and abundance .............................................. 6 Grain-size distribution of the matrix ......................................... 9 Clast shape................................................................... 10 Macrofabric .................................................................. 11 Microfabric .................................................................. 13 Surface features of quartz grains............................................. 13 Possible origins for the diamictons................................................... 15 Periglacial mass wasting deposits................................................. 15 Landslide deposits ............................................................... 19 Rockfall and rockslide avalanches............................................. 20 Debris flows ................................................................. 21 Glacial transport.....................................................-........ 22 Alluvial-colluvial deposits ...................................................... 24 Summary........................................................................... 27 References cited...................................................................... 30 ILLUSTRATIONS Page Figure 1. Generalized geologic map................................................................................... 3 2. Oblique aerial view west across Niwot Ridge to the Continental Divide.................................... 4 3. Map of rock units and the diamicton on Niwot Ridge and the composition of the diamicton ................. 5 4. Diagram showing approximate thickness of the diamicton on Niwot Ridge.................................... 6 5. Map of rock units and the diamicton on the unnamed ridge north of Niwot Ridge, and the composition of the diamicton ................................................................................................. 7 6. Diagram showing approximate thickness of the diamicton on the unnamed ridge ............................. 8 7. Ground view of diamicton on Niwot Ridge, showing large dispersed boulders ............................... 8 8. Graph of boulder abundance in the diamictons, till of Pinedale age, and residuum......................... 9 9. Diagrams showing mean grain-size distribution of samples of the Cox horizon of soil profiles............. 9 10. Diagram comparing the angularity of megaclasts in till and outwash of Pinedale age, the diamictons, and residuum ............................................................................................. 10 11. Plot of macrofabric at site II on the unnamed ridge ...................................................... 12 12-15. Scanning electron micrographs of: 12. Quartz grains from residuum ......................................................................... 16 13. Parallel ridge and step patterns on quartz grains from diamicton on Niwot Ridge and till .......... 17 14. Arcuate patterns on quartz grains from diamicton on Niwot Ridge and till .......................... 18 15. Linear depressions on quartz grains from diamicton on Niwot Ridge ................................ 19 16. Oblique aerial view of diamicton on Niwot Ridge overlying Tertiary monzonite ................................ 20 17. Comparison of sorting, graphic mean plotted against inclusive graphic standard deviation .................... 22 18. Photograph of alluvial and colluvial deposits on canyon floor of Cache la Poudre River ...................... 24 19. Map locating diamictons that have been mapped as Tertiary stream deposits ................................... 26 20. Photograph of diamicton mapped as boulder gravel capping a ridge in Squaw Pass quadrangle ................... 28 inIV CONTENTS TABLES Page Table 1. Summary of boulder sizes measured in plots on diamictons, till, and residuum................................ 6 2. Shapes of clasts in the diamicton on Niwot Ridge and the unnamed ridge ................................... 11 3. Summary of macrofabric data for the diamicton on the unnamed ridge ....................................... 12 4. Comparison of mean vector and vector magnitude for the macrofabrics and microfabrics of the diamicton on the unnamed ridge .......................................................................................... 14 5. Surface features of quartz grains from four types of deposits investigated with the scanning electron microscope..................................................................................... 15POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS NEAR THE SUMMIT OF THE FRONT RANGE IN NORTH-CENTRAL COLORADO By Richard f. Madole ABSTRACT Diamictons cap ridges and fill U-shaped cols at several localities along the Continental Divide in the northern Front Range, north-central Colorado. In the past, a few of the diamictons were mapped as till, chiefly because they contain many large boulders of exotic rocks in a poorly sorted matrix. However, four categories of deposits, all of which are common to this region, possess these characteristics. They include (1) periglacial mass wasting deposits; (2) landslide deposits; (3) glacial deposits; and (4) alluvial-colluvial deposits. Because the genesis of the diamictons profoundly influences the interpretation of the structural, erosional, and climatic histories of the region, two areas of diamictons, previously mapped as till, were restudied. The two areas are on Niwot Ridge and an unnamed ridge to the north, high interfluvial divides that extend east from the Continental Divide in western Boulder County, Colo. Transport by slow mass movement in a periglacial environment is rejected as an origin for the diamictons, and an interpretation of origin by landsliding has several weaknesses. If ice were the transporting agent, the glaciers were small (less than 5 km from uppermost accumulation area to terminus) and not the large ice cap suggested by earlier workers. Even though the evidence does not unequivocally prove the origin of the diamictons, it suggests three arguments favoring the interpretation that they are mixtures of mostly alluvium and colluvium. These arguments are based on (1) the physical resemblance of the diamictons to bouldery deposits known to consist of alluvium, colluvium, and debris flow deposits; (2) the occurrence of similar diamictons in areas where glaciation cannot account for them, and (3) the probability that the diamictons are of Tertiary rather than Quaternary age because of the amount of erosion that has occurred since some of them were deposited. The two diamictons studied, which were previously mapped as till of Quaternary age, are here interpreted to be aggregations of alluvium, colluvium, and possibly some debris flow deposits, which accumulated during Tertiary time on a surface of low relief that subsequently was uplifted and deeply dissected. INTRODUCTION Diamictons that consist of boulders in a poorly sorted, sandy matrix top ridge crests and fill cols at several localities along the summit of the northern Front Range. Diamicton is a nongenetic term for a poorly sorted terrestrial sediment containing a wide range of particle sizes, such as a till (Flint and others, 1960a, 1960b), and it is used here to avoid a genetic term for deposits whose origin is uncertain. The diamictons are texturally similar to late Pleistocene tills in nearby valleys, but they are older than the tills. The diamictons predate the formation of the deep valleys through which late Pleistocene valley glaciers moved, and they occur 200-400 m above the uppermost occurrence of till along adjacent valley sides. Morphologic characteristics of the deposits that could aid in interpreting their origin are absent from the diamictons, possibly because they are old and have been greatly modified by mass movement and erosion. Without landforms it is difficult to determine whether the deposits are till or some type of nonglacial deposit, because the sedimentological criteria of poor sorting and the presence of large boulders of exotic rock types are common to diamictons of several origins (Flint and others, 1960a; Harland and others, 1966). Faceted or striated clasts were not found in any of the diamictons examined, and weathering has long since erased any markings that might have been on the clasts at the surface. However, distinctively striated clasts are not common in the tills of the region, because the coarsegrained crystalline rocks that dominate these deposits do not striate readily. Poorly sorted terrestrial deposits of Miocene to Quaternary age are widespread in the mountains of Colorado and probably are common to many parts of the Rocky Mountain region. Different origins assigned to these diamictons result in markedly different interpretations of the climatic, tectonic, and erosional histories of the region. Several deposits initially described as till in various publications (Atwood and Mather, 1932; Bryan and Ray, 1940; Eschman, 1955; Gable, 1972; Harris and Fahnestock, 1962; Ives, 1953; Moss, 1951; Madole, 1960; Ray, 1940; Richmond, 1948; l2 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS, FRONT RANGE, COLORADO Wahlstrom, 1940, 1947) were reinterpreted to be diamictons of nonglacial origin (Richmond, 1965, p. 217-218; Madole, 1976, p. 302-303). Accordingly, this has modified previous interpretations of glacial history. This report summarizes evidence gathered from the study of two diamictons that previously were mapped as till (Wahlstrom, 1940, 1947; Ives, 1953; Madole, 1960) and that formed an integral part of Wahlstrom’s (1947) work on the Front Range summit and subsummit erosion surface problem. The discussion concerning the origin of these two deposits is based chiefly on sedimentological data, because the deposits are relatively small and isolated and lack remains of landforms. The first part of the report describes the sedimentary characteristics of the two d iamictons, and the second presents four possible origins for the diamictons in terms of their sedimentary characteristics. ACKNOWLEDGMENTS The National Science Foundation College Teacher’s Research Participation Program and Academic Year Extension Grant GY-5574 funded part of this work. James A. Clark provided invaluable assistance in the field throughout the summers of 1968 and 1969. Sharon Allred, Thomas Bassier, Nancy Finnegan, Holly Horton, Darv Lloyd, Barbara Madole, Mark Madole, Thomas Madole, Nancy McKinnie, and Harvey Moulton helped in various parts of the work involved in the seismic surveys, excavating pits and recording data for macrofabrics, measuring microfabrics, and evaluating the roundness of clasts in the deposits studied. Robert McGrew, Electron Microscopy Suite, Department of Molecular, Cellular, and Developmental Biology, University of Colorado, provided instruction in the operation of the scanning electron microscope. Charles Semmer and Ginger Wadleigh of the National Center for Atmospheric Research, Boulder, Colo., supplied the photographs for figures 2 and 16. The following individuals of the Institute of Arctic and Alpine Research gave assistance: J. T. Andrews and Nel Caine helped with the computer programs for till fabric analysis and reviewed a preliminary draft of this report; Larry Williams helped with computer programs for two-dimensional computer analysis of microfabrics; Rolf Kihl did grain-size analyses. K. L. Pierce, G. R. Scott, R. B. Taylor, D. A. Coates, G. A. Izett, and C. A. Wallace, U.S. Geological Survey, provided many helpful suggestions for improving the presentation of this study. STUDY SITES The diamictons chosen for study cap two ridges, Niwot Ridge and an unnamed ridge to the immediate north, that are high interfluvial divides extending east from the Continental Divide (fig. 1). These areas were the principal sites studied because the composition of the diamictons relative to that of the Audubon-Albion stock demonstrates that the diamictons were transported to their sites of deposition. Only a few of the diamictons along the summit of the northern Front Range can be shown unequivocally to have been transported for distances greater than would be expected by creep and solifluction. The diamictons on Niwot Ridge and the unnamed ridge to the north, however, can be shown to be far removed from their source. The cobbles and boulders in them, which (based on five measurements) make up an estimated 10-30 percent of the deposits, consist almost entirely of clasts derived from Proterozoic quartz monzonite and biotite gneiss (Wahlstrom, 1940, 1947; Gable and Madole, 1976); yet these diamictons overlie the Audubon-Albion stock (chiefly monzonite of Tertiary age). Hence, no ambiguity remains about whether these two diamictons were transported for considerable distances; the question is, how were they transported? The diamictons on Niwot Ridge and the unnamed ridge to the north are at altitudes of about 3,450-3,720 m, which, as shown in figures 1 and 2, approaches the level of the Continental Divide. The deposit on the unnamed ridge is 100-140 m above timberline (altitude about 3,350 m) and 155-290 m above adjacent valley floors. The deposit on Niwot Ridge is 100-240 m higher than that on the unnamed ridge and 260-440 m above the valley floors. SEDIMENTARY CHARACTERISTICS OF THE DIAMICTONS DISTRIBUTION, CONTACTS, AND THICKNESS The diamicton on Niwot Ridge is about2 km long, as much as 0.5 km wide, and according to seismic data, 3-36 m thick (figs. 3,4). The diamicton on the unnamed ridge is about 0.6 km long, 0.3 km wide, and 5.5-19 m thick (figs. 5, 6). These widths include only the crestal portion of each ridge, because solifluction has spread the diamictons down the valley sides to adjacent valley floors (figs. 1, 2). Both diamictons are sheet deposits that unconform-ably overlie igneous rocks of the Tertiary Audubon-Albion stock. Seismic data obtained on the unnamed ridge (fig. 6) suggest that the contact between theiudubon /lount Toll /> y^Kawnefe' ak l r~Zri’\'sJr. Pawftee*-L>fePass IV • ■/■/■ //-A' :£^/X<^p>X£! '/s.try. -AS (A fi Bowlder! -Kiowa, -frlount- V -r Albion. diamicton and bedrock is probably uneven. The upper surfaces of the diamictons are also uneven, owing to postdepositional mass movement; this is particularly apparent on Niwot Ridge, where solifluction has I 1 1 1 i 1 ——i-----------------1--------------1— 0 12 3' KILOMETERS CONTOUR INTERVAL 200 FEET 1 ft= 0.3048 m Figure 1.—Generalized geologic map showing the topographic setting of the diamictons on Niwot Ridge and the unnamed ridge to the north and their location on the Tertiary Audubon-Albion stock, above till in adjacent valleys, and east of two Proterozoic rock units from which most of their clasts were derived. Modified from Gable and Madole (1976); Pearson (1980). Contour interval 200 ft; 1 ft = 0.3048 m. HOLOCENE Organic-rich sediment and peat PLEISTOCENE Till of Pinedale and Bull Lake age Boulder Creek Granodiorite Biotite gneiss (formerly Idaho Springs Formation) Diamicton similar to that on Niwot Ridge and the unnamed ridge, not included in this study Glacier SEDIMENTARY CHARACTERISTICS OF THE DIAMICTONS 105°37'30"____________ 3 EXPLANATION TERTIARY Diamicton-Dashed where mass movement has transported beyond initial site of deposition Audubon-Albion stock-Monzonite, quartz monzonite, and syenite PROTEROZOIC Silver Plume Quartz Monzonite Biotite quartz diorite 106° 105° 41° - __[___WYOMING 1 ”Y" "" COLORADO [ Approximate\ area of " figure 1 \___ ___T X _X 7------------1 sC 1 ^ Denver yrf/mm k* Yd| r T d4 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS. FRONT RANGE, COLORADO Figure 2.—Oblique aerial view west across the summit of Niwot Ridge to the Continental Divide. Diamictons cap ridges and fill cols at several localities along the Continental Divide in the northern Front Range. Diamicton boundaries approximate. Solifluction has transported the diamicton down the sides of Niwot Ridge across the areas now occupied by snowbanks (arrows). Turf-banked terraces and stone-banked terraces, features of periglacial mass wasting, visible on right. A diamicton similar to that on Niwot Ridge occurs in the saddle between Mount Albion and Kiowa Peak. (National Center for Atmospheric Research photo.) formed a series of large, turf-banked terraces (faintly visible lineations from left to right in fig. 2). Although both diamictons consist of boulders and cobbles (10-30 percent based on five measurements) in a matrix composed predominantly of sand and granules, a lenticular unit of homogeneous, well-sorted, very fine sand and silt (unit B, fig. 6) is present at fabric site IV on the unnamed ridge, beneath 60 cm of rocky colluvium. The unit was exposed throughout the extent of two trenches, each about 1 m deep and 3 m long, that were dug at right angles to each other at fabric site IV. Fine sand was encountered also in an excavation 91 m to the northwest. Interpretation of seismic data suggests that sediment like that in unit B also may exist at the west edge of the diamicton (fig. 6, query), and that at the east edge of the diamicton, unit B ranges in thickness from 5 to 8.2 m and pinches out to the west. The difference in seismic velocities between the sand of unit B and the diamictons is distinct. Eight velocities measured in unit B ranged from 689 to 939 m/s (meters per second) (mean, x = 845; one standard deviation, s = 124); 15 velocities measured in the diamicton on the unnamed ridge north of Niwot Ridge ranged from 1,015 to 2,591 m/s (x = 1,329; s = 313), and 13 velocities measured in the diamicton on Niwot Ridge ranged from 1,375 to 4,450 m/s (x = 3,203; one standard deviation, s = 997). The higher velocities of the diamicton on Niwot Ridge could be due to frozen ground and a higher content of pebbles, cobbles, and boulders. The low end of the velocity range of both diamictons could be the result of sands like unit B being present at the sites where the low velocities were measured. COMPOSITION Differences in the composition of boulders and cobbles between the diamictons on Niwot Ridge and the unnamed ridge indicate that they were not derivedSEDIMENTARY CHARACTERISTICS OF THE DIAMICTONS 5 105°37' UNCONSOLIDATED DEPOSITS: Qt Talus deposits (Quaternary) :: ;Td:::: Diamicton (Tertiary) BEDROCK: Silver Plume Quartz Monzonite (Proterozoic Y) Biotite gneiss (Proterozoic X) (\^Ta\)\ Audubon-Albion stock (Tertiary) Miscellaneous rocks chiefly from -------- dikes and small intrusives (Tertiary and Precambrian) 5o SEISMIC SHOT HOLE VD FABRIC-STUDY SITE c-3a COMPOSITION-STUDY SITE Figure 3.—Rock units and the diamicton on Niwot Ridge, and the composition of the diamicton and location of fabric-study pits, seismic shot holes, and composition- and boulder-study sites. Histogram columns show bedrock source, in percent, of clasts in diamicton. Section A-A', figure 4. Contour interval 25 m. from the same source area, despite their location on opposite sides of upper South St. Vrain Creek. An estimate of the boulder and cobble compositions was obtained by identifying rock types within five plots (4 X 4 m) laid out on each diamicton (figs. 4, 5). Between 50 and 115 boulders and cobbles were identified in each plot; the variation in the number of clasts counted is a function of what was available on the surface. These counts indicate that 36-70 percent of the boulders and cobbles in the diamicton on Niwot Ridge were derived from biotite gneiss (formerly called Idaho Springs Formation), 22-51 percent from the Silver Plume Quartz Monzonite (“granite” clasts from migmatitic parts of the Idaho Springs Formation were counted as quartz monzonite), and 1-7 percent from the monzonite of the Audubon-Albion stock. In comparison, 66-98 percent of the boulders and cobbles in the diamicton on the unnamed ridge were derived from the Silver Plume Quartz Monzonite, 0-2 percent from biotite gneiss, and 2-34 percent from the monzonite stock. TEXTURE Sediment size studies concentrated on the size range and abundance of boulders, and on the percentage of sand, silt, and clay in the matrix. For the purposes of this discussion, cobbles and boulders constitute the framework clasts, and matrix includes all material less than 32 mm in size (pebbles, granules, sand, silt,6 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS, FRONT RANGE, COLORADO T ABLE 1.—Summary of boulder sizes measured in UxU-m plots on diamictons, till, and residuum on Niwot Ridge, the unnamed ridge, and in the Red Roclc-Brainard Lakes area Deposit type Site1 No. of observations Percent 25-50 cm Percent 50-75 cm Percent 75-100 cm Percent > 100 cm Maximum size observed (cm) Diamictons on NR-l 74 58 23 10 9 188 Niwot Ridge NR-2 93 70 25 3 2 343 and the NR-3 115 76 19 3 2 112 unnamed NR-4 54 80 18 2 0 79 ridge. NR-5 71 69 20 6 5 234 UR-2 56 71 21 4 4 170 UR-4 50 70 22 2 6 122 Till RB-1 49 85 13 0 2 140 RB-2 50 66 28 2 4 122 RB-3 50 54 26 16 4 165 Residuum NR-6 68 87 13 0 0 66 NR-7 76 96 2 2 0 81 NR-8 13 91 7 2 0 76 UR-6 54 98 2 0 0 74 1 NR, Niwot Ridge; UR, Unnamed ridge; RB, Red Rock-Brainard Lakes area. Site locations for NR and UR are shown on figures 3 and 5 (composition-study sites), except for NR-7 and NR-8, which are too far east to be included. and clay). As noted previously, boulders and cobbles (framework clasts) are estimated to make up 10-30 percent of the diamictons, based on five measurements. As for the matrix, eight samples from Niwot Ridge and six samples from the unnamed ridge yielded the following pairs of means, respectively: percent pebbles — 49 and 28.8; percent granules — 6.6 and 9.6; percent sand-silt-clay — 43.7 and 61.6. Sand makes up 54-76 percent of the less-than-2 mm fraction, whereas clay constitutes only 3.5-10.5 percent. BOULDER-SIZE RANGE AND ABUNDANCE One of the most distinctive features of the diamictons is that large boulders, such as shown in figure 7, are scattered over the surface of the deposit. Large boulders are also common on the surface of the tills of the region, to such an extent that this characteristic is a criterion used in delineating till boundaries. Large boulders also occur on other surficial deposits but are not apparently as numerous and uniformly distributed. Because of these occurrences, an effort was made to quantify the similarities and differences in size and distribution of boulders on the surface of the diamictons on Niwot Ridge and the unnamed ridge, on till in nearby valleys, and on residuum on slopes and interfluves comparable to those occupied by the diamictons. An estimate of the size and distribution of boulders in the diamictons was obtained by (1) measuring the WEST EAST A A' Figure 4.—Diagram showing the approximate thickness of the diamicton on Niwot Ridge, as interpreted from seismic data. Numbers indicate seismic shot holes (fig. 3). The diamicton ranges in thickness from a minimum of 3 m, just west of the hut, to a maximum of 36 m, at or just west of shot hole 2, near the eastern limit of the deposit. Spurious data recorded at six shot holes (4, 6, 8, 9,13, and 15) were attributed to discontinuous frozen ground. The east end of the section was oriented to connect shot hole 2 with C-6; hence, shot hole 1 is not included in this diagram (fig. 3, orientation A-A').SEDIMENTARY CHARACTERISTICS OF THE DIAMICTONS 7 105°36' UNCONSOLIDATED DEPOSITS: Or :Td ;;; Talus deposit (Quaternary) Diamicton (Tertiary) BEDROCK: Silver Plume Quartz Monzonite (Proterozoic Y) Biotite gneiss (Proterozoic X) Audubon-Albion stock (Tertiary) Miscellaneous rocks chiefly from dikes and small intrusives (Tertiary and Precambrian) 90 SEISMIC SHOT HOLE VD FABRIC-STUDY SITE C_5A COMPOSITION-STUDY SITE Figure 5.—Rock units and the diamicton on the unnamed ridge north of Niwot Ridge, and the composition of the diamicton and location of fabric-study pits, seismic shot holes, and composition- and boulder-study sites. Histogram columns show bedrock source, in percent, of clasts in diamicton. Section B-B', figure 6. Topography mapped with theodolite August 1968 by R. F. Madole and J. A. Clark. Contour interval 3 m. long axis of all boulders found on the surface within the 4X4-m composition-study sites, and (2) measuring the long axis of all boulders longer than 75 cm encountered along a series of 10 randomly oriented 15-m strips. Only a single axis (the longest exposed) was measured because most boulders are partially buried, and it is environmentally undesirable to tear up alpine tundra to measure them. The principal objective was an estimate of maximum size, and the shapes of the boulders in this area do not vary greatly, most being blocky and rectangular. Method 1 revealed that most boulders are in the 25 to 50-cm range regardless of deposit origin and that boulders more than 75 cm long are generally uncommon (table 1). Because of these results, attention was shifted to the uncommonly large boulders, those whose apparent longest axis exceeded 75 cm. Method 2 was developed to deal only with characterizing the distribution of large boulders (fig. 8). This method was simpler than method 1 and permitted the sampling of a much larger area of each deposit in a fast and random manner.8 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS, FRONT RANGE, COLORADO WEST B METERS EAST S’ METERS -3490 -3480 Figure 6.—Diagram showing the approximate thickness of the diamicton on the unnamed ridge, as interpreted from seismic data. Numbers indicate seismic shot holes (fig. 5). The diamicton is about 5.5-19 m thick. Interpretation of seismic data in section B-B (fig. 5, orientation) suggests that the bedrock surface beneath the diamicton is irregular and that channel deposits exist near its edges. The channel(?) deposit shown on the west is inferred from the similarity of seismic velocities to those recorded for unit B, where excavations provided lithologic information. Figure 7.—Ground view of the diamicton on Niwot Ridge showing large boulders dispersed over its surface. Large boulders are common on the surface of the diamictons, especially on Niwot Ridge where many like the one in foreground are 3 m long (pack measures 40x40 cm). Most of the very large boulders, including one in foregound, are Proterozoic biotite gneiss.SEDIMENTARY CHARACTERISTICS OF THE DIAMICTONS 9 u z o A o (/> m < cc o z < 44 r 40 - 36 32 T) ir LU Q- D 28 24 20 16 12 DIAMICTON TILL o Method 1 suggests that the diamictons on Niwot Ridge and the unnamed ridge contain a greater range of boulder sizes and larger boulders than does residuum elsewhere on these ridges and in comparable settings on other ridges. Boulders 2-4 m long are common in the diamictons and in the tills in the valleys below, but they are rare in the nonglacial deposits in and near the study area except along cliffs, near tors, or on moderate to steep slopes (10°-20° or more) at altitudes above 3,600 m. This difference in boulder size is corroborated by the frequencies obtained with method 2 (fig. 8). The number of boulders counted along each set of 10 randomly oriented 15-m strips on the diamictons ranged from 13 to 42, whereas the number for more than half the counts made on residuum was 0 or 1. GRAIN-SIZE DISTRIBUTION OF THE MATRIX RESIDUUM 0 SURFICIAL DEPOSIT Figure 8.—Boulder abundance measured by method 2 on the diamictons on Niwot Ridge and the unnamed ridge, till of Pinedale age, and residuum. Dot indicates the mean number of boulders greater than 75 cm long counted per unit distance (150 m); vertical bar indicates range in number of boulders counted. Figure 9 shows the grain-size distributions for the matrix of the diamictons and unit B on the unnamed ridge north of Niwot Ridge (fig. 6). The less-than-2 mm fraction of the diamictons is chiefly sand (typically between 50 and 76 percent), of which the coarse and very coarse sand sizes are dominant. Clay-sized material typically makes up 3-11 percent of the less-than-2 mm fraction of the diamictons. Several tens of DIAMICTON ON NIWOT RIDGE Percent (8 samples) X S Pebbles 49.7 16.0 Granules 6.6 1.0 Sand-Silt-Clay 43.7 15.6 GRAIN SIZE, IN MILLIMETERS DIAMICTON ON UNNAMED RIDGE (6 samples) X S 28.8 9.0 9.6 1.5 61.6 8.0 GRAIN SIZE, IN MILLIMETERS UNIT B ON UNNAMED RIDGE (2 samples) X 04 0.3 99.3 GRAIN SIZE, IN MILLIMETERS Figure 9.—Diagrams showing mean grain-size distribution of samples of the Cox horizon of soil profiles at eight sites on the diamicton on Niwot Ridge, six sites on the diamicton on the unnamed ridge, and two sites on unit B on the unnamed ridge. Percent of pebbles (4-64 mm), granules (2-4 mm), and sand-silt-clay (less than 2 mm) is shown in terms of sample mean (x) and one standard deviation (s) about the mean.10 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS, FRONT RANGE, COLORADO analyses show that the tills of the area (both Bull Lake and Pinedale equivalents) contain similar amounts of sand. Sand was also the dominant size in a few analyses of residuum. Hence, the grain-size distribution of the less-than-2 mm fraction is believed to be controlled more by the source rocks than by the age or origin of the deposit, except for unit B. CLAST SHAPE Boulder shape proved to be the least significant parameter examined. It apparently reflects the number and orientation of joint sets in a particular rock type. The rocks of the study area, especially the Silver Plume Quartz Monzonite, yield mostly blocky or rectangular boulders, a fact that complicated the measurement of the macrofabrics, discussed later. Clast roundness was measured from photographs taken of exposures of till, outwash, residuum, and diamictons. Photograph sites for residuum included localities where most clasts are from just one of the major rock types of the area (namely biotite gneiss, Proterozoic quartz monzonite, or rocks of the Tertiary stock). Tracings were made of the outlines of the clasts visible in each photograph. Next, these tracings were matched as nearly as possible to one of the categories in Lees’ (1964) chart for rapid visual determination of grain angularity. E ight different observers performed the matching procedure on all the samples. The curves of figure 10 are based on a plot of all roundness values obtained by these observers for cobbles and boulders in till, outwash, residuum, and diamictons. The diamictons on Niwot Ridge and the unnamed ridge to the north probably were derived from different source areas (see fig. 1 and discussion of composition), and because they occur at different heights, they possibly were derived at different times. In spite of these differences, the clasts of the two diamictons show a similar degree of rounding. Actually, few clasts in either deposit are well rounded. The majority are ANGULARITY IN ARBITRARY UNITS Figure 10.—Diagram comparing the angularity of megaclasts in till and outwash pf Pinedale age, in the diamictons, and in residuum. Numerical values for angularity are from Lees (1964), and the correspondence to categories ranging from well rounded to angular is based on a comparison with Pettijohn (1949, p. 52). Cumulative frequency curves illustrate the pronounced difference in angularity between clasts in till and clasts in residuum. Whereas 85 percent of the clasts in till have angularity values less than about 390 (are well rounded to subrounded), 85 percent of the clasts in residuum have values greater than 390 (are subangular to angular) and reach values much higher than those in any of the other types of deposits. Moreover, half of the clasts in residuum are more angular than all but a fraction of the clasts (about 10 percent or less) in the diamictons. It should be noted that many of the samples used to construct the curves for till and outwash were at least twice as far from their probable source areas as were the samples used to construct the curves for the diamictons.SEDIMENTARY CHARACTERISTICS OF THE DIAMICTONS 11 subangular, many are subrounded, and a small percentage are highly angular. In contrast, the majority of clasts in residuum, whether or not moved by solifluction, tend to be strikingly angular regardless of the rock type. The similarity of the curves for the diamictons is not due to similar rock types, because the rock types in each differ (figs. 3,5). The differences in angularity of clasts in the different types of deposits are interpreted as being a function of differences in the mode and distance of transport. Residuum, which has moved only short distances by creep or solifluction, contains clasts that are mostly unrounded. MACROFABRIC As used here, macrofabric refers to the orientation in three dimensions of the axes of pebbles, cobbles, and boulders, whereas microfabric refers to orientations in two dimensions only of particles chiefly finer than 2 mm measured in thin sections. The study of fabric and its directional significance in tills, gravel, and diamictons has a long history, which was summarized in Potter and Pettijohn (1977). The following principles from their summary apply to the sediment studied here: (1) particles immersed in the transporting media tend to aline themselves parallel to and dipping into the flow direction, and (2) particle shape and size as well as local geometry of the substrate can introduce variations; commonly large particles are better oriented than smaller ones and simple shapes better than complicated ones. Although shape was recorded for each clast, azimuth and plunge were measured for only the longest axis. Clasts with equidimensional axes or long axes less than 1.5 times the intermediate axis were excluded from the study. Many clasts in both diamictons were excluded from study because of this limitation. Table 2 summarizes the shapes recorded for 500 clasts in each diamicton. The similarity in the shapes of the clasts in both deposits is evident, as is the dominance of rectangular shapes. The macrofabrics described here were measured chiefly on rectangular clasts whose longest axis was 1.5 to 2 times longer than the intermediate axis. For a significant (but unrecorded) percentage of clasts, the intermediate and small axes do not differ greatly in size. The computer program and techniques used in analyzing macrofabrics are those described by Andrews and Shimizu (1966), Andrews and Smith (1970), and Andrews (1971). Fabric analysis was made at five sites on each of the ridges as shown in figures 3 and 5. On the unnamed ridge north of Niwot Ridge, clast orientation from the surface to a depth of at least 75 cm closely parallels slope direction, which reflects the influence of mass movement as the dominant orienting process. Nonslope-related preferred orientations that trend northwest (fig. 11; table 3) were obtained at depths of only 75-100 cm along the relatively flat crest of this ridge (surface slope there is generally less than 3°). At site II (fig. 11), however, nonslope-related fabrics were not encountered above a depth of 1.4 m, probably because of the slightly steeper slope at this location. Although the deeper fabrics are at variance Table 2.—Shapes of clasts in the diamictons on Niwot Ridge and the unnamed ridge Study No. of Rectan- Discoidal and site observations gular Block5' P(or) sheet Triangular Diamicton on Niwot Ridge C-l 100 56 15 27 2 0 C-2 100 76 0 23 0 1 C-3 too 74 7 19 0 0 C-4 100 59 5 33 1 2 C-5 100 50 25 25 0 0 Total 500 315 52 127 3 3 Percent of total 63 10 25 1 1 Diamicton on the unnamed ridge C-l 100 68 9 21 0 2 C-2 100 70 8 20 0 2 C-3 100 54 18 22 0 6 C-5 100 56 24 18 2 0 II 100 52 20 28 0 0 Total 500 300 79 109 2 10 Percent of total 60 16 22 0.4 212 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS, FRONT RANGE, COLORADO Table 3.—Summary of macrofabric data for the diamicton on the unnamed ridge [The deeper fabric listed for site II was measured between 140 and 165 cm. It was not possible to obtain a deeper macrofabric at site IV, because of the lack of clasts in unit B] No. of Resultant Preferred Difference Vector Circle of Precision Point of Mean Site observa- vector(°) orientation (°) PO-RV magnitude confidence parameter balance dip tions (RV)' (PO)1 2 o (percent)3 * n. K5 6 o‘ o Surface (0-25 cm) i 25 341 319(7 a) 22 67 19.5 3.19 -3 -2.36 ii 50 13 13(11 a) 0 83 9.2 5.81 -1 -1.02 in 49 358 45 (7 o) 47 65 14.8 2.88* 0 — IV 50 339 295 (7 a) 44 64 15.1 2.76* 14 +9.8 V 50 5 277 (6 a) 88 55 18.3 2.20* 0 -0.12 Deeper (75-100 cm) i 26 340 320 (7 a) 20 71 18.4 3.36 -5 ii 51 356 327 (8 a) 29 62 15.6 2.62* -8 -5.92 hi 50 343 320 (7 a) 23 59 16.9 2.41* -5 -3.46 V 50 354 302 (4 a) 52 56 17.9 2.25* 22 +13.9 1 Mean orientation. 2 Preferred orientations were obtained from fabric diagrams contoured according to Kamb (1959). The contour interval is E+lo where E and a are the mean and standard deviation of the number of orientation data points in a given area. Densities >E+3o are believed to represent statistically significant preferred orientations. The number of complete contour intervals generated in each diagram is given in parentheses. 3 Vector magnitude was calculated as a decimal <1 and converted to a percentage. Higher values indicate stronger preferred orientations. * Actually, an arc on the circle with a unit area=l. 8 A parameter of concentration of data. It refers to the center of mass of data on a circle, which is equivalent to s in linear statistics. This parameter is used here to determine whether the sample approximates a spherical-normal distribution, which is to say that K>3. Values <3 are indicated above with an asterisk. K increases as the spread in the distribution of data points (observations) about the mean vector decreases. 6 Low values for point of balance indicate the lack of a preferred direction of dip. Negative numbers indicate that the total of dip values for clasts inclined in a southerly direction is greater than the total of dip values for clasts inclined in a northerly direction, and vice versa for positive numbers. c Figure 11.—Plot of macrofabric at site II on the unnamed ridge where slope is approximately 12 percent toward 7°-10° west of south. Single-barb arrows, slope direction; double-barbs, preferred orientation of the fabric. A, Fabric measured between ground surface and a depth of 25 cm; B, fabric measured between depths of 75 and 100 cm; and C, fabric measured between depths of 140 and 150 cm. A slope fabric (fabric whose preferred orientation is coincident with direction of slope) persists to a depth >1 m (A, B). At a depth of 1.4 m (C), a preferred orientation appears that is at variance with existing slopes, but in agreement with the preferred orientation of the deeper fabrics of sites I, HI, and V. (See table 3.) The contour interval is la (standard deviation) with respect to E (the mean of the number of orientation data points in a given area) (Kamb, 1959). Densities greater than E + 3o are believed to represent statistically significant preferred orientations. The greater the number of contours, the better developed the fabric.SEDIMENTARY CHARACTERISTICS OF THE DIAMICTONS 13 with slope directions, they generally coincide with each other and are parallel with the probable direction of transport indicated by clast composition. The results obtained in fabric studies of the dia-micton on Niwot Ridge are much less definitive than those from the diamicton on the unnamed ridge. The study sites on Niwot Ridge are 100-250 m higher and are located on a relict patterned ground and on solifluction terraces. These land forms suggest that freeze-thaw and mass movement have disturbed the surface of the diamicton on Niwot Ridge more than they have the surface of the diamicton on the unnamed ridge. The fabrics of all five study sites on Niwot Ridge are dominated by the effects of slow mass movement and perhaps by the sorting responsible for the patterned ground. A slope component persists in the deepest fabrics (depth of nearly 2 m) even on nearly level sites (slope less than 5°). Slope component as used here refers to that peak in a multimodal circular distribution which is approximately alined with slope inclination. Sites II and V on Niwot Ridge contained a minor nonslope-related component. Although these components point toward the cirques at the heads of South St. Vrain Creek and North Boulder Creek respectively, they are too weakly developed to cite as evidence that the diamicton was transported from these localities. Sites III and IV, situated on slopes of 18° and 13° respectively, show nothing but pronounced slope fabrics at depths of 1.5 to 1.8 m. Although a nonslope-related preferred orientation was measured at a depth of 1 m at site I, it parallels the preferred orientation of clasts in a nearby stone polygon, and therefore is presumed to have been formed by the same processes. MICROFABRIC Thin sections were made of samples collected from the diamicton on the unnamed ridge at each level at each site where the macrofabric was measured. As in the macrofabric studies, the only azimuth recorded was that of the longest axis, but only fragments whose length was at least twice their width were measured. Each microfabric sample was measured twice, once with a petrographic microscope and once by projecting the 70 X 70 mm thin sections with a slide projector onto grid paper where grain orientations were measured with a protractor. Use of the petrographic microscope, although more time consuming, yields somewhat better results, presumably because smaller detrital fragments and more total fragments could be measured precisely. As shown in table 4, macrofabric and microfabric measured with the petrographic microscope compare favorably for most sites, although agreement is better at depth. SURFACE FEATURES OF QUARTZ GRAINS Quartz grains from the three groups of samples described in table 5 were examined with a scanning electron microscope. Fifteen quartz grains were examined from each sample. The samples were separated and cleaned according to procedures outlined by Krinsley and Takahashi (1964), procedures that were current during 1971 when this work was done. Photomicrographs were taken of grains at low magnification (X50-100) to document variations in shape and characteristics of grain edges. Then grain surfaces were scanned at high magnifications and, if they possessed distinctive markings, were photographed. The surface features on quartz grains from the diamictons and till (Group II and III samples) are more numerous and diverse than those on quartz grains from residuum (Group I samples). Moreover, they occur over a greater range of scale, being no less common at X2.500 to 5,000 than at X250 to 500, the usual range for most features on grains from residuum. The markings on quartz grains from residuum are so coarse that photomicrographs at greater than X500 generally show little more than a part of the pattern focused upon. Quartz grains from residuum tend to be more angular than quartz grains from till, and typically have very sharp edges. Many grains from till are also angular, but just as many are subangular and some are almost subrounded. None of the grains examined exhibited the roundness of the grains from littoral and eolian environments shown by Krinsley and Donahue (1968), Krinsley and Margolis (1969), and Margolis and Krinsley (1971), except one set from outwash sampled 7 km downstream from the lower limit of glaciation. The principal surface feature most common in samples from residuum is the cuspate pattern (fig. 12A, B). Almost as common are the arcuate steps that in places closely parallel the form of the cusps. Neither feature is restricted to a given deposit type (fig. 14A, B), but both are relatively more abundant on grains from residuum than on grains from the diamictons and till, because of the absence of other features that abound on grains from the diamictons and till. Parallel ridge and step patterns occur on grains from all of the deposit types of table 5, but they tend to14 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS, FRONT RANGE, COLORADO Table 4.—Comparison of mean vector and vector magnitude for the macrofabrics (MA) and microfabrics (MI) of the diamicton on the unnamed ridge No. of Vector Vector Differences between MA Site Fabric observa- mean magnitude and MI vector means tions o (percent) n Depth 0-25 cm l MA 25 341 67 29 MI 85 10 59 2 MA 50 13 83 7 MI 74 6 72 4 MA 50 339 65 36 MI 80 15 61 5 MA 50 5 55 10 MI 85 355 69 Depth 95-110 cm i MA 26 340 71 7 MI 50 347 61 2 MA 50 6 64 2 MI 60 4 61 5 MA 50 354 56 21 MI 50 15 59 Depth 145-165 cm 2 MA 51 356 62 MI 134 4 63 8 be much more abundant on grains from the diamictons and till. Also, the parallel ridges and steps on grains from the diamictons and till show much more variation in scale, step width and height, and regularity of form (fig. 13). The use of the terms step or ridge depends on the attitude of the quartz grain. In one orientation, the pattern resembles a series of vertical risers and horizontal treads; in another orientation, it resembles the dip slopes of a series of hogbacks. This pattern and the arcuate steps shown in figure 14 are so common on quartz grains from glacial environments (Krinsley and others, 1964; Krinsley and Donahue, 1968; Krinsley and Margolis, 1969; Margolis and Kennett, 1971; Coch and Krinsley, 1971; Krinsley and Doornkamp, 1973; Kennett and Brunner, 1973; Blank and Margolis, 1975) that they have been termed “glacial”steps (Ingersoll, 1974). However, as noted by Setlow and Karpovich (1972), Brown (1973), and Ingersoll (1974), these features are not unique to glacial deposits. The similarity of the grain in figure 12C to those in figure 14 is anomalous. The quartz grain of figure 12C is from residuum, but its sample site is within 20-30 m of the outer limit of glacial deposits of Bull Lake age. It may therefore have been washed or blown from the nearby till. If the grain is not of glacial origin and the surface texture was formed within the residuum, the process that produced it is infrequent in residuum. Figure 14C illustrates the three dominant characteristics of surface textures of quartz grains from till, characteristics that are also dominant on grains from the diamicton on Niwot Ridge (figs. 14A, B, D). These characteristics are(l) an abundance of arcuate and parallel step or ridge patterns, (2) occurrence of surface textures at a variety of scales, and (3) surface textures in more than one orientation. Figure 14A exhibits patterns of at least three different sizes, the largest of which can be easily overlooked at this magnification (X5,000). When parallel or arcuate steps were found on grains from residuum, they were at this largest scale. At magnifications of X5,000, most grains from residuum appear to be featureless. Patterns with several ridges or steps per 1-2 pm (micrometers) were observed only on specimens from the diamictons and till.POSSIBLE ORIGINS FOR THE DIAMICTONS 15 Table 5.—Surface features on quartz grains from the four types of deposits investigated with the scanning electron microscope [All samples are from the Ward V/i quadrangle (Gable and Madole, 1976) and adjoining Gold Hill 7V2' quadrangle] Group Deposit type Sample localities Principal surface features of quartz grains IA Residuum Uplands underlain mostly by deeply weathered crystalline rocks well below timberline and east of the glacial limit where mass movement is slight to moderate (figs. 12A-C). IB Residuum Alpine settings comparable to those of the diamic-tons, where mass movement by solifluction and creep is moderate to great (fig. 12D). II Diamictons Niwot Ridge and the unnamed ridge (figs. 13A; UA, B, D; 15A, B). Magnifications of X 1,000-5,000: low relief; flat, relatively featureless surfaces dominate. Magnifications of X 200-500: angular grain edges, medium relief, cuspate patterns closely paralleled in places by arcuate steps, precipitated silica in hollows; abundant flat featureless surfaces; crystal overgrowths were observed in one sample. Magnifications of X 1,000-5,000: low relief, extensive areas of extremely flat, clean, featureless surfaces dominate. Magnifications of X 200-500: very angular, sharp grain edges, medium relief, conchoidal fractures, layering (probably edges of cleavage plates, Krinsley and Doornkamp, 1973), and smooth surfaces are common. Magnifications of X 200-5,000: angular to subangular grain edges, high relief, abundant arc-shaped steps and parallel steps that vary widely in scale, occasional striations(?). Ill Till Moraines in the upper valleys of South St. Vrain Creek, North Boulder Creek, and James Creek (figs. 13 B-D, 14C). Magnifications of X 200-5,500: angular to subangular grain edges, high relief, abundant arc-shaped steps, parallel steps, conchoidal fractures that vary widely in size and orientation. Some grains from both the diamictons and till show features that might be grooves, or striations (fig. 15). Variation in orientation of these linear features suggests origin by abrasion. POSSIBLE ORIGINS FOR THE DIAMICTONS The diamictons on Niwot Ridge and the unnamed ridge to the north are very poorly sorted and contain large boulders of exotic rock types in a fine-grained matrix. Stratification, if present, is so crude that it is not visible in small exposures (1-2 m across). These characteristics are evident in four categories of deposits, all of which are common to this region: (1) periglacial mass wasting deposits produced by cryo-turbation, solifluction, and creep: (2) landslide deposits produced primarily by flow as in rockfall or rockslide avalanches and debris flows; (3) glacial deposits; and (4) alluvial-colluvial deposits, aggregations of alluvium, colluvium, and debris flow deposits in variable amounts. In the following discussion, the origin of the diamictons on Niwot Ridge and the unnamed ridge will be examined in terms of these four types of deposits. PERIGLACIAL MASS WASTING DEPOSITS The study area abounds with features produced by cryoturbation, frost creep, and solifluction. These features, including both relict and active forms, are particularly abundant on Niwot Ridge (figs. 2, 16), where they have been described in detail by Benedict (1970). Hence, transport by the combined action of periglacial processes was considered as a possible origin for the diamictons. This origin, however, proved to be untenable, and the features so produced are regarded simply as an overprint on deposits that were already there. The occurrence of sediment containing abundant clasts mainly of Proterozoic rocks on a monzonite stock of Tertiary age is difficult to explain in this case by downslope transport by creep and solifluction, because the nearest summits are composed of the Tertiary monzonite. Monzonite rock rubble mantles the ridges west of both diamictons for distances of 0.5 km and more (fig. 16); yet, few clasts of monzonite are evident in either diamicton. The preponderance of Proterozoic Y Silver Plume Quartz Monzonite in the diamicton on the unnamed ridge indicates that the source of this sediment lay beyond the limits of the monzonite stock, 1-3 km to the northwest (fig. 1). Selective transport of exotic clasts from a distant source in preference to those from the nearest summits is inconsistent with an origin by slow mass movement. Fabric data also suggest that an origin by creep and solifluction is not reasonable. Macrofabric study at four sites on the diamicton on the unnamed ridge (figs. 5, 11; table 2) shows that clasts have long axes with a northwest-southeast preferred orientation. This does not conform to existing slope directions (figs. 1, 5) butFigure 12.—Scanning electron micrographs showing quartz-grain surface textures typical of Group I samples./!, B, Grains from residuum just below the limit of till, Brainard Lake Road, South St. Vrain drainage basin. C, Grain from residuum derived from Silver Plume Quartz Monzonite at junction of Brainard Lake Road and Colorado Highway 119. D, Grain from residuum at composition-study site C-6 on Niwot Ridge (fig. 3). Grains from residuum are angular and typically have sharp edges. The most common surface features are cuspate patterns (c) and arcuate steps (S), both of which are probably caused by conchoidal fracturing. Layers (L), both fine and coarse, are probably the edges of cleavage plates, as defined by Krinsley and Doornkamp (1973, p. 8). POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS. FRONT RANGE. COLORADOPOSSIBLE ORIGINS FOR THE DIAMIOTOXS 17 Figure 13.—Scanning-electron micrographs showing parallel ridge and step patterns. Whether or not of the same origin, these patterns are more common on grains from sample groups II and III than on grains from residuum. .4. Grain from the diamicton on Niwot Ridge. B, C, D, Grains from till collected 8 m below moraine surface in an excavation about 0.(1 km east of Silver Lake, near North Boulder Creek. Sharp, parallel ridges (R) occur frequently on grain surfaces or sides. These probably represent the trace or upturned edges of cleavage plates (Krinsley and Doornkamp, 1973).Figure 14.—Scanning electron micrographs. A, B, C. Grains from the diamicton on Niwot Ridge: c, cuspate pattern. I). Grain from till collected 8 m below moraine surface in an excavation about 0.6 km east of Silver Lake. Xorth Boulder Creek drainage basin. All of these grains are similar in that they contain an abundance of arcuate, parallel step or ridge patterns of different sizes and orientations. POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS. FRONT RANGE, COLORADOPOSSIBLE ORIGINS FOR THE DIAMICTONS 19 Figure 15.—Scanning electron micrographs of two grains from the diamicton on Niwot Ridge showing linear depressions. A, Depressions (d) are probably part of the pattern created by upturned cleavage plates (ridges). B, Variations in the orientation of linear grooves (denoted by arrows and not to be confused with the scanning artifacts perpendicular to the top and bottom of view) suggest the possibility of origin by abrasion. does corroborate evidence provided by the composition of the deposit, which indicates that the deposit was transported from an area to the northwest. Sites II and V on Niwot Ridge also possess nonslope-related components, although much less strongly developed. Their significance, however, is open to question because of the degree to which postdepositional mass movement has disturbed the deposit on Niwot Ridge. As shown in figure 8 and table 1, the diamictons on Niwot Ridge and the unnamed ridge have many more boulders than do other surficial deposits in the area located at comparable altitudes. Boulder counts made on residuum, most of which is undergoing slow mass movement, show that (1) boulders longer than 75 cm are rare except around rock knobs and (2) boulder size does not vary significantly between the different rock types of the area. The large (2-3 m) boulders in the diamictons (fig. 7) are mainly Proterozoic biotite gneiss, and to a lesser extent, Proterozoic quartz monzonite; yet, residuum formed from these same rock types on eastern Niwot Ridge does not contain numerous large boulders. The rapid decline in numbers of large boulders away from the few rock knobs that crop out along the ridge suggests that large boulders do not move far from their source on slopes of less than 15°. Therefore, I suggest that the large boulders in the diamictons on Niwot Ridge and the unnamed ridge to the north accumulated at the base of peaks and steep valley sides near the Continental Divide, and later were transported to their present locations by some process other than slow mass movement. Figure 10 shows that the clasts in the diamictons are more rounded than those in residuum even though the rock types are the same in both units. The greater rounding of the clasts in the diamicton supports the interpretation that they were transported by some means other than slow mass movement. The fact that the diamicton on the unnamed ridge underlies and overlies a unit of very fine sand and silt along its northeast edge, unit B of figure 6, demonstrates that the diamicton and unit B are contemporaneous. The shape, texture, and sorting of unit B seem inexplicable by any form of slow mass movement in a periglacial environment. LANDSLIDE DEPOSITS Landsliding could account for the composition of the diamictons and the abundance of large boulders.20 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS, FRONT RANGE, COLORADO Navajo Peak Arikaree Glacier Isabelle Glacier Figure 16.—Oblique aerial view to west showing the diamicton on Niwot Ridge(Td) overlying Tertiary monzonite (Ta). Monzonite extends for about 0.5 km west of the diamicton to the contact with Proterozoic biotite gneiss (Xg). The diamicton on Niwot Ridge, although almost surrounded by rocks of the stock, contains only a small percentage of clasts from the stock. (See figs. 1,3.) Patterned ground, noted in the discussion of macrofabrics, is visible over most of the diamicton surface. (National Center for Atmospheric Research photo.) However, mass flow capable of moving this volume of debris for distances of 3-4 km over relatively low gradients is limited to rock avalanches and debris flows. ROCKFALL AND ROCKSLIDE AVALANCHES A theory of origin by rockfall or rockslide avalanching has several weaknesses: (1) an exceptionallyPOSSIBLE ORIGINS FOR THE DIAMICTONS 21 low coefficient of friction would have been required for so long a slide on such a low gradient; (2) this type of landslide tends to produce angular brecciated material, which is not the kind of material described here; (3) this type of landslide tends to occur in incompetent, layered, deformed rocks that occupy structural attitudes favorable to sliding, whereas the study area is underlain by competent, coarse crystalline, foliate to massive rocks; (4) large landslides are uncommon in this part of the Front Range; and (5) diamictons similar to those on Niwot Ridge and the unnamed ridge occur on the Continental Divide itself. The diamicton on Niwot Ridge was at least 2 km long. The west end of what remains of the diamicton is only 300 m lower than the highest parts of the Continental Divide to the west. The vertical head and gradient requirements for moving this volume of debris 3-4 km horizontally eliminates most forms of “dry” landsliding except for rockfall or rockslide avalanches. A thin cushion of compressed air beneath the slide as described by Shreve (1968) for the Black-hawk, Elm, and Frank landslides would be required to account for so long a slide with so little drop. Even if the gradient were doubled by assuming that 300 m of relief has been lost due to erosional lowering of the slide source area, the maximum coefficient of friction (Shreve, 1968) would amount to only 0.23, a value that would still require a cushion of compressed air to explain the slide. Rockfall and rockslide avalanches produce breccias that are texturally different from the diamictons on Niwot Ridge and the unnamed ridge. The material in rock avalanches is shattered by fall but then undergoes little additional movement; consequently, little abrasion or rounding occurs during transport. Shreve (1968) cited a “jigsaw puzzle” effect, a condition where blocks which had shattered on impact remained undispersed during sliding, as evidence for transportation on a cushion of compressed air. Transport of this type would not account for the grain-size distributions and clast roundness observed in the diamictons, nor the unit of very fine sand and silt (unit B, fig. 6) associated with the deposit on the unnamed ridge. All of the large landslides described by Shreve (1968) occurred in incompetent, layered rocks that had been structurally deformed and had structural attitudes favorable to sliding. Three slides involved undercut thrust blocks, two occurred on dip slopes, and one was produced by quarrying. The geologic setting of the diamictons of this paper contrasts markedly with that of these six landslides. The rocks are coarse crystalline, foliate to massive, and very competent. Landslides are uncommon within the crystalline core of the northern Front Range except where the mineral belt, a northeast-trending Precambrian structure characterized by massive fracturing and broad shear zones (Tweto and Sims, 1963), intersects the Williams Range thrust fault and related structures on the northeast side of the thrust (Madole and others, 1974; Robinson and others, 1974). North of the mineral belt a few landslides do occur where Pleistocene glaciation oversteepened valley walls and where glacial till was plastered on very steep slopes, but these are comparatively small. Lastly, diamictons exist in saddles on or near the Continental Divide at Pawnee Pass, between Pawnee Peak and Mount Toll, and between Kiowa Peak and Mount Albion (figs. 1, 2). The physical similarity of these diamictons to those on Niwot Ridge and the unnamed ridge suggests a common origin. Two of the diamictons are on the Continental Divide itself, which, if they are due to landsliding, limits their potential source areas to a few relatively low nearby summits. DEBRIS FLOWS Debris flow is used here as a general term for debris that flows as a viscous fluid or slurry, a suspension of solids in a liquid. The debris may be of any size or include a broad range of sizes. Mudflows, for example, are a type of debris flow. The occurrence of large flows oftheSlumgullion type(Endlich, 1876; Howe, 1909) or smaller ones like those along the east flank of the Front Range (Madole and others, 1973) require incompetent rocks that fail when undercut by erosion or are wetted excessively. At Slumgullion, hydrothermal alteration produced a weak, easily deformed unit beneath a section of massive, competent, volcanic rock. Along the east flank of the Front Range, mass failures have resulted where silty-clay residuum or weak, steeply dipping shales, some containing swelling clays, have been saturated by water from adjacent aquifers. Similar conditions are absent in the crystalline core of the Front Range where massive, resistant rocks produce coarse residuum of which 50-75 percent of the less-than-2 mm fraction is sand, and commonly less than 10 percent is clay. Small-scale debris flows do, however, occur commonly on talus in the heads of many Front Range valleys. Curry (1966) described flows of this type in the Tenmile Range 60 km southwest of Niwot Ridge. The numerous large boulders on the diamictons suggest that debris flows may have contributed sediment to these deposits. This suggestion is based on the fact that small debris flows do occur in the area and that debris flows have been a source of large boulders22 POSSIBLE ORIGINS OF TILL-LIKE DEPOSITS, FRONT RANGE, COLORADO in alluvial fans and valley floor alluvium in many places in the canyons of the Front Range and in the piedmont slope deposits along the mountain front. Yet, direct evidence of debris flows in the form of levees or concentrations of cobbles and boulders outlining the traces of former levees or lobes were not found on either diamicton. Unfortunately, exposures of the internal character of the diamictons do not exist, and the 1- and 2-m-deep fabric-study pits did not reveal much. Consequently, the role of debris flow activity in forming these diamictons is a matter of speculation. It is considered improbable that the diamictons are primarily debris flows, but probable that debris flows contributed some part of the diamictons. GLACIAL TRANSPORT Most properties of the diamictons on Niwot Ridge and the unnamed ridge to the north are consistent with a glacial origin. Their ridgetop locations are not unusual if the transporting agent was glacier ice, nor is the small amount of Tertiary rock in the diamictons unusual. Till composition at a given point can be out of phase with bedrock. For example, where till overlies the Tertiary stock, it is chiefly Proterozoic rock debris derived from farther west; yet where it overlies Silver Plume Quartz Monzonite 5 km east of the stock, it is dominated by rock types from the stock. Hence, what would be a compositional anomaly for slow mass movement is not anomalous for glacial transport. The diamictons on Niwot Ridge and the unnamed ridge resemble till and are clearly different from nearby residuum in terms of the size and abundance of boulders present, sorting, and clast roundness (figs. 8-10). The difference in roundness between the clasts in the diamictons and those in till (fig. 10) are attributed to differences in distance of transport, the till having been transported twice as far as the diamictons. As shown in figure 17, the graphic mean of grain size plotted against inclusive standard deviation (Folk and Ward, 1957) for theless-than-2 mm fraction of the diamictons on Niwot Ridge and the unnamed ridge produces a distribution of points similar to that plotted for till. However, the data plotted for the diamictons also overlap the distributions plotted for alluvial fan and mudflow deposits by Landim and Frakes (1968). The fans and mudflows were derived from different rock types than the diamictons of this paper and in different weathering environments. Data from them was included only to reinforce the point that poor sorting does not necessarily discriminate between alluvial and glacial deposits. < > LU O a cc < o _ z cn < b tel o X Q_ < CC O LU > to D _J O z -e* & A A A A „A °°#e ° f* -A ,Vaa$ £-* ____. A EXPLANATION TILL © Pinedale and Bull Lake equivalents o Pre-Bull Lake till DIAMICTONS T Unnamed ridge A Niwot Ridge ALLUVIAL FANS □ Mudflow, California A Alluvial, California GRAPHIC MEAN (

< 2 _i 3 3 O 1 - 2400 2400 HOURS (M.S.T.) Figure 9. Mass precipitation curves for four weather stations, May 16-19, 1978.PRECIPITATION DISTRIBUTION 13 112° 110° 108° 106° EXPLANATION 2 -------- Line of equal precipitation (isohyet) Interval 1 inch Figure 10. Total storm precipitation, May 16-19, 1978.14 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. and 1- and 24-hour values from Miller and others (1973). Considering the scarcity of actual rainfall observations in this region, the maximum point value probably was not recorded. Therefore, the greatest observed rainfall is assumed to represent the average depth over an appreciable area, rather than the maximum point rainfall. A common assumption is that the maximum station rainfall represents an average depth over 10 mi2. In practice, precipitation amounts for past significant storms were tabulated for durations of 6, 12, 18, 24, 48, and 72 hours. The May 16-19, 1978, storm actually lasted about 60 hours. Therefore, the maximum 72-hour precipitation over 10 mi2 was considered conservatively to be 7.60 in. For comparison, 5.50 in. is the greatest observed 10-mi2 72-hour precipitation for the month of May in a section enclosing Lame Deer, Mont., bounded by latitude 44°N. and 49°N., and by longitude 105°W. and 110°W. (United States-Canada boundary). The precipitation for the May 16-19, 1978, storm established a record for May. However, when all months are considered, the rank of this storm is third greatest. The historical file used as a basis for comparison consists of extreme areal storm-rainfall depths that have been determined by the U.S. Army, Corps of Engineers, and other Government agency field offices (U.S. Army, Corps of Engineers, updated annually since 1945). The stratification by duration and geographical area used in this comparison is from the National Weather Service, Hydrometeorological Branch (1979). GENERAL DESCRIPTION OF FLOODS The area affected by the May 1978 floods in Montana and Wyoming is shown in figure 1. Major drainages in Montana where flooding occurred include the Yellowstone River and its major tributaries the Bighorn River, Tongue River, and Powder River. Drainages affected in Wyoming include these three tributaries of the Yellowstone River as well as the Belle Fourche River, Cheyenne River, and North Platte River. Peaks in the North Platte River drainage generally resulted from the first rain on May 16 or the early morning of May 17, whereas peaks in the more northerly basins were caused by the later rains. Streams throughout the area generally were flowing near or at bankfull stage before the May 16-19 precipitation because of greater-than-average precipitation and snowmelt runoff during early May. The high antecedent flows, generally saturated ground conditions, and stockwater reservoirs already at or near capacity contributed to the record and near-record floodflows that occurred. The precipitation at the higher elevations was snowfall (Burgess Junction, in the Big Horn Mountains in Wyoming, reported 27 in.), which delayed runoff of some of the mountain streams. These streams peaked several days later when warm temperatures melted the snow. Flooding would have been much more severe if all the precipitation had been rainfall. Peak discharges and peak stages were determined at 164 selected sites. At 30 of the sites, peak discharges were determined by indirect methods after the flood-waters receded. The remaining sites were either active or discontinued streamflow-gaging stations where stage-discharge relationships already were available. In all instances, trained personnel from the U.S. Geological Survey were dispatched to collect stage data, measure streamflow where possible, and obtain onsite survey data required for the indirect discharge measurements. Sites where data were collected and peak discharges determined are shown in figure 1. The peak discharges and stages are given in table 3 (at end of report). The numbers in the first column of table 3 correspond to the site numbers shown in figure 1. For convenience, site numbers are used throughout this report. The permanent station number is the number of the streamflow-gaging-station used in the annual data reports of the Geological Survey. The sites are numbered consecutively in downstream order. Sites on tributaries are listed between sites on the main stream in the order in which those tributaries enter the main stream. Sites on tributaries entering upstream from all main-stream sites are listed before the first main-stream site. FLOOD MAGNITUDE Peak discharges at about one-third of the streamflow-gaging stations were the largest since the stations were established. A comparison of May 1978 flood discharges with the greatest known flood discharges in the area can be made from figure 11, which relates discharge, in cubic feet per second per square mile, to corresponding drainage area. Enveloping curve A, defined by the largest known flood discharges, and enveloping curve B, defined by the May 1978 flood discharges, indicate that the May 1978 peak flows generally were about 50 percent less than the maximum known peak flows for drainage areas greater than 100 mi2. For drainages smaller than 100 mi2, the May 1978 peak discharges were about 50-80 percent less than the maximum known peak discharges. The gradual flattening of curve B for drainage areas less than 100 mi2 indicates thatFLOOD FREQUENCY 15 DRAINAGE AREA, IN SQUARE MILES Figure 11. Comparison of May 1978 peak discharges with maximum known flood peaks. smaller streams in the area did not flood appreciably, and that record flooding on the larger streams was not the result of peak-flow contributions from some small tributaries. Rather, all tributaries appeared to be contributing to a gradual buildup of flow that culminated in large discharges on the larger streams. FLOOD FREQUENCY Information on the magnitude and frequency of flooding is necessary for the adequate design of flood-plain structures and for making management decisions about flood-plain land use. In this report the frequency of flooding is expressed as the percentage chance of exceeding a specified flood magnitude during any 1-year period. Thus, a 2-percent-chance flood has 2 chances in 100 of being exceeded during any 1-year period. The occurrence of floods is assumed to be random in time; no schedule or regularity of occurrence is implied. The occurrence of a 2-percent-chance flood is no guarantee, therefore, that a similar-size flood will not occur next week or next year. For time periods longer than 1 year, the risks of experiencing large floods increase in a nonadditive fashion. For example, the risk of exceeding a 1-percent-chance flood one or more times during a 30-year period is 25 percent and during a 70-year period is 50 percent. The frequency of flooding was derived from a statistical analysis of annual peak flows at the gaging stations in the flood area. The method generally used to determine the flood-flow frequencies is described by the U.S. Water Resources Council (1977). At gaging sites in Montana having short flood records (less than 10 years), flood frequencies were determined from a re-16 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. gional flood-frequency study by the U.S. Geological Survey (Johnson and Omang, 1975). Flood-frequency information was not developed for sites on streams materially affected by regulation or diversion, or for Wyoming stream sites where the record length was less than 10 years. RESERVOIRS In Montana, the only major storage reservoirs located in the flood area are Bighorn Lake, which is formed behind Yellowtail Dam on the Bighorn River, and the Tongue River Reservoir on the Tongue River. On the Bighorn River, peak flows and stages were reduced substantially as a result of reservoir flood-control operations. Thus, although the peak inflow to Bighorn Lake was 27,000 ft3/s on May 18, the release to the river downstream from the dam was held to 1,220 ft3/s on May 20-21 (U.S. Bureau of Reclamation, 1979). The U.S. Bureau of Reclamation also estimated that peak discharge of the Bighorn River at Bighorn, Mont, (site 39), was reduced by about 25,000 ft3/s; for the Yellowstone River at Miles City (site 72) the peak discharge was reduced about 22,000 ft3/s and the peak stage was reduced 2 ft as a result of operation of Bighorn Lake. The reduction in stage at the Bighorn River site (site 39) could not be determined because of unknown backwater effects at higher flows. A summary of stage and contents for Bighorn Lake during May-June 1978 is presented in table 4. Curves of reservoir inflow, outflow, and storage contents through early June are shown in figure 12. Although the Tongue River Reservoir is not operated as a flood-control structure, reservoir storage significantly reduced the peak discharge of the Tongue River, from 17,500 ft3/s at the Montana-Wyoming State line (site 53) to 10,800 ft3/s at Tongue River Dam (site 56). Nevertheless, high flows at the dam seriously damaged the reservoir outlet structure and spillway. Although daily reservoir stages are not available, a composite hy-drograph showing discharge at State line and at Tongue River Dam is shown in figure 13. In Wyoming, the only major reservoir affected by large-scale flooding was Keyhole Reservoir on the Belle Fourche River. This reservoir spilled for the first time in its 26-year history and reached a record storage level on May 22, 1978. The peak outflow (combined spill and release) recorded on May 23 also was a new maximum of record. As is indicated by the curves of inflow, outflow, and storage contents in figure 14, the peak discharge of the Belle Fourche River was reduced by about 14,000 ft3/s as a result of the storage in Keyhole Reservoir. The reduction in stage was not determined. Table 4.—Summary of stage and contents for Bighorn Lake near St. Xavier, Mont. [Station 06286400; time 2400 hours, m.s.t. Maximum reservoir inflow, 27,000 cubic feet per second, May 18. Maximum reservoir contents, 1,236,700 acre-feet, July 13. Records furnished by U.S. Bureau of Reclamation] May 1978 June 1978 Day Elevation above NGVD of 1929 (feet) Contents (acre-feet) Change in storage (acre-feet) Elevation above NGVD of 1929 (feet) Contents Contents (acre-feet) Change in storage (acre-feet) I 3,608.45 828,500 3,640.07 1,116,900 - 500 2 3,609.54 836,000 ♦ 7,500 3,639.82 1,113,700 -3,200 3 3,610.41 841,500 ♦ 5,500 3,639.55 1,110,400 -3,300 4 3,611.08 845,400 ♦ 3,900 3,639.20 1,105,000 -5,400 5 3,611.84 850,000 ♦ 4,600 3,638.95 1,102,800 -2,200 6 3,612.94 857,500 ♦ 7,500 3,638.41 1,096,200 -6,600 7 3,613.90 865,200 ♦ 7,700 3,638.30 1,094,900 -1,300 8 3,614.76 873,400 ♦ 8,200 3,638.27 1,094,500 - 400 9 3,615.34 878,700 ♦ 5,300 3,638.20 1,093,700 - 800 10 3,615.84 883,100 + 4,400 3,638.52 1,097,600 ♦3,900 II 3,616.35 887,400 ♦ 4,300 3,638.98 1,103,200 ♦5,600 12 3,616.74 890,600 ♦ 3,200 3,639.07 1,104,300 +1,100 13 3,617.23 894,400 ♦ 3,800 3,639.05 1,104,100 - 200 14 3,617.73 898,200 ♦ 3,800 3,639.04 1,104,000 - 100 15 3,618.10 901,000 ♦ 2,800 3,639.56 1,110,500 ♦6,500 16 3,618.73 905,600 ♦ 4,600 3,640.27 1,119,500 ♦9,000 17 3,619.88 914,000 + 8,400 3,640.74 1,125,600 ♦6,100 18 3,624.17 949,900 +35,900 3,641.12 1,130,500 ♦4,900 19 3,628.93 993,300 ♦43,400 3,641.27 1,132,500 ♦2,000 20 3,632.79 1,032,300 ♦39,000 3,641.43 1,134,600 ♦2,100 21 3,634.54 1,051,300 ♦19,000 3,641.50 1,135,500 ♦ 900 22 3,635.81 1,065,500 ♦14,200 3,641.50 1,135,500 0 23 3,636.92 1,078,400 ♦12,900 3,641.70 1,138,200 ♦2,700 24 3,637.92 1,090,300 ♦11,900 3,641.86 1,140,300 ♦2,100 25 3,638.75 1,100,400 ♦10,100 3,642.10 1,143,500 ♦3,200 26 3,639.40 1,108,500 ♦ 8,100 3,642.20 1,144,900 ♦1,400 27 3,639.71 1,112,400 ♦ 3,900 3,642.15 1,144,200 - 700 28 3,639.85 1,114,100 ♦ 1,700 3,642.19 1,144,700 ♦ 500 29 3,640.00 1,116,000 ♦ 1,900 3,642.55 1,149,600 ♦4,900 30 3,640.09 1,117,200 ♦ 1,200 3,643.11 1,157,200 ♦7,600 31 3,640.11 1,117,400 ♦ 200 — — MAJOR RIVER BASINS YELLOWSTONE RIVER BASIN Record flooding occurred on several streams tributary to the Yellowstone River. Of the small tributaries, flooding was severe on Pryor Creek and Fly Creek near Billings, Mont. The Bighorn River, a major tributary, flooded extensively as did its major tributaries. Flooding was minor on the small Yellowstone River tributaries downstream from the mouth of the Bighorn River. Record flooding occurred on the Tongue River and its tributaries upstream from Tongue River Reservoir, but little overbank flooding occurred downstream from the Tongue River Reservoir. Significant flooding also occurred along upstream reaches of the Powder River and its tributaries, but little flooding occurred at the mouth. YELLOWSTONE RIVER Although the peak flood discharge of the Yellowstone River at Miles City, Mont, (site 72), was the greatestINFLOW AND OUTFLOW, IN THOUSANDS DISCHARGE, IN THOUSANDS OF CUBIC FEET PER SECOND OF CUBIC FEET PER SECOND MAJOR RIVER BASINS 17 1200 1100 1000 900 800 Figure 12. Inflow, outflow, and storage contents of Bighorn Lake, Mont. Data from U.S. Bureau of Reclamation. Figure 13. Hydrographs of discharge of the Tongue River near Decker, Mont., May 17-23, 1978. at that site since records began in 1922, flood damage generally was minor. High flood stages due to ice jamming are not unusual on the Yellowstone River and have caused considerably more damage than the May 1978 flood. No appreciable flooding occurred on the Yellowstone River downstream from Miles City, Mont., or upstream from the mouth of Pryor Creek near Billings, Mont. A flood hydrograph of the Yellowstone River at Miles City, Mont., is shown in figure 15. PRYOR CREEK Flooding was severe along Pryor Creek (sites 1, 4, 5, and 6), a small tributary of the Yellowstone River just downstream from Billings, Mont. Several State and county highway bridges were washed out along the Pryor Creek road, and substantial agricultural and residential property damage occurred on farms and ranches. A Burlington Northern Railroad bridge was washed out at the mouth of Pryor Creek, and the Big Horn Canal near Huntley was extensively damaged by Pryor Creek floodwaters. The only reported death resulting from the May 1978 flood occurred on Pryor Creek near Pryor when the victim left a flood-stranded STORAGE, IN THOUSANDS OF ACRE-FEET18 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. MAY JUNE Figure 14. Inflow, outflow, and storage contents of Keyhole Reservoir, Wyo., May 15-June 5, 1978. automobile and was evidently washed away by the current. Extensive urban property damage occurred near the town of Huntley (fig. 16). The peak discharge at the old gaging station, Pryor Creek near Billings (site 4), was more than four times that of the previous flow of record. The peak discharge at the upstream Pryor Creek gaging station (site 1) also was more than four times the maximum discharge previously known. At both sites the May 1978 flood exceeded the 1-percent-chance flood discharge. FLY CREEK Fly Creek is another small (drainage area less than 300 mi2) tributary of the Yellowstone River that flooded during May 1978. Residential property was in- undated in and near the small community of Pompeys Pillar, and substantial agricultural flood damage occurred upstream from Pompeys Pillar. The peak discharge for May 1978 (site 7) was almost 4 times the previously known peak discharge and was greater than the 1-percent-chance flood. BIGHORN RIVER Flooding was widespread and severe throughout the Bighorn River basin, with some of the largest unit flows and greatest flood damages occurring on the Bighorn River tributaries of Soap Creek (site 26), Beauvais Creek (site 28), Rotten Grass Creek (site 27), and the Little Bighorn River (sites 32 and 35). Flooding on the Bighorn River was severe upstream from Yel-MAJOR RIVER BASINS 19 Figure 15. Hydrograph of discharge of the Yellowstone River at Miles City, Mont, (site 72), May 18-24, 1978. lowtail Dam1 (fig. 17) where the tributaries Fifteen Mile Creek (site 13), and Nowood River (site 15), contributed record flood discharges to the main stem. The May 1978 peak discharge on Fifteen Mile Creek was about a 1- percent-chance flood. A hydrograph of discharge for the Norwood River is shown in figure 18. Flow on the main stem downstream from Yellowtail Dam was completely contained only as far downstream as the mouth of Soap Creek. Extreme runoff from Soap Creek, Rotten Grass Creek, Beauvais Creek, and the Little Bighorn River caused record flooding on the Bighorn River from St. Xavier to the mouth of the Bighorn River near Bighorn, Mont. The peak discharge of the Bighorn River at Bighorn (site 39) was more than twice the previous maximum of record and exceeded the 1-percent flood discharge. Agricultural flood damage was extensive along the Bighorn River (fig. 19), and numerous irrigation structures were destroyed. Residential flood damage occurred at scattered locations along the main stem, particularly near St. Xavier and Hardin, Mont. A flood hydrograph of the Bighorn River at Bighorn is shown in figure 20. Soap Creek, Beauvais Creek, and Rotten Grass Creek Flooding was severe on Soap Creek, Beauvais Creek, and Rotten Grass Creek, three relatively small (less than 150 mi2 drainage area) tributaries of the Bighorn River. Peak discharges during the May 1978 flood exceeded the 1-percent flood on all three streams and also greatly exceeded the previous peak of record on all three streams. Development along these streams is sparse, and residential property damage consequently was limited. Agricultural damage was extensive along all three streams, however, and severe channel erosion occurred on Beauvais Creek. Little Bighorn River and Tributaries Extensive flooding occurred on the Little Bighorn River from Pass Creek downstream to its confluence with the Bighorn River near Hardin, Mont. Upstream from Pass Creek, no flooding occurred on the Little Bighorn River main stem. Flooding was minor on smaller tributaries of the Little Bighorn River, as evidenced by the relatively small peak discharges of the Little Bighorn River tributary near Wyola, Mont, (site 31), and Long Otter Creek near Lodge Grass, Mont, (site 34). On Pass Creek near Wyola, Mont, (site 30), however, the May 1978 peak discharge was almost five times the previous peak flow of record. Residential property in Wyola was flooded, and several bridges were washed out upstream from Wyola. The May 1978 peak flow exceeded the 1-percent-chance flood. Lodge Grass Creek also flooded extensively. The small community of Lodge Grass, Mont., in particular, suffered severe residential and commerical damage (fig. 21). Flood damage upstream from the town was generally limited to agricultural range, cropland, roads, and bridges. At the only discharge- determination site (site 33) on Lodge Grass Creek, the May 1978 peak discharge was about 10 percent less than the largest known peak discharge. At this site, about 17 mi upstream from Lodge Grass, the May 1978 flood was about a 2- percent-chance flood. At Lodge Grass the magnitude of the May 1978 flood was probably greater than a 2-percent-chance flood, because the urban damage was reported to be the greatest since at least 1900 (Hardin Herald, 1978). The Little Bighorn River caused extensive flood damage from the mouth of Pass Creek downstream to the confluence with the Bighorn River near Hardin. Substantial urban property damage occurred in and near the small community of Crow Agency (fig. 22). The 1-90 highway interchange near Crow Agency was severely damaged. The Burlington Northern Railroad 'Confines the water of Bighorn Lake20 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. Figure 16. Flooding along U.S. Highway 312 near Huntley, Mont., from Pryor Creek overflow, May 19, 1978. View is westward. Photograph by U.S. Bureau of Reclamation. also suffered extensive track damage from Wyola to Hardin. The May 1978 peak discharge at the gaging station downstream from Pass Creek (site 32) was more than twice the highest previously known. Downstream near Hardin (site 35), the May 1978 peak discharge of the Little Bighorn River was more than four times the highest previously known flood discharge. At both sites, the May 1978 peak was greater than the 1-per-cent-chance flood. Flood hydrographs for both Little Bighorn River gaging stations are shown in figure 23. ROSEBUD CREEK Minor flooding occurred on Rosebud Creek near its mouth and damage was slight. No flooding occurred upstream from the gage site near Colstrip, Mont, (site 44). The May 1978 flood on Rosebud Creek was greater than a 1- percent-chance flood at the mouth (site 45) but was only a 15-percent-chance flood near Colstrip. TONGUE RIVER AND TRIBUTARIES Extensive flooding occurred on the Tongue River and its larger tributaries upstream from the Tongue River Reservoir. Flooding was minor or nonexistent on the upper Tongue River stations near Dayton, Wyo. (sites 46 and 47), but record flooding occurred near the Wyoming-Montana border (site 53). However, flood damage was minor along the main stem of the river because of sparse development. Overbank flooding was minor on the Tongue River downstream from the Tongue River Reservoir. Tributaries downstream from the reservoir did not flood appreciably.MAJOR RIVER BASINS 21 Figure 17. Flooded mobile home along the east bank of the Bighorn River near Manderson, Wyo., May 19, 1978. Upstream from the reservoir, Goose Creek (site 50) and Prairie Dog Creek (site 52) flooded extensively and were the largest contributors to the record Tongue River flows at the State line. Smaller tributaries did not flood significantly anywhere along the Tongue River. The May 1978 peak discharge on the Tongue River at the State line site was more than twice the maximum previously known. This peak flow exceeded the 1-percent-chance flood. The May 1978 peak flow on Goose Creek was near the maximum peak flow previously known and was about a 3-percent-chance flood. A flood hydrograph for Goose Creek is shown in figure 24. The Prairie Dog Creek flood peak was more than five times greater than the previously known maximum and was about a 1-percent-chance flood. POWDER RIVER AND TRIBUTARIES Flooding within the Powder River basin generally was limited to the main stem Powder River and its larger tributaries. Overbank flooding was probably most severe on the Powder River from Sussex, Wyo. (site 89), to Broadus, Mont, (site 103). Some urban property flood damage occurred at Broadus, and agricultural damage occurred throughout the reach. From Broadus to Locate, Mont, (site 116), the May 1978 peak22 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. MAY Figure 18. Hydrograph of discharge of the Nowood River near Tensleep, Wyo. (site 15), May 16-21, 1978. flow was reduced from 30,000 to 27,400 ft3/s by channel and valley storage, with a corresponding decrease in flooding. The May 1978 peak discharge on the Powder River exceeded the previous maximum for the period of record at Moorhead, Mont, (site 101), and at Broadus, Mont., but probably was not as great as the 1923 flood. At both sites the May 1978 peak was about a 3-percent-chance flood. At the other Powder River main-stem stations (sites 81, 89, 92, and 116), peak flows ranged from about a 4- to a 7-percent-chance flood. Powder River tributaries that flooded significantly were the South Fork Powder River (site 82) and Salt Creek (site 88) in Wyoming, and the Little Powder River in both Montana and Wyoming. Damage along these streams was relatively minor because of sparse development. Peak discharges on the South Fork Powder River during May 1978 ranged from a 20-percent-chance flood (site 83) to about a 1-percent-chance flood (site 82). The peak flow of Little Powder River near Broadus (site 112) was equivalent to that of a 2-per-cent-chance flood. A flood hydrograph for the Little Powder River above Dry Creek in Wyoming (site 109) is shown in figure 25. CHEYENNE RIVER BASIN CHEYENNE RIVER Flooding in the Cheyenne River basin was extensive and record floods occurred on the Cheyenne River and several of its tributaries. In the upper reaches of the Cheyenne River, Antelope Creek (site 118) and Dry Fork Cheyenne River (site 119) contributed substantially to the extensive flooding of the Cheyenne River near Dull Center, Wyo. (site 120). Flow records at these sites are unavailable prior to 1976. However, floodmarks and information furnished by local residents indicate that larger flows have occurred in the past. Farther downstream, record or near-record floods on Black Thunder Creek and Lance Creek caused extensive agricultural damage. Considerable road and bridge damage also took place, particularly on Black Thunder Creek. A road washout on Lance Creek that resulted from a heavy load of debris in the floodwaters is dramatically illustrated in figure 26. The peak discharge on Black Thunder Creek (site 122) was more than six times the largest discharge during the 6-year period on record. The peak discharge on Lance Creek (site 126), a 4-percent-chance flood, was slightly less than the largest discharge previously known. A flood hydrograph for Lance Creek is shown in figure 27. The first peak on the hydrograph resulted from the intense but more isolated rain on May 16 that fell in the headwater area near Orin, Wyo. The May 16 storm in this area caused the extreme flow of Sand Creek near Orin (note plotting of site 161 on fig. 11), which inundated and closed Interstate Highway 25 for a short time. The main stem of the Cheyenne River also flooded extensively downstream from the mouth of Lance Creek and caused considerable agricultural and road damage (fig. 28). At the gaging station near Riverview, Wyo. (site 127), the May 1978 peak discharge of the Cheyenne River was almost twice the maximum flood previously known and was greater than the 1-percent-chance flood. Downstream from Riverview the peak discharge of the Cheyenne River attenuated as far as the confluence of Beaver Creek, where large inflow was again supplied. Thus, at the gaging site near Edgemont, S. Dak. (site 130), the peak discharge of the Cheyenne River was about the same as at site 127. The May 1978 peak discharge near Edgemont was more than twice the highest peak previously known and was about a 1-percent-chance flood. BELLE FOURCHE RIVER Severe flooding occurred on the Belle Fourche River and some of its larger tributaries. Agricultural damageMAJOR RIVER BASINS 23 Figure 19. Flooded farmsteads on the left bank of the Bighorn River, 2 mi northeast of Hardin, Mont., May 19, 1978. View is northwestward. Photograph by U.S. Bureau of Reclamation. Figure 20. Hydrograph of discharge of the Bighorn River at Bighorn, Mont, (site 39), May 17-22, 1978. was substantial along the entire main stem in Wyoming. Record flood levels were reached at all gaging stations (sites 131 and 132, near Piney; site 136, below Moorcroft; and site 137, below Keyhole Reservoir). Some unusual road-culvert damage caused by the large flows of the upper Belle Fourche River is shown in figure 29. Tributary streams where high flows were recorded and agricultural damage occurred include Caballo Creek (site 133) and Donkey Creek (site 135). A flood hydrograph for Donkey Creek near Moorcroft, Wyo. (site 135), is shown in figure 30. The May 1978 peak discharges on the Belle Fourche River near Piney, Wyo. (sites 131 and 132), were greatly affected by impounded water released when an earthen dam washed out upstream. On the Belle Fourche River below Moorcroft, Wyo. (site 136), the 1978 peak discharge was more than three times the previous maximum discharge during the period of record and was the greatest since the flood in 1908. The24 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. Figure 21. Flooding at Lodge Grass, Mont., May 19, 1978. Lodge Grass is situated at the mouth of Lodge Grass Creek at the Little Bighorn River. View is southeastward. Photograph by U.S. Bureau of Reclamation.MAJOR RIVER BASINS 25 Figure 22. Flooding of the Little Bighorn River in the town of Crow Agency, Mont., at the Interstate Highway 1-94 interchange, May 19, 1978. View is northward. Photograph by U.S. Bureau of Reclamation.26 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. Figure 23. Hydrographs of discharge of the Little Bighorn River, May 17-22, 1978. Figure 24. Hydrograph of discharge of Goose Creek below Sheridan, Wyo. (site 50), May 17-22, 1978. Figure 25. Hydrograph of discharge of the Little Powder River above Dry Creek near Weston, Wyo. (site 109), May 17-22, 1978. May 1978 peak exceeded the 1-percent-chance flood at site 136. PLATTE RIVER BASIN MEDICINE BOW RIVER Severe flooding occurred on the Little Medicine Bow River near Medicine Bow, Wyo. (site 141). Agricultural damage was substantial, but little structural damage occurred because of sparse development. The flood flow from the Little Medicine Bow River contributed heavily to flooding on the Medicine Bow River. Upstream from Seminoe Reservoir (site 142), the May 1978 peak was about a 3-percent-chance flood. A discharge hydrograph for the Medicine Bow River is shown in figure 31. NORTH PLATTE RIVER The North Platte River basin has many reservoirs, and the manipulation of storage and releases during the May 1978 flood reduced the flood potential from the major tributaries. The flood peak on Deer Creek, at Glenrock, Wyo. (site 151), was a 3-percent chance flood; the peak on Box Elder Creek, at Box Elder, Wyo. (site 155), was a 3-percent-chance flood; and that on Sand Creek, near Orin, Wyo. (site 161), was a 5-percent-chance flood.FLOOD DAMAGE 27 Figure 26. Flooding of Lance Creek near Bright, Wyo., May 19, 1978. The force of debris and water would have destroyed the bridge had the water not breached the road. The May 1978 peak on the main stem of the North Platte River in Wyoming was well below the record flow of 1965 near Glenrock (site 154) and at Orin (site 163). Glendo Reservoir, just downstream from Orin, remained well below the maximum storage level. Downstream from the reservoir, the flow in the North Platte River was about normal for May. FLOOD DAMAGE One life was lost as a direct result of the May 1978 flooding, and damage to roads, bridges, railroads, irrigation structures, cropland, homes, and businesses was severe. On May 29, President Carter declared the flooded areas of Montana and Wyoming major disaster areas, thereby qualifying the areas for various Federal funds for relief and recovery efforts. In Montana, the initial disaster declaration affected the counties of Big Horn, Powder River, Rosebud, Treasure, and Yellowstone. In Wyoming, the affected counties were Big Horn, Campbell, Converse, Crook, Hot Springs, Johnson, Park, Natrona, Niobrara, Sheridan, Washakee, and Weston. Carbon and Stillwater Counties in Montana were subsequently added to the list of disaster-affected counties, but estimated damages in the two counties were considerably less than in the other flood-damaged counties. Estimates of flood damage were compiled by various State and Federal agencies and were made available by the Federal Disaster Assistance Administration (Dave Grier, written commun., 1978), the U.S. Agricultural Stabilization and Conservation Service (James Eggen, oral commun., 1979), and the Wyoming Disaster and Civil Defense Agency (1978). Total estimated damages for May 1978 are listed in table 5.DISCHARGE, IN CUBIC FEET PER SECOND 28 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. Figure 27. Hydrograph of discharge of Lance Creek near Riverview, Wyo. (site 126), May 17-22, 1978. Agricultural losses were much greater than either private- or public- facility losses in both Montana and Wyoming (table 5). The estimates for crop loss included such items as field washout of newly planted crops and sediment deposition in fields. The livestock loss figure was large; many newborn lambs and calves perished from the flooding and cold weather, and herds of cattle in Wyoming drowned in the rapidly rising water in some steep-sided river valleys. Miscellaneous agricultural damage included the cost of fence replacement; removal of debris from fields; and grading, shaping, and repair of private irrigation facilities. In the public-damage category, severe road and bridge damage occurred in both States. In Montana, numerous public irrigation facilities also were washed out or severely damaged. SEDIMENTATION MONTANA Sedimentation, which includes erosion, deposition, and other physical processes, was unusually large in Table 5.—Summary of flood damage [Data from the Federal Disaster Assistance Administration, the U.S. Agricultural Stabilization and Conservation Service, and the Wyoming Disaster and Civil Defense Agency] Type of damage Montana Wyoming Total Private damage: J 2,850,000 t 2,500,000 $ 5,350,000 Residences 2,500,000 2,000,000 4,500,000 Businesses 350,000 500,000 850,000 Agricultural damage: 10,915,300 12,320,000 23,235,300 Buildings and equipment 3,025,000 190,000 3,215,000 Crop loss 2,630,300 4,800,000 7,430,300 Livestock loss 2,062,000 4,460,000 6,522,000 Miscellaneous 3,193,000 2,870,000 6,068,000 Public damage: 3,798,400 1,500,200 5,298,600 Road systems 1,418,400 1,266.600 2,685,000 Public utilities 89,500 85,100 174,600 Debris removal 28,750 48,600 77,350 Water-control facilities Parks and recreational 1,572,000 32,500 1,604,500 facilities 194,250 6,800 201,050 Other public damage 495,500 60,600 556,100 Total damage 17,563,700 16,320,200 33,883,900 both Montana and Wyoming as a result of the flooding of May 1978. In comparing sediment data for three Montana stations on the Powder River, suspended-sediment concentration and suspended-sediment discharge obviously decreased as the peak flows moved downstream. The inability of the channel to contain the flood flow forced the water out onto the flood plain, where decreased velocities caused a settling of sediment. At all stations the maximum concentration preceded the maximum sediment discharge. Maximum daily suspended-sediment discharges as listed in table 6 exceeded the previous recorded maximum at all stations. However, only the Powder River at Moorhead had a mean daily sediment concentration that exceeded any previously recorded values; that concentration was 41,000 mg/L (milligrams per liter). Sediment movement in the Tongue River was considerably less than that in the Powder River, partly because the Tongue River Reservoir moderated flows and trapped much of the sediment from upstream sources. For the Tongue River in Montana, maximum mean daily suspended-sediment concentration was 5,900 mg/ L and suspended-sediment discharge was 84,400 ton/d at Miles City (site 71) on May 18. The short period of record does not justify historical comparisons. WYOMING Precipitation from storms of April 26-30 and May 2-8 provided saturated soil conditions favorable to flooding and erosion. Subsequent intense rains May 16-19 produced the stream flooding and large increases in sediment discharge. The contribution to sediment loads wasSEDIMENTATION 29 Figure 28. Bridge on the Cheyenne River near Riverview, Wyo., May 25, 1978. View from the right bank shows approach to bridge com pletely washed out. Washout probably occurred late May 19 or early May 20, 1978.30 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. Figure 29. Flood damage along the Belle Fourche River below Rattlesnake Creek near Piney, Wyo. (site 131), May 19, 1978. Upstream ends of culverts were bent upward, one more than 90°. Flow over the road beginning at left side of photograph and flow through culverts caused extensive erosion on the downstream side of the road. from enlargement of gullies, headcutting (see fig. 32), sloughing of river banks, and degrading of the stream channels. Large suspended-sediment concentrations and suspended-sediment discharge were prevalent in most streams. For example, a new maximum daily suspended-sediment discharge for the period of record, April 1946 to September 1957, October 1967 to September 1971, and January 1975 to May 1978, was measured at Powder River at Arvada, Wyo. (site 92). The suspended-sediment discharge on May 20, 1978, was 2,810,000 tons transported by a mean daily discharge of 22,600 ft3/s with a mean daily concentration of 46,000 mg/L. The previous maximum at this site was 2,340,000 tons on May 24, 1952. Another example of large quantities of sediment was the suspended-sediment discharge of 460,000 tons on May 20, 1978, at Bighorn River near Kane, Wyo. (site 18). This sediment discharge was obtained from the suspended-sediment transport curve (Colby, 1956) of figure 33. The mean daily discharge on this date was 17,900 ft3/s. The maximum suspended-sediment discharge at this site on June 25, 1946, was 972,000 tons, computed from mean daily values of concentration and flow. The period of record at this site is March 1946 to September 1964 and December 1969 to May 1978. Sediment data collected during the flood period in both Montana and Wyoming are summarized in table 7 (at end of report).DISCHARGE, IN CUBIC FEET PER SECOND SEDIMENTATION 31 Figure 30. Hydrograph of discharge of Donkey Creek near Moor-croft, Wyo. (site 135), May 17-22, 1978. Figure 31. Hydrograph of discharge for the Medicine Bow River above Seminoe Reservoir near Hanna, Wyo. (site 142), May 17-22, 1978. Figure 32. Headcutting near the mouth of Black Thunder Creek, near Hampshire, Wyo. (site 122), May 19, 1978.32 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. Table 6.—Daily suspended-sediment discharge for the Powder River in Montana Maximum Site Date suspended-sediment discharge (tons) At Moorhead (site 101) May 20, 1978 2,230,000 At Broadus (site 103) May 21, 1978 1,570,000 Near Locate (site 116) May 22, 1978 739,000 AERIAL PHOTOGRAPHY Aerial photographs were taken at or near the crest of the flood on several streams in Montana. The black-and-white photographs taken by the Montana Department of Highways are useful in identifying inundated areas. The areas flown and the photography numbers and scales are listed in table 8. The approximate location of the flight lines is shown in figure 34. The photographs are on file in the U.S. Geological Survey district office, Helena, Mont. FLOOD-HYDROGRAPH DATA Gage heights and discharges at selected times during the flood at streamflow-gaging stations are given in table 9 (at end of report). All continuous-record stations where the 1978 peak flow was at least that of a 10- percent-chance flood are included. The period included begins before the start of the major rise of the streams and extends to an arbitrary cutoff point when the discharge approached that of the antecedent flow. The time intervals used to identify stage and discharge data in table 9 provide sufficient detail to adequately define the flood hydrograph. SUMMARY Intense rains and some snow, produced by imbedded convective cells associated with a cold front, occurred over southeastern Montana and northeastern Wyoming May 16-19, 1978. Precipitation on previously saturated ground caused widespread flooding in the Yellowstone, Cheyenne, Belle Fourche, and North Platte River drainages. Maximum measured rainfall was 7.60 in. within 72 hours at Lame Deer, Mont. The storm established a precipitation record for that area for May, but ranks third when all months are considered. Figure 33. Suspended-sediment transport curve of the Bighorn River near Kane, Wyo. (site 18), October 1969 to September 1978. Peak discharges were determined at 164 selected sites in the area. Peak discharges at 48 of these sites exceeded the maximum peak discharges previously known and equaled or exceeded the 1-percent-chance flood at 24 sites. Peak flows and stages on several rivers were substantially reduced by large reservoirs in the area. Peak discharge of the Yellowstone River at Miles City, Mont., was reduced by about 22,000 ft3/s as a result of storage in Big Horn Lake. Keyhole Reservoir in Wyoming reached a record storage level and record peak outflow as a result of the storm. The storage capacity of the reservoir reduced the peak discharge by about 14,000 ft3/s in the reach below the dam. Flood damage was extensive, exceeding $33 million in the two States. Nineteen counties were declared major disaster areas. Daily suspended-sediment discharges were particularly large in the Powder River basin and exceeded previously recorded maximum values at four sites. The maximum daily suspended-sediment discharge was 2,810,000 tons on May 20 for the Powder River near Arvada, Wyo.SUMMARY 33 Table 8.—Aerial photography of the May 1978 flood in Montana [Photography by Montana Department of Highways] Stream Flight line number Location Photograph number Date in May Scale Yellowstone River 1 Pompeys Pillar Bridge 352-10 to 12 19 1:10,000 2 Hysham to Bighorn River FLT 1:353-77 to 91 20 1:12,000 3 Hyshara to Bighorn River FLT 2:353-92 to 100 20 1:12,000 Blue Creek 4 Mouth to Basin Creek 352-194 to 200 19 1:10,000 Pryor Creek 5 U.S. Highway 87 to Huntley FLT 1:352-150 to 169 19 1:9,600 6 U.S. Highway 87 to Huntley FLT 2:352-170 to 180 19 1:9,600 7 Huntley area FLT 1:352-181 to 189 19 1:9,600 8 Huntley area FLT 2:352-190 to 193 19 1:9,600 Fly Creek 9 Pompeys Pillar area 352-1 to 9 19 1:10,000 Bighorn River 10 Mouth to Bighorn County 353-101 to 104 20 1:12,000 11 North Hardin area FLT 1:352-14 to 17 19 1:10,000 12 North Hardin area FLT 2:352-18 to 27 19 1:10,000 Little Bighorn 13 Mouth to Crow Agency FLT 1:352-127 to 134 19 1:15,000 14 Mouth to Crow Agency FLT 2:352-135 to 139 19 1:16,000 15 Mouth to Crow Agency FLT 3:352-140 to 149 19 1:16,000 16 Crow Agency area 352-28 to 43 19 1:10,000 17 Crow Agency to Wyola 352-44 to 89 19 1:10,000 Pass Creek 18 Wyola to State line 352-90 to 100 19 1:10,000 Tongue River 19 Tongue River Reservoir to State line FLT 1:352-101 to 111 19 1:12,000 20 Tongue River Reservoir to State line FLT 2:352-113 to 126 19 1:12,000 21 Decker to Ashland FLT 1:353-1 to 12 20 1:12,000 22 Decker to Ashland FLT 2:353-13 to 29 20 1:12,000 23 Decker to Ashland FLT 3:353-30 to 38 20 1:12,000 24 Decker to Ashland FLT 4:353-39 to 41 20 1:12,000 25 Decker to Ashland FLT 5:353-42 to 76 20 1:12,00034 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO. 108° 107° 106° EXPLANATION 0 Flight line—Number corresponds to Table 8 0 10 10 20 20 T 30 30 MILES -n-1 40 KILOMETERS Figure 34. Location of flight lines along streams where aerial photographs were obtained at or near crest of flood, May 19-20, 1978.REFERENCES 35 REFERENCES Colby, B. R., 1956, Relationship of sediment discharge to streamflow: U.S. Geological Survey open-file report, 170 p. Hardin Herald, 1978, Flood is century’s worst disaster: Hardin, Mont., v. 71, no. 21, May 25, p. 1. Johnson, M. V., and Omang, R. J., 1976, A method for estimating magnitude and frequency of floods in Montana: U.S. Geological Survey Open- File Report 76-650, 35 p. Lott, G. A., 1976, Precipitable water over the United States, vol. 1, Monthly means: National Weather Service, NOAA Technical Report NWS 20, 173 p. Miller, J. F., 1964, Two- to ten-day precipitation for return periods of 2 to 100 years in the contiguous United States: U.S. Weather Bureau Technical Paper 49, 29 p. Miller, J. F., Frederick, R. H., and Tracy, R. J., 1973, Precipitation-frequency atlas of the western United States, vol. 1— Montana: National Weather Service, NOAA Atlas 2, 41 p. National Weather Service, Hydrometeorological Branch, 1979, Notes as an extension of NOAA Technical Memorandum NWS HYDRO 33: Unpublished note on file at the Silver Spring, Md., office of the National Weather Service. Omang, R. J., and Hull, J. A., 1978, Annual peak discharges from small drainage areas in Montana through September 1977: U.S. Geological Survey Open-File Report 78-219, 204 p. Riedel, J. T., and Ho, F. P., 1979, Precipitable water over the United States, vol. 2, Semi-monthly maxima: National Weather Service, NOAA Technical Report NWS 20, 359 p. U.S. Army, Corps of Engineers, updated annually since 1945, Storm rainfall in the United States, Depth-area-duration data. U.S. Bureau of Reclamation, 1979, Report on operations of Bighorn Lake during 1978: Unpublished data on file in Billings, Montana, office, 52 p. U.S. Environmental Science Services Administration, 1968, Weather atlas of the United States (original title: Climatic atlas of the United States): U.S. Department of Commerce, reprinted 1975, 262 p. U.S. Water Resources Council, 1977, Guidelines for determining flood flow frequency: Washington, D.C., Bulletin 17A, 26 p. Wyoming Disaster and Civil Defense Agency, 1978, Conditions resulting in the north central and eastern Wyoming flood disaster: Cheyenne, Wyoming Disaster and Civil Defense Agency, 89 p.TABLES 3, 7, AND 9Table 3.—Summary offlood stages and discharges [mi2, square miles; ft, feet; ft3/s, cubic feet per second] Maximum flood previously known Maximum flood of May 1978 Site number (fig. 1) Permanent station number Site of flood-discharge determination Drainage area (mi2) Datum of gage above NGVD of 1929 (ft) Period of record Date Gage height (ft) Discharge (ft3/s) Day Gage height (ft) Discharge (ft3/s) Percent chance of exceedance3 i 06216000 Pryor Creek at Pryor, Mont. 117 b3,900 1921-24; 1966-78 6-26-69 6.13 468 19 8.88 2,280 50 10 06265600 Tie Down Gulch near Worland, Wyo. 1.78 — 1961-78 8-31-63 8.62 328 19 6.11 114 33 11 06267260 North Prong East Fork Nowater Creek near Worland, Wyo. 3.77 1964-78 9-18-67 5.47 394 18 5.29 332 11 12 06267400 East Fork Nowater Creek near Colter, Wyo. 149 c4,165 1971-78 7-06-75 3.68 1,270 18 6.65 3,040 (h) 13 06268500 Fifteenmile Creek near Worland, Wyo. 518 c4,070 1951-78 5-22-52 i5.77 3,300 18 10.58 4,270 1 14 06268600 Bighorn River at 10 ,810 4,035.78 1965-69 6-23-67 13.69 15,900 19 14.45 17,500 (h) Worland, Wyo. CO ZD TABLESTable 3.—Summary of flood stages and discharges—Continued © Maximum flood previously known Maximum flood of May 1978 Site number (fig- 1) Permanent station number Site of flood-discharge determination Drainage area (mi2) Datum of gage above NGVD of 1929 (ft) Period of record Date Gage height (ft) Discharge (ft3/s) Day Gage height (ft) Discharge (ft3/s) Percent chance of exceedance3 15 06270000 Nowood River near Tensleep, Wyo. 803 c4,420 1938-43; 1950-55; 1972-78 6-16-55 i12.30 3,330 19 12.94 3,380 5 16 06274250 Elk Creek near Basin, Wyo 96.9 — 1959-78 6-06-67 10.91 4,260 19 9.30 2,450 14 17 06279090 Shell Creek near Greybull Wyo. , 560 — 1951; 1965-78 — — — 19 7.82 2,150 — 18 06279500 Bighorn River near Kane, Wyo. 15,765 c3,660 1928-78 6-16-35 ill.10 25,200 20 9.89 20,700 14 19 06282000 Shoshone River below Buffalo Bill Reservoir, Wyo. 1,538 c4,900 1921-78 5-28-28 i10.62 14,700 19 — f 1,230 — 20 06284200 Shoshone River at Willwood, Wyo. 1,980 c4,300 1974-78 6-20-74 10.43 12,100 19 7.89 5,000 (f) 21 06284400 Shoshone River near Garland, Wyo. 2,036 4,073.67 1958-78 7-01-67 is.76 13,300 19 7.50 4,550 50 22 06284500 Bitter Creek near Garland, Wyo. 80.5 c4,080 1950-53; 1957-60; 1968-78 7-04-75 4.74 1,230 17 3.04 552 >50 23 06284800 Whistle Creek near Garland, Wyo. 101 c4,150 1958-60; 1968-78 7-03-75 12.44 4,780 18 7.47 2,340 7 24 06285100 Shoshone River near Love11, Wyo. 2,350 c3,850 1966-78 7-01-67 6.49 13,400 18 6.25 7,680 50 25 06285400 Sage Creek at Sidon Canal near Deaver, Wyo. 341 c4,020 1958-60; 1968-78 6-08-58 9.22 2,250 19 5.32 518 33 26 06287500 Soap Creek near St. Xavier, Mont. 98.3 c3,250 1911-12; 1913; 1939-53; 1963; 1967-72 4-28-63 14.96 4,170 19 16.95 7,810 <1 27 06288000 Rotten Grass Creek near St. Xavier, Mont. 147 c3,150 1913-19; 1919-22; 1967-72 2-28-72 9.16 900 19 13.60 9,740 <1 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO.Table 3.—Summary of flood stages and discharges—Continued Maximum flood previously known Maximum flood of May 1978 Site number (fig- 1) Permanent station number Site of flood-discharge determination Drainage area (mi2) Datum of gage above NGVD of 1929 (ft) Period of record Date Gage height (ft) Discharge (ft3/s) Day Gage height (ft) Discharge (ft3/s) Percent chance of exceedance3 28 06288200 Beauvais Creek near St. Xavier, Mont. 100 c3,350 1967-77 6-09-68 8.00 1,600 19 9.54 8,580 50 37 06294600 Tullock Creek tributary near Hardin, Mont. 8.63 — 1973-78 3-03-75 3.38 171 18 1.67 60 33 38 06294690 Tullock Creek near Bighorn, Mont. 446 c2,770 1974-78 3-02-76 7.40 1,960 18 6.39 1,220 25 39 06294700 Bighorn River at 22 Bighorn, Mont. ,885 c2,690 1945-78 6-24-47 8.79 26,200 20 14.15 59,200 <1 40 06294930 Sarpy Creek tributary near Colstrip, Mont. 4.44 — 1972-78 1972 4.33 194 18 4.77 488 <1 41 06294940 Sarpy Creek near Hysham, Mont. 453 c2,680 1973-78 3-04-75 12.43 428 21 11.63 372 >50 FABLESTable 3.—Summary of flood stages and discharges—Continued K> Maximum flood Permanent Drainage Datum of Period previously known Maximum flood of May 1978 number (fig. 1) station number Site of flood-discharge determination area (mi2) gage above NGVD of 1929 (ft) of record Date Gage height (ft) Discharge (ft3/s) Day Gage height (ft) Discharge (ft^/s) Percent chance oJ exceedance3 42 06294985 East Fork Arraells Creek tributary near Cols trip, Mont. 1.87 — 1973-78 1-21-75 2.72 50 18 3.59 5 >50 43 06294995 Armells Creek near Forsyth, Mont. 370 c2,560 1974-78 1-21-75 4.80 k500 20 4.91 711 46 44 06295250 Rosebud Creek near Cols trip, Mont. 799 c3,000 1974-78 5-17-75 6.92 406 21 9.02 605 20 45 06296003 Rosebud Creek at mouth, near Rosebud, Mont. 1,302 2,480 1974-78 2-26-75 5.78 kl,200 19 6.78 2,620 <1 46 06297480 Tongue River at Tongue River Campground near Dayton, Wyo. 202 4,210 1974-78 5-10-77 4.30 k2,750 18 3.29 651 (f) 47 06298000 Tongue River near Dayton, Wyo. 204 4,060 1918-29; 1940-78 6-03-44 6.45 3,400 18 3.38 649 >50 48 06299900 Slater Creek near Monarch, Wyo. 18.0 — 1967-78 6-15-67 61.30 1,700 18 59.97 kl,100 11 49 — Jackson Creek near Big Horn, Wyo. 7.44 — — — — — 18 — 810 — 50 06305500 Goose Creek below Sheridan, Wyo. 392 3,701.36 1941-78 6-16-63 7.82 5,450 18 8.33 5,430 3 51 06306100 Squirrel Creek near Decker, Mont. 33.6 3,680 1975-78 May 1975 2.33 12 18 7.27 584 4 52 06306250 Prairie Dog Creek near Acme, Wyo. 358 3,450 1970-78 3-05-75 6.01 738 19 12.60 3,940 1 53 06306300 Tongue River at State line, near Decker, Mont. 1,477 3,429.14 1960-78 6-15-67 10.86 7,480 19 14.25 17,500 <1 54 06306900 Spring Creek near Decker, Mont. 34.7 — 1958-78 2-14-71 6.50 1,400 18 2.79 225 33 55 06306950 Leaf Rock Creek near Kirby, Mont. 6.14 — 1958-78 6-15-63 6.77 222 19 .94 24 >50 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO.Table 3.—Summary of flood stages and discharges—Continued Maximum flood Site Permanent Drainage Datum of Period previously known Maximum flood of May 1978 number station Site of flood- area gage above of (fig- 1) number discharge determination (mi2) NGVD of 1929 record Percent (ft) Gage Date height (ft) Discharge (ft3/S) Day Gage height (ft) Discharge (ft3/s) chance of exceedance3 56 06307500 Tongue River at Tongue River Dam, near Decker, Mont. 1,770 3,344.40 1939-78 6-15-67 8.20 7,340 20 20.00 10,800 57 06307520 Canyon Creek near Birney, Mont. 50.2 — 1972-78 6-14-76 2.28 182 18 .93 20 >50 58 06307600 Hanging Woman Creek near Birney, Mont. 470 3,150 1973-78 3-04-75 9.77 986 19 11.56 2,060 11 59 06307620 Tie Creek near Birney, Mont • 18.7 — 1973-78 3-03-75 2.36 9 19 1.40 7 >50 60 06307700 Cow Creek near Fort Howes ranger station, near Otter, Mont. 8.37 — 1972-78 1972 2.39 43 18 1.65 8 >50 61 06307720 Brian Creek near Ashland, Mont. 8.03 — 1973-78 3-01-75 3.75 93 19 1.94 25 50 62 06307740 Otter Creek near Ashland, Mont. 707 c2,920 1972-78 3-06-75 7.05 341 21 7.33 392 >50 63 06307780 Stebbins Creek at mouth, near Ashland, Mont. 19.9 — 1963-78 3-19-69 4.45 570 19 3.46 203 25 64 06307830 Tongue River below Brandenberg bridge, near Ashland, Mont. 4.062 c2,710 1973-78 6-18-67 — k5,740 22 9.96 8,340 10 65 06307930 Jack Creek near Volborg, Mont. 5.47 — 1973-78 5-05-75 4.56 271 18 5.62 448 6 66 06308100 Sixmile Creek tributary near Epsie, Mont. .24 — 1973-78 6-18-72 3.18 74 18 4.30 73 3 67 06308200 Basin Creek tributary near Volborg, Mont. .14 — 1955-78 7-02-58 6.96 390 18 1.31 16 >50 68 06308330 Deer Creek tributary near Volborg, Mont. 1.65 — 1973-78 1973 11.55 1,170 18 4.26 75 20 69 06308340 La Grange Creek near 3.66 — 1973-78 5-06-75 7.62 378 18 5.17 182 17 Volborg, Mont. 4^ CO TABLESTable 3.—Summary of flood stages and discharges—Continued 4^ 4^ Maximum flood previously known Maximum flood of May 1978 Site Permanent Drainage Datum of Period number station Site of flood- area gage above of (fig- 1) number discharge determination (mi2) NGVD of 1929 record Percent (ft) Gage Gage chance of Date height Discharge Day height Discharge exceed- (ft) (ft3/s) (ft) (ft3/s) ancea 70 06308400 Pumpkin Creek near Miles City, Mont. 697 c2,490 1972-78 5-06-75 12.27 2,890 19 11.13 2,390 40 71 06308500 Tongue River at 5 Miles City, Mont. ,379 2,375.76 1938-42; 1947-78 6-15-62 12.33 13,300 23 10.18 8,650 13 72 06309000 Yellowstone River at 48 Miles City, Mont. ,253 2,333.3 1922-23; 1928-78 6-19-44 12.74 96,300 22 16.50 102,300 <1 73 06309080 Deep Creek near Kinsey, Mont. 11.5 — 1962-78 6-09-72 16.78 2,430 18 4.70 400 >50 74 06309200 Middle Fork Powder River near Barnum, Wyo. 45.2 c7,220 1961-78 6-15-63 >■12.60 7,110 16 3.61 469 >50 75 06309260 Buffalo Creek above North Fork Buffalo Creek near Arminto, Wyo. 8.80 c7,660 1974-78 6-18-75 2.02 117 16 2.05 92 (h) 76 06309270 North Fork Buffalo Creek near Arminto, Wyo. 8.10 c7,720 1974-78 6-18-75 2.64 201 16 2.06 75 (h) 77 06309280 Buffalo Creek below North Fork Buffalo Creek near Arminto, Wyo. 18.6 c7,500 1974-78 6-18-75 2.16 295 16 1.91 149 (h) 78 06309450 Beaver Creek below Bayer Creek near Barnum, Wyo. 10.9 c7,030 1974-78 8-04-76 2.19 148 16 2.69 176 (h) 79 06309460 Beaver Creek above White Panther Ditch near Barnum, Wyo. 24.2 c5,350 1974-78 6-18-75 2.00 222 17 2.57 220 (h) 80 06311400 North Fork Powder River below Pass Creek near Mayoworth, Wyo. 100 c5,700 ml940-78 8-11-41 7.64 1,270 18 5.22 313 50 81 06312500 Powder River near Kaycee, Wyo. 980 4,533.76 1933-35; 1938-71 n8-ll-41 12.57 5,230 — 11.32 k4,200 4 82 06312700 South Fork Powder River near Powder River, Wyo. 262 — 1961-78 9-11-73 8.52 1,200 18 8.75 1,800 <1 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO.Table 3.—Summary of flood stages and discharges—Continued Maximum flood Site Permanent Drainage Datum of Period previously known Maximum flood of May 1978 number (fig. 1) station number Site of flood-discharge determination area (mi2) gage above NGVD of 1929 (ft) of record Date Gage height (ft) Discharge (ft3/s) Day Gage height (ft) Discharge (ft3/s) Percent chance of exceedance3 83 06313000 South Fork Powder River near Kaycee, Wyo. 1,150 c4,590 1911; 1938-40; 1950-69 5-22-62 14.43 35,500 18 i7.20 k8,200 20 84 06313020 Bobcat Creek near Edgerton, Wyo. 8.29 — 1965-78 9-11-73 4.62 1,060 18 1.88 64 >50 85 06313050 East Teapot Creek near Edgerton, Wyo. 5.44 — 1965-78 6-10-65 9.92 4,450 18 2.18 250 >50 86 06313100 Coal Draw near Midwest, Wyo. 11.4 — 1961-78 6-22-64 13.40 2,620 18 6.93 300 >50 87 06313180 Dugout Creek tributary near Midwest, Wyo. .8 c4,930 1965-78 7-15-67 9.10 1,590 18 2.93 160 >50 88 06313400 Salt Creek near Sussex, Wyo. 769 c4,480 1976-78 5-31-76 6.43 3,480 18 9.88 10,200 (hi 89 06313500 Powder River at Sussex, Wyo. 3,090 4,362.95 1938-40; 1950-57; 1977 5-23-52 i12.60 32,500 19 15.16 24,000 5 90 06313700 Dead Horse Creek near Buffalo, Wyo. 151 c3,970 1958-78 6-22-76 11.32 2,480 18 10.08 1,420 25 91 06316400 Crazy Woman Creek at upper station near Arvada, Wyo. 945 c3,765 1963-70; 1977 6-15-65 16.02 15,800 20 10.00 2,200 (h) 92 06317000 Powder River at Arvada, Wyo. 6,050 3,622.01 1919-78 9-29-23 i23.70 k100,000 20 16.9 k32,500 4 93 06318500 Clear Creek near Buffalo, Wyo. 120 5,184.83 1894; 1896-99; 1917-27; 1938-78 6-15-63 6.19 3,420 18 3.70 550 >50 94 06320200 Clear Creek below Rock Creek near Buffalo, Wyo. 322 c4,480 1971-78 5-30-71 6.28 2,060 18 6.00 1,620 (h) 95 06320400 Clear Creek at Ucross, Wyo. 409 c4,070 1976-78 5-11-77 7.46 1,280 19 9.07 1,740 (h) 4^ Cn TABLESTable 3.—Summary of flood stages and discharges—Continued Oi Maximum flood Site Permanent Drainage Datum of Period previously known Maximum flood of May 1978 number (fig. 1) station number Site of flood-discharge determination area (mi2) gage above NGVD of 1929 (ft) of record Date Gage height (ft) Discharge (ft2/s) Day Gage height (ft) Discharge (ft2/s) Percent chance of exceedance3 96 06321000 South Piney Creek near Story, Wyo. 69.4 c5,590 ±951-78 6-15-63 4.37 2,090 18 2.97 214 >50 97 06321100 South Piney Creek below Mead-Coffeen Ditch near Story, Wyo. 69.5 c5,520 1974-78 5-10-77 3.32 524 18 2.73 225 (h) 98 06321500 North Piney Creek near Story, Wyo. 36.8 c5,290 1951-78 6-15-63 5.04 1,820 18 3.04 459 >50 99 06323500 Piney Creek at Ucross, Wyo. 267 4,066.83 1917-23; 1950-78 6-16-63 7.33 3,570 19 5.30 1,260 33 100 06324000 Clear Creek near Arvada, Wyo. 1,110 3,506.51 1915-19; 1928-29; 1939-78 8-05-54 10.45 9,600 18 9.03 5,210 17 101 06324500 Powder River at Moorhead, Mont. 8,088 3,334.6 1929-72; 1974-78 P6-17-62 12.77 23,000 20 15.24 33,000 <1 102 06324700 Sand Creek near Broadus, Mont. 10.6 c3,090 1955-78 6-09-72 5.39 715 18 2.12 27 >50 103 06324710 Powder River at Broadus, Mont. 8,748 3,016.30 1975-78 P6-24-76 6.19 6,740 21 12.96 30,000 <1 104 06324800 Little Powder River tributary near Gillette, Wyo. .81 — 1960-78 6-22-64 96.44 176 18 7.97 33 17 105 06324890 Little Powder River below Corral Creek near Weston, Wyo. 204 c3,980 1977-78 — — — 18 9.61 2,410 (h) 106 06324900 Cedar Draw near Gillette, Wyo. 3.45 — 1959-78 6-22-64 9.75 758 18 6.87 230 25 107 06324910 Cow Creek tributary near Weston, Wyo. .72 — 1971-78 7-02-76 8.17 153 18 5.93 51 25 108 06324925 Little Powder River near Weston, Wyo. 540 c3,680 1977-78 — — — 19 13.32 4,460 (h) MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO.Table 3.—Summary of flood stages and discharges—Continued Maximum flood Site Permanent Drainage Datum of Period previously known Maximum flood of May 1978 number (fig. 1) station number Site of flood- area discharge determination (rai^) gage above NGVD of 1929 (ft) of record Date Gage height (ft) Discharge (ft3/s) Day Gage height (ft) Discharge (ft3/s) Percent chance o] exceedance3 109 06324970 Little Powder River above Dry Creek near Weston, Wyo. 1,235 c3,410 1972-78 1-17-74 8.05 1,000 19 11.62 5,300 (h) 110 06324995 Badger Creek at Biddle, Mont. 6.06 — 1972-78 6-23-76 7.97 414 18 2.48 54 33 111 06325400 East Fork Little Powder River near Hammond, Mont. 3.45 — 1974-78 6-23-76 6.18 155 18 5.69 40 33 112 06325500 Little Powder River near Broadus, Mont. 2,039 b3,020 1947-53; 1957-61; 1962-72 1972 9.30 2,700 20 9.85 33,160 2 113 06325700 Powder River tributary near Powderville, Mont. 3.20 — 1973-78 1973 16.91 480 18 2.42 32 33 114 06325950 Cut Coulee near Mizpah, Mont. 2.23 — 1973-78 5-05-75 8.45 272 18 4.17 103 20 115 06326300 Mizpah Creek near Mizpah, Mont. 797 c2,490 1974-78 5-06-75 9.80 1,920 19 7.04 1,030 >50 116 06326500 Powder River near Locate, Mont. 13,194 b2,400 1938-78 P2-19-43 11.23 31,000 23 11.27 27,400 7 117 06326510 Locate Creek tributary near Locate, Mont. .91 — 1973-78 1973 2.41 22 19 1.40 7 >50 118 06364700 Antelope Creek near Teckla, Wyo. 959 c4,450 1977-78 — — — 18 8.83 6,600 (h) 119 06365300 Dry Fork Cheyenne River near Bill, Wyo. 128 c5,060 1976-78 — — — 18 4.01 1,010 (h) 120 06365900 Cheyenne River near Dull Center, Wyo. 1,527 = ■*■4,312 1976-78 7-08-77 5.50 2,570 18 i12.00 11,800 (h) 121 06375600 Little Thunder Creek near Hampshire, Wyo. 234 =4,400 1977-78 — — — 18 9.02 3,030 (h) 122 06376300 Black Thunder Creek near Hampshire, Wyo. 535 =4,060 1972-78 9-09-73 11.49 804 18 14.13 5,050 (h) -3 TABLESTable 3.—Summary of flood stages and discharges—Continued oo Maximum flood previously known Maximum flood of May 1978 Site number (fig. 1) Permanent station number Site of flood-discharge determination Drainage area (mi2) Datum of gage above NGVD of 1929 (ft) Period of record Date Gage height (ft) Discharge (ft3/s) Day Gage height (ft) Discharge (f13/s ) Percent chance of exceedance3 123 06378300 Lodgepole Creek near Hampshire, Wyo. 354 c3,950 1977-78 — — — 18 4.08 166 (h) 124 06379600 Box Creek near Bill, Wyo. 112 1956-58; 1959; 1961-78 5-05-71 7.92 1,720 18 8.15 2,570 4 125 06382200 Pritchard Draw near Lance Creek, Wyo. k5.1 — 1964-78 9-03-68 13.29 4,050 18 4.78 360 >50 126 06386000 Lance Creek near Riverview, Wyo. 2,070 c3,750 1948-54; 1956-78 5-24-71 9.67 7,410 19 9.43 7,190 4 127 06386500 Cheyenne River near Riverview, Wyo. 5,270 c3,600 1948-74 5-22-62 8.74 16,000 — 12.22 k28,000 <1 128 06387500 Turner Creek near Osage, Wyo. 47.8 — 1959-78 6-15-62 16.72 3,000 18 15.57 2,480 11 129 06394000 Beaver Creek near Newcastle, Wyo. 1,320 c3,660 1943-78 6-16-62 19.98 11,900 19 16.37 3,870 3 130 06395000 Cheyenne River at Edgemont, S. Dak. 7,143 3,414.56 1903-06; 1928-33; 1946-78 5-25-71 10.57 13,800 20 13.65 k28,000 1 131 06425720 Belle Fourche River below Rattlesnake Creek near Piney, Wyo. 495 c4,540 1975-78 6-13-77 5.86 489 18 11.33 4,100 (h) 132 06425780 Belle Fourche River above Dry Creek near Piney, Wyo. 594 c4,460 1975-78 6-13-77 11.81 1,630 18 16.3 k5,630 (h) 133 06425900 Caballo Creek at mouth near Piney, Wyo. 260 c4,370 1977-78 — — — 19 8.66 2,170 (h) 134 06425950 Raven Creek near Moorcroft, Wyo. 76.0 c4,234 1977-78 — — — 19 5.55 236 (h) 135 06426400 Donkey Creek near Moorcroft, Wyo. 246 c4,200 1977-78 — — — 19 14.60 3,950 (h) MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO.Table 3.—Summary of flood stages and discharges—Continued Maximum flood Site Permanent Drainage Datura of Period previously known Maximum flood of May 1978 number (fig. 1) station number Site of flood-discharge determination area (mi2) gage above NGVD of 1929 (ft) of record Date Gage height (ft) Discharge (ft3/s) Day Gage height (ft) Discharge (ft3/s) Percent chance oi exceedance3 136 06426500 Belle Fourche River below Moorcroft, Wyo. 1,670 4,119.2 1943-70; 1975-78 5-27-62 14.33 r4,420 19 14.60 15,300 50 139 06429300 Ogden Creek near Sundance, Wyo. 8.42 — 1962-78 5-06-67 3.93 423 18 1.72 49 25 140 06634300 Sheep Creek near Medicine Bow, Wyo. 174 — 1961-78 7-07-61 11.48 1,900 17 9.76 1,700 5 141 06634600 Little Medicine Bow River near Medicine Bow, Wyo. 963 c6,600 1973-78 4-17-75 9.05 3,060 17 14.10 k9,500 (h) 142 06635000 Medicine Bow River above Seminoe Reservoir near Hanna, Wyo. 2,338 6,415.40 1939-78 3-29-43 5.23 6,590 18 6.25 5,220 3 143 06641400 Bear Springs Creek near Alcova, Wyo. 9.33 — 1960-78 10-06-62 12.36 533 17 12.24 131 50 144 06642000 North Platte River at 10,812 Alcova, Wyo. 5,299.40 1904-05; 1934-78 6-6, 10 11-1905 ill.50 13,400 17 — f395 — 145 06642700 Lawn Creek near Alcova, Wyo. 11.5 — 1961-78 8-10-74 9.15 1,250 17 7.60 565 13 146 06642760 Stinking Creek near Alcova, Wyo. 117 — 1961-78 8-12-63 7.93 2,750 17 7.12 1,750 20 147 06643300 Coal Creek near Goose Egg, Wyo. 5.39 — 1960-78 6-12-70 8.72 514 17 6.70 69 >50 148 06644840 McKenzie Draw tributary near Casper, Wyo. 2.02 — 1965-78 9-11-73 7.03 970 18 1.45 11 >50 CD TABLESTable 3.—Summary of flood stages and discharges—Continued Cn O Maximum flood previously known Maximum flood of May 1978 Site Permanent Drainage Datum of Period number (fig. 1) station number Site of flood-discharge determination area (mi2) gage above NGVD of 1929 (ft) of record Gage Gage Percent chance of Date height Discharge Day height Discharge exceed- (ft) (ft3/s) (ft) (ft3/s) ancea 149 06645150 Smith Creek above Otter Creek near Casper, Wyo. 9.91 c6,550 1974-78 5-13-75 3.40 40 17 1.37 19 (h) 150 06645160 Smith Creek at Otter Creek near Casper, Wyo. 10.9 c6,360 1974-78 5-13-75 1.54 39 17 2.84 16 (h) 151 06646600 Deer Creek below Millar Wasteway at Glenrock, Wyo. 213 c4,980 1961-78 6-12-70 9.45 14,200 17 8.87 6,090 3 152 06646700 East Fork Dry Creek tributary near Glenrock, Wyo. 2.60 — 1961-78 5-14-65 11.00 550 18 6.65 39 >50 153 06646780 Sand Creek near Glenrock, Wyo. 79.9 c5,000 1977-78 — — — 18 3.87 460 (h) 154 06646800 North Platte River near Glenrock, Wyo. 13,538 c4,920 1959-78 5-14-65 7.10 16,000 19 4.80 6,440 25 155 06647500 Box Elder Creek at Box Elder, Wyo. 63.0 c6,710 1946-51; 1961-67; 1971-78 5-14-65 is.58 4,530 17 6.61 2,230 3 156 06647890 Little Box Elder Creek near Careyhurst, Wyo. 7.18 c5,670 1974-78 6-18-75 1.31 21 18 1.69 54 (h) 157 06647900 Little Box Elder Creek at Little Box Elder Cave near Careyhurst, Wyo. 8.47 c5,480 1974-78 9-18-76 1.80 23 18 2.07 41 (h) 158 06648780 Sage Creek tributary near Orpha, Wyo. 1.38 — 1965-78 7-25-65 2.00 229 17 .40 10 >50 159 06649000 LaPrele Creek near Douglas, Wyo. 135 s5,600 1919-78 6-12-70 13.01 17,300 17 10.66 1,700 13 160 06649900 North Platte River tributary near Douglas, Wyo. 8.53 1961-78 5-22-61 11.32 1,400 18 4.97 91 50 161 06651800 Sand Creek near Orin, Wyo. 27.8 — 1955; 1961-78 8-07-55 — t20,700 16 k10.2 5,460 5 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO.Table 3.—Summary of flood stages and discharges—Continued Maximum flood previously known Maximum flood of May 1978 Site Permanent Drainage Datum of Period number station Site of flood- area gage above of (fig. 1) number discharge determination (mi2) NGVD of 1929 record Percent (ft) Gage Gage chance of Date height Discharge Day height Discharge exceed- (ft) (ft3/s) (ft) (ft3/s) ancea 162 _ Shawnee Creek near k90 ... 16 9,210 Orin, Wyo. k100 — — 8-07-55 — 7,530 — — — — 163 06652000 North Platte River 14,888 c4,660 1895-99; 5-15-65 10.00 23,800 17 7.76 12,200 14 at Orin, Wyo. 1917-18; 1924; 1958-78 164 06652400 Watkins Draw (formerly 6.95 — 1960-78 5-28-61 14.78 2,100 16 8.81 581 5 Watson Draw) near Lost Springs, Wyo. a<, less than; >, greater than. ^Altitude from barometer. cAltitude from topographic map. ^Estimated. eDoes not include bypass flow of about 9,200 cubic feet per second. ^Mean daily discharge. ^Affected by backwater. ^Less than 10 years of record (Wyoming stations only). *Site and datum then in use. JRevised from Oraang and Hull (1978). ^Approximate measurement. mPeak-flow record prior to 1974 water year includes records for station 06311500 (North Fork River near Mayoworth, Wyo.). nFlood of Sept. 30, 1923, reached a stage of 18.00 feet (discharge not determined). PFlood of September 1923 was probably greater. ^Gage moved 125 feet upstream during 1969 (same datum). rFlood of Apr. 7, 1924, reached a stage of 12.60 feet at site of former gaging station, 4.2 miles upstream at different datura; discharge, 12,500 cubic feet per second. Flood in June 1908 reached a stage about 2.50 feet higher than that of Apr. 7, 1924. sAltitude approximate from nearby line of levels. t0utside period of record. TABLESTable 7.—Sediment data t°C, degrees Celsius; ft3/s, cubic feet per second; mg/L, milligrams per liter; ton/d, tons per day; mm, millimeter] Oi to Date Time Temperature Cc) Streamflow, Instantaneous (ft3/s) Sediment suspended (mg/L) Sediment discharge (ton/d) Suspended sediment Fall diameter Percent finer than Indicated size, in millimeters Suspended sediment Sieve diameter Percent finer than Indicated size, in millimeters 0.004 0.016 0.062 0.125 0.250 0.500 1.00 0.062 0.125 0.250 0.500 1.00 2.00 06214500—Yellowstone River at Billings, Mont. (Lat 45°47'48" Long 108°28'12") 17 1700 11.0 21700 4260 250000 40 57 82 92 97 100 18 1400 9.0 30200 4130 357000 46 62 66 96 99 100 19 0815 9.0 50190 4550 615000 47 68 87 93 98 100 19 1415 9.0 42700 5160 595000 41 60 78 69 96 100 06267400—East Fork Nowater Creek near Colter, , Wyo. (site 12) 17 1750 8.5 512 68100 94100 18 1415 6.0 1550 41800 175000 15 1230 11.0 1390 5950 06270000—Nowood River near Tensleep 22300 , Wyo . (site 15) 18 2030 4.0 3060 5650 46700 19 2010 6.5 3000 3520 28500 06279500—Bighorn River near Kane, Wyo. (site 18) 20 1350 9.0 20700 11700 654000 54 67 92 96 98 100 06294700—Bighorn River at Bighorn, Mont. (site 39) 21 1230 14.5 20000 2800 151000 66 86 95 99 100 21 1430 12.0 103000 06295000—Yellowstone River 1920 534000 at Forsyth, Mont. (Lat 46° 15153" Long 106°41'43' 22 1700 17.0 37500 1250 130000 24 1100 17.5 30000 796 64500 87 91 62 90 77 06296120—Yellowstone River near Mills City, Mont. (Lat 46023'51" Long 105°53’36") 21 1800 15.0 77300 2830 591000 58 73 84 93 99 100 06305500—Goose Creek below Sheridan, Wyo. (site 50) 18 19 1720 1030 8.0 5540 3980 1660 1240 24800 13300 45 64 81 90 95 99 100 19 1740 — 2960 1060 8470 — 21 1010 — 2000 423 2280 — 87 83 71 06307525—Prairie Dog Creek above Jack Creek near Birney, Mont. (Lat 45°20'08" Long 106°46'25") 15 1720 19.5 1.7 253 1.2 24 1450 15.0 5.3 175 2.5 25 1445 14.0 4.8 126 1.6 83 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO.Table 7.—Sediment data—Continued Date Time Temperature Cc) Strearaflow, instantaneous (ft3/s) Sediment suspended (mg/L) Sediment discharge (ton/d) Suspended sediment Fail diameter Percent finer than Indicated size, in millimeters Suspended sediment Sieve diameter Percent finer than Indicated size, in millimeters 0.004 0.016 0.062 0.125 0.250 0.500 1.00- 0.062 0.125 0.250 0.500 1.00 2.00 06307528—Prairie Dog Creek near Birney, Mont. (Lat 45°17'28" Long 106°40'56") 18 1700 10.0 15 24 1205 17.5 4 25 1200 " 3 16 1430 17.5 19 1200 9.0 36 17 1215 14.0 8 20 1635 14.0 359 06307610- 17 1015 11.0 1660 19 1530 12.0 23 21 1330 15.5 1420 93 72 58 1.0 .66 100 06307560—East Trail Creek near Otter, Mont. (Lat 45°04'09" Long 106°24,35") .25 41 454 .03 44 06307600—Hanging Woman Creek near Birney, Mont, (site 58) 74 566 134 1.6 549 601 06307735—Home Creek near Ashland, Mont. (Lat 45°32'35" Long 106°11'39") 356 22 06307740—Otter Creek near Ashland, Mont, (site 62) 390 397 418 06307830—Tongue River below Brandenberg Bridge, near Ashland, Mont, (site 64) 96 95 99 95 17 1000 14.5 1550 510 2130 69 21 1500 — 5440 1440 21200 46 68 81 67 93 97 99 100 22 1730 — 8260 1120 25000 41 61 75 80 87 95 99 100 23 1350 — 6060 730 11900 42 62 81 88 98 100 06308160— -Pumpkin Creek near Loesch, Mont. (Lat 45°42 '40" Long 105°43'50") 15 1120 24.5 .04 121 .01 20 1400 14.0 146 136 54 99 15 1600 24.5 16 06308400—Pumpkin Creek near Miles City, Mont, (site 70) 146 6.3 99 U1 CO TABLESTable 7.—Sediment data—Continued Cn 4^ Date Time Temperature Cc) Strearaflow, instantaneous (ft3/s) Sediment suspended (mg/L) Sediment discharge (ton/d) Suspended sediment Fall diameter Percent finer than Indicated size, in millimeters Suspended sediment Sieve diameter Percent finer than Indicated size, in millimeters 0.004 0.016 0.062 0.125 0.250 0.500 1.00 0.062 0.125 0.250 0.500 1.00 2.00 06308500—Tongue River at Miles City, Mont, (site 71) 16 0800 17.5 1460 604 2380 19 0940 11.5 6980 5090 95900 75 86 90 95 98 100 21 1600 17.5 4490 1710 20700 44 61 78 89 99 100 23 1645 18.0 7700 2070 43000 30 42 06313400—Salt Creek near Sussex, Wyo. (site 88) 23 1115 — 96 1570 407 66 93 94 97 100 06313500—Powder River at Sussex, Wyo. (site 89) 19 1200 9.0 10500 48500 1380000 31 48 81 95 100 24 1700 16.0 2530 9560 65300 29 43 73 89 99 100 06316400- -Crazy Woman Creek at Upper Station, near Arvada, Wyo . (site 91) 19 1930 9.0 1640 2765 12200 62 76 86 92 97 99 100 25 1600 9.0 1109 2280 6830 43 60 79 91 97 99 100 06317000—Powder River at Arvada, Wyo. (site 92) 19 1305 9.0 16400 41500 1840000 39 57 81 95 100 20 1435 13.0 17800 38700 1860000 41 61 83 94 99 100 21 1415 16.5 5050 32000 436000 38 58 85 96 99 100 06318500—Clear Creek near Buffalo , Wyo. , (site 93) 19 1340 — 414 78 87 82 99 100 06320200—Clear Creek below Rock Creek near Buffalo, Wyo. (site 94) 17 1300 4.0 1240 346 1160 19 1440 8.0 1140 241 742 06320400—Clear Creek at Ucross, Wyo. (site 95) 19 1545 10.0 1410 594 2260 37 53 75 86 91 98 100 20 1830 10.5 1090 517 1520 21 1640 12.0 1190 477 1530 06321500—North Piney Creek near Story, Wyo. (site 98) 19 0900 — 375 174 176 20 0935 — 290 53 41 69 57 65 72 61 MAY 1978 FLOODS, SOUTHEASTERN MONT. AND NORTHEASTERN WYO.Table 7.—Sediment data—Continued Date Time Temperature Cc) Strearnf low, instantaneous (ft-Vs) Sediment suspended (mg/L) Sediment discharge (ton/d) Suspended sediment Fall diameter Percent finer than Indicated size, in millimeters Suspended sediment Sieve diameter Percent finer than Indicated size, in millimeters 0.004 0.016 0.062 0.125 0.250 0.500 1.00 0.062 0.125 0.250 0.500 1.00 2.00 06323000—Piney Creek at Kearny, Wyo. (Lat 44°32'08" Long 106°49'18") 19 20 16 0750 0845 1430 17.0 1010 634 225 82 614 140 57 56 06323500—Piney Creek at Ucross, Wyo. (site 99) 19 1610 — 1090 217 639 49 68 84 90 97 100 20 1800 — 680 183 336 58 21 1610 — 614 162 269 61 06324000—Clear Creek near Arvada, Wyo. (site 100) 20 1230 12.0 3020 1300 10600 34 54 75 83 86 92 100 21 1240 12.5 2080 1170 6570 56 06324710—Powder River at Broadus, Mont. (site 103) 18 1030 12.0 6300 19300 328000 27 43 82 96 99 100 22 1520 17.0 8910 22600 544000 45 69 90 97 100 10 06324890—Little Powder River below Corral Creek, near Weston, Wyo. (site 105) 06324925—Little Powder River near Weston, Wyo. (site 108) 16 1000 15.5 31 400 33 19 1030 10.0 4250 9130 105000 06324970— •Little Powdi 16 1200 16.5 103 377 105 06326500—1 22 1400 — 22600 19000 1160000 1430 18.0 24100 14700 957000 1500 — 23000 17000 1060000 1600 — 23600 17700 1130000 1700 18.0 23500 17900 1140000 1800 17.5 24000 18200 1180000 1900 17.5 24100 18700 1220000 2000 17.0 24700 19000 1270000 2100 — 25200 19000 1290000 2330 — 26600 18500 1330000 23 0100 — 27200 17500 1290000 96 90 98 100 06326500—Powder River near Locate, Mont, (site 116) 55 73 85 95 100 99 77 81 81 62 84 82 83 83 85 85 cn w TABLESTable 7.—Sediment data—Continued o X J— LU LU Li_ O CD D (J CJ Z < if) Z) o X o D Q O QC Q_ CO < LU > < _J D D (J YEAR 400 - 300 - 200 - 100 o X if) QC LU \— LU 5 o 00 Z> o z o ►— CJ Z) Q o QC 0_ if) < o LU > < —I Z> 5 Z) U -1 0 Figure 9.—Cumulative production from the Kern Front oil field. Based on production figures given in table 4 and the 1968 cumulative production figures of the state oil and gas supervisor (California Division of Oil and Gas, 1968, p. 53, 77). Cumulative liquid production through 1919 derived through the application of the 1920-1928 produced oilrwater ratio in the calculation of pre-1920 water production. so PROBABLE NATURE OF THE SURFACE DEFORMATIONTable 4.—Production figures for the Kern Front oilfield, 1912-68 [Based chiefly on production figures given by Park (1965, p. 20). Production figures for 1964 and later years taken chiefly from annual summary reports of the state oil and gas supervisor. Water-production figures prior to 1942 determined through prorationing of the Kern River water production against oil production from the Kern Front and Kern River oil fields; production figures for the two fields were generally lumped prior to 1942. One bbl = 5.615 ft3 = 0.1590 m3; 1 Mcf = 103 ft3 = 28.32 m3] Year Oil production (bbls) Gas production (Mcf) Water production (bbls) Cumulative gross liquid production (bbls) Steam injection (bbls) Cumulative net liquid production (bbls) 1912 No records - - - - - 1913 4,245 - - - - - 1914 13,050 - - - 1915 32,439 - - - - - 1916 19,995 - - - - - 1917 21,838 - - - - - 1918 17,867 - - - - - 1919 36,452 - - - - - 1920 106,400 - 553,000 659,400 - 659,400 1921 288,356 - 1,345,000 1,633,356 - 1,633,356 1922 352,853 - 1,808,000 2,160,853 - 2,160,853 1923 226,637 - 1,250,000 1 ,476,637 - 1,476,637 1924 275,813 - 1 ,558,000 1,833,813 - 1 ,833,813 1925 318,065 - 1 ,850,000 2,168,065 - 2,168,065 1926 608,936 - 3,946,000 4,554,936 - 4,554,936 1927 3,230,335 - 13,200,000 16,430,335 - 16,430,335 1928 2,710,305 - 15,400,000 18,110,305 - 18,110,305 1929 4,535,059 - 16,550,000 21 ,085,059 - 21 ,085,059 1930 4,276,671 s.sse.so^ 3,838,000 8,114,671 - 8,114,671 1931 2,996,152 471,981 2,688,000 5,684,152 - 5,684,152 1932 2,540,348 350,563 2,744,000 5,284,348 - 5,284,348 1933 2,369,570 329,062 3,700,000 6,069,570 - 6,069,570 1934 2,381,228 343,465 4,740,000 7,121,228 - 7,121,228 1935 2,988,584 370,220 8,330,000 11,318,584 - 11,318,584 1936 3,555,297 368,096 9,101,000 12,656,297 - 12,656,297 1937 3,876,157 463,152 10,650,000 14,526,157 - 14,526,157 1938 3,093,025 367,933 11 ,700,000 14,793,025 - 14,793,025 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA1939 2,513,135 228,121 1940 2,197,236 200,080 1941 2,133,776 178,476 1942 2,442,379 206,924 1943 2,677,400 283,406 1944 3,224,744 392,398 1945 3,179,581 456,712 1946 3,228,376 478,758 1947 3,241,709 450,110 1948 3,243,276 441,155 1949 2,535,189 298,657 1950 2,422,423 233,676 1951 2,773,067 239,736 1952 2,737,880 256,722 1953 2,669,822 233,061 1954 2,248,232 214,667 1955 2,190,925 159,030 1956 2,302,904 167,246 1957 2,297,891 170,608 1958 2,166,030 161,949 1959 2,158,255 146,301 1960 2,027,629 134,128 1961 1,959,303 142,986 1962 2,162,826 139,044 1963 2,159,519 150,230 1964 2,265,650 145,707 1965 2,613,426 146,127 1966 2,543,400 136,564 1967 2,437,261 115,387 1968 2,464,519 116,895 -^Cumulative gas 1912-1930 —^Cumulative figure, 1964-1965 12.050.000 13.760.000 22.480.000 4,185,186 4,002,759 4,950,057 5,726,716 6,968,983 7,974,242 9,013,052 8,975,505 9,742,610 11,895,301 13,319,878 14.165.940 13,858,855 15,278,470 16,374,761 16,283,003 15,625,461 16,217,265 16,263,209 16,925,084 19,082,738 19,975,753 20,740,735 24,114,894 25.085.940 24,633,544 24,431 ,510 14,563,135 15,957,236 24,613,776 6,627,565 6,680,159 8,174,801 8,906,297 10,197,359 11,215,951 12,256,328 11,510,694 12,165,033 14,668,368 16,057,758 16,835,762 16,107,087 17,469,395 18,677,665 18,580,894 17,791,491 18,375,520 18,290,838 18,884,387 21 ,245,564 22,135,272 23,006,385 26,728,320 27,629,340 27,070,805 26,896,029 1 ,946,257^ 1,517,876 888,984 962,582 14,563,135 15,957,236 24,613,776 6,627,565 6,680,159 8,174,801 8,906,297 10,197,359 11,215,951 12,256,328 11,510,694 12,165,033 14,668,368 16,057,758 16,835,762 16,107,087 17,469,395 18,677,665 18,580,894 17,791 ,491 18,375,520 18,290,838 18,884,387 21,245,564 22,135,272 23,006,385 24,782,063 26,111 ,464 26,181 ,821 25,933,447 to PROBABLE NATURE OF THE SURFACE DEFORMATION22 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA areas (pi. 1). Production from the Poso Creek oil field began in 1919 in the Premier area, but the “discovery” well was shut in in 1922 (Weddle, 1959, p. 41-42); significant production from the Premier, Enas, and McVan areas began in 1934, 1938, and 1936, respectively (table 5). Cumulative production from the Poso Creek oil field through 1972 by area consisted of: Premier area— 52,024,136 bbls (8.272 x 106 m3) of oil, 4,548,370 Mcf (128.810 x 106 m3) of gas, and 424,798,125 bbls (67.543 x 106 m3) of water (fig. 10A); Enas area—912,573 bbls (145,083 m3) of oil, and 7,077,926 bbls (1.125 x 106 m3) of water (fig. 10B); McVan area—2,534,959 bbls (403,058 m3) of oil, and 9,027,802 bbls (1.435 x 106 m3) of water (fig. 10C). Prior to 1972, wastewater was disposed of in sumps and stream channels; underground disposal, which was confined to the Premier area (table 5; Weddle, 1959, p. 47; California Division of Oil and Gas, 1972, p. 149), had by 1972 amounted to only 2,697,557 bbls (428,911 m3). Although steam injection has been carried out in all the producing areas of the Poso Creek field, injection in the Enas area has been trivial, and cumulative injection over the field as a whole through 1972 consisted of 4,783,832 bbls (760,629 m3) (table 5; California Division of Oil and Gas, 1972, p. 144). Figure 10.—Cumulative production from the Poso Creek oil field. Based on production figures given in table 5. A, Premier area. B, Enas area. C, McVan area.PROBABLE NATURE OF THE SURFACE DEFORMATION 23 Table 5.—Production figures for the Poso Creek oil field, 1919-72 [Premier and Enas areas: Based chiefly on production figures given by Weddle (1959, p. 50). Production figures for 1960 and later years taken from annual summary reports of the state oil and gas supervisor. McVan area: Based chiefly on production figures given by Mathews (1957, p. 27). Oil production for 1957 and 1958 and water production for 1957 deduced from Premier and Enas figures given by Weddle (1959, p. 50) and production figures for the full field given in the 1957 and 1958 summary reports of the state oil and gas supervisor. One bbl = 5.615 ft3 = 0.1590 m3; 1 Mcf = 103 ft3 = 28.32 m3] Premier area Year Oil production (bbls) Gas production (Mcf) Water production (bbls) Cumulative gross liquid production (bbls) Water flooding (bbls) Steam injection (bbls) Water disposal (bbls) Cumulative net liquid production (bbls) 1919-1929 16,632 - - 16,632 - - - 16,632 1929 6,572 - 323 6,895 - - - 6,895 1930 - - - - - - - - 1931 - - - - - - - - 1932 - - - - - - - - 1933 9,833 4,095 244 10,077 - - - 10,077 1934 75,571 7,300 4,816 80,387 - - - 80,387 1935 253,281 24,785 46,446 299,727 - - - 299,727 1936 570,431 65,746 198,400 768,831 - - - 768,831 1937 918,910 68,975 434,760 1,353,670 - - - 1,353,670 1938 599,927 40,412 574,232 1,174,159 - - - 1,174,159 1939 506,946 28,057 791,789 1,298,735 - - - 1,298,735 1940 427,717 25,065 961,314 1,389,031 - - - 1,389,031 1941 450,531 24,125 1,058,948 1,509,479 - - - 1,509,479 1942 570,366 34,385 1,440,514 2,010,880 - - - 2,010,880 1943 1,479,196 168,549 2,297,373 3,776,569 - - - 3,776,569 1944 1,618,733 210,499 2,440,292 4,059,025 - - - 4,059,025 1945 1,421,640 182,687 3,090,911 4,512,551 - - - 4,512,551 1946 1,239,974 150,862 3,348,420 4,588,394 - - - 4,588,394 1947 1,265,472 91,962 4,124,531 5,390,003 - - - 5,390,003 1948 1,216,436 101,849 4,616,777 5,833,213 - - - 5,833,213 1949 710,527 52,510 3,996,796 4,707,323 - - - 4,707,323 1950 770,139 59,300 4,541,427 5,311,566 - - - 5,311,566 1951 1,138,293 61,012 5,421,185 6,559,478 - - - 6,559,478 1952 1,352,793 101,071 6,466,360 7,819,153 - - - 7,819,153 1953 1,725,750 123,970 7,610,832 9,336,582 - - - 9,336,582 1954 1,275,342 130,985 7,198,829 8,474,171 - - - 8,474,171 1955 1,241,072 119,503 9,394,599 10,635,671 - - - 10,635,671 1956 1,465,415 122,607 13,023,014 14,488,429 - - - 14,488,429 1957 1,598,931 120,633 12,243,015 13,841,946 - - - 13,841,946 1958 1,288,507 144,484 11,530,583 12,819,090 - - - 12,819,090 1959 1,301,393 168,903 12,281,532 13,582,925 - - - 13,582,925 1960 1,294,230 192,170 12,703,673 13,997,903 - - - 13,997,903 1961 1,418,249 180,935 13,890,678 15,308,927 30,456 - - 15,278,471 1962 2,091,727 151,481 16,974,611 19,066,338 90,058 - - 18,976,280 1963 2,769,187 167,486 18,091,633 20,860,820 4,363 - - 20,856,457 1964 2,810,751 231,998 22,081,266 24,892,017 - - - 24,892,017 1965 2,376,478 211,953 24,138,469 26,514,947 - 72,901 - 26,442,046 1966 2,234,539 175,581 29,403,950 31,638,489 - 276,342 - 31 ,362,147 1967 2,168,002 143,239 28,631,188 30,799,190 - 433,957 - 30,365,233 1968 1,949,108 145,311 27,605,579 29,554,687 - 402,496 - 29,152,191 1969 1,632,872 108,354 25,339,067 26,971,939 - 366,631 - 26,605,308 1970 1,595,335 103,503 27,904,413 29,499,748 - 478,062 - 29,021 ,686 1971 1,642,670 146,959 29,468,488 31,111,158 - 847,747 - 30,263,411 1972 1,524,658 155,069 29,426,848 30,951,506 - 696,522 2,697,557 27,557,427£»-iy 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA Table 5.—Production figures for the Poso Creek oil field, 1919-72—Continued Enas area il production (bbls) Gas production (Mcf) Water production (bbls) Cumulative gross liquid production (bbls) Steam injection (bbls) Cumulative net liquid production (bbls) No records _ _ _ _ _ 2,855 - 328 3,183 - 3,183 2,255 - 321 2,576 - 2,576 200 - 113 313 - 313 168 - 112 280 - 280 1,351 - 936 2,287 - 2,287 1,855 - 1,332 3,187 - 3,187 6,105 - 5,222 11,327 - 11,327 12,629 - 37,741 50,370 - 50,370 3,099 - 16,640 19,739 - 19,739 2,969 - 1,398 4,367 _ 4,367 18,358 - 4,049 22,407 - 22,407 48,187 - 7,957 56,144 - 56,144 52,536 - 15,865 68,401 - 68,401 47,913 - 17,671 65,584 - 65,584 42,817 - 26,456 69,273 - 69,273 40,089 - 24,976 65,065 - 65,065 37,453 - 44,200 81,653 - 81,653 33,990 - 100,375 134,365 - 134,365 30,512 - 90,117 120,629 - 120,629 28,821 - 88,180 117,001 - 117,001 25,348 - 81,553 106,901 - 106,901 23,244 - 71,064 94,308 - 94,308 23,652 - 77,347 100,999 - 100,999 20,574 - 116,970 137,544 - 137,544 22,992 - 166,709 189,701 - 189,701 22,258 - 167,429 189,687 - 189,687 20,213 - 145,074 165,287 - 165,287 17,655 - 188,867 206,522 - 206,522 17,604 - 232,995 250,599 - 250,599 14,477 - 172,220 186,697 - 186,697 14,510 - 197,743 212,253 - 212,253 40,348 - 544,595 584,943 - 584,943 53,268 - 677,226 730,494 - 730,494 38,328 - 685,931 724,259 2,800 721,459 36,894 - 502,425 539,319 - 539,319 28,864 - 523,645 552,509 - 552,509 25,083 - 591 ,765 616,848 - 616,848 21,694 - 570,933 592,627 - 592,627 14,837 - 492,349 507,186 - 507,186 16,468 - 389,897 406,365 - 406,365PROBABLE NATURE OF THE SURFACE DEFORMATION 25 Table 6.—Production figures for the Poso Creek oilfield, 1919-72—Continued McVan area Year Oil production (bbls) Gas production (Mcf) Water production (bbls) Cumulative gross liquid production (bbls) Steam injection (bbls) Cumulative net liquid production (bbls) 1932 4,343 _ 730 5,073 _ 5,073 1933 8,999 - 1,187 10,186 - 10,186 1934 9,497 - 1,859 11,356 - 11,356 1935 3,701 - 1,208 4,909 - 4,, 909 1936 13,558 - 4,387 17,945 - 17,945 1937 53,758 - 31,017 84,775 - 84,775 1938 51,689 - 17,976 69,665 - 69,665 1939 35,072 - 41,563 76,635 - 76,635 1940 34,384 - 74,916 109,300 - 109,300 1941 28,507 - 77,332 105,839 - 105,839 1942 28,873 - 53,310 82,183 - 82,183 1943 30,721 - 70,566 101,287 - 101,287 1944 30,413 - 85,936 116,349 - 116,349 1945 30,511 - 62,626 93,137 - 93,137 1946 27,521 - 157,754 185,275 - 185,275 1947 32,062 - 192,648 224,710 - 224,710 1948 33,979 - 179,375 213,354 - 213,354 1949 37,713 - 181,763 219,476 - 219,476 1950 27,404 - 211,422 238,826 - 238,826 1951 26,100 - 154,625 180,725 - 180,725 1952 23,937 - 139,335 163,272 - 163,272 1953 24,105 - 150,036 174,141 - 174,141 1954 26,431 - 178,805 205,236 - 205,236 1955 21,814 - 161,833 183,647 - 183,647 1956 33,528 - 204,039 237,567 - 237,567 1957 36,212^ - 170,865 203,347 - 203,347 1958 32,878^ - 181,361—7 210,508 - 210,508 1959 28,988 - 191,856 220,844 - 220,844 1960 37,155 - 170,443 207,598 - 207,598 1961 40,335 - 175,583 215,918 - 215,918 1962 34,065 - 154,935 189,000 - 189,000 1963 40,246 - 153,090 193,336 - 193,336 1964 39,924 - 175,313 215,237 - 215,237 1965 41,766 - 226,172 267,938 6.228M/ 261,710 1966 107,489 - 288,130 395,619 107,198^/ 288,421 1967 290,327 - 532,536 822,863 233,660^/ 589,203 1968 318,241 - 727,651 1,045,892 331,788^/ 714,104 1969 311,768 - 957,782 1,269,550 213,879 1,055,671 1970 223,319 - 894,018 1,117,337 98,302 1,019,035 1971 139,979 - 748,506 888,485 94,191 794,294 1972 130,628 “ 853,793 984,421 121,128 863,293 -^Adjusted to agree with the 1959 cumulative figure. -^Average of 1957 and 1959 water production figures. -^Cumulative steam injection 1964 through 1965 (began Dec. 1964). Adjusted to agree with the 1968 corrected cumulative figure.Table 6.—Production figures for the Mount Poso oilfield, 1926-63 ga [Based chiefly on production figures given by Albright and others (1957, p. 19). Production figures for 1958 and later years taken from annual summary reports of the state oil and gas supervisor. One bbl = 5.615 ft8 = 0.1590 m3; 1 Mcf = 10s ft8 - 28.32 m8] Year Oil production (bbls) Gas production (Mcf) Water production (bbls) Cumulative gross liquid production (bbls) Water flooding (bbls) Steam injection (bbls) Cumulative net liquid production (bbls) 1926 52,124 1 ,720^ 440 52,564 _ _ 52,564 1927 42,944 1,411-1 113 43,657 - - 43,657 1928 56,344 1,859-^ 677 57,021 - - 57,021 1929 1 ,826,201 24,286 124,105 1 ,950,306 - 1 ,950,306 1930 3,866,443 129,495 360,994 4,227,437 - - 4,227,437 1931 3,017,175 71,806 1 ,262,044 4,279,219 - - 4,279,219 1932 2,915,199 43,141 2,312,050 5,227,249 - - 5,227,249 1933 3,043,262 17,502 2,461,016 5,504,278 - - 5,504,278 1934 3,438,510 5,872 3,098,376 6,536,886 - - 6,536,886 1935 5,375,637 39,776 4,177,093 9,552,730 - - 9,552,730 1936 6,733,250 59,087 6,548,846 13,282,096 - - 13,282,096 1937 6,574,928 40,050 10,989,122 17,564,050 - - 17,564,050 1938 6,250,946 17,641 13,418,937 19,669,883 - - 19,669,883 1939 4,262,235 12,998 13,830,332 18,092,567 - - 18,092,567 1940 3,411,800 1,744 12,493,232 15,905,032 - - 15,905,032 1941 4,102,032 575 14,033,745 18,135,777 - - 18,135,777 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA1942 7,472,396 592 26,341,678 33,814,074 - - 33,814,074 1943 8,427,304 63,110 37,177,639 45,604,943 - - 45,604,943 1944 8,005,438 186,583 47,077,515 55,082,953 - - 55,082,953 1945 6,712,104 194,614 55,619,576 62,331 ,680 - - 62,331 ,680 1946 5,935,637 120,332 63,519,932 69,455,569 - - 69,455,569 1947 5,157,837 77,428 69,566,885 74,724,722 - - 74,724,722 1948 4,569,050 75,775 73,930,456 78,499,506 - - 78,499,506 1949 4,202,066 83,591 77,659,629 81,861,695 - - 81 ,861 ,695 1950 3,807,950 75,511 77,984,536 81 ,792,486 - - 81 ,792,486 1951 3,450,576 61,028 81,171,519 84,622,095 - - 84,622,095 1952 3,281 ,569 79,943 81,681,816 84,963,385 - - 84,963,385—^ 1953 3,101,339 66,469 87,255,087 90,356,426 - - 90,356,426^ 1954 3,085,996 55,560 89,041,386 92,127,382 - - 92,127,382—^ 1955 3,161,201 58,133 95,378,219 98,539,420 111 ,385^ - 98,428,035-/ 1956 3,379,734 51,617 99,582,612 102,962,346 54,398-/ - 102,907,948 1957 3,315,953 33,411 105,112,491 108,428,444 52,338—^ - 108,376,106 1958 3,393,644 44,796 109,867,717 113,261 ,361 47,716-/ - 113,213,645 1959 3,175,586 56,212 110,359,421 113,535,007 56,704—^ - 113,478,303 1960 2,847,895 49,282 111,182,315 114,030,210 49,892^ - 113,980,318 1961 2,473,243 40,762 108,070,351 110,543,594 - - 110,543,594 1962 2,238,560 26,285 106,219,578 108,458,138 - - 108,458,138 1963 2,163,317 730 104,155,602 106,318,919 - No record 106,318,919 —^Estimated figures. 2/ — Does not reflect water flooding begun in 1952. 3/ -Cumulative water flooding figure for 1952-1955. 4/ -Adjusted to agree with 1963 corrected cumulative figure. Cumulative Production by Area, 1963 Main Dorsey Dominion Baker-Grover Granite Canyon West Oil (bbls) 133,378,777 3,761,832 4,550,013 3,491,350 716,941 2,428,512 Gas (Mcf) 1,970,733 ... - Water (bbls) 1,670,553,304 63,519,185 77,660,853 60,797,505 4,106,359 26,429,868 to PROBABLE NATURE OF THE SURFACE DEFORMATION28 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA Although a modest gas drive may have operated in the Premier area, the production is essentially water driven. Oil and gas produced from the Premier and Enas areas is drawn from the Chanac Formation and, to a much lesser extent, the basal sand of the Etchegoin (pi. 1); oil produced from the McVan area is drawn exclusively from the basal part of the Etchegoin (Mathews, 1957, p. 26; Weddle, 1959, p. 45). Production is from an average depth of 750 m in the Premier area, 550 m in-the Enas area, and about 350 m in the McVan area (California Division of Oil and Gas, 1960, p. 213, 215). A number of faults, most of which roughly parallel this elongate field have been mapped in the subsurface, and at least two apparently extend to the surface (section C-C', pi. 1; Weddle, 1959, pi. II). Although areally expansive and broken into a number of producing areas (pi. 1), the Mount Poso oil field is, in fact, about the size of the Kern Front field. Production from the Main area of the Mount Poso oil field began in 1926 (table 6; Albright and others, 1957, p. 6). Discovery wells in the Dorsey, Dominion, Baker-Grover, Granite Canyon, and West areas were subsequently completed in 1928, 1928, 1935, 1938, and 1943, respectively (Albright and others, 1957, p. 8-9). Cumulative production from the entire Mount Poso oil field through 1963 consisted of 148,327,425 bbls (23.584 x 106 m3) of oil, 1,970,733 Mcf (55.811 x 106 m3) of gas, and 1,902,694,649 bbls (302.528 x 106 m3) of water (fig. 11). Production of both oil and water have been predominantly from the Main area; oil and water drawn from all O X CJ 03 3 CJ o z < < —I 3 3 CJ 60 50 V) CL 40 cj CO 3 CJ - 30 - 20 z o H CJ 3 D O CL Q. CO < o ID > H < 3 3 CJ 10 -1 0 Figure 11.—Cumulative production from the Mount Poso oil field. Based on production figures given in table 6.PROBABLE NATURE OF THE SURFACE DEFORMATION 29 other areas combined is trivial by comparison (table 6). Water flooding, seemingly confined to the Main area, began in 1952; by 1963 it totaled only 372,433 bbls (50,217 m3) (table 6). The gasioil ratio in the Mount Poso oil field has been characteristically small (table 6; fig. 11), and the production clearly is water driven. Petroleum production in the Main area is principally from the various parts of the Vedder Sand (pi. 1) at an average depth of about 550 m (Albright and others, 1957, p. 14; California Division of Oil and Gas, 1960, p. 189). Production from the other areas of the Mount Poso field is nearly exclusively from the upper part of the Vedder at average depths that range between 425 and 800 m (California Division of Oil and Gas, 1960, p. 181, 183, 185, 187, 191). The entire Mount Poso oil field, according to Albright and others (1957, p. 10), is complexly faulted (section D-D'-D"-D"'-D"", pi. 1) and “all of the production areas within the field are fault closed reservoirs. ” In terms of areal extent, the Fruitvale field is perhaps the smallest of all the oil fields considered here (pi. 1), but it has, nonetheless, been relatively productive. The field was discovered in 1928 (Johnston, 1952, p. 122), but it was not until the middle 1930’s that production began to increase significantly (table 7). Cumulative production through 1959 consisted of 77,437,776 bbls (12.313 x 106 m3) of oil, 22,731,949 Mcf (643.769 x 106 m3) of gas, and 97,409,490 bbls (15.488 x 106 m3) of water (fig. 12). Wastewater was not injected into the subsurface until 1958, and it amounted to only 2,535,763 bbls (403,186 m3) through 1959 (table 7). Although the production from the Fruitvale oil field does not begin to compare with that from the Kern River field, the gas:oil ratio is more than an order of magnitude greater than the ratio that has characterized the Kern River production and about twice that of the Kern Front oil field (figs. 8, 9, and 12); hence we infer that gas drive in the Fruitvale field has been significantly greater than in any of the other fields shown on plate 1. Petroleum produced from the Fruitvale field has been almost exclusively from the Chanac Formation at an average depth of about 1,000 m (California Division of Oil Table 7.—Production figures for the Fruitvale oilfield, 1928-59 [Compiled from production figures given in annual summary reports of the state oil and gas supervisor. One bbl =5.615 ft3 = 0.1590 m3; 1 Mcf = 103 ft3 = 28.32 m8] Year Oil production (bbls) Gas production (Mcf) Water production (bbls) Cumulative gross liquid production (bbls) Water disposal (bbls) Cumulative net liquid production (bbls) 1928 151,596 _ _ 151,596 _ 151,596 1929 633,756 192,036 23,290 657,046 - 657,046 1930 915,897 404,317 28,855 944,752 - 944,752 1931 872,521 320,419 40,541 913,062 - 913,062 1932 1,626,378 594,163 104,877 1,731,255 - 1,731,255 1933 1,686,861 485,273 151,194 1,838,055 - 1,838,055 1934 1,360,849 330,590 166,208 1,527,057 - 1,527,057 1935 1,857,633 314,830 168,442 2,026,075 - 2,026,075 1936 2,864,106 442,137 257,231 3,121,337 - 3,121,337 1937 3,234,462 395,301 482,590 3,717,052 - 3,717,052 1938 3,087,265 323,583 847,290 3,934,555 - 3,934,555 1939 2,371,694 159,337 1,397,288 3,768,982 - 3,768,982 1940 2,061,009 85,901 1,312,938 3,373,947 - 3,373,947 1941 2,106,675 178,652 1,631,062 3,737,737 - 3,737,737 1942 2,343,320 514,061 1,566,440 3,909,760 - 3,909,760 1943 2,584,672 647,547 1,593,083 4,177,755 - 4,177,755 1944 3,107,735 538,524 2,624,474 5,732,209 - 5,732,209 1945 3,145,684 426,348 2,596,324 5,742,008 - 5,742,008 1946 2,865,318 358,325 3,315,850 6,181,168 - 6,181,168 1947 2,540,673 408,243 4,095,745 6,636,418 - 6.636,418 1948 2,510,580 433,429 5,400,324 7,910,904 - 7,910,904 1949 2,800,030 496,208 5,397,908 8,197,938 - 8,197,938 1950 2,879,778 598,438 4,978,029 7,857,807 - 7,857,807 1951 3,355,966 1,432,386 5,199,617 8,555,583 - 8,555,583 1952 3,413,106 1,653,180 4,403,574 7,816,680 - 7,816,680 1953 3,577,090 1,227,029 4,907,813 8,484,903 - 8,484,903 1954 3,580,703 1,450,330 5,723,608 9,304,311 - 9,304,311 1955 3,400,291 1,746,983 6,435,074 9,835,365 - 9,835,365 1956 3,203,696 1,741,083 7,538,478 10,742,174 - 10,742,174 1957 3,000,396 1,742,308 8,143,193 11,143,589 - 11 ,143,589 1958 2,718,723 1,653,561 8,488,380 11,207,103 13,993 11,193,110 1959 2,503,221 1,437,427 8,389,770 10,892,991 2,521,770 8,371 ,22130 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA and Gas, 1960, p. 115). Although the subsurface is thought to be laced with faults and the east boundary of the field is clearly fault controlled (Johnston, 1952, p. 123), none of these faults is known to project to the surface. DIFFERENTIAL SUBSIDENCE Subsidence associated with producing oil fields is governed by the same general principles as those that control subsidence associated with ground-water withdrawals from a confined aquifer (see section on “Surface Deformation Attributable to Ground-water Withdrawals” and Poland and Davis, 1969). Moreover, because all five of the oil fields described in the preceding paragraphs meet at least two of the several criteria that render them susceptible to compaction-induced subsidence, the likelihood that these particular fields may have sustained measurably significant subsidence is greatly enhanced. Specifically, since all produce from relatively young deposits (none of which are older than Miocene or conceivably Oligocene) at relatively shallow depths of generally less than 1,000 m, we could expect to find at least modest subsidence centering on any of these fields (Yerkes and Castle, 1969). Four of the five oil fields shown on plate 1 are characterized by differential subsidence of sufficient magnitude that it cannot be dismissed as the product of systematic or random error in geodetic leveling. Moreover, while this determination is in two out of four cases based on repeated surveys into a single mark, such that the measured signals are conceivably attributable to benchmark disturbance, this possibility would ask a good deal of chance coincidence. Similarly, even though the reported displacements are based largely on the results of single-run levelings, the differential subsidence identified with all but one of these examples is clearly an aberration on the regional tilt that persists through the oil fields (see section on “Surface Deformation Attributable to Tectonic Activity”). Hence it is very unlikely O X Z) CJ o z < CO D 0 1 H Z Z o H CJ D o o cc Q_ (/) < o D D CJ -1 1000 800 co cc UJ 1“ UJ o CD 600 g z o h" CJ D o o cc Q. CO < cD 400 D 200 3 Figure 12.—Cumulative production from the Fruitvale oil field. Based on production figures given in table 7.PROBABLE NATURE OF THE SURFACE DEFORMATION 31 that the observed subsidence could be due to blunders in any of the levelings. The maximum measured subsidence associated with operations in the Kern Front oil field has been recorded at bench mark 864 (pi. 1). Subsidence of this mark during the period 1903-68 is given as 0.3094 m with respect to 448 B (table 2). However, because significant production from this field did not begin until the middle or late 1920’s (table 4, fig. 9), it is likely that nearly all this subsidence has occurred since about 1930. Similarly, because 448 B probably sustained about 0.055 m of compaction-induced subsidence during the period 1903-68 (see section on “Surface Deformation Attributable to Ground-water Withdrawals”), we infer that the Kern Front oil field could have undergone no less than 0.36 m of differential subsidence during the period 1925-68. Moreover, measurement with respect to either bench mark 1133 or 1205 (pi. 1), neither of which could have sustained significant compaction-induced subsidence, suggests that 864 subsided 0.4145 and 0.4042 m, respectively, during the period 1903-68 (table 2). Finally, because nearby bench mark B-l 1931 (pi. 1) apparently rose 0.1024 m with respect to 448 B during the period 1931-68 (table 2), subsidence in the Kern Front oil field with respect to any point adjacent to but well outside the producing area of the field clearly exceeded 0.4 or even 0.5 m during the period 1903-68. The likelihood that the subsidence of bench mark 864 is due to oil-field operations is supported by the vertical displacement history of bench mark B 1931, which lies within but toward the edge of the Kern Front oil field (pi. 1). B 1931 subsided 0.0415 m with respect to 448 B and nearly 0.15 m with respect to B-l 1931 during the period 1931-68 (table 2). Nonetheless, a feature that challenges the likelihood that the subsidence in the Kern Front field is causally related to exploitation is the seeming absence of significant subsidence at B 1931 before 1963 (table 2). However, subsidence of B 1931 prior to 1963 could easily have been masked by comparable compaction-induced subsidence at 448 B or regional tilting between these marks during the period 1931-63. It is equally likely, moreover, that the recognition of subsidence at B 1931 since 1963 can be attributed to reduced pumpage or the achievement of near ultimate aquifer compaction in the area of 448 B. This interpretation is clearly consistent with the displacement history of B 1931 with respect to B-2 1931, a nearby bench mark that probably has undergone little if any compaction-induced subsidence. Specifically, roughly two thirds (or 0.1194 m) of the 0.1750 m of the subsidence of B 1931 with respect to B-2 1931 during the full period 1931-68 had occurred by 1963 (table 2). The existence of subsidence identified with the operations in the Poso Creek oil field is based on a single comparison; it is, as a result, the most equivocal of any of the examples of oil-field subsidence described here. Subsidence of bench mark 545 B (pi. 1) during the interval 1903-53 is given as 0.3322 m with respect to 448 B (table 2). If allowance is made for the probable compaction beneath 448 B, differential subsidence of this mark could easily increase to 0.36-0.37 m. Computation of the reported subsidence of 545 B is based on an assumption of vertical invariance between 448 B and B-3 1931 during the period 1953-63, a period that bracketed the inception and first major deformational episode associated with the evolution of the southern California uplift (Castle and others, 1976). Because B-3 1931 sustained an up-to-the-east tilt of 0.1301 m with respect to 448 B during the period 1931-63 (table 2), it is likely that at least a fraction of this relative uplift, and conceivably as much as 0.07-0.08 m, occurred between 1953 and 1963. Accordingly, the actual 1953 height of 545 B with respect to 448 B may have been 0.07-0.08 m less than the computed value, and the actual 1903-53 subsidence may have been enhanced by a like amount. Thus, while a measure of uncertainty pervades this entire reconstruction, differential subsidence of bench mark 545 B probably was about 0.4 m—roughly comparable with that measured in the Kern Front oil field. Moreover, a subjective argument (see below) indicates that the maximum subsidence centering on the Poso Creek oil field probably was several times that measured at this peripheral mark. The results of repeated surveys through the Mount Poso oil field indicate that the Main area (pi. 1) has sustained significant subsidence clearly associated with oilfield operations. Specifically, bench mark 884 B (pi. 1) rose 0.0893 m with respect to 448 B during the interval 1903-31 (table 2), a period preceding significant production from this field (table 6, fig. 11), whereas this same mark subsided 0.1856 m with respect to 448 B during the interval 1931-63 (table 2). The magnitude of the differential subsidence of 884 B is easily obtained through comparisons with the displacement histories of B-3 1931 and B-7 1931 (pi. 1). Accordingly, depending on the comparison, differential subsidence of bench mark 884 B ranged between 0.3157 and 0.3755 m during the interval 1931-63 (table 2). Regrettably, because this mark is located along the southeast edge of the field, we can only speculate on the maximum differential subsidence that occurred within the Mount Poso field. However, the production statistics (table 6, fig. 11) indicate that the liquid production from this field has been three and four times that in the Kern Front and Poso Creek oil fields, respectively. Thus it is likely that differential subsidence centering on the Mount Poso field may have approached 1.0 m. Finally, because this is the only one of the five fields described here in which two or more sur-32 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA veys preceded significant production, it is also the only one in which we can document an association between subsidence and production in both space and time. The vertical displacement histories of bench marks W 67 and X 67 (pi. 1) together indicate that the subsidence centering on the Fruitvale oil field is almost certainly due to the exploitation of this field. Subsidence of W 67 with respect to 448 B during the period 1926/27/30/ 31-59 was only 0.0541 m (table 2). However, because bench marks F 55 and Y 67 (pi. 1) rose 0.0340 and 0.0428 m with respect to 448 B during the periods 1926/27/30/ 31-57 and 1926/27/30/31-59, respectively (table 2), differential subsidence centering on the Fruitvale field probably approached 0.1 m between the initiation of significant production in 1929 (table 7, fig. 12) and the 1959 survey. Because the marginally positioned bench mark X 67 sustained measurably significant subsidence with respect to F 55 and Y 67 during the periods 1926/27/30/ 31-57 and 1926/27/30/31-59 (table 2), there is virtually no possibility that the modest subsidence centering on the Fruitvale oil field can be due to other than oil-field operations. Specifically, had X 67 shown no tendency toward differential movement consistent with the subsidence of W 67, it could be reasonably argued that the apparent subsidence of W 67 is the product of nothing more than bench-mark disturbance or some aberration in the measurements. Because production from all four of the subsiding oil fields cited above is essentially water drive, associated with varying but generally trivial gas drive, the magnitude of the measured subsidence seems surprisingly large in all but perhaps the Fruitvale field. That is, the better known examples of oil-field subsidence in California are clearly identified with gas-drive production (see, for example, Castle and Yerkes, 1976). Hence we infer that the observed subsidence in these fields can be traced in large measure to heavy pumpage and resultant compaction drive that simply outpaced edge-water migration. Although significant differential subsidence can be identified with production from all of the other oil fields considered in this report, the Kern River oil field seems to have been virtually devoid of subsidence. Comparisons with 448 B suggest, in fact, that the centrally located marks 768 and 634 B (pb 1) actually rose during the period 1903-68 (table 2). Although a fraction of this apparent uplift certainly is due to compaction-induced subsidence of 448 B, comparisons with several nearby bench marks well outside the field are equally supportive of a general absence of subsidence within the Kern River field. Specifically, during the period 1903-68 and with respect to bench mark 976 B (pi. 1), 768 rose 0.0559 rn and 634 B subsided only 0.0271 m (table 2). Similarly, during the same period and with respect to bench mark 1133, 768 rose 0.0062 m and 634 B subsided 0.0768 m (table 2). Therefore, although the subsidence of 634 B with respect to 1133 cannot be dismissed as negligible, it is nonetheless evident that exploitation-induced subsidence within the Kern River oil field has been nonexistent to trivial. This observation, accordingly, suggests a seeming paradox: the occurrence of subsidence in all of the other oil fields considered here is much more easily explained than is the absence of subsidence in the Kern River field. In other words, by virtually every standard used to evaluate the susceptibility of producing oil fields to extraction-induced subsidence, it is the Kern River rather than any of these other oil fields that should have sustained major subsidence. In comparing it only with the adjacent Kern Front oil field, the Kern River field is characterized by: (1) about four times the production; (2) production from significantly younger units; and (3) production from a median depth that is only slightly more than half that of the Kern Front oil field. In fact, the only feature of the Kern Front field that favors its subsidence over that of the Kern River oil field is the higher, but still relatively minor gas drive associated with the Kern Front production. The absence of significant subsidence in the Kern River oil field probably can be attributed to several factors. The most obvious, although not necessarily the most valid possibility, is that the compressibilities of the reservoir beds included with the Kern River Formation are generally very low. This possibility, moreover, is clearly supported by the inferred depositional environment of the productive facies at the head of the Kern River fan, where the relatively fine-grained and generally more compressible sediments would tend to be winnowed out. Hence, even with the enormous liquid production from the Kern River field (table 3, fig. 8), the compression index of these deposits may have simply precluded significant subsidence, however great the increased effective stress. Alternatively, the absence of subsidence within the Kern River oil field may be related to its close association with the Kern River drainage. That is, we assume that recharge through the Kern River may be introduced into the gently dipping producing beds of this oil field through the spreading grounds of the Kern River flood plain, at least within the area where these beds are neatly truncated by the Kern River (pi. 1). This postulated recharge, in effect, comprises a natural water flood that has acted to preserve reservoir fluid pressures at the near normal hydrostatic levels that characterize pre-exploitation reservoir conditions in most California oil fields. In other words, though Crowder (1952, p. 17) has indicated that water drive in the Kern River oil field is generated by edge-water encroachment from the south and west, it is not unlikely that encroachment from along the south edgePROBABLE NATURE OF THE SURFACE DEFORMATION 33 and, perhaps latterly, the east edge of the oil field (pi. 1) has dominated the production drive throughout most of the history of this field. Significant fault offset athwart the line of natural fluid flow would, of course, operate to inhibit this presumed natural water flooding. However, the trends of the major faults in the Kern River field roughly parallel the direction of maximum dip and are localized in the northern part of the field (pi. 1). The likelihood that natural water flooding has preserved reservoir fluid pressures within the Kern River oil field is supported by the salinities obtained from the produced waters. Zone-water salinities in the Kern River field are given as 3-16 grains/gallon (California Division of Oil and Gas, 1960, p. 139); this contrasts markedly with other southern San Joaquin Valley oil fields which are identified with salinities that range up to 2,700 grains/gallon and probably average over 1,000 grains/gallon (California Division of Oil and Gas, 1960, p. 10-295). Although very low zone-water salinities have been reported from several oil fields north and east of Bakersfield, including the Kern Front (17 grains/gallon—California Division of Oil and Gas, 1960, p. 137), the Kern River field holds the fresh-water purity record among those southern San Joaquin Valley oil fields for which zone-water analyses are given by the California Division of Oil and Gas (1960, p. 10-295). FAULTING The historical faulting along the east margins of the Kern Front and Poso Creek oil fields (pi. 1) is strikingly similar in its general characteristics to that associated with oil-field operations elsewhere in the United States. Of the eleven other recognized examples of surficial faulting around various California and Texas oil fields, seven closely resemble the Kern Front and Poso Creek faulting in that they are high angle, normal, down-thrown on the oil-field side, and generally associated with measured differential subsidence (Yerkes and Castle, 1969). The Kern Front and Poso Creek faulting probably is similar to these seven examples in yet another respect, for it parallels the oil-field boundaries and, hence, probably parallels the inferred isobases of subsidence that ordinarily are more or less concentrically distributed around these oil fields (Yerkes and Castle, 1969, p. 55). Castle and Yerkes (1976, p. 70-72) describe, in addition, three examples of subsurface faulting that accompanied oil-field exploitation in the Los Angeles basin; these examples lend support to a general cause-and-effect relation between oil-field operations and associated faulting, whether such faulting has propagated to the surface or not. Castle and others (1973) show that faulting along the east margin of the Inglewood oil field in the Baldwin Hills of southern California not only developed but should have developed as a result of differential compaction of the producing oil measures. Differential compaction in the Inglewood field, as in the general case, created an annulus of centripetally directed extensional horizontal strain surrounding the subsidence bowl centering on the field; it is this extensional strain, coupled with rebound of the elastically compressed, down-warped section along the edge of the subsidence bowl, that led directly to rupturing and faulting (fig. 13A). The Baldwin Hills faulting, which is probably the best studied example of surficial rupturing associated with oil-field operations in the world (California Department of Water Resources, 1964; Hudson and Scott, 1965; Jansen and others, 1967; Hamilton and Meehan, 1971; Casagrande and others, 1972; Leps, 1972; Castle and others, 1973; Castle and Youd, 1973; Castle and Yerkes, 1976), is similar to the faulting along the margins of the Kern Front and Poso Creek oil fields in the following ways: (1) both were preceded by several decades of production; (2) both were confined essentially to the oil-field periphery; (3) both were accompanied by oilfield subsidence; (4) both were unassociated with local seismic activity; (5) movement occurred largely or entirely on preexisting faults in both the Baldwin Hills and Oildale areas; and (6) faulting in both cases was high angle, normal, and characterized by relative downward movement on the oil-field side. The faulting in the Baldwin Hills and Oildale areas are dissimilar in that: (1) rupturing on the Kern Front fault has extended about 5.2 km and that on the Premier fault more than about 2.7 km—or about six and three times, respectively, the length of the longest rupture recognized in the Baldwin Hills (Castle and Yerkes, 1976, pi. 2); and (2) maximum fault displacement with respect to maximum subsidence PRODUCING | AREA CQNTR ACTIONAL EXTENSIONAL, STRAIN ZONE 'STRAIN ZONE* __________Original surface_ SURpAC6 / Z0NE 0F / VERTICALLY j DIRECTED / ELASTIC / COMPRESSION Base of/ compacting layer A PRODUCING i AREA H CONTRACTIONALi EXTENSIONAL . STRAIN ZONE ^STRAIN ZONE* Original surface Figure 13.—Schematic diagrams illustrating possible modes of failure (faulting) around the periphery of a subsiding oil field. A, the Baldwin Hills model (Castle and Yerkes, 1976, p. 72-74). B, postulated model designed to explain the faulting along the east margins of the Kern Front and Poso Creek oil fields.34 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA is far less in the Baldwin Hills than in either the Kern Front or Poso Creek oil fields—displacements of 0.15-0.18 m associated with 1.73 m of subsidence compared with displacements of more than 0.3 m associated with 0.6-0.9 m of subsidence in at least the Kern Front field and probably the Poso Creek field as well. Cumulative displacements on the Baldwin Hills faults reached a maximum of one-quarter to one-half the theoretical limit; this limit is based on the assumption that subsidence along the trace of the fault was the product of strictly elastic compression of the underlying section (fig. 13A). On the other hand, if we assume the operation of a similar model along the Kern Front fault, the maxiumum displacement measured since 1949 probably closely approaches—if it does not actually exceed—the theoretical limit that can be attributed to elastic rebound. That is, because the maximum differential subsidence in the Kern Front oil field is estimated to have been no more than about 0.6-0.9 m, it seems unlikely that subsidence along the trace of the fault could anywhere have exceeded more than 0.30-0.45 m; hence, for example, measured displacement on the Kern Front fault of at least 0.3 m (pi. 1) suggests either that downwarping of the section along the trace of the fault was nearly entirely elastic, or that simple elastic compaction can account for no more than a fraction of the historical faulting. Alternatively, the observed faulting may be the product of nothing more than differential compaction across the hydrologic (or fluid-pressure) barriers defined by the faults that bound the east margins of both the Kern Front oil field and the Premier area of the Poso Creek oil field. This postulated mechanism is analogous to the one proposed by Holzer (1980) to explain the historical displacements along the Pond-Poso Creek fault near Delano, Calif. Although the simplicity of this model is especially appealing, several general observations suggest that the actual mechanism may be somewhat more complex. Specifically, radially oriented horizontal strain has been recognized in every subsiding oil field where the appropriate measurements have been made (Castle and Yerkes, 1976), such that any explanation, it seems to us, must be able to explain the relation between the presumed presence of this horizontal strain (as well, of course, as the differential subsidence) and the faulting. Moreover, if simple differential compaction across the faults accounted for both the subsidence and the measured vertical separations across the faults, we should expect to find a fairly good correspondence between the two. However, the displacement opposite bench mark B 1931 was significantly greater than the subsidence of this mark, whether referred to 448 B or B-1 1931 (pi. 1; table 2), whereas the displacement opposite 864 was much less than the 1903-68 subsidence of this mark (pi. 1; table 2), most of which probably occurred after 1930 (table 4, fig. 9). Moreover, the general strain pattern described here probably differs from that in the area of the Pond-Poso Creek faulting in several significant ways. For example, though the data do not permit a clear determination, the subsidence gradients across the Kern Front and Poso Creek oil fields probably are much steeper than those in the area of the Pond-Poso Creek faulting. In addition, we infer that the faulting in this area roughly parallels the isobases of equal elevation change, whereas it lies nearly athwart the isobases in the area described by Holzer (1980, p. 1066). There is clearly no way we can exclude simple differential compaction as the source of the faulting in this area, but we doubt that it can fully explain the observed faulting if only because the dips on these faults (toward the centers of the respective fields) would tend to inhibit any vertical separation in the absence of at least modest extensional strain across these faults. Finally, the faulting along the margins of the Kern Front and Poso Creek oil fields may be explained by a “roll back” or “collapse” model based on a presumed attenuation of the hanging-wall block (fig. 13B). Specifically, if we assume that the radially oriented extensional strain characteristically developed around subsiding oil fields is linearly related to the subsidence gradient, we can calculate approximate values for both the extensional strain and the maximum likely horizontal displacement that could have been generated athwart a fault paralleling the subsidence isobases in at least the Kern Front field, by simple comparison with actually measured values in the Baldwin Hills. Thus, on the one hand, by 1958 (when faulting was first clearly recognized in the Baldwin Hills) the average subsidence gradient developed across the Inglewood oil field was about 700 mm/km (Castle and Yerkes, 1976, p. 19-20, pi. 4), whereas on the other hand, the average gradient across the Kern Front field probably has been no more than about 400 mm/km—a figure based on maximum probable subsidence through 1968 of about 0.9 m. Because the maximum extensional strain around the margin of the Baldwin Hills subsidence bowl could have been as much as (but probably was less than) 0.10 percent (Castle and Yerkes, 1976, p. 27-29), it is conceivable that the radially oriented extensional strain surrounding the Kern Front oil field may have been as great as 0.057 percent—and, hence, that the average extensional strain was about 0.028 percent. Thus, in the extreme case, if the radially oriented extensional strain within an hypothesized 1,000-m annulus was taken up entirely through slip along the Kern Front fault, extensional strain of 0.028 percent could have been associated with centripetally directed horizontal displacements athwart the fault of as much as 0.3 m. Accordingly, if the aver-PROBABLE NATURE OF THE SURFACE DEFORMATION 35 age dip on the Kern Front fault is about 70° W., we could anticipate a maximum vertical separation of about 0.8 m associated with a postulated horizontal displacement of 0.3 m. Because the actually measured vertical separation on the Kern Front was only about one-half this figure, the “roll back” model (fig. 13B) may account for at least a part of the historical faulting observed along the edges of both the Kern Front and Poso Creek oil fields. Analogies with the several examples cited by Yerkes and Castle (1969), and especially that of the Baldwin Hills (Castle and others, 1973; Castle and Yerkes, 1976), strongly support the conclusion that the historical faulting measured along the edges of the Kern Front and Poso Creek oil fields is also attributable to oilfield operations. Although historical movement on these faults may have involved other processes as well, the nature of this movement has been such that it is very unlikely that it could have occurred in the absence of oilfield operations. SURFACE MOVEMENTS ATTRIBUTABLE TO TECTONIC ACTIVITY Because southern California is recognized as an area of continuing tectonic activity, all the surface movements described here could be interpreted as products of this activity. However, we are inclined to concur with Gilluly and Grant (1949, p. 488) who observed that “causes of tectonic movements are so obscure that it is always possible to assert their effectiveness without the possibility of direct disproof; in the nature of the case, the demonstrated adequacy of another mechanism known to be operative and competent to produce the observed effects can only make it unnecessary to appeal to the unknown tectonic forces.” HEIGHT CHANGES Studies of differential subsidence centering on oil fields around the world have shown repeatedly that this subsidence can be attributed to fluid extraction and resultant compaction of the petroleum reservoir beds (Gilluly and Grant, 1949; Poland and Davis, 1969; Yerkes and Castle, 1969; Poland, 1972; Castle and Yerkes, 1976); hence we need not “appeal to unknown tectonic forces” in order to explain the differential subsidence within or around the Kern Front, Poso Creek, Mount Poso, and Fruitvale oil fields. We insist, in fact, that the burden of proof lies with those who choose to attribute this subsidence to tectonic activity. Accordingly, it seems inescapable that the subsidence we describe here (pi. 1; table 2) can, at best, be only incidentally associated with tectonic activity. Clearly tectonic deformation in the Oildale area is suggested especially by the history of movement at bench marks B-2 1931, B-3 1931, and B-7 1931 (pi. 1). Specifically, northeastward from Oildale these marks rose by progressively increasing amounts during the interval 1931-63, reaching a maximum of +0.1899 m at B-7 1931 (table 2). This is the largest positive signal revealed through comparisons of any of the vertical control data incorporated in this report, and it is unlikely that more than about 0.05 m of this displacement can be dismissed as the product of compaction beneath 448 B. Indeed, since compaction-induced subsidence of bench mark B-0 1931 (pi. 1) probably has been trivial (see section on “Surface Deformation Attributable to Ground-water Withdrawals”), referencing these movements to B-0 1931 indicates that relative tectonic uplift through the period 1931-63 probably reached a maximum (at B-7 1931) of about 0.1533 m (table 2). Owing to the relative stability between bench marks B-l 1931 and B-2 1931 (table 2), a minor element of ambiguity attaches to the interpretation of these displacements as tectonic. That is, although there is certainly no necessity that what we interpret as a generally up-to-the northeast tilt need be expressed as a uniformly smooth feature, the 1931-63 uplift of B-l 1931 seems an unexpectedly large aberration on a regionally developed tectonic tilt. In fact, however, a significant fraction of the differential uplift of B-1 1931 could be the product of artificially-induced rebound of the eastern or footwall block of the Kern Front fault (see section on “Surface Movements Attributable to Oil-field Operations”). Because the interval 1931-63 includes both the 1952 Kern County earthquake and the inception of the southern California uplift (and perhaps still other unrecognized tectonic events), the nature of this apparent tectonic tilting remains uncertain. However, because the 1931-63 uplift seems to have increased significantly to the northeast (away from the White Wolf fault), it seems unlikely that this tilting could have been a coseismic effect associated with the 1952 shock. FAULTING Two independent lines of evidence suggest a tectonic contribution to the historical displacements recognized along the faults bordering the Kern Front and Poso Creek oil fields. (1) Movement, insofar as we are aware, has been confined to the traces of throughgoing faults that show clearly defined evidence of prehistoric Quaternary activity which certainly had its origins in the tectonic evolution of this region. Thus there exists an inverse uniformitarian basis for assuming that any contemporary movement on these faults must be attributable to the same tectonic forces that were responsible for the prehistoric displacements. (2) The largest,36 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA cumulative historical displacements measured along the surface trace of at least the Kern Front fault (pi. 1) cannot, as we have already observed, be completely and unambiguously explained as the product of oil-field exploitation. Accordingly, tectonic activity could account for an undetermined and otherwise doubtfully explained fraction of this movement. The occurrence of any normal faulting and the size of any associated displacements on the Kern Front and Poso Creek faults are functions of both the orthogonally directed extensional horizontal strain across these faults and any differential uplift to the east—of whatever origin. Because tectonically generated uplift east of these faults, even if only of trivial dimensions, would tend to increase both the extensional strain and any resultant displacements on the fault, the differential uplift of bench mark B-2 1931 (table 2) suggests a tectonic basis for a part of the historical movement on at least the Kern Front fault. CONCLUSION Historical surface movements in the Oildale area, though in some ways small in comparison with similar movements elsewhere, are significant if only because they demonstrate the complex interaction among various natural and artificial processes. Height changes described in this paper probably can be explained largely as a result of subsurface compaction associated with fluid extraction and resultant reservoir pressure decline, coupled with modest up-to-the-east tectonic tilting. The historical rupturing along the surface traces of the Kern Front and Premier faults, which are among the longest examples recognized in the United States of both movement on historically aseismic faults and faulting associated with oil-field operations (Bonilla, 1967, p. 17-18, table 1; Yerkes and Castle, 1969, p. 61), can also be explained largely as the product of exploitation and resultant subsurface compaction. However, even though it is very unlikely that the observed faulting could have occurred in the absence of operations in the Kern Front and Poso Creek oil fields, a small, undetermined fraction of this historical movement is conceivably attributable to continuing tectonic activity along the west ramp of the Sierra Nevada. SUPPLEMENTAL DATA: AN APPRAISAL OF COMPACTION-INDUCED SUBSIDENCE IN THE CENTRAL BAKERSFIELD AREA Rigorous analysis of the available geodetic data, coupled with a limited assessment of the local hydrologic history, strongly support Lofgren’s (1975, p. D15) basic thesis: namely, that the apparent (and, by inference, compaction-induced) subsidence of those bench marks around the edge of the southern San Joaquin Valley in general and those in central Bakersfield in particular is actually due to the generally positive movement of the control points to which the various adjustments have been referred. This analysis, however, is significantly complicated by the occurrence of at least four and perhaps five major tectonic displacements of Bakersfield during the period 1901-65 (see below). The vertical displacement history of a representative mark in central Bakersfield, 421 B (pi. 1, fig. 14), indicates that Bakersfield was actually rising with respect to San Pedro during the period 1930/31-72/74 in which compaction-induced subsidence should have been accelerating. Moreover, height changes referred to Tidal 8, San Pedro, are biased toward the recognition of subsidence, such that the significance of at least a part of the subsidence shown by 421 B should be discounted. Specifically, bench mark Tidal 8 is located adjacent to an automatic tide gauge identified with a history of relatively positive movement that has exceeded the rise in eustatic sea level and probably has been rising at something less than 2 mm/yr with respect to an invariant datum (Hicks, 1972, p. 23; Hicks and Crosby, 1975). Alternatively, if we assume that the San Diego tide station has remained more or less invariant during the full period of its occupation—as suggested by geologic studies (McCrory and Lajoie, 1979)—we would be forced to conclude as a corollary that the San Pedro station has been rising at about 1.3 mm/yr with respect to a fixed datum. The acceptance of either of these estimates indicates, for example, that about 0.039-0.058 m of the 1926-53/55 subsidence of 421 B (fig. 14) should be attributed to relative uplift of Tidal 8. In addition, although 421 B subsided 0.1770 m during the period 1914-26, this subsidence accumulated (albeit irregularly) over virtually the entire line extending northward from Pacoima (fig. 1); hence the subsidence that occurred at 421 B must have been largely if not entirely tectonic. Similarly, although 421 B apparently subsided 0.3-0.4 m between 1926 and 1930/31, because this subsidence increased smoothly southward from Chowchilla (fig. 1), it is very unlikely that the 1926-30/31 (or 1901-30/31) subsidence of 421 B was other than tectonic. Again, although the available geodetic evidence neither confirms nor refutes either possibility, the 1930/31-53/55 uplift could have been chiefly aseismic and may have closely followed the 1926-30/31 collapse. Alternatively, of course, it may have accompanied the 1952 M 7.7 Arvin-Tehachapi earthquake, the product of a major left-lateral thrust event on the White Wolf fault (Oakeshott and others, 1955). The geodetic evidence (fig. 14) convincingly supports the idea that central Bakersfield sustained signifi-HEIGHT, IN METERS SUPPLEMENTAL DATA 37 Figure 14.—Changes in orthometric height at bench mark 421 B, Bakersfield, Calif., with respect to Tidal 8 (or nearby equivalents, bench marks A or I 33), San Pedro (fig. 1). (1) Based on leveling via Saugus, Palmdale, and Mojave (fig. 1). (2) Based on leveling via Saugus and Lebec (fig. l).The “1901” height is based on the results of 1897 third-order, double-rodded leveling between San Pedro and Pacoima (fig. 1) and 1902 second-order, double-rodded leveling between Pacoima and Bakersfield. The 1914 height is based on the results of second-order, double-run leveling. The 1930/31 height is based on the results of 1897/1902 third- and second-order leveling between San Pedro and Chowchilla (fig. 1), an assumption of invariance at bench mark 241 B, Chowchilla, during the interval 1897/1902-1930/31, and 1930/31 first-order leveling between Chowchilla and Bakersfield. Although it is unlikely that 241 B subsided in response to groundwater withdrawals during this period (Poland and Davis, 1969, p. 240-247), the location of Chowchilla along the south edge of a large reentrant of older rocks into the central valley (Jennings, 1977) that sustained rapidly accelerating arching during late Quaternary time (Marchand, 1977; D. G. Herd, oral commun., 1979) suggests that 241 B may have experienced modest uplift during the period 1897/1902-1930/31; hence the 1930/31 height probably is underestimated. All other heights are based exclusively on the results of first-order surveys. Orthometric corrections based on observed or interpolated gravity. Error bars show conventionally estimated random error only. Observed elevation data from U.S. Geological Survey field books 5718-5749, U.S. Geological Survey summary books 9114 and 9679, and National Geodetic Survey lines 82466, 82583, 82598, L-198, L-14778, L-14799, L-15577, L-19752, L-20130, L-20145, L-20169, L-20279, L-20298, L-22757, L-23611, L-23614, L-23644, L-23673, L-23675, L-23677, and L-23691.38 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA cant subsidence during the periods 1914-26 and 1926-30/ 31, whereas it sustained net uplift during the periods 1897/1902-1914, 1897/1902-1926, 1930/31-72/73/74, and 1953/55-72/73/74. It is entirely conceivable, of course, that any compaction-induced subsidence associated with ground-water withdrawals may have been masked by overwhelming tectonic signals even during those periods of net uplift. Nonetheless, the surface and subsurface hydrologic history, various geologic considerations and the local geodetic record combine in such a way that compaction-induced subsidence in the central Bakersfield area during the full interval 1901-73 must have been trivial (measurably insignificant) to nonexistent. Although we have no knowledge of the hydrologic history of this area prior to 1894, what we know of the post-1894 history indicates that Bakersfield remained free of subsidence attributable to ground-water withdrawals through at least 1930. Discharge from the Kern River increased steadily from about 1905 through 1918 and declined somewhat between 1919 and 1926 (Lof-gren, 1975, p. D17). Because this increased discharge would tend to inhibit any contemporary depletion of the ground-water reservoir (or recharge any earlier depletion owing to percolation through and into the sediments that form the head of the Kern River fan in the Bakersfield-Oildale area), water levels probably remained unchanged or even rose during the period 1905-26 (or 1901-26). In fact, comparisons between 1915 and 1925 ground-water levels in central Bakersfield indicate that they remained virtually static during this decade (Mendenhall and others, 1916, pi. 1; Harding, 1927, map l) . Nonetheless, Harding’s (1927, map 3) studies indicate that water levels declined about 2 m (a figure that probably roughly approximates the seasonal variation) in the area of 421 B during the period 1920-25. Water-level measurements from one of the few observation wells in the Bakersfield area for which we have a pre-1941 history, 29S/27E-26D (pi. 1), show that there was no decline in ground-water levels in this relatively shallow (~15-m) well between 1924 and 1946 and no more than 4-6 m between 1946 and 1959 (California Department of Water Resources, written commun., 1976). Similarly, hydrographs for wells about 6 km southeast of Bakersfield (30S/28E-10N3) and 4 km west-southwest of Bakersfield (29S/27E-34N1) indicate that water levels within the shallow aquifers (perforated at depths of 65 m) declined by no more than 4 m during the intervals 1952-68 and 1952-59, respectively (Lofgren, 1975, pi. 2F). Although these very modest changes followed the period of immediate interest here, they occurred within a period of clearly declining recharge of the producing ground-water reservoir. Because the period 1924-52 was one of generally balanced changes in the Kern River discharge (which, in fact, increased significantly during the decade 1935-45), ground-water declines in the shallow aquifers during the interval 1924-52 must have been significantly less than even the very small declines recognized (in wells 30S/28E-10N3 and 29S/27E-34N1) during subsequent periods and can thus be dismissed as negligible. Although water-level records for the deeper aquifers underlying Bakersfield indicate generally greater declines than those measured at 29S/27E-26D, it is unlikely that even these more precipitous declines could have provoked significant compaction of the reservoir skeleton, particularly during the period 1924-52. Specifically, very few deep-water wells (in excess of 100 m) had been drilled in the Bakersfield area prior to about 1940 (B. E. Lofgren, oral commun., 1976), such that it is unlikely that large water-level declines had occurred within the deeper, confined, or semiconfined aquifers before 1940. However, the hydrograph for well 29S/ 28E-20B1 (pi. 1), which reached a depth of 200 m, shows that water levels in this well declined at an average rate of about 1.3 m/yr between 1940 and 1949 and at about 2.0 m/yr during the period 1950-68 (Lofgren, 1975, pi. 2F). Records obtained from well 29S/28E-19J2 (pi. 1), which bottoms at about 180 m, show that water levels in this well declined at an average rate of about 1.25 m/yr during the period 1941-59 and at a slightly greater rate during succeeding years (California Department of Water Resources, written commun., 1976), and hence roughly corroborate the declines shown by well 29S/ 28E-20B1. However, even given these head declines, it is unlikely that they would have induced significant compaction, for they occurred within a section characterized by coarse clastic deposits identified with the head of the Kern River fan. Both pre- and post-war production in the Bakersfield-Oildale area has been drawn from the semiconsolidated, relatively young and presumably fresh alluvial deposits of the Kern River Formation and, to a lesser extent, a thin veneer of overlying gravels (Smith, 1964; Dale and others, 1966, p. 22, figs. 10 and 29). Because these deposits are much less susceptible to compaction than those distributed around the periphery of the fan, it is unlikely that the shallower aquifers in particular could have sustained more than trivial compaction through 1968, even in the absence of continuing recharge. Moreover, the deeper aquifers penetrated by wells 29S/28E-20B1 and 29S/28E-19J2 are contained within the same formation (the Kern River Formation) that produced massive volumes of oil and water (3.5 x 109 bbls through 1968) from the nearby Kern River oil field (pi. 1), yet at the same time (and for whatever reason) generated little (if any) differential subsidenceSUPPLEMENTAL DATA 39 within this field during the period 1903-68 (see section on “Surface Movements Attributable to Oil-field Operations”). Perhaps the clearest evidence of an absence of compaction associated with ground-water withdrawals from the surficial deposits underlying the Bakersfield-Oildale area during the period 1924-52 derives from the results of local leveling, coupled with a skeletal knowledge of the subsurface hydrologic history around the southeast margin of the southern San Joaquin Valley. Leveling between X 67 and both Y 67 and F 55 (pi. 1) indicates that Y 67 and F 55 rose 7 and 9 mm, respectively, with respect to X 67 during the interval 1926/30-53 (table 2). Yet, as shown by the water-level records for 29S/27E-26D, water-table reductions in this well were no more than 1 or 2 m during this same period and probably even less during the period 1921-44 (Lofgren, 1975, pi. 2A), whereas water-table declines beneath F 55 during the interval 1921-44 were 5-6 m (Lofgren, 1975, pi. 2A). Thus, other things being equal, because most of the pre-1946 ground-water withdrawals were from relatively shallow aquifers, any differential subsidence between these marks attributable to ground-water extraction should have been in a sense opposite to that actually observed. In fact, however, other things have not been equal and the very limited subsidence of X 67 with respect to either Y 67 or F 55 (table 2) is almost certainly due to its proximity to the Fruitvale oil field (pi. 1), a field that may have been associated with as much as 0.1 m of differential subsidence during the period 1926/30-59 (see section on “Surface Movements Attributable to Oilfield Operations”). Similarly, comparisons between observed elevation differences based on first-order leveling between F 55 and a series of marks extending 12 km southward from bench mark P 54 (about 1 km south of the White Wolf fault, fig. 1) to K 54, show that height changes with respect to F 55 during the interval 1926-47 ranged from about -2 mm at P 54 to a maximum of + 27 mm at K 54 (NGS lines 82598, L-12137, and L-12152). Through 1958 none but the northern part of the area between P 54 and K 54 was under irrigation, and a long-term hydrograph for a well (11N/19W-24R1) about 10 km east of P 54 and 8 km south of the White Wolf fault (and, hence, centering on the subsidiary ground-water basin south of the White Wolf), shows that water levels in this area remained essentially unchanged between 1925 and 1946 (Wood and Dale, 1964, p. 71, pis. 5 and 9). Because all the available information indicates that the water-bearing section beneath P 54 sustained little (if any) extraction-induced compaction through at least 1946 and probably through 1958, the stability of F 55 with respect to P 54 suggests that the central Bakersfield area remained equally free of com- paction-induced subsidence between 1926 and 1947. Although this analysis is somewhat questionable owing to the 1926-30/31 tectonic subsidence that occurred at Bakersfield (fig. 14), the preservation of these elevation differences throughout this period of collapse actually enhances the likelihood that the Bakersfield-Oildale area underwent little compaction-induced subsidence during the period 1926-47. That is, because it is much more likely that the Bakersfield marks experienced subsidence associated with ground-water withdrawals during the interval 1926-47 than did those bench marks south of the White Wolf fault, it follows either that the Bakersfield-Oildale area could not have sustained any significant subsurface compaction between 1926 and 1947 or, alternatively (and much more unlikely in our judgment), that the 1926-30/31 tectonic subsidence south of the White Wolf was markedly greater than that at Bakersfield. Indeed, we strongly suspect that tectonic activity during the interval 1926-47 accounts for the modest (27 mm) uplift of K 54, a mark that lies well within the Tehachapi Range. Subsidence associated with ground-water withdrawals in the central Bakersfield area during the post-1952 (post-earthquake) period is, in some ways, much more easily assessed than any that might have occurred prior to 1953. Specifically, the results of first-order levelings between bench mark 421 B, Bakersfield, and Tidal 8, San Pedro, show that 421 B rose 0.0514 m and 0.0989 m during the periods 1953/55-65 and 1953/55-72/ 74, respectively (fig. 14). Nevertheless, even if we accept the observation that 421 B rose with respect to Tidal 8 during the period 1953/55-72/74, we are again left with the possibility that tectonic uplift of 421 B may have masked measurably significant compaction-induced subsidence beneath this mark. However, a variety of arguments indicate that there was virtually no subsidence of central Bakersfield associated with ground-water withdrawals diming the period 1953-59. For example, comparisons among observed elevation differences based on first-order levelings (NGS lines L-14778 and L-17166) between bench mark S 89 (pi. 1) and several representative marks along the southeast edge of the San Joaquin Valley suggest that any subsidence of S 89 accompanying water-level declines beneath this mark during the interval 1953-59 must have been trivial. On the one hand, bench mark Bank AZ, situated about 20 km east-southeast of S 89 and about 5 km east of the east edge of the Edison oil field, subsided about 20 mm with respect to S 89 during the interval 1953-59. Bank AZ overlies a generally coarse, clastic ± 100 m section of the Kern River Formation and older fan deposits; this section in turn overlies indurated Miocene rocks (J. A. Bartow, oral commun., 1980) that crop out less than 240 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA km to the north and in apparently normal (or uncon-formable) contact with the Kern River Formation (Smith, 1964). On the other hand, bench mark S 55, situated about 35 km east-southeast of central Bakersfield, rose by a similarly small amount (23 mm) with respect to S 89 during the period 1953-59. S 55 lies directly over or immediately adjacent to granitic basement about 5 km northwest of the main trace of the White Wolf fault (Smith, 1964). Although we have no evidence of water-level declines beneath Bank AZ, this does not, of course, preclude their occurrences. Nevertheless, because the semiconsolidated Kern River Formation is three or four times thicker beneath central Bakersfield than it is beneath Bank AZ (J. A. Bartow, oral commun., 1980), there is a much greater likelihood (other things remaining equal) that S 89 would have subsided with respect to Bank AZ rather than vice versa. Moreover, not only did S 89 actually rise with respect to Bank AZ during the interval 1953-59, this uplift occurred during a period in which the subsidence within the unambiguously defined Arvin-Maricopa subsidence basin was actually accelerating (Lofgren, 1975, p. D35-D38). Hence we infer that the surficial deposits that characterize the head of the Kern River fan in the Bakersfield-Oildale area are virtually incompressible, even in the presence of major water-level declines. Owing to the clearly incompressible nature of the natural foundation underlying bench mark S 55, the subsidence of S 89 with respect to S 55 is a seemingly more reliable index of the actual compaction beneath S 89 than is the uplift of this mark with respect to Bank AZ. However, the proximity of S 55 to the White Wolf fault mitigates against the tectonic invariance of this mark during the 1953-59 period of postseismic adjustment. Accordingly, we are finally left with the near certainty that bench marks in the central Bakersfield area could have sustained little if any subsidence associated with ground-water withdrawals during the period 1953-59. Because this 6-year period is especially critical in this context, owing to the generally diminishing discharge of the Kern River and the accelerating subsidence throughout much of the southernmost San Joaquin Valley, it is equally unlikely that the central Bakersfield area could have sustained significant subsidence associated with ground-water withdrawals during any subsequent years through at least 1968. REFERENCES CITED Albright, M. B., Hluza, A. G., and Sullivan, J. C., 1957, Mount Poso oil field, in Summary of operations, California oil fields, forty-third annual report of the state oil and gas supervisor: California Division of Oil and Gas, v. 43, no. 2, p. 5-20. Bartow, J. A., and Pittman, G. M., 1983, The Kern River Formation, southeastern San Joaquin Valley, California: U.S. Geological Survey Bulletin 1529-D [in press]. Birdseye, C. H., 1925, Spirit leveling in California, 1896-1923: U.S. Geological Survey Bulletin 766, 748 p. Bonilla, M. G., 1967, Historic surface faulting in continental United States and adjacent parts of Mexico: U.S. Geological Survey open-file report, 36 p.; also U.S. Atomic Energy Commission Report TID-24124, 36 p. Bradley, W. W., 1917, California mineral production for 1916: California State Mining Bureau Bulletin 74, 179 p. -------1918, California mineral production for 1917: California State Mining Bureau Bulletin 83, 179 p. -------1920, California mineral production for 1919: California State Mining Bureau Bulletin 88, 204 p. Brooks, T. J., 1952a, Kern Front oil field, in AAPG, SEPM, SEG field trip routes, oil fields, geology: American Association of Petroleum Geologists Annual Meeting, Los Angeles, California, March 1952, p. 159-161. -------1952b, Kern River oil field, in AAPG, SEPM, SEG field trip routes, oil fields, geology: American Association of Petroleum Geologists Annual Meeting, Los Angeles, California, March 1952, p. 156-158. California Department of Water Resources, 1964, Investigation of failure, Baldwin Hills Reservoir: California Department of Water Resources, 64 p. California Division of Oil and Gas, 1960, California oil and gas fields— part 1, San Joaquin-Sacramento Valleys and northern coastal regions: California Division of Oil and Gas, San Francisco, 493 p. -------1968, Production statistics 1968, in Summary of operations, California oil fields, fifty-fourth annual report of the state oil and gas supervisor: California Division of Oil and Gas, v. 54, no. 2, part 1, 128 p. -------1972, Oil and gas statistics, in Summary of operations, oil, gas and geothermal production statistics, fifty-eighth annual report of the state oil and gas supervisor: California Division of Oil and Gas, v. 58, no. 2, p. 61-166. Casagrande, Arthur, Wilson, S. D., and Schwantes, E. D., Jr., 1972, The Baldwin Hills Reservoir failure in retrospect: Proceedings of Specialty Conference on Performance of Earth and Earth-Supported Structures, Purdue University, June 12-14, 1972, American Society of Civil Engineers, New York: v. I, pt. 1, p. 551-588. Castle, R. O., Church, J. P., and Elliott, M. R., 1976, Aseismic uplift in southern California: Science, v. 192, p. 251-253. Castle, R. O., and Yerkes, R. F., 1976, Recent surface movements in the Baldwin Hills, Los Angeles County, California: U.S. Geological Survey Professional Paper 882, 125 p. Castle, R. O., Yerkes, R. F., and Youd, T. L., 1973, Ground rupture in the Baldwin Hills—an alternative explanation: Association of Engineering Geologists Bulletin, v. 10, p. 21-46. Castle, R. O., and Youd, T. L., 1973, The Baldwin Hills Reservoir failure: Discussion: Proceedings of Specialty Conference on Performance of Earth and Earth-Supported Structures, Purdue University, June 12-14, 1972, American Society of Civil Engineers, New York, v. Ill, p. 91-99. Church, H. V., Jr., and Krammes, Kenneth (chm.), and others, 1957, Cenozoic correlation section across south San Joaquin Valley from San Andreas fault to Sierra Nevada foothills, California: American Association of Petroleum Geologists, Geologic Names and Correlations Committee, San Joaquin Valley Subcommittee on the Cenozoic, scale about 1 inch to 1-1/2 miles. Crowder, R. E., 1952, Kern River oil field, in Summary of operations, California oil fields, thirty-eighth annual report of the state oil and gas supervisor: California Division of Oil and Gas, v. 38, no. 2, p. 11-18.REFERENCES CITED 41 Dale, R. H., French, J. J., and Gordon, G. V., 1966, Ground-water geology and hydrology of the Kern River alluvial-fan area, California: U.S. Geological Survey open-file report, 92 p. de Laveaga, M., 1952, Oil fields of central San Joaquin Valley province, in AAPG, SEPM, SEG field trip routes, oil fields, geology; American Association of Petroleum Geologists Annual Meeting, Los Angeles, California, March 1952, p. 99-105 Dibblee, T. W., Jr., and Chesterman, C. W., 1953, Geology of the Breckenridge Mountain quadrangle, California: California Division of Mines Bulletin 168, 56 p. Gilluly, James, and Grant, U. S., 4th, 1949, Subsidence in the Long Beach Harbor area, California: Geological Society of America Bulletin, v. 60, p. 461-529. Hamilton, D. H., and Meehan, R. L., 1971, Ground rupture in the Baldwin Hills: Science, v. 172, p. 333-344. Harding, S. T., 1927, Ground water resources of the southern San Joaquin Valley: California Department of Water Resources, Bulletin 11, 146 p. Hicks, S. D., 1972, On the classification and trends of long period sea level series: Shore and Beach, v. 40, no. 1, p. 20-23. Hicks, S. D., and Crosby, J. E., 1975, An average long-period, sea-level series for the United States: National Oceanic and Atmospheric Administration, Technical Memorandum NOS 15, 6 p. Hill, M. L., 1954, Tectonics of faulting in southern California, chap. 4, in Jahns, R. H., ed., Geology of southern California: California Division of Mines Bulletin 170, p. 5-13. Hilton, G. S., McClelland, E. J., Klausing, R. L., and Kunkel, Fred, 1963, Geology, hydrology, and quality of water in the Terra Bella-Lost Hills area, San Joaquin Valley, California: U.S. Geological Survey open-file report, 158 p. Holzer, T. L., 1977, Ground failure in areas of subsidence due to ground-water decline in the United States, in Land subsidence symposium: Proceedings of the Second International Symposium on Land Subsidence, Anaheim, California, December 1976, International Association Hydrological Sciences Pub. 121, p. 423-433. ------1980, Faulting caused by groundwater level declines, San Joaquin Valley, California: Water Resources Research, v. 16, p. 1065-1070. Hudson, D. E., and Scott, R. F., 1965, Fault motions at the Baldwin Hills Reservoir site: Seismological Society of America Bulletin, v. 55, p. 165-180. Jansen, R. B., Dukleth, G. W., Gordon, B. B., James, L. B., and Shields, C. E., 1967, Earth movement at Baldwin Hills Reservoir: Journal of Soil Mechanics and Foundations Division, American Society of Civil Engineers, v. 93, SM4, p. 551-575. Jennings, C. W., 1977, Geologic map of California: California Division of Mines and Geology, Geologic Data Map series, scale 1:750,000. Johnston, R. L., 1955, Earthquake damage to oil fields and to Paloma Cycling Plant in the San Joaquin Valley, in Oakeshott, G. B., ed., Earthquakes in Kern County, California, during 1952: California Division of Mines Bulletin 171, p. 221-225. Johnston, Robert, 1952, Fruitvale oil field, in AAPG, SEPM, SEG field trip routes, oil fields, geology: American Association of Petroleum Geologists Annual Meeting, Los Angeles, California, March 1952, p. 122-123. Koch, T. W., 1933, Analysis and effects of current movement on an active fault in Buena Vista Hills oil field, Kern County, California: American Association of Petroleum Geologists Bulletin, v. 17, p. 694-712. Leps, T. M., 1972, Analysis of failure of Baldwin Hills Reservoir: Proceedings of Specialty Conference on Performance of Earth and Earth-supported Structures, Purdue University, June 12-14, 1972, American Society of Civil Engineers, New York: v. 1, pt. 1, p. 507-550. Lofgren, B. E., 1966, Tectonic movement in the Grapevine area, Kern County, California, in Geological Survey research 1966: U.S. Geological Survey Professional Paper 550-B, p. B6-B11. ------1975, Land subsidence due to ground-water withdrawal, Arvin- Maricopa area, California: U.S. Geological Survey Professional Paper 437-D, 55 p. Marchand, D. E., 1977, The Cenozoic history of the San Joaquin Valley and adjacent Sierra Nevada as inferred from the geology and soils of the eastern San Joaquin Valley, in Singer, M. J., ed., Soil development, geomorphology, and Cenozoic history of the northeastern San Joaquin Valley and adjacent areas, California: Guidebook for the Joint Field Session of the American Society of Agronomy, Soil Science Society of America and the Geological Society of America, Modesto, California, November 10-13, 1977, p. 39-50. Mathews, J. F., Jr., 1957, McVan area of Poso Creek oil field, in Summary of operations, California oil fields, forty-third annual report of the state oil and gas supervisor: California Division of Oil and Gas, v. 43, no. 1, p. 24-28. McCrory, P. A., and Lajoie, K. R., 1979, Marine terrace deformation, San Diego County, California [abs.]: Tectonophysics, v. 52, p. 407-408. McLaughlin, R. P., 1914, Kern River field, chap. V, in Petroleum industry of California: California State Mining Bureau Bulletin 69, p. 195-216. Mendenhall, W. C., Dale, R. B., and Stabler, Herman, 1916, Ground water in San Joaquin Valley, California: U.S. Geological Survey Water-Supply Paper 398, 310 p. Morton, D. M., 1977, Surface deformation in part of the San Jacinto Valley, southern California: U.S. Geological Survey Journal of Research, v. 51, p. 117-124. Nason, R. D., Philippsbom, F. R., and Yamashita, P. A., 1974, Catalog of creepmeter measurements in central California from 1968 to 1972: U.S. Geological Survey Open-File Report 74-31, 287 P- Oakeshott, G. B., and others, ed., 1955, Earthquakes in Kern County, California during 1952: California Division of Mines Bulletin 171, 283 p. Park, W. H., 1965, Kern Front oil field, in Summary of operations, California oil fields, fifty-first annual report of the state oil and gas supervisor: California Division of Oil and Gas, v. 51, no. 1, p. 13-22. Pease, E. W., 1952, Mount Poso group oil fields, in AAPG, SEPM, SEG field trip routes, oil fields, geology: American Association of Petroleum Geologists Annual Meeting, Los Angles, California, March 1952, p. 150-151 Poland, J. F., 1972, Subsidence and its control, in Underground waste management and environmental implications: American Association of Petroleum Geologists Memoir 18, p. 50-71. Poland, J. F., and Davis, G. H., 1969, Land subsidence due to withdrawal of fluids, in Vames, D. J., and Kiersch, George, eds., Reviews in engineering geology, vol. II: Boulder, Colorado, The Geological Society of America, p. 187-269. Smith, A. R., compiler, 1964, Geologic map of California, Olaf P. Jenkins edition, Bakersfield sheet: California Division of Mines and Geology, scale 1:250,000. U.S. Coast and Geodetic Survey, 1966, Vertical control data: U.S. Coast and Geodetic Survey Quadrangle 351192, 113 p. Vanicek, P., Castle, R. O., and Balazs, E. I., 1980, Geodetic leveling and its applications: Reviews of Geophysics and Space Physics, v. 18, p. 505-524. Weddle, J. R., 1959, Premier and Enas areas of Poso Creek oil field, in Summary of operations, California oil fields, forty-fifth annual report of the state oil and gas supervisor: California Division of Oil and Gas, v. 45, no. 2, p. 41-50.42 HISTORICAL SURFACE DEFORMATION NEAR OILDALE, CALIFORNIA Welge, E. A., 1973, Poso Creek oil field, McVan area, in Summary of operations, fifty-ninth annual report of the state oil and gas supervisor: California Division of Oil and Gas, v. 59, no. 1, p. 59-68. Whitten, C. A., 1961, Measurement of small movements in the earth’s crust: Annales Academiae Scientiarum Fennicae, Ser. A, III. Geologica-Geographica Suomalainen Tiedeakatemia, p. 315-320. Wood, P. R., and Dale, R. H., 1964, Geology and ground-water features of the Edison-Maricopa area, Kern County, California: U.S. Geological Survey Water-Supply Paper 1656, 108 p. Yerkes, R. F., and Castle, R. 0., 1969, Surface deformation associated with oil and gas field operations in the United States, in Land subsidence: International Association of Science Hydrology-UNESCO, pub. no. 88, v. 1, p. 55-66. QE ft* ]/. ^ljS UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY \ Dominion 1 MOUNT Grand \ I \ \l I X\1 |POSO \ McVan POSO Baker-Grover . area—_J Dorsey \area remier area CREEKlv FIELD 1 KERN / FRONT FIELD- / / FIELD FRUITVALE FIELD " Oif9S/28E-19J2 ^ ! BAKEfc'Krtl.uSi 9S/28E-1902^>^' ArnmspN t6r¥&A ;Maguni3fen. Mayfair 119°07'30" 35°40' 1 ia°n(V 37’30" 32 '30" 27’30" 27'30" T. 29 S. 118°52'30" 35°40' 37'30" 32'30' 22'30" 22'30" T. 30 S. T. 30 S. Base from U.S. Geological Survey North of Oildale, Knob Hill. Oildale, Oil Center (1970), Gosford, (1954), Lamont (1954), Deepwell Ranch (1952), and Sand Canyon (1965) 1:24 000 CONTOUR INTERVAL 20 FEET DOTTED LINES REPRESENT 10-FOOT CONTOURS NATIONAL GEODETIC VERTICAL DATUM OF 1929 35°20' 119°07'30" SCALE 1:62 500 8 KILOMETERS ~I 4 MILES 2'30" 119°00' R. 28 E. 57'30” 35°20’ 118°52'30" PROFESSIONAL PAPER 1245 PLATE 1 EXPLANATION 225 100 300 ^oLQjLoi- Historic fault trace Dashed where approximately located. Numbers show vertical separations in mm. U, upthrown side; D, downthrown side Fault mapped at surface (not shown in sections) Dashed where approximately located; queried where doubtful Fault revealed in subsurface (those shown in sections included only in part with those shown on map and vice versa) Dashed where approximately located. Traces shown on surfaces ranging from 100—1300 m below ground level \ .(Semiconsoliated (unconsolidate^consolidated) Boundary between unconsolidated and semiconsolidated or consolidated deposits • 448 B Bench mark Boundary of oil-producing area q29S/28E-20B1 Water well -------B " B B Location of cross section Faults mapped at surface after Hilton and others (1963, fig. 3). Faults at depth chiefly from Albright and others (1957, pi. II), Brooks (1952a, p. 159; 1952b, p. 158), Johnston (1952, p. 123), Weddle (1959, pi. II) and Welge (1973, pi. II); southern boundary fault of the Kern River oil field from California Division of Oil and Gas (1960, p. 138). Boundaries of oil-producing areas generalized from distribution of oil wells shown on U.S. Geological Survey Gosford, Knob Hill, North of Oildale, Oil Center, Oildale, and Sand Canyon 1:24,000—scale 7Vi' topographic quadrangle maps. Contact between unconsolidated and semiconsolidated deposits after Smith (1964). Geologic sections for Kern Front, Kern River, and Mount Poso oil field modified from Brooks (1952a, p. 160; 1952b, p. 156-157); Dibblee and Chesterman (1953), Albright and others (1957, pi. HI), and Bartow and Pittman (1983). Stratigraphic nomenclature and section for Poso Creek oil field from Weddle (1959, pi. Ill) A A' B B B" nr FEET - 1500 - 1000 - 500 SEA LEVEL - 500 - 1000 - 1500 - 2000 - 2500 Pleistocene (?), Pliocene, and Miocene Miocene c METERS C' FEET 300 - POSO CREEK OIL FIELD - 900 200 - - 600 100 - - 300 SEA SEA LEVEL LEVEL 100 - - 300 200 - / aV - 600 300 - Kern River Formation Kern River Formation /.'A Uy - 900 "Upper" Etchegoin /A "Upper" Etchegoin ' ' \ 400 - // Macoma claystone, j \ 1200 500 - - 1800 -7^Basal Etchegoin sand^ Chanac • Formation - 2100 Chanac Formation / L 2400 Pleistocene (?), Pliocene, and Miocene mi FEET - 1800 - 1500 - 1200 - 900 - 600 - 300 SEA LEVEL - 300 - 600 - 900 - 1200 - 1500 - 1800 Pleistocene (?), Pliocene, and Miocene X Miocene Miocene to/ Eocene Mesozoic MAP AND CROSS SECTIONS SHOWING MAJOR STRUCTURAL FEATURES AND OIL PRODUCING AREAS NEAR OILDALE, CALIFORNIAUNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY ^5 f/sy PROFESSIONAL PAPER 1245 PLATE 2 448 B / 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 0.6148 0.6148 0.6148 0.6148 R 364 / 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 2.1412 2.1778 2.1778 2.7926 2.7926 ORTHOMETRICALLY CORRECTED OBSERVED ELEVATION DIFFERENCES AMONG SELECTED BENCH MARKS IN THE OILDALE AREA AT VARIOUS TIMES SINCE 1903 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 12.4292 12.4368 13.0439 13.0516 10.2514 C747 Reset y Note: Elevation differences in meters. The magnitude of any height change at a given bench mark with respect to any control point listed in this table may be calculated directly by comparing sucessive elevation differences in the box relating the identified control point to the bench mark; the sense of movement may be deduced from the elevations listed in table 1. Locations shown on plate 1. 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 20.5884 20.5771 21.2031 21.1919 8.1592 8.1403 E747 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 47.4258 47.5276 47.5282 48.1423 48.1430 45.2845 45.3498 35.0984 35.0914 26.9511 B-l 1931 / 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 56.6213 56.6496 57.2644 44.2129 36.0725 9.1215 634 B / 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 87.6625 87.6549 87.6210 88.2696 88.2358 85.5213 85.4771 75.2257 75.1843 67.0439 40.2367 40.1273 40.0929 30.9714 B 1931 y^ 1903 1926727/30/31 1931 1953 1957 1959 1963 1968 97.5319 97.6432 98.2580 85.2064 77.0661 50.1150 40.9106 40.9935 10.0221 768 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 126.7340 126.4246 127.0394 113.9878 105.8475 78.8964 70.1127 69.7750 38.8036 29.2020 28.7814 864 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 133.8593 133.8736 134.4741 134.4884 131.6815 121.4301 121.4368 113.2965 86.3317 86.3454 77.2240 46.2044 46.2526 36.2304 7.4490 29-0 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 161.1088 161.1642 161.7790 148.7275 140.5871 113.6361 104.4875 104.5146 73.5432 63.5768 63.5211 34.3748 34.7396 27.2906 976 B 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 182.4924 182.6042 182.6259 183.2190 183.2406 180.3511 180.4264 170.1751 170.1891 162.0488 135.0666 135.0767 135.0977 125.9762 94.8299 94.9494 95.0048 84.9827 56.2013 48.7449 48.7522 21.4616 B-2 1931 / 1903 1926/27/30/31 1931 1953 1957 1959 1963 -1968 208.6534 208.7585 209.3733 196.3218 188.1815 161.2304 152.1089 121.1375 111.1154 82.3340 74.8849 47.5943 26.1326 1133 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 231.0541 231.0986 231.6689 231.7134 228.8763 218.6249 218.6618 210.5215 183.5265 183.5704 174.4490 143.3992 143.4776 133.4554 104.6740 97.1948 97.2250 69.9344 48.4499 48.4727 22.3401 Oil Hill A X~ 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 230.8069 230.9017 231.5165 218.4649 210.5008 183.3735 174.1856 174.2521 143.2807 133.2750 133.2585 104.0729 104.4771 97.0281 69.6981 69.7375 48.2758 22.1535 22.1432 0.1969 1205 (Mon. leaning, 1968) X" 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 97.1598 97.2899 97.9047 94.8460 95.1121 49.7340 49.7623 9.4973 9.6350 85.3326 85.3143 B-3 1931 X^ 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 29.5815 29.24931 29.8641' 27.0398 67.9504 97.1525 131.5273 179.0719 201.2254 545 B y^ 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 56.3512 56.4411 9.0153 0.2700 31.2213 41.1807 70.3827 104.7575 126.0512 152.3021 174.4556 40.7186 26.7697 633B y^ 884 B X 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 132.8360 132.9253 132.7397 133.3545 130.7841 130.5619 85.4996 85.2122 45.2628 45.0848 49.5669 49.8644 35.7656 35.4193 76.4848 76.4842 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 245.7141 245.9040 246.5187 243.5728 243.7262 198.2883 198.3764 158.0516 158.2491 63.2217 63.2997. 148.5543 148.6140 112.7887 113.1642 B-7 1931 X TBM 1266 X" 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 249.6326 249.7914 250.4062 247.4914 247.6136 202.2068 202.2638 161.9701 162.1365 67.1402 67.1872 152.4728 152.5015 193.1914 116.7072 117.0516 3.9185 3.8874 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 2.9721 2.9569 2.9585 2.9595 2.3421 2.3437 2.3447 P 89 X- 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 3.2260 3.2142 3.2166 3.2183 2.5994 2.6018 2.6035 0.2539 0.2573 0.2581 0.2588 Q 89 /— 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 13.2306 13.1968 13.1966 12.5820 12.5818 10.2585 10.2399 10.2381 10.0046 9.9826 9.9800 F 55 x~ 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 14.8016 14.7703 14.7660 14.7588 14.1555 14.1512 14.1440 11.8295 11.8134 11.8075 11.7993 11.5756 11.5561 11.5495 11.5404 1.5710 1.5785 1.5694 Y 67 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 13.7289 13.7045 13.7042 13.6953 13.0897 13.0894 13.0805 10.7568 10.7476 10.7457 10.7358 10.5029 10.4903 10.4876 10.4770 0.4983 0.5077 0.5076 1.0727 1.0658 1.0618 1.0635 1903 1926/27/30/31 1931 1953 1957 1959 1963 1968 15.5560 15.5957 15.6085 15.6101 14.9809 14.9937 14.9953 12.5839 12.6388 12.6500 12.6506 12.3300 12.3815 12.3919 12.3918 2.3254 2.3989 2.4119 0.7544 0.8254 0.8425 0.8513 1.8271 1.8912 1.9043 1.9148 ‘Assumes that bench mark B-3 1931 remained unchanged in elevation with respect to 448 B and R 364 between 1953 and 1963. ☆ INTERIOR—GEOLOGICAL SURVEY. RESTON. VIRGINIA-1983-G82723