Areal Geology in the Vicinity of the Chariot Site Lisburne Peninsula Northwestern Alaska By RUSSELL H. CAMPBELL GEOG LOGICAL SURVEY PROFESSIONAL PAP E R 3 9 5 Prepared on behalf of the U.S. Atomic Energy Commission UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY WILLIAM T. PECORA, Director Library of Congress catalog-card No. GS 66-262 EARTH SCIENCES LIBRARY For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 AFIS CC EARTH SCIENCES LIBRARY CONTENTS Page Abstract 1 | Stratigraphy-Continued Introduction and acknowledgments..__...__________. 1 Measured bedrock sections-Continued , Stratigraphy 3 Permian apd Trlas51f: rocks.—We‘st sections ___ Stratigraphic and petrographic methods and Shublik Formation (Triassic) .._... s Siksikpuk Formation (Permian) .._. terminology -- 5 3 ei A anat Permian and Triassic rocks-east sections ___.. Mississippian rocks a Shublik (Triassic)... ._.... Sedimentary rocks undivided _.. . =. ___ __ 5 Siksikpuk Formation (Permian) _______- Lisburne Group T Jurassic or Cretaceous rocks ..____._._._______ Nasorak ForMatio®.._______.__.______ T Telavirak Formation, partial section, Kogruk(?) Formation ..........._.__..____._.. 14 Niyilelik Creek............._._._.. Tupik 18 Unconsolidated deposits_________________.__.___--- Permian and Triassic FOCKS ____________________-- 19 Tertiary or Quaternary deposits ___.. Siksikpuk Formation (Permian) . 19 Tly irak Gravel..............._.._l{ icicle c sct Shublik Formation (Triassic) ____________-_- 20 Saftevik Jurassic or Cretaceous rocks __ Aon aearo ands 20 Quaternary depoSit$________________zzz_z____ Ogotoruk Formation. 20 Stream-terrace deposits ________________--- Telavirak Formation.... 25 Chariot Gravel... .s... ...... 0... Are o Cretaceous rocks 27 Colluvium se Kisimilok Formation.............!...._.__.._.c. 27 Lake, lagoon, and swamp deposits.__________ Fortress Mountain (?) Formation ____________-- 28 Wind-deposited silt and sand ___ Measured bedrock sections ______________- 30 Flood-plain Mississippian rocks-west sections ._______________ 30 Beach deposits of the present shoreline ___. Lisburne Group.......:....... .. 30 | Geologic structure. Nasorak Formation ___. 30 Thrust faults of the western province ________-- Sedimentary rocks undivided ________________ 33 Folding and faulting of the eastern province as Mississippian rocks-east sections ________._____ 34 Age and origin of deformation.__________________- Lisburne 34 | Geomorphology Tuplk Formation ...... L...... 34 | Geologic history _- Kogruk(?) Formation a 35 | References cited h Nasorak Formation.... ...._.._._... 44 | Index % Bras aearo ILLUSTRATIONS Page PLATE 1. Geologic map and structure sections __.. In pocket 2. Photomosaic of sea cliffs In pocket FIGURE 1. Index of geologic mapping by the U.S. Geological Survey on behalf of Project Chariot -~ 2 2. Generalized columnar sections of strata exposed in sea cliffs_________________-- 10 3. Photographs of thin sections showing range of abundance of allochems in Nasorak biomicrites and fossiliferous micrites ___. 11 4. Photographs of thin sections showing biosparite and dolomitized biomicrite from the Nasorak Formation 12 5-12. Photographs of- 5. Rhythmic interbeds of the Nasorak FOrMAtiON______________________- 13 6. Even continuous beds of the Nasorak Formation ____________________. 13 7. Coral head in the Nasorak Formation 14 8. Dolomitized fossiliferous micrite and biomicrite from the Kogruk(?) Formation _ 15 9. Dolomitized sedimentary breccia in the Kogruk(?) Formation ___.. 16 10. Intraformational breccia in the Kogruk(?) Formation _______________ 16 11. Relict current lamination in Kogruk(?) dolomite __________ A 17 12. Distinctive lenticular color mottling in Kogruk(?) dolomite___________. 18 376 III IV CONTENTS FIGURE 13. Generalized composite section of the Ogotoruk, Telavirak, Kisimilok, and Fortress Mountain(?) Formations 14. Photograph of Ogotoruk Creek valley from Crowbill Point _________________ 15. Photograph of phosphorite nodule in mudstone of the Ogotoruk Formation. 16. Triangular diagrams of classification of impure sandstone ___________________ 17-24. Photographs of- 17. Bedding characteristics in the Ogotoruk Formation _________________. 18. Bedding characteristics in the Telavirak Formation ________________ 19. Bottom marks in the Telavirak Formation 20. Bedding characteristics in the Kisimilok Formation ________________ 21. Bedding characteristics and outcrop aspect of some of the mudstone of the Kisimilok Formation 22. Bedding characteristics in the Fortress Mountain(?) Formation ___ 28. Current ripple marks in the Fortress Mountain(?) Formation ___________. 24. Texture of spicular(?) chert in the Nasorak Formation ___ 25. Size distribution curves of samples of unconsolidated deposits _________________ 26-28. Photographs of- 26. Bedding characteristics and structural features in the Telavirak For- mation 27. Fracture cleavage in the Ogotoruk Formation.....__...._._______________._ 28. Fracture cleavage in the Telavirak Formation ____________________ TABLES TABLE 1. Summary of sedimentary rocks and surficial deposits, Chariot site and vicinity, Alaska 2 2. Fossils collected from the Lisburne Group and the underlying mudstone-sand- stone-limestone unit Page AREAL GEOLOGY IN THE VICINITY OF THE CHARIOT SITE, LISBURNE PENINSULA, NORTHWESTERN ALASKA By RUSSELL H. CAMPBELL ABSTRACT Geologic mapping in support of Project Chariot covers about 350 square miles on the southwest side of the Lisburne Peninsula in northwestern Alaska. The area is bounded on the southwest by the Chukchi Sea and on the northeast by a roughly semicircular are having a radius of about 15 miles from the Chariot site at the mouth of Ogotoruk Creek. The exposed bedrock ranges in age from Early Mississip- pian to Cretaceous and crops out in paralled northeast- to north-trending bands in which the rocks are, in general, suc- cessively younger from west to east. The rocks are exclusively sedimentary and probably all marine. No angular unconfor- mities have been observed between bedrock units, and, al- though disconformities may separate several of the units, there is no local evidence of subaerial erosion or other indi- cation of strongly emergent conditions between Early Mis- sissippian and Early Cretaceous times. Limestone and dolo- mite beds of the Lisburne Group, locally of Mississippian age, predominate in the western part of the area. The underlying mudstone, sandstone, and limestone of Early Mississippian age are exposed chiefly on the extreme western side. The eastern half of the area is underlain by flysch facies mudstone and sandstone of Cretaceous and, possibly, Jurassic age. The presence of younger Cretaceous bedrock units some distance to the north and east of the map area suggests that deposits as young as Late Cretaceous may have been deposited and subsequently completely removed by erosion. Although the structural relations are complex and westerly dips are common in the surface exposures, the gross distri- bution of the units indicates a regional dip to the east or south- east. The structure of the western half of the area is domi- nated by north-trending imbricate thrust faults along which rocks of the Lisburne Group have been thrust eastward over Lisburne and younger strata. The rocks of the eastern half have been intensely folded, and broken by high-angle faults, giving a gross impression of plastic deformation. The struc- tures of both halves of the area appear to be related to a single major deformation of Late Cretaceous or early Ter- tiary age. Both the thrusting and folding are interpreted to be relatively shallow features that developed as a result of gravity gliding directed down the regional dip to the east. The Tertiary Period is represented by varied geomorphic features that reflect a long and complex history of erosion and deposition. Most of it was subaerial and fluvial, but marine erosion and deposition are represented by many fea- tures at low altitudes along the coast. In about half the area the bedrock is unconformably overlain by a thin veneer of unconsolidated deposits of Quaternary and, perhaps, late Tertiary age. The surficial deposits are chiefly colluvium, fluvial-terrace and flood-plain deposits, gravel and sand of uncertain origin (fluvial or marine) at high altitude, marine- terrace deposits at low altitude near the shoreline, lake and swamp deposits, wind-deposited silt and sand, and sand and gravel of the modern beach. INTRODUCTION AND ACKNOWLEDGMENTS In 1959 the U.S. Geological Survey was requested by the U.S. Atomic Energy Commission to provide a geologic map at a scale of 1 inch to 1 mile (1:63,860) of the land area within a radius of 15 miles of the Chariot site as a part of bioenvironmental studies in the vicinity of a proposed nuclear test excavation. Geologic mapping in support of the bioenvironmental studies program was done during the summer field seasons of 1959 and 1960 and was an expansion from the mapping done in 1958 (Kachadoorian and others, 1959; Sainsbury and Campbell, 1959) during pre- liminary investigations of the site by the Geological Survey in support of technical site-selection studies by the Atomic Energy Commission. The area mapped is roughly semicircular, bounded on the southwest by the Chukchi Sea and on the northeast by the Kukpuk River. It extends along the coast for 15 miles in either direction from the mouth of Ogotoruk Creek: northwest as far as Kemegrak Lagoon and the north side of the Kemegrak Hills and southeast about a mile beyond Pusigrak Lagoon. Along the Kukpuk River it extends from the vicinity of Ogsa- chak in the northwest (downstream end) to Alolu- krak on the southeast (upstream end) (pl. 1). The area included is approximately 350 square miles and includes all the Point Hope A-2 quadrangle as well as adjacent parts of the Point Hope A-1, B-1, and B-2 quadrangles (fig. 1). The general location and accessibility of the area have been described by Kachadoorian (1961, p. 9). The history of earliest exploration and geologic . work in the area has been described by Collier (1906, p. 6), by Kindle (1909, p. 520-521), and by Smith and Mertie (1930, p. 4-9). Kachadoorian (1961, p. 6-8) has summarized the history of Geological Sur- vey operations in the region on behalf of Project Chariot. The area of the geologic map (pl. 1) is in- cluded on the small-scale geologic maps of Collier 1 166° 30" 68°30' | Point H e B-3 166°00' I Point Hope B-2 165°30' AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA 165°00' Point Hope B-1 Point Hope h KUKPUK RlVpy» 3s 7 Outline of area of geologic map (”mix—Ho? Point Hope A-1 #4 68°15" & N eZ < 3, 141130ch a 084A} 68°00" 5 o 5 FIGURE 1.-Index of geologic mapping by U.S. Geological Survey on behalf of Project Chariot. 1. Kachadoorian, Reuben,-Campbell, R. H., Sainsbury, C. L., and Scholl, D. W., 1959, Geology of the Ogotoruk Creek area, northwestern Alaska: U.S. Geol. Survey TEM-976, open-file: report. la. Plate 1, Geologic map and sections of Ogotoruk Creek area, by Reuben Kachadoorian, R. H. Campbell, C. L. Sainsbury, and D. W. Scholl; scale 1:12,000. 1b. Plate 2, General bathymetry and marine geology of Ogotoruk Creek area, by D. W. Scholl and C. L. Sainsbury; scale about 1:31,680. lc. Plate 3, Engineering geology map of part of Ogotoruk Creek area, by Reuben Kachadoorian and R. H. Campbell; scale 1:4,800. 2. Sainsbury, C. L., and Campbell, R. H., 1959, Geologic strip map of part of the Kukpuk River, northwestern Alaska: U.S. Geol. Survey open-file report; scale about 1: 42,000. 3. Campbell, R. H., 1960, Preliminary geologic map and diagrammatic structure sections of part of the Point Hope A-2 quadrangle, north- western Alaska, in Kachadoorian, Reuben, and others, 1960, Geologic investigations in support of Project Chariot in the vicinity of Cape Thompson, northwestern Alaska-preliminary report: U.S. Geol. Survey TEI-753, pl. 2, scale 1: 48,000. 4. Campbell, R. H., geologic mapping during summer 1960. 5. Moore, G. W., geologic mapping during summer 1960. INTRODUCTION AND ACKNOWEDGMENT 8 (1906) and Smith and Mertie (1930). Data on the rocks exposed to the west of the area of this report have been taken from field notes of and discussions with G. W. Moore and I. L. Tailleur, of the U.S. Geological Survey, who examined those exposures in 1960 and 1961, respectively. Tailleur (oral commun., 1963) also provided additional information about the Mesozoic rocks along the Kukpuk River from his examinations in 1963. J. T. Dutro, Jr., E. G. Sable, and A. L. Bowsher (written commun., 1958) supplied valuable information on paleontology and stratig- raphy from a brief reconnaissance of the Cape Thompson area in 1951 and the Cape Lisburne- Corwin Bluff area in 1953. Figure 1 lists the sources of mapping data from which the geological map and sections were compiled. A summary report on the areal geology has been prepared (Campbell, 1966) for the U.S. Atomic Energy Commission volume on bioenvironmental studies of Project Chariot, and much of the text material and several illustrations appear in both this report and the summary. In July and August, 1958, fieldwork was done in the valley of Ogotoruk Creek by a party consisting of Reuben Kachadoorian, R. H. Campbell, C. L. Sainsbury, and D. W. Scholl, geologists, and Currey Lockett, cook and camp hand. Brief reconnaissance traverses were made along the coast in the company of I. L. Tailleur, who visited the party in early July; in addition, Sainsbury and Campbell examined ex- posures along the Kukpuk River for a distance of about 20 miles between the mouth of Igilerak Creek and Alolukrak. During the summer seasons of 1959 and 1960 the party engaged in areal mapping con- sisted of R. H. Campbell, geologist, and D. R. Currey, geologic field assistant. The fieldwork was done chiefly by weasel and foot traverse except along the sea cliffs between Crowbill Point and Cape Thompson, which were more easily accessible by small outboard motor boat. The field mapping was done on vertical aerial photographs, in 1958 at a scale of about 1:12,000 and in 1959 and 1960 at scales of about 1:46,000 and 1:41,000. Geology was transferred by radial planimetric plot- ter and by direct tracing (Campbell, 1961a) to topo- graphic base maps. The Point Hope A-2 quadrangle, 1:63,360 scale, was the only sheet published at the time of the field investigations. Topography for the adjacent areas was available only as 1:50,000-scale compilation sheets. Approximately half the area is covered by a thin veneer of unconsolidated deposits. In addition, nearly all the areas indicated as bedrock on the geo- logic map (pl. 1) are areas of barren frost-heaved bedrock rubble and therefore do not yield much re- liable structural and stratigraphic data. Undisturbed outcrops are generally confined to sea-cliff exposures and stream cutbanks. Many of the unconsolidated deposits display surface features that are easily dis- tinguished on the vertical aerial photographs; for most of the area, the distribution of those deposits was mapped by photointerpretation controlled by spot field examinations of reconnaissance density. By contrast, the photographic expression of the vari- ous bedrock units is less distinctive and may locally be deceptive; therefore, their mapped distribution is, necessarily, more closely controlled by field ex- amination of the outcrops. Photointerpretation of the bedrock distribution was used only in a few marginal areas, mostly in the southern part of the drainage basin of Ilyirak Creek. In those areas where the bedrock distribution was mapped by photo- interpretation based on field examinations of recon- naissance density, the unit label on the map is fol- lowed by a question mark. . Because the work was done as an integral part of investigations of much broader bicenvironmental studies and technical operations in connection with Project Chariot, it is impossible to acknowledge by name all the many persons who contributed ma- terially to the progress of the geologic mapping. Holmes & Narver, Inc., under contract to the U.S. Atomic Energy Commission, and Geological Survey personnel, both in Fairbanks and from parties en- gaged in other investigations at the Chariot site, provided helpful support without which the field- work could not have been effectively done. I par- ticularly wish to acknowledge the geologic work of Donald R. Currey, who served most ably as field assistant for the 1959 and 1960 summer field seasons. STRATIGRAPHY The bedrock of the map area consists entirely of sedimentary strata, probably all deposited in marine environments. The oldest strata exposed are mud- stone, sandstone, and limestone of an unnamed unit of Early Mississippian age. These are succeeded by the carbonate rocks of the Lisburne Group, locally of Early and Late Mississippian age. The Lisburne Group consists of three formations: the Nasorak Formation, chiefly limestone; the Kogruk(?) For- mation, chiefly dolomite; and the Tupik Formation, characterized by thick beds of black chert. The Lis- burne Group is overlain by the argillite, chert, and shale of the Siksikpuk Formation of Permian age, which is, in turn, succeeded by the shale, chert, and limestone of the Shublik Formation of Triassic age. 4 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PEN INSULA, ALASKA The Shublik is overlain by a very thick section of monotonously similar flysch-facies mudstone and sandstone strata, in which four formations are rec- ognized. They are, from oldest to youngest, the Ogotoruk, Telavirak, Kisimilok, and Fortress Moun- tain(?) Formations. The Fortress Mountain(?) is the youngest bedrock unit exposed in the map area. The only clearly datable fossils found above the Shublik Formation are pelecypods of Cretaceous age within the Kisimilok Formation, but a thick non- fossiliferous section intervenes between the top of the Shublik and the lowest clearly Cretaceous hori- zon. The Jurassic Period, therefore, may be repre- sented. Table 1 gives a summary of the stratigraphy. The bedrock is concealed in more than half the area by a few inches to several tens of feet of uncon- solidated sedimentary deposits and vegetation. Peat, sand, silt, and gravel occur as colluvium, windblown deposits, lake and swamp deposits, flood-plain de- posits, beach deposits, and terrace deposits at sev- eral levels. Most are of Quaternary age, but two de- posits of unconsolidated gravel found at high alti- tudes may be as old as Tertiary. Of the stratigraphic sections described in detail, all but the Niyiklik Creek section of the Telavirak Formation were measured along the magnificent sea- cliff exposures that extend nearly continuously from Crowbill Point to Cape Thompson (pl. 2). The see- tions of Mississippian strata and the lower part of the Imikrak Creek section of the Siksikpuk Forma- tion were measured by mapping the sea cliffs on oblique photographs at scales that were generally between 50 and 100 feet to the inch. (The photo- graphs used were taken at sea level and, insofar as possible, perpendicular to the shoreline. The scale for each was computed individually by taping or pacing a reference distance on the beach below the cliff.) The two sections of the Shublik Formation, the upper part of the Imikrak Creek section of the Siksikpuk Formation, and the Niyiklik Creek see- tion of the Telavirak Formation were measured by tape, pace, hand-level, and compass methods. Be- cause of the geographic continuity of most of the TABLE 1.1-Summary of sedimentary rocks and surficial deposits, Chariot site and vicinity, Alaska System Series Unit Name Character Thickness (feet) Tertiary(?) and Unconsolidated deposits Colluvium; windblown sand and silt; fluvial 0-100 Quaternary terrace and flood-plain gravel, sand, and silt; marine gravel and sand; and peat. Unconformity Lower(?) Fortress Mountain(?) Rhythmically interbedded silty mudstone and 3,000 + Cretaceous Formation sandstone, with minor conglomerate. Marine turbidites. Cretaceous Unconformity (?) Lower Cretaceous Kisimilok Formation Chiefly mudstone, with rhythmically inter- 5,000 + bedded sandstone abundant in basal zone. Buchia. Marine; turbidites common. Telavirak Formation Rhythmically interbedded sandstone and | 5,000+(1,000?) a mudstone, with minor - conglomerate. Jurassic or Marine turbidites. Cretaceous Ogotoruk Formation Mudstone with interbedded siltstone and | 5,000+(1,000?) sandstone. Marine; turbidites abundant. Disconformity(?) e t Lower(?), Middle, Shublik Formation Limestone, shale, and chert. Monotis abundant 200 Triassic and Upper Triassic in some limestone beds. Marine. > s= Disconformity(?) Permian Lower(?) Permian Siksikpuk Formation Argillite, chert, and minor shale. Marine. 400+ meera on Disconformity (?) f Tupik Formation Chert, mudstone, limestone, and minor 330 +(2007) o argillite. Upper Mississippian 3 : 2 Kogruk(?) Formation | Dolomite, limestone, and calcareous sedimen- 3,670 +(500?7) : g Ci tary breccia with minor chert. Marine fossils. o a & a 5 Nasorak Formation Chiefly rhythmically interbedded: limestone 2,200 8 & ”g and calcareous shale and minor interbedded 2 % Lower and Upper (3 silty shale. Marine fossils; limestone tur- 3 g Mississippian bidites(?). Sedimentary rocks Mudstone, sandstone, limestone, and minor 420 + (1, 500?) undivided conglomerate. Marine and possible non- marine. Base not exposed. STRATIGRAPHY f 5 measured sections, all of them have been grouped together in a separate part of this report. STRATIGRAPHIC AND PETROGRAPHIC METHODS AND TERMINOLOGY The terminology used to describe the bedding thickness is that recommended by Dunbar and Rod- gers (1957, p. 97). The color names conform insofar as possible to those of the National Research Council Rock-Color Chart (Goddard and others, 1948). Terms designating terrigenous sedimentary-rock types follow the terminology used by Williams, Turner, and Gilbert (1954). The limestones and dolomites have been classified according to the sys- tem and nomenclature proposed by Folk (1959) with but two modifications: (1) the traditional 2.00-mm boundary was used to distinguish rudite and arenite, rather than the 1.00-mm boundary suggested by Folk (1959, p. 16); and, (2) calcite grains as much as 0.031 mm in size that could not be determined as to origin-whether recrystallized micrite or dust from the abrasion of coarser allochems-are commonly present in minor amounts as an integral part of some matrix material and as such are included as "mi- crite" even though, in the strict sense proposed by Folk, the term excludes material coarser than 0.004 mm. The relative proportions of calcite and dolomite in hand specimens and thin sections of the carbonate rocks were determined by routine staining with Alizarine red S8 solution (Friedman, 1959), after preliminary optical and X-ray data on a pilot suite of specimens indicated that the rocks were chiefly calcite and dolomite, and that aragonite, gypsum, and high-magnesium calcite were not present in de- tectable amounts. The solution coats calcite with a deep red stain, whereas dolomite remains uncolored. MISSISSIPPIAN ROCKS Four formations of Mississippian age are shown on the geologic map (pl. 1). The lowermost is an un- named poorly exposed mudstone-sandstone-lime- stone sequence, the oldest exposed within the map area. It is overlain by the relatively pure limestone and dolomite beds of the Lisburne Group. The suc- cession appears to represent continuous marine de- position from Early to Late Mississippian time. SEDIMENTARY ROCKS UNDIVIDED The undivided sequence of mudstone, sandstone, and limestone of Early and Late Mississippian age crops out in the western part of the mapped area. The upper part of the sequence is well exposed in the sea cliffs a few hundred feet east of Cape Thompson (pl. 2A), where it is conformably overlain by the Lis- burne Group. Strata of the sequence are partly ex- posed along the back side of the beach between the Cape Thompson cliffs and Agarak Creek, in a few cutbanks along Agarak Creek, in rubble exposures to the west of Akoviknak Mountain, and, farther north, along the upper reaches of Nalakachak Creek. The upper part of the unit as exposed just east of Cape Thompson (pl. 24, fig. 2) consists of thin- bedded to thin-laminated shaly fine to very fine grained medium-gray sandstone and sandy siltstone interbedded with dark-gray to medium-dark-gray silty shale and mudstone and a few interbeds of medium- to thick-bedded dark-gray limestone. The limestone interbeds are chiefly a medium-grained poorly sorted biogenic calcarenite that has been partly dolomitized and partly silicified. The shales and sandstones appear to be generally noncalceareous. However, a few of the sandstone beds contain dolo- mite cement, and the mudstone beds are locally fos- siliferous. Tiny veinlets of calcite are common in all the beds. The rocks that crop out along Agarak Creek are very similar to those exposed just east of Cape Thompson, and the fauna from both areas is domi- nated by abundant small zaphrentoid corals. The rocks exposed on the nearby beach, however, include more abundant thin beds of medium-gray and red- dish-brown very fine grained quartz sandstone con- taining scattered coalified plant fragments and, lo- cally, ferruginous nodules and cement. In addition, the mudstone or shale interbeds are more strongly indurated and a sheen of disseminated very fine grained mica has developed along a few bedding sur- faces. In the exposures east of Akoviknak Mountain a few beds of coarse quartzose sandstone and a poly- mict fine pebble conglomerate are represented in frost-heaved rubble. The conglomerate pebbles in- clude some quartz, but they appear to be chiefly chert and fragments of other very fine grained rock. The conglomerate is well sorted as to size and contains relatively little matrix, but locally is well cemented with calcite and limonite(?). To the north, the poor outcrops along Angayukuk Creek are chiefly silty mudstone, locally shaly, with subordinate inter- bedded limestone. Some quartzose sandstone is pres- ent in the rubble exposures north of Angayukuk Creek, and the outcrop in Kunuk Creek is a laminated sandy siltstone. 6 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA Farther north, along the upper reaches of both major forks of Nalakachak Creek, the rocks are chiefly medium-gray to medium-dark-gray silty mud- stone and claystone, generally thin bedded and lo- cally shaly, but in some places occurring in thick and very thick beds. Sandy zones were not found. The mudstones are locally fossiliferous and interbedded with them are a few medium and thick beds of medium-gray fossiliferous limestone. The precise stratgraphic succession of the various rock types could not be established because of com- plex structure, poor exposures, and apparently rapid facies changes. Only the upper 420 feet exposed in the cliffs east of Cape Thompson were well estab- lished stratigraphically . (See measured sections, p. 33-34.) The total exposed thickness of the mudstone- sandstone-limestone unit is estimated to be on the order of 2,000 feet. The base of the sequence is not exposed. The contact with the overlying Lisburne Group is gradational and the adjacent strata inter- tongue. (See pl. 24.) The collections of marine fossils have been iden- tified by J. T. Dutro, Jr., and Helen M. Duncan, of the Geological Survey, who report (written commun., 1961) that the fauna in collections from near Cape Thompson is Early Mississippian in age. About 12 miles to the north, however, in the upper reaches of Nalakachack Creek, fossil collections from the mudstone-sandstone-limestone sequence (60A¥ACr-129, 60ACr-132, and 60A¥Cr-132A of table 2) are re- ported to be lower Upper Mississippian (Helen M. Duncan, written commun., 1963; J. T. Dutro, Jr., written commun., 1965). This suggests that the con- tact between this predominantly terrigenous clastic unit and the relatively pure limestone of the overly- ing Lisburne Group may transgress time, becoming progressively younger from south to north. It would indicate that something in excess of the 500 feet of fossiliferous carbonate beds assigned to the Lower Mississippian part of the Lisburne Group at Cape Thompson has graded laterally northward into a pre- dominantly mudstone section. This type of gradation is also suggested by Tailleur's observations (oral commun., 1965) that near Cape Dyer, to the north- west of the area of this report, the contact between the lowest thick carbonate sequence and the underly- ing mudstone unit lies at or very close to the bound- ary between the Lower and Upper Mississippian. Fossil collection 50A¥ACr-130, also from the upper reaches of Nalakachak Creek, appears to be anomal- ous. The fossils have been identified by Duncan (written commun., 1963) as mostly of the genus Tachylasma, associated with a few specimens of probable Ufimia. Duncan (written commun., 1963) notes that elsewhere Tachylasma is recorded only from rocks of Permian age. This age is difficult to reconcile with field observations indicating that the strata from which the fossils were thought to have come are interbedded between Mississippian strata represented by collections 60ACr-129 and 60A¥Cr- 132. The fossils of 60ACr-130, however, are mostly silicified horn corals that were found as loose weathered fragments on a frost-heaved rubble sur- face and may be some sort of lag deposit from an eroded klippe of the Ibrulikorak thrust sheet rather than from the beds on which they lie. Alterna- tively, if the fossils were from those beds, they may represent tightly infolded or infaulted Permian rocks (though they do not resemble the known strata of the Siksikpuk Formation elsewhere in the map area) in the Ibrulikorak thrust sheet, of which there could remain only a small klippe 5 or 10 feet thick. The mudstone-sandstone-limestone sequence cor- relates, at least in part, with the Mississippian coal- bearing formation reported by Collier (1906, p. 18- 19) in exposures along the cliffs south of Cape Lis- burne. No coal beds have been found within the area of plate 1, but Kindle (1909, p. 523-524) collected plant fragments from this area that were sufficiently large and well preserved to be identified. Dutro sug- gests (written commun., 1961) that the upper part of the mudstone-sandstone-limestone sequence-as ex- posed in the vicinity of Cape Thompson-together with some of the lower beds of the overlying Lis- burne Group, is probably equivalent to the type Utukok Formation (Early Mississippian) in the western DeLong Mountains (Sable and Dutro, 1961, p. 591, 592) about 90 miles to the east, and that the plant-bearing sandstones of possible nonmarine origin would correlate approximately with the Noatak sandstone (Devonian and Mississippian). The collections from the Nalakachak area were first thought to be faunally equivalent to part or all of the Lower Mississippian part (basal 500 ft) of the Nasorak Formation (Dutro and Duncan, written commun., 1962) and earlier papers (Campbell, 1965a ; Campbell, 1966) reported the unit to be Early Mississippian. The collections have subsequently been reported as most likely lower Upper Mississip- pian (Helen M. Duncan, written commun., 1965; J. T. Dutro, Jr., written commun., 1965) so that the map unit must now be regarded as of Early and Late Mississippian age. MISSISSIPPIAN ROCKS : 7 LISBURNE GROUP The Lisburne Group, here of Early and Late Mis- sissippian age, is about 5,900 feet thick and consists chiefly of limestone and dolomite beds, in part cherty, with variable but minor amounts of interbedded shale. The Lisburne, named by Schrader (1902, p. 241), has been described in recent reports in which five recognizable subdivisions were described as M14, M1; M1; M1,, and M1; (Campbell, 19602, pl. 3; 1960b). The lower three of these units (M11, M1, and M1;) have been grouped together and named the Nasorak Formation (Campbell, 1965a). The over- lying unit (M1,) is designated the Kogruk(?) For- mation because of its lithic similarity and partial faunal equivalence to the type Kogruk Formation, named by Sable and Dutro (1961) in the western DeLong Mountains. The topmost unit of the Lis- burne Group (M1;) is mapped as the Tupik Forma- tion because it is similar in lithology and strati- graphic position to the type Tupik Formation in the western DeLong Mountains (Sable and Dutro, 1961). The formation assignment was not determined for outcrops in a few small areas of poor exposure and complex structural relations; there, the Lisburne Group was mapped as undivided. NASORAK FORMATION The Nasorak Formation (Campbell, 19652) is a limestone sequence named from typical exposures in the sea cliffs near the mouth of Nasorak Creek (pl. 2B), where nearly 1,800 feet of the upper part of the formation are nearly continuously exposed with rela- tively little structural complexity. Most of the for- mation is also well exposed farther west in sea cliffs in the vicinity of Cape Thompson (fig. 2). (See meas- ured sections, p. 30-33, 44-49.) There the base is exposed in conformable contact with the underlying mudstone-sandstone-limestone sequence. Elsewhere, good exposures are limited chiefly to cutbanks along the Kukpuk and Ipewik Rivers. The lower member of the Nasorak Formation con- sists of 165 feet of strata and is best exposed just east of Cape Thompson. It consists of interbedded dark-gray to grayish-black silt clay shale, locally cal- careous, and medium-gray to dark-gray cherty lime- stone. This zone is overlain by the Cape Thompson Member, about 225 feet of massively outcropping very thick bedded light-gray to light-olive-gray lime- stone. The Cape Thompson Member is resistant to erosion and forms the promontory of Cape Thomp- son, its type locality, for which it is herein named. It is succeeded by about 50 feet of very thick bedded grayish-black calcareous mudstone containing small pyrite concretions and a few pyritized fossils, the basal part of the upper member of the formation ; above this the remaining part of the upper member is remarkably uniform in lithology and bedding char- acteristics. The upper member is characterized by rhythmically interbedded thin-bedded to medium- bedded dark-gray limestone and by thin-laminated to very thin bedded silty calcareous shale. Shale in- terbeds generally decrease in both abundance and thickness progressively upward through the mem- ber. The dark limestones of both the upper and lower members of the Nasorak Formation are predomi- nantly medium- to coarse-grained biomicrites. Poorly sorted allochems, nearly all fossil fragments, con- stitute 20-80 percent of the rock ; the remainder is a matrix of microcrystalline calcite and silt-sized detri- tal calcite (fig. 3C, D). There are, however, a few rare interbeds of coarse-grained biosparite (fig. 4C) in the upper member. Terrigenous debris is almost entirely lacking. The most abundant recognizable fossil fragments are crinoid columnals, undeter- mined echinoderm fragments, and fragments of Bryozoa. Foraminifera were seen as sparse consti- tuents of a few beds. Fragments of other shelled organisms, probably chiefly brachiopods, are also common. Incomplete replacement by dolomite is common, though not prevalent (fig. 44). Nodular limestone beds containing variable amounts of dark- gray to black chert are common at some horizons. Dark chert is locally abundant in several zones, chiefly as lenticular nodules and irregular angular masses in limestone beds. The interbedded calcareous shale is composed chiefly of micrite, fossiliferous micrite, and bio- micrite, much of which apparently contains abundant silt-sized detrital calcite grains (fig. 34, B). Terri- genous material is generally very rare throughout the formation and is represented chiefly by a small amount of clay (chiefly illite?) in the shale interbeds, and minor amounts of very fine to fine quartz silt. Sand-sized terrigenous debris is almost entirely lack- ing. The massive light-gray limestone of the Cape Thompson Member is chiefly a crinoid biosparite, consisting almost exclusively of coarse sand- to fine pebble-sized crinoid stem fragments and columnals (fig. 4B) ; locally it contains very minor amounts of very fine quartz silt and has been partly dolomitized and partly silicified. Bedding is expressed internally in this limestone by crinkly uneven discontinuous laminae at generally regular intervals of half an inch to a foot in spacing. 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['g 'Jo [Dizaquiag ...... '8[EUIUNJOD pJouLL;) |||||||| enllaoa]494. goput 'stiqop unrepoutopf :surropouryon =---~-s¥]Jours; pus asoures 'susozo41q ||||| pus 'susozo41q ...... =-~-~--~----u110; osours1 'usozo41q |||||| ........ FARRCAAS n ts ds SH ~~40put 'ds |||||||||||| ===-~~~~~~~~q9put 'usoz0£1q 918.13§9u9,f aht ~~~geput 'suroz041q ........ «de i acre aoa ial goput *ds [ofzorpofsh;) |||||||||||||| Seer ars '49put 'usoz0£rg :susoz0£ig ds junphydizydo7 conn r an c= or os rnd Bae] AoA ||||||||||||||||||||||||||||||||||| ds soppuonydo7 nti shiit t dik Fabe ing indi aka h alc he hea otes, ds ||||||||||||||||||||||||| gopun 'sre100 proguoryds7 |||||| vay cor 100+ 370 _ 470+ 3. (Mik-g of pl. 2B) Dolomite, dolomitic limestone, and chert. Chiefly medium-gray to medi- um-dark-gray fine to medium- crystalline biogenic dolomite (dolomitized biomicrite and fossiliferous micrite); about 20 percent medium-light-gray to dark-gray chert in small nodules, irregular patches, and some possible intraclasts; and, locally, about 20 percent light- olive-gray dolomitic limestone (partly dolomitized, 50 per- cent, fossiliferous micrite). In part a dolomitized coarse in- tramicrudite (or locally de- rived sedimentary breccia with carbonate mudstone matrix). Beds generally about 1 ft thick, but range in thickness from 1 in. to 2 ft. Irregular bedding, uneven bedding sur- faces, and continuous but in- distinct - bedding - surfaces result in a massively outcrop- ping aspect. Intraclasts gen- erally sparsely disseminated, but locally abundant; chiefly irregularly fragments of car- bonate mudstone, some show- ing internal bedding lamina- tion, and angular pieces of chert that appear to be de- trital (though there is also abundant postdepositional chert). Although some clasts are as much as 5 em across, most are only a few milli- meters in diameter. Ratio of dolomite to calcite ranges from about 19:1 to about 1:1. Recognizable ghosts of fossils include horn corals, crinoid columnals, and Bryozoa. 59ACr-74f is a fossil collec- tion (table 2). 59ACr-74 and 59ACr-75 are chips taken to represent lithologic varia- tions. Some tectonic breccia- tion of unit tends to obscure the nature of sedimentary breccia locally, chiefly along intensely jointed zones that show little observable dis- placement. Base of unit not exposed; contact with under- lying unit is a high-angle fault ._......._..G.hlr al tien Unit 270+ 85 Thickness (feet) Cumulative 7404+ 36 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA Kogruk(?) Formation-Continued High-angle fault, unknown thickness missing. 4. (Mik-f of pl. 2B) Dolomite with minor chert. Massively out- cropping - medium-gray - to olive-gray fine- to medium- crystalline biogenic dolomite; dark-gray to light-gray chert, in nodules generally less than 1 ft in diameter, locally as much as 10 percent of rock. Bedding characteristics and outcrop form much the same as unit 3, but contains less chert; contains no recogniz- able - intraclasts. Breccia abundant in one zone on east side of unit, at its fault con- tact with unit 5, where it may all be tectonic. Ghosts of fos- sils include crinoid columnals, Bryozoa, horn corals, and brachiopod fragments. 59ACr- 73f (table 2) is fossil collec- tion of the meager, poorly preserved fauna. 59ACr-73 and 59ACr-72 are chips taken of - characteristic - lithologic types. Unit separated from adjacent rocks on both sides by high-angle faults. Repre- sents a stratigraphic thickness of at least 100 ft, and as the accessible parts not clearly repeated elsewhere in section, it is believed to lie strati- graphically between units 3 and 5, probably with not more than a few hundred feet of beds missing .................\....o._. High-angle fault, unknown thickness missing (probably not more than a few hundred feet). 5. (Mik-e of pl. 2B) Carbonate- chert breccia, probably sedi- mentary, but because unit is bounded by high-angle faults, may be largely or completely tectonic. About 30 percent me- dium gray to medium-dark- gray chert-aphanitic micro- granular quartz containing abundant disseminated medi- um-crystalline euhedral and subhedral dolomite erystals; occurs as 2-15 cm angular fragments. Medium-gray co- arsely crystalline to medium- crystalline dolomite occurs as subrounded clasts in same size Unit 100+ Thickness eet Cumulative 840+ range. Matrix - commonly lighter in color than the dolo- mite clasts, generally medium light gray to light gray; chief- ly fine- to medium-crystalline dolomite with variable but minor amounts of relict(?) calcite micrite and microspar (?). In a few places, coarsely crystalline dolomite appears to occur as an intergranular cement; both clasts and ma- trix cut by veinlets filled with calcite and dolomite. Bedding characteristics of the massive- ly outcropping unit could not be distinguished. No fossils were seen. 59ACr-71 consists of chips taken to represent lithology. Unit bounded on both sides by high-angle faults; thickness shown is minimum. As lithology is not clearly repeated elsewhere in section, unit is believed to lie stratigraphically between units 4 and 6, probably with not more than a few hundred feet of beds missing -__- High-angle fault, unknown thickness missing. 6. (Upper part of Mik-d of pl. 2B) Rocks in inaccessible part of cliff, not exposed at beach level. Looks very similar to, and probably - gradational with, unit 7 below. From beach level, only observable difference from unit 7 is that the bedding surfaces of this unit look more even. Top of unit not exposed; thickness shown is therefore a mini- mum. 7. (Lower part of MIik-d of pl. 2B) Rhythmically interbedded dol- omitic limestone and silty calcite mudstone, with about 20 percent chert nodules. Me- diam-dark-gray - dolomitic limestone-dolomitized - lami- nated microsparite or calcite mudstone-in beds averaging 0.5 ft thick (range from 0.1 to 1.0 ft) rhythmically inter- bedded with shaly partings (generally less than 0.03 ft thick) consisting chiefly of medium-dark-gray silty mi- crosparite. (May contain as much as 18 percent fine Thickness (feet) Unit Cumulative 1454+ - 985+ 140+ 1,125+ Kogruk(?) Formation-Continued quartz silt.) No fossils seen. 59ACr-70 consists of chips taken to represent lithology. Base of unit not exposed, and contact with underlying unit is a high-angle fault. As this lithology is not clearly re- peated elsewhere in section, unit is believed to lie strati- graphically between units 6 and 8, probably with not more than a few hundred feet of beds missing ..;...____._...._.._... High-angle fault, unknown thickness missing. f (Upper one-fourth of Mlk-c of pl. 2B) Dolomite with very minor chert. White to yellow- ish-gray - medium-crystalline dolomite with 5-10 percent relict medium-crystalline cal- cite spar in irregular patches. Patches of finely crystalline dolomite from fine-sand to fine-pebble size look like al- lochem ghosts of unidentified origin. Unit crops out mas- sively and looks like a single thick bed, but some discon- tinuous lamination and a few zones of small (less than 1 in.) medium-gray chert nod- ules express bedding. Chert makes up only about 1 percent of unit. No fossils seen. 59ACr-69 consists of chips taken to represent lithologic types. Top not exposed ___ 9. (Lower three-fourths of Milik-c of pl. 2B) Dolomite with minor but distinctive lami- nated chert. Light-gray to very light gray, medium, coarse, and finely crystalline dolomite commonly showing ghostly internal cross-lamina- tion-probably chiefly dolo- mitized calcarenite, but includes some clearly recogniz- able dolomitized fossiliferous micrite-generally with less than 5 percent relict(?) cal- cite; locally one 3-ft zone con- tains as much as 50(?) per- cent - calcite. Irregularly bedded massive, thick, and a few thin beds, all discontinu- ous over several tens of feet, giving unit a massive cliff- forming aspect. Lower part MEASURED BEDROCK SECTIONS Thickness (feet) Unit Cumulative 150+ 1,275+ 140+ 1,415+ of unit contains about 20 per- cent dark-gray to light-gray chert in thin lenticular bands along bedding and in irregular small nodules. Upper part of unit contains a few percent more chert, partly as light- to - medium-gray - lenticular nodules as much as 2% ft thick and 6 ft long, as well as 3 distinctive zones, each about 10 ft thick, of light-gray and grayish-orange pink chert in very thin (% in. and thinner) laminae with minor amounts of interlaminated very finely crystalline - dolomite. One prominent zone of intraforma- tional breccia occurs about 60 ft above base of unit (fig. 10.) Fossils are very sparse and consist of dolomitized frag- mental material. 59ACr-68f is fossil collection (table 2). 59ACr-68 and 59ACr-67 are chips taken to represent lithology 10. (Uppermost part of Mik-b of pl. 2B) Dolomite with very minor chert. Chiefly yellowish-gray but partly light-olive-gray and medium-gray medium-crystal- line dolomite, locally showing some ghostly internal fine lamination-probably chiefly dolomitized micrite or very fine grained calcarenite. Very thick bedded with discontinu- ous faint bedding surfaces and a massively outcropping as- pect. Light- and dark-gray chert in thin discontinuous zones and bedding-oriented thin lenticular nodules make up 1-5 percent of unit. No fossils found. 59ACr-66 con- sists of chips taken to repre- sent lithology ..............__...._. 11. (In upper part of MlIk-b of pl. 2B) Dolomite and chert. Light-olive-gray and yellow- ish-gray finely crystalline dolomite-probably chiefly dolomitized micrite or very fine grained allomicrite-with relict(?) intergranular calcite micrite and microspar rang- ing from 3 to 20 percent. Very fine internal lamination (lo- cally cross laminated) is ex- pressed by alternating color 8T Thickness (feet) Unit Cumulative 380 1,745+ 57 1,802+ 38 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA Kogruk(?) Formation-Continued 12. laminae. Megascopic bedding is indistinct, but distribution of chert zones gives basal part of unit a thin-bedded aspect with a gradation upward to- ward more thickly bedded aspect resembling unit 10. Dark-gray chert occurs in thin (averaging about 1 in. thick) relatively continuous uneven surfaced zones. In lower part of unit, chert zones are regularly - interlayered with the dolomite at intervals of about 4 in. In upper half of unit, chert zones are slight- ly thicker but less continuous, and spacing between them grades upward to 1 ft. Top- most beds contain only a few scattered chert nodules. No fossils found in unit. 59ACr- 65 consists of chips taken to represent lithology _________ (In upper part of MIik-b of pl. 2B) Dolomite. Light-olive- gray to light-gray finely crys- talline dolomite-including clearly recognizable dolomi- tized biomicrite, but chiefly probably dolomitized lami- nated micrite-with minor (but locally as much as 20 percent) relict(?) micrite and local intergranular - calcite spar; and dark-gray finely crystalline laminated dolomite -probably a dolomitized mi- crite-containing as much as 5 percent carbonaceous ma- terial(?) interstitial to sub- hedral dolomite. Light-colored rocks predominate in the lower part of the unit in beds from 1 in. to 3 ft thick. The thick beds show indistinct internal lamination; the thin beds are internally thinly laminated and locally contain abundant small (about 1 in.) grayish- black chert nodules. Dark- colored rocks predominate in upper part of unit in beds as much as 1% ft thick, con- taining about 1 percent small dark-gray and grayish-black chert nodules. Bedding is gen- erally lenticular and continu- ous. Recognizable fossils are exclusively dolomitized ghosts Thickness (feet) Unit Cumulative 60 1,862+ of crinoid columnals. 59ACr- 64 consists of chips taken to represent lithology ___ 13. (In middle part of MIk-b of pl. 2B) Dolomite with minor chert. Light-olive-gray fine- to medium-crystalline biogenic dolomite (dolomitized biomi- crite and fossiliferous micrite containing from less than 1 percent to as much as 25 per- cent ghosts of fossils) with generally less than 5 percent relict(?) calcite micrite and intergranular spar. Dark- gray to grayish-black lenticu- lar nodules 1-8 in. thick and from less than 6 in. to about 2 ft long abundant (as much as 30 percent of the rocks) in some stratigraphic zones, where they are oriented along the bedding direction. Light- gray to very light gray irregu- lar small (about 2 in. in diameter) chert nodules ran- domly distributed. Total chert content of unit is estimated to be 5-10 percent. Unit looks like one massive bed, with bedding expressed by discon- tinuous internal laminae- chiefly oriented bryozoan leafy fragments-and discontinuous bedding plane partings spaced from 6 in. to 3 ft apart. Recognizable fossils include Bryozoa, crinoid columnals, horn coral, and an indistinct form of colonial coral(?). All fossils consist of dolomitized ghosts; none appeared suffi- ciently well preserved to war- rant collection. 59ACr-63 con- sists of chips taken to repre- sent lithology ...._...._.._._._._... 14. (In middle part of MIk-b of pl. 2B) Dolomite. Medium-dark- gray finely crystalline to me- dium-crystalline biogenic dolomite-dolomitized fossil- bearing micrite and biomicrite containing as much as 50 per- cent ghosts of fragmental fos- sils-in 6-in. to 1-ft-thick irregularly bedded discontinu- ous unevenly surfaced beds, predominates in several zones from 5-20 ft thick; separated by a few continuous beds 2-4 ft thick of light-gray Thickness (feet) Unit Cumulative 28 1,8904+ 155 2,045+ Kogruk(?) Formation-Continued medium-crystalline to coarse- ly crystalline biogenic(?) dolomite-dolomitized allomi- crite containing as much as 30 percent allochem (fossil?) ghosts. Unit is relatively chert free except near top, where some light-gray dolo- mite beds contain - minor amounts (less than 1 percent) of dark-gray to grayish-black chert in thin lenticular nod- ules. Recognizable fossil ma- terial includes Bryozoa, cri- noid columnals and other echinoderm fragments, horn corals, and brachiopod (?) shell fragments. 59ACr-62f is a fossil collection (table 2). 59ACr-62 consists of chips taken to represent lithology... 15. (In middle part of Mik-b of pl. 2B) Dolomite and subordinate chert. Medium-light-gray to medium-gray medium-crystal- line to finely crystalline biogenic(?) dolomite-dolomi- tized coarse biomicrite or bi- osparite, containing about 60 percent ghosts of fragmental fossils-in indistinct discon- tinuous beds from 5 in. to 3 ft thick. Dark-gray chert and minor amounts of light-gray chert make up about 15 per- cent of unit as irregular nod- ules arranged in relatively continuous zones within dolo- mite beds parallel to the bed- ding. Individual nodules are as much as 1 ft thick but average about 2 in. Dolomi- tized fossil 'debris includes chiefly crinoid columnals and other echinoderm fragments and - subordinate - Bryozoa. None appeared well-enough preserved to warrant collec- tion. 59ACr-61 consists of chips taken to represent Mithology | Unit 16 appears gradational with unit 15 through a transi- tion zone that is about 16 ft thick. These beds are included in the total thickness given for unit 16 below. (In lower part of MIk-b of pl. 2B) Dolomite. Light-gray, very light gray, and medium- MEASURED BEDROCK SECTIONS Thickness eet) Unit Cumulative 82 2127+ 25 21524 gray finely crystalline to me- dium-crystalline laminated dolomite-no clear cut ghosts remain, but textures expressed by patches and laminae of coarser crystalline dolomite in finer crystalline matrix and interlaminae suggest the rocks formed by dolomitization of laminated calcite mudstone or fine calcarenite-with distinc- tive lenticular color mottling that apparently represents variations in abundance of impurities (carbon?). - The lighter colored areas possibly represent - better "washed" current winnowed calcarenite in which calcite spar cement was deposited instead of in- terstitial micrite. (Mottling illustrated by photograph, fig. 12). Unit has massively out- cropping aspect and is very thick bedded, with individual beds as much as 50 ft thick. Bedding expressed by oriented mottled zones, internal lami- nation, and a few irregularly spaced indistinct discontinu- ous bedding-plane partings. Light-medium-gray to light- gray chert occurs as thin lenticular nodules and nodular bands oriented along bedding direction. A few zones may contain as much as 20 percent chert, but total with respect to entire unit is less than 10 percent. No fossils recognized. 59ACr-60 and 59ACr-60a are chips taken to represent lith- ology ci (In lower part of MIk-b of pl. 2B) Dolomite with minor chert. Medium-gray to dark- gray medium-crystalline bio- genic - dolomite-dolomitized medium-grained biomicrite containing about 20 percent ghosts of fragmental fossils of which leafy Bryozoa, ori- ented along bedding direction, predominate-with less than 5 percent relict(?) calcite, chiefly as sparry centers of almost wholly - dolomitized crinoid columnals(?). Dark- gray to grayish-black chert- silicified biomicrite or fossili- ferous micrite in which hollow 89 Thickness (feet) Unit Cumulative 100 2,252+ 40 Kogruk(?) Formation-Continued 18. spines (echinoderm or brachi- opod, most likely) predomi- nate-occurs as a few rare irregular nodules, generally about 1 in. in diameter. The unit is thin-bedded, regularly bedded; beds are continuous but have minor undulating un- evenness of bedding surfaces. Fossils include Bryozoa, cri- noid columnals and unidenti- fied echinoderm debris, horn coral, and brachiopods. 59ACr-59f is fossil collection (table 2). 59ACr-59 consists of chips taken to represent lithology ..........} (Lowermost part of Mlik-b of pl. 2B) Dolomite with minor chert. Medium-light-gray to medium-gray, and dark-gray medium-crystalline - dolomite, in large part biogenic-most is probably dolomitized fine- to coarse-grained biomicrite containing from 8 to 80 per- cent fragmental ghosts of fos- sils-generally with less than 3 percent relict(?) calcite, chiefly as intergranular patches of spar. Light-gray to dark-gray chert occurs chiefly as small irregular nod- ules and thin discontinuous zones of nodules within dolo- mite beds. The light-gray to medium-gray dolomite that makes up most of unit is thick to very thick-bedded (some beds as much as 20 ft thick) with irregularly spaced dis- continuous bedding surfaces; has a massively outcropping aspect. The dark-gray dolo- mite is all in one zone, 10-15 ft thick, of thinly bedded strata near middle of unit. Most beds show some internal lamination - at - irregularly spaced intervals, most notice- able and closely spaced in thin- bedded central zone. Chert makes up about 10 percent of upper - thick-bedded - zone, about 5 percent of lower thick-bedded zone, and is very rare in central thin-bedded zone. Recognizable ghosts of fossils include a few crinoid columnals and, rarely, strue- MEASURED BEDROCK SECTION Thickness (feet) Unit Cumulative 47 2,299 + tures that seem to be some form of colonial coral, but none of the material was well- enough preserved to warrant collection. 59ACr-58 consists of chips taken to represent lithology ..:......._ use al 19. (Uppermost part of Mik-a of pl. 2B) Dolomite. Light-olive- gray to medium-gray very finely crystalline to finely crystalline biogenic dolomite -dolomitized very fine grained to - coarse-grained biomicrite, fine biomicrudite, and fossiliferous micrite, con- taining from 7-60 percent ghosts of fragmental fossils- generally less than 3 percent relict(?) calcite micrite and intergranular spar. Medium- light-gray chert makes up a few percent of unit, chiefly in upper part, mostly as thin (as much as 10 in.) irregular- ly lenticular nodules in dis- continuous - bedding-oriented zones in and along bedding surfaces. Beds range in thick- ness from less than 1 in. to as much as 15 ft; bedding sur- faces are irregularly spaced (through close spacing is rare), relatively but not per- fectly even, and generally continuous for at least 100 ft (though overall aspect is gent- ly lenticular). Cross-joint spacing of about the same range as the bedding thickness combines to give unit a blocky- surfaced massive-outcropping aspect. Recognizable ghosts of fossils include only crinoid columnals and leafy bryozoan fragments, none well-enough preserved to warrant collec- tion. 59ACr-57 consists of chips taken to represent lith- ology ...... taa al. 20. (In upper part of Mik-a of pl. 2B) Dolomite with subordi- nate chert. Medium-light-gray to light-gray, and light-olive- gray finely crystalline to me- dium-crystalline dolomite, in part biogenic-dolomitized bi- omicrite and laminated mi- crite with as much as 20 per- cent ghosts of fragmental fossils-generally containing Thickness (feet) Unit Cumulative 110 2,409+ 255 2.6644 Kogruk(?) Formation-Continued less than 5 percent relict(?) calcite micrite and intergranu- lar spar. Dark-gray and me- dium-gray chert occurs as lenticular nodules within dolo- mite beds and as thin long (as much as 20 ft) discontinuous zones along bedding planes. Beds are thin, mostly about 4 in. thick, but ranging from 2 in. to 1% ft. Bedding surfaces are slightly uneven, but ap- pear relatively continuous. Recognizable ghosts of fossils include crinoid - columnals, leafy Bryozoa, colonial corals, and brachiopod fragments. 59ACr-56f is fossil collection (table 2); 59ACr-56 consists of chips taken to represent |...... (In middle part of of pl. 2B) Dolomitic limestone and silty fossiliferous carbonate mudstone. Medium-gray part- ly dolomitized (as much as 25 percent locally) partly silici- fied locally as much as 10 percent patchy aphanitic to finely crystalline microgranu- lar chert) fine- to very coarse grained crinoid-bryozoan bio- micrite, generally contains 30- 85 percent fragmental fossil material and, though micrite matrix predominates, as much as 10 percent intergranular sparry calcite. Chiefly irregu- larly bedded in thick and thin relatively continuous even beds. With interbedded thin- bedded to thin-laminated dark- gray silty (from less than 1 percent to as much as 25 per- cent quartz silt) fine-grained biomicrosparite (with 7-80 percent fragmental fossil ma- terial), and - medium-light- gray finely crystalline biogenic dolomite (probably the dolo- mitized equivalent of the silty biomicrosparite). Fossils in- clude a blastoid and locally abundant brachiopods, as well as bryozoan and echinoderm debris. 59ACr-55f is fossil collection (table 2) ; 59ACr-55 consists of chips taken to represent lithology .._. is MEASURED BEDROCK SECTIONS Thickness (feet) Unit Cumulative 120 2,784+ 86 2870+ 22. (In middle part of Mlik-a of pl. 2B) Dolomite with subordi- nate chert. Chiefly light-olive- gray to light-gray, but some medium-dark-gray, finely crys- talline biogenic dolomite- dolomitized fossil-bearing mi- crite, generally containing less than 10 percent fragmental fossil material-generally with less than 1 percent relict(?) calcite micrite. Me- dium-dark-gray to dark-gray chert makes up about 20 per- cent of unit, chiefly as small irregularly lenticular nodules within the dolomite beds. Beds are thin (commonly 1-6 in. thick) and have relatively continuous but undulating bedding surfaces, so that beds pinch and swell irregularly along bedding; compensated by alternating pinches and swells in adjacent beds. Ghosts of fossils are chiefly leafy Bryozoa, but brachiopod frag- ments are locally abundant. No fossil material collected. 59ACr-54 consists of chips taken to represent lithology _ 23. (In middle part of Mlk-a of pl. 2B) Dolomite. Light-gray to very light gray medium-crys- talline partly biogenic dolo- mite-sparse recognizable ghosts of crinoid columnals and ghostly internal color lamination suggest original rock was a fossiliferous cal- carenite. A minor amount of medium-gray chert occurs as small nodules. Bedding ir- regular; thickness of beds ranges from 6 in. to 12 ft, most commonly 2-4% ft. Crinoid columnals are the only fossils recognized. 59ACr-53 consists of chips taken to represent lithology. Unit appears very similar to the light-colored dolomite of underlying unit 24, but more thickly bedded (massively out- cropping); contains less me- dium-gray chert and no gray- ish-black chert. The two units appear gradational ______ 24. (In middle part of Mlk-a of pl. 2B) Dolomite with minor chert. Chiefly light-gray to 41 Thickness (feet) Unit Cumulative 25 2,895+ 88 2,9784+ 42 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA Kogruk(?) Formation-Continued Thickness o (feet) T’?’fi£¥f” s 8 4 , Unit Cumulative Unit Cam@lative dium-crystalline limestone in light-olive-gray coarsely crys- beds 5 in. to 2 ft thick with, talline dolomite-faint lami- very locally, about 1 percent nation suggests a dolomitized grayish-black chert as discon- calcarenite-in continuous tinuous lenticular zones very even beds most commonly 8 locally as much as 2 ft thick. 56 3,1197+ in. to 1% ft thick. Irregularly interbedded with medium-gray medium-crystalline(?) _ lami- nated - dolomite-dolomitized micrite (most laminae are feathery current laminations) -in discontinuous lenticular beds from a few inches to 1 ft thick. Grayish-black chert and medium-gray chert occurs in small (less than 1 ft) ir- regular nodules in a few long (as much as 30 ft) thin (com- monly about 6 in. thick) lentic- ular zones. Chert totals only about 5 percent of the rocks of unit. Sparse ghosts of fos- sils include horn coral and brachiopod fragments, as well as more common bryozoan and echinoderm debris. 59ACr-52f (table 2) is collection of sparse ghosts of fossils; 59ACr-52 consists of chips taken to represent lithology 85 3,0634- 25. (In middle part of Mik-a of pl. 2B) The following descrip- tion is from field notes,! probable corrections in par- entheses: Limestone (prob- ably - dolomitic), - dolomitic limestone (very possibly a nearly pure dolomite with a few percent relict calcite or late calcite veinlets that may not be obvious in hand speci- men), and chert. A 5-ft-thick bed of light-brown coarsely crystalline limestone forms base of unit. It is overlain by a zone about 20 ft thick of thin laminated medium-gray dolomitic limestone in beds a few inches to 3 ft thick, with about 10 percent grayish- black chert in discontinuous irregularly bordered zones locally as much as 1 ft thick. - The topmost zone (about 20 ft thick) is medium-gray me- 26. (In lower part of Mik-a of pl. 2B) Dolomite, cherty dolo- mite, limestone, and chert. Light-gray to medium-light- gray partly cherty largely bi- ogenic very fine to coarsely crystalline - dolomite-except for some uniformly coarsely crystalline dolomite in which original textures have been completely masked, rock ap- pears to be a dolomitized (mostly 80-95 percent dolo- mite) silicified (in many places with 10-20 percent very finely crystalline micro- granular quartz, as a porous spongy intergrowth with the carbonate) very fine grained to - coarse-grained - biogenic calcarenite, in part with a micrite matrix, and in part with intergranular calcite spar cement. Medium-gray to medium-dark-gray - limestone -very fine to very coarse grained crinoid-bryozoan bi- osparite, in places as much as 10 percent dolomitized; gen- erally contains more than 70 percent fragmental fossil ma- terial. Light-gray _ chert (spongy intergrowth in the dolomite) occurs in irregular patches of widely ranging size. Grayish-black chert oc- curs as irregular discontinu- ous zones as much as 6 in. thick, - commonly - oriented along bedding, but locally crosscutting bedding at low angles. Total chert content of unit is probably 5-10 percent. The dolomite is chiefly in beds ranging in thickness from 1 in. to 7 ft, but general aspect dominated by beds 3-4 ft thick. Bedding surfaces gen- erally appear even and con- tinuous. Internal lamination 1 No representative chips from this unit were available; therefore, the believed upon cursory field examination; in addition, the rocks designated as field designations could not be checked by staining for calcite or microscopic coarsely crystalline in the field commonly owe that crystallinity to the pres- textural examination in the laboratory. On the basis of comparisons be- ence of coarse-grained echinoderm debris, which, of course, consists largely tween field and laboratory designations for rocks of other units, the rocks of plates, each a single crystal. are probably a great deal more dolomitic and more finely crystalline than was Kogruk(?) Formation—Continfied not commonly well expressed, except in a few beds of dolo- mitized Bryozoa-bearing mi- crite near top of unit. In gen- eral, lower part of unit has a more massively outcropping aspect and is lighter in color; upward gradation to some- what darker colored, more ledgy aspect, most noticeable when viewed from a distance. Fossils are rare, but those found include horn coral and colonial coral as well as the ubiquitous fragmental echino- derm and bryozoan debris. 59ACr-29f is a fossil collec- tion (table 2). 59ACr-29 and 59ACr-28f are chips taken to represent lithology ._____- 27. (In lower part of Mik-a of pl. 2B) Dolomitic limestone, dolo- mite, and chert. Medium-gray to medium-dark-gray partly dolomitized (commonly 15-50 percent - dolomite) _ coarse- grained - crinoid - biomicro- sparite, chiefly with 25-50 percent - fragmental - fossil material, and clayey(?) mi- crosparite. Subordinate me- dium-light-gray very finely crystalline biogenic dolomite- dolomitized clayey(?) coarse- grained - crinoid - biomicro- sparite and _ fossiliferous micrite, with 1-40 percent ghosts and calcite relicts of fragmental fossils, and com- monly 60-80 percent dolomite. Grayish-black chert occurs chiefly as relatively continu- ous nodular zones 1-6 in. thick as well as small lenticular nodules, oriented along the bedding. Chert makes up about 10 percent of the rocks of the unit. The limestone is in beds 1 in. to 2% ft thick and generally shows some in- ternal lamination. Bedding surfaces generally appear even and continuous. Fossil material includes horn corals -particularly abundant near top of unit-as well as echinoderm - and - bryozoan debris. 59ACr-27f (table 2) is fossil collection from upper 10 ft of unit. 59ACr-27 con- MEASURED BEDROCK SECTIONS Thickness (feet) Unit Cumulative 375 38,4944 sists of chips taken to repre- sent lithology ...._._.._......__._.._ 28. (In lower part of Mik-a of pl. 29. 2B) Dolomite and dolomitic limestone, with chert. Medium- gray to - medium-dark-gray fine- to medium-crystalline dol- omite and dolomitic limestone -dolomitized (chiefly from 20-65 percent dolomite) very fine to very coarse grained biosparite and biomicrosparite (commonly with about 60 per- cent fragmental fossil relicts and ghosts). Pale-yellowish- brown finely crystalline lami- nated - dolomite-dolomitized (to more than 95 percent) cur- rent(?) laminated micrite or very fine calcarenite. Car- bonate rocks locally include a few percent spongy chert that is discernible only in micro- scopic examination. The car- bonate beds range in thickness from less than 1 in. to about 5 in., averaging about 4 in., and are separated by bedding oriented zones of dark-gray to grayish-black chert averaging about 3 in. thick but ranging from 1 in. to 5 in. in remark- ably continuous strata with only minor pinching and swelling. Chert makes up about 80 percent of unit. A few dolomite beds near top of unit are thicker, as much as 2 ft thick, and contain less chert. The only recognized fossil material was crinoid col- umnals and a few indistinct spiny or spicular structures in some of the chert. 59ACr-26 consists of chips taken to represent lithology ___ (Lowermost part of Mlk-a of pl. 2B) Dolomite, chert, and sub- ordinate limestone. Medium- light-gray medium-crystalline dolomite-probably a dolo- mitized faintly laminated fos- sil-bearing micrite, generally containing less than 5 percent allochem ghosts-interbedded with medium-dark-gray but otherwise similar medium- crystalline dolomite and light- gray - very - coarse-grained crinoid biosparite (which may be partly a biomicrosparite). 48 Thickness (feet) Unit Cumulative 47 3,5417+ 83 3,624+ 44 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA Kogruk(?) Formation-Continued Nasorak - Formation, The dolomite is in thick beds, generally 2%-7 ft thick, con- taining abundant (locally as much as 60 percent) thin (about 2 in. thick) continuous zones of grayish-black chert. Grayish-black and light-medi- um-gray chert also occurs as irregular nodules. Recogniz- able fossil material is chiefly crinoid columnals as relict calcite in chert and as ghosts in dolomite and ghosts of Bryozoa along lamination in dolomite. 59ACr-25 consists of chips taken to represent lithol0@y | .!;.....! . Total thickness of Ko- Thickness (feet) Unit Cumulative 46 3,670+ gruk(?) Formation .__.3,670-4 (500?) conformable contact (actually, the basal four units of the Kogruk(?) Formation together with the top unit of the underlying Nasorak Formation, appear to be a transition zone rep- resenting the gradual, alternating change of depositional environ- ments represented by the two formations). NASORAK FORMATION Kogruk(?) Formation. Conformable contact. Upper member of the Nasorak For- mation (Minu): 1. (MiInu-h of pl. 2B) Dolomite, dolomitic limestone, calcareous shale, and chert. Dark-gray finely crystalline biogenic dolo- mite and dolomitic limestone- dolomitized and partly dolomi- tized crinoid-bryozoan coarse- to very coarse grained biomi- crite, containing from 20-60 percent fragmental fossil ma- terial, and with replacement dolomite ranging from 20 to 80 percent; rhythmically in- terbedded with dark-gray thin laminated carbonate mudstone or calcareous shale-partly dolomitized micrite and fos- siliferous micrite. - Several beds of medium-gray partly dolomitized - bryozoan-crinoid coarse biosparite interbedded at widely spaced irregular in- tervals in lower half of unit. Grayish-black chert forms from 5-15 percent of most of the limy beds, chiefly as ir- regular nodules of widely ranging size (as much as 1% ft in diameter, but commonly smaller) in the limestone, with which they commonly have in- distinct gradational borders. The limestone beds range in thickness from less than 1 in. to about 2 ft; but thick beds are rare and found only in upper part of unit. More generally, a gradational in- crease in thickness upward from an average of about 6 in. in the lower part to about 1 ft in upper part. The inter- bedded carbonate mudstone forms partings as much as 3 in. in thickness; - gradual decrease in thickness and abundance of these partings from lower part of unit to top. Fossils include colonial corals and brachiopods as well as echinoderm and bryozoan debris. Colonial coral heads locally stand out as white lenses as much as 1 ft thick and 1% ft long in the lime- stone beds (fig. 7). 59ACr-22f, 59ACf-23f, and 59ACr-24f (table 2) are fossil collections. 59Acr-22, 59Acr-23, and a split from 59ACr-24f consist of chips taken to represent lithology 2. Covered interval. Rocks prob- ably similar to unit 1 but may be gradational to rock types of unit 3 below. Possibility of faulting cannot be completely ruled out, but no major dis- placement could be found along probable projection of the zone. Stratigraphic thick- ness represented ___________ 3. (Upper two-thirds of Minu-g of pl. 2B) Limestone, partly dolomitic, and _ calcareous shale, with subordinate chert, rhythmically interbedded bi- omicrite and carbonate mud- stone or calcareous shale. Medium-gray (weathers to light gray and pale grayish orange) coarse-grained cri- noid-bryozoan biomicrite lo- cally with irregular small Unit 586 85 Thickness feet) Cumulative 586 671 patches and laminae where intergranular - material - is sparry calcite cement) with 40-50 percent fragmental fos- sil allochems, in continuous but unevenly undulating beds averaging about 3 in. thick, but as much as 1 ft thick. Rhythmically interbedded with dark-gray thin-laminated clayey micrite and fossilifer- ous micrite in beds commonly less than 1 in. thick. Both are commonly partly dolomitized, and may contain as much as 15 percent dolomite locally, chiefly as dolomitized micrite matrix and as rims around fossil allochems. - Grayish- black chert-silicified biomi- crite and micrite-makes up less than 10 percent of the unit, chiefly as irregular zones of nodules within and oriented with the limestone beds. Many paired sets of biomicrite and fossiliferous micrite beds may be graded beds, with sharp bedding sur- faces at base of calcarenite bed and a gradual decrease upward in maximum size and abundance of allochems through an indistinct com- monly intertonguing contact with the overlying carbonate mudstone, whose top is marked by a sharply defined surface at base of next overlying calcarenite bed. The lami- nated micrite (carbonate mud- stone) - commonly makes up about 5-10 percent of unit; in central part of unit, where beds increase in thickness to as much as 6 in., it makes up a proportionately much great- er part of unit (locally as much as 30 percent). Fossils include horn corals, colonial coral, brachiopod fragments, Bryozoa (including Archi- medes), - and - echinoderm debris. 59ACr-lf (table 2) is a fossil collection. 59ACr- 1 and 59ACr-la consist of chips taken to represent lithology MEASURED BEDROCK SECTIONS Upper member of the Nasorak Formation-Continued Thickness (feet) Unit Cumulative 375 1,046 4, (Upper part of lower one-third of Minu-g of pl. 2B) Lime- stone, partly dolomitic, and calcareous shale, with sub- ordinate chert. Rhythmically interbedded biomicrite and fossiliferous clayey micrite similar to unit 3 above, but with an abrupt increase in proportion of thin laminated micrite and fossiliferous mi- crite to about 40 percent of unit. 59ACr-2 consists of chips taken to represent lithology . sess chiens 5. (Middle part of lower one-third of Minu-g of pl. 2B) Lime- stone, partly dolomitic, and calcareous shale, with sub- ordinate chert. Rhythmically interbedded biomicrite and laminated clayey micrite simi- lar to units 3 and 4 above, but with abrupt decrease in pro- portion of interbedded lami- nated micrite to 5-10 percent. 59ACr-3 consists of chips taken to represent lithology ... 6. (Lower part of lower one-third of Minu-g of pl. 2B) Lime- stone, partly dolomitic, and calcareous shale, with sub- ordinate chert. Rhythmically interbedded biomicrite and laminated clayey micrite simi- lar to units 3-5 above, but with about 40 percent lami- nated micrite interbeds. Also different in that some fossili- ferous micrite is locally dolo- mitized to a rock containing about 80 percent finely erys- talline dolomite with relict calcite allochems making up most of remainder. 59ACr-4 consists of chips taken to rep- resent lithology __________-- 7. (Upper part of Minu-f of pl. 2B) Calcareous shale and limestone, partly dolomitic, with minor chert. Rhythmi- cally interbedded biomicrite and laminated clayey micrite, locally as much as 60 percent dolomitized to finely crystal- line dolomite. Very similar to unit 6 above, but with abrupt change at contact to about 60 percent laminated micrite and fossiliferous micrite. 59¥ACr-5 45 Thickness (feet) Unit Cumulative 34 1,080 25 1,105 64 1,169 46 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA Upper member of the Nasorak Formation-Continued consists of chips taken to rep- resent lithology ._.... 8. (Middle part of Minu-f of pl. 9. 2B) Limestone and chert. Distinctive unevenly bedded unit. Medium-gray and dark- gray partly dolomitized partly silicified fossil-bearing mi- crite; and grayish-black chert (silicified fossil-bearing mi- crite) chiefly as irregularly lenticular nodules in the lime- stone, commonly having in- distinct gradational contacts with the limestone. Beds ap- pear relatively continuous and average about 9 in. in thick- ness, but pinch and swell from about 3 in. to about 1% ft in thickness, giving rise to a nodular aspect of the beds; adjacent beds appear to com- pensate one another. One dip- slope exposure shows that the nodular features are roughly circular in plan and average about 1 ft in diameter. Chert is commonly in the central parts of the "nodules," but does not seem to be requisite for their formation. They are probably differential compac- tion features.. 59ACr-6 con- sists of chips taken to repre- sent lithology ........._..._..!... (Lower part of Minu-f of pl. 2B) Shale and subordinate limestone. Grayish-black cal- careous clay shale with abundant close-spaced sheared bedding surfaces, many show- ing small slickenslides; with 20-30 percent interbedded medium-dark-gray to dark- gray clayey micrite, locally containing as much as 30 per- cent unidentified calcite allo- chems, but commonly 5 per- cent or less. The limestone (clayey micrite) occurs in lenses as much as 4 in. thick and about 3 ft long and ap- pears to follow specific hori- zons, so that some resemble boudinage structures. 59ACr- 7 consists of chips taken to represent lithology ________ 10. (Minu-e of pl. 2B) Limestone and calcareous shale. Chiefly Thickness (feet) Unit Cumulative 26 1,195 49 1,244 41 1,285 medium-gray partly dolomi- tized (ranging from 10 to 40 percent replacement dolomite) laminated Bryozoa-bearing micrite, probably containing some clay, with fragmental fossil material commonly mak- ing up 7-10 percent of the rock; but locally the rock is a coarse crinoid biomicrite with fragmental fossil mate- rial ranging from 50 to 90 percent and including a few foraminifera. The limestone is chiefly in beds about 1 ft thick or less, rhythmically interbedded with shaly clayey carbonaceous micrite in beds as much as 4 in. thick that makes up about 30 percent of unit. Sets consisting of a limestone bed and a shaly interbed in many places re- semble graded beds; such sets commonly range in thickness from 1 to 2 ft. Recognizable fossils include horn corals and colonial corals (most heads making discrete small lenses within limestone beds) as well as fragmental echinoderm and leafy bryozoan debris. 59ACr- 8f (table 2) is a fossil collec- tion. 59Acr-8 consists of chips taken to represent lithology (Bedding plant fault within unit 10 rocks makes total thickness of unit uncertain.) (Upper one-fourth of Minu-d of pl. 2B) Limestone and calcare- ous shale. Very similar to unit 10 above, but includes about 40 percent shaly mi- crite, probably containing some clay; the limestone beds are more generally medium dark gray to dark gray and contain a generally higher proportion (commonly 30-40 percent) of fragmental fossil debris and may locally contain as much as 20 percent fine quartz silt. In addition, the thickness of sets of limestone and interbedded mudstone is more nearly uniform and gen- erally about 1% ft thick. Recognizable fossils include horn corals, colonial corals (chiefly as lenticular heads made up of single colonies Unit Cumulative Thickness (feet) 50(?) 1,835 from 1 in. to 1 ft thick and from 6 in. to 5 ft long), as well as fragmental echinoderm and leafy bryozoan debris. 59ACr-8Af (table 2) is a fos- sil collection. 59ACr-8a con- sists of chips taken to repre- sent lithology .__.........._.____... 12. (Lower part of upper one-half of Minu-d of pl. 2B) Lime- stone, with minor chert and dolomite. - Chiefly medium- gray to medium-dark-gray laminated fossiliferous mi- crite and medium-grained to very coarse grained crinoid bryozoan biomicrite (contain- ing as much as 70 percent fragmental fossil debris), locally dolomitized (as much as but generally less than 50 percent dolomitized, and local- ly silicified to grayish-black chert) (cherts commonly con- tain as much as 80 percent euhedral very finely crystal- line dolomite, and may contain as much as 60 percent relict calcite). Chert and dolomite form irregular patches and zones in and along the thin limestone beds and make up about 5 percent and 20 per- cent of the unit volume, re- spectively. A few distinctive interbeds of very coarse grained - crinoid - biosparite that are also dolomitized in irregular patches, locally con- tain as much as 50 percent dolomite, chiefly as replace- ment of intergranular cement. Individual - limestone - beds range from less than 1 in. to about 1 ft in thickness, gen- erally averaging about 10 in. thick. Thin shaly partings, averaging about % in. thick, commonly separate the lime- stone beds, but all together make up only about 1-5 per- cent of unit. Except for frag- mental echinoderm and leafy bryozoan debris, no fossils were recognized, and none were collected, 59ACr-9 con- sists of chips taken to repre- sent MEASURED BEDROCK SECTIONS 47 Upper member of the Nasorak Formation-Continued Thickness (feet) Unit Cumulative 66 1,401 85 1,486 Thickness (feet) Unit Cumulative 13. (Topmost part of lower one-half of Minu-d of pl. 2B) Lime- stone. - Medium-gray - very coarse grained - biosparite, locally partly dolomitized, con- taining local coral fragments. Individual beds as much as 8% ft thick, and unit stands out as a thick-bedded zone between the thinner bedded units - above and - below. bB9ACr-9a consists of chips taken to represent lithology --- 14 1,500 14. (Lower one-half of Minu-d of pl. 2B) Limestone, with minor chert and dolomite. Virtually the same lithology and bed- ding characteristics as unit 12. A few of the chert speci- mens show possible ghosts of spicules in thin section (fig. 24). 59ACr-9b consists of chips taken to represent Hthology 127 1,627 15. (Upper one-third of Minu-c of pl. 2B) Shale and limestone. Grayish-black silty calcareous shale or shaly micrite (prob- ably dolomitized in places), in beds %-6 in. thick averaging about 3 in.; interbedded dark- gray dolomitized (as much as FigurE 24.-Texture of spicular(?) chert in the Nasorak Formation. Most of the light-gray material is very finely crystalline to aphanitic micro- granular quartz. A few percent dolomite is also present in the light- colored fraction, as disseminated very finely crystalline euhedral rhombs. The dark material is chiefly disseminated fine carbon and tiny crystals of disseminated pyrite, but it also includes a few percent of very finely crystalline calcite, 59ACr-9h#2. 48 AREAL GEOLOGY, VICINITY OF CHARI\T SITE, LISBURNE PENINSULA, ALASKA Upper member of the Nasorak Formation-Continued 16. 40 percent) silty (about 10 percent quartz silt) fine- grained biomicrite containing as much as 50 percent frag- mental fossil material, now chiefly ghosts, in discontinuous uneven beds %&-6 in. thick. The calcareous shale or shaly micrite makes up about 50 percent of the unit. 59ACr- 10 consists of chips taken to represent lithology _________ (Lower two-thirds of Minu-c of pl. 2B) Limestone, partly silicified and partly dolomi- tized. Chiefly medium-gray very coarse grained crinoid biomicrite containing as much as 60 percent fragmental fos- sil material, locally with as much as 40 percent replace- ment chert and 15 percent re- placement dolomite as matrix and rimming cell structures in and around calcite allo- chems; in even continuous beds ranging in thickness from 2 in. to 1% ft (fig. 6). Dark-gray thinly laminated dolomite-dolomitized micrite -makes up 5-10 percent of unit as very thin interbeds, and laminae within the lime- stone beds. Dark-gray chert occurs as thin (% to 8 in. thick) discontinuous irregu- larly surfaced zones along bedding planes and a few small irregular nodules within limestone beds, The thin in- ternal lamination of much of the limestone has a distinctive "crinkly" uneven aspect, per- haps as a result of differential compaction over the coarse echinoderm debris. 59ACr- 11f (table 2) is a fossil collec- tion. 59ACr-11 consists of chips taken to represent lith- dlogy . 1....0... ...er acces a lenee 17. (MInu-b of pl, 2B) Chert, lime- stone (partly dolomitized), and calcareous shale. Grayish- black chert-silicified (60-75 percent) carbonaceous (about 15 percent black opaque films) micrite; and - medium-dark- gray dolomitized (commonly from 10-50 percent replace- ment dolomite in apparently Thickness (feet) Unit Cumulative 12 1,639 26 1,665 irregular patchy zones) silt- bearing (generally less than 5 percent quartz silt) carbo- naceous shaly micrite that may contain a few percent clay locally. The chert occurs as indistinctly bordered lenti- cular nodules within the lime- stone beds and makes up about 50 percent of the unit. The chert-limestone beds appear relatively continuous and are rhythmically interbedded with thin (commonly less than % in. thick) calcareous shale partings, but have very un- even undulating bedding sur- faces such that individual beds pinch and swell in thickness from about 1 in. to as much as 8 in. in distances of 1-2 ft. This gives the chert-limestone beds the general aspects of zones of nearly disconnected lenticular nodules alined along bedding. Thinning of one bed is generally compensated by thickening of adjacent beds, suggesting a compaction ori- gin for the nodular aspect. In lower 25 ft of unit, chert content decreases slightly- to about 85 percent-shaly in- terbeds increase in thickness to as much as 1 in. -making up as much as 10 percent of the rocks-and some thin zones are not so prominently "nodular" in bed aspect. Basal 6 ft of unit is a zone con- taining a few thick beds (as much as 4 ft thick) of coarse- grained - crinoid biomicrite from which a few horn corals and Bryozoa were collected (fig. 5). 59ACr-12f (table 2) is a fossil collection. 59ACr- 12 consists of chips taken to represent lithology .______ 18. (Upper part of Minu-a of pl. 2B) Mudstone and limestone. Grayish-black calcareous silt clay mudstone and interbedded dark-gray - silty - clayey(?) partly dolomitized fossil-bear- ing micrite. In upper 25 ft of unit the mudstone is in thin, locally shaly, beds 1-4 in. Thick, rhythmically inter- bedded with silty micrite beds of similar thickness (fig. 5). Thickness (feet) Unit Cumulative 75 1,740 In lower 33 ft of unit lime- stone is virtually absent; the mudstone is in beds as much at 1 ft thick and contains minor but distinctive small patches of pyrites and pyri- tized brachiopod shells and other shell fragments. Bed- ding is masked in places by close-spaced fracture cleavage that gives the outcrop a shaly aspect but only locally follows direction of bedding. 59ACr- 13f (table 2) is a fossil collec- tion. 59ACr-13 consists of chips taken to represent fithology .. ciel... 19. (Lower part of Minu-a of pl. 2B) Limestone. _ Medium- dark-gray coarse-grained cri- noid biomicrite, locally partly dolomitized - in - irregularly bedded strata ranging in thickness from less than 1 in. to as much as 4 ft. Dark-gray silty(?) micrite in thin discon- tinuous laminae and partings as much as 1 in. thick are sub- ordinate interbeds. Echino- derm debris and subordinate bryozoan fragments are the only fossils recognized. 59ACr.14 consists of chips MEASURED BEDROCK SECTIONS 49 Upper member of the Nasorak Formation-Continued Thickness (feet) Unit Cumulative 58 1,798 taken to represent lithology.134- (20) 1,8114+ (20) Total thickness of upper member of the Nasorak Thickness (feet) Unit Cumulative to that in unit 16. Fossils in- include several brachiopods and, in thin section, a few possible Foraminifera as well as echinoderm and bryozoan debris. 59Acr-15f (table 2) is a fossil collection, of which a split serves to represent the lithology ...l... iii cs. 110+(15) 1,920+ (20?) Lower member of the Nasorak For- mation (MIinl) : 21. (Min] of pl. 2B) Mudstone and limestone. Very similar to unit 18, but no pyritized fos- sils were noted. Base not exposed ...... .._. 1,970 + (207) In a structurally very dis- turbed zone about 700 ft farther east, rocks thought to be appropriately assigned to unit 21 are associated with limestone beds, chiefly coarse- grained medium-dark-gray biomicrite, that includes a brachiopod fauna closely simi- lar to that collected from lower member of Nasorak Formation in sea cliff section at Cape Thompson, pl. 24. 59ACr-19-20f and 59ACr- 21f are fossil collections (table 2), 59ACr-19-20 and 59ACr- 21 consists of chips taken to represent lithology. Probably several tens of feet of beds are represented ..... (50?) 1,9704+(707) Base not exposed. Formation ... 1,811+ (20) Total thickness of lower Cape Thompson Member of the member .-......_...__...___. as 50+ (70?) Nasorak Formation (MiInc): Total thickness of Nasorak 20. (Mince of pl. 2B) Limestone. Formation ..:......._.:... .s... 1,9704+ (707?) Medium-gray (weathers to pale grayish orange) partly dolomitized (locally as much as 15 percent dolomitized micrite matrix and rims on fossil fragments) very coarse grained crinoid-bryozoan bio- microsparite (in places a fine rudite rather than a very coarse arenite) generally con- taining about 75 percent frag- mental fossil allochems. Irregularly bedded discontinu- ous(?) relatively even sur- faced beds range in thickness from a few inches to about 1% ft. "Crinkly" uneven dis- continuous internal lamina- tion is common, very similar Saligvik thrust fault zone. Kogruk(?) Formation (younger than Nasorak Formation). PERMIAN AND TRIASSIC ROCKS-WEST SECTIONS [Sections of Permian and Triassic rocks measured in sea-cliff exposures at Agate Rock, by Reuben Kachadoorian and I. L. Tailleur, July 1958] SHUBLIK FORMATION (TRIASSIC) Ogotoruk Formation (greenish-black claystone and grayish-black silt- stone, sheared near contact). Probable disconformity. (Although beds are generally accordant and relations are somewhat obscured by shearing of basal beds of over- lying Ogotoruk, there is a few feet of relief on the contact that may be attributable to pre-Ogotoruk erosion of uppermost beds of the Shublik.) 50 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PEN INSULA, ALASKA Shublik Formation ( ): %, ® 10. 11, Shale and minor chert. Dark- gray shale, generally thinly bedded in lower half of unit (beds %&-1 in. thick), but with some thicker beds (as much as 1 ft thick) in upper half. Top 5 ft of unit contains a few chert beds, 2-4 in. thick, interbedded with shale in beds about 1 ft thick ...._..______..___ Shale. Dark-gray thin-bedded hard (siliceous?) shale ______ Chert. Dark-medium-gray chert in beds averaging 5 in. thick; beds in upper half 5-10 in. thick, and beds in lower half 2-5 in. thick ..... ...;... Chert and interbedded shale. Chert in beds 2-4 in. thick, interbedded with shale in beds 1-2 in. thick ...... __... Limestone. Medium-gray lime- stone in beds 1-4 in. thick ___ Shear zone ...... :.... _ .._ Cherty limestone with abundant Monotis fossils. Cherty lime- stone in beds 1-8 in. thick, commonly medium gray in the central part of a bed grading to light gray at the margins, with a few interbeds of shale. Shear zone 1 ft thick 6 ft below top of unit. Monotis abundant throughout the unit _._... . _. acr caa ct Chert and shale. Black chert in beds %-2 in. thick, inter- bedded with black calcareous shale, most commonly - as paper-thin laminae but locally as much as 1 in. thick ______. Chert and shale. Black chert in beds 1-6 in. thick, with slightly undulating bedding surfaces; interbedded calcar- eous shale in beds as much as 2 in. thick. Basal part of this unit is gradational with top of underlying unit 10 ___. Calcareous siltstone and shale. Thinly bedded limy siltstone with interbedded shale. In- cludes one marcasite-rich zone about 9 in. thick in a shaly bed that grades into limy giltstone ..-... ... L. a_ ~.. Interval inaccessible in cliff. Rocks weather dark gray to black with yellow stain _____ Unit 28 1.5 13 28.5 15 Thickness (feet) Cumulative 28 24.5 87.5 43.5 49.5 51 74.5 838.5 98.5 104.5 108.5 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 28. 24, Chert and shale. Medium-gray chert with a dull to glassy luster in thin slightly uneven nodular beds 1-8 in. thick. A zone of shale in beds gener- ally less than 2 in. thick forms the basal 8 ft of the unit ___. Chert and shale. Interbedded chert and shale in approxi- mately equal amounts in beds 3-6 in. thick; contains some concretions as much as 3 in. in diameter ....._...._...._......_ Shale. Thinly bedded shale with concretions as much as 1 in. in diameter .._... ....__ Shale with some chert. Predom- inantly shale but including several chert beds about 3 in. thick. Sparse concretions as much as 3 in, in diameter ___ Massive chert; locally silty ___. Chert. Interbedded chert and silty chert; locally weathers yellow to dark yellow orange.. Shale and chert. Predominantly shale with a few chert beds 2-8 in. thick __. Cherty silt ...... _._... Shale, mudstone, and chert. Black shale with interbedded mudstone and silty shale in zones %&-2 in. thick. Top half of unit contains a few dark- gray to black layers of chert about 1 in. thick _...... Chert. Dark-gray slightly silty in beds ranging in thickness from 1 or 2 in. in lower part of unit to 6 in. in upper part. Zones 44-2 in. thick that weather to dark yellow give the unit an interbedded aspect Shale. Black shaly mudstone in- terbedded with silty shale in layers %&-2 in, thick. Upper half of unit contains a few dark-gray to black chert lay- ers about 1 in. thick ________ Chert. Dark-gray earthy chert that weathers to a dark yellow in beds that grade in thickness from 1 or 2 in. at base to about 6 in. at top _........_..._._._ Shale. Black shaly mudstone and silty shale in beds %-3 in. thick. A few chert inter- beds about 1 in. thick occur in upper 2 ft of unit ___ 17 18 2.5 . Thickness (feet) Cumulative 125.5 181.5 188.5 187.5 155.5 157.5 160.5 161.3 168.8 168.8 171.8 174.8 180.8 Shublik Formation-Continued 25. Chert. Dark-gray earthy chert beds ranging in thickness from 1 or 2 in. at base to 6 in. at top. Locally, zones from %4e-2 in. thick selec- tively weathered to dark- yellow .. cc sl nll 26. Shale. Black shaly mudstone and silty shale interbedded in layers from % to 3 in. thick. Top 1% ft of unit contains a few chert interbeds about 1 in. thick -_. _L L...... ls cal 27. Shale. Medium-dark-gray finely laminated muddy shale that weathers to yellowish orange. 28. Shale. Soft black shale in beds commonly ranging in thick- ness from 4e to 2 in. and averaging about 1% in. Up- per 10 ft of unit has a rela- tively massive aspect. Basal 3 ft is a clay shale with a probable high-iron content, as it weathers to dark yellow ___. Possible unconformity (beds may be very slightly discordant). Siksikpuk Formation. SIKSIKPUK FORMATION Shublik Formation. Possible unconformity (beds may be very slightly discordant). Siksikpuk Formation (Ps): 1. Chert and argillite, nodular. Greenish-gray to greenish- black chert in thin (as much as 6 in. thick) lenticular nod- ules that make up relatively continuous uneven beds that average 3-4 in. thick. Inter- bedded with greenish-gray argillite beds of similar thick- ness ..... _L... cl nl.. 2. Chert and argillite, evenly bedded. Interbedded chert and argillite similar to the rocks of unit 1, but in relatively continuous even-surfaced (rather than nodular) beds that commonly are 2-4 in. thick, although a few are as thin as 1 in. 3. Argillite, with only - minor chert. Greenish-gray argil- lite predominates in beds as much as 8 in. thick, averaging 4 in. One 4-in.-thick greenish- gray chert layer occurs 4 ft below top of unit; 13 ft below MEASURED BEDROCK SECTIONS 51 Thickness (feet) Unit Cumulative 4 184.8 3 187.8 2 189.8 18 202.8 (PERMTAN) 43 48 60 103 Accurdant contact: Thickness (feet) Unit Cumulative top of unit is a distorted nod- ular red jasperoid zone about 8 ft thick. In lower part of unit some dark streaking, about 2 in. thick, that ex- presses stratification. Base of unit not exposed __________ sl 2847? 111? Unit 3 is oldest stratigraphic unit exposed at the surface in core of a minor anticline, whose banded aspect in outcrop gave Agate Rock its name. PERMIAN AND TRIASSIC ROCKS-EAST SECTIONS [Sections of Permian and Triassic rocks in sea-cliff exposures at the mouth of Imikrak Creek and nearby to the west. Shublik Formation measured by C. L. Sainsbury, R. H. Campbell, Reuben Kachadoorian, and D. W. Scholl, August 1958; the lower part of the Siksikpuk Formation added by R. H. Campbell and D. R. Currey, August 1959] SHUBLIK FORMATION (TRIASSIC) Ogotoruk Formation: Grayish-black thin-bedded to shaly ar- gillite, with interbedded mudstone and siltstone in beds M4e-4 in. thick; persistent but discontinuous zone of red alteration within a few feet of the underlying contact. The Ogotoruk beds are intensely sheared and slickensided- much more so than the more competent beds of the under- lying Shublik. The basal Ogotoruk beds are covered, as is the contact, in the immediate vicinity of the measured Shublik section. They are, however, exposed in the sea cliffs in a minor anticline about % mile west of the expo- sures where the section was measured. The contact appears to be an accordant depositional contact, even though the overlying beds are intensely sheared. The shearing is interpreted as the nat- ural response of the relatively incompetent Ogotoruk rocks to the folding of the more competent Shublik beds, together with the effects of subsequent drag from above by the over- riding Ibrulikorak-Agate Rock thrust sheet. Again, the contact zone is covered in the immediate vicinity of the measured Shublik section, and the relations are described from an outcrop to the west-the same outcrop as that from which the above description of the basal Ogotoruk beds was made. Thickness (feet) Cumulative Shublik Formation ( ): 1. Mostly covered. Float indicates the topmost beds are greenish- gray to black siltstone or argillite, underlain by a zone of - shaly - Monotis-bearing limestone, underlain in turn by shale(?). (Thickness esti- mates subject to error due to poor exposure and to the geometry - gently-dipping beds intersecting gentle top- ographic slopes.) ._________ 30 30 2. Chert, interval mostly covered (thickness estimated). Gray- ish-black - to - medium-gray chert in beds averaging about 4 -in. thick .:.... .A... .s 10 40 52 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA Shublik Formation-Continued ”$3,217" Thickness Unit Cumulative Unit G “gumulative measured, is predominantly 3. Limestone and chert. Medium- shale a"" ~8B 200 Accordant contact. Siksikpuk Formation. olive-gray to medium-gray (weathers to grayish orange) Monotis-rich limestone, locally cherty (including some ir- regular small patches of dark- reddish-brown chert), in beds generally from 2 in. to 1 ft thick; some interbedded dark- SIKSIKPUK FORMATION (PERMIAN) Shublik Formation. Accordant contact. Siksikpuk Formation (Ps): 1. Argillite.: Greenish-gray argil- gray to greenish-gray chert. Unit crops out as a relatively continuous series of ledges with gentler more generally lite in a single relatively con- tinuous bed 1-2 ft thick. Internally laminated, with relatively sparse thin discon- tinuous lenticular laminae of vegetated slopes above and 4 emy _ aat aon of 20 60 slightly darker color ___ 2 2 4. Covered interval. Subdued slope- # Ch; Z; d eznd ”313125: magreégfg: forming unit, may {be shaly gray chert-apparently a sili- here, but to the west limestone cified argillite, as it displays y Che]? Slmflar. fo unt 3 the same internally laminated above, with some interbedded sirlicture as the argillite= black shale, crop out at what Fredominates as coriinuous appears to be the same strat- fie Os averaging about 3 in igraphic horizon as this cov- thick. Th ih grt is - Fecularl f ered interval (thickness esti- interim 3 deed jviths grienishy mated) ->" n.". .~ 5 95 2 ated) 7 % gray argillite beds that aver- 5. Chert and shale, with some age about 1 in. thick 15 17 limestone. Grayish-black to aq: fesatad "red" and dhol. In. Lede 3. Argillite, variegated red and 1-4 in. thick; interbedded with ame o a black to greenish-black shale thick, regularly inst’erlayered and subordinate interbedded with ,moderate-red argillite in {gigogséieafini lmzlestfinf. relatively continuous strati- her Ciet L -And Shale graphic zones commonly about locally contain thin laminae 1 ft thick. The: interlayerin in which Halobia fossils are Of, red ar'ld green genitalli sion! ssc en.... ah. - (139 follows bedding and from a 6. Shale. Predominantly _ thin- distance looks like true in- Edged black shale, with a terbedding; in detail, however, distinct sulfurous smell when edges of red layers are very freshly broken; irregularly uneven in many places, and interbedded .w1th minor crosscutting irregular to vein- amounts of thin-bedded dark like apophyses of red into gray chert. In places the shale green indicate that the zones near the base weathers to red- of red argillite formed by al- dish colors. A few feet above teration of green argillite. Red the base, a continuous thin zones appear to reflect per- (_1—2 in. thick) layer of very meable horizons, and many of light gray bentonitic(?) clay. the crosscutting apophyses Considerable lateral gradation follow joints ._. ..__.._._._....__ 15 82 of the unit is indicated by the presence, a short distance to the west, of a 12-ft-thick zone containing abundant thin- to medium-bedded greenish-gray argillite and limy argillite in which Monotis and Halobia fossils are locally abundant; this zone lies at about upper middle of unit, which, where 4. Argillite, containing sparse cal- careous fossils near base, and minor - interbedded - chert. Chiefly greenish-gray to dark- greenish-gray argillite, com- monly weathering to olive gray and locally to various reddish browns. Most com- monly beds are 1-3 ft thick, with faint internal laminae MEASURED BEDROCK SECTIONS 53 Siksikpuk Formation-Continued T};ifcel:1ta)ess Thickness Unit Cumulative oke. " n cates that units are accordant; best expressed as color band- ing on weathered surfaces. Greenish-gray chert in con- tinuous even layers, most com- monly 1-2 in. thick, inter- bedded in argillite at irregular intervals. Chert makes up very minor part of unit. Carbonate veinlets heal fractures in both argillite and chert in some places. Near base of unit, two argillite beds contain sparsely scattered carbonate fossils that include only brachiopods and gastropods. 59ACr-89f is a collection of fossils. 59ACr- 89 consists of chips taken to represent lithology. A zone of fracturing and high-angle faulting intersects the sea coast at the mouth of Imikrak Creek; thickness exposed is therefore minimum, and a stratigraphic thickness of 20 total thickness of Siksikpuk, as estimated from structure sections, probably no greater than 400 ft. Consequently, it is estimated that no more than 100 ft of lower part of Siksikpuk Formation is missing from these sea-cliff exposures.) Tupik Formation of the Lisburne Group. JURASSIC OR CRETACEOUS ROCKS The Ogotoruk and Telavirak Formations, as well as many parts of the Kisimilok and Fortress Moun- tain(?) Formations, are made up of a monotonous sequence of similar lithologic types in variable pro- portions and in beds of variable thickness. The following classification was devised for field use in these rocks to serve as an abbreviated description of the general lithology and bedding characteristics of an outcrop, to which distinguishing characteris- tics, if any, could be added. The classification is arbitrary, and all gradations between the various ft or more may be missing...... 2104-907 23924207 types may be found. It has, however, proved to be 5. Black shale, argillite, and chert, . s s R covered. Predemurant. a Fonvement field notation and for brevity is re- ly grayish-black gypsiferous tained in describing the measured section below. (?) limonitic(?) shale that weathers to variegated shades M. Massive to thick-bedded medium-dark-gray to dark-gray of red, orange, yellow, red mudstone having little or no internal bedding expression. brown, and white against the In many places close-spaced fracture cleavage-most com- blackish slope. In upper 10- monly axial plane cleavage, but, locally, pencil slates have 15 ft of unit there are some formed at some fold crests and troughs. Rarely fissile thin (%-3 in. thick) interbeds enough to be called a shale. of dark-greenish-gray argil- Mg. A dark-greenish-gray subtype of M, commonly sheared. lite and greenish-gray chert. 45 277 +20? May superficially resemble some of the greenish argillites 6. Argillite and minor limestone. of the Siksikpuk and Shublik Formations. Generally more Dark-gray to dark-greenish- argillaceous than most of the type-M rocks. Common at, gray argillite, commonly cal- but not restricted to, the base of the Ogotoruk Formation. s: and 'in places silty, Mt. Resembles M but commonly has recognizable internal predommzjltes ( beds as m.uch bedding expressed as thin laminae of alternating dark-gray a.s 5 ft thick; internal 1am1n_a- and slightly lighter colored layers containing slightly more tloriC Fxpressecil as uneven dlls- abundant quartz silt. 32111: 11121111. ifiikficgzgfizg MS. Mudstone of type M or M t with very tl'lin interbeds of gray zones in predominantly medium-dark-gray fine-gryned .sandy Sllt§tone (gray- darker rock. Ohne, interned. 1 wacke), generally rhythmically interbedded in cycles less in. thick, of medium-dafir- than 2 in. thick. Sandstone beds locally have small bottom ray silty} limestone. contains marks, most of which appear to be casts of small pellets a tew calcarcous fossils: a (fecal?). Low-angle internal cross-lamination is locally horn coral, brachiopods, and visible in sandy siltstone. Cycles are graded beds. a gastropod. 59ACr-88f is a Sm. Zone predominantly M or Mt with prominent irregularly fossil collection. 59ACr-88 interbedded lenses of thick-bedded to massive fine- to me- consists of chips taken to rep- dium-grained muddy sandstone (graywacke). Individual resent lithology. Base of unit beds are apparently discontinuous, but some zones may be not exposed ......_._......___. 204+? P07 +2021" traced a mile or two along the strike. High-angle fault contact. (Farther inland, the map configuration of the Siksikpuk-Tupik contact indi- SM. Interbedded mudstone of type M or Mt and muddy very fine-grained to medium-grained graywacke sandstone in nearly equal amounts. Generally rhythmically interbedded 54 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA in cycles from a few inches to 1% ft thick. The cycles are graded beds. Bottom marks are common and some are large. Carbonaceous trash is abundant in some sandstones, particularly in the Telavirak Formation. Low-angle cross- lamination is moderately common in sandstone beds. The sandstone-mudstone ratio is generally less than 60/40. S. Massive to thick-bedded silty very fine grained to medium- grained graywacke sandstone with little or no mudstone interbedded. Sandstone commonly shows little or no in- ternal bedding laminae, but, locally, a few beds split fairly easily along internal bedding planes on which some oriented mica may be seen. Bottom marks are rare, perhaps because shale interbeds are rare. SMt. Similar to SM but intermediate with S in that cycles and beds are as much as 2 ft thick and sandstone-mudstone ratios are greater than 60/40. Bottom marks are common and may be large. TELAVIRAK FORMATION, PARTIAL SECTION, NIYIKLIK CREEK [Section measured by R. H. Campbell and D. R. Currey, July 22, 1960. Thicknesses measured by pacing the outcrop width of the steeply dipping beds and estimating the correction for local dips] Top not exposed. Beds younger than unit 1 are covered and lie in structurally com- plex terrain. 1: 6. Is Covered. Judging from float, the rocks are chiefly of type SM, similar to unit 2 below. (thickness estimated) ___ Largely covered. Chiefly SM with in- terbedded MS, and MS becomes pre- dominant near the base ____________ Mostly MS with interbedded Mt. Grades from Mt at top, through a central thick zone of MS with abundant car- bonaceous debris and subordinate in- terbedded Mt to Mt again at base Predominantly MS with interbedded SM. Grades from chiefly MS at top; through interbedded MS and SM that, near base, includes a prominent zone of SM with abundant carbona- ceous debris; to MS at base _________ Chiefly MS and some interbedded SM, with minor amounts of Mt inter- bedded in some zones. Sandstones locally carry some carbonaceous de- bris. (The thickness indicated allows a correction for the double repetition of about 15 ft of the beds in one large drag fold exposed in the cutbank of the stream,) ...... .m. nia lca." Chiefly Sm with abundant carbonace- ous debris. Basal 300 ft is largely covered, but appears to contain sub- ordinate interbedded MS, and prob- ably grades to predominantly MS at the base cl la Aal Chiefly SM with only minor inter- bedded MS near base. Well exposed; one small drag fold was seen, and Thickness (feet) Unit Cumulative 100 100 250 350 350 700 200 900 180 1,080 450 1,530 10. 11. 12, 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 28. thickness was corrected to allow for repetition ...... Partly covered. Chiefly Mt with minor interbedded SM, base gradational with underlying unit 9. Locally folded, apparent thickness may be too large by a factor of 2 because of drag folds having high amplitudes and wave lengths of 3-20 ft _______ Rhythmically interbedded strata rang- ing from Ms to Sm in cycle thickness, with subordinate interbedded Mt Chiefly Mt with minor amounts of ir- regularly interbedded phosphorite in lenses as much as 1 in. thick. Locally some structural contortion, but no appreciable repetition _____________ Contorted M with minor Mt and some Mg interbeds; contains a few phos- phorite nodules locally associated with Mg. Contortion does not appear to represent significant repetition __ Largely covered. Appears from float to be largely M or Mt grading to MS at base Chiefly SM with well-developed bottom marks including good load casts and organic(?) bottom marks. Locally a thin phosphorite(?) lens is present in a mudstone interbed. Top 25 ft of unit is gradational into rocks of MS- eycle thickness __.. _._......._._.__L L. Largely covered. Mostly contorted M mudstone Partly covered. Chiefly MS but upper 10 ft of unit is gradational zone to mudstone of overlying unit 14.______ Chiefly SMt with a few interbeds of M. The sandstone beds are as much as 5 ft thick and locally have a slabby in- ternal parting ...... Unit grades from Mt with locally abun- dant phosphorite lenses at base to MS at top Partly covered. Chiefly M, with upper 100 ft of beds grading to Mt, and lower 120 ft of beds have slaty to shaly aspect. Minor amounts of phos- phorite found as nodules in lower middle part of unit, where beds are somewhat contorted ________________ Covered interval ..............____.__LL.L___. Chiefly MS but grades to Mt at top. Lower 150 ft is largely covered ___ Thick unit of M mudstone ________ __ Thin zone of MS having relatively uni- form. strdetufe ...l. ze Sheared, contorted M________________. Thickness (feet) Unit Cumulative 150 1,680 150 1,830 170 2,000 60 2,060 200 2,260 200 2,460 100 2,560 300 2,860 280 8,140 200 3,840 125 8,465 525 3,990 70 4,060 250 4,810 150 4,460 15 - 4,475 25 - 4,500 UNCONSOLIDATED DEPOSITS 55 Thickness (feet) Unit Cumulative 24. Thick unit of MS, partly covered near base. Some drag folding is evident, chiefly with wave lengths of 1-3 ft, and apparent thickness may be too large by as much as one-fourth ___. 450 4,950 25. Interbedded strata of S- and SMt-cycle thickness ell. AIW 135 5,085 26, MS, base not exposed .....:-........_..........._ 504+ 5,135 Ogotoruk Formation (largely mudstones of Mt and M types). Probably not more than 100 ft of strata represented by covered interval at con- tact between the Ogotoruk and Telavirak Formations in Niyiklik Creek. UNCONSOLIDATED DEPOSITS Unconsolidated deposits cover at least half of the area of plate 1. They generally range in thickness from a few feet to a few tens of feet and in only a few places exceed a hundred feet. The various types of deposits are: colluvium ; fluvial gravel, sand, and silt (both terrace and modern flood-plain deposits) ; water-laid gravel and sand of uncertain origin (flu- vial or marine at high altitudes; marine deposits of the modern shoreline and at low altitude along older shorelines nearby ; lake, lagoon, and swamp deposits (chiefly peat and muck); wind-deposited sand and silt; and gravel and sand of the modern beach. All but the present beach and flood plains are commonly covered with tundra vegetation. Ice is an abundant constituent in most of the unconsolidated deposits; it is present as both vertical wedges and horizontal layers. The interstitial ice of the fine-grained sedi- ments is much less spectacular but quantitatively more important. TERTIARY OR QUATERNARY DEPOSITS ILYIRAK GRAVEL The oldest of the unconsolidated deposits is prob- ably the gravel that mantles the upper flanks on the south side of the Kukpuk River valley from its junc- tion with the Ipewik River west to the drainage of Ilyirak Creek, from which the gravel deposit is herein named the Ilyirak Gravel. The gravel covers a single relatively continuous area between altitudes of about 150 feet and about 800 feet. At the lower altitudes it is overlapped by younger stream-terrace deposits of the Kukpuk River. The upper limit seems to be erosionally controlled. Parts of the continuous blanket deposit have been found at altitudes of as much as 415 feet, pebbles are mixed with the col- luvium at higher altitudes on some adjacent slopes, and, in addition, frost-broken fragments of exotic lithology (chiefly red and green chert that was prob- ably originally derived from the Siksikpuk and Shublik Formations) were found on the crest of an adjacent ridge of Lisburne bedrock at an altitude of more than 500 feet. The deposit ranges in thick- ness from 0 to more than 20 feet observed in one stream cut where the base of the deposit was not exposed. The gravels consist chiefly of well-rounded pebbles, relatively few cobbles, and generally less than 25 percent sand, silt, and clay (fig. 254). The deposits are porous and relatively well drained. The most abundant lithologic types are gray and brown chert, cherty limestone, and dolomite (probably derived from the Lisburne Group), with somewhat subordi- nate graywacke sandstone and mudstone (probably derived from the Jurassic? and Cretaceous rocks to the east), and, most commonly in the coarse sand and granule fraction, green and red chert (probably de- rived from the Siksikpuk and Shublik Formations). All these may have been locally derived; however, several pebbles and small cobbles of orthoquartzite were found for which no local source is known. Lo- cally, irregular patches of the gravel are cemented with limonite(?), but most of the deposit is uncon- solidated and friable. The age of the deposit has not been closely ascer- tained, but the high altitudes at which it is found suggest that it is the oldest unconsolidated deposit on the post-Cretaceous erosion surface. Stream-terrace deposits of the Kukpuk River that are at least as old as Sangamon occur at much lower altitudes in the same area. From this it is inferred that the Ilyirak Gravel is Yarmouth or older and may be as old as late Tertiary; hence, it is herein assigned a Tertiary or Quaternary age. The environment in which the gravel was de- posited is uncertain. The deposits are much more cleanly washed and better rounded than those of the younger terrace and flood plains that are clearly river deposited, yet the bulk of the Ilyirak Gravel lies wholly within a broad lowland that has appar- ently been carved from bedrock by the Kukpuk River and its tributary streams. The higher parts and remnant traces of the deposit are at altitudes that correspond roughly with the highest clearly recog- nizable strath terrace level of the Kukpuk and Ipewik River valleys, and the Ilyirak Gravel could be an old stream-deposited terrace. On the other hand, these altitudes are also approximately accordant with the altitude of the break in slope at the top of the wave- cut bedrock plain north of the mouth of the Kukpuk River (see Kachadoorian, 1966, p. 51-52 and pl. 1). 56 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA w Ces tec -s 6OACr-110(top +- 5.4) 60 |- 50 |- 40 |- 6OACr-110(-5.4- -8.8) 30 |-- CUMULATIVE WEIGHT PERCENT 20. |- 10 |- llllllld 0 256.0 64.0 16.0 40 20 10. 08. 025 0.1250062 0.031 0.016 GRAIN SIZE, IN MILLIMETERS A. llyirak Gravel f 6OACr-152a ./<59AC r-142 t] 256.0 64.0 16.0 4.0 2.0 1.0: <05" 0.25 0.125 0.031 0.016 0.062 GRAIN SIZE, IN MILLIMETERS B. Saligvik Gravel Pr o o c - w 2 'o $52 \ \\ | 3 I Ed -] / /59ACr—144 / z Ln - ie y- 60ACr-164-57» 8 s I ~ | CUMULATIVE WEIGHT PERCENT Pa o 20 |- l IJIJ\|JT (e _ L.- "l _ | __ 256.0 64.0 16.0 4.0. 20° «LQ (0.5 0.25 0485 00620.031 0.016 256.0 64.0 16.0 40. - 20 10. 08 0.25 6.1256 0.031 0.016 GRAIN SIZE, IN MILLIMETERS C. Stream-Terrace Deposits 0.062 GRAIN SIZE, IN MILLIMETERS D. Chariot Gravel 100 r | | 90 |- 80 |- 70 |- 80 |- 50 |- 40 |- 80 +- CUMULATIVE WEIGHT PERCENT 20 |- 10 / as* se-" ~ 0L | ll y _>" 256.0 64.0 16.0 4.0 2.0 "el [ Cat t ] lt lal f - - 10 _ 05 (0.25 0.125 0.031 0.016 0.062 GRAIN SIZE, IN MILLIMETERS E. Colluvium FIGURE 25.-Size distribution curves of samples of unconsolidated deposits. No exposures of the Ilyirak Gravel were found in which the original sedimentary structures could be SALIGVIK GRAVEL Another relatively continuous deposit of uncon- observed. The evidence so far seems compatible with | solidated gravel and sand occurs at relatively high either stream-terrace or marine (or estuarine) beach | altitude (as much as 350 ft) along the east flank of depositional environments. Saligvik Ridge, from which it is here named the UNCONSOLIDATED DEPOSITS Saligvik Gravel. The deposit trends north-northeast. The southern half forms a wedge-shaped apron along the flank of Saligvik Ridge and includes good cutbhank exposures at the head of Kiligvak Creek, the type locality; the northern half forms a long, low ridge bounded on the east by the center of Saligvik Valley and on the west by Saligvik Creek, which appears to have been incised at or near the contact between the limestone bedrock ridge to the west and the unconsolidated gravel. The deposit extends both to the north and to the south of the low divide that separates Ogotoruk and Saligvik Valleys. The high- est recognized parts of the deposit are at an alti- tude of approximately 350 feet. At the northern end, in the northwestern end of Saligvik Valley, the de- posit overlies bedrock at an altitude of slightly less than 150 feet. To the south, on the west side of Ogotoruk Valley, similar gravels also overlie bed- rock at altitudes as low as 150 feet. The deposit consists almost entirely of interstrati- fied well-rounded fine pebble to granule gravel and sand (fig. 25B). The internal stratification is fairly regular and even. The pebbles consist entirely of rock fragments which could have been locally de- rived. Graywacke is the most abundant rock type, but chert and cherty limestone are also well repre- sented. The gravel is commonly overlain by a few inches to about a foot of silt containing abundant organic debris and a few inches to a foot of tundra vegetation. Locally, thick peat deposits (1-6 ft thick) have formed in depressions that appear to be drained thaw lakes and old stream channels at the surface of the Saligvik Gravel. Incised stream-cut exposures of the gravel show that it is more than 35 feet thick in some places. Where exposed and thawed, the deposits are well drained and friable, and there is apparently little or no clay in the interstitial matrix. The surface expression of the gravel deposit is generally distinctive, both on the ground and in the vertical aerial photographs. The upper surface is characterized by large ice-wedge polygons separated by channels that are as much as 114 to 2 feet deep. Where streams have been incised through the pro- tecting mat of tundra vegetation, the gravels locally display a badlands topography, with steep-walled flat-bottomed gully, in a generally dendritic pattern, encroaching headward into the tundra-covered sur- face of generally more gentle relief. The age and origin of the deposit are uncertain. The age is surely older than the river-terrace deposits of probable Sangamon or older age that truncate it on the north. The low altitude of its base on the north indicates that it is younger than the erosional gap of the Kukpuk River through the southern Lisburne Hills and the erosional tributary Saligvik Valley; however, its position on the flank of the valley indicates that the cut bedrock surfaces of both Saligvik and Ogotoruk Valleys may have been deep- ened on the east side of the gravel deposit after its deposition. The position athwart the divide between Ogotoruk and Saligvik Valleys seems enigmatic, particularly with regard to the lower extremities of the gravel in Ogotoruk Valley. These lower sections, however, are thin and poorly exposed. Moreover, they are in some places intimately associated with stream-terrace deposits of tributaries to Ogotoruk Creek. It is possible, perhaps probable, that these parts of the deposit are more recent stream-terrace deposits that are made up almost exclusively of gravel and sand reworked from the Saligvik Gravel at higher altitude on the flank of the valley. If so, the Saligvik Gravel probably represents deposition in an ancestral Saligvik Valley that once extended to the south considerably beyond the present divide but which has migrated northward as a result of capture by the headward erosion of south-flowing Ogotoruk Creek. In any case, the Yarmouth Interglaciation provides the youngest depositional base level with which the deposit might be correlated, and it seems quite possible that it is older still, perhaps as old as late Tertiary. The deposit, therefore, is herein as- signed a Tertiary or Quaternary age. The Saligvik Gravel is probably easiest to visualize as the deposit of a northward-flowing tributary of the Kukpuk River. However, the possibility that it is a marine or lacustrine beach deposit cannot be disregarded : the high degrees of rounding and spher- icity of the pebbles, the rather well-sorted nature of interstratified sand and gravel, and the lack of abundant interstitial clay are all features that resem- ble those of the material of the modern beach and are distinctively different from those of the more recent stream-terrace and flood-plain deposits that are clearly related to the Kukpuk River. The chief difficulty of the beach-origin hypothesis is that a coastline at an altitude of 3850 feet or more would probably have made an island or a long peninsula of the ridge along whose flank the deposit was laid, and it is hard to reconstruct the circumstances which would permit such an island or peninsula, made up chiefly of limestone bedrock, to accumulate a beach in which graywacke pebbles predominate. Adjacent bedrock units that would provide a local source of gray detritus would have been exposed only on nearby islands. Although a reconnaissance search 58 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA i was made, no deposits remotely comparable to the Saligvik Gravel were found on hillsides where islands underlain by graywacke-bearing bedrock might be expected to have accumulated beach deposits during a high stand of sea level. Although the Ilyirak and Saligvik Gravels are similar in some of their surface expressions and in presumed minimum age, they are sufficiently differ- ent in grain size, pebble lithology, and maximum al- titude to indicate that they are not directly correla- tive with one another. The lower maximum altitude of the Saligvik Gravel may justify the inference that it is younger than the Ilyirak Gravel. QUATERNARY DEPOSITS STREAM-TERRACE DEPOSITS Several levels (and ages) of stream-terrace de- posits, clearly related to present streams or their immediate ancestors, are present along the Kukpuk and Ipewik Rivers and their tributaries, as well as along the shorter streams which drain southward to the sea, such as Ogotoruk and Kigimilok Creeks. The deposits consist chiefly of subrounded to subangular cobble and pebble gravels with abundant interstrati- fied (as well as interstitial) sand and silt (fig. 25C). The cobbles and pebbles consist, almost without ex- ception, of rock types that could have been derived from the bedrock formations of the map area, up- stream from the present sites of deposition. The thickest and most continuous of the terrace deposits is one about 30 feet thick that is intermit- tently exposed along the Kukpuk River. In many places the upper surface of a deposit, though covered with tundra vegetation and modified slightly by ice- generated microrelief features, is little reworked and displays the relatively flat characteristic terrace form. On this flat surface, shallow lakes and swamps and their grass-covered drained basins are common. Exposures of the bedrock surface on which this ter- race material is deposited are commonly within a foot of the low-water level of the present river. The thickness and relative continuousness of terrace de- posits at this level indicate that this entire stretch of the river was aggraded to a base level, probably a stand of sea level, at an altitude about 30 feet above the present sea level. It seems reasonable to infer, therefore, that this river terrace correlates with the stand of sea level, about 26 feet above the present level, during which beach deposits of Sangamon age were laid down along the coast (Moore and Scholl, 1961, p. 61). Although many, generally discontinuous, terrace surfaces are cut in the bedrock at higher altitudes along the rivers and streams, no deposits (with the possible exceptions of the Ilyirak and Saligvik Gravels, whose association with the prominent cut- terrace features is indirect at most) were found on those that were examined. At lower altitudes, ter- race deposits are most common from 3-15 feet above the present stream grades. They are generally dis- continuous, but locally, along some individual streams, are persistent. Most are probably younger than the Sangamon river terrace ; but some, particu- larly those along Ogotoruk Creek, may be early Sangamon or older, because the stream-cut bedrock | surface on which the Chariot Beach gravel of Sangamon age was deposited lies less than 5 feet above the present grade of Ogotoruk Creek where it cuts through the Chariot Gravel. CHARIOT GRAVEL Beach and nearshore marine deposits that repre- sent a eustatically high sea level, probably during the Sangamon Interglaciation, occur along low-lying areas of the coast, generally within a few hundred feet of the present shoreline. They are represented near the mouth of Ogotoruk Valley by an old bay- mouth bar, whose top ranges in altitude from $4 to 42 feet, and upon which the Chariot base camp was built; therefore, the Chariot Gravel is here named for these deposits. The character and distribution of these gravels, together with the associated under- lying marine platform and some of the overlying nonmarine deposits, have been described in detail, and their origin and age discussed by Sainsbury and others (1965); related deposits in the Point Hope and Cape Krusenstern areas have been described by Moore and Scholl (1961, p. 61-63). Except for the relatively high-standing old bay-mouth bar at the mouth of Ogotoruk Creek and a small outcrop near the mouth of Kuropak Creek, the deposits are ex- posed only in vertical stream-cut or wave-cut see- tions intermittently along the coast. They are most generally thin layers of marine sand and gravel, sandwiched between the wave-planed bedrock sur- face below, and a cover of nonmarine deposits, chiefly colluvium, of variable thickness. The deposits consist generally of friable well- rounded coarse- to fine-pebble gravel (fig. 25D) and interstratified sand. The bay-mouth bar deposit at the Chariot campsite seems to contain a greater- than-normal proportion of admixed silt and clay (?) thought to be wind-deposited material that has been mixed with the upper part of the gravel by percolat- ing rainwater and seasonal frost action. The deposit there is about 25 feet thick; where observed else- UNCONSOLIDATED DEPOSITS 59 where, the deposits range in thickness from a few inches to about 10 feet, but they could, of course, be thicker in some of the low-lying coastal areas where they are now concealed by younger nonmarine de- posits. CcOoLLUVIUM The most widespread of the unconsolidated de- posits is colluvium; it has formed at the base of nearly every bedrock rubble slope and extends as aprons of varying width and thickness onto the gentler slopes below. It is almost invariably covered with tundra vegetation and is exposed chiefly in stream cutbanks, wave-cut bluffs along the coast, and relatively sparse frost boils. Commonly, but not in- variably, there is a pronounced break in slope be- tween steeper relatively barren bedrock rubble hill- sides and the gentle well-vegetated colluvium-covered valley slopes. These slope breaks give the impression of a multitude of small discontinuous terraces. Soli- fluction lobes are abundant in the apronlike deposits, but where aprons have coalesced to blanket the bot- toms of some small valleys, longitudinal ridges parallel to the valley axes are common. Ice-wedge polygons and tussocks are extremely rare and seem to be confined to areas where the surface is nearly fiat and downslope movement has not occurred for some appreciable number of years. The thickest and best exposed of the colluvium deposits forms a promi- nent terrace along the coast of the Telavirak Hills. The terrace and its associated colluvium deposits have been described in detail by Sainsbury and others (1965). The colluvium is composed of angular to subangu- lar fragments of bedrock, generally of coarse pebble or smaller size, with variable amounts of frost-ad- mixed sand, silt, and clay of probable aeolian origin (fig. 256). Locally, the colluvium includes material derived from preexisting unconsolidated deposits which have been reworked, both with and without the addition of locally derived fragments of bedrock. The deposits are commonly less than 10 feet thick, form- ing thin continuous blankets over gentle bedrock slopes; but, locally, where the colluvium has filled old stream gullies, it may be as much as 20 feet thick. The coastal-terrace deposit at the foot of the Tela- virak Hills, where material was apparently supplied very rapidly as the sea cliffs of Sangamon age were eroded, is as much as 100 feet thick in some places. Colluvium forms at the base of bedrock rubble slopes, where it is mixed by frost action with finer material, both locally derived and deposited by aeo- lian processes. The growth of tundra vegetation insulates the underlying material so that the top of the permafrost zone rises above the base of the un- consolidated material. During the summer season, the upper 114-2 feet of the deposit thaws and, be- cause of the impermeability of the underlying frozen ground, becomes saturated with water. The water- saturated thawed zone is then free to move down- slope. Movement is chiefly by solifluction, but in a few places, where the matted cover of tundra is broken, it may occur by mudfiow and shallow slump. No direct evidence for the maximum age of the col- luvium deposits has been found. Deposits are being formed and moved at the present, and because the processes by which they are formed are so intimately associated with the arctic climate, their age is pre- sumed to range from earliest Pleistocene to the present. LAKE, LAGOON, AND SWAMP DEPOSITS Peat and muck, the principal constituents of swamp, lagoon, and lake deposits, are common in many parts of the low-lying coastal plain, in closed or nearly closed colluvium-filled depressions at higher altitudes (such as the low-gradient effluent drainage of Pumaknak Pond) and in the drained thaw-lake basins that are extremely common on the terrace deposits of the Kukpuk River; they are sporadically distributed across the surface of the Saligvik Gravel. Areas that are wet and swampy at present are commonly very grassy in appearance in contrast to most of the adjacent deposits of other sorts. The deposits in better drained terrain are most easily recognized where they occur in the drained basins of thaw lakes, which generally have distinctive marginal scarps. In areas where the de- posits appear to have been relatively well drained for some appreciable number of years, ice-wedge polygons are common. Peat and muck are also found interbedded with many of the older terrace deposits, as well as with colluvium and wind-deposited silt and sand. Apparently many small stream channels have been filled with colluvium or flood-plain deposits above which the surface runoff was locally ponded, forming a swampy environment in which peat ac- cumulated, in a few places to a thickness of several feet. These organic-rich layers are everywhere un- derlain by older unconsolidated deposits, and the present lakes, swamps, and lagoons are all floored and surrounded by older unconsolidated deposits. None within the mapped area lies directly on bed- rock. Consequently, the deposits are invariably thinner than the older unconsolidated deposits that surround them. 60 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA The composition of the deposits ranges from nearly pure peat to mud containing a fairly high proportion of silt, clay, and sand commonly mixed with peaty organic material. The silt, clay, and sand probably include both aeolian detritus and that derived from older unconsolidated deposits by wave erosion of the banks of the small lakes. The deposits of Mapsorak Lagoon have been studied in detail by Moore and Scholl (1961, p. 48-50), and many char- acteristics of that lagoon are probably shared by the others. Because the processes of peat formation seem to be associated with tundra vegetation and (but more indirectly) with the arctic climate, the range in age of the peat and muck deposits may well be nearly the same as that of the colluvium-from earliest Pleistocene to the present. Muck is certainly forming today at the bottom of many thaw lakes, and peat with a radiocarbon age of 26,000 + 400 years (middle Wisconsin) was sampled in the Point Hope area (Moore and Scholl, 1961, p. 63). WIND-DEPOSITED SILT AND SAND Silt and sand of probable aeolian origin covers much of the low-lying coastal-plain areas, as well as the lower flats and gentle slopes that are abundant in Ogotoruk and Saligvik Valleys and the valley of Kisimilok Creek. In the flat areas the deposits are commonly covered with a fairly continuous tundra mat, and ice-wedge polygons are the dominant micro- relief forms. On the slopes, grassy tussocks are more common, and solifluction stripes, perpendicular to the hillside contours, are the most prominent form of microrelief. The difference in surface expression reflects the difference in stability of the active layer (the zone in which summer thaw occurs) between the relatively stable flats and the slopes down which gravity tends to induce movement during the sum- mer period of thaw and water saturation. The deposits are compact and saturated with water or ice; cutbanks are quickly degraded by slump and soil flow. Thickness is commonly on the order of 1 or 2 feet; locally it may be as much as 4 feet, and greater thicknesses may have accumulated in a few places where depressions or gullies as much as 20 feet deep could be concealed beneath the unconsolidated deposits. Silt and sand most commonly is underlain by colluvium or other older unconsolidated surficial material, but in some places the subjacent material is residual frost-broken bedrock. Windblown deposits of several ages are probably present, as silt and sand are interbedded with some swamp deposits and with colluvium as well as lying upon all the other unconsolidated deposits except for the very recent flood-plain and beach sediments. Some dust is known to blow in Ogotoruk and Saligvik Valleys at present but not in amounts needed to form appreciable deposits. The most likely sources for the fine material of the aeolian deposits are the barren, unvegetated moraines and outwash plains exposed during glacial retreat. Many local low areas in which aeolian sand and silt predominate at the surface have a well-developed tundra mat and deep and well- defined ice-wedge polygons that must have been stabilized for an appreciable number of years and may be as old as late Wisconsin. The age of these deposits is, therefore, considered Pleistocene and Recent. FLOOD-PLAIN DEPOSITS Modern flood-plain deposits occur along the Kuk- puk and Ipewik Rivers, the lower reaches of a few of their tributaries, and along a few of the shorter streams that drain south to the ocean, such as Ogo- toruk and Kisimilok Creeks. The surfaces of the de- posits are generally barren of vegetation, but some parts that are awash only during relatively infre- quent (two or less a year) flood stages, sustain some grasses and tundra. The deposits consist of fluvial gravel, sand, and silt. The gravels are chiefly flat elongated tabular subrounded to subangular pebbles (showing better rounding in lower reaches of small streams as well as along the rivers); large cobbles and boulders are rare. The size and shape are probably functions of the bedding characteristics and jointing of the well- indurated original bedrock. The composition of the gravels reflects that of local and upstream sources of bedrock and, to a much lesser extent, older unconsoli- dated deposits. The proportion of matrix sand and silt in the gravel is variable; but it is commonly much greater than might be presumed from the sur- face appearance of the exposed gravel bars, and may locally make up more than 50 percent of a deposit. Apparently, gentle currents of the waning flood stage winnow the finer matrix from between the topmost pebbles of the flood-deposited mixture of gravel, sand, and silt. In the short streams that drain south to the Chukchi Sea, the flood-plain deposits probably do not exceed 10 feet in thickness. The deposits of the large rivers, although thicker than those of the small streams, probably do not exceed a few tens of feet. BEACH DEPOSITS OF THE PRESENT SHORELINE Recent gravel beach deposits extend along the en- tire coastline, continuously except for a few cliffed GEOLOGIC STRUCTURE 61 headlands along the sea cliffs between Crowbill Point and Cape Thompson. Beneath the sea cliffs the beach is too narrow to show on the map (pl. 1), but it is nevertheless present as a nearly continuous strand, broken by major headlands at Cape Thompson, Agate Rock, Artigotrat, and Crowbill Point (pl. 2). A narrow, but continuous beach lies along the foot of the coastal bluff at the south side of the Telavirak Hills and extends to the wider beaches of the ad- jacent lowlands of Ogotoruk Valley and the valley of Kisimilok Creek. Across the low-lying coastal plains to the northwest of Agarak Creek and to the south- east of Kisimilok Creek, beach deposits are continu- ous along the smoothly curved shoreline, in many places as barrier bars, separating the Chukchi Sea from fresh- and brackish-water lagoons. The deposits are generally barren of vegetation, but some sparse grasses may be found on the higher parts of the bar- rier bars, which are reached by only a few waves from the highest storms each year. The beaches are generally confined to altitudes of less than 12 feet, though a few of the barrier bars may be as much as 15 feet above sea level. They are generally less than 40 feet wide where they are pres- ent beneath the precipitous limestone cliffs, but they are considerably wider in the low-lying coastal areas where some of the barrier beaches are as much as $00 feet wide. The beach deposits of this and adjacent areas have been studied in detail by other investiga- tors in connection with the Chariot program (Scholl and Sainsbury, 1959; Moore, 1960; Moore and Cole, 1960; and Moore and Scholl, 1961). According to Scholl and Sainsbury (1959, p. 57-59), the deposits probably are generally less than 25 feet thick and are composed of stratified well-sorted well-rounded sandy pebble gravels consisting chiefly of fragments of fine-grained graywacke, siltstone, chert, and lime- stone. GEOLOGIC STRUCTURE A regional dip to the south or southeast is indi- cated by the exposure of progressively younger units from west to east on the map (pl. 1), even though westerly dips are common at surface exposures of the strata. As shown by the structure sections (pl. 1), Paleozoic and Mesozoic strata 25,000-30,000 feet thick are present in the eastern part of the area, but they have been eroded off the western part. In addi- tion to the stratigraphic evidence, gravity data show a generally gradual decrease in simple Bouger anomalies along a northwest to southeast profile across the area (Barnes and Allen, 1961, p. 80-86), and more recent data (Barnes, oral commun., 1962) suggest that the regional gradient is more nearly east or east-northeast than southeast. All the exposed rocks have approximately the same density; there- fore, the relatively smooth gravity gradient is inter- preted to reflect a gradual eastward thickening of the sedimentary rocks overlying a dense layer that either slopes relatively smoothly or is so deeply buried that its irregularities are not expressed. In the western half of the area the structure is dominated by a north-trending zone of imbricate thrust faults along which rocks of the Lisburne Group have been thrust eastward over Lisburne and younger strata. In the eastern half of the area the dominant structural features are complex high- amplitude folds and high-angle faults. THRUST FAULTS OF THE WESTERN PROVINCE The north-trending zone of thrust faults extends from the Chukchi Sea northward to Cape Lisburne (A. J. Collier, 1906 ; J. T. Dutro, Jr., E. G. Sable, and A. L. Bowsher, written commun., 1958). Four thrust sheets are present in the western part of the map area. The rocks of two of these, the Saligvik and Ibrulikorak thrust sheets, predominate at the sur- face. A third, the Angmakrok sheet, is only inter- mittently exposed along the eastern front of Saligvik Ridge beneath the younger Saligvik thrust sheet. The fourth, the Agate Rock thrust sheet, appears to be merely a large fault sliver below the Ibrulikorak fault. The Saligvik thrust sheet has an exposed width of more than 4 miles and a maximum thickness of 7,000-8,000 feet. The Ibrulikorak thrust sheet is slightly more than 8 miles wide at its widest point on the map, and its thickness ranges from about 2,000 feet at the coastline to an estimated 3,000 feet along the Kukpuk and Ipewik Rivers. Each of the thrust sheets has moved relatively eastward or southeastward, forming an imbricate pattern as shown in the structure sections (pl. 1). The earliest thrust sheet is bounded at the base by the Angmakrok thrust fault; it was subsequently broken by high-angle faults and overridden by the Saligvik thrust sheet along the Saligvik thrust fault (pl. 2B); the Saligvik thrust sheet was, in turn, folded, faulted, and overridden from the west by a still later thrust sheet bounded at its base by the Agate Rock and Ibrulikorak faults (pl. 24). The Akoviknak fault is probably the western tail of the Ibrulikorak fault (see structure sections, pl. 1) and could represent the upslope exposure of a zone of detachment that, to the east, broke upsection along progressively more westward fronts in successively younger pulses (Campbell, 1961c). In that event, 62 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA movement on the Akoviknak fault would be the sum of the movements of all the west-dipping thrust faults, for each of which the Akoviknak would have been the upslope tail. The eastern overthrusting on the Angmakrok thrust is a minimum of 1 mile (see structure section C-C", pl. 1), and an estimate of 2 or 3 miles would not be unrealistic. The movement on the Saligvik thrust is, at a minimum, 1 mile, but probably it is considerably more. The eastward overthrusting on the Ibrulikorak and Agate Rock faults is at least 2 miles and is possibly more than 5 miles. Thus, a total displacement of 7-10 miles is indicated. The displacement could be somewhat greater, but it seems unlikely that the total over- thrust displacement is on the order of several tens of miles because it has not brought into juxtaposition very different lithologic facies of the same forma- tions. The Mississippian strata of the Saligvik and Ibrulikorak thrust sheets are generally folded into rather broad syncelines and anticlines. The limbs of the structures, though cut by some high-angle faults, most of which have relatively small displacements, have relatively uniform gentle dips. Some axial zones, however, are intensely faulted and folded into tight structures of high amplitude. This is particu- larly striking in two synelines in the Saligvik thrust sheet, in which Siksikpuk, Shublik, and, locally, Ogotoruk rocks are infolded. In places these struc- tures have been further modified by drag effects as they were overridden by the Ibrulikorak thrust sheet. Drag folds of varying amplitudes are common in the basal strata of the thrust sheets. Chevron forms are strikingly abundant in the zone immediately above the Saligvik thrust fault in the sea-cliff exposures just west of the mouth of Amaktusak Creek (pl. 2B). FOLDING AND FAULTING OF THE EASTERN PROVINCE In contrast to the thrust-faulted province in the western part of the map area, the eastern part is dominated by north- to northeast-trending folds and high-angle faults. The folds are generally tight, of high amplitude, and have steep-dipping limbs and tightly crumpled axial areas. Overturned folds are common, generally with both limbs dipping to the west. Minor folds of several types ard widely vary- ing amplitudes are present on nearly «il the limbs of the folds (fig. 26). The high-angle faults appear to be intimately related to the folds. Axial-plane faults and bedding-plane faults are common, and slicken- siding is abundant on many bedding planes within the rock units. Many of the high-angle faults appear FiGURE 26.-Bedding characteristics and structural fea- tures in the Telavirak Formation. Interlaminated mudstone and sandy siltstone showing thickening, attenuation, and fracturing associated with adjust- ments to the tightly folded configuration in a minor anticline (a drag fold on the flank of a larger struc- ture). The glassy material that surrounds and veins the specimen is plastic in which it was imbedded to prevent its disintegration during sawing and polish- ing. to be zones in the crest and troughs of folds where the rocks failed by fracture, locally, rather than by flexure. Poor exposures, lack of key beds and marker horizons, and the abundance of minor folds having amplitudes larger than the size of the outcrops com- bine to obscure much of the general structural pic- ture in the areas underlain by the Ogotoruk, Tela- virak, Kisimilok, and Fortress Mountain(?) For- GEOLOGIC STRUCTURE 63 mations. The continuous projections of the longer faults shown on the map (pl. 1) are based largely on discontinuities of structure across the inferred fault traces rather than continuous exposure of the faults themselves. The major axial traces are similarly in- ferential, and the lines on the map serve more to illustrate the general nature of the folding and fault- ing than to show the precise locations of continuous readily recognizable features. Although the ampli- tudes of the major folds must be of the order of at least several hundred feet, it is important to note that rocks of the Shublik Formation and older units are not returned to the surface to the east of the east- ern flank of Saligvik Ridge by the folding or faulting of the Ogotoruk Formation. Nor are recognizably older rocks returned to the surface by folding or faulting in any of the successively younger map units. Joints, perpendicular or nearly perpendicular to the bedding, are common in the sandstone beds; close-spaced, locally slaty, fracture cleavage is com- mon in the mudstone beds. In many outcrops the fracture cleavage appears to be an axial-plane cleav- age, dipping steeply to the west. In many outcrops it is parallel or nearly parallel to the bedding, giving many of the mudstones a shaly aspect. In axial zones and some other structural settings, however, where the fracture cleavage intersects bedding-plane partings at oblique angles, the fractured rocks re- semble pencil slates (fig. 27). Where the mudstone is rhythmically interbedded with more competent sandstone, the close-spaced fracture cleavage, which may be at angles of as much as 30° to the bedding FIGURE 27.-Mudstone of the Ogotoruk Formation with one thin interbed of sandstone that expresses bedding; shows close-spaced fracture cleavage at acute angle to bedding. The straight edge of the scale case is 2 inches long. FIGURE 28.-Fracture cleavage in mudstone interbedded with sandstone in which the cleavage is not developed. Telavirak Formation. planes, appears to be related to the differential slip of the overlying and underlying sandstone beds (fig. 28). The hypothetical thrust fault that forms the con- tact between the Kisimilok and Fortress Moun- tain(?) Formations may be related to the thrust faults of the western half of the area ; however, there is no local evidence to suggest a direction or amount of displacement. Owing to the poor exposure, the possibility that this contact is an unconformity can- not be eliminated, but the generally smooth curva- ture of the contact and the indications that both units are discordant with the contact suggest that it may be an eastward-dipping low-angle (thrust) fault. AGE AND ORIGIN OF DEFORMATION The thrust faulting of the western province and the folding of the eastern province appear to be contemporaneous and are probably related to the same deforming stresses. This is indicated by the parallelism of the general trends of the folds with the fronts of the thrust sheets, by the absence in the western province limestone and dolomite strata of high-amplitude multiple folds of the type found in the less competent flysch facies beds of the eastern province, and by the absence of such high-amplitude folding of the thrust faults themselves. It seems likely that each of the thrust faults was a planar or smoothly curved surface at the time the overlying strata were displaced. The places where the thrust faults cross the stratigraphic units, therefore, indi- 64 GEOMORPHOLOGY cate that some gentle folding occurred before the overthrusting. But the large areas in which the faults follow stratigraphic horizons, and which are even now only broadly folded, indicate that the Paleozoic rocks were not thrown into high-amplitude folds along with the Jurassic(?) and Cretaceous strata. The youngest bedrock unit exposed in the known overthrust sheets is the lower part of the Ogotoruk Formation. As the Ogotoruk and Telavirak Forma- - tions form a continuous depositional sequence that probably also includes the Kisimilok Formation, the time of deformation indicated is post-Kisimilok. If the contact between the Kisimilok and Fortress Mountain(?) Formations is an unconformity, then two periods of fairly high intensity deformation would be indicated. However, the rocks of both units are contorted to about the same degree, and it seems more likely that the contact is a fault and that all of the bedrock units now exposed in the area were de- posited before a single major period of deformation in post-Fortress Mountain (?) time. Other evidence bearing on the age of deformation may be adduced from the Utukok-Corwin region to the north, where rocks as high in the section as the Nanushuk Group are evidently involved in thrust faulting of the same general structural associations as those in the western part of the Cape Lisburne Peninsula (Chapman and Sable, 1960, p. 144). Chap- man and Sable (1960, p. 144) believe these structural features to be the result of eastward- and northeast- ward-directed tangential forces originating west of the peninsula in the Tigara uplift, which Payne (1955) describes as of Tertiary(?) age, probably post-Paleocene. The deformation of rocks of the Chariot area and vicinity is herein interpreted to be a response to an easterly regional dip formed as a result of uplift in the vicinity of Point Hope and west of it (the Tigara uplift of Payne, 1955). The cross sections (pl. 1) show an average gradient of 7°%-10° eastward on the base of the Lisburne Group. The association of east- erly overthrusting with an easterly regional dip sug- gests that the thrusting took place by gravity glid- ing (Campbell, 1961c). The folding of the eastern province, with its predominance of west-dipping axial planes, took place at the same time under the same regional stresses. The difference in kinds of structure between the eastern and western provinces merely reflects the difference in response of rocks of different competence to components of gravitational force in the direction of the regional dip. The rela- tively competent rocks of the Lisburne Group tended to move as coherent sheets, chiefly along the numer- ous weakly bonded bedding planes at and near its base. The underlying mudstone-sandstone unit, be- ing water saturated, may have served as a lubricated zone along which the overlying coherent sheets could slide, possibly aided by abnormal fluid pressures (Hubbert and Rubey, 1959). The relatively incom- petent Jurassic(?) and Cretaceous rocks also tended to move downslope, but they were less confined by overburden than the more competent rocks below (and perhaps they were even buttressed laterally by the end of the eastern dip at a basin or synclinal axis in the vicinity of Cape Seppings). The response in this eastern province was chiefly by tight folding and high-angle faulting. GEOMORPHOLOGY The varied geomorphic features of the area repre- sent a long and complex history of erosion and depo- sition. Most of it was subaerial and fluvial, but ma- rine erosion and deposition are represented by many features at low altitudes along the coast and may have affected higher areas where the evidence is poorly preserved. Two major rivers, the Kukpuk and the Ipewik, are superposed across the general structural grain of the area. Their valleys are deeply incised into an old upland surface of very low relief. The upland surface appears to be stepped along a northwest-trending line that generally follows the northern side of the valley of the Kukpuk River. North of the Kukpuk River several north- to north- northwest-trending ridges rise to altitudes in excess of 1,750 feet. South of the Kukpuk River many ridge tops and hilltops show remnants of a low rolling surface between altitudes of 500 and 1,000 feet. The general topographic features of areas below 500 feet appear to reflect almost exclusively the dis- section of the old upland surface by minor streams that follow the general structural grain and are tributary to the Kukpuk River or drain south to the sea. Stream-cut terraces may be observed in the valleys of the Ipewik and Kukpuk Rivers at altitudes as high as 600 feet. Fluvial terrace deposits are found at lower altitudes along the rivers, and locally, as much as 30 feet of such deposits overlie cut bed- rock surfaces at altitudes as low as a foot above the present low-water level of the rivers. The prominent strike valleys and ridges appear to have developed as tributaries to the Kukpuk River during its incision. Some of the streams of the strike valleys appear to have been captured; others seem to be in imminent danger of capture by the shorter steeper south- flowing streams graded to the Chukchi Sea coast. GEOLOGIC HISTORY 65 No glacial moraine or outwash deposits have been found, nor are there any topographic features of clearly glacial origin. The line of wave-faceted north- and northeast- trending ridges that marks the present coastline seems to have been well established at nearly its present position by the end of Sangamon time. Wave erosion on the present coast is actively attacking bedrock only along the cliffs and headlands west of the Chariot site; even above those cliffs there are steep slopes which probably represent the degraded cliffs of the earlier coastline of Sangamon age. A detailed description of the many minor land- forms and microrelief features of the area was not attempted. The microrelief features are of types relatively common in arctic climates, and their gen- eral origin and development have been described by several workers in other areas (Hopkins and Sigafoos, 1951; Washburn, 1950 ; Sigafoos and Hop- kins, 1952; Sharp, 1942). Notably absent are such prominent features as pingos and elongated oriented lakes. GEOLOGIC HISTORY The sequence of sedimentary rocks represents nearly continuous marine conditions from Early Mis- sissippian through Early (?) Cretaceous time. The unnamed unit of Early and Late Mississippian age represents chiefly shallow-water marine deposition, with some intertonguing of possible nearshore non- marine deposits. A gradual deepening of marine con- ditions started before and continued during deposi- tion of most of the Nasorak Formation. The upper 1,600 feet of the Nasorak probably represents miogeosynclinal conditions and grades upward to the shallower marine platform associations represented by deposits of the Kogruk(?) Formation. The ap- parent discontinuousness of the Tupik Formation and the interbedding of facies similar to it within the underlying Kogruk(?) suggest that most probably this facies was deposited in disconnected shallow basins of the general platform association. The ab- sence of a sequence of recognizable Pennsylvanian rocks is not accompanied by any evidence of exten- give subaerial erosion, and there is no reason to infer that the area was emergent at that time. However, the possibility of post-Tupik pre-Siksikpuk erosion cannot be neglected. The thin continuous deposits of the Siksikpuk and Shublik Formations suggest gen- erally long-lived stable marine conditions at some depth below wave base through most of the Permian and Triassic, followed in Jurassic or Cretaceous time by eugeosynclinal conditions that persisted at least into Early Cretaceous time. The apparent discon- formity between the Shublik and Ogotoruk Forma- tions does not seem to represent significant subaerial erosion, for the upper Monotis-bearing limestone zone of the Shublik is present wherever the two for- mations are in unfaulted contact. Even if the Juras- sic Period is not represented by sedimentary depos- its, though it seems more likely that it is, there is no evidence that it was a period of emergence in this area. Except for sporadic marine deposition of the Pleistocene Gubik Formation in the coastal plain of the Utukok-Corwin area (Chapman and Sable, 1960, p. 69, table 2), no significant marine - deposits are known to occur in this region above the top of the Nanushuk Group, which was assigned by Chapman and Sable (1960, p. 69) to an Early and Late Cre- taceous age. The Corwin Formation, the topmost formation of the Nanushuk Group, includes non- marine facies, suggesting that the Utukok-Corwin area was emergent during Late Cretaceous time and intermittently during much of the later part of Early Cretaceous time. All the bedrock units now exposed in the area were probably deposited before the deformation that re- sulted in the thrust faulting and folding. Some minor folding, probably associated with early phases of the Tigara uplift, certainly preceded the main episode of thrust-fault displacement. The main de- formation probably took place in several pulses, as each thrust sheet was folded and broken by high- angle faults before it was overridden by the next higher sheet. Some late, anticlimatic folding is in- dicated by the folding and high-angle faulting of the highest of the imbricate thrust sheets, the Tbruli- korak. The age of the major deformation is uncer- tain, but it is most probably Late Cretaceous or early Tertiary. Payne (1955) suggests that uplift in the vicinity of the Lisburne Hills (the Tigara uplift) occurred during a post-Paleocene orogeny; he also indicates strong deformation of the Brooks Range geanticline at that time. The subsequent history of the area appears to be chiefly one of erosion which reduced the area of the Tigara uplift and adjacent parts of the Arctic Foot- hills physiographic province to a surface of relatively low relief. The ancestral Kukpuk and Ipewik Rivers established their west-trending drainage either on an erosion surface of such low relief that the bedrock structure and lithology had little effect or possibly on flat-lying younger deposits that have since been completely eroded off. Certainly by middle Pleisto- cene time the major rivers were draining westward toward what had been the higher parts of the Tigara 66 AREAL GEOLOGY, VICINITY OF CHARIOT SITE, LISBURNE PENINSULA, ALASKA uplift. The development of a westward-moving drainage indicates that a general westerly surface slope had formed in an area where the Tigara uplift had previously established an eastward-dipping re- gional structure. This suggests tectonic subsidence of the Tigara uplift area in post-Tigara pre-middle Pleistocene time. Some of the folding of the Ibru- likorak thrust sheet may have occurred in association with the westward tilting. The record of Sangamon deposits and pre-Sangamon erosion surfaces on which those deposits lie indicates that most of the modern drainage was well established and many of the smaller streams had cut to very nearly their present grades before the Sangamon Interglaciation, and that the major landforms were well outlined by middle Pleistocene time. REFERENCES CITED Barnes, D,. F., and Allen, R. V., 1961, Preliminary results of gravity measurements between Kotzebue and Point Hope, Alaska, in Kachadoorian, Reuben, and others, Geologic investigations in support of Project Chariot, Phase III, in the vicinity of Cape Thompson, northwestern Alaska- preliminary report: U.S. Geol. Survey TEI-779, p. 80- 86; prepared on behalf of the U.S. Atomic Energy Comm. Campbell, R. 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T., Jr., 1961, New Devonian and Mississippian formations in DeLong Mountains, northern Alaska: Am. Assoc. Petroleum Geologists Bull., v. 45, no. 5, p. 585-598. Sainsbury, C. L., and Campbell, R. H., 1959, Geologic strip map of part of Kukpuk River, northwestern Alaska: U.S. Geol. Survey open-file report, Sept. 17, 1959, 10 p. Sainsbury, C. L., Kachadoorian, Reuben, Campbell, R. H., and Scholl, D. W., 1965, Marine platform of probable Sangamon age, and associated terrace deposits, Cape Thompson area, northwestern Alaska: Arctic, v. 18, no. 4, p. 230-245. Scholl, D. W., and Sainsbury, C. L., 1959, Marine geology and bathymetry of the nearshore shelf of the Chukchi Sea, Ogotoruk Creek area, northwest Alaska: U.S. Geol. Survey TEI-606, 68 p., prepared on behalf of the U.S. Atomic Energy Comm.; also U.S. Geol. Survey open-file report. Schrader, F. C., 1902, Geological section of the Rocky Moun- tains in northern Alaska: Geol. Soc. America Bull, v. 13, p. 288-252. Sharp, R. P., 1942, Soil structures in the St. Elias Range, Yukon Territory: Jour. Geomorphology, v. 5, no. 4, p. 274-301. Sigafoos, R. S., and Hopkins, D. M., 1952, Soil instability on slopes in regions of perennially-frozen ground [Alaska]: Natl. Research Council, Highway Research Board Special Rept. 2, p. 176-192. Smith, P. S., and Mertie, J .B., Jr., 1980, Geology and mineral resources of northwestern Alaska: U.S. Geol. Survey Bull. 815, 351 p. Washburn, A. L., 1950, Patterned ground: Rev. canadienne geographie, v. 4, no. 3-4, p. 5-59. Williams, Howel, Turner, F. J., and Gilbert, C. M., 1954, Petrography-an introduction to the study of rocks in thin section: San Francisco, Calif., W. H. Freeman & Co., 406 p.; repr., 1958. A Page Acknowledgments 1 Agarak Creek PBA Agate Rock ... 19, 22, 23, 61 Agate Rock thrust sheet t 61 Akoviknak fault .._... - 61, 62 Alapah Limestone of Brooks Range.. - 14, 18 Algal IMIDTeSSIONE 9 Alizarine red S solution, stain used to de- termine calcite and dolomite proportions ' ........................- coon 5 U2 . sed i Amphiscapha sp 20 Amplexizaphrentis sp Angayukuk Creek .._. Angmakrok thrust fault .. Angmakrok thrust sheet . Archimedes sp .__..__._... Arctic Foothills province . 65 Artigotrat ...... 61 Aucella ._... $ 28 Avonia sp . 8 B Barnes, D. F., cited . 61 Barrier bars .._... 61 Beach deposits, present shoreline % 60 Bembexia inumbilicata .............._._.._._._.__ 9 Bentonitic(?) clay, Shublik Formation.... 52 Blastoid ...... 18 Bouger anomalies 61 Bowsher, A. L., cited 24, 61 Brachiopods ...... Brachythyris suborbicularis . Brooks Range, Alapah Limestone. @eanticline -...... ..............2.. 65 Siksikpuk and Shublik Formations.... 19 -T, 9, 11, 18, 14, 15, 18 f 28 28 ORCREE 0,0 nie iver 28 SUDIOEDIS -..... 02.00 lective ieee anes 28 subok . 28 sp :.:... Busxtonia sp 8 C Camarotoechid 8 C d 1.011 Sp 8 Canerintlia BD _...... 20 Canimi 8 Sp . 8 Caninoid coral . 8 Cape Krusenstern area . g 58 Cape Lisburne ...... Cape Lisburne Peninsula Cape Thompson ................-...-._..8; 4; 5, 0, T. 61 Cape Thompson Member, of Nasorak Formation .... T, 14 measured sections ...... Carbonized plant fragments Chapman, R. M., cited 64 Chariot Gravel .._... 58 Chonetes oklahomensis . 8 SP Ae levies. 8 INDEX [Italic page numbers indicate major references] Page Chukehl Seq 1, 60, 61, 64 Cleiothyridina obmazima 8 BD : eel reaver 8 Cloud, P. E., Jr., quoted.. 26 Colifer, A. J., cited ...... 61 Colville Group, nonmarine beds .. 30 Colville River region.. 28 Colluvium _...... 4, 59 Composita sp . 8 Corals ...... 8, 13 colonial .. is 18 HOYT enlil c 14, 18 lenticular heads 13 lithostrotionoid 14, 18 Zaphrentoid .. 5, 9 Corwin Formation 65 Cretaceous rocks ..... Crinoid columnals . Crowbill Point .-- 7. 9, 18, 18 Cyathoclisia sp .. 8 Cystodictya sp .. 9 D Deformation, A&@ _-_... 64, 65 age and origin ... 68 DeLong Mountains .- 8 Dictyoclostus sp ... 8 Dimegelasma sp .. 8 Dip, regional .._... 61 Diphyphylum ingens 9 sp - a 9 Diphystrotion sp 9 Dolomites, classification _......._._._._._.._._._._.-- 5 Duncan, H. M., fossil identification ...6, 14, 18, 20 | .o. .c lel LELA I ese 6, 18, 19 Dutro, J. T., Jr,, cited ..... fossil identification . ..6, 18, 19, 24, 61 ...... 6, 14, 18, 20 E Fabi haus sp 8 Echinoderms Oy M, 38 Endothyroid - 9, 14 Erosion |__. __ 64, 65 Erosion surface, post-Cretaceous & 55 D ..... 1 2.0.02 (C meen dee netninets 8 F Faberophyl sp 9 FABCICUIQDRYIUNM BD 9 Faults: high-angle .................... eastern province L...... we Agate Rock Akoviknak . Angmakrok hypothetical . Ibrulikorak Saligvik .-. western province Fenestella sp ...... 9 Fenestellid bryozoans . 9 Fenestrate bryozoan 9, 14 Figh teeth .........-......- 9 Page Fistulipora sp 9 Flood-plain deposits 60 Folds: broad synclines and anticlines 62 @OBeVPON: ") .:.... llof a 62 drag .. ...ll ude 62 high amplitude . 62, 63 overturned 62 Foraminifera .... 9 Fortress Mountain Formation. 27, 28, 30 Fortress Mountain(?) Formation ...... 4, 27 contact with Kisimilok Formation 28, 63, 64 deposition from turbidity currents... 29 description topography ... Fossil collections ... Fossils, Kisimilok Formation Kogruk(?) Formation Lisburne Group ......-- Nasorak Formation .... Ogotoruk Formation . sedimentary rocks undivided 6 Shublik Formation ..... 20 Siksikpuk Formation . 20 Tupik Formation ...... 18, 19 Telavirak Formation . 26 Fracture cleavage in mudstone ......_.._.._..-.- 63 G Gastropods Geologic history .. 65 Geologic structure f 61 Geomorphology . .-- 64 Gigantoproductus 18 Xone ...if... 18 Gravels: Nyirak :...... 55 Chariot ... 58 Saligvik 56 Gubik Formation, marine deposition 65 H Halobia: ...... 20 Hexaphyllia sp 9 Hubbert, M. K., cited . 64 1 Tbrulikorak fault ...-- iy teo 61 Tbrulikorak thrust sheet Ite .... Ice-wedge polygons Tlikrak Creek ...._--- 19 Ilyirak Creek . 55 Ilyirak Gravel - 55 Imikrak Creek .-- _. 19, 20 Intraformational breccia, Kogruk(?) FOFMAMIOR | > 87 Ipewik River ___.], 19, B5, 58, 60, 61, 64 drainage of ancestral ...... m 65 J Joints in sandstone ...-.------------ Jones, D. L., fossil identification TO Page Jurassic or Cretaceous rocks 20 lithologic types .______ 58 measured section ._._________ ok 58 Jurassic(?) and Cretaceous rocks 64 K Kemegrak Hille ........_.___.____L.__L 1 Kemegrak Lagoon . 1 Kiligvak Creek ___ 57 Killik-Itkillik area .._ 20 Kingak Shale, inferred correlation. 24 Kisimilok Creek _. Kisimilok Formation .. contact with Fortress Mountain (?) Formation ...... 28, 63, 64 contact with Telavirak Formation _ 26 correlation with part of Okpikruak Formation -...... ci cic 28 description 27 fossils .._ topography Kogruk Formation Kogruk(?) Formation breccia, intraformational sedimentary contact with Nasorak Formation. 13 description .. 14 fossils ___ 18 high-angle fault contact with Tupik Formation ._ 19 measured section .._. 85 Kukpuk River.1, 7, 14, 19, 22, 29, 58, 59, 60, 61, 64 drainage of ancestral 65 Kukpuk River valley ... 55 Kunuk Creek ... 5 L Lagoon deposit ..___.___. 59 Lake deposit _ 59 Lakes, thaw _. 57, 59 Lebenepuren 26, 28 Leiorynchus carboniferum 8 Liardiphyllum sp 9 Limestones, classification .____________ 5 Lingula sp :...... 8 Linoproductoid brachiopod 20 Linoproductus sp _________ _ 8, 20 Lisburne Group .....______. 3, 6, 7, 18, 28, 61, 64 contact with sedimentary rocks undivided 5 fossils 8, 9 measured sections $0, 34 Lithostrotionella sp. 1. 9 $p. 2 ..is 9 SD eels 9 Lozonema sp 9 M Mapsorak Lagoon, deposits of ._.________ 60 Marine deposition, Early Mississippian through Early (?) Cretaceous. 65 Martinia sp .._. 8 Martiniopsis sp ___ 20 Measured bedrock sections 80 Michelinia sp 9 Micrite ...... 5, 11 g 15 . 5 measured sections, east .___________. 84 sedimentary rocks undivided 38 West coe nle n. 80 : ...... 20 Moore, G. W., cited - 58, 60 Mack 2... s mes ital en i oen tva. 60 Nalakachak Creek ._ fossil collections .. INDEX Page Nanushuk ..............0....-.........0 29, 64, 65 Nasorak Creek ___. seee T, N4 Nasorak Formation 3, 4, 6, 7 bedding characteristics .._________ T contact with Kogruk Formation __ 13 deposition from turbidity currents _. 138 description fossils ._____ marine deposition .. measured sections ... Cape Thompson Member lower member . upper member . % Niviklik Creek, tributary of Ogotoruk Creek | 2.00. inna 26 Noatak sandstone, possible correlative. 6 0 Ogotoruk Creek .____ .... 1, 20, 22, 58, 60 Ogotoruk Formation ._____________ 20, 4, 27 contact with Shublik Formation ._.. 23, 65 contact with Telavirak Formation. 26 description _ 22 fossils .______ 24 fracture cleavage in mudstone beds .. 63 X-ray diffraction studies, of clays ___. 23 of phosphorite nodules ...______. 28 Ogotoruk Valley . 20, 25, 57, 58, 60 Ogsachak ._____.. 1 Okpikruak Formation, part of, correla- tion with Kisimilok Formation 28 Orbiculoid brachiopod Orthotetes sp ________ P Payne, T. G., cited ___ Peat, radiocarbon age . 7 Pelecypods ...... 9, 20 Pennsylvanian Period, absence of fossilif- erous strata 19 Pentremites sp _______ 9 Permafrost zone . 59 Permian rocks .. 19 measured east section ... 61 measured west section .. 49 Petrographic methods and terminology _.. 5 Phosphorite nodules .. 22, 28, 54 Plant fragments ___ 5, 6, 9 Platyceras sp ._ 9 Plicatifera sp . 3 20 Point Hope area . -_ 58, 64 Point Hope quadrangles . 1 Previous geologic investigations 1, 8 Productold ...... 8 Pumaknak Pond .. 59 Punctospirifer sp _ 8 Pusigrak Lagoon ._. 2 1 Pyriticzed fossils nll L2 31, 49 Q Quadratia sp ___ 8 Quaternary deposits .. 58 R 64 Rhabdomeson sp 9 Rubey, W. W., cited 64 Rynchonelloid .._... 8 S Sable, E. G., cited .._. Sainsbury, C. L., cited Saligvik Creek ___ Saligvik Gravel _. age and origin description __. Saligvik Ridge ___.. Saligvik thrust fault Saligvik thrust sheet . Saligvik Valley ___. Sangamon, erosion prior to Sangamon deposits .______. Sangamon Interglaciation . Schizophoria sp . . Scholl, D. W., cited . 58, 60, 61 Sedimentary breccia, Kogruk(?) Forma- Hon: -.... cc Sedimentary rocks undivided _ contact with Lisburne Group 5 description . .__..___ LL.... & 5 fogSiLS .-. 00000. ee Iie ele 6 Mississippian, measured sections ._ 88 See also Unnamed mudstone-sand- stone-limestone unit. Shublik Formation .___.___ 3, 4, 18, 19, 63, 65 bentonitic(?) clay ae 52 description j 20 folded and faulted relations with Siksikpuk Formation ..______. 19 fossils .........__... 4 measured sections Sigrikpak Ridge _ Siksikpuk Formation . description ...... .. UUU... folded and faulted relations with Shublik Formation 19 Tosstls ..... f 20 high-angle fault contact with Tupik Formation 19 measured sections .. Siphonodendron pauciradiale .. 2 9 BP Nol lenee nei 9 Sochkineophyllum sp 20 Solifluction lobes .._ 59 1.5.20. ini relo in Pied ieee cont 8 ark 8 increbescens 8 keokuk . 8 $D. 8 Spiriferoid ._.. 8 Spirigerella sp . 20 Sq laria sp 20 Stenoporoid bryozoans .___.__._________ 9 Straparollus (Euomphalus) alaskensis__ 20 (Ewomiphalus) sp .......lL.1..1..00 20 Stratigraphic methods and terminology. 4, 5 Stratigraphy ___. 8 summary table 4 See also individual formations. Stream-terrace deposits .____.____._. 58 Swamp deposit .. 59 Syringoperoid .... 9 Syringopora sp .._. 9 Syringothris sp ._ 8 T TP ACHA . ..... 2. . Ee ALAC 6 Tailleur, I. L., cited _.. $ 6 Telavirak Formation 4, 20, 25, 27 contact with Kisimilok Formation .. 26 contact with Ogotoruk Formation.... 26 description _. 25 fossils y 26 measured partial section, Niyiklik Creek _.. 54 Telavirak Hills ... 59, 61 Terebratuloid ...... 8 Terrace deposits, fluvial 64 Terraces, stream-out ........_..._._.._.__ 64 Tertiary or Quaternary deposits, gravels 55 Thrust sheet, Ibrulikorak _ 6, 61, 65, 66 SeNgVilk . ... 30.001 oal ine dud 61, 62 Page Thrust sheets ......}..........._._.__ 61 late folding and faulting ... 65 Tigara" uplift 64, 05 Tigara uplift area, tectonic subsidence .... 66 Tiglukpuk Formation 20 Topography .. 64 badlands .. 57 Trepostomatous bryozoans 9 Triassic rocks ...... 19 measured east section ......__.__._.__._____ 51 measured west section Tundra vegetation _._... Tupik Formation - description ...... 18 OBBHS : 20. -. 010. ide cnl ini oli in conter 18, 19 high-angle fault contact, with Ko- gruk(?) Formation .._._________. 19 INDEX Page Tupik Formation-Continued high-angle fault contact, with Sik- sikpuk Formation . R 19 measured section ._.... i 84 Tussocks . (... ...... tooo Annee nlin inon ial head 59, 60 U O Rime | - aces .s en eline fone P ere hand 6 Unconsolidated deposits ... .8, 4, 55 types .._... _.... L z 55 See also individual units. Unnamed mudstone-sandstone-limestone UnI . 0... re tirana an 3, 5, 83, 65 See also Sedimentary rocks undi- vided. Utukok-Corwin region . 29, 64, 65 Utukok Formation :._........................ 6, 14 W Wachsmuth Limestone ..... Western province, folding thrust faults ...... Wind-deposited silt and sand .._... sh ¥. Yarmouth Interglaciation .__.___________ Z -.... ..2... . LEAL EAR AN ded NB e ieee nd in Ailsa ate ages thee relearn atea t se Boc Zaphrentoid corals . Zaphriphyllum sp ... T1 Page 14 62 61 60 57 ¥ u.s. covernmeEenNnt PRINTING OFFICE: 1967-O 215.321 : PROFESSIONAL PAPER 395 PLATE 2 SE A! PREPARED ON BEHALF OF THE U.S. ATOMIC ENERGY COMMISSION a ~ UNITED STATES THE, INTERIOR GEOLOGICAL SURVEY * NW A oid onn nto vedicaiiitth Affillu‘ll’f gfl‘fii’h i + f I “g T ls l o ra > > a Cape Thompson a ..,_..-.-'---°"" , #: : H The * fart % #] : > > a =. ++ e < s re 1 Lat a .* 3 ia *% g R x ape". y '. gRU?' , a 080% Mint % a* * *. 3 a. + pC ,is ® Cage V R +] P A (ed ["% + % > 1K . * MI UsT...o - x: , wi # A $006 + -* n nRys +, a a f 7 .> -. tes geo. fame, nothin AQ. % - # t rre r ravi aa va ruma asa (aet " ~, ...-.--"."'- a s ie belt *" %. MIkt # 3 M i$ Mik £, < z Minc t"'......’........:Zn.....'.........................'.'....... % '?-.,?...,.-.n'. ... * p > t> "A *% , *' ») C s ; Ms? PS Ms ix“ Min 13 4 © : <3 A. WEST HALF a "a: C "% «5% * 5A o] % g . *C o.(/\ SYMBOLS: - Ms-Sedimentary rock undivided; MI-Lisburne Group undifferentiated; Min-Nasorak Formation of the Lisburne Group undivided; Minl - lower member of the Nasorak Formation; MInc-Cape Thompson Member of the Nasorak Formation; Minu- upper member of the Nasorak Formation, undivided except where zones a through h from oldest to youngest, respectively, are so labeled for.the purpose of showing fault offsets; MIk-Kogruk(?) Formation of the Lisburne Group, undivided except where zones a through h, from oldest to youngest, respectively, are so labeled for the purpose of showing fault offsets; MIit-Tupik Dotted lines are subsurface projections in vertical plane through the shoreline. p SE All Formation of the Lisburne Group; Mitk-Tupik and Kogruk (?) Formations undivided; Ps-Siksikpuk Formation; ks -Shublik Formation; KJo- Ogotoruk Formation. NW A! ® of wan H 5 4 § % z* * ® ¥ : _ ; x; a o be CG ¥. }. R f JZF -an MIK a a - 5 < * aa *.* :5P\;\q‘<‘.@ov fey. Crowbill Point s 00... * .' A & s & ... a % .\) e M a * a. Minc 54 AC 5 f p i> ming =s h X : s f ast "Mir 3 o Bim . f MIk - n, iB a 4.3/ j c > 3 7, a Ad < be < : : £ f * § f" o £ Ygg.‘ 2 & af ® Y* « #s * 3%:° + E.." . 3 B. EAST HALF grr Min s ..'. Ms M OF SEA CLIFFS BETWEEN AGARAK CREEK AND CROWBILL POINT, LISBURNE PENINSULA, NORTHWESTERN ALASKA, SHOWING THE STRATIGRAPHIC SEQUENCE PHOTOMOSAIC AND STRUCTURAL RELATIONS OF THE EXPOSED MISSISSIPPIAN, PERMIAN, TRIASSIC, AND JURASSIC OR CRETACEOUS SEDIMENTARY ROCKS y {Z 7 DAY We 1246 DissLAY|\ Stratigraphy of Some Paleozoic F ormatlons in the Independence Quadrangle Inyo County, California L"kGE‘OLOGICAL S U RV E Y PROFESSIONAL PAP E R - 39 6 summsath. swam E Prepared in cooperation with the Calzforma Department of Conservation, Division o f Mines and Geology Stratigraphy of Some Paleozoic Formations in the Independence Quadrangle Inyo County, California By DONALD C. ROSS G FO MOCICAL _ SURVEY _LRROFr LSssIoNAL . rAPER 3 96 Prepared in cooperation with the California Department of Conservation, Division of Mines and Geology UNITED STYAXTES GOVERNMENT PRINTING OFFICE, WASHING FON - 1966 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director Library of Congress catalog-card No. GS 66-247 For sale by the Superintenéient of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Page Vostract _ :d at . 1 .' Silurian and Devontan(?) 20 introduction. ~:~. L-} c :l. .o Or. L2. 1 Vaughn Gulch 30 Previous stratigraphic and paleontologic studies. 2 Sunday Canyon Formation................ll..... 32 Cambrian System .::.. .:... Ll. [0.0 ...l _ 3 Facies relations and correlations_________________. 34 Bonantsa Kine __ 3 ». Mississippian System....l. ..I... 35 Lead Gulch 5 Perdido _ lallll loll 35 Tamarack Canyon 7. Rest spring Shale-.. ---------------------------- 39 c. lll. oo 10001, __.. 9 Great'Basm stratigraphic and structural background and Mazourka Group 9 y a t t a § fria mi Paleozoic section of the Independence quadrangle as Al Rove Formation: 0200. 10 related to Paleozoic history of the western Great Badger Flat Limestone....._...__...__.;_[__ 12 pam." to atlatls 42 Barre! Spring Formation ...... 15 Stratigraphic 43 Johnson Spring 19 Referenceswited ._ c {liu lagna aay, 60 Ely Springs ._; 20. lly sr o ira d ea 61 Prats Fraur® 1. 2-7. 10. 11: 12. 13-17. 18. 19. ILLUSTRATIONS [Plates are in pocket] - Geologic map of Mazourka Canyon area, Independence quadrangle, Inyo County, Calif. - Generalized columnar section. Measured sections of Barrel Spring and Johnson Spring Formations. Measured sections of the Ely Springs Dolomite. Diagram showing relation of Silurian, Devonian(?), and Mississippian rocks of the Independence quadrangle to rocks in areas to the southeast in California. Page Index maps showing regional setting of Independence 2 Photographs: ~- Kine Dolomite. l l.} 0.00 l gl ec [Oc tu ylllatp od 5 3. Lead Gulch Formation, showing outcrop of metamorphosed calcareous siltstone near Whiteside mine. 6 #. Tamarack Canyon 00 t Du :f ait ll - Lok ok Copain gel 8 o: Al econ lll e Tt r ~ tater [Co 11 6. Al Rose Formation, showing graptolite-bearing uppermost 11 ¢. Badger Flat .."... t} _o 20 l IO} l rll. la atty, 13 a Ahotomicrographs of calcaremte in Badger Flat Limestone. .ll. l.... Il cc; Nlt M: O 13 . Photograph of Barrel Spring Formation, showing view north of Blue Stone tale 16 Photograph of Barrel Spring Formation, showing middle limestone member at type section in Mexican Gulch. 16 Photograph showing blocky shale and mudstone of upper part of Barrel Spring 17 Graph showing variation in thickness and lithology, Johnson Spring sauce 20 Photographs: 19. Johnson Spring Formation. ust at I ede ece oneness (ae ay 21 14. Johnson Spring Formation, showing rib of upper quartzite north of Blue Stone tale mine 23 15. Ply Springs 1.0. ...l olla ct ae f ml sik e talus 27 J6.. Ely springs Dolomite. c...}. _._... }.} XO llc lc c lovley 28 17. Vauehn Gulch lit latte _ 30 of conglomeratic sandstone, Perdido Formation... l 36 Photograph of Rest Spring Shale, showing bluff exposure east of Pops 39 TII STRATIGRAPHY OF SOME PALEOZOIC FORMATIONS IN THE INDEPENDENCE QUADRANGLE INYO COUNTY, CALIFORNIA By Donan C. Ross ABSTRACT In the Mazourka Canyon area of the Independence quadrangle in the Inyo Mountains of California, a well-exposed conform- able sequence of Upper Mississippian, Pennsylvanian, and Per- mian beds overlies an erosional surface cut on a conformable sequence of Cambrian, Ordovician, Silurian, and Devonian(?) rocks. The rocks from the Bonanza King Dolomite (Middle and Upper Cambrian) through the Rest Spring Shale (Upper Mississippian) are particularly well-exposed, easily accessible, and only moderately deformed and contact metamorphosed ; and they reveal significant lithologic variations along strike. The sequence of Cambrian, Ordovician, Silurian, and Devon- ian(?) rocks lying beneath the unconformity comprises about 10,000 feet of mostly thin-bedded fine- to medium-grained clastic rocks, dolomite, and limestone. Much of the carbonate ma- terial also is clastic. These rocks probably belong to a transi- tional assemblage between the siliceous eugeosynclinal assem- blage and the carbonate miogeosyneclinal assemblage of the Great Basin. Both geographically and lithologically, though, the rocks are nearer the carbonate assemblage. The Upper Mississippian clastic beds that overlie the un- conformity are probably part of the overlap assemblage of the Great Basin. These beds, about 3,000 feet thick, are dom- inantly shale and siltstone, although the lower several hundred feet is mostly sandstone and conglomerate containing abundant chert fragments. Along the strike from the dominantly carbonate terrane southeast of the quadrangle to the northern part of the Inde- pendence quadrangle, major lithologic changes occur, particu- larly in the Ordovician and Silurian rocks. In the Mazourka Canyon area, for example, the interval occupied by the Eureka Quartzite over much of the western part of the Great Basin is made up of interbedded quartzite, dolomite, limestone, shale, and siltstone; and the Ely Springs Dolomite grades north- westward from cherty dolomite to dominantly massive black chert. The most striking change occurs in the Silurian rocks ; dolomite, which is widespread southeast of the Mazourka Can- yon area, grades northwestward in a few miles into coral-rich bioclastic and argillaceous limestone, which in turn grades northward into graptolite-bearing shale and limestone. The Mississippian and younger rocks of the overlap assemblage in the Independence quadrangle also have a higher percentage of clastic material than do equivalent rocks to the southeast. INTRODUCTION In the Inyo Mountains of the Independence quad- rangle (fig. 1), near the west margin of the Great Basin, is a well-exposed structurally simple Paleozoic sedi- mentary section. - The rocks are intruded and generally slightly metamorphosed by batholithic masses of Mesozoic granitic rock that are probably part of the Sierra Nevada composite batholith. A recent U.S. Geological Survey Bulletin (with an accompanying geologic map at a scale of 1 : 62,500 (Ross, D. C., 1965) ) briefly describes the map units in the Independence quadrangle. The Paleozoic sedimentary section is about 16,000 feet thick and ranges in age from Early Cambrian to Permian (pl. 1). It appears to be conformable throughout except for an erosional unconformity that separates the Upper Mississippian rocks from the Silurian and Devonian (?) rocks. The oldest sedimentary rocks in the section-the Poleta, Harkless, Saline Valley, and Mule Spring For- mations (Early Cambrian), and the Monola Forma- tion (Middle Cambrian)-are extensively exposed north of the quadrangle, where they were studied in detail by Nelson (1962). Inasmuch as these forma- tions are exposed only over limited areas in the Inde- pendence quadrangle, are somewhat metamorphosed, and generally are not easily accessible, they will not be discussed in this paper. Brief descriptions of these units in the Independence quadrangle were published by D. C. Ross (1965). The youngest Paleozoic sedimentary rocks-the Keeler Canyon Formation (Pennsylvania and Per- mian) and the Owens Valley Formation ( Permian)- are extensively exposed southeast of the quadrangle (Merriam and Hall, 1957) ; there they are abundantly fossiliferous. Within the Independence quadrangle no complete sections are preserved, and the rocks are metamorphosed to such an extent that no fossils have been found. These formations, therefore, will not be discussed in this paper, but they are described briefly by D. C. Ross (1965). The diagrammatic columnar section (pl. 2) briefly summarizes the formations dis- cussed in this report. #4 STRATIGRAPHY OF PALEOZOIC FORMATION, Formation descriptions in this report are mostly based on outcrops within the Independence quadrangle, but the distribution of some formations in other parts of the Inyo Mountains is also discussed. To avoid repe- tition in the discussions of stratigraphic relations, only the lower contact is described for each formation. The measured sections were made from tape and compass traverses by Fred K. Miller and me, except for the Rest Spring Shale section, where I was assisted by Craig D. Ross. INDEPENDENCE QUADRANGLE, CALIFORNIA PREVIOUS STRATIGRAPHIC AND PALEONTOLOGIC STUDIES The first stratigraphic study in the Independence area was made in 1912, when Edwin Kirk did a reconnais- sance in the Inyo Mountains (in Knopf, 1918). Several references to the Paleozoic section in Mazourka Canyon were made in the report on this work. Since the work of Kirk, which called attention to the fossiliferous Paleozoic section in Mazourka Canyon, numerous geologists have examined and reported on N ~ (A Candelaria , | Hills \ |- / p- --- 1 I ~ \( | , Pioche® f Quartzite Mountain Mount Morrlin (N. T. S.) X Pendant x I Pine Creek ® | | r K Pendant } BIShOD Creek\ MOBuanTaw Pendant I Quartz Spnng 4 X so eet a nesses tee [soca [4 INDEPENDENCE C «be» \ ® New York do | | Butte 4) < ° Darwin 4’\ \ h \ ( x . 3 y ) f Z x C(5:00dsprmgs\ | x % | i s & | sls) ~ I x (ys War T, " _T| ~ \ | \ 2 \[\ ' oi Re LOS AgGELES Numi e o a we r tm F w Y 50 0 50 MILES ALLIE s ___ yx ~' ~ 118" BLANCO MOU NT AI N WAUCOBA WAUCOBA MouNntTAIN springs | * x Q} N & Area of geologic map 37° - $ g Quartz Spring area D P Independe UBEHEBE PEAK A Mount $0 Whitney fie A >, > 00 of DARWIN [PANAMINT j BUTTE Darwin o HAIWEE \Iv| RESERVOIR 10 20 MILES 1... _J. - 12 3a cd NEVADA 3 | | QUADRANGLE | LOCATION H > FIGURE 1.-Regional setting of the Independence quadrangle. PREVIOUS STRATIGRAPHY AND PALEONTOLOGIC STUDIES 3 specific measured sections or small areas. Most of this work has been concerned with the paleontology of the units, and little systematic geologic mapping has been done. Stauffer (1930) measured a section east of Kearsarge and collected fossils both there and near Barrel Springs from strata which at that time were referred to the Devonian. Phleger (1933) named and briefly described two new Ordovician formations (Mazourka and Barrel Spring) in a report concerned chiefly with the systematic paleon- tology of the faunas in these formations. Waite (1953), reporting on the fauna from the same beds that Stauffer studied, showed that these beds were Silurian rather than Devonian. Langenheim and several of his students (1956) meas- ured several sections in Mazourka Canyon and collected fossils from the Middle and Upper Ordovician rocks. Pestanan (1960) described the fauna (mainly corals, including several new species) in the Johnson Spring Formation, which he named. Greife and Langenheim (1963) described sponges and brachiopods from the Mazourka Formation. CAMBRIAN SYSTEM BONANZA KING DOLOMITE NAME AND DISTRIBUTION The Bonanza King Formation was named by Haz- zard and Mason (1936, p. 234) for the Bonanza King mine in the Providence Mountains of southeastern Cal- ifornia. -It is a distinctive unit over much of the south- western part of the Basin and Range province. In the Inyo Mountains the formation is almost exclusively dolomite, so the name Bonanza King Dolomite (Ross, D. C., 1965) is used in this report; the name Bonanza King Formation is used where rocks other than dolo- mite are abundant. The formation crops out in a broad arcuate belt as much as 214 miles wide along the crest of the Inyo Mountains from the north boundary of the quadrangle south to the latitude of Barrel Springs. South from Barrel Springs the outcrop becomes a much thinner, considerably faulted, and contact-metamorphosed belt that extends nearly to the mouth of Mazourka Canyon. North of the quadrangle this outcrop belt extends dis- continuously for several miles along the east face of the Inyo Mountains in the Waucoba Mountain quadrangle (C. A. Nelson, written commun., 1961). South of Mazourka Canyon, faulting and granitic intrusions disrupt the belt of outcrop; but in the New York Butte quadrangle I have seen rocks that may correlate with the Bonanza King Dolomite on the east face of the Inyo Mountains (along the trail east of sec. 80, F. 15 S., R. 37 E.). The Bonanza King Dolomite also underlies rather extensive areas along the east side of the Inyo Mountains north of Paiute Canyon in the Waucoba Wash quadrangle. THICKNESS AND STRATIGRAPHIC RELATIONS The Bonanza King Dolomite is about 2,800 feet thick at a measured section northeast of Badger Flat. The greatly expanded width of the Bonanza King outcrop southeast of the measured section is largely due to the topography and to exaggeration by a monoclinal bend in the formation, not to thickening of the formation. . At the type section in the Providence Mountains, Hazzard and Mason (1936, p. 234) included about 2,000 feet of strata in the Bonanza King. In the Nopah Range, Hazzard (1937, p. 318-319) measured 4,480 feet of beds in the combined Bonanza King and Cornfield Springs Formations. The Cornfield Springs in the Nopah Range is now considered to be equivalent to the upper part of the Bonanza King at the type section (Palmer and Hazzard, 1956, p. 2497-2499). At the Nevada Test Site, Barnes, Christiansen and Byers (1962, p. D30) assigned 4,600 feet of beds to the Bonanza King; and at Bare Mountain, Nev., Cornwall and Kleinhampl (1961) measured 3,800 feet of this formation. The Bonanza King Formation thus ranges in thickness from at least 2,000 feet to nearly 5,000 feet ; the nearly 3,000 feet in the Inyo Mountains is somewhat less than an average thickness. The Bonanza King Dolomite appears to rest con- formably on limestone and fine-grained clastic beds of the Monola Formation (Nelson, 1965). The contact is marked by an abrupt change in lithology, but con- cordant attitudes near the contact in the vicinity of the measured section suggest continuous deposition. East of the crest of the Inyo mountains, some discord- ance was noted along the contact, but it is probably chiefly the result of faulting. LITHOLOGY The Bonanza King Dolomite is easily recognized in the field by its conspicuous color banding. The bands, in varied shades of gray, range from a fraction of an inch to a few tens of feet in thickness. This wide- spread banding was aptly described by Noble (1934, p. 177) as suggesting the stripes of a zebra. Dolomite is the dominant rock type of the formation, almost to the exclusion of other rocks. Black chert, in nodules and in beds as much as 1 foot thick, is present locally. Limestone was noted at only two localities: (1) about 2,500 feet east of the Blue Bell mine, where two 11-foot-thick layers of white to buff limestone are present in the light-gray dolomite sequence, and (2) 3.8 miles S. 36° W. of the northeast corner of the 4 STRATIGRAPHY OF PALEOZOIC FORMATIONS quadrangle (at the attitude symbol N. 10° E., 25° W.), where purplish-pink and black limestone as well as somewhat argillaceous dolomite make up a zone no more than 50 feet thick. This latter zone may equate to a regional marker described by Barnes and Palmer (1961, p. C©102-C103) as a "persistent brown-weathering siliceous carbonate sequence about 40 feet thick" that separates the upper and lower members of the Bonanza King. The limestone zone was not recognized in the measured section. Much of the dolomite in the Bonanza King is re- markably pure, but some layers are liberally flecked with tremolite, phlogopite, and, locally, forsterite, which attest to the reconstitution of impurities in the dolomite by contact metamorphism. Aside from these metamorphic minerals, insoluble residues contain minor quartz and argillaceous material but rarely con- tain any heavy minerals. - North of Tamarack Canyon, near the northeast-trending fault (dashed on map) abundant pseudomorphs of iron oxide after pyrite were found in a thinly alluviated area. Some of the iron oxide masses were several inches across and massive. Others, as much as one-half inch in diameter, preserve in detail striated pyritohedrons. These iron impuri- ties were not found in place, but they probably weathered out of the underlying dolomite. Small pseudomorphs of pyrite have been found in place in other outcrops of Bonanza King Dolomite. No attempt was made to map members in the forma- tion. - Five units were distinguished along the measured section (see p. 43), chiefly on the basis of color changes due to differing proportions of light-to dark-gray bands. The uppermost unit (unit 5) could have been mapped separately over much of the area. It is massive and gen- erally weathers to craggy yellowish-gray outcrops that strongly contrast with the striped gray lower units. South of the measured section a distinctive black dolo- mite unit at least 150 feet thick lies between unit 5 and the striped lower units. This black dolomite may cor- relate with a similar black dolomite band that is near the top of the Bonanza King Formation at Bare Moun- tain, Nev. (Cornwall and Kleinhampl, 1961). Unit 5 would then equate to the combination of the white and gray bands that overlie the black band at Bare Moun- tain. The three broad color bands at the top of the Bonanza King Formation are a regional characteristic of the unit, as similar thick bands also occur in the Nopah Range (Hazzard, 1937, p. 319) and at several other localities in the southwestern part of the Great Basin, including the Quartz Spring area (J. F. Mc- Allister, oral commun., 1962). About 7 miles east of Mazourka Canyon, on the east side of the Inyo Moun- tains in the Waucoba Wash quandrangle, the three , INDEPENDENCE QUADRANGLE, CALIFORNIA broad color bands at the top of the Bonanza King Dolomite are mappable. The black dolomite band, where mapped separately, is shown on the geologic map as a dotted line. It either pinches out to the north or is faulted out, for it was not recognized along the measured section. Bedding in this formation is typically thin and ir- regular. Color-banded strata that are several tens of feet thick appear massive from a distance, but these, too, are generally thinly bedded. Commonly, coarse- grained white dolomite in anastomosing strlngers pro- duces a mottled or dappled surface (fig. 24) in a variety of patterns (fig. 2B). Though a dark groundmass is most common, locally, darker dolomlte mottles a lighter matrix. In places the dark-gray dolomite matrix is speckled with white dolomite and resembles what was called "Guinea-hen dolomite" by Calkins and Butler in an area in Utah (1943, pl. 11A, after p. 14). Mottled gray dolomite is common in other areas where the Bo- nanza King Formation is exposed; as far away as cen- tral Utah, rocks of a grossly similar age also exhibit this pronounced mottling (Morris and Lovering, 1961, fig. 21, p. 49). Fucoid markings are also widespread (fig. 2C) ; some strikingly resemble features called "twiglike bodies" in a Cambrian carbonate unit in Utah (Calkins and Butler, 1943, pl. 10B). Very thinly laminated light-gray dolomite, which generally splits into slabby to flaggy fragments, is also locally abundant. FOSSILS, AGE, AND CORRELATION Spherical to ellipsoidal bodies 5-25 mm in diameter and having conspicuous concentric bands are abundant in unit 1 and present but much less abundant in unit 3. These features are probably algal structures; they re- semble forms called @irvanella in other outcrop areas of this formation. Fucoid markings that resemble worm trails have also been found, but none of the fossils found in the quadrangle help establish the age of the formation. The Bonanza Kink Dolomite is underlain by rocks that are continuous with fossiliferous Middle Cambrian strata a few miles north of the quadrangle (Nelson, 1965) and is in turn overlain by a formation containing an Upper Cambrian fauna. - On the basis of work at the Nevada Test Site and in nearby areas in southern Nevada, Barnes and Palmer (1961, p. C103) assigned most of the Bonanza King Formation to the Middle Cambrian, but the uppermost part is considered to be Late Cambrian. A similar age range is assumed for the formation in the Independence quadrangle. The nearest correlative rocks that have been described in the literature belong to the Racetrack Dolomite in Racetrack Valley about 30 miles to the southeast (Mc- CAMBRIAN Allister, 1952, p. 8-9). Correlative rocks are also present, but as yet unmapped, in the Saline and Last Chance Ranges between Racetrack Valley and the Independence quadrangle. LEAD GULCH FORMATION NAME AND DISTRIBUTION The Lead Gulch Formation was named for exposures along Lead Gulch in the Independence quadrangle (Ross, D. C., 1963, p. B74). The formation is a thin relatively continuous faulted and folded belt which ex- tends from the north edge of the quadrangle south to about the latitude of Independence. This belt of out- crop continues north into the adjoining Waucoba Moun- tain quadrangle for about 1 mile (C. A. Nelson, written commun., 1961). South of the Independence quad- rangle, rocks having similar lithologies were seen at several points along the west face of the Inyo Mountains east of Lone Pine, in the New York Butte quadrangle. These rocks are well exposed along the trail east of see. 30, T. 15 S., R. 37 E. The Lead Gulch Formation is SYSTEM 5 FicurE 2.-Bonanza King Dolomite. A, Coarse-grained white dolomite and finer grained dark-gray dolomite in nodular beds. White dolomite in anastomosing irregular stringers produces a mottled surface. Out- crop along Inyo crest west of Badger Flat at elevation 10,960 feet. B, Irregular bedding shown by coarse white lenses of dolomite anastomosing through darker, gray dolomite. Along measured see- tion northeast of the Blue Bell mine. C, Fucoid markings in the dolomite. Along measured section northeast of the Blue Bell mine. also exposed along the east face of the Inyo Mountains north of Paiute Canyon, in the Waucoba Wash quadrangle. THICKNESS AND STRATIGRAPHIC RELATIONS At the type section of the Lead Gulch Formation (LG-1 on pl. 1), the measured thickness is 280 feet: however, the base of the formation is contorted and presumably is faulted. The maximum thickness prob- ably is at least 300 feet, but it may well be more. At many localities the Lead Gulch Formation has been thinned considerably or squeezed out entirely between thick dolomite units that bound it. The contact of the Lead Gulch Formation with the underlying Bonanza King Dolomite is almost every- where structurally disturbed but is presumed to be con- formable, as the attitude of the rocks on both sides of the contact is similar. LITHOLOGY The Lead Gulch Formation comprises limestone, silt- stone, dolomite, chert, and shale interlayered in a reg- STRATIGRAPHY OF PALEOZOIC FORMATIONS, FicurE 3.-Lead Gulch Formation. Outcrop of dominantly orange- weathering metamorphosed calcareous siltstone (dark beds stand out in relief). - Weathered back slits contain gray limestone. Exposure is about 600 feet east of the portal of the Whiteside mine (S% sec. 5, T. 13 S., R. 36 F.). ularly bedded sequence. - Beds are most commonly 14-2 inches thick but locally are as much as 5 inches thick. Blue- to medium-gray limestone and thinly laminated calcareous siltstone that weathers out in relief to shades of bright orange and red are the dominant and charac- terizing rock types of this formation. Most commonly these rock types are present in about equal amounts; at some places, however, the siltstone fraction domi- nates (fig. 3), and at other places thin-bedded limestone is far more abundant than the fine-grained clastic rocks. These lithologic types can most easily be seen in the ex- posures shown in figure 3 and along Lead Gulch, where a short trail leads from Mazourka Canyon, at the start of the Betty Jumbo mine road, to small mine workings in the Lead Gulch Formation. The siltstone beds are commonly folded and faulted, owing to their brittle- ness, but the regularity of the original beds still is read- ily apparent. At the base of some sections is as much as 20 feet of fissile olive-brown to dark-green shale, or its metamor- phosed equivalent. This unit, though not seen at the type section, probably was originally present but has been squeezed out. This shale, where present, is an ex- cellent marker bed to indicate the base of the formation. It is particularly useful where the Lead Gulch Forma- tion is contorted and overturned and the overlying and underlying dolomites are metamorphosed to coarse mas- sive indistinguishable units, as north of Lead Gulch along the granitic contact. Where the shale is meta- morphosed, it is altered variously to green chlorite schist containing minor quartz, or to a blocky, fractured green hornfels having a dense quartz groundmass (0.005 mm) in which is sprinkled abundant pale-green amphi- bole and some reddish-brown biotite. INDEPENDENCE QUADRANGLE, CALIFORNIA Black chert in thin regular layers or nodular beds as much as 4 inches thick is also present in the formation, but much of what was thought in the field to be chert proved, on microscopic examination, to be siltstone or calcareous siltstone. Thin-bedded dolomite in different shades of gray is locally common near the top of the formation. At the type section, dolomite is somewhat more abundant than at most exposures. The alternation of gray limestone and brown-, orange-, and reddish-weathering siltstone is repeated several times in the stratigraphic column in the Inde- pendence area. - The fairly regular interbedding of the two rock types, as shown in figure 3, distinguishes the Lead Gulch Formation from the formations in which these two rock types are irregularly interbedded. The Al Rose Formation (Lower Ordovician) is the unit most likely to be confused with the Lead Gulch. - In most out- crops, however, the Al Rose has irregular bedding and a predominance of silty material. - The limestone fraction commonly occurs in less resistant lenses that weather back to form distinctive "eyes," which are rare in Lead Gulch outcrops. FOSSILS, AGE, AND CORRELATION Trilobites establishing a Late Cambrian age for the Lead Gulch Formation have been identified and reported on as follows by A. R. Palmer (written commun., 1961, 1962) : USGS colln. 3749-CO. - Collected 6,700 feet N. 70 E. from SE cor. sec. 36, T. 11 S., R. 35 E. (California coordinates, zone 4; 2,271,900 E., 589,400 N.). Homagnostus sp. Pseudagnostws sp. Indeterminate acrotretid brachiopods Echinoderm parts This collection contained two rock types: a fine-grained gray limestone without identifiable trilobites, and a white limestone with abundant trilobite hash. This latter sample was dissolved in formic acid and yielded a thoroughly de- formed suite of small silicified (? )trilobites, indeterminate acrotretid brachiopods, and echinoderm parts. The dominant identifiable trilobites are agnostids representing the genera Homagnostus and Pseudagnostus. Homagnostus is a charac- teristic agnostid in the lower Nopah faunas, so this collection probably came from beds correlated with the lower Nopah. It is certainly from beds no older than the Late Cambrian Aphel- aspis zone of Dresbach age. This is just about the westernmost dated Upper Cambrian locality in the United States (ex- clusive of Alaska). USGS colln. 3750-CO._ Collected about 7,000 feet east of John- son Spring. (California coordinates, zone 4; 2,276,300 E., 574,750 N.). Homagnostus? Loganelius? USGS colln. 3802-CO. _ Collected about 6,900 feet N. 80° E. of Johnson Spring (California coordinates, zone 4; 2,276,000 E., 576,200 N.). CAMBRIAN SYSTEM T. Loganellus sp. The specimens represent a species of what is currently being called Loganellus. This type of trilobite characterizes the beds just above the Dunderberg interval over much of Nevada. At most localities where I have seen these, they are at or near the base of an interval of interbedded thin lime- stones and black cherts. The lithology of your sample is much like that in parts of the Emigrant Formation. At several other localities in the formation, black chitinous shells of acrotretid brachiopods and trilobite fragments were found. No fossils were found in the basal green shale; all the identifiable fossils were from limestone beds. No fossils have been found in the beds presumed to be part of the Lead Gulch Formation elsewhere in the Inyo Mountains (in the Waucoba Mountain, Waucoba Wash, and New York Butte quadrangles). The nearest occurrence of a similar section that has been dated by fossils is in the Quartz Spring area. Here, the lower 250 feet of unit 1 of the Nopah Forma- tion (McAllister, 1952, p. 9) is "limestone, in places silty or cherty, weathering brown, interbedded with light- olive shale." Trilobites of the EZvimnia zone of the Franconian Stage place this unit at the bottom of the middle division of the Upper Cambrian (McAllister, 1952, p. 10). The Lead Gulch Formation is thus considered to be approzhmately equivalent to the basal unit (unit A) of the} Nopah Formation in its type area (Hazzard, 1987, 11> 320). The basal Nopah comprises limestone, shale, calcareous sandstone, and sandy shale; trilobites of the Elvimia zone are also found in these beds. The Lead Gulch Formation also is probably approxi- mately equivalent to the 100-foot-thick Pseudagnostus- bearing lower shale member plus the overlying 100- to 200-foot-thick limestone containing chert, siltstone, and dolomite lenses that make up the lower part of the Nopath ormation in the Bare Mountain area, Nevada (Cornwall and Kleinhampl, 1961). Sections of thin- bedded, limestone, shale, siltstone, and some chert that are markedly similar to the Lead Gulch Formation occur {it Striped Hills near Lathrop Wells, Nev., and in the Specter Range quadrangle, Nevada. These sections, which are at least in part referred to the Dunderberg Shale (H. R. Cornwall, oral commun., 1964; Burchfiel, 1964, p. 49), are exposed in reddish-brown-weathering slopes between the more resistant carbonate rocks of the Bonanza King and Nopah Formations. The stratigraphic position of the Lead Gulch Forma- tion is comparable to that of the Dunderberg Shale as describéd in the Nevada Test Site area (Barnes and others, 1962, p. D31). The thickness and general lith- ology df the Dunderberg are also comparable to those of the Lead Gulch; but the wavy, nodular bedding de- seribed both at the Test Site and in the type area of the Dunderberg in the Eureka region (Nolan and others, 1956, p. 18) differs somewhat from that of the typical Lead Gulch. At the Nevada Test Site, fossils in the Dunderberg Shale are in the Dunderbergia zone, which is of early Late Cambrian (Dresbach) age (Barnes and others, 1962, p. D31). Trilobites of the Elvina zone of middle Late Cambrian (Franconian) age are present near the base of the overlying Windfall Formation (Barnes and others, 1962, p. D31). On the basis of similar stratigraphic position, lithol- ogy, and fauna, the Lead Gulch Formation probably equates to the Dunderberg Shale plus at least some of the immediately overlying Catlin Member of the Wind- fall Formation (Barnes and Byers, 1961, p. C103). The same types of trilobites that are found in the Lead Gulch Formation (Homagnostus, Pseudagnostus, and Loganellus) are also found in the lower $50 feet of the Catlin Member of the Windfall Formation. The lower part of the Catlin Member also contains other trilobites of the Zlvinia zone (Barnes and Byers, 1961, p. C©105- ©106). The northward extent of the Lead Gulch Formation as a mappable unit is limited by a facies change in which the Middle and Late Cambrian are represented by the Emigrant Formation, a trilobite-bearing thin- bedded sequence of limestone, claystone, siltstone, and chert. This formation is widespread in Esmeralda County, Nev. (Albers and Stewart, 1962, p. D2t; McKee and Moiola, 1962, p. 536-537), and has also been recognized in the Inyo Mountains in the Blanco Moun- tain quadrangle (Nelson, 1963) about 20 miles north of the Independence quadrangle. McKee and Moiola (1962, p. 537) described the upper member of the Emigrant Formation as approxi- mately 2,000 feet of thin-bedded blue to gray limestone alternating with %- to 2-inch-thick buff-to-black bands of chert or iron-stained limestone. Orange to reddish- gray calcareous shale, very thin bedded calcareous sand- stone, and very thin bedded chert are abundant near the top. Trilobites found in this member include Homagnostus and Pseudagnostus. As described, this member is much like the Lead Gulch Formation but is thicker; this suggests that the Lead Gulch may be a tongue-like southward extension of the Emigrant Formation. TAMARACK CANYON DOLOMITE NAME AND DISTRIBUTION The Tamarack Canyon Dolomite was named for ex- posures in the Independence quadrangle (Ross, D; C., 1963, p. B77). The strata now mapped as Tamarack 8 STRATICGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNTA Canyon were considered to be part of a thick sequence of "limestones, probably of Beekmantown age" by Kirk (in Knopf, 1918, p. 34) ; more recently, Langenheim and others (1956, p. 2087) considered the Tamarack Canyon beds to be part of the Pogonip Group. The formation is exposed in a fairly continuous arcu- ate belt from the north edge of the quadrangle to the latitude of Barrel Springs. From there south to the Betty Jumbo mine area, the Tamarack Canyon Dolo- mite is faulted and discontinuous, as well as strongly folded. The outcrop belt of the Tamarack Canyon continues northward for about 1 mile into the Waucoba Mountain quadrangle, and similar rocks are exposed a few miles farther north along the west front of the Inyo Mountains (C. A. Nelson, written commun, 1961). In the southern part of the Independence quadrangle, granitic rocks disrupt the outcrop belt of the Tamarack Canyon ; but east of Lone Pine and north of Dolomite, in the New York Butte quadrangle, sequences with a similar lithology and in the correct stratigraphic posi- tion can be traced along the west face of the Inyo Moun- tains for about 2 miles. These beds are well exposed along the trail east of see. 30, T. 15 S., R. 37 E. Other exposures of the Tamarack Canyon Dolomite have been noted in the northwest quarter of the Waucoba Wash quadrangle. The Tamarack Canyon Dolomite is thus a mappable unit throughout much of the Inyo Mountains. THICKNESS AND STRATIGRAPHIC RELATIONS At the measured section southeast of Badger Flat, the Tamarack Canyon Dolomite is 910 feet thick. In most other areas the formation is faulted, and a maxi- mum thickness cannot be measured. The basal contact of the Tamarack Canyon Dolomite with beds of the Lead Gulch Formation is undoubtedly conformable, as it is essentially gradational and some- what arbitrary. -It is marked by the highest occurrence of thin-bedded limestone in the underlying Lead Gulch Formation. In some places thin-bedded dolomite and limestone are interlayered near this contact. LITHOLOGY The predominant rock type is laminated to thick- bedded very light gray to medium-gray dolomite (fig. 4A) that normally weathers to a monotonous dull gray surface. The measured section described (see p. 44) is fairly typical. Outcrops that appear thick bedded to massive from a distance prove to be thin bedded on close observation; the bedding is shown chiefly by a fluted weathered surface that accentuates minor differ- ences in the resistance of the thin dolomite layers. Black chert, both as nodules and as nodular beds as much as a few inches thick, is scattered to abundant in the dolomite (fig. 4B) ; though widespread, it is absent in many outcrops. Chert nodules are particularly abundant in the rock near the mouth of Lead Gulch and directly across the Mazourka Canyon road to the west. - The general form of many nodules suggests that they are secondary replacements of the carbonate. Limestone was only noted at a few localities in the Tamarack Canyon Dolomite. - Although generally very Penny for 4.-Thin-bedded gray Tamarack Canyon Dolomite. scale. A, Along measured section about 6,000 feet N. 60° E. from SB cor. see. 36, T. 11 S., R. 35 E. B, Along measured section about 6,300 feet N. 64° E. from SE cor. see. 36, T. 11 S., R. 35 E. Note irregular black chert nodules. pure, the limestone and the dolomite may locally be somewhat argillaceous or contain scattered flakes of phlogopite that suggest metamorphism of impurities. Silty admixtures are rare in contrast to the overlying Ordovician carbonate rocks, which are characteristically silty. In figure 4, the very thin beds and laminae in varied shades of gray give a distinct color banding to the out- crop.. Though this thin banding is conspicuous locally, weathered surfaces much more commonly are a monoto- nous dull gray ; nowhere is the color banding comparable to that which characterizes the Bonanza King Dolomite. The Bonanza King and Tamarack Canyon Dolomites, which are generally so distinctive, become indistin- guishable near granitic contacts; there, both are coarse grained and dazzling white on fresh surfaces. FOSSILS, AGE, AND CORRELATION Fossils have not been found in the Tamarack Canyon Dolomite, but those found in the overlying and under- lying formations indicate that it could be Late Cam- brian or Early Ordovician or both. A Late Cambrian age is tentatively assigned to the Tamarack Canyon be- cause the absence of clastic quartz and silty interlayers in this unit suggests more affinity with the Nopah For- mation of Late Cambrian age than with the lower part of the Pogonip (Group of Early and Middle Ordovician age, in which clastic material is widespread. The map- pable lithologic break between the essentially clastic- free Tamarack Canyon Dolomite and the Al Rose Formation of Early Ordovician age, with its abundant clastic material, is thus tentatively correlated with the contact between the Nopah Formation and the Pogonip Group. This break also is considered to be the bound- ary between the Cambrian and the Ordovician. Both the Nopah and Tamarack Canyon Formations are predominantly dolomite, but there appears to be a significant difference between them. The Nopah Formation has characteristic color banding in a wide range of shades of gray in its type area in the Nopah Range (Hazzard, 1937, p. 320), in the Quartz Spring area (McAllister, 1952, p. 9), and at many other locali- ties, including the west flank of the Last Chance Range only 25 miles northeast of the Independence quad- rangle, This banding, so aptly named "zebra-strip- ing," which is diagnostic of both the N opah Formation and thF Bonanza King Formation, is conspicuously lack- ing in the Tamarack Canyon Dolomite throughout the Inyo Mountains. Speculation that the Tamarack Can- yon is Nopah that has lost its banding owing to incipi- ent metamorphism does not seem valid, for the diagnos- tic banding is well preserved in the underlying Bonanza King Dolomite, which had the same opportunity for metamorphism. The lack of color banding was the ORDOVICIAN SYSTEM 0 chief reason for proposing a local formational name in the Inyos for this presumed correlative of at least part of the Nopah Formation. Possibly the prevalence of extremely thin bedding in the Tamarack Canyon Dolo- mite is a precursor of the change from the thicker bedded dolomitic strata of the Nopah type to thin-bedded lime- stone and fine-grained clastic rocks of the Emigrant type. All the Tamarack Canyon Dolomite except its lower member is tentatively correlated with the Nopah For- mation of the Quartz Spring area (McAllister, 1952, p. 9) ; the lower member may be correlative with the Lead Gulch Formation. Similarly, the Nopah Formation at its type area (Hazzard, 1937, p. 321), but minus basal unit "A," is probably a Tamarack Canyon equivalent, as is at least the Smoky Member of the Windfall For- mation in the Nevada Test Site area (Barnes and Byers, 1961, p. C105). Unit "a" of the Pogonip Group in the Darwin area (Hall and MacKevett, 1962, p. 8) also may be equivalent to the upper part of the Nopah, and hence to the Tamarack Canyon. ORDOVICIAN SYSTEM MAZOURKA GROUP The term Mazourka Formation was first used by Phleger (1983, p. 2-3) to describe the rocks now re- ferred to the Mazourka Group (Ross, D. C., 1963, p. B78). Detailed mapping in the Independence quadran- gle showed that the two units that Phleger noted in his Mazourka Formation were mappable formational units almost the entire length of the Inyo Mountains, so they were named the Al Rose Formation and the Badger Flat Limestone by D. C. Ross (1963). Phleger's Mazourka Formation was raised to group status because it is correlative in part, and possibly in its entirety, with the Pogonip Group. The term Pogonip Group is not used for rocks in the Independence quadrangle because of differing opinions as to what is its equivalent in the Inyo Mountains. Langenheim and others (1956, p. 2087, 2091) considered the Mazourka Formation of Phleger to be the upper- most formation of the Pogonip Group. They also considered the underlying dolomite to be part of the Pogonip, but I consider it to be part of the Upper Cambrian Tamarack Canyon Dolomite, a partial Nopah equivalent. In the New York Butte quadrangle, Mer- riam (1963b, p. 9) included units in his Pogonip Group that I believe are correlative with Upper Cambrian formations in the Independence quadrangle. As long as these differences of opinion exist as to what consti- tutes the Pogonip in the Inyo Mountains, it seems ad- visable to use the local term Mazourka Group in the Independence area. 10 STRATICGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA To the south and east, lithologic and faunal correla- tions of the upper formation of the Mazourka Group (Badger Flat Limestone) can be made with the upper formation of the Pogonip Group (Antelope Valley Limestone) with some degree of confidence. Correla- tion of the remainder of the Mazourka Group (Al Rose Formation) with the remainder of the Pogonip Group (Goodwin and Ninemile Formations) is much more tenuous but is proposed in the following discussion. This doubt about correlation with the lower part of the Pogonip Group is a further reason for retaining the local name Mazourka in this area. Exposures near the north boundary of the Independ- ence quadrangle are the northwesternmost outcrops of the Mazourka Group and thus are the north westernmost occurrence of rocks that can be lithologically correlated with the Pogonip. Farther northwest, the nearest fossiliferous Ordovician rocks are about 50 miles north- west of the Independence quadrangle. There, a thick section of pelitic hornfels, slate, marble, and calcareous quartz sandstone in the Mount Morrison pendant of the Sierra Nevada contains Early and Middle Ordovician graptolites (Rinehart and Ross, 1964, p. 18, 19, 21). Undoubtedly the time equivalent of the Mazourka Group is present in this thick section, but the change in facies from the Independence area to the Sierra Nevada precludes lithologic correlation. If the clastic-rich Al Rose Formation includes the equivalent of the Goodwin Limestone as well as the Ninemile Formation of the Pogonip Group, the Mazourka Group may reflect the beginning of the change from the dominantly carbon- ate strata of the Pogonip Group to the dominantly fine- grained clastic rocks of the same time interval in the Sierra Nevada. The Mazourka Group thus may be marginal between the eastern (carbonate) assemblage and the transitional assemblage of the Great Basin. AL ROSE FORMATION NAME AND DISTRIBUTION > The Al Rose Formation was named (Ross, D. C., 1963, p. B79) for exposures in the Independence quad- rangle. The formation crops out as a discontinuous belt from the north edge of the quadrangle south to the latitude of Independence. The lower contact is commonly a fault; along some segments of the outcrop belt the Al Rose is entirely faulted out. The belt ex- tends northward beyond the quadrangle boundary for only about half a mile; there it is cut out by granitic rocks in the Waucoba Mountain quadrangle. The southern extension of the belt is also terminated by a granitic intrusive southwest of the Betty Jumbo mine. About 14 miles southeast of the Independence quad- rangle, in the New York Butte quadrangle, however, similar rocks extend along the west face of the Inyo Mountains for about 3 miles, from the latitude of Alico north to the prominent granitic hill that juts out from the front of the range. These rocks are the brown- weathering unit referred to by Merriam (1963b, p. 9) as Pogonip B. Hornfelsed equivalent rocks are exposed about 3 miles north of the Willow Creek Camp, in the Waucoba Wash quadrangle. THICKNESS AND STRATIGRAPHIC RELATIONS No accurate determination of the thickness of the Al Rose Formation has been made because faulting and folding have almost every where disturbed this rela- tively incompetent unit. At the type section (see p. 44), the formation is about 400 feet thick. The Al Rose Formation probably lies conformably on beds of the Tamarack Canyon Dolomite. Although the contact is commonly disturbed, similar attitudes near the contact suggest conformity. LITHOLOGY The Al Rose Formation is a distinctive unit in the field. It weathers to shades of orange and red brown and is readily distinguished from the overlying and underlying gray-weathering units. The colorful out- crops are made up mostly of siltstone, mudstone, and shale but contain some chert. Very thin irregular bedding is typical. Generally silty medium-gray to bluish-gray, limestone is subordinate to the red-brown- weathering clastic rocks but in some places is the domi- nant rock type. The limestone occurs in elongate lenses that weather back as holes, or "eyes," in the outcrop. This feature, named "crepe structure" by McAllister (1952, p. 10), is particularly noticeable in somewhat hornfelsed exposures (fig. 54). Clastic quartz grains are common in the limestone layers. In some specimens the carbonate also is obviously clastic. Much of the limestone probably is calcarenite, but recrystallization has altered the original form of the calcite grains. A thin bed of edgewise conglomerate was noted near the base of the measured section (fig. 5B). E The uppermost member of the formation (unit 3 of the measured section) is much darker than the rest of the formation at many localities. It is also more regularly bedded in 1- to 2-inch-thick beds composed mainly of mudstone and siltstone (fig. 6). Gray lime- stone forms elongate lenses or thin interbeds. This unit, 52 feet thick at the measured section, is the same unit that Langenheim and others (1956, p. 2087) re- ferred to as unit 4 in their measured section. FIGURE 5.-Al Rose Formation. A, Outcrop of predominantly contact metamorphosed siltstone in which nodular beds and lenses of lime- stone weather back to "eyes" (darker in photograph). Outcrop is about 4,000 feet N. 10° W. of Bee Springs. B, Thin layer of edgewise conglomerate near base of measured section. FOSSILS, AGE, AND CORRELATION Graptolites and trilobites have been collected from several localities, mostly near the top of the formation in unit 3. These forms, which establish an Early Ordovician age for the formation, were identified by R. J. Ross, Jr. (written commun., 1962), as follows : USGS colln. D915-CO. Collected 5,000 feet east-southeast of Johnson Spring (California coordinates, zone 4; 2,274,200 E., 574,200 N.). Phyllograptus cf. P. ilicifolius Hall Didymograptus protobifidus Elles USGS colln. D916-CO. Collected near top of Al Rose Formation in Water Canyon (California coordinates, zone 4; 2,274,600 E., 570,500 N.). Didymograptus protobifidus Elles USGS colln. D917-CO. Collected about 5,000 feet N. 80 E. of SE cor. sec. 86, T. 11 S., R. 85 E. (California coordinates, zone 4 ; 2,270,800 E., 587,900 N.). Phyllograptus anna Hall ORDOVICIAN SYSTEM 11 USGS colln. D918-CO. - Collected 5,000 feet N. 75 E. of Johnson Spring (California coordinates, zone 4; 2,274,100 E., 576,400 N.). USGS colln. D811-CO. Collected about 5,000 feet N. 80 EK. of Johnson Spring (California coordinates, zone 4; 2,274,300 E., 575,900 N.). ‘ Didymograptus protobifidus Elles USGS colln. D1054-CO. Collected about 1,800 feet N. 55 E. of SE cor. see. 25, T. 11 S., R. 35 E. (California coordinates, zone 4 ; 2,267,000 E., 593,300 N.). Didymograptus artus Elles and Wood (1 specimen) Didymograptus protobifidus Elles (abundant specimens) Tetragraptus bigsbyi Hall Phyllograptus anna Hall Ampyxinid trilobite Olenid aff. Parabollinella Asaphid ?, indeterminate The following collection was made in 1964 and was kindly loaned to the U.S. Geological Survey for iden- tification and study by Wilfrid D. Davis, San Jose State College. R. J. Ross, Jr., made the identification. Davis 157. Collected about 700 feet southeast of I-524, about a mile north along strike from D98-CO. (California coor- dinates, zone 4; 2,273,300 E., 581,300 N.). Didymograptus protobifidus Elles Indeterminate agnostid trilobite Indeterminate trilobite thorax and pygidium According to R. J. Ross, Jr., the above-listed fossils, all from near the top of the Al Rose Formation, are of late Arenig age of zones 4 and 5 of Elles (1925), and probably correlate with trilobite zone "J" of the Garden City Formation in northeastern Utah (Ross, R. J., 1951), and with the Ninemile Formation. The following three collections are from rocks strati- graphically beneath the graptolite localities previously discussed. FiGUrE 6.-Al Rose Formation. of the formation. and shale. below knife. Graptolite-bearing uppermost member Thinly and relatively regularly bedded siltstone Note thin nodular beds and eyelike lenses of limestone Exposed about 1 mile east of Johnson Spring in canyon that trends northeast from Blue Stone tale mine. 12 STRATIGRAPHY OF PALEOZOIC FORMATIONS, USGS colln. D919-CO. Collected 2,500 feet N. 40 E. of SE cor. sec. 25, T. 11 S., R. 35 E. (California coordinates, zone 4; 2,267,200 E., 594,200 N.). Shumardia sp. Trilobite pygidium, Kainellid or apatokephelid, poorly preserved. USGS Colln. D920-CO. Collected from same area as D919 but stratigraphically somewhat higher (California coordinates, zone 4 ; 2,267,000 E., 594,000 N.). Trigonocerca? sp. (a large pygidium) USGS colln. D1024-CO. Collected from measured section near base (California coordinates, zone 4; 2,272,800 E., 586,000 N.). Indeterminate asaphid trilobite thorax and pygidium Collection D919 is from near the base of the Al Rose Formation and is tentatively correlated by R. J. Ross, Jr., with some part of the Goodwin Limestone of the Eureka, Nev., area. D920 is from about the middle of the formation and contains the same trilobite (T'rigono- cerca?) that is characteristic in R. J. Ross, Jr.'s, zone H (1951, p. 28) of the Garden City Formation of north- eastern Utah. The T'rigonocerca zone is also present in the lower beds of the Ninemile Formation at its type section (R. J. Ross, Jr., written commun., 1964). As was already noted, Pogonip B of Merriam (1963b, p. 9) in the New York Butte quadrangle is probably correlative with the Al Rose Formation. Examination of the section studied by McAllister (1952, p. 11) in the Quartz Spring area, only 30 miles to the east, sug- gests that units 4-7 of the Pogonip all are correlative with the Al Rose Formation. - Similar comparison sug- gests correlation with units "b" and "c" of the Pogonip Group in the Darwin area, 30 miles to the southeast (Hall and MacKevett, 1962, p. 8). At Bare Mountain, Nev., both east of Secret Pass and north of the Diamond Queen mine, the Pogonip Group could be separated into two units, the lower of which is similar to the Al Rose Formation. The lower unit would be the lower third of the Pogonip, which was described by Cornwall and Kleinhampl (1961) as commonly containing silty and cherty layers that give outcrops a yellowish-gray to brownish-gray color. At Bare Mountain the ratio of carbonate to clastic material is higher than in the Al Rose Formation, but the overall brownish color caused by the local abundance of silty layers gives a definite Al Rose appearance to the lower Pogonip. Based on its stratigraphic position and its relation to the fossiliferous Lead Gulch Formation of Late Cambrian age, the Al Rose Formation may include the equivalent of both the Goodwin and the Ninemile Formations of the Pogonip Group. This would mean a westward thickening of the brown-weathering clastic- rich Ninemile equivalent at the expense of the domi- nantly carbonate Goodwin. The section at Darwin tends to confirm this possibility if, as suggested by Hall and MacKevett (1962, p. 8), the lowest member of INDEPENDENCE QUADRANGLE, CALIFORNIA their Pogonip is actually equivalent to part of the Nopah Formation. BADGER FLAT LIMESTONE NAME AND DISTRIBUTION The Badger Flat Limestone was named (Ross, D. C., 1963, p. B80) for exposures in the Independence quadrangle. A belt of nearly continuous outcrop ex- tends from the Squares Tunnel area in Mazourka Can- yon nearly to the north boundary of the quadrangle. A small area of outcrop near the south edge of the Waucoba Mountain quadrangle (C. A. Nelson, written commun., 1961) is the northern limit of this formation. South of Squares Tunnel, discontinuous outcrops ex- tend as far south as the Betty Jumbo mine, where a granitic body cuts out the Badger Flat. Lithologically similar rocks in the correct stratigraphic position re- appear about 14 miles to the southeast, in the New York Butte quadrangle, along a strike length of about 3 miles on the east face of the Inyo Mountains. These beds were referred to by Merriam (1963b, p. 9) as Pogo- nip C. Small exposures having the same lithologic features are also present on the east side of the Inyo Mountains in a rubbly, poorly exposed area north of the Cerro Gordo mine, in Bonham Canyon (Merriam, 1963b, p. 9), and near the White Eagle tale mine, in the Waucoba Wash quadrangle. THICKNESS AND STRATIGRAPHIC RELATIONS The thickness of four relatively undisturbed meas- ured sections of the Badger Flat Limestone ranges from 511 to 586 feet. (See p. 44-45.) This range compares favorably with Phleger's (1933, p. 2) measurement of 550 feet for the upper unit of his Mazourka Formation. The thickness of the Badger Flat also suggests that the rocks described by Kirk (in Knopf, 1918, p. 35) as about 500 feet of fossiliferous argillaceous limestone were actually the Badger Flat Limestone. Langen- heim and others (1956, p. 2087) reported a thickness of 428 feet for that part of Phleger's Mazourka Formation which equates to the Badger Flat Limestone. Struc- tural thinning near the base of that section probably accounts for this lower figure. At several other locali- ties in the quadrangle, suspiciously thin measurements of the Badger Flat Limestone were also the result of faulting. The thickness of the Badger Flat Limestone (500-600 ft) is comparable to that of its presumed equivalents in the southern Inyo Mountains (600 ft, Pogonip C; Mer- riam, written commun., 1961), at Darwin (540 ft, Pogonip "d"; Hall and MacKevett, 1962, p. 8), and at Quartz Spring (485 ft, unit 8 of the Pogonip; McAl- lister, 1952, p. 11). In the Nevada Test site area, how- ever, the Antelope Valley Limestone (presumably equiv- alent to the Badger Flat) is 1,355 feet thick (Byers and others, 1961, p. C108). Beds of the Badger Flat Limestone rest conformably on strata of the Al Rose Formation. The contact is easily recognized because of the sharp color contrast between the blue-gray Badger Flat and the brown Al Rose, but sedimentation appears to have been continu- ous across the contact. LITHOLOGY Blue-gray-weathering outcrops and nodular, irregu- lar bedding characterize the Badger Flat Limestone, which stands out in bold contrast to the brown-weather- ing strata both above and below it. Though a consider- able variety of textures and structures are present in this unit, most subdivisions shown in the measured see- tions (gee p. 44-45) are somewhat artificial; the Badger Flat, though not homogeneous, is difficult to subdivide into members. Blue-gray limestone is the dominant rock type in the formation, but the association of this limestone with irregular lenses and beds of light-gray-, orange-, and red-brown-weathering silty and marly beds (fig. 7) is the most diagnostic feature of this formation. Though the term "limestone" is used in describing the measured sections, almost all specimens studied in thin section contained abundant scattered quartz grains, commonly in an obviously clastic calcite matrix (fig. 8). The clastic nature of this unit is also shown by the fragmen- tal nature of the abundant fossils. Much, if not most, of the limestone could more precisely be called calcarenite or calcilutite. Ficurs 7.-Badger Flat Limestone. Darker areas are blue-gray silty limestone); lighter areas are yellowish- to brown-weathering silty and argillaceous layers. This extreme irregularity in bedding is common in the formation and produces picturesque mottled outcrops. - Ex- posed near top of unit 5 of the measured section. 212-460 0-66 2 ORDOVICIAN SYSTEM 13 FIGURE 8.-Badger Flat Limestone. Photomicrograph of calcarenite from prominent east-trending ridge south of Barrel Springs ; quartz (Q), calcite (C). Largest quartz grains are about 0.1 mm in diameter. Upper : plane-polarized light. Lower: crossed nicols. The presence of irregular lenses composed of different proportions of quartz and calcite is accentuated on weathered surfaces, where the more silty layers weather out in relief as spines, ridges, and rather exotic irregu- lar patterns. Black chert, both as nodules and as nod- ular beds, is locally abundant, particularly in the lower part of some sections. In the northern part of the outcrop area (see p. 45), thin beds of fairly pure but somewhat calcareous quartz- ite are present near the top of the formation. These beds seem to be the forerunners of more abundant quartzite in the overlying formation. FOSSILS, AGE, AND CORRELATION The Badger Flat Limestone is assigned a Middle Ordovician age on the basis of fossils. In an interval from 100 to 200 feet below the top of the formation, gastropods as much as 3 inches across are locally abundant enough to be a mappable feature of the for- 14 STRATIGRAPHY OF PALEOZOTIC FORMATIONS, mation. Elsewhere (generally lower in the formation) brachiopods, trilobites, and cephalopods have been col- lected. Pelmatozoan fragments are abundant through- out the formation ; small concentric structures as much as half an inch across, thought to be the algal form Girvanella, are also present. Large gastropods from one locality, and probably representative of the widespread gastropod zone, were identified by E. L. Yochelson (written commun. 1960) as follows: USGS colln. D731-CO._ Collected about 1,000 feet N. 30° W. of NE cor. see. 8, T. 13 S., R. 36 E. (California coordinates, zone 4 ; 2,270,300 E., 546,000 N.). Palliseria robusta Wilson Yochelson reported that this is a guide fossil to the Whiterock Stage of Cooper (1956), which is of earliest Middle Ordovician age, and that this species is found in the Antelope Valley Limestone of the Pogonip Group in Nevada. All the following fossils, except as noted, were iden- tified and reported by R. J. Ross., Jr. (written commun, 1960, 1961, 1962) : USGS colln. D750-CO. Collected on east side of Mazourka Canyon about 2.4 miles north of Johnson Spring (California coordinates, zone 4 ; 2,270,300 E., 587,300 N.). Orthambonites? mazourkaensis (Phleger) Orthambonites? patulus (Phleger) USGS colln. D752-CO. Collected on east side of Mazourka Canyon about 1.5 miles southeast of Badger Flat (California coordinates, zone 4 ; 2,269,700 E., 589,100 N.). Orthambonites? patulus (Phleger) Two trilobite pygidia-neither identifiable generically, but one obviously a bathyurid. USGS colln. D753-CO. Collected on east side of Al Rose Can- yon, south of Badger Flat (California coordinates, zone 4; 2,266,300 E., 592,800 N.). Orthmbonites? cf. 0. mazourkaensis Phleger Unidentifiable gastropods Isotelus-like trilobite Unidentifiable brachiopod, possibly an Orthidiell@ USGS colln. D921-CO. Collected 4,000 feet N. 45° E. of SE cor. see. 36, T. 11 S., R. 35 E. (California coordinates, zone 4; 2,269,000 E., 589,400 N.). Age: probably Middle Ordovician. Asaphid with minimum of six thoracic segments Pygidium but no cephalic parts Pterygometopid (aff. Achatella) (cranidium) Pygidium, digitate, possibly pliomerid, possibly dalmani- tid USGS colln. D922-CO. Collected from measured section BF-4 about 420 feet below top (California coordinates, zone 4; 2,271,800 E. 585,400 N.). Pseudomera? sp. (pygidium only) Cystid plate, showing hydrospires Fragment of cephalopod, unidentifiable USGS colln. D1002-CO.- Collected about 20 feet below top of measured section BF-4 (California coordinates, zone 4; 2,271,300 E., 585,100 N.). Sponge? Cystid plates Bryozoans, two genera but indeterminate INDEPENDENCE QUADRANGLE, CALIFORNIA USGS colln. D1003-CO._ Collected about 190 feet below top of measured section BF-4 (California coordinates, zone 4; 2,271,500 E., 585,200 N.). Sponges Rhysostrophia nevadensis Ulrich and Cooper Gastropods USGS colln. D1004-CO. Collected from about 230 feet below top of measured section BF-4 (California coordinates, zone 4; 2,271,500 E., 585,200 N.). Calycocoelia sp. Orthambonites patulus (Phleger) Orthambonites? cf. O. mazourkaensis (Phleger) Rhysostrophia occidentalis Ulrich and Cooper Rhysostrophia n. sp. USGS colln. D1006-CO._ Collected about 300 feet below top of formation about 4,500 feet east of J ohnson Spring (Cali- fornia coordinates, zone 4; 2,273,800 E., 575,000 N.). Orthambonites? cf. 0. mazourkaensis (Phleger) Conodonts, undetermined USGS colln. D1007-CO. - Collected about 350 feet below the top of formation about 4,500 feet east of Johnson Spring (Cali- fornia coordinates, zone 4; 2,273,800 E., 575,000 N.). The following cephalopods were identified by R. H. lower. Reudemannoceras sp. Rossoceras sp. : 1-550. - Collected about 4,000 feet N. 60° E. of SE cor. see. 36, T. 11 S., R. 35 E. (California coordinates, zone 4; 2,269,300 E., 588,700 N.). Identified by W. A. Oliver. Massive favositoid coral On the basis of these fossils, R. J. Ross, Jr. (1964, p. 86, fig. 9), assigned the Badger Flat Limestone to the Whiterock Stage and part of the overlying Marmor Stage of Cooper (1956). Ross considered the Badger Flat Limestone to be essentially equivalent to the Ante- lope Valley Limestone of the Pogonip Group as de- scribed in the Eureka district of Nevada (Nolan and others, 1956, p. 28). Greife and Langenheim (1963, p. 564), on the basis of studies of brachiopods and sponges from that part of Phleger's Mazourka Formation that I refer to the Badger Flat Limestone, suggested that "Faunal ele- ments described in this study indicate deposition start- ing in the Anomalorthis zone and possibly extending into the Rhysostrophia zone of Cooper's Whiterock stage." The Badger Flat Limestone is probably correlative both with unit 8 of the Pogonip in the Quartz Spring area (McAllister, 1952, p. 11) and with unit "d" of the Pogonip in the Darwin area (Hall and MacKevett, 1962, p. 8). In both areas, the upper part of the Pogo- nip Group like the Badger Flat Limestone, is blue-gray, irregularly bedded, contains abundant silty material, and bears a distinctive gastropod zone. At both Dar- win and Quartz Spring, however, the carbonate is almost entirely dolomite, whereas that in the Badger Flat is virtually all calcite. ORDOVICIAN SYSTEM 15 1 BARREL SPRING FORMATION | | The flame Barrel Spring Formation was proposed by Phleger (1983, p. 5) for "a succession of quartzites, impure limestones, and argillaceous shales of Middle Ordovician age, in the Inyo Mountains." Phleger des- ignated the type section "in the south fork of Mexican Canyon, which is the second canyon north of Barrel Spring Canyon." On the present topographic map, Barrel Spring Canyon is called Water Canyon, and Mexican Canyon (not named on the map) is the first canyon ‘ north of Bonanza Gulch. Langenheim and others (11956, p. 2091) referred to Mexican Gulch, which is the same as Phleger's Mexican Canyon. The Barrel Spring Formation crops out as a thin but widespread and easily recognizable unit from the Squares Tunnel area north to Badger Flat. About a mile northwest of Badger Flat, the formation is cut ' out by faulting, but it reappears for a short distance along the south margin of the Waucoba Mountain quadrangle, which is its northernmost occurrence. South of the Squares Tunnel area the formation is dis- continuously exposed in fault blocks as far south as the Betty Jumbo mine area, where granitic rocks interrupt the belt of outcrop. In the New York Butte quad- rangle, Merriam (1963b, p. 10) described similar beds along the west side of the Inyos and in San Lucas Can- yon; these rocks are the basal beds of the Eureka Quartzite. Beds of the Barrel Spring Formation are also exposed in a structurally complex area near the White Eagle tale mine, in the Waucoba Wash quadrangle. On Badger Flat and to the northwest, as well as near the Snowcaps mine near the mouth of Mazourka Can- yon, the Barrel Spring Formation is too thin to be mappedgeparately and is therefore mapped with the NAME AND DISTRIBUTION overlying Johnson Spring Formation. THICKNESS AND STRATIGRAPHIC RELATIONS The thickness of the Barrel Spring Formation in 10 sections along its outcrop belt ranges from 70 feet in Willow Springs Canyon to 206 feet about half a mile south of Barrel Springs (pl. 3). At the type section the measured thickness is 157 feet, but Phleger (1933, p. 5) reported 130 feet and Langenheim (1956, p. 2091) measured only 100.5 feet, presumably for the same section. The differences lie chiefly in the reported thickness of the upper shale unit. The Barrel Spring Formation thins northward and is only 100 feet thick at the northernmost measured section south of Badger Flat. Farther north it is only a few feet thick in some outcrops, possibly because faulting has disturbed the section. The formation also thins southward, as it is about 70 feet thick at the southern- most measured section. - The section of similar lithology in the New York Butte quadrangle is only 40-75 feet thick according to Merriam (1963b, p. 10). Near the White Eagle mine, in the Waucoba Wash quadrangle, the formation is, at most, 100 feet thick. It thus appears to be a lens in the Inyo Mountains that is thickest near Barrel Springs and thins to the north, east, and south. The Barrel Spring Formation comformably overlies the Badger Flat Limestone. At the base of the Barrel Spring is commonly an impure quartzite, in places con- tact metamorphosed to calc-hornfels, so that the contact between these rocks and the blue-gray carbonate beds of the underlying Badger Flat Limestone is readily map- pable. North of the type section, however, the distinc- tion between the two formations is not every where obvious. LITHOLOGY At the type section of the Barrel Spring Formation, Phleger (1933, p. 5) recognized three units : a quartzite at the base, an overlying impure limestone, and a cap- ping argillaceous shale. (See section BS-6, p. 46.) Langeheim and others (1956, p. 2091) noted the same three members a mile north of the type section and in two intervening canyons. North and south of this belt the three-fold division cannot readily be made. How- ever, the lower two units described by Phleger together make up a light-colored lower member at most Barrel Spring sections and can be distinguished from a darker colored upper unit (fig. 9). The lower member is absent at the north edge of the area and in the Waucoba Mountain quadrangle, to the north; it must also thin and disappear to the south, for it was not reported in the Barrel Spring equivalent by Merriam (1963b) and does not appear to be present in the Waucoba Wash quadrangle to the east. Phleger's upper unit, the argillaceous shale, which I informally call the upper member, has been locally dif- ferentiated from the lower two units combined (pl. 1), but generally the thinness of the Barrel Spring pre- cludes showing this subdivision on the geologic map. LOWER MEMBER The lower member, a light-colored limestone, impure quartzite, and siltstone unit, comprises the lower two units of Phleger's type section. The lower member is not present in section BS-8, but limestone beds within the upper member are probably tongues of the lower member, which is notably variable and lenticular. The member is mostly carbonate (fig. 10), but it con- tains much silt and many sand-size quartz grains. The composition ranges from almost pure carbonate to rela- tively pure quartzite, which is uncommon. The lower 16 STRATIGRAPHY OF PALEOZOIC FORMATIONS, FIGURE 9.-Barrel Spring Formation (Obs) in south side of ridge north of the Blue Stone tale mine. tion (Os) and the Badger Flat Limestone (Obf). member appears to be particularly susceptible to contact metamorphism, for diopside, seapolite, antigorite, trem- olite, and phlogopite(?) are mixed with the carbonate and the quartz. - Calcite is the dominant carbonate min- eral, although dolomite is locally abundant, as in sections BS-5 and BS-2. The magnesium-bearing calc-horn- fels minerals show that the dolomite was widespread and common. FiGurE 10.-Barrel Spring Formation. Exposure of the middle lime- stone member at the type section in Mexican Gulch. INDEPENDENCE QUADRANGLE, CALIFORNIA Also shown are the Johnson Spring Forma- Section BS-7 was measured along this ridge. In the silty limestones the quartz grains range from subangular to well rounded and from 0.01 to 0.1 mm in diameter. Sand-size particles are also locally abun- dant, but much of the rock that superficially looks like quartzite is actually calc-hornfels or calcareous silt- stone. A typical sample of Phleger's "impure quartz- ite" from the type section, for example, comprises about 10 percent tremolite and about 90 percent rock composed of virtually equal amounts of 0.03 to 0.06 mm quartz and calcite clasts; the rock, therefore, is actually a calcareous siltstone. Clastic calcite probably was very abundant originally, but recrystallization and formation of calc-hornfels minerals have destroyed the original clastic grains in most places. In some places the calcarenite contains well preserved rounded calcite grains as large as 1-2 mm. One calcarenite specimen from unit 2 of section BST is what might be termed a "microconglomerate" ; rounded calcite grains as much as 1.5 mm in diameter are scattered through a dense groundmass mostly com- posed of 0.01-0.1 mm calcite fragments and quartz grains. UPPER MEMBER The upper member is the same as the "argillaceous shale" of Phleger (1933, p. 5) and units 9, 10, and 11 of Langenheim and others (1956, p. 2086). It is a dis- ORDOVICIAN SYSTEM 17 Blocky red-brown-weathering Looking north 11.-Barrel Spring Formation. shale and mudstone in upper part of the formation. in canyon south of ridge shown in figure 9. tinctive red-brown-weathering shale, mudstone, and siltstone unit that forms an easily recognizable dark outcrop belt (fig. 9). Being somewhat less resistant than the bounding units, it is poorly exposed, but the red-brown rubbly slopes are obvious. Although the member is generally "soft," some outcrops are blocky and bold (figs. 9, 11), particularly where the rocks have been baked and metamorphosed. Outcrops of this unit are variously shale, mudstone, or siltstone (see p. 45-47), which are locally phyllitic. Thin quartzite layers are less common. Carbonate layers are rare, and the clastic rocks are not calcareous. Individual specimens show some difference in color and texture, but the unit in outcrop appears homogeneous. T'wo specimens of dark shale from the upper mem- ber were collected east of the Bluestone tale mine and submitted for semiquantitative spectographic analysis. The following results were reported (J. D. Vine, written commun., 1963) (only one number is shown where both analyses gave the same trace ele- ment amount) : Ti, 0.7; Mn, 0.005; B, 0.02, 0.03; Ba, 0.3, 0.1; Cr, 0.01, 0.015; Cu, 0.002, 0.003; Ga, 0.0015, 0.003; La, 0.005, 0; Nb, 0.003; Ni, 0.0015, 0.00015; Pb, 0.002, 0.0015: Sc, 0.0015; S8r, 0.01; V, 0.015, 0.02; ¥, 0.002, 0.0015; Yb, 0.0002; Zn, 0.05, 0; and Zr, 0.1, 0.07. Metamorphism is reflected locally by the presence of mica and, possibly also, chlorite. Blocky, some- what harder outcrops are also evidence of meta- morphism. - In some places sericitic hornfels is present that is considerably lighter colored than the original rock. Occurrences of mica and chlorite are scattered, however, so that superficially the rocks look unaffected. The rocks of the upper member are composed chiefly of rounded to angular quartz fragments from 0.01 to 0.1 mm in diameter or larger. Iron oxide is a common constituent and is the cause of the distinctive red-brown- weathering color. Dark carbonaceous material is also abundant locally. The original presence of argilla- ceous material is reflected in the mica and chlorite. FOSSILS, AGE, AND CORRELATION Brachiopods, trilobites, bryozoans, and graptolites are present, but not common, in the lower part of the upper member. Fossils are also present near the base of the lower member, but these are generally highly silicified and too poorly preserved to be identified. On the basis of the identified fossils, the Barrel Spring Formation is regarded as of Middle Ordovician age. The following fossils were identified by R. J. Ross, Jr. (written commun., 1959, 1961, 1962) : USGS colln. D924-CO. Collected about 70 feet below the top of the type section in Mexican Gulch (California coordinates, zone 4 ; 2,273,900 E., 571,200 N.). Isotelus (?) spurius Phleger This species has been reported only from the Barrel Spring Formation. USGS colln. D1005-CO. Collected about 75 feet below the top of the type section in Mexican Gulch (California coordi- nates, zone 4 ; 2,273,900 E., 571,200 N.). Orthambonites cf. 0. decipiens (Phleger) Remopleurides sp. Dicellograptus seaxtans USGS colln. D1017-CO. Collected about 60 feet below top of the type section in Mexican Gulch (California coordinates, zone 4 ; 2,274,000 E., 571,200 N.). Orthambonites decipiens (Phleger) Orthambonites sp. Valcourea cf. V. plana Cooper Valcourea sp. Bryozoans, indeterminate Lonchodomas sp. Ampyz (?) sp. Isotelus (?) spurius Phleger I-1579. - Collected from rubbly float, but almost in place, in the SE sec. 25, T. 11 S., R. 35 E., just south of Badger Flat (California coordinates, zone 4; 2,264,800 E., 594,400 N. No fossils have been collected from the Barrel Spring Formation north of this locality. Remopleurides I-7. Collected 3,300 feet northeast of Barrel Springs. Orthid brachiopod, possibly Hesperorthis I-1. Collected about 10,000 feet N. 10° E. of Johnson Spring. Trilobite pygidium 1-232. Collected 750 feet northeast of SE cor. see. 25, T. 11 S., R. 35 E. This is the only collection from the lower mem- ber and is from near the base of the member. Brachiopods Bryozoans Trilobites Pelmatozoan columnals This material is so highly silicified that the specimens are poorly preserved and cannot be properly prepared. 18 STRATIGRAPHY OF PALEOZOIC FORMATIONS, The following collections, made in the summer of 1964 by Wilfrid D. Davis, San Jose State College, were kindly loaned to the U.S. Geological Survey for identi- fication and study. The identifications were made by R. J. Ross, Jr. Davis 169. - Collected about 1,500 feet east-southeast of SE cor. sec. 25, T. 11 S., R. 35 E. (California coordinates, zone 4; 2,267,100 E., 591,750 N.). Hesperorthis cf. H. dubia Cooper Davis 170. Collected about 2,000 feet southeast of SE cor. see. 25, T. 11 S., R. 35 E. (California coordinates, zone 4; 2,267,500 E., 591,200 N.). Hesperorthis cf. H. dubia Cooper Rafinesquina-like species Davis 173. Collected about 3,000 feet southeast of SE cor. sec. 25, T. 11 S., R. 35 E. (California coordinates, zone 4; 2,267,900 E., 590,600 N.). Hesperorthis cf. H. dubia Cooper Plaesiomys? sp. Davis 176. Collected about 4,000 feet northeast of SE cor. see. 36, T. 11 S., R. 35 E. (California coordinates, zone 4; 2,268,900 E., 589,300 N.). Isotelus sp. (A much larger specimen than is common for I. spurius) Davis 158. Collected about 9,300 feet southeast of SE cor. sec. 36, T. 11 S., R. 35 B. (California coordinates, zone 4; 2,273,000 E., 580,900 N.). Isotelus spurius Phleger Valcourea sp. Dicellograptus? sp. Davis 180. Collected from bottom of canyon just east of Blue Stone tale mine (California coordinates, zone 4; 2,273,500 E., 575,000 N.). 4 Orthambonites decipiens (Phleger) Isotelus spurius Phleger Davis 180A. Collected half way up ridge southeast of Davis 180 (California coordinates, zone 4; 2,273,600 E., 574,600 N.). Isotelus sp. (large) Phleger (1933, p. 6) tentatively referred the Barrel Spring to the Trenton. On the Ordovician correlation chart (Twenhofel, 1954, following p. 298) the forma- tion was questionably assigned to the Trentonian Stage, but Twenhofel thought that it might be of Richmond age, and Cooper (in Twenhofel, 1954, p. 263) thought that it might extend down to include beds of Black River age. Langenheim and others (1956, p. 2092) believed the Barrel Spring to be Mohawkian (Black River and Trenton) on the basis of their faunal collec- tion, which contained about the same forms as Phleger's original collection. The Dicellograptus sextans in collection D1005-CO establishes the Barrel Spring Formation as the equiva- lent of zone 9 or 10 of Elles (1925), or lower Caradoc. This is probably equivalent to the Porterfield or Wilder- ness Stage (Ross, R. J., and Berry, 1963, table 1) and to part of the Black River. Langenheim, and others (1956, p. 2094) used the term Eureka Group to include the Barrel Spring Formation INDEPENDENCE QUADRANGLE, CALIFORNIA and the overlying unit that was later named the Johnson Spring Formation by Pestana (1960, p. 862). As is ex- plained later (p. 24), I have chosen not to use the name Eureka in this area, but I feel that Langenheim and his associates were correct in correlating the Barrel Spring Formation with the lower part of the Eureka Quartzite. Exact lithologic equivalents of the Barrel Spring, and in particular of the upper member, do not seem to be present in nearby sections of the Eureka south and east of the Inyo Mountains, but probable correlatives are found. On a spur east of the Viking mine, in the Darwin quadrangle (California coordinates, zone 4; 2,381,000 E., 372, 750 N.), for example, about 165 feet of sandy and silty dolomite and limestone is present above un- doubted Antelope Valley beds of the Pogonip Group that look similar to the Badger Flat Limestone, and be- low massive quartzite that is undoubtedly Eureka Quartzite. Very likely this interval contains (or is) the Barrel Spring equivalent. In the Panamint Butte quadrangle about 214 miles south-southeast of Panamint Butte (California coordi- nates, zone 4; 2,489,000 E., 393,800 N.), about 130 feet of dolomite, siltstone, and quartzite is present above limestone beds assigned to the Antelope Valley Lime- stone and below the Eureka Quartzite. These beds are in part red and orange weathering and also may repre- sent the Barrel Spring interval. In the Dry Mountain quadrangle about 114 miles north of Teakettle Junction (California coordinates, zone 4; 2,429,000 E., 533,000 N.), about 175 feet of silty and sandy dolomite forms a transition zone between the Pogonip Group and the Eureka Quartzite. This thin- bedded, yellow- to orange-weathering zone is currently assigned to the Pogonip (J. F. McAllister, written commun., 1962), but its thickness and stratigraphic position suggest that it may be a Barrel Spring correla- tive, although it does have a much higher percentage of carbonate. McAllister (written commun., 1962) also noted a similar 170-foot-thick section of transi- tional beds north of Pyramid Peak in the Funeral Mountains east of Death Valley. There reddish- brown-weathering silty and shaly beds and some dolo- mite are present in the lower part of the Eureka Quartzite. The lower part of the Eureka Quartzite at the Ne- vada Test Site, Nev., comprises 35 feet of thin-bedded orange- to brown-weathering limestone underlain by 60 feet of brown-weathering indistinctly thin-bedded quartzite (Byers and others, 1961, p. C108). This interval is a Barrel Spring equivalent (Ross, R. J., 1964, p. C18, colln. D680-CO). Interestingly enough, two of the fossil forms (Valcourea, Lonchodomas) in ORDOVICIAN SYSTEM 19 the limestone there are the same as forms from the shaly upper member of the Barrel Spring Formation. Near the west edge of the Specter Range quadrangle in Nevada, about 1 mile north of U.S. Highway 95, red- weathering thin-bedded quartzite, siltstone, and some shale that also may be the Barrel Spring equivalent are present near the base of the Eureka Quartzite. These sections east of the Inyo Mountains, though probable correlatives of the Barrel Spring, lack the distinctive red-brown shaly upper member. Most are dominantly carbonate, but this would be expected owing to the seemingly regional trend of increasing carbonate south and east of the Independence quadrangle. How- ever, shaly beds reappear in the basal part of the Eureka Quartzite in the Eureka area of eastern Nevada. Kirk (1933, p. 28) noted that "below the quartzite proper, as at Lone Mountain, sandy calcareous argillites were found." He also noted (1933, p. 32-33) that about 250 feet of mixed carbonate and quartzite in the Ante- lope Range about 30 miles southwest of Eureka contains Remoplewrides and Valcourea, which are also present in the Barrel Spring Formation. These beds were studied and named the Copenhagen Formation by Mer- riam (19632, p. 25), who suggested that the formation is a local lateral equivalent of the lower part of the Eureka Quartzite and that it is correlative with the Barrel Spring Formation. North and west of the quadrangle, the stratigraphic equivalent of the Barrel Spring Formation may well be present in the fossiliferous Ordovician section in the Mount Morrison roof pendant of the Sierra Nevada (Rinehart and Ross, 1964, p. 17-23), and in the Palmetto Formation in Nevada (Ferguson and others, 1954). In these areas, however, the exposed Ordo- vician sections are so different from those in the Inyo Mountains that recognition of any of the Inyo forma- tions is virtually impossible. The appearance of dark fine-grained clastic rocks of the Barrel Spring Forma- tion in the lower part of the Eureka Quartzite interval is probably a forerunner of these markedly different Ordovician rocks to the north and west. JOHNSON SPRING FORMATION NAME AND DISTRIBUTION The Johnson Spring Formation was named by Pes- tana (1960, p. 862) for exposures along the east side of Mazourka Canyon. It is a lateral equivalent of at least part of the widespread Eureka Quartzite. The relation of the Independence rocks to this widely known formation is discussed on page 24. A thin belt of the Johnson Spring Formation extends virtually unbroken except for minor cross faults from the vicinity of Barrel Springs north to Badger Flat. Northwest of Badger Flat the thin belt is faulted out, but it makes a brief reappearance along the south mar- gin of the Waucoba Mountain quadrangle, the north- ernmost known occurrence of the formation. - South of Barrel Springs the outcrop belt is discontinuous owing to faulting, but segments of the formation occur as far south as the Betty Jumbo mine, the southernmost appearance of the formation. The nearest outcrops of stratigraphically equivalent beds to the southeast in the New York Butte quadrangle are assigned to the Eureka Quartzite (Merriam, 1963b, p. 9). Directly east of the area, in the Waucoba Wash quadrangle, equivalent beds are found in a small area west of the Willow Creek Camp. The Johnson Spring Formation is thus virtually limited in its distribution to the Independence quad- rangle. Pestana (1960, p. 862) wisely gave-it a local name to point out its lithologic variation from the Eureka Quartzite. THICKNESS AND STRATIGRAPHIC RELATIONS The thickness of the Johnson Spring Formation 13 measured sections ranges from 398 feet near the south end of the outcrop belt to 114 feet near Badger Flat. Thinner sections were measured northwest of Badger Flat (one is only 39 feet thick), but these are suspect owing to faulting. The type section, which is about midway in the outcrop belt, is 210 feet thick ; this figure is fairly close to the average thickness of about 225 feet for the formation. In general, the Johnson Spring thins to the north (pl. 3), but it is difficult to say how much of this thinning is due to faulting and how much is due to variation in original thickness. Several sub- units of the Johnson Spring are notably lenticular. The sections given in "Stratigraphic Sections" (p. 47- 53) were measured in areas where the rocks were least disturbed. Most variation in thickness is due to varia- tions in original depositional thickness, but the subtle effects of strike faulting, such as those observed in the northern part of the area, cannot be completely dis- missed any where along the outcrop belt. The beds of the Johnson Spring Formation con- formably overlie the Barrel Spring Formation. The readily mappable contact between the dark-colored shale of the underlying Barrel Spring and the light- colored basal quartzite of the Johnson Spring Forma- tion is abrupt, but no break in deposition is noticeable. LITHOLOGY The Johnson Spring Formation represents a marked variation from its partial stratigraphic equivalent, the Eureka Quartzite. Good exposures along a strike length of some 15 miles, in steeply dipping but gener- 20 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNTA 400' - 300' ~ 200 -A I"nullllllmull er 100 - JS-13 JS-12 JS-11 JS-10 JS-9 JS-8 ||I||||||m|||||u||||||||||||||||||||||||Il“ ut. N Sme /// / "Eureka-like" y // quartzite SEA LEVEL < f f ; f f 4.£.4. JS-7 pau ** / |\\ S t- 100' SEA LEVEL JS-6 J§$-1 FicurB 12.-Variation in thickness and lithology of Johnson Spring Formation. ally unfaulted sections, provide an excellent opportunity to detail these variations. The characteristic rock type of the formation is white to gray orthoquartzite, although in some sections a combination of limestone, dolomite, siltstone, and shale is dominant. In addition to the decrease in thickness to the north, the percentage of quartzite also decreases in this direc- tion. From sections JS-1 to JS-10 (see p. 47-52) the percentage of quartzite decreases from 85 percent to 20 percent (fig. 12). Northward, in sections JS-11, -12, and -13, the trend is reversed, and quartzite percentage increases to 75 percent. The subunits of the Johnson Spring, and most not- ably the quartzites, are lenticular. One of the best ex- amples of this lenticularity is shown by the uppermost quartzite. It is 4 feet thick at section JS-10 and ex- pands to 70 feet at JS-11 along a strike of about 1 mile. Just south of JS-10 the uppermost quartzite seems to lens out completely, but it reappears and continues southward. . In this same area the basal quartzite also thickens markedly northward. On the composite cross section (pl. 3) it is apparent that other subunits are also lenticular, particularly the coral limestone lens that extends from sections JS-T to JS-10. Despite the len- ticularity, in most outcrops a distinctive light-colored quartzite at the top of the formation, and another at the base readily identify and delimit the Johnson Spring Formation. The abundance (or even the dominance) of thin- bedded limestone, dolomite, siltstone, and shale and the preservation of marine fossils leave little doubt about the marine origin of the Johnson Spring Formation. Some of the more massive quartzites, particularly in the upper part of the formation, may very possibly be subaerial deposits; but their intimate association and interbedding with marine beds means that if they were subaerial they were deposited as beach sands. Although the Johnson Spring Formation is easily mapped because of its distinctive quartzite cap and base, it nevertheless is one of the more lithologically variable formations in the quadrangle. The units shown in the composite section (pl. 3) are all mappable; if a large enough scale had been used they could have been delineated to show in plan view the lenticularity that is evident in cross section (pl. 3.) The following mem- bers, in descending order, are distinguishable: Upper quartzite Upper dolomite Coral limestone Middle quartzite Lower limestone Crinoidal dolomite Mixed lithology Lower quartzite No one section exposes all these units, and some mem- bers are probably laterally discontinuous equivalents of the same unit. Some units, as defined, are a com- posite of different lithologies and may contain several small subunits which further accentuate the variabil- ity of the formation. LOWER QUARTZITE The light-colored lower quartzite is present through- out the area and stands in contrast with the underlying dark-colored shale of the Barrel Spring Formation. The quartzite ranges in thickness from about 10 feet to 110 feet and is thickest at the northernmost measured section (JS-13). The quartzite is mostly light colored and pure at the south end of the area, but elsewhere it commonly weathers yellow to red brown and has calcareous cement (fig. 134). Characteristically the beds are thin, and crossbedding is obvious in some outcrops. - Seolithus is ORDOVICIAN SYSTEM 21 B FIGURE 13.-Johnson Spring Formation. A, Thin-bedded yellowish- weathering calcareous quartz sandstone and quartzite. Pure quartz ite layer below hammerhead; most other beds have some calcareous cement. Exposed about 40 feet above base of formation near section JS-13. B. Scolithus in quartzite showing hackly fracture. Exposed about 1 mile west-northwest of the Betty Jumbo mine in unit 7 of measured section JS-1. found locally and is particularly abundant in unit 7 of section JS-1 (fig. 13B and p. 48). The quartz grains are as much as 0.75 mm in diam- eter and are generally well rounded. In some speci- mens these larger grains are scattered through a mass of less well rounded grains from 0.1 to 0.2 mm in size. The quartzite in some outcrops is generally coarser grained than that higher in the formation. Some speci- mens have calcite cement, and others contain grains of tremolite and diopside, which attest to the original pres- ence of carbonate cement. Beds a few inches thick of dark-colored shale or siltstone are also present. At the type section the lower quartzite comprises Pestana's (1960, p. 863) units 1 and 2, which are com- bined as unit 1 in my description of the same section. (See section JS-7T, p. 50.) MIXED LITHOLOGY Immediately overlying the lower quartzite in the central part of the area, but lensing out both to the north and south, is a mixed sequence of limestone, dolo- mite, siltstone, calcareous quartz sandstone, shale, and quartzite. Its maximum thickness is about 60 feet, near the type section (JS-7). The unit as a whole weathers dark in contrast to the light-colored quartzites above and below. Medium- to dark-gray carbonate rocks and red-brown silty and shaly beds are interspersed with thin beds of light- colored sandstone and quartzite. The limestone is commonly thin bedded and nodular and contains coral and other fossil fragments. In see- tion JS-8, unit 4, the limestone has grayish-red lenses that give the rock an overall purplish cast. This par- ticular rock type commonly contains abundant corals. Most of the dolomite is thick bedded, but some is thin bedded and (or) has thin silty and sandy layers; locally, it contains pelmatozoan fragments. Owing to differ- ent proportions of quartz and dolomite grains, the unit ranges from clastic dolomite (calcarenite) to sandstone. Some specimens comprise well-rounded quartz grains, as large as 0.5 mm, in a matrix of carbonate or cale- hornfels and are lithologically much like the Ordovician rocks of the Mount Morrison roof pendant of the Sierra Nevada (Rinehart and Ross, 1964, p. 15). In some places laminated calc-hornfels has formed from the car- bonate layers, as in section J S-5. The section of mixed lithology comprises units 3-9 of Pestana's type section (1960, p. 863). In my modified version of the same section (JS-7), units 2-6 make up the mixed lithology. CRINOIDAL DOLOMITE At the north end of the area, dolomite rich in pelma- tozoan fragments overlies the section of mixed lithology. The crinoidal dolomite ranges in thickness from about 25 to 40 feet. The presence of limy and silty rocks both above and below the crinoidal dolomite in section JS-11 and above the crinoidal dolomite in section JS-12 sug- gests that the dolomite is a lateral variant of the mixed- lithology unit. The unit is made up of medium-gray to medium- dark-gray thin- nodular-bedded dolomite containing abundant pelmatozoan fragments and some brachiopod and coral fragments. The fragmental appearance of this rock is borne out in thin sections. Clasts of fos- sil material as much as 3 mm across are liberally scat- tered through a matrix of fragmental dolomite grains of various sizes but all much less than 1 mm in diameter. P4. STRATIGRAPHY OF PALEOZOIC FORMATIONS, This unit is truly a calcarenite. The crinoidal dolomite is not present at the type sec- tion ; it was noted only from section JS-10 north to see- tion JS-18. At section JS-13, where the upper quartz- ite bed of the formation is missing, the distinctive dolo- mite, rich in fossil fragments, is in contact with the over- lying Ely Springs Dolomite. LOWER LIMESTONE South of the type section and extending from section JS-5 to the southern limit of exposure of the formation, the mixed-lithology unit is overlain by a unit composed mostly of limestone, which is probably also a lateral variant of the mixed-lithology unit. The thickness of the lower limestone is extremely variable but reaches a maximum of 56 feet. To the south the limestone splits into three units that are interbedded with quartzite, and at section JS-1 it comprises only two thin limestone (and calc-hornfels) units; probably the lower limestone lenses out a short distance farther south. The lower limestone is made up of medium-gray to medium-dark-gray thin- nodular-bedded limestone with irregular lenses and beds of silty material that weather brown and reddish brown. Although limestone is most common, silty and dolomitic mixtures that have been altered to calc-hornfels are also present. Brachiopods are found locally, and pelmatozoan fragments are liber- ally scattered through the unit. MIDDLE QUARTZITE Overlying the belt of nonquartzite rocks is a distinc- tive marker zone composed mainly of pure quartzite. This unit is more than 200 feet thick in Willow Springs Canyon, but northward it thins and becomes discon- tinuous and finally disappears near section JS-9. Most beds in this unit could be referred to as "typical Eureka Quartzite." The quartzite is white to light gray, massive to poorly bedded, and has a blocky to hackly fracture; it is composed of well-sorted and well- rounded very fine to medium-sand-size quartz grains. Locally this unit contains thinly bedded crossbedded quartzite and may have calcite cement. - In some sections (JS-2 and -3, for example), particularly in the south- ernmost sections, the unit includes beds of limestone and dolomite. The middle quartzite is unit 10 in the type section of Pestana (1960, p. 863), and unit 7 of my modification of the same section (JS-7). CORAL LIMESTONE A unit composed mostly of limestone in which coral fragments are locally abundant forms a lens from the type section (JS-7) north to the vicinity of section INDEPENDENCE QUADRANGLE, CALIFORNIA JS-10. It thins rapidly both north and south from a maximum thickness of about 90 feet. The limestone is bluish gray to dark gray in thin ir- regular beds containing scattered black chert nodules. These beds are relatively soft and are poorly exposed in some areas. - Grayish-red silty lenses and irregular beds give a purplish cast to some outcrops. The grayish-red lenses, which are commonly coral bearing, are a distinc- tive feature of this unit. Corals are the most common fossils in the limestone, but brachiopods, gastropods, bryozoans, and pelmatozoan fragments were also seen. The corals are most abundant in the vicinity of sections JS-( and JS-8. Though gray limestone is the dominant lithology, dark-colored limy quartzite, dark-gray dolomite in thin nodular beds, and minor silty layers are also present. The coral limestone member comprises units 11-14 of Pestana's type section and units 8 and 9 of section JS-7. UPPER DOLOMITE Overlying the coral limestone member, but more ex- tensive, is a dolomite member that crops out along al- most the entire strike length of the formation. This dolomite, together with the coral limestone, forms a car- bonate belt separating the upper and middle quartzites. The dolomite is as much as 40 feet thick, and it thickens and thins irregularly along its strike length. The dolomite is medium gray to dark gray but weathers lighter. Bedding is variable; in some places it is thin and nodular, and elsewhere it is massive or very poorly developed and thick. Black chert nodules are scattered to common, and locally the chert is in 14- to 14-inch thick beds. Fossil debris-most commonly pelmatozoan fragments but also corals and brachio- pods-is scattered through the dolomite. The upper dolomite is unit 15 in Pestana's type sec- | tion, which equates to unit 10 of section JST. UPPER QUARTZITE The formation is capped by a light-colored relatively pure quartzite unit at every measured section except JS-13, the northernmost section measured. The thickest section, about 85 feet thick, was measured near the southern limit of exposure. The unit thins to less than 30 feet thick in less than a mile to the north and remains about 10-30 feet thick for several more miles along the strike. South of section JS-10 the unit lenses out, but it reappears as a thin layer at JS-10; from there it thickens rapidly northward but, just as rapidly, lenses out again south of section JS-13. The upper quartzite is an easily mapped unit, for it forms a prominent white rib (fig. 14) and has the appearance of "typical Eureka Quartzite." ORDOVICIAN SYSTEM 23 FIGURE 14.-Johnson Spring Formation. quartzite north of the Blue Stone tale mine. skyline are dolomite and limestone underlain by middle quartzite, Prominent rib of the upper Dark rocks to right on which makes white rib on skyline. Dark rocks to left of upper quartzite are lower part of the Ely Springs Dolomite. The quartzite is white to various shades of gray on fresh surfaces. - Locally it weathers to shades of yellow and orange or to a reddish cast along joint surfaces. Most outcrops are boldly massive, but some are thin to thick bedded. The quartz grains are fine to medium sand size and generally are well rounded and well sorted. The quartzite is notably pure, but minor calcite cement is found in some outcrops. The northernmost thick lens (JS-11, JS-12) contains minor dolomite and, lo- cally, soft sandy layers rich in sericite, which reflects argillaceous impurities. Pestana's (1960, p. 863) unit 16, at the type section, is the upper quartzite (unit 11) in the equivalent section JS-7. FOSSILS AND AGE Fossils in the Johnson Spring Formation are of par- ticular geologic importance because the lateral equiva- lent of this unit is almost exclusively quartzite that is notably unfossiliferous. The carbonate units, particu- larly the coral limestone unit and parts of the mixed- lithology unit, locally contain abundant corals and, less commonly brachiopods, bryozoans, and gastropods. Undiagnostic pelmatozoan fragments also are wide- spread and abundant. The first reported collections from the formation were made by Langenheim and others (1956, p. 2093). They listed a fauna of corals, bryozoans, brachiopods, gastro- pods, sponges, pelecypods, and cephalopods, which were collected in the canyon where JS-7 was later measured and in the next canyon to the south. They considered that "this fauna has a general Blackriver-Trentonian aspect, although certain elements, such as Ptychopleu- rella n.sp. and Favistella cf. F. discreta, suggests that it may be Trentonian." A further collection and study was made in the same area by Pestana (1960), who enlarged on the previous collections and described several new coral species and a new brachiopod species. Pestana (1960, p. 864), chiefly on the basis of the generic ranges of the corals, concluded that the formation appeared to be of Trenton age. In the present study of the Independence quadrangle, several collections were made, chiefly of corals and brachiopods. The identifications in the following col- lections were made by R. J. Ross, Jr. USGS colln. D1008-CO. Collected from unit 8 of section JS-T about 140 feet above the base of the formation (California coordinates, zone 4; 2,273,500 E., 575,700 N.). Streptelasmid corals, small Palaeophyllum ? sp. Lichenaria sp. Dinorthid, smooth, indeterminate (fragment) aff. Nicolella sp. (immature) Zygospira sp. Sowerbyella merriami Cooper This fauna correlates with the upper Copenhagen Formation and may be of Wilderness age. USGS colln. D1025-CO. Collected from unit 6 of section JS-T about 85 feet above the base of the formation (California co- ordinates, zone 4 ; 2,273,500 E., 575,700 N.). Small streptelasmid corals Zygospira sp. Sowerbyella sp. USGS colln. D1064-CO. _ Collected from unit 5 of section JS-2 (California coordinates, zone 4; 2,271,300 E., 544,700 N.). Sowerbyella? sp. (fairly large) Desmorthis? sp. Trilobite fragments The occurrence in this collection of the specimen which is probably Desmorthis was unexpected because Desmorthis is considered to be a genus of Whiterock age that occurs below Rhysostrophia. Collected from unit 7 of section JS-2 (California coordinates, zone 4 ; 2,271,300 E., 544,700 N.). Sowerbyella? sp. USGS collin. D1091-CO. _ Collected 70 feet above base of forma- tion (California coordinates, zone 4; 2,273,000 E., 579,700 N.) Dinorthis? sp. (mold of a large pedicle? valve) The following collections were identified and reported on by W. A. Oliver (written commun, 1960). Collected about 6,000 feet N. 40° E. of Johnson Spring in unit 10 (coral limestone) of section JS-10 (California coordinates, zone 4 ; 2,273,000 E., 580,200 N.). Palaeophylium sp. 1, several blocks "Streptelasma'" tennysoni Pestana (20 specimens repre- senting one or several coralla) Streptelasmatid corals (two specimens) Horn corals, indeterminate (nine specimens) Receptaculitid fragment [Oliver stated that Palaeophyllum sp. 1, which forms 50 per- cent of the collection, may be P. rugosum Billings of Pestana (1960) because it fits Pestana's description in all respects. 24 STRATIGRAPHY OF PALEOZOIC FORMATIONS, Neither the specimens at hand nor those illustrated by Pestana would justify comparison with Billings' species. "Streptelasma'" tennysoni Pestana forms 40 percent of the collection; Oliver did not know what genus it should be assigned to but stated that it is not Streptelasma. The peripheral budding with loose, phaceloid growth form is characteristic. Oliver believed that this collection is most likely Late Ordovician in age, although he would not rule out Early or Middle Silurian or late Middle Ordovician.] Collected about 4,900 feet N. 60° E. of Johnson Spring in the coral limestone unit near section JS-8 (California coordi- nates, zone 4 ; 2,273,300 E., 577,800 N.). Palaecophyllum sp. 2 Streptelasmatid corals [According to Oliver, PalacophylHum sp. 2(?) may be the same as P. sp. 1, but it is larger and has shorter septa. Neither is comparable to Pestana's other species of Palacophyllum.] Collected about 7,800 feet S. 59° E. of SE cor. sec. 86, T. 11 8., R. 35 E. Float from near the middle of formation (California coordinates, zone 4 ; 2,272,400 E., 582,900 N.). Palacophylium? sp. 3 Horn corals (indeterminate) Favistella sp. Echinoderm columnals Palacophyllum? sp. 3 could be P. mazourkaensis Pestana, be- cause it is comparable in size and growth form, but it is so poorly preserved that it cannot be definitely assigned, even to genus. Favistelle is presumably restricted to rocks of Middle and Late Ordovician age. Collected about 8,700 feet S. 54° E. of SE cor. see. 36, T. 11 S., R. 35 E. (California coordinates, zone 4: 2,272,700 E., 581,800 N.). Streptelismatid corals Echinoderm debris [Oliver noted that the streptelasmatid corals are of types common in parts of the Ordovician but that a Silurian age cannot be ruled out on the basis of these corals alone.] Collected 10 feet above base of unit 8 of section JS-8 (Cali- fornia coordinates, zone 4; 2,273,400 E., 577,400 N.). Indeterminate coral cf. Hofletcheria Sp. The corals, which looked so promising in the field, have not proven to be of much value in dating the Johnson Spring Formation; silicification has ap- parently destroyed internal structures, which are crit- ical for identification. Externally, the corals from some localities appear remarkably well preserved. Oliver's identifications suggest a Middle or Late Ordovi- cian age, but he was careful to point out that a Silurian age cannot be ruled out on the basis of the corals alone. R. J. Ross, Jr. (written commun., 1962), placed the Johnson Spring Formation in the Wilderness Stage (immediately below the Trenton) of the Middle Ordo- vician. Langenheim and others (1956, p. 2093) con- sidered that the "fauna has a general Blackriver-Tren- tonian aspect," but they seemed to favor a Trenton age. Pestana (1960, p. 864) also favored a Trenton age. The Johnson Spring Formation is thus considered Middle Ordovician, most probably middle or late Mid- dle Ordovician. INDEPENDENCE QUADRAN GLE, CALIFORNIA CORRELATION AND RELATION TO THE EUREKA QUaARTZITE Probably no formation in the Great Basin is more widely known than the Eureka Quartzite. It is a dis- tinctive relatively homogeneous unit that has a fantas- tically wide distribution, considering that its thickness is only a few hundred feet at most. Only a few miles southeast of the Independence quadrangle, in the New York Butte quadrangle, a belt of Eureka Quartzite oc- cupies the stratigraphic interval filled by the Johnson Spring Formation in the Independence area. There can be little doubt of the stratigraphic equivalence of these two units, particularly in view of the readily apparent lensing out of carbonate and other nonquartzite litholo- gies in the southern part of the area in the direction of the Eureka outcrops (pl. 3). In the New York Butte quadrangle, shaly beds prob- ably correlative with the Barrel Spring Formation are included in the lower part of the Eureka Quartzite (Merriam, 1963b, p. 10). Farther east, in Nevada, the fine-grained clastic and carbonate beds that had been mapped as Eureka Quartzite by Kirk (1933, p. 32) were placed in a new formation, the Copenhagen For- mation, by Merriam (19632, p. 25). The Eureka Quartzite, as defined in the New York Butte quadrangle (Merriam, 1963b, p. 9), would include both the Barrel Spring and Johnson Spring Formations. As currently defined in eastern Nevada (Webb, 1958, p. 2340-2342), the Copenhagen Formation would equate to the Barrel Spring Formation, and the Eureka Quartzite would be grossly equivalent to the Johnson Spring Formation. Langenheim and his associates (1956, p. 2094) pro- posed that the term Eureka Group include the Barrel Spring Formation and unnamed overlying rocks, later named the Johnson Spring Formation by Pestana (1960, p. 862). This terminology would fit sections in the western Great Basin, where Copenhagen-like rocks have been included in the Eureka, or where the Copen- hagen is not identifiable. In current eastern Nevada usage, however, Langenheim's Eureka Group would in- clude the Eureka Quartzite of Kirk (1933) plus the underlying Copenhagen Formation. Although Lan- genheim's suggestion probably has logic and historical precedent, its adoption seems improbable. The firmly entrenched name Eureka Quartzite is not likely to be soon replaced by another name so that Eureka can be used for the group. Correlation of individual sections of the Eureka Quartzite with the Johnson Spring Formation is some- what difficult. Fossils are virtually nonexistent in the Eureka, and the Johnson Spring Formation is litho- logically dissimilar from the "typical" Eureka. In some Eureka sections, a two- or three-fold subdivision is ORDOVICIAN SYSTEM 25 evident, the uppermost unit of which most likely equates to the Johnson Spring Formation. In the Quartz Spring area (McAllister, 1952, p. 12) the upper 250 feet of white vitreous quartzite of the Eureka may be correlative with the Johnson Spring, and the lower 150 feet of crossbedded darker, hema- titic quartzite, platy quartzite, and siltstone may be correlative with the Barrel Spring Formation as sug- gested by Langenheim and others (1956, p. 2090). Recent examination of this section by J. F. McAllister, R. J. Ross, Jr., and me, however, suggests the alternate possibility that the upper 250 feet of McAllister's see- tion correlates with units 7-11 of section JS-T of the Johnson Spring type section (the same as units 10-16 of Pestana, 1960, p. 862-863), and that the remainder of the Johnson Spring correlates with McAllister's lower Eureka. The possible relation of the Barrel Spring to this section is discussed on p. 18. A similar two-fold division of the Eureka was noted in the Funeral Mountains east of Death Valley (J. F. McAl- lister, written commun., 1962), and a similar correla- tion with the Johnson Spring is suggested. In the Darwin area (Hall and MacKevett, 1962, p. 10) the Eureka Quartzite is probably a correlative of the Johnson Spring. Here transitional beds between the Pogonip and the Eureka may equate to the Barrel Spring. (See p. 18.) At the Nevada Test Site, the 300-foot-thick upper unit of the Eureka Quartzite (Byers and others, 1961, p. C107) may be equivalent to the Johnson Spring, but this correlation is very tentative. Generally the Barrel Spring and Johnson Spring Formations can be equated to the Eureka Quartzite as described by Kirk (1933). Variations in the Eureka Quartzite from pure quartzite considered as "typical Eureka" are most common in the lower part, where carbonate and fine-grained clastic beds like those of the Copenhagen and Barrel Spring occur. The upper part of the Eureka, on the other hand, appears to remain relatively pure. Thus, a significant change in the lithology of the Eureka interval occurs in the Inde- pendence area (pl. 3; fig. 12) ; the Barrel Spring and Johnson Spring Formations together represent the westernmost recognizable stratigraphic equivalent of the Eureka. - To the northwest along the strike, equiva- lent beds may also be present in the Mount Morrison roof pendant about 50 miles away, where clean sand- size clastic material and calcareous quartz sandstone are interbedded with fine-grained clastics and carbonates in a thick interval containing Ordovician graptolites (Rinehart and Ross, 1964, p. 17-23). ELY SPRINGS DOLOMITE NAME AND DISTRIBUTION The Ely Springs Dolomite was named by Westgate and Knopf (1932, p. 15) from exposures in the Ely Springs Range near Pioche, Nev., nearly 200 miles northeast of the Independence quadrangle. The name is widely used in the southern part of the Great Basin for the carbonate rocks immediately overlying the Eureka Quartzite. A faulted but nearly continuous outcrop belt extends from the Squares Tunnel area to northwest of Badger Flat, where the formation is faulted and cut out by granitic rocks. This is the northwesternmost known occurrence of rocks that are assignable to the Ely Springs Dolomite. South of the Squares Tunnel area, faulted segments of the formation extend almost to Coyote Spring. Beds assignable to the Ely Springs Dolomite are present a few miles farther southeast, in the New York Butte quadrangle, (Merriam, 1963b, p. 10), and in a small area along the east front of the Inyo Mountains in the Waucoba Wash quadrangle near the White Eagle tale mine. THICKNESS AND STRATIGRAPHIC RELATIONS The measured thickness of the Ely Springs Dolomite ranges from 591 feet at the southernmost section (ES-1) to 195 feet at the northernmost section (ES-10). The northward thinning of the formation (pl. 4) is a characteristic of the Ely Springs Dolomite and several other formations in the quadrangle. The average thickness, based on nine measured sections, is less than 300 feet, much less than that of presumably correlative rocks southeast of the Inyo Mountains. Only a few miles to the southeast, in the New York Butte quadrangle, Merriam (1963b, p. 10) assigned at least 240 feet of beds to the Ely Springs. The upper contact there is uncertain because of the similarity of the upper part of the Ely Springs to the overlying Silurian dolomite; thus, the formation may be thicker. Merriam (1963b, p. 8) listed a thickness range from 240 to 550 feet for the Ely Springs, which is comparable to that of sections in the Independence quadrangle. The Ely Springs Dolomite generally is considerably thicker in the areas southeast of the Inyos. Reported thicknesses are: in the Darwin quadrangle, about 920 feet (Hall and MacKevett, 1962, p. 10) ; in the Quartz Spring area, 740-940 feet (McAllister, 1952, p. 15): at the Nevada Test Site, about 280 feet (Poole, 1965) ; and at the north end of the Nopah Range, 800 feet (Hazzard, 1937, p. 325). At Bare Mountain, Nev., Cornwall and Kleinhampl (1961) measured only about 300 feet. 26 STRATIGRAPHY OF PALEOZOIC FORMATIONS, The beds of the Ely Springs Dolomite overlie the Johnson Spring Formation conformably. The con- tact is generally abrupt, quartzite against the overlying dolomite. The interbedding of dolomite similar to that of the Ely Springs with quartzite in the upper part of the Johnson Spring Formation suggests a lithologic transition. For convenience in mapping, I placed the contact at the top of the uppermost quartzite. In other areas-for example, the Dry Mountain quadrangle quartzite beds are included in the lower part of the Ely Springs Dolomite (McAllister, written commun., 1962) and the base of the Ely Springs is placed at the bottom of the lowest carbonate above the massive Eureka Quartzite. In the Independence area, the upper dolo- mite of the Johnson Spring Formation may correlate with the lowermost Ely Springs of such sections. For mapping purposes, however, these differences are not significant. It is a matter of interpretation, through a few tens of feet at most, whether the lowest dolomite or the highest quartzite marks this contact. This interval, then, marked by intertonguing carbonate and clean sand-size clastic materials, represents a zone of contin- uous deposition but one in which conditions of sedimen- tation were changing. Such a change is widespread in the Great Basin at this stratigraphic level. LITHOLOGY The Ely Springs Dolomite is almost exclusively dolo- mite, in shades of gray, with varying amounts of nodular and bedded black chert. Throughout the In- dependence quadrangle the formation is readily sep- arable into three members (pl. 4): (1) a lower thin- bedded dark-gray dolomite containing abundant black chert, (2) a middle massive light-gray dolomite, and (38) an upper thin-bedded dark-gray dolomite with nodular and bedded black chert. These members are not delineated on the geologic map because they are too thin to be shown at the map scale. In addition to the thinning of the formation to the north, a pronounced lithologic change also occurs in the same direction. Near the north end of the outcrop belt, both the lower and upper members grade into massive black chert; in its northernmost exposures, the Ely Springs Dolomite comprises a lower massive chert member, a middle gray dolomite, and an upper massive chert member. This section is so different from the typical Ely Springs that it properly deserves a new for- mational name to point out this lithologic variance. Since such a name would apply only to a strike segment about 2 miles long northwest of Badger Flat, this var- iant is not named but is described as part of the Ely Springs. The trend of increasing chert at the ex- pense of dolomite in the Ely Springs is one more INDEPENDENCE QUADRANGLE, CALIFORNIA instance of the increase in transitional-assemblage affinities northward in the Paleozoic rocks of the Inde- pendence quadrangle. LOWER MEMBER The lower member, consisting of dark-gray dolomite and chert, forms a dark belt extending along the entire outcrop length of the formation. It ranges in thick- ness from 294 feet in Willow Springs Canyon to less than 50 feet near Badger Flat. The dolomite is mostly medium dark gray to dark gray on fresh surfaces and medium gray on weathered surfaces. Individual beds are generally 1-6 inches thick and somewhat nodular. Laminations are com- mon within many individual beds, but locally the out- crops are massive and poorly bedded. The chert is black where fresh and unaltered, but metamorphism has lightened much of it (fig. 154). The chert occurs in thin nodular beds as much as 3 inches thick, in scattered nodules, or in trains of nod- ules that follow bedding. The overall dark color and the abundance of chert characterize this member. Most outcrops in the southern part of the area are 10-15 percent chert (fig. 154), although some are almost chert free. About 114 miles southeast of Badger Flat, the amount of chert in- creases notably, and the rocks are as much as 25 percent black chert, commonly in nodular beds (fig. 152). The lower member is transformed entirely to chert in a strike length of less than 1 mile just south of Badger Flat. Section ES-9 shows this transition; chert beds as much as 1 foot thick are interbedded with dark dolo- mite overlying a basal unit composed of massive chert. At section ES-10, massive black chert, in part altered to shades of gray, makes up the entire member. This lithology continues across Badger Flat and north to the end of the outcrop belt (fig. 150). MIDDLE MEMBER The middle member, composed of light-gray dolomite was traced along the entire strike length of the forma- tion. It forms an easily recognizable light-gray belt that markedly contrasts with the underlying and over- lying darker members. The thickness ranges from about 65 feet to somewhat less than 150 feet but does not seem to change systematically along the strike. In contrast with the other two members, the greatest thickness of the middle member is near the center of the outcrop belt. The dolomite is medium gray to medium dark gray on fresh surfaces, similar to the dolomite of the lower member, and characteristically and distinctively light gray or, locally, dappled gray on weathered surfaces. ORDOVICIAN SYSTEM 27. Irregularly ridged and spiny surfaces are also present. From a distance the member appears massive, and it is a good cliff former; blocky, craggy outcrops are common. On close observation, however, most out- crops show some thin to thick irregular bedding. Clastic beds are generally absent, but a local sandy lens in unit 2 of section ES-5 indicates that sandy material was still being supplied, at least locally. - This lens has 15-20 percent of 0.2-0.5-mm well-rounded quartz grains scattered through a dolomite matrix. UPPER MEMBER The upper member, composed of dark-gray dolomite and chert, forms a dark, easily recognizable band along the entire strike length of the formation in the quad- rangle. This member was not recognized in the Inyo Mountains east and southeast of the Independence quadrangle. The thickness ranges from 166 feet in Willow Springs Canyon to about 30 feet near the north end of the area. The basal beds of the member are interbedded dark- gray to medium-gray dolomite and black chert in rather regular layers as much as 4 inches thick. These FicURE 15.-Ely Springs Dolomite. A, Black chert nodules and nodular layers in dark-gray dolomite of lower member in Willow Springs Canyon (unit 1 of measured section ES-1). Chert commonly con- tact metamorphosed to light-colored calc-hornfels minerals. B, Dark- gray dolomite and nodular bedded chert. Photograph taken about 10 feet above base of lower member of formation along section ES-8. Hammer used for scale. C, Banded chert west of Badger Flat. Lighter layers at least partly a metamorphic effect. Penny used for scale. distinctive beds are persistent and best developed in the northern part of the area (fig. 1641). In part, these beds are overlain by thin-bedded to massive dark-gray to light-gray dolomite. Bedding is commonly irregular, and chert nodules, though locally abundant, are missing in many outcrops. - The dolomite shows the pitted and ridged weathered surface typical of fine-grained dolomite in arid regions. The next overlying and most distinctive unit in the member is a massive black chert that is found at almost all outcrops. The chert forms bold outcrops (fig. 16B) a few feet to at least 30 feet thick. Lamination or thin bedding is visible in most of the seemingly massive outcrops on close observation. This massive chert unit was cited by Langenheim and others (1956, p. 2095) as an example of a siliceous hardpan mark- ing a post-Ely Springs erosional interval. Nolan, Merriam, and Williams (1956, p. 37) speculated that this unit was the stratigraphic equivalent of a massive bed of black chert that is widespread in the Great Basin and is considered to be the lowermost bed of the Roberts Mountains Formation of Silurian age. At several measured sections of the Ely Springs Dolomite, how- 28 STRATIGRAPHY OF PALEOZOIC FORMATIONS, A, Along measured section ES-10 ; steeply dipping contact of lighter colored middle member (unit 2) on left with dark dolomite and chert of upper member on right (unit 3 FicurRE 16.-Ely Springs Dolomite. capped by unit 4 at right of massive outcrop). B, Massive brecciated black chert at top of upper member; unit 7 of measured section ES-4. ( ever, the massive chert unit is overlain by dolomite typical of the rest of the formation. (See p. 54-56). I interpret the massive chert in the Independence quad- rangle as being within the Ely Springs Dolomite; in places it is the uppermost unit, and in other places it is below the uppermost dolomite. The massive chert and the overlying dolomite belong with the rest of what I call Ely Springs Dolomite, as a map unit. The much less certain question of the age of these upper beds and their correlation with the upper part of the Ely Springs Dolomite or with Silurian rocks in other areas is discussed in the following section, "Fos- sils, Age, and Correlation." Just south of Willow Spring Canyon, along section ES-1, 28 feet of cherty limestone is poorly exposed INDEPENDENCE QUADRANGLE, CALIFORNIA near the top of the upper member. This is the only known occurrence of limestone in the formation within the quadrangle. It is both overlain and underlain by cherty dolomite of the Ely Springs type, and is con- sidered to be part of the Ely Springs Dolomite, though it may be a precursor of the dominantly limestone strata of the overlying Vaughn Gulch Limestone of Silurian age. The upper member maintains a general three- or four-fold division as far north as section ES-10 (pl. 4). The transition of this member to massive chert north of section ES-10, is concealed in poor exposures in the Badger Flat area ; but northwest of Badger Flat, massive chert similar to that of the lower member is locally well exposed. Presumably the concealed tran- sition zone is much like that of the lower member as shown by section ES-9. FOSSILS, AGE, AND CORRELATION No identifiable fossils were recovered from the Ely Springs Dolomite during the mapping of the Inde- pendence quadrangle. Fragments of corals were found, and pelmatozoan debris is locally abundant. Some massive chert beds contain oval to rounded spots of somewhat coarser quartz (0.1-0.15 mm in diameter) that probably represent the remains of Radiolarian tests. One massive chert specimen was rich in sponge( ?) spicules. Langenheim and others (1956, p. 2095) reported poorly preserved Streptelasma sp. from the formation. A collection of brachiopods and corals from the lower part of the Ely Springs in the Darwin area is Late Ordovician in age (Hall and MacKevett, 1962, p. 11). A fauna of brachiopods and corals from the Quartz Spring area also support a Late Ordovician age (McAllister, 1952, p. 15). On the basis of lithologic comparison with fossiliferous Ely Springs in these areas, the rocks referred to the Ely Springs Dolomite in the Independence quadrangle are probably Late Ordovician in age. The lower and middle members probably correlate with units 1 and 2, respectively, of the Quartz Spring area (McAllister, 1952, p. 13) and with the lower and upper parts of the Ely Springs Dolomite in both the Darwin area (Hall and MacKevett, 1962, p. 11) and the Nopah Range (Hazzard, 1937, p. 325). The upper member, on the other hand, does not have an obvious correlative unit in the Ely Springs of the Quartz Spring area or the Nopah Range. At Darwin a 40-foot-thick dark-gray dolomite with little chert is at the top of the formation (Hall and MacKevett, 1962) and may be correlative with the upper member, but this correlation is very speculative. SILURIAN AND DEVONIAN(?) SYSTEMS The upper member may be equivalent to the lower part of the Hidden Valley Dolomite, which was origi- nally described in the Quartz Spring area by McAllis- ter (1952, p. 15) as medium-gray to light-gray dolomite with abundant chert. In the nearby New York Butte quadrangle, a direct lithologic comparison is difficult to make; although dolomite and chert make up the lower part of the Hidden Valley, they are metamor- phosed (Merriam, 1963b, p. 11). At Darwin, on the other hand, the Hidden Valley does not match the upper part of the Ely Springs of the Independence area. In the Nopah Range, dolomite containing abun- dant chert in the lower part of the unnamed Silurian (Hazzard, 1937, p. 326) may equate to the upper Ely Springs of the Independence area. At Lone Moun- tain (Nolan and others, 1956, p. 37), Bare Mountain (Cornwall and Kleinhampl, 1961), and other places in Nevada, black chert and dolomite that make up the lower part of the Roberts Mountains Formation of Silurian age may also be equivalent to the upper mem- ber of the Ely Springs Dolomite of the Independence area. I thought that the contact of the chert and dolo- mite of the lower unit with the slabby silty limestone of the middle unit of the Roberts Mountains Forma- tion in Chuckwalla Canyon (Bare Mountain) looked very similar to the contact between the Ely Springs and Vaughn Gulch Formations in the Independence quadrangle. The correlation of the lower and middle members of the Ely Springs Dolomite in the Independence area with the Ely Springs elsewhere is likely, and the assign- ment of a Late Ordovician age for these members is a strong probability. The correlation and -age of the upper member are less certain. The upper member is lithologically compatible with the lower two members of undoubted Ely Springs and is markedly different from the overlying rocks; hence, it belongs with the lower two members as a mappable unit. My presump- tions that these three members together are correlative with the Ely Springs and that the top of the formation in the Independence area marks the boundary between the Ordovician and the Silurian should be viewed with some reservations. The upper part of the formation could be Silurian and correlative with the lower part of the Hidden Valley Dolomite. The age and correlation uncertainties about the upper . part of what I call Ely Springs suggest that a new local formational name would be desirable for the entire formation, but retention of the old name is favored for the present to point out the similarity of this forma- tion to the Ely Springs elsewhere. Many formations in the Independence area have been given local names to stress variations from formations of the eastern (car- 212-460 O-66- a & 29 bonate) assemblage. Wherever possible, the "classic" carbonate assemblage names should probably be re- tained to call attention to the fact that, although transi- tional, the Independence Paleozoic section is closely related to the carbonate assemblage.* SILURIAN AND DEVONIAN(?) SYSTEMS Throughout most of the southwestern part of the Great Basin, the Silurian and Lower Devonian are rep- ; resented by dolomite typified by the Hidden Valley Dol- | In marked contrast, _ omite (McAllister, 1952, p. 15). the Silurian and Devonian(?) rocks in the Independ- ence quadrangle consist of thin-bedded argillaceous limestone and bioclastic limestone (the Vaughn Gulch Limestone) rich in coral, sponge, bryozoan, and pelma- tozoan debris that grades laterally northward into grap- tolite-bearing calcareous shale, siltstone, and argillace- ous limestone (the Sunday Canyon Formation) pene- trated by tongues of bioclastic limestone of the coral- rich facies to the south. The Vaughn Gulch Limestone and the Sunday Can- yon Formation are virtually limited to the Independence quadrangle. - The nearest Silurian and Lower Devonian rocks to the southeast in the New York Butte quadrangle are Hidden Valley Dolomite (Merriam, 1963b, p. 11). To the east the nearest rocks in this time span are near the east base of the Inyo Mountains about 3 miles east of the quadrangle boundary. These rocks are dolomite and are probably correlative with the Hidden Valley. To the north and west, limited outcrops of limy and 1 Regional studies of the Ely Springs Dolomite from its type section in eastern Nevada to eastern California suggest that the upper part of the Ely Springs Dolomite as used in Mazourka Canyon is Silurian (F. G. Poole, oral commun., 1965). In a field conference in Mazourka Canyon after the completion of this report, Poole suggested to me that at section ES-1 (pl. 4) much of the middle member was correlative with his unit Su», and the entire upper member was correlative with his unit Sus, both of which are Silurian units in the Nevada Test Site area (Poole, 1965), and units which he has recognized widely over the south- ern Great Basin. Poole also suggested essentially the same correlations for the middle and upper members at sections ES-4 and ES-10. He felt that the middle member is largely equivalent to his unit Su» rather than to the type upper Ely Springs, on the basis of rather subtle grain size and color differences in the dolomite, which he believes are diag- nostic on a regional scale. If these correlations are valid, it means that (1) the lower dark-gray dolomite and chert member in Mazourka Canyon is correlative with the lower Elk Springs Dolomite at the type section in eastern Nevada, (2) the lowermost beds of the middle member north to about the area of section ES-4 are correlative with the lower part of the upper Ely Springs at the type section, and (3) the rest of the Mazourka Canyon Ely Springs is correlative with Poole's units Su, and Sus, which he considers Silurian. Poole's regional studies also suggest that the Silurian rocks rest with erosional unconformity on various parts of the Ely Springs Dolomite over the southern Great Basin, and that rocks he believes to be Silurian in Mazourka Canyon were deposited on an erosion surface: at ES-1, on top of about 30 feet of beds correlative with type upper Ely Springs ; at ES-4, on top of only a few feet of beds correlative with type upper Ely Springs; and at ES-10, directly on beds correlative with type lower Ely Springs. Poole would thus restrict the name Ely Springs Dolomite to the rocks below this unconformity. No physical evidence of an erosional break has been noted, however, within what was mapped as Ely Springs in the Mazourka Canyon area. 30 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA silty rocks that are probably Silurian have been mapped in the Waucoba Mountain quadrangle by C. A. Nelson (oral commun., 1963) ; beyond this area Silurian rocks have not been recognized, though they could be present in roof pendants in the Sierra Nevada. {_- Despite their limited known outcrop area, the Silu- rian and Devonian(?) formations of the Independence area are important because they signal the northwest- ward change from the carbonate (eastern) assemblage to | the transitional assemblage of the Great Basin. VAUGHN GULCH LIMESTONE NAME AND DISTRIBUTION The Vaughn Gulch Limestone was named and the type section designated by Ross (1963, p. B81 ) for ex- posures along the ridge northwest of Vaughn Gulch, a small tributary to Owens Valley near the mouth of Mazourka Canyon. At the type section the formation is well exposed in a steeply dipping somewhat faulted and folded homocline (fig. 174). To the south the formation is considerably faulted and folded, and about 24/4 miles southeast of the type section it is cut out by a large granitic mass. - This is the south- ernmost known exposure of the formation. About 12 miles farther southeast, Silurian and lower Devonian rocks reappear, but they are part of the Hidden Valley Dolomite. FigURE 17.-Vaughn Gulch Limestone. A, Looking north at type sec- tion. On the left, the Perdido Formation (Mp) unconformably over- lies the Vaughn Gulch Limestone (DSvg) ; on the right, the underlying Ely Springs Dolomite (Oes) is in fault contact. B, Bioclastic beds on ridge northwest of Vaughn Gulch; 340 feet above base of unit 4 of the type section. The northern limit of the formation is in Water Can- yon, about 5 miles north of the type section. Tongues of the Vaughn Gulch Limestone extend several miles farther north into laterally equivalent graptolite-bear- ing rocks, but the canyon makes a practical though arbi- trary mapping break. THICKNESS AND STRATIGRAPHIC RELATIONS The measured thickness of the Vaughn Gulch is about 1,500 feet at the type section northwest of Vaughn Gulch. The upper contact is an erosional unconform- ity ; so the thickness measured is something less than the original thickness. A presumably much more eroded section about three-quarters of a mile northeast of Squares Tunnel is only about 260 feet thick. Almost everywhere else, faulting precludes thickness measure- ments. From the data at hand, all that can be deter- mined with certainty is that the original thickness was at least 1,500 feet. The contact with the underlying Ely Springs Dolo- mite is conformable. Dolomite or massive black chert at the top of the Ely Springs generally makes a rather distinctive and abrupt contact with the Vaughn Gulch Limestone. At the type section, a poorly exposed lime- stone 28 feet thick 18 feet below the top of the under- lying Ely Springs could be a tongue of the Vaughn Gulch Limestone. Nowhere else in the area was lime- SILURIAN AND DEVONIAN(?) SYSTEMS 31 stone found in the Ely Springs; this one section could reflect an interbedded transition between the Ely Springs Dolomite and the Vaughn Gulch Limestone. LITHOLOGY The Vaughn Gulch Limestone is predominantly thin- bedded argillaceous and silty limestone. (See VG-1,-2, p. 56.) Much of it is medium to dark gray on fresh sur- faces; it commonly weathers light gray, but shades of red, orange, and yellow are characteristic of the more impure beds. Bioclastic limestone (fig. 172), the most diagnostic rock type in the formation, is characterized by beds crowded with fragments of corals, sponges, bry- ozoans, pelmatozoans, and some brachiopods. Detailed study of some specimens leaves little doubt that most, if not all, of the limestone is fragmental. The widespread presence of fossil fragments, the general abundance of silty impurities, and the evidence of silt- to sand-size calcite clasts identify most of the rocks of this formation as calcarenite or calcilutite. Insoluble residues ranged from 21 to 69 percent in some samples that did not contain visible fossil fragments. Silt- and sand-size quartz fragments made up most of the residue, but finer grained, presumably argillaceous material and black carbonaceous matter were also present. The amount of insoluble residues indicate that some parts of the formation are calcareous siltstone. The specimens selected for insoluble-residue analyses were chosen from the beds that looked most impure, however, and lime- stone rather than siltstone is predominant in the formation. Black chert, in nodules and in beds as thick as 3 inches, is common in unit 7 near the top of the type section, less common near the base, and scattered elsewhere. At the type section, no obvious divisions could be mapped in the formation. - The units at the type section (VG-1, p. 56) were distinguished on the basis of gross color differences and the varying ratio of bioclastic limestone to argillaceous limestone. West of the Mazourka Canyon road there is even less opportunity to divide the formation, because thermal metamorphism has affected the section. Division of the type section on the basis of fossil zones might be possible, but this would not yield mappable subunits. The Vaughn Gulch Limestone is mostly a limestone in the field sense-that is, a calcareous rock. More pre- cisely, the formation is a clastic unit made up of quartz grains, calcite fragments (many of which are fossil fragments), and argillaceous and carbonaceous ma- terial. Dominantly the formation is made up of clastic beds ranging from calcilulite to calcirudite and, less commonly, calcareous siltstone. 212-460 0O-66--4 FOSSILS AND AGE Fossils are abundant, particularly at the type section. They are commonly silicified and many are broken, but some coral heads more than 1 foot across are preserved. The first report on fossils from the formation was made by Kirk (in Knopf, 1918, p. 36, 37). He listed genera of corals, brachiopods, trilobites, and one cepha- lopod and assigned the formation to the Devonian. He later recognized that these beds might be Silurian (Nolan, 1943, p. 153). The same section where Kirk collected, and presum- ably the type section of the Vaughn Gulch Limestone, was also examined by Stauffer (1930, p. 86-89). He tabulated an impressive fossil list keyed to the units he distinguished and assigned the rocks to the Middle Devonian. Waite (1953) in studying this same section, concluded that some of the fossils preclude a Devonian age. He noted particularly the forms Conchidium, Pyenostylus guelphensis Whiteaves, and Atrypina cf. A. disparilis (Hall), and further noted that new and better material showed that the Calceola of Stauffer was RAhizophyllum, a characteristic Silurian genus. Waite concluded that the fossils indicate a late Niagara or early Cayuga age for the formation. Collections from the type section of the Vaughn Gulch Limestone were also made by C. W. Merriam, who stated (1963b, p. 13) : The faunas consist very largely of corals, only Atrypae and rhynchonellids (Hatonia bicostata Stauffer) being at all common among the brachiopods. The large dasycladacean algae (Ver- ticillopore annulate Rezak) are most prolific here and provide a tie with the Hidden Valley of the type area as well as with the Roberts Mountains formation of central Nevada and the Laketown dolomite of western Utah. S Among corals of the limestone facies at Mazourka are many conforming to the general features of Strombodes. Others are assigned to Chonophylum, Rhizophyllum, Heliolites, Alveolites, and Cladopora. Also present are large cyathophyllids and bushy forms of the Phacelophyllum and Disphyllum types. Systematic collections were not made from the Vaughn Gulch Limestone during my study. Abundant material is already in the U.S. Geological Survey col- lections and is currently being restudied by C. W. Mer- riam. - The Vaughn Gulch Limestone at the type section contains some fossils very near the top that may be Devonian forms, but the great bulk of the formation is believed to be Silurian (C. W. Merriam, oral commun., 1964. The fact that the uppermost beds of the Vaughn Gulch may be Devonian in age and that possibly De- vonian monograptids are present in the upper part of the laterally equivalent Sunday Canyon Formation sug- gests that the Vaughn Gulch Limestone should be con- sidered Silurian and Devonian (?) in age. 32 STRATIGRAPHY OF PALEOZOIC FORMATIONS, SUNDAY CANYON FORMATION NAME AND DISTRIBUTION The Sunday Canyon Formation was named (Ross, D. C., 1963, p. B83) for Sunday Canyon, a small tribu- tary to Mazourka Canyon about 1 mile west of the out- crop belt of the formation. The Sunday Canyon For- mation crops out in a nearly continuous belt from Water Canyon to a point northwest of Badger Flat, where the formation presumably was entirely removed by erosion prior to the deposition of the overlying Mississippian rocks. Relatively poor exposure and faulting north- west of Badger Flat dictate caution for this presump- tion, however. THICKNESS AND STRATIGRAPHIC RELATIONS The Sunday Canyon Formation ranges in thickness from 0 to about 700 feet. The maximum exposed thick- ness, 683 feet, is at the type section in Bonanza Gulch, about four-tenths of a mile northeast of Barrel Springs, in T. 12 S., R. 36 E. (section SC-1, p. 57). The forma- tion thins to the north and is only 277 feet thick at a measured section south of Badger Flat (section SC-6, p 58). Northwest of Badger Flat the formation thins and wedges out beneath the overlying Mississippian rocks. The contact with the underlying chert and dolomite beds of the Ely Springs is presumably conformable. It is either covered or poorly exposed, as the Sunday Canyon beds are much less resistant and form a bench which may be partly covered by Ely Springs debris. LITHOLOGY The Sunday Canyon Formation consists chiefly of calcareous siltstone, calcareous shale, and argillaceous limestone. Outcrops of the formation are typically thin bedded and weather to poorly exposed slopes lit- tered with thin, shaly to flaggy fragments that are from light gray to shades of yellow and orange. Exposure is normally much better in dry canyons that cut across the strike. Tongues of clastic limestone rich in fossil fragments (northward extensions of the Vaughn Gulch Limestone) are widespread and locally abundant. They seem to be most abundant near Bonanza Gulch and to decrease in abundance to the north, although some beds of bio- clastic limestone are present almost to Badger Flat. A. rather prominent rib-forming zone composed mainly of fossil-rich clastic limestone and dense blue-gray lime- stone in the middle of the formation also contains cal- careous quartz sandstone, quartzite, and abundant chert. The siliceous part of this unit is represented by unit 5 in measured sections SC-3 and SC-4 (p.: 57). INDEPENDENCE QUADRANGLE, CALIFORNIA Chert is locally abundant both as beds and as nodules, but part of what looks like chert in the field is actually fine-grained siltstone, as can be seen on microscopic examination. Most nodules are obviously chert, but some layers that are reported as chert in the measured section may be suspect. The descriptions of the six measured sections (p. 57) give some idea of the gross lithology of the formation. It is not an easy formation to divide. Some bioclastic beds can be traced for some distance by large-scale map- ping, particularly the central, rib-forming unit, which was traced for about 2 miles north of section SC-3. The bulk of the formation, however, is a somewhat feature- less and variable mixture of calcareous, siliceous, and argillaceous material. A gross estimate of the relative amount of calcareous material in this formation was obtained from insoluble residues left when about 30 samples were dissolved in hydrochloric acid. Some of the specimens containing abundant bioclastic material yielded as little as 10 per- cent insoluble residue. Other light-gray rocks, called fine-grained limestone in field descriptions yielded 20- 30 percent insoluble residue. Most samples studied, however, were selected from rocks that were medium dark gray to dark gray on fresh surfaces and effer- vesced with acid. These rocks generally yielded 55- 85 percent insoluble residue, but some yielded more than 90 percent. Much of the insoluble material was fine- grained quartz, but clay and black carbonaceous mate- rial were also abundant. Limited thin-section study revealed that some of the fine-grained limestone is notably clastic ; also calcilutites composed of calcite and quartz grains from 0.02 to 0.05 mm in diameter are predominant. In the more silty limestone, quartz clasts 0.03-0.2 mm in diameter are predominant, but the quartz clasts are associated with calcite clasts and set in a calcareous-siliceous matrix. The distinctive calcareous quartz sandstone and quartzite units are made up of subangular to well- rounded quartz grains and minor feldspar grains from 0.05 to 0.4 mm in diameter set in a calcareous to siliceous matrix. The generalization can be made that the Sunday Canyon Formation is dominantly a clastic unit. Field mapping further suggests that the proportion of car- bonate material decreases toward the north, but more extensive insoluble-residue studies would have to be. made to confirm this. FOSSILS AND AGE The most significant fossils in the Sunday Canyon Formation are the Monograptus graptolites, which have been collected from several localities. They were identified and reported on as follows by W. B. N. Berry SILURIAN AND DEVONIAN(?) SYSTEMS 33 (written commun., 1964) and, for localities 1-233 and 1-235, by R. J. Ross, Jr., (written commun., 1959) : 1-233. Collected half a mile south of Badger Flat near the base of the formation (California coordinates, zone 4; 2,265,- 800 E., 592,100 N.). Monograptus spp. 1-235. Collected from south edge of Badger Flat in lower part of formation (California coordinates, zone 4; 2,262,700 E., 596,300 N.). Monograptus spp. USGS colln. D165-SD. Collected about 7,600 feet north-north- east of Johnson Spring (California coordinates, zone 4; 2,272,000 E., 582,300 N.). Monograptus cf. M. dubius (Suess) Age : In span of Wenlock-Ludlow. USGS colln. D166-SD. Collected from east side of Al Rose Canyon about a mile south of Badger Flat (California co- ordinates, zone 4 ; 2,267,100 E., 590,600 N.). Monograptus dubius (Suess) Monograptus sp. (of the M. tumescens type) Monograptus sp. (plain thecae and long slender rhab- dosome) Age: Probably Ludlow. USGS colln. D160-SD. Collected in Al Rose Canyon about 1,500 feet southeast of D166-SD (California coordinates, zone 4; 2,267,500 E., 589,100 N.). Monograptus? sp. (This could be an M. vomerinus type form, but the remains are so twisted that determina- tion is difficult.) Age: Silurian?. USGS colln. D161-SD. Collected in Al Rose Canyon about 500 feet southeast of D166-SD (California coordinates, zone 4; 2,267,200 E., 590,200 N.). Monograptus _ sp. thecae) Age: Silurian. USGS colln. D162-SD. Collected from about 9,000 feet north- northeast of Johnson Spring (California coordinates, zone 4; 2,271,400 E., 583,600 N.). Monograptus sp. (of the M. vulgaris type) Monograptus cf. M. scanius Tullberg Monograptus sp. (slender rhabdosomes and plain thecae ; could be of M. dubius group) Age: Probably Early Ludlow. USGS colln. D179-SD. Collected near top of unit 5, measured section SC-2. About 150 feet above the base of the forma- tion (California coordinates, zone 4 ; 2,272,600 E., 575,800 N.). Monograptus cf. M. uniformis Pribyl Age: Early Devonian. This form is clearly a Monograptid of the M. hercynicus group known to be restricted to beds of Early Devonian (at least clearly post-Ludlow) age. In terms of systemic subdivisions, this form suggests an early Gedinne age for the beds bearing it. (slender rhabdosomes with plain Corals have also been recovered from bioclastic tongues of the Vaughn Gulch Limestone at several lo- calities. The following corals were identified and re- ported on by W. A. Oliver, Jr. (written commun., 1960, 1962) : Section SC-3, unit 8. Collected about 35 feet below top of formation, about 5,000 feet northeast of Johnson Spring (California coordinates, zone 4; 2,272,100 E.; 578,400 N.). Alveolites sp. Favosites sp. Cerioid rugose coral Cylindrical rugose coral 1-998-1. Collected about 3,000 feet east-northeast of Johnson Spring. Measured section SC-2, unit 11 (California coordi- nates, zone 4 ; 2,272,400 E., 575,700 N.). Alveolites sp. Thammopora sp. "Cystiphyllum" sp. Cylindrical rugose coral 1-2001-1. Collected about 60 feet below top of unit 5, measured section SC-1 (California coordinates, zone 4; 2,272,300 E., 570,000 N.). Favositoid coral Alveolitoid coral Cyathophylloid (?) coral 1-503. Collected from ridge just south of I-998-1 and about 3,000 feet east of Johnson Spring (California coordinates, zone 4 ; 2,272,400 E., 575,600 N.). Cladoporoid (?) coral Favositoid coral Horn corals (indet.) Oliver indicated that the age assignment based on these corals can be no closer than Silurian or Devonian. Other fossils have also been identified and reported by R. J. Ross, Jr. (written commun., 1960, 1961) as follows : USGS colln. D163-SD. Collected from side canyon east of Mazourka Canyon and about 1% miles north of Johnson Spring (California coordinates, zone 4; 2,270,600 E., 583,700 N.). Tentaculites cf. T. bellulus Hall USGS colln. D164-SD. Collected from east side of Al Rose Canyon about 1 mile south of Badger Flat (California coordi- nates, zone 4 ; 2,267,100 E., 590,600 N.). Brachiopods that probably are rhynchonellids. Preserva- tion is so poor that the genus is indeterminate. USGS colln. D178-SD. Collected near base of unit 4, measured section SC-3 (about 190 ft below top of formation) 4,500 feet northeast of Johnson Spring (California coordinates, zone 4; 2,272,500 E., 578,600 N.). Tentaculites cf. T. bellulus Hall Ostracodes Brachiopods Sponge spicules The best fossils for use in age determination in the Sunday Canyon Formation are the Monograptus grap- tolites, which have traditionally have been considered to be restricted to the Silurian. Recent work by Berry (1966) has shown that monograptids considered De- vonian in Europe are also present in the United States. Berry (written commun., 1964) examined most of the graptolite collections from the Sunday Canyon Forma- tion and concluded that both Silurian and Devonian monograptids are present. The only collection of De- vonian age (D179SD) was made about 150 feet above the base of measured section SC-2 (p. 57). The other collections, all of which are considered Silurian, are from very near the base of the formation. Thus, 34 STRATIGRAPHY OF PALEOZOIC FORMATIONS, on the basis of the graptolites, the lower 100 feet or so of the formation is most likely Silurian, and the overlying remainder of the formation may be Devonian. Pend- ing further work on other fossil forms in this part of the section, it seems best at present to consider the Sunday Canyon Formation to be Silurian and Devonian (?) in age. The Silurian graptolites are considered to be Middle to Late Silurian; so the Lower Silurian apparently either is missing or has not been recognized. It has already been suggested (see p. 29) that the Ely Springs Dolomite in the Independence quadrangle could be partly Silurian ; but for formational mapping purposes, the base of the Sunday Canyon Formation is the natural break, whether or not it coincides with the boundary between the Ordovician and the Silurian. No physical evidence of a break in deposition or of erosion has been noted at this contact, but poor exposure of the contact precludes much study. FACIES RELATIONS AND CORRELATIONS The Silurian and Lower Devonian in much of south- eastern California and in parts of southern Nevada is represented by cherty dolomite as typified by the Hidden Valley Dolomite in the Quartz Spring area ( McAllister, 1952, p. 15). Generally the dolomite is medium to light gray and contains considerable nodular chert, particu- larly in the lower part. Grossly similar rocks are also reported in the Nopah Range (Hazzard, 1937, p. 326), at the Nevada Test Site (Johnson and Hibbard, 1957. p. 350), and in the Darwin quadrangle (Hall and Mac- Kevett, 1962, p. 12). The dolomitic facies extends north and west into the New York Butte quadrangle, where chert-bearing dolomite of the Hidden Valley Dolomite is cut off by granitic intrusive rocks about 10 miles southeast of the Independence quadrangle. Only 3 miles to the east, in the Waucoba Wash quadrangle, similar rocks, probably correlative with the Hidden Valley, are also engulfed in granitic rocks. Thus, sev- eral miles of granite rocks separate the Silurian and Lower Devonian rocks of the dolomitic facies from the nearest presumably stratigraphically equivalent rocks in the Independence quadrangle, the Vaughn Gulch Limestone. Although the stratigraphic continuity is broken by the granitic rocks, there can be little doubt of the general stratigraphic equivalence of the Vaughn Gulch Lime- stone and the Hidden Valley Dolomite, and thus a substantial facies change is evident. A. paleontologic tie is also provided by the large dasycladacean algae Verticillopora annulata Rezak, which occurs in the Vaughn Gulch Limestone as well as in the Hidden Valley Dolomite of the New York Butte quadrangle (Merriam, 1963b, p. 13). INDEPENDENCE QUADRANGLE, CALIFORNTA In much of the central part of the Great Basin in Nevada, the Silurian is made up of the Roberts Moun- tains Formation, a thin well-bedded limestone contain- ing abundant fossils, and the overlying Lone Mountain Dolomite, a somewhat massive dolomite and dolomitic limestone (Merriam, 1940, p. 11-14). Descriptions of the Roberts Mountains Formation in the Eureka, Nev., area bear certain similarities to descriptions of both the Vaughn Gulch and the Sunday Canyon Forma- tions. Nolan, Merriam and Williams (1956, p. 37) described the Roberts Mountains Formation as com- prising dark-gray flaggy platy to shaly limestone, platy to shaly limestone that is in part silty, and many beds that are highly organic and yield abundant corals. Merriam (19632, p. 38) described Monograptus from the Roberts Mountains Formation at the type locality. Nolan, Merriam and Williams (1956, p. 37) also de- scribed limestones from the Monitor Range which con- tain abundant HMonograptus. In discussing correlation they stated, "In the Inyo Mountains in California the Silurian dolomites are locally replaced by a highly fossiliferous limestone facies: the fossil evidence indicates that these limestones are equivalent in part to the Roberts Mountains formation." - The highly fossiliferous limestone they refer to is the Vaughn Gulch Limestone at its type section. On the basis of the descriptions in the Eureka area, both the coral- rich Vaughn Gulch facies and the graptolite-bearing Sunday Canyon facies are considered to be at least partly equivalent and lithologically similar to what is called Roberts Mountains Formation in central Nevada. As was already noted by C. W. Merriam, the large dacycladacean algae Verticillipore an- nulata Rezak also provides a paleontologic tie be- tween the Roberts Mountains Formation and the Vaughn Gulch Limestone. The middle unit of the Roberts Mountains Formation at Bare Mountain, Nev. (Cornwall and Kleinhampl, 1961), has a strong litho- logic resemblance to the Vaughn Gulch Limestone. In the outcrops of the Roberts Mountains that I examined in Chuckwalla Canyon, the slabby-weathering limy, silty layers of the middle unit (some of which are rich in fossil fragments) look very similar to the Vaughn Gulch Limestone at the type section. The upper unit of the Roberts Mountains Formation at Bare Moun- tain, however, does not resemble the Vaughn Gulch but is more like the Hidden Valley Dolomite. Inas- much as the possibly correlative rocks in the Inde- pendence area are separated from Roberts Mountains Formation by rocks of the Hidden Valley Dolomite and by great distance, it seems best at the present to use local names for the Silurian and Devonian (?) rocks of the Independence quadrangle. J: MISSISSIPPIAN SYSTEM 35 The relation between the Hidden Valley Dolomite and the Vaughn Gulch Limestone may be somewhat similar to the relation between the Roberts Mountains and Lone Mountain Formations in the Roberts Moun- tains as described by Winterer and Murphy (1960, p. 118). They considered those two formations to be es- sentially time-stratigraphic equivalents, the Lone Mountain Dolomite representing a reef complex and the Roberts Mountains Formation representing an off- reef, deeper water facies. Granitic rocks intruded between the Hidden Valley and Vaughn Gulch Formations have blotted out the facies contact, but the Vaughn Gulch Limestone seems to be lithologically and genetically similar to the Roberts Mountains Formation. Hence reef conditions probably existed not far away, for the Vaughn Gulch is rich in off-reef-type bioclastic debris. Traced north- ward, the Silurian rocks in the Independence quad- rangle contain less bioclastic material and more silty material, and the environment becomes more favorable for graptolites. The gradation northward to this Sun- day Canyon facies thus seems to reflect an increasing distance from a reef environment. It seems logical to - presume, therefore, that a reef zone existed on strike to the south in the position now occupied by granitic rocks. - The Hidden Valley facies as now exposed in the New York Butte quadrangle would, by this interpreta- tion, represent the generally shallow-water carbonate deposits inshore from the reef complex whose debris was shed to form the Vaughn Gulch Limestone. Northwestward the Silurian outcrops terminate in the Badger Flat area owing to the combination of pre- Perdido erosion, granitic intrusion, and Cenozoic over- lap. These outcrops are the northwesternmost expo- sures of fossiliferous Silurian rocks found in the Great Basin ; in fact, such rocks have not been found for sev- eral hundred miles to the north and west. Silurian beds may be present in the thick stratigraphic section of the Mount Morrison roof pendant (about 50 miles northwest of the Sierra Nevada), where several thou- sand feet of unfossiliferous beds conformably overlie graptolite-bearing Ordovician rocks (Rinehart and Ross, 1964, p. 21-23). MISSISSIPPIAN SYSTEM PERDIDO FORMATION NAME AND DISTRIBUTION The Perdido Formation was named by McAllister (1952, p. 22) for exposures in the Quartz Spring area, about 25 miles east of the Independence quadrangle. A discontinuous belt of the Perdido Formation ex- tends almost the entire length of the quadrangle from Bee Springs north to the quadrangle boundary. Northwest of Badger Flat the Perdido is faulted and is cut out by granitic rocks, but it reappears in fault slices along the front of the Inyo Mountains in the Wau- coba Wash quadrangle (C. A. Nelson, written commun, 1961). The only other known occurrence of probable Perdido rocks to the north is on a ridge east of Jackass Flat, about 6 miles northeast of the northeast corner of the Independence quadrangle. There, C. A. Nelson, (oral commun., 1965) mapped and described clastic and carbonate rocks which are lithologically similar to the Perdido exposed in the Independence quadrangle. Beds assignable to the Perdido Formation are also present in the New York Butte quadrangle, but there they are thin and locally missing (Merriam, 1963b, p. 18). THICKNESS AND STRATIGRAPHIC RELATIONS The maximum measured thickness of the Perdido Formation in the Independence quadrangle is 623 feet near Vaughn Gulch. East of Pops Gulch the forma- tion is about 550 feet thick. Near Badger Flat the Perdido is probably somewhat thicker than 600 feet, but near Water Canyon it is considerably thinner. Many units in the formation are lenticular and coarsely clastic; so it is not surprising that the original thickness is variable. Moreover, the Perdido is tran- sitional with the overlying Rest Spring Shale; some vertical range in the upper contact, which is based on the uppermost carbonate-clastic lens against the overly- ing shale, also accounts for some thickness variation. The Perdido Formation lies on an eroded surface of Silurian rocks. Near Vaughn Gulch and northeast of Squares Tunnel, the erosional surface is particularly evident ; but north of Water Canyon the contact appears remarkably conformable, though presumably also an erosional contact. No cutting out of beds was noted at the contact studied north of Water Canyon, and the concordance of attitudes on both sides of the contact there gives no clue to an unconformity. The contact was particularly difficult to determine where shaly beds in the Silurian were adjacent to shaly beds in the over- lying Perdido. The contact was generally placed at the top of the somewhat limy. shale assigned to the Silu- rian; this shale is commonly lighter colored than the overlying noncalcareous shale assigned to the Perdido. Early in the mapping the contact was placed at the lowest appearance of medium- to coarse-grained clastic rocks, but this resulted in much shale being assigned to the Silurian that was similar to the shale above the lowest sand-size clastics of the Perdido. As mapping progressed, the contact of calcareous against essentially noncalcareous shale seemed to be a more significant mappable horizon-though no obvious evidence of ero- 36 STRATIGRAPHY OF PALEOZOIC FORMATIONS, sion was noted at either contact. The thinning out of the Sunday Canyon Formation northwest of Badger Flat, however, does suggest an erosional unconformity if it is not the result of strike faulting. The amount of time and the thickness of beds repre- sented by the unconformity is difficult to ascertain. Direct comparison with the conformable sections in the | New York Butte and Quartz Spring areas is not pos- | Slble because of probable facies changes (pl. 5). One | could speculate that at least the Lost Burro Formation (Middle and Upper Devonian), the Tin Mountain | Limestone (Lower Mississippian), and the lower part |_ of the Perdido Formation are missing in the Independ- \ ence quadrange. But if facies changes like those de- monstrable in the Ordovician and Silurian also occurred in the Devonian and Mississippian, facies equivalents of at least parts of the Lost Burro, Tin Mountain, and lower Perdido could be present in the Independence area, particularly north of Water Can- yon, and not be recognizable. North of Water Canyon the only fossil control on this erosional gap is based on Silurian and Devonian(?) fossils in the lower part of the Sunday Canyon Formation and Upper Mississip- pian fossils more than 1,000 feet above the Perdido Formation. An erosional surface is plainly present beneath the Perdido south of Water Canyon. Though regional relations suggest that some parts of both the Devonian and the Mississippian are missing at this unconformity, the Independence quadrangle could well conceal facies equivalents of either the Lost Burro or Tin Mountain that would considerably narrow down this erosional gap. LITHOLOGY In the type area of the Perdido, near Quartz Spring, McAllister (1952, p. 22) noted that "heterogeneity is an outstanding characteristic." This statement applies equally to the Independence area, where the Perdido is predominantly a clastic unit of shale, siltstone, con- glomerate, calcarenite, and calcareous quartz sandstone. Limestone and bedded chert, which typify the lower part of the Perdido in the Quartz Spring area, both are subordinate in the Perdido of the Independence area. Whether this difference is due to the absence of the lower part of the Perdido in the Independence area or to a facies change is a moot question. Recognizable changes in other units-for example, the Silurian and Devonian (?)-suggest that a facies change is more probable, and this is shown diagrammatically on plate 5. _ Although the Perdido Formation is notably hetero- geneous, it has a gross litholgy that makes it easily recognizable as a formation in the Independence area. INDEPENDENCE QUADRANGLE, CALIFORNIA ‘Photomicrograph of conglomeratic sandstone about 1% miles north of Johnson Spring; note abundance of chert fragments (ch) and of quartz (Q) in dark dense groundmass. Ficurp 18.-Perdido Formation. Upper: plane-polarized light. Lower: crossed nicols. Probably the most obvious single feature of the forma- tion is the abundance of black chert fragments in the coarser clastic rocks (fig. 18). This chert and the gen- erally abundant medium- and coarse-grained clastic rocks make much of the Perdido Formation stand as a resistant rib of outcrop between the bounding less resist- ant units. North of Water Canyon, however, much of the lower part of the formation is composed of shale, and the contact with the underlying shaly Silurian and Devonian (?) rocks is much less obvious. No attempt will be made to systematically describe the multitude of rock types in the Perdido. The meas- ured sections (P-1, -2, -3, p. 58-60) are representative and give some idea of the range of rock types. Cer- tain distinctive rock types that are diagnostic of the Perdido in the Independence area are described in the following paragraphs. As previously noted, chert fragments are diagnostic of the coarser clastic rocks of the Perdido. Particu- MISSISSIPPIAN SYSTEM 37 larly distinctive is medium-gray to medium-dark-gray chert granule conglomerate composed largely of rounded chert fragments as much as 10 mm in diameter but containing some fragments as small as a fraction of a millimeter in diameter. Some beds are remark- ably well sorted and have chert grains averaging 3-4 mm in diameter. Radiolarian tests are common in some chert fragments. Quartz grains are present, but, characteristically, chert is dominant. - Chert fragments also dominate in some coarser conglomerate beds; these chert clasts are well rounded and several inches or more in largest dimension. Another Perdido rock type, large-boulder conglom- erate, is exposed on both sides of Vaughn Gulch. Boulders of quartzite and carbonate as much as 15 and possibly 20 feet in diameter are scattered through a rather thin unit in the lower part of the formation. Smaller boulders are also present. The matrix is a mixture of sandy and limy material. Unit 6 of meas- ured section P-1 (p. 59) is an example of this layer. At other localities farther north where fairly coarse conglomerate is present, few boulders exceed 1 foot in maximum diameter, and most are only a few inches in maximum size. According to Merriam (1963b, p. 19), some of the carbonate boulders in the large-boulder conglomerate are similar to rock types in the Lost Burro Formation (Devonian). Also in the Perdido is a group of rocks composed of various proportions of sand-size calcite and quartz clasts; fragments of chert and feldspar are subordinate. These beds, which were generally referred to in the field and in some of the measured sections as "sandy-limy layers," are chiefly medium gray (some weather brown) and range from thin bedded to massive; most are lenticular. Locally these beds are made up almost exclusively of quartz grains and are orthoquartzites, but most are composed predominantly of clastic calcite frag- ments. - Generally these rocks could be called calcareous quartz sandstone or calcarenite; calcarenite with 50-75 percent calcite fragments is most common. The calcite fragments as much as 3 mm in diameter are present, but the majority are 0.25-1 mm in diameter,; some patterned fragments are obviously fossil fragments. The quartz fragments are as much as 0.75 mm in diameter. Both calcite and quartz grains, as small as 0.05 mm in diame- ter, make up the groundmass. The clasts range from subangular to well rounded ; generally, the coarser frag- ments are the more rounded. __ Bedded chert, which is not common in the forma- tion, forms a distinctive and widespread marker unit in the lower part of the formation. (See unit 4, section P-1, and unit 2, section P-3, p. 59, 60.) This chert is black and thinly and regularly bedded and contains elongate light-gray lenses composed of somewhat coarser material and less carbonaceous material. The origin of the light-gray lenses in unknown, but some lenses contain abundant apatite. - Scattered in the chert beds are round areas as much as 0.15 mm across that are apparently devoid of dark, carbonaceous material and contain quartz that is coarser grained than the chert matrix; these areas may be evidence of Radio- larian tests. Shadowy elongate needlelike outlines in the chert may be sponge spicules. Another rock type that is locally common superficially resembles vesicular basalt, particularly on a weathered surface. - This rock is clastic, however. -It is composed of sand- to granule-size fragments in a dense ground- mass rich in carbonaceous material. The vesicular, porous aspect of this rock is its most diagnostic feature. Presumably the holes resulted from calcite fragments (many of them fossil fragments) being leached out. Commonly the holes are coated with red-brown iron oxide, which preserves fossil imprints, mostly of pel- matozoan fragments. (See fossil colln. 1-940, p. 37.) These rocks are most common west of A1 Rose Canyon. In addition to these lithologic types, which, though unusual, serve to characterize the Perdido of the Inde- pendence quadrangle, there is an abundance of shale and siltstone. - These form dark outcrops that in most places weather red brown and give the formation its predominant reddish-brown weathering color. In such a heterogeneous formation, it is virtually impossible to assign percentages to the various rock types. The coarse clastics are noticed and sampled beyond their importance, and the prosaic shale and silt- stone are apt to lack attention. Approximate calcula- tions from the three measured sections show about 55 percent shale and siltstone, 25 percent calcarenite and calcareous quartz sandstone, 15 percent conglomerate, and 5 percent of sandstone, quartzite, and chert. Although these percentages may not be valid for the whole formation in the Independence quadrangle, they probably show an approximate composition. FOSSILS, AGE, AND CORRELATION Fragments of brachiopods, corals, bryozoans, trilo- bites, and pelmatozoans have been recovered from the Perdido Formation. Most of the fossils are poorly preserved molds, and many are distorted ; so the collec- tions made thus far are of little help in determining the age of the Perdido. In addition, evidence of Radiolarian and sponges is found in some of the chert. The following collection was examined and commented on by Mackenzie Gordon, Jr. (written commun, 1964) : 1-940. Collected from porous crinoidal clastic rock from near the top of the Perdido Formation, 2,100 feet N. 73° W. of 38 SE cor. see. 25, T. 11 S., R. 35 E. (California coordinates, zone 4 ; 2,263,000 E., 592,800 N.). Horn coral indet. Crinoid columnals Strophomenoid? brachiopod indet. Reticulariina sp. indet. All these fossils are distorted. The ribs of the Reticulariina are stretched so that they are wide on one side and nar- row on the other. The species has four plicae at either side of the fold and may be R. campestris (White), which is found in rocks of Chester and Morrow age in the western United States; however, this specimen is too poorly pre- served to be identified with any sense of assurance. STRATIGRAPHY OF PALEOZOIC FORMATIONS, Cravenoceras and associated fossils of Late Missis- sippian age (Chester) were reported from near the top of the formation at its type area, near Quartz Spring (McAllister, 1952, p. 24). In the same refer- ence McAllister also reported on fossils at the base of the Perdido Formation in the southwestern part of the Ubehebe Peak quadrangle that may be late Kinderhook or Osage (Early Mississippian). On the basis of fos- sils from the upper part of the formation in the type area (rocks which resemble the Perdido of the Inde- pendence area) and fossils in the Cerro Gordo area, the Perdido of the Independence area is tentatively con- sidered to be Late Mississippian. The outcrops of the Perdido Formation closest to Independence exposures are in the New York Butte quadrangle. - There the formation is generally less than 100 feet thick and is locally absent (Merriam, 1963b, p. 19). The Perdido is characteristically of diverse lithology at some sections and is entirely fine-grained sandstone and quartzite at others. Merriam (1963b, p. 22) believed that the Perdido in the New York Butte quadrangle has been partly replaced by a shale which he referred to the Chainman Shale of Late Mis- sissippian age. Fossils found in the lower part of _ Merriam's Chainman are similar to some found in the type section of the Perdido. This relation is certainly in accord with the transitional nature of the upper contact of the Perdido Formation in the Independence quadrangle. The presence or absence of the lenticular coarser clastic beds of the Perdido results in an inter- fingering contact with the overlying shale (pl. 5). Furthermore, considerable variation in total thickness of a lenticular clastic unit like the Perdido seems probable. A report by Gordon (1964, p. A2-A¢A6) has a detailed discussion of the age and correlation of the Perdido Formation in the Inyo-Panamint region. The northernmost rocks that are assignable to the Perdido are in the Jackass Flat area, about 6 miles northeast of the Independence quadrangle, and in the fault slices along the front of the Inyo Mountains in the Waucoba Mountain quadrangle. These rocks have INDEPENDENCE QUADRANGLE, CALIFORNIA the typical coarse to fine clastic diversity of the Perdido and also have abundant chert clasts. In the Darwin area (pl. 5) Hall and MacKevett (1962, p. 20) described chert and limestone strata, which they considered to be the lateral equivalent of the lower part of the Perdido type section, and the over- lying silty Lee Flat Limestone (Upper Mississippian and Pennsylvanian ?), which they interpreted to be the lateral equivalent of the upper part of the Perdido and the overlying Rest Spring Shale. This sequence, if the | correlation is correct, represents a rather drastic change | in the Perdido, and it is another instance of an increase | in carbonate southeastward in the section. Such a facies change is in accord with facies changes that occur in other formations in this area. Farther east and north the Mississippian is again represented by dominantly clastic rocks. Probably a Perdido equivalent is present in the nearly 8,000 feet of argillite, siltstone, quartzite, conglomerate, and lime- stone of the Eleana Formation (Mississippian to Lower Pennsylvanian) at the Nevada Test Site area (Poole and others, 1961, p. D104). Similar rocks, probably also at least partly correlative with the Perdido, are present in a faulted section more than 3,000 feet thick at Bare Mountain, Nev. (Cornwall and Kleinhampl, 1961). Outcrops of the Meiklejohn Formation (Upper Mississippian) on the east side of Bare Mountain north of Tarantula Canyon have coarse clastic lenses rich in chert fragments interbedded with shale and siltstone and are very similar to Perdido outcrops.. Coarse clas- tic material, which characterizes the lithology of the Perdido Formation, is present throughout nearly all the Meiklejohn Formation (Cornwall and Kleinhampl, 1961). At Bare Mountain, therefore, a clear distinc- tion between a coarser grained facies equivalent to the Perdido and a finer grained facies equivalent to the Rest Spring is not readily made. The overall resem- blance of the Meiklejohn to the Perdido plus the Rest Spring leaves little doubt about their general equivalence. The clastic rocks, both fine- and coarse-grained, which typify the Perdido Formation in the Inyo Mountains appear to be replaced southward by carbon- ate rocks, as can be seen in the Darwin area. Farther south the Mississippian section is also dominantly car- j} bonate and chert, as reported from the Nopah Range h (Hazzard, 1937, p. 275) and in the Ivanpah quadrangle | (Hewett, 1956, p. 42). North and east of Independ- ence, the Perdido (and the entire Mississippian section) is predominantly clastic. Poole, Houser, and Orkild (1961, p. D109) considered the Eleana Formation to represent part of a clastic apron shed from the northeast-trending Antler orogenic belt (Roberts and MISSISSIPPIAN SYSTEM others, 1958) to the northwest. This would explain the southeastward facies trend to more carbonate de- posits as a reflection of increasing distance from an orogenic belt. REST SPRING SHALE NAME AND DISTRIBUTION The Rest Spring Shale was named by McAllister (1952, p. 25) at exposures in the Quartz Spring area. In the Inyo Mountains, dark-colored fine-grained clas- tic rocks now assigned to the Rest Spring were first called White Pine Shale by Kirk (in Knopf, 1918, p. 38). Rocks now considered to be the Perdido Formation were also included in the White Pine Shale by Kirk. In the New York Butte quadrangle, Merriam (1963b, p. 20) used the term Chainman Shale for this same in- terval. Chainman is a name derived from the Ely dis- trict of Nevada (Spencer, 1917, p. 26-27) and is widely used in eastern Nevada. The Rest Spring Shale crops out in a broad arcuate belt from west of Badger Flat to the mouth of the Mazourka Canyon. Disconnected fault segments con- tinue south to the Bee Springs area. North of the quadrangle, along the front of the Inyo Mountains in the Waucoba Mountain quadrangle, a small amount of the Rest Spring Shale occurs above the Perdido (C. A. Nelson, written commun., 1961) ; both formations are faulted against Cambrian beds. This is the north- westernmost known occurrence of the Rest Spring Shale. THICKNESS AND STRATIGRAPHIC RELATIONS Along a section east of Pops Gulch, 2,475 feet of beds were measured in the Rest Spring Shale. From aerial photographs and the trend of the bounding formations, the section appears to be relatively homoclinal; some folding has been observed along the section (fig. 19), however, and discontinuous beds suggest that the section may also be faulted. Probably 2,500 feet is a fair esti- mate of the thickness in the Independence quadrangle. In the Quartz Spring area (McAllister, 1952, p. 25-26) the Rest Spring Shale may be considerably thinner (pl. 5), as a maximum of only 400 feet was measured, but the combination of complex structure and an incompetent shale means that little confidence can be placed in this measurement. - In the Darwin area (Hall and MacKev- ett, 1962, p. 19-21) only a small amount of Rest Spring Shale is exposed in fault zones, and the formation is be- lieved to intertongue with and be laterally replaced by the Lee Flat Limestone. - In the New York Butte quad-, rangle (Merriam, 1966, p. 21) about 1,000 feet of shale! occupies this interval, but here also the true thickness is doubtful because of structural complications. 39 Exposed in bluff east of Pops Gulch. Boy in white shirt at base FIGURE 19.-Rest Spring Shale. Note rather tight folding near skyline. of cliff for scale. Despite the uncertainty about the true thickness of the Rest Spring Shale and its equivalents, the formation seems to thicken notably to the northwest. The contact with the underlying Perdido Formation is gradational and transitional. The close relation of the two formations is shown by the intertonguing of the coarser clastics of the Perdido with the finer clastics of the Rest Spring. The contact is arbitrarily placed at the top of the uppermost medium- to coarse-grained clastic rock, although its stratigraphic level probably varies somewhat throughout the quadrangle. The up- per beds of the Rest Spring Shale appear to be con- formably overlain by the carbonate beds of the Keeler Canyon Formation. LITHOLOGY The Rest Spring Shale crops out in a dark-colored band for almost the entire length of Mazourka Canyon. The color of fresh faces ranges from medium dark gray to black, and that of weathered surfaces also is gen- erally dark. Some black layers weather to light-gray, almost silvery, surfaces; dark-reddish-brown weather- ing is also common, particularly on smooth, desert- varnished surfaces. Much of the formation has been hornfelsed by the action of the large granitic mass to the west along the front of the Inyo Mountains. Originally the Rest Spring Shale had been a rather monotonous sequence of shale, mudstones, siltstone, minor fine-grained sandstone, and rare limestone. Where less hornfelsed as in the eastern part of the outcrop belt, the rocks are laminated to very thin bedded. Parting is generally shaly to flaggy but is slabby to blocky in some places, particu- larly where the rocks are more hornfelsed. East of Pops Gulch, where the section is relatively homoclinal, 40 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA the beds in the upper part of the formation are more massive. Though some bedding and parting may re- flect differences in original sediments, much is the result of the alteration to hornfels; metamorphic minerals are more abundant in the more massive part of the forma- tion, which is nearer the granitic body. Andalusite hornfels and spotted hornfels rich in seri- cite, which is at least partly the result of alteration of andalusite, are the most common rock types in the for- mation. - Andalusite crystals from a fraction of a milli- meter to several millimeters long are liberally sprinkled through many specimens. Some of the andalusite is fresh and exhibits the typical crosslike alinement of in- clusions (chiastolite), but more commonly it is partly altered to sericite or completely pseudomorphed by sericite. Many rocks contain scattered sericite that cannot be attributed to alteration of andalusite. This sericite presumably formed from the metamorphism of clay minerals. Phlogopite and chlorite are also widespread. The metamorphosed siltstones are composed of rounded to subangular quartz clasts from 0.05 to 0.25 mm in diameter scattered through a denser groundmass of various proportions of quartz, sericite, phlogopite, and chlorite. - Locally the percentage of quartz increases and the rock is fine-grained quartzite, but this is not common. Black organic material is common and widespread. One zone near the middle of the formation is particu- larly rich in carbonaceous material. This zone, which is several hundred feet wide, has been mapped for about 2 miles along the strike. It is probably lenticular, as it is not mappable beyond this segment and seems to merge with the other rocks of the formation. Within this carbonaceous layer goniatite fragments were recovered. A sample of this organic-rich layer from the principal goniatite locality (I-10) was submitted for semiquanti- tative spectrographic analysis. The following results were reported (J. D. Vine, written commun., 1963) : [Results are reported in percent to the nearest number in the series 1, 0.7, 0.3, 0.2, 0.15, 0.1, and so on, which represent approximate mid- points of group data on a geometric scale. The assigned group for semiquantitative results will include the quantitative value about 30 percent of the time] Ti- Or 0.05 0.005 Mn-..--:-. 003 0015 Set. 0083 ABL 0002 s.. 003 08 .08 HAZ.... 015 Yale .05 15 0015 0083 0005 Nd-.L....s: 007 Yb J...... 0005 .03 Niss Le: 001 no 02 Several other specimens of black shale from this goni- atite-bearing layer and other nearby localities in the Rest Spring were also spectrographically analyzed, and the concentrations of minor elements were about the same as in I-10 (J. D. Vine, written commun., 1963). FOSSILS, AGE, AND CORRELATION Fossil remains are scarce in the Rest Spring Shale, partly owing to the metamorphism of the formation, but a variety of forms have been recovered from two localities; plant-stem remains and possible worm bor- ings (fucoids) have been found elsewhere. Cravenocerid goniatite fragments were found about 1,300 feet east-northeast of Johnson Spring in a carbo- naceous-rich zone about 800 feet above the base of the formation (loc. I-10, California coordinates, zone 4; 2,270,500 E., 575,500 N.). These fossils were assigned a Late Mississippian age by Mackenzie Gordon, Jr. (written commun., 1961) : Two cravenocerid genera are already known in the Inyo Range in the Cerro Gordo area (New York Butte quadrangle), California. These are Cravenoceras and Cravenoceratoides. Cravenoceras is known at many localities in the United States, but Cravenoceratoides, a British genus, is known in the United States only in the Inyo Range, Calif., and the Diamond Range, Nev. It differs from Cravenoceras principally in the bifurca- tion of transverse lamellae on the inner part of the flanks. Most fragments collected in the Independence quadrangle are from the ventral part of the shell and would not show bifurca- tion even if the genus were Cravenoceratoides. One specimen appears to show bifurcation in one place, but this is not enough to go on. As Cravenoceratoides is the common cravenocerid in the Chainman Shale in the Cerro Gordo area, the present frag- ments may also belong in this genus. Some carbonate-rich specimens from the cravenocerid zone were disaggregated-using Schulz's Solution, sodium hypochlorite, and hydrofluoric acid-in an at- tempt to recover spores. Black organic particles were separated, but no spores were found (R. A. Scott, writ- ten commun., 1961). The other fossil collection was made about 285 feet below the top of the formation at the mouth of Pops Gulch. Most of the material is fragmental and poorly preserved, but considering that the matrix is andalusite hornfels, the collection is proof that fossils can survive metamorphism, at least locally. Mackenzie Gordon, Jr., reported as follows on this collection (written commun., 1963) : USGS colln. 20588-PC. Collected at mouth of Pops Gulch about 285 feet below the top of the Rest Spring Shale (California coordinates, zone 4 : 2,266,700 E., 581,200 N.). Fenestello sp. Crinoid plates Crinoid columnals Choneted indet. Heteralosia (?) sp. Semicostella (?) sp. Inflatia (?) sp. indet. sp. MISSISSIPPIAN SYSTEM 41 Linoproductus (?) sp. (small species) Spirifer aff. 8. increbescens Hall Spiriferoid, indet. Pelecypods, indet. Gastropod, indet. Goniatites, indet. (evolute form) Fossil plant This assemblage appears to have more in common with the Late Mississippian fauna than with the Early Pennsylvanian one. But, because of the preservation of these fossils as distorted molds, which precludes positive identification of species, one can only speak in general terms. The surpris- ing thing is that they are as well preserved as they are in this thoroughly metamorphosed matrix. The forms upon which a probable Mississippian age deter- mination is based include the supposed Heteralosia, recognized by its shape and scattered short semiprostrate spines. A similar form, as yet undescribed, occurs in the Upper Missis- sippian beds in western Utah. The avoniid here identified as Semicostella? likewise is indicative of Mississippian age, as no similar forms are known in the Pennsylvanian in this region. Also, the Flezaria resembles an undescribed Late Mississippian species. This genus is also represented in the Early Pennsylvanian by a large undescribed species, but this does not appear to be it. The goniatites, although they can- not be identified even as to order, in the absence of sutures and clear external features, resemble several Mississippian forms superificially. They do not resemble any of the known Pennsylvanian species in the Great Basin, most of which are gastrioceratids. Finally characteristic Early Pennsylvanian brachiopods, such as Rugoclostus and large linoproductids, are absent. Southeast of the Independence quadrangle Kirk (in Knopf, 1918, p. 38-39) made a collection about 114 miles north of the Cerro Gordo mine from fissile black shale that is referred to the Chainman by Merriam. This collection comprises mostly pelecypods and cepha- lopods. G. H. Girty (in Knopf, 1918, p. 39) made the following comment about that early collection: "* * * an interesting and peculiar fauna of the Caney Shale of Oklahoma and the related but less well known fauna of the White Pine Shale of Nevada. These faunas I refer to the Upper Mississippian." Abundant fossils have also been collected and re- ported on from the lower 400 feet of the Chainman Shale in the New York Butte quadrangle (Merriam, 1963b, p. 22) ; so far no fossils have been found in the upper 600 feet. Most distinctive are the cravenocerid goniatites, which are regarded as of Late Mississippian age (Merriam, 1963b, p. 23). Merriam thus regarded the Chainman Shale of the New York Butte quad- rangle as Upper Mississippian, although he acknowl- edged the possibility that the upper, unfossiliferous part may be Lower Pennsylvanian. In the Quartz Spring area, where the Rest Spring Shale was named, McAllister (1952, p. 26) reported that fossils are very scarce but include impressions of reedlike leaves, bryozoan fragments, and poorly pre- served microfossils. In the southwest corner of the Ube- hebe Peak quadrangle, fossils were collected from met- amorphosed shale at only one locality. J. S. Williams reported as follows on those fossils (McAllister, 1952, p. 26) : Impressions or fragmentary remains suggest brachiopods be- longing possibly to the genera Chonetes, Marginifera, and Composita, but even the generic identifications are uncertain. The fragmentary remains have slightly, but very slightly, more resemblance to Pennsylvanian species of these genera than to Mississippian species, but the age might as well be Mississipian as Pennsylvanian. McAllister further noted that the uncertain identifica- tion of these poorly preserved fossils cannot be used to determine the age of the Rest Spring Shale. Arbi- trarily, but provisionally, he placed the boundary be- tween the Mississippian and the Pennsylvanian at the base of the Rest Spring Shale, chiefly because, as he stated (1952, p. 26), "the formation lies above the Late Mississippian fauna in the uppermost part of the Perdido Formation and below the moderately early Pennsylvanian fauna in the lowest part of the Tihvipah Limestone." Further discussion of the age and cor- relation of the Rest Spring and Chainman in the Inyo- Panamint region is found in a report by Gordon (1964, p. A2-A6). The fossil collections from the Mazourka Canyon area support the assignment of a Mississippian age to the Rest Spring Shale in the Inyo Mountains. Absence of fossils in the uppermost 600 feet of the 1,000-foot-thick Chainman Shale in the New York Butte quadrangle and in the uppermost 285 feet of the 2,500-foot-thick Rest Spring Shale in the Independence quadrangle suggests that the upper part of the formation may in- clude Pennsylvanian strata, but the only diagnostic fossils from this shale are Upper Mississippian. Fol- lowing the convention of assigning an age to a forma- tion on the basis of available fossil data, even though fossils are absent in part of the formation, it is prefer- able at present to restrict the age of the Rest Spring to the Late Mississippian. The Rest Spring Shale of the Independence quad- rangle undoubtedly has lithologic correlative counter- parts in the Eleana Formation of the Nevada Test Site (Poole and others, 1961, p. D104) as well as the clastic Meiklejohn Formation at Bare Mountain, Nev. (Cornwall and Kleinhampl, 1961). Although specific correlations cannot be made because of distances involved and the variability of these clastic units, the Rest Spring, together with the Perdido and the correlative units mentioned above is considered to be part of a vast late Paleozoic clastic blanket which is 42 STRATIGRAPHY OF PALEOZOIC FORMATIONS, typified by the Chainman Shale and the Diamond Peak Formation of eastern Nevada (Nolan and others, 1956, p. 59-61). GREAT BASIN STRATIGRAPHIC AND STRUCTURAL BACKGROUND AND SETTING The Paleozoic stratigraphy of the western part of the Great Basin can be generalized by grouping the rocks into major assemblages that have lithologic con- tinuity and great geographic extent. An excellent summary of this stratigraphic picture and an interpre- tation of the structural development of this area in the Paleozoic was published by Roberts and others (1958). That report is the basis for the following summary. Deposition in this area during the Cambrian through the Devonian is represented by three assemblages, one of which is lithologically and geographically transi- tional between the other two. The first assemblage, which is widespread in eastern Nevada and southeastern California, is predominantly carbonate, comprising limestone and dolomite and smaller amounts of shale and quartzite. It has variously been called the eastern facies, the carbonate facies, and the miogeosynclinal eastern assemblage, but it is now generally refered to as the carbonate assemblage. In central and western Nevada, correlative strata aro mostly fine- to medium-grained siliceous clastic sedi- mentary rocks, chert, and volcanic rocks. These rocks have been called the western or eugeosynclinal, facies or assemblage and the clastic facies, but they are now called the siliccous assemblage (R. J. Roberts, oral commun., 1963). This assemblage was deposited in a eugeosynclinal environment, in contrast to the carbonate assemblage, which represents miogeosynclinal deposi- tion (Stille, 1940, p. 15). In some places in Nevada, particularly in the Osgood Mountains, an assemblage transitional between the car- bonate and siliceous assemblages has been recognized (Hotz and Willden, 1955). This assemblage is a mix- ture of carbonate, clastic, and volcanic rocks. The deposition of these three assemblages continued in their respective areas in the Cordilleran geosyncline until near the end of Devonian time, when orogenic movements began to affect a broad region (the Antler orogenic belt) generally coincident with the area of deposition of the transitional assemblage. Intense folding and faulting, including major thrusting along this emergent belt, lead to the deposition of a coarse clastic apron that spread both east and west. This coarse clastic apron, which grades laterally into fine- grained clastics and limestone, comprises Mississippian, Pennsylvanian, and Permian strata and is termed the INDEPENDENCE QUADRANGLE, CALIFORNIA overlap assemblage, as it was deposited over deformed strata of the carbonate, siliceous, and transitional as- semblages. PALEOZOIC SECTION OF THE INDEPENDENCE QUAD- RANGLE AS RELATED TO PALEOZOIC HISTORY OF THE WESTERN GREAT BASIN The Independence quadrangle and the Paleozoic roof | pendants in the eastern Sierra northwest of the Inde- | pendence quadrangle are in line with the north- northeast-trending Antler orogenic belt (fig. 1). In addition, the Independence Paleozoic section exposes the westernmost recognizable outcrops of several Great Basin formations. Thus, this quadrangle is stratigi- cally located, both structurally and stratigraphically, | for studies of the Paleozoic history of the western part | of the Great Basin. § Cambrian, Ordovician, Silurian, and Devonian(?) deposits in the Independence area are characterized by thin-bedded and well-bedded fine- to medium-grained clastic rocks and carbonate (both dolomite and lime- stone) and clean quartz sand that is extremely well rounded and well sorted; sand with carbonate cement is common in the Lower Cambrian and Middle Ordo- vician strata. - Much of the carbonate in the Ordovician, Silurian and Devonian (?) rocks is calcarenite and cal- cilutite, and many of the carbonate formations contain abundant ~silt-size quartz fragments. Crossbedding and ripple marks were seen at several localities. Clastic rocks, including the calcarenite, make up nearly half the Cambrian to Devonian (?) section. These Cambrian to Devonian (?) sedimentary rocks | have general characteristics that would class them as shelf or platform deposits; such characteristics are as- sociated with sediments deposited above wave base or in the foreland facies. Such sediments would have been deposited in an environment such as that of Stille's (1940) miogeosyncline. Though miogeosynclinal in general character, these strata differ somewhat from the carbonate assemblage of eastern Nevada and south- eastern California. Clastic material is more common in the Lower Ordovician rocks, chert becomes predom- inant in the Upper Ordovician rocks, and clastic ma- terial, including graptolitic beds, is significant in the Middle Ordovician rock and dominates in the Silurian and Devonian(?) rocks. Details of these regional var- iations are cited under the individual formations de- scribed in this report. Only a few miles southeast of the Independence quadrangle, the lower Paleozoic of the New York Butte quadrangle is a typical carbonate assemblage (W. C. Smith, written commun., 1961). Similar typical carbonate-assemblage rocks make up STRATIGRAPHIC the lower Paleozoic strata in the Darwin area (Hall and MacKevett, 1962, p. 6) and the Quartz Spring area (McAllister, 1952, p. 8), as well as large areas to the south and east. The Independence quadrangle thus stands near the east margin of the transitional as- semblage and has close geographic and stratigraphic ties to the carbonate assemblage. On a strike continuation northwest of the Independ- ence area, the nearest rocks in the age range of Cam- brian through Silurian and Devonian(?) are 50 miles away, in the Mount Morrison roof pendant of the Sierra Nevada. There, possibly 25,000 feet of mostly Ordovician strata, chiefly fine-grained clastic rocks and calcareous quartz sandstone, have been mapped. These rocks are also part of the transitional assemblage, but they have more aspects of the siliceous assemblage and were presumably deposited deeper in the geosyneline than the Independence rocks. ) The folding and faulting which characterized the) middle Paleozoic Antler orogeny in Nevada did not! extend into the Independence area. However, a major: stratigraphic break marked by Upper Mississippian | clastic rocks deposited on the eroded surface of the} Silurian and Devonian(?) rocks probably reflects this' orogeny. The contact between the Mississippian and Silurian and Devonian(?) rocks is obviously marked by erosion where Silurian and Devonian (?) beds have been cut out, but in many places it appears conformable and shows little evidence of a break. To the south- east at Darwin, New York Butte, and Quartz Spring (fig. 1), sedimentation continued uninterrupted throughout the middle Paleozoic. Apparently the effects of the Antler orogeny are not reflected southeast beyond the Independence area. In the Candelaria Hills of southern Mineral County, Nev. (fig. 1), strongly folded Ordovician rocks of the siliceous assemblage are unconformably overlain by Permian clastic rocks (Ferguson and others, 1954). There the effects of the Antler orogeny include folding, whereas at Independence only uplift and erosion are evident. In the Mount Morrison pendant in the Sierra, which lies northwest of the Independence area and southwest of the Candelaria Hills, fine-grained clastic rocks of Pennsylvanian age are in fault contact with Ordovician rocks and unfossiliferous rocks that are lithologically similar to the Ordovician rocks (Rinehart and Ross, 1964, p. 84). Though structural complications pre- clude any definite statement, it is possible that an erosional gap is present in this area also. The Perdido Formation-a variety of coarse clastic rocks, siltstone, shale, and calcareous quartz sand- stone-and the overlying Rest Spring Shale total about 43 SECTIONS 3,000 feet of strata that probably belong to the overlap assemblage of the Great Basin. The Perdido, which is characterized by abundant chert pebbles, cobbles, and boulders, probably reflects a source area north or west of the Independence quadrangle. Chert in beds thick enough to yield boulders the size of those present in the Perdido is rare in the Independence area (only in the Ely Springs Dolomite near Badger Flat) and , is likewise rare south and east of the quadrangle. | Southward from the Independence quadrangle the | thickness of clastic rock in the Perdido-Rest Shale in- | terval decreases rapidly, and the proportion of coarse | siliceous clastic rocks in the Perdido likewise decreases. Hall and MacKevett (1962, p. 20) suggested that in the Darwin area, a limestone unit (Lee Flat Limestone) laterally replaces the clastic interval of the upper part of the Perdido Formation and the Rest Spring Shale. Thus the coarse-grained overlap-assemblage rocks of the Upper Mississippian grade out rapidly to the south. Thick sequences of clastic rocks of Mississippian age are recognized in the Bare Mountain, Nev. (Cornwall and Kleinhampl, 1961) area, about 55 miles east of | Independence, and at Quartzite Mountain (Poole and others, 1961), about-100 miles northeast of the quad- rangle. The suggestion is that the general facies boundary between clastic and carbonate rocks of the Mississippian has more of an easterly trend than a northerly trend in this region. The Pennsylvanian and Permian strata are not dis- cussed in this report, but they are probably part of the overlap assemblage. The Keeler Canyon Formation (Pennsylvanian and Lower Permian) reflects a period of chiefly carbonate deposition between the periods of Mississippian and Permian clastic deposition. The Owens Valley Formation (Permian) is predominantly fine-grained clastics but is overlain by at least 500 feet of sand- to cobble-size clastic rocks in which quartzite and chert clasts are dominant. These coarse clastic beds, which grade out rapidly to the southeast and are not known in the Mount Morrison roof pendant, may reflect some fairly local uplift. STRATIGRAPHIC SECTIONS BK-1. About %, mile east of Blue Bell mine, NEV, sec. 24, T. 11 & N., R. 35 E. Lead Gulch Formation. Conformable contact. Bonanza King Dolomite: Feet 5. Dolomite, medium-gray to medium-dark-gray ; weathers light gray to yellowish gray; mas- sive; poorly bedded; fetid; some coarse grained and 205 1 44 BK-1. About %, mile east of Blue Bell mine-Continued Bonanza King Dolomite-Continued 4. Dolomite, dark-gray; weathers medium gray; laminated irregular nodular bedding; platy to flaggy parting; overall aspect of slope is varied gray beds as much as several feet thick; minor black chert near base; coarser grained, lighter, irregular patches of dolomite weather out, in some beds, leaving a darker dolomite matrix_. 3. Dolomite; higher proportion of darker colored beds (evident both on ground and in aerial photographs) ; upper and lower contacts rather sharp in aerial photographs; scattered mica and tremolite(?) ; some chert; G@irvanella (?) about 160 ft below top; irregular nodular bed- ding and "dappled gray" surface common-___. 2. Dolomite, various shades of gray; laminated to very thin, irregular bedding; platy to flaggy parting; much higher proportion of lighter beds; rather abrupt color break with overlying unit in aerial photographs; fucoidal beds lo- cally prominent; color bands from few inches to several feet thick 1. Dolomite, about same as unit 2 but has more dark beds; distinction of this unit is abundance of Girvanella (?) from % to 1 in across, as well as fucoids and other worm-trail-like markings, some of which are filled with coarser, lighter dolomite .... . - _. . susan un elie aiken an ue ant an aa s STRATIGRAPHY OF PALEOZOIC FORMATIONS, Feet 524 564 1, 026 504 Total Bonanza King Dolomite______________ 2, 823 Contact covered, presumably conformable. Monola Formation. LG-1. Type section of the Lead Guich Formation, in spur along east wall of Mazourka Canyon, 7,500 feet S. 85° E. from SH gor. se6. 30, T. 11 8., R.85 E. Tamarack Canyon Dolomite. Conformable contact. Lead Gulch Formation : Feet 7. Limestone, medium-dark-gray ; interbedded with orange-weathering silty beds; both types in beds 441 in. thick.. 52 6. Covered ________ 3 15 5. Dolomite,*medium-dark-gray ; very thin bedded; irregular _ceci4u osu 44 B :. 2 non ol n rae Ln eben ne a ae cons 35 3. Dolomite, medium- to dark-gray ; thin platy beds 5 2. Covered (scattered platy dolomite float; frag- ments of Lh HIG) ='... see cls ol arine ot ed wane HC ool ae me meas 50 1. Limestone, medium-bluish-gray; laminated to very thin bedded ; interbedded %4-in.-thick lay- ers of weathering gray to orange siltstone; some black chert in nodular beds as much as 4 in. thick; Lingula present; beds near base folded: contact contorted _____________L______ T9 Total Lead Gulch Pormation..____________ 280 Covered contact ; presumably fault cutting out originally conformable shale. Bonanza King Dolomite. INDEPENDENCE QUADRANGLE, CALIFORNIA TC-1. Type section of Tamarack Canyon Dolomite, 6,000 ft northeast of SE cor. sec. 36, T. 11 S., R. 36 E. Al Rose Formation. Conformable contact. Tamarack Canyon Dolomite: 3. Dolomite, medium-dark-gray; weathers medium light gray; generally massive, but partly very thin bedded ; rilled weathering surface accentu- ates the thin 2. Dolomite, medium- to dark-gray; weathers me- dium light gray to light gray ; very thin bedded to laminated ; some weathered surfaces rilled ; flaggy to slabby parting; some black chert near base -__- 1. Dolomite; same as overlying unit but black chert nodules and lenses (as much as 4 in. thick and 2 ft long) are more abundant______________ £ Feet 272 123 515 Total Tamarack Canyon Dolomite__________ 910 Conformable contact. Lead Gulch Formation. AR-1. Type section of the Al Rose Formation, about 2 miles NNE of Johnson Spring, T. 12 S., R. 36 E. Badger Flat Limestone. Conformable contact. Al Rose Formation : 3. Shale and mudstone, medium-dark-gray to olive- gray ; weathers light brown to moderate reddish brown; in beds as much as 2 in. thick; inter- bedded gray limestone beds as much as %4 in. thick; forms distinctive dark outcrop; grapto- Ates near top-. 0s ted ee lad neues 2. Siltstone and mudstone, medium-gray ; weathers dark yellowish orange to light brown; very irregularly interbedded thin-bedded medium- gray limestone; where silty beds are predomi- nant, limestone lenses weather out, leaving diagnostic "eyes"; outcrops have an overall brown appearance; fossil fragments found lo- cally; structural contortions in this relatively incompetent unit preclude accurate thickness measurements Feet 52 300- 400 (?) 1. Limestone, medium-gray, very thin bedded to laminated ; black chert near base; 6-in.-thick bed of edgewise conglomerate associated with sandy bioclastic layers about 3 ft below top___. 13 'Potal /Al Rose 400 ( ?) Conformable contact. Tamarack Canyon Dolomite. BF-1. About % mile northeast of Squares Tunnel, T. 12 S., R. 36 E. Barrel Spring Formation. Conformable contact. Badger Flat Limestone: 3. Limestone, medium-gray to medium-bluish-gray ; thin nodular beds and laminae; abundant argillaceous-siliceous irregular lenses and nod- STRATIGRAPHIC SECTIONS 45 BF-1. About % mile northeast of Squares Tunnel-Continued Badger Flat Limestone-Continued Feet ules which weather dark yellowish orange to light brown and in relief; lower 70 ft of unit has scattered large gastropods (Palliseria?) ; one orthocone cephalopod found______________ 165 2. Limestone, medium-gray to medium-bluish gray ; thin nodular beds; brownish argillaceous- siliceous beds abundant, as in unit 3; scattered black chert nodules; large gastropods (Pal- liseria?) 45 ft below top of unit______________ 95 1. Limestone and brown beds as in unit 2; black chert, in nodules and in lenses as much as 4 in. thick, more abundant than in unit 2; locally chert makes up 50 percent of unit, but generally about 10 percent; near base of unit, chert and brown layers make up about 50 percent of the unit and are interbedded in relatively even layers 1 to 3 in. thick with bluish limestone____ 297 Total Badger Flat Limestone______________ 557 Conformable contact. Al Rose Formation. BF-2. About V4 mile south of Barrel Springs, T. 12 S., R. 36 E. Barrel Spring Formation. Conformable contact. Badger Flat Limestone : Feet 7. Limestone, medium-bluish-gray to medium dark- gray ; irregular lenticular bedding, accentuated by irregular nodules, lenses, and beds as much as 1 in. thick of dark-yellowish-orange to light- brown siliceous-argillaceous material_________ 81 6. Same as unit 7; gastropod outlines______________ 1 5. Same as nnit T-: i ce 90 4. Same as unit 7; small chert nodules about 25 ft from top of unit; gastropod outlines about 45 ft below. LOD... _- on. 65 3. Same as unit 7; orange-brown material replaced by concentrations of amphibole crystals, which are also present, but less abundant, in the lime- stone. (This feature has been increasing downward from about 100 ft above this unit) __ 70 2. Same as unit 7 ; orange-brown beds common, abun- dant amphibole; very minor black chert as nodules and thin 99 1. Same as unit 7 ; chert nodules, lenses, and nodular beds locally make up as much as 20 percent of unit, but occurrence is sporadic; orange-brown heds also locally abundant__..:.-_____________ 105 Total Badger Flat Limestone______________ S11 Conformable contact. Al Rose Formation. BE-3. In Water Canyon about q mile east of Barrel Springs, T. 12 8., R. 86 E. Barrel Spring Formation. Conformable contact. Badger Flat Limestone: Limestone, blue-gray, in thin irregular beds ; variable amounts of gray argillaceous-siliceous material in BE-3. In Water Canyon about Ao mile east of Barrel Springs- Continued Badger Flat Limestone-Continued irregular interbeds that in places stand out in relief as reddish-brown-weathering ribs; these interbeds make up as much as 20 percent of unit and contain numerous amphibole crystals; other argillaceous beds (less siliceous?) weather black and give dappled appearance to unit; minor black chert nodules (several subunits could be desig- nated on the basis of percentage of argillaceous interbeds, but their gross lithology is very gmilar) --... nln edo n tane s 532 Conformable contact. Al Rose Formation. Feet BF-4. Type section of the Badger Flat Limestone, about 2 miles north-northeast of Johnson Spring, T. 12 S., R. 36 H. Barrel Spring Formation. Conformable contact. Badger Flat Limestone : Feet 7. Limestone, medium-gray, very thin and irreg- ular bedded; interbedded lenses and nodular beds of brown-weathering silty material; rare chert beds as much as %4 in. thick; abundant fossil cll cee} 41 6. Quartzite, dark- to light-gray ; beds 6 in. to 1 ft thick; weathers to brownish-gray knobby sur- face; some limy 5 5. Limestone, medium-gray, silty ; weathers distinc- tive dark yellowish orange to light brown; pelmatozoan fragments______________________ 12 4. Limestone, medium-gray, very thin and irregular bedded ; abundant nodules and lenses of yellow- weathering silty material; pelmatozoan frag- ments .. LOL 28 3. Quartzite, medium-gray; weathers brown and knobby ; some limy cement and lenticular lime- stone layors-_..0soucel n scat e lcd. 8 2. Limestone, medium- to dark-gray; irregular lenses of yellow- to brown-weathering silty ma- terial give distinctive irregular nodular appear- ance to outcrops ; fossils locally abundant____-_ 489 1. Limestone, gray, silty (?), very thin bedded ; some plack chert . al lees ied ie 8 Total Badger Flat Limestone_______________- 586 Conformable contact. Al Rose Formation. BS-1. About %o mile northeast of Bee Springs Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Feet 2 "-.. ola ele Ea ine oe an s nle ae eda are aes an aed 11 1. Siltstone and hornfels, medium- to dark-gray; weathers light brown to moderate reddish brown ; much spotted hornfels, some cale- horn- fels (?) ; commonly laminated ; basal few feet of _ calc-hornfels makes up lower member in some places but has not been differentiated in this section; coarsely crystalline limestone at con- tact suggests fault, but attitudes are conform- 46 BS-1. About %o mile northeast of Bee Springs-Continued Barrel Spring Formation-Continued Feet able, so may just be minor bedding-plane movement or recrystallization along permeable contact 2. ._.... ans dill 60 Total Barrel Spring Formation-______________ T1 Conformable contact. Badger Flat Limestone. BS-2. In Willow Springs Canyon, T. 18 S., R. 36 E. Feet Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Upper member : 4. Shale (altered to hornfels), dark-gray to greenish-gray ; partly calcareous ; well lam- inated In places. /.... sulla Lo ECIS 30 3. Limestone, medium-gray, thinly laminated, interbedded with lenses and irregular lay- ers of light-brown-weathering argillaceous materia1 ~. sn uP e >. 10 2. Shale (altered to hornfels), medium-light- gray, SIlIGGOUS-.L_ -L. n 10 Lower member : 1. Dolomite, white, coarse-grained; weathers pale yellowish orange . _-«__.__cLL____LL 20 Total Barrel Spring Formation-_____-__- r(t) Conformable contact. Badger Flat Limestone. BS-3. About % mile northeast of Squares Tunnel; T. 12 S., R. 8G R. Feet Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Upper member : 2. Shale (altered to hornfels), medium- to dark- gray; weathers moderate reddish brown to moderate brown; commonly speckled with white spots of metamorphic minerals______ 109 Lower member : 1. Calc-hornfels, white; some beds laminated, other beds massive; hackly fracture_______ 80 Total Barrel Spring Formation-_______-- 189 Conformable contact. Badger Flat Limestone. BS-4. About % mile northeast of Squares Tunnel, T. 12 S., R. 36 E. Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Feet Upper member : 4. Shale (altered to hornfels), medium-gray, thin-bedded ; weathers moderate reddish brown; poorly exposed interval of rubbly float - ence ce eol enced b onine ae ae ae i. 64 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA BS-4. About % mile northeast of Squares Tunnel-Continued Barrel Spring Formation-Continued Feet Lower member : 3. Limestone, sandy, impure, thin-bedded ; con- tains thin reddish-brown - argillaceous c ice alle ee nu asin a an ame's ane 15 2. Calc-hornfels, white; weathers partly to moderate reddish brown; massive; hackly _2 .n 2s. 22 l EP ia s se WNW corer eine ce at ae ae a te te 15 1. Calc-hornfels, medium-gray, laminated to thin-bedded; weathers grayish orange to dusky brown; weathering accentuates bedding by creating ribbed surface; some limestone and dolomite(?) _________----- 60 Total Barrel Spring Formation-_____--- 154 Conformable contact. Badger Flat Limestone. BS-5. About % mile south of Barrel Springs, T. 12 S., R. 36 E. Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Upper member : 7. Siltstone and shale; hornfelsed ; mostly dark colored ; weathers moderate reddish brown to dark yellowish orange; poorly exposed, but color of rubbly outcrop very distinc- aa tna a nie a anis bnat le seals 56 Lower member: 6. Mostly covered ; float and scattered exposures of light-colored calc-hornfels and impure _: .}... curl.. Pui we nim ce ie ie een 26 5. Limestone, medium-gray, nodular; irregular beds as much as 1 in. thick; interlayered lenses and beds of reddish-brown-weather- ing silicecous-argillaceous material in an- Feet astomosing L..... 11 4. Cale-hornfels, yellowish- to light-gray, lami- rat od 2 22.0.2. -... whoa mle to m hk sole in tn wad he by me e e ie ul ce tae ha 3. Dolomite, medium-gray, massive to poorly bedded Aidala -me 68 2. Limestone, medium-gray, massive to poorly bedded ; locally has reddish-brown-stained zones; abundant metamorphic minerals. 11 1. Calc-hornfels, light-gray, massive; weath- ers light brown; some limestone_______-- 3 Total Barrel Spring Formation-____--- 206 Conformable contact. Badger Flat Limestone. BS-6. Type section of the Barrel Spring Formation, about % mile northeast of Barrel Springs in Mexican Gulch (neat canyon north of Bonanza Gulch), T. 12 S., R. 36 E. Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Upper member : 3. Shale (altered to hornfels?), grayish-black ; most weathers moderate to dark reddish STRATIGRAPHIC SECTIONS 47 BS-6. Type section of the Barrel Spring Formation, about % mile northeast of Barrel Springs in Mexican Guich-Continued Barrel Spring Formation-Continued Feet brown but some weathers silvery gray; thinly laminated with shaly to flaggy parting; sandy and silty layers near top; brachiopods, trilobites, graptolites, and ostracodes in lower 5 ft; brachiopods also common 18 ft above base_______________- 78 Lower member : 2. Limestone, - medium-dark-gray: - weathers medium gray to medium bluish gray; ir- regular nodular beds %&-3 in. thick; in- terbedded light-brown lenticular beds that stand in relief on weathered surfaces but are not noticeable on fresh surfaces_____ 29 1. Calc-hornfels, impure sandstone and car- bonate; thin bluish-gray limestone beds near base; impure quartzite near top-____- 50 Total Barrel Spring Formation-_-____- 157 Conformable contact. Badger Flat Limestone. BS-7. About % mile east of Johnson Spring, T. 12 S., R. 36 E. [Section measured by Langenheim and others (1956) ] Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Upper member : 3. Shale to mudstone, medium- to olive-gray ; weathers light brown to moderate reddish brown ; shaly to flaggy parting; fragments of brachiopods and trilobites (Langenheim nits 9, 10; 11) £15 2-00 ese 86 Lower member : 2. Limestone, dark-gray; weathers medium gray; in irregular beds 4-3 in. thick; interbedded dark-gray argillaceous beds that weather out in relief as orange-brown ribs (Langenheim unit 8) ___-____________ 25 1. Limestone, medium-gray to light-olive-gray, sandy ; weathers light gray to pale yellow- ish orange; nodular, irregular bedding; some fucoids near top (Langenheim Wn 7) co on- JLE AEU AA an aim n a aes 30 Feet Total Barrel Spring Formation-_____-- 141 Conformable contact. Badger Flat Limestone. BS-8. About 1%) miles northeast of Johnson Spring, T. 12 S., R. 36 E. Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Feet 5. Shale, black to olive-gray ; weathers dark yellow- ish orange to moderate reddish brown; papery to shaly parting. _ L__- _c. 34 4. Limestone, gray to light-brown, silty, impure; abundant silty beds; some fossil fragments___ 4 0. Shale, same as unit 8 BS-8. About 1%y miles northeast of Johnson Springs-Con. Barrel Spring Formation-Continued Feet 2. Limestone, gray to light-brown, silty, impure; abundant fossil molds, mostly pelmatozoan, some . 8 J. Shale, same as unit 41 Total Barrel Spring 90 Conformable contact. Badger Flat Limestone. BS-9. About 2 miles north-northeast of Johnson Spring, T. 12 S., R. 36 E. Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Upper member : 2. Siltstone, dark-gray shale, and impure quart- zite in very thin bedded to laminated se- quence; siltstone and shale most abundant and weather to distinctive reddish brown. 73 Lower member : 1. Limestone, dark-gray, impure; weathers light brown to moderate reddish brown ; rich in fossil fragments, pelmatozoan predominate, some trilobite fragments; thin interbeds of black shale in lower part of unit__________ 34 Feet Total Barrel Spring Formation_____-_ 107 Conformable contact. Badger Flat Limestone. BS-10. - About 1 mile northeast of Pops Gulch, T. 11 S., R. 36 E. Johnson Spring Formation. Conformable contact. Barrel Spring Formation : Upper member : 2. Shale and siltstone, gray-black to dark- gray, thinly laminated ; weathers moderate reddish 59 Lower member : 1. Limestone, - medium-gray; beds %4-4 in. thick; interbedded with gray silty and shaly layers as much as 4 in. thick; weathers moderate reddish brown-______- 41 Feet Total Barrel Spring Formation-_-_____- 100 Conformable contact. Badger Flat Limestone. JS-1. About %y mile northcast of Bee Springs, T. 18 8., R. 36 K. Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Upper quartzite: Feet 17. Quartzite, very light-gray to yellowish-gray ; weathers white to dark yellowish orange; beds 3-4 in. thick; some beds laminated ; some calcareous cement_______---------- 3 48 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNTA JS-1. Johnson Spring Formation-Continued Upper quartzite-Continued 16. Dolomite, medium- to light-gray; weathers flight sray._-.~.._l_ 2230 _c cou la 15. Quartzite, white to yellowish-gray; part weathers dark yellowish orange to light brown, but overall color is white to cream; thick to thin bedded; forms bold outcrops; some is coarser than most Ojs quartzite and is probably recrystal- lized; calcareous cement near base______ Upper dolomite: 14. Dolomite, medium-gray; 1- to 4-in.-thick irregular beds interlayered with - to ¥4-in.-thick black chert beds-____________ Middle quartzite: 13. Quartzite, generally light-gray; yellowish tints weather darkish brown ; thin to very thin bedded, crossbedded locally; some 12. Quartzite, white to light-gray, thick- to thin- bedded; looks very massive in contrast to overlying well-bedded quartzite unit; small iron-stained spots cause speckling and accentuate bedding_________________ 11. Limestone, medium- to dark-gray, lami- nated; nodular bedding; possibly sandy ; contains one 6-in.-thick bed of calcareous quarts sandstone__c_-____LL_L_L_L______ 10. Quartzite, gray; weathers reddish-gray and brownish-gray ; some calcareous cement; some silty and calc-hornfels beds near Page 2 o ool ba nea e n ae ane oe. Lower limestone: 9. Limestone, medium-gray, erystalline_______ 8. Calc-hornfels, greenish-gray, dense, lami- nated; abundant epidote; weathers red- dish-gray and brownish-gray____________ Lower quartzite: 7. Quartzite, white to light-gray, poorly bed- ded; forms massive outcrops; Scolithus very abundant near center of unit:_____ 6. Quartzite, impure, and siltstone, limy quartzite, and minor calc-hornfels; light- to dark-gray; weather reddish-gray and yellowish-gray. Poorly exposed; com- monly very thinly bedded to laminated ___ Lower limestone : 5. Limestone, medium-gray ; weathers pale red- dish brown and gray; very thin irregular bedding ; irregular thin beds and lenses of reddish-gray-weathering argillaceous or sil- iceous 00 Lower quartzite: 4. Quartzite; calcareous cement common ; some ealc-hornfels 3. Quartzite, light-gray, pure; much crossbed- 0g 220 eo avn eee eae e ee cues 2. Siltstone, dark-gray, laminated, and impure quartzite; weathers moderate to dark red- dish . Ck O About %o mile northeast of Bee Springs-Continued Feet 1 82 12 27 T2 21 39 33 30 10 11 JS-1. About %o mile northeast of Bee Springs-Continued Johnson Spring Formation-Continued Lower quartzite-Continued 1. Quartzite, white to gray ; some crossbedding ; massive Total Johnson Spring Formation-_____ Conformable contract. Barrel Spring Formation. JS-2. In Willow Springs Canyon, T. 18 S., R. 86 Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Upper quartzite : 21. Quartzite, very light gray to medium-light- gray, massive; local wispy bedding______ Upper dolomite : 20. Dolomite, medium-dark-gray ; weathers med- ium gray to medium light gray ; generally massive, but locally bedded______________ Middle quartzite : 19. Quartzite, white to light-gray; massive; grains fine to very fine sand size; locally bedded ; blocky fracture__________ 18. Dolomite, dark-gray; weathers medium gray : erinold 17. Quartzite, white to light gray ; in part well- bedded with layers %%-1 in. thick, but gen- erally massive; minor calcite cement in some bed#._L_. 220.0. ___ _ 16. Limestone, dark-gray; weathers medium gray ; nodular beds as much as 4 in. thick ; some purplish-pink beds that contain fos- sil fragments (possibly a lens of the coral limestone unit of sections JS 7-10) ______ 15. Quartzite, white, massive_________________ 14. Dolomite, medium- to dark-gray; crinoid fraements" _._ ...... ssc clu cs 13. Quartzite, white, massive________________ 12. Dolomite, medium- to dark-gray; crinoid fragments 11. Quartzite, white, massive_________________ 10. Dolomite, medium- to dark-gray ; scattered crinold 9. Quartzite, white to light-gray; generally massive, but locally bedded; blocky -= __ ell c cb - Lower limestone : 8. Cale-hornfels, splotchy gray; abundant calcite; rosettes of tremolite( ?) ________- 7. Limestone, dark- to medium-gray, in nodular beds 1-6 in. thick; some beds laminated ; interbedded light-brown to moderate-red- dish-brown argillaceous lenses, which are more abundant in lower 13 ft of unit; scat- tered crinoid debris and brachiopod fragments Lower quartzite: 6. Quartzite, white to light-gray, massive____ Feet 27 392 Feet 30 40 22 30 103 34 10 STRATIGRAPHIC JS-2. In Willow Springs Canyon-Continued Johnson Spring Formation-Continued Lower limestone : Feet 5. Limestone, dark-gray ; laminated dark shale and siltstone beds common near top of unit; some crinoid debris and bra- chiopod fragments______._________-____ 10 Lower quartzite: 4. Quartzite, white, massive__________________ 12 Lower limestone : 3. Limestone, dark-gray ; nodular beds from less than % in. to as much as 6 in. thick ; partly argillaceous; crinoid, trilobite(?), and brachiopod fragments locally_____________ 12 2. Calc-hornfels, varied green and tan laminated beds; some dark-colored siltstone, sand- stone, and quartzite beds________________ 16 Lower quartzite : 1. Quartzite, white to light gray; well bedded near top, but generally massive (seems somewhat thicker on ridge to northwest where less structually disturbed) ________ 25 Total Johnson Spring Formation_______ 398 Conformable contact. Barrel Spring Formation. JS-3. About % mile northeast of Squares Tunnel, T. 12 S., R. 36 E. Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Upper quartzite : Feet 8. Quartzite, white, fine-grained, massive; hackly 11 Upper dolomite : 7. Dolomite, medium-gray ; mostly covered____ 14 Middle quartzite : 6. Quartzite, white, fine-grained, massive; hackly l_. 106 5. Limestone, medium-gray___________________ 2 4. Quartzite, white, massive; hackly fracture 8 Lower limestone : 3. Limestone, bluish-gray ; thin irregular beds; some fossil debris.... 33 2. Dolomite, medium-gray ; nodular beds______ 6 Lower quartzite : 1. Quartzite, white, ; yellow-to brown-weathering cement; well bedded in layers as much as several inches thick; somewhat coarser grained than upper and middle quartzite units___________________ 82 Total Johnson Spring Formation-______ 262 Conformable contact. Barrel Spring Formation. 212-460 0O-66--5 SECTIONS 49 JS-4. About % mile northeast of Squares Tunnel, T. 12 S., R. 36 B. Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Upper quartzite : Feet 8. Quartzite, white, fine-grained ______________ 13 Upper dolomite : 7. Dolomite, medium-gray, massive ; some nodu- lar c cle nell 36 Middle quartzite : 6. Quartzite, white, fine-grained, massive; hackly _ 79 Lower limestone : 5. Limestone, bluish-gray ; nodular beds a frac- tion of an inch to 2 in. thick ; fossil debris__ 20 Lower quartzite : 4. Quartzite, white, impure, thin-bedded; weathers grayish orange; flaggy parting___ 1 8. Shale, dark-gray_______L____-_L__:LiLGL__L 1 2. Quartzite, white, impure, thin-bedded ; weathers grayish orange ; flaggy parting. 58 1. Quartzite, white, fine-grained ; some weathers dark yellowish orange to light brown; hackly fracture; partly crossbedded ; some calcite :cemente. -_ ocr 24 Total Johnson Spring Formation-_______ 227 Conformable contact. Barrel Spring Formation. JS-5. About ¥, mile south of Barrel Springs, T. 12 S., R. 86 E. Ely Springs Dolomite. Conformable contact, but covered. Johnson Spring Formation : Upper quartzite : 15. Quartzite, white, fine-grained ; hackly frac- ture; breaks in pieces no more than a few inches __ ance 16 Upper dolomite : 14. Interval mostly covered; some coarse- grained dolomite about 20 ft below top of sn 00 o Ue CELLAR E 25 Middle quartzite: 13. Quartzite, white, fine-grained, massive to poorly bedded; intensively fractured ___ 60 Lower limestone : 12. Limestone, medium-bluish-gray to medium- dark-gray; in beds as much as several inches thick; interbedded siliceous-argil- laceous material that weathers moderate reddish brown to light brown and is in irregular nodular beds as much as 3 in. thick; abundant fossil fragments, mostly pelmatozoan 56 Mixed lithology : 11. Calc-hornfels, yellowish-gray to light-gray, well-bedded ; beds from fraction of an inch to 8 in. thick. L= cu 3 10. Shale, hornfelsed, dark-gray, very thin bedded to laminated; flaggy to shaly parting _c o Ll 2 Feet 50 JS-5. About ¥ mile south of Barrel Springs-Continued Johnson Spring Formation-Continued Mixed lithology-Continued 9. Calc-hornfels, yellowish-gray to light-gray, well-bedded ; beds from fraction of an inch to 8 in; thick___ _s T 8. Dolomite, medium-gray; weathers light to moderate brown; sugary texture; lami- nated to beds several inches thick; flaggy Feet to slabby ___ 11 7. Calc-hornfels, gray, well-laminated_______- 4. 6. Dolomite, medium-gray; weathers | light brown ; sugary texture ; laminated to beds several inches thick._._.____-__________. 8 5. Shale (altered to hornfels), grayish-black.. B 4: Covered _ y. ILE ence inet 6 Lower quartzite: 3. Quartzite, light-gray to white; somewhat coarser grained than quartzite in over- lying units; beds 1-2 ft thick; some @Collthus 000, L L IL 10 2. Quartzite, silty, impure; some shale layers; weathers light brown to moderate reddish brown ; very thin bedded ; some pure gray quartzite interbeds as much as 6 in. thick. 8 1. Quartzite, light-gray to white; somewhat coarser grained than overlying quartzites ; crossbedded...._.L______________LL_____ 11 Total Johnson Spring Formation-____-- 229 Conformable contact. Barrel Spring Formation. JS-6. About %o mile northeast of Barrel Springs, T. 12 8., R. 36 E. Ely Springs Dolomite. Conformable contract. Johnson Spring Formation : Upper quartzite : Feet 5. Quartzite, medium-dark-gray to white, mas- sive; unit contains one irregular dolomite pod s . IHG 13 Upper dolomite : 4. Dolomite, dark-gray; weathers medium gray; poor nodular bedding; some black chert nodules near top; strongly fetid; flecked with metamorphic minerals and and pelmatozoan debris________________- 34 Middle quartzite : 3. Quartzite, white to light-gray, massive_____ 43 Mixed lithology : 2. Poorly exposed interval; north of section, interval contains dark-gray shale and silt- stone underlain by limestone and dolomite containing pelmatozoan debris. Near mid- dle of covered interval is about 10 ft of calcareous sandstone and quartzite under- lain by about 2 ft of black shale. Below this are more cabonate rocks_____________ 51 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA JS-6. About %o mile northeast of Barrel Springs-Continued Johnson Spring Formation-Continued Lower quartzite: Feet 1. Quartzite, white to medium-gray, massive; weathers to yellow and red tints ; intensely fractured _.... 31 1. Siltstone and hornfels, medium- to dark-gray ; Total Johnson Spring Formation-____-_ 172 Conformable contact. Barrel Spring Formation. JS-7. - Type section of the Johnson Spring Formation, about % mile east of Johnson Spring; T. 12 8, R. 36 E. Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Upper quartzite: Feet 11. Quartzite, white to gray, fine-grained, mas- sive; markedly thins to south________-_--- 17 Upper dolomite : 10. Dolomite, dark-gray; weathers medium light gray, massive to poorly bedded; scattered black chert nodules and fossil debris ._.. 1... cc 20 Coral limestone : 9. Limestone, dark-gray, with scattered chert nodules and gastropod fragments______- 4 8. Limestone, dark gray; irregular, nodular bedding accentuated by dark-gray argil- laceous layers that weather medium gray; some dark-gray shaly mudstone about 20 ft below top; corals and bryo- zoans about 10 ft above base___________- 43 Middle quartzite : 7. Quartzite, very light gray to white, mas- sive; locally weathers to yellow and red tints; blocky fracture; calcareous cement in . PATE L 022 ae 2 22 PAL eee vara eae an ie ania oe ae t 34 Mixed lithology : 6. Limestone, dark-gray; weathers medium to light gray; thin nodular beds; minor reddish-brown-weathering argillaceous lenses; many coral and other fossil frag- ments c oce ll enor area ran eee saan s 20 5. Mixture of calcareous sandstone, red- brown-weathering thin-bedded siltstone, medium-gray fossiliferous _ limestone, medium-dark-gray dolomite, and minor white quartzite; makes a red-brown unit on 'the _L 26 4. Quartzite, white, massive________________ 2 3. Dolomite, sandy(?), - medium-light-gray, massive to thick-bedded; much fossil debris (mostly pelmatozoan)_____-__-_-_--- 5 2. Silty siliceous bed; light-olive-gray to medium-light-gray ; weathers light brown to moderate reddish brown ; laminated to very thin 6 Lower quartzite : 1. Quartzite, white to yellowish-gray, partly well-bedded and crossbedded ; coarser STRATIGRAPHIC SECTIONS 51 JS-7. Type section of Johnson Spring Formation, about % mile east of Johnson Spring-Continued Johnson Spring Formation-Continued Feet grained than overlying quartzite units; limy cement near base_________________ 35 Total Johnson Spring Formation-____ 210 Conformable contact. Barrel Spring Formation. JS-8. About %o mile northeast of Johnson Spring, T. 12 S., R. 36 E. Ely Springs Dolomite. Conformable contact. Johnson Snring Formation : Upper quartzite : 10. Quartzite, white to very light gray, fine- grained, poorly bedded to massive; weathers moderate yellow to moderate reddish brown on many joint surfaces___ 21 Feet Upper dolomite : 9. Dolomite, dark-gray, thick- to thin-bedded ; weathers medium light gray; black chert nodules 14 Coral limestone : 8. Limestone, bluish-gray ; irregular thin bed- ding ; many grayish-red streaks and lenses of argillaceous material cause unit to resemble Badger Flat Limestone locally ; coral fragments common near base______ 74 Te Covered. 00.1 2r.L ae c Sun all 10 Middle quartzite : 6. Quartzite, white to light-gray, massive, much fractured ; some calcareous cement. 23 Mixed lithology : 5. Dolomite, dark-gray; weathers medium gray; beds 1 ft or more thick; massive appearance L _c T Coral limestone : 4. Limestone, medium-gray ; irregular very thin nodular beds ; grayish-red lenses give purplish cast to rock in places; coral, crinoid, and brachiopod fragments______ 14 Mixed lithology : 3. Quartzite, light-gray to white; much cal- careous matrix (locally unit is a calcar- eous quartz sandstone)-__-_______._.___ 5 2. Poorly exposed slope of mixed siltstone, shale, limestone, and impure quartzite ; fragments commonly weather to shades of red. and ccc 0s __ 37 Lower quartzite: 1. Quartzite, medium- to light-gray, medium- to fine-grained, massive_______L________ 9 Total Johnson Spring Formation-_____ 214 Conformable contact. Barrel Spring Formation. JS-9. About 1%) miles northeast of Johnson Spring, T. 12 S., R. 36 E. Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Upper quartzite: 13. Quartzite, white to medium-gray; thick to thin bedded near base ; locally calcareous. 21 Upper dolomite : 12. Covered, probably like underlying dolomite (unit 11). 11 11. Dolomite, dark-gray ; thin nodular bedding ; minor black chert nodules; pelmatozoan fragments and corals(?)_______________ 26 Coral limestone : 10. Limestone, medium-gray to dark-yellowish- Feet brown; flaggy fracture; argillaceous; poorly exposed; many coral fragments, some 22 9. Quartzite, dark-gray to moderate-reddish- brown; limy interbeds_________________ 5 argillaceous beds ; similar to unit 10_____ 37 7. Dolomite, medium-dark-gray ; weathers me- dium light gray ; thin nodular bedding___ 12 6. Limestone, medium-dark-gray, bioclastic; generally massive, but bedding is shown by dark-gray siliceous laminated layers as much as 2 in. thick; pelmatozoan frag- ments common ; brachiopods also present.. 16 Mixed lithology : ¢ 5. Quartzite, white to medium-gray; massive but strongly jointed; metamorphic min- erals common near top, suggesting origi- nal calcareous cement__________________ T 4. Limestone, gray and dark-gray; weathers moderate reddish brown ; argillaceous lay- ers; poorly exposed 17 3. Quartzite, light- to medium-gray, very thin to thin-bedded ; some calcareous cement 8 2. Dolomite, dark-gray, laminated to very thin bedded; weathers dark yellowish orange ; poorly exposed 18 Lower quartzite : 1. Quartzite, medium-gray ; near top of unit is thin bedded and has some layers of silt- stone and shale, rest of unit is massive, pure, and poorly bedded; crisscrossed with' white _ 12 Total Johnson Spring Formation______ 212 Conformable contact. Barrel Spring Formation. JS-10. About 1%y miles northeast of Johnson Spring, T. 12 A:; R. 86 E: f Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Upper quartzite: Feet 12. Quartzite, medium-gray, massive__________ 4 52 STRATICGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA JS-11. About 1%y miles northeast of Johnson Spring-Con. Johnson Spring Formation-Continued Feet Upper dolomite: 11. Dolomite, dark-gray to grayish-black, thick- to thin-bedded ; appears massive_______- 21 Coral limestone : 10. Limestone, medium-gray to grayish-orange and grayish-red; very thin nodular bed- ding; some black chert nodules; corals and brachiopods locally abundant_______ 38 Crinoidal dolomite : 9. Dolomite, medium-gray; very thin bedded near base, but generally massive; abun- dant pelmatozoan debris which gives rock a nodular, bumpy surface______________- 26 Mixed lithology : 8. Mixture of siltstone, dark-gray dolomite, and thin dark-gray bioclastic limestone layers .. coco. eae aon ao ale oles alice fd m in m me 28 7. Dolomite, same as unit 5--______________-- 6 6. Sandstone, medium-gray, very thin bedded; well-rounded grains seem coarser than av- erage in this formation; calcareous cement 5. Dolomite, medium-gray; weathers grayish yellow to grayish orange; laminated to very thin bedded; irregular argillaceous interbeds as much as 14 in. thick______-- 17 Lower quartzite: 4. Quartzite, medium-gray ; thin- to very thick- bedded ; weathers to slightly brown-____. 5 3. Shale, dark-gray to black; weathers mod- erate reddish brown.____________________ 1 2. Quartzite, medium-gray, thin- to thick- bedded ; faint crossbedding__________--- 9 1. Quartzite, brown-weathering, silty, very thin lc 3 Total Johnson Spring 161 Conformable contact. Barrel Spring Formation. JS-11. About 2 miles north-northeast of Johnson Spring, T. 12 @.. R. 86 E. Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Upper quartzite: 8. Quartzite, medium-gray to white, thick- to thin-bedded ; some beds as much as a few feet thick; weathers "soft"; little cal- careous cement; lower part tends to weather to shades of red__________________ 70 Upper dolomite : 7. Dolomite, medium-dark-gray; poor nodular bedding ; coral fragments; some black chert Feet nodules -_: 9s 200 LO BC Luce 21 6. Quartzite, medium-gray ; weathers to knobby grayish-orange to light-brown surface- 10 5. Shale and siltstone, black; weathers mod- erate reddish brown ; laminated ; thin gray limestone near top of unit contains brachio- JS-11. About 2 miles north-northeast of Johnson Spring-Con. Johnson Spring Formation-Continued Upper quartzite-Continued Feet pods and coral fragments, may be lens of coral limestone nnit=____.____-____._____ $ Crinoidal dolomite: 4. Dolomite, medium-gray, knobby; irregular thin bedding; some crinoidal debris and coral and brachiopod fragments-_______-- 23 Mixed lithology : 3. Quartzite, light-gray, as one massive bed; though contact with overlying dolomite is fairly sharp, dolomite is obviously sandy for at least 1 ft above the quartzite; also quartzite has some calcareous cement___~ 3 2. Impure quartzite, siltstone, and black shale; thin-bedded to very thick bedded ; weathers moderate to dark reddish brown ; about 1 ft of gray limestone near base___________--- 16 Lower quartzite : 1. Quartzite, medium- to light-gray; locally very thin 10 Total Johnson Spring Formation-_____-- 158 Conformable contact. Barrel Spring Formation. JS-12. About 1 mile northeast of Pops Gulch, T. 11 8., R. 36 E. Ely Springs Dolomite. Conformablé contact. Johnson Spring Formation : Upper quartzite : Feet 7. Quartzite, white to light-gray, massive; some calcareous 5 6. Dolomite, grayish-black, very thin nodular bedding; local pelmatozoan T 5. Quartzite, white to light-gray, massive, typically fine-grained, well-sorted, even- grained; some calcareous cement________ 56 Upper dolomite : 4. Dolomite, medium-gray to medium-dark-gray, fine-grained ; very thin irregular poor bed- ding; some black chert nodules ; minor pel- matozoan 35 3. Poorly exposed grayish-orange silty, limy bed .:.. l Lean eus 9 Crinoidal dolomite: 2. Dolomite, medium-gray to medium-dark- gray ; knobby weathered surface ; very thin irregular poor bedding; many pelmatozoan fragments cause surface to appear clastic; some black chert as nodules and thin nod- ular beds =e 38 Lower quartzite : 1. Quartzite, medium- to light-gray, some yel- lowish-orange; weathers light brown to moderate reddish brown; beds %&-1 in. thick; commonly has thin partings of gray to green shale with fucoid markings; black shale locally has interbeds a few inches thick ; some clastic layers are more properly STRATIGRAPHIC SECTIONS JS-12. About 1 mile northeast of Pops Guich-Continued Johnson Spring Formation-Continued siltstone; some crossbedding; basal 4 ft of unit is clean massive light-grey quartz- ite; overlying 3 ft has much limy cement__ Total Johnson Spring Formation____________ Conformable contact. Barrel Spring Formation. JS-18. In SEV, sec. 25, T. 11 S., R. 85 E. Ely Springs Dolomite. Conformable contact. Johnson Spring Formation : Crinoidal dolomite: 2. Dolomite, medium-gray; thin nodular bed- ding; many pelmatozoan fragments and some coral(?) fragments.:._..____________ Lower quartzite: 1. Quartzite, medium- to light-gray; weathers to shades of yellow and brown ; thin irreg- ular beds, in places crossbedded ; calcareous cement common in lower 30 ft___________ Total Johnson Spring Formation_______ Feet 52 202 Feet 29 114 Conformable contact, but covered. Barrel Spring Formation. ES-1. In Willow Springs Canyon, T. 18 S., R. 36 E. [Units 10, 11, 12, 13 measured on top of ridge south of canyon] Vaughn Gulch Limestone. Conformable contact. Ely Springs Dolomite: Upper member : 13. Dolomite, medium-gray to medium-dark- gray; irregularly thin bedded; rilled weathered surfaces; some black chert nodules __: _ _ l .tn 24 12. Limestone, dark-gray to gray-black; lami- nated to very thin bedded ; some bedded chert exposed.___....___.__._____ 11. Dolomite, like unit 13 but laminated and has more pronounced rills______________ 10. Chert, black to medium-gray; predomi- nantly dark colored ; bedding ranges from regular laminae to nodular beds as much as 2 ft thick, two 6-in.- to 1-ft-thick medium-gray dolomite beds and some lenses interbedded with chert; much breecigtion E00 9. Dolomite, light-gray to medium-dark-gray, color banded; bands are 4-1 in. thick and are internally laminated ; lenses and thin nodular beds of black chert make up about 10 percent of this unit____________ 8. Dolomite, medium-gray; weathers light gray; in massive beds as much as 3 ft thick, within which are nodular beds 4-1 in. thick; scattered black chert nodules_ 7. Chert, black, and interbedded medium- to dark-gray dolomite; beds are % to 4 in. Feet 18 28 28 30 18 ES-1. In Willow Springs Canyon-Continued Ely Springs Dolomite-Continued Upper member-Continued thick; chert makes up more than half of unit; lower 2 ft is massive black chert; some brecciation of chert and contortion of dolomite 6. Dolomite, medium-dark-gray ; weathers light gray ; generally massive; some wispy bed- ding: fefid c__ll._____G_LLLLC L __ 5. Dolomite, dark-gray; weathers medium gray; thinly laminated %- to 2-in. thick beds ; interbedded black chert layers from 4 in. to several inches thick make up about 15 percent of the unit____________ Middle member : 4. Dolomite, medium-gray; weathers light gray; bedding indistinct within massive beds several feet thick, but thin to very thin near middle of unit; coral fragments locally clot. Lower member : 3. Dolomite, medium-gray, and black chert in brecciated sequence of thin interbeds____ 2. Dolomite, medium- to dark-gray, brecciated_ 1. Dolomite, medium-gray to medium-dark- gray ; laminated to very thin nodular beds ; interbedded with nodules and nodu- lar beds of black chert that are commonly metamorphosed to a white mass; chert and dolomite more regularly bedded near base; dolomite beds are 1-6 in. thick, and chert beds %%4-3 in. thick; locally chert makes up 25 percent of unit, but more commonly 15-20 percent________________ Total Ely Springs Dolomite___________ Conformable contact. Johnson Spring Formation. ES-2. About % mile northeast of Squares Tunnel, T. R. 36 E. Vaughn Gulch Limestone. Conformable contact. Ely Springs Dolomite : Upper member : 5. Chert, medium-dark-gray to black, in nodular beds from a fraction of an inch to 1 in. thick; much is bleached, altered, and brec- plated" .... IEC enas 4. Dolomite, light-gray, massive______________ 3. Dolomite, medium-dark-gray to dark-gray, and black chert in interbeds 1-4 in. thick that are commonly nodular; contacts of chert and dolomite commonly have reaction zone :of ceed lulu Middle member : 2. Dolomite, medium-dark-gray ; weathers med- ium gray; forms massive, blocky outcrops but is in part well bedded in thin layers; parts of some layers nodular ; metamorphic minerals scattered throughout unit_______ 58 Feet 131 12 38 244 591 12 S., Feet 22 22 34 103 54 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA ES-2. About % mile northeast of Squares Tunnel-Continued Ely Springs Dolomite-Continued Feet Lower member : 1. Dolomite, medium-dark-gray, massive; weathers medium gray ; irregular nodules of black chert (mostly metamorphosed to light-colored metamorphic minerals) make up as much as 10 percent of the unit; locally chert is in. trains of irregu- lar nodules, which accentuates well-bedded but nodular appearance of this unit_____- 114 Total Ely Springs Dolomite__________-- 295 Conformable contact. Johnson Spring Formation. ES-3. About %, mile south of Barrel Springs, T. 12 S., R. 36 E. Vaughn Gulch Limestone. Conformable contact. Ely Springs Dolomite: Upper member : Feet 9. Dolomite, grayish-black; weathers medium light gray ; part is well bedded in layers % in. to several inches thick, and partly mas- sive; flaggy to slabby parting; irregular pits and sharp points and ridges on weath- ered surfaces ; irregular black chert nodules as much as 3 in. across throughout unit but most abundant near base; chert nodules commonly have white altered rims_______ 49 8. Chert, grayish-black; altered to various shades of gray; nodular, irregular beds as much as 1 in. or more thick; some beds precciated _.. c AL_ e evel 17 7. Dolomite, dark-gray ; weathers medium gray ; poorly bedded to massive; black chert nod- ules (as large as several inches) and nod- ular beds (as thick as 2 in.) make up about 10-20 percent of the unit; weathers as a prominent TID. .. .. }% 2_L te L oe awa sss 20 6. Dolomite, medium-gray and interbedded gray- ish-black chert; beds mostly 1-5 in. thick; some dolomite is laminated and some chert is nodular, though generally regularly bed- ded; dolomite and chert in about equal Amounts - l a e RDM aa 36 Middle member : 5. Dolomite, beds locally from 1 in. to several inches thick; weathers to a dappled gray ; texture is sug- ary in contrast to aphanitic in overlying aolonmite - RNNHILS... .\. SL. L eal e ten 54 4. Dolomite, dark-gray ; weathers medium gray ; bedding ranges from laminae to beds 4 in. fhick 7".. L cu sou ooo Levan ens T 3. Dolomite, medium-gray to medium-dark- gray, massive to poorly bedded, weathers dappled gray, ridged and pitted __________ 18 medium-gray, - massive; ES-3. About ¥, mile south of Barrel Springs-Continued Ely Springs Dolomite-Continued Lower member : Feet 2. Dolomite, dark-gray to medium-dark-gray, massive to poorly bedded, fetid; scattered irregular black chert nodules as much as several inches long, commonly altered along rims; abundant pelmatozoan fragments lo- cally 1. Dolomite, dark-gray to medium-dark-gray ; irregular beds 1-4 in. thick; nodular inter- beds of black chert as much as 1 in. thick at intervals of 4-5 in. make up about 10 percent of the unit, near base increases to 20 percent; also near base are chert- rich layers several feet thick; pelma- tozoan debris abundant in places______-- 85 Total Ely Springs Dolomite_______-_-_-- 342 Conformable contract. Johnson Spring Formation. ES-4. About % mile east of Johnson Spring, at end of road at Bluestone tale mine, T. 12 8., R. 36 E. Sunday Canyon Formation. Conformable contact. Ely Springs Dolomite: Upper member : Feet 7. Chert, dark-gray to black, massive; some al- tered to lighter shades of gray ; brecciated _ 10 6. Dolomite, medium-gray ; weathers light gray ; very thin bedded, somewhat irregular; weathers to a varied gray-banded appear- ANCO Ul noun eeonuceamenenaten 13 5. Dolomite, dark-gray, dark- to light-gray- weathering, and somewhat nodular black chert regularly interbedded in layers 1-4 in. Thick -c co 15 Middle member : 4. Dolomite, medium-gray ; weathers light gray ; thin to thick bedded, but massive appear- ance; some pelmatozoan fragments; scat- tered metamorphic minerals common----- 64 3. Dolomite, dark-gray, massive; weathers medium dark gray; scattered black chert nodules and thin nodular beds-________-- 57 2. Dolomite, dark-gray; nodular beds 1-5 in. thick; interlayered with nodular black chert beds 1-3 in. thick; pelmatozoan fragments -c.. coule cn reed ene ue 22 1. Dolomite, dark-gray, fetid ; massive beds sev- eral feet thick and some irregular dark lenses and wispy layers that accent bed- ding and are themselves laminated to thin bedded ; scattered fossil fragments_______ 19 Total Ely Springs Dolomite_______-_--- 200 Conformable contact. Johnson Spring Formation. STRATIGRAPHIC SECTIONS 55 ES-5. About 1 mile northeast of Johnson Spring, T. 12 S., R. 36 B. Sunday Canyon Formation. Conformable contact. Ely Springs Dolomite: Upper member : Feet 5. Chert, black, massive, brecciated_______---- 12 4. Covered (probably same as unit 3) ______--- 5 3. Dolomite, grayish-black, very thin bedded; laced with very thin white carbonate stringers; interbedded nodular black chert layers as much as 1 in. thick________-_-- 28 Middle member : 2. Dolomite, medium-dark-gray ; weathers light gray; poorly bedded thick to thin beds; massive outcrops; olive-gray sandy dolo- mite lens S5 ff from 145 Lower member : 1. Dolomite, dark-gray; thin, irregular bed- ding ; black chert nodules and nodular beds as much as 2 in. thick; chert less abun- dans cocco ces es 61 Total Ely Springs Dolomite____-_--_---- 251 Conformable contact. Johnson Spring Formation. ES-6. About 1% miles northeast of Johnson Spring; T. 12 S., R. 36 E. Sunday Canyon Formation. Conformable contact. Ely Springs Dolomite: Upper member : Feet 6. Chert, black, massive, brecciated_________-- 9 5. Dolomite, medium-gray, laminated ; weathers varied 15 4. Dolomite, dark-gray, in thinly laminated beds as much as a few inches thick interbedded with black chert in beds as much as 3 in. thick. 2. _ cJ ARE ULI 19 Middle member : 3. Dolomite, - medium-gray; - weathers light gray; some very thin irregular bedding; forms massive 97 Lower member : 2. Dolomite, dark-gray to medium-dark-gray ; very minor chert stringers; very thin irreg- ular bedding, shown by wispy varied-gray color bands on weathered surface_______- 39 1. Dolomite, dark-gray, in irregular nodular beds as much as 4 in. thick interbedded with irregular nodular black chert layers as much as 3 in. thick; some pelmatozoan CGeDri® secs aoc po LEL ASL e dane as 56 Total Ely Springs Dolomite______----- 285 Conformable contact. Johnson Spring Formation. ES-7. About 2 miles NNE of Johnson Spring, T. 12 S., R. 36 E. Sunday Canyon Formation. Conformable contact-covered. Ely Springs Dolomite: Upper member : Feet 6. Dolomite, varied gray ; thin irregular 6 5. Mostly covered ; massive black chert striking into this interval from south of section-_- 5 4. Dolomite, grayish-black, thin-bedded, laced with thin white dolomite stringers and in- terbedded with black chert beds 1-2 in. Thick... SL eon_ _L luc 28 Middle member : 3. Dolomite, medium-light-gray, weathers light gray; irregular thin to thick beds; some erinold 69 Lower member : 2. Dolomite, medium-dark-gray ; weathers medium gray; thin irregular bedding, darker and thinner bedded in lower part, some crinoid fragments-___________----- 43 1. Dolomite, medium-dark-gray, thin- to very thin-bedded, with irregular, nodular inter- beds of chert as much as 3 in. thick; both partly laminated ________________________ 64 Total Ely Springs Dolomite_________-- 215 Conformable contact. Johnson Spring Formation. About 1 mile northeast of Pops Guich, T. 12 S., R. 36 E. Sunday Canyon Formation. Conformable contact. Ely Springs Dolomite: Upper member : Feet 8. Dolomite, medium-dark-gray ; weathers light gray; abundant pelmatozoan debris_____- 1 T, Covered ___ . LIL Lat den ai aaa 7. 6. Dolomite, medium-dark-gray ; weathers medium gray; irregular thin beds; irreg- ular black chert nodules_________-_-_------ 5 5. Chert, black, massive, brecciated ; thin dolo- mite 2 4. Dolomite, -medium-dark-gray to medium- f gray; irregularly laminated to very thin bedded ~...... L 2220... omenia re un ne inike me mk 1 3. Dolomite, dark-gray, and interbedded black chert ; dolomite beds as much as 4 in. thick and internally laminated ; chert beds 1 in. thick; chert makes up 25-50 percent of unit; pélmatozoan debris in dolomite near top 'Of u 15 Middle member : 2. Dolomite, -medium-dark-gray to medium- gray; weathers light gray ; irregular beds a few inches to a few feet thick (overall massive appearance) ; sharp color contrast with overlying darker dolomite and chert. 141 Lower member : 1. Dolomite, gray-black to dark-gray, and inter- bedded black chert; dolomite in beds as 56 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA ES-8. About 1 mile northeast of Pops Guich-Continued Ely Springs Dolomite-Continued Lower member-Continued Feet much as 1 ft thick with varied gray lam- inations; chert in fairly regular beds as much as 4 in. thick; chert makes up about 25 percent of unit; top 3 ft composed of black chert beds as much as 1 ft thick with thin dolomite interbeds-_________________ 61 Total Ely Springs Dolomite___________ 238 Conformable contact. Johnson Spring Formation. ES-9. About 1 mile northeast of Pops Gulch, T. 11 S., R. 36 E. Ely Springs Dolomite. Feet Middle member : gray, massive dolomite. Lower member : 2. Chert, black, and interbedded dark-gray to grayish-black dolomite; dolomite beds as much as 1 ft or more thick; chert beds a few inches to 1 ft thick________________ 28 1. Chert, black; some very thin irregular bed- ding; massive bold outerops-___________ 15 Total Ely Springs 43 Conformable contact. Johnson Spring Formation. ES-10. In SEV sec. 25, T. 11 S., R. 35 H. Sunday Canyon Formation. Conformable contact. Ely Springs Dolomite : Upper member : 5. Dolomite, dark-gray, knobby, irregularly bedded ; minor black chert______________ 10 4. Chert, black, massive, brecciated__________ 5 3. Dolomite, dark-gray to grayish-black, and interbedded black chert; very thin bed- ded s 52 2s er e n al uae ae cane anar awn 25 Middle member : 2. Dolomite, light- to medium-gray ; very thin nodular beds; sharp color contrast with overlying dark cherty beds______________ 105 Lower member : 1. Chert, black, massive, brecciated ; gray where Feet altered = 220 nc ner len l ea tie. s 50 Total Ely Springs Dolomite___________ 195 Conformable contact. Johnson Spring Formation. VG-1. Type section of the Vaughn Gulch Limestone, about 2 miles north-northeast of Kearsarge, T. 13 S., R. 35 H. Perdido Formation. Erosional unconformity. Vaughn Gulch Limestone : 7. Limestone, dark-gray; generally weathers me- dium gray ; in 1- to 6-in.-thick laminated beds ; interbedded with o- to 3-in.-thick black chert VG-1. Type section of the Vaughn Gulch Limestone, about 2 miles north-northeast of Kearsarge-Continued Vaughn Gulch Limestone-Continued layers; some limestone beds weather grayish orange to moderate reddish brown, which sug- gests argillaceous impurities; chert decreases near top of unit, and limestone becomes bio- clastic; coral fragments abundant at upper contact. cau el soe to wend. 96 6. Limestone, medium- to dark-bluish-gray, dense, laminated; minor argillaceous limestone______ 70 5. Argillaceous limestone and siltstone, dark-gray ; weathers light gray to grayish orange; platy to shaly fracture; generally poorly exposed; fow OLL UL Lole 105 4. Limestone, argillaceous, laminated ; red weather- ing surfaces; shaly parting; interbedded bio- clastic limestone and dense bluish-gray lime- stone abundant but not as common as in unit S._..~. mclean cl 484 3. Limestone, medium-dark-gray to medium-bluish- gray; 6-in. to 1-ft.-thick coral-rich bioclastic beds predominant; orange-weathering argil- laceous beds subordinate; minor chert________ 215 2. Limestone, like unit 1, but greater proportion of argillaceous limestone; bioclastic beds sub- ordinate; slope has yellowish tint; some black chert in lenticular beds and nodules__________ 363 1. Limestone, medium-dark-gray to medium-bluish- gray, laminated to thin-bedded; alternating sequence of bioclastic limestone and dense blue limestone; thin-bedded orange-weathering ar- gillaceous limestone subordinate; thin black chert beds and nodules present_______________ 185 Feet Total Vaughn Gulch Limestone____________ 1, 518 Conformable contact. Ely Springs Dolomite. VG-2. About % mile northeast of Squares Tunnel, T. 12 S., R. 36 E. Perdido Formation. Erosional unconformity. Vaughn Gulch Limestone: 6. Limestone, medium-gray, dense; some thinly laminated argillaceous layers; crinoid debris_. 26 . Limestone, medium-gray, and interbedded dark- gray argillaceous layers that weather moderate reddish brown to light brown ; beds are from a fraction of an inch to 1 in. thick and have a flaggy parting; commonly metamorphosed to calc-hornfels; minor crinoid debris________ 51 Limestone, medium-gray, thinly laminated ; minor argillaceous stringers which weather moderate reddish brown 23 3. Calc-hornfels, weathers light brown to moderate reddish brown, commonly thinly laminated ; much of this interval is covered _____________ 60 2. Limestone, medium-gray, beds from fraction of an inch to several inches thick; flaggy parting ; minor argillaceous beds ; crinoid debris locally 79 Feet Ot #> STRATIGRAPHIC SECTIONS 57 VG-2. About % mile northeast of Squares Tunnel-Continued Vaughn Gulch Limestone-Continued Feet 1. Limestone, argillaceous, dark-gray; weathers grayish orange; thinly laminate4____________- 25 Total Vaughn Gulch Limestone-_______---- - 264 Conformable contact. Ely Springs Dolomite. SC-1. Type section of the Sunday Canyon Formation, in Bonanza Gulch, about 4q mile northeast of Barrel Springs, T. 12 8... R. S6 R. Perdido Formation. Erosional Unconformity. Sunday Canyon Formation : 5. Limestone, dark-gray, dense, argillaceous(?) weathers grayish orange to light brown; com- monly studded with metamorphic minerals (chiefly amphibole?) ; massive to poorly bedded in 1- to 2-ft-thick beds ; interbedded black chert layers as much as 8 in. thick; 1-ft-thick blue bioclastic limestone bed about 60 ft from top contains favositid, alveolitoid, and cyatho- phylloid corals; mudstone interbedded near top Of unit: 222 20 AIEEE ore ae ae ae ea ea ues 4. Mudstone and chert, dark-gray to black; weathers light gray to moderate reddish brown; very thin bedded; some dark-gray ciclo lel ls pane.. 27 3. Limestone, dark-gray ; weathers light gray ; very thinly bedded ; flaggy parting; some bioclastic beds as much as 1 ft thick, including a par- ticularly coral-rich bed 114 ft from top of unit; some flaggy beds weather to shades of yellow, orange, or red, which suggests argillaceous im- purities; "brown dashed-line" beds near top- 2. Limestone and argillaceous limestone, dark-gray ; weathers light gray ; beds a foot or more thick ; alternates with blue-gray limestone beds that are about the same thickness and rich in fossil debris, particularly pelmatozoan, but also corals and bryozoans; argillaceous limestone beds dominant in the upper 100 ft, elsewhere they tend to be covered and bioclastic limestone layers stand out in relief on slopes-_______-- 1. Limestone, dark- to medium-gray; weathers light gray; platy splitting; very thin bedded, probably argillaceous; clastic fossil fragments in lower 55 ft; forms platy gray outcrops that might be called typical of the Silurian to the nOrEh=..... cn ncs Reece o Tul maen -oh a 133 Feet 166 217 140 Total Sunday Canyon Formation___________ 683 Conformable contact, but covered. Ely Springs Dolomite. SC-2. Perdido Formation. Erosional unconformity. Sunday Canyon Formation : 11. Shale, black; weathers light to medium gray, some with reddish shades; thinly laminated ; Section %o mile east of Johnson Spring, T. 12 S., R. 36 E. SC-2. Section %o mile east of Johnson Spring-Continued Sunday Canyon Formation-Continued mostly noncalcareous; upper 10 ft has three 1- to 2-ft-thick blue-gray limestone beds con- taining abundant fossil debris, mostly pel- matozoans; shale poorly exposed on rubbly SLOP@ | 10. Limestone, argillaceous, black to dusky-yellow, generally laminated to very thin bedded ; beds as much as 1 ft thick near top of unit ; platy to to flaggy splitting; nodular black chert inter- beds as much as 6 in. thick make up as much as 10 percent of unit____--_________________ T4 9. Shale, limy, dark-gray; weathers light gray; shaly parting; poorly exposed in rubbly slope ....._..-- 33 8. Limestone, bluegray, fine-grained; poorly de- fined thin irregular beds; few fossil frag- Feet 122 _ - 2 2.0.20 one re aree s mnie ee of l e m ee e a oe mele 10 7. Siltstone(?), limy, light-olive-gray; weathers grayish orange with small reddish spots___--- 45 6. Limestone, argillaceous, medium to dark-gray ; weathers light gray; laminated; platy pPaTIING Co.cc cll an 96 5. Limestone, argillaceous, medium- to dark-gray, weathers light gray; laminated; platy part- ing; several 1- to 3-ft-thick beds of blue-gray bioclastic limestone; Monograptus near top-. 76 4. Limestone, bluish-gray, irregular beds VM4o-1 in. thick; bioclastic (calcarenite), rich in corals and lc Loud. linens 4 3. Limestone, argillaceous, medium-gray; weath- ers dark yellowish orange to light brown; thinly laminated; platy and flaggy parting 23 2. Covered _-_... _ _s cnl dace dst a olin ee 38 1. Limestone, argillaceous; dark- to medium-gray, massive; weathers medium light gray ; locally thin irregular beds; blocky fracture; abun- dant metamorphic amphibole___________-_--- 6 Total Sunday Canyon Formation-___-____-- 524 Conformable contact. Ely Springs Dolomite. YC-3. About 1 mile northeast of Johnson Spring, T. 12 S., R. 36 E. Perdido Formation. Erosional unconformity. Sunday Canyon Formation : Feet 9. Platy and shaly beds, calcareous, argillaceous; some black chert; poorly exposed 32 8. Limestone, blue-gray, with abundant crinoidal and coral _ 9 7. Limestone, blue- to dark-gray, interbedded with flaggy argillaceous beds; calcareous beds 2-3 ft thick separated by several feet of argilla- ceous beds ; black chert nodules-___________--- 42 6. Same as unit 7, but no chert__________.________ 36 5. Quartzite and calcareous quartz sandstone, medium-gray ; minor calcareous layers; lentic- O LILA van ake 7T. 4. Limestone, blue-gray to medium-dark-gray, inter- bedded with flaggy argillaceous layers; lime- 58 STRATIGRAPHY OF PALEOZOIC FORMATIONS, SC-3. About 1 mile northeast of Johnson Spring-Continued Sunday Canyon Formation-Continued stone beds 2-3 ft thick separated by several feet of argillaceous beds; Tentaculites and graptolites near 3. Limestone, - medium-dark-gray, laminated to thinly laminated ; scattered altered pyrite crys- tals: platy 2. Limestone, argillaceous (or limy shale and silt- stone) ; platy to flaggy splitting; red-brown spots and streaks ("brown dashed-line beds") present; some blue-gray bioclastic limestone layers; scattered poor exposures in slope_____ 1. Covered Total Sunday Canyon Formation___________ Conformable contact, but covered. Ely Springs Dolomite. Feet 62 41 246 19 494 SC-4. About % mile east of mouth of Pops Gulch, T. 12 8., R. 36 E. Perdido Formation. Erosional unconformity-contact uncertain. Sunday Canyon Formation : 9. Limestone, dark-bluish-gray, fine-grained, bioclas- tic(?) ; abundant tiny pyrite crystals on some 2 o 22 2 ean ne oe er ena ine inte e anale n 8. Shale, mostly in shades of dark gray; some is slightly calcareous; poorly exposed__________ 7. Limestone, blue-gray, very thin bedded; partly bioclastic 6. Limestone, shaly (or limy shale), medium-gray to light-olive-gray; limy; dark-gray siltstone or chert float suggests thin interbeds of these materials 5. Limestone, medium-gray, sandy, and thin beds of dark-gray quartzite and black chert; one 6- in.-thick bed composed of chert fragments as much as % in. across in cherty matrix______ 4. Limestone, grayish-black, mostly very thin bed- ded, partly massive; irregular beds__________ 3. Shale, medium-gray to light-olive-gray, partly calcareous 2. Limestone, dark- to light-gray, laminated to very thin and irregularly bedded ; some fossil debris $ some Iimy 1. Shalé, calcareous, medium-gray; weathers light olive gray, with red to brown spots and "dashed lines" in some layers; blue-gray bioclastic lime- stone layers as much as a few feet thick scat- tered throughout the interval; poorly exposed rubbly outcrop; scattered graptolites from 50 ft to 270 ft above base, brachiopods about 300 ft above base, one trilobite fragment about 190 ft: above bases scn lof benno cel. Total Sunday Canyon Formation__________ Conformable contact. Ely Springs Dolomite. Feet 87 83 27 20 389 627 INDEPENDENCE QUADRANGLE, CALIFORNIA SC-5. About 1 mile northeast of Pops Gulch, T. 11 S., R. Perdido Formation. Erosional unconformity (covered). Sunday Canyon Formation : 5. Limestone, grayish-black, poorly bedded but partly laminated; bioclastic, abundant pelma- fozoan cll ccc. 4. Shale, limy, medium-gray; weathers light olive gray 3. Limestone, medium-dark-gray; very thinly and irregularly bedded; interbedded black chert layers as much as 5 in. thick; limestone beds 1 ft or more thick.... __. Lie 2. Shale, limy, medium-gray; weathers grayish orange with light-brown spots and "dashed lines"; laminated; shaly parting; some blue- gray limestone beds 4%-% in. thick ; fossil frag- MENUS as ou 202 eu oe e ooc el o anne e a wale aaa 1. Covered .... :.... /he soe L_ Total Sunday Canyon Formation____________ Conformable contact. Ely Springs Dolomite. SC-6. In SHY sec. 25, T. 11 S., R. 35 E. Perdido Formation. Erosional unconformity. Sunday Canyon Formation : 3. Shale, various shades of gray; some weathers olive gray; weakly calcareous in part_________ 2. Limestone, dark-gray, dense, very thin bedded to laminated, interbedded with black chert beds as much as 4 Jn. leone, 1. Shale, calcareous, medium-gray; weathers light gray to light olive gray or yellowish gray; reddish and brownish spots and "dashed lines" abundant; some 1- to 2-ft-thick beds of blue- gray bioclastic limestone_____________________ Total Sunday Canyon Formation-___________ Conformable contact. Ely Springs Dolomite. P-1. Rest Spring Shale. Conformable contact. Perdido Formation : 19. Sandstone, calcareous, medium-gray ; much pel- matozoan 18. Shale, dark-gray to black; fucoids locally____ 17. Sandstone,: like unit 16. Shale, like unit 15. Sandstone, like unit: _c 14. Shale. like unit _ 18. Sandstone, like unit 12. Shale, dark-gray to black ; some calcareous sand- stone beds ; fucoids locally__________________ 11. Limestone, medium-gray, laminated ; flaggy part- ing: ___ te 1 fual Saut in t nari led ere 36 E. Feet 246 374 Feet 66 17 194 277 Northeast cor. SHY, sec. 8, T. 13 S., R. 35 H. Feet Ot STRATIGRAPHIC P-1. Northeast cor. SE% see. 8-Continued Perdido Formation-Continued 10. Conglomerate, chert, quartzite, and limestone; chiefly calcareous fragments, including much pelmatozoan debris in a bluish-gray calcite matrix (calcirudite) ; quartzite and chert frag- ments angular to well rounded and as much as several inches 9. Limestone (mostly calcarenite), medium-gray laminated; splits flaggy; interbedded dark- gray argillaceous-calcareous beds as much as 6 in. thick that weather dark brownish and stand out in relief ; minor crossbedding in some limestone layers; abundant pelmatozoan frag- ments; forms prominent cliff___________«____ 8. Shale, black to dark-gray; weathers medium gray ; thin calcareous sandstone and calcare- nite beds ; fucoids abundant locally________-- 7. Siltstone; weathers olive gray to light brown; weakly calcareous ; poorly exposed ; seems to fill irregularities in underlying coarse con- glomerate Lice..., 6. Conglomerate; boulders of quartzite and lime- stone as much as several feet across; some well rounded ; quartzite most abundant; both calcareous and siliceous matrix; south of the section, boulders 10-15 ft across were seen___ . Limestone, bluish-gray, very thin bedded; some chert as fragments and thin beds______---- 4. Chert, siltstone, and some sandstone; dark colored; very thin bedded and lenticular; some limy beds; chert to the north along the south side of Vaughn Gulch contains light- colored lenses typical of chert in lower Per- (100. - 22 232 22 ate wie a an h a hace a be mie ad me ut an mace an cin n te in 3. Conglomerate; angular to rounded chert frag- ments as much as 2 in. across scattered in medium-bluish-gray limestone matrix; sandy lenses and some siltstone__________________- 2. Siltstone, medium- to dark-gray, very thin bedded 1. Mostly covered ; some chert-pebble conglomerate beds with calcareous matrix______________-- Ot "Potal Perdido Erosional unconformity. Vaughn Gulch Limestone. P-2. About %o mile northeast of Johnson Spring, T. 12 8., R. 36 E. Rest Spring Shale Conformable contact. Perdido Formation : 20. Randy. limy layer.; 19. Shale, black; weathers light gray-__________-- 18. Chert conglomerate with siliceous matrix; poorly 17. Chert conglomerate, like unit 2-_____________- 16. Shale, black; weathers light gray 15. Sandy, limy beds, very thin bedded in part; crinoidal debris common; matrix generally calcareous but partly siliceous; some pebbly beds made up predominantly of chert clasts__ Feet 12 134 49 48 42 15 19 623 Feet 43 47 23 14 36 SECTIONS 59 P-2. About %o mile northeast of Johnson Spring-Continued Perdido Formation-Continued 14. Chert granule conglomerate, granules as much as 44 in. in 13. Limestone with abundant crinoidal and: chert fragments. ~ (ealcarenite to - calcirudite?) ; sandy, limy beds present; locally, chert- granule conglomerate; some brown siltstone. 12. Shale, black ; looks 11. Siltstone, medium-gray; weathers light brown, partly thinly laminated--=-______._-.___L._. 10. Conglomerate and sandstone with limestone matrix; conglomerate a few feet thick at base, grades up to very thin bedded medium-gray gandy . unc occ cael 9. Chert, black, massive; overlain by pebble and granule conglomerate in which chert clasts are predominant; both chert and quartzite clasts well rounded and as much as several inches across; weathers dark gray te vas 8. Covered. probably 7. Conglomerate; limy matrix; black chert clasts as much as several inches across; quartzite clasts also 6. Shale, lec 5. Cherty conglomerate, like unit 2-_________---- d. Covered 12222000000 Ean dea ase aut 3. Limestone, sandy, medium-bluish-gray, irregu- larly bedded; black chert as nodules and ir- regular beds; some crinoidal debris_______-- 2. Conglomerate, dark-gray, poorly bedded; argil- laceous-siliceous matrix with scattered frag- ments and pebbles as much as 2 in. in diam- eter ; clasts mostly chert ; some gray quartzite 1. Shale and siltstone, medium-gray; shaly to papery parting; many joint faces and silty layers weather moderate reddish brown, in contrast to gray-weathering shales; calcar- eous shale bed about 140 ft above Total Perdido Formati0H..... us Erosional unconformity. Sunday Canyon Formation. P-3. About % mile east of mouth of Pops Gulch; T. R. 96 E. Rest Spring Shale. Conformable contact. Perdido Formation : 23. Limy sandstone (or sandy limestone(?)), me- dium-gray, massive ; some pelmatozoan debris 22. Shale, mudstone, and chert (?) ; black, very thin bedded ; chert and mudstone layers as much as 1 ft thick separated by shale partings as much as 2 in. thick ; 1- to 2-ft thick limy sand- stone tan 21. Limestone, medium-gray, very thinly and irregu- larly bedded; weathers to yellowish and brownish shades; some thin chert layers-___-- 20. Mudstone and siltstone, dark-colored ; weathers moderate reddish brown-______________-_------ 19. Sandy limestone and some fine-grained quartzite in a structurally disturbed bed_______------ Feet 7T 21 15 15 14 w o to A 10 22 224 550 12 8., Feet 29 13 12(?) 60 STRATIGRAPHY OF PALEOZOIC FORMATIONS, INDEPENDENCE QUADRANGLE, CALIFORNIA P-3. About % mile east of mouth of Pops Gulch-Continued Perdido Formation-Continued 18. Mudstone and shale, dark-gray to black, very 17. 16. 15. 14. 13. 12. JF 10. thin bedded; weathers moderate reddish brown; shaly to flaggy parting; some chert conglomerate in lenticular beds as much as 1 ft thick; some limy sandstone; fucoids locally l rsn lt o.. Sandy limestone, medium-gray________________ Mudstone, siltstone, conglomerate, and sandy limestone, interbedded ; includes 2-ft-thick bio- clastic limestone bed having abundant pel- matozoan Conglomerate and sandstone; grayish-black ma- trix; partly calcareous, partly siliceous; pel- matozoan fragments and other clasts weather out leaving a pitted surface ("cinder rock") ; scattered but prominent chert clasts as much asd utc _ O Mudstone and siltstone, poorly exposed________ Sandy limestone, thin-bedded to laminated ; some mudstone and chert beds____________________ Siltstone, mudstone, and shale, black to dark- gray; some weathers light gray, but most weathers to red and brown shades; subordi- nate limy sandstone beds; rubbly exposure___ Sandy limestone, medium-gray, and lesser black mudstone; much variation in grain size and carbonate content of sandy beds; some chert beds as much as 6 in. thick, and some granule and pebble conglomerates composed of lime- stone fragments in sandy limestone matrix__. Mudstone, black, and lesser sandy limestone; limestone beds from 6 in. to several feet thick (some discordance of the sandy beds, which appear to have "squirted" around in the muddy . Sandy limestone, medium-gray to medium-dark- gray; abundant clastic carbonate and lesser fragments of chert and mudstone ; black mud- stone interbeds as much as a few feet thick; upper 9 ft is a massive sandy limestone con- taining abundant well-rounded well-sorted qnartz l_ __ ___ . Mudstone, gray-black to black, very thin bedded ; weathers dark reddish brown; some of unit may be chert. . Sandstone and conglomerate ; mostly chert clasts in gray-black siliceous mudstone matrix; commonly weathers reddish brown-_________ Bhale, black. -_: nd eer ees Lac . Conglomerate, medium-gray limestone matrix; clasts mostly chert, but some quartzite and carbonate; some slabby chert fragments as much as 2 ft long and medium-gray quartzite clasts as much as 6 in. long; clasts angular to well rounded and range from coarse sand to pebbles in a limy matrix; some chert grit and shale near LODs e n neal o niin area de od age Erosional unconformity. 4. Shale, mudstone, and chert(?), gray-black; weathers light gray to moderate reddish brown; very thin bedded, but partly irregular Feet 28 25 41 28 28 33 26 31 P-3. About % mile east of mouth of Pops Gulich-Continued Perdido Formation-Continued Feet slabs and flags; one sandy limestone lens 1 ft thick -and 8 ft long."... _:L__ 12 24 3. Conglomerate; mostly well-rounded chert clasts as much as 2 in. thick in dense black matrix___ 3 2. Shale, dark-gray to black; weathers light gray to dark red-brown; some shale fucoidal and interbedded with nodular beds of black chert as much as 8 in. thick ; prominent white lenses are present in this unit to the south on ridge ._ LQ it P2 1. Shale, various shades of gray-black to light- gray, laminated to very thin bedded; some finely laminated dark-gray siltstone; some beds richly sprinkled with metamorphic min- erals, mostly tremolite; these beds are dark gray but commonly weather red or brown; shales are partly fucoidal._________________ 130? Total Perdido Formation-________________ 557 Erosional unconformity. Sunday Canyon Formation. REFERENCES CITED Albers, J. P., and Stewart, J. H., 1962, Precambrian(?) and Cambrian stratigraphy in Esmeralda County, Nevada in Short papers in geology, hydrology, and topography : U.S. Geol. Survey Prof. Paper 450-D, p. D24-D27. Barnes, Harley, and Byers, F. M., Jr., 1961, Windfall Forma- tion (Upper Cambrian) of Nevada Test Site and vicinity, Nevada in Short papers in the geologic and hydrologic sciences : U.S. Geol. Survey Prof. Paper 424-C, p. C103-C106. Barnes, Harley, Christiansen, R. L., and Byers, F. M., Jr., 1962, Cambrian Carrara Formation, Bonanza King Formation, and Dunderberg Shale east of Yucca Flat, Nye County, Nevada in Short papers in geology, hydrology, and topog- raphy : U.S. Geol. Survey Prof. Paper 450-D, p. D27-D31. Barnes, Harley, and Palmer, A. R., 1961, Revision of strati- graphic nomenclature of Cambrian rocks, Nevada Test Site and vicinity, Nevada in Short papers in the geologic and hydrologic sciences: U.S. Geol. Survey Prof. Paper 424-C, p. C100-C103. Berry, W. B. N., 1965, American Early Devonian monograptids [abs.] ; Geol. Soc. America Spec. Paper 82, p. 11. Burchfiel, B. C., 1964, Precambrian and Paleozoic stratigraphy of Specter Range quadrangle, Nye County, Nevada: Am. Assoc. Petroleum Geologists Bull., v. 48, no. 1, p. 40-56. Byers, F. M., Jr., Barnes, Harley, Poole, F. G., and Ross, R. J., Jr., 1961, Revised subdivision of Ordovician System at the Nevada Test Site and vicinity, Nevada in Short papers in the geologic and hydrologic sciences : U.S. Geol. Survey Prof. Paper 424-C, p. C106-C109. Calkins, F. C., and Butler, B. S., 1943, Geology and ore deposits of the Cottonwood-American Fork area, Utah: U.S. Geol. Survey Prof. Paper 201, 152 p. Cooper, G. A., 1956, Chazyan and related brachiopods [U.S. Canada): Washington, D.C., Smithsonian Misc. Colin., v. 127, pt. 2, p. 1025-1245. REFERENCES CITED 61 Cornwall, H. R., and Kleinhampl, F. J., 1961, Geology of the Bare Mountain quadrangle, Nevada : U.S. Geol. Survey Geol. Quad. Map GQ-157. Elles, G. L., 1925, The characteristic assemblages of the grapto- lite zones of the British Isles : Geol. Mag. [Great Britain], v. 62, no. 8, p. 337-3417. Ferguson, H. G., Muller, S. W., and Cathcart, S. H., 1954, Geol- ogy of the Mina quadrangle, Nevada: U.S. Geol. Survey Geol. Quad. Map GQ-45. Gordon, Mackenzie, Jr., 1964, California Carboniferous cepha- lopods : U.S. Geol. Survey Prof. Paper 483-A, 27 p. Greife, J. L., and Langenheim, R. L., Jr., 1963, Sponges and brachiopods from the Middle Ordovician Mazourka For- mation, Independence quadrangle, California : Jour. Paleon- tology, v. 37, no. 8, p. 564-574. Hall, W. E., and MacKevett, E. M., Jr., 1962, Geology and ore deposits of the Darwin quadrangle, Inyo County, Cali- fornia: U.S. Geol. Survey Prof. Paper 368, 87 p. Hazzard, J. C., 1937, Paleozoic section in the Nopah and Rest- ing Springs Mountains, Inyo County, California : California Jour. Mines and Geology, v. 33, no. 4, p. 273-839. Hazzard, J. C., and Mason, J. F., 1936, Middle Cambrian for- mations of the Providence and Marble Mountains, Cali- fornia: Geol. Soc. America Bull., v. 47, no. 2, p. 229-240. Hewett, D. F., 1956, Geology and mineral resources of the Ivanpah quadrangle, California and Nevada: U.S. Geol. Survey Prof. Paper 275, 172 p. Hotz, P. E., and Willden, C. R., 1955, Lower Paleozoic sedi- mentary facies transitional between eastern and western types in the Osgood Mountains quadrangle, Humboldt County, Nevada [abs.]: Geol. Soc. America Bull., v. 66, no. 12, pt. 2, p. 1652. Johnson, M. S., and Hibbard, D. E., 1957, Geology of the Atomic Energy Commission Nevada proving grounds area, Nevada : U.S. Geol. Survey Bull. 1021-K, p. 333-384. Kirk, Edwin, 1933, The Eureka quartzite of the Great Basin region: Am. Jour. Sci., 5th ser., v. 26, no. 151, p. 27-44. Knopf, Adolph, 1918, A geological reconnaissance of the Inyo Range and the eastern slope of the southern Sierra Nevada, California, with a section on the stratigraphy of the Inyo Range, by Edwin Kirk: U.S. Geol. Survey Prof. Paper 110, 130 p. Langenheim, R. L., Jr., Barnes, J. A., Delise, K. C., Ross, W. A., and Stanton, J. M., 1956, Middle and Upper (?) Ordovician rocks of Independence quadrangle, California: Am. Assoc. Petroleum Geologists Bull., v. 40, no. 9, p. 2081-2097. McAllister, J. F., 1952, Rocks and structure of the Quartz Spring area, northern Panamint Range, California: Cali- fornia Div. Mines Spec. Rept. 25, 38 p. McKee, E. H., and Moiola, R. J., 1962, Precambrian and Cam- brian rocks of south-central Esmeralda County, Nevada: Am. Jour. Sci., v. 260, no. 7, p. 530-538. Merriam, C. W., 1940, Devonian stratigraphy and paleontology of the Roberts Mountains region, Nevada: Geol. Soc. America Spec. Paper 25, 114 p. 1963a, Paleozoic rocks of Antelope Valley, Eureka and Nye Counties, Nevada: U.S. Geol. Survey Prof. Paper 423, 67 p. 1963b, Geology of the Cerro Gordo mining district, Inyo County, California: U.S. Geol. Survey Prof. Paper 408, 83 p. Merriam, C. W., and Hall, W. E., 1957, Pennsylvanian and Permian rocks of the southern Inyo Mountains, California : U.S. Geol. Survey Bull. 1061-A, p. 1-15. Morris, H. T., and Lovering, T. S., 1961, Stratigraphy of the East Tintic Mountains, Utah: U.S. Geol. Survey Prof. Paper 361, 145 p. Nelson, C. A., 1962, Lower Cambrian-Precambrian succession, White-Inyo Mountains, California: Geol. Soc. America Bull., v. 73, no. 1, p. 139-144. 1963, Preliminary geologic map of the Blanco Mountain quadrangle, Inyo and Mono Counties, California: U.S. Geol. Survey Mineral Inv. Field Studies Map MF-256. Nelson, C. A., 1965, Monola Formation, in Cohee, G. B., and West, W. S., Changes in stratigraphic nomenclature by the U.S. Geological Survey, 1963: U.S. Geol. Survey Bull. 1194-A, p. A29-A33. Noble, L. F., 1934, Rock formations of Death Valley, California : Science, n.s., v. 80, no. 2069, p. 173-178. Nolan, T. B., 1943, The Basin and Range provinces in Utah, Nevada, and California: U.S. Geol. Survey Prof. Paper 197-D, p. 141-196. Nolan, T. B., Merriam, C. W., and Williams, J. S., 1956, The stratigraphic section in the vicinity of Eureka, Nevada : U.S. Geol. Survey Prof. Paper 276, 77 p. Palmer, A. R., and Hazzard, J. C., 1956, Age and correlation of Cornfield Springs and Bonanza King formations in south- eastern California and Southern Nevada: Am. Assoc. Pe- troleum Geologists Bull., v. 40, no. 10, p. 2494-2499. Pestana, H. R., 1960, Fossils from the Johnson Spring forma- tion, middle Ordovician, Independence quadrangle, Cali- fornia: Jour. Paleontology, v. 34, no. 5, p. 862-873. Phleger, F. B., Jr., 1933, Notes on certain Ordovician faunas of the Inyo Mountains, California: Southern California Acad. Sci. Bull., v. 32, pt. 1, p. 1-21. Poole, F. G., 1965, Geology of the Frenchman Flat quadrangle, Nye, Lincoln, and Clark Counties, Nevada: U.S. Geol. Survey Geol. Quad. Map GQ-456. Poole, F. G., Houser, F. N., and Orkild, P. P., 1961, Eleana For- mation of Nevada Test Site and vicinity, Nye County, Ne- vada in Short papers in the geologic and hydrologic sciences: U.S. Geol. Survey Prof. Paper 424-D, p. D104- D111. Rinehart, C. D., and Ross, D. C., 1964, Geology and mineral deposits of the Mount Morrison quadrangle, Sierra Ne vada, California: U.S. Geol. Survey Prof. Paper 385, 104 p. Roberts, R. J., Hotz, P. E., Gilluly, James, and Ferguson, H. G., 1958, Paleozoic rocks of north-central Nevada: Am. Assoc. Petroleum Geologists Bull., v. 42, no. 12, p. 2813-2857. Ross, D. C., 1963, New Cambrian, Ordovician and Silurian for- mations in the Independence quadrangle, Inyo County, California in Short papers in geology and hydrology : U.S. Geol. Survey Prof. Paper 475-B, p. BT4-B85. 1965, Geology of the Independence quadrangle, Inyo County, California: U.S. Geol. Survey Bull. 1181-0, 64 p. Ross, R. J., Jr., 1951, Stratigraphy of the Garden City forma- tion in northeastern Utah and its trilobite faunas: Yale Univ., Peabody Mus. Nat. History Bull. 6, 161 p. 1964, Middle and Lower Ordovician Formations in southernmost Nevada and adjacent California: U.S. Geol. Survey Bull. 1180-C, 95 p. Ross, R. J., Jr., and Berry, W. B. N., 1963, Ordovician grapto- lites of the Basin Ranges in California, Nevada, Utah, and Idaho : U.S. Geol. Survey Bull. 1134, 177 p. Spencer, A. C., 1917, The geology and ore deposits of Ely, Ne- vada : U.S. Geol. Survey Prof. Paper 96, 189 p. Stauffer, C. R., 1930, The Devonian of California: California Univ. Dept. Geol. Sci. Bull., v. 19, no. 4, p. 81-118. 62 STRATIGRAPHY OF PALEOZOIC FORMATIONS, Stille, Hans, 1940, Einfiihrung in den Bau Amerikas: Berlin, Gebriider Borntraeger, 717 p. Twenhofel, W. H., chm., 1954, Correlation of the Ordovician formations of North America: Geol. Soc. America Bull., v. 65, no. 8, p. 247-298. Waite, R. H., 1953, Age of the "Devonian" of the Kearsarge area, California [abs.] : Geol. Soc. America Bull., v. 64, no. 12, pt. 2, p. 1521. INDEPENDENCE QUADRANGLE, CALIFORNTA Webb, G. W., 1958, Middle Ordovician stratigraphy in eastern Nevada and western Utah: Am. Assoc. Petroleum Geolo- gists Bull., v. 42, no. 10, p. 2335-2377. Westgate, L. G., and Knopf, Adolph, 1932, Geology and ore de- posits of the Pioche district, Nevada: U.S. Geol. Survey Prof. Paper 171, 79 p. Winterer, E. L., and Murphy, M. A., 1960, Silurian reef com- plex and associated facies, central Nevada : Jour. Geology, v. 68, no. 2, p. 117-139. Abstract . ...-- 7 correlation . distribution fossils. . .... lithology --. Ampyz sp. --- Analysis, Atrypina .. 31 B . Badger Flat Limestone, age. 13 cortelation 2 s B0. EAI 18 distriblition. _- .s. 22. 12 stratigraphic relations . stratigraphic sections. ......__- thickness "-..... lad kers 12 Sy pe sectioh _-. .>. s 2.0 cous 45 Barrel Spring Formation, age. 17 CorrelSfONn - 1 20220008 se 20.0000 120 oll 17 (DSHMIDUHION : 2.0 000.00. 0 Leer oan 15 slic on nt Lon ee pe de slu 17: lithology. 15 lower member..----- 15 stratigraphic relations . . .. ._... .. 15 stratigraphic sections. ....._.________ ___- 45-47 thickness......-- % 15 type section.. .. 46 upper member. . 16 Barrel Springs, sections near.... ._ 45, 46, 49, 50, 54, 57 Bee Springs, section near..___.___________._. 45, 47 Berry, W. B. N., fossil identification . . ..._._. 33 Blue Bell mine, section near...__._.__ 43 Bluestone tale mine, section at . _..___.__._.__. 54 Bonanza Gulch, section in-...__._._______.___ 57 Bonanza King Dolomite, age...... ; 4 correlation . _ ; ~ 4 distribution . ¥ 8 fosslly. 0. .. one un cou MeL LUO niid es 4 0. 02. E20 0.0 CE ce ice 8 stratigraphic relations . . .... 5 8 stratigraphic section......._.______._______ 43 thickness.."....." e aaa Yc usan 8 6, 14, 17, 21, 22, 23, 28, 31, 33 AA nll. 14, 17, 22, 23, 31 € f Ness . E 14 aol all 3 Cephalopods. .___.t...._... 5 if, 283, 31 f ... Af Chonophylium.. ...... --- lie LLL __ 0 1 INDEX [Italic page numbers indicate major references] Page Color banding, Bonanza King Dolomite... 3 Nopah 9 Tamarack Canyon Dolomite..........--~ 9 Conchid@tnt. .) 1, dect Adsl Cnt Laden aoe 31 Conodonts. c: 14 Contact metamorphism . ...... ___. 16 Copenhagen Formation.. 24 Coran £.... 00 0000.0 sive 14, 21, 22, 28, 31, 33 CrATendderas. .... .2 200 uc uud aan, ciel s 38, 40 Crhtenbeeratobde$.. \... .. ..x WRU nner nan 40 Crepe structure.. .s 2. ...o. leas cei 10 Crystiphyllim Bp . . l 0. 000, 33 D Desmorthis 8p .. . . .- -- --- - Devonian System . .. correlations... - ___ facies 'Dicellograptus isp a DunderbergiBhale............_.__...- DrinderDergi@RONG. .._. 7 E BRutoliHh s. 22020050000 e oue e uled mads 31 A 6 Elvinia zone.... A 7 Ely Springs Dolomite, ago. ...........------- 28, 29 correlation. >. - 2. Gani ces 28, 29 ae... fossils ..cu 2.1 adel uce s 28 su- > #6 lower 26 middle 26 stratigraphic relations stratigraphic sections. thickness........... upper members #7 Emigrant Formation 7 Eof@HChEMQED.. ... .ll ten na ces 24 Bureka . .< _: s. 24 F . C4 cowl cL acini n oc 48 Famistelln discrela .< .. 1 dul oust gks oue 23 24 sp........_.. 33 Penestelln §p-.:.. 10200-00000 A0 IO. nasi cage 40 ece. tee de n aie nano- I Se s 41 SDL L 12000 doll Mn dated ener acl sens 40 ./. .. 48 Fossils, Al Rose Formation... ...__....._...._ 11 Badger Flat Limeston@.._.____.._...___-. 18 Barrel Spring Formation.....____..__..._. 17 Bonanza King Dolomite...______.__..._._.. 4 Ely Springs 28 Johnson Spring Formation. .........~..-- 28 Lead Gulch Formation......___..._....-- 6 Perdido 87 Vaughn Gulch Limestone. 81 Fucold- markings... -- ot rie 4 G Page .... .... 14, 22, 28 Girty, G. H., quoted.. s Goniatites.........-- & Gordon, Mackenzie, Jr.,"foss1l identification... 37, 40 Graptolites. .. Somali on oon 11,17, 32 Great Basin, str - 48 Heliolites . _ a 31 FHlesperorthi 17 dubia. - # 18 Heteralosia 41 Bp.... ..... ...l Se L211 .cc 40 Hidden Valley DolOMit@__.___.----.---------- 34 Fiomagnostus. ...-- 7 8D. .... cll ec 6 s.... s; ... 22. . BRR L2 cc lc clue eel 40 7 14 _____ 17,18 ,,,,,,,,,,, 18 ion near. . . . 44, 45, 47, 50, 51, 52, 54, 55, 57, 59 28 _________________ 22 ___________ 24 crinoidal dolomite.....__A.____...._____. 21 distribution . . .. £ 19 F.. Olen Al coco noe danae e 28 lithology >- 40 lower limestone. . 22 lower quartzite . . - 20 middle quartzite . 22 nixed .. :2 ..0- ... 21 relation to Eureka Quartzite.....__._.. .- 21 stratigraphic relations.. 1. ...... _...... 19 stratigraphic sections. 47-58 thickness. .- s 19 type section 50 upper dolomite... 22 upper quartzite. _.. 20. eL 22 K Kearsarge, section Near. ise 56 L Lead Gulch Formation, Age. .-.-------------- 6 Correlation: _ 7. . 0s. aghe. c lous conect. 6 distribution -- 2/0. steel. se toul aude 5 fossils . ). .o. n ocio eae ain ena 6 lithology ...-. grr .ll... 5 stratigraphic relations. .......--.--------- 5 Lic ies 6 typé SeCHON. .-.. 2200000004 44 8D . ._. cc ccc cc cence >> 28 n. Cole ool orev eens 6 Sod. 64 INDEX Page Lonehodomns. 01 cians 18 Stratigraphic section-Continued 17 44 Lone Mountain Dolomite.....________________ 35 58 59 M 50 57 Mazourka Canyon, section...________________ 44 57 Mazourka Group 9 57 Merriam, C. W., quoted. _. 31 58 Mexican Gulch, section in.. 46 stratigraphic relations . 39 58 Missigsipplan 35 thickness._______ 39 58 Monopraptus dirbies. .. .io. .. lol 33 Reticulariina campestris 38 44 hercynicus . _ 33 Degen cc sc onsen ot. on l cal on aao 38 56 scanius.. ___ 33 Retdemannoceras sp. ...... .... 14 56 uniformis.. 33 .... . ..... .... 22 conn 2 oleae nlc, 31 Streptelasma tennysoni ‘ 23 83 Rhysostrophia mevadensis..____________________ 14 spell. 28 33 occidentalis. . .________ n 14 Strombodes . ‘ 31 CV. O0. 14 Roberts Mountains Formation..__.__________ 34 sungisirifigi F0 \ j ii * NMieoftella sp -__ Lo L__._:*': L094 / 23 Ross, R. J., Jr., fossil identification._.._.______ 11 lossils .._ 52 4 14, 17, 18, 23, 33 so 8D... . ...l o sls caren. Lol Leal < 14 s2 ) 001 s clave. clean t s Lone A £ Ast a 12 57,58 /__ Oliver, W. A F., te 33 8 s thickness. ._. _. 82 P Ordovician Syst m FW . i type-section. -~ - ele Po b Bee .. .. _._... 57 Orthambonites d -- 17/18; # Scolthus """""""""" P0 # ________ 14 Semicostella 2 41 g __________ 4 O| - 40 .B ______ 17 Sfmmfzrdm arrears ias 12 Tamarack Canyon Dolomi 3 1740 9 __________ 14 Silurian Sy§tem,_ 29 4. 9 ____________ 33 y C -Red. £2. . ABELL GBs c cl. 322... 2. 9 * Iithology - -L 2. _.2. ~* 8 «stratigraphic relations . 8 Palaeophyllum mazout 24 [ thickness |___... #. 8 - rugosum.____ j 23 type 2. nicl loud clit ice 44 23 entaculites bellwime =-. & .0.2 ES) 23 Tetragraptus bigsbyi_.. fk: 11 24 Thomnopore #p... Ad AURA OOO OLE. 33 24 Trigonocerca sp . 12 42 Trilobites. . ___. at beef i 6,7, 11, 14, 17, 31 ta Palmer, A. R., fossil identificat Parabollinella Vaughn Gulch Limestone, age. ...._.________ 8! correlation.. _... distribution 30 distribution . _... t.)... AIAL 86 £ 81 fosslls....._..._ t 3 37 lithology. --.. .. Ray il e ole i 81 lithology 00.0.0 0...c0 36 stratigraphic relations. sir ince - 30 sediment source. K..l ! 48 stratigraphic sections.. ._. 56, 57 stratigraphic relations . £ 4 85 thickness _. g stratigraphic sections type section .. __ 5 thickness.._______ 35 Verticillopora annulata Phacelophyltwm.... «~ C>... 2 41.0600 31 P Phyllograptus anna. . .____ 11 Hicifolius.. . ...._____ t A1 j Plaesiomys l 3 6. is Water Canyon, section in . __. 45 glantfteg . 40 williams, 7.88., #201... ___... a1 ogonip Group...__________ ________ , 4 Pops Gulch, sections near. __. Willow Springs Canyofi sectlon in 46, 48, 53 Previous stratigraphic studies Windfall Formation . Z Pseudagnostus Catlin Member. $p. a. 49 Worm trails. 4 Pseudomera sp . _ 50 Ptychopleurella sp. .___.______ A 50 Y ' Pycnostylus guelphensis______________________ C 51 ? 51 Yochelson, E. L., fossil identification ._______ 14 s 51 3.000. .I lnt nol 52 Z Roofs: 2s. 290200 e nlp. Ral. LIB 35 100200000 i bet cae s proove d dan ious 82 . ~ Zuygospira sp... ___. Pome a 23 g U.S. GOVERNMENT PRIN ° 2s 5 ig H f P g # ~ + _ ami F wong d ol) 44 -. f UNITED STATES DEPARTMENT OF THE INTERIOR PROFESSIONAL PAPER 396 SYSTEM CARB ONIFEROUS Mississippian SILURIAN AND DEVONIAN(?) Pa m a > 0 a s 0 CAMBRIAN SERIES GEOLOGICAL SURVEY PLATE 2 GENERAL FORMATION IZED SECTION CHARACTER OF ROCKS IN FEET Shale and siltstone, dark-gray; commonly weathers reddish brown; contains minor sandstone. - Carbonaceous-rich layer near middle contains goniatite fragments. - Much of unit is metamorphosed to andalusite hornfels Rest Spring Sha Clastic rocks, fine- to coarse-grained, lenticular and variable. Chert is abundant as granule- to boulder-sized clasts; quartzite frag- ments are also common. Calcareous quartz sandstone lenses abundant. Dark-reddish-weathering bold outcrops are diagnostic Vaughn Gulch Limestone: Sunday Canyon Formation: Limestone, silty, dark-gray, thin-bedded; chert Argillaceous limestone and mudstone, dark-gray; layers; corals near top; 96 ft thick interbedded with black chert; 166 ft thick Limestone, dark-bluish-gray, laminated; 70 ft thick Mudstone and chert, dark-gray; minor limestone; 27 Argillaceous limestone and siltstone; platy fracture; §. ft thick 105 ft thick Perdido F fist Argillaceous limestone, dark-gray; yellow flaggy Argillaceous limestone, laminated; lesser bioclastic weathered slopes; minor coral-rich layers; 217 ft limestone; 484 ft thick thick Bioclastic limestone rich in coral fragments, bluish- Argillaceous limestone, dark-gray, and blue-gray gray; minor chert; 215 ft thick Sunday bioclastic layers rich in corals; 140 ft thick Argillaceous limestone and lesser bioclastic lime- Canyon Argillaceous limestone and calcareous shale, stone; yellow outcrops; black chert nodules and Formation medium-gray, yellow-weathering, very thin layers; 363 ft thick bedded, Monograptus-bearing; 133 ft thick Bioclastic limestone, medium-bluish-gray; lesser Vaughn T argillaceous limestone; black chert; 185 ft thick Gulch f Limest -E €, W massive; ules; 49 ick Chert, black; nodular irregular layers; 17. ft thick Ely Springs 75-7 y Dolomite, dark-gray, and black chert interbedded in thin layers; 56 ft thick Dolomite h Dolomite, medium-gray, well-bedded; 79 ft thick o Dolomite, dark-gray, massive to poorly bedded; scattered black chert nodules; 56 ft thick Johnson Spring Dolomite, dark ; in lar beds 1-4 in. thick; thin chert interbeds; 85 ft thick Formation : Quartzite, white, massive; 17 ft thick ng s Dolomite, dark-gray, massive; scattered chert nodules; 20 ft thick £ on > 6... Limestone, dark-gray, irregularly bedded; silty layers; corals and other fossils; 47 ft thick Quartzite, white, massive; some calcareous cement; 34 ft thick Mixed unit of clastic and carbonate rocks; 59 ft thick rtzite, white to yellow, crossbedded; calcareous cement in part; 35 ft thick Shale, weathers a distinctive red brown; fossils near base; 78 ft thick Limestone, medium-gray; irregular beds interlayered with siltstone; 29 ft thick ite, impure, and li int red and mixed; ft thick Limestone; irregularly bedded calcarenite with brown-weather ing silty lenses; 90 ft thick. Al R05? > Some thin quartzite beds. Abundant fossils Formation . Limestone and bluish-gray calcarenite in irregular beds; abundant brown-weathering siltstone lenses: black chert in thin beds 'and nodules; 500 ft thick. Fossils abundant locall Shale, mudstone, and lesser limestone, red-brown-weathering; 50 ft thick. Graptolites near top Si eri lesser I } Badger Limestone Mazourka Group Tamarack Canyon 3 C A 4 Dolomite Dolomite, medium-gray, massive to thin-bedded; 272 ft thick Dolomite, medium-gray, laminated; 123 ft thick Dolomite, same as above, but contains black chert nodules; 515 ft thick Lead Gulch Limestone, siltstone, dolomite, chert, and shale interbedded in thin regular layers, brown-weathering; Formation trilobites near base Dolomite, medium- to yellowish-gray, massive, poorly bedded; 205 ft thick Dolomite, varied gray and banded (thin irregular bedding characteristic of bottom 2618 ft of formation); 524 ft thick Dolomite, banded in varied shades of gray, darker shades dominant; Grvanella in upper part; 564 ft thick Dolomite, banded in varied shades of gray, lighter shades dominant;.1026 ft thick Dolomite, banded in varied shades of gray; darker shades dominant; 504 ft thick. Abundant Girvanelle as well as fucoids and other worm traillike markings Bonanza King Dolomite GENERALIZED COLUMNAR SECTION OF PALEOZOIC ROCKé IN INDEPENDENCE QUADRANGLE, INYO COUNTY, CALIFORNIA 212-460 O - 66 (In pocket) % UNITED STATES DEPARTMENT OF THE INTERIOR PROFESSIONAL PAPER 396 GEOLOGICAL SURVEY PLATE 3 THICKNESS, THICKNESS, IN FEET IN FEET N JS-2 JS-1 S Koo. 3 I% i- 400" we (matfl‘,t a eft". Upfi/ it yak ~> jot" I% i "Aes ypP® fea f see /// C 0 Type section of Johnson Spring Formation g ; x 5 & T ; - he t f a up Boge: Middle quartzite g - 200" a C 0 w c € 0 Aes .n o y colo 35 100' - 1 Lower limestone (Pugs Lower quartzite O a - 0 Shale and siltstone - __ _s 5 "Fe a ad F § s ae -=) £ teo nes gents. BS-2 BS-1| 5 real set, mo? up cdo 3 - 100" rzite a ® f ls © S 6 [% c BS- 3 G= Type section of Barrel Spring Formation §" ok a" m "avg-"MEASURED SECTIONS OF BARREL SPRING AND JOHNSON SPRING FORMATIONS, INDEPENDENCE QUADRANGLE, INYO COUNTY, CALIFORNIA LOCATION OF SECTIONS IS SHOWN ON THE GEOLOGIC MAP, AND DESCRIPTION OF SECTIONS IS GIVEN IN TEXT 212-460 O - 66 (In pocket) Less UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY PROFESSIONAL PAPER 396 PLATE 4 THICKNESS, IN FEET 600' 500° 400" 300° 200' 100' N Ys o 1 MILE Ely Springs Dolomite THICKNESS, IN FEET $ 600° lade F- 400' 300" 200' 100 MEASURED SECTIONS OF THE ELY SPRINGS DOLOMITE, INDEPENDENCE QUADRANGLE, INYO COUNTY, CALIFORNIA LOCATION OF SECTIONS IS SHOWN ON T HE GEOLOGIC MAP, AND DESCRIPTION OF SECTIONS IS GIVEN IN TEXT 212-460 O - 66 (In pocket) 6 |. UNITED STATES DEPARTMENT OF THE INTERIOR 26 fa PROFESSIONAL PAPER 396 GEOLOGICAL SURVEY PEATE 5 K. Independence quadrangle : New York Butte quadrangle Quartz Spring area Darwin quadrangle Sunday Canyon area Vaughn Gulch area (Merriam, 1963b) (McAllister, 1952) (Hall and MacKevett, 1962) THICKNESS ; ; IN -FEET m 6000' Keeler Canyon Formation (Pennsylvanian and Permian) 4 E) -5000' ea A 2 < k z- zZ - L_ u < s a. > C 4 Keéler Canyon Formation me a= /// A Lee Flat Limestone E - 4000" 7 < (Pennsylvanian and Permian) |[-1==1- t & A f is_. Q. eee mak t --- Perdido Formation a cp" | -=- (lower member) g L $54 f ~ <> T 3000 Stele t |- -->> Tin Mountain Limestone g 3000" cll H In é ~- _- Y I par ~ yeas {ac |- 1000" Perdido Formation |~ $0 > /k & Aa Ff] <= Vaughn Gulch 5:3) £ o a fite 1 :. osi 4 --- i- . g t* .! "lgDEX/LQ?) S; eye git/// e s lg] TIL Limestone a n as Z Hidden Valley Dolomite 3 z of SILU- |e "ae < marl ~.. __ ol Sere 2% | | Rian ormation =--] 3x =- % _L < 35 E 3, A Ely Springs Dolomite _ c- Ely Springs Dolomite (Ordovician) WWW 7, 6A A é (Ordovician) 19 20 MILES I % TO ROCKS IN AREAS TO THE SOUTHEAST IN CALIFORNIA -__ DIAGRAM SHOWING RELATION OF SILURIAN, DEVONIAN(?), AND MISSISSIPPIAN ROCKS OF THE INDEPENDENCE QUADRANGLE 212-460 O - 66 (In pocket) PROFESSIONAL PAPER 396 UNITED STATES DEPARTMENT OF THE INTERIOR PLATE !; GEOLOGICAL SURVEY ; 00 FEET yam ple . R Blue c- as T a ] €1 to W ;, £0 , & EXPLANATION CENG: ZOIC Alluvial deposits MESO- ZOIC Granitic rocks Owens Valley and Keeler Canyon Formations PENNSYL- VANIAN AND PERMIAN Rest Spring Shale Siltstone, shale, and mudstone, dark-gray; commonly metamorphosed to andalusite hornfels. Pattern shows locally mapped zone of carbon-rich beds that contain cravenocerid goniatites Upper Mississippian INEC #2 MISSISSIPPIAN poon," CARBONIFEROUS Perdido Formation Mized clastic sequence of sandstone, conglomerate, calcarenite, and shale; chert clasts are abundant J UNCONFORMITY Sunday Canyon and Vaughn Gulch Formations DSsc, Sunday Canyon Formation: graptolitic limy shale facies; limy shale, shale, and lesser limestone DSvg, Vaughn Gulch Limestone: bioclastic lime- stome facies; thinly bedded limestone and argil- laceous limestone, rich in coral and sponge frag- ments R y- SILURIAN AND DEVONIAN(® Ely Springs Dolomite Dolomite,light- to dark-gray, thin- to thick-bedded; contains abundant black chert ( Ojs Johnson Springs Formation Mized sequence of quartzite, dolomite, limestone (in part coral-bearing); lesser siltstone and shale Upper Ordovician IAL Barrel Spring Formation Obs, Barrel Spring Formation undifferentiated. Mapped with Johnson Spring Formation on > Badger Flat and to northwest Obsu, upper member; reddish-weathering shale, mudstone, and siltstone Obsl, lower member; limestone, impure quartzite, and siltstone Middle Ordovician A ORDOVICIAN Badger Flat Limestone Limestone and calcarenite, blue-gray, silty, and yellowish siltstone; black chert abundant in lower part N Ay" Mazourka Group -P A_ Al Rose Formation Siltstone, shale, and mudstone; brown-weathering limestone subordinate. Mapped with Badger Flat Limestone east of Bee Springs y Lower Ordovician N, mero aA he €tc Tamarack Canyon Dolomite Dolomite, monotonous gray-weathering, thin-bedded.; black chert nodules locally abundant Upper Cambrian A_" Lead Gulch Formation Thin-bedded interlayed sequence of limestone, silt- % stone, dolomite, chert, and shale a 6 & s ve CAMBRIAN ZA Bonanza King Dolomite Dolomite, laminated to thick-bedded; color banded in varied shades of gray to give diagnostic "zebra- striping" to most outcrops. Dashed line denotes locally mapped conspicuous black dolomite band Middle and Upper Cambrian fess ~ R S s l $ g ~§ Undivided sedimentary rocks \ 8 Include Poleta, Harkless, Saline Valley, and Mule § Spring Formations of Early Cambrian age, and J S Monola Formation of Middle Cambrian age Contact Dashed where approximately located m see uate has mee dan Fault Dashed where approximately located; dotted where concealed. Ball indicates downthrown side so _ om am Inclined Vertical Overturned Strike and dip of beds F- J8-12 Measured section Described in text m D 919 CO Fossil locality TRUE NORTH AGNE T C APPROXIMATE MEAN DECLINATION, 1966 36 E INTERIOR-GEOLOGICAL SURVEY, WASHINGTON, D. C.-1966-G65348 Geology mapped by D. C. Ross, F. K. Miller, Base from U.S. Geological Survey topographic and R. J. Pickering, 1959-1962 quadrangle: Independence, 1951 10,000-foot grid based on California coordinate system, zone 4 GEOLOGIC MAP OF MAZOURKA CANYON AREA, INDEPENDENCE QUADRANGLE, INYO COUNTY, CALIFORNIA SCALE 1:31 680 1 Ya 0 1 MILE 1 hs 0 1 KILOMETER CONTOUR INTERVAL 80 FEET - DATUM IS MEAN SEA LEVEL