Paleozoic Formations • 

Ill 

the Wind River Basin 

Wyoming 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 495-B 

Prepared in cooperation with the Geological 

Surve_y of Wyoming and the Department of 

Geology of the University of Wyoming as part 

of a program of the Department of the 

Interior for development of the Missouri 

River basin 

Paleozoic Formations • In 

the Wind River Basin 

Wyoming 

By W. R. KEEFER and]. A. VAN LIEU 

GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 495-B 

Prepared in cooperation with the Geological 

Survey of Wyoming and the Department of 

Geology of the University of Wyoming as part 

of a program of the Department of the 

Interior for development of the Missouri 

River basin 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1966 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

For sale by the Superintendent of Documents, Government Printing Office Washington, D.C., 20402 
CONTENTS 

Page. 

Abstract __________________________________________ _ B1 Pennsylvanian rocks-Continued 

Introduction ______________________________________ _ 2 Tensleep Sandstone _____________ - - - _- ----- - - - - - -

General geographic and geologic setting _______________ _ 2 Permian rocks ______________ - ___ -_------------------

General stratigraphic features _______________________ _ 6 l'romenclature _________________________________ _ 

Cambrian rocks ___________________________________ _ 7 Park City Formation ___________________________ _ 

Generalfeatures------------------------~------- 7 Permian and Triassic rocks, Goose Egg Formation------

Flathead Sandstone ____________________________ _ 14 Paleozoic structure __________________ ----------------

Gros Ventre Formation _________________________ _ 15 Economic geology _________________ - _ - - - - - - - - - - - - - - - -

Galla tin Limestone ____________________________ _ 19 Oil and gas ___________________ - - - - _ - - - - - - - - - - - -

Ordovician rocks, Bighorn Dolomite _________________ _ 21 Phosphate rock _________________ - - - _ - - - - - - - - - - - -

Devonian rocks, Darby Formation ___________________ _ 26 Other commodities ______________ --- _ - - - - - - - - - - - -

Mississippian rocks, Madison Limestone ______________ _ 29 References cited __________________ ------------------

Pennsylvanian rocks _______________________________ _ 35 Index ____________________________________________ _ 

Amsden Formation ____________________________ _ 35 

ILLUSTRATIONS 

[Plates are in pocket] 

PLATE 1. Map showing major outcrops and locations of measured sections of Paleozoic rocks in central 

FIGURE 

Wyoming. 

2-5. Sections of Paleozoic rocks along Wind River Basin: 

6. 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20. 

21. 

22. 

23. 

2. West side. 

3. l'rorth side. 

4. South side. 

5. East side. 

Electric and sample logs of Pan American Petroleum Corp. Shoshone-Arapahoe Tribal 9 at 

Winkleman Dome. 

Page 

Index map of Wyoming_________________________________________________________ B3 

Map showing major physiographic and structural features in central Wyoming________ 4 

Photograph of exposures of upper Paleozoic formations in Dinwoody Canyon__________ 5 

Aerial view looking north into Wind River Canyon_________________________________ 6 

Schematic diagram showing facies relations in Cambrian rocks from northern Utah to 

South Dakota_______________________________________________________________ 11 

Thickness map of Cambrian rocks in central Wyoming______________________________ 12 

Photograph showing Cambrian rocks along north side of Warm Spring Creek__________ 13 

Photograph showing Flathead Sandstone unconformably overlying Precambrian rocks 

in Wind River Canyon_______________________________________________________ 15 

Photograph of Cambrian, Ordovician, Mississippian, and Pennsylvanian strata in Wind 

RiverCanyon________________________________________________________________ 17 

Photograph of weathered surface of Bighorn Dolomite______________________________ 22 

Thickness map of Bighorn Dolomite in central Wyoming ______________________ -- __ -- 24 

Thickness map of Darby Formation in central Wyoming____________________________ 28 

Chart showing nomenclature of Carboniferous strata, east flank of Wind River Range__ 31 

Thickness map of Madison Limestone in central Wyoming__________________________ 32 

Map showing general distribution of formations underlying Madison Limestone________ 34 

Section of lower part of Amsden Formation at Cherry Creek ________________ ---- __ -- 36 

Thickness map of Tensleep and Amsden Formations in central Wyoming_ _ _ _ _ _ _ _ _ _ _ _ _ 38 

Diagram showing approximate intervals of time represented by Mississippian and 

Pennsylvanian formations ________________________________________________ -_ _ _ _ 39 

Photograph of cliff of Tensleep Sandstone in Sinks Canyon__________________________ 41 

Map showing distribution of major facies in Permian rocks _____________________ -____ 44 

Photograph of exposures of Goose Egg Formation at Alcova Dam____________________ 45 

Thickness map of Park City Formation and equivalents in central Wyoming_______ _ _ _ 46 

Photograph of prominent dip slopes of Park City Formation along east flank of Wind 

River Range________________________________________________________________ 47 

lll 

Page 

B40 

43 

43 

44 

49 

50 

50 

50 

51 

51 

51 

57 
IV CONTENTS 

TABLES 

Page 

TABLE 1. Locations of measured sections and the sources of data used in compilation of this report__ B8 

2-8. Fossils from: 

2. Cambrian formations____________________________________________________ 16 

3. Bighorn I>olomite_______________________________________________________ 25 

4. I>arby Formation_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 29 

5. Madison Limestone______________________________________________________ 33 

6. Amsden Formation______________________________________________________ 39 

7. Tensleep Sandstone______________________________________________________ 42 

8. Park City and Goose Egg Formations______________________________________ 48 
GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

PALEOZOIC FORMATIONS IN THE WIND RIVER BASIN, WYOMING 

By W. R. KEEFER and J. A. VAN LIEu 

ABSTRACT 

The Wind River Basin, occupying an area of 8,500 square 

miles in central Wyoming, is an extensive structural depression 

bounded on the south by the Granite Mountains, on the west by 

the Wind River Range, on the north by the Washakie Range and 

Owl Creek and Bighorn Mountains, and on the east by the Casper 

arch. These features were formed during Laramide deformation in Late Cretaceous and early Tertiary times. Paleozoic 

rocks underlie the basin and crop out along all the mountain 

flanks except the east. 

During Paleozoic time central Wyoming was part of the 

interior stable shelf region that lay along the east side of the 

Cordilleran geosyncline. Rocks representing all the Paleozoic 

systems, except possibly the Silurian, were deposited across 

the present site of the Wind River Basin during repeated transgressions and regressions of epicontinental seas. Because 

greatest sedimentary accumulation was toward the west, the 

Paleozoic section is thicker and more complete in the western 

part of the basin than in the eastern part. Marked changes 

in the thickness and lithology of nearly all form-ations take 

place from west to east, and some units disappear eastward owing to truncation or nondeposition. Although most 

of the strata were deposited under normal marine conditions, 

the pattern of .sedimentation was often influenced locally 1by 

slight but significant fluctuations in the base level of deposition caused by changes in sea level or by tectonic movements. 

Paleozoic formations in the 'Vind River Basin include the 

Flathead 'Sandstone, the Gros Ventre Formation,· and the Gallatin Limestone of Cambrian age; the Bighorn Dolomite of 

Ordovician age; the Darby Formation of Devonian and earliest 

Mississippian age ; the Madison Limestone of Missis·sippian 

age; the Amsden Formation and the Tensleep Sandstone of 

Pennsylvanian age; the Park Oity Formation and its equivalents of Permian age; and the Goose Egg Formation of Permian 

and Triassic age. Subdivision into formations and members 

of formations is based primarily on the classification and 

nomenclature that have been established for the sequence in 

the northern part of the Wind River Range. 

The Cambrian rocks are a well-defined transgressive sequen~e containing .a basal quartzitic sandstone unit (Flathead), 

a middle predonunantly shale unit ( Gros Ventre), and an 

upper limestone unit (Gallatin). Thicknesses decrease from 

1,200 feet in the northwestern part of the Wind River Basin 

to 50 feet at the southeastern corner. The sedimentary pattern is one of continuous transgression, beginning in Middle 

Cambrian time and reaching a maximum in Late Cambrian 

time, but the strata ·show that the transgression was interrupted many times 'bY minor retreats of the sea. 

The Bighorn Dolomite is divided into three members : the 

Lander Sandstone Member which occurs locally at the base an 

unnamed massive cliff-forming dolomite in the middle and' the 

Leigh Dolomite Member at the top. The formation '300 feet 

thick. in the northwestern part of the basin, thins t~ a wedge 

edge m the central part. Most of the Bighorn is considered to 

be Late Ordovician in age, but the Lander Sandstone Member 

may be Middle Ordovician. 

Silurian rocks have not been recognized in central Wyoming. 

If ever deposited in the region, they were removed by erosion 

before succeeding strata were laid down. 

The Darby Formation of Devonian and earliest Mississippian 

age has the most limited distribution of any of the Paleozoic 

units in the area, being confined to the western third of the 

basin. The sequence, which has a maximum thickness of 200 

feet, consists chiefly of dolomite in the lower part and of interbedded siltstone, shale, sandstone, and carbonate rocks in the 

upper. Locally at the top is a dark shale which is part of a 

widespread unit of latest Devonian and earliest Mississippian 

age that rests uncomformably on older Devonian rocks. 

Mississippian strata are 700 feet thick in the western part of 

the Wind River Basin, but they thin to 175 feet in the southeastern part. These rocks, predominantly resistant massive to 

thin-bedded crystalline limestone, are all assigned to the Madison Limestone. Brecciated and cavernous zones and intraformational unconformities are present, particularly in the 

upper part. The formation rests on the Dal"by Formation with 

apparent conformity toward the west, but eastward it truncates 

successively older formations and rests on the Flathead Sandstone in the southeast corner of the basin. The bulk of the 

Madison is Early Mississippian, ·but in the northern and central 

Wind River Range and adjacent Washakie Range it includes 

about 100 feet of beds that are Late Mississippian. 

The Amsden Formation is divided into a lower sandstone unit, 

called the Darwin Sandstone Member, and an upper unnamed 

unit of interbedded dolomite, shale, sandstone, and limestone. 

Thicknesses range from 355 feet in the northwestern part of the 

Wind River Basin to zero at the southeast corner. The formation is largely Early to Middle Pennsylvanian, but the Darwin 

Sandstone Member and immediately overlying beds are Late 

Mississippian. The Tensleep Sandstone, a uniformly. massive 

to crossbedded cliff-forming sandstone, containing a few thin 

beds of chert and limestone, is one of the most conspicuous 

Paleozoic units. 'Thickness ranges from 200 feet to more than 

600 feet. Most of the formation is Middle Pennsylvanian. At 

the southeast corner of the basin all Pennsylvanian rocks (mostly 

Upper Pennsylvanian), as well as some Lower Permian rocks, 

are included in the Casper Formation. 

Permian rocks are interbedded chert, limestone, dolomite, siltstone, sandstone, and phosphorite in the western two-thirds of 

the Wind River Basin, and red beds and gypsum, with thin beds 

of limestone, in the eastern third. The chert and carbonate 

facies, 150-350 feet thick, is referred to the Park City Formation 

and equivalents, and the red-bed facies, 355-380 feet thick, to the 

Goose Egg Formation. The Park City is largely early Late 

Permian, although the basal few feet, in some places separated 

from the overlying beds by an unconformity, is Early Permian. 

The lower 270-300 feet of the Goose Egg is equivalent to the 

Park City, but the remainder intertongues with the Dinwoody 

B1 
B2 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMIN-G 

Formation of Early Triassic age. Uppermost Permian rocks 

hav~ not been recognized in the basin area. 

T'he Wind River Basin was remarkably stable throughout the 

Paleozoic Era. Although considerable time elapsed between 

deposition of successive formations, there are no recognizable 

angular discordances within the entire sequence of Paleozoic 

rocks. Tectonic movements were limited to broad warping along 

trends which show little direct relation to structural trends 

developed during Laramide deformation. One exception is along 

the southeast margin of the basin where an area coinciding 

roughly with the present-day Laramie Mountains and parts of 

the Granite Mountains was positive intermittently during much 

of Paleozoic time. 

Paleozoic rocks, principally the Park City Formation and 

Tensleep Sandstone, are among the most important oil and gas 

reservoirs in the Wind River Basin. Much of the production 

has been from anticlinal traps along the basin margins, but 

conditions favoring stratigraphic entrapment also exist. The 

Park City contains extensive, though undeveloped, deposits of 

low-grade phosphate, especially in the western and northwestern 

parts of the basin. Raw materials for construction use are 

widespread. Pisolitic iron-bearing red shale occurs in the 

Amsden Formation, and small deposits of radioactive materials 

have been reported from Cambrian, Pennsylvanian, and Permian 

rocks at a few localities. 

INTRODUCTION 

Rocks of Paleozoic age underlie most of central 

Wyoming. Complete sequences are especially well 

exposed along the margins of the Wind River Basin 

and in the adjacent mountain ranges. Owing to both 

academic and economic interest, these rocks have been 

studied extensively since the earliest territorial surveya 

in the 1870's. As a result, many basic data on the distribution, thickness, lithology, paleontology, and depositional history of the various Paleozoic formations have 

been accumulated. These data, many of which were 

obtained by the lT.S. Geological Survey during a program of detailed geologic mapping and stratigraphic 

studies in the Wind River Basin, begun in the early 

1940's, are summarized in this report. 

Many individuals have thus contributed valuable information and ideas to this study; specific contributions 

will be cited below. Two of the early investigators, 

however, merit special recognition for their fundamental work on the classification and nomenclature of Paleozoic strata in the Wind River Basin and ajacent areas. 

Darton ( 1906 a, b) mapped the distribution of the 

Paleozoic rocks in the Owl Creek and Bighorn Mountains along the north and northeast margins of the 

basin and formally named and defined many of the 

individual formations. Blackwelder, during geological 

investigations in central and northwestern Wyoming 

from 1910 to 1913, traced many of the Paleozoic units 

through the Teton and Gros Ventre Ranges into the 

northern Wind River Range along the west edge of the 

1Vind River Basin. He (1918) modified some of Darton's earlier classifications and also named and defined 

several new formations and members of formations, 

particularly in the lower part of the sequence. The 

work by Darton and Blackwelder, though since modified, has formed the basis for all subsequent studies of 

the Paleozoic rocks in central Wyoming. 

Thomas (1948, 1952, 1957) presented excellent summaries of the stratigraphy and depositional history of 

the Paleozoic rocks in central Wyoming and adjacent 

regions. 

GENERAL GEOGRAPHIC AND GEOLOGIC SETTING 

The Wind River Basin includes about 8,500 square 

miles in central Wyoming, occupying most of Fremont 

County and the western part of Natrona County (fig. 

1). It is an extensive structural depression bounded 

on the south by the Granite Mountains, on the west by 

the Wind River Range, on the north by the Washakie 

Range and Owl Creek and Bighorn Mountains, and on 

the east by the Casper arch. (See fig. 2.) As thus 

defined, the outline of the structural basin is roughly 

that of a parallelogram, with a maximum length of 

about 180 miles from northwest to southeast and a maximum width of about 75 miles north to south. The 

structurally deepest parts are close to the Owl Creek 

Mountains and the Oasper arch, which lie along the 

r.Lorth and east margins, respectively. The basin and 

adjacent mountains were formed during Laramide deformation in Late Cretaceous and early Tertiary times. 

Most of the Wind River Basin is also a conspicuous 

topographic depression which has the same western 

and northern limits as the structural basin, but it is 

restricted on the south by the Beaver Divide, a 1,000-

foot erosional escarpment of Tertiary rocks, and on 

the east by a series of broad low ridges, sometimes 

called the Hiland Divide, extending north from the 

Rattlesnake Hills to the south end of the Bighorn 

Mountains. The Hiland Divide separates the Wind 

River drainage system from that of the Powder and 

North Platte Rivers to the east; the Beaver Divide 

separates the Wind River drainage system from that 

of the Sweetwater River to the south. 

The floor of the Wind River Basin, underlain by 

flat-lying lower Eocene rocks, is a region of low relief with only a few scattered buttes and mesas rising 

to as much as 500 feet above the general landscape. In 

the nortlnvestern part of the basin, the altitude of the 

floor is 7,000 feet above sea level, whereas farther to the 

east and southeast in the central part it is 5,000-5,500 

feet. 'Vith few exceptions, Paleozoic rocks do not crop 

out within the basin proper, but they have been penetrated in many places near the margins by wells drilled 

for oil and gas. 
PALEOZOIC FORMATIONS B3 

44 

Kemmerer 1 

I 

Rawlins II I \ 

!\

AL ANYI I 

0 

I 1 -l 0 I 

0 

A T E R I 0 

r--_j c I 

\\ ~ -L--~ 

li I LARAMIE·. ~-L'al ramie Cheyenne 

I ® ___ L_ 

I ---, I 

I 

0 50 100 MILES 

FIGURE 1.-.Jndex map of Wyoming showing location of Wind River Basin (stippled). 

The Granite Mountains are formed from a large anticlinal uplift that extends eastward from the south end 

of the Wind River Range for about 75 miles. The 

steep flank is to the south and southwest; the gentle 

north flank coincides with the south margin of the 

Wind River. The range was folded to mountainous 

proportions and deeply eroded during Laramide deformation, but later was almost completely buried by middle and upper Tertiary sediments. At present, the 

range is visible only as a series of prominent granite 

knobs projecting as much as 1,000 feet above a nearly 

level plain of flat-lying Miocene and Pliocene rocks, 

6,500-7,000 feet above sea level, upon which the Sweetwater River drainage is established. Paleozoic rocks 

crop out in some places along the flanks of subsidiary 

folds, such as the Rattlesnake Hills and Conant Creek 

anticline, that project northwestward into the Wind 

River Basin from the main mass of the range (pl. 1). 

The Wind River Range, culminating in 13,785-foot 

Gannett Peak, is the largest mountain uplift in Wyoming. The range trends northwest through the westcentral part of the State for about 100 miles and has a 

maximum width of a;bout 50 miles. Its west flank, 

bordering on the Green River Basin, is steep to overturned and broken by eastward-dipping reverse faults 

along which 35,000 feet or more of structural displacement has taken place (Berg, 1961). In contra;st, the 

east flank, with which we are concerned in the present 

study, is characterized by moderately gentle dip slopes 

on Paleozoic rocks which descend uniformly eastward 

into the Wind River Basin at dips of 10°-20°. The 

structural continuity of the east flank is interrupted in 

a few places by high-angle normal and reverse faults, 

with displacements commonly less than 1,000 feet, and 

by sharp monoclinal folds. Precambrian crystalline 

rocks, chiefly massive granite and granite gneiss, form 
B4 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

the core of the range, and Paleozoic rocks are well exposed in a nearly linear outcrop belt along the entire 

east flank (pl. 1). Complete sections of the Paleozoic 

rocks may be obse.rved in many steep-walled canyons 

which have been cut transverse to the strike of the stJ.'Iata 

by eastward-flowing tributaries of the Wind River. 

(For example, see fig. 3.) 

The Washakie Range, at the northwest corner of the 

Wind River Basin, is a series of faulted folds, in echelon, which extends northwest from Black Mountain 

(81;2 T. 7 N., R. 4 W., pl. 1) for about 70 miles (Love, 

1939, p. 5). This extensive uplift was completely 

buried by Eocene and Oligocene pyroclastic rocks of the 

Absaroka Range; it has now been partly exhumed. 

The south flank of the Washakie Range, generally 

steep and broken by northward-dipping reverse faults, 

is visible in several areas, and the Precambrian rocks 

exposed in some of the larger folds may represent part 

of its central core (Keefer, 1957, p. 205); the north 

flank is still buried. Altitudes of the exposed parts are 

as much as 10,000 feet above sea level. Discontinuous 

outcrops of Paleozoic rocks occur around the margins 

of many individual anticlines. 

The Owl Creek Mountains rise abruptly along the 

north edge of the Wind River Basin. This large anticlinal uplift, separating the Wind River Basin from 

the Bighorn Basin to the north, extends nearly eastwest across central Wyoming from the southeast edge 

of the Absaroka Range to the southwest end of the 

Bighorn Mountains, a distance of about 80 miles.1 

Rocks on the south flank of the range are steep to overturned, and have overriden the north margin of the 

Wind River Basin along an extensive system of reverse 

faults (Keefer, 1965, pl. 4). Strata on the north side of 

the range dip gently northward into the Bighorn Basin. 

Although the range as a whole is elongated nearly eastwest, individual segments in the west half trend 

obliquely northwestward. Altitudes range from 4,800 

1 That part of the range lying east of Wind River Canyon was called 

the Bridger Range by many previous workers, but in recent years it 

has been a more common practice to refer to the entire range as the 

Owl Creek Mountains. 

0 10 20 30 40 50 MILES 

FIGURE 2.-l\Iajor physiographic and structural features in central Wyoming. 

structural basin. 

Dashed line indicates approximate outline of Wind River 
0 "" 01 

I 

0< 

.... 

0 

0 

I 

Ol 

r 

"" 

FIGURE 3.-Exposures on north wall of Din woody Canyon, northern Wind River Ra nge. lied, Chugwater and Dlnwoody Formations; Pp, Park City Formation and equivalents; PI, 

Tensleep Sa ndstone; IPa, Amsden Forma tion; Mm. Madison Limestone. 

t;;j 

~ 0 

~ ...... 

0 

6 

~ 

~ 

~ 0 

~ 

to 

en 
B6 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

to 6,000 feet above sea level along the south edge to 7,000 

to 9,500 feet along the crest. Complete sequences of 

Paleozoic rocks crop out in many places; the best and 

most spectacular exposures are in Wind River Canyon 

which cuts across the central part of the range (fig. 4). 

The southwest-plunging end o"f the Bighorn Mountains forms the northeast margin of the Wind River 

Basin. This part of the range has an extensive core 

of Precambrian crystalline rocks flanked on the south 

by Paleozoic strata that dip south about 15° (Tourtelot, 

1953). These Paleozoic rocks have likewise been thrust 

south over the deep part of the Wind River Basin. The 

Bighorn Mountains are separated structurally from the 

Owl Creek Mountains to the west by a broad shallow 

synclinal area underlain for the most part by flat-lying 

Eocene rocks. 

The Casper arch is a major, but not deeply eroded, 

structural upward whose steep to overturned and 

faulted west flank coincides with the east margin of 

the \Vind River structural basin. The arch, which is 

underlain chiefly by Upper Cretaceous and Paleocene 

rocks, is characterized by low hills and ridges which 

slope gently eastward into the Powder River Basin. 

Altitudes range generally from 5,500 to 6,000 feet above 

sea level. No Paleozoic rocks crop out along the Casper 

arch, but all or part of the sequence has been penetrated 

hy drill holes at many localities. Outcrops are present 

to the south, however, along the north edge of Casper 

Mountain at the northwest end of the Laramie Mountains (fig. 2). A complete sequence of Paleozoic strata 

is also exposed near Alcova Reservoir, at the extreme 

southeast end of the Wind River Basin. 

GENERAL STRATIGRAPHIC FEATURES 

During Paleozoic time central Wyoming was part of 

the interior stable shelf region that lay along the east 

side of the main Cordilleran geosyncline. Rocks representing parts of all the Paleozoic systems, except 

possibly the Silurian, were deposited across the present 

site of the ·wind River Basin during numerous transgressions and regressions of epicontinental seas. Because the greatest sedimentary accumulation was toward the west, in the geosynclinal area of southeastern 

Idaho, the Paleozoic sequence is thicker and more comFIGURE 4.-Aerial view looking north into Wind River Canyon, central Owl Creek Mountains. Boysen Dam and north end of Boysen 

Reservoir are at bottom of photograph. PPu , Park City, Tensleep, and Amsden Formations; MOu, Madison Limestone und Bighorn 

Dolomite; £u, Cambrian rocks, undivided ; pCr, Precambrian igneous and metamorphic rocks; f-1, . Boysen normal fault. Faulted complex of Paleozoic und Mesozoic rock~. overlapped by 'l'ertiary rocks, occupies lower hulf of view. Photograph courtesy of P . T. Jenkins 

and L. P. House. 
PALEOZOIC FORMATIONS B7 

plete in the western part of the Wind River Basin than 

in the eastern part. Marked changes in the thickness 

and lithology of nearly all formations take place from 

west to east across the basin, and some units elisa ppear 

easbvard owing to truncation or nondeposition. 

The general lithologies, thicknesses, and stratigraphic 

relations of Paleozoic formations around the margins 

of the Wind River Basin and along the flanks of the 

adjacent mountain ranges are shown graphically on four 

correlation charts, plates 2-5. Individual measured 

surface sections or drilled subsurface sections were 

selected at 26 key localities, the distance between adjacent sections ranging from 6 to 28 miles (pl. 1). Localities and sources of data are listed in table 1; significant 

fossil collections are given in tables 2-8. 

The stratigraphy is discussed according to the classification and nomenclature of strata in the northwestern 

part of the basin, where the Paleozoic record is most 

nearly complete. The rocks there are classified as 

follows: 

Permian: 

Park City I!'ormation and equivalents 

Pennsylvanian: 

Tensleep Sandstone 

Amsden Formation 

Mississippian : 

Madison Limestone 

Devonian and lowermost Mississippian : 

Darby Formation 

Ordovician : 

Bighorn Dolomite 

Cambrian: 

Galla tin Limestone 

Gros Ventre Formation 

Flathead Sandstone 

CAMBRIAN ROCKS 

GENERAL FEATURES 

A well-defined transgressive marine sequence, including a basal sandstone unit, a middle shale unit, and an 

upper limestone unit, was deposited across most of central Wyoming during an eastward advance of the epicontinental sea in Middle and Late Cambrian time (fig. 

5). The major trend of transgression was interrupted 

repeatedly by minor retreats of the sea. At times certain -areas emerged and were eroded, while adjacent 

areas were still submerged and receiving sediments; 

there is no evidence, however, that the sea withdrew 

completely from the region between the time that the 

initial sediments were laid down in Middle Cambrian 

time and the close of the period. With each new surge 

the sea encroached farther eastward; by Late Cambrian 

time all central Wyoming was inundated, and the sea 

spread as far ·as the Black Hills region in northeastern 

Wyoming and western South Dakota (Thomas, 1957, 

p.4). 

The Cambrian sequence varies greatly in thickness 

and lithology from one place to another. The tripartite 

division of sandstone, shale, and limestone is especially 

distinct in the mountains along the west side of the Wind 

River Basin; but toward the east the rocks become progressively more clastic, and many units lose their distinctiveness owing to changes in facies. Formation 

boundaries cross time lines and become progressively 

younger from west to east across the basin area. Thickness of Cambrian rocks decreases from a maximum of 

about 1,200 feet along the west edge of the basin to only 

50 feet in the eastern most part (fig. 6) . The decrease is 

due partly to nondeposition and partly to the pronounced erosional unconformity at the top of the 

sequence. 

In the Owl Creek and Bighorn Mountains, Darton 

(1906a, p. 14-15; 1906b, p. 23-'26) referred all Cambrian 

strata to the Deadwood Formation, a name he had given 

earlier (Darton, 1901, p. 505) to Cambrian rocks in the 

Black Hills region. In the northwestern Wind River 

Range, Eliot Blackwelder (U.S. Geol. Survey, 1918, 

unpub. field notes), distinguished three formations corresponding to the three major lithologic subdivisions 

and employed terms then in current use farther westFlathead Sandstone, Gros Ventre Formation, and Gallatin Limestone (fig. 7). Blackwelder's classification has 

been used subsequently throughout much of the 'Vind 

River Basin, and is used in this report. 

Because of the variations in thickness and lithology, 

however, alternate systems of classification and nomenclature have been proposed for the Cambrian sequence in 

some areas of the basin. In the central and eastern 

Owl Creek Mountains, for example, Miller ( 1936, p. 

124) applied the name Depass Formation to the lower 

part of the Cambrian sequence, and Deiss ( 1938, p. 

1104) applied the na1ne Boysen Formation to the upper 

part. In the southwestern part of the Wind River 

Basin, Shaw (1957) referred the basal Cambrian unit to 

the Flathead Sandstone, but elevated both the Gros 

Ventre and Gallatin to group status and separated each 

group into several individual formations. Shaw ( 1954) 

also introduced the name Buck Spring Formation for 

all Cambrian rocks overlying the Flathead Sandstone 

in the south-central part of the basin. Additional disetlssions of the problems in classification and nomenclature are included below in the descriptions of formations. 
Section 

Warm Spring 

Creek 

Din woody 

Canyon 

Bull Lake 

Canyon 

Trout Creek 

Squaw Creek 

Sinks Canyon 

Beaver Creek 

Sweetwater 

Canyon 

Windy Gap 

Circle Ridge 

Flathead 

I Sandstone 

TABLE 1.-Locations of measured sections and the sources of data used 1·n compilat1:on of this report 

[An asterisk (*) indicates source is unpublished field notes, U.S Geol. Survey; blank space indicates formation absent] 

Gros Ventre Gallatin 

I 

Bighorn 

I 

Darby Madison Amsden 

Formation Limestone Dolomite Formation Limestone Formation 

Sees. 30 and 31, T. 42 N., R. 108 W. Sec. 1, T. 41 N., R. 108 W. Sec. 31, T. 42 N., Sees. 14 and 15, 

R. 107 w. T. 41 N., R. 107 W. 

Tensleep 

Sandstone 

Sees. 9 and 10, 

T. 41 N., R. 107 W. 

Miller (1936, p. 131, 132) Keefer (1957, p. 166-168) Weart (1948) Keefer (1957, p. 170-172) 

Park City Formation 

and equivalents 

Sees. 11 and 14, 

T. 41 N., R. 107 W. 

Weart (1948) 

Northeastern part, T. 4 N., R. 6 W. Sec. 11, Sec. 12, T. 4 N., R. 6 W. Northeastern part, Sec. 1, Sec. 6, T. 4 N., R. 5 W. 

T. 4 N., R. 6 W. T. 4 N., R. 6 W. T. 4 N., R. 6 W. 

J. F. Murphy* I J. F. Murphy' J. F. Murphy* J. F. Mrnphy" I J. F. Murphy* J. F. Murphy* J. F. Murphy* Eliot Blackwelder• Sheldon 

Eliot Blackwelder* Eliot Blackwelder• Eliot Blackwelder• (1957' pl. 13) 

Sec. 9, T. 2 N., R. 4 W. Sec. 3, Sec. 2, T. 2 N, R. 4 W. Sec. 35, 

T.2N.,R.4W. T.3N.,R.4W. 

Murphy and others (1956); Murphy and Richmond (1965) 

Sec. 1, T. 2 S., R. 3 W. Sec. 5, T. 2 S., R. 2 W. Sees. 4 and 5, T. 2 S., R. 2 W; sees 32 and 33, T. 1 S., R. 2 W. 

I 

Sec. 22, 

T. 1 S., R. 2 W 

(Not measured) 

Planetable traverse by W. R. Keefer Love •nd otho" I J. F. Murphy* Love and others (1947, p. 36, 37) 

and R. L. Koogle (1947, p. 37) 

Sec. 4, T. 33 N., R. 101 W. Sec. 4, Sec. 5, Along North Fork Sec. 18, 

T. 33 N., R. 101 W. T. 33 N., R. 101 W. Popo Agie River T. 33 N., R. 100 W. 

(Not measured) 

Burton (1952) Strickland (1957, Biggs (1951) Burton (1952) King (1947, p. 3o-40) 

p. 21); Burton (1952) 

Sec. 25, Sec. 18, T. 32 N., R. 100 W. Sec. 18, Sec. 20, Sec. 25, 

T. 32N., R.101 W. T. 32 N., R. 100 W. T. 32 N., R. 100 W. T. 32 N., R. 100 W. 

(Not measured) 

Hembree (1949) Strickland (1957, fig. 1) Bigg~ (1951) Hembree (1949) Condit (1924, p. 24) 

Sec. 24, T. 30 N., R. 100 W. I ""'· ... Sec. 6, Sees. 8 and 18, Sec. 9, Sees. 9 and 10, Sees. 11 and 12, 

T. 30N., R.100W. T. 29 N., R. 98 W. T. 30 N., R. 99 W. 'l.'. 30 N., R. 99 W. T.30N., R.99W. T. 30 N., R. 99 W. 

-- Gooldy (1947) Gooldy (1947) Lower part, Shaw 

(1955, p. 61) 

Gooldy (1947) Condit (1924, 

p. 28, 29) 

Sees. 27 and 28, T. 29 N., R. 97 W. 

I 

Sec. 34, T. 29 N., R. 97 W. Sec. 27, T. 29 N., R. 97 W. Sec. 26, 

T. 29 N., R. 97 W. 

DeLand (1954) Bell (1955) Bell (1955) 

Sec. 1, T. 42 N., Northeastern part, Sec. 29, T. 43 N., Sec. 36, T. 43 N., R. 106 W. Sec. 7, Sec. 19, Sec. 18, Sec. 13, 

R.106W. T. 43 N., R.106 W. R.106W. T. 42 N., R. 105 W. T. 43 N., R. 106 W. T. 42 N., R. 105 W. T. 43 N., R. 107 W. 

Love (1939, p. 15) W. R. Keefer* Love (1939, p. 16); 

W. R. Keefer* 

Love {1939, p. 18-25) Biggs (1951) Love (1939, p. 29) Keefer (1957, p. 174) 

(Not measured) 

Sees. 30 and 31, T. 8 N., R. 2 W.; sees. 4 and 5, T. 42 N., R. 101 W. I 

Sec. 13, T. 7 N., R. 3 W. 

ttl 

00 

0 

t?:l 

0 

~ 

0 

~ 

0 

~ 

~ 

~ 

z 

t:::t 

~ 1-1 

< t?:l 

~ 

txl 

~~ 

Q 

~ ~ 

~ 

~ 0 

0 

~ 
Milton (1942) 

Sheep Ridge 

Sec. 3, I Sec. 9, Sec. 3, Sees. 4 and 20, Sec. 2, Sec. 27, I Sees. 10 and 35, I Sees. 14 and 15, I Sec. 31, T. 6 N., R. 2 E. T. 7 N., R. 2 E. T. 7 N., R. 2 E. T. 7 N., R. 2 E. T. 7 N., R. 1 W. T. 7 N., R. 1 E. T. 7 N., R. 1 E. T. 7 N., R. 1 E. T. 7 N., R. 2 E. 

Phillips (1958) Flanagan (1955) Phillips (1958) Thomas (1948, Phillips (1958) p. 85) 

---------~~;----~ ~~- -Sees.; and 24, Sec. 24, -------- Sees. 24 and 25, I Sec. 25, T. 6 N., R. 3E. I Sec. 36, 

T. 7 N., R. 3 E. T. 7 N., R. 3 E. T. 6 N., R. 3 E. T. 6 N., R. 3 E. T. 6 N., R. 3 E. T. 6 N., R. 3 E. 

Blackrock Ridge l--------'--------'----------------l 

Powell (1957) Powell (1957) 

---------- Sec. 4; T. 5 N., R. 6 E. I Sec. 33, Sec. 32, I Sec. 30, I Sec. 19, Sec. 28, 

Wind River T. 7 N., R. 6 E. T. 7 N., R. 6 E. T. 7 N. R. 6 E. T. 7 N., R. 6 E. T. 42 N., R. 94 W. 

Canyon -----

Tourtelot and Thompson (1948) Tourtelot and Thompson (1948) Tourtelot (1953) 

Sec. 19, T. 40 N., R. 91 W. Sec. 35, Sec. 35, Producers Oil No. 1 Barcklay, Sees. 7 and 8, Eastern T. 41 N., R. 92 W. T. 41 N., R. 92 W. sec. 11, T. 40 N., R. 91 W. T. 40 N., R. 91 W. Owl Creek Mountains . H. A. Tourtelot* Lyon (1956) Lyon (1956) Petroleum Information, Inc., Denver, Tourtelot (1953) 

Colo. 

Badwater (Not measured) 

Sec. 6, Sec. 20, I Sec. 22, Sees. 16 and 21, T. 40 N., R. 90 W. T. 40 N., R. 89 W. T. 40 N., R. 89 W. T. 41 N., R. 89 W. 

H. A. Tourtelot* Tourtelot (1953) 

-------- Sec. 26, T. 39 N., R. 88 W. Sec. 3, T. 40 N., R.l Sec. 21, I Sees. 32 and 33. Sec. 4, 

86 W.; sec. 34, T. 41 T. 40 N., R. 86 W. T. 40 N., R. 86 W. T. 38 N., R. 87 W. Deadman Butte N., R. 86 W. 

H. A. Tourtelot* Woodward (1957, p. 259, 260) Tourtelot (1953) 

----------------------------------------------------------1-------------------------------------

Sec. 36, T. 33 N., R. Sec. 13, T. 32 N., R. 94 W. Sec. 23, T. 32 N., R. 94 W. 94 W.; sec. 31, T. 33 N., R.93W.;sec. 2, Conant Creek T. 32 N., R. 94 W. 

VanHouten and Weitz (1956); Shaw (1957, p. 12) V. L. White* 

Sinclair-Wyoming Oil Co. No.2, sec. 1, T. 33 N., R. 92 W. Muskrat (Not penetrated) (Not penetrated) 

E-log study by J. A. Van Lieu 

I 

East Sec. 26, T. 33 N., R. 89 W. Sees. 23 and 26, T. 33 N., R. 89 W. 

Canyon Creek (Not measured) (Not measured) 

Rattlesnake Hills 

VanHouten and Weitz (1956); VanHouten and Weitz (1956) 

J. L. Weitz* 

Sec. 24, T. 33 N., R. 88 W. Sec. 24, I Sec. 32, I Sec. 24, Sec. 4, T. 33 N., R. 88 w: T. 33 N., R. 87 W. T. 33 N., R. 88 W. T. 32 N., R. 87 W. 

Shaw (1957, p. 12); Bogrett (1951) Bogrett (1951) Thomas (1934, p. 1673, 1674) 

0 

~ 

~ ~ 

0 

6 

l;lj 

~ 

~ ~ 

0 

~ 

tt1 

<:0 
I 

Section 

Fish Creek 

---------

Alcova 

Bates Creek 

Notches 

North Casper 

Creek 

I Casper 

I 

Mountain 

TABLE 1.-Locations of measured sections and the sources of data used in compilation of this 1·eport-Continued 

Flathead Gros Ventre 

I 

Gallatin 

I 

Bighorn 

I 

Darby Madison 

I 

Amsden 

I 

Tensleep I p.,k City Fo=•tion Sandstone Formation Limestone Dolomite Formation Limestone Formation Sandstone and equivalents 

(Not penetrated) 

Atlantic Refining Co. No.1, sec. 9, T. 31 N., R. 84 W. 

E-log study by J.D. Love 

Northwestern Sec. 30, 

part, T. 29 N., Northwestern part, T. 29 N., R. 83 W. T. 30 N., R. 82 W. 

R.83W. 

Lee (1927, p. 52) Lee (1927, p. 52) Thomas (1934, 

p. 1677) 

Sec. 5, Sees. 5 and 6, T. 30 N., R. 79 W. Sec. 6, 

T. 30 N., R. 79 W. T. 30 N., R. 79 W. 

Harrison (1938) Harrison (1938) Jenkins (1950) 

(Not penetrated) Trigood Oil Co. Cheyenne Lease No. 10, sec. 3, T. 37 N., R. 85 W. 

E-log study by J. A. Van Lieu 

Pure Oil Co. No.1, sec. 36, T. 37 N., R. 82 W. Pure oil Co. No. 1, sec. 36, T. 37 N., R. 82 W. 

Sample and E-log study by J. A. Van Lieu Sample and E-log study by J. A. Van Lieu 

Sec. 9, Sec. 9, Northwestern part, T. 32 N., R. 80 W. Sec. 12, 

T. 32 N., R. 79 W. T. 32 N., R. 79 W. T. 32 N., R. 81 W. 

Sims (1948) Sims (1948) Lee (1927, p. 49) Burk and Thomas 

I (1956, p. 5-7) 

to 

._. 

0 

0 

t_:rj 

0 

~ 

0 

~ 

0 

"':! 

8 

~ 

~ 

z 

t::; 

l:C 

1-4 

<! 

t_:rj 

l:C 

td 

> m 

1-4 

~z 

·Q 

t_:rj 

z 

8 

l:C 

~ 

~ 0 

0 

~ 
(1) 

BEAR RIVER 

RANGE, UTAH 

St. Charles 

Limestone 

Nounan 

Limestone 

Bloomington 

Formation 

Blacksmith 

Limestone 

Ute 

Limestone 

Langston 

Limestone 

Brigham 

Quartzite 

Ordovician rocks 

(2) 

WIND RIVER 

MOUNTAINS 

(3) 

WIND RIVER 

CANYON 

Ordovician rocks 

PREDOMINANT FACIES 

[§I] . 

. 

Sandstone and conglomerate 

~ 

~ 

Shale, siltstone, and shaly sandstone 

CJ 

Limestone and dolomite 

FEET 

500~ 

50 MILES 

0 I 

APPROXIMATE SCALES 

(4) 

BLACK HILLS 

Deadwood 

Formation 

FIGURE 5.-Facies relations in Cambrian rocks from northern Utah to western South Dakota. Sources of data: (1) Stokes (1953), Deiss (1938), S.S. Oriel (oral commun., 1964) ; 

(2) Keefer (19<57); (3) Tourtelot and Thompson (1948); (4) Darton and Paige (1925). 

~ t<J 

0 

~ 

0 

1-4 

0 

1-.:j 

0 

~ 

0 

~ z 

UJ. 

to 

t-l 

t-l 
106° rJ.)oo 109° 108° 10r 44 o 

! ~~----' _, p A R K I - I T I I I 46 " ,.!'/"\._,-\, I I w 46 A s H A K I E I I 

-... ) ..... ·- 1.. N I~ 

; 45 3 , ~ 1 · "<P0 45 I 1 ~ c 109 ~1.os "1'67 106 105 1o4' 1ill !l2J. 101 100 -gog, 98 97 96 -95 9~ ~3 92 91 90 89 as s7 86 1 85 84 83 82 81 so 79 78 R 77 w r.:~ 

I ~ -I- - _...., \Po ~ ~•"- 144 I I I 

'/ - ~- 0 ~\ ~ Ll:i"""<J T't"-, s p R I N G s I i j ~ 1

1

, "' ~ 1'. . ~ ~...... • --~ T I I p... 1\ 43 ' IX-~- X - 43 I I J 0 H N s 0 N I 

(:]111 

_1. X ~ 0 "\ "'-.._ "'- /-~ " "~b lTper~ polil• - _ 1 _n _ , :g 

TIETOINJ: ~t---. 'Xr .........._~ 1:=-= _, :n -~, V 42 '1-...f---- \v 1 I< ' 1 ~ 1'-. v,..- ~h...'¥ . - 1 I , ~n:. u 1 41 ~ ~'-... iDDub is ---.14-- L ~ .:S. J. l I I .. .........- -....... I " ~ ov I I 

I --~~-~-"" ~ 6 -=* I I IY" ::::-.... - - ~- -, - --r-- t--- -- -- --r--. f--

1 _, -- \ . \ '\ be"" -' ..,. ~ ~ -if:..- . )[I- J ~ - i~Ul I 

--.. ----?-·f9b 1\0 

1'\ R '\ I V 5 --...... ... r- - ~ ' I 4

1_ K I'-. --*-b..-::" r- •- R•lln l ~p,'L\ 1\ ,....~\. \ ~6 5 4 3 2 R.1W. R.IE. 2 3 4 5 6j \ \ \ I .........-1-1" ~ I 

o, ITif ~ \" '\ ;r-;- -~ / 4 I 39 I;'" I L.--~--""" )< '\ r-- P'O< ~ 

3?-J<. ~ """ '1\ 1- I~ \ I\ (I ( -~ I r-- \ "'-...,1 --~ ~ ..-- l-- 1'"---, I [\ I \ \ ~ , r-- 1- 6l1,... 

I ...... \ \ \ i\ \ \ ,~ I ll37 \ I \ X 2 ]) I 1\ 37 I' ,,, 1\. • jJ I ' I ' I~ .., I\ . \ I\ I, 

~ \ 1 ~~ T .. v · } 36 1

, \ "~'\ 1\ (h t--r-- Soh .Cl 3_5 )__:':l...IJ ....... - '\_ r-r--b-,•N .A!Eivert<n 11 35 IJ 1 ' \. \ J43o 

I /~. / f\ X r-- k._ - - ~ 1 I\ N ' A T ~ 0 . .»- 4i)( J""'. 34 I - lL _\.. lli...~ ;1- (-- ' / I I \ \ I\ \ ) : .... ......_Pmedal~ / 'I--~ '-\L .r 'Vp, ~~~ L·l-·- 3

'V J i \ , { I'\ '-3pO JZ 

33 1 i 0 '~, ru l -_ra~ l:l:d - 33 / / i _l J 1 ) / _.,.- 20~P )~cjsper l~ 

r 32 ·I I ' J er,J l \'~ I -~ 1\ (~- ;- l V J 1 v ;v"V":v ~ 1 ' 

s l"u I B I L E h I )-J ~"' \ I ..,._..._~ ') l'- +-- + 17'>--lf r h.-JL1l? -"'- i I 30 " IEXPLANATION 

X 

Surface section 

• 

Subsurface section 

0 10 20 30 MILES 

__j 

I 

rI 

-t 

I:>< 

IZ 

~ ,~ 

~ rt· _L__j 42 ° 

F 1 R 1 E 1 M 1 o 1 ~<1'?:.~~ ~~cfo 1 J_ i 

1 1 1 

1 1 1 1 I I I I N I ' 

t---L> (L_ --?!-- I I I I I R I I B I I 0 I I 0 'U !26 I I ! I C I A 

+-~--+--- ----

R I 

I I Sl w IE R1~01 !100 99 El T IW 98 97 I 96 95 

A Tl25 E 

93 92 I 91 I 90 s9 1 88 1 87 1 86 1 8ls I 84 I 83 I s2 I 81 78 9A 79 

Dl 8.0 

I 1 l l l II I I u l I I 

FIGURE 6.--Thickness map of Cambrian rocks in central Wyoming. Interval is 100 feet; isopachs are restored across mountain arches where rocks have been eroded; isopachs are 

da.shed where control is inad.equate. 

tt1 

..... 

t>..J 

0 

l"J 

0 

~ 

0 

0 

~ 

0 

"":' 

8 

~ 

~ 

~ 

~ 

~ ~ 

t:l:l 

~ 

JZ! 

c 

~ 

~ 

~ 0 

~ 

~ 
0 "' '!' 

01 

... 

0 

0 

I 

i 

co 

FIGURE 7.- Cambrian rocks along Warm Spring Creek, northern Wind River Range. Ob, Bighorn Dolomite. Cg, Gallatin Limestone; Cgo, Open Door Limestone Member, Cgd, 

type section of the Du Noir Limestone Member. Gros Ventre Formation; Cgvp, Park Shale Member, Cgvd, Death Canyon Limestone Member, Cgvw, Wolsey Shale Member. 

Cf, Flathead Sandstone. Note grass covered siDpes of Gros Ventre Formation in right background and treeless dip slope of Flathead Sandstone In right middle ground. 

~ t.".l 

0 

~ H 

0 

6 

J:lj 

0 

~ z 

rp. 

l:l:l 

~ 

C;.j 
B14 GE•OLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

FLATHEAD SANDSTONE 

Definition 

The name Flathead Formation was originally proposed by Peale ( 1893, p. 20-22) for exposures in Flathead Pass, southwe;;tern Montana, and included a basal 

quartzite, the Flathead Quartzite, and an upper green 

shale sequence designated the "Flathead shales." In 

the Gros Ventre Range of northwestern 'Vyoming, 

Blackwelder ( 1918, p. 417) included the green shale 

in the lower part of his Gros Ventre Formation and restricted the Flathead to the basal quartzitic sandstone. 

The formation is now generally accepted in this restricted sense, and has been recognized over wide areas 

in western and central Wyoming. 

Lithology and Thickness 

Along the east flank of the Wind River Range the 

Flathead Sandstone has an average thickness of about 

200 feet, except at the southeast end where it thickens 

to nearly 350 feet (pl. 2, Sweetwater Canyon section). 

The formation is predominantly pink, reddish-brown, 

tan, and gray fine- to coarse-grained sandstone. It is 

quartzitic for the most part, and contains glauconite 

and hematite in many places. Many of the beds are 

thinly laminated with pink and reddish-brown layers 

alternating with tan and gray layers. Some crossbedding is present. The basal beds of the formation are 

commonly conglomeratic and arkosic, containing angular fragments of quartz, feldspar, and mica. Granite 

pebbles as much as 1 inch across are locally disseminated 

in the lowermost strata. The upper beds of the Flathead are generally softer and are shaly, and have numerous partings of green and gray-green ·micaceous 

shale. 

Topographically, the Flathead Sandstone usually 

forms a series of resistant blocky ledges which rise 

abruptly in steep slopes above the basal contact with the 

Precambrian crystalline rocks. Outcrops support heavy 

gro,vths of trees in most places, but locally prominent 

treeless dip slopes on top of the uppermost resistant 

sandstone bed (fig. 7) occur. The sandstone commonly 

breaks into large slabs which slide short distances down 

the slopes; small rock slides are numerous along steep 

dip slopes. 

Strata included in the Flathead Sandstone along the 

north and south margins of the Wind River Basin are 

similar lithologically to those in the Wind River Range. 

In the Washakie Range and western part of the Owl 

Creek Mounta:ins, thicknesses remain fairly constant at 

120- 160 feet, but they increase eastward to 255 feet in 

the Wind River Canyon and to nearly 400 feet in the 

eastern Ow I Creek Mountains (pl. 3, Bad water section). 

Along the south edge of the basin the Flathead ranges 

in thickness from 245 feet at the Conant Creek locality 

to more than 500 feet in the northern part of the Rattlesnake Hills (pl. 4) . In the latter area the basal conglomerate is as mu ch as 120 feet thick. The eastward 

thickening of the formation is at the expense of the overlying Gros Ventre Formation, with which it interfingers. 

At the southeast end of the 'Wind River Basin, and in 

adjacent areas along the west side of the Laramie Mountains, 45-90 feet of coarse-grained quartzitic sandstone 

(pl. 5) was assigned to the Flathead Sandstone by Shaw 

( 1954). These strata are overlain directly by clastic 

rocks forming the base of the Mississippian Madison 

Limestone, and Maughan ( 1963, p. C26) suggested the 

possibility that the sandstone now placed in the Flathead may represent a locally thick sandy facies of the 

basal part of the Madison Limestone. 

Contact With Precambrian Rocks 

The Flathead Sandstone unconformably overlies 

Precambrian igneous and metamorphic rocks. Tht' 

contact is generally concealed by forest cover or talus. 

In a few places, however, such as in Wind River Canyon, the contact is continuously exposed for several hundred yards (fig. 8). The eroded surface of the Precambr·ian rocks apparently had some topographic relief; 

this relief probably accounts for some of the local variations in thickness of the Flathead. 

"\Vhere the Flathead Sandstone directly overlies massive granite and granite gneiss, there is commonly a 

transitional zone of weathered arkose at its base. The 

weathered zone represents a regolith that was winnowed 

during the encroachment of the Cambrian sea. 

Contact With the Gros Ventre Formation 

The Flathead sandstone is overlain conformably 

by the Gros Ventre Formation; laterally the two 

formations interfinger. The formation boundary is 

usually placed at the top of the uppermost persistent 

quartzitic sandstone in the sequence, but in most places 

the change from quartzitic and, in part, shaly sandstone 

below to soft shale and shnJy sandstone above is gradational. The contact is also marked locally by a topographic change from cliffs below to concave slopes 

above. On electric logs there is an easily recognized 

shift from the low resistivity and self-potential curves 

of the Gros Ventre to the more expanded curves of the 

Flathead (pl. o). 

Age 

Fe\Y diagnostic fossils have been found in the Flathead Sandstone in the Wind River Basin (table 2); 

thus, the part of Cambrian time represented is not precisely known. From regional stratigraphic and paleontologic correlations, Miller ( 1936, p. 142) and Shaw 

(1957, p. 9) <.:onsidered the formation to be early Middle 
PALEOZOIC FORMATIONS B15 

FIGURE 8.- Flathead Sandstone (Cf) unconformably overlying Precambrian rocks (p{;r) along east side of Wind River Canyon, central Owl 

Creek Mountains. 

Cambrian in age. Owing to its transgressive origin, the 

sequence is somewhat younger in the eastern part of the 

b1tsin than in the western part (fig. 5). 

The Flathead Sandstone probably is lithologically 

continuous with the lower part of the Deadwood Formation of Late Cambrian and Early Ordovician age in 

the Black Hills and the Brigham Quartzite of late Precambrian and Early (?) and Middle Cambrian age in 

southeastern Idaho and northern Utah (fig. 5). 

Conditions of Deposition 

The Flathead is a classic example of transgressive 

sandstone, representing the initial deposit laid down 

during the eastward migration of the Cambrian seas 

into the interior stable shelf region (fig. 5). Debris 

eroded from the adjacent Precambrian terrane accumulated chiefly in a shore and near-shore environment. 

Periodic retreats and readvances of the sea caused intertonguing of the coarser sediments of the Flathead on the 

east with the finer· grained sediments of the Gros Ventre 

Formation on the west. 

GROS VENTRE FORMATION 

Definition 

The Gros Ventre Formation was named by Blackwelder (1918) from exposures on Doubletop Peak in 

the Gros Ventre Range, about 25 miles southwest of 

the Warm Spring Creek section (pl. 1). The sequence 

probably includes the lateral equivalents of the "Flathead shales" and the lower part of the Gallatin Formation of Peale ( 1893, p. 20-25) in southwestern Montana. 

At the type section, the Gros Ventre Formation can 

be divided into three distinctive lithologic units: a lower 

shale and shaly sandstone unit; a middle limestone unit 

called the Death Canyon Member by Miller ( 1936, p. 

119) and referred to in this report as the Death Canyon 

Limestone Member; and an upper shale and limestone 

unit. These units are readily distinguished in the western and northwestern parts of the Wind River Basin 

(fig. 7) but not in the central and eastern parts. 

In th western part of the Wind River Basin, Shaw 

(1957) raised the Gros Ventre to group rank and, following the terminology of Weed ( 1900) in central Montana, referred to the upper unit as the Park Shale and 

to the lower unit as the Wolsey Shale. He (Shaw, 1957, 

p. 9-10) retained the Death Canyon Limestone for the 

middle unit. Although Shaw's terminology is used in 

this report, it is modified to the extent that the Gros 

Ventre is retained as a formation and the three subdivisions are classed as members. Gros Ventre strata are 

generally poorly exposed and, as a result, are mapped as 

a single unit. 

Lithology and Thickness 

In the Warm Spring Creek section at the northwest 

end of the Wind River Range (pl. 2) the Gros Ventre 

Formation is 747 feet thick and contains the threefold 

division mentioned above. The shale units are commonly grass covered and good exposures are rare; in 

contrast the Death Canyon Limestone Member forms 

vertical cliffs and is one of the most conspicuous units 

in the Cambrian sequence (fig. 7). 

The Wolsey Shale Member is 107 feet thick along 

Warm Spring Creek and consists of greenish-gray, tan, 

and pink micaceous sandy shale and very fine grained 

shaly sandstone that is highly glauconitic in most places. 

The basal part contains some beds similar to those in the 
B16 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

upper part of the Flathead Sandstone, so that the contact in places is grada:tional. The Death Canyon Limestone Member, 219 feet thick, is charaterized by cliffforming gray thin-bedded crystalline limestone that is 

commonly mottled by inclusions of irregularly shaped 

tan granular limestone or dolomite masses a fraction of 

an inch to several inches across. The Park Shale Member consists of 421 feet of soft greenish-gray micaceous 

shale with varying amounts of thin-bedded gray limestone that increases in abundance toward the top. The 

limestone commonly contains beds of flat-pebble conglomerate, consisting of disk-shaped limestone fragments oriented mostly parallel to the bedding planes 

in a dense to granular limestone matrix. The flat pebbles are particularly conspicuous on weathered surfaces 

that transect the bedding planes. 

Stratigraphic section 

Collec- tion 

No. 

(pis. 

2-5) 

TABLE 2.- Fossils from Cambrian formations 

[Generic and specific names are quoted "ithout modification from sources shown] 

Species References 

---------------------------------·----------------------1-----------

Warm Spring Creek __ 

Dinwoody Canyon ___ _ 

Sweetwater Canyon __ _ 

Windy Gap ___ __ ____ _ 

Wind River Canyon __ 

Deadman Butte ____ _ _ 

Conant Creek ___ ____ _ 

Rattlesnake Hills ____ _ 

1 

2 

3 

4 

5 

6 

7 

1 

2 

3 

1 

2 

3 

4 

5 

6 

7 

8 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

1 

2 

1 

2 

3 

1 

2 

Lingulepis acuminatus ____________________ ___ _______________ _____ _ 

Cedarina cf. C. alberta, C. victoria, Bynumia sp. indet., M odocia? sp., 

Tricrepicephalus? sp., Semicircularia arcuata. 

Agnostus sp., Linnarssonella sp. cf. L. modesta, L. transversa, Obolus? 

sp. cf. 0 . zentus. 

Kingstonia sublettensis, Blountia globosa, B. dunoirensis, B. sp. cf. B. 

amage, Crepicephalus sp., Cedaria sp. aff. C. prolifica, Arapahoia levis, 

M aryvillia sp., Agnostus sp. aff. A. tumidosus. 

Elvinia roemeri, Burnetia'! sp., Eoorthis '! sp. cf. E. iddingsi ___________ _ 

Taenicephalus cordillerensis, W ilbernia sp., Billings ella coloradoensis, 

Billingsella? sp. aff. B. striata, Dicellomus sp., Lingulepis acuminata var. meeki, Acroteta microscopica var. tetonensis, lrvingella gibba. Briscoia schucherti, Synthrophia alata, Eoorthis sp. cf. E. iophon __ ___ __ _ Obolus sp ___ ______ ____ ______ ____ __ ___ _____ ______ __________ ___ __ _ 

Abnndant fragments of Late Cambrian trilobites ________ ________ ___ _ 

Eoorthis qf. E. remnicha __ -------------- ------------------------- - Glyphaspis ____ __________________ ___________ _____ _______________ _ Bolaspidella? _____ ____ _________ ___ _____ ____ ______ ________ __ __ ___ _ Bolaspis, Hyolithes __ ______ __________________ ____________________ _ 

Apachia convexa, Burnetia alta, Cliffia latagenae, Deadwoodia duris, 

Dellea saginata, llousia vacuna?, Iddingsia occidentalis, lrvingella aff. 

I. fiohri, Xenocheilos cf. X. spineum, Elvinia sp. (Elvinia zone). Taenicephalus cordillerensis ( Taenicephalus zone) __________ ______ __ _ _ ldahoia sp., Monocheil1ts'? sp., (Idahoia zone) _____ _________________ _ _ Ellipsocephaloides sp., (I dahoia zone) __ ______________ __________ ____ _ 

Cranidia B and C of DeLand and Shaw (Trempealeauan) ___________ _ 

Billingsella coloradoensis, Eo01·this cf. E. remnicha, Lingulepis acumi- natus, Acroteta microscopica var. tetonensis, Dicellomus cf. D. nanus, 

Hyolithes? sp., Prozacomps·us sp., I dahoia sp., Prosaukia sp., Chariocephalus? sp., M aladia sp. (Ptychaspis-Prosaukia zone). Scohthus ___ ________ ______________ ____ ____________________ ___ __ _ 

Scolithus _________ ________________ __ ___ _________________ _______ _ Lingulepis __________________________________ ___________ ____ ____ _ Glyphaspis ____ ___________ _______________________ ___ ____________ _ 

Ampahoia spatulata, A. sp. cf. A. typa, Dicellomus nana, Linnarssonella 

tennesseensis, L. sp. cf. L. modesta. 

Arapahoia spatulata, A. typa, Blountia dunoirensis'? ______ ___________ _ 

Crepicephalus tripunctatus, M aryvillia sp. cf. M. ariston, Hyolithes sp __ _ Blountia sp., Kingstonia sp., Tricrepicephalus sp., Aphelaspis sp ___ __ _ _ 

Taenicephalus cordillerensis, Saratogia sp., Billings ella coloradoensis ____ _ Elvinia n. sp., Pterocephalia n. sp ____ __ ____ ___ ______________ _____ _ _ Dike/acephalus ____ __________ __ __ ________ ______ - _- _--------------

Peronopsis?, Hyolithes?, Elrathiella, Westonia cf. W. ella _____________ _ Tricrepicephalus tripunctus, Dicellomus nan us ________ ____ _____ _____ _ Tricrepicephalus ( Crepicephalus zone) ___ _____ ____ ________ _________ _ 

Billingsella, Eom·this, Glyptotrophia, Linnarssonella, Berkia, Bernia, 

Dellea, Parabolinoides (Elvinia zone). 

Billingsella, Eoorthis, Huenella, Bemaspis, Orygmaspis, Taenicephalus 

( Taenicephalus zone). 

Approximate horizon of the type of Westonia dartoni of Walcott ___ ___ _ 

Lingulepis; an undescribed trilobite of pre-Cedaria Middle Cambrian age_ 

Miller (1936, p. 132). 

Denson (1942). 

Miller (1936, p. 132). 

Do. 

Miller (1936, p. 131). 

Do. 

Do. 

Eliot Blackwelder (U.S. 

Geol. Survey, unpub. 

field notes). 

Do. 

Do. 

Shaw (1957). 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

DeLand and Shaw (1956, 

p. 561). 

Love (1939, p. 16). 

Miller (1936, p. 137). 

Deiss (1938, p. 1099) . 

Do. 

Deiss (1938, p. 1097, 

1098). 

Miller (1936, p. 136); 

Deiss (1938, p. 1096). 

Deiss (1938, p. 1906). 

Miller (1936, p. 136). 

Deiss (1938, p. 1095). 

Miller (1936, p. 136) . 

Deiss (1938, p. 1094) . 

Deiss (1938, p. 1093). 

Woodward (1957, p. 222). 

Do. 

Shaw (1957). 

Van Houten and Weitz 

(1956); Shaw (1957). 

Van Houten and Weitz 

(1956). 

Shaw (1957). 

Do. 
PALEOZOIC FORMATIONS B17 

Southeast of \'T arm Spring Creek, along the east flank 

of the Wind River Range, the thickness of the Gros 

Ventre Formation ranges from a minimum of 300 feet 

to a maximum of about 760 feet (pl. 2). The three 

members can be recognized at least as far southeast as 

Bull Lake Canyon, but farther south the Death Canyon 

Limestone Member becomes progressively more shaly 

and sandy and loses its identity as a resistant cliff-forming unit. In Sweetwater Canyon at the southeast end of 

the range, the Gros Ventre is chiefly interbedded shale 

and sandstone with numerous thin beds of limestone 

and flat-pebble conglomerate in the upper one-third to 

one-half of the formation. 

The three members of the Gros Ventre Formation are 

also easily identified in outcrops along the south 

side of the Washakie Range where their aggregate 

thickness ranges from 500 to 700 feet. Sufficient observations have not been made in the Circle Ridge area 

(pis. 1, 3) to determine the presence of the Death Canyon Limestone Member, but this unit seems to have disappeared by facies change at least as far west as the 

exposures near Merritt Pass in the western Owl Creek 

Mountains (T. 8 N., R.1 W., pl.1). 

In the Owl Creek and southern Bighorn Mountains 

the Gros Ventre Formation is a nonresistant unit consisting largely of interbedded gray-green and tan glauconitic micaceous shale, sandstone,· and siltstone and 

some beds of limestone and flat-pebble conglomerate in 

the upper part (fig. 9). Some of the sandstone is hematitic and red to reddish brown. Thickness ranges from 

150 feet in the eastern part of this region to 575 feet in 

the central and western parts; variations seem to be 

largely the result of eastward interfingering with the 

upper part of the Flathead Sandstone (pl. 3). Because 

of this interfingering, Miller ( 1936, p. 123, 124) proposed that the Flathead and Gros Ventre be combined 

as a single unit and applied the name l,)epass Formation to all Cambrian rocks older than the Gallatin Limestone. Tourtelot and Thompson ( 1948), Tourtelot 

( 1953), and Woodward ( 1957), however, differentiated 

the Flathead and Gros Ventre Formations on the basis 

of detailed mapping of the Cambrian rocks in this 

reg10n. 

Along the south margin of the Wind River Basin, 

strata assigned to the Gros Ventre Formation are predominantly reddish-brown and gray fine-grained sandFtGuHE 9.- Camllrian, Ordovician, Mississippian, and Pennsylvanian strata exposed a long west wall of Wind River Canyon, central Owl 

Creek :\Iounta ins. !Pta, Teusleep and Amsden Formations; Mm, Madison Limestone ; Ob, Bighorn Dolomite; Cg, Gallatin Limestone; Cgv, 

Gros Ventre Formation. 
B18 GE·OLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

stone, siHstone, and a few thin beds of shale. In the 

Conant Creek area, beds of gray glauconitic flat-pebbl e 

limestone conglomerate, possibly equivalent to part of 

the Death Canyon Limestone Member, are present in 

the middle of the formation; some of these beds extend 

as far east as the East Canyon Creek section, but they 

seem to be entirely absent at the north end of the Rattlesnake Hills (pl. 4). Thickness of the Gros Ventre Formation decreases from 512 feet in Sweetwater Canyon 

to 287 feet in the northern Rattlesnake Hills. The decrease in thickness easbvard is caused by interfingering 

with the Flathead Sandstone at the base of the formation and possibly in part by truncation at the top by the 

Madison Limestone. The Madison bevels eastward 

across successively older beds in the Cambrian sequence, 

overlaps the entire Gallatin Limestone in the southcentral part of the basin, and rests on the Gros Ventre 

Formation at the north end of the Rattlesnake Hills 

(pl. 4 a.nd fig. 15; Shaw, 1957, p. 12). 

Inasmuch as the Cambrian rocks overlying the Flathead in the south-central part of the Wind River Basin, 

and adjacent regions to the south, are atypical of the 

Gros Ventre Formation farther west and northwest, 

Shaw (1954) introduced a new name, Buck Spring Formation, for this red facies. That name, however, has 

not yet been used widely in the vVind River Basin. 

A well drilled in the North Casper Creek oil field 

along the east edge of the Wind River Basin (pl. 5) penetrated 205 fee t of Cambrian strata between the Madison Limestone and the Flathead Sandstone. This sequence, consisting chiefly of purple and tan to white 

glauconitic micaceous siltstone in the lower part and 

purple and gray glauconitic dolomite in the upper part, 

may represent only the Gros Ventre Formation, or it 

may also contain some equivalents of the Gallatin Limestone. Farther south, however, at the west end of Casper Mountain, these particular strata are entirely cut 

out beneath the Madison Limestone which rests directly 

on the Flathead Sandstone. 

Contact With the Gallatin Limestone 

The contact betw.een the Gros Ventre Formation and 

the overlying Gallatin Limestone, in those areas where 

the Du Noir Limestone Member is present at the base 

of the Gallatin, is marked by a sharp change from grasscovered shaly slopes below to cliff-forming limestone 

above (figs. 7, 9). In subsurface sections there is an 

easily recognized shift in the resistivity curves on electric logs (pl. 6). Where the Du Noir Limestone Member is absent or poorly developed, however, the formation contact is not so readily defined. At the south end 

of the Bighorn Mountains, ·w·oodward (1957, p. 217) 

stated that "it is difficult if not impossible to differentiate the Gros Ventre from the overlying Gallatin northeastward from the point of disappearance of the basal 

Du Noir limestone member of the Gallatin." Similarly, 

along the south margin of the Wind River Basin, east 

of Conant Creek, Shaw (1957) recognized the possibility that the upper part of the Gros Ventre Formation (his Buck Spring Formation) contained some 

equivalents of the Gallatin Limestone. 

An erosional unconformity between the Gros Ventre 

Formation and Gallatin Limestone was observed by 

Miller (1936, p. 122) in the Teton Range and by Blackwelder (1918) at the type seotion of the Gros Ventre 

in the Gros Ventre Range in northwestern Wyoming. 

Miller (1936, p. 119) reported an unconformity locally 

in the vVarm Spring Creek area in the northern Wind 

RiYer Range, and DeLand (1954) described a similar 

relation between the two formations in the Sweetwater 

Canyon area at the south end of the range. Elsewhere 

in the '\Vind River Basin the contact seems to be conformable. 

In the southeastern part of the basin, strata assigned 

to the Gros Ventre Formation are overlain, and in some 

places completely overlapped, by the Madison Limestone. 

Age 

Fossils collected from the Gros Ventre Formation 

(table 2) indicate that over much of the basin area the 

formation is of middle to late Middle Cambrian age. 

The Oedaria zone is represented in the upper part of the 

formation; this zone is considered to mark the base of 

the Upper Cambrian Series (Howell and others, 1944). 

Strata assigned to the Gros Ventre Formation are 

so mew hat younger in the eastern part of the Wind 

River Basin that in the western part. Both in the Rattlesnake Hills and southern Bighorn Mountain areas 

(pl. 3, 4), east of the wedge edge of the Du Noir Limestone Member of the Gallatin Limestone, the stratigraphic and paleontologic relations suggest that the 

upper part of the Gros Ventre is in part the age equivalent of the Du Noir (Shaw, 1957, p. 13; Woodward, 

1957, p. 223, fig. 4). The base of the Gros Ventre also 

becomes younger eastward because of intertonguing 

with the Flathead Sandstone (fig. 5). 

Conditions or Deposition 

Strata of the Gros Ventre Formation are offshore 

deposits that were laid down contemporaneously with 

the shore and near-shore sediments of the Flathead 

Sandstone as the Cambrian sea continued its eastward 

transgression across central Wyoming (fig. 5). The 

Death Canyon Limestone Member probably was deposited during a more easterly advance of the sea than 

was the overlying Park Shale Member; if so, there may 

have been a limited westward retreat of the shoreline, 

or the shoreline may have been nearly stabilized in one 
PALEOZOIC FORMATIONS Bl9 

position, during the early part of the deposition of the 

Park. Later, the sea readvanced and limestone was 

deposited along with the shale over much of the wind 

River Basin area. 

Shaw (1957, p. 13) cites evidence that the reddishbrown clastic rocks of the Gros Ventre Formation (his 

Buck Spring Formation) in the south-central part of 

the basin are partly marine and partly nonmarine. He 

concludes that this area, and the adjacent area to the 

south, were emergent periodically "either through local 

uplift to the south of Wyoming or simply by filling of 

the sea at a faster rate than the eustatic rise of sea level 

could submerge the sediments." Although the data are 

inconclusive, Shaw (1957, p.13) favors the second interpretation, because ( 1) the strata generally lack coarse 

conglomerates and ( 2) the repeated intercalation of 

sandstones containing inarticulate brachiopods suggests 

a very close balance between depositional filling and 

marine transgression such as would occur on a low shelving shore. 

In the western part of the Wind River Basin the Park 

Shale Member of the Gros Ventre Formation was partially eroded before the deposition of the Du N oir 

Limestone Member of the Gallatin Limestone. Farther 

east, however, sedimentation seems to have been continous. 

The origin of limestone flat-pebble conglomerate beds 

has been discussed by several workers. McKee ( 1945, 

p. 65-70) presents an excellent summary of the different 

views bearing on this subject in connection with his detailed studies of the Cambrian rocks of the Grand Canyon region. He (McKee, 1945, p. 67-69) observed that 

the flat-pebble conglomerate beds in the canyon region. 

are common in regressive deposits, but they do not occur 

in transgressive deposits, and that they developed exclusively along the shoreward margins of the limestone 

facies. Although most previous investigators believed 

that such conglomerate was formed near shore and in 

shallow water (beach or tidal-flat conditions), McKee 

(1945, p. 69) concluded that some were formed at least 

100 miles seaward from the strand line. From the sedimentary relations, he further concluded that these beds 

originated at a time when basin sinking ceased or slowed 

down to such an extent that sedimentation built up the 

bottom, partly above the profile of equilibrium, after 

which the sea regressed and conglomerate was formed 

in favorable localities. 

Regarding similar deposits in parts of Montana and 

Wyoming, Lochman-Balk (1957, p. 145) and Robinson 

(1963, p. 20) agree that the flat limestone pebbles formed 

largely through fragmentation of previously deposited 

limestone by wave and current action, although Robinson also suggests that some of the conglomerate may 

have formed as a result of different rates of lithification 

of thin-bedded strata. The distribution of flat-pebble 

conglomerate. in the Cambrian sequence of the Wind 

River Basin seems to be very similar to that found elsewhere across the Rocky Mountain foreland region, but 

few studies have been made. In a brief discussion Shaw 

(1957, p. 13) suggests that the normal condition for the 

development of the conglomerate was one of shallow 

water with restricted circulation. 

·Glauconite, though absent in most of the Paleozoic 

rocks of central Wyoming, is abundant in many of the 

Cambrian units. Conditions facilitating the development of glauconite have been summarized by Cloud 

(1955) and Lochman-Balk (1957). These include: (1) 

marine waters of normal salinity, (2) slightly reducing 

environment resulting from decaying organic matter, 

(3) ingestion of sediment by bottom-dwelling organisms 

having low oxygen requirements, ( 4) presence of micaceous minerals (especially biotite) or bottom muds of 

high iron content, and ( 5) slow sedimentation rate to 

avoid rapid burial of bottom sediments. Presumably, 

many of these conditions existed during the deposition 

of much of the Paleozoic succession in this region. 

However, one important factor seems to set the 

Cambrian apart from the younger rock systems. 

The Cambrian seas advanced across an eroded surface 

of Precambrian crystalline rocks which doubtless furnished a greater supply of micaceous minerals than did · 

any of the succeeding periods of the Paleozoic. Where 

other favorable conditions were met along the slowly 

submerging shelves, a significant quantity of these 

minerals was probably converted to glauconite. 

GALLATIN LIMESTONE 

Definition 

The Gallatin Limestone, the youngest Cambrian formation in central Wyoming, was named and described 

by Peale (1893, p. 22, 23) from exposures in the Gallatin Range of southwestern Montana. At the type 

section it originally included in its lower part limestone 

and shale of Middle Cambrian age, which probably constitute the upper part of the Gros Ventre Formation 

as that unit was later defined by Blackwelder ( 1918), 

and limestone of Late Cambrian age in its upper part. 

Inasmuch as the Galla tin Limestone, as used in the 

Wind River Basin, is not completely representative of 

the type Gallatin, Deiss ( 1938, p. 110±) substituted a 

new name, Boysen Formation, for all Upper Cambrian 

rocks in the Wind River Canyon area and subdivided 

it into the Maurice, Snowy Range, and Grove Creek 

Members (pl. 3) . The Boysen, although extended westward into the Gros Ventre Range by Foster (1947, p. 

154 7) and Wanless and others ( 1955, p. 13), has not 

gained wide acceptance in central Wyoming. 
B20 GEOLOGY OF THE WJN:D RIVER BASIN, CENTRAL WYOMING 

Along the east flank of the Wind River Range the 

Gallatin Limestone can be divided into three units: 

a thin lower limestone unit, a thin middle shale unit, 

and a thick upper limestone unit. 'The basal limestone 

was named the Du N oir Member (referred to as the 

Du N oir Limestone Member in this report) by Miller 

('19'36, p. 124, 125) ; the section along Warm Spring 

Creek at the northwest end of the range was designated as the type (fig. 7). Shaw (1957, p. 13-15) 

classed the Gallatin as a group in this region, raised the 

Du N oir to formational status, and named the remainder the Open Door Limestone (Shaw and DeLand, 

1955, p. 38) from exposures along the east ·wall of 

Granite Canyon, just below the topographic feature 

known as the "Open Door" in the Gros Ventre Range 

in northwestern Wyoming. The Open Door Limestone 

included the thin shale ~unit at the base that was referred 

to as the Dry Creek Shale Member by Shaw (1957, p. 

14) following the redefinition of that unit by Lochman 

( 1950) in central l\fontana. Although Shaw's terminology is used in this report, it is modified to the extent 

that the Gallatin is retained as a formation, and the 

Open Door and Du N oir are classed as members, because 

they are generally mapped as one unit. 

Lithology and Thickness 

The Gallatin Limestone is a resistant sequence that 

forms conspicuous cliffs above the shale slopes of the 

Gros Ventre Formation. It forms the lowermost series 

of ledg0s in many canyons. The formation is 265-365 

feet thick in the Wind River Range. In the Washakie 

Range, and Owl Creek and southern Bighorn Mountains the minimum thickness is about 235 feet and the 

maximum is 455 feet (pl. 3), although Darton ( 1906a, 

p. 14, pl. IV -b) described a section in Ow I Creek Canyon (T. 8 N., R. 3 W.) in which the Bighorn Dolomite 

apparently rests directly on shale of the Gros Ventre 

Formation with no intervening Gallatin. Along the 

south edge of the Wind River Basin the formation can 

be traced from Sweetwater Canyon eastward only as far 

as the Conant Creek area, where it is 209 feet thick. 

Farther east the Du N oir Limestone Member at the base 

merges with elastic sediments of the Gros Ventre Formation (pl. 4). In the eastern and southeastern parts 

of the basin the Gallatin Limestone is entirely cut out 

by the erosional unconformity at the base of the Madison Limestone. 

Along Warm Spring Creek, at the northwest end of 

the Wind River Range, the Du Noir Limestone Member 

is a prominent 48-foot eliff-forming unit (fig. 7) of gray 

thin-bedded highly glauconitic and oolitic limestone 

with some flat-pebble conglomerate. The overlying 

lower shale unit of the Open Door Limestone Member is 

54 feet thick and consists chiefly of soft greenish-gray 

shale with a minor amount of thin-bedded gray limestone. The upper 263 feet of the Open Door is a hard, 

resistant series of gray thin-bedded to massive limestone 

and a few flat-pebble conglomerate beds. The uppermost part of this member is commonly mottled with tan 

small irregular masses of granular limestone. Some of 

the exposed surfaces weather to a rough pitted surface 

similar to ·the overlying Bighorn Dolomite. 

The Gallatin Limestone in many places contains 

cavities filled with red earthy deposits which, where 

exposed on the sides of the cliffs, contribute much red 

staining to the outcrops. Because of this, the outcrops, 

when viewed from a distance, appear to contain much 

red material. 

The characteristic lithologies of the two members of 

the Gallatin are readily distinguished in most other sections southeast along the east flank of the Wind River 

Range. Contacts between members are not drawn 

through some of the localities shown on plate 2, but this 

is chiefly because of poor exposures and (or) the lack 

of adequate observations. The Du Noir Limestone 

Member is 82 feet thick in Sweetwater Canyon at the 

southeast end of the range, which is the maximum observed for this region. The overlying shale unit of the 

Open Door at the same locality (pl. 2) is only 23 feet 

thick and contains a few thin white sandstone and red 

siltstone beds in addition to limestone. 

Shaw (1957, fig. 3) has traced the DuN oir Limestone 

Member as far east as the Conant Creek area along the 

south margin of the Wind River Basin, where he assigned 110 feet of limestone and sandstone to the unit. 

Farther east, the limestone wedges out into elastic strata 

of the Gros Ventre Formation and the member becomes 

unidentifiable (pl. 4). 

The subdivisions of the Gallatin Limestone are easily 

recognized in the Washakie Range. The Du N oir Limestone Member can be traced eastward along the entire 

south side of the Owl Creek Mountains and into the 

southern Bighorn Mountains, but there the limestone 

disappears because of facies change (Woodward, 19·57, 

fig. 4). The Open Door Limestone Member also becomes progressively more shaly and sandy eastward 

(pl. 3). 

In subsurface sections in the western part of the Wind 

River Basin the Gallatin Limestone is easily identified 

from electric logs (pl. 6) . 

Contact With the Bighorn Dolomite 

An erosional unconformity separates the Gallatin 

Limestone from the Bighorn Dolomite. In the Warm 

Spring Creek area, at the northwest end of the Wind 

River Range, Miller (1936, p. 131) noted 100 feet of 

beds at the top of the Gallatin on Warm Spring Mountain (Wlj2 sec. :35, T. 42 N., R. 108 W., pl. 1) that are 
PALEOZOIC FORMATIONS B21 

absent 3 miles farther west. At th'e southeast end of 

the range, Bell ( 1955) observed that the contact relief 

is as much as 3 feet, and that debris from the uppermost 

Cambrian rocks is incorporated in the Lander Sandstone Member of the Bighorn. In Owl Creek Canyon, 

at the northwest corner of the Owl Creek Mountains, 

the Gallatin was apparently cut out by pre-Bighorn 

erosion (Darton, 1906a, p. 14). In the Wind River 

Canyon area, Tourtelot and Thompson (1948) reported 

a sharp uneven contact at the top of the Gallatin and 

fragments of limestone locally in the basal 3-5 feet of 

the overlying Bighorn. In many other places, however, the formation contact shows little evidence of the 

considerable length of time (Late Cambrian to Middle 

or Late Ordovician) that transpired between the deposition of the Gallatin and that of the Bighorn Dolomite. 

Both the Gallatin and the Bighorn commonly form 

cliffs, but the massive character of the Bighorn is generally in sharp contrast to the more prononnced banded 

appearance of the Gallatin (fig. 9). The formation 

bonndary is easily detected on electric logs (pl. 6). 

In the eastern Owl Creek and southern Bighorn 

Mountains and in the Conant Creek area along the 

south edge of the basin, the Gallatin Limestone is overlain directly by the :Madison Limestone. 

Age 

Fossils collected in the Wind River Basin and adjacent regions (ta!hle 2; Miller, 1936, p. 140, 141; Shaw, 

1957, p. 14, 15) indicate the following zonation for the 

Gallatin Limestone: Du N oir Limestone MemberOedaria, Orepicephaltus, and possibly Aphelaspis zones; 

Open Door Limestone Member- Aphelaspis and Elvinia zones in the lower shale unit and Elvinia and 

other zones of Late Cambrian and possibly earliest 

Ordovician age in the upper limestone unit. Thus, the 

formation is largely, if not wholly, Late Cambrian in 

age. 

Regionally, LochlJlan-Balk and Wilson (1958, p. 334) 

have described an extensive faunal change between the 

Aphelaspis and Elvinia zones. They attribute this 

change to widespread emergence and shallowing of the 

seas. across much of the North American cratonic and 

miogeosynclinal areas. The boundary between these 

two zones corresponds closely to the contact between 

the Du Noir and Open Door Limestone Members of 

the Gallatin. As noted by Shaw (1957, p. 14), and as 

discussed below, sedimentary features suggest a break 

in sedimentation between these two units in the western 

part of the Wind River Basin. 

Conditions of Deposition 

Before the Gallatin Limestone was deposited the sea 

had apparently withdrawn from the western part of the 

Wind River Basin area, but it had remained in the cen2(}5'-54() 0-&6----4 

tral and eastern parts. At the beginning of the depositional period represented by the Du N oir Limestone 

Member, the entire region was again submerged and 

carbonate sediments accumulated in the central and 

western parts of the basin area and clastic sediments 

in the eastern part. The flat-pebble conglomerate in 

the upper part of this member, and the shale in the 

overlying Open Door Limestone Member, suggest that 

regression, and perhaps emergence, took place at this 

time. In Late Cambrian time, which is represented by 

the upper limestone of the Open Door Limestone Member, the sea expanded eastward beyond any of its previous limits and extended across at least the northern 

half of Wyoming and into the Black Hills region. 

Cavities filled with red earthy material at some horizons 

within the Open Door Limestone Member may indicate 

that parts of central Wyoming were periodically emergent during Late Cambrian time. 

At the end of Cambrian time, or shortly thereafter, 

the sea withdrew completely from central Wyoming and 

the entire region was exposed to erosion. There is, 

however, little evidence of this widespread regression in 

the uppermost Cambrian rocks. 

ORDOVICIAN ROCKS, BIGHORN DOLOMITE 

Definition 

The Bighorn Dolomite, defined by Darton (1904, p. 

394-396) from typical exposures along the east flank 

of the Bighorn Mountains, includes all the rocks of 

Ordovician age in central Wyoming. Because it invariably forms cliffs, the Bighorn is perhaps the most 

conspicuous Paleozoic formation in the mountains along 

the west and north sides of the vVind River Basin (figs. 

4, 9). 

In the type area, Darton (1906b, p. 26, 27) recognized 

three lithologic subdivisions of the Bighorn (which he 

called the Bighorn Limestone) : a lower light-gray 

sandstone, a middle massive buff limestone, and an 

upper thin-bedded white to gray limestone containing, 

locally, a red-weathering fossil-rich zone at the top. 

Later work by Kirk ( 1930, p. 460-46·5) in the southern 

Bighorn and eastern Owl Creek Mountains indicated 

that the basal sandstone is in reality two nnits separated 

by an erosional unconformity. Kirk concluded that (1) 

the lowermost sandstone, which contains abundant fish 

remains, does not extend south and west of the eastern 

end of the Owl Creek Mountains and is the equivalent 

of the Middle Ordovician Harding Sandstone of central 

Colorado; and (2) the upper sandstone, which has few, 

if any, fish remains but a large invertebrate fauna, is 

of much wider distribution and forms the base of the 

Bighorn proper. Thomas (1952, p. '35) and Ross 

(1957a, p. 17) concur in this interpretation. 
B22 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

In the Wind River Range the basal sandstone (postHarding Sandstone equivalent) of the Bighorn Dolomite was called the Lander Sandstone Member by Miller ( 1930, p. 196) from outcrops along the Middle Popo 

Agie River southwest of Lander (near the Sinks Canyon 

section shown on pl. 2). The upper thin-bedded dolomite was referred to the Leigh Dolomite Member by 

Blackwelder (1918), the name being derived from the 

canyon of that name in the Teton Range of northwestern Wyoming. The middle massive dolomite has not 

received formal designation. 

Lithology and Thickness 

T~e Lander Sandstone Member occurs only locally 

along the east flank of ·the Wind River Range (pl. 2). 

It is a lenticular gray to tan, in part red, fine- to coarsegrained sandstone generally less than 5 feet thick. 

Fragments of the underlying Gallatin Limestone are 

commonly incorporated in the basal part. Because the 

member is thin and lenticular and easily concealed by 

talus, it may have a wider distribution than is apparent 

from known outcrops. 

The unnamed middle member of the Bighorn Dolomite is a remarkably uniform sequence of very resistant 

cliff-forming buff to light-gray massive granular dolomite. The lower part is rather limy in places and commonly darker gray, but it still retains its granular texture. The dolomite weathers to a very rough pitted surface (fig. 10) that consists of a randomly branching network of slightly raised ridges a fraction of an inch in 

height and width. In Dinwoody Canyon, J. F. Murphy 

(oral commun., 1963) found a conglomerate lens, 1 inch 

thick, 11 feet above the base of the massive dolomite, 

which contains pebbles of igneous and metasedimentary 

rocks Vs-1,4 inch across. Farther south, in Bull Lake 

Canyon, Murphy and others (1956) described beds of 

dolomite breccia at the top of the member, and cave 

fillings of thin-bedded dolomite in the upper part. 

Thickness of the middle member ranges from about 

230 feet in the central and northern Wind River Range 

to only about 15 feet in the southern part. The decrease 

in thickness southward is the result of beveling at the 

top by Mississippian and (or) Devonian strata, and 

perhaps the result in part of nondeposition. 

The Leigh Dolomite Member consists chiefly of white, 

gray, and pink thin-bedded _to platy dolomite. The 

dolomite is dense, porcelaneous, and weathers chalky 

FIGURE 10.-Weathered surface of Bighorn Dolomite showing typical "fretwork" pattern. Outcrop along east side of Horse Creek, southcentral Wa shakie Range. 
PALEOZOIC FORMATIONS B23 

white. It generally forms a conspicuous recessed white 

band along the cliff faces. Beds of massive dolomite 

similar to those in the underlying middle member of 

the Bighorn are in the upper part of the Leigh at many 

localities. The member.is 85 feet thick at the northwest 

end of the Wind River Range, but thins southward and 

disappears, owing to the erosional unconformity at the 

top. 

The middle and upper members of the Bighorn Dolomite, which have a combined thickness of 210-300 feet, 

are readily identified in the Washakie Range; the 

Lander Sandstone Member is only locally present, but 

in some sections it is as much as 7 feet thick. In the 

Circle Ridge area the Bighorn is 260 feet thick, but 

because of the unconformity at the top, it thins progressively eastward to a wedge edge 'at the east end of the 

Owl Creek Mountains (fig.11; Thomas, 1952, p. 35), 

approximately at the east edge of T. 40 N., R. 92 W. 

Sandy beds at the base of the formation in Wind River 

Canyon and in the eastern Owl Creek Mountains probably represent the Lander Sandstone Member rather 

than the Harding Sandstone equivalent. The Bighorn 

Dolomite is not present in the Badwater and Deadman 

Butte sections in the southern Bighorn Mountains (pl. 

3), but it reappears beneath the Madison Limestone a 

few miles farther north and thickens along the east 

flank of the range toward the type area. 

The Bighorn Dolomite is absent along the east and 

south margins of the Wind River Basin (fig. 11), although in the Conant Creek area the lower part of the 

Madison Limestone is a hard ragged-weathering siliceous dolomite that has been mistaken for the Bighorn. 

Contact With Overlying Rocks 

The Bighorn Dolomite is overlain unconformably 

by the Darby Formation in the central and northern 

parts of the Wind River and Washakie Ranges, and 

western Owl Creek Mountains and by the Madison 

Limestone in the e'astern Owl Creek Mountains (fig. 9) 

and southern Wind River Range. Along Warm Spring 

Creek in the northern Wind River Range the erosional 

unconformity at the top of the Bighorn is marked by 

earthy beds having layers and cavities filled with calcite 

crystals. The upper contact has as much as 20 feet of 

relief and at one place in the north wall of Warm 

Spring Canyon a large mass of breccia is present in the 

top of the Bighorn Dolomite. As discussed below, this 

breccia may represent a channel filled with Devonian 

sediments similar to those that have been found in the 

Dinwoody Canyon and Bull Lake Canyon areas. The 

contact is generally irregular and shows several feet 

of local relief at many other localities; in some places, 

however, there is little physical evidence of the long 

hiatus between the Bighorn and next overlying strata. 

The Darby Formation is more easily eroded than the 

Bighorn, and generally forms slopes above the massive 

dolomite cliffs. 

Where the Bighorn Dolomite is overlain by the Madison Limestone, the contact is likewise sharp and irregular in most places. At the south end of the Wind 

River Range, Bell (1955) observed that a weathered 

surface occurs at the top of the Bighorn and that vertical fractures or channels filled with red siltstone extend 

down several feet into the underlying dolomite. Where 

the basal part of the Madison is dolomitic, however, 

the contact is not always apparent. 

Age 

The Bighorn Dolomite contains sparse poorly preserved fossils, including corals, mollusks, and crinoids, 

in the western and northern parts of the Wind River 

Basin (table 3). Probably the most characteristic form 

is the chain coral 0 atenipora (formerly a subgenus of 

H alysites). The large.st collections of fossils were obtained by Miller ( 1930) . At the type locality of the 

Lander Sandstone Member (Sinks Canyon section, pl. 

2), for example, he (Miller, 1930, p. 198-201) found a 

total of 135 different species, mostly mollusks. Along 

the southeast edge of the Bighorn Mountains (northeast of the Deadman Butte section shown on pl. 3), 

Amsden and Miller ( 1942) collected several species of 

conodonts from both the Harding Sandstone equivalent 

and the next younger Lander Sandstone Member. 

'There seems little doubt that the Harding Sandstone 

equivalent is Middle Ordovician. However, despite the 

variety of fossils found in the younger parts of the Bighorn Dolomite, including the Lander Sandstone Member, agreement has not yet been reached regarding the 

exact stages of Ordovician time that are represented by 

the formation. The problems have been discussed in 

many papers (for example, Ross, 1957b; Thomas, 1952, 

p. 35; 1948, p. 83; Love, 1939, p. 20). No new information for dating the formation was obtained during this 

investigation ; the main issues are summarized below. 

Darton (1906b, p. 29) considered the upper part of 

the Bighorn Dolomite in the Bighorn Mountains as 

Late Ordovician (Richmond) and the lower part as 

Middle Ordovician (Trenton), based on fossil identifications by E. 0. Ulrich. This interpretation prevailed 

in central Wyoming until Miller (1930, 1932) found 

that 25 of the relatively diagnostic species from the 

Lander Sandstone Member seem to indicate Middle 

Ordovician (Trenton and possibly Black River) age 

and 22 Late Ordovician (Richmond) age. He (Miller, 

1930, p. 203, 204; 1932, p. 203, 209) concluded that the 

appearance of Richmond fossils is sufficient to fix the 

age of the lower part of the Bighorn Dolomite (Lander 

Sandstone Member) as very Late Ordovician. Suhse-
r-1,)0° 109° 108° wr 

I r ~- p ~ R K ~ I ·r T I i 4~\ ,.!'-' -''\, ~" . - ! ~ w 6 A s H A K I E I I I I I I I I I I 

I 45 ~ ) ~ '1'- I // I If 112w! "' !1c 109 4o8 ~ 106 105 1~4' 103 1b2 i'Toi 1--!.o.o 99 98 V97 go; -95 9~ ,Jl3 

4

;2 91 90 89 88 87 86 1 "~ 84

1

1 83 1! 82 1

1

811

1 

8 " 1 

1 

1 1 1 • · 

I r-- ~ 144 oo P I J , / 

4

4-- - t- -+- - ~' H T S P F lel' G ~ / L-- -- f -? ..._C l 1 1 r , 1 r '= J---,..7~ __ ... v .. 1 17 x I 

·\ 43 / r--. _;· .. -' . lt..-.. 43 I 1/ I II J I 0 i )( , \ '-!... "' ....---r . ./ I ./ lTherm poli~ I • / r I T r ~tt . 18 .....,..J---' ~ /- v ~ TfETOfNj' ~- r·~ ~ --~~v.l\. 1 42 ,r 1 1 .• " ' ,~-- x- L- L., ./ ' V. I l J :~JU I "--- (< bD b ·' ' 'i' "T I I , I 41 '~'- u ~~ T 6 - -~ , L....J' v4')( J~~~- ·- ---, L~ +---+- -i _J __ -->--~ 

l I ' f 4~- ! "\ X ~ '~ J ~/ ~ ~ l I y ~ ,;-~ ! '-. ' ""~ ll I 

f---.. Y.r; 5 4 3 2 R.1 W. R.'fi.E 2 3 / 4 5 6j lv l " 

1

1 

39 \ I ' f -, 39 I " 

r x 1 '\1 4 J I : f ' I 

38 o -~ T re j 1 l.....,---~',.....38 i \ I 

r ~v- '\ I \ 3 I / I 1 I I ' 37 / \ I ,\ X II I l 37 I \ h-ll 

' ! '\t\. ~- /2 / luJl !

3 6 I \ I I'\"" I I T / 3 6 I \ I I IJ I 

I 13s I )_~I 1 \ ~ If e ~ ~ 'F.ivert n 35 l t\ I T ,TlJ 

j- '~ 1\X' T I v I N A T 'if 0 N A 

~43° 

34 

~ 

.I ~ 1\ s . 34 ; 

' __ ,_ \ ~ J-?._,~'- _/ -rt -~-~- ._J I }-

-I:> I 

0 I ~ "_l I \ f\1~ 1 L., " I \ I •1 " i I " ~ 1

32 

/ I 1 l ~J ' xk • l 32 1 '\, 1 1 1 1 

Cjsper I ~~ 

I I I ' i""l ..... \ I ) I .1.-- l-- -+- - - - J I I 1 111 11· 

TIE I r--..-4/' ~---, 1---. __.....1 

I s 13'u B L E T 

i II ~~l~ ~X I I ~fl I ~ .. ~ ~ ~ ~ ~ l fB~u~:,t~~:.~~:1;~;vf'\ 30 

EXPLANATION 

X 

Surface section 

• 

Subsurface section 

0 10 20 30 MILES 

' l I I ' _I_L ) I I l- - - - - -~- - -ttnr F R 

-:br!_t~l~- - -11---I~ -l-1- ___,i---+_,--+--+--++-+-+--+--+----+---+-----+-+ 

l;>o 

IZ 

I< c I I A I I I R I I B I I o I IN I !>rl 

~ 

" I " I " I " I t I " I " I " I " I eo I " I " ! J,.l i 1 [ I I I I I I I I I ! 42° 

~~--+----

26 

E / T /w I A !I Tj25 E I R I 98 97 I 96 95 9-4 u !L3 . 9_2 l 91 90 I 

Sf w IE 

hclJ2VJ 101 !1 oo I 99 

ll II I ILH4 1 I FIGURE H.-Thickness of map of Bighorn Dolomite in central Wyoming. Interval is 100 feet; isopachs are res:tored across mountain arches where rocks have been eroded; isopachs 

are dashed where control is inadequate. 

·to 

t..,:) 

~ 

~ 0 

~ 

0 

~ 

0 

lo%j 

t-3 

~ 

~ 

~ t::J 

::0 

~ t<:l 

::0 

~ Ul 

__ z 

Q 

~ ::0 

~ 

~ 0 

~ ~ 

z 

0 
Collection 

Stratigraphic section No. 

(pls. 

2-5) 

Dinwoody Canyon____ 4 

5 

Bull Lake_ _ _ _ _ _ _ _ _ _ _ 1 

1a 

Sinks Canyon________ 1 

2 

Sweetwater Canyon___ 9 

Windy Gap__________ 2 

3 

PALEOZOIC FORMATIONS 

TABLE 3.-Fossils from the Bighorn Dolomite 

[Generic and specific names are quoted without modification from sources shown] 

Species 

Catenipora gracilis, Streptelasma aff. S. foerstei, Grewinkia sp., Calapoecia 

sp., Nyctopora sp., Zygospira cf. Z. jupiterensis, Paucicrura sp., 

Sowerbyella or Thaerodonta sp., Platystrophia sp., Hesperorthis sp., 

Cyclendoceras? sp. 

Streptelasma sp., Euomphalopterus? sp., Fusispira cf. F. injlata, Halysites 

gracilis, Drepanodus subrectus, Panderodus gracilis. 

Halysites (Cdtenipora) cf. H. gracilis, "Holophragma" sp.; unidentifiable 

streptelasmoid coral, brachiopods, and cephalopods. 

Drepanodus curvatus, Oistodus sp., Panderodus cf. P. gracilis, Cordylodus 

sp., Ozarkodina sp. A, Ozarkodina sp. B, Ligonodina sp., Trichonodella? 

sp., Belodina compressus, Prioniodina sp. 

Composite fauna from the Lander Sandstone Member in Sinks Canyon 

and vicinity, collected and described by Miller. The following species are included: Receptaculites, 1; Cyclocrinites, 1; coral, 7; worm, 1; 

brachiopods, 27; pelecypods, 13; gastropods, 34; cephalopods, 50; 

trilobites, 1. 

Composite fauna from the middle massive dolomite and Leigh Dolomite 

Members in the central Wind River Mountains, collected and 

described by Miller. Includes Receptaculites arcticus, Streptelasma 

corniculum, S. robustum, S. sp., Columnaria alveolata, C. halli, 

Palaeophyllum stokesi, Calapoecia borealis, C. canadensis, Halysites 

gracilis, Dinorthis? sp., · Rhynchotrema capax, Catazyga cf. C. headi 

borealis, Maclurina? sp., Liospira? sp., Allumettoceras? sp., Spyroceras 

rarum, Trochonema umbilicatum. 

Receptaculites sp., Halysites gracilis, Halysites cf. H. microporus, 

Hesperorthis? sp., Resserella tersa?, Rhynchotrema increbescens?, 

tetracorals indet. 

Calapoecia sp., Streptelasma sp., Receptaculites sp., Halysites sp_------- Catazyga sp., abundant crinoid stems ______________________________ _ 

B25 

References 

R. J. Ross, Jr., to J. F. 

Murphy (written com- mun., 1955). 

J. W. Huddle to J. F. 

Murphy (written com- mun., 1963); Eliot 

Blackwelder (U.S. 

Geol. Survey, unpub. 

field notes) ; identification by E. 0. Ulrich. 

Murphy and others 

(1956); J. W. Huddle 

to J. F. Murphy 

(written commun., 

1963). 

Miller (1932, p. 204-206). 

Miller (1932, p. 206, 207). 

Bell (1955). 

Love (1939, p. 20); 

Keefer (1957; p. 167). 

quent investigations of North American Ordovician 

cephalopods by Flower (1946, 1952) have shown that 

forms typical of the Bighorn occur both in rocks of the 

Upper Ordovician Series in southern Ohio and northern 

Kentucky and in beds of definite late Middle Ordovician 

age in New York and Ontario. 

Reporting on more recent fossil discoveries ·at severa] 

horizons within the Bighorn Dolomite in the southeastern Bighorn Mountains, Hose (1955, p. 45-48, 111, 112) 

concluded, from identifications by Josiah Bridge, that 

the upper part of the basal sandstone (Lander Sandstone Member) is Middle Ordovician and the upper two 

members of the formation are Late Ordovician. Ross 

(1957b, p. 468) considered the fossil-rich red-weathering zone at the top of the formation in the central Bighorn Mountains to be Late Ordovician. Wanless and 

others (1955, p. 15, 16) expressed the opinion, based on 

the presence of favositid corals, that the Leigh Dolomite 

Member in the Teton Range might possibly be of Silurian age, though corals of this type are also known in 

some places from Upper Ordovician rocks. 

Furthermore, in Ross' opinion ( 1957b, p. 463) "the 

paleontologic evidence for the Late Ordovician age of 

the [Lander Sandstone Member] is still impressive." 

Duncan ( 1956, p. 220) stated "General investigations of 

American Ordovician corals have led the writer to believe that the relatively diversified and advanced fauna 

in the lower part of the Bighorn dolomite and equivalent strata must be indicative of Lat&----pDobably early 

Late-Ordovician age." 

From the evidence at hand it seems likely that at 

least the upper part of the Bighorn is Late Ordovician. 

Conditions of Deposition 

The Ordovician sea first invaded central Wyoming 

in Middle Ordovician time and deposited sandstone 

equivalent to the Harding Sandstone in a shore and 

near-shore marine environment. The original distribution of this sandstone is not known, but Ross (1957a., p. 

18) suggested the possibility that the Harding equivalent was deposited across at least part of the Wind 

River Basin, south and west of its present area of outcrop, and that it was completely removed by later erosion and reworking into the next younger Lander Sandstone Member. Ross (1957a, p. 17) also pointed out, on 

the other hand, that the irregular occurrence of the 

Harding Sandstone equivalent may be due as much to 
B26 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

irregular original deposition as to any subsequent 

events. After the deposition of the Harding Sandstone equivalent, the region seems to have been raised 

above the level of the sea again and to have eroded until 

later Middle Ordovician time or until Late Ordovician 

time depending on the age that is assigned to the Lander 

Sandstone Member. 

The deposition of the Lander Sandstone Member 

marked the beginning of widespread marine sedimentation in central Wyoming. Miller (1930, p. 213) 

concluded from faunal evidence that a shallow sea 

transgressed from the Arctic southeastward into the region. The source of the sand is not known. It is known 

however, that clastic rocks of Cambrian age were exposed in some parts of the region during the transgression of the Ordovician sea. The nearest such area, 

along the present southeast margin of the Wind River 

Basin, could have contributed some of the clastic debris 

in the Lander Sandstone Member. The evidence is inconclusive, however, be.cause much of the record was 

destroyed by pre-Mississippian erosion. No conclusions 

can be drawn regarding the irregular distribution and 

thinness of the Lander; there is no evidence of erosion 

or reworking of the sands before the carbonate sediments were deposited over them. On the contrary, the 

contact between the Lander Sandstone Member and the 

overlying massive dolomite appears to be conformable, 

and, in many places, gradational (Ross, 1957b, p. 462). 

The thick carbonate sequence that forms the main 

body of the Bighorn Dolomite was probably deposited 

in a warm shallow sea, but far enough from shore so 

that very little clastic debris was carried into the main 

area of accumulation. The factors influencing sedimentation must have been constant for a long time, because 

the strata over large areas are so uniform in composition, color, and texture. Little is yet known, however, 

about the time or mode of dolomitization. Blackwelder 

( 1913) was the first to consider this problem in detail; 

Ross (1957a) summarized some of the more current 

views on the subject. Both investigators conclude that 

the material was deposited originally as calcium carbonate; but, whereas Blackwelder (1913, p. 621, 622) believed that the limestone was dolomitized before lithification, Ross (1957a, p.19) considered it more likely that 

dolomitization took place after lithification had begun. 

According to Robinson (1963, p. 23, 24), the possibility 

that dolomite was deposited directly from sea water 

should not be dismissed, even though dolomite is not 

being deposited in quantity in modern open seas. 

The peculiar branching structures that are so characteristic of exposed surfaces of the Bighorn Dolomite 

(fig. 10) are clearly the result of differential weathering 

related to variations in the physical and (or) chemical 

composition of the dolomite. Darton ( 1906c) believed 

that the raised parts of the network are siliceous and 

hence less easily weathered than the surrounding dolomite. Blackwelder ( 1913, p. 615, 624) pointed out that 

the rock contains very little silica and concluded that 

the network is more likely the result of differential 

weathering of compact fine-grained (more resistant) 

dolomite embedded in a matrix of more coarsely crystalline and more porous (less resistant) dolomite. He 

(Blackwelder, 1913, p. 624) further concluded that the 

branching structures are of organic origin, possibly calcareous algae whose original organic structures were 

obliterated in the process of dolomitization. Ross 

(1957a, p. 18) cited evidence, on the other hand, that 

the structures could not have been secreted by algae 

above the ocean floor and suggested that the raised parts 

of the network were either minute solution channels or 

passages of burrowing organisms filled by carbonate 

mud. 

The presence of the small pebbles of· igneous and 

metasedimentary rocks in the basal part of the middle 

massive dolomite member in Dinwoody Canyon is enigmatic; so far as is known this is their only occurrence, 

but they could have been easily overlooked in other outcrops. The pebbles, though somewhat rounded, show 

little sign of having been extensively weathered before 

reaching their ultimate depositional site (J. F. Murphy, 

oral commun., 1963), indicating, perhaps, that transport had not been for any great distance. There is no 

evidence, however, to suggest that any part of the Wind 

River Range was emergent and being eroded during 

deposition of the Bighorn. Some parts of the Granite 

Mountains might possibly have been eroded to the 

Precambrian at this time, but these mountains lie 75 

miles southeast of Din woody Canyon (pl. 1). 

Much additional study is needed before more reliable 

conclusions can be made regarding the origin of the 

Bighorn Dolomite. 

At the close of Ordovician time the sea withdrew 

from central Wyoming and a period of erosion ensued, 

possibly lasting through all of the Silurian Period and 

part of the Devonian Period. 

DEVONIAN ROCKS, DARBY FORMATION 

Definition 

The name Darby Formation was applied by Blackwelder (1918) to a variable sequence of dolomite and 

shale lying between the Madison Limestone and Bighorn 

Dolomite in northwestern Wyoming. Blackwelder 

(p. 420) derived the term from the canyon of Darby 

Creek on the west slope of the Teton Range, but he gave 

a 1neasured section from Sheep Mountain on the west 

slope of the Wind River Range (about 20 miles south of 
PALEOZOIC FORMATIONS B27 

the Warm Spring Creek loc., pl. 1) as the type. He 

considered the Darby to be Devonian and equivalent to 

the Three Forks Shale and the upper part of the Jefferson Limestone in southwestern Montana as described 

by Peale (1893, p. 27-32). 

In the Wind River Basin the Darby Formation, as 

mapped, likewise includes all strata lying between the 

Bighorn Dolomite and Madison Limestone. Regional 

stratigraphic studies by Andrichuk (1951), Sandberg 

(1963, oral commun., 1964), and Sandberg and McMannis (1964) have shown, however, that this sequence 

is very complex, and that it includes strata correlative 

with the Beartooth Butte Formation of Early Devonian 

age, the Maywood and Jefferson Formations of Late 

Devonian age, and a dark shale unit of latest Devonian 

.and earliest Mississippian age. 

Strata assigned to the Darby Formation have the 

most limited distribution of any of the Paleozoic units 

in the Wind River Basin, being restricted to the flanks 

of the northern and central Wind River Range, the 

Washakie Range, and western half of the Ow 1 Creek 

Mountains (fig. 12). 

Lithology and Thickness 

The Darby Formation is 193 feet thick at the northwestern end of the Wind River Range, but thins progressively southeastward to a wedge edge near Sinks Canyon 

(pl. 2). Except in canyon walls, these rocks are poorly 

exposed, commonly forming topographic saddles or 

benches between the resistant Madison Limestone and 

Bighorn Dolomite. Where well exposed, however, they 

form a very distinctive unit because of their contrast 

in color and in bedding characteristics with both the 

overlying and underlying strata. 

In the northwestern Wind River Range the Darby 

consists chiefly of resistant buff, gray, and brown thinto thick-bedded ledgy dolomite in the lower part and 

greenish-gray and red soft siltstone, shale, and sandstone interbedded with white, pink, and brown 

limestone and dolomite in the upper part. The most 

characteristic beds are dark-brown granular dolomite 

which emits a strong petroleumlike odor when freshly 

broken; hence, the term "fetid" is commonly applied to 

them. The granular texture of some beds is so conspicuous that they are often mistaken for sandstone. The 

dolomites are readily distinguished from the carbonate 

rocks in the Bighorn Dolomite below and the Madison 

Limestone above, although some of the lower beds of 

the Madison are superficially similar in places. The 

sandstone of the Darby is fine to coarse grained and 

commonly contains abundant large rounded frosted 

grains. Such grains are also scattered through some of 

the dolomite beds. 

The Darby Formation, as mapped in exposures extending southeast from Warm Spring Creek to Bull 

Lake, ineludes at the top 5-30 feet of thin-bedded siltstone, shale, and silty dolomite. According to Sandberg 

( 1963), this unit is in part equivalent to a dark shale 

unit of latest Devonian and earliest Mississippian age 

that is widespread in northern Wyoming and southern 

Montana and that overlies all older Devonian strata 

with marked regional unconformity. In parts of Montana these strata were assigned to the basal beds of the 

Madison Limestone (Sloss, 1952, p. 66) rather than to 

the underlying Three Forks Shale. 

In the Bull Lake Canyon and Dinwoody Canyon 

areas Murphy and others (1956) reported local channels 

of sandy to conglomeratic siltstone and dolomite at the 

base of the Darby that have cut into underlying Bighorn Dolomite. Some of the channels contain Early 

Devonian fossils and represent the Beartooth Butte 

Formation, whereas others contain early Late Devonian 

fossils and correlate with the Maywood Formation 

(C. A. Sandberg, oral commun., 1964) . The large 

masses of breccia at the top of the Bighorn Dolomite at 

the Warm Spring Creek locality (see discussion above) 

may also represent either one or both of these formations, but no fossils have been collected. 

The Darby Formation has been traced southeast 

along the east flank of the Wind River Range as far as 

Sinks Canyon (pl. 2), where about 20 feet of tan 

crystalline dolomite imbedded with large fragments of 

white medium- to coarse-grained quartzitic sandstone 

was reported by Strickland (1957, p. 27). Sections 

along the north edge of the Wind River Basin are similar to those in the Wind River Range; the sequence 

becomes more sandy and finally wedges out in the central Owl Creek Mountains (pl. 3). Strickland (1957, 

p. 25) noted that toward the limits of its distribution, 

the lower part of the sequence seems to be overlapped by 

the upper part. Correlation of the upper stra~as 

seen in sections near the wedge edges-with the dark 

shale unit of the northwestern Wind River Range is yet 

to be determined. Maughan (1963, p. C26) discussed 

the possibility, however, that clastic rocks assigned to 

the basal part of the Madison Limestone in the northern 

Laramie Mountains are in part equivalent to the dark 

shale unit. 

Contact With the Madison Limestone 

The dark shale unit seems to be transitional with the 

basal beds of the Madison Limestone in outcrops extending from Bull Lake Canyon northwest to Warm 

Spring Creek (C. A. Sandberg, oral commun., 1964) . 

Farther east and south, where the dark shale unit is 

absent or poorly developed, an erosional unconformity 

may separate the Madison and Darby Formations, but 
106° 

~10o ,.. 109° 10so 10r 44° 

I~ 0 p A~ R K - I T I I 

I

I ~~c:' .1'./'"'\0j.._ I I w 46 A s H A K I E I _! 

r-:·~ ~ / I \ - I N I ....:l 

I 4 ~ ) ' I I ....:l I • - I I '- I 45 I . 81 80 79 78 R 77W ijiC .11_09 ~Hl8 "110 106 105 10-i, 103 _ lb.2 101 100 99 98 97 96 gs 91 .)l3 92 91 90 89 88 87 R6 85 84 8 3 82 1'<1 

If '~ 144 l I I 

!, 1 44--- - f-- ---..J ~ rt-- ......... H 0 T ~ p R I N G s I ; l P=l 

,, -,..c.H~ ·~ -· ...... I • --f- T I I p.. ~~ 43 I / ~"- ~....... Oc~- ~ :..- . !'-- o. 43 I I J o H N s o N l ~ jJ\ 'lrl' ( I ~ '- /~ - lTheril)Jpohs I • , 

~I [), V' X -.....; 8 I I I t < TjETojNI\ !4"- ~ ( \ ( r-7<-7!::"':' ~ I. /j" 4 

I ~~~ ' \ jD .L Y 1 I 41 ~ ......_ ) Dub Js~ \ 6 - --- I ~ I 

,/ ~~- ~--

-- _ ! " ! ~,\ I , / /) I =-: . . . . . . . . . . . . . . . 1 -l I ~' '\{6 5 4_ ~ 2 R I W R 1 E1 2 3 4 5 6} 

I ~ \ I k \ 4/ l 3 I X ~ '\\:~ )( I I 

3

1 ( "\ I ,. 3 

- \ I~~ /3 I 

3 7 '\ : '\~'\.X • I 2 I 3 I I I I I I 1 I ' II l I t t I --'r-'r" 

(:]111 

~ \ ,'\ I I I· I I I I '\II I I I I I I 1

00 

~ ~ II~-, 1 • 1, n· 

3 I I I ; I I I I _N l I I I I t l .wM 3 ~-~ '1.. •• N \ or. I vert< n 13 -f- ' ... ~. \ k .,.f r--- __ 34 1 ,J ~ 'Y" / s I 3 

A { ... 43° 

I 

n

Pmedale '~~-- ~\~ ... -z.rf\ _/ -~ -~ ~- ~ I [ l 1 l 1 I I l'\ 33 

~~ \ \~ 1, [aLan er l I I 33 I I I i I I I l l 1" 

I (;.\. I \ I " 

~ \ 32 I 'i, I I I l 

I s 131 U / B I L I E I T I T I E ~ '\ 1 ,' ~ -r- -,~- -- -,-... t-- / 

11 / ~ 6--..=f-. 

~ 10 

~ l 1: 

I II r[ 

l 

I 

I 

I 

rI 

+ 

32 

°Casper 

I 

""' 

r TT- q-"~f-I--~-[1_~~l~_I_I~fo IIi -r I I I II lBout~r:r~~:a~~~~i~iver 

'· l -LLJJ--LLLlTJ r-~--1---

30 

I 

L F R E Ml 0 N T I '>< 

EXPLANATION 

X 

Surface section 

~z 

~---~--+--+---1--+--t-·-+--+--ll---1--+---+- ! I I I I I I l I I I I I I I I~ 

27 

0 

I 

• 

Subsurface section 

10 20 

i 

II Sl w IE 

lwkiL.mJ I too j _99 

30 MILES 1 

26 c A R 

A II Tlzs E l R I 94 ~ 93 I 92 I 91 I !tO L 89 I 88 I 87 I 86 I 815 I 84 t 83 

Ej T IW 98 97 l 96 95 I II 1

2

:

4 1 1 l I I l -ll 1 T 

IP=l 

~ Rhw 

I 

I 

B N 

82 I 81 7R 

n 

0 

80 79 

T 142° 

FIGURE 12.-Thickness map of Darby Formation in central Wyoming. Based in part on C. A. Sandberg (written commun., 1963). Interval is 100 feet; isopachs are restored 

across mountain arches where rocks have been eroded; isopachs are dashed where control is inadequate. 

to 

~ 

(YJ 

~ 

1?:1 

0 

t"' 

8 

~ 

0 

"':! 

~ 

~ 

z 

t:;:j 

P:l 

~ 1?:1 

P:l 

t::d 

> w 

,.z 

~ 

~ P:l 

> t"' 

~ ~ 

0 

e 

z 

~ 
PALEOZOIC FORMATIONS B29 

in most places observations have bee too inadequate 

to determine the nature of the contact i detail. 

Age 

Fish remains have been found inch nellike deposits 

at the base of the Darby Formatio and associated 

strata in Bull Lake Canyon and near y sections along 

the east flank of the Wind River Rang (table 4; Denison, 1951, p. 234). These fossils indicate that the lowermost channels are Early Devonian in age, whereas the 

next overlying ones are early Late Devonian (Sandberg 

and McMannis, 1964; C. A. Sandberg, oral commun., 

1964). Conodonts from the dark shale unit in Dinwoody and Bull Lake Canyons are latest Devonian 

(table 4; Klapper, 1958, p. 1083) and t ose from Warm 

Spring Lake are earliest Mississippi (C. A. Sandberg, oral commun., 1964). Most of t e rocks assigned 

~o the Darby Formation are, therefor, Late Devonian 

In age. 

Conditions of Deposition 

No positive record that rocks of Silurian age were deposited in the Wind River Basin area has been found. 

However, Silurian strata have been recognized in the 

northern part of the Powder River Basin (C. A. Sandberg, oral commun., 1963) and also in !isolated patches 

in southeastern Wyoming (Chronic anld Ferris, 1961) ; 

thus, Silurian seas may have covered rt least parts of 

central Wyoming. 

The region was emergent during m4 st of Early and 

Middle Devonian time, although PJ.inor flooding 

occurred in at least the western part of the Wind River 

Basin area during the early part of the I eriod. In early 

Late Devonian time the sea advance~ eastward, and 

perhaps southward, into the region, rst filling only 

narrow channelways but later covering all the land surface. However, the sea at this time probably did not 

extend much beyond the present kno1lrn limits of the 

Darby Formation (jig. 12). Thomati (1948, p. 84) 

concluded, from the abundance of fro ted sand grains 

in the formation in sections near the 11ledge edge, that 

the Darby in central Wyoming was deposited fairly 

close to shore and that the sand was blown into the sea. 

Presumably, therefore, a broad landmass extended 

across the eastern half of the Wind River Basin area 

during this part of Late Devonian time. 

The sea withdrew from central Wyoming before the 

end of Devonian time, and a period of intense erosion 

followed. Thus, much of the erosion commonly attrib--

uted to the period immediately preceding the deposition of the Madison Limestone may have occurred 

instead before the end of the Devonian. In latest Devonian and earliest Mississippian time, the sea 

readvanced and the dark shale unit was laid down 

across the truncated edges of rocks ranging in age from 

Late Devonian in western and northern Wyoming 

(Sando and Dutro, 1960, p. 123; Sandberg, 1963, p. 

C19) to Precambrian in east-central Wyoming (C. A. 

Sandberg, oral commun., 1963). Sedimentation seems 

to have been continuous into Madison time in at least 

the western part of the Wind River Basin area, but the 

sea may have withdrawn from the central and eastern 

parts for a short interval before Madison deposition. 

MISSISSIPPIAN ROCKS, MADISON LIMESTONE 

Definition 

The Madison Limestone was named and described by 

Peale ( 1893, p 32) for the Madison Range in the Three 

Forks region of southwestern Montana. The age of the 

formation in the type area was designated as "Lower 

Carboniferous." In southeastern Idaho, Mansfield 

(1927, p. 60-71) subdivided the Mississippian rocks into 

the Madison Limestone at the base and the Brazer Limestone (named earlier by Richardson, 1913) at the top; 

the ages were considered to be Early Mississippian and 

Late Mississippian, respectively. 

The name Madision has long been used to designate 

all the rocks of Mississippian age in central Wyoming 

(Darton, 1906a, b; Blackwelder, 1918). However, as 

early as 1918 Branson and Greger (1918) described fos1 ~BLE 4.-Fossils from the Darby Formation 

Stratigraphic section 

Dinwoody Canyon ___ _ 

Bull Lake Canyon ___ _ 

Collection 

No. 

(pls. 

2-5) 

6 

2 

3 

[Generic and pecific names are quoted without modification from sources shown] 

Species References 

Fish remains_ -------------------------------------------------- J. F. Murphy (U.S. Geol. 

survey, unpub. field 

Bothriolepis pate~; teeth _and scales of unidentifiable crossopterygians __ 

Apatogr:athu~ ~anans, Htndeoqellr: cf. H. acuta, Icriodus darbyensis, I. 

mehlt, ~Crt4 dU;s sp., Jt!eopnonwdus sp., Ozarkodina regularis, Palmatolepts g nt?clymem_ae, P. rug?sa, Polygnathus inornata, P. nodocostata, P. trwngulans, P. vannodosa, P. wyomingensis Spathognathodus ac ~leatus, S. jugosus. ' 

notes). 

Do. 

Klapper (1958). 
B30 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

sils of Late Mississippian age from the upper part of the 

formation in Bull Lake Canyon. The lower approximately 50 feet of this sequence, bearing what was considered to be a Ste. Genevieve fauna, was named the 

Sacajawea Formation, and the overlying beds, believed 

to be of possible Chester age, were included in the 

Amsden Formation by C. C. Branson (1937; see fig.13). 

More recently other geologists have attempted to subdivide the Mississippian sequence in the Wind River 

Basin area; the various classifications, many of which 

follow the terminology established in central Montana 

(Collier and Cathcart, 1922, p. 173; Sloss, 1952; Easton, 

1962) are shown on figure 13. 

None of the proposed classifications, however, has 

been demonstrated to be wholly satisfactory for geologic mapping; many are based on lithologic and (or) 

paleontologic differences that may be easily recognized 

locally but not regionally. Denson and Morrissey 

( 1952), for example, separated the Madison on the 

basis of insoluble residues, but stated (p. 40) ·that "Divisions of the Madison formations are frequently recognized only with difficul•ty in the field." Therefore, in 

this report all Mississippian rocks above the dark shale 

unit of the Darby Formation and below the Amsden 

Formation are included in the Madison Limestone because they constitute a natural lithologic unit for geologic mapping. For convenience in stratigraphic and 

paleontologic discussion, however, the formation has 

been divided into upper and lower members. 

In the summer of 1964, W. J. Sando collected fossils 

and studied the stratigraphy of the Mississippian rocks 

at several localities along the east flank of the Wind 

River Range. The preliminary results of his work 

were made available to us during the final stages of 

preparation of the present report (W. J. Sando, written commun., 1965) . 

Lithology and Thickness 

The Madison Limestone includes 600-700 feet of resistant cliff-forming carbonate strata in the central and 

northern Wind River Range and adjacent parts of the 

W~ashakie Range. The lower member, 500-600 feet 

thick, consists mainly of bluish-gray to gray massive to 

thin-bedded crystalline limestone and dolomitic limestone. The limestone is mottled by inclusions of tan 

granular limestone or dolomite similar to those in the 

Gallatin Limestone and the Death Canyon Limestone 

Member of the Gros Ventre Formation. At most localities the basal part contains thin beds of buff granular dolomitic limestone similar to some of the beds in 

the upper part of the Darby Formation. The lower 

strata also contain masses of breccia consisting of angular limestone fragments in a red earthy matrix ; 

weathering and erosion of the breccia causes conspicuous 

red staining on many outcrops. Massive to bedded 

chert layers as much as 15 feet thick are present at 

several localities, and chert nodules are abundant 

throughout. Caverns are common in the limestone, 

especially in the more granular beds. 

The upper member of the Madison Limestone, about 

100 feet thick, is chiefly thin to massive and irregularly 

bedded gray, tan, and yellowish-tan dolomite and limestone. Thin beds of red shale and siltstone are locally 

present. The carbonate rocks in some zones are highly 

fractured, brecciated, and cavernous and contain much 

red cla;stic material. Conspicuous disconformities also 

occur at a few horizons. 

The limestone and dolomite vary in lithology and 

texture; these rocks have been described in some detail 

by Andrichuk ( 1955) and Flanagan ( 1962) . 

Thickness of the Mississippian sequence ranges from 

235 to 535 feet in the southern Wind River Range (pl. 2) 

and from 335 to 635 feet in the Owl Creek and southern 

Bighorn Mountains (pl. 3). Along the south edge of 

the Wind River Basin the thickness is 175-400 feet, along 

the east edge it is 245-275 feet (pis. 4, ·5). Madison 

strata generally thin from northwest to southeast across 

central Wyoming (fig.14). 

Lithologies similar to those described above characterize the Madison Limestone in other areas around the 

Wind River Basin. The lower member is everywhere 

present, although Denson and Morrissey (1952, figs. 7, 

8) indicated that the basal part (their Lodgepole Formation) is absent 1along the south margin. Tourtelot 

and Thompson ( 1948) observed lenses of sandstone at 

the hase of the lower member in the Wind River Canyon 

area and, at the southeast edge of the basin, Jenkins 

( 1950) included about 60 feet of quartzitic sandstone 

and conglomerate at the base. As noted above, these 

clastic rocks, as well as those that have been assigned to 

the underlying Flathead Sandstone, are all included 

by Maughan ( 1963, p. C26) in the basal part of the 

Madison Limestone in the northern Laramie Mountains. 

The distribution of the upper member of the Madison 

Limestone is more restricted than that of the lower 

member, owing to post-Madison erosion; its exact limits 

have not yet been worked out in detail. Denson and 

Morrissey (1952, fig. 4) showed the upper member to be 

present in the Wind River Canyon area, whereas Andrichuk ('1955, fig. 5) and Sando (written commun., 1965) 

do not extend it that far east in the Owl Creek Mountains. Correlation in the southern Wind River Range 

is also in doubt, but the unit may extend as far southeast 

as Sinks Canyon, or beyond. East of ~Sweetwater Canyon, however, the Amsden Formation seems to rest directly on the lower member of the Madison, and the 

upper member is absent. 
. I I Branson and Th1s report Branson (1937) _E3ranson (1 9412 

Tensleep 

Sandstone 

Upper 

........ ·::· 

Ten sleep 

Sandstone 

Ten sleep 

Sandstone 

g part c 

0 

~ 

ro 

Ten sleep 

~ Sandstone ro 

E 

0 

LL. 

c 

Q) 

"0 

(/) 

E 

<( 

Q) 

c 

.s 

(/) 

Q) 

E 

:.J 

c 

0 

.!!! 

"0 

ro 

::?! 

Darwin 

Sandstone 

Member 

Upper 

member 

Lower 

member 

1:·;:::;:::.::::. 

92ft [.:·."<·:-:·· .. ·: 

E 

0 

LL. 

c 

Q) 

"0 

(/) 

E 

<( 

Darwin 

Sandstone 

Member 

Brazer(?) 

96ft~ Limestone 

equivalent 

580 ft ~~ Madison Limestone 

c 

0 

~ I Upper E Amsden 

0 

LL. 

c 

Q) 

"0 

(/) 

E 

<( 

Lower Amsden 

(Beds of Beds of 

possible Chester(?) age 

Chester age) 

Sacajawea Sacajawea 

Formation Formation 

Madison Limestone I Madison Limestone 

• 

1

! Denson and 1 ~ . I l Stnckland (1957~~'1D'is~ey 0952)~nd nch u k (1955) Flanagan (1962) 

0. 

:::l 

0 

(5 

c 

0 

.!!! 

"0 

ro 

::?! 

(Not studied) 

.!!! §I Sacajawea . ~ Member 

::?! 

.... 

Q) 

0. 

0. 

=>t--------1 

(Unnamed 

part) 

ID I Lodgepole 

~ and Miss ion 

...J Canyon 

0. 

:::l 

0 

(5 

c 

0 

(/) 

:0 

ro 

::?! 

(Not studied) 

"Upper" 

Madison 0. 

:::l 

0 

(5 

c 

0 

.!!! 

"0 

ro 

Mission Canyon! ::?! 

and 

Lodgepole 

Formations 

(Not studied) 

Upper 

unit 

Middle and 

lower units 

(Not studied) 

"Upper" 

Madison 

"Middle" and 

"lower" Madison 

FIGURE 13.~Nomenclature of Carboniferous strata, east flank of Wind River Range. Section shown is from Bull Lake Canyon. 

~ 

~ 0 

~ 1-4 

Q 

6 

~ 

~ 

1-4 

~ 

0 

~ 

to 

~ 

1-' 
~10° 109° 108° 107° 

T p A R K - ===F=Z="-, T I 

106 

I

I ~~-~ .!'-',./)...('\ - I I w 46 A s H A K I E I ., 44° 

I 

I 

~~ ~ 

'llr.::l 

C:J - <.. ~ 1\,J'\~ _u I N 

I 45 3 ! \. fO'i . 45 I I I "' I" '" ''" 115} ,,/ '" .o> '"~ ,,, "' ,

00 , " , " <,;;- " ,, ' , , 00 ., " " " ; ., " I " I " I " eo '" I ~4---f---r--IT ~ ,...,. i' ( H 0 T s p R I N G s f.>Ot 144 I 

i_-- ti- V\ • • / / - - j il&:Ci 

~ 43 ·:;;Z~ '~- _., - ~ •v '"-._.~,_ r \ I J o H N s o N ; Po< 

_;\ X \ ~ "- 1->. 1/_lf'x. e \ "'-rfperm poliill • _jt le J I - . ::S 

T/"T1N I ::.., '" '~c 1x '--ccrcr-r---- x "'--r .A0' " "!'--. ! -c 1 > 1 ~ T 1 I ~ " ~ . · t'-. 1\ ~ '""- xr ;~ I I I 41 '"' ....:J( -2t_ ""'t\.\ 6 S:- ~. I 41v ,I _,.__ 1- ·- ·~ -t--- -------- ---~j_;.. \'" I 11 t r·, f' '' ~ Otj:_'~-:-::-- r- 1- ~-=-- R '-=:t:: A I 

I 4o I '\, X 1 '\. . -- ~ 1 4o I "' } J. 1 1 

I \ ~ \ 5 I ·, 

--1--r y.. \ Y6 5 4 3 'J,? R w R 1 E 2 3 4 5 6_1 • / 1 , I ~ ~ _.... li39 X J) \, \ I lA. ''\. . / 1/ 4 7 I 39 /. I '\ I 

'( ~ I ' _/ 1- / r-.... I /' T I>( I ( '1\ v1- J7 ' 7 ,l 38 ~~ _L r---1 \ 1\ 3 / I 11 11 37 j 1 'I /'~ \ x v I r/ l 37/ i I I \ T£ 

I ... I \· \ t //'2 c / I / V 1 l 1 1 I. 

136 

~ /'' I \ \ v T ~ I II 36 ! . { \ / \ ~~ ,.,.0 ~-~I j ·\ N. ,- ~Eivert<n 135 1 \ ~ / 

1 ·'(~~ 'r----~ ~ . I I N ....... ~ r1.. 0 I N 1 J T34 ] ~\ Is:\ \ Ia 1 r ~, ~Pinedale \ \f/~~Z.,.~ ./ -t-;- -1-'1- ·- 34 ; '. 

,~ r ] ~.:~~f ,y 1\ h•n ~ y I ., " ~ )< - •t.V , ~~Q:)','; r ~'~r, w y \< , r v-v- 1'-.:.::, N 

liJ'uT B L E r T T 1 E i _ \ \ _y ~ • ,,iJ'-- ~~-/ -r-,_,_~~Jk 

~ 

1: 

R I 

X i I 

L-1

30 

I I I I I AJo~ fl\ I~\ I I /1 ~ \*0 I r 17! ! ! ! L~/ !~:1 L~} 

43° 

I 

I EXPLANATION rI 

-+ II>-< 

rz 

I~ 

IP=I 

~ IR J7W 

I 

I 1420 

X 

E I T lw I A II Tl25 E I R ~ I 'I I r ll X I luo 98 97 I 96 95 I 94 ~ 93 92 I 91 90 ~~A 87 86 8 84 83 82 I 81 I 80 I 79 I 78 

i LJ:1~1~r·~:r+i~-J~+~1 m II ([I B I I 0 I IN I i Surface section 

• 

Subsurface section Sj W IE 

IRib.ll.l 101 1100 I 99 

0 10 20 30 MILES 

r I ! II 12:

4 1 1 I i I l I II I I I FIGURE 14.-Thickness map of Madison Limestone in central Wyoming. Interval is 100 ft; isopachs are restored across mountain arches where rocks have been eroded; isopachs are 

dashed where control is inadequate. 

o; 

~ 

t_..:) 

~ 0 

b 

~ 

0 

l'%j 

~ t:rJ 

:a 

z 

t::1 

~ 

~ l"'.l 

~ 

td 

> 

~~ 

Q 

2: 

8 

~ 

:a 

t-<1 

0 

~ 1-4 

~ 
PALEOZOIC FORMATIONS B33 

Ba.sal Unconformity 

The unconformity at the base of the Madison Lime.-

stone is one of the most prominent in central Wyoming; 

however, as stated above, much of the truncation may 

have taken place in latest Devonian time, before the 

deposition of the dark shale unit of the Darby Formation. The general distribution of various formations 

that directly underlie the Madison across the region is 

shown on figure 15. In the western part of the Wind 

River Basin the formation overlies the Darby Forma6on with apparent conformity, but eastward it rests on 

successively older beds and, in the southeast part of the 

basin, directly overlies the Cambrian Flathead Sandstone. The contact shows several feet of relief in many 

places, and basal strata of the l\tiadison commonly contain sandstone and siltstone in which fragments reworked from the underlying formations are incorporated. In the Bates Creek section (pis. 4, 5) the basal 

quartzitic unit was probably derived principally from 

the Flathead Sandstone. 

Contact With the Amsden Formation 

The Madison Limestone is separated from the overlying Amsden Formation by a conspicuous erosional 

unconformity. The basal strata of the Amsden, generally sandstone, were deposited on a very irregular surface that shows several feet of local relief. The sandstone commonly fills cracks which extend down ward 

into the underlying limestone. The sharp lithologic 

change between the Madison and Amsden Formations 

is readily recognized in most outcrops, and the contact 

is also easily identified on electric logs (pl. 6). 

Age 

The Madison Limestone is sparsely to abundantly 

fossiliferous in many zones (table 5). Recent paleontologic studies by Sando (written commun., 1965) indicate that the lower member is largely late Early Mississippian (late Osage) in age, and that the upper 

member is early Late Mississippian (early Meramec) 

in age; thus, the bulk of the formation seems to correlate with the Mission Canyon Limestone of southwestern Montana. Basal strata of the lower member may 

be equivalent in part to the Lodgepole Limestone 

(I{inderhook and early Osage); as noted previously, 

C. A. Sandberg (oral commun., 1964) has observed evidence that the contact between the Madison and Darby 

Formations is transitional in places. Sando found no 

fossils to indicate that any of the rocks here assigned 

to the Madison are as young as latest Mississippian 

(Chester), as had been suggested by Branson (1937). 

Conditions of Deposition 

In Early Mississippian time the sea may have withdrawn from all but the western third of the Wind River 

Basin area; strata as old as the Flathead Sandstone 

were exposed to erosion in the southeastern part. The 

sea advanced from the north and northwest at the 

beginning of Madison deposition, and a thick succession 

of carbonate sediments were laid down across the entire 

TABLE 5.-Fossils from the Madison Limestone 

[Generic and specific names are quoted without modification from sources shown] 

--

Collection 

Stratigraphic section No. Species References 

(pls. 

2-5) 

Din woody Canyon ____ 7 Syringopora sp _______________ - _ -- - _ -- -- -- -- -- -- -- -- -- ----- --- -;- - Thomas (1948, fig. 3). 

Bull Lake Canyon ____ 4 Zaphrentis amsdenensis, Spir~fer pella~nsis, S. shoshone.n~is,. Compos'df! Branson and Greger 

trimtclea, Eumetria marcyt, Pugnmdes ottumwa, Sptnfenna brownt, (1918,p.312);~urphy 

Orthotetes kaskaskiensis, Chonetes chesterensis, Tetracamera subcuneata, and others (1956); 

Phillipsia sp.? Homalophyllites?, Caninophyllum?, Lithostrotion?, Helen Duncan (written 

Diphyphyllum?. . commun., 1954). Sinks Canyon ________ 4 Triplophyllites sp., Cyathophyllum sp., Syringopora sp., Dtphyphyllum Biggs, C. A. (1951). 

sp., Barbouria sp. Beaver Creek ________ 1 Spirifer cf. S. madisonensis ________________________ - _--- _--------- Shaw (1955, p. 63). 

Sweetwater Canyon ___ 10 Syringopora surcularia, Spirifer sp __________________ - _------------- Bell (1955). 

11 Spirifer madisonensis?, S. centronat1ts, "Orthotetes" sp. indet_ ___ - ____ - Do. 

Windy Gap __________ 4 Lithostrotion? sp., Syringopora sp., Diphyphyllum?, Spirifer striatus var. Love (1939, p. 26); 

madisonensis, Spirifer cf. S. increbescens, S. sp., Composita sp. indet., Keefer (1957, p. 169). 

crinoid columnals, fenestellid bryozoans. Conant Creek ________ 4 Spirifer centronatus? _________________________________ - __ --------- V. L. White (U.S. Geol. 

Survey, unpub. field 

notes). Alcova ______________ 1 Camarotoechia aff. C. sappho, C. sp., Spirifer aff. S. keokuk, Spiriferina 

solidirostris?, Cleiothyridina crassicardinalis. 

Lee (1927, p. 52). 

2 Productus parviformis, Spirifer centronatus, Spiriferina solidirostris, Do. 

Cleiothyridina crassicardinalis. 

Bates Creek _________ 1 Spirifer centronatus, Composita sp. indet_ ____________ ----- _--------- Jenkins ( 1950) . Casper Mountain _____ 1 Spirifer centronatus, Syringopora sur wlaria, Com posit a humilis- - - __ --- Lee (1927, p. 48). 
B34 GEOLOGY OF THE WIND RIVER BASIN, C'ENTRAL WYOMING 

0 10 20 MILES I 

EXPLANATION 

D 

Darby Formation 

and associated strata 

Bighorn 

-Dolomite 

D Gallatin Limestone 

. 

Gros Ventre 

~ Formation 

42° ~--------------------~--------------------~------------------~ 109° 108° 107° 106° 

FIGURE 15.-General distribution of formations underlying Madison Limestone in central Wyoming. Dashed line indicates approximate outline 

of Wind River structural basin. 

region. Variations in thickness and type of carbonate 

facies deposited at any given time or place probably 

reflect minor tectonic movements and consequent 

changes in sea level. In the eastern and southeastern 

parts of the basin, debris from the underlying rocks was 

reworked into the basal strata of the Madison, but it was 

spread only a short distance into the main basins of 

depostion to the north and west. 

Toward the end of the depositional period represented 

by the lower member of the Madison, evaporitic sediments accumulated in south-central Montana. Andrichuk (1955, p. 2198) attributed this accumulation to 

extreme shoaling conditions which hindered free circulation of marine waters. As the circulation became 

more restricted, particularly in areas of deeper water 

surrounded by shoals, the water became progressively 

more saline and eventually evaporites were precipitated. Conditions did not favor evaporite deposition 

farther south in northern and central Wyoming during 

Early Mississippian time, but shoaling across the major 

shelf area is indicated by the presence of oolitic and 

fragmental limestone and dolomite in some places 

(Andrichuk, 1955, p. 2198). 

Marine sedimentation also took place during early 

Late Mississippian time in at least the western and 

northwestern parts of the Wind River Basin area. To 

what extent the sea may have covered the eastern and 

southeastern parts of the basin during this part of the 

period is not known. If the Late Mississippian sea did 

extend into the southeastern part of this region, the 

sediments deposited were probably thin and hence 

destroyed by post-Madison pre-Amsden erosion. 

Evaporites accumulated in westernmost Wyoming 

(Sando and Dutro, 1960, p. 124; Wanless and others, 

1955, p. 28, 29) and in northern Wyoming (Andrichuk, 

1955, p. 2204) in Late Mississippian time. These 

deposits do not extend into central Wyoming, but the 

conspicuous brecciated and cavernous zones in the upper 

member of the Madison Limestone may represent evaporite beds that were leached during periods of emergence, probably in Late Mississippian time. 
PALEOZOIC FORMATIONS B35 

Definition 

PENNSYLVANIAN ROCKS 

AMSDEN FORMATION 2 

The Amsden Formation was named and described by 

Darton ( 1904, p. 396) from exposures in the northern 

part of the Bighorn Mountains; in it he included all 

the strata lying between the typical blue-gray limestone 

of the Madison and the massive crossbedded sandstone 

of the Tensleep. In the type area he described a red 

shale sequence, normally with a basal sandstone, in the 

lower part of the formation and interbedded limestone 

and sandy and cherty beds in the upper part. Darton 

( 1906a, b) traced these units throughout the Bighorn 

and Owl Creek Mountains. Blackwelder (1918) 

identified the Amsden Formation in the Gros Ventre 

Range and northern and central Wind River Range, 

and named the basal sandstone, which is thick in this 

region, the Darwin Sandstone Member from Darwin 

Peak in the Gros Ventre Range, about 25 miles southwest of the Warm Spring Creek locality (pl. 2). Darton and Blackwelder believed the formation to be 

largely Pennsylvanian, but both suggested that the 

lower· part might be Mississippian. 

Although the Amsden Formation can be recognized 

with certainty throughout most of central Wyoming, 

an anomalous situation at the southern end of the Wind 

River Range has given rise to considerable confusion 

and oontroversy regarding its age and correlation. In 

1918, Branson and Greger ( 1918) reported a Late Mississippian fauna from red ferruginous shale and sandstone overlying the Madison Limestone south of the 

canyon of the Little Popo Agie River (west edge of T. 

31 N., R. 99 W.). They (Branson and ·Greger, 1918) 

referred these beds to the Amsden Formation, but because the exposures are poor (the fossils were collected 

from slope wash) , they presented a measured section 

of the Upper Mississippian rocks (upper member of 

the Madison Limestone of this report) in Bull Lake 

Canyon as a lateral equivalent, noting (p. 310) that 

"The iron, sandstone, and shales of the [Amsden in the] 

Popo Agie region do not appear [in Bull Lake Canyon] 

and the rock is mainly dolomite and limestone." They 

failed to recognize that the prominent sandstone overlying the Upper Mississippian rocks in the Bull Lake 

area was actually the basal sandstone of the Amsden 

(Darwin) rather than the Tensleep Sandstone. This 

miscorrelation probably arose for two reasons: ( 1) the 

red shale beds are not present in Bull Lake Canyon; 

and (2) the Darwin Sandstone Member is either absent 

or poorly represented at the locality south of the Little 

2 Since the preparation of this report, W. J. Sando (written commun., 1965) has collected fossils from the Amsden Formation in the 

western Wind River Basin which indicate that the lower part is Late 

:\Iississippian in age ; see discussion of age of Amsden Formation. 

Popo Agie River, and the first massive sandstone upward in the section is the Tensleep Sandstone. 

C. C. Branson (1937) later referred the basal part of 

the Upper Mississippian sequence (bearing a Ste. Genevieve fauna.) in the Bull Lake region to the Sacajawea 

Formation and the overlying limestone of possible 

Chester age to the "lower Amsden." The "upper Amsden" (fig. 13), according to Branson, "consists of 80 

feet of sandstone [Darwin Sandstone Member] over- . 

lain by 96 feet of limestone, sandstone, and shale." Still 

later it was proposed (Branson, 1939 ; Branson and 

Branson, 1941) that the name Amsden he abandoned in 

this region, and that all strata of Pennsylvanian age be 

referred to the Tensleep Sandstone. No indication is 

given that the authors recognized the Darwin. The 

controversial nature of these proposals has fostered extensive investigation and discussion of the Amsden Fo:-

mation in central Wyoming. Details may be found In 

many published papers, including Love ( 1939, p. 23, 24; 

19·54), Thomas ( 1948, p. 86, 87), Burk ( 1954, p. 2-4), 

Andrichuk (1955, p. '2178), Shaw and Bell (1955), 

Keefer (1957, p. 172), Strickland (1957, p. 23-25), and 

Easton (1962, p. 21, 22), and in unpublished theses by 

Biggs (1951), Bell (1955), Gorman (1962), and Bearce 

(196·3). . 

The problems regarding the age and correlatiOn of 

the Amsden Formation have been compounded because 

the Darwin Sandstone Member is unfossiliferous, because it is poorly exposed in critical areas in the southern 

Wind River Range, and because it thins southward and 

cannot be identified specifically in the vicinity of Little 

Popo Agie canyon where Branson and Greger ( 19'18) 

first reported Late Mississippian fossils from the lower 

part of the Amsden. In 1955, however, Sh~w and Bell 

(19·55) trenched a section of the controversial red beds 

along Cherry Creek (sec. 19, T. 31 N., R. 99 W.), sou~h 

of the Little Popo Agie canyon, described the rocks In 

detail, and made extensive fossil collections (fig. 16). It 

is apparent from Shaw and Bell~s study t?at the controversial section about 70 feet thick, contains Pennsylvanian fossils in ;he upper part and Mississippian fossils 

in the lower part. However, they (Shaw and Bell, 

1955) believed that the Mississippian part correl~ted 

temporally with the upper member of the. Madison 

Limestone at Bull Lake, whereas Sando (written commun. 1965) interpreted the fossils from Cherry Creek 

to be 'younger than those at Bull Lake. (See di~ussion below of age relations within Amsden Formation.) 

Lithology and Thickness 

In the northwestern Wind River Range and adjacent 

Washakie Range the Amsden Formation ranges in 

thickness from 210 to 355 feet. The Darwin Sandstone 

Member at the base consists of cliff-forming red, gray, 
B36 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

Composita trinuclea, Composita sp., Linoproductus sp. ident., 

Spirijer opimus 

Composita ovata, Composita subtilita, Composita trinuclea, Composita sp. ident.,Eumetria sp. ident., Spirijer opimus, Spirijer 

sp. ident., Wellerella sp. ident. 

Composita trinuclea, Composita sp. ident., Dictyoclostus sp. ident., 

Eumetria sulcata, Linoproductus sp. ident., Spirijer opimus, 

Spirijer sp. ident., Wellerella osagensis? 

Composita trinuclea, Composita sp. ident., Eumetria verneuiliana, 

Eumetria sp. ident., Grijjithides moorei, Linoproductus croneisi, 

? Myalina sanctiludov1:ci, "Orthotetes" sp., ? Palaeonoeilo 

amsdenensis, Productus phillipsi?, "Pustula genevievensis," 

Spirijer welleri, Spirijer sp. ident. 

Eumetria verneuiliana, Grijjithides moorei, ? Palaeoneilo 

amsdenensis, Productus phillipsi?, Spirifer weller·i 

Eumetria verneuUana, ? Palaeoneilo amsdenens·is, "Schizophoria 

swallovi,'' Spirijer welleri, "Spirijerina" browni, Torynifer ct. 

T. setigera 

Amsden Formation 

Madison Limestone 

EXPLANATION 

[_J 0 . 

Sandstone 

Siltstone 

Shale 

Claystone 

~ 

~ 

Sandstone lenses 

Limestone 

I 

Red and maroon strata 

FIGURE 16.-Section of lower part of Amsden Formation at Cherry Creek, sec. 19, T. 31 

N., R. 99 W. Based on Shaw and Bell (1955, p. 334). 
PALEOZOIC FORMATIONS B37 

and white fine-· to medium-grained crossbedded to massive moderately porous and friable sandstone. In 

lithology and outcrop appearance it is strikingly similar to the Tensleep Sandstone. Thickness of the Dar~ 

win has a considerable range, from a minimum of about 

30 feet to a maximum of 170 feet. The range in thickness, however, seems to have no uniform trend; it prob~ 

rubly is due chiefly to the irregular erosion surface on 

which it was deposited. 

The upper part of the Amsden Formation is a variable 

sequence of dolomite, shale, sandstone, and limestone 

ranging in thickness from 180 feet to about 300 feet. 

Colors most common are red, green, gray, and buff. 

The unit is generally poorly exposed because most of 

the strata are nonresistant, but it produces characteristic red, tan, and yellow soils. In many places, directly 

overlying the Darwin Sandstone Member, is a red shale 

about 40 feet thick that contains many hematitic nodules or pisolites. It forms a conspicuous red zone 

along the weathered slopes. Thin beds of sandstone 

occur mostly in the upper part of the formation and are 

typically fine grained, hard, and quartzitic. The dolomite and limestone are massive to thin bedded and are 

generally cherty. Slight disconformities occur locally 

within this upper sequence. 

Southeast along the east flank of the Wind River 

Range the Amsden Formation is 120 feet to about 400 

feet thick. The Darwin Sandstone Member, averaging 

about 75 feet in thickness, can be traced as a relatively 

well defined unit as far southeast as Canyon Creek, 

directly south of Lander in T. 31 N., R. 100 W. There 

the member is about 30 feet thick, unconformably overlies typical Madison Limestone, and conformably 

underlies red ferruginous shale. Farther southeast, in 

sections from the north rim of Little Popo Agie canyon 

(T. 31 N., R. 99 W.) to Sweetwater Canyon, strata 

assigned to the lower part of the Amsden Formation are 

chiefly interbedded red shale, siltstone, and sandstone. 

A 15- to 30-foot basal sandstone is present in most sections, but it is generally thin bedded and easily eroded, 

and hence forms a much less distinct unit than the Darwin Sandstone Member farther north. Although 

many workers have considered this basal sandstone to 

represent the Darwin, specific correlations of the various sandstone units are still very uncertain. 

The upper part of the Amsden Formntion can also 

be traced throughout the central and southeastern parts 

of the Wind River Range. Toward the southeast end 

of the range, however, the sequence contains a higher 

proportion of sandstone and red beds than it does in the 

central and northwestern parts. 

The Amsden Formation is 190__,250 feet thick in the 

Owl Creek and southern Bighorn Mountains. In most 

sections it can be separated into a basal gray to buff 

sandstone (generally correlated with the Darwin Sandstone Member) , a middle red shale and siltstone, and an 

upper light-gray, buff, and tan cherty limestone and 

dolomite. In some places in the southern Bighorn 

Mountains, however, carbonate rocks are scanty, and 

the tripartite division cannot readily be made. 

Along the south margin of the Wind River Basin the 

basal sandstone of the Amsden, also generally referred 

to as the Darwin Sandstone 'Member, is 20'-50 feet thick 

and is overlain by 80-130 feet of chiefly red and gray 

shale and siltstone and locally a few thin beds of sandstone and cherty limestone and dolomite. In the Bates 

Creek and Casper Mountain sections (pl. 5) , at the 

southeast edge of the basin, all Pennsylvanian rocks have 

customarily been included in the lower part of the 

Casper Formation. Lee ( 19·27, p. 49) correlated 85 

feet of red shale at the base of the Casper on Casper 

Mountain with the lower red shale of the Amsden Formation. However, it is now known that the lower part 

o£ the Pennsylvanian sequence in this area is younger 

than the Amsden (fig. 18) and hence is not equivalent 

in a time-stratigraphic sense. 

Contact With the Tensleep Sandstone 

The contact between the Amsden Formation and the 

overlying 'Tensleep Sandstone is marked by a sharp 

change in topography £rom weathered talus-covered 

slopes below to nearly vertical cliffs above. There is 

little evidence of a sedimentary break between the two 

· formations, except locally (for example, Love, 1939, p. 

28), and in many places the contact is gradational where 

thin beds o£ sandstone typical o£ the Tensleep are interbedded with cherty carbonate beds. Agatston (1954, 

p. 515) proposed that the top of the Amsden be drawn 

at the base o£ the lowermost sandstone typical o£ the 

Tensleep, even though thin carbonate, shale, and sandstone beds might be included in the Tensleep. Because 

of the uncertainty of the con tact, the Tensleep and Amsden Formations have been mapped as a single unit in 

some regions, particularly in northwestern Wyoming 

(Love ~and others, 1951). For the same reason the two 

formations are combined on the isopach map (fig. 17). 

Age 

Fossils have not been found in the Darwin 8andstone 

Member o£ the Amsden Formation, but several zones 

above the 'Darwin are fossiliferous, particularly along 

the east flank o£ the Wind River Range (table 6). Until 

recently, all the £ormation above the Darwin was considered to be Pennsylvanian (probably Morrow and 

Atoka; fig~ 18) in age ('Burk, 1954, p. 5 ; Shaw and Bell, 

1955, p. 335; Shaw, 1955, p. 62; Agatston, 1957, p. 32; 

Gorman, 1962) . Furthermore, despite the fact that 

red strata assigned to the lower part o£ the Amsden in 
"1.10° 109° 108° 10r 

:I "' l p A R K - F=f="=-r T F="- I 

106 

I ~6 -" /'.J"\/'\. I I w 46 A s H A K I E I 

., 44° 

I 

I 

J:[]~ ~ w 

ll: 

6J -c.. ,; \.,. I N 

I 45 ) ) - I _., I \_ I 45 111 

l1c 1o9 ~108 '1'67 106 105 104' 1o3_ 1b2 101 100 99 9oiii 97 gr; -95 9:\l ,Jl3 92 91 90 3q 88 87 8" 1 R~ I 84 I 83 ' <~<:: ' 

-.... , ....._ 144........_ • _ 1 1 n ! ~- - t-- -t--..>< - · -~o p-- H C T I' S iP R I N G S t I' 'j. i g I I 

T ~ v / ..,. \ b... .... ..-7' ' ~ - - I-- -r """'" ~.......__ I I 1 I H 

t],\ ~ ----.... /X / ( ........... ~~. ~-~ ./'7 • -lT . -1-1- ~ : r-.... I J 0 

T ~ I ( ._ ...... ·1-. 8 -.... l.ooi ...... r- ' D c TjETOINi ~' v•; x, .. l-soK>-r-........x t:.:.:=!.z ~ X """ i~ - 42 -t........... -.... ~ ... I }.-n 

f I 1 ..,- yl ~~ ~: ........ '!'\. ~ ~ ~ ")-./J 1 L 

i ~('" /")(~X lr>DubJ>i' .. V ~..-~ 6 '......_ ~~ ~ ~- r-- ·E 00 r::-: '""; -,:::__-,_7\. ~ ----{ _ _ _, 

- 17 '\. <_ ... v "' 1\-- t~--. ,_:.t,_--::_r- I.- -e- - "' ""--- I l_ 4o ~ / _ k - 1 ~ 5 """" "'1.7 l 40 l!i ~ "'- X'\ I 

I 1---- ~' \ '--1.6 ""-oS_ 4 3 2 R I W R 1 E.~- 3 4 5 6 f 1 '~ \ 

1

1 

~ J 39 \ _x1 t"' ..... ~ -- I 39 I i'~" ~ I / '\ I / 4 ~Q ·, I 

~38 y 'i\ v ;;:._ ..__ r-...... '' "- -r 38 i: \-IJ 1 

I I' f----:V \.. I \ / ( • 3 I l ' I \ I lL I ~;;; I / .... • / I \ • 

I Htoo~ ~~ ' I" A "IOU'" I 37 I "' • iJ 

'I\ ~ 2 ' Jill, 6, \ 1/ \ , 7 v .r = --... l ' I I I t J:J 3s \.{'J \ e ~ alij;(ert n / 3

s i ""-...: l\1\ I I I t1 

I '-..{ 1\ T '7 , i "' A T 'lit 0 ~r 

1 1 1 

~ "PmOOall /--'\ L-h,ill r~~ /c_G -/,- ~ ( " ; r'\ 1\., \!'-- -\ 

r<'' 430 

;> 

I 

,- l 00 '~,-~f,i\lf x1 }""f" 1 TrJ:: \ " I<~ \ I\ ' "'I, ', I I r (;\ K \ kx • \ " l 1

'6, \ '~ ~ ",.I IX 

s 1

31

U r B I L E IT IT I ElI \ \ ~vn I 3l.---r- !---+-1 --\t---r~ -~--~~ v ..-'tL 41 

t\ ' ,. I I r ' ~-

°Ca:sper 

I 

~ 10 

~ 

j 1: 

I 

I I r--1 

I 

I 

I 

I 

rI 

-+ 1>-o 

~z 

I< 

,~ 

~ 

~J7: I 

L--. lA 

N 

m ~ I rl\ f Ti-'I I~ \ko ~ou:tr~~i:a~~~~i~irer I I II -T I If • 30 

EX PLANA TI 0 N 

X 

l J I I ·rrjrfffi~ffi-t-~-tprtl~~c-•-+ I LJ F LRTET~ MJ-OKN~i'ZJ, ~ -1==-Tir I I I I I I I I : : 0 I I I I -- -+---1:_ --L'·~~ " __ t_t_T I c I I A I I I R I I B 

Surface section 

• 

Subsurface section 

IT~~~~~~~~~~~-L~~~~~~~~~~~~~~~~~~~~~~UL~~~~~~_,~~~~80 79 I 78 

0 10 20 30 MILES 

I 1 42° 

FIGURE 17.-Thickness map of Tensleep and Amsden Formations in central Wyoming. Includes Casper Formation in southeastern part of Wind River Basin. Based in part on W. W. 

Mallory (written commun., 1963). Interval is 100 feet; isopachs are restored across mountain arches where rocks have been eroded; isopachs are dashed where control is 

inadequate. 

td 

~ 

0 

t".l 

0 

8 

~ 

0 

~ 

8 

~ 

~ 

z 

t:1 

::tl 

~ ::tl 

-~ ~ 

~ 

~ 

~ 0 

~ 

~ 
PA!JEOZOIC FORMATIONS B39 

the southern Wind River Range contain Mississippian 

:fossils, many workers believed that the conspicuous erosional unconformity at the base of the Darwin Sandstone Memher marked the Pennsylvanian-Mississippian 

boundary. Such a boundary would correspond to the 

widespread unconformity between the two systems in 

most other regions across the continent (Moore and 

others,1944,p.663). 

W. J. Sando (written commun., 1965) has obtained 

evidence to show that the above reasoning is erroneous; 

fossil collections obtained by him from a locality along 

I-Iorse Creek north of Dubois (near Windy Gap section, pl. 3) indicate that the systemic boundary actually 

occurs within the red shale sequence above the Darwin. 

Sando therefore interprets the Darwin Sandstone Menlber and overlying red shale (at least as much as 73 :ft 

AGE WESTERN WYOMING I CENTRAL WYOMING Casper 

Mountain z 

<C Post-Wolfcamp Park City Formation and equivalent rocks 

a... 

~ 

:iE 

Wolfcamp ---, _____,--- ~ 

.. _. ··: ;. :- ....... _. / . • ... 

Virgil ""- . .. ·._ -_. ~er z 

~ ··• .. <C Missouri / Formation z .. . ....... -• <C 

~ Des Moines Tensleep Sandstone Tensleep Sandstone / >- en en ::::;) z 

/?/ 0 e5 Atoka ~ a... Amsden Amsden 

z Morrow Formation Formation 0 

I co -? ?~? z --------------- 0:: _, <C 

<...:> z 

<C Late a: ............... ~ a... - ~ 

en 

en ........ en 

en Early Madison Limestone - :iE 

FIGURE 18.-Schematic diagram showing approximate intervals of time represented by Mississippian and Pennsylvanian formations in central 

and western Wyoming. Interpreted from data in Thomas and others (195'3), Love (1954), and Agatston (1954). 

TABLE 6.-Fossils from the Amsden Formation 

[Generic and specific names are quoted without modification from sources shown] 

Collection 

Stratigraphic section No. Species References 

(pls. 

2-5) 

Dinwoody Canyon ____ 8 Pteria sp., Astartella sp., Entomis sp., Paraparchites? sp _______________ Eliot Blackwelder (U.S. 

Geol. Survey, unpub. 

field notes); identification by G. H. Girty. 

Bull Lake Canyon ____ 5 Climacammina sp., Endothyra sp., Bradyina sp., Textrataxis cf. T. mill- Murphy and others 

sapensis, Fusulinella gephyraea?, Spirifer cf. S. opimus, Spirifer cf. (1956); Henbest (1956, 

S. rockymontanus, Neospirifer? n. sp., Phricodothyris? sp. indet., p. 61); Love (1954). 

Composita subtilita, Mesolobus striatus, Antiquatonia n. sp., Marginifera splendens, Punctospirifer? sp. indet., Linoproductus prattenianus, Pharkidonotus percarinatus, Plagioglypta? sp. Beaver Creek ________ 2 Orbiculoidea wyomingensis, Wellerella n. sp., Cancrinella boonensis?, Burk (1954, p. 6-7); modiCleiothyridina? sp., Linoproauctus n. sp., L. croneisi, "Marginifera" fied by Shaw (1955, p. 

n. sp., Spir(fer welleri, Allorisma. 63). ., 

,) Composita sp. (not like Composita in the Spirifer welleri zone below it) __ Shaw (1955, p. 63). 

Sweetwater Canyon ___ 12 Spirifer occidental is, Composita sp ________________ - ___ - _-- _-------- W. G. Bell (1955). Windy Gap __________ 5 Spirifer "opimus," Linoproductus n. sp., Composita "trinuclea," Bel- Love (1939,p.28);Shaw 

lerophon sp., Strophostylus? sp. (1955, p. 62). 

6 Orthotetes? sp., Dictyoclostus portlockianus, Linoproductus prattenianus, Burk (1954, p. 7-8). 

Spirifer sp., Composita subtilita var. subtilita, C. subtilita var. trinuclea, 

C. subtilita var. ovata, C. sp., Cleiothyridina sp., Wellerella osagensis, 

Allorisma terminale. 

7 Fusulinella sp ________________________________ -- ------ -- -- ----- -- Love (1939, p. 28); Shaw 

Conant Creek ________ (1955, p. 62). 

5 Chaetetes cf. C. milleporaceous __________________________________ - __ Love (1954). 

East Canyon Creek ___ 1 Allorisma cf. A. terminale _________________________________________ Do. Alcova ______________ 'l ,) Productus cora, P. hermosanus, Composita subtilita, Parallelodon? sp., Lee (1927, p. 52). 

Deltopecten? sp., Pteria sp., Plagioglypta? sp., Bellerophon crassus?. 

4 Allorisma terminale, Pteria longa?, Deltopecten aviculatnm, Parallelodon? Do. 

sp., Schizodtts? sp., Pleurophorns? sp., Bellerophon n. sp., Euphemus 

carbonarius?, Naticopsis aff. N. nana. 
B40 GEOLOGY OF THE WIND RIVER BASIN, C'ENTRAL WYOMING 

above the top of the Darwin) to be latest Mississippian 

(Chester) in age, and infers partial or complete correlation with the controversial red-bed sequence at the 

base of the Amsden Formation along Cherry Creek in 

the southern Wind River Range. As stated above, previous workers (Branson and Greger, 1918; Morey, 1935; 

Shaw and Bell, 1955) had considered this latter sequence to be early Late Mississipian (Meramec) in 

age and hence equivalent to the upper member of the 

Madison Limestone at the Bull Lake Canyon locality. 

Sando (written commun., 1965), on the other hand, considers the Late Mississippian faunas in the basal part 

of the Amsden at Cherry Creek to be of Chester age 

and hence younger than the early Law Mississippian 

(:~1eramec) faunas from the upper member of the Madison at Bull Lake. It should be noted that studies of 

ostracodes from the Mississippian sequence in Illinois 

(for example, Croneis and Funkhouser, 1938, p. 334; 

Coryell and Johnson, 1939, p. 214) suggested a Chester 

age for forms similar to those identified by Morey 

( 1935) as Meramec from the Cherry Creek locality. 

Based on the evidence obtained by Sando (written 

commun., 1965), the following conclusions seem warranted; ( 1) The Amsden contains strata of both Mississippian and Pennsylvanian ages; (2) the basal beds 

of the Amsden are approximately the same age throughout the Wind River Range, but are younger than the 

upper member of the Madison Limestone; and (3) the 

upper member of the Madison Limestone was cut out by 

post-Madison pre-Amsden erosion in the southern Wind 

River Range. In the southern Wind River Range, it 

is still a matter-of conjecture whether the Darwin Sandstone Member of the Amsden Formation disappears 

by facies change, by nondeposition, or by erosion. Precise correlation of the various units of the Amsden in 

the Wind River Basin with those of the type section 

along Amsden Creek in the northern Bighorn:Mountains is also pro~lematic. Gorman (1962) concluded, 

froril a study of fusulinids at the type section, that at 

least the beds immediately overlying the unfossiliferous 

basal sandstone (generally considered to be a Darwin 

equivalent) are Pennsylvanian and that the basal sandstone is probably also Pennsylvanian. 

Conditions of Deposition 

After the Madison Limestone was deposited, central 

Wyoming emerged, and the exposed carbonate rocks 

were eroded into a very irregular surface. In the central and southeastern parts of the Wind River Basin 

area, erosion cut down into Lower Mississippian strata. 

A broad positive area occupied southeastern Wyoming 

and extended as far northwest as the region along the 

southeastern margin of the Wind River Basin (Mallory, 1963, fig. 195.2; Agatston, 1954, fig. 9); in some 

places its Precambrian core was breached. 

At the beginning of Amsden deposition a shallow sea 

spread across all but the southeastern part of the Wind 

River Basin, probably from the west and northwest, 

and an extensive deposit of sand was laid down. Because much of eastern and southeastern Wyoming was 

underlain either by Mississippian carbonate rocks or 

Precambrian crystalline rocks at this time, the source 

of the highly quartzose debris of the Darwin Sandstone 

Member is not known. W. W. Mallory (oral commun., 

1964) suggests that the sand may have come from north 

and east of Wyoming, but the evidence is not conclusive. 

Sand deposition was followed by the widespread accumulation of red clay and silt that was spread across the 

shallow shelf areas from sources also as yet unknown. 

Presumably the highly ferruginous clay was derived 

from a region in which regolithic soils were being developed, perhaps in some parts of southeastern 

Wyoming where Precambrian rocks are known to have 

been exposed to weathering and erosion at that time. 

Fluctuations in sea level, probably in response to 

minor structural movements within the depositional 

area, gave rise to an alternating sequence of limestone, 

dolomite, shale, and sandstone in the upper part of the 

Amsden Formation. Local disconformities within this 

sequence, especially in the upper part (for example, 

Agatston, 1957, p. 29; Gorman, 1962), suggest that certain areas were periodically raised above the level of the 

sea and briefly eroded; the southeastern part of the basin 

area remained emergent. The gradational contact between the Amsden and overlying Tensleep indicates 

that there was no significant withdrawal of the sea at 

the close of Amsden time. 

TENSLEEP SANDSTONE 

Definition 

The Tensleep Sandstone was defined by Darton 

( 1904, p. 397) as the thick sandstone overlying the 

Amsden Formation in the southwestern part. of the Bighorn Mountains. The formation can be traced throughout central and northwestern Wyoming, although on 

Casper Mountain at the southeastern edge of the Wind 

River Basin equivalent rocks are included in the lower 

part of the Casper Formation (Darton, 1908). Branson (1939) included all the Amsden Formation in the 

Tensleep Sandstone in the central Wind River Range, 

but this usage was not widely adopted. 

Lithology and Thickness 

The massive cliff-forming Tensleep Sandstone is one 

of the most distinctive Paleozoic formations in theregion (figs. 3, 19). Along the east flank of the Wind 

River Range the formation is predominantly buff, tan, 

cream-colored, and white fine-grained massive to cross-
PALEOZOIC FORMATION'S B41 

FIGURE 19.-Cliff of Tensleep Sandstone along north side of Middle Popo Agie River, Sinks Canyon. Note crossbedding in left half 

of photograph. 

bedded sandstone (fig. 19). Most of the rock is rather 

porous and friable, but some beds are hard and quartzitic. Thin irregular beds of chert are common, and 

because of the gradational contact with the underlying 

Amsden, the basal part of the Tensleep may include a 

few thin beds of limestone or dolomite. Carbonate 

beds also occur higher in the formation. Many of the 

outcrops weather brown and rusty brown, and, viewed 

from a distance, some appear to be nearly black. 

Coarse talus generally accumulates at the base of the 

cliffs and obscures the lower part of the formation as 

well as much of the underlying Amsden. The Tensleep Sandstone is only about 215 feet thick at the 

northwest end of the range, but it thickens gradually 

to more than 600 feet at the southeast end (pl. 2). 

The lithology of the Tensleep Sandstone is fairly 

uniform. Thickness along the north edge ranges from 

200 to 440 feet, the thickest sections being in the eastern 

Owl Creek Mountains and the southwestern Bighorn 

Mountains (pl. 3). Along the south margin of the 

basin the formation is 220- 350 feet thick (pl. 4). 

In the Bates Creek and Casper Mountain areas (pl. 

5), all Pennsylvanian rocks are placed in the Casper 

Formation (Darton, 1908, p. 418). Sandstone beds 

generally similar to the Tensleep Sandstone occur in 

the middle and upper parts of the Casper, although 

these beds are younger. (See fig. 18). 

COntact With Park City and Equivalent Rocks 

A conspicuous erosional unconformity separates the 

Tensleep Sandstone from the overlying Park City Formation and equivalent rocks of Permian age in nearly 

all exposures around the margins of the Wind River 

Basin. The contact is distinctly uneven and shows 

from a few inches to several feet of relief in many 

places. The basal beds of the Permian sequence are 

commonly conglomeratic. Blackwelder (U.S. Geol. 

Survey, unpub. field notes) reported that in the Dinwoody Canyon area as much as 37 feet of sandstone at 

the top of the Tensleep was cut out underneath the 

unconformity. The time span represented by the unconformity over much of the basin area includes Late 

Pennsylvanian and earliest Permian times. The contact is easily defined on electric logs (pl. 6). 
B42 GE1

0LOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

Age 

Fossils have been collected from several different 

zones within the Tensleep Sandstone at many scattered 

localities in central Wyoming (table 7) . They indica:te that most, if not all, of the formation within the 

Wind River Basin area is Middle Pennsylvanian (Des 

Moines) (Love, 1954; Agatston, 1954, p. 529; Hen best, 

1954; Hoare and Burgess, 1960). Love ( 1954) suggested that in westernmost Wyoming the upper part 

is Late Pennsylvanian (Missouri and Virgil). In the 

Casper Mountain area the lowermost part of the Casper 

Formation may be Middle Pennsylvanian (Agatston, 

1954, table 5), but fusulinids of Late Pennsylvanian 

age have been found near the base and in the middle 

part of the sequence, and Early Permian (Wolfcamp) 

fossils in the upper part (Thomas and others, 1953, fig. 

2 and table 2). An interpretation of the regional age 

relations is shown on figure 18. 

TABLE 7.-Fossils from the Tensleep Sandstone 

[Generic and specific names are quoted without modification from sources shown] 

Collection 

Stratigraphic section No. Species References 

(pis. 2-5) 

Warm Spring Creek___ 8 

Dinwoody Canyon____ 9 

Derbyia crassa, Linoproductus prattenianus, Dictyoclostus hermosanus, Spirijer opimus, Neospirijer cameratus, Composita sp., Straparolus 

(Euomphalus) cf. S. (E.) plummeri, Dentalium (Plagioglypta) sp., 

Ameura sp., Millerella? sp., fusiform fusulinid, either Fusulina sp., or Triticites sp. 

Hoare and Burgess (1960, p. 711-715). 

Derbyia? sp., Productus cora, P. scmireticulatus, P. sp., Spirijer rockymontanus, Composita subtilita, Aviculipecten sp., Pseudomonotis 

hawni?, Pleurophorous? sp., Dentalium sp., Euphemus carbonarius, 

Bellerophon percarinatus, Pleurotomaria sp. 

Eliot Blackwelder (U.S. 

Geol. Survey, unpub. 

field notes) ; iden tification by G. H. Girty; 

Branson (1939, p. 1210). Trout Creek_ _ _ _ _ _ _ _ _ 1 

Sinks Canyon________ 5 

Calcitornella sp., Climacammina sp., Endothyra sp., Bradyina sp., Fusulina leei?, Wedekindellina sp. Henbest (1954, p. 52); 

Love (1954). 

Branson (1939, p. 1208). 

Wind River Canyon __ 12 

Dictyoclostus .~ermosanus, Linoproductus prattenianus, Squamularia perplexa, Composita subtilita. 

Bates Creek _ _ _ _ _ _ _ _ _ 2 

ldiognathodus sp., Streptognathodus sp., Prioniodus sp., Hindeodella sp., 

Helodus sp., Cladodus sp., Fusulina n. sp., Staffella sp. 

Branson (1939, p. 1207). 

C. E . J enkins (1950). 

Thomas and others (1953). 

Fusulinids ____ ___ ____ ____ _______________ ____ _____ _______ _______ _ 

Casper Mountain__ __ _ 2 Triticites kellyensis, projected into section from about 6 miles farther 

east. 

In the Mayoworth area along the east flank of the 

Bighorn Mountains, about 40 miles northeast of the 

Deadman Butte section (pl. 1), Verville (1957) 

described fusulinids and Rhodes ( 1963) described conodonts, of Wolfcamp age in sandy limestone beds which 

they assigned to the uppermost part of the Tensleep 

Sandstone. According to E. K. Maughan (oral commun., 1963), however, these strata are lithologically 

similar to, and probably correlate with, the N owood 

Member of the Phosphoria Formation (McCue, 1953) 

farther west in the southwestern Bighorn Mountains 

(pl. 3) and hence form no part of the Tensleep as we 

have used it in the Wind River Basin area. 

Conditions of Deposition 

Following the deposition of the Amsden Formation a 

shallow sea remained in central Wyoming, although 

some moderately unstable areas were at times raised 

above the base level of deposition, thereby producing 

local disconformities within the boundary zone between 

the Tensleep and Amsden Formations. At the beginning of Middle Pennsylvanian (Des Moines) time, 

quartz detritus was spread across the basin of deposition. The source of the sand is not apparent; Agatston 

(1954, p. 564) suggested that it might have been supplied by uplifts west and south of Wyoming. Thin 

beds of limestone, thickening toward the main area of 

carbonate deposition in eastern Wyoming (Agatston, 

1954, p. 564) , were deposited along with the sandstone 

as the sea advanced and retreated. The only land that 

stood above the sea in central Wyoming was in the 

Casper Mountain area, where sedimentation did not 

occur until later in late Middle Pennsylv-anian or Late 

Pennsylvanian time. In southeastern Wyoming a 

broad positive area furnished sediment until it was submerged in Early Permian time ( Agatston, 1954, p. 565). 

If sedimentation occurred in the Wind River Basin, 

exclusive of the Casper Mountain area, during Late 

Pennsylvanian time, all record of it was destroyed by 

post-Tensleep erosion. The distribution of thickness 

and facies within the Pennsylvanian sequence (Love, 

1954; Agatston, 1954), however, suggests that ( 1) much 

of central Wyoming was raised above the level of the 

sea at the beginning of Late Pennsylvania time; (2) the 

sea retreated eastward into eastern Wyoming and westward toward the major geosynclinal area in southeastern Idaho; and ( 3) detritus eroded from the 
PALEOZOIC FORMATIONS B43 

exposed Tensleep Sandstone was redeposited in basins 

of deposition that flanked the uplift. Marine sedimentation continued along the southeast edge of the Wind 

River Basin and areas to the east through all Late 

Pennsylvanian ti,me, ·and in westernmost Wyoming at 

least until near the close of that epoch. 

PERMIAN ROCKS 

NOMENCLATURE 

Rocks of Permian age comprise one of the most complex Paleozoic systems in central Wyoming. Because 

it contains extensive phosphate deposits and is one of 

the most important reservoirs for oil and gas in the 

region, this system has also been one of the most widely 

studied. Marked lithologic changes occur from west 

to east across the-Wind River Basin, and many problems 

exist in nomenclature and correlation. The regional 

relations, summarized below, have been discussed in 

detail by Thomas ( 1934), Tourtelot ( 1952), McCue 

(1953), McKelvey and others (1956; 1959), and Weichman (1958). 

Darton (1906a, p. 17, 18) applied the name Embar 

Formation to a "prominent series of limestone and chert 

beds lying between the Tensleep sandstone and the Chugwater red beds" along the north slope of the Owl Creek 

Mountains. The type section is about 6 miles north of 

the Sheep Ridge section (pis. 1, 2). Darton (1906b, 

p. 35, 36) extended the term into the Bighorn Mountains, 

but limited it to a lower limestone and shale unit only 

and did not include any of the overlying red shale and 

gypsum. Condit (1916, p. 263), however, recognized 

that the marine strata graded eastward from the type 

area into red shales containing many gypsum beds. He 

( p. 263) stated "In the Bighorn Mountains * * * the 

transformation of the Embar beds is so complete that 

they ean only with difficulty be distinguished from the 

overlying red beds composing the Chugwater formation [Triassic]." 

In an early report on the northern Wind ·River Range, 

Blackwelder (1911, p. 475) used the name Embar, but 

he later (1918) separated the sequence into two formations. The upper unit, consisting of greenish-gray 

shale, siltstone, and sandstone now considered to be of 

Triassic age, he called the Dinwoody Formation from 

exposures in Dinwoody Canyon. The lower part, predominantly limestone, dolomite, chert, and phosphate 

rock, he referred to the Park City Formation, a name 

used earlier by Boutwell ( 1907, p. 443) in the Park City 

mining district of Utah. Condit (1924, p. 11) concluded that the beds assigned to the Park City by Blackwelder were more nearly correlative with the Phosphoria 

Formation as that unit had been defined by Richards 

and Mansfield ( 1912) in southeastern Idaho. The 

Phosphoria was then widely accepted in the central and 

western parts of the Wind River Basin for the rocks 

lying between the Tensleep Sandstone and the Din woody 

Formation. Limited use of the name Embar continued, but the term has long since been considered obsolete 

(Thomas, 1934, p. 1670, 1671) and was abandoned 

(McKelvey and others, 19·56, p. 2835). 

In 1947 the U.S. Geological Survey began a systematic investigation of the western phosphate field, 

which includes western Wyoming, northwestern Utah, 

eastern Idaho, and southwestern Montana. This program resulted in a comprehensive study and review of 

the stratigraphy, nomenclature, and correlation of the 

Permian rocks (McKelvey and others, 1956, 1959). It 

was proposed that the sequence be divided into three 

major lithologic facies, each being assigned to a different formation; the general distribution of the various 

facies is shown on figure 20. Because considerable intertonguing occurs between the different rock types, the 

individual members of one formation in any given vertical section may be directly overlain or underlain by 

members of another formation. (See Dinwoody Canyon section, pl. 2.) Therefore, for geologic mapping, 

it was further proposed that the name of the formation bearing the dominant lithology be given 

preference. 

Within the Wind River Basin all the major types 

of facies are present-chiefly red beds of the Goose Egg 

Formation (see following paragraph) in the eastern 

part; carbonate rocks of the Park City Formation in 

the central part; and mudstone, chert, and phosphorite 

of the Phosphoria Formation and variable amounts 

of sandstone of the Shedhorn Sandstone in the western 

part (fig. 20). The distinction between the red-bed 

and carbonate rock facies in the eastern third of the 

basin is relatively clear cut, but in the western third the 

separation of facies is often very difficult because of the 

intricate intertonguing of many different rock types. 

The principal lithology over much of the area, however, is carbonate rock; consequently, the name Park 

City Formation and equivalents is used in this report 

rather than the name Phosphoria Formation which has 

been used more commonly in the past. 

Thomas ( 1934) studied the intertonguing of limestone with red beds in central and southeastern Wyoming, and named several of the eastward-projecting 

tongues of the Phosphoria Formation. In a later report, Burk and Thomas ( 1956) proposed the name 

Goose Egg Formation for the red shale and gypsum 

sequence containing thin beds of limestone in the extreme southeast corner of the Wind River Basin (fig. 

21.). The name was derived from the Goose Egg Post 

Office along Wyoming Highway 220 at the west end 
B44 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

MONTANA 

---------------------------, EXPLANATION 

l 

J 

I 

I 

f 

__ _] 

I 

N 

I 

I 

\ 

Mudstone, chert, and phosphorite 

(Phosphoria Formation) 

Sandstone 

(Shedhorn Sandstone) 

Carbonate rock 

(Park City Formation) 

Red beds 

(Goose Egg Formation) 

I I 

L---UTAH--~------ -~~~~l~~ --------_j 

0 50 100 MILES 

FIGURE 20.-Distribution of major facies in Permian rock·s in central and western Wyoming. Based on McKelvey and others (1959, p. 4). 

of Casper Mountain; the type section is shown on plate 

5. In this report the Goose Egg is extended northward 

to include similar strata in the southern Bighorn 

Mount,ains. 

PARK CITY FORMATION 

Lithology and Thickness 

In the northern Wind River Range and adjacent 

parts of the Washakie Range, the Park City Formation 

consists of 150-260 feet (fig. 22) of interbedded chert, 

limestone, dolomite, siltstone, and very fine grained 

sa~dstone and a few thin beds of shale and phosphate 

rock. Colors are predominantly tan, gray, and buff; the 

phosphatic beds are dark gray to brown and black. The 

basal beds of the formation, 5-15 feet thick, are commonly conglomeratic and contain angular fragments of 

white and gray siltstone, sandstone, and crystalline 

quartz, and rounded pebbles and granules of black 

chert. The matrix of the conglomerate ranges from 

pink and gray dense sandy limestone to tan and pink 

coarse-grained sandstone. Chert occurs in thin beds but 

more commonly as tubular twisted masses in thickbedded limestone and dolomite. The twisted chert 

masses, which are particularly abundant in the upper 

half, are the most characteristic lithologic features of 

the formation. Phosphate rock, generally black and 

oolitic, is in beds only a foot or two thick. Some other 

rock types contain abundant phosphatic grains or pellets, and many fossil shells are highly phosphatic. 

Similar lithology characterizes the Park City Formation toward the southeast end of the Wind River Range, 

except for a gradual increase in limestone and dolomite. 

Also, little sandstone or basal conglomerate is present 

at most localities. Detailed descriptions have been published by King (1947-1957) and Sheldon (1957), who 

separated these r:ocks into several units for convenience 

in evaluating the phosphate deposits. Thickness ranges 

from about 180 to 325 feet (pl. 2). The upper massive 

chert and carbonate units erode to very prominent dip 

slopes along the entire east flank of the range (fig. 23). 

The dip slopes are grass covered, but they are conspicuously devoid of trees in contrast to the underlying 

Tensleep Sandstone. 

Along the south margin of the Wind River Basin the 

Park City can be traced as far east as the Conant Creek 

area, where it is :about 350 feet thick (pl. 1). Farther 

east, toward the north end of Rattlesnake Hills, the carbonate and chert facies grade into the red-bed facies of 

the Goose Egg Formation (Weichman, 1958). Thin 

tongues of limestone project eastward into the red beds, 

however, and are present throughout the eastern part 

of the Wind River Basin (fig. 21; see discussion of 

Goose Egg Formation) .. 
FIOURFJ 21.- Exposures of Goose Eg·g Formation (l<Pge) at Alcova Darn, southeastern Wind Rive r Basin. lie, Chugwater Formation; Pt, Tensleep Sandstone. 

;;' 

~ 0 

~ ..... 

Q 

":: 

0 

::0 

0 

~ 2: 

r/J 

t:d 

~ 
.,J,.1o· 1os• 107" 109° 

I 1 V : p ~ R K - T T F= ' 

I

I 4G ~~ .!'' / \....- f-k _J,.....---:::.1\ ,· w 46A s H A K I E I - '0 ;' ;·"- I " . - I ll N I I I 

' 45 .~ I ' M- I i 45 I X I• 1a9 ~iX 8 --«57 •or;t 1o5 1~<1 1.Q.L 1;,, 10• 1a!' 99 98 97 96 fos . 9 4 93_ 92 91 9a 89 88 87 8b' 1 "' 84 83 82 8

1 80 79 78 

"' 1 , 1 

! 4~ fl- _::_ - t--f__ ~' H 0 T S: P k I N G S t

44 

\ 1 i ~ li2 wl li1 

~'\ 43 II > -/--::~. . A 1\-' x·- ,........... • 4~ ~~ 1

• J o H N s o N 

1 

\J I 1 \ '0.. ~ ....-_]i,- \ ]T~erm polis I ·'-:3 . . :E 

TIEToj N : 4&. \\ 1>< ---1: ~;o 42 ::>o-iY'-J.-/ I U< 1 '- ( )·---- --~~ ~ lr ~ 4< • IX 1 u 

I 1'--\ ,j., b . . \X I X I I I I I I 41 ........ t. .... ,.:Y u ~~ / v----.k ~ 6 "-X .::-.._ _ r -+-- 41 ~---r=*--r- r- -- ~ r-- - - ---- --1--~ ~--'-

1 I I i 4~- - ! "' / f ·--~- t\ "r---.. fo-• ~ ~--=- "'1\ ~-)<~ - I "-. \ 

-- •--~ ~0 13 4' RW ~IE 2 3 4 56 !' 1A ' 

3~ '· I (' I I 39 I " X I 

X !' \ I v •\ 4 I , 38 < ~ ~ .... ~ --11 0/ 38 ,· X \ I I I I I I ---1 \ I J e '-.. "1 ·, ;::: I 1 37 •

1 1 ·, / ~ \ ~v 37 i . ..........-- --'4: • g, ' I/...-'(' -\ 2 ., / - __.. ' '-

~ \/r \ _\ T --- / 36 ! ll'' IL 35 k-"'-1 J \. • N oiivert<n 3S 1 ~ 

I I 0 '-~~ 1\ (~X 5 e ~l-.----'~ 1 N _IY'_ T ~ 

34~ , ___ \1\ /' ~~ , rrr'~-, T:J 34 • ; A / 

0/1 N I A 

5ft)--i><>o 

1

33 I I \., ·r ·,r ~~Later V I • 33 • • i 

l 132 I I I I er,\ I ~, ( ---- --· ---\3 2 ! • 

I I I f===f f= \',p_ X •\ \ ... / l1!~- 1---'1 ---t--

p,... _c / I\ 

X 

r-· I X 

°Clsper .) 

s 1

31 u • t--~j../ 

.. m 

_j~- - _ _jr- ~--\-

• 

E I B L E T T 

30 I'~ "'l X I f¥ I \j I ~II ' + o I I i Bpu nd ~ry of_ Win~. Rli '- I\ 1 - . I structu ra l bals1n 

I ~-111~0Ilf~ !; L L "r-~ 

' y_ 

EXPLANATION 

X 

Surface section R l IB im ~~3 I 82 I 81 I 8o I 79 I 78 

H: n_:JJ:tti l~+t~ll4it I I I I I 

• 

Subsurface section 

0 10 20 30 MI LES 

s R1b2 

[ ·101 riOO I 99 

E Ef T 1

w 98 97 I 96 95 

I II 1

2

:

4 1 

R • I 90 : 89 

A ! T l25 E 94 . 93 I 92 I 91 1 

88 I 87 I 86 

F IGURE 22.-Thickness map O:f Park City Formation and equivalents, in central Wyoming. Interval is 100 feet; isopachs ar e restored across mountain a rches where rocks have been 

eroded ; isopachs are dashed where control is inadequate. 

to 

~ 

0) 

~ b 

0 

>-< 

0 

"'j 

>-3 

~ 

~ 

~ 

~ 

< l:':l 

~ 

ttl 

~ 

~ 

~ ~ 

> t"' 

~ 0 

~ z 

0 
PALEOZOIC FORMATIONS B47 

FIG URE 23.- Prominent dip slopes ( " flatirons") of Park City Formation along east fiank of Wind River Runge, near· Fort Washakie. 'l'ree- · 

covered slopes in middle background are on 'l'ensleep Sandstone. 

The Park City Formation is 200- 265 feet thick in 

the Owl Creek Mountains (pl. 3), and consists chiefly 

of limestone, dolomite, dolomitic siltstone, and chert. 

These beds persist to the east end of the range, but farther east, in exposures at the west end of the Bighorn 

Mountains, red beds and gypsum (of the Goose Egg 

Formation) are the dominant rock types (Tourtelot, 

1952, p. 50). At the base of the Permain sequence in 

the southwestern Bighorn Mountains is a thin resistant dolomite that unconformably overlies the Tensleep 

Sandstone and which is, in turn, unconformably overlain by the lowermost red beds (pl. 3). This dolomite has been referred to as the N owood Member of the 

Phosphoria Formation by McCue ( 1953). It can be 

traced westward into the Owl Creek Mountains (E. K. 

Maughan, oral commun., 1963) and probably correlates 

with the Grandeur Member of the Park City Formation in the northern Wind River Range (McKelvey 

and others, 1959, p. 12-15) _ 

Contact With the Dinwoody Formation 

The contact between the Park City Formation and 

the overlying Triassic Dinwoody Formation appears 

to be nearly everywhere conformable, even though a 

hiatus, possibly representing all Late Permian (Ochoa) 

time, occurs between the two formations. There is, 

however, a sharp change in lithology at the contact. 

In contrast to the ledge-forming massive gray and tan 

chert, limestone, and dolomite in the upper part of the 

Park City, the Dinwoody is characterized by slopeforming thin-bedded slabby siltstone and very fine 

grained sandstone that weather to a distinctive yellowish tan in most places. The contact is readily defined 

on most electric logs. 

Age 

The Park City Formation is abundantly fossiliferous, containing a predominance of brachiopods and 

bryozoans (table 8) _ Coquina beds consisting almost 

entirely of large specimens of a single fossil species occur locally, as do conodonts and fish and shark remains. 

Yochelson (1963) found that each major rock facies 

has its own characteristic fossil assemblage and stated 

that "The nearly complete limitation of each assemblage to a particular facies is striking." 

Despite the variety and abundance of fossils, specific 

correlation with the standard reference section of Permian rocks in West Texas is still somewhat uncertain. 

According to Thomas ( 1948, p. 90), the faunas in the 

Permian rocks of central Wyoming are provincial and 

not well represented in the Texas Permian. The available data indicate, however, tha:t most of the Park City 

correlates with the Word Formation of Guadalupe 

(Early and Late Permian) age (Thomas, 1948, p. 90; 

Williams, in McKelvey and others, 1959, p. 39, 40). The 

basal beds (Nowood or Grandeur Member) are as old 

as Leonard and possibly Wolfcamp (Early Permian), 

and the uppermost part probably is at least as young as 

late Guadalupe. Fossils of definite Ochoa (Late Permian) age have not been recognized. 

Conditions of Deposition 

At the beginning of Permian time a broad northsouth-trending highland occupied all the Wind River 

Basin area. Rocks of Middle Pennsylvanian age were 

exposed in the central and western parts of the basin, 

some of Late Pennsylvanian age in the eastern part. 

The seas lay both east and west of the highland and, in 

Wolfcamp time, began to encroach upon it from both 
B48 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

sides. Possibly by late W olfcamp time the highland 

was breached by shallow throughgoing seaways that 

persisted into Leonard time, and a thin deposit of limestone was laid down across the northern and western 

parts of the basin. Sand, eroded from the exposed Tensleep Sandstone, was deposited along the east edge during Wolfcamp time. Then the seas regressed, at least 

from the eastern part of the basin area, and a short period of erosion followed. In late Leonard time, seas 

again encroached from either side of the highland, and 

by Guadalupe time the entire region was flooded. In the 

east the sea remained shallow, and red shale and evaporite sediments accumulated, but toward the west, sedimentation took place in deeper waters. Periodically 

the sea expanded eastward, and thin but widespread 

tongues of limestone were deposited over the westwardprojecting tongues of red shale. In Thomas' opinion 

(1948, p. 91) the relation between the red beds and the 

limestone is one of intertonguing rather than of facies 

change, suggesting that the eastward expansion of the 

sea was fairly rapid. 

Stratigraphic section 

Warm Spring Creek __ 

Dinwoody Canyon ___ _ 

Bull Lake Canyon ___ _ 

Trout Creek ______ __ _ 

Squaw Creek _____ __ _ 

Sinks Canyon _____ __ _ Beaver Creek _______ _ 

Collection 

No. (pis. 

2- 5) 

9 

10 

11 

10 

11 

12 

13 

6 

7 

8 

9 

2 

1 

2 

6 

4 

The sea may have withdrawn by the end of Guadalupe time, for there is no positive record that sedimentation occurred in the basin area during latest Permian 

time. 

TABLE 8.-Fossils from Park City and Goose Egg Formations 

[Generic and specific names are quoted without modification from sources shown] 

Species 

Bellerophon sp., Euphemites subpapillosus, Strophostylus sp., Plicatoderbya magna, Punctospirifer pulchra, Neospirifer pseudocameratus, 

Waagenoconcha montpelierensis, Aulosteges cf. A. hispidus, Pustula 

nevadensis. 

Stenopora (3 sp.), Lioclema sp., Phyllopora sp., Rhombopora sp., Meekella 

sp., Chonetes aff. C. geinitzianus, Aulosteges sp., Spiriferina pulchra, 

Aviculopecten sp., Pseudomonotis aff. P. hawni, Bellerophon? sp., 

Patella sp., Nautilus sp. Orbiculoidea sp _____________ __ ____ __ __ -- ---- -- - - - - - --------- -- -- -

Orbiculoidea sp. indet., fish remains _____ __ -- _-- --- -- ---- -- - ---- - - - -

Orbiculoidea (Roemerella) utahensis, Schizodus sp. indet. or Scaphellina 

sp. indet., Sanguinolites? sp. indet. or Wilkingia? sp indet., fish 

remains, bryozoans. Orbiculoidea (Roemerella) utahensis, Derbyia magna, Wellerella cf. W. 

osagensis, Spheno.~teges hispidus, Echinauris subhorridus, Bathymyonia 

nevadensis, Spiriferina pulchra, Aviculopecten sp. indet., Nucluopsis poposiensis, Polidevcia bellistriata, Stutchburia sp. indet., fish remains, 

abundant bryozoans. Composita subtilita, Chonetes sp. indet. Sphenosteges hispidus, Derbyia 

magna, Bathymyonia sp. indet., Spiriferina pulchra, Aviculopecten 

sp. indet., Hustedia phosphoriensis, Nucula pulchella, Cyrtorostia 

varicostata, Camptonectes? sp. indet., Pseudomonotis sp. indet., 

Conocardium sp. indet., Schizodus canalis, Stutchburia? sp. indet., 

Sanguinolites? sp. indet. or W ilkingia sp. indet., Stearoceras? sp. 

indet., Euphemitopsis subjiapillosus, fish remains, abundant 

bryozoans. Orbiculoidea sp. indet., Scaphellina concinnus, Schizodus cf. S. wheeleri, 

Euphemites sp. indet., Sanguinolites? sp. indet. or Wilkingia sp. 

indet., Cyrtorostia? sp. indet., fish remains, abundant bryozoans. Orbiculoidea sp. indet., Echinauris sub horrid us, "Liosotella" sp. indct. , 

Bathymyonia nevadensis, Spiriferina pulchra, Muirwoodia multi- striatus, abundant bryozoans. Composita subtilita, Spiriferina cf. S. kentuckensis, Hustedia phosphoriensis. lV ellerella cf. W . osagensis, Sphenosteges sp. indet., Composita subtilita, 

Derbyia sp. indet., Neospirifer pseudocameratus, "Liosotella" sp. 

indet., Bathymyonia nevadensis, Muirwoodia multistriatus, Spiriferina 

pulchra, Hustedia phosphoriensis, Dielasma sp. indet., Myalina cf. 

M. (M.) wyominyensis, Cyrtorostia varicostata, Aviculopecten cf. 

A. kaibabensis, Aviculopecten sp. indet., Plagioglypta canna, abundant 

bryozoans. Composita subtilita?, Solenomya sp., Pteria sp., Allorisma terminale?, 

Sanguinolaria? sp., Pleurophorus sp., Pleurophorus aff. P. subcostatus, 

Astartella? sp., Schizodus? sp., Plagioglypta canna, Patellostium? sp., 

Pleurotomaria sp. Orbiculoidea sp ________ __ ___ ____ ______ ______ __ - - --- __ _ -- ------ -- -

Composita sp., Neospirifer pseudocameratis, Punctospirifer pule her __ - __ - Orbiculoidea sp., Allorisma sp _ _ _ _ ___ ______ _____ _ -- - _---- - --- - - - --

Orbiculoidea sp ___ __ ____ ____ ___ ____ ---- --- - - --- -------- ------ - -- -

References 

Love (1939, p. 34). 

Eliot Blackwelder (U.S. 

Geol. Survey, unpub. field notes); identification by G . H. Girty. 

Weart (1948). 

E. L. Yochelson (written 

commun., 1964). 

Do. 

Do. 

Do . 

E. L. Yochelson (written 

commun., 1964) . 

Do . 

Do. 

Do. 

Eliot Blackwelder (U.S. 

Geol. Survey, unpub. 

field notes); identification by G. H. Girty. 

King (1947, p . 38- 39). 

King (1947, p. 32). 

Condit (1924, p . 24). 

Condit (1924, p. 29). 
Collection 

Stratigraphic section No. 

(pls. 

2-5) 

Windy Gap__________ 8 

9 

10 

Circle Ridge_________ 1 

Sheep Ridge_ _ _ _ _ _ _ _ _ 1 

2 

Wind River Canyon__ 13 

Rattlesnake Hills___ _ _ 3 

4 

Alcova______________ 5 

6 

Bates Creek _ _ _ _ _ _ _ _ _ 3 

CasperMountain_____ 3 

PALEOZOIC FORMATIONS 

TABLE 8.-Fossils from Park City and Goose Egg Formations-Continued 

[Generic and specific names are quoted without modification from sources shown] 

Species 

Sphenosteges sp. indet., Composita sp. indet., Derbyia magna, Neospirifer 

pseudocameratus, Echinauris subhorridus, "Liosotella" sp. indet., 

Bathymyonia nevadensis, Spiriferina sp. indet., Nucula sp. indet., 

Polidevcia bellistriata, Schizodus sp. indet. or Scaphellina sp. indet., 

Sanguinolites? sp. indet. or Wilkingia sp. indet., fish remains, abundant bryozoans. 

Bathymyonia nevadensis, Derbyia magna, Cyrtorostia varicostata, fish re- mains, abundant bryozoans. 

Conularia sp. indet., Orbiculoidea sp. indet., Sphenosteges hispidus, 

Bathymyonia nevadensis, Derbyia magna, Spiriferina pulchra, Spiriferina cf. S. kentuckensis, Hustedia phosphoriensis, Aviculopecten sp. 

indet., Schizodus sp. indet. or Scaphellina sp. indet., Sanguinolites? 

sp. indet. or Wilkingia sp. indet., Costatoria secradiata, Stutchburia? 

sp. indet., fish remains, abundant bryozoans. 

Hustedia phosphoriensis, Spiriferina pulchra, Aviculopecten sp., Pustula 

nevadensis, Orbiculoidea sp. Plagioglypta, M yalina? ________________________________ - _---------

Plicatoderbya, Punctospirifer, Batostomella, Aviculopecten, Hustedia, 

Stenopora?, Pleurotomaria, Horridonia?, Dictyoclostus, Ammodiscus. 

(Collection obtained from type section of "Embar" Formation.) 

Stenopora n. sp., Phyllopora sp., Derbya aff. D. multistriata, Spiriferina 

pulchra, Solenomya? n. sp., Chaenomya? n. sp., Deltopecten aff. D. 

vanvleeti, Pseuodmonotis aff. P. sublevis, Pseudomonotis aff. P. hawni, 

Oxytoma? n. sp., Myalina wyomingensis?, Myalina sp., Schizodus aff. 

S. deparcus, Schizodus aff. S. subcircularis, S. ferrieri?, Pleurophorus n. sp., Plagioglypta canna, Bellerophon aff. B. crassus, Euphemus? sp., 

Naticopsis? sp., Omphalotrochus? sp. Plagioglypta? sp ________________________ -- __ - _- _ -----------------

Bryozoans (many species), Punctospirifer pulchra, Punctospirifer aff. P. 

kentuckyensis, Composita cf. C. mexicana, Derbya aff. D. plicatella, 

Tentaculites sp., Plagioglypta? sp. (small), Myalina sp. (large), Myalina aff. M. perattenuata, Pleurophorus pricei, Pleurophorus (4 sp.), 

Leda obesa, Cyrtorostra? sp., Aviculopecten sp., Deltopecten vanvleeti, 

Parallelodon aff. P. tenuistriatus, Edmondia? sp., Schizodus cf. S. 

wheeleri, Schizodus? sp. (large), Schizodus sp. (small), Pinna peracuta, 

Euphemus subpapillosus, Bellerophon sp., gastropod (high-spired 

form), Coelogasteroceras thomasi, Coloceras? sp. Plagioglypta? sp ___________________________________ --------------

Myalina permiana, Pinna cf. P. peracuta, Pleurophorus sp., gastropods 

(high-spired form; several species). 

Dentalium (Plagioglypta) cf. D. (P.) canna, Pleurophorus occidentalis, 

gastropods (high-spired form). 

Pinna paracuta, Schizodus ferrieri, Pteria? sp., Plagioglypta canna_-----

B49 

References 

E. L. Yochelson (written 

commun., 1964). 

Do. 

Do. 

Milton (1942). 

McCue (1953). 

Do. 

Lee (1927, p. 57). 

Thomas (1934, p. 1674). 

Thomas (1934, p. 1675). 

Thomas (1934, p. 1678). 

Do. 

Jenkins (1950). 

Lee (1927, p. 49). 

PERMIAN AND TRIASSIC ROCKS, GOOSE EGG 

FORMATION 

Medicine Member is an eastward-projecting tongue 

from the Lower Triassic Dinwoody Formation. Thus, 

only that part of the Goose Egg Formation lying below 

the top of the Ervay is considered to be the equivalent 

of the Park City Formation; these strata have a thickness of 304 feet (pl. 5) . 

Lithology and Thickness 

At its type locality (Casper Mountain section, pl. 5) 

the Goose Egg Formation consists of 380 feet of red 

gypsiferous shale and siltstone interbedded with distinctive gray and purple dense platy limestone. The 

formation can be divided in ascending order into 

Opeche Shale, Minnekahta Limestone, Glendo Shale, 

Forelle Limestone, Difficulty Shale, Ervay, Freezeout 

Shale, and Little Medicine Members ( Burk and 

Thomas, 1956, p. 6; Maughan, 1964). The red-bed 

units range in thickness from 40 to about 100 feet, and 

the limestone beds from 6 to 22 feet. The Minnekahta, 

Forelle, and Ervay Members are eastward-projecting 

tongues from the Park City Formation, and the Little 

The individual members of the Goose Egg Formation 

can be traced in subsurface sections northwest along the 

Casper arch to the south end of the Bighorn Mountains. 

In this area they are 355 feet thick; of this thickness 

the Park City equivalents comprise 270 feet (pl. 3). 

Westward into the Owl Creek Mountains the red beds 

and gypsum gradually intertongue with carbonate rocks 

and chert of the Park City Formation (pl. 3) and with 

dolomitic siltstone of the Dinwoody Formation. Another member, the N owood Member of the Phosphoria 
B50 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

For1nation of McCue ( 1953), occurs locally at the base 

of the Goose Egg in the southwestern Bighorn Mountains (pl. 3). 

Although typical lithologies of fhe Goose Egg Formation can be observed in exposures at the north end of 

R1attlesnake Hills (pl. 4), it is difficult to distinguish 

the Forelle Limestone Member, because several thin 

limestone beds occur in the middle part of the formation. 

Some of the red-bed units appear to extend westward 

along the south margin of the Wind River Basin nearly 

as far -as the Conant Creek area, but exposures are too 

poor in the intervening area to show where individual 

tongues wedge out. 

Contact With the Chugwater Formation 

The Goose Egg Formation is overlain conformably 

by the Triassic Chugwater Formation. Because both 

formations consist predominantly of red shale and siltstone, it is commonly difficult to determine the contact in 

surface sections. According to Burk and Thomas 

(1956, p. 7), the Goose Egg beds are generally darker 

red, sandier, more gypsiferous, and somewhat more 

resistant than those in the Chugwater. In addition, 

the Goose Egg contains thin beds of limestone, but the 

lower part of the Chugwater does not. The Goose Egg 

Formation generally shows higher resistivity on electric 

logs than does the Chugwater; the contact, therefore, 

is easily identified in subsurface sections. 

Age 

The Minnekahta Limestone and Ervay Members hs,ve 

yielded fossils at several localities in the southern and 

southeastern parts of the Wind River Basin (table 8). 

A large assemblage from the Ervay in the Rattlesnake 

Hills indicates correlation with the upper part of the 

Park City Formation and equivalents of the Wind 

River Range (Thomas, 1934, p. 1676). It is concluded, 

therefore, that the Goose Egg Formation below the 

top of the Ervay Member is probably Early and early 

Late Permian. The upper two members of the formation (Freezeout Shale and Little Medicine Members), 

on the other hand, are lateral equivalents of the Din-

·woody Formation which is considered to be of Early 

Triassic age (Newell and Kummel, 1942). There is no 

evidence that rocks of latest Pennian age exist in the 

region, despite the seeming conformity between the 

Ervay Member and overlying strata. 

Conditions of Deposition 

While normal marine sedimentation took place in the 

western half of the Wind River Basin during late Early 

and early Late Permian times, red clastic sediments 

accumulated in the shallow areas of the seas in the eastern part. The continuity and uniformity of the red 

beds suggest that the red beds were deposited under 

water, but this is still uncertain. The source of the 

red debris is not known, but it was probably low landmasses tha.:t lay principally to the east and south of 

Wyoming (Thomas, 1934, p. 1691, 1692). Increase in 

the depth of water, caused either by eustatic rise in sea 

level or cessation of uplift in the landmasses, resulted 

periodically in the deposition of limestone across the 

entire region. In the eastern part of the basin area, 

some arms of the sea became isolated, or circulation 

became restricted, to the extent that evaporites were 

deposited. 

Sedimentation apparently ceased in central Wyoming 

during latest Permian time, but there is no evidence in 

the strata of the Goose Egg Formation to suggest that 

the sea withdrew. 

PALEOZOIC STRUCTURE 

Throughout the Paleozoic Era the present site of 

the Wind River Basin was a region of remarkable crustal sta.bility. Although hiatuses-some of them representing long periods of time-occur between many of 

the formations, no angular discordances within the 

Paleozoic rocks were recognized. The thickness maps 

(figs. 6, 11, 12, 14, 17, and 22) suggest that tectonic 

movements were limited to broad upwarping and downwarping along trends which, with one exception, show 

little direct relation to the structural trends of later 

Laramide deformation. If some parallelism did exist 

during certain periods, it was only temporary and in 

large part probably coincidental. Commonly the reverse is true; Paleozoic "highs" and "lows" correspond 

to Laramide "lows" and "highs," respectively. (Compare isopach maps with fig. 2.) The one exception is 

along the southeast margin of the basin, where an area 

coinciding roughly with the Laramie Mountains wa'3 

relatively positive during much of Paleozoic time. 

This positive area, which widened south and southeast, 

is outlined by thickness lines for both the Cambrian 

and Mississippian strata (figs. 6, 14) ; Ordovician and 

Devonian rocks, if initially deposited in the area, were 

eroded before successively younger strata were laid 

down. One of the most pronounced periods of uplift 

was Middle Pennsylvanian (Atoka) time, when the 

positive area extended westward and included much 

of the region now occupied by the Granite Mountains. 

In terms of Pennsylvanian paleogeography, it has been 

referred to by Mallory ( 1963) as the Pathfinder uplift. 

ECONOMIC GEOLOGY 

OIL AND GAS 

Paleozoic rocks are among the most important reservoirs for oil and gas in the Wind River Basin ; they 

constitute the primary objectives for drilling in many 
PALEOZOIC FORMATIONS B51 

areas. The Park City Formation and equivalents and 

Tensleep Sandstone are the most prolific, each being 

productive in about 20 fields (drill data as of Aug. 1, 

1963). The Madison Limestone yields oil and gas in two 

fields, the Amsden Formation (Darwin Sandstone 

Member) in one. Wells drilled to Precambrian rocks 

in several of the producing fields have not found significant amounts of petroleum in Devonian or older rocks. 

Nearly all production from Paleozoic rocks has been 

from anticlinal folds along the basin margins. Conditions favoring stratigraphic entrapment, such as 

textural and porosity changes within carbonate strata, 

wedging out of beds beneath unconformities, and 

changes in facies, exist in certain areas. Many of these 

potential sources, however, have not been adequately 

studied or explored. The Cottonwood Creek field in the 

southeastern part of the Bighorn Basin produces from 

a stratigraphic trap formed by the carbonate-to-shale 

facies change within the Park City and Goose Egg Formations (Biggs and Espach, 1960, p. 80), but attempts 

to locate similar traps in the south-central part of the 

Wind .River Basin have as yet been unsuccessful. 

Owing to excessive drilling depths, the Paleozoic rocks 

remain virtually untested in the central part of the basin. 

PHOSPH.A:TE ROCK 

Permian rocks have long been recognized as a potential source of phosphate in central and western 

'Vyoming (Weeks and Ferrier, 1906; Weeks, 1907; 

Blackwelder, 1911; Condit, 1924). Owing to accessibility and proximity to a railroad terminal, the deposits 

along the east flank of the Wind River Range near Lander have been of particular economic interest. King 

(1947) studied the Lander deposits, and, more recently, 

Sheldon (1957) reported on the phosphate rocks at 

selected localities in the northwestern part of the range. 

Phosphate rock is also present in nearly all outcrops of 

the Park City Formation and equivalents in the southwestern and northern parts of the Wind River Basin, 

but these have not been extensively studied. 

The phosphate-bearing rocks generally form two distinct zones within the Permian sequence along the east 

flank of the Wind River Range. These zones have been 

referred to as the "lower phosphate zone" and "upper 

phosphate zone" by Condit (1924) and King (1947) 

and as units B and D by Sheldon ( 1957). Each zone 

occurs as distinct beds of phosphorite, generally less 

than 1 foot thick and rarely more than 2 feet thick, and 

as grains or pellets disseminated through shale, sandstone, and limestone, with which the phosphorite is 

interbedded. According to King ( 194 7, p. 12), the 

phosphate rock in the Lander area is classed as low to 

medium grade; the lower zone ranges from 21.5 to 29.7 

pereent P205 and the upper zone from 15.2 to 20.2 

percent P 205. 

None of the phosphate deposits in the region has yet 

been exploited. The reserves, mining conditions, and 

power and transportation facilities are adequate, but 

the thinness and relative low grade of the phosphate 

beds have been the principal deterrents (King, 1947, p. 

81). A determination that the Lander deposits are 

economic undoubtedly would provide an incentive to 

search for additional reserves in the adjacent areas. 

OTHER COMMODITIES 

The sandstone and carbonate rocks of the Paleozoic 

formations are readily available for a variety of construction uses in many areas. None of the strata has 

yet been used extensively as building stone. The Flathead Sandstone would probably be the best source, because of its color, resistance to weathering, and thin 

bedding. Other thick sandstone units, such as the Tensleep 'Sandstone and the Darwin Sandstone Member of 

the Amsden Formation, are more massive, friable, and 

porous. 

Hematite-bearing red shale that occurs above the Darwin Sandstone Member of the Amsden Formation at 

many localities may prove to be a source of low-grade 

iron ore. Gruner and Smith ( 1955, p. 31) reported 

carnotite associated with barite and fluorite in rocks of 

Cambrian ( ? ) age near Whiskey Mountain (sec. 12, T. 

40 N., R. 107 W.), in the northern part of the Wind 

River Range. Localized radioactive deposits have also 

been reported from the Tensleep Sandstone in sec. 31, 

T. 31 N., R. 97 W., and from the Phosphoda Formation 

in sees. 7 and 10, T. 30 N., R. 97 W. (Wilson, 1960, p. 23). 

The extent and potential of the deposits are not known. 

REFERENCES CITED 

Agatston, R. S., 1954, Pennsylvanian and Lower Permian of 

northern and eastern Wyoming : Am. Assoc. Petroleum 

Geologists Bull., v. 38, no. 4, p. 508-583. 

-- 1957, Pennsyl~aniau of the Wind River Basin, in Wyoming Geol. Assoc. Guidebook, 12th Ann. Field Conf., 1957: 

p. 29-33. 

Amsden, T. W., and Miller, A. K., 1942, Ordovician conodonts 

from the Bighorn Mountains of Wyoming: Jour. Paleontology, v.16, no. 3, p. 301-306. 

· Andrichuk, J. M., 1951, Regional stratigraphic analysis of 

Devonian System in Wyoming, Montana, southern Saskatchewan, and Alberta: Am. Assoc. Petroleum Geologists 

Bull., v. 35, no. 11, p. 2368-2408. 

-- 1955, Mississippian Madison group stratigraphy and 

sedimentation in Wyoming and southern Montana : Am. 

Ass·oc. Petroleum Geologists Bull., v. 39, no. 11, p. 2170-2210. 

Bearce, D. N., 1963, The Sacajawea Formation and the Darwin 

Sandstone in the southeast Wind River Mountains, Wyoming: Missouri Univ., unpub. masters thesis, 61 p. 
B52 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

Bell, W. G., 1955, The geology of the southeastern flank of the 

Wind River Mountains, Fremont County, Wyoming: Wyoming Univ., unpub. Ph.D. dissertation, 204 p. 

Berg, R. R., 1961, Laramide tectonics of the Wind River Mountains, in Wyoming Geol. Assoc. Guidebook 16th Ann. Field 

Conf., 1961 : p. 70-80. 

Biggs, C. A., 1951, Stratigraphy of the Amsden formation of 

the Wind River Range and adjacent areas in northwestern 

Wyoming: Wyoming Univ., unpub. masters thesis, 121 p. 

Biggs, Paul, and Espach, R. H., 1960, Petroleum and natural gas 

fields in Wyoming: U.S. Bur. Mines Bull. 582, 538 p. 

Blackwelder, Eliot, 1911, A reconnaissance of the phosphate 

deposits in western Wyoming: U.S. Geol. Survey Bull. 470, 

p. 452-481. 

--- 1913, Origin of the Bighorn dolomite of Wyoming : Geol. 

Soc. America Bull., v. 24, p. 607--624. 

--- 1918, New geological formations in western Wyoming: 

Washington Acad. Sci. Jour., v. 8, no. 13, p. 417-426. 

Bogrett, J. W., 1951, Geology of the northwestern end of the 

Rattlesnake Hills, Natrona County, Wyoming: Wyoming 

Univ., unpub. masters thesis, 70 p. 

Boutwell, J. M., 1907, Stratigraphy and structure of the Park 

City mining district, Utah: Jour. Geology, v. 15, p. 434-458. 

Branson, C. C., 1937, Stratigraphy and fauna of the Sacajawea 

formation, Mississippian, of Wyoming: Jour. Paleontology, 

v.11,no.8,p.650--660. 

--- 1939, Pennsylvanian formations of central Wyoming: 

Geol. Soc. America Bull., v. 50, no. 8, p. 1199-1226. 

Branson, E. B., and Branson, 0. C., 1941, Geology af the Wind 

River 'Mountains, Wyoming: Am. Assoc. Petroleum Geologists Bull., v. 25, no. 1, p. 120-151. 

Branson, E. B., and Greger, D. K., 1918, Amsden formation of 

the east slope of the Wind River Mountains of "Wyoming 

and its fauna: Geol. Soc. America Bull., v. 29, p. 309-326. 

Burk, C. A., 1954, Faunas and ·age of the Amsden formation in 

Wyoming: Jour. Paleontology, v. 28, no. 1, p. 1-16. 

Burk, C. A., and Thomas, H. D., 1956, The Goose Egg formation 

('Permo-Triassic) of eastern Wyoming: Wyoming Geol. 

Survey Rept. Inv. 6, 11 p. 

Burton, G. ·C., 1952, Geology of 'Squaw Creek area, Wind River 

Mountains, Fremont County, Wyoming: Mi·ssouri Univ., 

unpub. master thesis. 

Chronic, John, and Ferris, C. S., Jr., 1961, Lower Paleozoic outlier in southeastern Wyoming [a'bs.] : Geol. 'Soc. America 

Spec. Paper 68, p. 86. 

Cloud, P. E., Jr., 1955, Physical limits of glauconite .formation: 

Am. Assoc. Petroleum Geologists Bull., v. 39, no. 4, p. 484-492. 

Collier, A. J., and Cathcart, S. H., 1922, Possi•bility of finding oil 

in laccolithic domes south of the Little Rocky Mountains, 

Montana: U.S. Geol. Survey Bull. 736-F, p.171-178. 

Condit, D. D., 1916, Rel·ations of Embar and Chugwater formations in central Wyoming: U.S. Geol. Survey Prof. Paper 

98-0, p. 263-270. 

---1924, Phosphate deposits in the Wind River Mountains, 

near Lander, Wyoming: U.S. Geol. Survey Bull. 764, 39 p. 

Coryell, H. N., and Johnson, S. C., 1939, Ostracoda of the Clore 

limestone, Upper Mississippian, of Illinois: Jour. Paleontology, v. 13, no. 2, p. 214-224. 

Croneis, C. G., and Funkhouser, H. J., 1938, New ostracodes 

from the Clore formation [Ill.] : Denison Univ. Sci. Lab. 

Jour., v. 33, p. 331-360. 

Darton, N. H., 1901, Geology and water resources of the southern half of the Black Hills and adjoining regions in South 

Dakota and Wyoming: U.S. Geol. •Survey 21st Ann. Rept., 

pt. 4, 489-599. 

Darton, N.H., 1904, Comparison of the stratigraphy of the Black 

Hills, Bighorn Mountains, and Rocky Mountain front range: 

Geol. Soc. America Bull., v.l5, p. 379-448. 

--- 1906a, Geology of the Owl Creek Mountains: U.S·. 59th 

Cong., 1st sess., S. Doc. 219, 48 p. 

---1906b, Geology of the Bighorn Mountains: U.S. Geol. 

Survey Prof. Paper 51, 129 p. 

---1906c, Fish remains in Ordovician rocks in Bighorn 

Mountains, Wyoming, with a resume of Ordovician geology 

of the Northwest: Geol. Soc. America Bull., v. 17, p. 541-

566. 

---1908, Paleozoic and Mesozoic of central "''Yoming : Geol. 

Soc. America Bull., v. 19, p. 403-470. 

Darton, N. H., and Paige, Sidney, 1925, Central Black Hills, 

South Dakota: U.S. Geol. Survey ·Geol. Atlas, Folio 219, 

7 maps. 

Deiss, Charles, 1938, Cambrian formations and sections in part 

of Cordilleran trough: Geol. Soc. America Bull., v. 49, no. 

7, p. 1067-1168. 

DeLand, C. R., 1954, Cambrian stratigraphy and Upper Cambrian trilobites of the southwestern flank of the Wind River 

Mountains. Wyoming: Wyoming Univ., unpub. masters 

•thesis, 135 p. 

DeLand, C. R., and Shaw, A. B., 1956, Upper Cambrian trilobites 

from western Wyoming: Jour. Paleontology, v. 30, no. 3, 

p. 542-562. 

Denison, R. H., 1951, Late Devonian fresh-water fishes from the 

western United States: Fieldiana Geology, v. 1'1, no. 5, 

p. 221-261. 

Denson, M. E., Jr., and Morrissey, N. S., 1952, The Madison 

group (Mississippian) of the Big Horn and Wind River 

Basins, Wyoming, in Wyoming Geol. Assoc. Guidebook, 7th 

Ann. Field Oonf., 1952: p. 37-43. 

Denson, N. M., 1942, Late Middle Cambrian trilobite faunas and 

stratigraphy of Al•berta, Montana, Wyoming, and Utah: 

Princeton Univ., unpub. Ph.D. dissertation. 

Duncan, Helen, 1956, Ordovician and ·Silurian coral faunas of 

western United States: U.S. Geol. Survey Bull. 1021-F, p. 

209-236. 

Easton, W. H., 1962, <Carboniferous formations and faunas of 

central Montana: U.S. Geol. Survey Prof. Paper 348, 126 p. 

Flanagan, P. E., 1955, Geology of the Mud Creek area, Hot 

Springs County, Wyoming: Wyoming Univ., unpub. masters 

thesis, 57 p. 

~-- 1962, The Mississippian-Madison rock:;; of the Wind River 

Basin, Wyoming [abs.], in Program for Rocky Mountain 

Section, Am. Assoc. Petroleum Geologists, 12th Ann. Mtg., 

Salt Lake City, Utah: p. 20. 

Flower, R. H., 1946, Ordovician cephalopods of the Cincinnati 

region: Bull. Am. Paleontology, v. 29, no. 116, 656 p. 

--- 1952, New Ordovician cephalopods from eastern North 

America: Jour. Paleontology, v. 26, no. 1, p. 24-59. 

Foster, H. L., 1947, Paleozoic and Mesozoic stratigraphy of 

northern Gros Ventre Mountains and Mount Leidy Highlands, Teton County, Wyoming: Am. Assoc. Petroleum 

Geologists Bull., v. 31, no. 9, p. 1537-1593. 

Gooldy, P. L., 1947, Geology of the Beaver Creek-South Sheep 

Mountain area, Fremont County, Wyoming: Wyoming Univ., 

unpub. masters thesis, 75 p. 

Gorman, D. R., 1962, A study of the Amsden Formation: Illinois 

Univ., unpub. Ph.D. dissertation, 167 p. 
PALEOZOIC FORMATIONS B53 

Gruner, J. W., and Smith, D. K., Jr., 1955, Annual report for 

Aprill, 1954 to March 31, 1955: U.S. Atomic Energy Comm. 

RME 3020, 37 p. 

Harrison, J. W., 1938, Pennsylvanian stratigraphy of the Laramie Range of southeastern Wyoming: Wyoming Univ., 

unpub. masters thesis, 85 p. 

Hembree, M. R., 1949, Geology of the Fossil Hill area, Wind 

River Mountains, Fremont County, Wyoming: Missouri 

Univ., unpub. masters thesis. 

Henbest, L. G., 1954, Pennsylvanian Foraminifera in Amsden 

formation and Tensleep sandstone, Montana and Wyoming, 

in Billings Geol. Soc. Guidebook 5th Ann. Field Conf., 1954: 

p.~. 

--- 1956, Foraminifera and correlation of the Tensleep 

sandstone of Pennsylvanian age in Wyoming, in Wyoming 

Geol. Assoc. Guidebook 11th Ann. Field Conf., 1956: p. 58-63. 

Hoare, R. D., and Burgess, J.D., 1960, Fauna from the Tensleep 

Sandstone in Wyoming: Jour. Paleontology, v. 34, p. 711-

716. 

Hose, R. K., 1955, Geology of the Crazy Woman Creek area, 

Johnson County, Wyoming: U.S. Geol. Survey Bull. 1027-B. 

p. 33-118. 

Howell, B. F., and others, 1944, Correlation of the Cambrian 

formations of North America [chart 1] : Geol. Soc. America 

Bull., v. 55, no. 8, p. 993-1003. 

Jenkins, C. E., 1950, Geology of the Bates Creek-Corral Creek 

area, Natrona County, Wyoming: Wyoming Univ., unpub. 

masters thesis, 80 p. 

Keefer, W. R., 1957, Geology of the Du Noir area, Fremont 

County, Wyoming: U.S. Geol. Survey Prof. Paper 294-E, 

p. 155-221. 

--- 1965, Stratigraphy and geologic history of the uppermost Cretaceous, Paleocene, and lower Eocene rocks in the 

Wind River Basin, central Wyoming: U.S. Geol. Survey 

Prof. Paper 495-A, 77 p. 

King, R. H., 1947, Phosphate deposits near Lander, Wyoming: 

Wyoming Geol. Survey Bull. 39, 84 p. 

--- 1957, Stratigraphy of the Phosphoria formation in the 

Wind River Mountains, in Wyoming Geol. Assoc. Guidebook 12th Ann. Field Conf., 1957 : p. 35-38. 

Kirk, Edwin, 1930, The Harding sandstone of Colorado: Am. 

Jour. Sci., 5th ser., v. 20, p. 456--466. 

Klapper, Gilbert, 1958, An Upper Devonian conodont fauna from 

the Darby formation of the Wind River Mountains, Wyoming: Jour. Paleontology, v. 32, no. 6, p. 1082-1093. 

Lee, ,V. T., 1927, Correlation of geologic formations between 

east-central Colorado, central Wyoming, and southern Montana: U.S. Geol. Survey Prof. Paper 149,80 p. 

Lochman, Christina, 1950, Status of the Dry Creek Shale of 

central Montana: Am. Assoc. Petroleum Geologists Bull., 

v.34,no. 11,p.2200-2222. 

LPChman-Balk, Christina, 1956, The evo~ution of some Upper 

Cambrian and Lower Ordovician trilobite families: Jour. 

Paleontology, v. 30, no. 3, p. 445-462. 

--- 1957, Paleoecology of the Cambrian in Montana and 

Wyoming, chap. 8 in Ladd, H. S., ed., Paleoecology, v. 2 of 

Treatise on marine ecology and paleoecology: Geol. Soc. 

America Mem. 67, p.117-162. 

Lochman-Balk, Christina, and Wilson, J. L., 1958, Cambrian 

biostratigraphy in North America: Jour. Paleontology, v. 

32, no. 2, p. 312-350. 

Love, J. D., 1939, Geology along the southern margin of the 

Absaroka Range, Wyoming: Geol. Soc. America Spec. 

Paper 20, 134 p. 

--- 1954, Tentative diagrammatic correlation of Tensleep, 

Amsden, Casper, and Hartville Formations in Wyoming, in 

Wyoming Geol. Assoc. Guidebook 9th Ann. Field Conf., 

1954 [chart in pocket]. 

Love, J. D., Keefer, W. R., Dnnean, D. C., Bergqui~St, H. R., and 

Hose, R. K., 1951, Geologic map of the Spread Creek-Gros 

Ventre River area, Teton County, Wyoming: U.S. Geol. 

Survey Oil and Gas Inv. Map OM-118. 

Love, J.D., Tourtelot, H. A., Johnson, C. 0., Thompson, R. M., 

Sharke:r, H. H. R., and Zapp, A. D., 1947, Stratigraphic 

sections of Mesozoic rocks in central Wyoming: Wyoming 

Geol. Survey Bull. 38, 59 p. 

Love, J.D., Weitz, J. L., and Hose, R. K., 1955, Geologic map of 

Wyoming: U.S. Geol. Survey. 

Lyon, D. L., 1956, Geology of the north flank, eastern Bridger 

Range, Hot Springs County, Wyoming: Wyoming Univ., 

unpub. masters thesis, 95 p. 

McCue, J. J., 1953, Facies changes within the Phosphoria Formation in the southeast portion of the Big Horn Basin, 

Wyoming: Wyoming Univ., unpub. masters thesis, 88 p. 

McKee, E. D., 1945, Stratigraphy and ecology of the Grand 

Canyon Cambrian, Pt. 1 of Cambrian history of the Grand 

Canyon region : Carnegie Inst. Washington Pub. 563, p. 

1-168. 

McKelvey, V. E., Williams, J. S., Sheldon, R. P., Cressman, E. 

R., Cheney, T. M., and Swanson, R. W., 1956, Summary description of Phosphoria, Park City, and Shedhorn Formations in western phosphate field: Am. Assoc. Petroleum 

Geologists Bull., v. 40, no. 12, p. 2826--2863. 

McKelvey, V. E., Cressman, E. R., Sheldon, R. P., Cheney, T. M., 

Swanson, R. W., and Williams, J. S., 1959, The Phosphoria, 

Park City, and Shedhorn formations in western phosphate 

field: U.S. Geol. Survey Prof. Paper 313-A, p. 1-46. 

Mallory, W. ,V., 1963, Pathfinder uplift of Pennsylvanian age in 

southern Wyoming, in Short papers in geology, hydrology, 

and topography: U. S. Geol. Survey Prof. Paper 450-E, p. 

E57-E60. 

Mansfield, G. R., 1927, Geography, geology, and mineral resources of part of southeastern Idaho, with descriptions of 

Carboniferous and Triassic fossils, by G. H. Girty: U.S. 

Geol. Survey Prof. Paper 152, 453 p. 

Maughan, E. K., 1963, Mississippian rocks in the Laramie Range, 

Wyoming, and adjacent areas, in Short papers in geology 

and hydrology : U.S. Geol. Survey Prof. Paper 475-0, p. 

023--{)27. 

--- 1964, The Goose Egg Formation in the Laramie Range 

and adjacent parts of southeastern Wyoming, in Geological 

Survey Research 1964: U.S. Geol. Survey Prof. Paper 501-B, 

p. B53-B60. 

Miller, A. K., 1930, The age and correlation of the Bighorn formation of northwestern United States: Am. Jour. Sci., 5th 

ser., v. 20, p. 195-213. 

--- 1932, The cephalopods of the Bighorn formation of the 

Wind River Mountains of Wyoming: Connecticut Acad. 

Arts and Sci. Trans:, v. 31, p. 193-297. 

Miller, B. M., 1936, Cambrian stratigraphy of northwestern 

Wyoming: Jour. Geology, v. 44, no. 2, pt. 1, p. 113--144. 

Milton, A. A., 1942, Geology of the Circle Ridge-Spring Mountain 

area, Owl Creek Mountains, Wyoming: Iowa State Univ .. 

unpub. masters thesis. 
B54 GEOLOGY OF THE WIND RIVER BASIN, CENTRAL WYOMING 

Moore, R. C., chm., and others, 1944, Correlation of Pennsylvanian formations of North America: Geol. Soc. America 

Bull., v. 55, no. 6, p. 657-706. 

Morey, P. S., 1935, Ostracoda from the Amsden formation of 

Wyoming: Jour. Paleontology, v. 9, no. 6, p. 474-482. 

Murphy, J. F., Privrasky, N. C., and Moerlein, G. A., 1956, 

Geology of the Sheldon-Little Dome area, Fremont County, 

Wyoming: U.S. Geol. Survey Oil and Gas Inv. Map OM-181. 

Murphy, J. F., and Richmond, G. M., 1965, Geology of the Bull 

Lake West quadrangle, Wyoming: U.S. Geol. Survey 

Geol. Quad. Map ·GQ-432. 

Newell, N. D., and Kummel, Bernhard, Jr., 1942, Lower Eo-

·Triassic stratigraphy, western Wyoming and southeast 

Idaho: Geol. Soc. America Bull., v. 53, no. 6, p. 937-996. 

Peale, A. C., 1893, The Paleozoic section in the vicinity of Three 

Forks, Mont.,: U.S. Geol. survey Bull. 110, 56 p. 

Phillips, D. P., 1958, Geology of the Sheep Ridge area, Hot 

Springs and Fremont Counties, Wyoming: Wyoming Univ., 

unpub. masters thesis, 135 p. 

Powell, J. D., 1957, The geology of the Blackrock Ridge area, 

Hot Springs and Fremont Counties, Wyoming : Wyoming 

Univ., unpub. masters thesis, 118 p. 

Rhodes, F. H. T., 1963, Conodonts from the topmost Tensleep 

Sandstone of the eastern Big Horn Mountains, Wyoming : 

Jour. Paleontology, v. 37, no. 2, p. 401-408. 

Richards, R. W., and Mansfield, G. R., 1912, The Bannock overthrust, a major fault in southeastern Idaho and northeastern Utah: Jour. Geology, v. 20, p. 681-709. 

Richardson, G. B., 1913, The Paleozoic section in northern Utah: 

Am. Jour. Sci., 4th ser., v. 36, p. 406--416. 

Rabinson, G. D., 1963, Geology of the Three Forks quadrangle, 

Montana: U.S. Geol. Survey Prof. Paper 370, 143 p. 

Ross, R. J., Jr., 1957a, Origin of Ordovician units exposed near 

the Wind River basin, i.n Wyoming Geol. Assoc. Guidebook 

12th Ann. Field Conf., 1957: p. 17-19. 

--- 1957:b, Ordovician fossils from wells in the Williston 

basin, eastern Montana: U.S. Geol. Survey Bull. 10"21-M, p. 

439-510. 

Sandberg, C. A., 1963, Dark shale unit of Devonian and 

Mississippian age in northern Wyoming and southern Montana, in Short papers in geology and hydrology: U.S. Geol. 

Survey Prof. Paper 475-C, p. C17-C20. 

Sandberg, C. A., and McMannis, W. J., 1964, Occurrence and 

paleogeographic significance of the Maywood Formation of 

Late Devonian age in the Gallatin Range, southwestern 

Montana, in Geological Survey Research 1964: U.S. Geol. 

Survey Prof. Paper 501-C, p. C50--C54. 

Sando, W. J., and Dutro, J. T., Jr., 1960, Stratigraphy and coral 

zonation of the Madison Group and Brazer Dolomite in 

northeastern Utah, western Wyoming, and southwestern 

Montana, in Wyoming Geol. Assoc. Guidebook 15th Ann. 

Field Oonf., 1960: p. 117-126. 

Shaw, A. B., 1954, Correlation of the Paleozoic formations of 

Wyoming, in Wyoming Geol. Assoc. Guidebook 9th Ann. 

Field Conf., 1954. [chart in pocket]. 

--- 1955, The Amsden formation in southwestern and southcentral Wyoming, in Wyoming Geol. Assoc. Guidebook lOth 

Ann. Field Conf., 1955: p. 6().-.63. 

--- 1957, Cambrian of tbe southwestern 'Vind River Basin, 

Wyoming, in Wyoming Geol. Assoc. Guidebook 12th Arm. 

Field Oonf., 1957: p. 9-16. 

Shaw, A. B., and Bell, W. G., 1955, Age of the Amsden formation, Cherry Creek, Wind River Mountains, Wyoming: Am. 

Assoc. Petroleum Geologists Bull., v. 39, no. 3, p. 333-337. 

Shaw, A. B., and DeLand, C. R., 1955, Cambrian of southwestern 

Wyoming, in Wyoming Geol. Assoc. Guidebook lOth Ann. 

Field Conf., 1955: p. 3~. 

Sheldon, R. P., 1957, Physical stratigraphy of the Phosphoria 

formation in northwestern Wyoming: U.S. Geol. Survey 

Bull. 1042-E, p.105-185. 

Sims, F. C., 1948, Geology of the west end of the Laramie Range, 

Natrona County, Wyoming: Wyoming Univ., unpub. masters 

thesis, 52 p. 

Sloss, L. L., 1952, Introduction to the Mississippian of the Williston Basin, in Billings Geol. Soc. Guidebook 3d Ann. 

Field Conf., 1952 : p. 65-69. 

Stokes, W. L., 1953, Summary of Paleozoic and Mesozoic stratigraphy [Utah], in Intermountain Assoc. Petroleum Geologists Guidebook 4th Ann. Field Conf., 1953: p. 14-18. 

Strickland, J. W., 1957, Summary of Mississippian and Devonian 

stratigraphy, Wind River Basin, Wyoming, in Wyoming 

Geol. Assoc. Guidebook 12th Ann. Field Conf., 1957: p. 2Q28. 

Thomas, H. D., 1934, Phosphoria and Dinwoody· tongues in 

lower Chugwater of central and southeastern Wyoming: 

Am. Assoc. Petroleum Geologists Bull., v. 18, no. 12, p. 1655-

1697. 

--- 1948, Summary of Paleozoic stratigraphy of the Wind 

River Basin, Wyoming, in Wyoming Geol. Assoc. Guidebook 

3d Ann. Field Conf., 1948: p. 79-95. 

--- 1952, Cambrian and Ordovician stratigraphy around the 

southern Bighorn Basin, Wyoming, in Wyoming Geol. Assoc. 

Guidebook 7th Ann. Field Conf., 1952: p. 32-36. 

--- 1957, Geologic history and structure of Wyoming : 

Wyoming Geol. Survey repr. 18, 11 p. 

Thomas, H. D., Thompson, M. L., and Harrison, J. W., 1953, 

Fusulinids of the Casper formation of Wyoming: Wyoming 

Geol. Survey Bull. 46, 56 p. 

Tourtelot, H. A., 1952, Marine and evaporite facies of Permian 

and Triassic strata in the southern part of the Bighorn 

Basin and adjacent areas, central Wyoming, in Wyoming 

Geol. Assoc. Guidebook 7th Ann. Field Conf., 1952 : p. 4~2. 

--- 1953, Geology of the Bad water area, central Wyoming: 

U.S. Geol. Survey Oil and Gas Inv. Map OM-124. 

Tourtelot, H. A., and Thompson, R. M., 1948, Geology of the 

Boysen area, central Wyoming: U.S. Geol. Survey Oil and 

Gas Inv. Map91. 

VanHouten, F. B., and Weitz, J. L., 1956, Geologic map of the 

eastern Beaver Divide-Gas Hills area, Fremont and 

Natrona Counties, Wyoming: U.S. Geol. Survey Oil and 

Gas Inv. Map OM-180. 

Verville, G. J., 1957, Wolfcampian fusulinids from the Tensleep sandstone in the Bighorn Mountains, Wyoming: Jour. 

·Paleontology, v. 31, no. 2, p. 349-352. 

Walcott, C. D., 1908, Cambrian Brachiopoda-descriptions .of 

new genera and species, No. 3 of Cambrian geology and 

!paleontology: Smithsonian Misc. CoHn., v. 53, no. 3, p. 53-

137. 

Wanless, H. R., Belknap, R. L., and Foster, Helen, 1955, Paleozoic and ~Mesozoic rocks of Gros Ventre, Teton, Hoback, and 

'Snake River ranges, Wyoming: Geol. Soc. America Mem. 

63, 90 p, 
PALEOZOIC FORMATIONS B55 

Weart, R. 0., 1948, Geology of the northern flank of the Wind 

River Mountains, Fremont County, Wyoming: Univ. Syr-acuse, unpub. masters thesis. 

Weed, W. H., 1900, Geology of the Little Belt Mountains, Montana: U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 257-461. 

Weeks, F. B., 1907, Phosphate deposits in western United States: 

U.S. Geol. Survey Bull. 340-K, p. 441-447. 

Weeks, F. B., and Ferrier, ,V. F., 1906, Phosphate deposits in 

western United States: U.S. Geol. ·Survey Bull. 31&--P, p. 

449-462. 

Weichman, B. E., 1958, Stratigraphy of the ·Phosphoria Formation in the southern portion of the Wind River Basin, Wyoming: Wyoming Univ., unpub. masters thesis, 72 p. 

Wilson, W. H., 1960, Radioactive mineral deposits ·of Wyoming: 

Wyoming Geol. Survey Rept. lnv. 7, 41 p. 

Woodward, T. C., 1957, Geology of the Deadman Butte area, 

Natrona County, Wyoming: Am. Assoc. •Petroleum Geologists Bull., v. 41, no. 2, p. 212-262. 

Y·oche1son, E. L., 1963, Paleoecology orf the Permian Phosphoria 

Formation and related rocks, in Short papers in geology 

•and hydrology: U.S. Geol. •Survey Prof. Paper 475_.B, p. 

B123--B124. 

INDEX 

[Italic page numbers indicate major references] 

A Page Page 

Absaroka Range ________________ -------------- B4 Bothriolepis ______ -- ______ --------------------- B29 

Acroteta microscopica tetonensis________________ 16 Boysen Formation ___ ------------------------ 7 

Agatston, R. S., cited________________________ 42 subdivisions ______ ----------------________ 19 

Agnostus tumidosus___________________________ 16 Bradyina SP---------------------------- _ ------ 39,42 

sp_ --------------------------------------- 16 Branson, E. B., quoted _____ ----------------- 35 

AUorisma _____ ___ ----------- ___________ . ___ ___ 39 Brigham Quartzite___________________________ 15 

terminale __ ------------------ ____ ---- _____ 39,48 Briscoia schucherti- ________ -------------- __ . -- 16 

Allumettoceras sp_ ---------------------------- 25 Burnetia alta. __ ------------------------------ 16 

Ameura sp ____ --------------------------- ____ 42 Buck Spring Formation ____________________ 7, 18,19 

Ammodiscus ___________________ -------------- 49 Building stone, Flathead Sandstone__________ 51 

Amsden Formation ____ -------------- ________ 90,95 Bull Lake____________________________________ 35 

contact with Tensleep Sandstone_________ 97 Bull Lake Canyon. __ ------------ 22, 23, 27, 29, 30, 1,0 

Darwin Sandstone Member ________ 95,97,99,1,0 Burk, C. A., cited ____________________________ 43,50 

oil and gas __________________ ---------- 51 Burnetia sp ________________ ------------------- 16 

fossils ____ ----------------------------- 95, 97,99 Bynumia sp __ -------------------------------- 16 

Anticline, Conant Creek_____________________ 3 

Antiquatonia sp. ------------------------------ 39 c 

Apachia convexa. __ --------------------------- 16 Calapoecia borealis---------------------------- 25 

Apatognathus varians _____ ---------------- ____ 29 canadensis._--------_------- ___ -- __ -__ ---- 25 

Aphelaspis sp _________ ----- ________ ___ ___ ___ __ 16 SP---- ------------------------------------ 25 zone _______ --------------_________________ 21 Calcitornella sp_ ------------------------------ 42 Arapahoia levis ______ -------------____________ 16 Camarotoechia sapphO------------------------- 33 

spatulata ________________ ------------- _____ 16 sp_ ------------------------------ _______ _ _ 33 

typa_ -------------------------------- _____ 16 Cambrian formations, fossils__________________ 16 

Astartella SP-------------------------- _____ __ 39, 48 Cambrian rocks.----------------------------- 7 Aulosteges hispidus____________________________ 48 Camptonectes sp_ ----------------------------- 48 

sp_ --------------------------------- ___ ___ 48 Cancrinella boonensis_________________________ 39 

Aviculopecten. _ __ _ _ _ _ __ ___ _ _ ___ _ _ ___ _ __ __ _ _ _ _ _ 49 Caninophyllum.------------------------------ 33 

kaibabensis ____________ ------------------ __ 48 Carnotite associated with barite and fluorite__ 51 

SP------------------------------------- 42, 48,49 Casper arch. __ ------------------------------ 2, 6, 49 

Casper Formation ______________________ 37, 1,0, 1,1, 1,2 

B Casper Mountain ___ -------------- 6, 18, 37, 1,0, 1,1, 42 Barbouria sp _________ ---- __ _ __ _ ______ _ __ _ __ ___ 33 Catazyga headi borealis_----------------------- 25 Bates Creek _______________________________ 33, 37,41 sp _________ --- _____ . ___ -- __ ----- _ -- __ -- __ - 25 

Bathymyonia nevadensis __________________ _____ 48,49 Catenipora •. -_-------------------------------- 23 

sp _________ ------------------------------- 48 gracilis _______ ----------------------------- 25 

Batostomella ______ _____ --------------- __ _____ _ 49 Cedaria prolifica.--------------------- -------- 16 

Beartooth Butte Formation__________________ 27 wne _______________ ----------------------- 18, 21 

Beaver Divide, erosional escarpment of Terti- Cedarina alberta ___ --------------------------- 16 

ary rocks _____ -------------------- :e victoria ____________ -----------------_______ 16 

Bellerophon crassus___________________________ 39 Chaetetes milleporaceous-----------------"----- 39 

percarinatus ______ ------------------------ 42 Chariocephalus SP----------------------------- 16 

sp_ ------------------------------------ 39, 48, 49 Cherry Creek. ____ --------------------------- 95, 1,0 

Belodina compressus. __ ------------------- ____ 25 Chonetes chesterensis. ___ ---------------------- 33 

Bemaspis ____________ ---------- ___ _________ ___ 16 geinitzianus ___ _ -- _____ -------------------- 48 

Berkia .• ----------------------- ___ ___ ___ __ ____ 16 sp ___________________ --- _ --------------- _ _ 48 

Bernia ____ ---------------------_______________ 16 Chugwater Formation ________________________ 1,9,50 

Bighorn Basin________________________________ 4 Circle Ridge area ___________________________ -- 23 

Bighorn Dolomite ________ ---------------- ____ :eo, :et Cladodus sp __ ------------------------------ __ 42 

contact with overlying rocks______________ :es Cleiothyridina crassicardinalis----------------- 33 

fossils _____ ---------------- ____________ !BJ, 29, 25 sp _________________ - _ -------------------- _ 39 

Lander Sandstone Member ________ 21,!B!B,2S,25 Cliffia latagenae.------------------------------ 16 

Leigh Dolomite Member _________________ 22,S5 Climacammina SP----------------------------- 39,42 

Bighorn Limestone___________________________ 21 Cloud, P. E., Jr., cited_______________________ 19 

Bighorn Mountains ____ 6, 7, 17, 18, 21, 23, 25, 30, 35, 37, Coelogasteroceras thomasL----------------- ---- 49 

41, 42, 43, 47 Coloceras sp _____ --------------------------- __ 49 

BiUingseUa_ _ _ __ _ ___ _____ __ ______ __ ___ _ _______ 16 Columnaria alveolata__________________________ 25 

coloradoensis______________ ___ ___ __ ____ _ ___ 16 halli_ _________________________________ ---- 25 

striata _____ ----------_____________________ 16 Composita humilis. __ ------------------------- 33 

Blackwelder, Eliot, cited ________________ 7, 26, 41,43 

Blountia amage_______________________________ 16 

subtilita ______ _ ------------------------- 39, 42, 48 

ovata. _________ ---------------------- _ 39 

dunoirensis ___ ---------------------------- 16 trinuclea ____________ ------------------ 39 

globosa _________ ------------- ___ ___________ 16 trinuclea _______________________ ----------- 33, 39 

sp-------------------- _ ---- _ _ __ _ _ __ __ __ __ _ 16 

BolaspideUa ____________________ -------------- 16 

Bolaspis _________ __ ------------- ______ ________ 16 

sp_ ------------------------------ 33, 39, 42, 48,49 Conant Creek _____________________________ 20, 21,44 

Conant Creek anticline_______________________ 3 

Page 

Condit, D. D., quoted________________________ B43 

Conocardium sp.----------------------------- 48 

Conularia SP---------------------------------- 49 

Cordilleran geosyncline --------------------- 6 

Cordylodus SP--------------------------------- 25 

Costatoria secradiata--------------------------- 49 

Cottonwood Creek oil and gas field ---------- 51 

CrepicephalUS------------------------- -------- 21 

tripunctatus _____ _ -- _ ---------------------- 16 

sp. ----------------- ______ ---------------- 16 

wne ------------------------------------- 16,21 

Cyathophyllum SP------------------------ ---- 33 

Cyclendoceras _______ --- _---------------------- 25 

Cyclocrinites __ -------------------------------- 25 

Cyrtorostia varicostata. ------------------------ 48,49 

SP---------------------------------------- 48 

Cyrtorostra SP--------------------------------- 49 

D 

Darby Formation ____ ----------------------- S3, S6 

contact with Madison Limestone.________ S7 

fossils. ______ ----------------------------- S9 

Darton, N.H., quoted_______________________ 43 

Darwin Sandstone Member of Amsden Formation.-------------------- 95, 97,99, 1,0 

oil and gas________________________________ 51 

Deadwood Formation.----------------------- 7,15 

Deadwoodia duris----------------------------- 16 

Death Canyon Limestone Member of Gros 

Ventre Formation _________ ---- 15, 17,18 

Death Canyon Member of Gros Ventre Formation--------------------------- 15 

DeUea. --------------------------------------- 16 

saginata. ___ ------------------------------

Deltopecten aviculatum------------------------

vanvleeti. _ --------------------------------

sp_--------------------------------------- Denison, R. H., quoted _____________________ _ 

Dentalium (Plagioglypta) canna ______________ _ 

(Plagioglypta) SP--------------------------

sp.---------------------------------------

16 

39 

49 

39 

30 

49 

42 

42 

Depass Formation---------------------------- 7,17 

Derbya multistriata. ___ ----------------------- 49 

plicatella ____ _ -- __ ------------------------- 49 

Derbyia crassa. _ ------------------------------ 42 

magna ______________ ---------------------- 48,49 

sp ________ -------------------------------- 42,48 

Devonian rocks------------------------------- S6, 50 

Dicellomus nanus----------------------------- 16 

sp _______________ ------------------------- 16 

Dictyoclostus ___ ------------------------------- 49 

hermosanus.------------------------------ 42 

portlockianus. ___ ------------------------- 39 

Dielasma sp. __ ------------------------------- 48 

Difficulty Shale Member, Goose Egg Formation.----------------------- __ _ 

Dikelocephalus __ ------------------------------

49 

16 

Dinorthis sp. ___ ------------------------------ 25 

Din woody Canyon ____________ U, 23, 26, !B7, S9, 1,1, 1,3 

Din woody Formation._------------------- 43, 1,9, 50 

Diphyphyllum _____________ ------------------ 33 

sp __________ ------------------------------ 33 

Disconformities between Tensleep and Atpsden Formations__________________ ;,:e 

Drepanodus curvatus__________________________ 25 

subrectus _____ ----------------------------- 25 

B57 
B58 

Page 

Dry Creek Shale Member of Gallatin Limestone_---------------------------- B20 

Du Noir Limestone Member of Gallatin 

Limestone _____________________ 18, ro, S1 

Du Noir Member of Gallatin Limestone______ 20 

Duncan, Helen, quoted_______________________ 25 

E 

East Canyon Creek__________________________ 18 

Echinauris tubhorridU8------------------------ 48,49 

Edmondia sp ___ ------------------------ ______ 49 

Ellipsocephaloides sp __ ------------------------ 16 

Elrathiella _______________________ ---------- __ _ 16 

Elvinia roemeri. ____ -------------------------- 16 

sp ___________________________ ------------ _ 16 

zone _______________________ --------------- 16, 21 

Ember Formation____________________________ 49 

Endothyra sp ___ ------------------------------ 39,42 

Entomis sp __ --------------------------------- 39 

Eocene rocks_-------------------------------- 2, 4, 6 

Eoorthis. ____________ -------- __ ------------ _ _ _ 16 

iddinosL __________ ------. _ -------------- _ 16 

iophon ______________________ -------------- 16 

remnicha. ____ --------------- ___ ---------- 16 

Ervay Member of Goose Egg Formation_____ 49 

fossils _________ --------------______________ 50 

Eumetria marcyL---------------------------- 33 

Euomphalopterus sp_ ------------------------- 25 

Euphemites subpapillosus_____________________ 48 

sp_ --------------------------------------- 48 

Euphemitopsis subpapillosus __________________ 48,49 

Euphemus carbonarius------------------------ 39,42 

Evaporite beds, Mississippian________________ 94 

F 

Faults _____________________________ ----------_ 3, 4 

Flathead Pass-------------------------------- 14 

Flathead Quartzite___________________________ 14 

Flathead Sandstone ____________ 7, 14, 16, 17, 18,30,39 

building stone ________________ ------------ 51 

contact with Gros Ventre Formation_____ 14 

contact with Precambrian rocks__________ 14 

Flathead shales _______________________________ 14, 15 

Folds ________________________ ----------------- 3, 4 

Forelle Limestone Member of Goose Egg 

Formation_---------------------- 49,50 

Fossils, Amsden Formation _____ ---------- 95,37,39 

Bighorn Dolomite _____________________ 21, 23,25 

Cambrian formations_____________________ 16 

Darby Formation __ ---------------------- 29 

Ervay Member of Goose Egg Formation.. 50 

Gallatin Limestone_______________________ 21 

Goose Egg Formation____________________ 48 

Madison Limestone ______________________ 33,40 

Minnekahta Limestone Member of Goose 

Egg Formation___________________ 50 

Park City Formation _____________________ 47,48 

Tensleep Sandstone______________________ 42 

Freezeout Shale Member of Goose Egg Formation.-------------------------- 49,50 

Fusispira injlata______________________________ 25 

Fusulina leeL_______________________________ 42 

sp. ----------------- _____ -------- _ ____ _ ___ 42 

Fusulinella gephyraea. __ ---------------------- 39 

sp ________ ------------- ____ --------- _ ____ _ 39 

Fusulinids___________________________________ 42 

G 

Gallatin Formation of Peale__________________ 15 

Gallatin Limestone ______________________ 7, 18, 19,22 

contact with Bighorn Dolomite___________ 20 

Du Noir Limestone Member __________ 18,20,21 

Du Noir Member________________________ 20 

fossils _____ ------------------------------- 21 

Open Door Limestone Member __________ 20,21 

Gas _________________ ------------_____________ 50 

Geology, economic___________________________ 50 

Glauconite in Cambrian units________________ 19 

Glendo Shale Member of Goose Egg Formation._--------------___________ 49 

INDEX 

Page, 

Glyphaspis _____ ------------------------------ Bl6 

Glyptotrophia ____________ --------------------- 16 

Goose Egg Formation ________________________ 49,49 

contact with Chugwater Formation______ 50 

Difficulty Shale Member.---------------- 49 

Ervay Member ____ ---------------------- 49 

fossils. __ ----------------------------- 50 

Forelle Limestone Member _______________ 49,50 

fossils __ ---------------------------------- 48 

Freezeout Shale Member----------------- 49,50 

Glendo Shale Member___________________ 49 

Little Medicine Member _________________ 49,50 

Minnekahta Limestone Member_________ 49 

fossils. ___ -------------------------___ 50 

Opeche Shale Member_------------------ 49 

Gorman, D. R., cited________________________ 40 

Grandeur Member of Park City Formation.. 47 

Granite Mountains___________________________ 3, 26 

Greger, D. K., quoted________________________ 35 

Grewinkia sp __ ------------------------------- 25 

Gros Ventre Formation ___ ----------------_ 7, 14,15 

contact with Gallatin Limestone_________ 18 

Death Canyon Limestone Member---- 15, 17, 18 

Death Canyon Member__________________ 15 

Park Shale Member ______________________ 15,18 

Wolsey Shale Member___________________ 15 

Gros Ventre Range ________ ---------- 14, 15, 18, 20,35 

Gypsum beds __________ ---------------------- 43 

H 

Halysites. ____ -------------------------------- 23 

gracilis. _____________ ----- __ -------------- 25 

micro porus. __ ---------------------------- 25 

(Catenipora) gracilis .. -------------------- 25 

Harding Sandstone of central Colorado_______ 21 

Helodus sp ________ --------------------------- 42 

Hesperothis sp __ ------------------- __ --------- 25 

Hiland Divide_______________________________ 2 

Hindeodella acuta----------------------------- 29 

sp_ --------------------------------------- 42 

Holophraoma sp. _ ---------------------------- 25 

Homalophyllites. ___ -------------------------- 33 

Horridonia ___ -------------------------------- 49 

Horse Creek__________________________________ 39 

Housia vacuna________________________________ 16 

Huenella. _ --------------------------------- _ _ 16 

Hustedia ___ ---------------------------------- 49 

phosphoriensis. --------------------------- 48,49 

Hyolithes._----------------------------------- 16 

sp ________________________ ---- ___ ----- _ __ _ 16" 

I 

Icriodus darbyens£8____________________________ 29 

mehli. _________ --------------------------- 29 

sp _________________________________ --- _ __ _ 29 

Idahoia sp. ____________ ----------------------- 16 wne ___________________ ------------------ _ 16 

Iddingsia occidentaliB------------------------- _ 16 

Idiognathodus sp_ ----------------------------- 42 

Introduction ___________________ ------ ____ ----_ 2 

Iron ore, hematite-bearing red shale.--------- 51 

Irvinoella flohrL __ ---------------------------- 16 

gibba. __ ---------- ___ ----------------- _ __ _ 16 

J 

Jefferson Limestone__________________________ 27 

K 

King, R. H., cited____________________________ 51 

Kingstonia sublettensis. _ ---------------------- 16 

sp_ ---------- ___ -------------------------- 16 

Kirk, Edwin, cited___________________________ 21 

L 

Lander, phosphate deposits __ ---------------- 51 

Lander Sandstone Member, Bighorn Dolomite ____ ------------------ 21, 22, 23,25 

Laramide deformation________________________ 50 

Laramie Mountains__________________________ 14 

Leda obesa_________________ ______ ________ _____ 49 

Page 

Leigh Dolomite Member, Bighorn Dolomite_ B22, S6 

Ligonodina sp ____ -------· ------------ ________ 25 

Lingulep£8 _____ _ ----------------------------- _ 16 

acuminatus. --------- ____ ---------- __ _ ____ 16 

acuminata meeki._________________________ 16 

Linnarssonella _______________ _____ ------------ 16 

modesta ________ ---------------------- ____ _ 16 

tennesseensis ______________________ ___ ---- _ 16 

transversa_________________________________ 16 

Linoproductus croneisi. _ ---------------------- 39 

prattenianus ___ --------------------------- 39, 42 

sp __ ------ ___________ ------------ ___ __ __ __ 39 

Lioclema SP---------------------------------- _ 48 

Liospira sp ________________ ------------------ _ 25 

Liostella sp __________________ ----------------- 48, 49 

Lithostrotion. ---------- __ ------------------- __ 33 

SP-------------------------------------- __ 33 

Little Medicine Member of Goose Egg Formation_-------------------------- 49,50 

Lochman-Balk, Christina, cited______________ 19 

Lodgepole Limestone ________ ---- __ .-------_-- 33 

M 

McKee, E. D., cited_________________________ 19 

Maclurina sp_________________________________ 25 

Madison Limestone. __________ 14, 18, 20, 23, 27, 29,40 

basal unconformity_______________________ 33 

contact with Amsden Formation_________ 39 

fossils ____ -------------------------------- 33, 40 

oil and gas. ___________________ ----------- 51 

Maladia sp. _____________ --------------------- 16 

Mallory, W. W., cited_______________________ 40 

Maroinifera splendens ____ -------------------- 39 

sp _______________________ -------------- _ -- 39 

Maryvillia ariston_____________________________ 16 

sp _________________________________ -- ____ - 16 

Maughan, E. K., cited_______________________ 42 

Maywood Formation________________________ 27 

Meekella SP----------------------------------- 48 

Mesolobus striatus. _____ ---------------------- 39 

Millerella sp _____________ --------------------- 42 

Minnekahta Limestone Member of Goose Egg 

Formation._--------------------- 49 

fossils. __ --------------------------------- 50 

Miocene rocks________________________________ 3 

Mission Canyon Limestone._---------------- 33 

Mississippian evaporite beds_________________ 94 

Mississippian rocks ____ ---------------------- 29 

Modocia sp_ ---------------------------------- 16 

Monocheilus sp __ --------------- ______ ----- _ __ 16 

Morrissey, N. S., quoted_____________________ 30 

Muirwoodia muUistriatus. -------------------- 48 

Murphy, J. F., cited_________________________ 22 

Myalina __ ------------- ____ ------------------- 49 

perattenuata _____________ ----------------- 49 

permiana ______________ ------------------- 49 

(Myalina) wyomingensis__________________ 48 

sp ________________________________ ----- _ _ _ 49 

N 

Naticopsis nana ____ -------------------------- 39 

Nautilus SP----------------------------------- 48 

Neoprioniodus sp __ --------------------------- 29 

Neospirifer cameratus_________________________ 42 

pseudocameratus.------------------------- 48,49 

sp _________________________________ -- _ _ _ _ _ 39 

North Casper Creek oil field._--------------- 18 

Nowood Member of Phosphoria Formation __ ------------------------- 42, 47, 49 

Nuctopsis poposiensis. ------------------------ 48 

Nucula pulchella. __ -------------------------- 48 

sp __________ ---------------- ______ ------- _ 49 

Nyctopora sp_ -------------------------------- 25 

0 

Obolus zentus.-------------------------------- 16 

sp _ _ _ __ __ __ _ _ __ ____ __ __ __ __ __ __ __ __ _ _ __ _ _ _ 16 

OiL_----------------------------------------- 60 

Oistodus sp ________ --------------------------- 25 

Oligocene rocks------------------------------- 4 
Page· 

Opeche Shale Member of Goose Egg Formation ____ -------------_____________ B49 

Open Door Limestone Member of Gallatin Limestone ________________________ 20,21 

Orbiculoidea wyomingensis_____________________ 39 

(Roemerella) utahensis____________________ 48 sp ________________________________________ 48, 49 

Ordovician rocks._------------------------ 21, 29,50 

Orthotetes kaskaskiensis. __ . _ ------------------ 33 

sp_ ---------- ____ -------------- __________ . 33, 39 

Orygmaspis ... ________________ . ____ __________ _ 16 

Owl Creek Canyon ___________________________ 20,21 

Owl Creek Mountains _______ 4, 7, 14, 17, 20, 21, 29,90, 

35, 37, 41, 43,47 

Ozarkodina regularis. _________ . _______ -------- 29 

sp. A---------------------------------____ 25 sp. B_____________________________________ 25 

p 

Palaeophyllum stokesL----------------------- 25 Paleowic rocks _____________________________ 2, 9, 4, 6 

classification._. __________ .--------------_ 7 

reservoirs for oil and gas__________________ 50 

Paleozoic structure.-------------------------- 50 

Palmatolepis gonioclymeniae __ ---------------- 29 

rugosa __________ -------------.. ----------- 29 

Panderodus gracilis. _____________ ------------- 25 

Parabolinoides_ ------------------------------- 16 

Parallelodon tenuistriatus_ -------------------- 49 

sp_ --------- _____ ---- ________ ---------- __ _ 39 

Paraparchites SP------------------------------ 39 

Park City Formation_-------------------- 49, 44,49 

contact with Dinwoody Formation_______ 47 

fossils. ___ -------------------------------- 47, 48 Grandeur Member_______________________ 47 

oil and gas_______________________________ 51 

phosphate rock___________________________ 51 

Park Shale Member of Gros Ventre Forma- tion ______________________________ 15,18 

Patella sp ____ - --~----- --- _ -------------- ___ _ _ 48 

Patellostium sp ___ --------- ___ ---------------- 48 

Pathfinder uplift. __ ------------------________ 50 

Paucicrura sp. _- -------------------------- ___ 25 

Pennsylvanian rocks __ ------------------- ____ 95,47 

Permian rocks________________________________ 49 

phosphate rock___________________________ 51 

Peronopsis. __ -------------------------- ___ .__ 16 

Pharkidonotus percarinatus ____ --------------- 39 

Phillipsia SP---------------------------------- 33 

Phosphate deposits near Lander______________ 51 

Phosphate rock, Park City Formation_______ 51 

Permian rocks____________________________ 51 

Phosphoria Formation_______________________ 49 

Nowood Member __ ------------------- 42, 47,49 

radioactive deposits______________________ 51 

Phricodothyris sp _____ -- --------- ____ ------ __ _ 39 

Phyllopora. ___________ ------------- __ _ ____ _ _ _ 49 

sp. ----------------------------- _ __ _ _ __ ___ 48 

Pierocephalia n. SP---------------------------- 16 

Pinna peracuta_ ------------------------------ 49 

Plagioglypta __ ------------ ____ --------- ____ ___ 49 

canna __________ ------------------- _______ 48, 49 

sp. ---------------··---------------- _______ 39, 49 

Platystrophia sp ___________ ------------- ______ 25 

Pleurophorus occidentalis______________________ 49 

pricei. _______ ______ --- _ __ ___ _ _ ___ ___ ___ ___ 49 

subcostatus _____ ------------ _ ____ ___ _ __ ___ 48 

SPP--------------------------------- 39, 42, 48,49 

Pleurotomaria ______ ------------------------ __ 49 

sp_ ------ _ ----- ____ ---------------- _______ 42, 48 

Plicatoderbya ______________ ---------- __ ___ _ ___ 49 

magna ____________________ ---------------- 48 

Pliocene rocks---------------_________________ 3 

Polidevcia bellistriata _______ ------------- ___ ___ 49 

Polygnathus inornata ___ ---------------------- 29 

nodocosfata ___ ---------------------- __ ___ _ 29 

triangularis ___________ --------------______ 29 

varinodosa. _ --------- __ -------- _____ __ ____ 29 

wyomingensis __ --- _ -------------------- ___ 29 

INDEX 

Page. 

Precambrian crystalline rocks. ______ B3, 6, 14, 19,40 

Previous work ____ --------------------------- 2 

Prioniodina SP------------------------------ __ 25 

Prioniodus SP--------------------------------- 42 Productus cora ________________________________ 39,42 

hermosanus ______________________ __ ------- 39 

parviformis. __ -------------------- _ ------- 33 semireticulatus ___________ -------- __ _ ___ ___ 42 

sp. __________ ----------------------------- 42 

Prosaukia sp ______________ -------------- _____ 16 

Prozacompsus sp ______ ----------------------- 16 

Pseudomonotis hawni. _ ----------------------- 42,48 

sp _______ ----------------~--------- ------- 48 

Pteria longa ________ -------------------------- 39 

sp_ ----------------- __ -------------- ___ 39, 48, 49 

Pugnoides ottumwa___________________________ 33 

Punctospirifer __ ------------------------------ 49 

pulchra __________ ______ ------------------- 48 sp_ ____________ __ _ _ __ _ ___________ __ _______ 39 

Pustula nevadensis---------------------------- 48,49 

Ptychaspis-Prosaukia zone____________________ 16 

R 

Radioactive deposits, Phosphoria Formation_ 51 

Tensleep Sandstone __ -------------------- 51 

Rattlesnake Hills ___ ------------------------- 18,50 

Receptaculites ______________ ------------------- 25 

articus _______ ________ --------------------- 25 sp_ _ _ ___ _ __ _ _ __ __ _ _ _ _ __ __ ___ _ __ _ _ __ _ _ __ __ _ 25 

Relief._--------------- ____ ------------------- 2 

Resserella tersa __________ -------------- ___ ---- 25 

Rhombopora sp ________ ----------------------- 48 

Rhynchotrema capa.t. _ ------------------------ 25 

increbescens ____ ____ ----------------------- 25 

Robinson, G. D., cited_______________________ 19 

Ross, R. J., Jr., cited _______________ ---------- 25,26 

s 

Sacajawea Formation ___ --------------------- 30,35 

Sandberg, C. A., cited __ ------------------ 27, 29,33 

Sando, W. J., cited _____________________ 30, 33, 39,40 

Sanguinolaria SP------------------------------ 48 

Sanguinolites sp __ ---------------------------- 48,49 

Saratogia sp __ -------------------------------- 16 

Scaphellina concinnus_________________________ 48 

sp_ --------------------------------------- 48, 49 

Schizodus canalis. __ -------------------_______ 48 

ferrieri. ____________ --------------------- __ 49 

wheeleri. ___ ------------------------------ 48,49 

SP------------------------------------- 39, 48, 49 

Scolithus. ___ --------------------------------- 16 

Semicircularia arcuata __ ---------------------- 16 

Shaw, A. B., cited._---------------------- 15, 19,20 

Shedhorn Sandstone ___ ---------------------- 49 

Sheep Mountain_____________________________ 26 

Silurian rocks __ --------------------__________ 29 Sinks Canyon ________________________________ 27,30 

Solenomya sp ___ ------------------------------ 48 

Sowerbyella sp _________ -------------- __ _______ 25 

Spathognthodus aculeatus ___ ------------------ 29 

jugosus. _ ---------------------------- _ __ __ 29 

Sphenosteges hispidus __ ----------------------- 48,49 

sp_ --------------------.------------------ 48, 49 

Spirifer centronatus- ---------------- ___ ____ ___ 33 

keokuk ______ -------------------------_____ 33 

madisonensis. _____ ----------------------- 33 

occidentalis_ ~ _- ----------------- _ __ _______ 39 

opimus.------------------------------- ___ 39, 42 

pellaensis ___ ----------------------- ____ _ __ 33 

rockymontanus ___ ------------------ _______ 39,42 

shoshonensis _______ ---------------- ____ ___ 33 

wellerL--------------------------- _______ 39 

sp_ --------------------------------------- 33, 39 

Spiriferina brownL___________________________ 33 

kentuckensis __ ------------------------- ___ 48,49 

pulchra ____________ ------------------- ____ 48,49 

solidirostris ______ ---------------------- ___ 33 

sp_ ------------------------------------ ___ 49 

B59 

Page, 

Spyoceras rarum------------------------------ B25 Squamularia perplexa_________________________ 42 

Stajfella sp ___________ ------------------------ 42 

Stearoceras. _______ --------------------------- 48 

Stenopora ____ ------------------------------- _ 49 

SP----------------------------------------- 48 

Straparolus (Euomphalus) plummerL-------- 42 

Stratigraphy ___ ------------------------------ 6 

Streptelasma corniculum._-------------------- 25 

foerstet_ __ -------- _---- ___ ----------------- 25 

robustum_ -------------------------------- 25 sp. ________________________________ ---- _ __ 25 

Streptognathodus SP--------------------------- 42 

Strophostylus sp_ ----------------------------- 39,48 

Structure, Paleowic ____ ---------------------- 60 

Stutchburia sp __ ------------------------------ 48, 49 Sweetwater Canyon __________________________ 18,20 

Synthrophia alata __ --------------------------- 16 Syringopora surcularia________________________ 33 

sp _______ --,----------- __ ________ __ _______ 33 

T 

Taenicephalus. _ ----- ___ -- ______ --------------

cordillerensis------------------------------- zone _____ ------------------ ____ ---- ______ _ 

16 

16 

16 

Tensleep Sandstone __ ------------------ 95, 97, 40,48 

contact with Park City and equivalent 

rocks----_------------------------ 41 

fossils. __ --------------------------------- 42 oil and gas_______________________________ 51 

radioactive deposits______________________ 61 

Tentaculites sp _____ --------- ____ ------------- 49 Teton Range _________________________________ 18,25 

Tetracamera subcuneata_______________________ 33 

Textrataxis millsapensis_______________________ 39 

Thaerodonta sp_ ------------------------------ 25 Thomas, H. D., cited __________________ 43,47,48,50 

Three Forks Shale. __ ------------------------ 27 

Topography---------------------------------- 2, 97 

Triassic rocks. __ ----------------------------- 49,49 

Trichonodella sp __ ------ _____ ----------------- 25 

Pricrepicephalus ________ ---------------------- 16 

tripunctus. ___ ---------------------------- 16 

sp _ -------------- _________________ --- _ ---- 16 

Triplophyllites ____________ -------- ------------ 33 

sp----------------------------------------

'llriticites kellyensis _______ ---------------------

sp-------------------------- --------------

Trochonema umbilicatum ___ ------------------

u 

Unconformity between, Bighorn Dolomite 

33 

42 

42 

25 

and Darby Formation____________ 29 

Bighorn Dolomite and Madison Limestone ____________ ----------------- 29 

Darby Formation and Madison Limestone ____ ------------------------- 27 

Gallatin Limestone and Bighorn Dolomite ___ --------------------------- SO 

Gros Ventre Formation and Gallatin 

Limestone________________________ 18 

Tensleep Sandstone and Park City For- mation ________________________ --- 41 

w 

Waagenoconcha montpelierensis ___ ------------ 48 

Warm Spring Canyon________________________ !89 

Warm Spring Creek ____________________ 15,20,23,27 

Warm Spring Lake___________________________ !89 

Warm Spring Mountain. __ ------------------ 20 

Washakie Range _______________ 4,14,17,20,29,35,44 

Wedekindellina sp __ -------------------------- 42 

Wellerella osagensis--------------------------- 39,48 

sp ___ ------------------ ________ ----------- 39 

Westonia. ------------------------------------ 16 

dartoni. _______ --------------------------- 16 

ella.______________________________________ 16 
B60 

Pagt> 

Wilbernia SP---------------------------------- B16 

Wind River Canyon_--------------- 14, 19, 21, SS, 30 

Wind River drainage system___________________ 2 

Wind River Range_ 3, 20, 22, 26, 27, 30, 36, 37, 39, 40, 44 

Wind River structural basin, defined_________ S 

Windy Gap___________________________________ 39 

Wilkingia sp ____ ------------------------ ______ 48,49 

INDEX 

Page 

Wolsey Shale Member of Gros Ventre Formation __ ---------------------------- B16 

Woodward, T. C., quoted____________________ 18 

Word Formation_____________________________ 47 

X 

Xenocheilos spineum__________________________ 16 

0 

y 

Yochelson, E. L., quoted ____________________ _ 

z 

Zaphrentis amsdensis __ ----------------- _____ _ 

Zygospira jupiterensis ______ -------- ___ - ------

U.S. GOVERNMENT PRINTING OFFICE: 1966 0-205-540 

Page 

B47 

33 

25