Geology of the Crazy 

Woman Creek Area 

Johnson County 

Wyoming

By RICHARD K. HOSE

A CONTRIBUTION TO ECONOMIC GEOLOGY

GEOLOGICAL SURVEY BULLETIN 1027-B

Prepared as part of a program 

of the Department of the Interior 

for development of the Missouri 

River basin

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1955
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price $1.75 (paper cover)
CONTENTS

Page

Abstract..__ _ _--__-__-______-_-_-__________-__-_-_-____----_____-- 33

Introduction, _____________________________________________________ 35

Location and extent of area_____________________________________ 35

Purpose and scope of report_____-___________-_____--__-____-____ 36

Field work and map compilation. _______________________________ 36

Acknowledgments. ____________________________________________ 36

Previous investigations,________________________________________ 37

Geography______________________________________________________ 38

Surface features.______________________-_______-_---__--------- 38

Water supply and drainage-____________________________________ 40

Climate and vegetation_______________________________________ 42

Accessibility and settlement___-_-___-___-_______-_-_--_____-__-_ 42

Stratigraphy._____________________________________________________ 42

i General features.._______-___-____-__-_-____-___-____-_------_- 42

Location of measured sections..-..-_____________________________ 43

Pre-Cambrian rocks__________________________________________ 43

Paleozoic rocks.--___--______-_-_________-______-__-_-__---_-__ 44

Flathead sandstone._-__-__-_-_-____________--_______---_-_ 44

Gallatin limestone and Gros Ventre formation, undivided_______ 44

Bighorn dolomite-_________________________________________ 45

Madison limestone_______________________________________ 48

Amsden formation,,_______________________________________ 49

Tensleep sandstone._______-________________--___-__---__-_ 49

Permian red shale and gypsum sequence______--___-____-__-- 50

Mesozoic rocks________________________________________________ 51

Chugwater formation. _____________________________________ 51

Gypsum Spring formation__'________________________________ 52

,, Sundance formation________-___-___---___--__-__--__-_-_--- 54

Morrison formation,_______________________________________ 55

Cleverly formation. _______________________________________ 56

Skull Creek shale________________________________._________ 57

Newcastle sandstone.______________________________________ 58

Mowry shale________________-_-________-___-____-__------- 58

Frontier formation.._______________________________________ 59

Cody shale_______________________________________________ 61

Parkman sandstone._______________________________________ 64

Bearpaw shale. ___________-___________-__-__--__--___--_-- 64

Lance formation.__________________________________________ 65

Cenozoic rocks________________________________________________ 66

Fort Union formation._______________________-_---__--_---- 66

Wasatch formation. _______________________________________ 67

White River formation_________________-____-____-----__--_ 70

Quaternary rocks__________________________________________ 71

in
IV CONTENTS

	Page 

Structure. _____-_,____-_--____----__-_______________-___---_______ 73

Regional features.,____________________________________________ 73

Folds and faults_________________-_____--______________________ 74

Structural history._____________________________________________ 77

Economic geology.______-_____-_-___---___-_---____-____---____-__ 78

Oil and gas potentialities.________________________________________ 78

Coal_______ ___-_--____-.-_--------_.-_.__-- -__---___._-- 81

General features___________________________________________ 81

Coal in T. 47 N., R. 81 W__________________________________ 83

Coal in T. 48 N., R. 80 W__________________________________ 83

Coal in T. 49 N., R. 80 W__________________________________ 85

Manganese. __________________________________________________ 88

Allanite______________________________________________________ 88

Bentonite_ ___________________________________________'_________ 89

Construction materials.________________________________________ 89

Stratigraphic sections of Mesozoic and Paleozoic rocks. ________________ 91

Literature cited _ __________________________________________________ 114

Index,_________-_____-.______-____________-__-_-----________-____ 117

ILLUSTKATIONS

[Plates 6-13 in pocket]

PLATE 6. Geologic map and sections showing structure contours of the Crazy 

Woman Creek area, Johnson County, Wyo.

7. Index map showing location of Crazy Woman Creek area and oil and 

gas fields in western Powder River Basin.

8. Generalized section of sedimentary units exposed in the Crazy 

Woman Creek area.

9. Index map and correlation of electric logs of the Skull Creek shale.

10. Correlation diagram of Cretaceous formations of the Black Hills and 

the Crazy Woman Creek area.

11. Sections of coal beds measured in T. 47 N., R. 81 W.

12. Sections of coal beds measured in T. 48 N., R. 80 W.

13. Sections of coal beds measured in T. 49 N., R. 80 W.

FIGURE 13. Index map of Wyoming showing location of the Crazy Woman Page 

Creek area______-______________-_-____---_________-__ 35

14. View of east flank of the Bighorn Mountains showing prominent piedmont suriaces________________________________

15. Massive dolomitic part of the Bighorn dolomite. ___________

16. Contact between the dolomitic and sandstone units of the

Bighorn dolomite_-___________-_-_____________________ 46

17. View of the east flank of the Horn at the South Fork Crazy

Woman Creek_ ______________________________________ 48

18. Cross section showing unconformable relationship of Gypsum 

Spring formation to older and younger units in western 

Powder River Basin __________________________________ 53

19. Cross section showing relationship of Gypsum Spring formation to older and younger units from the western Wind 

River Basin__________________________________________ 53

20. Diagram showing the occurrence of faunal zones of the Black

Hills region in the Frontier formation-___-_-___-______-_ 60
CONTENTS

Page

FrouKE 21. Approximate contact between the Kingsbury conglomerate 

member of the Wasatch formation and the Fort Union 

formation ___________________________________________ 68

22. Conglomerate of the White River formation on Canyon Fork

Powder River________________________________________ 71

23. Gravel of terrace level 2 (Qtg2 ) on the North Fork Crazy,

Woman Creek_________________________________.._ 72

24. View of the abrupt change from moderate to high dips in Paleozoic strata on the North Fork Crazy Woman Creek___--_- 75

25. Geologic map of the Bighorn Mountains showing three major

structural segments.__________________________________ 79

26. Generalized section showing average interval between coal

beds of T. 47 N., R. 81 W______.__._.____.____.___ __ 82

27. Generalized sections showing average interval between coal

beds in Tps. 48 and 49 N., R. 80 W_ ____________________ 85

TABLES

TABLE 1. Discharge of the North and Middle Forks Crazy Woman Creek, 

October 1948 to September 1949_.________ _________-___

2. Average annual and monthly precipitation and temperature in 

the Crazy Woman Creek area____________________________

3. Coal reserves in T. 47 N., R. 81 W___ ______________________

4. Coal reserves in T. 48 N., R. 80 W_ ________________________

5. Coal reserves in T. 49 N., R. 80 W__..__..__._.__...____...

6. Spectroscopic analysis of allanite. ___--_-_-__________--_--__

Page 

41

41

84

86

87

90

A CONTRIBUTION TO ECONOMIC GEOLOGY

GEOLOGY OF THE CRAZY WOMAN CREEK AREA 

JOHNSON COUNTY, WYOMING

By RICHARD K. HOSE

ABSTRACT

The Crazy Woman Creek area comprises about 576 square miles along the 

west-central margin of the Powder River Basin and the east-central flank of 

the Bighorn Mountains in Johnson County, Wyo. Pre-Cambrian granitic rocks 

form the high rugged core of the Bighorn Mountains. Resistant units of the 

Paleozoic sequence support the high essentially north-trending scarp along the 

east flank of the Bighorn Mountains; the softer rocks of the Permian red 

shale and gypsum sequence and younger units underlie the Powder River Basin.

Rocks of every system except the Silurian and Devonian are present in the 

Crazy Woman Creek area. Paleozoic rocks are as much as 2,550 feet thick 

and are dominantly of marine origin. Mesozoic rocks attain a maximum thickness of about 9,350 feet and are of marine, brackish water, and nonmarine origin; 

marine rocks are the most common. The Cenozoic rocks, which have an aggregate thickness of more than 5,000 feet, are wholly of continental origin.

The oldest sedimentary unit, the Flathead sandstone of Middle Cambrian 

age, is about 250 feet thick. It is overlain by the Gros Ventre formation and 

Gallatin limestone undivided, aggregating 550 feet in thickness and ranging 

in age from Late Cambrian to Early Ordovician. The next younger unit is the 

Bighorn dolomite, which ranges in thickness from about 150 to over 350 feet 

and in age from Middle to Late Ordovician. The 550-foot Madison limestone of early Mississippian age unconformably overlies the Bighorn dolomite. 

It is succeeded by the Amsden formation of Mississippian (?) and Pennsylvanian 

age. The Ten sleep sandstone of early Pennsylvanian (Des Moines) age overlies 

the Amsden formation and is about 350 feet thick. The Tensleep sandstone is 

overlain by the Permian red shale and gypsum sequence, which is about 250 

feet thick.

The oldest Mesozoic unit is the nonmarine Chugwater formation of Triassic 

age. This formation ranges from 750 to more than 800 feet in thickness and 

consists dominantly of red siltstone, sandstone, and shale. The Chugwater formation is uuconformably overlain by the Gypsum Spring formation of Middle 

Jurassic age, which ranges in thickness from about 120 feet to a wedge edge 6 

miles south of the mapped area. Unconformably overlying the Gypsum. Spring 

formation is the Sundauce formation of Late Jurassic age, which is approximately 285 feet thick and consists of sandstone, shale, and minor amounts of 

oolitic limestone. The nonmarine Morrison formation of Late Jurassic age,

33
34 CONTRIBUTIONS TO ECONOMIC GEOLOGY

about 185 feet thick, overlies the Snnclance formation, and consists dominantly 

of varicolored claystones and thin beds of siltstone and sandstone. This unit 

is overlain by the Cloverly formation, which is of Early Cretaceous age and 

ranges in thickness from 135 to 165 feet. The Skull Creek shale of Early 

Cretaceous age, which overlies the Cloverly formation, is about 165 feet thick. 

The Newcastle sandstone of Early Cretaceous age, next above the Skull Creek 

shale, is about 40 feet thick. The Mowry shale of Early Cretaceous age overlies 

the Newcastle sandstone and is about 500 feet thick.

The Frontier formation of Late Cretaceous age, which overlies the Mowry 

shale, is about 480 feet thick and consists dominantly of interlaminated darkgray shale and light-gray sandstone, capped by a resistant conglomeratic sandstone. The next younger unit, the Cody shale of Late Cretaceous age, is about 

8,670 feet thick; 925 feet below the top is the 200-foot Shannon sandstone 

member. The Parkman sandstone of Late Cretaceous age overlies the Cody 

shale and is 720 feet thick. The next younger unit, the Bearpaw shale of Late 

Cretaceous age, is 200 feet thick and consists of drab-colored silt shale.

The Lance formation of Late Cretaceous age, which ranges in thickness from 

1,950 to 2,200 feet, overlies the Bearpaw shale and consists of interbedded 

sandstone, siltstone, and shale.

The Fort Union formation of Paleocene age rests on the Lance formation and 

is about 3,900 feet thick. The Wasatch formation of early Eocene age rests 

apparently conformably on the Fort Union formation throughout most of the 

mapped area, but its mountainward basal equivalent, the Kingsbury conglomerate member of the Wasatch formation, unconformably overlies successively 

the Fort Union formation, the Lance formation, the Bearpaw shale, and the 

Parkman sandstone. The next higher mountainward member of the Wasatch 

formation, the Moncrief, rests unconformably on the Kingsbury conglomerate 

and older units just north of the Crazy Woman Creek area. The White River 

formation of early Oligocene age is restricted to small outliers on the subsummit uplands of the Bighorn Mountains and consists mainly of marlstone, 

conglomerate, and soft brown bentonitic clay. Quaternary deposits, dominantly 

terrace gravels, alluvium and landslide debris, are widespread.

Structural activity during the time after the pre-Cambrian and before the 

Laramide orogeny began was limited to mild regional tilting, uparching, or 

uplift followed by erosion and subsequent depression. This mild tilting resulted in unconformities that are recognizable only by a study of the regional 

relationships of the formational units. These unconformities are present at 

the base of the Madison limestone, the Permian red shale and gypsum sequence, 

at the base of the Gypsum Spring formation, and at the base of the Sundance 

formation.

Laramide orogeny in the Bighorn Mountains began during Fort Union time. 

Before the end of Fort Union time the central portion of the Bighorn Mountains 

had been elevated and eroded in part to the pre-Cambrian. A record of uplift 

at the end of Fort Union time is preserved in the angular unconformity at the 

base of the Kingsbury conglomerate member of the Wasatch formation. After 

Kingsbury time another uplift occurred which tilted the Kingsbury conglomerate 

member of the Wasatch formation as much as 60 degrees. The Moncrief member of the Wasatch formation, which overlies the Kingsbury conglomerate 

member unconformably was not affected by folding. However thrust faults 

have moved older rocks up and over the Moncrief member.

Strata in the Crazy Woman Creek area generally dip eastward, and except 

for the almost flat-lying Wasatch formation crop out as relatively narrow northtrending bands. Structural relief resulting from this eastward dip is as much
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 35

as 18,000 feet. The mapped area contains 5 major anticlinal folds and one 

structural terrace. Faults with a few exceptions ore confined to the competent 

Paleozoic strata.

Oil and gas have been produced in the Billy Crook anticline, but to date not 

elsewhere in the area. A small manganese deposit and a deposit of allanite 

are present at the northern end of the Horn. Bentonite beds are common in 

the Mowry shale and the Frontier formation. Subbituminous coal beds .from 

2.5 to 15 feet thick underlie three townships, and total measured, indicated, and 

inferred coal reserves are more than one billion tons.

INTRODUCTION

LOCATION AND EXTENT OF AREA

The Crazy Woman Creek area lies south of the town of Buffalo in 

Johnson County, Wyo., and includes 16 townships, approximately 576 

square miles. The location of the area mapped is shown on the index 

maps (fig. 13 and pi. Y). The western boundary extends southward 

along the western edge of K. 83 W. along the east flank of the Bighorn 

Mountains to the vicinity of the Horn, a prominent structural and 

physiographic feature of the Bighorn Mountains. The southern 

boundary extends eastward along the southern edge of T. 46 N. well 

out into the Powder River Basin. The eastern boundary lies along 

the eastern edge of R. 80 W. and the northern boundary along the 

northern edge of T. 49 N.

45

K YELLOWSTONE I/'

44

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 Buffalo

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FIGURE 13. Index map of Wyoming showing location of the Crazy Woman Creek area.
36 CONTRIBUTIONS TO ECONOMIC GEOLOGY 

PURPOSE AND SCOPE OF REPORT

The present study is one of oil, gas, and coal investigations made by 

the U. S. Geological Survey as a part of a program of the Department 

of the Interior for the development of the Missouri Eiver basin. 

Basic geologic data for use in oil and gas exploration and coal reserve 

evaluation include determinations of thickness, lateral variation, and 

relative age of stratigraphic units; present structural configuration 

and tectonic history of the area; extent, thickness, and attitude of 

numerous coal beds; and distribution, thickness, and types of terrace 

deposits. These data contribute to an appraisal of regional geologic 

problems and hence to a better regional evaluation of oil and gas 

possibilities.

FIELD WORK AND MAP COMPILATION

This report is based on field work done during the field seasons of 

1950 and 1951 and 2 weeks in 1952. Field data were compiled on 

aerial photographs at a scale of 1: 31,680. Data were transferred to a 

poly conic projection upon which was superimposed a land grid. The 

land grid was plotted from data provided by the U. S. Bureau of Land 

Management. The only surveys in approximately 7 townships were 

made in 1882; few of the section corners were recovered. The remaining 9 townships were resurveyed at least in part in 1927, 1947, and 

1948, and all quarter and section corners are marked with brass caps. 

Geologic mapping in the westernmost tier of townships was transferred to preliminary topographic maps which were prepared for the 

U. S. Bureau of Eeclamation by Fairchild Aerial Surveys, Inc., and 

then transferred to the base map. Four first-order U. S. Geological 

Survey and U. S. Coast and Geodetic Survey triangulation stations 

are located in the area. A subordinate triangulation net was established with planetable and alidade. Altitudes for structure contouring 

were established with an aneroid barometer. Stratigraphic sections 

of major units were measured with planetable and alidade; smaller 

units were measured with compass and tape.

ACKNOWLEDGMENTS

During the 1950 field season the writer was assisted by Theodore 

Scott, who mapped a substantial portion of the Paleozoic and Quaternary rocks. In 1951, M. J. Bergin and E. S. Sears assisted in mapping 

Tertiary beds. Bergin also mapped some of the Paleozoic rocks of the 

Horn area and Quaternary rocks in the eastern part of the area. 

W. J. Mapel collaborated with the writer in measuring several stratigraphic sections of Mesozoic rocks along the west margin of the 

Powder Eiver Basin. All phases of the investigation were supervised
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 37

by J. D. Love, whose cooperation and suggestions greatly facilitated 

the preparation of this report.

Identification of fossil collections and determination of their ages 

was done by paleontologists of the Geological Survey. Trilobites 

from the Cambrian and a brachiopod from the Lower Ordovician 

were identified by A. R. Palmer. Palmer and Josiah Bridge jointly 

identified dendroid graptolites from the Gallatin and Gros Ventre 

formations, undivided. Mollusks and a sponge from the lower part 

of the Bighorn dolomite were identified by Josiah Bridge and corals 

by Edwin Kirk. Faunas from the upper part of the Bighorn dolomite 

were identified by Jean Berdan and Josiah Bridge. Collections from 

the Madison limestone and Amsden formation were studied by Helen 

Duncan and J. S. Williams. R. W. Imlay identified mollusks from 

the Gypsum Spring and Sundance formations and Edwin Kirk a 

crinoid from the basal part of the Sundance formation. All Cretaceous fossils were identified by W. A. Cobban and J. B. Reeside, Jr. 

Eocene fresh-water mollusks were identified by T.-C. Yen and Eocene 

vertebrates by M. J. Hough. C. L. Gazin of theU. S. National Museum 

identified Hyposodus simplex.

A. H. Makela described, thin sections of crystalline rocks. Three 

analyses of manganese-bearing rock were made by Dr. H. G. Fisk, of 

the National Resources Research Institute. The report was prepared 

with the cooperation of the Geological Survey of Wyoming and the 

Department of Geology, University of Wyoming.

During 1859 and 1860 a reconnaissance of a large area of northern 

Wyoming, Montana, and the western parts of North and South Dakota 

was carried out under the direction of Capt. W. F. Raynolds. F. V. 

Hay den (1869) who accompanied Raynolds, compiled a generalized 

geologic map of the region of which the Crazy Woman Creek area is 

a small part. In 1904 Darton defined the stratigraphic units of the 

Bighorn Mountains. Later (1906) Darton revised some of his preliminary units and published a map and comprehensive report on the 

entire Bighorn Mountains and a peripheral belt in which major 

physiographic, structural, and stratigraphic units were outlined. Gale 

and Wegemann (1910) made a reconnaissance examination of Tertiary 

coals in this and adjoining areas. In 1912 Wegemann studied the 

Sussex coalfield, the northern part of which extends into the Crazy 

Woman Creek area. Wegemann (1913) also studied coals in the 

Barber coalfield, which adjoins the Crazy Woman Creek area on the 

northeast. Wilson (1938) mapped the Tensleep fault, which trends 

essentially east across the Bighorn Mountains from Tensleep, Wyo., to 

the northern part of the Horn. Demorest (1941) mapped Paleozoic
38 CONTRIBUTIONS TO ECONOMIC GEOLOGY

and Triassic units along the east flank of the Bighorn Mountains from 

Clear Creek south to the Horn. Sharp (1948) made a detailed study 

of the Moncrief member of the Wasatch formation along the east flank 

of the Bighorn Mountains. Richardson 1 mapped an area which included a portion of the Horn. Detailed geologic mapping was done by 

Mapel in 1949 and 1950 in the Lake DeSmet area to the north; this is 

also a part of the Geological Survey's oil, gas, and coal investigations 

program.

GEOGRAPHY

SURFACE FEATURES

The Crazy Woman Creek area covers parts of two major topographic provinces: the east flank of the Bighorn Mountains and the 

western margin of the Powder River Basin. The Bighorn Mountains 

rise abruptly from about 5,900 feet to more than 8,200 feet above sea 

level in a distance of 2 to 3 miles. Altitudes in the basin range from 

about 4,200 feet in the eastern part of the mapped area to about 5,900 

feet above sea level along the base of the Bighorn Mountain front, over 

a distance of about 19 miles. The east flank of Bighorn Mountains 

is composed of a sequence of resistant Paleozoic rocks overlying the 

pre-Cambrian core of the range. The top of the Tensleep sandstone 

can be regarded as the boundary between the mountains and the 

basin. The Powder River Basin has been etched out of more easily 

eroded sedimentary rocks ranging in age from Permian through 

Mesozoic to Eocene. Kingsbury Ridge, which is composed of the resistant Kingsbury conglomerate member of the Wasatch formation, 

forms a divide in the northernmost part of the area between the Clear 

Creek drainage 6 miles north of the mapped area and the Crazy 

Woman Creek drainage. Resistant units in the upper part of the Fort 

Union formation and the lower part of the Wasatch formation form a 

discontinuous north-trending ridge about 3 to 6 miles east of U. S. 

Highway 87.

Piedmont interstream surfaces with relief of as much as 500 feet are 

characteristic of the entire Bighorn Mountain front (fig. 14). Basinward, however, these older surfaces have been eroded, leaving only 

remnants.

Streams head high in the Bighorn Mountains and flow eastward 

through steep youthful canyons cut in the resistant rocks which form 

the east flank of the range (fig. 15). As the streams leave the mountain canyons, they flow with progressively decreasing gradient into the 

Powder River Basin where they occupy valleys flanked by more mature topography.

1 Richardson, A. L., 1950, Geology of the Mayoworth region, Johnson County, Wyo.: 

Unpublished Master of Arts thesis in flies of Univ. of Wyoming library.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 39

FIGURE 14. View of east flank of the Bighorn Mountains showing prominent 

piedmont surfaces.

FIGURE 15. Canyon of the North Fork Crazy Woman Creek cut through massive dolomitic 

part of the Bighorn dolomite.
40 CONTRIBUTIONS TO ECONOMIC GEOLOGY

»

. Major streams are the North, Middle, and South Forks Crazy 

Woman Creek in the north, central, and southern parts of the area; 

Muddy and Billy Creeks south of the North Fork Crazy Woman 

Creek; and Beaver Creek between the Middle and South Forks Crazy 

Woman Creek. All streams flow into the forks of Crazy Woman 

Creek or the main drainage which is designated Crazy Woman Creek *^ 

east of the juncture of the Middle Fork with the North Fork. The 

use of irrigation waters taken from Billy Creek, Beaver Creek, and 

the South Fork Crazy Woman Creek is so extensive during the summer IT 

months that these streams become intermittent in their lower courses. I

Stream gradients in the last mile of flow through the mountains * 

range from a minimum of 250 feet per mile for the North Fork Crazy £^ 

Woman Creek to a maximum of 1,100 feet per mile for the South Fork 

Crazy Woman Creek. This gradient difference may be partly due to « 

the fact that the North Fork Crazy Woman Creek has the greatest W. 

discharge in the area, whereas the South Fork Crazy Woman Creek has 

one of the lowest. The first mile of flow in the basin is on gradients i v 

ranging from 210 feet per mile for Muddy Creek to as much as 540 feet 

per mile for the South Fork Crazy Woman Creek. Gradients for the 

second mile of flow in the basin range from 100 feet per mile for the 

Middle Fork Crazy Woman Creek to 190 feet per mile for the South 

Fork Crazy Woman Creek. Gradients past the two-mile mark decrease and more closely approach uniformity, until a relatively gentle 

gradient of approximately 11 feet per mile is reached for Crazy r. Woman Creek between the bridge in sec. 31, T. 48 N., E. 81W., and the 

northeast edge of the mapped area.

Altitudes at which the streams leave the resistant rocks of the Bighorn Mountains and enter the relatively nonresistant rocks of the 

Powder River Basin are as follows: North Fork Crazy Woman Creek, 

5,900 feet above sea level; Muddy Creek, 5,600 feet above sea level; 

Billy Creek, 5,720 feet above sea level; Middle Fork Crazy Woman 

Creek, 5,450 feet above sea level; Beaver Creek, 5,900 feet above sea 

level; and South Fork Crazy Woman Creek, 5,900 feet above sea level. 

The difference in altitude at which the streams leave the mountain 

province coupled with their various gradients is significant in the 

consideration of a classification and correlation of terrace levels.

Table 1 shows a maximum mean discharge in June 1949 of 117 cfs 

and a minimum mean discharge of 4.08 cfs in February 1949 for the ' 

North Fork Crazy Woman Creek. Table 1 also shows a maximum 

mean discharge of 114 cfs during June 1949, and a minimum mean discharge of 7.35 cfs in February 1949 for the Middle Fork Crazy Woman 

Creek. Most of the discharge of the forks and tributaries of Crazy 

Woman Creek is diverted for irrigation of the flat bottom lands during
TABLE 1. Discharge of the North and Middle Forks Crazy Woman Creek

[Gaging station: North Fork, sec. 27, T. 49 N., R. 83 W.; Middle Fork, sec. 1

October_. 

NovemberDecemberJanuary. _. 

February. . 

March-.--. 

April---.-- 

May_.... 

June__... 

July--.-. 

August---. 

September.

North Fork

Cubic feet 

per second

274.1

193.8

168.7

138.4

114.2

134.9

590.2

1,652

3,514

898

377.6

315.8

Maximum

11.0

7.8

5.9

4.9

4.5

4.9

54

86

349

67

26

24

Minimum

7.5

5.5

4.9

3.5

3.8

3.9

4.3

24

46

14

8.0

7.6

Mean

4

4

4

1

5

117

2

1

1

TABLE 2. Average annual and monthly precipitation and temperature i

Precipitation '

Station

Sheridan Field Station.. .................

Jan.

0.50

.46

.59

.41

Feb.

0.65

.54

.41

.32

Mar.

1.18

1.15

1.00

.75

Apr.

2.22

1.36

1.37

1.52

May

2.91

2.95

1.82

2.23

June

3.29

2.99

4.56

2.67

July

1.48

1.19

1.24

.92

Temperature 2

20.3

23.8

19.2

22.8

20.6

24.4

20.8

25.2

31.2

30.3

31.6

31.0

44.3

41.9

44.1

43.8

54.1

50.5

52.9

51.4

61.4

57.8

59.8

59.0

72.2

68.2

69.8

69.2

1 Same number of years average as for temperature except for record at Kaycee which is an average of 6 years.

2 Sheridan Field Station average of 14 years, Buffalo average of 8 years, Lower Crazy Woman Creek average of 5 ye
42 CONTRIBUTIONS TO ECONOMIC GEOLOGY

the summer months. No statistics are available on discharge of 

smaller streams or Crazy Woman Creek; hence total discharge and 

amount of irrigation waters used cannot be determined.

Water supply in the mapped area is augmented by many pumping 

wells and earthwork dams across intermittent streams. Many of the 

larger dams contain water the year round, but some of the smaller 

ones contain water only intermittently.

The climate of the Crazy Woman Creek area is semiarid. Average 

annual precipitation as recorded by U. S. Weather Bureau stations 

(table 2) ranges from an average annual rainfall of 12.61 inches at 

Kaycee to 17.11 inches at the Sheridan Field Station. On lower Crazy 

Woman Creek the average annual temperature for a 5-year period 

was 43.5° F; the lowest monthly average temperature over a 5-year 

period was 19.2° F in January, and the maximum monthly average 

temperature was 69.8° F for July.

Vegetation in the basin area consists mainly of sagebrush, pricklypear, rabbitbrush, and a number of grasses. Trees are confined to 

stream bottoms or irrigated areas. Arable lands are mainly restricted 

to irrigated flat valleys, but in recent years many acres of relatively 

flat nonirrigated dry farmlands have been profitably planted with 

wheat. The flanks and subsummit uplands of the Bighorn Mountains 

are heavily forested; areas of various types of conifers in the uplands 

are interspersed with large open grassy parks.

ACCESSIBILITY AND SETTLEMENT

U. S. Highway 87 extends north through the middle of the area 

and passes through Buffalo, the county seat of Johnson Comity, 7 

miles north of the northern boundary. Although U. S. Highway 87 

is the only paved road in the area, there are several graded all-weather 

roads that form a network, making the larger portions of the mapped 

area easily accessible. Numerous small trails and ungraded roads, 

many of which are not shown on the geologic map, give almost complete accessibility by motor vehicle; an exception is the steep eastern 

flank of the Bighorn Mountains.

No towns are present within the mapped area, and settlement is 

almost wholly confined to the vicinity of streams.

STRATIGRAPHY

GENERAL FEATURES

Rocks ranging in age from Cambrian through Cretaceous were 

mapped, and stratigraphic sections were measured in detail; Pale-
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 43

ocene and younger rocks, although not measured, were mapped and 

described. Paleozoic rocks aggregate a maximum thickness of about 

2,550 feet; the dominant rock types are carbonates and sandstone. 

In the Paleozoic sequence, rocks of Silurian and Devonian age are 

absent. Mesozoic rocks attain a maximum thickness of about 9,350 

feet; the dominant rock type is shale or claystone. Thickness of 

Cenozoic rocks ranges from 4,000 to 5,000 feet.

Paleozoic rocks are dominantly of marine origin, whereas the 

Mesozoic sequence includes units of nonmarine, marine, and brackish-water origin; Cenozoic rocks are wholly of continental origin. 

Paleozoic and Mesozoic rocks are confined mostly to the western part 

of the mapped area, and, except in areas of local structural anomalies, 

dip eastward and trend essentially north-south. Cenozoic rocks occupy the eastern half of the mapped area and dip gently eastward 

or are flat lying. A generalized graphic section of rocks cropping 

out in the Crazy Woman Creek area is shown in plate 8.

LOCATION OF MEASURED SECTIONS

Except for the Gallatin limestone and Gros Ventre shale, undivided, and the Permian red shale and gypsum sequence, the section 

of Paleozoic rocks was measured along the North Fork Crazy Woman 

Creek through sees. 27 and 28, T. 49; N., R. 83 W. The Gallatin limestone and Gros Ventre formation, undivided, were measured in sees. 

8 and 9, T. 47 N., R. 83 W. The Permian red shale and gypsum 

sequence was measured in sec. 35, T. 48 N., R. 83 W. The Gypsum 

Spring and Sundance formations were measured in sees. 2 and 11, 

T. 48 N., R. 83 W. The Morrison and Cloveiiy formations, Skull 

Creek shale, Newcastle sandstone and Mowry shale were measured 

in sees. 25, 35, and 36, T. 49 N., R. 83 W. Except for the Frontier 

and Lance formations, younger Cretaceous rocks were measured in 

sees. 12 and 13, T. 49 N., R. 83 W. The Frontier formation was 

measured in sec. 1, T. 48 N., R. 83 W., and the Lance formation in 

sec.29,T.49N.,R.83W.

PBE-CAMBBIAN BOCKS

Pre-Cambrian rocks in the Crazy Woman Creek area have not 

been studied in detail. They consist mainly of foliated granite which 

has been locally intruded by diabase and pyroxenite dikes and irregularly shaped pegmatite masses. The granite is pinkish gray to gray, 

fine to coarse grained and contains plagioclase in places altered to 

sericite, quartz, microcline, biotite, and minor amounts of accessory 

minerals. Enclosed in pre-Cambrian granite in the southern half 

of sec. 31, T. 47 N., R. 83 W. is a small deposit which contains calcite, 

diopside, garnet, soda amphibole, epidote, oligoclase, and allanite.

339462 55 2
44 CONTRIBUTIONS TO ECONOMIC GEOLOGY

PALEOZOIC BOCKS 

FLATHEAD SANDSTONE

The Flathead sandstone unconformably overlies the foliated preCambrian granite and is overlain by the Gallatin limestone and Gros 

Ventre formation, undivided. Darton (1904, 1906) considered the 

unit a part of his Deadwood formation. The term Flathead sandstone 

was first used in this region by Wilson (1938), who applied it to outcrops of the formation along the Tensleep Fault west of the southern 

part of the Crazy Woman Creek area. In 1941 Demorest extended the 

usage to the east flank of the Bighorn Mountains.

The formation consists of about 260 feet of tan to light-brown, 

medium- to coarse-grained quartz sandstone. The quartz grains are 

relatively equant and rounded throughout, and many are secondarily 

enlarged; accessory minerals are rare. The basal 2 to 5 feet are conglomeratic, containing well-rounded quartz pebbles as much as 1.5 

inches long. Bedding ranges from regular to cross laminated. The 

Flathead sandstone forms a rounded ridge commonly covered by pine 

trees or grass. The upper few feet of the Flathead sandstone contains 

abundant inarticulate brachiopods and sparse "Elrathia" sp.; the latter 

fossil indicates a Middle Cambrian age for at least the upper part 

of the Flathead sandstone of the mapped area.

GALLATIN LIMESTONE AND GROS VENTRE FORMATION, UNDIVIDED

The Gallatin limestone and Gros Ventre formation are not distinguishable in this area although elements of both are present. They 

overlie the Flathead sandstone. The sequence crops out high along 

the flanks of the Bighorn Mountains and generally dips eastward. 

Three distinct lithologic units are present. The lower 136 feet consists 

of a very friable nonresistant medium- to coarse-grained glauconitic 

sandstone. The average length of the intermediate intercept of quartz 

grains in a disaggregated sample mounted in balsam is 0.3 millimeter 

as compared with the average of 0.4 millimeter for the long intercept. 

The quartz grains range from rounded to subangular and the glauconite is polylobate. About 30 percent of the rock is glauconite and 

the remainder is quartz. The upper part of the sequence is partly 

hematitic; colors range from a drab brownish green to dusky red. The 

glauconitic sandstone and overlying unit form soft slopes; except 

where exposures are good, the two units cannot be separated. The 

sandstone is overlain by about 370 feet of interbedded soft grayishgreen shale, light-gray limestone, thin sandstones, and beds of flatpebble conglomerate. The slopes formed by these.units are usually 

covered by talus and vegetation. The topmost unit, which occupies 

the stratigraphic position of the Gallatin limestone of other areas, is
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 45

about 50 feet thick and consists of resistant grayish-red slabby silty 

limestone and a few thin beds of flat-pebble conglomerate. The limestone contains about 35 percent of irregularly shaped angular silt and 

very fine sand sized grains; the remainder is calcite in rhombs ranging 

from 0.1 millimeter in length down to cryptocrystalline interstitial 

filling. Minor amounts of glauconite are present. Some very small 

brachiopod shells are visible in thin section.

The contact between the Flathead sandstone and the Gallatin limestone and Gros Ventre formation, undivided, is marked by a sharp 

change from resistant nonglauconitic quartz sandstone below to friable glauconitic sandstone above. Darton (1904, 1906) included the 

units which are herein defined as the Flathead sandstone and the 

Gallatin limestone and Gros Ventre formation, undivided, in his 

Deadwood formation. Demorest (1941) used the term Flathead 

sandstone and referred to the overlying shale and limestone section as 

the Deadwood formation. The glauconitic sandstone and the grayish-green shale sequence strongly resemble the Gros Ventre of areas 

to the west, and the grayish-red limestone occupies the stratigraphic 

position of the Gallatin limestone. Because the limestone is too thin 

to be mapped as a separate unit in the areas of steep dips and vertical 

faces where it commonly crops out, it is included with the Gros 

Ventre formation. Trilobite assemblages that characterize the Dresbach and Trempeleau ages of the Late Cambrian are found in the glauconitic sandstone and grayish-green shale. Fossils representing a 

Franconian age have not been found, but this is probably due to generally heavy cover on the softer parts of the Gallatin limestone and 

Gros Ventre formation, undivided. Although no fossils were found 

in the grayish-red limestone within the mapped area, Denson (personal communication, 1951) reported a Canadian fauna to be present 

in the unit about 32 miles to the northwest.

BIGHORN DOLOMITE

The Bighorn dolomite overlies the Gallatin limestone and Gros 

Ventre formation, undivided, and is unconformably overlain by the 

Madison limestone. The formation crops out in prominent cliffs 

along both flanks of the Bighorn Mountains north of the Horn. The 

Bighorn dolomite consists of three major units.

The basal 65-foot unit of the formation is a very light gray to brickred very fine grained to coarse grained almost pure quartz sandstone; 

accessory minerals are rare. Of this sandstone unit the lower 48 feet 

is dominantly very light gray and very fine grained. Grains vary in 

cross section from equidimensional to somewhat elongated and from 

rounded to subround. Some zones show hematitic staining. The 

next higher 12 feet of sandstone includes two major grain sizes, those
46 CONTRIBUTIONS TO ECONOMIC GEOLOGY

FIGUHE lij. Contact between tno dnlomitie and sandstone units of the Bighorn dolomite 

on the North Fork Crazy Woman Creek. Bone fragments zone about 8 inches below hammer ; handle rests on unit 10.

ranging from 0.5 to 1.0 millimeter in diameter and those ranging in 

long intercept from 0.2 to 0.5 millimeter. Grains of the coarser fraction consist of almost perfect spheres; grains of the finer fraction 

show less perfect sphericity although they are quite rounded. A 

great number of the larger grains contain very fine hairlike needles 

of rutile(?). This 12-foot bed (fig. 16) contains abundant small 

bone fragments of primitive jawless fishes. The upper 3.5 feet is fine 

to medium-grained well-indurated quartz sandstone which contains 

mollusks, Receptaculities oweni Hall, and conodonts. At the surface 

this 65-foot sandstone unit is moderately friable, but, in the few subsurface sections where it has been drilled, it is characteristically very 

dense, hard, and impermeable.

Overlying the basal 65-foot sandstone unit of the Bighorn dolomite 

is,about 250 feet of tan very dense massive dolomite which forms steep 

resistant cliffs (fig. 15). The weathered surface of the dolomite is, in 

places, pitted and marked by a reticulate network of siliceous veinlets. 

The lower 3 feet of the unit contains very fine sand grains. Thin sections of samples of the massive dolomite show a random orientation 

of dolomite rhombs ranging in maximum length from 0.02 to 0.04 

millimeter. Some larger anhedral crystals of dolomite have the 

smaller rhombs included in them.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 47

Overlying the 250-foot massive dolomite along the North Fork 

Crazy Woman Creek is a white-weathering slabby argillaceous dolomite about 40 feet thick. This dolomite is characterized by an abundance of ostracodes covering bedding surfaces. In a covered interval 

between the North Fork Crazy Woman Creek and Billy Creek the unit 

wedges out, but north of the North Fork Crazy Woman Creek it 

thickens and persists.

The Bighorn dolomite is truncated by the Madison limestone and 

thins from about 350 feet along the North Fork Crazy Woman Creek 

to about 150 feet at the southern end of the Horn. Darton (1906) 

shows the Bighorn dolomite completely cut out 18 miles southwest 

of the Horn by the unconformity at the base of the Madison limestone. 

The contact between the grayish-red limestone of the Gallatin limestone and Gros Ventre formation, undivided, and the Bighorn dolomite 

is sharp. Beds directly above the contact are light-gray sandstone, 

whereas those below are grayish-red limestone.

The basal sandstone unit of the Bighorn dolomite has at different 

times been correlated with the Harding sandstone of Colorado and 

with the Lander sandstone member of the Bighorn dolomite of the 

western Wind River Basin. The correlation of these two units is not 

certain, however, for the Lander sandstone until recently has been regarded as Upper Ordovician (Miller, 1932) and the Harding sandstone as Middle Ordovician. Flower (1952b), in light of more recent 

knowledge, indicates that the Lander sandstone member may be as old 

as late Trenton, and he has reaffirmed the Middle Ordovician' age of 

the Harding sandstone as stated by Kirk (1930). According to Elower 

(1952a) the cephalopods of the Harding sandstone most resemble 

those of Black River and Trenton species; hence it is apparent that 

the Lander is younger than the Harding. Amsden and Miller (1942), 

who have studied the conodonts of the basal sandstone of the Bighorn 

dolomite of the Crazy Woman Creek area, have discovered two distinct 

faunal zones in that unit. The younger is restricted to unit 10 (the 

upper 3.5 feet of the lower 65-foot sandstone) of the Bighorn dolomite 

of this report (p. 112) and the older to the underlying sandstone. According to Amsden and Miller, conodonts from the lower zone are 

similar to those found in the Harding sandstone of Colorado, as well 

as in the Platteville limestone of Minnesota. Unit 10, the upper zone, 

yielded a conodont fauna similar to that found in the gray shales and 

siltstones of the Whitewood limestone of the Black Hills, South 

Dakota. The shale and siltstone sequence of the Whitewood is regarded by Furnish (and others, 1936) as Middle(?) Ordovician. 

Amsden and Miller regard the lower faunal zone of the clastic portion 

of the Bighorn dolomite as Middle Ordovician, as well as unit 10, but 

state that the fauna of unit 10 may be Upper Ordovician. Because the
48 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Harding and Lander sandstones now appear as two distinct chronological entities within the Middle Ordovician, and as two distinct 

fauna! zones are present in the basal sandstone of the Bighorn dolomite, it is possible that chronologic elements of both the Lander and 

Harding sandstones are present in the clastic portion of the Bighorn 

dolomite. According to Josiah Bridge, collections of Maclurites 

manitobensis Whiteaves and Endoceras landerense Foerste from a bed 

equivalent to unit 10 just 12 miles north of the mapped area indicate a 

Middle Ordovician age for that unit. Fossils from the upper part of 

the massive dolomite, the middle unit of the Bighorn dolomite, and 

from the upper white slabby dolomite indicate a Late Ordovician age 

for these parts of the Bighorn dolomite.

MADISON LIMESTONE

The Madison limestone unconformably overlies the Bighorn dolomite and crops out in resistant cliffs along the flanks of the Bighorn 

Mountains (fig. 17). The unit has been penetrated in deep test wells 

in both the Billy Creek and the Steel Creek anticlines. The Madison 

limestone is about 550 feet thick and consists of four major alternating 

units of limy dolomite, which range in color from light tan to gray, 

and limestone. The lower 3 feet of the formation is slightly sandy

FIGURE 17. View of the east flank of the Horn at the South Fork Crazy Woman Creek. 

The Bighorn dolomite (Ob) and Madison Limestone (Mm) form the resistant cliffs. 

The Gallatin limestone and Gros Ventre formation, undivided (-Cgg), form the slope.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 49

and locally conglomeratic. The sequence ranges from thin bedded to 

massive. Some of the beds are bioclastic, but most are finely crystalline limestone or dolomite. The entire formation is fossiliferous but 

sparsely so in the lower 100 feet. The most common fossils are spiriferoid brachiopods and solitary tetracorals; the former are abundant 

in the middle part.

The contact between the Bighorn dolomite and the Madison limestone is characterized by a topographic break; the Madison limestone 

cliffs are set back from the Bighorn dolomite. The basal part of the 

Madison limestone is a gray somewhat sandy dolomitic limestone; 

the underlying Bighorn dolomite is a tan dense dolomite or white 

slabby dolomite north of Billy Creek. The Madison limestone contains an early Mississippian fauna; collections from Rock Creek, 12 

miles north of the mapped area, identified by Helen Duncan on April 

12, 1952, indicate that the upper part may be late Mississippian.

AMSDEN FORMATION

The Amsden formation overlies the Madison limestone and is 

present along the flanks of the Bighorn Mountains. A complete section was penetrated in test holes in both the Billy Creek and Steel 

Creek anticlines. The Amsden formation is about 250 feet thick; it 

consists of soft brick-red fine-grained silty sandstone in the basal 

100 feet, thin-bedded light-gray dolomites, dolomite breccia, and soft 

red clay stone in the middle 75 to 100 feet, and yellow to tan massive 

dolomite interspersed with a network of light-brown siliceous veinlets 

in the upper 50 to 75 feet. The contact between the Madison limestone 

and the Amsden formation is marked by a sharp change from dense 

gray limestone below to thin lenticular sandstones, slabby tan dolomite, and reddish-brown siltstones above. Collections from the lower 

part of the Amsden formation at Rock Creek, 13 miles north of the 

mapped area, contained DiphyphyUum sp., Syringopom sp. (identified by Helen Duncan on April 16,1952) and some productid brachiopods. Corals found in the lower part of the Amsden formation range 

from late Mississippian to early Pennsylvania!!; no forms diagnostic 

of either system were found. No fossils were found in the upper part 

of the Amsden formation of the mapped area.

TENSUGEP SANDSTONE

The Tensleep sandstone overlies the Amsden formation and forms 

the resistant steep dip slopes along the flanks of the Bighorn Mountains. The contact of the Tensleep with the overlying Permian red 

shale and gypsum sequence marks the topographic boundary between 

the Bighorn Mountains and the Powder River Basin. The formation 

has long been a producer of oil in fields along the western and southern 

margins of the basin.
50 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The Tensleep sandstone in the mapped area is about 350 feet thick. 

Mapel (personal communication, 1952) reports ,a thickness of 275 feet 

in the Lake De Smet area. Richards and Rogers (1951) report a 

range in thickness from a wedge edge to 100 feet for the Tensleep sandstone in the Hardin area, Montana, 55 miles north of the Crazy Woman 

Creek area. The formation is dominantly a light-tan to gray, or sometimes grayish-red, fine-grained massive to crossbedded sandstone. 

Dolomite beds are common in the lower part of the formation; they are 

thinner and scarcer in the upper part. In places thin lenticular beds 

of light-gray to brown chert yield abundant foraminifers. The apparently conformable contact between the Amsden formation and the 

Tensleep sandstone is placed at the top of the upper thick limy dolomite. Beds above the contact are dominantly sandstone. Love (personal communication, 1952) collected fusulines from the upper part 

of the Tensleep sandstone along the western margin of the Bighorn 

Mountains, which were identified by L. G. Henbest as characteristic 

of the Des Moines (early Pennsylvanian) epoch.

PERMIAN RED SHALE AND GYPSUM SEQUENCE

The Permian red shale and gypsum sequence overlies the Tensleep sandstone; it crops out along the eastern margin of the Bighorn 

Mountains and generally dips eastward. The sequence is about 250 

feet thick. The lower 50 feet consists of soft dark reddish-brown 

silty claystone, with local conglomeratic lenses in the basal 6 feet composed of reworked Tensleep sandstone in a reddish-brown claystone 

matrix. This unit is overlain by 50 feet of red siltstone which contains at the top and base 5 and 8 feet, respectively, of thin-bedded yellowish-gray dolomitic and argillaceous limestone that is similar to the 

Minnekahta limestone of areas to the east and southeast. The upper 

150 feet consists of interbedded gypsum and red siltstone, which is 

capped by a porous brecciated and lenticular limestone from 3 to 5 

feet thick. In places the gypsum is leached out at the surface. 

Except for the limestones, the unit forms a slope.

The contact with the Tensleep sandstone is sharp; beds above the 

contact are soft red claystone and shale which contrast strongly with 

the light-colored sandstones below. The basal 50-foot red silty claystone unit is very similar to the Opeche shale of eastern Wyoming 

and seems to be correlative with that formation. The limestone of 

the middle red siltstone and limestone unit bears a strong resemblance 

to the Minnekahta limestone of eastern Wyoming and occupies the 

same stratigraphic position. Darton (1904) included the dolomitic 

limestone in his Chugwater formation but suggested that it was 

equivalent to the Minnekahta limestone. Although no fossils have 

been found in the dolomitic limestones of the mapped area, brachiopods, pelecypods, and bryozoans similar to those in the Phosphoria
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 51

formation of Permian age, 70 miles to the southwest, were collected 

by Love (personal communication, 1952) 3 miles northwest of Mayoworth from a tan dolomite which directly overlies the Tensleep sandstone. The upper 150-foot gypsum and red siltstone unit is tentatively 

correlated with a similar sequence in the upper part of the Phosphoria 

formation on the southwestern flank of the Bighorn Mountains and 

with the Permian (?) shale and gypsum sequence of the Hartville 

region in eastern Wyoming. The gypsiferous sequence may be in part 

equivalent to the Dinwoody formation of Early Triassic age of the 

southwestern Bighorn Basin.

MESOZOIC BOCKS 

CHUGWATER FORMATION

The Chugwater formation overlies the Permian red shale and 

gypsum sequence and is unconformably overlain by the Gypsum 

Spring formation. The formation crops out as a prominent red unit 

along the western margin of the Powder River Basin and has been 

penetrated in numerous test holes in that region. It ranges in thickness from 750 to more than 800 feet and in most places can be separated into three units. The lowermost 700 feet, called the Red Peak 

member of the Chugwater formation in central Wyoming (Love, 

Johnson, and others, 1945), consists of a soft sequence of interbedded 

moderate reddish-brown siltstone, shale, and silty fine-grained sandstone; the sandstone is more abundant in the upper half. The unit 

weathers to soft reddish slopes. Overlying this unit in places is a 

lenticular slabby dense resistant light-gray dolomitic limestone, 

which has a maximum thickness of 5 feet in the mapped area and 

which contains purple clay laminae along bedding surfaces. This 

limestone is correlated with the Alcova limestone member of the 

Chugwater formation of central Wyoming. It can be traced on the 

surface in prominent hogbacks along the southeast edge of the Bighorn Mountains to the Powder River lineament and correlated in 

subsurface sections into central Wyoming. The topmost unit of the 

Chugwater formation is a salmon-pink fine-grained massive sandstone 

ranging in thickness from 45 to more than 100 feet. The sandstone 

in many places contains scattered spherical frosted quartz grains as 

much as 0.5 millimeter in diameter embedded in the fine-grained 

matrix. In the Red Fork Powder River area this sandstone has been 

called the Crow Mountain sandstone member of the Chugwater formation by Carlson (1949) on the basis of correlation with the type 

Crow Mountain sandstone member of Love in central Wyoming (Love, 

1939). The threefold division of the Chugwater formation is feasible only where the Alcova limestone member is present. Where the 

limestone is absent, it is difficult to separate the sandstone beds of the
52 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Red Peak member from those of the Crow Mountain sandstone 

member as defined by Love (1948).

The contact between the Permian red shale and gypsum sequence 

and the Chugwater formation is characterized by a change from red 

siltstone and white gypsum below to reddish-brown siltstone and silt 

shale above.

The lower part of the Chugwater formation, the Red Peak member 

of central Wyoming, thins from about TOO feet in the Crazy Woman 

Creek area to 480 feet in the Texas Co.'s Forbes test well 1, 11 miles 

southwest of Sheridan, Wyo. In view of this substantial northward 

thinning along the western margin of the Powder River Basin when 

compared with the relatively constant thickness for the unit in central 

Wyoming, it is likely that the Alcova limestone member rests unconformably on the lower Chugwater unit. The so-called Crow Mountain sandstone member ranges in thickness from 45 to more than 100 

feet within the Crazy Woman Creek and thins to less than 25 feet on 

Little Goose Creek 14 miles south of Sheridan. The difference in 

thickness of the sandstone as well as the complete absence of younger 

Chugwater strata, such as are present in the Wind River Basin, is 

evidence for an unconformity at the base of the Gypsum Spring formation (fig. 19). Love, Johnson, and others, (1945) have suggested 

that the thinning of the Nugget sandstone and the upper part of the 

Chugwater formation in central Wyoming may be the result of uplift 

followed by erosion preceding Gypsum Spring time. Except for the 

Alcova limestone member, the Chugwater formation is nonmarine in 

origin and fossils are rare. Those fossils found indicate a Triassic 

age for the Chugwater formation.

GYPSUM SPRING FORMATION

The Gypsum Spring formation unconformably overlies the Chugwater formation and is unconformably overlain by the Sundance formation. The Gypsum Spring formation thins southward from 120 

feet at Elgin Creek to a wedge edge 6 miles south of the mapped area; 

it persists northward along the western margin of the Powder River 

Basin into Montana where it attains a maximum thickness of 190 feet 

in the vicinity of Lodgegrass Creek (Hose and Mapel, unpublished 

data). Because of the southward thinning of the Gypsum Spring 

formation, with the oldest beds extending the farthest south, the following description applies to the northernmost measured sections of 

the mapped area.

The lower part of the formation contains as much as 50 feet of 

probably limy gypsum with interbedded reddish-brown siltstone and 

shale, but generally the gypsum is leached out, leaving in its stead a 

thinner section of limestone breccia and reddish-brown siltstone or
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO, 53

shale. Overlying the gypsiferous unit are from 20 to 40 feet of moderate reddish-brown claystone. The remaining 70 feet consists of alternating zones of light-gray argillaceous limestone and moderate 

reddish-brown claystone; a 5-foot limestone zone is at the base, succeeded by a 15-foot claystone unit and a 10-foot limestone unit, with a 

20-foot claystone unit at the top.

The unconformable contact between the Chugwater formation and 

the overlying Gypsum Spring formation is comparatively sharp. The 

beds below the contact are reddish-brown sandstone whereas those 

above consist of gypsum, limestone breccia, or fine-grained siltstone.

Southward from Elgin Creek the Sundance formation overlies 

progressively older units of the Gypsum Spring formation; at the 

southern edge of the mapped area the Sundance formation rests on 

a thin portion of the lower gypsiferous unit (figs. 18 and 19). This 

relationship indicates post-Gypsum Spring and pre-Sundance upwarping and erosion in the southern part of the Powder River Basin.

MAYOWORTH

LITTLE 

GOOSE CREEK

FIGURE .1.8. Diagrammatic cross section showing unconformable relationship of 

Gypsum Spring formation to older and younger units along the western margin of 

the Powder River Basin.

WESTERN 

WIND RIVER BASIN

SOUTH 

MAYOWORTH

FIGURE 19. Diagrammatic cross section showing relationship of Gypsum Spring 

formation to older and younger units from the western Wind River Basin to 3 

miles south of Mayoworth.
54 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The thinning of the Gypsum Spring formation from the western 

part of the Wind River Basin eastward has also been attributed to 

mild regional up warping and subsequent erosion (Love, Tourtelot, 

and others, 1945). Fossils from the Gypsum Spring formation of 

the mapped area are limited to nondiagnostic pelecypods. Imlay 

(personal communication, 1951), on the basis of collections from a 

more typically marine facies of the formation in the western part 

of the Bighorn Basin and on the relationship of the formation to 

younger marine units in western Wyoming, considers the Gypsum 

Spring formation to be early Middle Jurassic (Lower Bajocian) 

in age.

SUNDANCE FORMATION

The Sundance formation unconformably overlies the Gypsum 

Spring formation in the Crazy Woman Creek area (fig. 18) and is 

overlain by the Morrison formation. The formation crops out along 

the western part of the Powder River Basin and has been penetrated 

in numerous test holes in the region. The Sundance formation is 

approximately 287 feet thick. The lower 112 feet consists of three 

stratigraphic units of which the lower and upper are resistant sandstones : the lower 30 feet is light-gray to light-tan fine-grained regularly bedded very calcareous and somewhat resistant sandstone with 

some shale beds in the lower part; overlying the basal sandstone is 

approximately 25 feet of soft calcareous grayish-olive shale. The 

next higher 57 feet is yellowish-gray fine-grained calcareous slightly 

glauconitic crossbedded resistant sandstone. The remaining 175 feet 

consists dominantly of olive-gray silty calcareous shales with a few 

thin soft sandstone layers. The upper 10 feet of this 175-foot unit 

consists of slabby shaly calcareous slightly glauconitic brownweathering sandstone.

In the southern part of the mapped area the lowermost unit of the 

Sundance formation is a lenticular glauconitic, oolitic, and locally 

conglomeratic limestone. Several thin sections of specimens from 

the oolite bed show a flood of rounded quartz grains. Many of these 

grains serve as nuclei for the oolites. The oolites are spherical to 

ovoid in shape, ranging in diameter from 0.1 to 0.3 millimeter. The 

oolites range from radial with no concentric bands to a series of concentric bands in which the crystalline calcite is radial. Interstitial 

filling is cryptocrystalline calcite. The basal oolite bed attains a 

thickness of approximately 15 feet about 7 miles south of the mapped 

area and rests on the Crow Mountain sandstone member of the Chugwater formation. The lower fine-grained sandstone in the mapped 

area grades into an arenaceous oolitic limestone with abundant 

rounded quartz and rare zircon grains, 7 miles south of the mapped 

area.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 55

The upper slabby sandstone of the Sundance formation is channeled, 

and the channels are filled by the basal sandstone of the Morrison 

formation. The contact between the Gypsum Spring formation and 

the Sundance formation is unconformable and is marked by soft red 

shale and argillaceous limestone beds below the contact and sandstone 

or dense oolitic limestone beds above. The basal sandstone of the 

mapped area yielded Isocrinus sp., and a zone 20 feet above the base 

of the 175-foot shale sequence contained abundant Pachyteuthis densus 

(Meek and Hay den). Neither of these fossils is particularly useful in 

accurately dating beds, but ammonites from the basal sandstone of 

the Sundance formation of adjacent areas and in the Black Hills 

(Imlay 1947) indicate a Late Jurassic age for the Sundance formation.

MORRISON FORMATION

The Morrison formation overlies the Sundance formation and is 

overlain by the Cleverly formation. The outcrop of the Morrison 

formation trends essentially north-south and dips generally eastward. 

The formation has remarkable uniformity of thickness, about 185 feet, 

in both surface and subsurface sections along the western part of the 

Powder River Basin. The formation is dominantly sandstone in the 

lower part and clay stone in the upper part. The lower part contains 

many beds of yellowish-gray siltstone and fine-grained sandstone interbedded with varicolored shales and claystones. In the upper part 

there is much less sandstone and siltstone and more red, ' O preen, * and

black claystone. The upper 30 feet throughout the mapped area is 

very dark gray carbonaceous shale; the lower 112 feet of the formation is calcareous. Fifty-five feet above the base is a lenticular very 

light gray marlstone bed about 1 foot thick which contains abundant 

nonmarine ostracodes and chara fructification. Disaggregated grains 

of the basal sandstone of the Morrison formation show an average 

long intercept of 0.24 millimeter and an average intermediate intercept of 0.13 millimeter. The grains range from angular to subangular 

and are dominantly quartz, although some feldspar is present; accessory minerals are minor. The matrix of the sandstone falls into the 

clay to silt size, and the cement is calcite.

Except for the thin slabby beds of glauconltic sandstone of the 

Sundance formation, strata below the contact with the Morrison formation are dominantly shale; beds directly above the contact are 

massive light-gray lenticular sandstones. The Morrison formation 

contains an abundant fresh-water invertebrate fauna of Late Jurassic 

age near Mayoworth, about 7 miles south of the Crazy Woman Creek 

area (Love, Thompson, and others, 1945). Dinosaur bones are also 

common.
56 CONTRIBUTIONS TO ECONOMIC GEOLOGY

CLOVERLY FORMATION

The Cleverly formation overlies the Morrison formation. Throughout the mapped area the Cloverly formation consists of a welldeveloped basal sandstone which ranges in thickness from 15 to 45 

feet, overlain by about 120 feet of grayish-black shale interlaminated 

with olive-gray siltstone. The basal sandstone is coarser grained than 

the sandstones in the Morrison; from a disaggregated sample approximately 45 percent was retained on a 60 mesh screen, 45 percent retained 

on a 115 mesh screen, and 10 percent retained on a 250 mesh screen. 

The sandstone is composed of almost pure quartz; grains are relatively equant and rounded to subangular. Many of the grains have 

been secondarily enlarged and have developed crystal facets. The 

basal sandstone forms a resistant ridge largely covered with pine 

trees. The grayish-black shale and siltstone sequence contains several 

zones of flat ellipsoidal ironstone concretions, as well as a zone of 

radial concretions of the phosphatic mineral dahllite, 110 feet above 

the base of the formation. The grayish-black shale and siltstone 

sequence is capped by a 5.5-foot bed of calcareous thin-bedded 

brownish-gray siltstone, which forms a persistent ridge throughout 

the mapped area.

The upper boundary of the Cloverly formation in the mapped area 

conforms to the definition of the Cloverly formation in adjacent 

regions. In central Wyoming the formation consists of three major 

units: a basal sandstone which is locally conglomeratic, an intermediate varicolored claystone, and the so-called "rusty beds," a 

series of resistant slabby siltstone and sandstone beds. This threefold breakdown strongly resembles the Black Hills sequence 

where the Lakota sandstone is at the base and is overlain by the Fuson 

shale and the Fall River sandstone. Except for minor facies variations the two sequences are probably equivalent. The correlation 

of the Cloverly formation of the Crazy Woman Creek area with that 

of central Wyoming and with the Lakota sandstone, Fuson shale, 

and Fall River sandstone of the Black Hills is difficult because of the 

atypical f acies of the sequence in the mapped area.

In the Crazy Woman Creek area the intermediate varicolored sequence is absent and the rusty bed sequence is poorly developed. The 

equivalents of those units are grayish-black shales and siltstones. 

The lower part of the overlying Skull Creek shale also contains grayish-black shale and siltstone, as well as a resistant and persistent ridge 

which is almost identical with that in the upper part of the Cloverly 

formation. A study of electric logs from the Mush Creek oilfield on 

the southwest flank of the Black Hills to the Crazy Woman Creek 

area across the Powder River Basin (pi. 9) shows the development 

of a zone of siltstone in the lower part of the Skull Creek shale as indi-
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 57

cated by the increase in resistivity curves of subsurface section 8. 

This siltstone zone of the Skull Creek shale persists along the western margin of the basin into the Crazy Woman Creek area; it is for 

this reason that the upper resistant siltstone and grayish-black shale 

of the sequence between the basal sandstone of the Cleverly formation 

and the Newcastle sandstone is included with the Skull Creek shale 

rather than with the Cleverly formation.

It should be noted in subsurface sections 12 through 15 (pi. 9) that 

the upper zone of the Cleverly formation is dominantly shale, and in 

the region of Sheridan, Wyo., the problem of selecting the top of the 

Cleverly formation would be difficult.

One mile south of the mapped area the Cleverly formation contains 

a 20-foot remnant of the intermediate varicolored claystone unit, 

which is overlain by grayish-black shale and siltstone. The lithologic 

change northward into the grayish-black shales is apparently graclational, as indicated by the constant thickness of the formation above 

the basal sandstone in subsurface section IT, at a point 9 miles south 

of the mapped area and subsurface section 16 on the Middle Fork 

Crazy Woman Creek. The basal sandstone has a thickness of 12 feet 

in subsurface section IT and 55 feet in subsurface section 16.

The contact between the Morrison formation and the Cleverly 

formation is sharp. The upper part of the Morrison formation consists of dark and dully varicolored claystones and shales, and the lowermost Cleverly strata are .light-yellowish-gray sandstone. The 

assignment of the Cloverly formation to the Lower Cretaceous has 

been discussed by Love, Thompson, and others (1945).

SKULL CHEEK SHALE

The Skull Creek shale overlies the Cloverly formation and varies 

in thickness from 125 feet in subsurface section IT (pi. 9), 9 miles 

south of the mapped area, to 165 feet in subsurface section 16, on the 

Middle Fork Crazy Woman Creek; it is 165 feet thick on the surface 

at Muddy Creek. The lower 8T feet is characterized by many laminae 

and beds of gray siltstone alternating with grayish-black shales, a 

sequence very much like that in the upper part of the underlying 

Cloverly formation. This silty zone in the Skull Creek shale first 

appears in subsurface section 8, sec. 28, T. 53 N., R. 68 W., and persists westward across the Powder River Basin into the Crazy Woman 

Creek area. The lower 8T-foot unit is capped by a resistant ridgeforming siltstone bed about 2.5 feet thick, which can be traced 

throughout the mapped area. The upper T9 feet consists of grayishblack soft flaky clay shale.

The contact between the Cloverly formation and the Skull Creek 

shale is placed at the top of the first resistant siltstone ledge above
58 CONTRIBUTIONS TO ECONOMIC GEOLOGY

the 15- to 45-foot basal sandstone of the Cloverly formation. Beds 

directly above the contact are grayish-black shales that form a slope, 

but beds below the contact are more resistant and contain siltstone 

laminae.

The Skull Creek shale correlates with that part of the Thermopolis 

shale which underlies the Muddy sandstone member in central Wyoming. The Skull Creek shale is considered to be Early Cretaceous in 

age (Cobban, 1951).

NEWCASTLE SANDSTONE

The Newcastle sandstone which overlies the Skull Creek shale was 

named by Hancock (1920) from excellent exposures about a half 

mile east of Newcastle, Wyo., on the southwestern edge of the Black 

Hills. In the southern part of the Powder River Basin and elsewhere 

the unit has been called the Muddy sandstone or the Muddy sandstone 

member of the Thermopolis shale. The formation is in general one 

of the most persistent and widespread sandstones in Wyoming; locally, however, it grades into shale and becomes impermeable, as shown 

in subsurface sections 5 and 6 and in part 7 (pi. 9). The gradation of the sandstone into shale in an appropriate structural setting, 

as in the Mush Creek oilfield, is responsible for oil accumulation.

In the mapped area the Newcastle sandstone is about 40 feet thick 

and consists of light-gray medium-grained sandstone which contains 

abundant black and red grains. The unit forms a persistent, in many 

places pine-covered, ridge throughout the mapped area.

The contact between the Skull Creek shale and the Newcastle sandstone is sharp. Beds above the contact are light-colored sandstone 

which contrast with the grayish-black shales below. The Newcastle 

sandstone and its correlatives had been regarded for many years as 

the basal sandstone of the Upper Cretaceous, but Crowley (1951) 

found f oraminif ers in the intercalated shales of the Newcastle sandstone in the Mush Creek oilfield which he believed to be of Early 

Cretaceous age. Subsequently Cobban and Eeeside (1951) ascribed to 

the Early Cretaceous ammonites from the overlying Mowry shale 

and thus corroborated the Early Cretaceous age of the Newcastle 

sandstone.

MOWRY SHALE

The Mowry shale overlies the Newcastle sandstone and, like the 

Newcastle, extends over most of Wyoming. In the Crazy Woman 

Creek area the Mowry shale is about 500 feet thick and consists of 

two major units which grade into each other. The lower unit, which 

is about 150 feet thick, is soft grayish-black shale with several thin 

beds of bentonite. This unit is nonsiliceous in the lower part but 

slightly siliceous in the upper part; any contact between it and the
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 59

overlying unit would be unreliable. The upper unit of 350 feet consists of light-gray brittle laminated siliceous shale, with several yellowish bentonite beds and a few thin sandstones. The siliceous shale 

crops out as a resistant rounded ridge characteristically marked by a 

growth of pine trees.

The lower 150-foot unit occupies the same stratigraphic position 

and is in part the lithogenetic equivalent of the upper part of the 

Thermopolis shale as defined by Lupton (1916) in the southern part 

of the Bighorn Basin. It is also equivalent to the nonsiliceous portion 

of the Mowry shale of the Black Hills, which at one time was mapped 

as a distinct unit, the Nefsy shale member of the Graneros shale. 

Rubey (1930, p. 4) considered the Nefsy shale member a poor unit 

to map and included it in his Mowry siliceous shale member of the 

Graneros shale. The upper limit of the nonsiliceous portion of the 

Mowry shale in the mapped area also has a poor upper boundary to 

map and is included with the Mowry shale.

The contact between the Newcastle sandstone and the overlying 

Mowry shale is sharp: the beds above the contact are soft grayishblack shales which contrast with the light-gray sandstone below. The 

Mowry shale contains abundant fish scales throughout. A collection 

of ammonites from the upper part of the siliceous shale in the southern 

half of the mapped area contained Metengonoceras sp. and Neogastroplites wyomingensis (Eeeside and Weymouth). This faunule indicates an Early Cretaceous age for the Mowry shale (pi. 10).

FRONTIER FORMATION

The Frontier formation, which is about 480 feet thick, overlies the 

Mowry shale. The lower 80 feet consists of somewhat bentonitic 

dark-gray shale and siltstone, with four bentonite beds ranging in 

thickness from 1 to 6 feet; it is characterized by flat ellipsoidal 

ferruginous and calcareous siltstone concretions and is similar to the 

lower part of the Belle Fourche shale of the Black Hills region. The 

remaining 400 feet of the Frontier formation consists mainly of interlaminated light-gray sandstone and dark-gray shale, with a few conglomeratic sandstone beds and a 4-foot bentonite bed.

The upper 35 feet of this 400-foot unit consists mainly of finegrained sandstone with a few shale laminae and is capped by a black 

chert pebble conglomerate which ranges in thickness from 2 to 10 

feet. The 35-foot sandstone unit increases in resistance to weathering 

and becomes coarser grained about 4 miles south of the mapped area. 

Disaggregated samples of the unit in that area show an average ratio 

of long to intermediate intercept of 1.4; the intermediate intercept 

ranges from 0.2 to 0.5 millimeter in length, and the grains range 

from angular to subrounded. About 20 percent of the grains are

339462 55 3
60 CONTRIBUTIONS TO ECONOMIC GEOLOGY

feldspar; the remainder is quartz, many grains of which are coated 

with a limonitic stain. Four miles south of the mapped area the 

upper 35-foot sandstone is conglomeratic and contains well-rounded 

ellipsoidal pebbles and cobbles of andesite, as well as abundant blackweathering chert pebbles. The conglomeratic sandstone forms a 

resistant ridge which is recognizable over the entire area, but the 

underlying strata usually form soft slopes.

The top 2- to 10-foot conglomeratic sandstone of the Frontier 

formation of the mapped area is not equivalent lithogenetically or 

chronologically to the top sandstone of the Frontier formation (First 

Wall Creek sand of drillers) of the Tisdale anticline, 19 miles to the 

south. There the top sandstone is either late Turner or early Sage 

Breaks in age, and the Frontier formation is much thicker than in the 

Crazy Woman Creek area where the top sandstone of the Frontier 

formation is of Greenhorn age.

Several of the f aunal zones of Colorado age as outlined by Cobban 

(1951) in the Black Hills region are represented in the Crazy Woman 

Creek area (fig. 20). A zone 250 to 350 feet above the base of the 

Frontier formation contains Acanthoceras? amphibolum Morrow, 

which is correlative with the middle f aunal zone of tjie Belle Fourche

CRAZY WOMAN TISDALE

CR

shale Cody 

tier formation

1

EEK AF

:.°':e?V'ss:.-'

REA AT

*

* 

~~Metoicocerag cf. M. praecox Haas

*

sITICLI

.'b.'-.-P-Vi-':

N

 I

E

formation Cody shale 

Frontier

Faunal zones of Black Hills which

are present in western Powder

River basin 1

«>

rt 

J=

1

u

'l

 2

E

.8

so

« "3

<D

fc

i

Scaphites corvensis Cobban

Scaphites whitjieldi Cobban

Inoceramus labiatus Schlotheim

Metoicoceras whitei Hyatt

Metoicoceras n.sp.

Metoicoceras praecox Haas

Acanthoceras? n.sp.

Acanthoceras? amphibolum Morrow

Calycoceras sp.

' Indicates relative position of diagnostic fossils 1 Modified after Cobban (1951)

FIGURE 20. Diagram (not to scale) showing the occurrence of faunal zones of the Black 

Hills region in the Frontier formation of the Crazy Woman Creek area and Tisdale 

anticline.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 61

shale in the Black Hills. Acanthocerasf n. sp. was found 400 feet 

above the base of the Frontier formation and correlates with the 

upper zone of the Belle Fourche shale. The topmost conglomerate 

ledge contains Metoicoceras cf. M. praecox Haas which resembles M. 

praecox Haas, the diagnostic form of the lowest faunal zone of. the 

Greenhorn formation, which overlies the Belle Fourche shale in the 

Black Hills. Metoicoceras cf. M. praecox Haas is slightly more advanced than M. praecox Haas and is probably slightly younger 

(Cobban, personal communication, 1952). The lowermost Belle 

Fourche faunal zone, characterized by Calycoceras n. sp., was not 

found in the mapped area but is present on the northeast flank of 

the Tisdale anticline 19 miles south of the Crazy Woman Creek area. 

The part of the Frontier formation of Belle Fourche age is much 

more sandy than its Black Hills equivalent, and the uppermost 

sandstone of the Frontier formation, which is lowermost Greenhorn 

in age, contrasts sharply with the marls, limestones, and shales in the 

lower part of that unit in the Black Hills.

The contact between the Mo wry shale and the overlying Frontier 

formation is arbitrarily placed at the base of the first bentonite bed 

above the siliceous shale. Beds above the contact are nonsiliceous, in 

contrast with siliceous beds below.

CODY SHALE

The Cody shale overlies the Frontier formation. At Elgin Creek 

the shale is about 3,670 feet thick and is about the same thickness in 

the North Fork Powder River well. However, equivalent rocks in the 

Amerada Petroleum Co.'s deep test at Smith Cut, 3 miles south of 

the mapped area, are about 3,100 feet thick. The amount of thinning within the mapped area is not known, but it is probable that the 

Cody shale in the Billy Creek and Steel Creek anticlines is considerably thinner than at Elgin Creek. Almost the entire sequence is soft 

and forms slopes. Strata whose age equivalents range from lower 

Greenhorn through Claggett are included in the Cody shale.

The lower 320 feet is equivalent in age to the Greenhorn formation 

and consists domintantly of dark-gray shale. The basal 35 feet of this 

sequence contains some soft conglomeratic sandstones interbedded 

with shale; the upper 40 feet consists of light-gray fine- to mediumgrained soft calcareous sandstone. Shale just below this sandstone 

is also calcareous. Metoicoceras n. sp., characteristic of the lower part 

of the Greenhorn formation of the Black Hills, was not found in the 

Cody shale of the Crazy Woman Creek area but was found in the 

Frontier formation of the northeast flank of the Tisdale anticline, 

19 miles south of the mapped area. Fossils of the Metoicoceras whitei 

Hyatt zone of the upper middle part of the Greenhorn formation were 

found about 100 feet above the base of the Cody shale, and the Inocer-
62 CONTRIBUTIONS TO ECONOMIC GEOLOGY

amus labiatw Schlotheim zone characteristic of the uppermost Greenhorn was found at the top of that part of the Cody shale that is of 

Greenhorn age.

Overlying the 40-foot sandstone at the top of the sequence of rocks 

of Greenhorn age is 45 feet of interlaminated shale and fine-grained 

sandstone which contains the /Scaphites whitfieldi Cobban zone, characteristic of the middle part of the Turner sandy member of the Carlile 

shale. The lower Carlile f aunal zones typical of the unnamed member 

of the Carlile shale beneath the Turner sandy member in the Black 

Hills appear to be absent in the Crazy Woman Creek area. These 

two zones are also absent in the Bighorn and Wind River Basins to 

the west and southwest.

Overlying the sequence of middle Turner age in the mapped area 

is approximately 115 feet of dark-gray silty shale, the lower 20 feet 

of which contains several beds of ironstone concretions and the upper 

95 feet of which contains septarian concretions. The 95-foot unit 

contains an abundant fauna, including Scaphites corvensis Cobban, 

which is diagnostic of the Sage Breaks member of the Carlile shale 

of the Black Hills (pi. 10).

In the vicinity of the Tisdale anticline the First Wall Creek sand 

of drillers, which forms the top unit of the Frontier formation of that 

area, occurs above a sequence which resembles the lithology of the 

Scaphites whitfieldi Cobban zone and below shales containing a Sage 

Breaks fauna. It is probable that this sandstone, which wedges out 

north of the Tisdale anticline and about 4 to 5 miles south of the 

Crazy Woman Creek area, is equivalent to the upper part of the Turner 

or the lower part of the Sage Breaks members of the Carlile shale. 

In summary, the upper part of the Frontier formation of the Tisdale 

anticline includes beds of Greenhorn and Turner age, whereas in the 

Crazy Woman Creek area these beds are included in the Cody shale.

The next higher 200 feet of section is poorly exposed and consists 

largely of dark-gray shales. About 160 feet above the base of the unit 

is a persistent siltstone concretion zone weathering light rusty brown, 

in which the concretions are as much as 10 feet in diameter. This zone 

contains an abundant fauna characteristic of the lower part of the 

Niobrara; the 2 most abundant forms are Inoceramus deformis Meek 

and /Scaphites preventricosus Cobban (pi. 10). This concretionary 

zone has been mapped throughout the area and is well developed along 

U. S. Highway 87, at a point 20 miles south of the mapped area.

The overlying 750 feet is dominantly soft gray chalky shale, which 

is usually poorly exposed; it is lithologically unfavorable for the preservation of fossils. The only fossils found in the unit in the mapped 

area are Ostrea congesta Conrad encrusting thick-shelled Inoceramus 

sp. A similar unit in a similar stratigraphic position in the Black 

Hills also contains this fauna. Abundant specimens of flattened
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 63

mollusks were found in the unit 20 miles south of the Crazy Woman 

Creek area, half a mile east of U. S. Highway 87, along the south bank 

of the South Fork Powder River. This fauna includes one scaphite 

questionably identified as /S. depressus Reeside, a form diagnostic of 

the middle part of the Niobrara. The remaining calcareous shale 

sequence is poorly exposed; no other Niobrara faunal zones were 

found.

The next higher 1,100 feet of section consists essentially of interlaminated dark-gray shale and light-gray fine-grained sandstone with 

many zones of siltstone and many beds containing light-gray septarian 

concretions. No fossils were found in the lower 300' feet of the 

sequence, but it may be equivalent to the Telegraph Creek. From 300 

feet above the base to the top of the unit the sequence contains many 

varieties of both Scaphites Tdppocrepis (De Kay) and ScapMtes 

aquilaensis Reeside. These forms are characteristic of the Eagle sandstone of Montana.

The next younger unit of the Cody shale is the Shannon sandstone 

member, which is about 200 feet thick. This unit consists dominantly 

of pale-olive very fine to fine-grained glauconitic sandstone with many 

thin partings of dark-gray shale. A disaggregated discrete sample of 

the Shannon sandstone member has relatively equant and angular 

grains ranging in intermediate intercept from 0.1 to 0.2 millimeter. 

The sample shows a significant percentage of transparent and cloudy 

feldspar, but it is dominantly clear quartz. Polylobate glauconite is 

very abundant; minor constituents are biotite, muscovite, chlorite, 

black chert, and dark-gray opaque grains. Locally this unit contains 

rusty brown-weathering fossiliferous siltstone concretions as much as 

4 feet in diameter. The concretions contain Baculites aquilaensis 

Reeside, which is also characteristic of the Eagle sandstone of Montana. Locally, also the Shannon sandstone member forms resistant 

hogbacks, but in places the sequence is soft and is mapped only with 

difficulty.

Overlying the Shannon sandstone member of the Cody shale is a 

soft grayish-black shale which is approximately 900 to 950 feet thick. 

The lower 80 feet of this unit contains zones of small ellipsoidal dark 

reddish-brown concretions and resembles the upper part of the Gammon ferruginous member of the Pierre shale of the Black Hills. This 

upper sequence corresponds in stratigraphic position to the Claggett 

shale of Montana.

Shale in surface sections of the Cody shale is calcareous only in 

rocks believed to be Greenhorn or Niobrara in age. The contact between the Frontier formation and the Cody shale is marked by a 

change from resistant conglomeratic sandstone below to nonresistant 

shale with some sandstone above.
64 CONTRIBUTIONS TO ECONOMIC GEOLOGY 

PARKMAN SANDSTONE

The Parkman sandstone, which overlies the Cody shale, forms a 

prominent ridge extending from the southern margin of the Powder 

River Basin northward through the mapped area into Montana. In 

the Crazy Woman Creek area the Parkman sandstone attains a maximum thickness of 720 feet. The unit is dominantly a yellowish-gray 

sandstone, the lower half of which contains large moderate-brown 

ellipsoidal concretions.

Sandstone in the lower part is fine- to medium-grained, angular 

to subangular, and has a ratio of long to intermediate intercept of 1.5. 

The grains are composed dominantly of quartz with many inclusions; 

most of the grains are translucent to opaque and are coated with limonitic material. A few zones of dark-gray shale are interbedded with 

the sandstone.

A 25-foot moderate-brown carbonaceous shale is present near the 

top, and the formation is capped by an 8-foot white to very light gray 

crossbedded sandstone. This sandstone is fine- to medium-grained, 

angular to subangular, and with a long to intermediate intercept ratio 

of 1.5. The grains are dominantly of quartz with 5 to 10 percent 

feldspar. The sandstone is argillaceous and contains minor amounts 

of biotite. In reflected light most of the grains appear cloudy and 

light colored.

The Parkman sandstone of the mapped area is referred to as the 

Mesaverde formation 15 miles south of the mapped area. There the 

Mesaverde formation is divided into three units: the Parkman sandstone member at the base, an unnamed member just above the middle, 

and the Teapot sandstone member at the top. The white to very light 

gray 8-foot sandstone at the top of the Parkman sandstone in the 

Crazy Woman Creek area is probably equivalent to the Teapot sandstone member of the Mesaverde formation, but the lower members of 

the Mesaverde formation cannot be recognized as distinct units in the 

mapped area.

The contact between the Cody shale and the Parkman sandstone 

is sharp. Beds below the contact are soft grayish-black shale, and 

beds above are yellowish-gray sandstone. A remnant of sandstone 

of about the same age as the Parkman is in the Pierre shale of southeastern Montana. The formation is absent along the western margin 

of the Black Hills; it probably thins eastward from the mapped area 

and grades into the dark-gray shales of the Pierre shale. North of 

the Wyoming-Montana State boundary the Parkman sandstone is 

called the Judith River formation (Andrews and others, 1944).

BEARPAW SHALE

The Bearpaw shale, which overlies the Parkman sandstone, is about 

200 feet thick and consists mainly of dark-greenish-gray shale with
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 65

light-gray siltstone laminae. The unit is soft and is commonly covered with slopewash at most places. The upper 15 feet grades from 

silty shale near the base to shaly sandstone 2 to 3 feet thick at the 

top. The upper 6 inches of the Bearpaw shale consists of grayishyellow bentonite. Baculites compressus Say and AcanthoscapJiites 

nodosus (Owen) were found in the upper part of the formation and 

are diagnostic of part of the Bearpaw shale of Montana (pi. 10). 

Formerly the sequence in the Crazy 'Woman Creek area had been included in the Piney formation of Darton (1906). The contact between 

the Parkman sandstone and the Bearpaw shale is characterized by 

white sandstone below and olive-gray shales above.

LANCE FORMATION

The Lance formation, which overlies the Bearpaw shale, is poorly 

exposed throughout most of the mapped area. It ranges in thickness 

from 1,950 to 2,200 feet. The lower 100 feet consists of drab-brown 

thin-bedded fine-grained shaly sandstone with many partings of darkgray shale. The next higher 500 feet of strata is a series of lenticular 

yellowish-gray crossbedded sandstone beds some of which are as 

much as 70 feet thick interbedded with dark-gray shales. A discrete 

sample of the lenticular sandstone of the Lance formation is fine 

to medium grained. The grains range in length of intermediate intercept from 0.15 to 0.35 millimeter and have a ratio of long to 

intermediate intercept of 1.3. The grains are dominantly quartz 

with minor feldspar; most of them have a cloudy appearance in reflected light. The rock contains abundant dark-gray to black translucent to opaque grains and minor amounts of biotite and chlorite. 

Grains range from subrounded to angular. The remainder of the 

Lance formation consists of interbedded light- to yellowish-gray soft 

sandstones and dark-gray shales. Beds of carbonaceous shale are 

present throughout the upper half of the unit.

The contact between the Bearpaw shale and the Lance formation 

is arbitrarily placed at the top of the 6-inch bentonite bed. Beds 

directly above the contact are similar to beds below but grade upward 

into a thin-bedded shaly sandstone unit which is different from the 

shales of the Bearpaw.

The lower 600 feet of the formation, which contains dinosaur bones, 

is of Late Cretaceous age. No fossils have been found in the upper 

part of the Lance formation within the mapped area, and the assignment of the entire Lance formation to the Upper Cretaceous is one 

of convenience. The lower 100 feet of the Lance formation may, in 

part, be equivalent to the Fox Hills sandstone, a well-developed 

resistant marine sandstone unit of Late Cretaceous age, which is recognized about 20 miles south of the Crazy Woman Creek area.
66 CONTRIBUTIONS TO ECONOMIC GEOLOGY

CENOZOIC BOCKS 

FORT UNION FORMATION

The Fort Union formation overlies the Lance formation with apparent conformity. The Fort Union formation is overlain unconformably in the Kingsbury Ridge area by the Kingsbury conglomerate 

member of the Wasatch formation, but farther south it is overlain with 

apparent conformity by the shales and sandstones of the finer grained 

facies of the Wasatch formation.

In the vicinity of Billy triangulation station the Fort Union formation is approximately 3,950 feet thick. Here the lower 500 feet 

contains many beds of moderate-brown ferruginous resistant sandstone ledges interbedded with siltstone and shale. The next higher 

1,900 feet of strata consists dominantly of very light gray siltstone 

and gray shaly sandstone with some thin reddish-brown resistant 

ferruginous sandstone ledges. A discrete sample of sandstone from 

this zone contains grains ranging in intermediate intercept from 0.2 

to 0.5 millimeter and has a ratio of long to intermediate intercept of 

1.2. Grains are angular to subangular. The rock contains moderate 

amounts of somewhat weathered feldspar but is dominantly quartz. 

In reflected light about one-fourth of the grains are cloudy. Lightcolored mica is present in moderate amounts, and black opaque grains 

are abundant.

The remainder of the sequence contains many thick zones of carbonaceous shale interbedded with siltstone and includes many lenticular 

beds of conglomerate which are very similar to those in the Kingsbury 

conglomerate member of the Wasatch formation. The conglomerates 

contain mostly quartzitic sandstone pebbles, minor amounts of dolomite and limestone pebbles, and rare pebbles of pre-Cambrian igneous 

rocks apparently derived from the Bighorn Mountains. These lenses 

of conglomerate do not extend south of Crazy Woman Creek in the 

mapped area, nor do they extend farther north than 1 mile north of 

Billy triangulation station. However, along Rock Creek, 13 miles 

north of the mapped area, conglomerates of this type again appear in 

the upper part of the Fort Union formation; they also are present 

12 miles south of the mapped area. Pebbles and cobbles in the upper 

part of the Fort Union formation 12 miles south of the mapped area 

consist dominantly of quartzite and highly siliceous metasediments, 

which contrast sharply in type with those found to the north. Just 

south of Crazy Woman Creek the upper part of the Fort Union formation contains 8 coal beds and many carbonaceous shales. The coal 

beds attain maximum thickness between 1 and 5 miles south of Crazy 

Woman Creek; southward they grade into thin zones of carbonaceous 

shale. No coals are in the Fort Union formation north of Crazy 

Woman Creek. The carbonaceous shales can be traced southward to
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 67

where they pinch out about 2 to 5 miles north of the southern boundary 

of the mapped area.

The contact between the Lance and Fort Union formations is 

arbitrarily placed at the base of a series of slabby resistant ferruginous 

sandstone ledges. Beds just above the contact are resistant and form 

persistent rounded ridges; beds below the contact are soft sandstones 

and shale which form slopes. No angular unconformity was noted 

within or at the base of the Fort Union formation. In the Rock 

Creek area, however, Mapel (personal communication, 1952) reports 

an angular unconformity at the base of the conglomeratic sequence 

within the Fort Union formation. R. W. Brown (personal communication, 1952) collected Paleocene plants from the Fort Union 

formation of the mapped area.

WASATCH FORMATION

The Wasatch formation is exposed in the eastern part of the Crazy 

Woman Creek area. From Kingsbury Ridge northward to a point a 

few miles south of Sheridan, Wyo., the Wasatch formation is divisible 

into two distinct members the Kingsbury conglomerate member 

below and the Moncrief member above which are separated by an 

angular unconformity of as much as 45 degrees. The discordance 

between the two members diminishes sharply basinward and separation becomes difficult, both structurally and lithologically. The lower 

unit was called the Kingsbury conglomerate by Darton (1906), but 

in this report it will be treated as a member of the Wasatch formation 

following Love and Weitz's (1951) consideration of the unit and, 

more specifically, as the coarse basal mountainward fades of the 

Wasatch formation. The upper member has been called the Moncrief 

gravel by Sharp (1948) but was later called the Moncrief member of 

the Wasatch formation (Love and Weitz, 1951).

The Kingsbury conglomerate member of the Wasatch formation 

unconformably overlaps the Fort Union formation (pi. 6, cross section 

A-A'), and north of the mapped area it successively overlaps the 

Lance formation, the Bearpaw shale, and the Parkman sandstone. 

Four miles north of the mapped area the Kingsbury conglomerate 

member is unconformably overlain by the Moncrief member of the 

Wasatch formation. Southward and eastward from Kingsbury 

Ridge the Kingsbury conglomerate member thins and grades imperceptibly into the finer basal, basinward part of the Wasatch formation; the Moncrief member grades imperceptibly into the finer 

facies of the upper part of the formation. In the vicinity of Kingsbury Ridge the Kingsbury conglomerate member ranges in thickness 

from 400 to 600 feet. The unit contains a series of interbedded poorly 

indurated conglomerates, medium- to coarse-grained sandstones, siltstones, and silty shales (fig. 21).. Typically the conglomerate has a
CONTRIBUTIONS TO ECONOMIC GEOLOGY

FIGURE 21. Southwest face of Kingsbury Ridge showing approximate contact between the 

Kingsbury conglomerate member of the Wasatch formation (Twk) and the Fort Union 

formation (Tfu).

medium- to coarse-grained matrix with moderate amounts of black, 

pink, and green accessory grains. The well-rounded pebbles and 

cobbles consist of limestone, dolomite, quartzite, chert, and rarely of 

deeply weathered pre-Cambrian igneous rocks. Many collections 

of fresh-water invertebrates indicate an Eocene age for the Kingsbury 

conglomerate member. The assemblage identified by T.-C. Yen is 

as follows: Pisidium sp., Hydrobia? eulimoides Meek, Goniobasis cf. 

Gf. tenera (Hall), Viviparus cf. V. returns Meek and Hayden, Physa 

cf. P. longiuscula Meek and Hayden, Macrocyclus sp., Discus cf. D. 

rcdstonensis (Cockerell).

Two miles north of Kingsbury Ridge the flat-lying Moncrief member of the Wasatch formation rests unconformably on the Kingsbury 

conglomerate member. The Moncrief member in that area is about 

1,200 feet thick (Sharp 1948). The lower third of the Moncrief 

member consists of interbedded greenish siltstone, silty sandstone, 

grits, and thin beds of conglomerate; it grades upward into coarse 

boulder beds, in which the boulders are dominantly deeply weathered 

pre-Cambrian igneous rock. A typical sandstone of the lower part 

of the Moncrief member is dominantly medium- to coarse-grained, but 

some of the grains are in the fine and granule sizes. The larger grains 

are relatively equidimensional and well rounded; the smaller grains
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 69

are less equidimensional and subangular to subrounded. The sandstone includes minor amounts of greenish biotite and hornblende as 

well as moderate amounts of translucent to opaque altered feldspars. 

Some lithic fragments are likewise present. The top of the northern 

part of Kingsbury Eidge is characterized by boulders as large as 5 

feet in diameter. Some of these boulders are derived from Paleozoic rocks; Sharp (1948) suggests that this material was deposited in 

late Cenpzoic time as a result of erosion of Bald Kiclge and the Bighorn Mountains and is not a part of the Kingsbury conglomerate 

member. The part of the Wasatch formation which overlies the 

Kingsbury conglomerate member in the region east and southeast of 

Kingsbury Ridge comprises the finer clastic basinward facies of the 

Moncrief member.

South of the southernmost limit of the Kingsbury conglomerate 

member the Wasatch formation includes equivalents of both the 

Kingsbury conglomerate member and the Moncrief member. The 

Wasatch formation, where it contains equivalents of both of these 

members, attains a thickness of about 500 feet in the mapped area. 

The basal portion of the Wasatch formation, in part the Kingsbury 

conglomerate member equivalent, is best developed south of Crazy 

Woman Creek, where its maximum thickness is about 150 feet. The 

sequence consists of red and dark-green soft claystones with lenticular 

calcareous medium- to coarse-grained sandstone lenses. The larger 

grains of these lenticular sandstones are equant and well rounded, but 

grains of the smaller fraction are somewhat elongate and angular. 

Although it is dominantly a quartzose sandstone, moderate amounts 

of orthoclase, microcline, and rocks fragments are present. Some of 

the quartz grains are discolored by hematite, which imparts a red color 

in reflected light. Black translucent to opaque grains are abundant. 

The calcite cement is in part poikilitic. The basal part is of various 

thicknesses and southward is less brightly colored. The zone persists as far southeast as Sussex, Wyo., 15 miles from the mapped area.

The upper part of the Wasatch formation, the lateral equivalent 

of the Moncrief member, consists of soft argillaceous sandstones, siltstones, shales, many carbonaceous shales, and 6 major coal beds, one 

of which is as much as 7 feet thick. Associated with the coals in 

places is a red slaglike rock which has been called clinker. There 

are two different rock types included in clinker. One is formed from 

burned coal and resembles clinker found in a coal-burning stove; 

the other is formed by fusion and oxidation of the enclosing sediments as a result of burning of coal. The coals can be traced northeast along Crazy Woman Creek for many miles, but they thin southward and are absent at the southern boundary of the mapped area. 

The coal and carbonaceous shale portion of the Wasatch formation
70 CONTRIBUTIONS TO ECONOMIC GEOLOGY

grades, in the southern part of the mapped area, into a sequence of 

coarse-grained tan sandstone and drab-greenish-gray siltstone. The 

sandy facies of the formation contains many lenses of ferruginous 

material, which locally imparts a red color to the unit. These sandstones, about 5 miles south of the mapped area, are conglomeratic 

and contain pebbles of quartzite and chert. The contact between the 

Fort Union formation and the Wasatch formation is marked by a 

lithologic change from coals or carbonaceous shales below to soft red 

and green claystones with intercalated sandstone lenses above. In 

places where the Kingsbury conglomerate member of the Wasatch 

formation truncates the Fort Union formation, the contact is characterized by coarse conglomerate above and nonconglomeratic beds 

below.

The red claystones of the basal portion of the Wasatch formation 

yielded a few mammal teeth of early Eocene age. Fossils found from 

200 to 400 feet above the redbed sequence of the Wasatch formation 

of the Sussex region are more abundant and indicate a very early 

Eocene age (Gray Bull of Granger, 1914) for that part of the Wasatch 

formation. The fossils found in the Sussex region are as follows: 

Multituberculata, Ectypodus cf. tovrdus; Insectivora, Cynodontomys 

sp.; Primates, Petycodus sp., Tetonius sp., Phenacolemur sp.; Creodonta, Sinopa, Pachyaena; Carnivora, Viverravus; Condylarthra, 

Hyopsodus sp., Ectocion sp., Haplomylus sp., Phenacodus sp.; Perissodactyla, Hyracotherium; Artiodactyla, Diacodexis.

The upper 50 feet of the Wasatch formation in the southeastern part 

of the Crazy Woman Creek area contains Hyopsodus simplex, a form 

characteristic of the lower Eocene (Gray Bull of Granger). Brown 

(1948) found Coryphodon sp. and HymcotJierivm, (Eohippus) sp. 

in a zone slightly higher than the Kingsbury conglomerate member 

of the Wasatch formation. This form is present throughout lower 

Eocene strata.

WHITE RIVER FORMATION

On the subsummit uplands of the Bighorn Mountains there are a 

number of almost flat-lying deposits of similar sedimentary rocks. 

Osterwald (1949) called these rocks in the Tongue Eiver area the 

White River (?) formation, basing the assignment on vertebrates of 

Oligocene age collected from these deposits (Osterwald, personal communication, 1951). Because of the similarities of the deposits in the 

Crazy Woman Creek area to the material in the Tongue River area 

as well as in other parts of Wyoming, they are herein referred to as 

the White River formation. The strata are almost flat lying and 

unconformably overlap the pre-Cambrian and Paleozoic strata. The 

White Rive.r formation fills pre-Oligocene valleys of high relief and 

usually forms flat grassy parks. The formation is best exposed 1 mile
GEOLOGY OP CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 71

FIGURE 22. Conglomerate of the White River formation on Canyon Fork Powder River 

10 miles west of the Crazy Woman Creek area.

west of the mapped area along the North Fork Crazy Woman Creek, 

where it attains a maximum thickness of 200 to 300 feet. Here the 

sequence consists of light-brown bentonitic claystones interbedded 

with conglomerates cemented by calcium carbonate and very light 

gray tuffaceous marlstones. The conglomerates in the northern part 

of the area contain angular fragments of igneous rocks ranging in 

diameter from y% to 7 inches (fig. 22) ; at the north end of the Horn 

the conglomerate contains some fragments derived from Paleozoic 

rocks. Thin sections of the finer part of this conglomerate show irregularly shaped grains of feldspar, quartz, blue-green hornblende 

andbiotite, all of which are usually surrounded by thin bands of radial 

calcite; these are embedded in a finely crystalline nonoriented calcite 

matrix. Many microscopic calcite-lined vugs are present and fractures 

in grains of feldspar, hornblende, and rock fragments are filled with 

calcite oriented at right angles to the fracture. The matrix is argillaceous; the very fine insoluble residue is a light-brown clay of the 

same type as the interbedded claystones.

QUATERNARY ROCKS

Three types of surficial deposits of Quaternary age were mapped in 

the Crazy Woman Creek area: landslide debris, terrace gravels, and 

alluvium. Landslide debris is present in places in the basin area but
72 CONTRIBUTIONS TO ECONOMIC GEOLOGY

is of such limited extent that mapping is impracticable. Landslide 

debris in the steep canyons cut in the pre-Cambrian terrane consists 

of angular fragments and blocks of granite; in other places in the 

mountain area it consists of slumped rocks from the Gros Ventre formation and the Gallatin limestone, as well as large blocks derived 

from the more resistant Bighorn dolomite and Madison limestone. 

Landslide debris in both the mountain and basin areas includes 

homogeneous bodies of material emplaced as discrete but broken units 

as well as individual blocks.

Gravels cap many terrace levels. On older terraces gravel deposits 

range in thickness from 5 feet in the eastern part of the mapped 

area to as much as 20 feet close to the mountain front. These gravels 

consist of pebbles, cobbles, and boulders mainly derived from the 

pre-Cambrian crystalline rocks of the Bighorn Mountains, with minor 

amount of limestone and dolomites derived from Paleozoic rocks 

(fig. 23). The oldest terrace gravels are coarser grained in most 

places than the younger ones. The youngest terraces are covered 

chiefly with sand and silt but locally are capped by gravel. The finer 

portion of the gravels on all terraces ranges in size from clay through 

granule in almost equal proportions. The oldest terraces that abut 

against the Tensleep sandstone at the mountain front are covered 

with a veneer of angular blocks derived from the Tensleep sandstone.

FIGURE 23. Gravel of terrace level 2 n the North Fork Crazy Woman Creek. 

Gravel rests on eastward-dipping Cody shale.
GEOLOGY OP CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 73

The veneer thickens toward the mountain. The edges of terraces 

which abut against bedrock or against the "riser" of a higher terrace 

usually have cover of colluvial material sloping toward the streams. 

Terraces of the Crazy Woman Creek area are of many complexly 

related levels; they are classified only in the broudest sense. The 

following list shows ranges of terrace levels above adjacent streams 

using symbols appearing on the geologic map (pi. 6) : Qtg5 is more 

than 300 feet above adjacent streams; Otg4 ranges in height from 

130 to 300 feet, Qtg3 from 90 to 130 feet, Qtg2 from 40 to 90 feet, and 

Qtgx from 5 to 40 feet. Deposits on levels below 5 feet are considered 

as alluvium.

Although alluvium is present along the beds of most streams, it 

was not feasible to show it in most places on the scale of mapping. 

The alluvium is a mixture of clay, silt, and sand, commonly containing much organic matter; it also contains pebbles and cobbles locally.

STRUCTURE

REGIONAL FEATURES

The Crazy Woman Creek area includes parts of both the Bighorn 

Mountain and the Powder River Basin structural provinces. The 

central part of the Bighorn Mountains as well as the. adjoining Powder River Basin trend approximately N. 15° to 20° W. .In the 

mountain province the folds are more intense than those in the basin. 

Anticlines of the mountain province have their steeper limb on the 

west, in contrast with those of the basin which have their steeper 

limb on the east. High-angle reverse faults predominate, but some 

thrust faults of minor displacement and normal faults are present. 

Except for four minor transverse faults, they are restricted to the 

mountain province. The foliated pre-Cambrian "granite" north of 

the Horn and west of the base of the Flathead sandstone trends 

almost at right angles to the axis of the range and dips from approximately 45 degrees northward to vertical. Except for local folds 

and faults the sedimentary rocks dip generally eastward, giving 

structural relief of more than 18,000 feet. The Tertiary strata of 

the eastern portion of the area dip gently eastward; the maximum 

dip at the base of the Wasatch formation is 13 degrees (fig. 17). 

An exception to the easterly dip was noted on the southeast bank of 

Crazy Woman Creek (pi. 6).

Darton (1906) discussed the structural geology of the Crazy Woman 

Creek area only generally. Chamberlin (1940), in discussing the 

mountain ranges around the Bighorn Basin, considered the Bighorn 

Mountains to be composed of three asymmetrical segments (fig. 25). 

Demorest (1941), in his study of the east flank of the Bighorn Mountains, followed the general outline suggested by Chamberlin. The
74 CONTRIBUTIONS TO ECONOMIC GEOLOGY

north and south segments of the range have their steep limbs on the 

west side, and the central segment has its steep limb on the east. The 

central segment is outlined by the Tongue River on the north and by 

the Tensleep and Horn faults on the south. The Crazy Woman Creek 

area lies within the central segment.

Structure contours (pi. 6) with 1,000-foot intervals were drawn on 

the base of the Flathead sandstone as far east as the base of the Newcastle sandstone. Contours with the same interval were drawn on 

the base of the Newcastle sandstone for younger Cretaceous and 

Paleocene strata. Structure cross sections (pi. 6) were used as checks 

against computations of depth to datum surfaces from points where 

elevations and surface dips as well as thickness of stratigraphic units 

were known. In Tps. 48 and 49 N., K. 80 W., contours with 10-foot 

intervals were drawn on coal bed 6; this bed was selected because it 

had the longest outcrop and covered the greatest area.

FOLDS AND FAULTS

Pre-Cambrian granites of the Crazy Woman Creek area are intensely foliated. At the northern end of the Horn, including a few 

square miles just west of the mapped area, the granite forms an anticlinal fold with the axis plunging northwestward at about 50 degrees. 

The strike of foliation on the west flank is approximately N. 20° W.; 

the dip is about 60 degrees to the southwest. Foliation on the northeastern flank trends approximately N. 75° W. and dips approximately 

65 degrees to the northeast. The foliation is unconformable with the 

attitude of beds of the Paleozoic sequence. Strike of foliation of the 

granite north of the Horn within and, in part, a few miles west of the 

mapped area, ranges from N. 35° E. to east-west and dip ranges from 

35 degrees northward to vertical.

North of the North Fork Crazy Woman Creek within the mapped 

area, dips in the Paleozoic and Mesozoic rocks range from 30 degrees 

east to vertical and in some places beds are overturned and dip steeply 

westward. (See pi. 6, structure section A-A''.) In the northern part 

of the area there are three westward-dipping, generally northwardtrending reverse faults. Along each fault the pre-Cambrian granite 

has been moved over the lower part of the Cambrian sequence. In the 

northernmost part of the mapped area a reverse fault trends about 

N. 25° E., oblique to the strike of bedding and then trends eastward 

and becomes a transverse fault.

South of the North Fork Crazy Woman Creek, dips of the strata 

are more gentle, and the width of outcrop of Paleozoic rocks ranges 

from 2 to 7" miles. The transition from gentle dips in the south to high 

dips in the Paleozoic rocks north (fig. 24) of the North Fork Crazy 

Woman Creek is marked by a reverse fault which trends obliquely
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 75

FIGURE 24. View of the abrupt change from moderate to high dips in Paleozoic strata 

on the North Fork Crazy Woman Creek.

across the strike of the formations at its southern end and then curves 

eastward to become a transverse fault. Because of the greater intensity of deformation north of the fault when compared with the area to 

the south, it seems reasonable to assume that the resulting shearing 

stress was relieved by the fault. South of the North Fork Crazy 

Woman Creek structural configuration in the mountain area, although 

less intense, is somewhat more complex. This portion of the mapped 

area contains three southeastward-plunging asymmetric anticlines 

with steep and faulted west limbs. The steep limb of anticlines on the 

mountainward side of basins is quite common, particularly in the Bighorn Basin (Pierce and others, 1947). This characteristic direction 

of asymmetry may be explained by what Thorn (1936, p. 210) has 

called "basin mechanics."

The northernmost anticline, the West Billy Creek anticline of 

Demorest (1941), is approximately 7 to 8 miles long. The northern 

end of this fold is in part overturned and thrust westward. The 

thrust (low-angle reverse fault) has minor westward displacement 

and is truncated at its northern end by a transverse fault. North and 

east of the thrust fault is a reverse (high-angle) fault, with the eastern 

block upthrown, which trends about N. 20° E. at its southern end and 

about N". 70° E. at its northern end. It is probable that this fault

339462 55 4
76 CONTRIBUTIONS TO ECONOMIC GEOLOGY

antedates the transverse fault at the north end of the anticline and 

was at one time continuous with the thrust fault. Southward the 

thrust fault passes into a reverse fault and disappears in the Amsden 

formation. The fault along the southwestern side of the anticline is 

a reverse fault with the east block upthrown. (See pi. 6, structure 

section B B''.) The anticline loses its identity about 1 mile south of 

the Middle Fork Crazy Woman Creek.

The Beaver Creek anticline of Demorest (1941), just south of the 

Middle Fork Crazy Woman Creek, is also asymmetrical with its southwest side marked by a reverse fault in which the eastern block is upthrown. The Beaver Creek anticline is about 3 miles long and is 

breached to the pre-Cambrian basement at its northern end.

The Horn, a large southeastward-plunging anticlinal fold breached 

to the pre-Cambrian rocks, lies in the southwestern part of the 

mapped area. The fold is bounded on the southwest by the Horn 

fault, a reverse fault with more than 4,000 feet of throw in its central 

portion; the eastern block is upthrown. Paralleling this fault about 

a quarter of a mile to the southwest is a low-angle thrust fault, the 

overriding (northeast) block of which has moved relatively southwestward and has placed Chugwater strata in contact with the 

Sundance formation. In gross aspect the area lying between the 

two faults is an overturned syncline modified by transverse faulting. 

(See pi. 6, structure section C C''.) Within the mapped area the 

Horn anticline is terminated at the north by a transverse fault which 

may be a branch of the Tensleep fault to the west (Wilson, 1938).

In the part of the mapped area that lies within the Powder River 

Basin, the structure is less complex than in the mountains. The 

major features include two closed anticlinal folds and one structural 

terrace. The Billy Creek anticline (pi. 6, structure section B B') 

is asymmetrical, with dips on the east flank as much as 25 degrees 

and dips on the west flank as much as 10 degrees. The crest of the 

anticline trends about 1ST. 20° W., but Bramlette (1949, p. 83) reports 

that the subsurface axis trends more northwesterly. Surface closure 

on the Billy Creek anticline is about 400 to 500 feet.

The Steel Creek anticline is also asymmetrical with its steeper 

limb on the east flank. (See pi. 6, structure section C C'.} Dips 

on the east flank are as much as 30 degrees; on the west flank the 

maximum dip is 7 degrees. Surface closure on the Steel Creek 

anticline is about 300 feet.

About 2.5 miles south of Crazy Woman Creek, in sec. 22, T. 47 N., 

R. 81 W., and adjacent sections, there is a structural terrace. Along 

an east-west line through the terrace, beds in the upper part of the 

Fort Union formation dip eastward about 9 degrees. Beds in the 

lower part of the Wasatch formation are horizontal for about threefourths of a mile and then assume an eastward dip of approximately
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 77

6 to 8 degrees. The southern end of the structural terrace is cut by 

a transverse fault. At the northern end of the structure, just south 

of Crazy Woman Creek, dips decrease from 9 degrees eastward in 

the upper part of the Fort Union formation to approximately 4 

degrees eastward in the Wasatch formation 3 miles northeast of the 

structural terrace. South of the fault marking the southern edge of 

the structural terrace are three more transverse faults, in echelon, 

which cut both the upper part of the Fort Union formation and the 

lower part of the Wasatch formation.

STRUCTURAL HISTORY

In addition to both pre-Cambrian and Laramide orogenic movements, there were several periods of gentle regional uplift followed 

by erosion. The resulting unconformities, although angular, are 

SO slight that their effect on present structure is negligible, and they 

can be detected only by regional studies. The first regional uplift of 

this type occurred after deposition of the Bighorn dolomite and before deposition of the Madison limestone. Evidence supporting this 

uplift is found in the truncated Bighorn dolomite and the complete 

absence of Silurian and Devonian strata. The unconformity at the 

base of the Madison limestone truncates the Bighorn dolomite; in the 

southern part of the Bighorn Mountains the Madison rests unconformably on the Gallatin limestone. It is possible that there were 

several later uplifts rather than one, but, as there is no record in the 

rocks, this cannot be determined. If the Tensleep sandstone of the 

mapped area is Des Moines in age, the lack of younger Pennsylvanian 

strata, such as those in the Hartville region in eastern Wyoming (Love 

and others, 1953) and at Casper Mountain along the southern margin of the Powder River Basin (Thomas, 1948), suggests that one 

or more structural disturbances followed Des Moines time and preceded the deposition of the Permian red shale and gypsum sequence.

Meager evidence for uplift preceding the deposition of the Alcova 

limestone member of the Chugwater formation is found in the 

thinning of the pre-Alcova part of the Chugwater formation from 

700 feet in the mapped area to about 480 feet in the Texas Co.'s Forbes 

test well 1 in the north in Sheridan County, Wyo. (figs. 18 and 19). 

The various thicknesses of the so-called Crow Mountain sandstone 

member of the Chugwater formation (Carlson, 1949) and the absence 

of the younger Popo Agie member of the Chugwater formation, 

which is so widespread in central Wyoming, indicate gentle regional 

uplift and erosion of these rocks in northeastern Wyoming before the 

deposition of the Gypsum Spring formation and following deposition 

of the Chugwater formation. The truncation of the Gypsum Spring 

formation by the unconformity at the base of the Sundance formation 

in central Wyoming as well as in the mapped area indicates regional
78 CONTRIBUTIONS TO ECONOMIC GEOLOGY

uplift followed by erosion preceding deposition of the Sundance 

(figs. 18 and 19).

Laramide tectonic activity in the Bighorn Mountains began during 

the time of deposition of the Fort Union formation. In the northern 

part of the Crazy Woman Creek area and at Rock Creek, 13 miles 

north of the mapped area, the upper part of the Fort Union formation 

contains pebbles derived from Paleozoic rocks, indicating that uplift 

was followed by erosion of the Bighorn Mountains at least to the 

Bighorn dolomite and in part of the pre-Cambrian. Deformation was 

more intense in the central part of the Bighorn Mountains and was 

probably confined to the central segment of Demorest (fig. 25). This 

probability is supported by the fact that well-developed conglomerates 

in .the Fort. Union formation are confined to a belt directly east of 

the .central: segment.: Folding, following deposition of the Fort 

Union formation, resulted in as much as a 45-degree discordance between the Kingsbury conglomerate member of the Wasatch formation 

and the Fort Union formation in the vicinity of Kingsbury Ridge. 

Folding after the deposition of the Kingsbury conglomerate member 

of the Wasatch formation resulted in local dips in the unit as much 

as 45 degrees; the Kingsbury conglomerate member is unconformably 

overlain by the flat-lying Moncrief member of the Wasatch formation. 

Sharp (1948) has described thrust faulting that followed the deposition of the Moncrief member. This thrusting was not accompanied 

by even local folding of Wasatch strata in that part of the Powder 

River Basin which lies opposite the zone of thrusting along the east 

front of the Bighorn Mountains. In the Crazy Woman Creek area, 

however, beds which are equivalent to the lower part of the Moncrief 

member of the Wasatch formation dip as much as 9 degrees eastward; 

this suggests that the forces which produced post-Moncrief thrusting 

from Kingsbury Ridge north to Moncrief Ridge produced mild folding south of Kingsbury Ridge. The Fort Union formation is conformable with older units and is the youngest unit to be strongly 

folded regionally. It is therefore believed that at least the outlines 

of the major folds discussed above were formed, after deposition of 

the Fort Union and preceding the deposition of the Kingsbury.

ECONOMIC GEOLOGY

OIL AND GAS POTENTIALITIES

The discovery well for the Billy Creek gasfield was drilled in 1923 

and gas was found in the Frontier formation. Since that time, 7 

more producing wells have been drilled to the Frontier formation; in 

1937 a well was drilled to the basal sandstone of the Bighorn dolomite. The well penetrated neither gas nor oil in commercial quantities. Cumulative production to 1947, according to Bramlette (1949,
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 79

Fault, dashed whore approximately located 

Direction of dip of axial plane

FIOUUE 25. Geologic map of the Bighorn Mountains showing three major structural

segments.

p. 83), was 3,218,858 thousand cubic feet of gas. This production so 

depleted the field that it is now used as a storage reservoir for the gas 

coming from the Big Sand Draw field in Fremont County for use 

by the towns of Buffalo and Sheridan. Owing to the recent discovery 

of oil in the Tensleep sandstone in Stanolind's North Fork Powder 

Eiver field 24 miles to the south of the Billy Creek anticline, further 

testing of this sandstone in the vicinity of the Billy Creek anticline 

may be worth while.
80 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Three dry test holes have been drilled on the Steel Creek anticline 

thus far. A recent test well that penetrated the Amsden formation 

and reached the Madison limestone showed slight oil staining in the 

Permian red shale and gypsum sequence, but the Tensleep sandstone 

was barren.

The most promising untested structure within the mapped area is 

the structural terrace south of Crazy Woman Creek. Although there 

is no closure at the surface, geophysical data suggest that there is 

closure at depth. In the Sussex-Meadow Creek oilfield 20 miles south 

of the mapped area there is oil in the Parkman sandstone, the Sussex 

and Shannon sandstone members of the Cody shale, the Frontier 

formation, the Newcastle sandstone, the Cleverly formation, and the 

Tensleep sandstone. On the structural terrace it is estimated that a 

test hole 13,500 feet .deep would penetrate all these zones except the 

Sussex, which probably has graded into shale or wedged out in this 

area. A well drilled 52 miles north of the mapped area by J. Ray 

McDermott & Co. at Ash Creek in Sheridan County, Wyo., recently 

pumped 180 barrels per day of 36 gravity oil from what has been called 

the Shannon sandstone member of the Cody shale (Petroleum Information, 1952).

Stratigraphic data at the present are insufficient for predicting 

stratigraphic traps within the Crazy Woman Creek area. A few 

regional generalizations can be made, however, that may be useful in 

the search for oil accumulated in such traps.

The Parkman sandstone, which is overlain and underlain by marine 

shales, thins eastward so that it is unrecognizable on the east side of the 

Powder River Basin. The axis of the basin is located only a few 

miles east of the Bighorn Mountains and the thinning and wedging 

out would occur updip east of the axis. The topmost sandstone of the 

Frontier formation, which is equivalent to the Carlile in age at Tisdale anticline and which is probably the First Wall Creek sand, of 

drillers, that yields oil in the Sussex-Meadow Creek oilfield, thins 

northward and grades into shale a few miles south of the Crazy 

Woman Creek area. When more subsurface data are available, it may 

be possible to determine more precisely the area of "pinch-out." The 

grading into shale of the Sussex sandstone member of the Cody shale 

(Wilson, 1951) in areas to the south suggests the possibility of oil accumulation in favorable places, but more subsurface data are needed 

before the most promising areas can be defined.

The so-called Crow Mountain sandstone member of the Chugwater 

formation (Carlson, 1949) is truncated by the Gypsum Spring formation, or, where that unit is absent, by the Sundance formation in the 

area east of the axis of the Powder River Basin. This truncation 

may have resulted in a trap favorable for the accumulation of oil
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 81

at the wedge edge. Oil is produced from a unit occupying the same 

stratigraphic position as this sandstone at Hamilton dome in the Bighorn Basin; the sandstone is oil stained at the surface at Lodgegrass 

Creek, on the west side of the Powder River Basin in Montana. Furthermore the sandstone is oil saturated in many surface and subsurface 

sections in central Wyoming (Love, Johnson, and others, 1945).

COAL 

GENERAL FEATURES

Coal beds of commercial thickness are present in T. 47 1ST., R. 81 W., 

and Tps. 48 and 49 N., R. 80 W. Coal in T. 47 N., R. 81 W., is present 

both in the upper part of the Fort Union formation and in the Wasatch 

formation; in the other two townships only the Wasatch formation 

is exposed. Coal beds of the Fort Union formation are limited to a 

north-south trending zone about 4 miles long; north and south of 

this zone the coal beds grade into carbonaceous shales. In the same 

township the coal beds of the Wasatch formation also grade southward into carbonaceous shales. The northward gradation into carbonaceous shales is obscured by the terrace and alluvial deposits along 

Crazy Woman Creek. The coal seams in the Wasatch persist northeastward into Tps. 48 and 49 N"., R. 80 W., along Crazy Woman Creek 

to the north edge of the mapped area, where they can be correlated 

with the coals of the Lake De Smet area.

The coals of the Crazy Woman Creek area are usually black, shiny, 

and brittle and, upon exposure to air, slack and break down to small 

angular fragments. Some of the coal is dull and woody in appearance. Partings of carbonaceous shale and coaly shale are common, 

as are petrified stumps and logs. Many of the thicker beds have been 

locally burned to clinker. Because mining of these coals has been 

on a very small scale, and because operations have virtually ceased 

in recent years, no samples have been collected for analysis. Analyses 

of samples collected in the Lake De Smet area by Mapel (personal communication, 1952) indicate that the coal from the Wasatch formation 

is subbituminous. Coal of the Fort Union formation is likewise subbituminous (Wegemann, 1912).

Reserves of coal were computed for two classes: measured and 

indicated, and inferred. Reserves were computed only for beds which 

exceed the 2.5-foot commercial minimum thickness for their grade. 

Size of areas underlain by coal were determined by polar planimeter; 

a weight of 1,700 short tons per acre-foot has been assumed for subbituminous coal. Total reserves of all classes in the Crazy Woman 

Creek area exceed one billion short tons.
82

BI..D 6 

BED 5

BED 4 

BED 3

BED 2

BED A

BED B 

BED C

BEDD

BEDE 

BEDF

BED G 

BED H

Th

 . . _

'

=

 . <==

 . . _

 = -

_. ._

 : 

 

 

 

 

~_ 

 

 

 

 

 

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 . . 

 . . 

 . . 

 . ..

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 . .

 . . _

^z^l/\

ckness, 

feet

20

31

55

60

90

150

. 8

23

10

20

30

13

12 

32

FIGURE 26. Generalized section showing 

average interval between coal beds of T. 47 

N., R 81 W.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 83 

COAL, IN T. 47 N., K. 81 W.

Within the upper 200 feet of the Fort Union formation 8 coal beds 

are present. These are shown in figure 26 and are lettered in descending order from A to H. All except bed F exceed, at least locally, 2.5 

feet in thickness. The combination of heavy cover and burning of 

coal beds at the surface restricted a detailed study of the various 

thicknesses of the coal and nature and number of partings in many 

of the beds. The various thicknesses for all beds is given in plate 11. 

Localities of measured coal sections have been plotted on the geologic 

map (pi. 6). Average interval between coal beds of the Fort Union 

and Wasatch formations is given in figure 26. Beds in the upper 

part of the Fort Union formation dip as much as 14 degrees eastward. 

Total reserves of coal of all classes for the Fort Union formation 

aggregate 82.4 million short tons. Table 3 shows various classes 

of reserves for all beds except the F bed.

Five coal beds have been mapped in the Wasatch formation of this 

township. They are numbered in ascending order from 2 to 6 (fig. 

26); all of these, except coal bed 6, locally exceed the 2.5-foot commercial minimum thickness. A 90-foot zone of carbonaceous shale and 

thin coal beds is present above the basal red and green claystone of 

the Wasatch formation and below coal bed 2. The carbonaceous shale 

and coal zone grades into shales and siltstones both north and south 

from the NE*4 of sec. 28, where it is best developed; the zone of 

maximum development of carbonaceous shales and thin coals is only 

about a mile long. It is possible that a part of the zone is equivalent 

to coal bed 1 of the north-easternmost township of the mapped area. 

South of sees. 28 and 27, coal beds numbered 2 through 6 thin and 

grade into siltstone and shale. Plate 11 shows the various thicknesses 

of the coal beds and nature and thickness of partings. Reserves of 

all classes of Wasatch coals are given in table 3.

COAL, IN T. 48 N., R. 80 W.

Coal beds numbered 3 to 6 crop out along both sides of Crazy Woman 

Creek; the outcrops are generally restricted to areas close to the creek. 

Coal bed 6 probably extends into the adjoining township on the west, 

but does not crop out; older coal beds do not crop out any farther 

west than the east half of sec. 30. Within this township coal bed 6 

attains a maximum aggregate thickness of 3 feet 5 inches; reserves 

have been computed for that part of the bed that exceeds 2.5 feet. 

Coal bed 5 attains a maximum aggregate thickness of 8 feet 4 inches 

at locality 5-17 and minimum aggregate thickness of 4 feet 7 inches at 

locality 5-16. Coal bed 4, because of its lower position in the section, 

is more limited in outcrop than younger beds; south of sec. 10 the 

bed is below stream level. The bed ranges in aggregate thickness
TABLE 3. Coal reserves in T. 47 N., R. 81 

[In millions of short tons]

Bed

5... ....... ....... ......... .... ... . .

5.... ... .............................. .....

5.....................

5....... ................. .. ..

4... ....

3....... .................................. .....

3.................... .. .

3 .- .. .............. . .. ....

2....... _ .. .

2...... __ ...... ....

A. ......................

A.......................

B. .............................. ....... . .....

B. ............. ....

C. ..................... .. ..

C.. ..................... .. ....... .. .

D.._ ... .. ...

E_. ....... ........ .

Q-. ................

EL.- ........................................

Acres

184 

304 

4.745 

525 

4,818 

280 

2,265 

1,560 

262 

371 

345 

493 

238 

1,932 

260 

2,993 

1,527 

2,764 

264 

634

"Weighted 

average 

thickness 

(feet)

3.3

7.2 

5.2 

4.8 

3.6 

5.1 

4.5 

4.0 

3.1 

4.3 

2.7 

3.2 

4.0 

3.5 

10.4 

6.0 

2.6 

5.4 

4.9 

3.3

Overburden 

(feet)

0-150 

0-150 

0-150 

0-150 

0-200 

0-250 

0-250 

0-250 

0-250 

0-250 

(MOO 

0-400 

0-400 

0-400 

0-400 

0-400 

0-400 

0-500 

0-500 

0-500

Measured and Indicated rese

Beds have thickness of 

2}i-5 

(feet)

1.1

21.7

18.0

1.4 

2.8 

.6 

.9 

1.7 

3.4

6.9

2.3 

3.7

5-10 

(feet)

3.9 

44.0

2.5

31.8

26.3

More 

than 10 

(feet)

4.8
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 85

from 4 feet 7 inches to 5 feet 2 inches. Reserves for all coals and 

for all classes are given in table 4 and measured sections on plate 12. 

Average interval between coal beds in T. 48 N. and T. 49 K, R. 80 W., 

is given in figure 27.

COAL. IN T. 49 N., R. 80 W.

Two more coal beds crop out in this township than in T. 48 N., 

R. 80 W. These beds are numbered 1 and 2, in ascending order. 

Coal beds numbered 2 through 6 correlate with beds of the same 

numbers in T. 47 K, R. 81 W. Coal bed 1 crops out in 3 localities, 

but exposures are so poor elsewhere that the bed cannot be mapped. 

It ranges in aggregate thickness from 2 feet 10 inches at locality 1-1 

to 7 feet 4 inches at locality 1-3. Coal bed 3 has an average aggregate 

thickness of about 3 feet, but at localities 3-1, 3-2, 3-3, and 3-5 it is 

less than 2.5 feet. Coal bed 4 ranges in thickness from 2 feet 4 inches 

at locality 4^-8 to 5 feet 8 inches at locality 4-7. Coal bed 5 ranges 

in thickness from 3 feet 6 inches to as much as 7 feet 2 inches. Coal 

bed 6 is of commercial thickness at only 5 of the numbered localities 

(pi. 6). Reserves for all coals and for all classes are given in table 5 

and measured sections on plate 13.

T.49N.,R.80W.

Thickness, 

BED 6 ^ ^ feet

__ 13 

BED 5

BED 4

BED 3

BED 2

T.48N., R.80W. 

ThickBED I

BED 6

BED 5

23

49

63

BED 4

BED 3 

BED 2

FIGURE 27. Generalized sections showing average interval between coal beds in the Wasatch formation in Tps. 48 and 49 N., 

R. 80 W.
TABLE 4. Coal reserves in T. 48 N., R. 80 

[In millions of short tons]

Bed

6.-..--'.-......................................

5.---.-....,..... .... ..... ..... ....... . ..

5..-. -...-__...__.-..-___._._-_..-________ ...

5.... ..... ... . .

5 -

5..................... ...... .... .....

5.-.---..,---......... ........................

^...... ..........................................

4... ............. .... .. . ... .

4.--..-.-.--...-. ..... ........... ....... ..

3------------.. --.---..-__.__-.--..-.__._._..-__

Acres

38560 

35, 394 

1,053 

10, 116 

981 

2, 638 

1,960 

99 

1, 450 

9,592 

6,790

Weighted 

average 

thickness 

(feet)

2.7 

6.2 

4.7 

6.2 

4.7 

6.2 

4.7 

3.4 

5.1 

4.3 

4.0

Overburden 

(feet)

0-150 

0-150 

0-150 

0-150 

0-150 

0-150 

0-150 

0-200 

0-200 

0-200 

0-300

Measured and indicated reser

Beds have thickness of 

2^-5 

(feet)

29.5

1.9

8.1

.6

7.1

5-10 

(feet)

62.6

111.0

13.1

More 

than 10 

(feet)
TABLE 5. Coal reserves in T. 49 N., R. 80 

[In millions of short tons]

Bed

6.....-........-.--........-.-....... .........

5

5-..-.-..-.-.-....... ...... .-..--. ..-....-

5_ ......... . .. ._ . . _ ... .._.. ...

5................... ---.---.. ..-..--.-.-.-.-.-.

4..._._....--.. .._.-_-.-..._...-. .-._.._..

4. ................. ... ..... ............... ..

4. . . .

4. . ......... .... ..... . _.... ... .

4.

4.. ....... - .-.-.._.-_.._._..._-._....... _..

4......... ......... ........ . . ........... ..

4................................................

4_ . ......... . .. ..... ........... ... .

3-......-..-.-...... -.-.-.-.....--......-. ...

3...............................................

3... --..- - ...-_...--.-_ -. .-..-

3... _-__.__-_....... ............................

3.........-.-.-........-.-..-....-.-. ....-....

2-.----....-.-........-....... ....-.-.-...-.....

2..... .._._.__._._...._.__.__.__....___..__-_..__

2.... .............. .. .... . ........... ..

2._... -.-----...-.....-_._.._....-.-..__.-_......

2..... -.-.-._..--_._-_._..-......._.-...._

2... ..-._..--...._.. ......... ...._.-.-...... ..

2...............................................

1... ..------_.--._ ...... . ....... ...

I...... -._.---.--...._._.-.-...._.-_---..._-....

1.. .. . ...... .-. ..... -......--.-

I-...--.-..... ... . ... ..... --------... ... .

1.. ---_-._.-.-.--......-...--....-_--......_.....

Acres

656 

214 

342 

731 

11,188 

801 

2,398 

1,049 

1,387 

251 

2,470 

1,445 

3,005 

2,928 

289 

6,986 

6,091 

285 

5,238 

478 

992 

2,104 

2,881 

2,984 

1,129 

10, 126 

124 

80 

920 

1,963 

2,027

Weighted 

average 

thickness 

(feet)

2.8 

3.8 

6.7 

5.5 

4.8 

3.8 

4.3 

4.5 

3.1 

3.0 

4.9 

3.9 

2.8 

3.5 

2.6 

3.1 

3.2 

3.0 

2.7 

2.9 

3.7 

3.5 

3.7 

3.5 

3.0 

3.3 

2.7 

7.0 

2.7 

3.2 

7.0

Overburden 

(feet;

0-150 

0-100 

0-100 

0-100 

0-150 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-200 

0-250 

0-250 

0-250 

0-250 

0-250

Measured, and indicated res

Beds have thickness of 

2lA-5 

(feet)

3.2 

1.4

74.8 

5.4 

18.2 

8.3 

7.6 

1.3 

21.4 

9.9 

14.9

1.3 

38.2 

34.5 

1.5

2.4 

6.5 

13.0 

18.8 

18.5 

6.0

.6

4.3 

11.1

5-10 

(feet)

4.1 

7.1

1.0

25.1

More 

than 10 

(feet)
88 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Coal beds numbered 5 and 6 seem to correlate with the Healy bed 

of the Lake De Smet area to the north, but, owing to the increasing 

interval between the beds south of the northern edge of the mapped 

area, it was more practical to map the beds separately. Coal bed 4 

corresponds to the Timar bed of Mapel. Bed 3 correlates with Mapel's 

lower Cameron bed. Coal bed 2 correlates with the Dry Creek bed 

of Mapel and bed 1 probably with the Ucross bed of Mapel.

MANGANESE

Manganese is present in two deposits, one in the NW*4 sec- 32 

and the other in the Ny2 sec. 30, T 47 K, R. 83 W. The deposits 

are of two major types. In one type pyrolusite has impregnated the Flathead sandstone; the mineralized masses are lenticular and are apparently parallel to the bedding. In the other 

type the ore has been localized as dense black nodules in the 

brown clay of the White River formation or as stringers in the porous 

weathered pre-Cambrian granites near the contact with the White 

River formation. The largest body of impregnated sandstone is in 

the NW^ sec. 32. Here the lens is from 30 to 50 feet thick and about 

150 feet long. Analyses of representative samples of this ore provided 

by H. G. Fisk, of the Wyoming Natural Resources Research Institute, 

show 8.9 percent MnO2 - The deposit in the NWy^ sec. 32 is in part 

overlain by the White River formation, and the clays just above the 

contact contain limited amounts of the nodular pyrolusite. In sec. 

30 pyrolusite occurs dominantly as nodules in the clay in the White 

River or as stringers in the weathered pre-Cambrian granite, although 

small lenses of the pyrolusite occur in the Flathead sandstone. A 

sample of the nodular pyrolusite in the brown clays retained on a 

10-mesh screen assayed 50.3 percent Mn02 ; the average Mn02 content 

for the entire sample is 33.8 percent. These analyses were also provided by H. G. Fisk.

Owing to the occurrence of pyrolusite nodules in the White River 

formation, it is apparent that the mineralization is post-White River. 

The manner in which the mineral was emplaced is not so apparent; 

the mineralization seems to be related to the contact of the White River 

formation with older units, and the pyrolusite may have been precipitated out from ground water along a permeable contact zone.

ALLANITE

Allanite, a complex silicate of calcium, aluminum, and iron containing a large proportion of rare earths, is found in a small deposit 

in foliated granite along the north line of sec. 6, T. 46 N., R. 83 W. The 

assemblage of associated minerals, calcite, diopside, garnet, soda, amphibole, epidote, and oligoclase suggests a contact metamorphic origin.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 89

The igneous body which may have given rise to this mineral suite 

was not observed although the granite terrane of the Horn includes 

many small pegmatite bodies. The epidote is banded parallel to the 

country rock; the allanite occurs as irregular masses feathering into 

the epidote and wall rock.

The mineralized body is concordant with foliation in the granitic 

country rock, which strikes about N. 70° W., and dips about 65 degrees 

northeast. The determination of the exact size of the deposit would 

require inclined core drilling, for cover is heavy. Studies with a 

geiger counter indicate that the lens-shaped body containing allanite 

is about 100 feet long and as much as 7 feet wide. Table 6 presents 

results of a quantitive spectroscopic analysis.

BENTONITE

Bentonite beds, ranging in thickness from a few inches to as much 

as 6 feet, were observed in both the Frontier formation and the Mowry 

shale (see sections p. 99-103) ; thin beds were also observed in other 

Cretaceous formations. The minimum dip of bentonite beds at the 

surface is 15 degrees eastward.

CONSTRUCTION MATERIALS

Gravels capping terraces range in thickness from more than 20 feet 

close to the mountain front to less than 5 feet in the eastern part 

of the mapped area. The pebbles and cobbles of these deposits are 

derived mainly from pre-Cambrian igneous and metamorphic rocks 

of the Bighorn Mountains, with minor amounts of limestone and 

dolomite. The pebbles, cobbles, and boulders are well rounded; the 

boulders reach a maximum diameter of about 5 feet. The matrix 

ranges in size from clay through grit. The terrace gravels are used 

extensively in the construction of unpaved roads throughout the 

mapped area. Where streams flow through conglomeratic formations, such as the Kingsbury conglomerate member of the Wasatch 

formation, stream beds contain much gravel and sand.
90 CONTRIBUTIONS TO ECONOMIC GEOLOGY

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GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 91

STRATIGRAPHIC SECTIONS OF MESOZOIC AND 

PALEOZOIC ROCKS

Upper Cretaceous: Feet 

Lance formation: Measured in sec. 29, T. 49 N., R. 82 W.

12. Sandstone and shale, interbedded; sandstone is very light 

gray and pale grayish yellow, fine grained, friable, thin- to 

thick-bedded, crossbedded; shale is dark gray and dark 

olive gray; a few thin beds of dark-yellowish-brown carbonaceous shale. In the upper two-thirds of the unit are 

several massive bedded sandstone lenses as much as 20 ft 

thick, which grade into thin-bedded sandstone and shale 

within 100 yd_________________. __________ 1,330 

11. Sandstone, very light gray (weathering to grayish yellow), 

medium- to fine-grained, friable, thick-bedded, crossbedded, cavernous; unit is lenticular, forms a cliff.____ 70 

10. Sandstone, very light gray (weathering to grayish-yellow), 

medium- to fine-grained, medium- to thick-bedded, crossbedded ; contains a few thin beds and partings of dark-gray 

shale and dark-brown carbonaceous shale and scattered 

calcareous sandstone concretions weathering moderate yellowish brown________ __________________ 285

9. Shale, moderate-brown, silty, carbonaceous; contains thin 

lenses of light-gray fine-grained sandstone. Top of unit 

channeled by overlying unit __ 8

S. Sandstone, very light gray, very fine to fine-grained, thin- to 

medium-bedded; a few thin partings of moderate-brown 

carbonaceous shale and scattered yellowish-brown sandstone concretions that are about 1 to 3 in. across______ 62

7. Concealed_______________________________ 46

6. Sandstone, very light gray (weathering to yellowish gray), 

fine-grained, thinly and evenly bedded, locally crossbedded; 

contains beds of platy calcareous sandstone concretions at 

intervals of 3 to 6 ft apart and a few partings of dark-gray 

shale__________ _ :__ _ 

.;. 5. Concealed _________ _

4. Sandstone, yellowish-gray to very light gray, fine-grained,

 i friable, thin-bedded, crossbedded; a few beds are calcareous 

and slabby; contains laminae of dark-gray shale and particles of carbonized wood _ _ _ 25 

: 13.! Concealed _________ ^ _^_ 31

2. Sandstone, very light gray, very fine grained, thin-bedded;

contains many thin partings of dark-gray shale________ 20

.1. Mostly concealed. Appears.to be mainly interbedded darkgreenish-guay shale and light-gray fine-grained sandstone_ 42

:. ii: i Total Lance formation___________ _._______ 1,970 

Contact between the Lance formation and the Bearpaw shale. The 

beds above this horizon are predominantly sandstone; the beds 

below are predominantly shale.

339462 55-
92 ,,'.. :

Upper Cretaceous -Continued Feet 

Bearpaw shale : Measured in, sec. 13, T. 49 N., R. 83 W.

3. Bentonite, grayish-yellow________________________ 0. 5 

; 2. Shale, dark-greenish-gray, silty, becoming more silty and i ; 

slightly sandy near the top. Top 2 to 3 ft is very fine > 

grained sandstone that contains many partings of darkgreenish-gray shale and forms a weak ledge_________ 15 

USGS Mesozoic locality 22831; from sandstone at top of 

unit:

Niwula sp.

Nuculaiia cf. N. corsicana Stephenson 

Pteria (Oxytonta) nebrascana (Evans and Shumard) 

Ostrea sp.

BaGulites compressus Say

Acanthoscaphites nodosus (Owen) var. quadrang- 

 ' laris (Meek and Hayden)

nodusus (Owen) var. brevis (Meek) 

1. Shale, dark-greenish-gray; laminae of light-gray siltstone

near the top. Unit is partly covered___ __._____ 183

Total Bearpaw shale_____________________ 198 

Contact between the Bearpaw shale and the Parkmau sandstone.

The beds below this horizon are predominantly sandstone. 

Parkman sandstone: Measured in sec. 13, T. 49 N., R. 83 W.

7. Sandstone, white, fine-grained, poorly cemented, crossbedded___ _:______;_____________________ 8

6. Shale, pale-brown and moderate-brown, carbonaceous, silty_ 25 

5. Sandstone, very light gray, fine- to medium-grained, many 

black, pink, and green grains, friable, medium-bedded, 

crossbedded; contains a few moderate-brown siltstone concretions and a few laminae of moderate-brown carbonaceous shale _ ____________________ _ 130

4. Shale and sandstone, interbedded; shale is dark greenish 

gray, silty, slightly carbonaceous; sandstone is very light 

gray, very fine grained ; unit is thin bedded_________ 45 

3. Sandstone and shale, interbedded; sandstone is very light 

gray, very fine to fine grained, locally calcareous and 

slabby, in beds as thick as 2 ft, crossbedded; shale is dark 

greenish gray, sandy, slightly carbonaceous____ __ 85 

2. Sandstone, very light gray (weathering to grayish yellow), 

fine- to medium-grained, calcareous, alternating thick, medium, and thin beds, crossbedded; contains moderate-brown 

calcareous sandstone concretions as much as 4 ft long. 215 

ft above the base is a lenticular bed 2 ft thick of moderatebrown carbonaceous siltstone. Forms rounded ridges and 

knolls _________________________________ 283 

USGS Mesozoic locality 22826; 30 ft above base of unit: 

Pinna sp. 

Inoceramus sp. 

Ethmocardium whitei Ball 

Gyrodes sp. 

Baciilites sp.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 93

Upper Cretaceous Continued

Parkman sandstone Continued Feet 

1. Sandstone and shale, interbedded, becoming more slialy near 

the base; sandstone is very light gray, fine grained, thin 

bedded, locally calcareous and slabby, crossbedded, contains 

a few moderate-brown sandstone concretions; shale is dark 

gray, locally slightly carbonaceous _ _ _______ 145

Total Parkman sandstone________ ________ 721 

Contact between the Parkman sandstone and the Cody shale. The 

beds above this horizon are transitional between clay shale and 

sandstone. The contact is placed at the base of the lowest bed of 

sandstone. 

Cody shale :i Measured in. sees. 13 and 14, T. 49 N., R. S3 W.

42. Clay shale, grayish-black; contains several beds of darkgray septarian limestone concretions______________ 293 

USGS Mesozoic locality 22833; concretions 98 ft below top 

of unit:

Inooeramus cf. /. l)aral>ini Morton 

Buculites aff. B. liaresi Reeside

41. Shale, dark-gray; interlamiuated light-gray siltstone and 

very light gray fine-grained sandstone near the base; bed 

1 ft thick of grayish-green bentonite 78 ft from base; unit 

partly covered_______________ _-______ 513 

40. Shale, dark-gray to grayish-black; a few laminae and thin 

beds of light-gray fine-grained sandstone; at top of unit a 

bed about 3 in. thick of fine-grained sandstone that contains 

highly polished pebbles as much as 1 in. long of black, green, 

and gray chert; unit contains 4 or 5 beds of ellipsoidal darkgray silty limestone concretions as much as 1 ft long, which 

weather dark reddish brown___________'. ___________ 65

USGS Mesozoic locality 22832 and 22824 ; from concretions : 

Niiculana sp.

Geltena cf. G. tjracilis (Meek and Hayden) 

Inocenvmus barabini Morton 

Bac/ulites haresi Reeside 

39. Bentonite, pale-greenish-gray 1_^________________ 1

38. Shale and sandstone, interbedded; shale is dark gray; sandstone is light gray, fine grained; unit contains 2 beds of ellipsoidal dark-gray silty limestone concretions that weather 

dark reddish brown ^._L: _ 12 

37. Shale, dark-gray, sandy_______________________ 42

Total "upper shale member" of Cody shale (beds 42-37)- 927 

36. Sandstone and shale, interbedded; sandstone is very light gray, 

weathering yellowish gray, fine to medium grained, a few 

grains of glauconite, slightly calcareous, very thin bedded, 

more sandstone near base of unit; shale is dark gray, sandy ; 

unit contains several beds of moderate-yellowish-brown
94 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Upper Cretaceous Continued 

Cody shale Continued

36. Sandstone and shale, interbedded Continued Feet 

calcareous sandstone concretions._ ___ _ 76 

USGS Mesozoic locality 22803; concretions in top 10 ft of 

unit:

Perissonota sp.

Pecten (Syncyclonema) halli Gabb 

: Baculites haresi Reeside

aqiiilaensis Reeside 

Placenticeras platmm Hyatt

35. Sandstone, pale-olive, very fine grained, abundant glauconite 

locally, many thin partings of dark-gray shale, slightly calcareous; top 15 ft is fine- to medium-grained sandstone that 

contains sparse glauconite; beds of widely spaced moderateyellowish-brown calcareous sandstone concretions about 25 

and 75 ft above base of unit; contact with the underlying 

unit is gradational________ __ _ _____ ___ 139 

USGS Mesozoic locality 22823; sandstone concretions 75 ft 

above base of unit:

Pteria linffiiaeformis (Evans and Shuniard) 

.1 Anomia n. sp.

Luciwi aff. L. subundata Hall and Meek 

Volutodcrma? sp. 

Raculites haresi Reeside

Total Shannon sandstone member of Cody shale 

(beds 36 and 35). (In part equivalent to Eagle 

sandstone) ______ ---.__- ---- -.__.,_____ 215

34. Siltstone and shale, interlaminated; siltstoue is very light 

gray; shale is dark gray; several beds of ellipsoidal rustyweathering ironstone concretions that are as much as 6 in. 

long_______j.__;_g______; _______________:.________ 126

USGS Mesozoic locality; 23148; float about 75 ft below top 

of unit:

Pecten (Syncyclonema) hallii Gabb ; 

Turitella n. sp. 

Eutrephoceras alcesense Reeside . .;- ; 

Baculites haresi Reeside , . 

Seaphites hippocrepis (DeK.ay) 

Placenticeras sp.

33. Shale and siltstone, interbedded and iuterlaminated; shale is 

dark gray to grayish black; siltstone is light yellowish gray ; 

crushed fossil fragments in the shale in upper half of unit_ 57 

32. Clay shale, dark-gray to grayish-black; a few very thin 

stringers of light:yellowish-gray siltstone; contains 3 or 4 

beds of ellipsoidal rusty-weathering ironstone concretions; 

at top of un|jt,is a bed of dark-yellowish-brown calcareous 

siltstone concretions that weather moderate brown_____ 28 

31. Bentonite, grayish-yellow; contains small moderate-yellow

cone-in-cone chips_________________________ 1
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 95

Upper Cretaceous Continued

Cody shale Continued Feet 

30. Shale, dark-gray to grayish-black; top half of unit contains 

many laminae of light-gray siltstone; 2 ft below top of unit 

is a bed of closely spaced dark-gray calcareous siltstone 

concretions as much as 2 ft long and 1 ft thick; 5 ft below 

top of unit is a bed of dark-gray white-weathering septerian limestone concretions_ _____ _______ 39 

29. Shale, dark-gray, silty; about 15 ft, 25 ft, and 35 ft above the 

base of the unit are beds of dark-gray white-weathering 

limestone concretions from 6 to 18 in. across; at base of 

unit is a bed of closely spaced light-gray calcareous siltstone concretions about 6 in. thick and 2 ft long. A 1-ft 

grayish bentonite bed is present at top____________ 52 

USGS Mesozoic locality 22830; concretions 35 ft above base 

of unit: 

Oslrea sp. 

Cyprimeria sp. 

Xylopliagella, sp. 

Oliyoptycha? n. sp. 

Baculites aquilaensis Reeside 

Scaphites hippocrepis (DeKay)

cf. 8. aquilaensis Reeside

USGS Mesozoic locality 22828; concretions 25 ft above base 

of unit:

Scaphites hippocrepis (DeKay) 

Placenticeras meelci Boehm 

Baculites aquilaesis var. separatus Reeside 

USGS Mesozois locality 22829; concretions 15 ft above base 

of unit: 

Inoceramus sp.

Pteria cf. B. linffuaeformis (Evans and Shumard) 

Anoinia sp. 

Baculites haresi Reeside

aquilaensis var. obestts Reeside

28. Shale, dark-gray, silty __ _____ ___ 48 

27. Bentonite, yellowish-gray; contains dark-greenish-gray concretions about 12 in. across at widely spaced intervals__ 1 

26. Shale and sandstone, interlaminated; shale is dark gray; sandstone is very light gray, fine grained; several beds of darkgray septarian limestone concretions 1 to 6 in. across, which 

weather yellowish gray and contain fucoidal markings on 

their exterior surface; 5 ft below the top of the unit is a 

prominent bed of moderate-brown calcareous siltstone concretions which are as much as 10 ft in diameter________ 30 

USGS Mesozoic locality 22821; from limestone concretions: 

Baculites aquilaensis Reeside

haresi Reeside

Scaphites hippocrepis (DeKay) 

USGS Mesozoic locality 22834; float from this unit:

Fasciolaria aff. F. cheyennensis (Meek and Hayden)
96 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Upper Cretaceous ^Continued

 Cody shale Continued Feet 

25. Shale and sandstone, interlaminated; shale is dark gray ; sandstone is very light gray, fine grained; a bed of dark-gray 

septarian limestone concretions weathering light brown, 

about 30 ft above base________________________ 123 

24. Bentonite, yellowish-gray, 1 ft thick; underlain by a bed 6 in.

thick of calcareous sandstone that forms a weak ledge___ 1% 

23. Sandstone and shale, interbedded and interlaminated ; shale is 

dark gray; sandstone is very light gray, fine grained, occurs 

locally in lenses as much as 1% ft thick, which contain 

tabular dark-gray limestone concretions weathering light 

brown _ _ _ 565 

USGS Mesozoic locality 22822; from tabular limestone 

concretions 242 ft below top of unit: 

Nucula sp. 

Nuculana n. sp. 

Breviarca n. sp. 

Inoceramus sp. 

Ostrea sp.

Geltena cf. G. yracilis (Meek and Hayden) 

Lucina aff. L. subundata (Hall and Meek) 

"Cor~bula" n. sp.

Dentalium paupercuhim (Meek and Hayden) 

Polinices sp. 

Actaeonf sp. 

Cylichna sp.

Scaphites aquilaensis Reeside 

aquilaensis var. nanus Reeside 

aquilaensis var. costatus Reeside 

levis Reeside 

Jiippocrepis (DeKay) 

hippocrepis var. crassus Reeside 

Haresiceras placentiforme Reeside

placentiforme var. parvum Reeside 

Baoulites aquilaensis Reeside

aquilaensis var. separatus Reeside 

aquilaensis var. obesus Reeside 

haresi Reeside 

asper Morton?

22. Shale, grayish-black, noncalcareous. Unit is poorly exposed_ 40 

21. Shale, dark-gray to grayish-black (weathering to light gray to

brown), very calcareous. Unit is partly covered__ __ 300 

20. Shale, dark-gray to grayish-black, alternately calcareous and 

: noncalcareous. Unit is poorly exposed-.__________ 190 

19. Shale, dark-gray, very calcareous ; a few stringers of bentonite 

less than 1 in. thick; contains a few poorly preserved Inoceramus and Ostrea congesta. Unit is partly covered___ 182 

18. Bentonite, very light gray__ _ ____________ 1 

17. Shale, grayish-black, noncalcareous. Unit is partly covered_ 73 

16. Shale, dark-gray, noncalcareous; a bed of medium-gray septarian limestone concretions at top of unit__________ 40
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 97

Upper Cretaceous Continued

Cody shale Continued feet 

15. Mostly concealed. Appears to be mainly dark-gray shale; 

at top of unit is a prominent bed of dark-yellowish-orange 

septarian silty limestone concretions as much as 10 ft in 

diameter; beds of similar concretions crop out less prominently near the middle and at base of unit 160 

USGS Mesozoic localities 23151 and 22827; concretions at 

top of unit: 

Serpula sp.

Inoceramus de form-is Meek 

aff. /. erccttis Meek 

n. sp.

Ph,oladomya papyracea Meek and Hayden 

Cardium sp. 

"Tellina" sp. 

Parmicorbula n. sp. 

Creonellaf n. sp.

Polinices cf. P. concinna (Hall and Meek) 

Gyrodes conradi Meek 

aff. G. depressa Meek 

Xenophora simpsoni Stanton 

Turitella, icMtei Stanton 

Hercorhynchus n. sp. 

Bellifusust n. sp. 

Anchura? sp.

Aetaeon? n. sp. aff. A. propinquus Stanton 

Baculites mariasensis Cobban 

ScapMtes preventricosus Cobban

USGS Mesozoic locality 23152; concretions at base of unit: 

Inoceramus n. sp. 

Anchuraf n. sp.

' 14. Mostly concealed. Appears to be mainly dark-gray silt shale; 

several beds of dark-gray septarian concretions (weathering 

to light gray) with veins of dark-orange calcite_ ___ 92 

USGS Mesozoic locality 22816; concretions 58 ft from base

of unit: 

.' Inoceramus n. sp.

Baculites cf. B. "besairiei Collignon 

Prionocyclu.3 n. sp. 

Scaphites corvensis Cobban

USGS Mesozoic locality 22817; concretions in this unit at 

Dry Muddy Creek, NE^4 sec. 1, T. 48 N., B. 83 W. 

Inoceramus n. sp. 

Oyrodes depressa Meek :. 

Aporrhais sp. 

Eutrephoceras n. sp. 

ScapMtes corvensis Cobban 

Baculites cf. B. besairiei Collignon 

Prionocyclus n. sp.

Proplacenticeras pseudoplacenta (Hyatt)

13. Silt shale, dark-gray (weathering to dusky yellowish brown), 

noncalcareous; several beds of dark-gray ironstone concretions, weathering to rusty__________ ____.___ 20
98 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Upper Cretaceous Continued

Cody shale Continued Feet 

12. Shale and sandstone, interbedded and interlaminated; shale 

is dark gray, noncalcareous; sandstone is white to light 

gray, fine grained, in lenticular beds as much as 1 in. thick; 

locally plate-shaped dark-gray limestone concretions occur 

in the sandstone beds; contact with the underlying unit is 

very sharp_________ __________ _________ 44

USGS Mesozoic locality 2281.3 ; concretionary sandstone lens 

27 ft above base of unit: 

Inoceramus dimidius White

perplexus Whitfield 

Polinices sp.

ScapJiites whitfieldi Cobban 

Prionocyclus wyomingensis Meek

11. Sandstone, light- to dark-gray (weathering to light gray), 

fine- to medium-grained, friable, calcareous; bottom part 

of unit contains many thin partings of dark-gray shale; 9 ft 

above base of unit is a bed of medium-gray sandy limestone 

concretions that weather light gray_ _ _____ 41 

USGS Mesozoic locality 22819; concretions 9 ft above base 

of unit: 

Serpula sp.

Inoceramus labiatus (Schlotheim) 

Ostrea sp. 

Cerithium n. sp. 

Mammites aff. M. nodosoides (Schlotheim) var. spinosa

Basse

Watinoceras cf. W. coloradoense (Henderson) 

Puzosia aff. P. planulate (Sowerby)

10. Shale and sandstone, interlaminated, bentonitic in bottom 3 

ft; shale is dark gray ; sandstone is light gray, fine grained; 

slightly calcareous______^___________________ 20 

9. Bentonite _______________________________ 2 

8. Shale, dark-gray (weathering to moderate yellowish brown),

sandy slightly calcareous________ _ _ ____ 11 

7. Shale, dark-gray (weathering to dark bluish gray), calcareous, fossiliferous______________________ 61 

USGS Mesozoic locality 22811; near base of unit: 

Inoceramus labiatus (Schlotheim) 

Borissjalcoceras sp.

6. Silt shale, dark-gray noncalcareous; scattered dark-gray septarian limestone concretions near top of unit. 

USGS Mesozoic locality 22815; concretions in this unit about 

2 miles south of Dry Muddy Creek SE^NB^SW^ sec. 

12, T. 48 N., R. 83 W_______________________ 22 

Pteria sp.

Inoceramus aff. /. fragilis Hall and Meek 

Scaphites delicatulus Warren 

Sciponoceras gracile (Schumard) 

Allocrioceras pariense (White) 

Borissjalcoceras cf. B. reesidei Morrow
GEOLOGY OF CRAZY WOMAN CREEK AREA; JOHNSON COUNTY, WYO. 99

Upper Cretaceous Continued

Cody shale Continued Feet 

5. Mostly concealed. Appears to be mainly dark-gray noncal-

.careous shale______________ _ __ 45 

4. Mostly concealed. Appears to be mainly dark-gray shale; unit 

contains several beds of dark-gray septarian limestone concretions with veins of bright-yellow calcite; black chert 

pebbles weathering out from the top of the unit; 1-footthick bed of bentonite at top______ __________ 51 

USGS Mesozoic locality 22808 and 23149; limestone concretions in this unit: 

Pteria n. sp.

Inoceramus cf. /. fragilis Hall and Meek 

Dentalium pauperculum Meek and Hayden 

Anchura? sp. 

Oligoptycha sp. 

Metoicoceras n. sp. 

Dunveganoceras cf. D. conditum Haas

3. Bentonite, grayish-orange_____________________ 1 

2. Mostly concealed. About 5 ft of dark-gray silty shale exposed near middle of unit_________ ______ 27 

1. Sandstone and shale, interbedded and interlaminated; shale 

is dark gray (weathering to grayish brown) ; sandstone 

is light gray to white, fine to medium grained, a few 

slabby calcareous sandstone beds as much as 1 in. thick, 

which contain coarse grains of black chert; a 3-inch-thick 

bed of sandstone at top of unit contains rounded and 

polished black chert granules and pebbles as much as 

iy2 in. long____________________________ 36

Total Cody shale________-____________ 3, 672. 0 

The contact between the Frontier formation and the Cody shale is 

characterized by soft shales and sandstones above and by resistant 

conglomeratic sandstone directly below. 

Frontier formation : Measured in sec. 1, T. 48 N., R. 83 W.

26. Siltstone, tan and light-gray, calcareous, contains wellformed cone-in-cone structure and lenses 6 to 8 in. thick 

of friable coarse-grained light-gray sandstone that contain 

granules and pebbles of black chert as much as threefourths of an inch long; forms weak ledge_________ 2^. 

USGS Mesozoic localities 22809 and 23154: 

Inoceraimis prefragilis Stephenson 

Gyrodes aff. G. conradi Meek 

Metoicoceras n. sp.

cf. M. praecox Haas

Mantelliceras cf. M. canitaurirmm Haas

25. Sandstone, light-gray to white, fine-grained, occurs in beds 

less than one-half inch thick, which are separated by 

partings and very thin beds of dark-gray shale; a few 

thin beds of siltstone with incipient cone-in-cone structure; weathers to yellowish-gray slopes.- ______ 33
100 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Upper Cretaceous Continued

Frontier formation Continued Feet

24. Shale with interlarninated sandstone; shale is dark gray; 

 sandstone is light gray, fine grained, and occurs in lenticular beds as much as 1% in. thick; beds of dark-gray 

septarian limestone concretions with septa of brightyellow calcite occur 3 ft and 12 ft above base of unit; 

widely spaced dark-gray septarian silty limestone concre1 . tions that weather moderate brown occur 20 ft above

base of unit____________:___________ _ 65 

USGS Mesozoic locality 22801; bed of sandstone 43 ft 

above base of unit:

Acanthoceras? n. sp.

USGS Mesozoic locality 22807; concretions 12 ft above 

base of unit:

Acantlioceras? n. sp.

23. Bentonite, pale-olive-green_ _ ______ 4 

22. Sandstone and shale, interbedded and interlaminated; shale

is dark gray ; sandstone is light gray, fine grained____ 15 

21. Shale, dark-gray; contains a few laminae of light-gray finegrained sandstone________________________ 6 

20. Sandstone and shale, interbedded and interlaminated; 

sandstone is light gray, fine grained; shale is dark gray; 

a bed of widely spaced dark-gray brown-weathering septariate limestone concretions as much as 10 ft in diameter 

at top of unit______________ _____________ 39 

USGS Mesozoic locality 22804; concretions at top of unit: 

Nuculana sp. :; 

Inoceramus prefragilis Stephenson 

Ostrea sp.

 Psilomya n. sp. aff. P. concentrica (Stanton) 

Corbwlam.ella n. sp.

Dentalium paupercuUim Meek and Hayden 

Polinices aff. P. concinno, (Hall and Meek) 

Gyrodes aff. G-. conradi Meek 

Borissjakoceras reesidei Morrow

n. sp.

Acanthoceras? ampliibolum Morrow

USGS Mesozoic locality 22806; 14 ft above base of unit: 

Ostrea, sp.

Acanthoceras? amphibolum Morrow

19. Shale and sandstone, interbedded and interlaminated; shale 

is dark gray; sandstone is very light gray, fine to medium 

grained, crossbedded, occurs mostly in beds less than 4 in. 

thick, a few lenticular beds as much as 8 in. thick; 

a bed of bentonite 6 in. thick 40 ft above base of unit___ 43 

18. Sandstone, yellowish-gray (weathers to dark yellowish 

orange) ; contains sparse black chert granules and pebbles 

as much as one-fourth inch long in:,_ a medium-grained 

matrix, many red and green grains, crossbedded, calcareous; 

forms a ledge_.-_ _____ _______________ ]
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 101

Upper Cretaceous Continued

Frontier formation Continued Feet 

17. Shale and sandstone, interbedded and interlaniinated, predominantly sandstone in upper part and predominantly 

shale in lower part; shale is dark gray; sandstone is very 

light gray, fine to medium grained, crossbedded in beds and 

lenses as much as 4 in. thick 16 

USGS Mesozoic locality. 22805; 2 ft above base of unit:

Acanthoceras? amphibolum Morrow

16. Sandstone, very'light gray (weathering to grayish orange), 

fine-grained, friable, noncalcareous; contains a few laminae 

of dark-gray shale_______ _ 2 

15. Silt shale and sandstone, interlaniinated; shale is dark gray;

sandstone is light gray, fine grained_ _ _ 15 

14. Silt shale and siltstone, interlaniinated, dark gray; 6-inchthick lens of fine-grained light-gray sandstone in top 1 ft 

of unit___ ___ _______________________ 15

13. Sandstone and shale, interbedded and interlaniinated; shale 

is dark gray to grayish black; sandstone is light gray to 

white, weathering light gray and light brown, very fine 

grained to silty, crossbedded, in lenticular beds that are 

mostly less than 1 in. thick; near top of unit are two or 

three lenticular beds of sandstone as much as 1 ft thick___ 142 

12. Shale, dark-gray (weathering to dark yellowish brown),

slightly silty ____ __. 11

11 Shale, light-olive-gray, very silty, lower 2 ft bentonitic____ 5 

10. Bentonite, light greenish gray in lower half and light olive 

gray in upper half; near base of unit is a light-brown layer 

3 in. thick, which is present for at least 1 mile in either 

direction along the strike of the beds______________ 5 

9. Shaly siltstone, dark-yellowish-brown; contains dark-gray 

calcareous siltstone concretions that are 2 to 3 ft long and 

about 9 in. thick; at base of unit is a lenticular bed of 

brown-weathering sandstone 1 ft thick____________ 

8. Shale, dark-gray, silty, flaky____________________ 1 

7. Shale and siltstone, light-olive-gray, more silty in upper half 

of unit, bentonitic; contains manganiferous-stained plateshaped limy siltstone concretions__________ ____ 6 

6. Bentonite, pale-olive-gray_____________________ 1 

5. Siltstone, dark-gray to grayish-brown, bentonitic becoming 

more bentonitic toward top of unit, poorly consolidated; a 

few platy dark-gray calcareous siltstone concretions as 

much as 4 ft long_______ ______________ 15

4. Shale, medium-dark-gray, bentonitic_______________ 4

3. Bentonite, light-olive-gray_____________________ 2

2. Shale, dark-gray to grayish-black (weathering to dark yellowish brown), minor silty partings______________ 13 

1. Bentonite, pale-olive-green to gray; 2-foot-thick zone of lightgray bentonitic shale near middle of unit__________ 6

Total Frontier formation___________________ 481.0
102 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Contact between the Frontier formation and the Mowry shale. The base 

of the Frontier formation is placed arbitrarily at the base of a persistent 

bed of bentonite that occurs at approximately the change from dark 

gray-weathering silt shales above to light-gray-weathering siliceous 

shales below.

Lower Cretaceous: Feet 

Mowry shale: Measured in sec. 25, T. 49 N., R. 83 W.

25. Siltstone and claystone, gray, slightly brittle, weathers rusty

brown along joint surfaces____________________ 5Mt 

24. Shale, gray to light-gray, siliceous, laminae and thin beds of

fine-grained sandstone_-_____________ _ __ 27

23. Sandstone, tan to gray, fine-grained (weathering to light

gray), contains laminae of siltstone and dark-gray shale__ 11 

22. Shale, brownish-gray, silty becoming sandy in top 1 ft and

grading into overlying unit___________________.._ 6 

21. Bentonite and bentonitic shale; bentonite is dirty greenish

yellow; shale is grayish brown.________ __ _ _ 3% 

20. Shale, gray, somewhat siliceous___________________ 12 

19. Sandstone, gray (weathering to light gray), medium-grained,

noncalcareous __-_ ____________ _____-- 2 

18. Sandstone and siltstone, gray, thin-bedded; a few laminae of 

gray shale in the lower portion; the unit is capped by a bed 

of 1.3 ft thick of very light gray fine-grained sandstone___ 7 

. 17. Shale, gray, siliceous, a few laminae of fine-grained gray

sandstone _____.________________________ 6 

16. Shale with interlaminated fine-grained sandstone, gray,

weathering brown, soft-____________________ 21

15. Shale, light-gray, siliceous; contains abundant fish scales__ 22^ 

14. Bentonite, tan______________________________ y> 

13. Shale, gray, siliceous__________________________ 5 

12. Bentonite, greenish-yellow_______________________ 3 

11. Scale, light-gray, siliceous, brittle, contains abundant fish

scales _________________________________ 216 

USGS Mesozoic locality 23581; in the SW% sec. 25, T. 46 

N., R. 83 W.:

Inoceramus sp., Metenffonooeras sp.

Ne'ogastropUtes ioyomin,gensis (Reeside and Weymouth)

10. Shale, dark-gray (weathering to medium gray), slightly silty, 

brittle; a bed of bentonite 1.3 ft thick occurs 37 ft above 

base of unit; two beds of bentonite, less than one-half foot 

thick, occur in the basal 32 ft; at top of unit is a zone of 

cone-in-cone concretions that are as much as 4 ft long__ 62 

9. Bentonite, pale-greenish-yellow, silty_______________ 1^ 

8. Shale, grayish-black; brownish-gray calcareous concretions at

base of unit___ _ _ _______ _ _ 8 

7. Shale, grayish-black, plastic._____________________ 10 

6. Shale, grayish-black, a few sandy streaks__-_ _______ 32 

5. Bentonite, moderate-greenish-yellow________________ 1^

4. Shale, grayish-black, bentonitic, soft______________ 1% 

3. Sandstone and shale; sandstone is gray, fine grained; shale

is black_____ __ ____ __ _ _____ li/2
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 103

Lower Cretaceous Continued

Mowry shale Continued Feet 

2. Shale, grayish-black, bentonitic; dark-brown silty concretions 

that contain a few poorly preserved Inoceramus impressions occur about 1 ft from the base of the unit________ 30 

1. Sandstone and shale; sandstone is brownish black, weathering to light brownish gray; shale is brownish black; a bed 

1 ft thick of steel-gray bentonitic shale 2 ft from top of 

unit ______________________..___________ 7

Total Mowry shale________________________ 503.0 

Contact between the Mowry shale and the Newcastle sandstone. The 

Newcastle sandstone forms a broad white outcrop that contrasts 

both in color and lithology with the soft dark shale of the overlying 

Mowry shale. The contact is gradational within about 7 ft. 

Newcastle sandstone: Measured in sec. 25, T. 49 N., R. 83 W.

4. Sandstone, light-gray to light-tan, medium-grained, abundant 

black grains; the middle 6 ft is fine grained and poorly 

consolidated; the top 1 ft forms a weak ledge________ 22 

3. Sandstone, light-tan to light-gray (weathering to rusty 

orange), medium-grained, abundant black and red accessory 

grains; forms a ledge__________-__________________ 5

2. Sandstone, light-gray, medium-grained, abundant black and

yellowish-green accessory grains, poorly cemented__ 4 

1. Sandstone, light-tan to light-gray, fine-grained, very shaly,

poorly cemented - ___ ___________________ 11

Total Newcastle sandstone_________________ 42 

Contact between the Newcastle sandstone and the Skull Creek shale. 

The contact is placed at the base of a zone about 10 ft thick, which 

is gradational between the medium-grained sandstone of the Newcastle and underlying black clay shale. 

Skull Creek shale : Measured in sec. 25, T. 49 N., R. S3 W.

5. Clay shale, grayish-black, flaky, soft______________ 64 

4. Shale, grayish-black ; and interlauiinated light-gray siltstone ;

unit becomes more silty towards base_____________ Ifi 

3. Siltstone, tan to light-gray, calcareous, thin-bedded, contains

a few plant fragments: forms a weak ledge_________ 2.5 

2. Clay shale and silt shale, olive-gray to dark-gray, noncalcareous; a few laminae of light-gray to tan siltstone; two 

beds of siltstone one 8 in. thick 56 ft above base of unit, 

and the other 2 ft thick 40 ft above base of unit locally 

form weak ledges_________________________ 6.1 

1. Concealed. Zones of iron-stained siltstone concretions 5 and

10 ft above base of unit______________________ 22

Total Skull Creek shale_____________________ 164.5 

The contact between the Cloverly formation and the Skull Creek shale 

is characterized by grayish-black shales that form a slope above and 

shales that contain siltstone laminae and that are more resistant 

below.
104 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Lower Cretaceous Continued Feet 

Cloverly formation : Measured in sec. 25, T. 49 N., R. 83 W.

14. Siltstone, brownish-gray, calcareous, thin-bedded, slabby__ 5% 

13. Shale and siltstone interbedded in beds 4 to 6 in. thick; dark 

gray and light gray, weathering from drab tan to brown; 

contains abundant dahllite concretions __________ 23 

12. Shale, dark-gray; top 8 ft is clay shale and remainder is silt 

 i shale.; at 12 and 17 ft above the base are zones of iron-stained

siltstone concretions 6 in. thick_________________ 32 

11. Clay shale, grayish olive.in upper half, dark gray in lower 

half; unit capped by a bed of pebbly ferruginous sandstone 

2 in. thick________________________________ 12 

10. Shale, grayish-black (weathering to drab brown), noncalcareous; at top and near middle of unit are beds 2 ft thick 

of thin-bedded brown calcareous siltstone; a few 4- to 6-in. 

beds of siltstone in upper part of unit__'_____ ____ 31 

9. Sandstone, brownish-black, conglomeratic,75 a few pebbles as

much as one-fourth inch long________u_^____ 

8. Shale, olive-gray (weathering to ochre), plastic________ 6 

7. Shale, brownish-black, silty, carbonaceous___________ 2 

6. Shale, light-yellowish-gray, silty_________________ 5 

5. Sandstone, light-yellowish-gray; medium grained with subrounded grains, well sorted ; unit is lenticular_ _ _ 2 

4. Clay shale, brownish-black, carbonaceous____________ 9 

3. Mostly concealed. Appears to be mainly gray silty sandstone. 17 

2. Sandstone, very light gray, fine-grained, calcareous, clean,

tliin-bedded, crossbedded______________________ 8 

1. Sandstone, light-yellowish-gray (weathering from light yellowish brown to white) ; composed almost entirely of 

medium to coarse grains of quartz, fairly well sorted, crossbedded. This and the overlying unit support a growth of 

cedars and scrubby pines and form a prominent and persistent ridge that can be traced for several miles in either 

direction along the strike of the beds in this vicinity___ 3

Total Cloverly formation___________________ 156. 5 

Contact between the Cloverly formation and the Morrison formation. 

Beds above the contact in the lower part of the Cloverly formation are 

predominately sandstone; beds below the contact are varicolored claystones. 

Jurassic:

Morrison formation : Measured in sees. 35 and 36, T. 49 N., R. 83 W. 

25. Olaystone, grading upwards from brownish black to light gray

in upper 1 ft, soft__________________________ 5. 8 

24. Claystone, gray, silty_____ _____ _ __ 2. 3 

23. Shale and claystone, brownish-black; may be carbonaceous;

beutonitic 2-ft zone 3 ft above base________________ 29. 0 

22. Claystone, grayish red in lower half and pale olive green in 

upper half; a 5-ft bentonitic zone 22 ft above base, grades 

into overlying unit______ __________________ 39. 2 

21. Sandstone, light-yellowish-gray, fine-grained, calcareous;

accessory grains minor; forms a weak ledge___ __ .5
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 105

Jurassic Continued

Morrison formation Continued Feet 

20. Claystone, alternating grayish red and pale olive, soft________ 5.1

19. Sandstone, light-yellowish-gray (weathering to brown), very

fine grained, crossbedded to slabby_________.____ 7. 0 

18. Claystone, dark-greenish-gray, silty, calcareous, soft_____ 3.1 

17. Sandstone, light-yellowish-gray (weathering to brown) ; fine

grained containing sparse red and green minerals _ . 7 

16. Claystone, dark-greenish-gray, silty, calcareous, soft______ 3.1 

15. Sandstone, yellowish-gray, fine-grained, soft, lenticular___- 1. 9 

14. Siltstone, yellowish-gray, sandy, calcareous, soft_ _____ 2.1 

13. Sandstone, yellowish-gray (weathering to brown), very fine

grained thin-bedded to massive, calcareous, lenticular____ . 7 

12. Claystone, dark-greenish-gray to pale-olive, silty in part, 

calcareous, soft; contains a 6-in. argillaceous limestone 

about 10 ft above base. Chara fructifications and ostracodes 

are abundant in the limestone_________________ 27.1 

11. Siltstone and sandstone, dark-greenish-gray (weathering to

yellow gray), very thin bedded, calcareous, soft______ 10. 6 

10. Siltstone, dark-reddish-brown, clayey, calcareous_______ 4. 0 

9. Sandstone, yellowish-gray, very fine grained, silty, calcareous,

thin-bedded, soft___________________-____ 1. S 

8. Claystone, dusky-red, silty, calcareous, soft____________ 5. 6

7. Siltstone, dusky-red (weathering to brick red) ; fractures into

small cuboidal fragments, calcareous_ ____ ____ 3. 0

6. Claystone, dark-greenish-gray, calcareous, soft ______ 1. 2 

5. Sandstone, yellowish-gray, fine-grained, thin-bedded; forms a

ragged ledge, lenticular._ ___ _____ ____ 2. 0

4. Claystone, dark-greenish-gray, silty in middle 1 ft, calcareous 5. 2 

3. Sandstone, yellowish-gray, fine-grained, calcareous, lenticular . 9 

2. Claystone, dusky-yellow-green, silty, calcareous, soft_____ 2.9 

1. Sandstone, yellowish-gray, fine grained, crossbedded, calcareous ; this unit is lenticular and ranges from a featheredge 

to over 6 ft in thickness; channels through underlying Sundance beds_ ___ _ _ _ -. _ 2. 0

Total Morrison formation___________________ 184. 7 

Contact between the Morrison formation and the Sundance formation. 

Beds above the contact are predominantly sandstone ; beds below the 

contact are thin glaucouitic shaly sandstones and marine shales. 

Sundance formation: Measured in sec. 2, T. 48 N., R. 83 W.

24. Sandstone, brown, medium- to fine-grained; resistant to 

weathering. This unit is completely removed a few feet 

along outcrop and replaced by the basal lenticular sandstone 

of the Morrison formation____________________ . S 

23. Sandstone, tan, fine-grained, shaly, soft________'_____ 3. 4 

22. Sandstone, brown to red, fine-grained, calcareous, shaly, soft- 3. 4 

21. Sandstone, weathers brown, medium- to fine-grained, glauconitic, calcareous, 6-in. olive-gray shale 8 ft from top _ 5. 6 

20. Shale, olive-gray, silty, calcareous; 3 ft from top is a 6-in.

ledge of oyster coquina_ ____ _ _______ 47. 3 

19. Sandstone, gray (weathering to tan), fine-grained, slabby, very

calcareous; forms a ledge_____ __ ____ 1.4
106 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Jurassic Continued

Sundance formation Continued Feet 

18. Shale, olive-gray, silty, calcareous, a few thin sandy zones 

throughout. PachyteutMs densus are abundant in lower 

20 ft___________________________________ 113. 8 

17. Oolitic limestone, yellowish-gray (weathering to brown),

sparsely fossiliferous, lenticular ; absent 300 ft north___ 2. 3 

16. Sandstone, yellowish-gray, fine-grained, well-sorted, calcareous ; contains red and green accessory grains; regular to 

crossbedded; forms topmost prominent cliff in lower Sundance formation___________________________ 16. 5 

15. Sandstone, yellowish-tan, fine-grained, calcareous, poorly indurated; contains red and green accessory minerals____ 25.1 

14. Shale, grayish-olive, silty, calcareous, soft __________ 1. 6 

13. Sandstone, tan, very fine grained, silty, calcareous______ 11. 5 

12. Sandstone and shale; tan sandstone is fine grained and silty

and unit appears to grade upward into unit 14________ 2. 4 

11. Shale, grayish-olive, calcareous, soft_______________ 5. 6 

10. Sandstone, light-tan, fine-grained, silty, crossbedded, calcareous___________________________________ 1.3 

9. Shale, grayish-olive, calcareous, soft __ _ _ . 9 

8. Sandstone, light-tan, very fine grained, silty, calcareous, soft- . 9 

7. Shale, grayish-olive, calcareous, with a 6-in. sandstone ledge

3 ft above base__________________________ 13. 8 

6. Sandstone, pale-olive, very fine grained, shaly, calcareous, soft- 5. 5 

5. Sandstone, light-gray to light-tan, fine-grained, well-sized; in 

thin regular beds from 2 to 8 in. thick; very calcareous, 

somewhat friable; minor red accessory minerals______ 12. 0 

4. Sandstone, light-tan, fine-grained, crossbedded, calcareous,

glauconitic? __ _________ _ ________ 5. 0 

3. Shale, greenish-gray, sandy, calcareous, soft-__________ 3. 0 

2. Sandstone, light-tan, very fine grained, shaly, soft ______ 1. 7 

1. Sandstone, light-tan, fine-grained, crossbedded, calcareous; 

rounded chert pebbles as much as 1.5 in. long in the upper 

6 in.; contains Isocrinus sp_____- 2. 6

Total Sundance formation____________________ 287. 4

Contact between the Sundance formation and the Gypsum Spring formation. Beds above the contact are conglornertic sandstones; beds 

below are argillaceous light-colored limestones and reddish-colored 

claystones. . Gypsum Spring formation: Measured in sec. 11, T., 48 N., R. S3 W.

13. Limestone, light-greenish-gray, argillaceous, soft________ 1. 0 

12. Claystone, grading upwards from dark reddish brown to light

greenish yellow in top 6 in.; calcareous, soft.________ 3. 4 

11. Limestone, light-tan to light-gray, argillaceous, irregularly 

bedded in lower half and concretionary in upper half; forms 

a minor ledge______. _ _ _ _ 2. 0 

10. Claystone, dark-reddish-brown with pale-yellowish-green

bands and laminae in lower 5 ft; silty, calcareous______ 15. 6 

0. Siltstone and limestone, interbedded in about 7.3 ratio, moderate reddish brown and light gray, weathers to a rounded 

ochre-colored ledge________ __ __________ 4. 5
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 107

Jurassic Continued

Gypsum Spring formation Continued Feet

8. Limestone, light-gray, argillaceous; contains a parting 4 to 

6 in. thick of pale-green claystone near middle; forms 

a ledge___________________________^__ 3.0

7. Claystone, grading upwards from dark to moderate reddish 

brown mottled ochre to pale greenish yellow in top 8 in.; 

silty, calcareous, soft____________ _____.__ 7.1

6. Limestone, pale-greenish-yellow, argillaceous; forms a minor

ledge________________________________ . 6

5. Claystone, pale-greenish-yellow, calcareous, soft________ 1. 0

4. Claystone, grading upwards from dark to moderate reddish 

brown to grayish red in top 8 ft; silty, slightly calcareous, 

soft __________________________________ 35. 2

3. Limestone breccia, light-brown, porous, contains angular red 

fragments of claystone and a few thin beds of liglitbrown siltstone_______________________ 15.6

2. Siltstone, light-brown, sandy, soft__________________ 12.0

1. Gypsum, white, weathering to gray________________ 5. 0

Total Gypsum Spring formation______________ 106. 0 

The contact between the Chugwater formation and the Gypsum Spring 

formation is characterized by salnion-pink sandstones below and gypsum, limestone breccia, or fine-grained siltstone above. 

Triassic:

Chugwater formation : Measured in sees. 34 and 35, T. 49 N., R. 83 W.

4. Sandstone, light-brown, weathering to salmon-pink, the top

1 ft banded pink and red, very fine grained, calcareous,

crossbedded, massive; contains irregularly shaped lenses

and pods of gypsum that are probably secondary_____ 24. 0

3. Sandstone, light-brown (weathering to salmon pink), very line

grained, silty, slightly calcareous, crossbedded, massive_ 27. 6 

2. Limestone, light-gray, dolomitic, thin-bedded, shibby, dense, 

resistant, lenticular; contains laminae of purple clay along . 

bedding surfaces____-________ _ ______ 0-5 

1. Interbedded moderate reddish-brown siltstone, shale and

silty fine-grained sandstone; weathers to slopes __ 700--750

Total Ohugwater formation______________ 750-870 

Contact between the Permian red shale and gypsum sequence and the 

Chugwater formation. Beds above the contact are silty shales, siltstones, and shaly sandstones; beds below the contact are predominantly 

gypsiferous. 

Permian:

Red shale and gypsum sequence : Measured in sec. 35, T. 48 N., R. S3 W. 

20. Limestone, pink, porous, soft, brecciated, not continuous along

outcrop _________________________________ 5. 2 

19. Gypsum, white with 2-ft bed of red siltstone in the middle_ 10. 6 

18. Partly covered, probably gypsiferous siltstone with a few beds

of gypsum_______________________________ 29. 7 

17. Gypsum, white to pink, soft, with a few thin layers of silt__ 15. 9 

339462 55 6
108 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Permian Continued

Red shale and gypsum sequence Continued Feet 

16. Siltstone, moderate-reddish-brown, gypsiferous, soft____ _ 15. 9 

15. Gypsum, white with pink laminae_________________ 1. 0 

14. Shale, grading upwards from moderate reddish brown to grayish red in the upper half. There are two thin pale-green 

chert nodule zones in the middle about 1 to 1.5 in. thick_ 3. 9 

13. Gypsum, white, soft, three 1-ft partings of moderate-reddishbrown silt in the upper half. The gypsum generally modified 

by red and gray laminae along bedding. Outcrop appears 

affected by slumping_______________________ 40. 0 

12. Siltstone and gypsum ; siltstone, moderate-reddish-brown, soft;

gypsum, white, soft_________________________ 2. 0 

11. Gypsum, white, soft__________________________ 1. 5 

10. Partly covered, potholes indicate reddish gypsiferous siltstone- 9. 0 

9. Gypsum, white with some minor red mottling__________ 7. 2 

8. Partly covered, potholes indicate reddish gypsiferous siltstone __________________________________ 8.1 

7. Limestone, yellowish-gray, porous, soft___-__________ 1. 9 

6. Dolomite, light-tan, calcareous, thin-bedded, and modified by

many darker laminae parallel to bedding_ __ ________ 2. 2 

5. Limestone, yellowish-gray, soft, porous, thin-bedded_____ 1. 0 

4. Siltstone, moderate reddish-brown, soft, platy to massive__ 37. 0 

3. Limestone, yellowish-gray, dolomitic, argillaceous and silty, 

beds thin and undulating and modified by closely spaced 

dark laminae; in the middle is 1.5 ft of thin-bedded calcareous grayish-red siltstone________.__________ 7. 9 

2. Claystone, dark- to moderate-reddish-brown, slightly calcerous,

soft __________________________________ 49.1 

1. Claystone, pale-olive-green, silty, slightly calcareous, soft__ 1. 8

Total Permian red shale and gypsum sequence______ 250. 9 

Contact between the Tensleep sandstone and the Permian red shale and 

gypsum sequence. Contact is sharp between the light-colored sandstone of the Tensleep and the dark-reddish-brown shale of the Permian 

red shale and gypsum sequence. 

Carboniferous:

Tensleep sandstone: Measured in sec. 27, T. 49 N., B. 83 W.

27. Sandstone, salmon-pink to very light tan, fine- to mediumgrained, crossbedded_______________________ 88. 0 

26. Covered ________________________________ 5. 0 

25. Sandstone, same as underlying unit but forms a separate

cliff __________________________________ 33. 0 

24. Sandstone with same lithology as unit 23 but stands out as a

separate cliff________________'.___________ 43.0 

23. Sandstone, salmon-pink, fine-grained, crossbedded, a prominent cliff former; at top is a zone containing poor molds of 

crinoid stems________________________ 46. 5 

22. Sandstone, tan to salmon-pink, fine-grained; in ledges 10 to

14 in. thick_______________________________ 22. 4 

21. Covered, possibly same as the underlying unit 20______ __ 4. 5

20. Sandstone, gray to red, fine-grained; lower 3 ft massive,

remainder thin bedded_______________________ 10.1
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 109

Carboniferous Continued

Tensleep sandstone Continued ' Feet 

19. Covered, probably sandstone as indicated by 6-iu. exposure at

base and at top__________________ 4. 5 

18. Siltstone, grayish-red to buff, sandy soft___________ 1. 2 

17. Sandstone, pink, white and tan, in 4- to 8-in. beds; in ledges;

has some thin silt zones; sandstone is very clean____ 4. 5 

16. Sandstone, salmon-pink (weathering to light reddish brown),

fine-grained, massive_________________ __ 3. 0 

15. Sandstone, reddish-tan to pink, crossbedded in the upper half,

massive below_______________________ 13. 5 

14. Sandstone, light-gray (weathering from tan to gray), finegrained, massive, forms a rounded ledge____ 12. 0 

13. Dolomite, light-tan and gray, limy, argillaceous; at top is an

irregular lens of chert-bearing foraniinifers___ ___- 2. 6 

12. Sandstone, very light tan (weathering to gray), fine-grained, 

clean, massive, somewhat crossbedclecl; contains a zone of 

siliceous nodules 4 ft from top________ _ _ 8. 4 

11. Dolomite, pinkish-gray; contains irregular sparkly salmonpink fine-grained sandstone lenses____________ 3. 6 

10. Limestone, gray (weathering to light gray), silty, massive. 1. 6 

9. Sandstone, tan (weathering to gray), fine-grained, calcareous, 

massive_________________________'. _______ 

8. Dolomite, tan, limy; appears to vary in thickness________ 

7. Sandstone, light-gray, fine-grained, massive, clean; top appears to be channeled____________________ 3. 8 

6. Dolomite, pink, limy ; contact with overlying unit is wavy___ 2. 0 

5. Sandstone, light-gray (weathering to gray), fine-grained,

massive; a 5-ft more resistant zone caps the unit______ 15. 0 

4. Dolomite, light-pink, limy, sandy_________________ 1.1 

3. Sandstone, light-gray, fine-grained____ __________ . __ 6. 4 

2. Dolomite, light-pinkish-gray____________________ 4.3 

1. Sandstone, light-gray, fine-grained, calcareous; massive in

beds about 2.5 ft thick ; forms minor ledge__________ 8. 6

Total Teaslee;) sandstone________.._______ 355.3

Contact between the Ainsden formation and the Tensleep sandstone. 

The contact is based on the presence of sandstone in the basal portion of the Tensleep sandstone and dolomites and chert in the upper 

part of the Amsden formation. 

Amsden formation : Measured in sec. 27, T. 49 N., R. 83 W.

14. Dolomite, very light gray, argillaceous______________ 2. 8 

13. Dolomite, pinkish-tan (weathering from red to tan) ; forms a 

minor ledge; silica lenses and nodules are parallel to 

bedding ___ ____ __ _ 7.8

12. Dolomite, weathers very light tan, limy, fractures irregularly- 8. 2 

11. Dolomite, tan, calcareous; in three resistant ledges: lower 

ledge weathers to a pockety surface, modified by many 

closely spaced fractures and contains a network of chert; 

middle ledge is massive; at base of upper ledge is 3 ft of 

grayish-red silty claystone overlain by 1.5 ft of pinkishgray dolomite. The remainder of the upper ledge is massive with top 1 to 2 ft a hackly light-gray chert_.. __ 41. 5
110 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Carboniferous Continued

Amsden formation Continued Feet 

10. Covered, lower portion probably contains redbeds, with a few

limestone, dolomite, and sandstone ledges__ 57. 0 

9. Breccia, weathers gray; dolomite and silica fragments in a

dolomitic matrix______________ __ 3. 4 

8. Dolomite, tan, slightly argillaceous, resistant; at top is a

disconformity __ ________-_ _ 4. 0 

7. Limestone, brown to reddish-tan, dolomitic; contains abundant irregularly shaped inclusions of silica_ ..____ 6.0 

6. Covered ___________________________ ____ 11.0 

5. Claystone, nioderate-recldish-brown, silty with irregular

light-colored fine-grained sandstone stringers__ _-_ 9. 5 

4. Covered, closoly spaced "potholes" indicate a soft fine-grained

reddish-brown sandstone in part yellowish-gray 85. 5 

3. Dolomite, light-tan, argillaceous, calcareous; has many pink

to buff zones ; fractured irregularly_____ 9. 0 

2. Limestone, tan (weathering to gray), dense to crystalline;

forms a minor ledge_ ____ _______ ______ 1. 6 

1. Sandstone, reddish-tan (weathering to brown), fine-grained,

calcareous, lenticular and contorted; contains limestone

fragments near the base as much as 6 in. long__ __ 2. 3

Total Amsdeu formation___'. ________________.____ 247. 6

Contact between the Madison limestone and the Amsden formation. 

Beds above the contact are in part red and sandy. Beds below the 

contact are gray limestones and limy dolomites. 

Madison limestone: Measured in sec. 28, T. 49 N., R. 83 W.

21. Limestone tan (weathering to gray), beds 2 to 4 ft thick___ 9. 6 

20. Limestone, light-tan, thin-bedded, less resistant than adjacent units; contains flat chert inclusions along bedding; 

disconformity at top____________________ __ 3. 5 

19. Limestone, light-tan to white (weathering to tan), massive;

erosional unconformity at top_ __ _________-_ 48. 6 

18. Limestone breccia weathers to an irregular surface, perhaps

caused by solution__________________________ 27. 4

17. Breccia, weathers to a rusty tan; dolomite, fragments in a

dolomite matrix ; disconformity at top________ ____ 7. 0 

16. Dolomite, light-gray, containing secondary calcite inclusions_ 6. 0 

15. Limestone breccia, weathering from pink to white_______ 4. 0 

14. Dolomite-limestone, light-tan (weathering to a brownish tan), 

thin and irregularly bedded, slightly limy at the base becoming limestone at the top_____________ ____ 43. 0 

13. Dolomite, light-tan (weathering to a brownish tan), massive; 

resistant forming a prominent cliff; modified by many 

closely spaced fractures at a high angle to bedding ___ 61. 4 

12. Covered __________________________________ 28. 0 

11. Limestone, yellowish-gray (weathering to gray), dolomitic, 

resistant, massive; contains a few thin zones of chert 

along bedding_____________________________ 31. 5 

10. Limestone, yellowish-gray; lower part massive, remainder 

thin- to medium-bedded with a 2-ft zone of clastic? crossbedded limestone about 20 ft from top_____________ 76. 0
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. Ill

Carboniferous Continued

Madison limestone Continued Feet 

9. Limestone, gray with a reddish tint in places, oolitic, resistant,

abundantly fossiliferous_____________________ 5. 6 

Unit contains:

Sclmcliertella? sp. 

Camarotoechiaf sp. 

Spirifer centronatus Winchell 

Punctospirifer sp. 

Composita cf. 0. humilis

8. Limestone, gray (weathering tan), dense, massive, resistant; 

contains a 3-in. zone of reworked dolomite in a limestone 

matrix at the base ; erosioual unconformity at base_____ 2. 2 

7. Dolomite, light-gray (weathering light tan), limy, argillaceous, dense; resistant in places; has thin closely spaced 

bedding laminae of grayish-red material. Contains Spirifer 

centronatus Winchell____ _______ __________ 3.0

6. Covered, probably a thin-bedded limestone or dolomite____ 26. 8 

5. Dolomite, tan to light-tan, limy; massive in the lower onefourth and upper half, the remainder thin bedded_______ 88. 7

4. Covered, probably similar to unit 35 but is thin bedded and

softer ______________________________ 12.0 

3. Limestone, light-gray with grayish-red mottling, weathering

from tan to pink, dolomitic, resistant__________ 9. 2 

2. Limestone, greenish-gray, resistant, dense; in beds from 2 in.

to 1 ft thick__________ ____________ 5. 9

1. Dolomite, tan, massive, dense_______ _ _ 3.6

Total Madison limestone _______ _____ 540. 5 

Contact between the Bighorn dolomite and the Madison limestone. Beds 

above the contact are predominantly limestone and bear a Mississippian 

fauna. Beds below the contact are massive dense dolomite. 

Ordovician:

Bighorn dolomite: Measured in sec. 28, T. 49 N., K. S3 W.

15. Dolomite, white to very light gray, argillaceous, slabby; contains abundant ostracodes on bedding surfaces___ _.. 40.0 

Float from this unit contained : 

Rliinidictya sp. 

Streptelnsma sp. 

Tropidodiscus sp. 

Raphistoma sp. 

..-.;;. Isotelus sp. 

, v Odontopleura ap.

; , . Bythocypris cf. B. cylindrica (Hall) Beyrichia sp. 

LaccoprimiHa, sp. 

Chevroleperditki, sp.

14. Dolomite, tan, massive, crystalline; contains irregular chert 

nodules along the bedding; somewhat less resistant than 

unit 12____-___________________________ 57.0 

Unit contains:

Streptelasma sp. 

Calapoecia sp. 

Halysites sp. 

Paleofavosites sp.
112 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Ordoviciau Continued

Bighorn dolomite Continued Feet 

13. Covered _________________________________ 2.0 

12. Dolomite, light-tan; in the lower 10 ft there are irregular 

streaks that are rust colored and contain a dark mineral, 

the remainder seems to be a mixture of porous and very 

dense dolomite that may account for its pitted appearance; 

there are scattered irregular inclusions of chert. The 

entire unit is somewhat fossiliferous, but the fossils are 

difficult to get out________ __________________ 188. 0

The basal 7 ft contains 'Lepidocyclus cf. L. perlamellosa 

(Rhynchotrema of authors). : 11. Transition zone dolomitic sandstone in lower half and sandy 

dolomite in upper half, light tan, abundant dark grains; 

seems to be made up of thin undulating lenses; very faint 

traces of brachiopods and solitary tetracorals ______ 3. 9 

Contact between the basal sandstone of the Bighorn dolomite and the 

dolomitic fades. Included in the dolomitic facies is a 3.9-ft transition zone of sandy dolomite. Beds above the contact are predominantly dolomite.

10. Sandstone, light-gray with dark-maroon mottling_______ 3. 5 

The upper 2 to 4 in. is a mildly undulatory bedded ferruginous zone containing Rece-ptaculities, Orthocerid( ?) 

cephalopoda? and Maclnrites sp. An equivalent zone at 

Rock Creek 12 miles north of the mapped area contained: 

Rcceptaculites oweni Hall 

Maclurites manitobensis Whiteaves 

Endoceras landerense Foerste 

9. Sandstone, silty greenish-gray, soft_______________ . 6

8. Sandstone, very light reddish gray (weathering to brick red), 

medium- to coarse-grained ; numerous red grains; massive; 

contains many "bone" fragments _ _ ____ __ 12. 2 

7. Covered ______________ ____ _________ 5. 0

6. Sandstone, light-tan with streaks of dark gray, mediumgrained ___________ ______________-________ 4. 6 

5. Sandstone, very light gray, very fine grained, very soft___ 1. 8 

4. Shale, very light gray, soft, containing one thin band of

reddish-gray shale___________-__ ____ 2. 0 

3. Sandstone, very light gray (weathering to light tan), fine- to 

medium-grained, friable, massive, modified by a few inconspicuous bedding surfaces. The whole unit is marked 

by discontinuous grayish-red laminae spaced irregularly 

about one-eighth to one-fourth inch apart. In the lower 

5 ft are pinkish lenses arranged at right angles to the 

bedding, crossbedded in part. 33 

2. Sandstone, alternating pale-greenish-gray and pale red, finegrained, thin-bedded__..________.. '__ . 6

1. Sandstone, pale-pinkish-gray, very fine grained, calcareous,

somewhat soft_________________ _'-. .8

Total Bighorn dolomite.!__JiL.J____ __ 355. 0
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 113

Contact between the Gallatin limestone and Gros Ventre formation, undivided and the basal sandstone of the Bighorn dolomite is sharp. 

Cambrian: .. i?cet 

Gallatin limestone and Gros Ventre formation, undivided: Measured 

in sees. 8 and 9, T. 47 N., R. 83 W.

8. Limestone, pinkish-gray (weathering to salmon pink) silty,

thin-bedded; contorted in part; conglomeratic (flat-pebble

i-type) ; contains grayish-red silt laminae along bedding;

fucoids present throughout __ _ _ 48. 0 

7. Covered. Lithology in this zone to the north is very similar

to the underlying unit _ 306.0 

A well-exposed section along U. S. Highway 16 at a point 

5^6 miles north of the mapped area contained the following : 

Dikelocephalus sp. 

Illaenurus cf. /. calvini, Walter 

Corlinia sp. 

Kold-inioidea-f sp.

Dendroyraptiis hallianus (Prout)(?) 

eclivardxi Ru^demaimV sp.

6. Silt-stone, salt shale, limy sandstone; grayish green, very 

slabby; sandstone is light tan, line to medium grained and 

glauconitic, inarticulate brachiopocls and poorly preserved 

trilobites throughout, unit forms a slope__________ 6.1. 0 

5. Sandstone, dusky red with streaks of olive green, mediumgrained, crossbedded; beds range from 6 in. to 4 ft, glauconitic and hematitic; contact with overlying unit is sharp. 18. 0 

4. Sandstone, dusky-yellow-green, medium-grained, very glauconitic, a few shale laminae, friable_______________ 43. 0 

3. Sandstone : shale in about a 2 : 3 ratio ; sandstone is yellowish

gray weathering to brown, medium grained, thin bedded ' ' ' 

and glauconitic; shale is grayish green, silty, glauconitic, : 

poorly preserved trilobite fragments in the lower 2 ft___ '54.1 

Contains:

Arapahoia convex® Lochman 

nichartensia Lochman 

<; #/) inoya Loch in a n 

Ccdaria niwonia Lochman 

Dicellomus occidental!s Bell 

Tricrepicephalus sp. 

Unca-spis sp.

2. Sandstone, green, medium- to course-grained, glauconitic, 

friable, appearance very similar to gunpowder, many 

grayish-green silt shale laminae .and a thin bed of olivegray plastic clay near top, the upper 5 ft becomes si.mly and 

slabby Contains Bolasp.idella^ sp., Syspachvilus cf. S. 

dunoircnsis (Miller)______'.__________ ___ ___ 13. 6

1. Sandstone, dark-greenish-brown, (weathers to a reddish 

brown) in beds up to 1.5 ft, crossbedded, very glauconitic, 

very poorly preserved trilobites_____________ _ .. 7.3

Total Gallatin limestone and Gros Ventre formation, 

undivided___________________________ 551. 0
114 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Cambrian Continued

Contact between the Flathead sandstone and the;Gallatin limestone 

and Gros Ventre formation, undivided, is characterized by nonglauconitic resistant sandstone below and glauconitic friable sandstone 

above. ; V': .'".'

Flathead sandstone : Measured in section 28, T. 49 N., R. 83 W. Feet 

7. Sandstone, gray in the lower half and top 10 ft, the remainder 

reddish gray; in other places this unit is light tan, medium 

grained, well rounded and spherical, friable. In the upper 

6 in. are abundant inarticulate brachiopods. "Elrathia" sp. 

was collected from this zone 12 miles north of the mapped 

area__________________________________ 23. 5 

6. Sandstone, predominantly tan but unit has a few buff and red 

beds, medium to coarse grained, some massive beds as much 

as 6 ft thick_______________________________ 42. 5 

5. Sandstone, buff, medium- to coarse-grained; grains are well 

rounded and spherical; beds are about 1 to 2 ft thick, unit 

forms a slope. In the upper 20 ft are several 2-in. ferruginous zones parallel to the bedding _ ___ ___ _ 48. 5 

4. Mostly covered, probably similar to unit 3______ ____ 28. 0 

3. Sandstone, tan (weathering to reddish tan), medium- to

coarse-grained, soft, clean; upper 30 ft partly covered____ 58. 0 

2. Sandstone, reddish-brown, medium to coarse-grained, crossbedded, friable__________________________ 11. 5 

1. Partly covered, small holes indicate a brownish-red sandstone, 

medium- to coarse-grained, crossbedded and soft. In other 

places the basal 10 to 15 ft are conglomeratic with rounded 

quartz pebbles as much as one-half inch in diameter_______ 45

Total Flathead sandstone____________________ 258.0 

Contact between the pre-Cambrian and Cambrian Flathead sandstone. 

Contact is sharp, and the surface upon which the Flathead sandstone lies 

is flat.

Foliated pre-Cambrian granite.

Amsdeu, T. W., and Miller, A. K. 1942, Ordovician conodonts from the Bighorn

Mountains of Wyoming: Jour. Paleontology, v. 16, p. 301-306. 

Andrews, D. A., Lambert, G. S., and Stose, G. W., 1944, Geologic map of Montana:

TJ. S. Geol. Survey Oil and Gas Inv. Prelim. Map 25. 

Bramlette, W. A., 1949, Billy Creek gas field: Wyo. Geol. Assoc. Guidebook,

4th Ann. Field Conf. in the Powder River Basin, p. 83. 

Brown, R. W., 1948, Age of the Kiugsbury conglomerate [Wyo.] is Eocene:

Geol. Soc. America Bull., v. 59, p. 1165-1172. 

Carlson, C. E., 1949, Geologic map and structure sections of the Red Fork Powder

River area: Wyo. Geol. Assoc. Guidebook, 4th Ann. Field Conf., Powder

River Basin, insert. 

Chamberlin, R, T., 1940, Diastrophic behavior around the Bighorn Basin, Mont.

and Wyo.: Jour. Geology, v. 48, p. 673-716. 

Cobban, W. A., 1951, Colorado shale of central and northwestern Montana and

equivalent rocks of Black Hills: Am. Assoc. Petroleum Geologists Bull.,

v. 35, p. 2170-2198.
GEOLOGY OF CRAZY WOMAN CREEK AREA, JOHNSON COUNTY, WYO. 115

Cobban, W. A., and Reeside, J. B. Jr., 1951, Lower Cretaceous ammonites in

Colorado, Wyoming, and Montana: Am. Assoc. Petroleum Geologists Bull.,

v. 35, p. 1892-1893. 

Crowley, A. J., 1951, Possible Lower Cretaceous uplifting ot: Black Hills, Wyo.

and S. Dak.: Am. Assoc. Petroleum Geologists Bull., v. 35, p. 83-90. 

Darton, N. H., 1904, Comparison of the stratigraphy of the Black Hills, Bighorn

Mountains, and Rocky Mountain front range: Geol. Soc. America Bull. v. 15,

p. 379-448.

 1906, Geology of the Bighorn Mountains: U. S. Geol. Survey Prof. Paper

51, p. 1-121. 

Demorest, M. H., 1941, Critical structural features of the Bighorn Mountains,

Wyo.: Geol. Soc. America Bull., v. 52, p. 161-175. 

Flower, R. H., 1952a, Cephalopods from the Harcling and Manitou formations

of Colorado: Jour. Paleontology, v. 26, p. 505-518.

 1952b, New Ordovician cephalopods from eastern North America: Jour.

Paleontology, v. 26, p. 25-26. 

Furnish, W. M., Barragy, B. J., Miller, A. K., 1936, Ordovician fossils from

upper part of type section of Deadwood formation, South Dakota: Am.

Assoc. Petroleum Geologists Bull. v. 20, p. 1329-1341. 

Gale, H. S., and Wegemann, C. H., 1910, The Buffalo coal field, Wyoming: U. S.

Geol. Survey Bull. 381, p. 137-169. 

Granger, Walter, 1914, On the names of lower Eocene faunal horizons of

Wyoming and New Mexico: Am. Mus. Nat. History, v. 33, p. 202-205. 

Hancock, E. T., 1920, Lance Creek oil and gas field, Wyoming: U. S. Geol. Survey

Bull. 716, p. 35-53. 

Hayden, F. V., 1869, Geologic report of the exploration of the Yellowstone and

Missouri Rivers under the direction of Captain W. F. Raynolds: 40th Cong.,

2d Sess., S. Doc. 77. 

Imlay, R. W., 1947, Marine Jurassic of Black Hills area, South Dakota and

Wyoming: Am. Assoc. Petroleum Geologists Bull., v. 31, p. 227-273. 

Kirk, Edwin, 1930, The Harcling sandstone of Colorado: Am. Jour. Sci., ser. 5,

v. 20, p. 456-466. 

Love, J. D., 1939, Geology along the southern margin of the Absaroka Range,

Wyo.: Geol. Soc. America Special Paper 20, p. 1-134.

 1948, Mesozoic stratigraphy of the Wind River Basin, central Wyoming: 

Wyo. Geol. Assoc. Guidebook, 3d Ann. Field Conf., Wind River Basin, 

p. 96-111.

Love, J. D., Deiisou, N. M., and Henbest, L. G., 1953, Stratigraphy and paleontology of Paleozoic rocks, Hartville region, eastern Wyoming: U. S. Geol. 

Survey Oil and Gas Inv. Chart OC 44.

Love, J. D., Johnson, C. O., Nace, H. L., Sharkey, H. H. R., Thompson, R. M., 

Tonrtelot, H. A., Zapp, A. D., 1945, Stratigraphic sections and thickness maps 

of Triassic rocks in central Wyoming: U. S. Geol. Survey Oil and Gas Inv. 

Prelim. Chart 17.

Love, J. D., Thompson, R. M., Johnson, C. O., Sharkey, H. H. R., Tourtelot, H. A., 

and Zapp, A. D., assisted by Nace, H. L., 1945, Stratigraphic sections and 

thickness maps of Lower Cretaceous and nonmarine Jurassic rocks of central 

Wyoming: U. S. Geol. Survey Oil and Gas Inv. Prelim. Chart 13.

Love, J. D., Tourtelot, H. A., Johnson, C. 0., and others, 1945, Stratigraphic 

sections and thickness maps of Jurassic rocks in central Wyoming: U. S. 

Geol. Survey Oil and Gas Chart 14.

Love, J. D., and Weitz, J. L., 1951, Geologic map of the Powder River Basin and 

adjacent areas, Wyoming: U. S. Geol. Survey Oil and Gas Inv. Map OM 122.
116 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Lupton, C. T., 1916, Oil and gas iiear Basin, Bighorn County, Wyo.: U. S. Geol.

Survey Bull. 621, p. 157-190. 

Miller, A. K., 1932, The cephalopods of the Bighorn formation of the Wind River

Mountains of Wyoming: Conn. Acad. Arts Sci. Trans., v. 31, p. 193-297. 

Osterwald, F. W., 1949, Structure of the Tongue River area, Bighorn Mountains,

Wyo.: Wyo. Geol. Assoc. Guidebook, 4th Ann. Field Conf., Powder River

Basin, p. 37-39. 

Pierce, W. G., Andrews, D. A., Keroher, J. K., 1947, Structure contour map of

the Bighorn Basin, Wyo. and Mont.: U. S. Geol. Survey Oil and Gas Tuv.

Prelim. Map 74.

Petroleum Information, July 4, 1952. 

Richards, P. W., and Rogers, C. P. Jr., 1951, Geology of Hardin area, Bighorn

and Yellowstone Counties, Mont.: U. S. Geol. Survey Oil and Gas Inv. Map

OM 111.

Rubey, W. W., 1930, Lithologic studies of fine-grained Upper Cretaceous sedimentary rocks of the Black Hills region: U. S. Geol. Survey Prof. Paper

165-A. 

Sharp, R. P., 1948, Early Tertiary fauglomerate. Bighorn Mountains. AVyo.: Jour.

Geology, v. 56, p. 1-15. 

Thorn, W. T. Jr., 1936, Deep focus earthquakes from a geologist's point of view:

Am. Geophys. Union Trans., v. 17, pt. 1, p. 108-111. 

Thomas, H. D., 1948, Summary of Paleozoic stratigraphy of the Wind River

Basin, Wyo.: Wyo. Geol. Assoc. Guidebook, 3d Ann. Field Conf., Wind River

Basin, Wyo., p. 79-95. 

Wegemann, C. H., 1912, The Sussex coal field, Johnson, Natrona, and Converse

Counties, Wyo.: U. S. Geol. Survey Bull., 471-F, p. 21-38. 

 1913, The Barber coal field, Johnson County, Wyo.: U. S. Geol. Survey

Bull. 531, p. 262-284. 

Wilson, C. W., 1938, The Teiisleep fault, Johnson and Washakie Counties, AVyo.:

Jour. Geology, v. 46, p. 686-881. 

Wilson, J. B., 1951, Stratigraphy of the Sussex sandstone, Powder River Basin,

Wyo.: Wyo. Geol. Survey Rept. Inv. 3, p. 1-11.
INDEX

Page

Accessibility of the area.__. ._._._...___ 42 

Acknowledgments . ._. ._ 36-37

; Alcove limestone member, Chugwater formation.. 51,52

Allanite. ..... .......................... 88-89

spcctroscopic analysis....--.-...--...--.-. 90

Alluvium..._ __....._ ..._____ 73

Amsden formation, description.--....-__... 49

fauna .... .......................... 49

stratigraphic section..--....---.....--.- 109-110

Annell, Charles, spectroscopic analysis.._.. 90

Bcarpaw shale, description...-.-.--..-.--.... 64-65

fauna.....-.-.-..-...---.-.....---.-.._ 65,92

stratigraphic section....----------____ 92

Beaver Creek anticline...._......_____ 76

Bentonite.-... . 89

Bighorn dolomite___. ...___.__.__ 39 

description.____ __________ 45-48 

fauna.......................... 46,47,48, 111, 112

stratigraphic section----.-..--.-..---... 111-112

Billy Creek anticline-----.-...----.. 48, 49, 76; pi. 6

Billy Creek gasfleld, discovery well..------.. 78-80

Black Hills, faunal zones in the Frontier formation.___. ___________ 60-61

Cambrian, stratigraphic sections ---. - 113-114 

Carboniferous, stratigraphic sections.... . 108-111

Cenozoic rocks.------.- ----- -- --. 43,66-73

Chugwater formation..' - . --- 51-52 

stratigraphic section----. -------------- 107

Climate.-..---.-.-----.------.--------.----.. 42

Clinker -----..-..-------.------..------.--. 81

Wasatch formation.-- . - .-__ 69

Cleverly formation.- -- .--- -- -. 43

description.-..-.--.-- ......... 56-57; pi. 9

stratigraphic section----.-.--.-----.---_ 104

Coal... , . 81-88

in T. 47 N., R. 81 W ...... 81-83, 84; pi. 11

in T. 48 N., R. 80 W.......... 81, 83, 85; pi. 12

in T. 49 N., R. 80 W...... 81, 85, 87-88; pis. 6, 13

reserves.--..--.....----.....---- 81,83,84,86-87

sections.-...--..-.-_____........ 82, 85; pi. 6

Wasatch formation...__-------_------ 69-70

Cody shale.....-----...----....-----...------ 61

description.......---------------------- 61-63

fauna . . 61-63,93-99

stratigraphic section_. .. _ -.. 93-99 

Construction materials. ------------------- 89

Cretaceous, stratigraphic sections-_..... 91-104

Crow Mountain sandstone member, Chugwater formation...------. --- 51-52, 54

Deadwood formation.--..--.-.--.-.-. ---.--. 44,45 

Discharge of streams__--------- ----------- 40-42

DrainagePage 

. 40-42

Economic geology.------- 78-90

Fauna, Amsden formation _.............. 49

Bearpaw shale ___.___...____ 65,92 

Bighorn dolomite --------- 46,47,48,111,112

Cody shale--------.-----..----.. 61-63,93-99

Flathead sandstone__.............._.44,114

Frontier formation............ 60-61,99,100,101

identification .... -.... ...... 37

Kingsbury conglomerate member,

Wasatch formation...______ 68 

Madison limestone..-. --________49, 111 

Morrison formation. .__..__.__55,105 

Parkman sandstone.._-.....---.-...... 92

Shannon sandstone member, Cody shale. 63,94 

Sundance formation _....-.-..55,106

Tensleep sandstone ---------__ 50,108,109

Wasatch formation. _ 68, 70

Faunal zones, Frontier formation...------_ 60-61

Field work..---.-.--------.-----------...--. 36

Flathead sandstone, description..... ....--- 44

fauna__--------__ 44,114

stratigraphic section.-.----.-...--.. .... 114

Folds and faults--..---- ------ -. 73-77

Fort Union formation _...._..___... 68,70

description.-----..--.-....--.-....-.-.. 66-67

dips in.....____--------_____.-- 76-77

Frontier formation...... - 43,63

description..------ ..................... 59-61

fauna.---------- ---.. 60-61,99,100,101

stratigraphic section...................... 99-101

Oallatin limestone and Oros Ventre formation, undivided-_............... 47

description...-- ........................ 44-45

stratigraphic section...._____.....__ 113

Geography.-.._......... _...__ .., 38-42

Gypsum Spring formation ...--_...-.....-. 43

description..........._..__ ... 52-54

stratigraphic section........_......... 106-107

Gravels, terrace.----..-.-.----------..-_... 71-73

Harding sandstone of Colorado... 47-48 

Horn anticline.._ - - - 76

Horn fault-------...---- ------------------- 74,76

Irrigation. .-__........................... 42

Jurassic, stratigraphic sections.-. ----- ..- 104-107

Kingsbury conglomerate member, Wasatch

formation, description..._ 67-70; pi. 6 

fauna_..-....--------...-....--.--.-..-- 68

117
118 INDEX

Page 

Lance formation---. - - 43, 67

description-------.----.-------.---------. 65

stratigraphic section----------......--.... 91

Lander sandstone member, Bighorn dolomite...__....__________ 47-48

Location of the area.__ ._---...__ _---._. 35

Madison limestone, description .---.-----..- 48^9 

fauna._______._...._.._____ 49,111 

stratigraphic section,_.-------_..__--.-- 110-111

Manganese... ..--.. .... ... 88

Map compilation ----------------------- - 36

Mesozoicrocks..---------.-------.---.. 43,51-65

dips in..--.---- ----- --- ---- 74; pi. 6

Moncrief member, Wasatch formation, description .-.-.....-_... 67,68-69

Morrisonformation - --------_----.__ 43,57

description.- .._. -------- - 55

fauna.__ _ ...._..._... . 55,105

stratigraphic section----------------. 104-105

Mowry shale______----------_ 43, 61, pi. 10

description-..--------- ------_. 58-59

stratigraphic section.. -__ ... 102-103

Mush Creek oilfield..---.__-.-_--_____...-..- 58 

electric logs... ---------- ---... 56-57; pi. 9

Newcastle sandstone..-. -------------- 43,57,59

description,. ---- ... 58; pi. 9

stratigraphic section-- ._.-..-. 103

Nugget sandstone..- ------- 52

Oil and gas potentialities-.----.-...__.--... 78-81 

Ordovician, stratigraphic section..___ 111-112

Paleozoic rocks. . ------- __-.. 43

description..-.--.-- --- ------ -.- 44-51

dipsin--- , --------------- 74-75; pi. 6

Parkman sandstone.. ... ....-. .. 65 

description..- -------------------------- 64

fauna___ .- ---- ----------..- --- 92

stratigraphic section. 92-93

Permian red shale and gypsum sequence..-.. 43,52 

description.. - --- -- --- - 50-51 

stratigraphic section. ------------------- 107-108 

Pre-Cambrian rocks, description.-__-------- 43

folds... 74

Precipitation--...----.. ------ ----------- 41,42

Previous investigations....-....... __ _- .37-38 j

Quaternary rocks, description. 71-73 '

Page

Red Peak member, Chugwater formation.... 51-52

Relief, structural...-..--.-......-.......-.--- 73

topographic-....__ ._ -__-__.. 38

Roads-.-------------.- _ .._ _ 42

Settlement-. .-.- -..__- .-..-._- 42

Shannon sandstone member, Cody shale.--.. 63

fauna - - - . _ 63,94

stratigraphic section___............_ 93-94

Skull Creek shale----.--. ------ 43, 56; pi. 9

description... 1...... ......._ 57-58

stratigraphic section..---------- - -.... 103

Steel Creek anticline_-.._ ._.. 48, 49, 76; pi. 6 

test holes...-_.....__._ .___._ _ 80

Stratigraphic sections, location and measurement _-... 43

Mesozoic rocks.. -__..__.._____.___.. 91-107

Paleozoic rocks----------- -------. .. 107-114

Stratigraphic traps, possibility of oil accumulation___..._._,..-.___. 80-81 

Stratigraphy--.---....-.----.-.-.--.---- 42-73

Structural history.__.. _______-_______._... 77-78

Structural terrace.--.___..-.....___ 76-77,80

Structure, regional features.---------_...... 73-74

Sundance formation_..._. .---._____ 43,53 

description_.______._._______._________... 54-55

fauna __ _____ 55,106

stratigraphic section.. _ -_ . 105-106 

Sussex-Meadow Creek oilfield._.- - 80

Temperature.--.. ................._._ 41

Tensleep Fault---.--.--.--..----.-..- 44,74,76

Tensleep sandstone, description...- - -- . 49-50 

fauna - -- -- 50,108,109 

stratigraphic section. ---.---.... .-.'11.... 108-109

Terraces, gravels capping_. __ .. 72,89 

levels.-------.----.---------------- 73; pi. 6

Thermopolis shale.._.......___.'._: .:. 58,59

Topography.---...---.-.----.----.----. 38

Triassic, Chugwater formation, stratigraphic

section-----------.--. . ---.. 107

Vegetation---.----.------.------------- 42

Wasatach-formation. -_. ,... .. 73,76-77 

description.. -. . . ...... 67-70

fauna - - -- 68,70

un conform it y. _ - - .- . 67

Water supply.--- - 40-42

West Billy Creek anticline.------------ 75-76; pi. 6

White River formation, description -.-..-. 70-71

o