Please do not destroy or throw away this publication. If you have no further use for 

it, write to the Geological Survey at Washington and ask for a frank to return it

UNITED STATES DEPARTMENT OF THE INTERIOR 

Harold L. Ickes, Secretary

GEOLOGICAL SURVEY 

W. C. Mendenhall, Director

Bulletin 847 B

THE ROSEBUD COAL FIELD

ROSEBUD AND CUSTER COUNTIES

MONTANA

BY

W. G. PIERCE

Contributions to economic geology. 1934-36 

(Pages 43-120)

UNITED STATES

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1936

For sale by the Superintendent of Documents. Washington, D. C. ------- Price $1.25

CONTENTS

Page

Abstract. _______...__._-_-_-.__-___---.____-_-____--._____-._-._-- 43

Introduction__ .-___..____.___._.-_-_._.-.---_._--.____-.._.__.- 44

Location and relations of the field.._____________________________ 44

Previous investigations.________--__-_--_______-___________-_-- 45

Field work and acknowledgments._.____________________________ 46

Land surveys---___-__-------.----__----__--__-._-__--_-.--.-- 47

Magnetic declination_.-..-...........-_-....._.._____-.._-..-. 47

Geography.. _--._-._.-- _. --.._.. .... ..._.... 47

Land features.______-__-.___-----.-.----_--...-__-----_.----- 47

Drainage and water supply.... . .._...__........ 48

Timber, culture, and settlement _____________________________ 51

Routes of travel.____-_______-----_-_-----___---_-__--__-_---- 52

Stratigraphy.._________________________ --____-.____--_-___--- 53

Tertiary (?) system_____.___..__-_._.___.__._..._.__.__..__.. 53

Lance formation.__.__.__-_---__---_...____-______._._..-_ 53

Hell Creek member_-.---_.----._.__-.____._-__.----- 53

Tullock member.._..-.--__-.-__.___.__.___.._._.__.-- 54

Tertiary system._____________-_-_---_-_-.__-.__-_______._-__-. 57

Fort Union formation__ ...............................^... 57

Lebo shale member..__________________________________ 57

Occurrence and character._______._..____.____..___ 57

Correlation eastward- ...........................^. 60

Tongue River member-_-__--_-_-_____-___-________---_ 61

Tertiary (?) and Quaternary deposits.___________________________ 64

Terrace gravel.__________-___----__---_-_____-____-____--- 64

Alluvium__ __--_-__---_-_-_--_--_-_-___---_-___-_-__--_- 66

Structure ________________ _________-_____-_-_______-____..-_____--- 66

Relations and character________________________________________ 66

Faults.-________-___---_-___-.---_-_------__-_-___-_--_____-_ 68

Superficial folds and slumps.__-__.-____--_-.-.-_.__.___________ 69

Geomorphology . __----_-__--_-_-_-_-_-___--__-___---_____-________ 71

Coal__.._____.___.___.__....____._.___._... 73

General section_______-__-_-_-_-_-_-----_-___-_____-_-___._..- 73

The coal beds.....--___-__._. ____-_--___________.__.___.__ 75

Coals of the Tullock member of the Lance formation._________ 76

Wright bed___--_-_-___---____-____-____-_-__---____._ 76

Coal beds in the lower part of the Tullock___________i__ 76

Coal beds in the upper part of the Tullock _______________ 77

Coals of the Lebo shale member of the Fort Union formation. __ 77

Big Dirty bed.__---___-___-_-__--___--_______________ 77

Bed at the base of the Lebo in the eastern part of the field. _ _ 78

Bed in the upper part of the Lebo__._---__________--__ 78

Local beds in the Lebo________-___--_________-__-___- 78

Coals of the Tongue River member of the Fort Union formation. 78

Bed at the base of the Tongue River member___________ 78

Trail Creek coal zone..__---__-__--_-___--____________- 78
IV CONTENTS

Coal Continued.

The coal beds Continued,

Coals of the Tongue River member of the Fort Union formation Continued. Page 

Burley bed._------_-______-___________-______________ 79

Foster bed_______._____________ ______________________ 79

Terretbed________"_.____________________ 79

Haddow bed_____________________________________ 80

Flowers bed_.______________________________________ 80

McKay and Rosebud coal beds.________________________ 80

Physical and chemical properties ___________________________ 80

Coal clinker______________________________________________ 81

Quantity of coal__________________________________________ 82

Outlook for development_________________________________ 84

Details by townships______________________________________ 85

ILLUSTRATIONS

Page

PLATE 5. A, Typical topography of the Tongue River member of the Fort 

Union formation, E^ sec. 16, T. 5 N., R. 45 E.; B, Contact 

of the Tongue River and Lebo members of the Fort Union 

formation, sec. 3, T. 5 N., R. 44 E...................... 52

6. A, View looking north across the Tongue River Valley from the 

SWK sec. 27, T. 4 N., R. 47 E.; B, Bench at the top of the Tullock member of the Lance formation, sec. 10, T. 5 N., R. 42 E_ 53

7. A, Superficially folded coal bed on Sweeney Creek, SE% sec. 

27, T. 6 N., R. 43 E.; B, Superficial fold exposed on Coal 

Creek, SW^sec. 30, T. 6 N.,R. 44E.____________________ 68

8. A, Superficial fold involving a coal bed in the Tullock member 

of the Lance formation, in sec. 14, T. 4 N., R. 47 E.; B, 

Slump block of steeply dipping Tongue River strata resting 

on horizontal Lebo beds, sec. 23, T. 3 N., R. 47 E_ __________ 69

9. Stratigraphic position of the coal beds in the Rosebud coal field

and their correlation with principal coals of adj oining fields _ 76

10. Generalized sections across the Rosebud coal field, showing

the position and relation of the coal beds___________ In pocket

11. Geologic map of the Rosebud coal field, Montana________ In pocket

12. Sections of coal beds in T. 2 N., R. 42 E____________ 90

13. Sections of coal beds in T. 3 N., R. 43 E_________________ 96

14. Sections of coal beds in T. 2 N., R. 43 E___._--__-_._____ 96

15. Sections of coal beds in T. 3 N., R. 44 E___________________ 102

16. Sections of coal beds in T. 2 N., R. 44 E_______--__-___-___ 102

17. Sections of coal beds in T. 4 N., R. 45 E_______________ 104

18. Sections of coal beds in T. 3 N., R. 45 E____._-___.____ 104

19. Sections of coal beds in T. 5 N., R. 47 E____________ 110

20. Sections of coal beds in T. 4 N., R. 47 E___________ .'... 112

21. Sections of coal beds in T. 3 N., R. 47 E______--___-.____._ 112

FIGURE 7. Index map showing location of Rosebud coal field, Montana. _ 45

8. Structure map of the Rosebud coal field,___________________ 67

9. A typical fault in the Rosebud coal field._____--_____--_ 68
ILLUSTRATIONS V

Page

FIGURE 10. Diagrammatic section of a slump in T. 3 N., R. 47 E_._... 70

11. Lenticularity of the coal in the Tullock member of the Lance

formation.___________________________________________ 76

12. Sections of coal beds in T. 6 N., R. 42 £...__............. 85

13. Sections of coal beds in T. 5 N., R. 42 E__..______ 87

14. Sections of coal beds in T. 4 N., R. 42 E___._______ 89

15. Sections of coal beds in T. 3 N., R. 42 E__..._______ 90

16. Sections of coal beds in T. 6 N., R. 43 E.____.._....._. 92

17. Sections of coal beds in T. 5 N., R. 43 E___.._._... 94

18. Sections of coal beds in T. 4 N., R. 43 E__.__.__.__._ 95

19. Sections of coal beds in T. 6 N., R. 44 E................. 98

20. Sections of coal beds in T. 5 N., R. 44 E__....._.__._ 99

21. Sections of coal beds in T. 4 N., R. 44 E_______...___ 100

22. Sections of coal beds in T. 5 N., R. 45 E.___..._.___ 104

23. Sections of coal beds in T. 2 N., R. 45 E__._.._._...... 106

24. Sections of coal beds in T. 5 N., R. 46 E................. 107

25. Sections of coal beds in T. 4 N., R. 46 E................. 109

26. Sections of coal beds in T. 3 N., R. 46 E______..__... 110

27. Sectionsof coal beds in T. 5 N., R. 48 E.............._.. 114

28. Sections of coal beds in T. 4 N., R. 48 E......._.___ 115

29. Sections of coal beds in T. 3 N., R. 48 E......__._... 117

30. Sections of coal beds in T. 5 N., R. 49 E................. 118

31. Sections of coal beds in T. 4 N., R. 49 E__.-_.-.-........ 119

32. Sections of coal beds in T. 3 N., R. 49 E._........._.__ 120

THE ROSEBUD COAL FIELD, ROSEBUD AND CUSTER 

COUNTIES, MONTANA

By W. G. PIERCE

ABSTRACT

The Rosebud coal field, named from Rosebud Creek and the village of 

Rosebud, includes an area of about 1,050 square miles and forms a very small 

part of the subbituminous and lignite coal fields of eastern Montana and 

Wyoming and the western part of the Dakotas. It is an irregularly bounded 

tract lying south of the Yellowstone River in eastern Rosebud County and 

western Ouster County and measures 50 miles from east to west and 28 

miles from north to south. It adjoins the Forsyth coal field, on the west, the 

Ashland coal field, on the south, and the Miles City coal field, in part, on the 

morth.

The southern part of the field and the Rosebud Creek-Tongue River divide, 

which passes northward nearly across the west-central portion of the field, 

include high timbered areas, but most of the field is timberless and contains 

'badlands and rolling country. The highest altitude in the area is 3,475 feet, 

and the lowest is 2,400 feet on the Yellowstone River. The maximum relief 

ihi the field is therefore 1,075 feet.

The exposed rocks are continental and belong to the Lance (Tertiary?) 

and Fort Union (Tertiary) formations. A full section of the Tullock member 

of the Lance and several hundred feet of the underlying Hell Creek member

 of the same formation are exposed in the Rosebud Creek Valley. The Hell 

Creek member has a slight greenish tint and is practically non-coal-bearing, 

tout otherwise it is similar lithologically to the Tullock member. The Lance 

is overlain conformably by the Fort Union formation, which is divided into a 

lower (Lebo) member and an upper (Tongue River) member. In the Rosebud 

'Creek Valley the Fort Union and Lance formations are distinguished by differences in lithology, and the contact is marked by the base of the Big Dirty

 coal bed, but in the Tongue River Valley their separation is difficult. The contrast between the two members of the Fort Union formation the somber-

 colored Lebo shale and the yellow sandy Tongue River member is marked, 

'but the contact is gradational through a zone 20 to 40 feet thick.

The formations exposed in the Rosebud coal field are almost flat-lying, and 

the maximum structural relief is only about 250 feet. The axis of a very 

shallow syncline trends northeastward, approximately following the valley of 

the Tongue River, and a slight anticlinal nose in the northwestern part of the 

field plunges southeastward. In addition there are a few small and superr 

flcial folds that may have been formed as a result of the movement of nearby 

slump blocks or landslides. Two formal faults, each with a throw of about 

60 feet, were observed; they appear to be related to differential compaction 

of the underlying beds.

Gravel and terrace remnants occur in many parts of the Rosebud coal field. 

The terraces in the Yellowstone Valley are well preserved; those in the smaller

43
44 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

valleys are dissected and less distinct. Ten or more terraces, which are 

younger than the Flaxville Plain (Miocene or Pliocene), were recognized 

in the Yellowstone Valley. They are all of Pliocene (?) or Pleistocene age.

The drainage pattern in the Rosebud coal field, as well as elsewhere in 

eastern Montana, presents unusual features. In the areas where the streams 

flow northeastward the interstream divides lie southeast of the median line 

between the streams. Also, numerous streams abruptly change their trend 

from northeast to northwest. The suggested explanation for these features is 

that the region has been tilted toward the northwest, thus increasing the 

gradients of the northw.estward-flowing streams and decreasing the gradients 

of the southeastward-flowing streams, thereby causing a shift of the interstream 

divides and probably piracy by some of the streams that were steepened. Presumably the tilting took place at a time when the region had a low relief.

This field contains an estimated total quantity of 1,171,000,000 tons of subbituminous coal in beds over 1% feet thick, of which 85 percent is in the Tongue 

River member of the Fort Union formation. Of the total estimated tonnage, 

30 percent is in beds from 1% to 3 feet thick and 70 percent is in beds over 3 

feet thick. There is no commercial mining in the field at present.

INTRODUCTION

Location and relations of the field. The Rosebud coal field is in 

Kosebud and Ouster Counties, in southeastern Montana. It is south 

of the Yellowstone River, between the Forsyth coal field, on the west, 

the Ashland coal field, on the south, and the Miles City coal field, on 

the north. It includes an irregular-shaped area of 1,050 square miles, 

which is crossed by the drainage basins of Rosebud Creek and the 

Tongue River. This field is a small part of the large subbituminous 

and lignite fields of eastern Montana and Wyoming and the western 

part of the Dakotas. It is named from the town of Rosebud and 

Rosebud Creek.

Figure 7 shows the location of this field and its relation to other 

coal-bearing fields that have been mapped and described in publications of the Geological Survey. The names of the fields and references to the Geological Survey publications in which they have been, 

described are as follows:

Coal fields whose locations are shown in figure 7

No.

1

?,

3

4

5

6

7

8

ft

10 

11

12

13

14

IS

16

Field

.-..do 

Northwestern South Dakota ....

Sidney ________ . ..........

Bulletin

775.

381-A.

726-A.

541-Q.

575.

381-A and

471-C.

726-D.

531-E.

341-A.

627. 

471-D.

751-E.

381-A.

471-D.

471-D.

471-D.

No.

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Field

Baker ____ . ..................

Miles City...... .......-.....

Forsyth. .^ ______ . ..........

Tullock Creek..................

coal field.

Pine Ridge- __________

Bulletin' 

471-D.

751-F.

531-F.

341-A.

812-A.

749.

647.

341-B.

381-B.

4.71 A

806-B.

796-A.

831-B..

 856.

541-H,

847-B.

847-C.
ROSEBUD' COAL FIELD, MONTANA' 45

Previous investigations. The general geologic features of this 

area have been known for many years through the work of several 

geologists, though none of the published reports give a detailed 

description of the geology or coal deposits. Dobbin 1 has mapped 

the geologic boundaries and coal beds in an area adjacent to the 

western boundary of the field. Bass 2 has made similar surveys of

the Ashland field, adjoining the southern boundary. Renick 3 describes the principal geologic features in this and adjoining areas 

and gives information on wells and quantity and quality of the

1 Dobbin, C. E., The Forsyth coal field, Rosebud, Treasure, and Big Horn Counties, 

Mont.: U. S. Geol. Survey Bull. 812, pp. 1-55, 1929.

" Bass, N. W., The Ashland coal field, Rosebud, Powder River, and Custer Counties, 

Mont. : U. S. Geol. Survey Bull. 831, pp. 19-105, 1932.

3 Renick, B. C., Geology and ground-water resources of central and southern Rosebud 

County, Mont.: U. S. Geol. Survey Water-Supply Paper 600, 1929.
46 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

water. The oil possibilities of southeastern Montana, including the 

area of the Kosebud coal field, are discussed in a press notice by 

Dobbin and Thorn.4 The stratigraphy and broad structural features 

of eastern Montana have been described by Thorn and Dobbin.6 

Rowe 6 has mentioned briefly the occurrence of coal in this area. 

Collier and Smith 7 mapped an area which joins this on the north,, 

but four of the townships that are included in their report were 

mapped for further detail and are included in the present report,

Field work and acknowledgments. During the summer of 1929- 

the southwestern part of the area was mapped by the writer, assisted 

by Roland W. Brown, D. A. Andrews, F. H. Kellogg, and T. D, 

Mundorf; and in the summer of 1930 the mapping was continued by 

the writer, assisted by A. W. Quinn, H. E. Thomas, T. D. Mundorf, 

and G. C. Sleight. George Newlin served as camp hand for the party 

during both summers.

The method of mapping employed was a combination of triangulation and stadia traverse, with a plane table and telescopic alidade, 

A triangulation net expanded from a measured base line was extended over the entire area and used for horizontal and vertical control. The positions of geographic features, geologic boundaries, outcrops of coal beds, and altitudes were largely determined by stadia 

traverses originating at triangulation points. The positions of the 

land lines were determined by locating numerous section corners. 

Altitudes in the field are based on bench marks established at Col-1 

strip, Mont., by engineers of the Northern Pacific Railway and were 

subsequently checked with the United States Coast and Geodetic 

Survey bench marks along the Yellowstone River.

The splendid assistance and cooperation of the members of the 

party is deeply appreciated. The merchants and inhabitants of the 

region, through their friendly cooperation, were of material aid during the field work. The writer wishes to acknowledge the assistance 

of H. D. Miser, under whose direction the survey was made, and of 

A. A. Baker, who organized the, party in 1929 and has given many 

valuable suggestions during the preparation of this report. He 

wishes also to express his appreciation to the Director of the Geological Survey for permission to submit this report, in essentially its

* Dobbin, C E., and Thorn, W. T., Jr., Oil possibilities in southeastern Montana: 

U. S. Geol. Survey Press Notice, January 1921.

B Thorn1 , W. T., Jr., and Dobbin, C. E., Stratigraphy of Cretaceous-Eocene transition 

beds in eastern Montana and the Dakotas: Geol. Soc. America, Bull., vol. 35, pp. 

481-506, 1924. Thoin, W. T., Jr., The relation of deep-seated faults to the surface 

structural features of central Montana: Am. Assoc. Petroleum Geologists Bull., vol. 

7, pp. 1-13, 1923.

6 Rowe, J. P., Montana coal and lignite deposits: Montana Uhiv; Bull. 37, Geol. 

ser. 2, 1906. . . :

7 Collier, A. J., and Smith, C. D., The Miles City coal field, Mont.: U. S. Geol.; Survey 

Bull. 341, pp. 36-61, 1908. :
47

present form, to Princeton University as part of a dissertation for 

the degree of doctor of philosophy.

Land surveys. All of the area included in the Rosebud field has 

been subdivided by surveys of the General Land Office. Some of 

the townships were surveyed between 1878 and 1891, the remainder 

between 1900 and 1913. During this later period resurveys and retracements were made in several of the townships that had been 

surveyed prior to 1891. Most of the corners established by the 

later surveys have remained undisturbed, but few of the corners 

established by the earlier surveys can be found. The section lines 

shown on the map that are based on these older surveys may therefore be somewhat in error.

Magnetic declination. The normal magnetic declination in this 

field is between 16°30" and 17°30' to the east. In the course of planetable mapping that involved triangulation for control and orientation, a notable departure from the normal declination was found to 

prevail in the northeast quarter of T. 4 N., R. 48 E., but the investigation was not extended into the adjoining townships. The declination at about 20 points in the northeast quarter of this township was 

determined, the readings were plotted, and the isogonic lines which 

were drawn through points of equal declination were found to trend 

north-northeast. The declination decreases from 16°30' in the northr 

central part of the township to 14° in the northeastern part. An 

explanation for this declination was not found in the surface features or rocks of the area. Clinker, which abounds in portions of 

the coal field, commonly attracts the compass- needle, but there is 

none within several miles of the northeast quarter of the township 

here described. About 150 miles farther west Knappen and Moulton 8 have noted compass deflections of as much as 7° and attribute 

them to magnetite grains in the tuffaceous beds of the Lance and 

Judith River formations.

GEOGRAPHY

LAND FEATURES

The Rosebud coal field lies within the portion of the Great Plains 

province described by Fenneman 9 as the Missouri Plateau unglaciated section. The characteristic surface features of the field are 

much-dissected plateaulike uplands, terraces, and badlands.

The uplands are confined to the southern part of the field and to 

the Tongue River-Rosebud Creek divide, which passes northward

8 Knappen, R. S., and Moulton, G. F., Geology and mineral resources of parts of 

Carbon, Big Horn, 1'ellowstone, and Stillwater Counties, Mont.: U. S. Geol. Survey Bull. 

 822, p. 2, 1930.

8 Fenneman, N. M., Physiographic divisions of the Unite.d States: Assoc. Am. Geographers Annals, vol. 18, no. 4, p. 277, 1928.
'48 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

nearly across the west-central part of the field. They are covered 

with grass and trees, which increase their contrast with the lower 

treeless country, much of which contains badlands. The uplands are 

irregular in outline, their borders being intricately crenulated by 

reentrant valleys and spurs. Buttes are common along their margins. 

Among the most conspicuous ones are the Rosebud Buttes, in sec. 19, 

T. 5 N., R. 43 E., which are completely isolated from the upland 

area and rise 300 feet above the surrounding country. The descent 

from the uplands toward the valleys is usually steep near the uplands but flattens to irregular dissected slopes that merge with the 

valley bottoms.

The northeastern part of the field contains rather narrow valleys 

and low but rugged interstream divides. The divide between the 

Tongue River and Pumpkin Creek is sharp, and the adjacent valleys 

on both sides of the divide are intricately dissected and contain large 

areas of badlands. The divide between the Tongue and Yellowstone 

Rivers separates two distinct types of topography. The slope toward 

the Tongue River is steep and cut into badlands, but the slope toward 

the Yellowstone is gradual and covered by grass or trees.

The flood plain of the Yellowstone River is in places 2 miles or 

more wide and is bordered by a succession of gravel-covered benches 

which occupy a belt 4 miles wide on the south side of the river. 

Similar benches extend from the Yellowstone up the valleys of the 

Tongue River and Rosebud Creek and also occur along Pumpkin 

Creek, a tributary of the Tongue River. -The flood plain of Rosebud 

Creek is about half a mile wide, and that of the Tongue River is 

about three-quarters of a mile wide. Pumpkin Creek has a meandering course in a rather narrow valley, with rough country on both 

sides.

Altitudes above sea level are shown at various places on plate 11, 

to give a general idea of the topography and relief. The highest 

points lie west of Rosebud Creek in sees. 19 and 30, T. 2 N., R. 42 

E., where the altitude is between 3,425 and 3,475 feet. The lowest 

country is along the Yellowstone River, which is about 2,400 feet 

above sea level. The maximum relief in the field is about 1,075 feet, 

though no township has a relief of over 600 feet.

DRAINAGE AND WATER SUPPLY

The Yellowstone River, which forms part of the north boundary 

of the field, is the largest stream in the region. It heads in Yellowstone National Park and flows east and north across Montana to 

join the Missouri River near the North Dakota-Montana State line. 

As most of the water in the river is derived from the mountains to 

the west, the flow of water is largely independent of local climatic
BOSEBUD COAL FIELD, MONTANA 49

conditions, and the river offers a, reliable supply of water for irrigating the bottom land in its valley. From early pioneer days theYellowstone Valley has been an important route of travel and the 

river a source of water supply for livestock and domestic use. The 

water is generally turbid, except in dry seasons. The gradient of the 

Yellowstone River in the area mapped is about 3.7 feet to the mile. 

The stream-gaging record of the Yellowstone at Miles City in 1923 10 

shows a maximum discharge of 53,300 second-feet in June and a 

minimum of 1,800 second-feet in December. Records of the Yellowstone at Intake, Mont., which is about 100 miles below Miles City, 

for the period 1903 to 1928,11 show a maximum discharge of 159,000 

second-feet June 21, 1921, and a minimum of 1,200 second-feet 

December 6 to 8,1922, and January 6 and 7,1923.

The Tongue River is the largest tributary of the Yellowstone River 

that crosses the Rosebud field. It heads in the Big Horn Mountains 

in northern Wyoming, flows northeastward, and empties into the 

Yellowstone River at Miles City, Mont. It is a clear stream except 

at high stages. During the spring, when its volume is tremendously 

increased by melting snow in the mountains and by rainfall, it 

becomes a treacherous river, cutting into its soft banks, scouring deep 

holes in its channel, and at times overflowing its banks and doing 

considerable damage in the fertile alluvial flats. It is from 200 to 

300 feet wide and has a fall of about 7.7 feet to the mile. A Government gaging station at Decker, Mont., 65 miles south of the field, 

measured the discharge of the Tongue River between April and 

September 1928. During this period of 6 months, the maximum discharge was 3,730 second-feet in May, and the minimum was 210 

second-feet in August. At low-water stages the river can be forded 

with a car where there is a solid bottom. At many places along its 

course water is diverted for irrigating the bottom lands. In 1914 

a concrete dam was built across the river in sec. 16, T. 2 N., R. 45 E., 

but during an excessively dry year there is insufficient water to irrigate all the land that is normally supplied from the reservoir.

Rosebud Creek heads in the uplands known as the Rosebud and 

Wolf Mountains, in the eastern part of the Crow Indian Reservation, 

and flows in a general northeasterly direction until it enters the area, 

whence it flows north and a little west until it joins the Yellowstone 

River near Rosebud. The water is turbid but potable throughout the 

summer. The stream is confined to a narrow channel in the valley 

alluvium, which is rarely over 20 feet wide and 10 feet deep. It is 

from 2 to 5 feet deep, and its gradient is about 13 feet to the mile.

10 Surface water supply of the United States, 1928, pt. 6: U. S. Geol. Survey WaterSupply Paper 666, p. 83, 1931.

11 Idem, p. 84. Surface water supply of the United States, 1923, pt. 6 : U. S. Geol. 

Survey Water-Supply Paper 566, p. 124, 1927.
50 . CONTiUBUlriONS TO ECONOMIC GEOLOGY, 1934-36

Pumpkin Creek, a stream about 60 miles long, flows through the 

extreme eastern part of the Rosebud coal field and joins the Tongue 

River about 2 miles north of this area. As its source of supply is 

principally surface run-off, it does not carry water during prolonged 

dry seasons.

The smaller tributaries of the Yellowstone River that carry the 

surface run-off in the north-central part of the area are Sweeney, 

Graveyard, and Moon Creeks. Sweeney Creek, slightly larger than 

the other two, is about 18 miles in length.

There are several flowing artesian wells in the Yellowstone -Valley. 

The Lott well, at Hathaway, is reported to be 460 feet deep and the 

water rises 6 feet above the surface; another water horizon was struck 

at 250 feet, and from it the water rose within 14 feet of the surface. 

Two other flowing wells have been sunk in the vicinity of Hathaway 

one in the NW% sec. 22 and one in the Ny2 sec. 20, T. 6 N.,, 

R. 44 E. There are a few flowing wells in the vicinity of Rosebud, 

and several on the north side of the Yellowstone. Artesian waterbearing beds have been encountered at Miles City at depths of 140 and 

425 to 525 feet, but some of the wells in the immediate vicinity of that 

place no longer flow because of the large consumption and the drawdown produced by rapid pumping.

In the Tongue River Valley two wells at depths of about 365 and 

385 feet yield flows of water at the S-H ranch, in the NW% sec. 31, 

T. 3 N., R. 46 E. The initial head of water in the deeper well is 

reported to have been 25 feet above the surface, and there has been 

no appreciable decline in head since they were drilled in 1914. 

Flowing wells have been obtained both up and down the river from 

this place.

There are no flowing wells along Rosebud Creek in this field, but 

at the Bean ranch, in the NWi/4 sec. 8, T. 1 N., R. 43 E., a drilled 

well yields a small flow. Renick 12 reports that in a drilled well 570 

feet deep in sec. 8, T. 5 N., R. 42 E., the water rises to 3 feet below 

the surface.

Shallow dug wells yield sufficient water for domestic supply over 

most of the area. Water from the Lebo shale member is in general 

highly mineralized and unfit for drinking. Numerous springs issue 

from the base of the clinker where erosion has cut sharp valleys into 

it and also from the sides of valleys cut into the gravel benches in 

the Yellowstone Valley. Alkaline waters issue from springs and 

seeps along the contact of the Tongue River and Lebo shale members 

of the Fort Union formation. A small spring at locality 123, in 

sec. 4, T. 2 N., R. 44 E. (see pi. 11), issues from the Terret coal bed.

12 Renick, B. C., Geology and ground-water resources of central and southern Rosebud 

County, Mont.: U. S. Geol. Survey Water-Supply Paper 600, p. 93, 1929.
ROSEBUD COAL FIELD, MONTANA 51

As a whole, springs are not significant as a source of water supply 

in this field, as they are neither large nor of constant flow. The 

ground-water resources in the part of this field that lies in Rosebud 

County have been discussed in detail by Renick.18

TIMBER, CULTURE, AND SETTLEMENT

A fair growth of western yellow pine and jumper is present on 

the divide between Rosebud Creek and the Tongue River, on the high 

land in T. 2 K, R. 42 E., and on the southern part of the divide 

between the Tongue River and Pumpkin Creek. The timber is almost exclusively confined to the high clinker-capped areas and to 

the steep slopes below the clinker. A sawmill in sec. 7, T. 3 N., 

R. 45 E., provides some lumber for local consumption. It is interesting to note that the trees seem to thrive only on the sandy Tongue 

River member of the Fort Union formation. (See pi. 5, A, B.) 

Very little timber grows on the Tullock member of the Lance formation, which is also rather sandy. The Tullock member is at a lower 

.altitude and does not have the rough, rocky slopes of the Tongue River 

member. Sparse growths of cottonwood, ash, ash-leaved maple, and 

buffaloberry trees are found along the major stream courses.

Several species of sagebrush and cactus are abundant. Spanish 

bayonet, greasewood, Russian thistle, and three-leaved sumac are 

rather common. Buffalo grass and spear grass are the more common 

monocotyledons.

Farming is principally confined to the bottom lands along the 

Yellowstone and Tongue Rivers and Rosebud Creek. Alfalfa and 

grain for forage are the chief crops. There is some dry farming 

on the divides and in the Sweeney Creek Valley. The rainfall is 

not sufficient for successful farming except in unusual years. The 

country is naturally adapted for grazing, which is the principal 

industry in this area.

Rosebud is the largest town in the Rosebud coal field. The census 

of 1930 reports 351 inhabitants in the Rosebud district. The small 

.settlement of Hathaway has a store, post office, and school. Miles 

City, which is at the junction of the Tongue and Yellowstone Rivers, 

outside the area of this report, is the trade center of a large part of 

this area. It is served by two transcontinental railroads the Northern Pacific Railway and the Chicago, Milwaukee, St. Paul & Pacific 

Railroad and had a population in 1930 of 7,175. Settlement is more 

dense along the Yellowstone River, Rosebud Creek, and the Tongue 

River, but although ranches are rather sparsely located over the 

entire area there are about 175 that are inhabited.

13 Renick. B. C., op. cit.
52 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

ROUTES OF TRAVEL

The transcontinental route of the Northern Pacific Railway follows 

the south bank of the Yellowstone Eiver and that of the Chicago, 

Milwaukee, St. Paul & Pacific Railroad follows the north bank. A 

branch line of the Northern Pacific runs south to Colstrip, a coalmining camp that lies about 3 miles west of the southwest corner of 

the Rosebud coal field. Construction work on the proposed line of 

the North & South Railroad, which was to follow the Tongue River 

from Miles City, Mont., to Sheridan, Wyo., stopped in 1923 and has 

not been resumed.

Several graded roads and numerous secondary roads provide access 

by automobile to many parts of the Rosebud coal field. United 

States Highway No. 10, also called the " Yellowstone Highway ", 

follows the south side of the Yellowstone River and is an important 

tourist route. This highway is all gravel-surfaced and partly oiled 

between Miles City and Forsyth. A graded road follows the east 

side of the Tongue River from Miles City across the Rosebud coal 

field and continues southward to Ashland and Sheridan. A graded, 

gravel-surfaced road in the valley of Pumpkin Creek joins the 

Tongue River road about 2 miles north of the Rosebud coal field. 

The Pumpkin Creek road is an important stage route between Miles 

City and Volborg, Broadus, and other points. The area along Rosebud Creek is served by a graded road that runs in the bottom of the 

valley. About 6 miles south of Rosebud the road forks, one fork 

leading to Forsyth, which is 10 miles distant, and the other to Rosebud. From this fork, about 6 miles south of Rosebud, the road has 

been graveled to both Forsyth and Rosebud; it is also graveled 

southward from the forks to a point about midway across the area. 

In the southern part of the field it again forks; the east, fork crosses 

the divide and follows Alfalfa Creek to the Tongue River and thence 

goes to Ashland; the other fork continues up Rosebud Creek, with 

forks leading to Ashland and Colstrip. A graded road from Rosebud traverses the Rosebud Buttes, but the grading ends about a mile 

south of the buttes. Grading was continued up the Sweeney Creek 

road in 1929 to the north line of T. 4 N., R. 44 E. A graded road 

begins in sec. 21, T. 3 N., R. 45 E., extends northeastward through 

the upper drainage basin of Moon Creek, and joins United States 

Highway No. 10 in the lower part of the Moon Creek Valley. A 

road from Hathaway leads up Graveyard Creek to its head. A 

wagon road along the Tongue River-Rosebud Creek divide and other 

roads leading to the various ranches in the area are frequently 

traveled.
U. S. GEOLOGICAL SURVEY BULLETIN 847 PLATE 5

.-I. TYPICAL TOPOGRAPHY OF THE TONGUE RIVER MEMBER OF MIL FORT UNION 

FORMATION, EJ/2 SEC. 16, T. 5 N., R. 45 E., MONT.

The clinker formed by the burning of the Burley coal bed caps the ridge and the butte in the foreground 

The greater abundance of trees on the clinker-covered summits and on the steep slopes is characteristic.

B. CONTACT OF THE TONGUE RIVER AND LERO MEMBERS OF THE FORT UNION 

FORMATION NEAR THE WEST QUARTER CORNER OF SEC. 3, T. 5 N., R. 44 E.

The somber-colored shale of the Lebo member in the foreground forms badlands; the overlying lightercolored beds in the distance are Tongue River. The clinker formed by the burning of the Burley coal 

bed caps the ridge.
U. S. GEOLOGICAL SURVEY BULLETIN" 847 PLATE 6

A. VIEW LOOKING NORTH ACROSS THE TONGUE RIVER VALLEY FROM THE SWH.

SEC. 27, T. 4 N., R. 47 E. 

Showing the wide valley of the Tongue Hiver and outcrops of the Tullock member of the Lance formation.

li. BENCH AT THE TOP OK THE TULLOCK MEMBER OF THE LANCE FORMATION,

SEC. 10, T. 5 N., R. 42 E.

Formed by stripping of the Lebo. The valley of Rosebud Creek appears in the background.
ROSEBUD COAL FIELD, MONTANA ;. ; . 531

STRATIGRAPHY

The rocks that crop out in the Rosebud coal field belong to the 

Fort Union and Lance formations, with the exception of the Pleistocene gravel and recent alluvium along1 the streams. The Fort 

Union formation is of early Tertiary (Eocene) age, but the age of" 

the underlying Lance formation has long been in controversy. Since 

the decision in 1914 by the Geological Survey to refer the Lance tentatively to the Tertiary, there has been considerable paleontologic 

and structural evidence which seems to warrant placing at least part 

of the Lance in the Cretaceous period. In this paper, however, the 

assignment heretofore adopted by the Geological Survey will be 

used, insamuch as studies of the age of the Lance are still in progress. 

The Lance formation has been subdivided into a lower member, the 

Hell Creek, and an upper member, the Tullock. The Fort Union 

formation is divided into the Lebo shale member (lower) and the 

Tongue River member (upper). The Tongue River member is the 

principal coal-bearing series in the field. Pleistocene gravel covers 

a series of benches in Yellowstone Valley and occurs to a lesser extent 

in other parts of the field. Alluvium in the Yellowstone, Tongue, 

and Rosebud Valleys is shown on plate 11 (in pocket).

TERTIARY (?) SYSTEM 

LANCE FORMATION

The Lance formation was divided by Rog'ers and Lee 14 into two 

parts an upper coal-bearing member, called the Tullock, and a 

lower, undifferentiated portion. The lower member was later named 

" Hell Creek " by Thorn and Dobbin.15 The areal mapping of these 

members was extended by Dobbin 16 eastward from the Tullock Creek 

field across the Forsyth coal field to the western boundary of the 

Rosebud coal field. Inasmuch as the division into two members had 

already been carried to the western boundary of the Rosebud coal 

field, the same division was extended into this field, though, as 

explained below, the division was difficult to make east of Rosebud 

Creek.

HELL CREEK MEMBER

The Hell Creek member crops out in the northwest corner of the 

Rosebud coal field, mostly in the lower part of the Rosebud Creek

14 Rogers, G. S., and Lee, Wallace, Geology of the Tullock Creek coal field, Rosebud and 

Big Horn Counties, Mont. : U. S. Geol. Survey Bull. 749, pp. 19-34, 1923.

" Thom, W. T., Jr., and Dobbin, C. E., Stratigraphy of Cretaceous-Eocene transition 

beds in eastern Montana and the Dakotas : Geol. Soc. America Bull., vol. 35, pp. 491-492, 

1924.

10 Dobbin, C. E., The Forsyth coal field, Rosebud, Treasure, and Big Horn Counties, 

Mont.: U. S. Geol. Survey Bull. 812, pi. 7, 1929. 

692 36 2
54 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

Valley, where about 300 feet of the member is revealed. It is probably present slightly below the surface in the lower parts of the 

Yellowstone and Tongue River Valleys. The upper part of the 

Hell Creek member as exposed in the Rosebud Creek Valley does 

not differ in topographic expression from the lower part of the overlying Tullock member of the Lance formation.

The upper part of the Hell Creek member in the Rosebud field 

does not contain great thicknesses of somber-colored clay and shale, 

such as occur in the member at its type.locality on Hell Creek, in 

northern Garfield County. Oil the contrary, it is composed of lightcolored sandy shale with a greenish-yellow tint and massive beds of 

white to light-tan sandstones. In the southern part of T. 5 N., R. 

42 E., a slight difference in color between the Hell Creek and Tullock 

members can be noticed from a distance.

In the Tullock Creek coal field, where the Lance was divided 

into two members, the difference between them is distinct, but it 

becomes less and less distinct as they are traced eastward. In the 

Forsyth coal field the base of the Wright coal bed is mapped as the 

top of the Hell Creek member. The base of this same coal bed is 

also mapped as the top of the Hell Creek member, on the west side 

of Rosebud Creek in the Rosebud field. But on the east side of Rosebud Creek, in T. 6 N., R. 42 E., the Wright coal bed, becomes.discontinuous and finally disappears. Also, in this township the lithology 

of the Hell Creek member changes markedly from alternating beds 

of sandstone and shale to massive cross-bedded sandstones. These 

massive sandstones, which appear in the upper part of the Hell Creek 

member, are indistinguishable from the sandstones in the lower part 

of the Tullock member. These similar lithologic features persist 

north and east from this township, and in consequence it is necessary

to draw there an arbitrary boundary between the Hell Creek and 

Tullock. If the contact in these directions were projected from the 

horizon of the Wright coal with a dip that accords with the regional 

dip of the strata, it would place the top of the Hell Creek member 

about 30 feet above the Yellowstone River, but inasmuch as there 

is no change in lithology upon which to base a separation of the 

Hell Creek and Tullock members, the thickness of the Tullock is 

arbitrarily increased to include these additional strata. Consequently, the contact is shown on the map as crossing the Yellowstone 

River a mile below the town of Rosebud.

TULLOCK MEMBER

The Tullock member forms the surface of much of the northern 

part of the Rosebud area. It crops out in the Yellowstone Valley but 

is partly concealed there by extensive gravel deposits. It crops out 

also in the valleys of the Tongue River (pi. 6, A) and Rosebud and
EOSEBUD COAL FIELD, MONTANA 55

Pumpkin Creeks, extending southward slightly beyond the south 

line of T. 3 N.

The Tullock is composed of sandstone and shale, with a predominance of sandstone. The sandstones are light yellow, evenly bedded, 

;and rarely massive. Two or locally three coal beds occur in the 

upper 100 feet; the most persistent bed is about TO feet below the top.

A detailed section of this member was measured in the northwestern part of the field, where it is 264 feet thick. In the Tullock Creek 

iield, which lies to the west, this member is from 290 to 300 feet thick. 

In regard to the lower boundary; Rogers and Lee 17 write:

The base of the Tullock member is considered to be the base of coal bed 

A, the lowest in the Lance formation in this field. Bed A is fairly persistent 

through the western and central parts of the field and is generally thicker than 

18 inches in these districts. * * * In much of the district east of Sarpy

Creek [that is, in the eastern part of the field] coal bed A is absent, but bed

 C, which is 35 feet higher, is persistent. In this district, however, for the sake 

of uniformity, the base of the Tullock member was mapped at the horizon of 

!bed A.

In the Forsyth coal field, according to Dobbin,18 the Tullock 

.member is between 240 and 270 feet thick, and the base of the member 

is placed at the base of the Wright coal bed.

Where the Wright bed is present in the Rosebud coal field, it is 

taken as the basal bed of the Tullock member. It corresponds to the 

bed of the same name in the Forsyth coal field and probably to 

bed C in the eastern part of the Tullock Creek coal field. In the 

Rosebud and Forsyth coal fields the Wright bed is generally a persistent marker, but variable in coal content, except east of Rosebud 

Creek. Here it is discontinuous and pinches out in the southern part 

of T. 6 N., R. 42 E. Along the Yellowstone River in T. 6 N., Rs. 

43 and 44 E., slightly over 300 feet of strata are included in the 

Tullock member, because there is no horizon in the lower part at 

which a contact can be consistently drawn.

In the Rosebud Valley the top of the Tullock is marked in places 

by a resistant sandstone bed from 2 to 10 feet thick, which produces 

a bench. (See pi. 6, B.} In the western half of the field the Big 

Dirty coal bed, at the base of the overlying Lebo shale member, is 

persistent, and its base was mapped as the top of the Tullock. East 

of the Rosebud Creek-Tongue River divide the lithology of the upper 

part of the Tullock differs from that on the west side. East of, the

 divide the Big Dirty coal bed is not very persistent, and the thin 

cross-bedded sandstones, which have a slight topographic expression 

at the top of the Tullock west of the divide, are not present. Also,

17 Rogers, G. S., and Lee, Wallace, Geology of the Tullock Creek coal field, Rosebud 

and Big Horn Counties, Mont.: TJ. S. Geol. Survey Bull. 749, pp. 30-31. 1923.

18 Dobbin, C. E., The Forsyth coal field, Rosebud, Treasure, and Big Horn Counties, 

Mont.: U. S. Geol. Survey Bull. 812, pp. 10-12, J929.
56 . CONTRIBUTIONS .TO. ECONOMIC GEOLOGY, 1934-36

the middle and lower parts of the Tullock are still lithologically distinguishable from the Lebo shale east of the divide, but in the eastern 

part of the area the transition is so gradual that any contact linebetween the Tullock and the Lebo has to be drawn quite arbitrarily.

Fossil plants were collected from a sandstone in the Tullock 

member 50 feet below the Big Dirty coal bed, in the SW1/^ sec.. 

12, T. 5 N., R. 43 E.

In the NW14 sec. 33, T. 6 N., R. 42 E., a large block of sandstone 

float, probably from a bed near the base of the Tullock, contained 

many reptilian and fish fragments. Crocodilian vertebrae, turtle 

plates, and garpike (Lepid'osteius) scales were very abundant in this 

sandstone block and are not uncommon in the Lance elsewhere.

Section of the Tullock member of the Lance formation in sec. 15, T. 5 N.t

R. 42 E.

Lebo shale member of the Fort Union formation. 

Tullock member of the Lance formation: Feet 

Sandstone, brown, in places forming rim rock_______ 5 

Shale, tan, sandy___ __________________ 13

Shale, gray, clay; concretionary layer at base 1 foot thick_ 10 

Sandstone, with interbedcled tan clay____________ 6 

Clay, gray __ ____ _ 9

Sandstone, with interbedded white clay, capped by 6

inches of gray carbonaceous shale_____________ 11 

Coal_____1_________________________ 3 

Sandstone, cream-colored, with interbedded light-gray

shale______________________________ 14 

Shale, gray, carbonaceous_ _______________ 5

Coal______________-________________ 1 

Sandstone, white, with interbedded clay__________ 14 

Coal; gray carbonaceous shale above and below___ 1 

Sandstone, with interbedded white clay_________ 18% 

Shale, brown__________ __________._______ %

Sandstone, light-colored, with interbedcled clay_____ 2 

Shale, brown, carbonaceous- ____ _________ 1 

Sandstone, cream-colored, shaly___________ 3

Shale, brown, arid coal____________________ 1 

Sandstone _ '. 16 

Shale, tan, sandy________________________ 16 

Shale, brown, with streaks of coal__________ ____ 1

Sandstone, white, soft _ 8 

Clay, gray_____ ___ ________________ 9

Shale, brown, and coal__.__________________:_ 3 

Sandstone, white to tan, with interbedded sandy shale 49 

Coal; brown shale above and below____________ 1 

Sandstone, cream-colored, with layer of hard brown

sandstone 2 feet thick near top_____________ 40

Coal, Wright bed_______________________ %-3

Hell Creek member of the Lance formation. 

264
ROSEBUD COAL FIELD, MONTANA 57

A section of the upper 78 feet of the Tullock, measured in T. 5 N., 

R. 44 E., is given on page 59.

TERTIARY SYSTEM

FORT UNION FORMATION

The Fort Union formation can be easily separated into two members on lithologic differences. The dark shale of the Lebo, which is 

the lower member, presents considerable contrast to the overlying 

yellow sandy Tongue River member. The contact between the two 

is not everywhere sharp but may be transitional through a zone of 

20 to 40 feet vertically.

LEBO SHALE MEMBER

Occurrence and character. The Lebo shale member forms a large 

part of the surface of the Rosebud field east of Tongue River and 

occupies an irregular strip about 4 miles wide on the west side of 

the Tongue River Valley. It crops out, on both sides of the Rosebud 

and Pumpkin Greek Valleys and also in the valleys of creeks tributary to the Yellowstone River, such as Sweeney, Graveyard, and 

Moon Creeks. In the Yellowstone Valley the Lebo shale member 

is partly covered by terrace gravel.

The Lebo shale is only loosely consolidated and is subject to rapid 

erosion. Where conditions are such that rapid removal of soft 

material may take place, badlands are formed. Smooth, rounded 

mounds of somber-colored shale, resembling haystacks in their general outline, are often produced by erosion of the Lebo shale. It is 

the author's opinion that considerable material, especially in the 

Lebo, is removed in suspension from below the surface that is, percolating water carries with it the finer clay and silt particles. The 

result of this washing out of material is apparent from the small 

funnel-shaped depressions and tunnels developed in badland areas.

The Lebo shale member is composed of somber-colored shale beds, 

with lenses of gray and yellow sandstone. There are many ironstone concretion zones, ranging in thickness from an inch or two to 

a foot. The following sections show the lithology of the member. 

The first section is incomplete, but the second one includes a partial 

section of the members above and below the Lebo.

Section of the Lebo shale member of the Fort Union formation in the 

sec. 28, T. 3 N., R. 43 E.

Ft. in.

Unrecorded beds at top of member______________ 80± 

Sandstone, yellow________________________ 8 

Ironstone concretion bed_____________________ 2 

Shale, light yellow and gray___________________ 17 

Ironstone concretion bed_____________________ 3
58 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

Section of the Lebo shale member of the Fort Union formation in the SE.%

sec. 28, T. 8 N., R. 48 E Continued. Ft. in. 

Shale, gray____________________________ 5 2. 

Shale, dark____________________________ 6 

Shale, gray__^__________________________ 6 

Shale, black________________.__________ 6; 

Shale, grayl______,____________________ 19 

Coal______________________,________ 8'- 

Shale, gray _________________________ 9

Shale, black, with thin coal lenses_____-________ 6 

Shale, gray _ ______________________ 3

Ironstone concretion bed____________________ 1 

Shale, gray.___________________________ 5 

Ironstone concretion bed_____________________ 3

Shale, gray __________ __________ 3 

Coal, impure (Big Dir'ty bed)_________________ 2 6 

Tullock member of Lance formation. 

167±

Section of the Lebo shale member of the Fort Union formation, with partial 

sections of overlying and underlying beds, m the NEy± sec. 1, T. 5 N., R. 44 

E., beginning at locality 290 and extending northwest to Graveyard Creek

Tongue River member of Fort Union formation: Ft. in. 

Clinker (Burley bed)__-_______________ 10 

Clay shale, gray_____________________ 4 

Bone_______________________________ 1 2 

Coal _____________________________ 10 

Shale, sandy, partly concealed______________ 23 

Sandstone, massive, fine-grained, cross-bedded, yellow

to white__________________________ 38 

Shale, sandy, gray______ ____________ 23

Shale, yellow, calcareous, sandy ____________ 3

Sandstone, massive, white to yellow_________ 105

208

Lebo shale member of Fort Union formation:

Shale, somber-colored; contains ironstone concretions- 42 

Sandstone, soft, buff; contains concretions______ 21 

Shale_____________________________ 29 8 

Coal, bony_ _________ _ _________ T

Shale _______4_____________________ 13 

Sandstone___:____________ _______ 5'

Coal and carbonaceous shale_______________ 1 

Shale; contains ironstone concretions _ ___ 19 

Shale, carbonaceous, with streaks of coal______ 3 

Shale____________________________ 3 

Bone_______________ _____________

Shale; contains ironstone concretions_________ 13 

Coal, impure__________________ _____

Shale, somber-colored_________'___________ 2

Coal________________ __ _ ____ 

Shale, somber-colored__-_________ _____ 18 

Coal, impure_;_____________________ 1
ROSEBUD COAL FIELD, MONTANA 59

Section of the Lebo shale member of the Fort Union formation, etc., in the

sec. 1, T. 5 N., R. 44 ^. Continued.

Lebo shale member of Fort Union formation Continued. Ft. in. 

Shale ____________________________ 7 

Coal, impure _______________________ 9 

Shale___________________________ 14 

Bone and impure coal______________ ___ 2 

Shale, somber-colored _________________ 3

Total Lebo shale member_______________ 194

Tullock member of the Lance formation:

Fine-grained sandstone and light-gray shale ___ 5

Shale _____________________________ 3

Coal, impure_________________ ___ 7

Sandstone, with thin beds of shale___________ 21 8

Coal_______________________1____ 5

Shale_______________________ 2

Bony coal and shale___________ __ 2

Shale_____________________________ 17

Sandstone, massive, buff_________________ 10

Coal_____________________________ 4

Sandstone and shale_______________:___ 10

Coal, bony _ _ ___ 1

Sandstone, fine-grained, yellow to buff_________ 5

78 

The Lebo is variable in thickness. It reaches its maximum thickness in the central part of the area, where it is from 190 to 220 feet 

thick, but the average thickness is about 170 feet. This slight variation in thickness, however, has no significance, because the lower 

boundary in particular cannot be placed on a bed or stratum that is 

continuous over even a large part of the area. The Big Dirty coal 

bed is mapped as the basal bed of the Lebo in the western part of the 

area. In the Kosebud Creek Valley the difference in lithology between the Lebo shale and the underlying Tullock member makes 

the boundary easy to locate, but in the Tongue River Valley the 

change from predominantly shaly beds to more sandy beds is one of 

gradual transition. Here the Big Dirty coal bed cannot be located 

with certainty, for several beds of similar character exist. The base 

of a coal and shale bed that resembles the Big Dirty was therefore 

mapped as the base of the Lebo. Including this bed, the Lebo in the 

Tongue Eiver Valley is about 200 feet thick. In the Pumpkin Creek 

Valley the coal beds are lenticular and the change in lithology is 

transitional through a thick zone, so there is no persistent horizon at 

which a contact can be drawn.

The top of the Lebo is not sharply defined, although there is a distinct change in lithology within a vertical distance of 25 or 30 feet. 

The somber-colored shale of the Lebo member grades upward into
60 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 193 4-3 6

the lighter-colored interbedded sandstone and shale of the Tongue 

River member (pi. 5, B}. The most striking difference between the 

two members is the change in color. Locally a calcareous bed, about 

1 foot thick, is present where the strata change from sandstone to 

shale. This calcareous bed is more resistant to erosion than the 

beds above and below and forms an inconspicuous bench. It may be 

that this calcareous bed was formed by the leaching of calcium carbonate from the overlying beds, the soluble material being carried 

downward by meteoric waters and precipitated when further movement was retarded by the shale.

Correlation eastward. In the Ekalaka lignite field 19 the Tongue 

River member of the Fort Union formation is underlain by the 

Lance formation, which is composed of two members the Ludlow 

lignitic member (upper) and the Hell Creek member (lower). 

(See pi. 9.) In the Rosebud field the Lebo shale member of the 

Fort Union formation and the Tullock member of the Lance formation become more and more alike in lithology as these members are 

traced eastward, until it becomes impracticable to separate them. 

Thorn and Dobbin 20 have correlated these two members with the 

Ludlow lignitic member, which is in accord with the lithologic evidence in the Rosebud coal field, except that the Tongue River-Lebo 

contact apparently is rising eastward, so that the Ludlow may also 

include strata equivalent in age to the lower part of the Tongue 

River member of the Rosebud field: The report by Parker and 

Andrews 21 on the Mizpah coal field, which lies between the Rosebud 

and Ekalaka coal fields, may give additional information on these 

correlations. Thorn and Dobbin 22 state that " east of the Powder 

River-O'Fallon Creek divide and along the Cedar Creek anticline it 

[Tullock member] is still recognizable, though thinner and lithologically more like the underlying Hell Creek member and overlying 

Lebo shale ", but the writer believes that a lithologic distinction between the Lebo and Tullock members cannot be carried eastward 

beyond the Rosebud coal field.

In the Miles City coal field 23 the Tullock and Lebo members were 

undifferentiated, both of them being included in the lower member of 

the Fort Union formation. The relation of the members of the Fort 

Union and Lance formations mapped in the Rosebud field to the 

upper and lower members of the Fort Union section in the Miles City

19 Bauer, C. M., The Ekalaka lignite field, southeastern Montana: U. S. Geol. Survey 

Bull. 751, p. 236, 1924.

20 Thorn, W. T., Jr., and Dobbin, C. E., Stratigraphy of Cretaceous-Eocene transition 

beds in eastern Montana and the Dakotas : GeoL.Soc. America Bull., vol. 35, p. 492, 1924.

21 Parker, F. S., and Andrews, D. A., The Mizpah coal field, Custer County, Mont, (in 

preparation). 

. z" Thorn, W. T., Jr., and Dobbin, C. E., op. cit., p. 492.

28 Collier, A. J., and Smith, C. D., The Miles City coal field, Mont.: U. S. Geol. Survey 

Bull. 341, pp. 38-43, 1909.
ROSEBUD COAL F-IELD, MONTANA 61

field, which includes 250 feet of Lance strata, is shown in plate 9. 

The base of the Lebo member as mapped in the Rosebud coal field 

corresponds to coal bed C in the Miles City coal field. Thorn and 

Dobbin also,24 in a regional stratigraphic study, have placed the base 

of the Lebo shale member at coal bed C in the Miles City field.

TONGUE EIVER MEMBER

The Tongue River member of the Fort Union formation is exposed 

over about one-third of the area of the Rosebud coal field. It crops 

out on the Rosebud Creek-Tongue River and Tongue River-Pumpkin 

Creek divides and in the high region in the southwestern part of the 

field. This member contains the most valuable coal beds in this field, 

many of which have burned along their outcrops and formed thick 

clinkers. The clinker is more resistant to erosion than the rocks 

above or below, and consequently, where present, it has influenced the 

topographic expression of the member. The clinker commonly forms 

the resistant rim above steep slopes and caps buttes and ridges (pi. 

5, A). Areas covered by clinker are shown on plate 11 (in pocket).

The Tongue River member is composed mainly of yellow sandstones, with beds of sandy shale, carbonaceous shale, and coal. 

There are a few rather lenticular, massive sandstone beds. The 

greater part of the member has been eroded, as the maximum thickness now present in the area is 400 feet. Bass 25 states, in regard to 

the thickness of the Tongue River member in the Ashland coal field:

Although the total thickness of 1,600 feet applies to the westernmost part 

of the field, and 1,150 feet to the easternmost part, the decrease in thickness is 

believed not to take place uniformly, but at least a considerable part of it 

apparently occurs in the easternmost part of R. 47 E. From that locality eastward the lower part of the member thins rapidly.

The total thickness of the Tongue River member in the northward 

extension of the Sheridan coal field is estimated by Baker 20 to be 

between 1,626 and 1,780 feet. The lower part of the member is 

gradational for 25 or 30 feet into the Lebo shale, but otherwise the 

change is marked. Along Cow Creek in T. 3 N., R. 45 E., the base 

of the Tongue River member has been placed arbitrarily: it was 

drawn at the same horizon rather than shifted vertically to follow 

the local transitions from sandstone to shale.

Fossil plants were collected at several localities from clinkered 

sandstones above the Terret and Burley coal beds.

24 Thorn, W. T., Jr., and Dobbin, C. E., op. cit., p. 494.

28 Bass, N. W., The Ashland coal field, Rosebud, Powder River, and Custer Counties, 

Mont. : U. S. Geol. Survey Bull. 831, p. 35, 1932.

20 Baker, A. A., The northward extension of the Sheridan coal field, Big Horn and. 

Rosebud Counties, Mont.: U. S. Geol. Survey Bull. 806, p. 27, 1929.
62 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36 

Section of part of the Tongue River member of the Fort Union formation

Sec. 24, T. 2 N., R. 42 E.

Ft. in.

Clinker_______________________________ 20

Ash of Rosebud coal bed________________ 2

Sandstone, soft, massive.___________________ 35

Ash of McKay coal bed____________________ 1

Clay shale, buff and white___________________ 22 8

Sandstone, shaly, with thin coal beds___________ 58

Shale, sandy _________________________ 21

Shale, carbonaceous, with streaks of coal__________ 1 6

Shale, changing to sandstone in lower part______ 11 4

Coal_________________________________ 1 4

Shale_______________________________ 34

Coal; Terret zone__..___________________ 4 8

Sandstone, massive _____________________ 14

Coal; Terret zone_________________________ 1 11 

Sandstone, massive, white, containing bed of ironstone

concretions _ __________________ 17

. Coal_________________________________ 11

Sandstone and clayey sandstone____._________ 25

Coal; Burley bed; top eroded_______________ S+

NW*4 sec. 7, T. 2 N., R. 43 E. .

Burley bed.

Sandstone and shale ______ ____________ 55

Coal_________________________________ 2

Brown-shale parting ______________________ 1

Coal _______________________________ 7

Shale, brown, carbonaceous. _ _ __ 6

Sandstone and shale ______________________ 20

Sandstone, hard, concretionary ________ 2

Sandstone and shale ______'.___________-______ 22

Shale, gray _ ________________:._ 11

Shale, brown ' 6

Coal________________________________ 4

Brown-shale parting. ___ 1

Coal________________________________ 2

Shale, brown to gray _ ________ 3 3

Coal________________________________ 8

Bone ________________________________ 1

Coal_____________________:__________- 4

Shale, dark gray, and brown__________________ 2 1

Sandstone, buff, and shale, gray_______________ 10

Shale, brown; carbonaceous streaks __ __ 1 6

Sandstone, with some shale_________________ _ 21 

Lebo shale member. 

	378 4

Section of part of the Tongue River member of the Fort Union formation at 

locality 450, sec. 18, T. 3 N., R. 45 E.

Ft. in.

Clinker_______________________________ 20+ 

Ash of Terret coal bed-_________________ 1

. Shale and sandstone __________________ 26
ROSEBUD COAL FIELD, MONTANA 63

Section of part of'the Tongue River member of the Fort Union formation at

locality 450, seo. 18, T, 3 N., R. 45 E. Continued. Ft. in.

Sandstone, calcareous ___________________ 3 6

Shale and sandstone_____________________ 27 6

Shale, brown___________________________ 4

Coal; Bnrley bed________________________ 1 5

Shale, brown, with some fine yellow powder_______ 1 6

Sandstone, buff, and shale_________________ 33

Shale, light gray_________________________ 1

Coal________________________________, 3

Sandstone and gray shale; sandstone predominant____ 16 6

Coal, dirty____________________________ 2

Coal (in Trial Creek coal zone)-_____________ 1 5

Sandstone and shale______ _ _____ __ 30 

Lebo shale member. 

	163 7

Section of part of Vhe Tongue River member of the Fort Union formation at

locality 80, sec. 34, T. 2 N., R. 48 E. Ft. in.

Clinker________._____________________ 20

Ash bed (of Knoblock (?) bed of the Ashland field) 2

Concealed __________________,_________ 17

Sandstone, with some ironstone concretions______ 20

Sandstone and shale, interbedded______________ 46

Coal________________________________ 2 3

Sandstone __ ____..______________ 2

Shale, gray_________________:_________ 10

Coal, bone, and shale____________ ___ __ 1 6

Shale, gray___________________________ 9 6

Sandstone, hard_____________________ __ 2 6

Sandstone, gray to white, with some shale___ 8 6

Coal________________________________ 6

Sandstone, gray to white, with some gray shale_ 29 6

Coal _______________________________ 3

Shale, brown and gray__ ___ ____ 1 3

Coal __^______________________________ 2 1

Shale, gray, finely laminated- 9 6

Sandstone, gray to white, cross-bedded..____________ 28 6

Concealed, probably sandstone in lower part___ 14

Coal; Terret bed_________________________ 5

Shale, hard, brown, sandy______________ __ 6

Concealed _______|_____________________ 16

Sandstone, friable, massive______________ __ 4 6

Shale, gray, and concealed slope_______________ 33

Shale, black, carbonaceous__ _ ___ __ 3

Coal; Burley bed_:______________________ . 6 2

Clay, gritty _____ _ _ 3

292 6

Section of part of tJie Tongue River member of the Fort Union formation, "beginning at locality 681, in the SE.y* sec. 7, T. 3 N., R. 49 E.

Ft. in. 

Clinker ; Flowers bed______ _______ ____ 15

Sandstone, light yellow, shaly____________ 35
64 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

Section of part of the Tongue River member of the Fort Union formation

in the SE1/^ sec. 7, T. 3 N.,.R. 49 E Continued, 

Coal _1_______________________________ 8 

Sandstone, light yellow, shaly________________ 26 

Shale, gray__________:______:___________ 8 

Shale, brown_________________________ 1 

Shale, gray________________________ _ 4 

Coal, fairly persistent________________________ 6

Shale, brown ___!__._______.______________ 1 

Shale, gray_________________________ 3

Shale, carbonaceous____________________ 1 2 

Coal, impure, and shale___________________ 1 7 

Shale, sandy___________________________ 28 

Cbal ________;_______________________ 4 

Shale, gray.__________________________ 2

Shale, sandy, light yellow___________________ 28 

Shale, light gray_________________________.._. 5

Sandstone, brown______:__________________ 3

Shale, sandy, light yellow____'._______________________ 16

Shale, carbonaceous, with streaks of coal________ 1 

Coal ________________________________. 1 5 

Shale, sandy, light yellow___________________ 10 

Sandstone, brown__________________________ 1 

Lebo shale member. 

192 8

TERTIARY (?) AND QUATERNARY DEPOSITS 

TERRACE GRAVEL.

The terraces along the Yellowstone Kiver are better developed than 

those in the smaller stream valleys in this field and consequently were 

studied in greater detail. Twelve terraces, some as far as 8 miles 

south of the river, were distinguished on the south side of the Yellowstone Valley. -These terraces are designated on plate 11 .by letters 

A for the lowest (youngest) terrace and L for the highest (oldest). 

Generalized intervals between the terraces in the Yellowstone Valley 

are as follows :

Feet

Yellowstone River to A terrace____________ _ _ 70 

A terrace to B terrace -_ ___ _ __ '-'- 45 

B terrace to C terrace____________________________ 50

C terrace to D terrace__________ _ _______ _ 80

D terrace to E terrace___________ ____________ 100

E terrace to F terrace________-___ _ __ __ 50 

F terrace to G terrace_________ ___ _ _ 40

G terrace to H terrace ___ ___ __ _______ 40

H terrace to I terrace___________ 25

I terrace to J terrace_________ __ _ _ 70 

J terrace to K terrace__________________.______ 90

K terrace to L terrace.._ __ _ _ ___ _ 125

785
KOSEBUD COAL FIELD, MONTANA 65

The broadest terrace (D), in T. 6 N., Rs. 42 and 43 E., is about 245 

feet above the Yellowstone River; terrace C, about 165 feet above the 

river, is also well defined.

Elsewhere than in the Yellowstone Valley data on terraces were 

obtained only incidentally to the coal mapping and are consequently 

incomplete. The correlations shown on plate 11 are therefore tentative and subject to revision. Seven terraces were recognized in the 

Pumpkin Creek Valley, the -lower five of which correspond to those 

mapped by Bass 2T in an area adjoining on the south. Five or more 

terraces are present in the Tongue River Valley but are dissected and 

discontinuous in many places. Many terrace remnants occur in the 

Rosebud Creek Valley, but most of them are not shown on plate 11.

Alden,28 on the basis of physiographic relations, correlates gravel 

deposits near Glendive, which are between TOO and 800 feet above

the Yellowstone River, with the Flaxville gravel, of Miocene or 

Pliocene age. If dissection of the Flaxville Plain did not begin 

until early Pleistocene time, then the terraces below the Flaxville 

are Pleistocene (or younger). A small remnant of a gravel-covered 

terrace 700 feet above the Yellowstone River in the Forsyth coal 

field may correspond to the Flaxville Plain, according to Dobbin. 29 

In the Rosebud field the highest terrace (L) is about 785 feet above 

the. Yellowstone, so it is tentatively correlated as a remnant of the 

Flaxville also. Furthermore, the L.terrace was .found only in the 

southeast quarter of T. 5 N., R. 44 E., and occurs on the divide, instead of on the sides of valleys like the lower terraces. Remnants of 

the K terrace were found only in the same area as the L terrace, and 

possibly it too should be grouped with the pre-Pleistocene terraces, 

but ibecause it occurs below and on both sides of the divide, it is 

grouped with the lower terraces. Inasmuch as no fossils were found 

in any of the terraces, the age classification of the higher terraces 

is tentative.

A large variety of igneous rocks from granitic to basic are found 

in the gravel of all the terraces. Quartzite is very abundant, and 

a few limestone pebbles 2 inches or less in diameter and one 6-inch 

cobble were noticed. Most of the igneous and quartzite pebbles were 

probably derived from the mountains far to the west and south, laid 

down on a plain above the present surface, and later reworked and 

gradually let down to their present position.

The terraces along the Yellowstone are made up almost entirely 

of foreign pebbles and cobbles, derived from igneous rocks and

27 Bass, N. W., The Ashland coal field, Rosebud, Powder River, and Custer Counties, 

Mont. : U. S. Geol. Survey Bull. 831, pp. 44-47, 1932.

28 Alden W. C., Physiographic development of the northern Great Plains: Geol. Soc. 

America Bull., vol. 35, no. 2, pp. 402-403, 1924.

29 Dobbin, C. E., The Forsyth coal field, Rosebud, Treasure, and Big Horn Counties, 

Mont.: U. S. Geol. Survey Bull. 812, p. 22, 1929.
66 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

quartzites, whereas the terraces in some of the tributary valleys contain considerable material derived from local sources, especially 

clinker fragments. Several of the terraces, particularly the higher 

ones, contain moss agates. . .,

The size of the material in the terraces varies laterally, along, the 

same terrace, as well as between different terraces, from fine sand 

to boulders 6 inches in diameter. Pebbles half an inch to 1 inch 

in diameter are common.

The gravel seems to be thicker in the terraces 300 feet or less 

above the stream beds. At the gravel pit near the airport north 

of Miles City the gravel in a terrace 290 feet above the Yellowstone 

is about 50 feet thick. At several places within the Rosebud area 

the gravel in the terraces less than 300 feet above the Yellowstone 

is 30 feet thick. The terraces higher than 300 feet above the river 

commonly have only a thin covering of gravel.

ALLUVIUM

The alluvial silt, sand, and gravel along the Yellowstone and 

Tongue Rivers and Rosebud Creek are the most recent deposits 

jn the Rosebud coal field. As shown on plate 11, the belt of alluvium is about half a mile wide along Rosebud Creek, three-fourths 

of a mile wide along the Tongue River, and from 1 to 3 miles udde 

along the Yellowstone River, but it is cut into small tracts by the 

meandering of these streams. Alluvium is present also along Pumpkin Creek and many of the other smaller streams, but it is of smaller 

extent and less distinct than in the areas just mentioned. Although 

fine sand and silt are predominant, the alluvium is not the same in 

all places, its composition being dependent in part upon the local

source rocks from which it is derived. For example, the alluvium

in the Yellowstone Valley contains a noticeable amount of gravel, 

which is derived from the Pleistocene gravel terraces, whereas the 

alluvium in the Rosebud Creek and Tongue River Valleys contains 

a noticeable amount of clinker in areas near a source of clinker 

supply. The alluvial flats and bottom lands along the three major 

streams form some of the best farm land in the area. Alfalfa is 

the most common crop, but where the land is irrigated a variety of 

crops are grown.

STRUCTURE

RELATIONS AND CHARACTER

The strata in this field are nearly flat-lying. Almost everywhere 

the dips are so slight that the attitude of the beds can be determined 

only by accurate instrumental readings over areas several miles in 

extent. Coal beds constitute the most readily traceable horizons for
KOSEBUD COAL FIELD, MONTANA 67

this work, but the intervals between them are not everywhere constant, and serious errors are introduced when altitudes on different 

coal beds: are reduced to a common datum plane.

The Forsyth, coal field, immediately west of this area; lies;'according to Dobbin,80 in a broad, shallow syncline which connects the 

Bull Mountain syncline and the Powder Kiver Basin. Bass 31 says 

that in the Ashland coal field, which adjoins the Rosebud coal field 

on the south,

The chief features * * * are a broad syncline plunging gradually northeastward, its axis following the Tongue River Valley, and a northwestwardtrending downfold that crosses the Tongue River syncline near Ashland. The 

Tongue River syncline constitutes the major syncline between the Black Hills 

uplift, far to the southeast, and the Porcupine dome, to the northwest near 

Forsyth. .

FIGURE 8. Structure map of the Rosebud coal field.

Figure 8 shows the attitude of the strata in the Rosebud field. The 

contour lines are drawn on the base of the Lebo member of the Fort 

Union formation, which is marked by the base of the Big Dirty 

coal bed in the western part of the field. In the northern part, where 

the Lebo has been removed by erosion, the base of the member has 

been restored. The contour interval is 50 feet. Most of the altitudes 

used in preparing the map were observed on coal beds. In the eastern 

part of the field the coal beds are very lenticular, so where possible 

the contact between the Tongue River and Lebo members was used as 

a supplementary datum. The strata rarely dip more than 1°. The

80 Dobbin, C. E., The Forsyth coal field, Rosebud, Treasure, and Big Horn Counties, 

Mont.: U. S. Geol. Survey Bull. 812, p. 22, 1929.

"Bass, N. W., The Ashland coal field, Rosebud, Powder River, and Custer Counties, 

Mont.: U. S. Geol. Survey Bull. 831, pp. 47-48, 1932.
68 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

few dips of 3° or more are all due to faulting or slumping, so far 

as could be ascertained.

The predominant .structural features of the area are the Tongue 

River syncline, whose axis follows the Tongue River Valley, trending 

northeastward from T. 3 N., R. 46 E., to T. 5 N., R. 47 E., and the 

;anticlinal nose that plunges southeastward from T. 5 N., R. .42 E., 

..toward the Tongue River. Both.limbs of the Tongue River syncline 

rise gradually, with numerous irregularities and undulations. Many 

of the undulations and depressions are too small to be shown on a 

sketch map. They do not have a definite system or pattern and are 

probably due to conditions of sedimentation and. later differential 

compaction. The anticlinal nose in the northwestern part of the area 

is the reflection of minor undulations far out on the flank of the Porcupine dome, which is 30 miles northwest of this area. The maximum 

structural relief in the Rosebud coal field is 250 feet.

NE-

_ .1-1 Terret cli'nker 

Terret clinker £ ^ijv

^Burley 

coal

Vertical scale 

50 o 100 Feet

Horizontal scale 

250 o 1,000 Feet

FIGURE 9. A typical fault in the Rosebud coal field, near the northwest corner of T. 3 N.,

R. 45 E.

FAULTS

Two small normal faults were mapped in and near the northwest

corner of T. 3 N., R. 45 E. (See pi. 11.) They are parallel, having a 

strike of N. 30° W., and are slightly offset. As the faults are concealed, their position is most easily determined by noting the vertical 

displacement of the Terret clinker, supplemented by tracing the 

Burley coal bed, below.

The more northerly fault, which is also the one that was traceable 

for the greater distance, was examined in detail. It has a maximum 

throw of 60 feet, with the downthrow on the southwest. Because 

of the throw and sequence of coal beds the Terret bed, which is 

generally burned, is nearly at the same horizon on the southwest 

side of the fault as the Burley bed on the northeast side of the 

fault. The actual fault plane was observed only at locality 223. 

This fault is of an unusual type, as shown in figure 9. Displacement 

appears to have occurred only on the downthrown side. A rise 

of about 3° SW. carries the displaced beds up to their normal posi-
U. S. GEOLOGICAL SURVEY BULLETIN' 847 PLATE 7

A. SUPERFICIALLY FOLDED COAL BED ON SWEENEY CREEK, SEW SEC. 27, T. 6 N.,

R. 43 E.

The contact between the overlying alluvium and the Tullock member of the Lance formation is indicated 

by a broken line. The stadia rod on the left is 13 feet high.

B. SUPERFICIAL FOLD EXPOSED ON COAL CREEK, SWJ4 SEC. 30, T. 6 N., R. 44 E.

The folded beds of the Tullock member are truncated by alluvium about 3 feet above the top of the

13-foot stadia rod.
U. S. GEOLOGICAL SUKVET BULLETIN" 847 PLATE 8

A. SUPERFICIAL FOLD I,\ \OL\1NU A COAL DEI) IN THE TULLOCK MEMHER OF 

THE LANCE FORMATION, SEC. 14, T. 4 N., R. 47 E.

The shale a few feet below the folded coal bed is not folded; part of the coal bed has been removed by 

erosion and is overlain by alluvium.

«. SLUMP liLOCK. OF STEEPLY DIPPING TONGUE RIVEH STRATA RESTING ON 

HORIZONTAL LEKO BEDS, SEC. 23, T. 3 N., R. 47 E.

The base of the 13-foot stadia rod is on the plane of movement, which is a bedding surface. (See fig. 10

for a diagram of the slump.)
ROSEBUD COAL FIELD, MONTANA 69

tion within 1,000 to 1,500 feet from the fault. It seems likely that 

the faulting took place before the burning of the Terret coal bed 

in the immediate vicinity of the fault, because the strata along part 

of the west or downthrown side of the fault are not baked or 

clinkered. The down-faulting at these places buried the coal, so 

that it could not get sufficient oxygen for burning. The more southerly of these two faults is poorly exposed, and little is known about 

it, but it is probably related and similar to the one just described.

In the NWV4 sec. 34, T. 6 N., R. 42 E., another fault of the same 

type has a throw of about 35 feet and strikes N. 10° W. The strata 

on the west side are downthrown and they dip toward the fault 

at a maximum angle of 3°. It is probable that there are several 

other faults in the area which are not shown on the map. In the 

SE% sec. 31, T. 4 N., R. 45 E., a dip of 3°30' was noticed, and a 

similar fault was suspected but could not be found. Differences 

in the altitude of the coal beds in the southern part of sec. 33, T. 

4 N., R. 44 E., suggest the possibility of a small concealed fault 

there.

The small throw and short linear extent of the faults suggest 

that they may not have a deep-seated origin. Inasmuch as they 

occur in loosely consolidated strata of continental origin, it seems 

quite likely that they may be due in some way to differential compaction of the underlying beds.

Faulting of the same type as here described has been noted by 

Rogers and Lee in the Tullock Creek coal field.82

Three small asymmetric folds, one so sharply folded that displacement has occurred, were found in the Rosebud field. The views 

in plate 7, A, Z?, and plate 8, A, will convey the detail and size of 

these folds more accurately than a written description. One of the 

folds is exposed in a cut bank of Sweeney Creek in the SEV4 sec. 

27, T. 6 N., R. 43 E.; another 3 miles to the east, in a cut bank of 

Coal Creek in the Ny2 sec. 31, T. 6 N., R. 44 E.; and the third, 25 

miles southeast of the other two, in a tributary valley of the Tongue 

River in the SWV4 sec. 14, T. 4 N., R. 47 E.

These folds occur in an area of flat-lying strata, where the regional 

dip is about 10 feet to the mile. They are 25 to 100 miles from areas 

of large folds or structural deformation. All the folds are in the 

Tullock member of the Lance formation, which, either as a whole or 

in part, is not competent to transmit a thrust for any great distance.

The outstanding features of these folds may be summarized as follows: (1) They do not persist with depth. A close examination of

32 Rogers, G. S., and Lee, Wallace, Geology of the Tullock Creek coal field, Rosebud 

and Big Horn Counties, Mont.: U. S. Geol. Survey Bull. 749, p. 52, 1932. 

692 36 3
70 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

plate 8, A, shows that about 4 feet of the shale below the coal bed 

is folded, but the rest of the shale, to the bed of the creek, is not 

folded. The crest of the folded coal bed has been eroded and then 

covered with alluvium; (2) all three of the folds occur in the bottoms of valleys and are only slightly above the beds of the streams; 

their trends are parallel to the valleys in which they occur; (3) 

alluvium, is present a few feet above each of the folds, but is not 

involved in the folding; (4) the pressure apparently has not come 

from the same direction in all the folds, for two of them are either 

asymmetric or overturned to the east and one is asymmetric in the 

opposite direction.

The writer has come to the conclusion that these folds are of 

surficial origin and are not connected with any regional deformation.

Jerret clinker "SW

surface

Terret clinker

FIGURE 10. Diagrammatic section of a slump in T. 3 N., R. 47 E., drawn to scale and 

normal to the plane of movement.

Although a search was made for evidence of some force that produced each individual fold, nothing of significance was found in their 

immediate vicinity. However, in the same general area an exposure 

of a slump revealed evidence which suggests a genetic relationship 

between slumping and surficial folds. The slump is in the southwest 

corner of sec. 13 and the northeast corner of sec. 23, T. 3 N., R. 47 E. 

In figure 10 the highest bed on the left is clinker of the Terret coal 

bed. Clinker from this same bed has moved down a vertical distance 

of 215 feet while moving a horizontal distance of 655 feet minus the 

amount of recession of the clinker escarpment since the slump began. 

The broken line indicating the plane of movement is drawn arbitrarily. A detailed view of the displaced block in the lower right 

corner of figure 10 is shown in plate 8, B. In this photograph the 

displaced block has moved from left to right. The beds dip 60° -toward their original position, that is, into the plane of movement. 

The base of the stadia rod is on the plane of movement, which coincides with a horizontal bedding plane and is not an old erosion surface. As the movement has been on a bedding plane, the strata above 

it must have been shoved up in front of the slump block and have
ROSEBUD COAL FIELD, MONTANA 71

produced a small superficial fold, which has since been removed by 

the erosion of Haddow Creek. If the movement was along a poorly 

lubricated surface, considerable drag would be expected, which might 

produce sharply overturned and ruptured folds, such as the one 

shown in plate 7, A. Such drag effect would also produce differential horizontal movement decreasing downward from the slump 

plane. Thus the superficial folds that occur in this field may be the 

result of slumping, acting in either of the two ways mentioned. The 

movement however may not have been of the same proportion and 

scale as that just illustrated but may have involved a much larger 

block which moved only a very short distance.

A landslide at a shale quarry in Cleveland, Ohio, that was. accompanied by buckling and anticlinal folding is described by Van 

Horn.83 He thought that vertical pressure was more effective than 

horizontal pressure in producing the folding. Bucher 34 describes 

some small folds near Cincinnati which he attributes to the pressure of flowing layers of shale beneath the fold, just as clay buckles 

or squeezes in the bottom of an excavation or in a coal mine. Another explanation 35 that has been offered for the origin of similar 

superficial folds is expansion caused by weathering and the action 

of meteoric waters. The superficial folding in the Kosebud field 

might be correlated with weathering action insofar as the location 

and character of the folds are concerned, for they occur in the bottoms of valleys with alluvium overlying them and they die out 

with depth, but the quantitative effectiveness of this process has not 

been tested. Glacial action has been advanced as the cause of other 

superficial folds but need not be considered here, as the Rosebud 

field lies outside the limits of any known ice sheet.

GEOMORPHOLOGY

In middle Tertiary time this region was probably an extensive 

plain of low relief, covered in many places by gravel. Regional 

uplift started cutting by the streams, followed by many interruptions in the erosion cycle. The successive terraces along the Yellowstone River and many of the other streams indicate several 

changes of baselevel or changes in gradient of the trunk streams. 

The Rosebud coal field was never covered by Pleistocene glaciers,

M Van Horn, F. R., Landslide accompanied by buckling and its relation to local anticlinal folds: Geol. Soc. America Bull., vol. 20, pp. 625-632, 1910.

M Bucher, W. H., The mechanical interpretation of Joints : Jour. Geology, yol. 29, no. 1, 

pp. 18-23, 1921. ' "

85 Campbell, M. K., Rock folds due to weathering: Jour. Geology, vol. 14, no. 8, 

pp. 718-721, 1906. Croneis, Carey, Geology of the Arkansas Paleozoic area, with especial reference to oil and gas possibilities: Arkansas Geol. Survey Bull. 3, p. 336, 1930. 

Woolnough, W. G., " Stone rolls" in the Bull! coal seam of New South Wales: Royal 

Soc. New South Wales Jour, and Proc., vol. 44, pp. 334-340, 1910; Pseudotectonic 

structures: Am. Assoc. Petroleum Geologists Bull., vol. 17, no. 9, pp. 1098-1106, 1933.
72 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

but the margin of the farthest advance of the continental ice sheet 

in late Pleistocene time passed about 80 miles north of this field 

and crossed the Yellowstone River about 100 miles below Miles 

City. The ice blocked the mouth of the Yellowstone, the major 

stream in this section of Montana, and doubtless affected the development of the present surface features of the Rosebud coal field. 

A discussion of the origin, history, and development of the stream 

terraces that occur in many parts of the Rosebud field is beyond 

the purpose of this report; a more detailed report on the Pleistocene 

terraces in southeastern Montana is being prepared. The terraces 

 and stream-worn gravel composed of material foreign to this region 

occur not only along the major streams but also along and at the 

heads of small streams, such as Sweeney, Graveyard, and Moon 

Creeks. Inasmuch as these small streams could never have transported the gravel from its original source in the mountains far 

to the west and south, the conclusion is reached that some of the 

material from an extensive Tertiary gravel-covered plain has been 

let down and forms part of the terrace deposits now present in this 

area. Erosion in the Rosebud field has removed this plain, which 

corresponds to either the Cypress Hills or the Flaxville Plain.

Many of the smaller streams have the apparently anomalous condition of a steep gradient combined with sharply meandering channels in alluvial valleys, for the streams are so heavily loaded with 

alluvial material that they are at grade, even though the gradient 

is steep.

The drainage pattern of the eastern part of Montana has several 

unusual features. The valleys of the Yellowstone, Tongue, and 

Powder Rivers and other streams are asymmetric, or, to express it 

in another way, the southeastward-flowing tributaries, of these 

streams are short in comparison with the tributaries flowing northwest. This same general relation is found in the Rosebud field. The 

southeast tributaries of the Tongue River, for instance, are about 

twice as long as the northwest tributaries. Another unusual feature 

in the regional drainage pattern is the change in the course of streams 

from northeast to northwest. Figure 7 will serve to illustrate these 

northwest bends of streams for example, the Powder River, the 

Tongue River, Rosebud Creek, and the Musselshell River. Similarly, 

Ash Creek, in the southeastern part of the Rosebud field, flows 

toward Pumpkin Creek until within 2 miles of it and then makes 

a turn of more than 90° and flows northwestward into the Tongue 

River. Although the headwaters of Ash Creek appear to have been 

tributary to Pumpkin Creek at one time, that time must have been 

back in the Pleistocene epoch, for there is no evidence of an ancient 

channel across the Ash Creek-Pumpkin Creek divide, and there are 

at least five terraces in the Pumpkin Creek Valley below this divide.
ROSEBUD COAL FIELD, MONTANA 73

If the upper part of Ash Creek once flowed into Pumpkin Creek, 

there has been between 110 and 150 feet of downcutting by Ash 

Creek since it became a tributary of the Tongue River. Still another example in the Rosebud field is Moon Creek, in T. 5 N., R. 46 

E.; which flows northeastward toward the Tongue River in its upper 

part but turns abruptly and flows northward and northwestward into 

the Yellowstone River.

The asymmetric form of valleys that trend northeast and the 

change in stream trends from northeast to northwest suggest that 

the region has been tilted, the southeastern part rising in relation 

to the northwestern part. At the time of tilting this region was 

probably one of low relief with mature streams, so that only a small 

amount of tilting was necessary to produce the anomalies now present. This tilting would increase the gradients of small streams that 

were flowing northwestward into larger streams that presumably 

drained northeastward and would decrease the gradients of the small 

streams that were flowing southeastward into the same larger 

streams. The advantage possessed by the northwestward-flowing 

tributaries over the southeastward-flowing tributaries would cause 

the divides between major streams trending northeast to shift gradually toward the southeast and thus develop the asymmetric valleys 

that now exist. The abrupt change in trend from northeast to northwest of several streams of various sizes may be due, in large part, to 

piracy, which resulted also from tilting. The cutting power of the 

streams that flowed northwestward would be increased by a northwestward tilt, whereas the major streams, which are presumed to 

have been flowing northeastward, would not have their gradients 

.affected, by such a tilt. Consequently, some of the northwestwardflowing streams would, by headward erosion, cut back until they 

captured the waters of some northeastward-flowing streams. Possibly some of the large streams were diverted from their channels 

as a direct result of tilting, but this would require either a large 

amount of tilting or an area of extremely low relief, or a combination 

of the two. An additional result of tilting toward the northwest 

would be the tendency for some of the small valleys to develop with 

a prevalent northw^st,,trend. The parallel northwest trend of the 

small valleys has been noted by Russell,38 but he ascribes a different 

origin to them.

COAL

GENERAL SECTION

As the strata in this field are nearly flat lying, the oldest coals 

occur in the lower areas and the youngest at greater altitudes. ExM Russell, W. L., Drainage alignment In the western Great Plains: Jour. Geology, 

vol. 37, no. 3, pp. 249-255, 1929.
74 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

cept for a few local lenses of coal less than 18 inches'thick in the 

Hell Creek member of the Lance, the lowest coal stratigraphically is 

the Wright bed, the base of which is at the contact of the Tullock and 

Hell Creek members of the Lance formation. The Tullock member 

contains several thin coal beds, most of which are in the upper 100 

feet. Coal in the lower part of the Tullock was mapped in T. 6 N., 

Rs. 42, 43, and 44 E.; T. 5 N., Rs. 48 and 49 E.; and T. 4 N., R. 47 E. 

The Big Dirty bed, at the base of the Lebo member of the Fort Union 

in the western part of the field, and local beds at the base of the Lebo 

in the eastern part of the field are of minor importance as a source 

of coal because of the impurity of the coal. Only at a relatively few 

places was the Big Dirty bed found to be of fair quality. The thickest and cleanest coal beds in this field are in the Tongue River member of the Fort Union formation. In this member the Buiiey and 

Terret coal beds are the two most important when both thickness and 

areal extent are considered. The Rosebud bed is the thickest coal 

bed in the field but is only of small lateral distribution in the southwestern part of the field.

The stratigraphic position of the coal beds in the Rosebud field 

and their relations to the coals of the Ashland, Forsyth, and Miles 

City fields are shown in plate.9. The coal beds present in these three 

adjoining fields extend into the Rosebud field, thus making correlation of beds among these four fields possible by actual tracing of the 

outcrops. The thickness of the principal coal beds of the Rosebud 

coal field and the average intervals between them are as follows:

Principal coal beds west of Tongue River in the Rosebud field

Tongue River member of the Fort Union formation: Feet

Coal, Rosebud bed___________________ 20

Interval ____________________________ 30

Coal, McKay bed _______1____________ 5

Interval_ ____________________ 145

Coal, Terret bed______________;_________ 12

Interval________________________ 50

Coal, Burley bed_______________________ 6

Interval _________________________ 50

Coal, in Trail Creek coal zone_______________ 2

Interval __________________________ 60

Lebo member of the Fort Union formation:

Interval, which, in T. 5 N., R. 46 E., and adjacent 

townships, contains coal from 1 to 2% feet thick 

in a discontinuous bed, 90 to 100 feet below the 

top of the Lebo____1_____________ 170-190 

Coal, Big Dirty bed____________________ 2% 

Tullock member of the Lance formation:

Interval, containing local coal beds principally in

upper 100 feet____________________ 270 

Coal, Wright bed_______________________ 2 

Hell Creek member of the Lance formation.
ROSEBUD COAL FIELD, MONTANA 75

Principal coal beds east of Tongue Rwer in the Rosebiid fteld

Tongue River member of the Fort Union formation: Feet 

Coal, Flowers -bed_____________________ 8 

Interval _________________________ 25-30 

Coal, Haddow bed______________________ 2-5 

Interval __________________________ 40-75 

Coal, Terret bed__l_____________ ____ __ 9 

Interval _____1___________ 25 

Coal, Foster bed_______________________ l-2y2

Interval __________________________ GO-90 

Lebo member of the Fort Union formation:

Interval _________________________ 200 

Coal_____________________________ 0-2 

Tullock member of the Lance formation:

Interval, containing local coal beds from 1 to 3 feet 

thick in the upper 100 feet and lower 90 feet___ 290

THE COAL BEDS

The position of the outcrops of the different coal beds is shown on 

plate 11. Most of the numbers along the outcrop lines indicate the 

locations where the coal beds were measured and refer to coal sections given in the township descriptions and in plates 12 to 21 and 

figures 12 to 32. Plate 10 shows two generalized sections of the coal 

beds of the Eosebud field, one extending north-northeastward and 

the other eastward across the field. The abrupt termination of the 

Eosebud, McKay, and Flowers beds is due to their removal by erosion. 

Information is lacking on the coals in the Lance formation in the 

southwestern part of the field because they are covered, but inasmuch 

as the coal beds are probably thin and at considerable depth below 

the surf ace, they are. not of economic value under present conditions.

The coal beds in the Tullock and Lebo members are thin and 

lenticular. Because of their lenticularity, their correlation is difficult and uncertain. Plate 11 shows some of these beds as continuous 

over many square miles of area, whereas in reality there are several 

discontinuous beds at slightly different stratigraphic horizons. On 

the graphic coal sections coal beds that may be discontinuous but 

occur at approximately the same stratigraphic horizon are also 

grouped. Figure 11, drawn from actual' coal-section measurements, 

illustrates graphically the lenticularity of the coal in the lower part 

of the Tullock member of the Lance formation. These sections were 

measured on practically a straight line of outcrop along the Yellowstone Eiver in T. 6 N., E. 43 E. From this figure it is evident that, 

unless the coal sections are measured at close intervals, erroneous 

correlations will be made. Partings in coal beds are often regarded 

as a criterion for correlation, but, as the figure illustrates, they are 

not infallible. The sandy parting present in the five center sections 

is equivalent to shale partings in the sections on the extreme left
76 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

and right. The rapid 

change of strata above 

and .below the coal beds 

is also illustrated by figure 11.

COALS OF THE TTJLLOCK 

MEMBER OF THE LANCE 

FORMATION

Wright bed. The 

Wright bed crops out only 

in the northwestern part 

of the field. At locality 

177 there is 3 feet of 

coal in this bed. At localities 7 and 163 it is 

about 2% feet thick. At 

five of the remaining ten 

localities where sections 

were taken, the coal is 

only slightly over 18 inches 

thick, and at the other 

five localities the Wright 

bed contains less than 18 

inches of coal. A thin 

but fairly persistent bed 

25 feet above the Wright 

was measured at three 

places. Only at locality 2 

does it contain 18 inches 

of coal. In the Forsyth 

field 87 the Wright bed is 

described as occurring at 

many places in two benches 

about 26 feet apart.

Coal beds in the lower 

part of the Tullock. 

Along the Yellowstone 

Eiver in parts of T. 6 N., 

Ks. 42, 43, and 44 E., 

several coal beds occur in 

the lower part of the 

Tullock member of the

a Dobbin, C. E., The Forsyth coal field, Rosebud, Treasure, and Big Horn Counties, 

Mont.: U. S.'Geol. Survey Bull. 812, p. 26, 1929.
U. S. GEOLOGICAL SUBVEY BULLETIN 847 PLATE U

T. 6 S., R. 42 E.

Northern extension

of the Sheridan

coal field, Montana. Ashland coal field

U. S. G. S. Bull. 806-B U. S. G. S. Bull. 831-B

-2.000 ^ ,

- 1,900

-1,800

-1.700

-1,600

-1,500

-1,400

-1.300

-1,200

-1,100

-1,000

- 900

- 800

M2

-

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Wall

Lower split of Wall

__ ^

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- 700

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Lay Creek

FlowersGoodale

Jerret

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Forsyth coal field 

U. S. G. S. Bull. 812-A

EXPLANATION

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- 400

- 300

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jrnedcoal Bone coal

Sawyer

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Lee

Western part of Ekalaka lignite field,

Rosebud coal field Miles C ty coal field Southeastern Montana

 

Rosebud . 

McKay

Stocker

Robinson

Burley

 

LEBO SHALE

FORT UNION

&^Dirty 

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MEMBEROF.g

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Bi| Dirty ^

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Rosebud coal field from text)

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STRATIGRAPHIC POSITION OF THE COAL BEDS IN THE ROSEBUD COAL FIELD AND THEIR CORRELATION

WITH PRINCIPAL COALS OF ADJOINING FIELDS.
ROSEBUD COAL FIELD, MONTANA 77

Lance formation. The thickest and most extensive of these beds 

has a maximum thickness of 4 feet 9 inches of coal and a 1%-inch 

parting at locality 196, in T. 6 N., R. 43 E. It thins rapidly westward and gradually eastward from this locality. (See fig. 11.)

In the central part of T. 4 N., K. 47 E., a coal zone between 200 

and 235 feet below the top of the Tullock member contains two coal 

beds 25 to 35 feet apart, which have a maximum thickness of about 

3% feet. The upper bed is generally dirty. The lower bed crops 

out at several places along the Tongue River; it contains about 3 

feet of fair coal.

In the northeastern part of the field coal was found at only two 

localities in the lower part of the Tullock member. At these outcrops, on Johnson and Pumpkin Creeks, the coal is about 2 feet 

thick.

Goal beds in the nipper pcurt of the Tullock. Coal in the upper 

100 feet of the Tullock member of the Lance formation occurs in 

many places in the Rosebud field. Most of the coal is of poor 

quality, and none of the beds are thick.

In the Rosebud Creek Valley the coal in the upper part of the 

Tullock member is 50 to 85 feet below the top. In T. 5 N., R. 42 E., 

three beds in this zone, 45, 60, and 85 feet from the top of the Tullock 

member, range in thickness from 1% feet or less to about 2^ feet. 

In T. 4 N., R. 43 E., a small drift mine has been operated for local 

supply at locality 157; the bed is 2 feet 10 inches thick and 75 

feet below the top of the Tullock member. At locality 28, in T. 

3 N., R. 42 E., there are two beds about 2 feet thick, 50 and 60 

feet below the top of the Tullock member. About a mile farther 

north, at locality 27, in T. 4 N., R. 43 E., one of these beds contains 

3 feet of coal, but still farther north and west it is less than 18 

inches thick.

In the Tongue River Valley and the lower part of the Pumpkin 

Creek Valley thin coal beds are present in the upper 100 feet of the 

Tullock member. The beds are generally 3 feet or less in thickness; 

beds 5 feet thick are of local extent. Over half of the coal is impure, because of thin, irregular lenses and layers of carbonaceous 

shale and bone.

COALS OF THE LEBO SHALE MEMBER OF THE FORT UNION

FORMATION

Big Dvrty bed. The coal bed at the base of the Lebo in the western part of the field is correlated with the Big Dirty bed of the 

Forsyth coal field.38 In the Rosebud Valley the Big Dirty bed can 

be traced easily. Where it does not contain coal its horizon is 

marked by a carbonaceous shale bed 3 to 4 feet thick. In the Tongue

88 Dobbin, C. E., op. cit., p. 26.
78 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

River Valley and eastward the bed;, is more discontinuous, and so 

the name " Big Dirty " is not used in that region.

The Big Dirty bed in this field is,.not as.thick as it is in the coal 

fields to the west, and it is of poor quality. Numerous sections of 

this bed were measured, but at only a few places is the coal clean 

enough to be used for a domestic fuel. It is predominantly a carbonaceous shale bed from 2 to 5 feet thick, in which there are thin seams 

of coal grading almost imperceptibly into the shale. At locality 

396, in T. 4 N., R. 46 E., the bed at the base of the Lebo contains 

5 feet 3 inches of slightly dirty coal with a parting of shale 1 inch 

thick. About half a mile south of this place, however, at locality 

400, the bed is more impure and does not contain Ii/2 feet of clean 

coal. In parts of the Rosebud Creek Valley a bed of shale and 

dirty coal occurs about 15 feet above the Big Dirty.

Bedi at the base of the Lebo in the eastern part of the field. A bed 

at the base of the Lebo in the Tongue River Valley and in part of 

the area east of this river is at the stratigraphic position of the Big 

Dirty bed and is similar to it but is discontinuous. The coal is 

generally dirty and unsuitable for mining.

Bed in the upper part of the Lebo. A discontinuous coal bed 90 

to 100 feet below the top of the Lebo member is mapped in the eastern part of T. 5 N., R. 46 E., and the western part of T. 5 N., R. 47 

E. The coal is usually dirty and ranges from about 1 to 3 feet in 

thickness. It is equivalent to bed D of the Miles City coal field.

Local beds in the Lebo. Local coal beds in the Lebo member are 

lenticular and impure and are thus not important as a probable 

source of coal. In the northeast corner of T. 5 N., R. 49 E., a bed 

about 3% feet thick, which is between 50 and 75 feet above the base 

of the Lebo, has burned along its outcrop and formed clinker. The

bed contains very little recoverable coal in this township.

In T. 4 N., R. 43 E., a local bed was mapped for a few miles; at 

locality 158 it contains 2 feet 8 inches of bony coal and 10 inches of 

clean coal. In T. 3 N., R. 47 E., a bed of coal in the Lebo has a 

maximum thickness of 1 foot 10 inches of clean coal.

COALS OF THE TONGUE RIVER MEMBER OF THE FORT UNION

FORMATION

Bed at the base of the Tongue River member. A thin coal bed is 

present at the base of the Tongue River member in T. 5 N., R. 46 E. 

On the west side of Moon Creek it is less than iy2 feet thick, and in 

the southeast corner of the township it has an average thickness of 

2 feet in an area of about 1 square mile.

Trail Creek ooal zone. Th& Trail Creek coal, named from Trail 

Creek, is a fairly persistent bed in T. 2 N., R. 44 E. West and north 

of this township, however, it pinches out, but other coal beds occur
BOSEBUD COAL FIELD, MONTANA 79

at nearly the same horizon and at lower horizons in the basal 60 feet 

of the Tongue River member. For convenience these coal beds are 

all grouped as the Trail Creek coal zone. The Trail Creek zone is 

restricted, to.the area between .Rosebud Creek and the Tongue River. 

In the northern part of. T- 2 N;, R. 43 E., it contains two beds from 

30 to 40 feet apart. The most persistent coal bed in the zone is 

generally about 50 feet below the Burley bed. The coal beds in the 

Trail Creek zone,range from iy2 feet or less to 3 3/£ feet in thickness.

Bwley< bed. The Burley bed is correlated with the bed of the 

same name in the Forsyth. and Ashland coal fields. It crops out only 

in that part of the Rosebud field lying west of the Tongue River. 

West of Rosebud Creek it is. 5 to S1/^ feet thick, but northward along 

the Tongue River-Rosebud Creek divide, it thins from 6 feet 2 

inches in the southern part of T. 2 N., R. 43 E., to 3 feet in the 

northeastern part of the same township and less than 2 feet in the 

western part of T. 3 N., R. 44 E., where it is difficult to trace. 

In the extreme southern part of T. 4.N., R. 45 E., a bed at the same 

horizon as the Burley begins to thicken rapidly toward the north. It 

is not certain that this bed is the same as the Burley, in the southern 

part of the field, but for the purpose of clarity it is designated by 

the same name. This bed reaches a maximum measured thickness 

of 9 feet 6 inches at locality 229, in sec. 12, T. 4 N., R. 44 E.; north 

of this locality it has burned along the outcrop and formed a thick 

clinker, which is correlated with bed E of the Miles City field. The 

Burley coal is clean and of good quality. This bed contains more 

coal than any other bed in the Rosebud field.

Foster bed. The Foster coal bed underlies a small area in the 

eastern part of T. 3 N., R. 47 E., and the western part of T. 3 N., 

R. 48 E. An interval of 28 feet between the Foster and Terret beds 

near the south line of these townships decreases to 16 feet 5 miles 

to the north. The Foster coal is usually in two beds from iy2 

to 5 feet apart; the coal in one or the other of the beds is generally 

between iy2 and 2,y2 feet thick.

Terret bed. The Terret coal bed, which is correlated with the 

Terret bed in the Ashland field, has burned along most of its outcrop 

and produced the clinker on the divide between Rosebud Creek and 

the Tongue River in this area. This bed averages 12 feet in thickness on the Rosebud-Tongue divide south of T. 4 N., and where 

unburned will yield valuable coal. A mile north of T. 3 N., Rs. 44 

and 45 E., it splits up into thin coal beds. Also, on the west side 

of Rosebud Creek it splits and thins to less than 18 inches of coal. 

The Terret bed is within a few feet of the same stratigraphic horizon 

as the Robinson bed in the Forsyth field.

On the east side of the Tongue River the Terret bed is present 

in the eastern part of T. "3 N^.R.. 47 E., and the southwestern part of
80 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

T. 3 N., R. 48 E. It has burned along most of the outcrop, but 

the clinker is partly obscured by clinker of higher beds. East of the 

Tongue River the Terret coal has a maximum measured thickness 

of 10 feet and an average thickness of 8 feet, except east of the middle 

of T. 3 N., R. 48 E., where it thins rapidly eastward and becomes 

less than 18 inches thick.

On the west side of the Tongue River.the Terret bed is 160 feet 

above the base of the Tongue River member; on the east side of the 

river the interval decreases to about 90 feet. This difference may 

possibly be due to a change in the stratigraphic position of the 

Tongue River-Lebo contact.

Haddow bed The Haddow coal bed is named from Haddow 

Creek, in T. 3 N., R. 47 E.; it occurs only near the head of this 

creek. The bed is of small areal extent and is about 2 feet thick, 

except in the extreme southeast corner of T. 3.N., R. 47 E., where 

it has a maximum thickness of 5% feet.

Flowers bed. The Flowers coal bed is the northern continuation 

of the Flowers-Goodale bed in the Ashland coal field. It is present 

in the southwestern part of T. 3 N., R. 48 E., and small outliers of. 

clinker remain in the extreme eastern part of T. 3 N., R. 47 E. The 

coal is between 7 and 8 feet thick and is extensively burned along 

the outcrop. The Flowers bed is 60 feet above the Terret bed in the 

western part of the township and 35 feet above in the eastern part; 

it is the uppermost coal bed in the Tongue River member in the area 

east of the Tongue River.

McKay and Rosebud coal beds. The McKay bed is about 145 feet 

above the Terret bed, and the Rosebud bed is 30 feet above the McKay. The McKay and Rosebud beds are the uppermost of the. series 

of coal beds present in this field and occur only in T. 2 N., K. 42 E. 

Here, however, the Rosebud bed, which is over 20 feet thick, and the 

McKay bed, which is 5 feet or more thick, have been largely removed 

by erosion and burning. These two beds extend into both the Forsyth and Ashland coal fields.

PHYSICAL AND CHEMICAL PROPERTIES

The coal in the Rosebud coal field is of subbituminous rank. The 

coal in the Tongue River member of the Fort Union formation is of 

good grade, but that occurring in lower members and formations is 

poorer. The coal is shiny black, has a conchoidal fracture, and disintegrates and loses moisture when exposed to the air. There were 

no operating mines from which unweathered samples could be procured in this field; consequently samples for analysis were not obtained. Analyses of coals from nearby fields will, however, serve 

as an index of the values to be expected in this field. In the following table of analyses form A represents the composition of the
ROSEBUD COAL FIELD, .MONTANA 81

sample as received in the laboratory, form B the theoretical composition after all moisture has been eliminated, and form C the composition after both ash and moisture are removed. All the analyses 

were made in the laboratory of the United States Bureau of Mines 

at Pittsburgh, Pa.

Analysis of coal from fields near the Rosebud field

Location

Colstrip, Mont., composite of 4 analyses, 

Rosebud bed, sec. 34, 

T. 2 N., R. 41 E. 

Miles City, Mont., average of 2 samples from 

Kircher bed. 

Sheridan, Wyo., composite of 12 analyses, 

Monarch bed. 

Scranton, N. Dak., sec. 

24, T. 131 N., R. 100 

W. 

Roundup, Mont., composite of 2 analyses, 

Roundup bed, sees. 

23-25, T. 8 N., R. 25 

E.

Laboratory no.

A19659..

6694 and 

5780.

25224.... 

A45697.. 

A31560..

60

f

!«4

6.6

16 

11.7 

21.6 

7.5

.a 

R 

1CO *S

£

A 

B 

C

A 

B 

C 

A 

B 

C 

A 

B 

C 

A 

B 

C

Proximate

3a

o

S

24.1 

29.6

23.8 

~41.~2 

"l3."2

<D

£Jj{ c8 -i-3 

*O Q

>

28.4 

37.4 

41.4

27.7 

39.3 

45 3

32.4 

42.5 

44.5 

24.8 

42.2 

47.9 

28.7 

33.1 

36.6

*fl «§1-°

PH

40.2 

53.0 

58.6

33.4 

47.4

54,7

40.5 

63.1 

55.6 

26.9 

45.8 

52.1 

49.8 

57.3 

63.4

 s

 <

7.3 

9.6

9.4 

13.3

3.3 

4.3

~7."I 

12.0

"8.1 

9.6

Ultimate

a 

o, 3

03

0.7 

1.0 

1.1

.7 

1.0 

1.1

.4 

.5 

.5 

1.4 

2.4 

2.8 

.6 

.6 

.6

a 

1

t

W

6.2 

4.7 

5.2

....

6.5 

5.1 

5.3 

7.2 

4.5 

6.1 

5.6 

4.8 

5.3

a 

.8 

S O

53.6 

70.6 

78.1

.....

55.3 

72.6 

75.8 

37.8 

64.3 

73.1 

62.6 

72.1 

79.8

§ M o is

%

0.7 

1.0 

1.1

....

.9 

.2 

.2 

.6 

.0 

.1 

.0 

.1 

.3

ao

sO

31.5 

13.1 

14.5

.....

33.7 

16.4 

17.1 

45.9 

15.8 

17.9 

22.0 

11.8 

13.0

Heating, 

value.

2 g

 a 

o

5,060 

6,644 

7,350

4,221 

5,992 

6,910 

6,213 

6,843 

7,154 

3,617 

6,160 

6,989 

6,011 

6,922 

7,661

 "" a

co a

sea "si

n*3 3 

«

9,090 

11,960 

13,230

7,598 

10, 786 

12, 437 

9,383 

12, 317 

12, 877 

6,610 

11,070 

12, 680 

10,820 

12, 460 

13, 790

The coal in the Tongue River member of the Fort Union formation in the Rosebud field probably is similar chemically to that at 

Colstrip, Mont. (no. A19659). The older coals should correspond 

more closely with those near Miles City, Mont. (nos. 5694 and 

5780). The difference in the chemical composition and properties 

in the coals from west to east may be seen by a comparison of the 

analyses of samples from Roundup, Colstrip, and Miles City, Mont., 

and Scranton, N. Dak.

COAL CLINKER

The coals in the Tongue River member of the Fort Union formation, especially the Terret, Rosebud, Flowers, and Burley beds, 

have burned along their outcrops, so that the overlying beds are 

baked and reddened. After the burning has extended in from the 

outcrop a few feet, the heat is transmitted to the overlying strata. 

The sandstones and shales overlying the burned coal are fused and 

baked for several tens of feet vertically. The exact distance is 

largely dependent upon the thickness of the coal bed and the 

cracks and openings available for oxygen to reach the burning 

coal and for gases to escape. Clinker 50 feet thick is not uncommon. The character of the clinker depends not only on the intensity of the heat but also on the kind of rock. For instance, a
82 CONTRIBUTIONS TO ECONOMIC . GEOLOGY, 3934-36

sandstone bed only a few feet above the burning coal may be 

only slightly altered, while a bed of shale or sandy shale above this 

may be fused. The beds below a burned coal bed appear to be 

unchanged. Spontaneous combustion seems to be the cause of most 

of the burning, although ignition may occasionally have been due 

directly or indirectly to lightning or human agency. Locally the 

ash bed of the Terret coal has been cemented by lime, forming a 

bed of hard white porous rock about a foot thick. The physical 

and chemical effects accompanying the formation of clinker are 

discussed more completely by Rogers.39

The limits of the clinker or baked rock on the surface are taken 

as an index of the extent of burning. As the Burley, Terret, Flowers, and Rosebud beds are extensively burned, the estimated limit 

of burning of these beds is shown on plate 11.

Many of the smaller coal beds are oxidized along their outcrop, 

but no clinker is formed. A bed of soft red sooty material a few 

inches thick may be all that remains at the outcrop of a 3-foot 

coal bed that has been oxidized. This slow oxidation does not extend in far from the outcrop and occurs more commonly in coal beds 

3 feet or less in thickness. There does not appear to be any accompanying change in the overlying or underlying strata. The ash 

from these oxidized beds is different from that at the base of the 

clinker. The oxidation of these thin coal beds probably never 

reached the kindling temperature. The oxidized -outcrop is indicated on the map in the same way as the burned outcrop.

QUANTITY OF COAL

In the accompanying table the estimated coal tonnage is given 

both by beds and by townships. In making these estimates, there 

were two important factors that could not be determined with, a fair 

degree of accuracy the extent to which the coal beds have been 

burned under cover, and the amount of coal contained in beds less 

than 3 feet thick. The first factor was determined as accurately as 

possible by a study of the field conditions, but drilling will be necessary for more precise information. The second factor is largely 

one of interpretation and affects the tonnage estimates of coal in 

the Lebo member of the Fort Union formation and the Tullock 

member of the Lance formation. The coal in these two members is

.extremely variable in thickness and purity; a bed which at one 

locality is 3 feet thick may not contain li/^ feet of clean coal half 

a mile away. In estimating the quantity of coal in these members,

. a minimum figure rather than a maximum was used. A maximum

89 Rogers, G. S., and Lee, Wallace, Geology of the Tullock Creek coal field, Rosebud and 

Big Horn Counties, Mont. : U. S. Geol. Survey Bull. 749, pp. 81-85, 1923. Rogers, G. S.. 

Baked, shale-a nds-; slag, formed by the--burning, of coal beds: U. S: Geol. ; Suuvey Prof. 

Paper 108, pp. 1-10, 1918.
ROSEBUD COAL FIELD, MONTANA 83

figure, which would include probable coal beds entirely concealed by 

cover, would increase the estimate several times. Such beds, however, are similar to those that are known from outcrop measurements and are not of much economic importance, although their 

aggregate quantity over large areas may run into millions of tons. 

For the townships in which coal in the Lebo and Tullock members 

does not crop out no estimate of the quantity of coal which they may 

contain is given.

Estimated quantity of coal in Rosebud field, by beds and toivnships, in millions

of tons

T. 6N., R. 42 E. (fractional) ..........

T. 5 N., R. 42 E........... ............

T. 4 N., R. 42 E..... ..................

T. 3 N., R. 42 E .... ................

T. 2 N., R. 42 E.. .....................

T. 6N., R. 43 E. (fractional)........ ..

T. 5 N., R. 43 E... ....................

T. 4 N., R. 43 E.. .....................

T. 3 N., R. 43 E......... ..............

T. 2 N., R. 43 E.... ...................

T. 6N., R. 44 E. (fractional)..........

T. 5 N., R. 44 E... ....................

T. 4 N., R. 44 E... ....................

T. 3 N., R. 44 E....... ................

T. 2N., R. 44 E... ....................

T. 5 N., R. 45 E.. .....................

T. 4 N., R. 45 E... ....................

T. 3 N., R. 45 E.. .....................

T. 2N., R. 45 E. (fractional)... .......

T. 5 N., R. 46 E... ....................

T. 4 N., R. 46 E.. .....................

T. 3 N., R. 46 E.......................

T. 5 N., R. 47 E.. .....................

T. 4 N., R. 47 E.. .....................

T. 3 N., R. 47 E.......................

T. 5 N., R. 48 E ....................

T. 4 N., R. 48 E... ....................

T. 3 N., R. 48 E. ......................

T. 5 N., R. 49 E.. .....................

T. 4 N., R. 49 E... ....................

T. 3 N., R. 49 E.. .....................

Fort Union formation .

Tongue River member

Rosebud

33

8 16

S?

W 

o

§

14

32

S3 n

o

fc

......

2

1

3

1

0

EH

1

32

3

85 

131

8 

4

2

49

315

£

1 

«

15

171

2 

2 

52

10

14 

46 

79 

4 

100 

7

502

Trail Ceek '

7

9 

1

28

8 

14 

36 

5 

2

3

113

Lebo

member

 d 

a <s

K. "8 >>a> £"°

51_o uT*

5

4 

5 

3

1 

10

1

1

9 

3

1

1 

2 

1 

3

3

1

49

Lance formation

Tullock 

member

o

CQ O

sl

o, 

a 

t>

10 

3 

4

10 

14

1 

3 

1 

2 

9 

6

8

71

lower Middle andTullock, including Wright

1 

20 

6

10

......

1

......

8 

......

1

1

53

 a 

1

i

34 

14 

22 

226 

10

22 

27 

112 

. 2 

11 

25 

' 145 

246 

9 

110 

11

12 

3 

2 

8 

11 

7 

13 

7 

69 

11 

1

1,171

' Includes "bed below Burley" in T. 5 N., R. 45 E., and "bed at base of Tongue River" in T. 5 N., R. 

46 E. 

»Flowers. 

1 Haddow.

The estimated quantity of coal in beds over 1% feet thick in the 

Eosebud coal field is 1,171,000,000 tons. Of this total about 85 percent is in the Tongue River member of the Fort Union formation
84 CONTRIBUTION'S TO ECONOMIC GEOLOGY, 1934-36

and 15 percent is in the Lebo member of the Fort Union formation 

and the Lance formation. Most of the 15 percent occurring in the 

Lebo member and the Lance formation is in beds between 1% and 3 

feet thick. Of the total estimated tonnage about 30 percent is in 

beds from 1% to 3 feet thick, and 70 percent is in beds over 3 feet 

thick.

OUTLOOK FOE DEVELOPMENT

There are no mines operating OIL a commercial scale in this field. 

Small amounts of coal are taken from a few small mines and open 

pits to supply fuel for local domestic use. At the Snyder mine, in 

the NEi/4 sec. 31, T. 2 N., R. 44 E., and the Haddow Creek mine, in 

the SW% sec. 32, T. 3 N., R. 48 E., the coal is taken out of open pits 

on the Terret bed. At the Pierson mine on the Rosebud bed, in the 

SW14 sec. 19, T. 2 N., R. 42 E., a few wagon loads of coal a year 

are taken from natural exposures in the banks of Pony Creek. A 

small drift has been opened in the Burley bed at locality 280, in the 

SE^4 sec. 35, T. 5 N., R. 45 E. Open-pit prospects on the Burley 

bed at localities 41,151,153, and 229 have supplied some coal.

In parts of the field that are some distance from the coal beds in 

the Tongue River member the coal in the Lance formation is used 

locally. At the Sand mine, at locality 15T, in the NW^ sec. 29, T. 

4 N., K. 43 E., two parallel drifts 30 feet apart have been run in 

about 75 feet on a coal bed which is about 3 feet thick. The small 

mines in coal beds in the Tullock member along the Yellowstone 

River have been abandoned for many years.

Mining on a commercial scale will probably be restricted to the 

beds in the Tongue River member, such as the Rosebud, Flowers, 

Terret, and Burley beds. Of these the Terret and Burley beds are 

of most importance in this field. The unburned Terret coal on the 

Rosebud Creek and Tongue River divide is under 100 feet or more 

of cover. Areas where the cover is 50 feet or less are small, so 

there is little opportunity for large-scale open-pit mining. The Terret bed in the NW% sec. 20, T. 3 N., R. 48 E., is overlain by 60 feet 

or less of cover; the coal is about 8 feet thick. In the northwestern 

part of T. 2 N., R. 42 E., the Burley bed is overlain by less than 50 

feet of cover over an area of 2 to 3 square miles; the coal is from 5 

to 8 feet thick. In T. 4 N., R. 45 E., the Burley bed, from 5 to 9 feet 

thick, underlies a considerable area, in most of which it' is overlain 

by more than 50 feet of cover. Small areas of the Burley bed, which 

are overlain by 50 feet or less of cover, are also indicated on plate 

11, in the western part of T. 2 N., R. 43 E., and the southern part of 

T. 5 N., R. 45 E.

The quantity of coal in the Rosebud field is not great enough to 

warrant construction at the present time of the transportation f acil-
ROSEBUD COAL FIELD, MONTANA 85

ities necessary for commercial production. The coal beds are neither 

as thick nor of as large horizontal extent as those of the adjoining 

Forsyth and Ashland coal fields, with which the Rosebud coal would 

have to compete. At Colstrip, Mont., in 1929, coal was being mined 

from an open cut at the rate of 4,000 tons a day for use in the locomotives of the Northern Pacific Railway. A total of 10,000,000 tons 

had been blocked out, which at that rate of production would take 

from 8 to 10 years to mine.

DETAILS BY TOWNSHIPS

In the following pages the area is described by townships, which 

are taken in order from north to south, beginning with the western 

tier of townships. The geography and geology are briefly discussed 

and details of the coal not given in the preceding pages are described. 

The locality numbers mentioned in the text are shown on plate 11 

.and are numbered consecutively, beginning in the northwest corner 

of the area and following up the drainage on the west side of Rosebud 

Creek and down the drainage on the east side, then following the 

other streams in a similar manner, progressing eastward across the 

field to the northeast corner. The sections of the coal beds measured 

at these localities are shown graphically in plates 12 to 21 and figures 

12 to 32.

T. 6 N., R. 4^ E- (fractional). A-succession of stream terraces covers all 

of the fractional part of T. 6 N., E. 42 B., south of the Yellowstone Blver. 

There are a few dry farms on the flat terraces, and the fertile soil produces

T. 6 N., R. 42 E.

Wright bed 

184

Local bed in lower Tullock

188 189 190

Ft. in. ssgl Ft- in191 192 

In. Ft. in. ,»Ft. in,

9

EXPLANATION

Bony coal Dirty 

coal

Carbonaceous Sandstone Clay

shale 

FIGURE 12. Sections of coal beds in T. 6 N., E. 42 E.

large crops in years of adequate rainfall. The broadest terrace stands about 

250 feet above the Yellowstone. The maximum relief is about 450 feet.

The Hell Creek member of the Lance formation crops out extensively in this 

township. It is overlain by the Tullock member of the Lance formation, 

692 36 4
86 COSTTEIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

which crops out in most of the eastern part of the township. The lower part 

of the Tullock contains some massive beds of sandstone and a few thin coal 

beds. The Tullock member is overlain by the Lebo shale member of the Fort 

Union formation in the southeast corner of the township. A belt of alluvium 

of irregular width borders the Yellowstone River and Rosebud Creek.

The Wright bed, at the base of the Tullock member of the Lance formation, 

contains 20 inches of coal, with a %-inch parting in the middle, at locality 

184. The bed is not traceable northward from this locality. A local bed below 

the Wright at locality 185 contains 20 inches of coal. A local coal bed in the 

lower part of the Tullock crops out in sees. 13, 14, and 24. Coal sections were 

measured at localities 188, 189, 190, 191, and 192; at three of these localities 

it contains less than 18 inches of coal. This bed is thin and through much 

of its extent is of poor quality. The Big Dirty bed, at the base of the Lebo, 

is present only in sec. 35. No sections were measured in this township, but, to 

judge from sections measured in the township adjoining on the south, the Big 

Dirty bed probably does not contain 18 inches of clean coal.

Coal for local consumption has been produced from a small drift mine on the 

local bed in the lower part of the Tullock member at locality 191, but this 

mine has been abandoned for some time.

T. 5 N., R. 42 E. Rosebud Creek flows northward almost through the center 

of T. 5 N., R. 42 E. With the exception of the West Fork of Rosebud Creek, 

the tributaries are small, but they cut deep valleys, which head in badlands of 

the Lebo member of the Fort Union. The Tongue River member of the Fort 

Union formation crops out in a small area in sees. 13 and 24. The Lebo member of the Fort Union crops out in the highlands in the eastern! part of the 

township. Over the rest of the township are beds belonging to the Tullock 

and Hell Creek members of the Lance formation. A section of the Tullock 

member measured in sec. 15 is given on page 56. Badlands are predominant, 

vegetation is scarce, grazing land is poor, and farming is restricted to the 

bottom lands along Rosebud Creek.

The township as a whole is poor in coal and does not contain beds worth 

mining on a commercial scale. All the beds are characterized by extreme 

variability in thickness and a low grade of coal. The Wright coal bed, at the 

base of the Tullock, was measured at localities 1, 3, 5, 7, 170,172, 173, 177, 178, 

and 182, It is nowhere over 3 feet in thickness and at some places is less than 

18 inches. At locality 177 a drift was opened on the Wright bed but is now 

abandoned. At the Lore mine, which is outside this township, in the NEi/4 

sec. 2, T. 5 N., R. 41 E., the Wright bed contains 2 feet 8 inches of clean coal. 

At locality 8 the Wright bed is less than 18 inches thick. A bed 25 feet above 

the Wright is fairly persistent and at locality 2 contains 18 inches of coal but 

more commonly contains shale interbedded with the coal, or a very thin bed 

of coal, as shown by sees. 4 and 169. Four beds that occur 20, 45, 60, and 85 

feet below the top of the Tullock member of the Lance locally contain 18 

inches or more of coal. As all of them crop out on a steep slope, they have been 

mapped by one outcrop line, which represents1 a coal zone rather than a single 

coal bed. Sections of these coal beds were measured at localities 168, 176, and 

180. At locality 6, in the SW1^ sec. 30, the following section, beginning about 

60 feet below the top of the Tullock member, shows several thin beds:

Ft. in.

Shale, carbonaceous, with thin coal streaks_ _ ____ 4 

Sandstone, cream-colored, argillaceous, becoming lighter

at base _ - 37 

Shale, carbonaceous, and coal__ _ _ _ 1 6
ROSEBUD COAL FIELD, MONTANA 87

£,
88 CONTEIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

Ft. in.

Shale, white, clay_______________________ 4 6 

Coal and carbonaceous shale_________________ 2 6 

Sandstone, tan and white, argillaceous-_________ 14 

Coal and carbonaceous shale________________ 4 

Sandstone, tan, with interbedded sandy shale_______ 28 6 

Coal________________________________ 7 

Sandstone, light, argillaceous_________________ 3 6 

Shale, brown, carbonaceous__________________ 7 

Coal and carbonaceous shale_________________ 6 

Interval to Wright bed, at base of Tullock__________ 100±

The Big Dirty bed, at the base of the Lebo shale member, contains from 2 

feet to 5 feet 7 inches of coal, shale, and bone at localities 166, 167, 171, 174, 

175, 179, 181, 183, and 186. Because of its impurity, it is of doubtful commercial value. At locality 187 a local coal bed 18 inches thick is present about 

75 feet above the base of the Tongue River member.

T. 4 N., R- 4^ E. Rosebud Creek flows northward along the east edge of 

T. 4 N., R. 42 E. West of and above the alluvial flats bordering Rosebud 

Creek a series of sandstones and shales form a conspicuous escarpment through 

which the tributaries of Rosebud Creek have cut narrow valleys; farther west 

the surface of the township is a series of rounded somber-colored shale hills. 

The township is deeply dissected by erosion, and there are large areas of 

badlands. Vegetation is sparse.

The top of the Hell Creek member of the Lance formation crops out along 

Rosebud Creek, in the northeast corner of the township. The overlying Tullock 

member of the Lance formation crops out in about half of the area. The upper 

part of this member is marked by a series of sandstones and shales, which are 

more resistant to erosion than the overlying beds and therefore form a bench 

or escarpment. Above this escarpment occurs the Lebo shale member of the 

Fort Union formation, which crops out on the ridges in the western part of the 

township. Only a few small areas of rocks belonging to the Tongue River 

member of the Fort Union formation remain in the highest parts of the 

township. Stream gravel mantles nearly all the higher'hills.

The Wright bed, at the base of the Tullock member of the Lance formation, 

crops out only in the northeast corner of the township. At locality 163 it is 

3 feet thick, with a 1-inch parting near the top. A few wagon loads of coal 

have been taken from the outcrop in the east bank of Rosebud Creek at this 

locality. At localities 10 and 11 the coal is less than 18 inches thick. A shale 

bed from 25 to 30 feet above the Wright contains 1 foot or more of coal in a 

few places. From 185 to 220 feet above the Wright, or 50 to 85 feet below the 

top of the Tullock member, is a coal zone, which at localities 12 and 23 contains 

about 18 inches of coal. At locality 27, 300 feet east of sec. 36,' a bed in this 

zone contains 3 feet of coal, but as this bed is traced northwestward in to-this 

township it changes to black shale with thin seams of coal. The Big Dirty 

bed contains ifrom 3 feet to 5 feet 8 inches of dirty coal, shale, and bone at 

localities 9, 13 to 22, and 26. In a few places it carries coal that is clean 

enough to burn, but as a whole this bed is so dirty that it is questionably 

classifiable, as a fuel. At locality 22, in sec. 31, a small quantity has been 

mined. A local coal bed about 50 feet above the base of the Lebo at locality 

25, in sec. 36, is extremely variable in coal content and generally consists of 

black shale and soot, with a few inches of coal.

T. 8 N., R. 42 E. T. 3 N., R. 42 E., lies on the west side of the Rosebud Creek 

Valley and is largely drained by West Cottonwood, Sprague, and Udie Creeks,
T. 4 N.,R.42 E.

Local bed about 50 ft 

above base of Lebo member Big Dirty bed

Ft in. 

10

Ft

16

Ft. In.

I Ft in. 

jl 2

18 

Ft. 

Coal zone 50 to 85 ft 

below top of Tullock Wright bed

12 23 10

Ft In. Ft In. 

FIGDBB 14. Sections of coal beds in T. 4 N
90 CONTRIBUTION'S TO ECONOMIC GEOLOGY, 1934-36

which are tributaries of Rosebud Creek. The southwest quarter of the township is steeply rolling and grass-covered, but the remainder of the township 

is greatly dissected and practically barren of vegetation.

The Tongue River member of the Fort Union crops out in the southwestern 

part of this township and along the divides between the principal streams. 

The Lebo shale member of the Fort Union formation is exposed in the valleys 

and gives rise to barren and sparsely vegetated areas. The Tullock member 

of the Lance formation crops out along four stream courses in the eastern part 

of the township.

A thin coal bed in the zone 50 to 85 feet below the top of the Tullock member 

is the lowest coal bed exposed in this township. It crops out only in sec. 1, 

where it was measured at locality 28. The Big Dirty bed, at the base of the 

Lebo shale member of the Fort Union formation, crops out on the east and

north sides of the township and

T. 3 N.. R. 42 E.

Terretor _ , . . Robinson bed BurIeV bedBig Dirty 

bed

33 24

t

Coal zone 50 to 85 ft. 

below top of Tullock 

28

,Ft in.

usually contains about 3 feet of 

dirty coal. The impurities in this 

bed make it of doubtful commercial value, but a section was 

measured at locality 32. The Burley bed, in the lower part of the 

Tongue River member, is about 

7 feet 6 inches thick at locality 

24, in sec. 18, but the area underlain by good coal is less than 100 

acres. At locality 33 there is a 

very small area underlain by a 

bed of coal 2 feet thick which 

is 40 feet above the Burley bed. 

It is at approximately the horizon 

of the Terret bed, which forms 

the thick clinker east of Rosebud 

Creek, and of the Robinson bed, 

which has been mapped in T. 2 

N., R. 41 E., in the Forsyth coal 

field. This bed is not of economic

value, however, because of its extremely small lateral extent.

T. 2 N., R. J,2 £7 The surface 

of T. 2 N., R. 42 E., is drained by

four eastward-flowing tributaries of Rosebud Creek from north to south Spring 

Creek, a small valley known locally as " The Break ", Pony Creek, and the North 

Fork of Cow Creek. The divides between these valleys are capped by erosional 

remnants of Rosebud clinker, on which there are growths of yellow pine and 

juniper. As a whole, the topography of the township is rough, for the valleys 

below the clinker-capped divides are deep, and there are numerous buttes.

The Lebo member of the Fort Union formation is exposed in a small area 

along Spring Creek in the northeast corner of the township. The Tongue 

River member crops out in the remainder of the township. A partial section 

of the Tongue River member measured in sec. 24 is given on page 62.

The Burley bed is the lowest coal mapped in the township and ranges in 

thickness from 3 to 9 feet. The coal has few partings and is of good quality. 

In the eastern part of the township it averages 8 feet or more in thickness, 

and in the northern part it is from 5 to 6 feet thick. It is not exposed in the

EXPLANATION

Coal Bony coal Bone Shale

FIGURE 15. Sections of coal beds in T. 3 N. 

R. 42 E.
U. S. GEOLOGICAL SURVEY BULLETIN 847 PLATE 12

T. 2 N., R. 42 E.

Terret bed

/ * \ Upper split Upper split upper split?

43 . 72 49 51 66 68 42 44 50 64 65 71 74

Ft. in. Ft. fn. Ft in. Ft in. Ft in. pt in. m Ft in. In. Ft. in. Ft in. _ Ft in. Ft. In. Ft . fn.

r:

I I

|4 8

Burley bed

34 38 41 

Ft in. Ft

45 46 

Ft in. Ft

48 67 

.Ft. in.

6 

I

18+

8 8

69 70

,, ;,_, Ft In.

8 4

73

EXPLANATION

Coal Bony coal Bone Carbonaceous

shale

Shale Sandy Sandstone Clay 

shale

SECTIONS OF COAL BEDS IN T. 2 N., R. 42 E.
ROSEBUD COAL FIELD, MONTANA 91

southwestern part of the township, where it is overlain by thick cover. Along 

the eastern tier of sections the Burley coal is, for the most part, burned or 

oxidized along the outcrop. West of this the coal is generally covered by 

smooth grassy slopes. Sections were measured at localities 34 (locality 143 of 

Dobbin 40 ), 37, 38, 41, 45, 46, 48, 67, 69, 70, and 73. The Terret bed, about 50 

feet above the Burley bed, is split into two or more thin coal beds; on the 

east side of Rosebud Creek it is 10 to 15 feet thick. In thisi township the 

greatest thickness of coal observed is in the upper split of this bed, at locality 

65, where there is 4 feet 8 inches of coal. Coal sections were measured at 

localities 42, 44, 50, 64, 65, 71, and 74. Several of these were made to show 

the westward thinning of the Terret bed. At locality 40 there is only 6 inches 

of coal. The thin coal beds at localities 40, 42, and 44 are from 75 to 100 feet 

above the Burley bed and possibly are not a part of the Terret. bed. At locality 

39, 2 feet of interbedded coal and shale occur at the horizon of the Terret bed, 

at approximately the same stratigraphic position as the Robinson bed of the 

Forsyth coal field, in T. 2 N., R. 41 E. These two beds (Terret and Robinson) 

appear to be approximate stratigraphic equivalents, but different names are 

used because it seems probable that the Robinson bed of the Forsyth coal 

field thins toward the east, as it approaches this township, until it becomes 

less than 18 inches thick. A local coal bed about 60 feet below the McKay 

bed occurs in three small isolated outcrops in or near sec. 13. Coal sections 

taken at localities 51, 66, and 68 show that this coal is from 16 to 26 Indies 

thick. A mile and a half west of locality 68 it contains less than 18 inches 

of coal. The area in which this bed occurs is so small that it is not of economic 

value. The McKay bed, in T. 2 N., R. 41 E. (in the Forsyth coal field 41 ), is 

over 6 feet thick and from 8 to 21 feet below the Rosebud bed. In the northwestern part of T. 1 N., R. 42 E. (in the Ashland coal field 42 ), the McKay bed 

is from 7 to 9 feet thick and from 7 to 30 feet below the Rosebud bed. The 

McKay bed, where unburned, is usually concealed by clinker of the Rosebud 

bed. At locality 49 a coal bed 4 feet 6 inches thick occurs 33 feet below the 

ash of the burned Rosebud bed. This bed is correlated with the McKay 

bed. It is believed to be at least 4 feet 6 inches thick and to lie about 30 

feet below the Rosebud bed in a large area in the southwestern part of this 

township, although additional outcrops to substantiate this belief were not 

found. Where the McKay bed is unburned, its areal distribution will correspond approximately with that of the Rosebud clinker. Unburned coal in the 

Rosebud bed is confined to less than 2 square miles in the western part of 

the township. Two outcrops of the Rosebud bed were found one at the 

Pierson mine, at locality 72, near which the coal is reported to have been burning for nearly 10 years, and the other at locality 43. Complete thicknesses 

could not be measured on either of these outcrops, but from the development 

work at Colstrip, 2 miles west of this township, a thickness of 20 feet or more 

may be inferred. The average amount of cover on the Rosebud bed in sees. 

19 and 30 is 150 feet and in sec. 34 is 100 feet.

Coal for local domestic use has been mined from the Burley bed at the 

McKay mine at locality 41, in sec. 7. -Areas underlain by the Burley bed in 

the northwestern part of the township, on the north and south sides of 

Spring Creek, appeMr to be favorable for open-cut mining. The coal ranges 

from 5 to 8 feet in thickness, and the areas in which the cover does not

40 Dobbin, C. E., The Forsyth coal field, Rosebud, Treasure, and Big Horn Counties, 

Mont.: U. S. Geol. Survey Bull. 812, pi. 10, 1929. 

« Idem, p. 53.

i2 Bass, N. W., The Ashland coal field, Rosebud, Powder River, and Custer Counties, 

Mont. : U. S. Geol. Survey Bull. 831, p. 63, 1932.
92 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

exceed 50 feet are shown on plate 11. At the Pierson wagon mine, at locality 

72, the coal is obtained from an exposure in the banks of Pony Creek.

T. 6 N., R. 43 E. (fractional) That part of T, 6 N., R. 43 B., which lies 

within the Rosebud coal field is covered by a series of terraces, which are 

now partly dissected by Butte, Sweeney, and Coal Creeks. The highest point 

in this part of the township is m sec. 32; it is 500 feet above Yellowstone 

River.

T.6 Nn-R43 E.

' Local bed about 

below 220 ft 

Local bed top of Tullock

240 Ft , 247_. , Ft In. ,_ -«. In.

2 4

Bed about 300 ft. 

below top of Tullock

193 -. in 194 195 Ft in. i, i Ft in. 196

199 , 200 241 i Ft in. .,,5...*:, Ft in. . 242 243 244 245 Ft '" I»VAV, Ft in. .. _, Ft in. ^^ Ft in. ........... Ft 248

Ft in. 

4

EXPLANATION 

Coal Bony coal Bone

Dirty Carbonaceous Shale 

coal shale

FIGUKB 16. Sections of coal beds in T. 6 N., R. 43 E.

The Tullock member of the Lance formation, in many places concealed by 

a thin veneer of terrace gravel, covers practically all of the township that 

lies south of the Yellowstone River. All the coal beds that have been mapped 

are in the lower part of this member. The Tullock member is overlain by 

the Lebo shale member of the Fort Union formation, which crops out in the
KOSEBUD COAL FIELD, MONTANA 93

highlands in the southeast and southwest corners of the township, in parts of 

the southern tier of sections. Only a small area of alluvium is present on 

the south side of the Yellowstone.

A coal zone about 300 feet below the top of the Tullock member is shown 

on plate 11 but is not as continuous as shown by the outcrop line. Coal sections at localities 194 to 199 and 242 are on the same bed. (See fig. 11.) 

This bed thins out west of locality 194 and is probably represented by the 

lower coal and shale bed at locality 193. A short distance east of locality 242 

the coal bed ends abruptly, probably being cut out by a stream channel. A 

soft sandstone is present at the horizon of the coal bed. At locality 243 a coal 

bed is present at approximately the same horizon as the bed at locality 242. 

It is of variable thickness, as shown by sees. 243, 244, 245, and 248. A 

section of a local bed about 220 feet below the top of the Tullock was measured 

at locality 247, and another local bed was measured at locality 240. Neither 

of these beds contains 18 inches of coal. No sections were measured on the 

Big Dirty bed at the base of the Lebo, which crops out only in the southern 

part of the township. To judge from sections measured in the township adjoining on the south, the Big Dirty bed probably does not contain 18 inches of 

clean coal.

None of the coal in this1 part of the township was being mined at the time 

the survey was made. The mine workings at locality 245, consisting of two 

drifts, have been abandoned for many years, A small drift mine is operated 

sporadically at locality 199 to produce coal for local consumption. The small 

open-pit wagon prospect between localities 198 and 199 has not been used 

for a long time.

T. 5 N., R. JfS E. Sweeney Creek and its tributaries drain all except about 4 

square miles of T. 5 N., R. 43 E. An escarpment of the Tullock member borders 

this creek across the township. The escarpment is just above the level of the 

stream near the Horton ranch, in sec. 31, T. 5 N., R. 44 E., but rises to a height 

of 150 feet above the stream in sec. 3, where Sweeney Creek leaves the township. Above the escarpment are somber-colored shales dissected into badlands. 

A picturesque feature of this township is the group of sharp, high red-capped 

peaks in sees. 18 and 19, known as the Rosebud Buttes. They rise 300 feet 

above the surrounding country and are erosion remnants capped by the resistant 

clinker formed by the burning of the Burley bed. The surface of the township 

as a whole is rough and dissected by many sharp, deep valleys. The maximum 

relief is 650 feet.

Rocks belonging to the Tullock member of the Lance formation are exposed 

along Sweeney Creek in a strip 2 miles wide in the northern part and narrowing 

to about 1 mile in the southeastern part, and also in several valleys along the 

west border of the township. The Lebo shale member of the Fort Union formation forms the surface rock over a wide area on both sides of Sweeney Creek 

and in the southwest corner of the township. A maximum of 300 feet of strata 

belonging to the Tongue River member remains on the Rosebud-Sweeney Creek 

divide in the southwestern part of the township. Terrace gravel covers many 

of the hills on the west side of Sweeney Creek.

The township is practically devoid of coal beds 18 inches or more in thickness. A coal bed less than 18 inches thick, 60 feet below the top of the Tullock 

member, near the Jackson ranch in sec. 24, has been utilized as an emergency 

source of domestic fuel. The Big Dirty bed does not contain 18 inches of coal 

at any of the exposures examined. The sections measured at localities 202, 205, 

206, 238, and 239 show the character of this bed. At locality 201 the Big Dirty 

bed contains less than 18 inches of coal, and at localities 203 and 204 it is practically all carbonaceous shale. There are no coal beds 18 inches or more thick
94 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

Big Dirty bed

202 205 206 239

Ft. Ft. in. in.

in the Lebo member above the Big Dirty bed. There are two small isolated 

areas containing coal in the Trail Creek zone in sec. 31, but no sections of it 

were measured in this township. About a quarter of a mile south of sec. 31, at 

locality 165, the Trail Creek zone contains 2 feet of coal and 15 inches of impure 

coal. Erosion has removed the Burley and Terret beds in this township.

T. 4 N., R. 43 E. Rosebud Creek, which crosses the southwestern part of 

T. 4 N., R. 43 E., and its tributaries drain all of this township except about 6 

square miles in the northeastern part, which is drained by tributaries of Sweeney 

Creek. The west side of the Rosebud-Sweeney Creek divide is deeply cut by 

erosion, forming a strip of barren badlands surmounting an inconspicuous 

escarpment and extending in a northwesterly direction across the middle of the 

township. The east side of the divide slopes away gently and is covered with 

vegetation. The maximum relief is about 500 feet.

Erosion has cut deeply into the Tullock member of the Lance, exposing a 

complete section of this member in the western part of the township. The

somber-colored shales of the

t______T. 5 N..R.43 E.___________^ Lebo member of the Fort

Union, which overlie the Tullock member, crop out principally in this township as an 

irregular band along the west 

side of the Rosebud-Sweeney 

Creek divide. The lower part 

of the Tongue River member 

caps this divide.

No outcrops of the Wright 

bed, at the base of the Tullock member of the Lance, 

were found in this township, 

but about a quarter of a mile 

west of sec. 7, at locality 163, 

there is 2 feet 7 inches of 

clean coal exposed. From 190 

to 225 feet above the Wright 

bed, or 50 to 85 feet below the 

top of the Tullock member, is 

a coal zone which, at locality 

27, contains a coal bed 3 

feet thick with a %-inch parting. Southward this bed splits into two beds 

8 feet apart, each bed containing 2 feet or less of somewhat impure coal. This 

bed underlies a little over half of sec. 31. On the east side of Rosebud 

Creek, at the Sand mine, a section was measured on a coal bed 70 feet below 

the top of the Tullock member, at locality 157. This bed thins northward to 

less than 18 inches. Half a mile south of the south township line a bed at 

approximately the same horizon contains a few inches more of coal than at 

the Sand mine. If this is a continuous bed. through sees. 29 and 32, it 

will average about 3 feet in thickness. The Big Dirty bed, at the base of the 

Lebo, does not contain coal 18 inches or more in thickness. A section measured 

at locality 164 shows 3 feet 7 inches of coal and shale interbedded. A coal 

section measured at locality 158 on a local bed in the Lebo member, about 

35 feet above the Big Dirty, is shown on the map in sees. 21 and 22, but the 

coal is dirty and of little importance. The coal in the Trail Creek zone is 

about 50 feet above the base of the Tongue River member. The maximum 

thickness of clean coal observed is 2 feet 10 inches. Coal sections were measB

EXPLANATION

Coal Bony coal Bone

Carbonaceous Shale 

shale

Dirty 

coal

Sandstone 

PIGUBB 17. Sections of coal beds in T. 5 N., R. 43 E.
Trail Creek coal zone Lo

"v ab

Coal Bony coal Carbonaceous Shale 

shale

Sandy Sandstone Clay 

shale

el- 

» 

2 C3 FIGDRB 18. Sections of coal beds in T. 4 
96 CONTEIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

and 155, appear to be on a continuous bed, which thins southward. A section 

measured on the west side of Rosebud Creek, at locality 29, indicates that 

this bed splits into two parts, and the coal in both of these splits pinches out 

westward in the adjoining township, near locality 28. Sections of the Big 

Dirty bed were measured at localities 30, 81, 35, 36, 107, 108, 129, 130, 181, 133, 

135, 154, and 156, but, as this coal bed is extremely variable in quality and; 

?n many places contains over 50 percent of bone and shale, it is regarded as of 

doubtful commercial value. At locality 156 a local bed about 2 feet thick, 

with a 2-inch parting in the middle, occurs 20 feet above the Big Dirty bed. 

Coal sections of beds in the Trail Creek zone were measured only in sees, 

35 and 36, at localities 109, 110, 112, and 113. Coal sections 109, 110, and 

113 probably correspond with the lower coal at 112. Beds from 1 to 2 feet 

thick may be present in this zone in sees. 13 and 24. The Burley bed 

occurs in parts of sees. 13, 24, and 36. In the township adjoining on the 

south the Burley bed thins northward, so it is not certain that the Burley 

bed continues northward to localities 136 and 137, but as the coal at these 

places is at approximately the same horizon as the Burley bed, the name is 

used. Practically all of the Terret bed has burned and formed the clinker 

in the eastern part of the township.

T. 2 N.t R. 48 E. Rosebud Creek flows northward through a broad valley 

across the middle of T. 2 N., R. 43 B. The sides of the valley rise gradually 

to high clinker-capped mesas and ridges, which are several hundred feet above 

the valley. The upland in the eastern part of the area is an undulating table? 

land, which has been partly dissected by deep ravines. Several gravel-covered 

terrace remnants and small areas of badlands occur on the west side of 

Rosebud Creek.

The uppermost part of the Tullock member of the Lance formation probably 

extends for a short distance into this township along Rosebud Creek. Overlying this is the Lebo shale member of the Fort Union formation. The Tongue 

River member of the Fort Union covers over half of the township; a sectionmeasured in sec. 7 is given on page 62.

The maximum thickness of the Trail Creek coal zone is 45 feet, and the 

lowest coal in it is 20 feet or more above the base of the Tongue River member. 

One or more coal beds oS 'small lateral extent occur in this zone. As one bed 

pinches out, another comes in at a slightly higher or lower horizon. None of 

the beds in this zone are over 2% feet thick, and commonly they are 2 feet or 

less. Coal sections were measured in this zone at localities 47, 54, 58, 60, 61r 

63, 75, 77, 81, 84, 85, 93, 97, 99, 101, 102, and 105. An uncorrelated coal section 

measured at locality 100 probably belongs in the lower part of this zone. la 

the west tier of sections the Burley bed, which is about 50 feet above the topof the Trail Creek zone, is over 7 feet thick, and on the east side of Rosebud 

Creek, at locality 78, it is 6 feet 2 inches thick. This bed thins northward 

and is about 3 feet thick in the extreme northeastern part of the township. 

The coal is of good quality. Sections were measured at localities 52, 53, 59, 62, 

76, 78, 91, 92, 98, 104, 106, and 111. At localities 92 and 106 the upper part 

of the Burley bed is oxidized, so that a short distance back from the outcrop 

the coal is probably thicker. In the northern part of the township the Terret 

bed is about 125 feet above the Burley bed; in the southern part, 70 feet above 

the Burley. On the east side of Rosebud Creek the Terret bed is burned 

along its outcrop, except in the southeastern part of the township. A section 

measured at locality 103 shows 11 feet of good quality coal, the top part of 

which is slightly oxidized, but in the southern part of the township, at locality 

79, this bed has thinned to 5 feet. Coal sections measured at localities 55, 56, 

and 57 show that the Terret bed thins even more on the west side of Rosebud
U. 8. GEOLOGICAL SURVEY BULLETIN 847 PLATE 13

T. 3 N., R. 43 E.

Burley bed Trail Greek coal zone Big Dirty bed

136 137 109 110 112 113 30 31 35 36 107. 108 129 130 131 133 135 154 156

Ft. Ft, in. K' in- .Ft' in' , t Ft '" .0. in. In. Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. Ft. in Ft. in. . .Ft. In. « '" F«- '" Ft Ft. in.

5

II

8

I 9

6

I 6

Coaj zone 50 to 85 ft. 

below top of Tullock

29 132 134 155

Ft. in. Ft. in. Ft. in. Ft. in.

2 I

13 3

3 5

ft I Z

|2 3

12 4

EXPLANATION

Coal Bony coal Bone Carbonaceous Shale Sandy Sandstone Clay

shale shale

SECTIONS OF COAL BEDS IN T. 3 N., R. 43 E.
U. S. GEOLOGICAL SURVEY BULLETIN 847 PLATE 14

T.2 N..R.43E.

Local beds Local bed Terret bed Burtey bed

50 to 120.ft. 135 ft. _ ______________ _____________________________________ _____________________________________ 

above Terret above Terret Upper split Upper split N

80 t . 96 55 56 . 57 79 103 52 53 59 62 76 78 91 92 98 104 106 111 

.''"', ,Ft in' Ft ln- Ft in- Ft in. Ft Ft Ft in. Ft in. Ft in. Ft in. Ft in. Ft in. « ln- Ft In. Ft in. Ft in. Ft ^ .

.11 i i i i i i i i I : ^, ^^^m ^^^m ^^^m ^^^m ^^^m ^^^m ^^^m ^^^m ^^^m ^^^m ^^^m ^^^m ^^^r

I 3

I 6

o 2

|7 8

|8 3+

52

12 I

Trail Creek coal zone Uncorrelated

47 54 58 60 61 63 75 77 81 84 85 93 97 99 101 102 105 100

Ft in. Ft in. [n fl in_ Ft in. Ft. in. Ft. in. Ft in. Ft. in. FL in_ Ft in. Ft. in. Ft. in. Ft. in. Ft in. Ft in. Ft in. Ft in.

I

t , ' 6 H '° H > B' 

 I

EXPLANATION 

Coal Bony coal Bone i

Carbonaceous Shale Sandstone Clay 

shale

(a) Oxidized coal, therefore 

incomplete section

SECTIONS OF COAL BEDS IN T. 2 N. t R. 43 K.
ROSEBUD COAL FIELD, MONTANA 97

Creek and splits into two parts. The area underlain by this bed west of 

Rosebud Creek is very small, being restricted to about 75 acres in the southern 

part of sec. 18 and very small areas in sec. 31. Coal beds above the 

Terret are not of economic importance in this township. On a high butte at 

locality 80 three local beds were found above the Terret, the lowest 50 feet 

above it. The thickness of the beds and the intervals between them are shown 

in the plotted coal section. The high buttes in sec. 35 are capped by 

clinker, probably formed from the Knoblock bed, which occurs in the Ashland 

coal field At locality 96 a local bed 135 feet above the Terret contains 15 inches 

of coal.

None of the coal in this township is mined. Two areas west of Rosebud 

Creek, which are underlain by the Burley bed under less than 50 feet of cover, 

are shown on plate 11. The coal at these localities is 7 feet or more thick. 

In sees. 10 and 11 the Burley bed underlies about 25 acres in which the 

cover is less than 50 feet; the coal is 5 feet thick.

T. 6 N., R. 44 E. (fractional). Yellowstone River, which flows northeastward 

across T. 6 N., R. 0 44 E., is bordered on the south by a flood plain ranging in 

width from a few hundred feet to over 2 miles. A series of dissected terraces 

cover most of the area south of the alluvial flood plain.' The maximum relief 

is about 500 feet. Much of the bottom land along the river is under cultivation, and good crops are raised if there is sufficient rainfall. About 600 acres 

of alluvial bottom land between the Northern Pacific Railway and the Yellowstone River is irrigated by pumping water from the river.

The Tullock member of the Lance formation borders the flood plain of the 

Yellowstone River and extends up Graveyard, Iron Jaw, and Coal Creeks. The 

Tullock member is overlain by the Lebo shale member of the Fort Union formation. Small remnants of the Tongue River member of the Fort Union formation overlie the Lebo in sees. 27 and 34.

The outcrop of coal beds in the lower part of the Tullock member is practically 

confined to Coal Creek. Three coal beds crop out in the cut banks along this 

creek. The bed at locality 246 cannot be traced up the creek, but the measured 

section of the bed at locality 248, in T. 6 N., R. 43 E., is similar to it. The bed 

at locality 246 is 30 feet lower in altitude than the bed at locality 248, and it 

seems probable that there has been a slight dislocation between these two 

points. The bed at locality 248 is about 300 feet below the top of the Tullock. 

The coal in the local bed about 280 feet below the top of the Tullock is less than 

18 inches thick at the two places it was measured localities 249 and 255. 

Sections of the local bed about 240 feet below the top of the Tullock were 

measured at localities 250, 254, and 256* The coal bed at the base of the Lebo 

is generally too dirty and impure to be used as a fuel; occurrences of fairly 

clean coal IS inches or more in thickness are extremely local in extent. Coal 

sections were measured at localities 253, 260 to 266, 295, and 296.

None of the coal in this part of the township is being mined. A small drift 

mine at locality 246 has been abandoned for a number of years.

T. 5 N., R. 44 E. A dissected clinker-capped divide extends northwestward 

from the southeast corner of T. 5 N., R. 44 E. The surface of the township is 

rough, with the area of irregular and jagged clinker-capped buttes and escarpments in the central and southeastern portions surrounded by sharply dissected 

semi-badlands. The maximum relief is about 650 feet.

The Tullock member of the Lance formation crops out on Graveyard, Iron 

Jaw, Coal, and Sweeney Creeks. The Lebo shale member of the Fort Union 

formation crops out in a band of irregular width in the western and northern 

parts of the township. The lower part of the Tongue River member crops out 

on the divide. The burning of the Burley coal bed, in 'the Tongue River
P 

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T. 6 N., R. 44 E. 

_____A______

Bed at base of Lebo member

Local bed about 240 ft 

below top of Tullock

Bed about 300 (?) ft Local bed about 280 ft 

below top of Tullock below top of Tullock

Ft. in. 255

Coal B

Sha

PiQimm 19. Sections of coal beds iu T. 6 N
KOSEBUD COAL FIELD, MONTANA 99

probably continues northward with about the same thickness. A bed in the 

Terret zone, about 85 feet above the Burley bed, contains 4 feet 6 inches of coal 

at locality 236, a few hundred feet south of the south township line, in sec. 6, 

T. 4 N., R. 45 E. This bed thins northward from the south township line. It 

is restricted to part of sees. 35 and 36.

T. 4 N., R. 44 H. T. 4 N., R. 44 E., occupies the upper part of the drainage 

area of Sweeney Creek. The land is gently rolling, supports a good growth of 

grasses suitable for grazing, and is in part under cultivation. Long, gradual 

slopes and wide valleys are characteristic surface features of the township.

The upper part of the Tullock member of the Lance formation is exposed for 

about a mile along Sweeney Creek in sec. 3. Above this, in a rough semicircle, the Lebo shale member of the Fort Union formation crops out. The 

Tongue River member of the Fort Union is exposed in nearly three-fourths of 

the township and contains the coal beds of economic importance. The beds are 

practically flat-lying, except in close proximity to faults. A normal fault in 

sec. 36 is described in the section on structure (p. 68) ; an exposure of the

T. 5 N., R. 44 E.

Local bed 45 ft. 

above base of 

Lebo member '

Bed at base of Lebo member

268 F, in. 237 258,

I 5

259. 267 

I Ft in. 

5

2 3

J3 4 

10

EXPLANATION 

Coal Bony coal Bone

Carbonaceous Shale 

shale

Clay

FIGURE 20. Sections of coal beds in T. 5 N., R. 44 E.

fault surface was found at locality 223. In the southern part of sec. 33 

there is some irregularity in the position of the coal beds, which may possibly 

be due to a small concealed fault.

The bed at the base of the Lebo shale member, which is the lowest coal 

exposed in this township, is variable in coal content, is dirty, and is not 

important as an economic source of coal. A section was measured at locality 

210. A coal bed 6 inches thick occurs in the Lebo member at locality 207. 

In the Trail Creek zone, at locality 147, there is a coal bed 14 inches thick, 

but as it is slightly oxidized at the top, its true thickness is probably greater 

than this. A coal bed 2 feet 6 inches thick, which is higher stratigraphically in this zone, was measured at locality 152, a mile west of this 

township. These sections are probably on two different beds in the Trail 

Creek zone, the bed at locality 147 having thinned to the northwest. Sections 

of coal beds in the Trail Creek zone were measured in the Sweeney Creek 

drainage area at localities 208, 209, and 217. A maximum of 2 feet 2 inches 

of poor coal was found in this zone. Seven inches of coal, which has been 

oxidized, was found in the lower part of this zone at locality 211. There is
^J (D JS

P p 

MOB

p1 S- 3

 J~* O & r.,

i-j >-" 5Z

tO O f5 P

Li « P

M ° «f

T. 4 N., R. 44 E.

p (D

o o 

P 2

tJ* l-u

c& p 

If

m p

S coT"

?!

p o

SI

10 ?.

tO CD

CO CO

Terret bed Burley bed

149 216 150 151 213 214 215 218 

Ft in. Ft. in. .Ft in. .Ft. in. Ft. in. , Ft. in. Ft. in. Ft. i

3 

5

^^B m^^m mtoaj <~'-? f=sz** -^ ^^H 

3 I

zyz

4 9

6 8

Iff*)

I:

Trail Creek coal zone

Bed at base of 

Lebo member

147 208 209 217 . 210

Ft. in. Ft. in. Ft. in. In.

I

EXP

l^H 

Coal 

Sandy 

shale

(a) Oxid

inc

FIGURE 21. Sections of coal beds in T. 4 N., 
ROSEBUD COAL FIELD, MONTANA 101

coal has been mined from open pits. The Burley bed at locality 223 is cut 

off to the southwest by a fault and is concealed by alluvium in the creek. 

The Terret bed occurs only in the southern part of the township. It is about 

60 feet above the Burley bed and has burned and formed a red clinker along 

much of its outcrop. Unburned coal in the Terret bed does not underlie a 

very large area. It is 4 feet 9 inches thick at locality 216, and at locality 

149 there is 5% feet of coal underlain by 2 feet of shale and then 3 feet 8 

inches of coal, which is slightly oxidized.

T. 3 N., R. 44 E. The Rosebud Creek-Tongue River divide passes through 

the middle of T. 3 N., R. 44 E., in a northerly direction. The rather flat top 

of the divide is bordered by an irregular clinker escarpment. The valleys 

on both sides of the divide are sharp and deep, and the rugged slopes are 

covered with timber. The relief is about 400 feet.

The upper part of the Lebo shale member of the Fort Union formation is 

exposed in the valleys of tributaries of the Tongue River and Rosebud Creek, 

on the east and west sides of the township, respectively. Overlying this 

conformably are the yellow and buff sandstone and gray shale of the Tongue 

River member, which is .the surface formation over most of the township 

and contains all the coal beds. The normal fault in sec. 1 is described on 

pages 68-69.

The Trail Creek coal zone is not a single bed, but includes several disconr 

tinuous coal beds in the lower 60 feet of the Tongue River member. The most: 

persistent coal bed is about 50 feet below the Burley bed. All the beds in this 

zone are thin and relatively unimportant. . Sections of the coal beds in the 

Trail Creek zone were measured at localities 118,120, 126,127,128,144, 453, 454, 

455, 457, 459, 461, and 466; the coal beds at localities 144 and 454 are in the 

lower part of this zone. The 3y2 feet of coal at locality 127 thins rapidly to 

the southwest. At locality 114 a bed in the Trail Creek zone has been oxidized, 

and 5 feet below it is a bed of coal and shale about 1 foot thick. The Burley 

bed is generally from 50 to 60 feet below the thick Terret clinker, but in the 

southeastern part of the township the interval is about 90 feet. Its thickness 

ranges from less than 18 inches to 4 feet 4 inches; the thicker and cleaner coal 

occurs on the west side of the divide. Sections of the Burley bed were meas-r 

ured at localities 117, 119, 121, 122, 125, 138 to 141, 143, 145, 146, 148, 212, 220, 

452, 456, 458, 462, 463, and 465. The coal at localities 122 and 125 seems to 

be oxidized, so the sections are probably not accurate. The Burley bed crops 

out at locality 464 and at a spring at locality 142, but no sections were measured. The Burley bed is probably not a continuous single bed over the entire 

township, as the grouping of sections in plate 15 implies. The coal sections 

of the Burley bed in the southwest corner of the township are on a continuous bed, as are also those in the northwest corner, but the coal may or may 

not be continuous between these two places. Some of the Burley coal sections 

in the eastern part of the township are probably on discontinuous beds. The 

Terret bed has burned along practically all of its outcrop and has formed a 

thick clinker that covers a large part of the surface of the township. Where 

unburned, the coal in this bed is 9 feet or more thick. Coal sections were 

measured at localities 221 and 460, and an outcrop was noticed at locality 124. 

At locality 221 there is 9 feet of coal and at the base more than 1 foot of ash 

and coal that was burning at the time of the field investigation in 1929. In 

the township south of this one the maximum thickness of the Terret bed is 

15 feet.

The Terret bed is the best one for development in this township. The estimate 

of the limit of the burning of the Terret bed is rather indefinite, but unburned 

692 36 -5
102 COIsTTEIBUTIOlsrS TO ECONOMIC GEOLOGY, 1934-36

coal underlies narrow strips along the main divide and the minor divides. 

The cover is between 100 and 150 feet. A small, impure coal bed in the Trail 

Creek zone has been prospected at locality 466.

T. 2 N., R. 44 E- The Rosebud-Tongue River divide follows an irregular 

northerly course through T.. 2 N., R. 44 E. The surface of the township is 

that of an upland of moderate relief trenched by deep valleys. The burning 

of the Terret coal bed has produced a red clinker, which is more resistant to 

erosion than the underlying strata, and consequently forms the protecting cap 

above a steep slope along an irregular escarpment. The steep slopes are covered with yellow pine and juniper. The maximum relief is about 600 feet.

The upper part of the Lebo shale member of the Fort Union formation is 

exposed in the valleys of tributaries of the Tongue River, on the east side of the ' - 

township. Overlying this conformably are the yellow and buff sandstone and 

gray shale of the Tongue River member, which are present at the surface over 

most of the township.

All the coal beds cropping out in this township occur in the Tongue River 

member of the Fort Union formation. The lowest coal is in the Trail Creek 

zone, which includes several discontinuous coal beds. The most persistent bed 

is about 60 feet above the base of the Tongue River member and is the bed ^ 

that is usually denoted by the outcrop line on plate 11. The maximum meas- !, 

ured thickness of the coal in this zone is 2 feet 11 inches, and its average ' 

thickness is about 2 feet. Coal sections were measured at localities 115, 468, 475, ' 

477, 479, 484, 490, 491, 493, 496, 497, 499, 502, 506, 508, 510, 511, 512, 516, 517, 

518, 531, 532, 534, 535, and 540. At localities 471 and 507 the persistent bed 

in the Trail Creek zone is oxidized along the outcrop. At locality 537 there is 8 

inches of coal, 44 feet below the persistent bed in the Trail Creek zone and ^ 

about 15 feet above the base of the Tongue River member. It is convenient 

to refer the coal in the Trail Creek zone to the Terret bed, which lies above it, 

because of the widespread extent and distinctiveness of the Terret clinker. The 

interval between the Trail Creek coal and the Terret bed increases to the west; 

at localities 493 and 496, in sec. 23, the interval is 77 feet; at locality 510, 

in sec. 21, it is 100 feet. The Terret-Burley interval remains constant at 

about 50 feet through these same sections. At locality 490, in sec. 24, the coal T 

in the Trail Creek zone is 77 feet below the Terret bed; 36 feet below the per- ' 

sistent coal bed in the Trail Creek zone, or 103 feet below the Terret bed, 

there is 8 inches of coal, then a 6-foot interval and 8 inches more of coal. 

This horizon may pass into the Trail Creek coal in sec. 21 (locality 510), 

which is 100 feet below the Terret. At locality 517 the Trail Creek coal 

is 2 feet 2 inches thick and 90 feet below the Terret bed. A few hundred feet 

east, at locality 518, it is only 8 inches thick. The Burley coal bed is from 

35 to 50 feet above the persistent coal bed in the Trail Creek zone and crops out 

in sees. 5, 6, and 30 and along the east side of the divide. Only a partial i 

section was measured at locality 116, where a spring issues from the Burley ; 

bed, but coal sections measured a short distance outside the township show that I 

the Burley coal in this vicinity is from 3 to 4 feet thick. The Burley bed is the ; 

thickest, from 4 to 5% feet, and of the best quality in the southwest quarter of ,' 

the township. At locality 474 the Burley bed is only 1 foot thick, and at 

locality 476 it contains only 6 inches of coal. It thickens west of sec. 12, 

however, and at locality 481 contains 4 feet of coal. At localities 478, 480, and 

500 the Burley bed is oxidized at its outcrop, so that measurements of its real 

thickness were not obtained. The Burley coal is partly exposed at locality 503. 

Coal sections were measured at localities 116, 467, 469, 470, 472, 474, 480, 481, 

483, 485, 488, 490, 491, 492, 494, 495, 498, 501, 509, 515, 519 to 530, 533, 536, 538, 

539, 541, 542, 544, 545, and 547 to 552. In the northeastern part of the township
U. 8. GEOLOGICAL SURVEY BULLETIN 847 PLATE 16

T. 3 N., R. 44 E.

Terret bed Burley bed

221 460 117 119 121 122 125 138 139 140 141 143 145 146

. Ft. in. Ft. in. Ft. in.

|3 6+

In. .__.Ft. in. -__.Ft. in. __Ft. in. .__.pt. in. , .Ft. in. . .Ft. in. __iFt. in.

\2 9

Z II

|9 6

148 212 220 452' 456 458 462 463 465

Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. ft. in. Ft. in. Ft. in. Ft- in-

.2

I Z

Trail Creek coal zone 

_____A_____

118 120 126 127 128 144 

Ft. in.

I 6

In. b~jFt- '" U^j Ft. m. t^g,- '" bda '" 

__ __I**' 6

I 

Ft. in. ^^ 

454 455 457 459 461 466

 

In. ^J Ft. in. i^ Ft. in. [ j Ft. in. 

2 M 9^ IS & 

26- ~" " ^ l S^S -3

I 3

EXPLANATION

3 !O

ll 4

Coal Bony coal Bone Carbonaceous Shale 

shale

Fjgq //. ; ; h^ (a i Oxidized coal, therefore 

C33 l^v) [r-^i incomplete section

Sandy Sandstone Clay

shale

SECTIONS OF COAL BEDS IN T. 3 N., R. 44 E.
U. 8. GEOLOGICAL SURVEY

T. 2 N., R. 44 E.

BULLETIN 847 PLATE 16

Local bed 135 ft. above Terret

""

'

I 4 '

Burley bed

116 r 467 469 470 472 474

a '" Ft in. Ft. in. Ft in. Ft in. Ft

I

480 481 . 483 435 488 490 491 492

111 ' a Ft. in. Ft. in. Ft. in. Ft. in. Ft in. Ft

al 4

|3 Z Ml

Terret bed

: s«

13 6

Ft.

494 495 498 501 509 515 519 520 521 522 523 524 525 526 527 528

/' '"' Fl m- Ft Ft m. Ft in. Ft in. Ft. in. Ft. in. Ft. in. Ft in. Ft in. Ft in. Ft in. Ft. in. Ft in. Ft. in. HUM 4 7

14 6 ^1^ 3

3 10

15 Z

529 530 533 5,36 538 539 541 542 544 545 547 548 549 550 551 552

/' '" u=-, a in ' , , a >" , , a in - , .Ft- '" . ,Ft- ^. , ,Ft. in. , ,« In. . , Ft. in. § , Ft. in. _ H in. _ Jt. ,n. , ,FL to. , ,Ft in. § /t. in. ^Ft in.

i

13 II

Z

|4 6

|3 3

4 7

IS t

Trail Creek coal zone

115 . 468 475 477 479 484 490 491 493 496 497 499 502 506 508

, '"' a in - Ft. in. Ft. in. Ft Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. Fl in. Ft. M:» || Ft. in. F

I I

510

in. Ft. in.

I

511 512 516 517 51tt 531 532 534 535 540

Ft. m. It. m. ft. in. ft. in. In. Ft in. Ft. in. Ft. In. ft, in. ft. in.

EXPLANATION

2 2

II

w

Coal Bony coal Bone Carbonaceous Shale 

2 6 shale

SECTIONS OF COAL BEDS IN T. 2 N., R. 44 E.

Sandy Sandstone Clay

shale (a) Oxidized coal, therefore 

incomplete section
EOSEBUD COAL FIELD, MONTANA 103

the interval between the Terret and Burley beds increases from 50 feet to 

about 75 feet. The Terret bed is present only in a narrow strip along the 

divide between the Tongue River and Rosebud Creek. It is the thickest coal 

bed in the township, containing from 9 to 15 feet of clean coal. It has burned 

along practically all of its outcrop and has formed the thick clinker that covers 

a large part of the surf ace. of the township. Coal sections were measured at 

localities 82, 83, 94, 482, 486, 504, 505, 513, 514, and 543. At locality 513 the coal 

is poorly exposed, so that the measurement of 15 feet of coal is only approximate. 

At locality 123 a spring issues from the Terret bed, which is unburned there, 

and at localities 487 and 546 the Terret coal crops out but was not measured. 

A local bed 18 inches or less in thickness occurs 135 feet above the Terret in 

sees. 7, 18, and 19, on which the coal sections at localities 86 to 90 and 95 were 

measured. This bed is too thin to be of economic value and is also of small 

lateral extent.

Coal for local supply is obtained from surface workings on the Terret bed 

at the Snyder mine, in the northeast corner of sec. 31. The total thickness 

of the coal here could not be' ascertained, but it is more than 9% feet, and 

about 160 acres has 50 feet or less of cover. The cover over the Terret bed 

on the divide is generally between 100 and 200 feet.

T. 5 N., R. 43 E. The greater part of T. 5 N., R. 45 E., lies in the drainage 

area of Graveyard Creek. The surface of this township presents varied topography in the northwest and northeast corners, typical badlands; in the central and southwestern parts, sparsely wooded buttes and ridges capped by 

clinker; in the eastern part, gently undulating grassland, parts of which are 

under cultivation. This township is also described in the report on the Miles 

City coal field.48

The Lebo member of the Fort Union formation appears in the lower parts of 

the area in the Graveyard Creek Valley and the valleys in the northeast 

corner of the township. The Tongue River member of the Fort Union formation crops out in the remainder of the township.

No coal beds 18 inches or more in thickness were found in the Lebo member. 

A coal bed about 15 feet below the Burley occurs in the northern part of the 

township, mainly in sees. 2, 3, 4, 5, 9, 10, and 11. This bed thins to less 

than 18 inches south of a line between localities 285 and 290. The northern 

limit is not known, but a section measured in T. 5 N., R. 46 E., seems to indicate 

that it does riot extend far to the northeast. In sees. 3, 4, and 9, where best 

exposed, it has a thickness of 2 to 3 feet. Sections were measured at localities 

284 to 289, 291 to 294, 297, and 298. The Burley bed, about 190 feet above the 

base of the Tongue River member of the Fort Union formation, is the thickest 

coal bed in the township, but practically all of it has been burned. Unburned 

coal remains in parts of sees. 31, 32, 35, and 36. A small area in sees. 35 

and 36 is underlain by coal under 50 feet or less of cover. The Burley is of 

variable thickness, ranging from 2 to 6% feet; sections were measured at 

localities 271, 280, 282, 283, 299, and 315. A coal bed about 15 feet above the 

Burley bed occurs in the southern part of the township, in sees. 31 and 35. 

The maximum measured thickness of the bed is 21 feet, and its horizontal extent 

is small. Sections were measured at localities 270 and 281.

A small drift mine in the Burley bed, at locality 280, has been operated to 

obtain fuel for local use.

T. 4 N., R. 45 E. An irregular divide, which separates the drainage basins 

of Sweeney and Graveyard Creeks on the northwest and the Tongue River on 

the southeast, extends diagonally across T. 4 N., R. 45 E., from the northeast

ta U. S. Geol. Survey Bull. 341, pp. 36-61, 1907.
104 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

corner. Along the main divide and the minor divides between tributary 

streams the surface is rugged and covered with pine timber. The maximum 

relief is slightly over 400 feet.

The Lebo shale member of the Fort Union formation is exposed in an area 

of about 2 square miles in the southeast corner of the township. The overlying 

Tongue River member crops out in the rest of the township. The red clinker 

in the southwestern part of the township was formed by the burning of the 

Terret coal bed, and that in the northern part by the burning of the Burley 

coal bed.

The Trail Creek zone, which contains the lowest coal cropping out in the 

township, is 19 inches or less in thickness and about 65 feet below the Burley 

bed. Sections were measured at localities 423 and 428. The Burley bed is only

T. 5 N., R. 45 E.

EXPLANATION

Coal

Bony coal 

Bone

Shale

Sandy' 

shale

Sandstone

Clay

PIGDKE 22. Sections of coal beds in T. 5 N., R. 45 E.

about 2 feet thick in the southwestern part of the township but thickens 

to as much as 8% feet in the northern part. Coal sections of the Burley 

bed were measured at localities 225, 227, 228, 231, 234, 277, 279, 411, 413, 414: 

416, 418, 420, 422, and 434. There is a split in the bed at locality 231. At 

locality 277 the split is still present and the lower coal bed has thinned to 7 

feet. Still farther east, at locality 279, the bed is split into three parts. The 

uppermost bed at locality 279 is probably a higher bed, not found at the other 

two localities just mentioned. A local resident states that at locality 273 the 

coal is more than 9 feet thick. At locality 413 four coal beds, each less than 

18 inches thick, occur within 20 feet below the Burley bed. In the southwestern part of the township the Terret bed has burned along most of its 

outcrop. At locality 435 this bed is about 60 feet above the Burley and con-
U. S. GEOLOGICAL SURVEY BULLETIN 847 PLATE 17

T. 4. N., R. 45 E.

Terret coal zone

226 232 233 235 236 269 272 274 275 276 278 407 412 415 417 419 421 429 435

Ft. in. Ft. in. Ft. in. . Ft- >in- Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. FL in. Ft in. Ft. in. Ft. in. ln- Ft- in- Ft. in. Ft. in. Ft. in. Ft. In.

I 3

3 7

|4 3 3 e

Burley bed

225 227 228

Ft. in. In. Ft.

231 234 277 279 411 413 414 416 418 420 422 434

Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. Ft. in. Ft in. Ft. in. Ft. in. Ft. in.

I

efc

ital

I 6

)8 6 B

w 

. _ ia

l(aj

U a r^'8

3}4 21/2

z.Vz V* Hz 2

I («;

3 6

"2 3

i:

15 3

I I 4 

I

t(a) 13 2

Is 6

EXPLANATION 

Coal Bony coal Bone

Carbonaceous Shale Sandy Sandstone 

shale shale

(a) Oxidized coal, therefore 

incomplete section

SECTIONS OF COAL BEDS IN T. 4 N., R. 45 E.

Trail Creek coal zone

423 428

Ft in. Ft. in.

I
U. S. GEOLOGICAL SURVEY BULLETIN 847 PLATE 18

T. 3 N., R. 45 E.

Terret bed Burley bed

222 442 424 431 432 437 439 440 441 443 444 445 446 

^Ft- '" 'l^-J a '"' I I Ft '" I I Ft. in. t^Ft. in. ^ Ft. in. ,__i Ft. in. t_J Ft. in. , _j Ft. in. .^ Ft. in. ,_. , Ft. in. ^ Ft. in.

448 449 450

I &

8 7

2 9

2 3 2 3

I

Trail Creek coal zone

426 . 430 433 436 438 446 447 450

, Ft '" , ,Ft. in. , .Ft. in. .^.j Ft. in. ,__, Ft. in. h.^i Ft in. ,_.Ft , , Ft in.

451

in. i .-< Ft. in.

|2 3

EXPLANATION 

Coal Bony coal Bone

Dirty Carbonaceous Shale 

coal shale

Sandy Sandstone Clay 

shale

(a) Oxidized coal, therefore 

incomplete section

SECTIONS OF COAL BEDS IN T. 3 N., R. 45 E.
, KOSEBUD COAL FIELD, MONTANA 105

tains 7% feet of fairly good coal in two beds separated by 1 foot of impure 

coal near the middle. Northeast of this locality the Terret bed splits into 

several parts. At locality 421 there are three beds in this zone. The separate 

splits of the Terret bed could not be traced individually, so that all the coal 

beds that lie above the Burley bed are included in the Terret zone. The 

coal section at locality 226 includes only one of the splits, but one or more 

splits are probably concealed near it. Coal beds in the Terret zone were 

measured at localities 226, 232, 233, 235, 236, 269, 272, 274, 275, 276, 278, 407, 

412, 415, 417, 419, 421, 429, and 435. The coal included in this zone in sees. 

5, 6, 8, 9, and 10 is about 125 feet above the Burley bed, which is twice 

the interval between the Burley and Terret beds in the southwestern part of 

the township. The Terret zone contains several coal beds, some of which are 

of only local extent, and includes thin beds which are higher stratigraphically 

than the Terret bed and are not connected with it.

The Burley and Terret beds are the only ones thick enough to be minable. 

The Burley bed has not been mined in this township. Areas from a quarter 

of a mile to half a mile wide parallel to the outcrop, with less than 50 feet 

of cover, may offer stripping possibilities. A small amount of coal has been 

mined from the Terret zone at locality 236 in sec. 6. The bed is 4^ feet 

thick, but the area which it underlies near this locality is small.

T. 8 N., R. 45 E. The northwest corner of T. 3 N., R. 45 E., is crossed by 

the divide between the Tongue River and Sweeney Creek, a tributary of the 

Yellowstone River, and the Tongue River flows northeastward across the southeast corner of the township. Near the divide the surface is rugged and the 

steep slopes are covered with yellow pine and juniper. The southeastern half 

of the area is largely grass-covered and more rolling, with, some badlands. 

The maximum relief is about 600 feet.

The Tullock member of the Lance formation crops out in a narrow strip 

along the Tongue River in the southeast corner of the township. The overlying Lebo shale member of the Fort Union formation crops out extensively 

In the southeastern and eastern parts of the townships. The contact between 

the Lebo member and the overlying Tongue River member is generally transitional through, a vertical distance of 20 to 30 feet, but beyond these limits 

the lithologic contrast is marked. Along Cow Creek this transition from 

somber-colored shale to sandstone is irregular. In mapping, the contact has 

been drawn arbitrarily, at the average horizon of lithologic change, rather 

than following the vertical variations. The outcrop of the Tongue River member is confined principally to the higher land in the northwestern part of the 

township. A section of the Tongue River member measured in sec. 18 is 

given on pages 62-63. The two en e'chelon faults in sees. 6 and 7 are described 

on pages 68-69.

The Lebo shale member contains no coal beds of economic value. A bed of 

shale and dirty coal presumably lies at its base, but it was not observed in 

the poor exposures along the Tongue River. Coal beds in the Trail Creek 

zone, which is from 30 to 60 feet above the base of the Tongue River member, 

range from less than 18 inches to 2 feet in thickness. Coal sections were 

measured at localities 426, 430, 433, 436, 438, 446, 447, and 450. At localities 

430 and 433 thin beds occur about 20 feet below the more persistent bed in the 

Trail Creek zone. The coal at locality 447 is 2 feet thick, but the bed is only 

of local extent. The coal in the Trail Creek zone is not of sufficient thickness 

i.o be of economic value. The Burley bed is 40 to 60 feet above the Trail 

Creek zone and is usually from 50 to 60 feet below the Terret clinker. The 

coal is 2y% feet or less in thickness. Sections of the Burley bed were measured
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

T. 2 N.^R. 45 E.

r ^^»i . ^

Trail Creek Local bed. in 

coal zone Lebo member

473 489 

Ft in.

at localities 424, 431, 432, 437, 439, 440, 441, 443 to 446, and 448 to 451. At 

locality 427, which is only 33 feet below the clinker formed by the lower split (?) 

of the Terret bed, the Burley bed is oxidized along its outcrop, so that only a 

red band a few inches thick marks its horizon. Most of the coal in the Terret 

bed has been destroyed by burning, and a thick red clinker has formed above 

it as a result. Some unburned Terret coal may remain in parts of sees. 

5, 7, 8, 15, 16, and 17, but the lateral extent of the bed at any place is small. 

Coal sections were measured at localities 222 and 442.

T. 2 N., R. 45 E. (fractional). The Tongue River, which flows northeastward across T. 2 N., R. 45 E., supplies water for irrigating the fertile bottom 

lands along the northwest side of the river. From the river the surface rises

through a series of gravel-covered terrace remnants 

to the high clinker-capped buttes and ridges in the 

northwestern part of the township. The maximum 

relief is about 500 feet.

The Tullock member of the Lance formation 

occurs only in a very small area in the northeast 

corner of the township. It is overlain by the 

Lebo shale member of the Fort Union, which is 

the surface formation over most of this fractional 

part of the township. The Tongue River member 

caps ridges in the northwestern part of the township but has a total area of outcrop of only about 

2 square miles.

The township contains no coal of economic value. 

No exposures of the dirty coal bed at the base 

of the Lebo were found. At locality 489 a local 

coal bed in the Lebo member contains only 11 

inches of clean coal. A coal section of the Trail 

Creek bed measured at locality 473 shows 2% feet 

of impure coal oxidized in the upper part. In sec. 

7 there may be coal from iy2 to 2 feet thick at the 

Trail. Creek or Burley horizons, but no outcrops

In.

& i 

it

\M

2 6

EXPLANATION

Coal Bony coal Bone

Shale Sandstone Clay

(a) Oxidized coal, therefore 

<iflrwiv incomplete section 

shale

FIGURE 23. Sections of coal 

beds in T. 2 N., R. 45 E.

were found. All of the Terret coal has burned and formed the red clinker in 

sees. 5, 7, 18, and 19.

T. 5 N., R. 46 E. The surface of the greater part of T. 5 N., R 46 E., consists 

of rolling grass lands, but rough badland areas predominate in sees. 3, 4, 

5, and 6, the east tier of sections, and the Sy2 sec. 35. Much of the northwestern half of the township is made up of gently sloping terraces, covered 

with a thin layer of gravel. Rather sharp valleys have been cut in these terrace 

slopes. The maximum relief is about 400 feet.

The upper 40 feet of the Tullock member of the Lance formation crops 

out on Moon Creek, in the northeast corner of the township. The Lebo shale 

member of the Fort Union formation, which is 190 to 220 feet thick and consists principally of somber-colored shale, although locally thick beds of sandstone occur in it, crops out in about half of the township. The contact 

between the Lebo and Tongue River members of the Fort Union is marked 

over much of this township by a thin coal bed. The Tongue River member 

crops out in the southern and western parts of the township. This township 

is also described in the report on the Miles City coal field.44

«U. S. Geol. Survey Bull. 341, pp. 36-61, 1907.
ROSEBUD COAL FIELD, MONTANA 107

T. 5 N., R. 46 E.

Bed at base of 

Tongue River member

''300 307 312 313 320 322 323 324P

| Ft in. __ Ft in. __ Ft. in. Ft in. gsj| In. Ft in. __ Ft in. __Ft. in.

1 ' ( 5 H> 3 I I

I

Lebo member 

301

325 r , 326,. . 327,. . 328 379 381 386

, FL '« . , FL '" , , Ft '" , i Ft in. Ft in. Ft. in. s=. Ft in.

2 2 H2 2

Bed 90 to 100 ft. 

below top of Lebo

^302 314 , 317 318 ft In. .a .Ft'ln. OUD Ft in. .*». Ft in. . .Ft in. -"Ft in. Ft in,

2 10

319 321 329

I Ft in. Ft in.

2 8

330 331 333 335 337

Ft In. ^Ft in. .._Ft in. __ '" __ Ft in.

380 385 387

Ft. in. bseiFt in.

Coal Bony coal Bone Dirty Carbonaceous 

coal shale

..Shale Sandstone Clay

FIGORB 24. Sections of coal beds In T. 5 N., R. 46 E.
108 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

In general the strata are flat-lying, but dips of 30 to 45 minutes were measured between localities 333 and 337. It is difficult to ascertain the structure, 

because of the lack of a persistent horizon. In sec. 25 there is an indication 

of a small arch. These slight dips probably become insignificant with depth.

In the N% sec. 4 there has been some deformation during sedimentation. 

Small superficial faults of short horizontal and vertical extent are associated 

with beds dipping at a maximum of 45°. The steep dips persist for only a 

few feet. Some thin coal beds end abruptly against sandstone, at some 

places; cut by an old stream channel and in other places terminated by slight 

displacement. Extreme cross-bedding is common. Compaction after deposition 

may also have caused some of the displacements and irregularities.

The Tullock member of the Lance formation does not contain any coal 

over 18 inches thick at outcrops in this township; a section of a thin local 

bed about 40 feet below the top of the Tullock was measured at locality 304. 

The coal bed at the base of the Lebo member of the Fort Union formation, 

which is approximately equivalent to bed C of the Miles City coal field and 

the Big Dirty bed, crops out along Moon Creek, in the northeast corner of 

the township, and at the southern edge of sec. 36. The coal is of poor 

quality, as shown by the sections measured at localities 305, 308, 334, and 

388. At locality 384, in the township adjoining on the south, this bed contains 

4 feet 3 inches of fair coal, but it changes to impure coal a short distance 

from that locality. A coal bed, which is equivalent to bed D of the Miles 

City coal field, occurs 90 to 100 feet below the top of the Lebo member. 

Its average thickness is about- 2% feet, but it is very dirty and only locally 

contains coal of fair quality. It thins out in sees. 1 and 12. Coal sections 

were measured at localities 302, 303, 306, 309, 310, 311, 314, 317, 318, 319, 

321, 329, 330, 331, 333, 335, 337, 368, 380, 385, and 387. A local bed 28 feet 

below the top of the Lebo member was measured at. locality 301. The 

coal at the base of the Tongue River member is thickest in sees. 25 and 36, 

where its average thickness is about 2 feet 2 inches. Elsewhere in the 

township it is less than 18 inches thick. Sections were measured at localities 

300, 307, 312, 313, 320, 322 to 328, 379, 381, and 386.

T. 4 N., R. 46 E. The Yellowstone-Tongue River divide extends a little 

north of east through the northern tier of sections in T. 4 N., R. 46 E. Moon 

Creek drains the small area north of this divide, and the area south of it is

drained by southeastward-flowing tributaries of the Tongue River. In the 

northern and northwestern parts of the township the surface is rolling and 

grass-covered and some land is under cultivation; the surface of the remainder 

of the township is largely badlands with considerable relief. The maximum 

relief is 500 feet.

The Tullock member of the Lance formation is exposed along the Tongue 

River and the lower parts of its tributaries, in the southeastern part of the 

township. The Lebo shale member of the Fort Union formation, from 170 

to 200 feet thick, forms the surface rock over half of the township. The 

lower part of the Tongue River member of the Fort Union formation crops 

out principally on the divide in the northwestern part of the township.

No coal 18 inches or more in thickness was found in the Tullock member. 

At locality 406, about 100 feet below the top of the Tullock member, 8 feet 

of carbonaceous shale with streaks of coal is exposed on the north side of 

Forest Creek. The coal at the base of the Lebo member is generally so dirty 

that it can be disregarded as a source of coal. The bed contains the best.
ROSEBUD COAL FIELD, MONTANA 109

 coal at locality 396, where there is 5 feet 3 inches of somewhat impure coal,

 but coal of this thickness is of only small lateral extent. Sections on this 

Tjed were also measured at localities 395, 400, and 401. The Burley bed 

underlies only a small area in sees. 6 and 7. At locality 316 only thin 

'beds of coal were found at the Burley horizon. In the township west of this 

one the Burley bed contains as much as 8 feet of coal, but measured sections

 show that it splits into three parts and becomes thinner toward the east. 

'The Burley bed is probably not more than 2 feet thick in this township. At 

locality 410 there are several coal beds from 6 inches to a foot 'thick in the 

'Tongue River member.

T. S N., R. 46 E- The Tongue River flows northeastward across the center 

of T. 3 N., R. 46 E. BeT. 4 N VR. 46 E. f .A. . . .

Bed at base of Lebo member Local bed about 100 ft' 

x below top of Tullock 

406

yond the flood plain in

 .the northwest half of the

 township the surface is 

largely badlands. Gravel-

 covered benches are present for a few miles southeast of the Tongue River. 

'The maximum relief . is 

.about 450 feet.

The Tullock member of 

the Lance formation crops

 out in a narrow strip 

along the Tongue River 

and extends a few miles 

up the tributary valleys. 

The overlying Lebo shale 

member of the Fort Union 

formation, which is about 

170 feet thick, is the sur- 

:face rock jn most of the 

remaining area of the 

township. The Tongue 

Hiver member of the Fort 

Union formation crops

 out in a small area in the 

southeastern part of the

 township.

. The coal that occurs from 40 to 160 feet below the top of the Tullock mem- 

'her is so lenticular that any single bed is traceable for only a short distance. 

For convenience in treatment it is grouped into a single bed, but in reality it is 

a coal zone. The coal at localities 409, 553, and 556 is 40 to 70 feet lower 

stratigraphically than the coal indicated by the outcrop line on plate 11 at 

localities 408, 425, 557, 559, 566, and 568. The coal indicated by the outcrop 

line is a discontinuous bed 40 to 110 feet below the top of the Tullock. A small 

.amount of coal has been taken out at locality 566 for local supply. A coal bed 

&t the base of the Lebo was measured at localities 558, 560, and 561, where it 

had a maximum thickness of 22 inches. The outcrop of a local bed about 85 

feet below the top of the Lebo member is not shown on the map, inasmuch as 

the bed varies a great deal in thickness; sections measured at localities 554 and

Carbonaceous Shale 

shale

Sandy Sandstone Clay 

shale 

FIGURE 25. Sections of coal beds in T. 4 N., R. 46 E.
110 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

555 show that it is between 14 inches and 2 feet thick, 

in the Tongue River member has burned.

T. 3 N., R. 46 E. 

, * ^

Local bed 85 ft. Bed at base of Lebo member 

below top of Lebo member

_____ ,A.____________ ______________s\.________________

554 . 555 . 558 _ . 560 561

Ft. in. Ft. in. Ft. in. Ft in. Ft in.

AH of the Terret coal

I 6

10

Beds 40 to 160 ft 

below top of Tullock

409 425 . 553 556

rfLJE: ^Ft '" >,,, ,, Ft in. __Ft in.

 ..= -'

|2 4

EXPLANATION 

Coal Bony coal Bone

8 Dirty Carbonaceous Shale

coal shale

I 5 t -d i -rd

Sandy Sandstone 

shale

FIGURE 26. Sections of coal beds in T. 3 N., R. 46 E.

T. 5 N., R. 47 E. The Tongue River flows northeastward across the southeast corner of T. 5 N., R. 47 E. With the exception of the bottom lands along 

the river, the surface of the township is rough and deeply dissected by erosion. 

Badlands are common. The maximum relief is about 525 feet.

The Tullock member of the Lance formation crops out on both sides of the 

Tongue River and is the surface formation in more than half of the township ; about 230 feet of this member is exposed. The Lebo member, composed 

of about 200 feet of somber-colored shale, with some sandstone beds and ironstone concretions, overlies the Tullock member and crops out in the western 

part of the township. An irregular, dirty coal bed is arbitrarily taken as the 

base of the Lebo, for the Lebo and Tullock are very similar in appearance, and 

any boundary line between them is an artificial one. The Tongue River member 

of the Fort Union formation crops out in areas of moderate extent in the west-
TJ. 8 GEOLOGICAL SURVEY BULLETIN 847 PLATE 19

T. 5 N., R. 47 E.

Local bed 20 ft. Bed at base of 

above base of Tongue Riv8r member

Bed 90 to 100 ft. 

below top of Lebo

Tongue River member 

339

rt. in.

332

Ft in. 

I 2

336 338 343 364 365 

Ft. in. Ft. in. K3 Ft. in. __ Ft. in. 

6

369 376

Ft. in. r^J Ft. in

2 9

Bed at base of Lebo member

340 342 351 353 354 359 361

. Ft. m. VBT-H Ft. in. MR Ft. in. . .Ft in. Ft. in. .,...,. Ft. in.

I 5

366 370

Ft in. Ft in.

|3 6

7

ll 7

19 6 

I

ll 6

3 6

Bed 50 to 110 ft. 

below top of Tullock

, Ft. in. 344 347 348

Ft in.

2 2

350

Ft. in. 

9

352

2 4

Local beds 70 to 130 ft. 

below top of Tullock

345 . 346 ,, . 356 ,. . 

, Ft. in. _I,R. m. ..,...,., Ft in.

I 8

Local bed about 

30 ft. below 

top of Tullock

373

Ft. in.

9 

7

5

II 7

8

5

355 357 r 360 363

Ft. in. __ Ft in. . Ft. in. _,.., Ft. in.

371 372

I 7

I 3

I 8

Local bed 175 ft. 

below top of Tullock

358 Ft in. 362.Ft. i.

3 7

ll 9

2 2

I 

I I 3

EXPLANATION

 

ESB OE f&z^

Coal Bony coal Bone

Dirty Carbonaceous Shale 

coal shale

Sandy Sandstone Clay 

shale

(a) Oxfdized" coal, therefore 

incomplete section

SECTIONS OF COAL BEDS IN T. 5 N., R. 47 E.

Ft. in.

6

9

4

4*
EOSEBUD COAL FIELD, MONTANA 111

ern part of the township. This township is also described in the report on the 

Miles City coal field.46

Several coal beds occur in the Tullock member, but they are not of economic 

value. A local coal bed about 175 feet below the top of the Tullock, which 

crops out only on Thorp Creek, contains the best coal in this township. Sections were measured at localities 358 and 362; at locality 362 it contains 3 

feet 7 inches of coal, but to judge from the other coal beds in the Tullock 

member, this bed probably does not extend very far horizontally without 

becoming of poorer quality. Sections of local beds 70 to 130 feet below the 

top of the Tullock were measured at localities 345, 346, and 356, and a local 

bed about 30 feet below the top of the Tullock was measured at locality 373, 

but their outcrops were not mapped. The coal bed 50 to 110 feet below the 

top of the Tullock is a coal zone rather than a single persistent bed; the 

locations of the discontinuous beds in this zone are represented on plate 11 

by a continuous line of outcrop. The coal is variable in thickness and quality 

and only locally is over 2 feet thick. The small partings, bone, and shale in 

the coal render it of little value as a coal bed. Sections were measured at 

localities 341, 344, 347 to 350, 352, 355, 357, 360, 363, 371, 372, and 374. A 

bed at the base of the Lebo consists of 21/£ to 3 feet of carbonaceous shale, 

with thin beds of impure coal. Only locally does it contain 18 inches of fair 

coal. The sections measured at localities 340, 342, 351, 353, 354, 359, 361, 366, 

and 370 show the character of this bed. The coal bed 90 to 100 feet below the 

top of the Lebo, which is equivalent to bed D of the Miles City coal field, is 

also impure and of little value. Sections were measured at localities 332, 

336, 338, 343, 364, 365, 367, 369, 376, and 378. Parts of this bed have burned 

in the southwestern part of the township and formed a clinker. The coal 

at localities 364 and 365 is grouped with the bed 90 to 100 feet below the 

top of the Lebo, but actually it is lower stratigraphically and probably represents small local beds.

A coal bed at the base of the Tongue River member occurs in parts of sees. 

30 and 31 and is from 1 foot 9 inches to 2 feet 2 inches thick. A section was 

measured at locality 375. A local bed about 20 feet above the base of the 

Tongue River member is of small horizontal extent and only 2 feet thick. A 

section was measured at locality 339.

T. 4 N., R. 41 E. The Tongue River flows northeastward across the middle 

of T. 4 N., R. 47 E. Except for the alluvial bottom land along the river, the 

surface of the township is rough. Badlands are common in the northwestern 

and southeastern parts. The maximum relief is about 450 feet.

About 240 feet of the Tullock member of the Lance formation is exposed in 

the Tongue River Valley. The Lebo shale member of the Fort Union formation crops out in the northwestern and southeastern parts of the township.

A local coal bed in the Tullock, 35 feet below locality 614, contains 3% feet 

of coal. Coal at this horizon also crops out in the bed of the Tongue River at 

locality 615, 25 feet below the Tullock bed shown on the map at locality 611. 

At the outcrop in the Tongue River near locality 611 there is about 3 feet of 

good coal, partly covered by water. A coal bed about 200 feet below the top of 

the Tullock is mapped in sees. 10, 12 to 16, and 23. The cleanest and thickest 

coal in this bed is at locality 611. Sections were measured at localities 382, 

392, 610 to 614, 616, 617, and 618. The coal thins to less than 18 inches northeastward across sec. 13. Another local bed, about 130 feet below the top of the 

Tullock, that crops out a few feet above the Tongue River was measured at

45 U. S. Geol. Survey Bull. 341, pp. 36-61, 1907.
112 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

locality 403. It is concealed by alluvium and therefore traceable only a short 

distance. A local coal bed 40 to 70 feet below the top of the Tullock is mapped 

in the southwestern part of the township. The coal is discontinuous, impure, 

and variable in thickness. Sections were measured at localities 402, 404, 405, 600, 

608, and 609. A coal bed at the base of the Lebo is present only in the northwestern part of the township. Locally it contains a thickness of several feet 

of fair coal, but generally the bed is dirty and contains several partings. Sections were measured at localities 377, 383, 384, 389, 390, 391, 393, 394, 397, 398, 

and 399. Above localities 608 and 609, in sec. 28, a coal bed near the base of 

the Lebo was measured. This bed is 22 feet above the bed at locality 608; it 

contains 2 feet 3 inches of coal but its horizontal extent is small. About 16 

feet above this bed, at locality 609, is a bed of coal 10 inches thick. A local bed 

135 feet below the top of the Lebo, measured at locality 607, in sec. 35, contains 22 inches of coal with a 6-inch parting.

A few wagon loads of coal a year are taken from the bed that crops out in 

the Tongue River near localities 611 and 615. The bed at the base of the Lebo 

has been prospected at locality 384.

T. 3 N., R. 1ft E. The Tongue River flows northeastward through the northwest corner of T. 3 N., R. 47 E., and the township is drained by northwestwardflowing tributaries of the river. The surface of the township is rough and 

broken. Badlands are common in the central and northeastern parts and are 

present to a lesser extent elsewhere. Steep-sided clinker-capped buttes rise 

above the surrounding surface in the eastern and southeastern parts of the 

township. The total relief is about 450 feet.

The Tullock member of the Lance formation crops out along the Tongue 

River and along numerous smaller valleys near the north and west sides of the 

township. The Lebo shale member of the Fort Union formation crops out in 

the greater part of the township. The lower part of the member is similar 

in lithology to the underlying Tullock beds. The Tongue River member of 

the Fort Union formation is present in the eastern part of the township and 

extends northwestward along the divides.

The local coal bed 70 to 110 feet below the-top of the Tullock, which crops 

out in the extreme western part of the township, is discontinuous, is variable 

in thickness and purity, and does not include an important reserve of coal. 

Clean coal 18 inches thick is of only local horizontal extent. Sections were 

measured at localities 565 and 569 to 575. A local bed 60 feet below the top of 

the Tullock was observed only at locality 567, in sec. 18; the bed is only 

22 inches thick and was not mapped. Sections of a local bed about 130 feet 

below the top of the Lebo were measured at localities 577, 589, 597, 598, and 

599, but the coal is generally of poor quality; the thickest coal in this bed is 

20 inches thick where it is unbroken by partings. The Tongue River member 

 contains the thickest coal beds in the area, but they are of slight horizontal 

extent and are usually burned along their outcrops. A local bed at the base of 

the Tongue River member was observed only at locality 576. The Foster bed, 

which is about 28 feet below the Terret bed, in places consists of two beds 3 

to 5 feet apart. The total coal ranges from 1 foot 9 inches to 4% feet; the 

maximum measured thickness of coal not separated by partings, however, is 

2 feet 10 inches. The Foster bed is generally unburned along the outcrop. 

Sections were measured at localities 564, 578, 580, 587, 588, 594, 595, 601, and 

602. The Terret bed is the thickest coal bed in this township, but it is of small 

horizontal extent. Burning along its entire outcrop has further reduced the 

quantity of available coal. The area underlain by the Terret coal consists of 

isolated outliers and narrow strips on and in the interstream divides. The
U. S. GEOLOGICAL SURVEY BULLETIN 847 PLATE 20

T. 4 N., R. 47 E.

Local bed 135 ft. 

below top of Lebo Bed at base of Lebo member

Local bed about 130 ft, 

below top of Tullock

403.. . j Ft. in.

Local bed 40 to 70 ft. below top of Tullock

405 Ft. in.

I 9J2

. Ft. in. 

Z

3 2

608

3 6

Local bed about 200 ft. 

below top of Tullock

Local bed 35 ft. 

below locality 614

3 6

" in. 0 Ft in. 6U R jn

EXPLANATION 

Coal Bony coal Bone

Dirty Carbonaceous Shale 

coal shale

Sandstone Clay 

SECTIONS OF COAL BEDS IN T. 4 N., R. 47 E.
U. 8. GEOLOGICAL SURVEY BULLETIN 847 PLATE 21

T. 3 N. R. 47 E.

Haddow bed

562

Ft. in.

563 579

Ft. in. ._ Ft. in.

596

3 6 3 6

I 10

I 9

Foster bed Bed at base of 

Tongue River member

603 564 578 580 587 588 594 595 601 602 576

Ft. in. . Ft. in. . Ft in. . .Ft. in. .__Ft In. .__.Ft. In. i__.ft. in. ,__, Ft. in. , , Ft. in. ......Ft in. ,....., Ft. in,

Z 7

\2 10

3 6

2 5

Local bed about 130 ft. below top of Lebo member

Local bed 

60 ft. below 

top of Tullock

Local beds 70 to 110 ft. 

below top of Tullock

577 589 597

Ft. in. ,__ Ft. in.

598 599 . 567 565 569 570 571 572 573 574 575

» in. H- in. . .. ...Ft in. Ft. in. ,_Ft. in. Ft in. Ft. in. Ft. in. Ft in. Ft.

2 9

EXPLANATION 

Coal Bony coal Bone

Dirty Carbonaceous Shale 

coal shale

Sandy Sandstone Clay 

shale

1 4

7

2 3

I 3

I 6

SECTIONS OF COAL BEDS IN T. 3 N., R. 47 E.
ROSEBUD COAL FIELD, MONTANA 113

exact area of available coal in this bed is undetermined, because the limit of 

burning is unknown. Inasmuch as the areas are small and not easily accessible, 

the coal in this bed in this township is not considered of as much value as the 

measured sections might indicate. The bed is between 5% and 9 feet thick. 

Sections were measured at localities 563, 579, 596, and 603. The Terret bed is 

present in parts of sees. 13, 24, 25, 35, and 36. The Haddow bed, named 

from Haddow Creek, is present in only small areas in sec. 13 and the eastern 

part of sees. 24, 25, and 36. At locality 562, which is 300 feet south of the 

south line of sec. 36, the Haddow bed contains 5% feet of coal, but it thins 

northward and eastward from this locality. At locality 585, in sec. 30, T. 3 N., 

R. 48 E., it contains only 2 feet of coal. The Haddow bed contains between 

2 and 5 feet of coal in a small area in the eastern part of sec. 36. In the 

remaining areas in this township in which it occurs this bed is probably not 

much over 2 feet in thickness, and perhaps less. The Haddow bed is about 

50 feet above the Terret bed.

T. 5 N., R. 48 E. The Tongue River flows northeastward across the northwest 

corner of T. 5 N., R. 48 E., and the surface of the township is drained by several 

of its northwestward-flowing tributaries, including Pumpkin Creek, which crosses 

the northeast corner of the township. Except for the broad alluvial flat along 

the Tongue River and the valley floor of Pumpkin Creek, the surface of the 

township is deeply dissected by erosion. Badlands are common, and vegetation 

is scarce. The maximum relief is about 540 feet.

The Tullock member of the Lance formation crops out over much of the township. The Lebo member of the Fort Union formation is between 160 and 190 

feet thick and crops out extensively between Nelson and Pratt Creeks and between Pratt and Pumpkin Creeks. The Tongue River member is present in a 

small area in sees. 22 and 23, and a few remnants occur in sec. 36. This 

township is also described in the report on the Miles City coal field.48

A local bed about 250 feet below the top of the Tullock, which crops out at 

locality 664, on Pumpkin Creek in sec. 3, contains 2 feet of clean, solid coal, 

the best coal found in this township. A coal bed 45 to 85 feet below the top of 

the Tullock member occurs in the north-central part of the township and in small 

areas in sees. 30 and 32. Generally the bed is about 70 feet below the top of 

the Tullock and consists of 1 to 2 feet of coal in an impure coal and shale bed. 

The thicknesses of over 5 feet at localities 645 and 657 are exceptional arid are 

only of local extent. The coal in the upper part of the Tullock may be completely 

absent in places and reappear at a slightly higher or lower horizon; consequently, 

this coal, which is represented as a single bed on the map, is really a zone with 

a maximum thickness of 40 feet. Sections were measured at localities 642, 645, 

654, 655, 657, 658, 660, 662, 663, 665 to 668, 670, and 673. A bed at the base of 

the Lebo is extremely variable in purity and thickness. The large amount of 

shale and bone in the bed render it of little value. Sections were measured at 

localities 641, 643, 644, 648, 650 to 653, 656, 659, 661, 669, 671, and 672. A coal 

section of a series of local beds in the Lebo was measured at locality 649; each 

bed of coal is less than 18 inches thick. The lowest coal is about 30 feet above 

the base of the Lebo.

The coal at locality 657 has been prospected, but none of the coal in this 

township is mined.

T. 4 N., R. 48 E. The Tongue River flows northeastward across the northwest 

corner of T. 4 N., R. 48 E. Northwestward-flowing tributaries of the river have 

cut deep valleys which are separated by sharp narrow divides. Badlands are 

common in this township. The maximum relief is about 500 feet.

« U. S. Geol. Survey Bull. 341, pp. 36-61, 1907.
114 CONTRIBUTION'S TO ECONOMIC GEOLOGY, 1934-36

T. 5 N., R. 48 E.

Local bed with 

lowest coal about 30 ft. 

above base of Lebo member 

649

Bed at base of Lebo member

644 :. 648 r. :. 650 c. :. 651 r. :- . 652

Coal zone 45 to 85 ft. 

below top of Tullock

.642 ft , 645 iB 654 , 655 ,. . 657 c, , 658 et . 660 Ft. in. OJt* Ft. in. ^1 Ft. in. 1OJ/. Ft. In. "-J ° Ft in. ^1 Ft in. ^±. Ft in. 662

Local bed about 250 ft

below top of Tullock 

673 664 Ft

EXPLANATION 

Coal Bony coal Bone

Dirty Carbonaceous Shale 

coal shale

Sandy Sandstone Clay 

shale

FIGURE 27. Sections of coal beds in T. 5 N., R. 48 E.
ROSEBUD COAL FIELD, MONTANA 115

The Tullock member of the Lance formation crops out in the valleys of Ash 

and Nelson Creeks and the Tongue River. The Lebo shale member of the Fort 

Union formation, from 160 to 180 feet thick, crops out on the divides between 

the tributary streams of the Tongue River. The Tongue River member is 

present in small areas in the eastern part and the southwest corner of the 

township.

A local bed about 100 feet below the top of the Tullock, measured at locality 

619, in sec. 35, is of little value because of the impurity of the coal. The 

extent of another local bed about 220 feet below the top of the Tullock memT. 4 N., R. 48 E.

Bed at base of 

Lebo member

646

Local bed about 100 ft. 

below top of Tullock

619 634 635 636

.Ft. In. . .Ft In. __Ft In. _ .Ft tn. EXPLANATION

HH IwiSfl

Coal Bony coal

Carbonaceous Shale 

shale

Sandstone Clay

Local bed about 220 ft. 

below top of Tullock

FIGURE 28. Sections of coal beds In T. 4 N., R. 48 E.

her, in sec. 6, is concealed by alluvium; at locality 633 it contains 3 feet 2 

inches of coal. A local coal bed about 100 feet below the top of the Tullock is 

mapped in sees. 1, 2, 3, 11, and 12. At locality 638 it contains 5 feet 2 inches 

of coal. At locality 645, a few hundred feet north of sec. 1, this bed is 5 

feet 8 inches thick, but the coal is somewhat impure. Sections were measured 

at localities 634 to 640. East of the east township line this bed becomes very 

impure. A measured section at locality 647, T. 4 N., R. 49 E., is shown in 

figure 31. A coal bed at the base of the Lebo was found only in sec. 1; a section 

was measured at locality 646.
116 CONTBIBUTIOE'S TO ECONOMIC GEOLOGY, 1934-36

None of the coal in this township is mined. The local bed about 100 feet 

below the top of the Tullock in the northeastern part of the township and thelocal bed in sec. 6 contain the best coal.

T. 3 N., R. 48 E. ln the northeastern half of T. 3 N., E. 48 E., there are 

several wide, gravel-covered terraces surmounting areas of badlands. Thesurface rises toward the southwest to clinker-capped buttes and ridges. The' 

total relief is about 500 feet.

The upper part of the Tullock member of the Lance formation crops out. on. 

Ash Creek, in the northeastern part of the township. The overlying Leboshale member of the Fort Union formation also crops out extensively in thenortheastern half of the township. The Tongue River, member of the Fort 

Union crops out in the southwestern half and contains all the coal beds of 

any economic value.

Sections of the coal bed at the base of the Lebo were measured at localities 621, 622 and 632. The coal is very dirty and of little value; The Fosterbed, about 120 feet above the base of the Tongue River member in the southwestcorner of the township and 70 feet above the base :3 miles to the north, is in. 

few places over 18 inches thick and generally consists of two thin bedsseparated by 1 to 5 feet of shale. It is present only in.parts of some of the 

western tier of sections of this township. 'In sec. 30 the Foster bed is 27 

feet below the Terret; north of this section the interval decreases to 16 feetCoal sections were measured at localities 584, 590, 604, 605, 606, and 620a. 

The Terret bed, the thickest and most valuable coal bed in the township, isburned along most of its outcrop. It is about 9 feet thick in parts of sees.. 

17 to 20, 28, and 29 to 33, and apparently thins rapidly east of'locality 626.. 

Sections were measured at localities 581, 583, 591, 593, 620, 624 to 627, 629, 

and 630. The Flowers bed, which lies above the Terret, is also clinkered'. 

along its outcrop. The interval between it and the Terret bed decreases to 

the northeast. In the southwest corner of the township this interval is 80' 

feet; it decreases to 70 feet and finally to 50 feet in the northwestern part of 

the township; and it decreases eastward to 35 feet at locality 626. The Haddow 

bed is not a valuable coal bed in this township. The average thickness isbetween 2 and 3 feet. It thickens southwest of this township; at locality 

562, in sec. 1, T. 2 N., R. 47 E., it is 5% feet thick. The Haddow bed 

is 25* to 30 feet below the Flowers; it is mapped only on the west side of thedivide, in sees. 19, 30, 31, and 32. The Flowers bed is about 150 feet above 

the base of the Tongue River member and is the highest coal in this township.. 

It has burned along its entire outcrop, so that 'measurements of its thickness 

are difficult to obtain. Areas of workable coal in this bed are present on thedivide in parts of sees. 19, 20, 27, 28, 29, 32, 33, and 34. The average 

thickness of the bed is nearly 8 feet. Coal sections were measured at localities 586, 592, and 623. .

Coal is mined in the fall from the open pits on the Terret bed, in the Southwest corner of sec. 32, at locality 581, to obtain fuel for local consumption. 

The mine is made accessible by a poor road up Haddow Creek. An area in 

sec. 20, which is underlain by the thick Terret bed under less than 60 

feet of cover, may be suitable for open-cut mining. A small area of the 

Flowers bed in the SW^ sec. 33 is overlain by less than 50 feet of cover.

T. 5 N., R. 49 E. Pumpkin Creek, meandering a great deal in its narrow 

flood plain, flows northwestward across T. 5 N., R. 49 E. A strip of alluvium 

about half a mile wide is present along the creek, but is not shown on 

plate 11. Badlands are common in the southwestern and northeastern parts - 

of the area. The maximum relief is about 375 feet. .
ROSEBUD COAL FIELD, MONTANA 

T. 3 N., R. 48 E.

117

Flowers bed Haddowbed

586 592 

, Ft. in.

8 S,-

Terret bed

581 583 

...i Ft. In. .. .Ft

591

593 620 624 625 626 r 627 629 c ' 630

Ft. in. ,_ Ft. in. ,Ft. in. ,.., .;, Ft. in. __ Ft. in. 1 Ft. in. __ Ft in. Ft in.

a la^a 3

I

2 2

Foster bed Bed at base of Lebo member

EXPLANATION

Coal Bony coal Bone Carbonaceous Shale Sandy Sandstone Clay 

shale shale

FIGUBB 29. Sections of coal beds in T. 3 N., R. 48 E. 

692 36 6
118 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

t. 5 N.^R. 49 E.

Bed 50 to 75 ft 

above base of Lebo member Bed at base of Lebo member

 697 . 700 . 676

, Ft in. ._. Ft in. '683 , 689 690,

Local beds 35 .'to 75 ft 

below top of Tullock

677 682 in. Ft in. Ft in. Ft in. Ft in. Ft in. Ft in. .*. 692 696 **

I 7

Iwai bed about 200 ft 

IreJowtopof Tultock

701

I

EXPLANATION

H^H ^^^a JP^jM

Coal Bony coal Bone

Dirty Carbonaceous Shale 

coal shale

Sandy Sandstone Clay 

shale '

3 3'

FIGURE 30. Sections of coal beds in T. 5 N., R. 49 E.
ROSEBUD COAL FIELD, MONTANA 119

The Tullock member of the Lance formation, which contains a coal zone 

from 85 to 70 feet below the top, crops out over most of the township. The Lebo 

shale member of the Fort Union formation crops out in the northeastern and 

southwestern parts.

A local coal bed about 200 feet below the top of the Tullock member is 

incompletely exposed on Johnson Creek at locality 701, in sec. 6, but contains 

2 feet of fair quality coal. The coal in the zone 35 to 75 feet below the top 

of the Tullock is variable in thickness but is generally between 2 and 3 feet 

thick and rather impure. Although the coal in this zone is discontinuous, it 

is grouped in figure 30 as a single bed. It occurs in the northeastern and southwestern parts of the township and in several isolated areas. Sections were 

measured at localities 674, 675, 677, 678, 682, 688, 692, 696, and 699. A coal

T. 4 N., R. 49 E.

Local bed in 

Lebo member

679 _, . 685 686

i Ft. in. t^j Ft. in. _ _ Ft. in.

2 6

I 3

Bed at base of Local bed about 100 ft. 

Lebo member be|OW top of Tullock

680

Ft. in.

EXPLANATION

Coal Bony coal Carbonaceous 

shale

3 z.

Shale Sandstone Clay 

FIGURE 81. Sections of coal beds in T. 4 N., R. 49 E.

bed at the base of the Lebo, which is present in the northeastern and southwestern parts of the township, is generally dirty and of little value. Sections 

were measured at localities 676, 681, 683, 689, 690, 691, 693, 694, 695, and 698. 

A coal bed from 50 to 75 feet above the base of the Lebo crops out in sees. 1, 11, 

and 12. It has burned along most of its outcrop and produced clinker. Because of the small area underlain by coal in this bed, it is not of value as a 

source of coal in this township. Sections were measured at localities 697 and 700.

T. 4 N., R. 49 E. The divide between Pumpkin Creek and the Tongue River 

crosses the western part of T. 4 N., R. 49 E. The surface of the divide is a 

rolling upland with a few clinker-capped buttes rising above the general level. 

Areas of badlands occupy the greater part of the rest of the township. The 

maximum relief is about 650 feet.

The Tullock member of the Lance formation crops out along the valleys on 

the north and east sides of the township. The Lebo member of the Fort Union 

formation, which is the surface formation in the greater part of the township, 

is composed of 180 to 200 feet of somber-colored shale with local lenses of sandstone. The lithology of the Tullock and Lebo is so similar that any boundary 

between them is an artificial and arbitrary one. The Tongue River member of 

the Fort Union formation is present on the divide in the west half of the 

township.
120 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1934-36

A section of a local coal bed about 100 feet below the top of the Tullock 

was measured in sec. 7, at locality 647. The bed is less than 18 inches 

thick, but it may thicken westward. . (See T. 4 N., R. 48 E.) The coal bed at 

the base of the Lebo contains less than 18 inches of coal, except near locality 

680. Here it contains 5 feet of coal that is impure, but this thickness is only 

of local extent. At locality 681, in sec. 32, T. 5 N., R. 49 E., this bed has 

thinned to 3 feet 7 inches and the coal is dirty. Sections of local beds in the 

Lebo were measured at localities 679, 685, and 686, but the beds are thin 

and of no value. The bed at locality 679 is aboUt 40 feet above the base of the

Lebo; the beds at localities,"685 and 686 are 

. _____T. 3 N.^R. 49 E.____ about 60 and 1001 feet, respectively, below the

Local hPrt in o j ,.,. <. ' top of the Lebo. Local bed m Bed at base of Lebo member m,. , Lebo member ^____^_____ Thig township contains very little coal,

and none of it is mined. The coal bed near 

i. the east line of sec. 4 has been prospected.

T. S N., R. 49 E. The highest parts of the 

surface of T. B N., R. 49 E., are the clinkercapped buttes and ridges on the divide between Pumpkin Creek and Ash Creek, in the 

western part of the township. The west 

slope of the divide is steep and cut into badlands at several places. The slope east of the 

divide is fairly steep, but mostly grasscovered, with scattered areas of badlands. 

Along the west side of Pumpkin and Ash 

Creeks there are broad areas of smooth

EXPLANATION terrace topography. Very few of the original 

W£ B section corners were found, so the section

i o i ^ ^^ lines shown on plate 11 are only approximate. Coal Bony coal Carbonaceous , rr, , . * ., \ f

shale Tne Tullock member of the Lance forma-

^_^ tion crops out on Pumpkin Creek in the east111 px] ern part of the township. The contact beShale Sandstone tweeh the Tullock and the overlying Lebo

FIGURE 82.-Section8 of coal beds member of the Fort Union formation * arbi'

m T. 3 N., R. 49 E. trarily drawn 200' to 220 feet below the top

of the Lebo, but is of little significance or

importance for recognition in the field. The Tongue River member crops out on 

the divide between Ash and Pumpkin Creeks and in the southwest corner of 

the township. A section of the Tongue River member measured at locality 

631 is given on pages 63-64.

No coal beds containing 18 inches or more of clean coal were found in this 

township. A section was measured on a local bed in the Lebo at locality 628. 

The coal at the base of the Lebo, measured at localities 684 and 687, is too 

impure to be of value as a fuel.

A very small amount of coal has been taken from a local bed about 75 feet 

below the top of the Lebo in the Cabin Creek and Rough Creek Valleys. This 

bed is less than 18 inches thick.

 '. ..,." ' O . : :