GEOLOGY OF THE UPPER STILLWATER BASIN, STILLWATER 

AND CARBON COUNTIES, MONTANA, WITH SPECIAL REFERENCE TO COAL AND OIL.

By W. R. CALVERT.

INTRODUCTION.

In 1907 a coal field on the west side of the Bighorn Basin, Wyo., 

was examined by the United States Geological Survey, and the 

investigation was extended northward to include the coal-producing 

area in the vicinity of Red Lodge, Mont. Mapping was discontinued 

at Rock Creek, however, and no definite information was obtained 

relative to the westward extent of the coal field beyond that stream. 

Coal had been reported at Nye, on Stillwater River, and it was considered possible that this coal bed and some one of those developed 

at Red Lodge were identical. In 1908 the writer extended the investigation of the previous year westward from Red Lodge with the 

idea of ascertaining whether the coal beds at Red Lodge and at Nye 

are of the same geologic age and whether they are continuous in the 

intervening area.

Time has not been available from 1908 until now to prepare for 

publication the data obtained in the field examination. In consequence the notes on the coal development here given are incomplete, 

as they refer to conditions during and prior to 1908. The chief 

object of this paper is to discuss the geologic conditions in the field 

and the relation of the coal at Nye and Red Lodge.

In common with other investigations of Rocky Mountain coal 

fields made by the United States Geological Survey in recent years, 

the examination was made primarily for the purpose of classifying 

the land with respect to coal. In the field, therefore, land lines were 

followed wherever it was feasible, and locations were checked from 

time to time by established land corners. The topography was 

sketched by plane-table methods, an aneroid barometer being used 

for vertical control.

In the field the writer was assisted by F. H. Kay and E. F. Schramm 

and in the office by Mr. Kay in the compilation of data obtained-.

199
200 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

SURFACE FEATURES.

The area to which this report relates lies adjacent to and north of 

the Beartooth Mountains and extends westward from Rock Creek to 

Stillwater River. It contains about 300 square miles. (See PL XX.)

The surface of the field is considerably diversified, including broad 

terraces and areas of rolling or much dissected country. On the 

south it is bordered by the rugged Beartooth Mountains. Glaciation 

has done much to modify land forms in the vicinity of the mountains, 

as nearly every stream valley and interstream divide is filled or 

covered with glacial debris. Aside from the mountainous tract the 

roughest topography is seen in the western part of the field, where 

the interstream areas rise to an altitude of 6,000 feet, or 1,000 feet 

above the valleys. The lowest place is in the extreme northeast 

corner of the field, where the altitude is about 4,600 feet above sea 

level. From this locality the surface rises toward the south and 

culminates in the high peaks of the Beartooth Mountains, whose 

glacier-crowned summits reach a maximum altitude of over 12,000 

feet, the highest in the State. Mapping was not extended southward 

beyond the base of the mountains, where the altitude is uniformly 

about 6,000 feet.

The field as a whole is well drained by perennial streams flowing 

from the mountains. The largest of these are Rock, East and West 

Red Lodge, East and West Rosebud, and Fishtail creeks and Stillwater River, all direct or indirect tributaries of the Yellows tone.

Red Lodge is the largest town in the area, having a population of 

about 4,860. Other post offices are Luther, on West Red Lodge 

Creek; Dean, on a branch of Fishtail Creek; and Nye, near the junction of West Stillwater River with the main stream. Red Lodge is 

connected with the transcontinental line of the Northern Pacific 

Railway by a branch from Laurel, about 16 miles west of Billings. 

Transportation from other parts of the field is effected by wagon to 

points on the Northern Pacific.

GEOLOGY.

STRATIGRAPHY.

The rocks of the area comprise a great thickness of strata ranging 

from coal measures of lower Montana (Upper Cretaceous) age to 

beds more than 8,000 feet up in the Fort Union formation of the 

Eocene. Older sedimentary formations and crystalline rocks are 

exposed in the Beartooth Mountains, along whose north base there 

is a profound fault that brings Paleozoic rocks into contact with 

Tertiary formations south of Red Lodge and with successively older 

strata to the west. The geology of this area is shown on Plate XXI.
U.S. GEOLOGICAL SURVEY BULLETIN 641 PLATE XX

TOPOGRAPHIC MAP 

OF THE

UPPER STILLWATER BASIN

STILLM^ATER AND CARBON COUNTIES 

MONTANA

KEY MAP

Shaded portion of key map shows location of Upper StillwaterBasin
GEOLOGY OF THE UPPER STILLWATER BASIN, MONT. 201

CRETACEOUS SYSTEM. 

EAGLE SANDSTONE AND LIVINGSTON FORMATION (UPPER CRETACEOUS).

The oldest rocks in the area consist of a white sandstone about 300 

feet thick, the upper part of which is massive and grades downward 

into a sandy shale. The entire thickness of this sandstone occurs 

only in the western part of the field, but the upper portion is exposed 

locally as far east as sec. 4, T. 6 S., R. 18 E. A carbonaceous zone, 

locally coal bearing, occurs at the top of the sandstone. This white 

sandstone is overlain by a mass of greenish or brownish sandstone and 

sandy tuffaceous shale about 3,200 feet thick in the central part of 

the area. On examination these overlying beds appear to be highly 

andesitic in character and therefore to have been derived from volcanic rocks. These andesitic strata are exposed over a considerable 

area in the western part of the field. On West Rosebud Creek poorly 

assorted volcanic agglomerate, also of andesitic material, appears as a 

thin wedge in the midst of the tuffaceous beds, and this agglomerate 

thickens westward until in the vicinity of Stillwater River it is about 

2,000 feet thick. In spite of this notable thickening and the fact that 

the base of the agglomerate is uniformly about 625 feet above the base 

of the andesitic beds, the stratigraphic distance between the agglomerate and the overlying Tertiary beds (Fort Union formation) remains fairly constant. A section of the andesitic beds measured in 

T. 5 S., R. 18 E., where the agglomerate is absent, is as follows:

Section in T. 5 S., R. IS E.

Feet.

Sandstone, brownish, platy, and sandy shale (thickness estimated). 1,500 

Sandstone, platy, brownish gray, with layers of chocolate-colored 

concretions as much as 1 foot in diameter....................... 99

Partly'''oncealed; lower 100 feet is yellowish-brown platy sandstone and yellowish sandy shale............................... 287

Sp-ndstone, very irftrgular in lithology and bedding, coarse grained 

tc-pebbly.................................................... 55

Sandstone, brown, and sandy shale... t. ......................... 120

Partly concealed; where exposed consists of brown sandy shale 

<^'and thin brown sandstone.................................... 880

Sandstone, gray or brown, with intercalated yellowish shale; texture and bedding variable, chiefly fine grained and tuffaceous, 

with plant fragments........................................ 214

Shale and thin platy sandstone, brownish gray, compact and fine 

grained..................................................... 11

Sandstone, thin bedded, coarse grained......................... 39

Shale, gray and yellow, with thin sandstone and lignitic bands..... 28

.3,233

On Stillwater River the section of the andesitic beds differs from 

that given above and comprises about 625 feet of shale and sandstone, 

2,000 feet of agglomerate, and 2,500 feet of shale and thin sandstone,

43768° Bull. 641 17 14
202 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

all highly andesitic. All of this section is not exposed in the area 

mapped but is shown on each side of Stillwater Valley farther northeast.

Considerable interest attaches to the age of the basal coal-bearing 

sandstone and the overlying andesitic beds. Fossil leaves are present 

in both formations, although they are confined chiefly to rocks closely 

associated with the coal bed of the massive sandstone and to the andesitic beds underlying the agglomerate. These leaves are similar to 

those found in the vicinity of Livingston, about 35 miles northwest of 

Nye, and the rocks containing them are therefore to be correlated 

with similar plant-bearing beds at Livingston. In that locality the 

rock section consists of a mass of shale about 3,600 feet thick, which 

has been considered by previous writers to be the representative of 

the Colorado shale, Pierre shale, and Fox Hills sandstone. Overlying 

this mass of shale at Livingston is a coal-bearing sandy formation 

about 800 feet thick that contains fossil leaves similar to those found 

in the coal measures near Nye. Next higher stratigraphically is a 

mass of andesitic rocks about 5,000 feet thick, near the base of which 

occur leaves of the identical species found in the andesitic beds east of 

Stillwater River. In earlier reports the coal measures at Livingston 

were considered to be of Laramie age and the andesitic rocks above, 

termed the Livingston formation, were supposed to have been deposited after a period of erogenic movement following the Laramie. 

According to this interpretation the coal-bearing sandstone at Nye 

should be considered Laramie and the overlying andesitic rocks to be 

of Livingston age. Regional study by R. W. Stone and the writer, 

however, leads to the conclusion that the stratigraphy at Livingston 

has been misinterpreted. Colorado fossils have been found at the top 

of the mass of shale that constitutes the lowest formation i$ the section 

as described, and it therefore appears that the coal-bearing sandstone 

at Livingston is of lower Montana age rather than Laramie, as has 

been previously supposed. Furthermore, no unconformity was 

was found between the coal measures and the overlying Livingston 

formation, and there is evidence of continuous deposition froi? Colorado time into Fort Union time. The present interpretation is that 

the coal measures near Livingston are of lower Montana age, and that 

the Livingston formation itself is the time equivalent of the Claggett, 

Judith River, Bearpaw, and possibly even younger formations as developed elsewhere in the State, and is therefore of Upper Cretaceous 

and Eocene age.

In this report, therefore, the coal measures in the vicinity of Nye are 

assigned to the Eagle sandstone, the lowest formation of the Montana 

group. As the overlying rocks up to the Fort Union can not be separated on the basis of either lithology or paleontology the term Livingston formation will be applied to them, although it is to be under-
U.S.GEOLOGICAL SURVEY BULLETIN 641 PLATE XXI

R.I5E. R.I6E.

LEGE N D

Linley conglomerate Livinjiston formation 

(agglomerate, member}

Livin^ston formation 

(leaf-bearing beds)

Ea6le sandstone 

(coal bearing)

Outcrop of coal bed

Glacial drift (Including 

terminal, lateral, and ground 

moraines, and outwash)

Terrace 6ravel o

(May include Lance

formation in lower portion) \-

Strike and dip

 : A Gout, land corner found

GEOLOGIC MAP 

OF THE

UPPER STILLWATER BASIN

STILLWATER AND CARBON COUNTIES 

MONTANA

BY -W.B..CAL.VERT

KEY MAP

Shaded portion of key map shows location of Upper Stillwater Basin 6 Miles
GEOLOGY OP THE UPPER STILLWATEE BASIN, MONT. , r 20vV

stood that by the use of this name no attempt is made to convey an 

idea of distinct geologic time. It is not appropriate to discuss in this. 

report all the details on which are based the present interpretation of 

the stratigraphic questions involved, and the reader interested in the 

subject is referred to a paper in which the problem is treated at greater 

length.1 In any event, however, it has been ascertained beyond 

question that the coal measures at Nye are not in the same geologic 

formation as those at Red Lodge, but are nearly 9,000 feet lower.

TERTIARY SYSTEM. 

FORT UNION FORMATION (EOCENE).

The rocks in the eastern part of the field, aside from surficial 

material and those of an area of about 5 square miles south of Linley, 

represent fresh-water deposits of Fort Union age, which are predominantly sandy. Woodruff 2 has separated the Fort Union formation of this region into three members, the division being based 

on the presence or absence of valuable coal beds. The lowest member 

consists of variable yellowish sandstone and shale 5,700 feet thick, 

in which no coal of any consequence occurs. Above is a member 

825 feet thick, which is lithologically similar in appearance to the 

underlying member, but which contains several beds of coal. The 

upper member, about 2,000 feet thick, is also of essentially the same 

character as the lower, and likewise differs from the middle member in 

that it contains no valuable coal beds. Although it is likely that the 

lower part of the section should be referred to the Lance formation 

("Ceratops beds"), fossils belonging to that formation were not 

found, and as there is no distinct change in lithology in the mass of 

rocks described, the entire sequence is tentatively designated Fort 

Union.

LINLEY CONGLOMERATE (POST-EOCENE).

In addition to the Eagle sandstone, the Livingston and Fort 

Union formations, as previously described, other rocks are represented in the area. Between Linley'and the Beartooth Mountains 

is an area of about 5 square miles in which a conglomeratic sandstone lies with marked unconformity on tilted and eroded Fort Union 

rocks. The conglomerate is bedded throughout and is composed 

mainly of grains and well-rounded pebbles, 6 inches or less in diameter, 

of greenish porphyry, with smaller amounts of limestone and pink 

granite, all presumably originating in the Beartooth Mountains. 

The strata appear to dip at a moderate angle to the northeast, but 

this dip is considered to be the original attitude of deposition rather 

than the result of subsequent structural disturbance. It is difficult

1 Stone, R. W., and Calvert, W. R.., The stratigraphic relations of the Livingston formation of Montana: 

Econ. Geology, vol. 5, Nos. 6, 7, and 8,1910.

2 Woodruff, E. G., The Red Lodge coal field, Mont.: U. S- Geol. Survey Bull. 341, pp. 92-107,1907.
204 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

to determine the thickness of this conglomerate, but it attains an 

approximate maximum of 300 feet. Toward the north it thins to 

a mere film. Although erosion has now separated the conglomerate 

from the Beartooth Mountains, its southern border no doubt formerly extended to that uplift. Because of the development of this 

conglomerate in the vicinity of Linley, it is here designated the 

Linley conglomerate.

No fossils were found in the conglomerate, and its age is therefore 

uncertain. Its superposition on highly tilted Fort Union rocks 

indicates that it is considerably younger than the Fort Union and 

also more recent than the major structural disturbances of the region. 

That it is not of glacial age or origin is indicated by the evenly 

bedded and solidified character of the rocks, by the entire absence of 

striae, and by the superposition of undoubted glacial drift along 

the eastern margin of the conglomerate. The date of the deposition 

of the Linley conglomerate is rather to be correlated with the period 

when erosion had laid bare the crystalline core of the Beartooth 

Mountains and when streams emerging from the uplift had much 

greater gradient and carrying capacity than at present. The conglomerate was laid down as a fan or delta deposit by Red Lodge 

Creek at the locality where its gradient was suddenly lowered on 

emergence from the mountainous area. Criteria to determine the date 

of this condition are not available, and the Linley conglomerate is 

therefore merely referred to the post-Eocene.

QUATERNARY SYSTEM.

Glacial drift covers a considerable part of the area and effectually 

conceals all older sediments wherever it occurs. This drift is made 

up of lateral and terminal moraines, outwash, and other forms Of 

glacial debris. On the recession of the glacier that once occupied 

Stillwater Valley a lake was formed, and along its borders were 

strewn bowlders, probably left by floating ice; the lake floor was also 

covered by de*bris, which now conceals the underlying rock. Terrace 

gravel occupies the surface in much of the eastern part of the field.

IGNEOUS BOCKS.

Two areas of intrusive andesite were noted in the vicinity of 

Dean post office one in sees. 13 and 14, T. 5 S., R. 16 E., and the 

other in sees. 15, 16, and 17, T. 5 S., R. 17 E. These rocks were 

not examined in detail, but as they cut the lower part of the Livingston formation they must have been intruded at a later date than 

the deposition of that material, and they were probably intruded 

before the movement which resulted in the formation of the Dean 

anticline.
GEOLOGY OF THE UPPER ST1LLWATEB BASIN, MONT. 205 

STRUCTURE.

The structure in the eastern part of the field is relatively simple. 

At Red Lodge the strata associated with the coal beds dip at an 

angle of 18° toward the Beartooth Mountains, but the angle decreases as the mountains are approached. The beds are finally 

terminated by a fault of great throw which extends northwestward 

along the base of the mountains entirely across the field. Near 

Red Lodge Paleozoic limestone standing vertical occurs just south 

of the fault line, but farther west younger rocks up to and including 

the Jurassic appear, indicating that the throw of the fault lessens 

in that direction.

North of Red Lodge the strike of the beds remains fairly constant 

in direction, although interrupted by minor flexures. The dip gradually decreases, however, and at the northern border of the area it 

is less than 5°. Because of this decrease in dip the entire thickness 

of the Fort Union is not exposed in the area surveyed, and the total 

of 8,500 feet assigned to the formation was measured northeast of 

Red Lodge.

Minor faults and folds are numerous in the district west of Rock 

Creek and northwest of Red Lodge. These local structural features 

were generally not mapped, however, as the lack of persistent welldefined key beds rendered it practically impossible to work out the 

structure in detail. West of R. 19 E. the structure is dominated by 

an anticline which trends N. 70° W. to the western border of the 

field. East of Nye this anticline is cut by a fault. The fault can 

not be followed for any considerable distance, as on the east it 

extends into andesitic rocks where the structure is largely concealed 

by lack of well-defined bedding and on the west it passes under a 

mantle of alluvium and glacial material. The amount of vertical 

displacement can not be determined with certainty, but in the cliff 

near the south side of T. 4 S., R. 16 E., it must be nearly 600 feet. 

Southeast of this locality the structure seems best explained by two 

faults.

COAL IN THE RED LODGE DISTRICT.

FORT UNION FORMATION.

The coals at Red Lodge had been studied prior to the examination 

by the writer in 1908, and only one main point, that relating to the 

westward extent of the Red Lodge field, remained to be decided. 

For details regarding the coals, therefore, the reader is referred to 

the previous publication on this field.1 The repetition of certain 

points relative to the coal, however, seems desirable. The workable

i Woodruff, E. G., The Red Lodge coal field, Mont.: U. S. Geol. Survey Bull. 341, pp. 92-107, 1907.
206 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

beds have a vertical range of about 800 feet and are underlain by 

about 5,700 feet of practically barren strata. Above them is a similar mass of sandstone and sandy shale about 2,000 feet thick which 

is also unproductive of coal. Measurement of the coal shows a total 

of 71 feet in beds more than 3 feet thick. The workable beds are 

known locally as Nos. 1, 1|, 2, 3, 4, 4J, 5, and 6. The coals are 

high-grade subbituminous coals, and compare favorably in heat value 

with the bituminous coals of the Mississippi Valley but do not stock 

so well.

The Fort Union coal beds west of Red Lodge are exposed in outcrop on both sides of Rock Creek, where they dip 18° S. and strike 

N. 78° W., but immediately west of the town exposures are lacking 

and there is nothing to indicate whether or not the structure continues regularly. Near the west quarter corner of sec. 28, T. 7 S., 

R. 20 E., however, a coal bed has Jbeen prospected, and though the 

opening was badly caved certain information was obtainable. It 

was noted that the strike and dip of the bed were identical with 

those on Rock Creek, and by sighting back along the strike it seemed 

probable that the bed is No. 1J, an assumption which is strengthened 

by the apparent thickness and character of the bed at the prospect, 

which is comparable to No. 1£ as developed at Red Lodge.

West of the prospect in sec. 28 exposures are not good, but the 

structure seems to be regular. If so, the upper coal bed meets the 

Beartooth fault near the east side of the township to the west, and 

the lower beds continue only a short distance farther. It seems 

likely, therefore, that the producing district at Red Lodge will be 

practically confined to Tps. 7 and 8 S., R. 20 E., for although the 

Fort Union formation constitutes the surface over a large area 

northwest of Red Lodge the highest strata exposed are below the 

productive zone.

LIVINGSTON FORMATION.

On West Rosebud Creek a carbonaceous zone near the base of the 

andesitic beds overlying the Eagle sandstone has been prospected 

at several localities, but in only one place has coal actually been 

removed. This is in sec. 23, T. 5 S., R. 17 E., where T. E. Philip 

drove an entry 250 feet long. The coal occurs here in four irregular 

benches with partings of bone and shale. The lower bench reaches 

a maximum thickness of 17 inches, and the bench above ranges from 

1 inch to 13 inches. The next higher bench is termed the "rotten 

vein" and is worthless; the top bench is the most variable of all. 

This coal is not valuable, as the waste is excessive and the coal bed 

extremely variable and faulted. Where opened at other localities
GEOLOGY OF THE "UPPER STILLWATER BASIN, MONT. 207

the zone comprises only carbonaceous shale with thin partings of 

coal. Carbonaceous zones occur also near the top of the Livingston 

formation, but.no coal bed was found more than 8 inches thick.

EAGLE SAND STONE.

Coal is mined near Nye, in what is known as the Upper Stillwater 

Basin, from a single bed that is near the top of the massive white 

sandstone believed to be the Eagle. Above this are the brownish 

clay shale and thin tuffaceous sandstone constituting the lower part 

of the Livingston formation. The coal bed is exposed in outcrop in 

the cliff east of Stillwater River, gradually approaching the level of 

the valley floor, which it crosses in sec. 28, T. 4 S., R. 16 E., and it 

continues in a direction slightly north of west to the vicinity of the 

south quarter corner of sec. 19. From this locality it apparently 

swings to the south along the southeast base of Sheep Mountain, 

where it turns to the east and probably passes beneath alluvium and 

glacial drift. It is not known with certainty whether the bed 

appears elsewhere within the area, as the structure in this vicinity 

is complex and largely concealed by glacial debris.

Three mines have been opened on this coal bed and operated to 

supply a small local demand. The easternmost of these is the Albertson mine, in the SE. | NW. 1 sec. 28, T. 4 S., R. 16 E. At this 

locality the coal bed is split by bone or sandstone partings into 

several benches, as shown in the following section, measured at a 

point in the mine 250 feet from the entrance:

Section of coal bed 'in the Albertson mine.

Sandstone. Ft. in.

Coal................................................... 10

Sandstone............................................ 1

Coal................................................... 11

Bone.................................................. 1

Coal................................................... 8

Bone.................................................. 4

Sandstone............................................... 4$

Coal................................................... 7J

Bone and sandstone. .................................... 2 10

Coal................................................... 1

Sandstone. 

Total coal............................................ 4 $

Sample No. 6314 (see p. 210 for analysis) was cut at this place and 

includes the upper three benches of coal. At the time of the examination the entry of the Albertson mine was about 250 feet long on a very 

slight dip. No water or gas has been encountered in the workings.

On the northwest side of Stillwater River, in the NE. | NW. J sec. 

29, is the Loffer mine. Here the bed is opened by a slope 400 feet
208 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

long on a dip of 11°. The coal occurs in three benches, as shown by 

the following section, measured at the end of the slope:

Section of coal bed in Loffer mine.

Sandstone. 

Goal............................'.

Coal.............................

Bone. ...........................

Sandstone. .......................

Coal.............................

Ft. in. 

....................... 5

....................... 2

....................... 11

....................... 9

....................... 3

....................... 3 3

Sandstone.

Total coal.......:....:................................ 4 7

Sample No. 6320 (see p. 210) was obtained by making a cut across 

the three benches of coal at the place where the section given above 

was" measured. Although under considerable cover, the coal is 

badly weathered near the outcrop and is not marketable for at least 

125 feet from the mouth of the entry.

About three-quarters of a mile west of the Loffer mine is the 

Lehner opening. The entry was filled with water at the tune of 

visit, so that an examination could not be made, but it was reported 

that the coal occurs in three benches, which are shown in the following 

section, given by a local resident:

Reported section of coal bed at Lehner mine.

Sandstone. 

Coal. ..................................................

Bone parting. 

Coal. ................................................

Shale. ...............................................

Coal. ..................................................

Total coal. .........................................

 Feet. 

...... 1

...... 1

...... 2

...... 3

....... 5

Aside from these three mines no development worthy of mention has been made in the vicinity of Nye. The coal bed has been 

prospected southeast of the Albertson mine, in the southern part 

of sec. 33, and shown to be of poor quality and insufficient thickness. On the opposite side of the valley, southwest of the Lehner 

mine, nothing is known of the coal bed. Its probable outcrop is 

indicated on the map (PI. XXI) but it was not seen, and therefore 

the area of readily available coal in the vicinity of Nye is probably of 

small extent. Dips near the outcrop are comparatively slight 

as a rule, yet a short distance away from-the outcrop the coal bed 

is carried by increasing dips to considerable depths. Coal is mined 

from a thin bed in sec. 8, T. 5 S., R. 16 E., from rocks which in lithology might belong either to the coal measures or to the overlying
GEOLOGY OP THE UPPER STILLWATER BASIN", MONT. 209

andesitic beds. Fossil plants" do not serve to differentiate these 

formations sharply, so that there is doubt as to the stratigraphic 

position of the coal. It is probable, however, that the bed is above 

the coal bed exposed north and east of Nye. On the west side of 

Stillwater River, outside of the area mapped, a bed of coal has been 

opened that is probably the same as that near Nye. It is, however, 

of poor quality and is not considered further in this report.

CHARACTER OF THE COAL.

The coal of the Nye district is fairly dense and rather dull in 

luster, though it contains brighter bands ranging from a mere film 

to some a quarter of an inch thick. Brown resin occurs in a few minute lenses. So far as known the coal is noncoking.

Samples were taken from the Albertson (No. 6314) and Loffer 

(No. 6320) mines, and their analyses, made in the United States 

Geological Survey laboratory at Pittsburgh, are given below.
Analyses of coal samples from the Nye coalfield

[F. M. Stanton, chemist in charge.]

Laboratory 

No.

6314 

6320 

3590 

5823 

5495 

5508

Location.

Quarter.

NW... 

NE... 

SE....

SW...

NE...

Section.

28 

29 

30 

6 

17 

13

T. S.

4 

4 

7 

8 

6 

5

R. E.

16 

16 

20 

21 

23 

22

Thickness.

Coal 

bed.

ft. in. 

7 9

5 9 

11 5 

3 11

7 8 

7 5

Part 

sampled.

Ft. in. 

3 1£

4 7 

6 0 

3 9 

3 6 

4 1

Airdrying 

loss.

2.2 

2.4 

4.7 

3.3 

8.8 

3.7

Form 

of

analysis.

A 

B 

C 

D

A 

B 

C 

D

A 

B 

C 

D

A 

B 

C 

D

A 

B 

C 

D

A 

B 

C 

D

Proximate.

Moisture.

7.0 

4.9

6.7 

4.4

11.7 

7.3

9.8 

6.7

14.8 

6.6

9.7 

6.3

Volatile 

matter.

30.1 

30.8 

. 32.4 

40.5

32.4 

33.2 

34.7 

42.1

36.1 

37.9 

40.9 

47.3

34.7 

35.9 

38.5 

42.4

26.9 

29.6 

31.6 

37.5

27.7 

28.7 

30.6 

37.5

Fixed 

carbon.

44.2 

45.2 

47.5 

59.5

44.5 

45.6 

47.7 

57.9

40.2 

42.2 

45.5 

52.7

47.2 

48.8 

52.3 

57.6

44.9 

49.2 

52.7 

62.5

46.2 

47.9 

51.2 

62.5

Ash.

18.7 

19.1 

20.1

16.41 

16.81 

17.60

11.98 

12.57 

13.57

8.27 

8.55 

9.17

13.35 

14.64 

15.67

16.42 

17.05 

18.20
GEOLOGY OF THE UPPER ST1LLWATEB BASIN", MONT. 211

In the table the analyses are given in four forms, marked A, B, C, 

and D. Analysis A represents the composition of the sample as it 

comes from the mine. This form is not well suited for comparisons, 

for the amount of moisture in the sample as it comes from the mine 

is largely a matter of accident and consequently analyses of the same 

coal expressed in this form may vary widely. Analysis B represents 

the sample after it has been dried at a temperature a little above 

the normal until its weight becomes constant. This form of analysis 

is best adapted to general comparisons. Analysis C represents the 

theoretical condition of the coal after all the moisture has been 

eliminated. Analysis D represents the coal after all moisture and 

ash have been theoretically removed. This is supposed to represent 

the true coal substance, free from the most important impurities. 

Forms C and D are obtained from the others by recalculation. They 

should not be used for commercial representation, for they represent* 

theoretical conditions that never exist.

In the analytical work chemists generally recognize that it is not 

possible to determine the proximate constituents of coal or lignite 

with the same degree of accuracy as the ultimate constituents. 

Therefore the air-drying loss, moisture, volatile matter, fixed carbon, 

and ash are given to one decimal place only; whereas the ash (in an 

ultimate analysis), sulphur, hydrogen, carbon, nitrogen, and oxygen 

are given to two decimal places. It is also understood that calorific 

determinations to individual units are not reliable; therefore in the 

column headed "Calories" the heat values are given to the nearest 

five units, and in the column headed "British thermal units" they 

are given to the nearest tens, a British thermal unit being about 

one-half the value of a calorie.

In order to make direct comparisons with other coals of this 

general region analyses of some of the best-known coals have been 

inserted in the table. No. 3590 represents a sample from bed No. 1 

in the mine of the Northwestern Improvement Co. at Red Lodge. 

No. 5823 represents a sample from bed No. 4 in the mine of the Bear 

Creek Coal Co. at Bear Creek. Both of these beds are in the Fort 

Union formation and hence are much younger geologically than the 

Nye bed in this field. Nos. 5495 and 5508 represent coal from the 

Bridger bed, in the eastern part of Carbon County, which occupies 

about the same stratigraphic position as the Nye bed. No. 5495 

is the analysis of a sample from the mine of the Bridger Coal Improvement Co. and. No. 5508 of a sample from Gebo No. 2 mine of the 

Bituminous Coal Co.

By comparison of the analyses it will be seen that th6 composition 

of the Nye coal is more nearly like that of the Bridger coal than it is 

like that of the coal at Red Lodge and Bear Creek. The moisture 

of the Nye coal is nearly the same as that of the Bridger coal and
212 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

considerably less than that of the Fort Union coals at Red Lodge and 

Bear Creek. The amount of volatile matter is also nearly the same 

in the Nye and Bridger coals and less than in those of Bear Creek and 

Red Lodge. Ash, on the other hand, is greater in the Nye and 

Bridger coals than it is in the Red Lodge and Bear Creek coals. 

The real value of the coal itself, aside from any impurities such as 

moisture and ash that it may contain, is well shown by a comparison 

of the heating values in the analyses of form D:

Heating values of some Montana coals.

Coal.

N ye.-.*. ..............................................................................

Laboratory 

No.

6314

6320

5495

5508

3590

5823

British 

trier mal 

units.

13,640

13,900

13,970

13. 870

12,820

1Q OCft

From this table it is evident that the substance of the Nye and 

Bridger coals is superior in heating value to that of the Red Lodge 

and Bear Creek coals, but the higher ash content would tend to 

neutralize this advantage and make the two coals as they reach the 

market of about the same value.

These coals are doubtless near the dividing line between bituminous 

and subbituminous. Those of Red Lodge and Bear Creek, owing 

to their tendency to slack when exposed to the atmosphere, are 

generally regarded as subbituminous, whereas the Bridger coal, which 

shows little or no tendency to slack, is regarded as bituminous. It is 

said that the coal at Nye' will stock as well as that at Red Lodge, if 

not better, and if this claim is in accord with the facts it appears that 

the Nye coal may be classified as bituminous rather than subbituminous like the Red Lodge and Bear Creek coals. This assignment of 

the Nye coal to the bituminous class is still further strengthened by 

the similarity of its composition to that of the Bridger coal as shown 

by the analyses.

FUTURE DEVELOPMENT.

In the Red Lodge district development is certain to be steady and 

continued, as a great amount of coal is known to be available and 

transportation facilities are entirely adequate. The coal in the 

Upper Stillwater Basin, however, is less fortunately situated, and the 

present demand is purely local. The future of this area, therefore, 

is dependent on future transportation facilities. Surveys have been 

made from Columbus, on Yellowstone River, to the headwaters of 

the Stillwater, the object being to build a line to Cooke City to aid in 

the development of the metalliferous district in that vicinity, If
GEOLOGY OF THE UPPER STILLWATER BASIN, MONT. 213

this line is ever built it will afford an outlet for the coal near Nye, 

and as this coal compares favorably with that of competing fields, a 

considerable amount would no doubt find its way to market. The 

tonnage of available coal, however, is not comparable to that of the 

Ked Lodge field, where there are at least eight workable beds and 

where the area underlain by coal within 2,000 feet of the surface is 

considerably greater than at Nye.

OIL PROSPECTS.

At two localities in the area mapped there have been attempts to 

obtarn oil by drilling. One of these is in the northeastern part of 

sec. 4, T. 6 S., R. 18 E., and the other is in the SE. | sec. 32 of the 

same township. At the former place several holes were put down 

to different depths, the deepest being 1,500 feet. After pa&sirig 

through surface wash and the lower sandy portion of the Eagle sandstone the drilling was in dark shale and thin sandstone, presumably 

of Colorado age. AH the holes were dry, although indications of oil 

were reported. The drilling was done on the axis of an anticline, 

but nevertheless the absence of oil in the rock section has not been 

conclusively shown, first because the holes were of insufficient depth, 

and second because they were put down on the pitching end of the 

anticline. The absence of water in the drill holes, however, suggests 

that the beds penetrated are not charged with oil higher in the anticlinal arch and that if oil is present at any horizon through which the 

drill passed it has accumulated at that horizon lower down on the 

flanks of the anticline. All prospecting at this locality had ceased at 

the time of examination in 1908.

At the locality in sec. 32 there is more justification for oil prospecting, and considerable money had been expended prior to 1904, 

when large operations ceased, owing, it is said, to disagreement 

among the stockholders. One hole had been drilled to a depth of 

1,100 feet and several others to about 600 feet. Indications of oil 

were reported in each, and it was "asserted that in one hole small 

amounts of oil were obtained. At three points near by small pools 

of asphalt occur, and in 1908 these pools were being augmented by 

asphalt oozing from the ground.

Geologic relations in this vicinity are much obscured by thick 

growths of quaking aspen, but enough was observed to ascertain 

that the drilling was done in Fort Union rocks dipping toward the 

Beartooth fault at an angle of 22°. The exact location of the fault 

here is somewhat doubtful, owing to the covering of talus, but it is 

probable that the holes are about a quarter of a mile from the fault 

line. Because of the relation of the drill holes to the fault the original 

stratigraphic horizon of the oil is in doubt, and whether or not it is 

indigenous to the Fort Union beds with which it is at present asso-
214 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

ciated is uncertain. It seems probable, however, that the original 

source of the hydrocarbons was at a lower stratigraphic horizon, and 

that the Beartooth fault has afforded opportunities for migration 

upward to the pervious strata of the Fort Union. Evaporation at 

the surface then dissipated the volatile portion, and the residuum 

remains as asphalt. The fact that this bituminous residue is present 

at the surface suggests that oil in large quantity is not likely to be 

found hi the strata from which the asphalt oozes. Moreover, whatever oil is present would be more likely to be encountered by drilling 

nearer to the Beartooth fault, but the possible oil-bearing strata would 

naturally be at a greater depth than is reached in the holes drilled 

prior to 1908.