GEOLOGICAL SURVEY CIRCULAR 251

RESULTS OF RECONNAISSANCE FOR 

URANIFEROUS COAL, LIGNITE, 

AND CARBONACEOUS SHALE 

IN WESTERN MONTANA

By William J. Hail, Jr., and James R. Gill
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 251

RESULTS OF RECONNAISSANCE FOR URANIFEROUS COAL, LIGNITE, AND 

CARBONACEOUS SHALE IN WESTERN MONTANA

By William J. Hail, Jr., and James R. GUI

-This report concerns work done on behalf of the 

U. 8. Atomic Energy Commission and is published 

with the permission of the Commission.

Washington, D. C., 1953

Free on application to the Geological Survey, Washington 25, D. C.
CONTENTS

Page

Abstract.................................... 1

Introduction. ................................ 1

Cretaceous coal ............................. 1

Description of districts examined ............. 1

Livingston-Trail Creek coal field, Park,

Gallatin, and Sweetgrass Counties...... 1

Electric coal field, Park County......... 2

Ryegate district, Golden Valley,

Wheatland, Yellowstone, and

Stillwater Counties.................... 3

Silver Bow Valley district,

Silver Bow and Deer Lodge

Counties ............................. 3

Upper Ruby River district,

Madison and Beaverhead

Counties............................. 3

Tertiary lignite and carbonaceous shale ....... 4

Description of districts examined .............. 4

Lombard coal field, Broadwater County . . 4 

Smith River Valley district,

Meagher County....................... 4

Townsend Valley district,

Broadwater County.................... 4

Gallatin Valley district,

Gallatin County ....................... 5

Prickly Pear Valley district,

Lewis and Clark County............... 5

Avon Valley district, Powell County....... 6

Page

Description of districts examined--Con. 

Blackfoot Valley district, Powell,

Granite, and Missoula Counties......... 6

Flint Creek Valley district, Granite

and Powell Counties .................. 6

Deer Lodge Valley district,

Deer Lodge and Powell Counties ....... 6

Missoula Valley district, Missoula

County............................... 7

Bitterroot Valley district,

Ravalli County........................ 7

Big Hole Valley district,

Beaverhead County.................... 7

Silver Bow Valley district,

Silver Bow and Deer Lodge Counties.... 7 

Jefferson Valley district, Silver Bow

and Madison Counties.................. 8

Beaverhead Valley district, Beaverhead

and Madison Counties ................. 8

Madison Valley district,

Madison County ....................... 8

Centennial Valley district,

Beaverhead County .................... 8

Medicine Lodge Creek Valley district,

Beaverhead County .................... 8

Lemhi Valley district,

Lemhi County, Idaho................... 8

Literature cited.............................. 9

ILLUSTRATION

Page

Plate 1. -Index map of southwestern Montana showing areas prospected for uranium-bearing lignite. Inside back cover

TABLES

Page

Table 1. Samples collected in the Livingston-Trail Creek coal field ....................................... 2

2. Samples collected in the Electric coal field ................ . ................................... 2

3. Samples collected in t.he Ryegate district............................ ........................... 3

4. Samples collected in the Silver Bow Valley district .............................................. 3

5. Samples collected in the Upper Ruby River district........................................... ... 4

6. Samples collected in the Smith River Valley district ............................................. 4

7. Samples collected in the Townsend Valley district ................................................ 5

8. Samples collected in the Gallatin Valley district................................................. 5

9. Samples collected in the Prickly Pear Valley district .......................................... . 5

10. Samples collected in the Avon Valley district ................................................. . 6

11. Samples collected in the Flint Creek Valley district............................................ . 6

12. Samples collected in the Deer Lodge Valley district............................................ . 6

13. Samples collected in the Mi'ssoula Valley district ............................................... 7

14. Samples collected in the Bitterroot Valley district .............................................. 7

15. Samples collected in the Medicine Lodge Creek district .......................................... 8

16. Samples collected in the Lemhi Valley district ................................................ . 9
RESULTS OF RECONNAISSANCE FOR URANIFEROUS COAL, LIGNITE, AND 

CARBONACEOUS SHALE IN WESTERN MONTANA

ABSTRACT

A reconnaissance search for uraniferous lignite and carbonaceous shale was made in western 

Montana and adjacent parts of Idaho during the 

summer of 1951. Particular emphasis in the 

examination was placed on coal and carbonaceous 

shale associated with volcanic rocks, as volcanic 

rocks in many areas appear to have released 

uranium to circulating ground water from which 

it was -concentrated in carbonaceous material. 

Twenty-two areas in Montana and one area in 

Idaho were examined. The coal in five of these 

areas is of Cretaceous age. The coal and 

carbonaceous shale in the remaining 18 areas occur 

in Tertiary "lake-bed" deposits of Oligocene and 

younger age. Both the Cretaceous and Tertiary 

coal and carbonaceous shale are associated with 

contemporaneous or younger volcanic rocks and 

pyroclastic sequences.

A sample of carbonaceous shale from the 

Prickly Pear Valley northeast of Helena, Mont., 

contained 0. 013 percent uranium. A sample of 

carbonaceous shale from the Flint Creek Valley 

southwest of Drummond, Mont., contained 0. 006 percent uranium. All other samples of both Cretaceous 

and Tertiary coal and carbonaceous shale were 

essentially nonradioactive.

INTRODUCTION

A reconnaissance search for uraniferous lignite and carbonaceous shale in western Montana 

(see accompanying index map, pi. 1) was made 

during the summer of 1951 as part of the Geological Survey program of reconnaissance for 

uranium deposits in the Rocky Mountain region. 

The work was sponsored by the Division of Raw 

Materials of the Atomic Energy Commission.

Uraniferous lignite and coal in South Dakota 

were studied by Denson, Bachman, and Zeller 

(1950), who showed that the uranium in Cretaceous 

and Tertiary coal seemed to have been derived 

by leaching from the slightly radioactive White River 

formation that unconformably overlies the coalbearing formations. Both Cretaceous and Tertiary 

coal-bearing formations in western Montana contain volcanic rocks or tuffs or are associated with 

them and this association was used as a primary 

guide for reconnaissance prospecting.

CRETACEOUS COAL

Upper Cretaceous coals in the LivingstonTrail Creek and Electric coal fields and the 

Ryegate district were examined and tested for 

radioactivity. The tuffaceous and volcanic rocks 

of the Livingston formation of Late Cretaceous 

and Paleocene age, which overlies the coals in 

the Livingston-Trail Creek and Electric fields, 

and interbedded tuffs in the Judith River formation 

in the Ryegate district, might have served as 

potential source beds for uranium. No appreciable 

radioactivity was detected, however, in the field 

examination of the coals. The bulk of the volcanic 

material in the Livingston formation is basic in 

composition rather than acidic. Radioactive elements 

seem to occur more commonly in acidic volcanic 

rocks.

The petrologic type of the tuffs in the Judith 

River formation was not determined. Cretaceous 

coals at other localities also were sampled, but 

the samples did not contain significant amounts 

of uranium.

DESCRIPTION OF DISTRICTS EXAMINED

Livingston-Trail Creek coal field, 

Park, Gallatin, and Sweetgrass Counties

The Livingston-Trail Creek coal field covers an 

area of approximately 300 -square miles (Calvert, 

1912, p. 29) and lies in the southern part of 

Montana 40 miles north of Yellowstone National 

Park. Rocks from pre-Cambrian to Paleocene 

age are exposed in the area, and all are deformed 

by faulting and folding. The Upper Cretaceous 

coal-bearing strata in the area are more than 

750 feet thick and are overlain by over 5,000 feet 

of tuffaceous and agglomeratic sediments of the 

Livingston formation.

The Livingston-Trail Creek coal field has 

been subjected to pronounced folding and faulting 

that closely parallels the mountain uplift to the 

south. The coal beds are exposed along the 

limbs of sharply folded anticlines and synclines, 

and at many places are vertical or overturned.

Four beds ranging from 1 to 6 feet in thicknes 

have been prospected or mined in the area. The 

coal is of bituminous rank and has been used in
the past for coking. At present, all of the mines are 

abandoned and most cannot be entered.

Over 20 localities were examined radiometrically 

with a Geiger-Muller counter, and coal samples for

chemical analysis were collected at 12 localities in 

Tps. lto4S., andRs. 6to8E., Park and Gallatin Counties. 

No abnormal radioactivity was detected in the coals in 

the field, nor did any sample contain more than 0. 002 percent uranium in the ash upon chemical analysis.

Table 1. Samples collected in the Livingston-Trail Creek coal field

Lab. 

no.

62081

62052

62053

62054

62055

62056

62057

62074

62075

62076

62077

62071

62072

62073

62045

62046

62070

62059

62060

62061

62062

62063

62064

62065

62066

62067

62068

62069

Field 

no.

MM-37

MM -8

MM-9

MM-1C

MM-11

MM-12

MM-13

MM-30

MM-31

MM-32

MM-33

MM- 27

MM- 28

MM- 29

MM-1

MM-2

MM-26

MM-15

MM-16

MM-17

MM-18

MM-19

MM-20

MM-21

MM-22

MM-23

MM-24

MM- 25

ell1

a2

a

a

a

a

a

a

a

a

a

a

a

a

0.001

a

a

a

a

.001

a

a

a

.001

.001

.001

a

a

a

Per

U

___

 _

___

 

 _

___

 

 

___

___

 

 

 

 

 

 

 

 

___

 

 

 -

cent

U in 

ash-

___

_ _

___

 

_ _

_ _

 _

_--

_ _

___

_ 

 

0.001

___

 _

 

___

.001

.002

 

Ash

34.9

36.4

39.7

56.9

21.3

20.0

12.0

17-5

8.82

11.6 17.6

14.4

15.1

22.7

40.8

37.8

17.4

34.3

33-0

26.4

35.8

30.9

38.6

17.9

53.5

16.6

17.0

20.7

Location (Section, Township, Range) 

and description

34, IS. 6 E. 1.1' coal bed.

21, 2 S. 7 E. 2.0' coal bed.

21, 2 S. 7 E. 2.8' coal bed.

21, 2 So 7 E. 1.3 1 coaly shale.

27, 2 S. 7 E. upper 2.6' of 8' coal bed.

27, 2 S. 7 E. middle 2.6' of 8' coal bed.

27, 2 S. 7 E. lower 2.6' of 8' coal bed.

26, 2 S. 7 E. 5.0' bed of 20.0' coal zone.

26, 2 S. f E. 7.0' -bed of 20. 0 1 coal zone.

26, 2 S. 7 E. 3.0' bed of 20. O 1 coal zone.

26, 2 S. 7 E. 5.0' bed of 20.0' coal zone.

33, 2 S. 7 E. 2.5' coal bed.

33, 2 S. 7 E. upper 2' of 4.0' bed.

33, 2 S. 7 E. lower 2.0' of 4.0' bed.

NW£ 26, 2 S., 8 E., 3.0' coal bed.

NW£ 26, 2 S., 8 E., 3.2' coal bed.

N|- 31, 2 S., 8 E., 4.0' coal bed.

27, 3 S. 8 E. 1.9' coal bed.

27, 3 S. 8 E. 2.2' coal bed.

27, 3 S. 8 E. 2.6' coal bed.

27, 3 S. 8 E. 6.0' coal bed.

27, 3 S. 8 E. 4.6' coal bed.

27, 3 S. 8 E. 4.0' coal bed.

NW£ 28, 3 S., 8 E., 3.0' coal bed.

NW£ 28, 3 S., 8 E., 3.0 ' coaly shale.

NW£ 28, 3 S., 8 E., upper 2.0' of 4.0' coal bed.

NW-n- 28, 3 S., 8 E., lower 2.0' of 4.0' coal bed.

ml 4, 4S., 8 E., 1.5' coal bed.

1 eU=equivalent uranium.

2 "a" in this and subsequent tables indicates an equivalent uranium content or uraniuin content 

of less than 0.001 percent.

Electric coal field, Park County

The Electric coal field is in the southwestern 

corner of Park County, Mont., just north of Yellowstone National Park. The coals in this field probably 

are of Late Cretaceous age (Calvert, 1912, p. 55) and 

may be direct correlatives of those exposed in the 

Livingston-Trail Creek coal field about 40 miles to 

the north. The general stratigraphy of the area is 

essentially the same as that of the Livingston-Trail 

Creek area.

Three to four coals ranging in thickness from 

6 inches to 4 feet or more are present in the Electric 

coal field. All mining has ceased in this area, and 

good exposures of the. coal are difficult to find. Six 

localities were examined radiometrically, and at four 

of these, samples were collected for chemical analysis. 

None of the coals examined contained significant amounts 

of uranium.

Table 2. Samples collected in the Electric coal field

Lab. 

no.

62080

62078

62079

62047

62048

62049

62050

Field 

no.

MM-36

MM-34

MM-35

MM-36

MM-4

MM-5

MM-6

Percent

eU

a

a

a

a

a

a

a

U

___

 

 

 

 

 

U in 

ash

___

 

 

 

 

Ash

11.6

, 13.5

21.5

14.3

8.57

29-3

75.4

Location (Section, Township, Range) 

and description

NE£ 8, 9 S., 7 E., 2.2' coal bed.

36, 9 S., 7 E., upper 3-0' of 6.0' coal bed.

36, 9 S., 7 E., lower 3.0' of 6.0' coal bed.

6, 9 S., 8 E., upper 2.5' of 5' coal bed.

6, 9 S., 8 E., lower 2.5' of 5' coal bed.

6, 9 S., 8 E., 0.8' coal bed.

6, 9 S., 8 E., 1.5' coaly shale.
Ryegate district, Golden Valley, Wheatland, 

Yellowstone, and Stillwater Counties

Lignite and carbonaceous shale interbedded with 

volcanic ash and tuffaceous sandstone is present in the 

Judith River formation of Late Cretaceous age in Golden 

Valley and adjacent counties (Ellis and others, 1924). 

The best exposures occur at locality 1 (pi. 1), about 

10 miles north of Ryegate, where 12 beds of lignite 

and carbonaceous shale ranging in thickness from 

0. 5 to 5 feet, and interbedded with thin tuffaceous sandstone and siltstone, occur in a stratigraphic interval 

of about 48 feet. The stratigraphically highest lignite 

bed, 1. 7 feet thick, directly underlies a 4-foot bed 

of silty volcanic ash. The lignites and associated

carbonaceous shales were sampled as was the 4-foot 

bed of volcanic ash. The ash contained 0.001 percent 

equivalent uranium but the lignite and carbonaceous 

shale were not radioactive.

The eight lignite samples from the four other 

localities visited contained less than 0.001 percent 

equivalent uranium.

It is believed that the tuffaceous beds interbedded 

with the lignites and carbonaceous shales in the Judith 

River formation are too thin to be effective source beds 

for uranium. It seems unlikely that potential uraniumbearing coal or carbonaceous shale occurs in the Judith 

River formation in the Ryegate district.

Table 3.--Samples collected in the Ryegate district

Lab. 

no.

66731

66719

66720

66721

66726

66727

66728

66729

66730

66722

66723

66724

66725

Field 

no.

MM-139

MM-127

MM-128

MM-129

MM-134

MM-135

MM-136

MM-137

MM-138

MM-130

MM-131

MM-132

MM-133

eU

0.001

.001

a

a

.001

a

a

a

a

.002

a,

a

.001

Per

U

_..

 

 

 

 

 

 

 

 

 

sent

U in 

ash

...

 

 

 

 

 

Ash

82.5

67.9

26.0

36.5

18.0

40.0

48.5

27.9

28.9

^27.9

62.5

Location (Section, Township, Range) 

and -description

18, 6 N., 18 E., 1.1' lignitic shale.

NE£ 6, 6 N., 20 E., 1.0' lignitic shale.

SW cor. of 6, 6 N., 20 E., 1-5' lignite.

SW cor. of 6, 6 N., 20 E., 2.5' lignite.

21, 8 N., 20 E. 4.0' volcanic ash.

21, 8 N., 20 E. 1.7" lignite.

21, 8 N., 20 E. 3.6' lignite.

21, 8 N., 20 E. 1.4' lignite.

21, 8 N., 20 E. 5-2' lignite.

31-32, 8 N., 20 E., 1.8' bed volcanic ash.

31-32, 8 N., 20 E., 1.7' lignite.

31-32, 8 N., 20 E., 2.8' lignite.

31-32, 8 N., 20 E.,.1.1' lignitic shale.

Silver Bow Valley district, Silver Bow and 

Deer Lodge Counties

At two localities near Anaconda, thin impure 

Cretaceous coals are exposed. At locality 11 (pi. 1), 

sec. 10, T. 4 N., R. 11 W., haM a mile south of 

Anaconda, 2 feet of coaly shale is exposed and contains

0. 002 percent equivalent uranium. At locality 12, 

sec. 33, T. 5 N., R. 11 W., about li miles west of 

Anaconda, a total of 4 feet 4 inches of impure coal is 

exposed. Two channel samples of two beds were submitted for chemical determinations. Both samples 

had an equivalent uranium value of 0. 002 percent and 

contained less than 0.001 percent uranium in the ash.

Table 4. Samples collected in the Silver Bow Valley district

Lab. 

no.

63967 

63968 

63966

Field 

no.

MM-90 

MM-91 

MM-89

Percent

eU

0.002 

.002 

.002

U

 

U in 

ash

---

Ash

45.6 

86.6

Location (Section, Township, Range) 

and description

33, 5 N., 11 W., 2.9' coaly shale. 

33, 5 N., 11 W., 1.5' coal 

10, 4 N., 11 W., 2.0" coaly shale.

Upper Ruby River district, Madison and 

Beaverhead Counties

Coal of Late Cretaceous age is exposed along 

the course of the upper part of the Ruby River 

in the valley between the Snow Crest Mountains 

on the west, and the Gravelly Range on the east.

The coal beds are interbedded with brown 

and gray shale and siltstone. Several old prospect 

pits, and one mine, the Basin Creek mine (sec. 28, 

T. 11 S., R. 3 W.), are present in the area. Most

of the coal beds are less than 1 foot thick, 

although the coal bed in the Basin Creek mine 

is 2| feet thick.

Tertiary and Cretaceous volcanic rocks in 

the vicinity of these prospects and the mine may 

at one time have been a potential source for uranium. However, the coal beds are separated from 

the volcanic rocks by several hundred feet of 

impervious sediments, and the geologic conditions 

for mineralization by downward percolation of 

ground water are not favorable. Five samples
were collected for analysis. Only one showed any 

radioactivity, and this sample of a bed 1 foot

thick contained only 0.002 percent equivalent 

uranium.

Table 5. Samples collected in the Upper Ruby River district

Lab.

no.

65271

65272

65274

65275

65275

65276

Field

no.

MM-44

MM-45

MM-47

MM-48

MM -46

MM-49

Percent

CU

a

0.002

a

a

a

.002

U

___

 

 _

 

U in

ash

___

 

 _

 

AaVi

17.5

74.5

5.55

12.6

14.1

95.8

Location (Section, Township, Range)

and description

20, 10 S., 5 W., 1.0' coal bed.

Ni 28, 10 S., 5 W., 1.0' coaly shale.

NE£ 28, 11 S., 5 W., 1.5' coal bed.

NEi 28, 11 S., 5 W., 1.2' coal bed.

NE£ 29, 11 S., 5 W., 0.8' coal bed.

SE£ 28, US., IE., 6.0' volcanic ash.

TERTIARY LIGNITE AND CARBONACEOUS 

SHALE

Basinlike depressions that separate the various 

mountain ranges in western Montana and adjacent parts 

of Idaho are filled with poorly to well-indurated lightgray, tan, and buff clays, shales, siltstones, and volcanic ash. The deposits range in age from Oligocene 

to Miocene and perhaps Pliocene. The deposits are 

commonly known as "lake beds" and are so called in 

this report although little evidence of typical lacustrine 

conditions of deposition was noted. Numerous poorly 

consolidated tuffaceous sands and gravels are common. 

A few 6- to 30-inch lenticular beds of lignite are exposed at several places along the margins of the basins.

Remnants of volcanic rocks in the form of flows 

and ash beds occur throughout the.. Tertiary basins of 

southwestern Montana but in general are poorly exposed. 

Tertiary volcanic ash, rhyolite, and basalt flows are 

common in the mountain ranges that bound the basins 

and are generally better exposed than their counterparts in the adjacent basins.

Pleistocene and Recent gravel mantles all of the 

basin deposits, and good natural exposures are rare. 

The lignites are thin and lenticular and are exposed 

at few places. All of the Tertiary lake beds examined

are deformed by gentle folding and normal faulting. 

The areas in which reconnaissance work was done are 

shown on the accompanying index map (pi. 1).

DESCRIPTION OF DISTRICTS EXAMINED 

Lombard coal field, Broadwater County

A brief reconnaissance was made in Tps. 4and 5N., 

Rs. 2 and 3 E., Broadwater County, Mont., at the 

approximate site of the Lombard coal field as discussed 

in U. S. Bureau of Mines Technical Paper T529 and 

summarized by Combo and others (1950). Surface 

outcrops and mines discussed in the above papers were 

not found. Local residents knew of no coal-mining 

operations in the area in the past but pointed out an 

entry 1,000 feet long that was made along a bed of 

block shale in an attempt to locate coal.

Smith River Valley district, Meagher County

No significant deposits of lignite or carbonaceous 

shale were found in the poorly exposed Tertiary beds near 

White Sulfur Springs in the Smith River Valley district.

Analyses of samples of volcanic ash collected 

in the district are shown in table 6.

Table 6. Samples collected in the Smith River Valley district

Lab,

no.

66701

66702

66700

66698

66699

Field

no.

MM- 109

MM- 110

MM-108

MM-106

MM- 107

Percent

pTT

0.005

.002

.002

.002

.002

U

*

 

 

 

 

- 

U in

ash

 

 

 

---

Ash

95.0

91.1

91.1

92.5

Location (Section, Township, Range)

and description

8-9, 6 N., 7 E., grab sample volcanic ash.

9, 7 N., 7 E., grab sample volcanic ash.

12-15, 9 N., 5 E., grab sample volcanic ash.

W|- 14, 10 N., 5 E., grab sample volcanic ash.

SWij- 26, UN., 4 E., grab sample volcanic ash.

Townsend Valley district, 

Broadwater County

Only one small deposit of lignite was found in the 

Tertiary lake beds in the Townsend Valley (locality 2,

pi. 1). The lignite is in sec. 17, T. 5 N., R. 3 E. 

and is overlain by several hundred feet of Oligocene 

tuffaceous shales, clays, and sandstones that are exposed south of Sixmile Creek in T. 5 N., R. 3 E. 

The lignite consists of two beds having a total thickness
of about 5 feet, interbedded with about 7 feet of darkbrown carbonaceous shale. Two samples of the lignite

and two samples of tuffaceous shale or argillaceous 

ash contained less than 0.001 percent uranium.

Table 7. Samples collected in the Townsend Valley district

Lab. 

no.

66756 

66757 

66755 

66758

66753 

66754

Field 

no.

MM-164 

MM -165 

MM-163 

MM-166 

MM-161 

MM-162

eU

0.001 

a 

.003 

a 

a, 

.002

Per

U

 

cent

U in 

ash

___

Ash

38.2 

45.8

27.7

Location (Section, Township, Range) 

and description

17, 5 N. 8 E. 3.0' lignite. 

17, 5 N. 8 E. 2.1' lignite. 

17, 5 N. 8 E. 2.0' volcanic ash. 

17, 5 N. 8 E. grab sample of lignite. 

12, 5 N. 2 E. grab sample Pardee Unit 2. 

12, 5 N. 2 E. grab sample Pardee Unit 3.

Gallatin Valley district, Gallatin County

-The Tertiary lake deposits that floor the 

Gallatin Valley district are well exposed along 

the east side of the Madison River south of 

Logan, Mont. The deposits in this vicinity 

are composed of tan to buff tuffaceous shales, 

siltstones, sandstone, and gravel. Volcanic

ash beds are present in places. A sample 

of a volcanic ash from locality 3, sec. 9, 

T. IN., R. 2 E. (pi. 1) contained 0.002 percent equivalent uranium and 0.001 percent uranium. 

In general, the Tertiary lake beds are poorly 

exposed and at most places are covered with a 

heavy mantle of gravel. No lignite or carbonaceous 

shale beds were found.

Table 8. Samples collected in the Gallatin Valley district

Lab. 

no.

62082 

62083

Field 

no.

MM-38 

MM-39

Percent

eU

0.002 

.002

U

0.001

U in 

ash

 

Ash

___

Location (Section, Township, Range) 

and description

9, IN., 2 E., 0.9' volcanic ash. 

9, IN., 2E., 0.9' tuffaceous sandstone.

Prickly Pear Valley district, 

Lewis and Clark County

The Prickly Pear Valley district includes parts 

of the drainage basins of Sevenmile Creek, Ten - 

mile Creek, and Prickly Pear Creek, adjacent 

to the Missouri River. Exposures of the Tertiary 

lake beds in this district are restricted to the 

broad flat or rolling interstream areas and are 

poor. It was possible to obtain samples at only 

two of the localities visited. A sample of 

weathered lignite, obtained from a mine dump on 

the west side of Silver Creek (locality 4, pi. 1), 

contained less than 0.001 percent uranium.

West of Houser Lake, beds of Oligocene age are 

exposed in a series of low rolling hills (Lorenz and others, 

1951, p. 16). In this area the beds are predominantly 

light-tan to buff tuffaceous shales and siltstones. A

few thin bentonitic ash beds are also present. The 

adjacent areas are under cultivation, and exposures are 

poor. At locality 5 (pi. 1) in the NWi sec. 28, T. 11 N., 

R. 2 W., bentonitic ash and one 6-inch bed of carbonaceous 

shale is exposed. A sample of the carbonaceous shale 

contained 0. 014 percent equivalent uranium and 0. 013 percent uranium. The overlying bentonitic ash contained 

0.003 percent equivalent uranium. The devitrification 

of this ash, accompanied by leaching, may account for 

the high uranium content of the underlying carbonaceous 

shale. The uranium content of 0.013 percent is the 

highest determined for any sample of lignite or carbonaceous shale obtained in this reconnaissance examination. 

Additional examination of the immediate vicinity was 

hampered by the extent of cover.

Reconnaissance throughout the remainder of this 

district did not detect other abnormally radioactive 

lignite or carbonaceous shale beds.

Table 9- Samples collected in the Prickly Pear Valley district

1

Lab.

no.

66750

66751

66752

Field

no.

MM-158

MM-159

MM-160

Percent

eU

0.003

.014

.001

U

__

0.013

U in

ash

__

___

 

Ash

__

_ _ 

32.2

.

Location (Section, Township, Range)

and description

NW£ 28, 11 N., 2 W., 2.0' volcanic ash.

NW£ 28, 11 N., 2 W., 0.5' carbonaceous shale.

SW£ 8, 11 N., 4 W., grab sample of lignite.
Avon Valley district, 

Powell County

The Tertiary lake beds in the Avon Valley district 

are poorly exposed and no evidence of appreciable deposits of lignite or carbonaceous shale was found. A

carbonaceous shale zone 5. 5 feet thick was examined 

and sampled at locality 6 (pi. 1), sec. 21, T. UN., 

R. 8 W"., but the shale did not contain significant 

quantities of uranium. Further exploration of the 

Tertiary lake beds of this district failed to discover 

other deposits of carbonaceous shale.

Table 10. Samples collected In the Avon Valley district

Lab. 

no.

639^9 

63950

Field 

no.

MM-72 

MM-73

Percent

eU

0.002 

.001

U

 

U in 

ash

 

Ash Location (Section, Township, Range) 

and description

21, UN., 8 W. , upper 2.8" carbonaceous shale. 

21, UN., 8 W., lower 2.8" carbonaceous shale.

Blackfoot Valley district, Powell, Granite, 

and Missoula Counties

Reconnaissance of the poorly exposed Tertiary 

lake beds in the Blackfoot Valley district near Helmville, 

Mont, did not reveal significant deposits of lignite or 

carbonaceous shale. Abnormal radioactivity was not 

detected in any of the Tertiary lake beds examined in 

this district.

Flint Creek Valley district, 

Granite and Powell Counties

The Tertiary lake beds are poorly exposed in the 

Flint Creek Valley district and are covered at most 

places by a thick mantle of stream gravels. At locality 7 

(pi. 1), NWi sec. 35, T. UN., R. 13 W., about 

40 feet of lignitic and carbonaceous shales is exposed. 

Radiometric examination of the outcrop with a GeigerMuller counter did not detect significant radioactivity, 

but one sample of carbonaceous shale contained 0. 006 percent uranium. Uranium was absent in all other samples. 

The sample containing 0. 006 percent uranium represents 

a 4-foot channel sample of the uppermost carbonaceous 

shale.

It is possible that other uraniferous beds may be 

in the area, but the poor condition of outcrop made their 

presence difficult to ascertain. Additional investigation 

of this immediate vicinity with more sensitive instruments 

might prove to be of value. Numerous other localities 

were visited in the area, but no significant radioactivity 

was detected.

Locality 8 (pi. 1), in the NWi sec. 18, T. 9 N. , 

R. 12 W., is a coal prospect in steeply dipping 

Cretaceous beds. Examination and sampling of the 

thin impure coal at this locality failed to reveal any 

radioactivity.

Table 11. Samples collected in the Flint Creek Valley district

Lab. 

no.

63951

63952

63953

6395^

63955

63956

63957

63958

63959

Field 

no.

MM-74

MM-75

MM-76

MM-77

MM-78

MM-79

MM-80

MM-81

MM-82

eU

0.004

a

a

a

a

a

a

a

a

Per

U

0.006

 

 

 

 

 

cent

U in 

ash

__ _

 

 

 

 

 

 

Ash

...

29.9

32.8

26.0

28.9

35.9

50.6

88.6

57-2

Location (Section, Township, Range) 

and description

NW£ 35, 11 N. 13 W. 4.0' carbonaceous shale.

NW£ 35, UN. 13 W. 1.5' lignite.

HW£ 35, UN. 13 W. 2.5' lignite.

NW£ 35, 11 N. 13 W. 1.8' lignite.

NV/i 35, 11 N. 13 W. 0.3' lignite.

IWfc 35, 11 N. 13 W. 2.5' lignite.

NW£ 35, 11 N. 13 W. 3-0' lignite.

NW£ 35, 11 N. 13 W. 4.0' coal ash.

NV/i 18, 9 N., 12 W., 1.0' coaly shaJe.

Deer Lodge Valley district, 

Deer Lodge and Powell Counties

Reconnaissance in the Deer Lodge Valley 

district did not find any appreciable deposits of 

radioactive lignite or carbonaceous shale. At

locality 9 (pi. 1), in sec. 24, T. 9 N., R. 11 W., 

two beds of carbonaceous shale, each about 1 foot 

thick, are overlain by an undetermined thickness 

of light-gray tuffaceous shale and volcanic ash. 

Samples of carbonaceous shale contained less than 

0.001 percent uranium.

Table 12. Samples collected in the Deer Lodge Valley district

Lab.

no.

63946

63947

63948

63945

Field

no.

MM-69

MM-70

MM-71

MM-88

Percent

eU

0.002

.001

.002

a

U

a

 

 

 

U in

ash

_ __

 

 

Ash

_ __

 

 

 

Location (Section, Township, Range)

and description

18, 6 N., 10 W., 2.0' volcanic ash.

24, 9 N., 11 W., 1.0' carbonaceous shale.

24, 9 N., 11 W., 1.2' carbonaceous shale.

24, 9 N., 11 W., 2.0' volcanic ash.
Missoula Valley district, 

Missoula County

Extensive reconnaissance was made of the 

Tertiary lake beds in the Missoula Valley district. 

Exposures of coal-bearing sediments are very poor 

in this district, and a majority of samples had to be 

collected from abandoned mine dumps. Samples 

were collected at 6 localities and 15 other localities 

were examined but not sampled. Significant radioactivity was not detected at any of the localities examined.

Most of- the samples came from the immediate vicinity of Missoula near the Hell Gate 

mine, locality 15 (pi. 1) where small scale 

mining activity was carried on prior to 1940 

(Pardee, 1913, pp. 240-241). In this area, four 

coal beds from 1 to 6 feet thick and overlain 

by volcanic ash have been reported; three of 

these four beds were sampled. None of the 

samples submitted contained more than 0.001 percent uranium.

Table 15. Samples collected In the Missoula Valley district

Lab. 

no.

66757

66758

66759

66740

66741

66742

66745

66744

6675^

66745

66694

Field 

no.

MM-145

MM-146

MM-147

MM-148

MM-149

MM-150

MM-151

MM-152

MM-144

MM-155

MM-102

Percent

eU

a

0.002

.002

.005

.001

a

a

a

a

.001

a

U

___

___

 

 

 

 

 _

 

 

 

U In 

ash

___

___

 

 

 

 

 

 

 

Ash

15.5

67.7

70.5

 

26.2

11.2

24.0

59-0

58.6

28.0

Location (Section, Township, Range) 

and description

E^ 4, 14 N., 19 W., grab sample lignite.

E| 4, 14 N., 19 W., upper 2.0' of 4.0' lignitic shale

E^ 4, 14 N., 19 W., lower 2.0' of 4.0' lignitic shale

E^ 4, 14 N., 19 W., 5.0' volcanic ash.

SE^- 55, 14 N., 19 W-, grab sample lignite.

SE£ 55, 14 N., 19 W., grab sample lignite.

C. 55, 14 N., 19 W., grab sample lignite.

C. 55, 14 N., 19 W., grab sample lignite.

NWf 26, 14 N., 22 W., grab sample lignite.

SwJ- 4, 15 N., 22 W., grab sample lignite.

21, 16 N., 25 W., grab sample lignite..

Bitterroot Valley district, Ravalli County

Lignite and carbonaceous shale were found at 

only one place in the poorly exposed Tertiary lake 

beds in the Bitterroot Valley district south of Hamilton, 

Mont. At locality 10 (pi. 1), in the NWiSEi sec. 34, 

T. 4 N., R. 21 W., near Darby, more than 20 feet 

of lignite and carbonaceous shale is exposed (Pardee,

1913, p. 242). Channel samples were taken of six 

of the most lignitic beds in the sequence, and the 

entire section was examined radiometrically. None 

of the beds indicated significant radioactivity in the 

field, and of the six samples analyzed only one contained as much as 0.002 percent uranium in the ash. 

The remaining five samples contained less than 

0.001 percent uranium.

Table 14. Samples collected in the Bitterroot Valley district

Lab. 

no.

66688 

66689 

66690 

66691 

66692 

66695

Field 

no.

MM-96 

MM-97 

MM-98 

MM-99 

MM-100 

MM-101

eU

a 

a 

a 

a 

a 

0.002

Per<

U

a

sent

U in 

ash

0.002

Ash

27.4 

18.5

21.6 

26.1 

25-5 

56.2

Location (Section, Township, Range) 

and description

NW-tNEt 54, 4 N. 21 W. 2.0' lignite. 

NWtNEt 54, 4 N. 21 W. 0.7' lignite. 

NWtNEt 54, 4 N. 21 W. 0.5' lignite. 

NWtNEt 54, 4 N. 21 W. 1.1' lignite. 

NWtNEt 54, 4 N. 21 W. 1.9' lignite. 

NWtNEt 54, 4 N. 21 W. O.I 1 lignitic shale.

Big Hole Valley district, 

Beaverhead County

Reconnaissance of the Big Hole Valley district in 

the vicinity of Wisdom, Jackson, andFishtrap, Mont., 

did not find lignite or carbonaceous shale. Although 

exposures of significant thickness of Tertiary lake beds 

are poor or non-existent, except along the margins of 

the valley, it is doubtful whether carbonaceous beds 

of appreciable thickness are present.

Silver Bow Valley district, Silver Bow 

and Deer Lodge Counties

The Silver Bow Valley district includes 

the towns of Anaconda and Butte and the adjacent county to the south of Anaconda. The 

lake beds are poorly defined in this district, 

and the occurrence of Tertiary lignite deposits 

is unknown.
Jefferson Valley district, Silver Bow 

and Madison Counties

Reconnaissance of the Jefferson Valley district 

south of Whitehall, Mont., did not discover any 

significant deposits of lignite or carbonaceous shale 

in the Tertiary lake beds. Exposures in the valley 

are poor.

Beaverhead Valley district, Beaverhead 

and Madison Counties

No deposits of lignite or carbonaceous shale were 

found in the reconnaissance of the Beaverhead Valley 

district in the immediate vicinity of Dillon, Mont. 

The Tertiary lake beds, which are restricted to the 

valley proper, are poorly exposed and it is unlikely 

that they contain uraniferous lignite.

Madison Valley district, Madison County

Tertiary lake beds are poorly exposed in the 

Madison Valley district, and appreciable deposits of 

lignite or carbonaceous shales are not evident.

Centennial Valley district, Beaverhead County

The Tertiary beds in the vicinity of Lima and 

Dell, Mont., in the Centennial Valley district, are

quite unlike those of other districts. These beds are 

composed of red poorly consolidated conglomerate, 

sandstone, siltstone, shale with some interbedded 

basalt, and rhyolite. Lignite and carbonaceous 

shales were not found.

Medicine Lodge Creek Valley district, 

Beaverhead County

In this general district at least three beds of 

lignite are interbedded with light-gray to brown 

shales, siltstones, and thin sandstones. The lignite 

beds range from 2 to 5 feet in thickness, and at many 

places contain numerous thin partings of carbonaceous 

shale which contribute to the high ash content of the 

lignite. These beds are part of the best exposures of 

coal-bearing Tertiary lake deposits examined in 

southwestern Montana. Small-scale mining has been 

intermittently active in this district for more than 

30 years. Operations were discontinued during the 

winter of 1949-50 because of the local labor conditions 

and a poor market for high-ash lignite.

Seven localities were examined and 12 samples 

taken. Two of the mines can still be entered and 

sampling of moderately fresh coal was possible. Of 

the 12 samples submitted for analysis, 4 contained 

0. 003 percent equivalent uranium, 1 contained 

0. 002 percent equivalent uranium, and 1 contained 

0.001 percent equivalent uranium. The remaining samples contained less than 0.001 percent equivalent uranium.

Table 15. Samples collected in the Medicine Lodge Creek district

Lab. 

no.

63294

63277

63278

63279

63284

63285

63282

63283

63286

63287

63280

63281

Field 

no.

MM-67

MM-50

MM-51

MM-52

MM-57

MM -58

MM-55

MM-56

MM-59

MM-60

MM-53

MM-54

eU

a

0.003

.003

.003

.003

.002

a

a

.001

a

a

a

Perc

U

 

 

 

 

 

 

a

 

 

 

snt

U in 

ash

_ 

 

 

 

 

 

0.001

 

___

Ash

44.7

64.2

 

71-5

79.7

73.5

19.1

15.4

24.5

28.3

19.6

21.0

Location (Section, Township, Range) 

and description

C 6, 10 S., 12 W., grab sample lignite.

SW£ 18, 11 S., 11 W. 1.5' lignitic shale.

SW£ 18, 11 S., 11 W. 1.5' carbonaceous shale.

SW£ 18, 11 S., 11 W. 1.5' lignitic shale.

SW£ 30, 11 S., 11 W. 3.0' lignitic shale.

SW£ 30, 11 S., 11 W._ 1.6' lignitic shale.

SE£ 2, 11 S., 12 W., grab sample lignite.

C 14, 11 S., 12 W., grab sample lignite.

SW£ 35, 11 S., 12 W., upper 2.5' of 5.0' lignite

SW£ 35, 11 S., 12 ¥., lower 2.5' of 5.0' lignite

Si 35, 11 S., 12 W., 'upper 2.8' of 4.9' lignite.

si 35, 11 S., 12 W., lower 2.1' of 4.9' lignite.

Lemhi Valley district, 

Lemhi County, Idaho

Tertiary beds are extensively exposed along the 

Salmon River in the vicinity of the town of Salmon. 

Exposures of these beds are poor except along the 

river where there are cliffs 200 to 300 feet high. 

The lake beds consist of tan to buff shale, siltstone, 

and sandstone, with thin beds of'carbonaceous shals. 

Lignite in this area seems to be restricted to the 

western part of the valley.

In Pollard Canyon, li miles west of Salmon, 

a 6-foot bed of impure lignite is mined from time 

to time (locality 13, SWi sec. 2, T. 21 E.). (See 

pi. 1.) The lignite was examined radiometrically,

and two channel samples of the fresh lignite were 

taken. These samples contained less than 0.001 percent equivalent uranium.

At locality 14, sec. 15, T. 23 N., R. 20 E., 

18 miles northwest of Salmon, more than 200 feet of 

coal-bearing strata are exposed along the east bank 

of Moose Creek. These coal-bearing beds are 

restricted to a small, high intermountain basin that is 

estimated to cover 600 acres and is bounded by 

granitic rocks on all sides. Fifteen to twenty thin 

beds of lignite are interbedded with soft tan shales 

and unconsolidated arkosic sands. The lignite is 

predominantly woody, weathers rapidly, and is 

probably younger than the lignites in the Tertiary 

beds near Salmon.
No radioactivity was detected in any coal bed. 

Two channel samples of a 5-foot bed, the uppermost 

in the exposed section, contained less than 0.001 percent equivalent uranium.

Examination of the Lemhi Valley district 

has not revealed any uraniferous lignite of

potential commercial grade. Additional investigation of this area does not seem worthwhile, 

except to the south in the vicinity of Challis, 

Idaho, where reconnaissance was not made in 

1951 because of lack of time. Reconnaissance 

examinations will be made of these rocks when 

feasible.

Table 16. Samples collected in the Lemhi Valley district

Lab.

no.

65960

65961

65962

65965

Field

no.

MM-85

MM-84

MM-85

MM-86

Percent

pTT

a

0.001

a

a

U

a

 

 

U in

ash

0.001

 

 

flaV,

45.6

42.6

16.2

12.1

Location (Section, Township, Range)

and description

SWi 2, 21 N., 21 E., upper 5-0 1 of 6.0' lignite.

SW£ 2, 21 N., 21 E., lower 5.0' of 6.0' lignite.

15, 25 N., 20 E., upper 2.5 1 of 5-0 1 lignite.

15, 25 N., 20 E., lower 2.5' of 5-0 ' lignite.

LITERATURE CITED

Andrews, D. A., Lambert, G. S., and Stose, G. W., 

1944, Geologic map of Montana: U. S. Geol. Survey Oil and Gas Inv. Prelim. Map 25.

Calvert, W. R., 1912, The Livingston and Trail Creek 

coal fields, Park, Gallatin, and Sweetgrass Counties, 

Mont., in Coal fields in Montana: U. S. Geol. Survey Bull. 471-E, pp. 28-49.

_________1912, The Electric coal field, Park 

County, Mont., in Coal fields in Montana: U. S. 

Geol. Survey Bull. 471-E, pp. 50-66.

Combo, J. X., Holmes, C. N., and Christnel, H. R., 

1950, Coal resources of Montana: U. S. Geol. Survey Inv. Map C 2.

Denson, N. M., Bachman, G. O., and Zeller, H. D., 

1950, Summary of new information on uraniferous 

lignites in the Dakotas: Unpublished report in files 

of U. S. Geol. Survey as Trace Elements Memo. 

Rept. 175.

Ellis, A. J., and Meinzer, O. E., 1924, Groundwater in Musselshell and Golden Valley Counties, 

Mont.: U. S. Geol. Survey Water Supply Paper 518.

Lorenz, H. W., and Swenson, F. A., 1951, Geology 

and ground-water resources of the Helena Valley, 

Montana with a section on the chemical quality 

of the water by H. A. Swenson: U. S. Geol. Survey Cir. 83, p. 68.

Pardee, J. T., 1911, Coal in the Tertiary lake beds 

of southwestern Montana, in Contributions to economic 

geology: U. S. Geol. Survey Bull. 531, pp. 229- 

244.

__________1925, Geology and ground-water resources of Townsend Valley, Montana: U. S. Geol. 

Survey Water Supply Paper 539, 61 pp.

1932, Analyses of Montana coals:

U. S. Bur. Mines Tech. Paper T529, 123 pp.

INT.-DUP. SEC., HASH.. D.C. ?6760
UNITED STATES DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY CIRCULAR 251 PLATE 1

White Sulphur 

Springs

__JQ._W_T^A N A 

W Y 0 M }| N 6

EXPLANATION

Tertiary lake bed deposits

Coal fields 

Areas examined listed below

1. Livingston-Trail Creek Coal Field

	*

2. Electric Coal Field

3. Lombard Coal Field

4 Ryegate District

5. Smith River Valley

6. Townsend Valley

7. Gallatin Valley

8. Prickly Pear Valley

9. Avon Valley

10. Blackfoot Valley

11. Flint Creek Valley

I 2. Deer Lodge Valley

I 3. Missoula Valley

I 4. Bitterroot Valley

I 5. Big Hole Valley

I 6. Silver Bow Valley

I 7. Jefferson Valley

18. Beaverhead Valley

I 9. Madison Valley

20. Upper Ruby River Valley

2 I. Centennial Valley

22. Medicine Lodge Creek Valley

23. Lemhi Valley

Locality referred to in text

0 6 10 iO 3O 40 MILES

Modified after Andrews et alJ944, Combo et al, 1950 

and Pardee 7 l9ll

INDEX MAP OF SOUTHWESTERN MONTANA SHOWING AREAS PROSPECTED FOR URANIUM-BEARING LIGNITE