RC: 303;

GEOLOGICAL SURVEY CIRCULAR 303

STRATIGRAPHIC SECTIONS 

OF THE PHOSPHORIA 

FORMATION IN MONTANA 

PART 2, 1949-50

m: **" 

Prepared as part of the program of 

the Department of the Interior for 

development of the Missouri River 

Basin and of work done on behalf of 

the U. S. Atomic Energy Commission. 

The report is published with the 

permission of the Commission.
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas MeKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 303

STRATIGRAPHIC SECTIONS OF THE PHOSPHORIA FORMATION IN MONTANA

PART 2,1949-50

By R. W. Swanson, E. R. Cressman, R. S. Jones, and B. K. Replogle

Prepared as part of the program of 

the Department of the Interior for 

development of tfie Missouri River 

Basin and of work done on behalf of 

the U. S. Atomic Energy Commission. 

The report is published with the 

permission of the Commission.

Washington, D. C.,1953

Free on application t»the Geological Survey, Washington 25, D. G.
STRATIGRAPHIC SECTIONS OF THE PHOSPHORIA FORMATION IN MONTANA

PART 2, 194&-50

By R. W. Swanson, E. R. Cressman, R. S. Jones, and B. K. Replogle

CONTENTS

Lot no. Page

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

Acknowledgments................... 1

Stratigraphy of the Phosphoria

formation in Montana ............. 4

Stratigraphic sections............... 4

Selected bibliography ............... 4

Tables of Stratigraphic

sections

Moonlight Adit ................ 1340 5

Lot no. Page

Tables of Stratigraphic 

sections Continued

Anaconda quarry.............. 1337 7

Canyon Camp................. 1311 8

Warm Springs Creek.......... 1300 11

Lazyman Hill................. 1319 13

Alpine Creek................. 1307 16

Sliderock Mountain............ 1301 18

Taylor Creek, Idaho .......... 1342 21

ILLUSTRATIONS

Figure 1. Outcrops of the Phosphoria formation in Montana and localities sampled..........

2. Generalized section of the Phosphoria formation at Sheep Creek, Montana, lot no. 1234

Page

2

3

INTRODUCTION

The U. S. Geological Survey has recently measured and sampled the Phosphoria formation at many 

localities in Montana and other western states. These 

data will not be fully synthesized and analyzed for 

several years, but segments of the data, accompanied 

by little or no interpretation, are published as preliminary reports as they are assembled. This report, 

which contains abstracts of many of the sections in 

southwestern Montana (fig. 1), is one of this series 

and is the fourth Montana report; it includes the second 

half of the data gathered in Montana during 1949 and 

1950. The field and laboratory procedures adopted in 

these investigations are described rather fully in a 

previous report (McKelvey and others, 1953).

Many people have taken part in this investigation. 

The program of which this work is a part was organized 

byV. E. McKelvey. J. L. Elliott, W. J. Garmoe, 

R. F. Gosman, C. W. Tandy, and W. H. Wilson participated in the description of strata and the collection 

of samples referred to in this report. Crushing and 

splitting of the samples in the field was done by 

T.K. Rigby. The laboratory preparation of samples 

for chemical analysis was done in Denver, Colo. , 

under the direction of W. P. Huleatt.

The PgOs and acid- insoluble analyses were 

made for the Survey by the U. S. Bureau of Mines at

the Northwest Electrodevelopment Laboratory, 

Albany, Oreg., under the direction of S. M. Shelton 

and M. L. Wright. The A1 2O 3 , Fe 2O 3 , and loss-onignition analyses were made in the Trace Elements 

Section laboratory of the Survey in Washington, D. C., 

under the direction of J. C. Rabbitt by chemists 

H. Alberty, I. Barlow, T. Parley, C. Hoy, and 

M. Landers.

Compilation of the data has been by K. S. Bergman. 

Organization of the tabular data has been largely by 

Anita Wise.

AC KNOWLEDGMENTS

Special thanks are due A. E. Weissenborn and 

M. R. Klepper, who gave much advice and help in 

carrying out the field program. The field and laboratory investigations have been conducted as part of 

the program of the Department of the Interior for the 

development of the Missouri River Basin and on behalf of the Division of Raw Materials of the Atomic 

Energy Commission.

It is a pleasure to acknowledge the fine 

cooperation extended to the field parties by the 

local residents and property owners, who furnished information and services and gave access 

to property.
113° 112° 111°

EXPLANATION

Outcrop of Phosphoria formation, 

dotted where questionable PHILIPSBURG

4*

Location and lot number of sample 

locality included in this report

Location and lot number of sample 

locality to be included in later reports

i

Recompiled and modified t 

from Clabaugh. 1946 I

45°

113° 112° 111°

Figure 1. Outcrops of the Phosphoria formation in Montana and localities sampled.

2
PERCENT Pj, 05 

20 10

THICKNESS 

IN FEET

AVERAGE 

PERCENT DESCRIPTION

FEET Dinwoody formation 

Mudscone: calcareous, soft, pale-yellow, thin-bedded

PHOSPHORIA FORMATION

Member E 

Sandstone: hard, pale, yellowish-orange, rhick-bedded

Chert: hard, light-gray, thick-bedded chert interbedded with medium-hard, pale 

yellowish-orange, thick-bedded chert

Sandstone and chert: medium-hard, light-gray, thick-bedded sandstone containing 

some interbeds of hard, light-gray chert

50

Sandstone and chert: medium-hard, brownish-gray, thick-bedded sandstone 

interbedded with hard, light-gray, thick-bedded chert

Sandstone: medium-hard, yellowish-brown, thick-bedded sandstone interbedded 

with hard, brownish-gray sandstone

Chert: medium-hard, dusky yellowish-orange, to medium-brown, thick-bedded

Mudstone: medium-hard, light-gray to yellowish-brown, thick-bedded

100 Sandstone: hard, light-gray to yellowish-brown, thick-bedded; lowermost 0.75 

foot phosphatic

12

Member D 

Mudstone: phosphatic, soft, brownish-black, thin-bedded

Mudstone: soft, brownish-black to black, fissile

ISO 25 Phosphate rock: oolitic, soft, dark-brown, thin-bedded

14

Phosphate rock and mudstone: oolitic, medium-hard, brownish-gray, phosphate 

rock, interbedded with medium-hard, brownish-gray mudstone

Member C 

Sandstone: soft, dusky yellowish-orange, thick-bedded

200 Sandstone and chert: medium-hard, light brownish-gray, massive sandstone 

interbedded with hard, yellowish-gray, massive chert

Dolomite: sandy, medium-hard, medium- to light-gray; contains lenses and 

nodules of chert

Sandstone: soft, dusky yellow, chin-bedded; contains many lenses and nodules 

of chert

250 Chert: hard, medium-gray ro yellowish-brown, thick-bedded; contains same 

interbeds of mudstone and sandstone

Member B

Mudstone: medium-hard, medium yellowish-brown, thin-bedded; contains several 

small lenses of oolitic phosphate rock

300 14 Phosphate rock and mudstone: soft, brownish-gray, oolitic phosphate rock 

interbedded with soft, pale yellowish-brown mudstone

Mudstone: medium-hard, medium yellowish-brown, thin-bedded

Member A 

Mudstone: dolomitic, soft, light-gray, thin-bedded

349 10

Dolomite: medium-hard, pale yellowish-orange, thin-bedded; contains some 

interbedded cherty mudstone

Quadrant formation 

Sandstone: medium-hard, light-gray, thin-bedded

Figure 2. Generalized section of the Phosphoria formation at Sheep Creek, Montana, lot no. 1234.

3
STRATIGRAPHY OF THE PHOSPHORIA FORMATION 

IN MONTANA

The Phosphoria formation in southwestern 

Montana consists in general of five members, two phosphatic shale members, and three hard members (fig. 2). 

The lower two hard members are dominated by limestone and the top hard member by chert and sandstone 

or quartzite. Most of the members can be identified 

over a large part of the area of outcrop, though member 

correlation toward the east and northeast is much more 

difficult. The formation ranges in thickness from less 

than 100 to more than 800 feet.

The lowermost or A_ member is best developed 

toward the west and southwest and consists of limestone 

or dolomite, sandstone, mudstone, and chert with a 

maximum thickness of nearly 350 feet. It overlies the 

Pennsylvania!! Quadrant formation and is probably 

equivalent to the upper member of the Wells formation 

of southeastern Idaho and adjacent Wyoming and Utah 

(McKelvey, 1949).

The lower phosphatic shale or B_ member is 

about 50 feet thick near the southwesTcorner of the 

State but thins markedly to the north and east where in 

some areas it cannot be recognized.

The middle or C_ member consists of as much 

as 200 feet of limestone and/or chert and sandstone. 

The upper phosphatic shale or D_ member is rather 

similar to and much more uniform and widespread than 

the B_ member, though minable phosphate is present 

onlyToward the north end of the field where the full 

thickness of the phosphatic zone may consist of a 

single 3- to 5-foot bed of high-grade phosphate rock.

The uppermost or E_ member is the most widespread and uniform, averaging about 100 feet in thickness and consisting chiefly of siliceous rocks siltstone,

chert, and quartzitic sandstone. It is overlain by 

the Triassic Dinwoody formation in the greater part 

of the area and by the Jurassic Ellis group toward the 

north and northeast.

STRATIGRAPHIC SECTIONS

Analytical data and abstracts of stratigraphic sections measured at eight localities follow. Their locations 

as well as the locations of other sections previously reported (Swanson and others, 1953, Klepper and others, . 

1953, and Cressmanand others, 1953) and sections to be 

reported later are shown in figure 1.

SELECTED BIBLIOGRAPHY

Clabaugh, P. S., 1946, Permian phosphate deposits of Montana, Idaho, Wyoming, and Utah: 

U. S. Geol. Survey, Strategic Minerals Inv. 

Prelim. Map 3-198.

Cressman, E. R., Wilson, W. H., Tandy, C. W., 

and Garmoe, W.. J., 1953, Stratigraphic sections 

of the Phosphoria formation in Montana, 1949- 50, 

pt. 1: U. S. Geol. Survey Circ. 302.

Klepper, M. R., Honkala, F. S., Payne, O. A., and 

Rupple, E. T., 1953, Stratigraphic sections of the 

Phosphoria formation in Montana, 1948: U. S. Geol. 

Survey Circ. 260.

McKelvey, V. E., 1949, Geological studies of the 

western phosphate field:"Am. Inst. Min. Met. Eng. 

Mining Trans., v. 184, p. 270-279.

McKelvey, V. E., Davidson, D. F., O'Malley, F. W., 

and Smith, L. E., 1953, Stratigraphic sections of 

the Phosphoria formation in Idaho, 1947-48, pt. 1: 

U. S. Geol. Survey Circ. 208.

Swanson, R. W., Lowell, W. R., Cressman, E. R., 

and Bostwick, D.. A., 1953, Stratigraphic sections' 

of the Phosphoria formation in Montana, 1947-48: 

U. S. Geol. Survey Circ. 209.
Moonlight Adit, Mont., lot. 1340

D member of Phosphoria formation sampled in Moonlight adit of Sunlight Mining Company, NW^ sec. 29, T. 8 N.

Samples 5903-5907 cut from top of stope above main drift of adit, samples 5908-5914 cut from south end of 

samples 5915-5916 cut from same drift at junction with crosscut. Beds strike N. 30* W. and dip 40* NE. S

insoluble by U. S. Bureau of Mines laboratory, Albany, Oreg., and for other constituents by Trace Element

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses (percent)

P2°5 A1 2°3 Fe2°3

Loss on 

ignition

A

inso

E member of Phosphoria formation basal bed only

E- 1 Chert -- 0.5 -- -- -- -- 

D member of Phosphoria formation

D-13 

D-12 

D-ll 

D-10 

D- 9

D- 8

D- 7 

D- 6 

D- 5

D- 4 

D- 3 

D- 2 

D- 1

"PVirtQnViQ + & f*r\r*]? «_«__ _ _

"PHrtQTiVi a t A Y*nr*lf _._._._.

Sample 5903-RWS represents same beds 

as samples 5908-RWS and 5909-RWS.

Mudstone -- ----- _____ __ _ _

5907-RWS 

5906-RWS 

5905-RWS 

5904-RWS 

5908-RWS

5909-RWS 

5903-RWS

5910-RWS 

5911-RWS 

5912-RWS

5913-RWS 

5914-RWS 

5915-RWS 

5916-RWS

1.9 

.5 

.7 

.4 

1.4

.3 

(1.1)

1.3 

.3 

1.6

.4 

1.0 

.8 

.6

35.4 

22.3 

37.0 

26.7 

33.6

26.2 

32.8

13.0 

8.4 

6.4

1.4 

21.4 

34.2 

31.0

0.78 

5.66 

1.29 

4.86 

2.47

5.54 

3. 11

 9. 52 

10.3 

10.6

11.4 

7. 10 

2.39 

2.63

1.69 

5.16 

1.25 

5.01 

1.35

2.25 

2.27

4.06 

5.59 

4.03

5.83 

4.39 

1.38 

1.58

1. 17 

2.68 

1.22 

2.85 

1.67

3.56 

2.29

4.51 

5. 11 

3.52

4.47 

3.95 

1.97 

2.19

2

1

2

1

4

5

6

7

2

1

C member of Phosphoria formation upper part only

C- 2 

C- 1

f1 V*OT*1" anrl nnaT*'f'7i io

Breccia, phosphatic sandstone, and

_ .

1.3 

2.0 _ _ .

 

 

Lower part of Phosphoria formation measured in outcrop and hand trenches on north side of Little Gold Creek, SW£ 

County, Mont. This locality is nearly 1 mile SE of Moonlight adit portal. Beds strike N. 40* W. and dip 25

and D member is sheared and not well enough exposed to sample.

E member of Phosphoria formation basal part only

E- 2 

E- 1 --

3.0 

1.0

--

--

-- -- 
Moonlight Adit Continued

Bed 

no. Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses (percent)

P2°5 A1 2°3 Fe2°3

Loss on 

ignition

Ac

inso

D member of Phosphoria formation

D- 2 Phosphatic muds one and phosphate rock-- 

D- 1 Phosphate rock and mudstone------------

Bed D-l probably equivalent to beds D-l 

and D-2 of Moonlight adit.

C-20 Sandstone, quartzitic --- --- _________

C-19 Limestone, cherty, recrystallized ___ __ 

C-18 Limestone, cherty------ -- _ _______

C-17 Covered------------ ------ --- _

C-16 Limestone, recrystallized, contains

sulfides - _______ __ ---------

C-15 Marble -- -

C-14 Covered---------- __________

C-13 Marble, cherty----------- -- --

o> C-12 Marble and chert---- --- ------------

C-ll Marble, cherty----------------- ------

C-10 Quartzite ------------- --_--_- _

C- 9 Marble, cherty--- --------------------

C- 8 Marble, cherty --_--- _-___ 

C- 7 Marble, cherty-- -------- ----- _

C- 6 Quartzite---------- ----- ----- -

C- 5 Marble--------------------------------

C- 4 Quartzite------------------------------

C- 3 Marble------ -------- ____

C- 2 Marble -

C- 1 Sandstone, conglomerate, and silt--------

Possibly glacial debris forced between beds 

at Quadrant-Phosphoria contact.

Cq-1 Quartzite ------ ________ ____________

5.3 

1.7

C member of Phosphoria formation

2.4

13.0

4.0

1.2

1.9

5.3 

2.5 

5.3 

9.1 

3.0

1.8 

2.0 

9.8 

1.3 

3.7

5.3

.2

1.0

3.8

.7

Quadrant formation top bed only

5. 
Anaconda Quarry, Mont., lot 1337

Part of Phosphoria formation measured and sampled in outcrop and hand trench in bluff about i mile east of limesto

Company, north side of Wcrm Spring Creek, sec. 23, T. 5 N., R. 12 W., Deerlodge County, Mont. Beds in 

and graphitic, correlations uncertain. Beds strike N. 75° E. and dip 25° N. Section measured by R. W. Sw

August 1950. Samples analyzed for P^Oc and acid insoluble by U. S. Bureau of Mines laboratory, Albany, O

Trace Elements Section laboratory, U~ S. Geological Survey. Washington, D. C.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses (percent)

P2°5 A1203 Fe 203

Loss on 

ignition

A

inso

E member of Phosphoria formation top not exposed

E- 3 

E- 2 

E- 1

f^no Tpty " to ____*^_____ ___ _

3.8 

28.7 

7.7 __ __

--

_ 

D member of Phosphoria formation

D-12 

D-ll 

D-10 

D- 9 

D- 8

D- 7

D- 6 

D- 5 

D- 4

D- 3 

D- 2 

D- 1

Quartzite, phospha tic ------- -------- -

*DV| f\c* i^l*i Q to T1 f\f*]r _

Phosphate rook ---- --- -

Phosphate rock, argillaceous (appears

Mudstone and phosphate rock - ---- --

Mudstone - --- ------------- -- -

Mudstone, phosphatic - - - -

5902-RWS 

5901-RWS 

5900-RWS 

5899-RWS 

5896-RWS

5898-RWS

5895-RWS 

5897-RWS 

5894 -RWS 

5893 -RWS

5892-RWS 

5891 -RWS 

5890 -RWS

0.8 

.9 

.9 

.6 

1.8

.9

(.5) 

.4 

1.2 

1.2

1.0 

.6 

.6

18.9 

29.0 

26.6 

32.8 

30.2

11.8

19.2 

14.0 

30.6 

19.3

10.0 

3.9 

7.2

1.48 

1.87 

4.68 

1.28 

3.25

9.12

7.30 

9.96 

3.60 

7.92

10.9 

14.8 

11.6

1.41 

2.23 

1.02 

.68 

1.25

1.23

2.80 

7.93 

1.45 

3.35

4.54 

7.52 

12. 1

0.94 

2.55 

6.79 

4.96 

7.79

12.66

16.52 

13.68 

10.72 

16.36

20.08 

20.54 

25. 16

2

1

1

4

2

3

1

2

4

4

3

C member of Phosphoria formation top bed only

C- 1 -- 2.

-- -- __ 
Canyon Camp, Mor+., lot 1311

Phosphoria formation measured and B and D members sampled at Canyon Camp, Ruby River Canyon, NE-j sec. 18, 

Madison County, Mont., on overturned west limb of Ruby Valley syncline. Beds strike N. 10* W. and dip 50

through C-8 are from natural exposures on north side of canyon 300 feet above river; rest of section from s

beds C-10 through C-25 and E-7 through E-23 from natural exposures and beds D-l through E-6 from prosp

measured by C. W. Tandy, R. S. Jones, E. R. Cressman, R. F. Gosman, and W. J. Garmoe and sampled by 

in August 1949. Samples analyzed by U. S. Bureau of Mines laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

Cumulat

thicknes

(feet)

Dinwoody formation basal bed only

td-l -- 1.8 -- -- 1.8 

E member of Phosphoria formation

E-23

E-22

E-21

E-20

03 E-19

E-18 

E-17 

E-16 

E-15 

E-14

E-13 

E-12 

E-ll

E-10 

E- 9

E- 8 

E- 7 

E- 6 

E- 5 

E- 4

Covered: Phosphoria-Dinwoody contact

arbitrarily placed at top of covered interval. 

Mudstone, cherty -----------------------

Sandstone, cherty, and dolomitic mudstone 

Chert-- -- -- -- -- -- 

Chert, sandy - --- - -- ---- --- 

Chert - 

Chert, dolomitic--- ---- -

Chert, dolomitic and dolomite -- 

Sandstone, cherty and mudstone 

Chert _

Sandstone, cherty 

Chert, sandy ---- 

Chert --- -

Faults of unknown but probably small displacement occur within and at base of bed 

E-ll; thickness given is uncertain.

Chert-- - --- - - - 

Chert, dolomitic ------ --- ___________

Fault of unknown displacement at base of 

bed E-9.

Chert, dolomitic 

Chert, dolomitic 

Chert 

Chert 

Chert ------- 

725- RSJ

724- RSJ

723- RSJ

15.0

12.3

.9

2.7

4.2

12.8 

6.0 

2. 1 

2.0 

1.6

23.3

14.0

15.0

1.7 

3.0

1.5 

.4 

.5

2.0 

.5

0.8 

.8 

.6

80.5

81.7

85. 1

15.0

27.3

28.2

30.9

35.1

47.9

53.9

56.0

58.0

59.6

82.9

96.9

111.9

113.6

116.6

118.1

118.5

119.0

121.0

121.5
E- 3 

E- 2 

E- 1

r^ho-rf ---. ..-..--...-..... __...--.._...- 722- RSJ 

721- RSJ 

720- RSJ

1. 1 

1.4 

1.2

.3

1.8 

. 5

84.4 

76.8 

57.3

122.6 

124.0 

125.2

D member of Phosphoria formation

D-20 

D-19 

D-18 

D-17 

D-16

D-15 

D-14 

D-13 

D-12 

D-H

D-10

D- 9 

D- 8 

D- 7 

D- 6

D- 5 

D- 4 

D- 3 

D- 2 

D- 1

The base of bed D-10 may be a bedding plane

Phosphate rock; fos. col. no. 11683 --------

Muds tone, phosphatic -- - - - - ---------

r^he-r-f ___________________________________

719- RSJ 

718- RSJ 

717- RSJ 

716- RSJ 

715- RSJ

714- RSJ 

713- RSJ 

712-CWT 

711-CWT 

710-CWT

709-CWT 

fault.

708-CWT 

707-CWT 

706-CWT 

705-CWT

704-CWT 

703-CWT 

702-CWT 

701-CWT 

700-CWT

2.3 

3. 2

.9 

.8 

1..4

2.0 

3. 1 

2.6 

1.1 

1.6

.6

.9 

1.6 

1.2 

2.0

3.0 

. 7 

1.4 

2.4 

.6

3.0 

2.8 

.3 

6.9 

25.5

17.6 

15.5 

15.2 

5.8 

7.4

6.1

6.4 

1.3 

6.8 

23.9

1.6 

10.0 

22.9 

2.7 

6.5

69.3 

60.6 

70.0 

50.8 

11.3

5.8 

33.6 

27.2 

41.2 

38.8

44.0

46.0 

8. 7 

40. 7 

11.8

43.2 

47.0 

11.6 

67.8 

71.3

2.3 

5.5 

6.4 

7.2 

8.6

10.6 

13.7 

16.3 

17.4 

19.0

19.6

20.5 

22. 1 

23.3 

25.3

28.3 

29.0 

30.4 

32.8 

33.4

C member of Phosphoria formation

C-25 

C-24 

C-23 

C-22 

C-21

C-20 

C-19 

C-18 

C-17 

C-16

015 

C-14 

C-13 

C-12

Chert, sandy---- --- _____________ _

Dolomite, sandy---- - -____- __ _

fh^T-t -_-_______-»___-____-______________

--

1. 1 

2.0 

1.2 

2.2 

1.8

1.2 

6.4 

14.3 

1.7

.5

4.3 

2. 1 

4.5 

8.2

--

1. 1 

3.1 

4.3 

6.5 

8.3

9.6 

16.0 

30.3 

32.0 

32.5

36.8 

38.9 

43.4 

51.6
Canyon Camp, Mont., lot 1311

Bed 

no.

C-ll

c-io

C- 9

C- 8 

C- 7

C- 6 

C- 5 

C- 4 

C- 3 

C- 2

C- 1

Rock description

Mudstone-- ----------- - _-- - __-

Covered; unable to correlate from north

Chert ----------------------------------

Dolomite -- - ---- - --___ - 

\^rH.\^J. (,j OGLAJLVtV

Sandstone ------------ -_ ______ 

Chert ---- -- ----- _--_-_-

Phdvt

Sample 

no.

732-ERC

Thickness 

(feet)

3.0 

14.3

1.3 

.6

1. 1 

.9 

1.4 

1.4 

4.7

5.0

Chemical analyses 

(percent)

P2°5

0.9

Acid 

insoluble

75.4

Cumulat

thickne

(feet)

54.6 

68.9

70.2 

70.8

71.9 

72.8 

74.2 

75.6 

80.3

85.3

B member of Phosphoria formation

B

e

B- 4

B i

B

_ T

B

_ 1

Phosphate rock; fos. col. no. 11682------ 

Phprt - - - _ -- - -

f Q T»Vvf\na 4-ia ff\r*\f

771 T?!?/"1

Tin Tr>T>/~<

77Q_T7>T>/~1

 7 ->o IT<T> r*

777 _T?'D/~I

0. 7

. 5

1.0

.8

.5

1. 1

27.0

3.0

2.5

5.6

85.8

18. 7

8.8

77. 7

15.8

0.7

1.2

2.2

3.0

3.5

A member of Phosphoria formation base not exposed

A-12

A- l l

A-10

A_ Q

A- 8

A- 7

A- 6

A- *>

A - 4

A. 7

A- 2

A- 1

Dolomite, dolomitic chert, and

Dolomite - -------__-_-__---- ______

Dolomite -- _-___-__- -_---_---_____ 

r"h<sT-t

Dolomite --- --- - ------ _-_ - 

Chert 

Dolomite ----- ______ _ --- --_- 

IVfudstone calcareous 

*

726-ERC

_ 

__

__

_ 

2. 1

1.4

.3

.6

.25

1.3

.2

1.7

.25

2.4

3. 5

5.6

1.2

 «»

 «»

_ _

-» 

_ 

.-

_> 

_ _

28.2

-> 

_, _.

__

__

-> 

-» _.

- _

--

2. 1

3.5

3.8

4.4

4.6

5.9

6.1

7.8

8.1

10.5

14.0

19.6
Warm Springs Creek, Mont., lot 1300

Phosphoria formation measured and B and D members sampled near Warm Springs Creek, NWi sec. 22, T. 9 S., R

Mont., near crest of small anticline. D member measured and sampled in hand trench; rest of formation m

sampled from natural exposures. Beds strike N. 30° E. and dip 2° NW. Section measured by W. H. Wilson

J. L. Elliott and sampled by Elliott, Replogle, and R. F. Gosman in August 1949. Samples analyzed by U. S

laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

Cumula

thickne

(feet)

E member of Phosphoria formation top not exposed

E-13 

E-12

E -i i

E i n

E

n

E - ft

E _ 7

E

(_

E

C

E- A.

E

_ *

E _ f

E

i

Dinwoody-Phosphoria contact covered, 

approximate thickness of covered interval

Sandstone, carbonatic, contains glauconiteChert - -- _ -- _

Sandstone - - --- - ____ 

Phprt

CllGrt 3,I> £?ill£LC6OUS 

f"*hf*T*t

Chert 

Chert _____ __._ 

Chert 

Chert ____ - _ - - -

Phpyt

--

1 1 ft 1 - WWW

3384-WHW

3383-WHW

4.5

4.4 

1.4

5.0

40.3

.5

7 3

6

0

32. 1

21.5

5.0

1.9

2.5

2.0

--

0.5

.4

.7

--

O9 B

Q3 2

Q-l i

4.5

8.9 

10.3

15.3

55.6

56.1

58.4

Ac 7

97.3

11O Q

1 7^ f

125.7

1 7Q 

130.2

D member of Phosphoria formation

D- 7 

D- 6 

D- 5 

D- 4 

D- 3

D- 2 

D- 1 Mudstone, phosphatic, cherty mudstone,

3382-WHW 

3381-WHW 

3380-WHW 

3379-WHW 

3378-WHW

3377-WHW 

3376-WHW

1.7 

.9 

.7 

1.7 

1. 1

1.5 

1.8

18.5 

27.3 

26.7 

31.2 

10.4

1.8 

3.3

41.3 

23.0 

20.2 

10.5 

43.7

75.5 

80.5

1.7 

2.6 

3.3 

5.0 

6.1

7.6 

9.4

C member of Phosphoria formacion

C-10 

C- 9 

C- 8

Phprt ------_----_-__-__-_..___________-_ 3375-WHW 1.2 

8.! 

5.

0.4 92.0 1.2 

9.7 

14.7
Warm Springs Creek, Mont., lot 1300

Bed 

no.

C- 7 

C- 6 

C- 5 

C- 4 

C- 3

C- 2 

C- 1

Rock description

Qo nH Q^fkTI O « _

fhori ___

Sample 

no.

750-WHW

Thickness 

(feet)

10.0 

3.8 

3.4 

18.7 

3. 1

3.2 

1.3

Chemical analyses 

(percent)

P2°5

3.3

Acid 

insoluble

78. 3

Cumulativ

thicknes

(feet)

24.7 

28.3 

31.9 

50.6 

53.7

56.9 

58.2

B member of Phosphoria formation

B- 2 

B- 1

Sandstone, phosphatic and phosphate rock - 743 -WHW 

743-WHW

1.2 

1.2

19.4 

21.9

45.4 

39.3

0.9 

2. 1

A member of Phosphoria formation base not exposed

A- 3 

A- 2 

A- 1 __

2. 5 

9.8 

15.0

--

~ ~ 2.5 

12.3 

27. 3 

1

Fossil collection made by W. R. Record, Paleontology and Stratigraphy Branch, U. S. Geological Survey.
Lazyman Hill, Mont., lot 1319

Phosphoria formation sampled on Lazyman Hill, sec. 9, T. 10 S., R. 2 W., Madison County, Mont., on east limb 

Beds D-l through E-2 exposed in hand trench on east face of hill; E member measured from natural exposu

all other samples taken and rest of formation measured from natural exposures on northeast face of hill. 

and dip 13° W. Section measured by E. R. Cressman, B. K. Replogle, and W. J. Garmoe and sampled by R

September 1949. Samples analyzed by U. S. Bureau of Mines laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

Cumula

thickne

(feet)

E member of Phosphoria formation top not exposed

E-25 

E-24 

E-23 

E-22 

E-21

E-20 

E-19 

E-18 

E-17 

E-16

E-15 

E-14 

E-13 

E-12 

E-ll

E-10 

E- 9 

E- 8 

E- 7 

E- 6

E- 5 

E- 4 

E- 3 

E- 2 

E- 1

Dinwoody-Phosphoria contact covered, 

approximate thickness of covered interval- -

Mudstone, dolomitic -- ___|_______________

Mudstone, dolomitic -- ____ __ _______

Covered interval 

Sandstone, phosphatic and chert- -- - --

Sand stone, cherty -- - ____________ ____

C OVG r*6 d intG rv£-l ~

Sandstone - - - -- -- --- - -------

Sandstone - ---- --- ------ - _______

Sandstone - - - --- ----- __________

Chert, sandy -- - --- - - -- --

Phprt

Chert -

Chert 

Phprt

Chert 

Phprt

\_xli^J. t

V-slld. V

Chert 

742 -ERG 

741-ERC

10.0

1.0 

.5 

.6 

3.3 

3.8

7.4 

5.3 

1.4 

2.3 

2.9

4.1 

8.5 

4.3 

15.2 

8.1

9.0 

7.9 

8.2 

.6 

8.5

8.5 

3.7 

3.2 

3.5 

1.3

0.7 

.8

93.8 

90.4

10.

11.

11.

12.

15.

19.

26.

31.

33.

35.

38.

42.

51. 

55.

70.

78.

87.

95.

103.

104.

112.

121.

125. 

128.

131.

133.

D member of Phosphoria formation

D- 8 

D- 7 Mudstone - - --- ____ __

740-ERC 

739 -ERG

1.0 

1.3

0.5 

1.2

87.6 

86.3

1.0 

2.3
Lazyman Hill, Mont., lot 1319

Bed 

no.

D- 6 

D- 5 

D- 4 

D- 3 

D- 2

D- 1

Rock description

P Q T*V"n"inQ ttfa r*(*\r*\r

Mudstone, phosphatic, and argillaceous

Mudstone, phosphatic, phosphate rock, and

Sample 

no.

738-ERC 

737-ERC 

736-ERC 

735-ERC

734-ERC 

733-ERC

Thickness 

(feet)

0.9 

1.2 

.9 

.6

1.2 

1.4

Chemical analyses 

(percent)

P2°5

1.5 

28.0 

33.7 

10.4

6.2 

15.6

Acid 

insoluble

17.0 

19.2 

7.6 

49.4

63.4 

42.0

Cumulat

thickne

(feet)

3.2 

4.4 

5.3 

5.9

7. 1 

8.5

C member of Phosphoria formation

C l L.

P- 1 5

C- 1 4

C-13

P- 12

P- 1 1

P-10

P- Q

C

o

P- 7

C- 6

P- 5

P- 4

C - ^

C- 2

P- 1

Chert-- 

Chert 

f^i iaT*f''7'it^

Limestone, dolomitic, argillaceous and

CJanf^ctrtn^ r*a1r*a T*^/^n Q 

Sandstone, cherty and dolomite- ---------

Sandstone, cherty, sandstone, and sandy

Chert-------------- --

74Q-Wtn

"JAO^ftTfO

6.1

2.0

6.1

4.5

8

C

6.2

7. 7

? 7

2

0

2.0

1.2

2.3

3.9

3.6

3.5

4 ?

0.5

0.6

93.2

91.0

6.1

8 1

M

->

1 Q 7

77 7

33.4

41.1

43.8

46.6

48.6

AQ Q

52. 1

56.0

59.6

63.1

67.3

B member of Phosphoria formation

B- 2 

B- 1

747 -BKR 

746-BKR

1.2 

1.5

8.5 

27.9

61.8 

19.3

1.2 

2.7

A member of Phosphoria formation

A-26 

A-25 

A-24 

A-23 

A-22

f1 Q T*V"i/^nQ t^ t*f^r*\r sk T*CM 1 1 a r*^< in c

C* Q r*hr>na te* f*r»r*lr ___

(~* Q T*l^oria to t*t~\r*\£

(~* sk T*hon3 1^ T*or*lf «..«.._...._«. .. _ « _ _ ~ 

f~^ Q T*Vvrtna t^ T*/^r*lr _ 

745-BKR 0.7 

6.5 

8.2 

3.2 

8.6

1.7 20.3 0.7 

7.2 

15.4 

18.6 

27.2
A-21 

A-20 

A-19 

A-18 

A-17

A-16 

A-15 

A-14 

A-13 

A-12

A-ll 

A-10 

A- 9 

A- 8 

A- 7

A- 6 

A- 5 

A- 4 

A- 3 

A- 2

A- 1

Carbonate rock-- - - ------ -

Carbonate rock -- --- - -- - ------

Carbonate rock -- -- - --- --- ----

Sandstone, carbonatic - - -- ---- ----

Sandstone, carbonatic ------ ------ _---

Carbonate rock -- ---- --- -- 

QonH Qtnn^ pa T*hona ti f* .. ............

GO nf\ cttrtn^ r*o Y*}^rtfisi4"i r* .............

.-

4.6 

11.2 

1.5 

2.5 

3.7

4.7 

3.7 

2.6 

4.8 

7.0

2.5 

3.3 

12.0 

16.1 

1.0

2.3 

3.7 

4.5 

5.5 

4.3

7.9

--

31.

43.

44.

47.

50.

55.

59.

61.

66.

73.

76.

79.

91.

107.

108.

110.

114.

118.

124.

128.

136.

Quadrant formation top bed only

/~* r* 1 24.0 24.
Alpine Creek, Mont., lot 1307

B and D members of Phosphoria formation sampled and A, C, and most of E members described in southeast-facin

Alpine Creek, NI sec. 26, T. 10 S., R. 2 W., Madison County, Mont., on gently dipping east limb of Ruby V

C-10 through E-l measured and sampled in hand trench, all others from natural exposure. Beds strike N. 

Section measured by E, R. Cressman, W. H. Wilson, and R. L. Jones and sampled by W» J. Garmoe and J. L

Samples analyzed by U. S. Bureau of Mines laboratory, Albany, Qreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

Cumulat

thicknes

(feet)

E member of Phosphoria formation top not exposed

E-12 

E-H 

E-10 

E- 9 

E- 8

E- 7 

E- 6 

E- 5

TP 4

E- 3

E- 2 

E- 1

Dinwoody-Phosphoria contact covered, 

estimated thickness of covered interval --

Sandstone, dolomitic; fos. col. no. 11689 --

Sandstone, dolomitic; fos. col. no. 11687 --

Chert -- -

Chert 3394-WHW

10.

4.9 

4.2 

2.0 

3.0 

14.0

4.8 

8.0 

36.5 

11.5 

9.5

5.9 

2.4 0.9 90.6

10.0

14.9 

19.1 

21.1 

24. 1 

38. 1

42.9 

50.9 

87.4 

98.9 

108.4

114.3 

116.7

D member of Phosphoria formation

D- 4

D- 3 

D- 2 

D- 1

Phosphate rock, argillaceous and

Mudstone, phosphatic - - - ____ 

3393-WHW 

3392-WHW 

3391-WHW 

3390-WHW

1. 1

1.8 

1.0 

.5

30.5 

4.6 

2.6 

12. 1

13.7 

64.6 

29.4 

52.5

1. 1

2.9 

3.9 

4.4

C member of Phosphoria formation

c-io

C- 9 

C- 8 

C- 7 

C- 6

C- 5 

C- 4

Chert 3389-WHW 1.0 

4.3 

6.7 

. 3.0 

5.2

3.6 

6.8

5.6 79.9 1.0 

5.3 

12.0 

15.0 

20.2

23.8 

30.6
\ ' -J

C- 2

\ ' * 

Sandstone, dolomitic -- ---- - ------

1 ?

2.2

1. 7

o O Q

36.0

37.7

B member of Phosphoria formation

B_ -j

B- 2

B- 1

Sandstone, phosphatic and conglomerate; 

fos. col. no. 11686-- -- ----------

Phosphate rock, sandy, conglomeratic; 

fos. col. no. 11685 --- - ------ 

 J7QQ AI/TIW

 5 1 Q "7 \Ttf TTTir

3386-WHW

? 1

.9

1..1

1.4

8

-1

26.6

90.0

19. 1

2.3

3.2

4.3

A member of Phosphoria formation

A-16

A - 1 5

A- 14

A 

-11

A- 12

A-l 1

A-10

A- 9

A- 8

A_ 7

A- 6

A - 5

A- 4

A_ "i

A_ 7

A- 1

Dolomite 

DolomitG 

Dolomite -- - -- _-___- - - ___

Dolomite ---- ---- --- -- - 

T"^f*l onri 1 1& fM^^r* r*i Q

T^ol OTW 1 1 r* faf*t>r*f*i o *sonHv

__

__

2.9

? Q

3.3

3.8

0.8

2. 2

2.8

0.8

0.9

1.7

2.4

2.0

2.8

2.6

15.5

0.3

__

__

_ _

__

_ _

_ _

__

_ _

__

__

2.9

5.8

9.1

12.9

13.7

15.9

18.7

19.5

20.4

22.1

24.5

26.5

29.3

31.9

47.4

47.7

Quadrant formation top bed only

Cq-1 C A 5.4

1 Fossil collection made by W. R. Record, Paleontology and Stratigraphy Branch, U. S. Geological Survey.
Sliderock Mountain, Mont., lot 1301

Phosphoria formation measured and B and D members sampled on Sliderock Mountain, Ni sec. 25, T. 10 S., R. 4 W

Mont., on overturned west limb of Ruby Valley syncline. Thrust-faulting was recognized in lower formation

Phosphoria outcrop. Average strike is about N-S and dip about 40° W. A and C members measured from n

B and D members sampled from hand trenches on spur between heads of South and Middle Forks of Fawn Cr

measured from natural exposure in gully at head of Middle Fork of Fawn Creek. Section measured by C. W

Cressman and sampled by R. F. Gosman and W. J. Garmoe in August 1949. Samples analysed by U. S. Burea

Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

Cumulati

thicknes

(feet)

Dinwoody formation basal bed only

Id-1 22.0 22.0

E member of Phosphoria formation

E- 7 

E- 6 

E- 5 

E- 4 

E- 3

E- 2 

E- 1 Chert and mudstone --------------------

--

2. 7 

30.2 

2.9 

7.2 

3.5

4.8 

60.0

--

--

2.7 

32.9 

35.8 

43.0 

46.5

51.3 

111.3

D member of Phosphoria formation base not exposed

D-12 

D-ll 

D-10

D- 9 

D- 8

D- 7 

D- 6 

D- 5 

D- 4

D- 3

D- 2 

D- 1

Chert ---- - ----

Phosphate rock, argillaceous

Phosphate rock and argillaceous phosphate

Mudstone, phosphate rock, and phosphatic

Fault and shear zones, especially at the 

base of beds D-2, 5, 6, and 12 make thickness and stratigraphic sequence 

questionable.

692-CWT 

691-CWT

690 -CWT 

689-CWT 

688-CWT

687-CWT 

686- ERC 

685- ERC

684- ERC 

683- ERC

682- ERC 

681 -ERC

6.0 

3.8

.5 

.6 

.9

.6 

1.0 

2.4

.7 

2.4

1.5 

1.6

1.0 

7.3

12.0 

2.9 

22.6

4.8 

12.2 

23.4

21.6 

.8

10.2 

13.6

87.5 

51.7

22. 5 

53.3 

18.3

8.3 

37. 1 

14. 5

20.4 

12.7

42.0 

40. 7

6.0 

9.8

10.3 

10.9 

11.8

12.4 

13.4 

15.8

16.5 

18.9

20.4 

22.0
C member of Phosphoria formation top not exposed

C-19 

C-18 

C-17 

C-16

C-15 

C-14 

C-13 

C-12

c-ii 

c-io

C- 9 

C- 8 

C- 7 

C- 6

C- 5 

C- 4 

C- 3 

C- 2 

C- 1

D-C contact not exposed, covered interval 

of about five feet may include faults.

O Q TI H <a t rvn o _ « _ _ ^ _ _

pVkQ-pt -- ------_---_--_--_---------------

GQ y» H e 4- f\n O oVlOT*i"Xr _ « _« 

fhei-rt-- -- - - ___ _ ____________

/~'VlOY>t__ _ _ ____ __-.___________ _ __ _

--

5.0 

2.6 

12.5 

2.2 

5.0

6.0 

2.4 

5.8 

14.2 

8.7

5.5 

2.7 

2.4 

1.5 

1. 1

8.7 

3.0 

.3 

11.8 

1.6

"" "x

--

5.0 

7.6 

20.1 

22.3 

27.3

33.3 

35.7 

41.5 

55.7 

64.4

69.9 

72.6 

75.0 

76.5 

77.6

86.3 

89.3 

89.6 

101.4 

103.0

B member of Phosphoria formation base not exposed

B- 7

B- 6 

B- 5 

B- 4 

B- 3

B- 2 

B- 1

Phosphate rock, argillaceous and

699 -CWT 

698-CWT 

697-CWT 

696-CWT 

695-CWT

694-CWT 

693-CWT

0.7 

.8 

1. 1 

1.3

. 7

.5 

1.0

14.3 

5.7 

18.0 

26.7 

14.2

26.2 

34.6

53.0 

72.7 

45.5 

20.2 

60.0

26.0 

5.0

0.7 

1.5 

2.6 

3.9 

4.6

5.1 6.'l

A member of Phosphoria formation top not exposed

A-14

A-13 

A-12 

A-ll

Bed A-14 is highly fractured and brecciated.

--

35.0 

17.0

.8 

2.0 

1.7

35.0 

52.0

52.8 

54.8 

56.5
Sliderock Mountain Continued

Bed 

no.

A-10 

A- 9 

A- 8 

A- 7 

A- 6

A- 5 

A- 4 

A- 3 

A- 2 

A- 1

Rock description

Dolomite; fos. col. no. 11671 --------------

CQ v»H dti^nci f*a1f*£it% cionQ _ _ _ _____

Sample 

no.

__

Thickness 

(feet)

4. 7 

1. 0 

12.0 

4.4 

5.2

1.2 

1.2 

5.8 

6.7 

6.8

Chemical analyses 

(percent)

P 2°5

__

Acid 

insoluble

__

Cumulativ

thickness 

(feet)

56.5 

62.2 

74.2 

78.6 

83.8

85.0 

86.2 

92.0 

98.7 

105.5

Quadrant formation top bed only

Cq-1 -- -- -- -- -- 

CO

o
Taylor Creek, Idaho, lot 1342

B member of Phosphoria formation measured and sampled from natural exposure on the east side of Taylor Cree

Clark County, Idaho, by R. F. Gosman in September 1950. Beds strike N. 80* W. and dip 11* S. Sample

by U. S. Bureau of Mines laboratory, Albany, Oreg., and for other constituents by Trace Elements Sectio

Washington, D. C.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses (percent

P2°5 A1203 FeZ°3

Loss on 

ignition

in

B member of Phosphoria formation

B

-l

B

o

B

l

C C (- ) o T^f~*

C C /L o TDTj^/"'

'^SAd.-'R'GT'

3.5

.75

1.5

30. 2

17.0

31.3

0

£.Q

.62

.73

0.77

1.35

Q1

5.39

1.97

3.31

A member of Phosphoria formation top beds only

A_7

A-l

£\ *

Sandstone- - 

C C £. C O "Cif"1 1.6 4.5