GEOLOGICAL SURVEY CIRCULAR 326

STRATIGRAPHIC SECTIONS OF 

THE PHOSPHORIA FORMATION 

IN MONTANA, 1951

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 McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 326

STRATIGRAPHIC SECTIONS OF THE PHOSPHORIA FORMATION IN MONTANA

1951

By J. A. Peterson, R. F. Gosman, and R. W. Swanaon

Prepared as part of the program of 

the Department of the Interior far 

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.

Washington, D. C., 1964

Free on application to the Geological Survey, Washington 26, D. C.
STRATIGRAPHIC SECTIONS OF THE PHOSPHORIA FORMATION IN MONTANA

1951

By J. A. Peterson, R. F. Gosman, and R. W. Swanson

CONTENTS

Introduction .................

Acknowledgments ............

Stratigraphy of the Phosphoria 

formation in Montana ......

Stratigraphic sections........

References..................

Tables of stratigraphic 

sections

North Boulder Creek....

Three Forks ...........

Logan..................

Jefferson Canyon .......

Lot no. Page

1

1

1

4

4

1364

1356

1367

1355

5

7

9

10

Lot no. Page

Tables of stratigraphic 

sections Continued

Sappington Canyon .........

South Boulder Creek .......

La Marche Gulch...........

Canyon Creek no. 3 .......

North Big Hole Canyon......

South Big Hole Canyon .....

South Big Hole Canyon no. 2 

Indian Creek...............

Cinnabar Mountain ........

Landon Ridge .............

1357

1365

1366

1359

1358

1354

1354

1362

1363

1361

12

14

16

18

20

23

24

25

26

27

ILLUSTRATIONS

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

2. Generalized sections of 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 the sections .measured in southwestern Montana (fig. 1) during 1951, is the 

fifth Montana report of this series. The field 

and laboratory procedures adopted in these investigations are described fully in a previous report 

(McKelvey and others, 1953).

Many people have taken part in this investigation. The laboratory preparation of samples 

for chemical analysis was done in Denver, Colo., 

under the direction of W. P. Huleatt. The 

P2 0 5 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 2 03 , Fe^03 , and 

loss-on-ignition .analyses were made in the 

Trace Elements Section laboratory of the Survey 

in Washington, D. C., under the supervision

of J. C. Rabbitt, by chemists H. Alberty, T. Parley, 

C. Hoy, and M. Landers.

The data were compiled by K. S. Bergman, and 

Anita Wise organized most of the tabular data.

ACKNOWLEDGMENTS

Special thanks are due A. E. Weissenborn, who 

gave much advice and help in carrying out the field 

program. The cost of the field and laboratory investigations has been borne in part by the Department of 

the Interior program for development of the 

Missouri River basin and in part by 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.

STRATIGRAPHY OF THE PHOSPHORIA FORMATION 

IN MONTANA

In southwestern Montana the Phosphoria formation 

has been divided into five members: two phosphatic 

shale members, B and D, and three hard members, 

A," C, and E (fig. 2). The lower two hard members,
113 112°

Outcrop of Phosphoria formation, 

dotted where questionable

Location and lot number of sample 

locality included in this report

Location and lot number of sample 

locality included in other reports

1253, 1343 1254

fc£

SET*

&1

Recompiled and modified 

from Clabaugh, 1946

113° 112° 111'

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

2
30

PERCENT 

20 IO

T»«-

NESS 

IN FEET

AVERAGE 

Z 6 DESCRIPTION

FEET Dinwoody formation 

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

50

too

PHOSPHORIA FORMATION

Member E 

Sandstone: hard, pale, yellowish-orange, thick-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 inter beds of hard, light-gray chert

31

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

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

14

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

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

foot phosphatic

19 12

Member D 

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

15 Mudstone: soft, brownish-black to black, fissile

ISO

2OO

250

3OO

349

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

14 Phosphate rock and mudstonet oolitic, medium-hard, brownish-gray, phosphate 

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

12

Member C 

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

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

interbedded with hard, yellowish-gray, massive chert

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

nodules of chert

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

of chert

35 Chert: hard, medium-gray to yellowish-brown, thick-bedded; contains some 

interbeds of mudstone and sandstone

Member B

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

small lenses of oolitic phosphate rock

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

interhedded with soft, pale yellowish-brown mudstone

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

Member A 

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

10

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

interbedded cherty mudstone

Quadrant formation 

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

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

3
A and C, are dominated by limestone and the top, or 

E 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 A member is best developed toward the west 

and the southwest and consists of limestone or of dolomite, sandstone, mudstone, and chert. It has a maximum thickness of nearly 350 feet, overlies the Quadrant formation of Pennsylvanian age, and is probably 

equivalent to the upper member of the Wells formation 

of southeastern Idaho and adjacent Wyoming and Utah 

(McKelvey, 1949).

Near the southwest corner of the state the lower 

phosphatic shale [B member] is about 50 feet thick, 

but thins markedly to the north and east, where in 

some areas it cannot be recognized. In the 

Centennial Mountains it contains a rich bed of minable 

phosphate.

The C member consists of as much as to 200 feet 

of limestone, chert, and sandstone. The upper phosphatic shale [p member] is similar to and much more 

uniform and widespread than the B member, though 

minable phosphate is present only toward the north 

end of the area where the full thickness of the phosphatic 

zone may consist of a single 3- to 5-foot bed of highgrade phosphate rock.

The 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. In the greater part of the 

area it is overlain by the Dinwoody formation of 

Triassic age and toward the north and northeast by 

the Ellis group of Jurassic age.

STRATIGRAPHIC SECTIONS

Abstracts of stratigraphic sections measured 

at fourteen localities and analytical data are presented 

on the following pages. Their locations as well as the 

locations of other sections previously reported 

(Swanson and others, 1953a and b, Klepper and others, 

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

reported later are shown on figure 1.

REFERENCES

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, 

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

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

Ruppel, 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, part 1: 

U. S. Geol. Survey Circ. 208.

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

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

of the Phosphoria formation in Montana, 1947-48. 

U. S. Geol. Survey Circ. 209.

Swanson, R. W., Cressman, E. R., Jones, 

R. S., and Replogle, B. K., 1953b, 

Stratigraphic sections of the Phosphoria 

formation in Montana, 1949-50, part 2: 

U. S. Geol. Survey Circ. 303.
North Boulder Creek, Mont., lot 1364

Phosphoria formation measured and sampled in natural exposure on north side of road in NEi sec. 4, T. 2 

County, Mont. Beds strike N. 20* W. and dip 45* NE. Section measured by R. F. Gosman and sam

August 1951. Samples analyzed by U. S. Bureau of Mines laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical an

(percen

P2°5

Ellis group basal beds only

Je-2 

Je- 1 Conglomerate - -- --- - - __

15.0 

1.8

-- 

Phosphoria formation

P-30 

P-29 

P-28 

P-27 

P-26

P-25 

P-24 

P-23 

P-22 

P-21

P-20 

P-19 

P-18 

P-17 

P-16

P-15 

P-14 

P-13 

P-12 

P-ll

P-10 

P- 9 

P- 8 

P- 7 

P- 6

P- 5 

P- 4

Chert, sandy ----- 

Mudstone, cherty - - - --- 

Ph^rt ---- _ - _ -----_ ______-____,______-._

Mudstone, cherty -- ------- _-__ ____

Chert and cherty mudstone - ---- _______

Chert, phosphatic --- -- --- 

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

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

fhe»r*t ____________________________________

Quartzite -- --- --- --- - 

Chert and quartzite - - -

Chert, sandy - ______ -___-_ 

Carbonate rock, sandy --- -- -- ----- 

Mudstone - -- 

Sandstone, argillaceous, carbonatic --- ---

Mudstone, sandy - -- _____ -----

Mudstone and sandstone - ----- -_- _

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

Quartzite -- -- 

5533-RFG

5532-RFG 

5531-RFG

0.8 

7.2 

.9 

1.4 

2.8

.7 

1.2 

5.8 

.8 

.8

.4 

2.0 

.3 

19.0 

5.4

6.3 

5.6 

5.0 

20.0 

2,7

.6 

.4 

1.6 

4.3 

4.7

.7 

2.3

16.4

14. 1 

4.3
North Boulder Creek Continued

Bed 

no.

P- 3 

P- 2 

P- 1

Rock description

Mudstone, sandy and carbonatic sandstone --_ 

Quartzite and carbonatic sandstone -. ---

Mudstone, carbonatic ---- - -- _______

Sample 

no.

_ _

Thickness 

(feet)

3.2 

2.0 

6.3

Chemical ana

(percent)

P2°5

--

in

Quadrant formation top bed only

Cq-1 f^lfl Y*t^Pl to _. _ 2.5 
Three Forks, Mont., lot 1356

Phosphoria formation measured and sampled in natural exposure at north end of Milligan Canyon about 300 f

sec, 24, T. 2 N., R. 1 W., Jefferson County, Mont. Beds strike N. 80* E. and dip 25* N. Section m

and sampled by R. F. Gosman in June 1951. Samples analyzed by U. S. Bureau of Mines laboratory, 

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical ana

(percent)

P2°5

Ellis group basal bed only

T«»_1 Conglomerate; fos. col. no. 12698 - _--- -

Phosphoria formation

P-29 

P-28 

P-27 

P-26 

P-25

P-24 

P-23 

P-22 

P-21 

P-20

P-19 

P-18 

P-17 

P-16 

P-15

P-14 

P-13 

P-12 

P-ll 

P-10

P- 9 

P- 8 

P- 7 

P- 6 

P- 5

P- 4 

P- 3

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

r»U<aY-t

'Mudstone, phosphatic- - - 

fl-IOTt __________ ______ _ _

Chert, phosphatic, sandy - ________ ___

Phort --.-.«--»-_--.-»-.-»-.-»-__._._...-»_.-»_.__-_..,_. ........

f^ T*l£>Y*t Qfl/1 r*Q T~V^rtfl?i 4"O Y*f\f^1f __________ ,_. ____ -.

C* Vn_-r»t -.-.-. -. -. -. -.-.-.__-.-.-.-.-.-.-.__-.-. _

Chert, phosphatie - --_- - __- ---

CQ riH Q trtfi£* a nH r*a y*)~i^no to v*r\r*\e

5405-JAP

5404-JAP 

5403-JAP

5402-JAP 

5401 -JAP

5400-JAP

1.0 

6.2 

.2 

2.3 

.1

.9 

.3 

.3 

.7 

.3

7.0 

1.0 

1.5 

3.5 

.5'

.5 

2.5 

7.3 

1.6 

1.5

3.5 

26.3 

4.3 

21.3 

7.0

1.5 

2.3

18.8

20.2 

18.9

10.9 

23.7

16.3

1 Fossil collection made by J. A. Peterson.
Three Forks Continued

Bed 

no.

P- 2 

P- 1

Rock description

/"\I1 *> T*t T 1 to ________

Mudstone, carbonatic - - ---- _--- 

Sample 

no.

--

Thickness 

(feet)

0.9 

1.7

Chemical an

(percent

P2°5

--

i

Quadrant formation not measured

/I _. 1
Logan, Mont., lot 1367

Phosphoria formation measured and sampled along ridge on east side of road about 1 mile northwest of Logan, s

Gallatin County, Mont. Beds strike N. 70° E. and dip 20' N. Section measured by R. W. Swanson and J. 

sampled by Swanson in September 1951. Samples analyzed by U. S. Bureau of Mines laboratory, Albany

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyse

(percent)

P2°5

Aci

insolu

Ellis group not measured

To-1 C onglome r ate - -- _____ __________ 

Phosphoria formation top contact approximately located

P-23 

P-22 

P-21 

P-20 

P-19

P-18 

P-17 

P-16 

P-15 

P-14

P-13 

P-12 

P-ll 

P-10 

P- 9

P- 8 

P- 7 

P- 6 

P- 5 

P- 4

P- 3 

P- 2 

P- 1

Sandstone, quartzitic -___ _- ________ 

/""^IIQ T*tTlto _ < _

Quartzite - _-__ ______ ___ ____ 

Sandstone, quartzitic _________ ___________

Carbonate rock, chert, and sandstone _______

Chert and mudstone ____________ -__ __ 

Carbonate rock and chert __________ - _--

Mudstone and chert -- --------- - -

Chert and carbonatic mudstone -- -____-

Mudstone and chert -- ______ __ ----- 

_""^ll?5 T*tTlto _ _ ._ _u.j_i ._.

Quartzite, phosphatic _-____---_-_-_ __- _

Chert and quartzite -- - ----__----------

Mudstone, carbonatic - ____- ___ -___ 

/""* «i T*V^onQ tr* T*O/* Vr Q Y*fTi l"l£i/*Of^nQ .*_!___

Mudstone, carbonatic _-___.-------_--- ---

Quartzite, cherty; fos. col. no. 12699 - -___

Sandstone, carbonatic, quartzitic - - 

5593-RWS 

5592-RWS 

5591 -RWS

17.0 

4.6 

13.2 

6.0 

2.5

2.0 

2.0 

1.5 

1.9 

1.7

1.2 

5.8 

1.1 

1. 1 

1.6

.9 

1. 1 

.7 

1.0

U3

1.3 

1.5 

2.9

1.4 

.9 

1.3

< »*

72.

68.

62.

 »

1 Fossil collection made by J. A. Peterson.
Jefferson Canyon, Mont., lot 1355

Phosphoria formation measured and sampled in natural exposure and hand trench about 200 feet above river 

Canyon, SEi sec. 13, T. 1 N., R. 3 W., Madison County, Mont. Beds strike N. 45" E. and dip 45" N

J. A. Peterson and sampled by R. F. Gosman in June 1951. 

Oreg.

Samples analyzed by U. S. Bureau of M

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

___(percent)___

P2°5

Acid 

insoluble

C

t

Ellis group basal bed only

5.0 Je-1 Sandstone, conglomeratic- --- - 

	Phosphoria formation

P-31 Chert 

P-30 Quartzite and chert - -- -- - 

P-29 Chert and quartzite ---- - -- 

P-28 Chert and mudstone ------ --.

P-27 Chert 

P-26 Quartzite _________ __ __ ______

P-25 Chert 

P-24 Quartzite and phosphatic quartzite - 

P-23 Chert, sandy -- -- -- 

P-22 Quartzite ----- ---- ____.

P-21 Quartzite and chert - 

P-20 Sandstone, phosphatic ------- -- 5384-JAP

P-19 Chert 

P-18 Phosphate rock, cherty -- ----- --- 5383-JAP

P-17 Chert 

P-16 Chert, phosphatic' 5382-JAP

P-15 Chert - 

P-14 Chert, phosphatic - -- ------ 5381-JAP

P-13 Carbonate rock and chert - - - -- 

P-12 Chert and cherty carbonate rock -- ------

P-ll Mudstone, argillaceous - -- 5380-JAP

P-10 Chert, argillaceous - - - 5379-JAP

P- 9 Phosphate rock, argillaceous-- --- 5378-JAP

P- 8 Mudstone, cherty, carbonatic -- --- --- 5377-JAP

P- 7 Phosphate rock, argillaceous - - 5376-JAP

P- 6 Mudstone 5375-JAP

P- 5 Chert -- --- ----- .

P- 4 Quartzite; fos. col. no. 12693 5374-JAP

1.5 

10.5 

1.9 

1.2 

7.8

1.0 

2.0 

3.6 

.5 

2.8

7. 1 

.3

2.9 

.5

1.8

.5

.7

.6

1.7

10.4

.5 

3.6

.9 

3.5

.9

.4 

6.3 

1.3

18.6

18.2

15.5

17.5

8.9

2.0

22. 1

1.1

24.7

1.7 

7.3

48.4

45.0

53.6

46.8

64.3

75.0

31.9

64.0

32.4

72.1

77.9
P- ^

P- ?

P- 1

TV/TiiHdtrtno _ _

Sandstone, conglomeratic, phosphatic - ---

.5

.5

13.5

Quadrant formation top beds only

Cq-1 

Cq-2

--

__

-- 

1 Fossil collection made by J. A. Peterson.
Sappington Canyon, Mont., lot 1357

Phosphoria formation measured and sampled in natural exposure along ridge on east side of Jefferson River in 

Gallatin County, Mont. Beds strike N. 80* W. and dip 44" N. Section measured by J. A. Peterson and 

in July 1951. 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

Cum

thi

(

Ellis group basal beds only

Je-2 Carbonate rock, argillaceous, sandy _______ -- 4.2

Je-1 Mudstone, carbonatic ______________ __ -- 1.1

	Phosphoria formation

P-41 Quartzite ___ ________________________ -- 0.9

P-40 Sandstone, carbonatic, conglomeratic-- __ -- 3.0

P-39 Chert _ ________ ____ -- 6.5

P-38 Quartzite, carbonatic ___ __________ -- 1.3

P-37 Chert and sandstone _______ _____ __ '-- 6.9

P-36 Quartzite, carbonatic _________«__________ -- 1.6

P-35 Chert _-___-____________________ -- 2.4

P-34 Quartzite, carbonatic _____________________ -- 3.5

P-33 Sandstone, carbonatic; fos. col. no. 12697 __ -- 6.2

P-32 Sandstone, carbonatic --- - -- ____ -- 9.3

P-31 Chert ___________-___-_ -- 16.0

P-30 Carbonate rock, argillaceous ____ _______ -- 1.3

P-29 Carbonate rock, argillaceous and chert ____ -- 6.9

P-28 Chert ____________________________ -- 2.7

P-27 Phosphate rock, argillaceous ___ _________ 5483-JAP .2

P-26 Chert and mudstone _____ ______ _ ____ -- 3.0

P-25 Mudstone, phosphatic __ __ 5482-JAP .2

P-24 Mudstone and chert _ ______ ____ -- 8.0

P-23 Mudstone _-___________ 5481-JAP 1.8

P-22 Phosphate rock, argillaceous _____________ 5480-JAP .5

P-21 Carbonate rock __________________ 5479-JAP 1.2

P-20 Phosphate rock, argillaceous and mudstone _ 5478-JAP . 3

F-19 Phosphate rock, argillaceous _ _____ 5477-JAP .2

P-18 Mudstone, phosphatic - ______ ____ 5476-JAP .3

P-17 Phosphate rock, argillaceous _ _________ 5475-JAP 1.1

P-16 Mudstone, phosphatic, carbonatic _________ 5474-JAP .5

P-15 Mudstone - ____ 5473-JAP .4

P-14 Mudstone _ __ 5472-JAP .7

23.0

16.1

2.0 

25.3

1.2

17.4

29.1

8.3

26.8

11.4 

6.8 

4.6

34.9

47.3

73.6

30.8

6.0

30. 7

18.8

48.7

18.3

30.3

57.7

64.7
P-13

P-12

P-ll

P-10

P- 9

P

Q

P- 7

P

L

P- 5

P- A

P- 3

P- 2

P- 1

"P Vl /"\ C 1"* Vl £1 to T*rtf* \T S3 T* rfl 1 1 Q f* Oflll G

Mudstone - -- _____ ______ ____

Mudstone, phosphatic ____ ______ __

/"** *i T*VirtTi *a to Y*/"\O !* 

Chert 

/"** Vi of*t si n/^ on T*V*nnn to T*rtf* t

_*** *3 T*V* onss to T*r\r*1r ^ T nrlv

f*1 ViOY*t £1 nrl f* Q T*V^f^n otir* niioytf/ito

f*1 Q Y*V*rtma to T*rtf* lr Q TTTI llo r*ortii ts.

Carbonate rock, conglomeratic _____ __

Carbonate rock and chert -_ _ -_ --

5471 -JAP

5470-JAP

5469-JAP

.3

2.3

.5

.9

.7

3.0

9.5

1.3

6.5

6.9

.5

11.2

16,0

18.3

1.5

11.5

?Q Q

72.3

59.0

Quadrant formation top beds only

Cq-1

Cq-2

Cq-3

Qsan/^Qt^no on T*V*rtma tir* oVioytv

^^11 QT't'7'lto f*Q T*V^rtn 51 tl f*

Sandstone, carbonatic and chert ___________

6.0

14.0

5.0

1 Fossil collection made by J. A. Peterson.
South Boulder Creek, Mont., lot 1365

Phosphoria formation measured and sampled in hand trench and natural exposure about 200 feet above and 

sec. 10, T. 1 S., R. 3 W., Madison County, Mont. Beds strike east-west and dip 35* N. Sec^jn m

and sampled by R. F. Gosman in August 1951. Samples analyzed by U. S. Bureau of Mines labora

Bed 

no.

Rock description

Sample 

no.

Thicknes 

(feet)

Chemical analyses 

___(percent)___

P2°5

Acid 

insoluble

Ellis group basal beds only

Je-5 Carbonate rock _- _ --------- ______ -- (?)

Je-4 Covered interval -- ------ - - --- - - 15.0

Je-3 Sandstone, carbonatic --- - - _- -- 1.0

Je-2 Covered interval ------ - - -_- - -- 3.0

Je-1 Sandstone, calcareous --- --- --- -- -- 3.0

	Phosphoria formation

P-25 Covered interval; (sandstone float in

	pit) -- 7.0 

P-24 Chert - - -- 8.3 

P-23 Quartzite, carbonatic, phosphatic--- - - 1.0 

P-22 Chert 11.0 

P-21 Mudstone, phosphatic ---------------- 5569-JAP .4

P-20 Mudstone, carbonatic -- - ----- -_- -- 1.6

P-19 Chert, phosphatic 5568-JAP .4

P-18 Chert _._-._ _ .. - -- .7

P-l? Mudstone, phosphatic -- - 5567-JAP .5

P-16 Carbonate rock - --- ------ __-_--___ 3.0

P-15 Phosphate rock, argillaceous - 5566-JAP .5

P-14 Chert ~ 7.2

P-13 Mudstone, carbonatic --- 5540-JAP 5.5

P-12 Mudstone -, 5539-JAP 5.5

P-ll Phosphate rock, cherty --- 5538-JAP .6

P-10 Mudstone, carbonatic --- - 5537-JAP 1.7

	Below bed P-10 occurs a much-weathered 

	porphyry sill 3. 6 feet thick.

P- 9 Mudstone - --- 5536-JAP .6

P- 8 Phosphate rock, argillaceous --- -- - 5535-JAP .7

P- 7 Chert -- - -- 7.6

P- 6 phosphate rock ------------------------- 5534-JAP .3

14.4

16.6

18.3

18.6

1. 1

2.2

25.8

1.8

2.2 

26.2

30.5

59.9

52.5

47.3

45.5

68.06

74.3

30.26

71.06

70.0

29.5

11.9
P- 5

P- 4

P- 3

P- 2

P- 1

Conglomerate - -- - ------ --

Quartzite, carbonatic -- - - - - 

5.3

5.7

1.0

4.0

1.0

Quadrant formation top beds only

Cq-5

Cq-4

Cq-3

Cq-2

Cq-1

Carbonate rock and carbonatic sandstone -

Carbonate rock and carbonatic sandstone -

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

__

--

--

--

--

6.5

15.0

2.0

7.0

(?)

_ 

--

--

--

--

__

--

--

--

--
La Marche Gulch, Mont., lot 1366

Phosphoria formation measured and sampled in hand trench and natural exposure near La Marche Gulch on we

R. 9 W., Beaverhead County, Mont. Beds strike N. 40* W. and dip 45* SW. Section measured by R. F

in August 1951, Samples analyzed by U. S. Bureau of Mines laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses (perce

P205J A12°3! Fe2°3

Loss on 

ignition

E member of Phosphoria formation not measured

E- 1 Quartzite _ __ __ _ _ _ _ _ _ _ ___ __ -- -- -- -- -- 

D member of Phosphoria formation

D-16 

D-15 

D-14 

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

Phosphate rock - . - --

Carbonate rock - -- ---

^VirtQnVin t^ mr*]f fi T*cri 11 a f*^rtii Q

Phosphate rock and mudstone ______ __ 

Mudstone, carbonatic - -- -- 

Phosphate rock, argillaceous and

Phosphate rock, argillaceous and 

mudstone - - - --- --

Phosphate rock, argillaceous and 

mudstone -- - - -------------

Phosphate rock, argillaceous -- --- 

Phosphate rock, argillaceous and

Mudstone, phosphatic ----- - -- 

Mudstone, phosphatic and phosphate rock -- 

Mudstone, phosphatic and phosphate rock --

Mudstone, phosphatic and phosphate rock 

5585-RFG 

5584-RFG 

5583-RFG 

5582-RFG 

5581 -RFC

5580-RFG 

5579-RFG 

5578-RFG

5577-RFG 

5576-RFG

5575-RFG 

5574-RFG 

5573-RFG 

5572-RFG 

5571 -RFC

5570-RFG

0.5 

.4 

1.0 

.6 

U5

1.2 

2.1 

1.2

3.0 

2.7

4.0 

2.1 

1.1 

1.1 

3.3

1.0

28.4 

3.9 

4.3 

22.4 

27.0

.9 

24.0 

22.8

23.2 

18.7

22.7 

15.4 

.8 

15.8 

16.7

13.4

1.49 

4.24

2.93 

2.26 

13.6

5.20 

7.02

5.72

2.19 

2.60

1.38 

1. 12 

2.72

2.83 

3. 15

2.83

-_>

14.02 

4.18

5.27 

17.63 

5.44

6.40 

6.94

5.70

Lower part of Phosphoria formation

P-19 

P-18 

P-17 

P-16 

P-15

P-14 

P-13

Carbonate rock; fos. col. no. 12696

V_* ell LJU'lla.lC A UlM-JY

Carbonate rock and mudstone -_---_ 

Carbonate rock and mudstone - --

13.0 

.8 

4.1 

1.0 

9.3

11.0 

4.2

--

__
P-12 Carbonate rock- - - -

P-ll Carbonate rock, sandy and chert

P-10 Quartzite, carbonatic - -

P- 9 Chert and sandstone - -- -

P- 8 Carbonate rock, sandy, cherty --

P- 7 Quartzite, carbonatic -- -

P- 6 Carbonate rock, cherty -

P- 5 Carbonate rock, cherty --- -

P- 4 Sandstone, cherty - - - ---

P- 3 Carbonate rock, sandy --- __-.

P- 2 Sandstone - --- - ___.

P- 1 Carbonate rock -- - -

Cq-1 Quartzite, carbonatic -- __-_-._

Cq-2 Carbonate rock, argillaceous ---

Cq-3 Quartzite --___ _

Cq-4 Quartzite -- - - - -

7.5 

18.0 

3.0 

3.2 

3.0

6.5

18.0

14.6

2.0

5.5

.8 

7.2

Quadrant formation top beds only

4.0 

7.8 

5.0 

3.0

1 Fossil collection made by J. A. Peterson.
Canyon Creek no. 3, Mont., lot 1359

Phosphoria formation measured and sampled in hand trench and natural exposure about 1,500 feet northeast 

east limb of broad syncline in NWi sec. 13, T. 2 S., R. 10 W., Beaverhead County, Mont. Beds str

Section measured by J. A. Peterson and sampled by R. F. Gosman in July 1951. Samples analyzed 

laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

C

Dinwoody formation not measured

E member of Phosphoria formation

E- 7 

E- 6 

E- 5 

E- 4 

E- 3

E- 2 

E- 1

Quartzite, carbonatic - -

Chert 

Chert, sandy ---- -- i

8.0 

12.0 

12.0 

25.0 

5.0

12.0 

2.0

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

Mudstone, carbonatic -------- - -- --

Phosphate rock -- - 

Mudstone' -- - ------ - -

Phosphate rock, argillaceous----- - - 

Mudstone, phosphatic ----- -- 

Phosphate rock, argillaceous -- 

Mudstone --- - - _______ ___

Mudstone, phosphatic ------ ---

Mudstone, phosphatic --- - - - -

Sandstone, phosphatic --- - - - ---

5424-JAP 

5423-JAP 

5422-JAP 

5421 -JAP 

5420-JAP

5419-JAP 

5418-JAP 

5417-JAP 

541 6- JAP 

541 5- JAP

5414-JAP 

5413-JAP 

5412-JAP

0.9 

.9 

.4 

.9 

.3

.4 

2.2 

1.5 

3.0 

3.5

2.0 

1.2 

.7

31.5 

1.2 

.7 

29.0 

3.6

27.3 

20.6 

13.6 

23.7 

4.5

10.5 

13.6 

15.9

15.8 

16.1 

64.9 

4.9 

59.3

5.3 

22.9 

47.2 

24.5 

64.5

54.1 

38.3 

45.3

C member of Phosphoria formation

C- 5 

C- 4 

C- 3 

C- 2 

C- 1

Carbonate rock; fos. col. no. 12694 --- 

Quartzite, carbonatic -- --- - ------ 

Carbonate rock - ------ - - - _

4.5 

6.0 

12.7 

18.0 

5.0
B member of Phosphoria formation

B- 1 f* f\\Tf* T'rtfl 1 fl tOT'TT'^l -u.-u.-u.mm.-u.mm.mm-u. _u_ui_ JJ. _u

Covered interval forms gentle slope 

between resistant limestone units.

16.5 

A member of Phosphoria formation

A-10 

A- 9 

A- 8 

A- 7 

A- 6

A- 5 

A- 4 

A- 3 

A- 2 

A- 1

Carbonate rock and chert 

Carbonate rock - 

Carbonate rock - -- 

Covered interval - - 

Carbonate rock - - 

Covered interval - 

Carbonate rock, cherty 

Covered interval --- 

Quartzite, cherty - 

Carbonate rock - -

2.0 

7.4 

5.7 

7.0 

3.0

7.0 

7.0 

6.3 

1.5 

6.0

Quadrant formation not measured

Cq-l f^ll 3 T*t *7\ tfS _u _u _u

1 Fossil collection made by J. A. Peterson.
North Big Hole Canyon, Mont. , lot 1358

A, B, D, and E members of Phosphoria formation measured and sampled in hand trenches and natural expos

River in NEi sec. 3, T. 5 S., R. 8 W., Madison County, Mont., on northwest limb of asymmetrical an

A-9 measured in lower trench, bed nos. B-l through B-7 in middle trench, and bed nos. D-l through 

mainder of beds measured in natural exposure. Beds strike N. 70 0 E. and dip 20* N. Section measur

sampled by Peterson and R. F. Gosman in June and July 1951. Samples analyzed by U. S. Bureau of M

Or eg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

Cu

th

Dinwoody formation not measured

Contact between Phosphoria and Dinwoody 

formations in covered interval at bottom 

of dip slope on uppermost beds of 

Phosphoria formation.

E member of Phosphoria formation top not exposed

E- 8 

E- 7 

E- 6 

E- 5 

E- 4

E- 3 

E- 2 

E- 1

Chert 

/""\ lie fit" ty 1 + o

Phort

Chert 

ftna T*t^i to

/" WOT**

f*lllQ T*tT1 to

4.6 

9.0 

2.0 

8.2 

2.0

2.0 

21.6 

26.5

D member of Phosphoria formation

D-38 

D-37 

D-36 

D-35 

D-34

D-33 

D-32 

D-31 

D-30 

D-29

D-28 

D-27 

D-26

fVlOft

Mudstone -- ______ _ _ __ 

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

Mudstone, phosphatic - - - -- --

<Dhf\GnVta to 'Y*f\f*'\f /"*ss T*Virtnss ti _"* __. _ __ __.

Mudstone - - --- -- - --

Phosphate rock -- -- ---- ---

Phosphate rock --- - --- - --

Mudstone, carbonatic - - - - - -

Phosphate rock - - - -- ----

5461 -JAP 

5460-JAP 

5459-JAP 

5458-JAP 

5457-JAP

5456-JAP 

5455-JAP 

5454-JAP 

5453-JAP 

5452-JAP

5451 -JAP 

5450-JAP 

5449-JAP

0.6 

1.0 

1.0 

2.2 

.6

.5 

.8 

.6 

.7 

.6

1.3 

.5 

1.8

4.5 

2.4 

4.5 

13.3 

15.9

4.8 

4.7 

23.9 

16.4 

11.7

23.7 

7.7 

24.3

82.4 

71.3 

66.4 

45.4 

12.4

58.6 

60.7 

10.9 

31.3 

42.3

9.9 

49.7 

10.0
D-25 

D-24 

D-23 

D-22 

D-21

D-20 

D-19 

D-18 

D-17 

D-16

D-15 

D-14 

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

Carbonate rock, phosphatic -- - -- --

Phosphate rock, argillaceous -------- ----

JtT 11WO fJllCL lv" X \J\fR. f C*A c£XXXcLl_*C.s UUO *

Phosphate rock, argillaceous -

JL Il(J0|JIlcL 1C X LH_.lVj cLX glJJLcLwdJUd

*P Vl r\ cr* V» Q to T»f\f*lf aT*Cfi 1 1 ar*onil Q

Phosphate rock, argillaceous-- -- 

Mudstone, phosphatic - ________________

f* 9 T/*lr\ f\ n Q t o T* r\f* If

f* Q yVlfXnfl to T*rV* If

f* Q T*1~» f\YiQ to T*f\f*lr

^3V^r\CT%h Q to T*fV*lf Q T* Cfl 1 1 Q f*Of\11 C

C^ Q f*1~* f\ n fi t o T* f\f* If

Mudstone, phosphatic, carbonatic ----- --

Mudstone, carbonatic - - -- - --

Mudstone, phosphatic, carbonatic- ----

/""* Q T"V^f\MQ to T*f"lf* If

Phosphate rock, argillaceous, carbonatic --

C^ n t*lr\ f\n Q t o T* f\r* If

^3V| f\B T\h Q t O T* f\f* If Q T* rf 1 1 1 Q f* O f\\ 1 G

Mudstone, phosphatic - - - --

^3Vir\cTvVi Q to T*f\r*lf Q T*rri 1 1 Q r*of\n G

Mudstone, sandy ---- - ________ _

5448-JAP 

5447-JAP 

5446-JAP 

5445-JAP 

5444-JAP

5443-JAP 

5442-JAP 

5441 -JAP 

5440-JAP 

5439-JAP

5438-JAP 

5437-JAP 

5436-JAP 

5435-JAP 

5434-JAP

5433-JAP 

5432-JAP 

5431 -JAP 

5430-JAP 

54 29 -JAP

5428-JAP 

5427-JAP 

5426- JAP 

5425-JAP

.8 

.6 

.8 

1.7 

1.7

.4 

1.4 

1.4 

2.3 

.4 -

.7 

.4 

.5 

.6 

1. 1

1.1 

.7 

.4 

.7 

.5

1.4 

1.5 

1.5 

.5 

.5

12.0 

19.4 

21.9 

26.3 

17.0

6.3 

16.3 

20.6 

14.0 

2.3

2.5 

3.4 

17.6 

5.1 

9.8

3.5 

7.9 

11.5 

3.3 

14.7

2.2 

19.5 

13.8 

23.2

8.0 

21.3 

20.9 

15.0 

32.6

59.5 

31.7 

22.7 

38.5 

5.0

5.8 

7.7 

28.5 

9.9 

39.3

6.1 

48.9 

38.4 

6.1 

27.2

5.5 

27.5 

38.5 

36.0

C member of Phosphoria formation not described

B member of Phosphoria formation

B- 7 

B- 6 

B- 5 

B- 4 

B- 3

B- 2 

B- 1

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

Mudstone - _______________________

Mudstone, carbonatic --------------------

OQ r\f\ c t f\nr\ r*ss T*V^f\nQ ti r*

Carbonate rock, sandy, and sandy mudstone _

C* a T»Hr_n Q to T»nr*lr QanHv a nH Qanrlv _. _. _.-.-._.

5411 -JAP 

5410-JAP 

5409-JAP 

5408-JAP 

5407-JAP

1.2 

.8 

.6 

.9 

2.0

3.3

4.2

0.6 

.5 

34.0 

.8 

0.3

85.3 

86.3 

10.0 

68.3 

69.0

A member of Phosphoria formation

A- 9

Approximately 50 feet of upper A member

not measured. Complete A member

measured at South Big Hole Canyon no. 1,

lot no. 1354.

/""* Q >»V\ f\njj to T*f\f*lf 9 T* Cfl 1 1 Q f*O f\\1 C -. 5390-JAP 1.5 0.3 27.3 
North Big Hole Canyon Continued

Bed 

no.

A- 8 

A- 7 

A- 6

A- 5 

A- 4

A- 3 

A- 2 

A- 1

Rock description

Carbonate rock, argillaceous; fos. col. 

no. 12692- 

Limestone ------------------------- --

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

Limestone and chert -------- --- -----

Sample 

no.

5389-JAP 

5388-JAP

5387-JAP 

5386-JAP 

5385-JAP

Thickness 

(feet)

2.2

3 0 4

1.9 

1.5 

1.5

1. 1 

3.6 

12.9

Chemical analyses 

(percent)

P2°5

0.6 

6

.3 

. 1 

<. 1

Acid 

insoluble

37.0 

48.2

35.3 

50.2 

19.4

C

1

Quadrant formation top bed only

Cq-1

Fossil collection made by J. A. Peterson.

CO 

CO
South Big Hole Canyon, Mont., lot 1354

A, C, and D members of Phosphoria formation measured and sampled in natural exposure and hand trench 

of Big Hole River in SE^ sec. 3, T. 5 S., R. 8 W., Beaverhead County, Mont., on northwest limb of 

N. 60* E. and dip 20* NW. Section measured by J. A. Peterson and sampled by R. F. Gosman in Jun

U. So Bureau of Mines laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

C

D member of Phosphoria formation lower part only

D- 8 

D- 7 

D- 6 

D- 5 

D- 4

D- 3 

D- 2 

D- 1

Mudstone, phosphatic - - 

Phosphate rock, argillaceousPhosphate rock, argillaceousCarbonate rock --- -- Mudstone, phosphatic--------

Carbonate rock, argillaceous. 

Mudstone, phosphatic---- - 

Mudstone- ---- __________

5468-JAP 

5467-JAP 

5466-JAP 

5465-JAP 

5464-JAP

5463-JAP 

5462-JAP

3.0 

1.1

1.3

1.4 

1.8 

4.0

12.6

25.4

20.3

1.1

16.2

1.8 

17.3

49.1

2214

29.5

4.1

39.1

40.2

42.5

C member of Phosphoria formation

C - *»

P- 4

P- ^

C _ )

C _ 1

PaT*Honatfi T*nf»lr

Carbonate rock, cherty, sandy --- ---__

Carbonate rock, cherty------ -- -- 

/""* Q r»Hrinaf ^ T*r»f»lr 

Chert 

B member apparently lenses out at this

locality. Mudstones of B member at North

Big Hole Canyon, lot no. 1358, may be

represented by upper part of bed A- 5 here.

» _

 

3.3

12.5

20.3

70 O

6.6

 .

 _

_ _

_

A member of Phosphoria formation

A- 5

A- 4

A- 3

A_ 7

A- 1

C** nf*Tw4- Q n A f* o 1*1*1 /^tioi"o T*i"ir*lr

/""* Q T*V\OMQ t^ v*Of*lr Q nrl f*ho T*t

/""* Q y*V\ f\n fi t o if* f\f* lr

/"* Q T*Hr*nfif ^ T*r*f»lr

/"* Q T*V\ c\n a t o Tf*f\f* lr

19.0

39.4

14.0

6.7

10.0

->«»

-M

 «*

Quadrant formation not measured

Cq-1 f\ 11 Q T^^T 1 4*0
South Big Hole Canyon no. 2, Mont., lot 1354

B member of Phosphoria formation measured and sampled in hand trench along ridge about 1 mile south of Big Ho

Beaverhead County, Mont. Section measured by J. A. Peterson and sampled by R. F. Gosman in June 195

Mines laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses (percent)

P2°5 A12°3 Fe2 03

Loss on 

ignition

in

C member of Phosphoria formation basal bed only

C _i* Chert 6.0 

B member of Phosphoria formation

B-fio

1

B

e.

coB-5

H^ 

B-4.

B

.'a

B_7

B

_i

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

5406-JAP is sample of thin bed of phosphate rock contained in bed B-7 near the 

middle.

^2Vt r\cn It Q 4- o p/tf*!*'

Phosphate rock -- - -- - 

"PHitcnHa t<a T*OO!T

Phosphate rock - - - -

Phosphate rock, sandy --- 

Mudstone, carbonatic, sandy - -- 

Mudstone, sandy, carbonatic - - 

C1OO T A 'D

C1OQ T A 'D

5406-JAP

^^Q7- TAP

c?O&_ TAP

C?QC_ T A T>

5394- TAP

R3O7_ TAP

C7Q7_ TA p

2 7

1.4

(.2)

.3

.5

1.0

.5

1.2

5.2

1.7

6 7

30. 1

33.0

34.4

37.6

20.5

.4

.2

4.80

3.89

1.80

1.16

1.19

1.45

.68

1.99

.64

2 54

2.04

2.67

2.61

2.74

2.25

A member of Phosphoria formation top bed only

A-l ^* Q T*V»r\nsa to Y*Of*lf 9 nf\ ohoi'M" 17.3 __ 
Indian Creek, Mont., lot 1362

Phosphoria formation measured and sampled at natural exposure on north side of Indian Creek in sec. 20, T

County, Mont. Section measured by R. F. Gosman and sampled by J. A. Peterson in August 1951. 

Bureau of Mines laboratory, Albany, Oreg.

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

C

Dinwoody formation basal beds only

1-d-l 

l-d-2

C arbonate rock

QoriH cfr>nA r*a T*Hrinaf i f* _ _

? 

0.5

__ --

Phosphoria formation

P-16 

P-15 

P-14

P-13 

P-12

CO

01 P-ll 

P-10 

P- 9 

P- 8 

P- 7

P- 6 

P- 5 

p. 4

P- 3 

P- 2

P- 1

Q 11 3. I* 1 55 1 t^

Chert

Phosphate rock, argillaceous and 

TYiii dstone

Phosphate rock, argillaceous, and

nVirtci'nHati f* TYinrf^if nn^ _________ _ _

"P Vine* r\V\ ft tA T*fM"*lr _____ _

TWf 11 H c. t rin ^ f* n T*Vi f\r\ *^ 1 1 f* _ _ _

/"* f\ T*V\nTlQ f"^ T*flf*lr __-M._-M.I_ _M- _

Mudstone and argillaceous phosphate rock--

f"^ii3 T*t T 1 1^ 0^3 T*V\nn*^ ti f*

Mudstone, carbonatic and quartzite -- 

TVyfnHctrknfi QanHv r*aT*Hrinatir* ..____ __

ConH^tr^n*^ nnH QanHv r*aT*HrtnatA T*rtplr «._.___

5497-RFG 

5496-RFG

5495-RFG

5494-RFG 

5493 -RFG 

5492-RFG 

5491 -RFG 

5490-RFG

78.0 

39.0

.3

.4

2.0

1.1 

1.0 

.4 

.7 

.6

5. 7 

4.5 

6.5 

3.4 

8.7

.3

23.9 

1.7

23.9

31.9 

3.8 

1.6 

19.5 

15.0

32.3 

10.3

16.3

3.9 

63.3 

8. 1 

26.5 

47.5

Quadrant formation top beds only

Cq-1

Pn-7

0*3 r\A ctfin^ f^fi T*V\flTlQ ^"lf* i_ _M-_I__M- _«,

Qo nH ct nr\& r*zi T*V\rtno tlf* Q nH f*Vi^T*t _

17.0

10.5 ^ ^^
Cinnabar Mountain, Mont., lot 1363

Phosphoria formation measured and sampled in natural exposure on east side of Cinnabar Mountain, sec. 31

County, Montana. Beds strike N. 50° W. and dip 75* SW. Section measured by J. A. Peterson and 

in August 1951. 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

C

t

Dinwoody formation basal beds only

 frd-3 

-frd-2 

 frd-1

(~* Q T*Vlf"in!l tp* T*fV*t !1 T*Cfl 1 1 51 f*f*f*m^

Carbonate rock; fos. col. no. 12695 __ _ __

1.5 

2.0 

4.8

"* ""

_.

Phosphoria formation

P-17

P I A

P-15

P-14.

P-13

P-l 7

P-ll

P-10

P- 9

P- 8

P- 7

P- 6

P- 5

P- 4.

P- 3

P- 7

P- l

Quartzite, carbonatic - - - 

(~* V»^T*t an/1 f**\ T*V*r\n fitf* Y*rtf*t

Chert and mudstone - - -

f* Vl#iT*t' 51 T*tfl 11 SlOf'fMlQ

Mudstone, contains gypsum - _

'^^VifNOnn** 4- A T»r\f*\r Q T*Cfl 11 51 ^*^rtl 1I ^

C arbonate rock phosphatic --------------

^^Virtci^ViQ to Tf*r\f*]f Q T*cri 1 1 a oo/^n c

Mudstone, carbonatic, phosphatic - --

^VirhcrtViQ to irw»lr £) T*cri 11 a f»orm c

Conglomerate, phosphatic - --

5530-JAP

5529-JAP

5528-JAP

5527-JAP

5526-JAP

5519-JAP

5518-JAP

 5517-TAP

5516-JAP

c;4.qq_ TA "P

R4.QR- TA "P

6.5

11.8

7.2

2.5

8.0

7.0

1.3

2.0

.8

2.3

1.0

2.2

1.7

1.5

1.4

.7

1.0

__

_ _

2.1

3.4

4.9

19.9

8.3

21.6

21 3

23 4

12.6

16.8

174

__

 

 mm

 

72.7

71.9

64.5

35.8

9.3

23.03

23.7

17.5

32 5

36.3

49.6

Quadrant formation top beds only

Cq-1

Cq-2

Sandstone, carbonatic, argillaceous -

Ona Y*tf7i to _ __ _ _

3.0

50.0 -M M

Fossil collection made by J. A. Peterson.
Landon Ridge, Mont., lot 1361

B member of Phosphoria formation measured and sampled in bulldozer trench in SWi sec. 27, T. 12 S., R

Mont. Beds strike east-west and dip 25° S. Section measured by J. A. Peterson and sampled by P

in August 1951. Samples analyzed by U. S. Bureau of Mines laboratory, Albany, Oreg.

CO

-3

Bed 

no.

Rock description

Sample 

no.

Thickness 

(feet)

Chemical analyses 

(percent)

P2°5

Acid 

insoluble

C member of Phosphoria formation basal bed only

C-l Quartzite, phosphatic -- ---- - -- 3.0 -- -- 

B member of Phosphoria formation

B-6 

B-5 

B-4 

B-3 

B-2

B-l

Phosphate rock, sandy-- - --

Chert, phosphatic -- --- - ---

"PVl OGT^Vlfl t^T*Or*lfQQnf1v

Phosphate rock, argillaceous-- ---

P » j

5489-JAP 

5488-JAP 

5487-JAP 

5486-JAP 

5485-JAP

5484-JAP

0.2 

.4 

1.1 

1.4 

1.1

1.2

19.3 

18.7 

28.8 

27.6 

28.7

26.3

41.5 

46.4 

18.0 

20. 5 

18.3

20.6

A member of Phosphoria formation top bed only

A-l ^*VlOT*t rf"* O Y*Vl flfl^S t "1 rf"* -- 0.6 -- --