GEOLOGICAL SURVEY CIRCULAR 302 

STRATIGRAPHIC SECTIONS OF THE 

PHOSPHORIA FORMATION IN 

MONTANA, 1949-50 

PART 1 

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 T:HE INTERIOR 

Douglas McKay, Secretary 

GEOLOGICAL SURVEY 

W. E. Wrather, Director 

GEOLOGICAL SURVEY CIRCULAR 302 

STRATIGRAPHIC SECTIONS OF THE PHOSPHORIA FORMATION 

IN MONTANA, 1949-50, PART 1 

By E. R. Cressman, W. H. Wilson, C. W. Tandy, and W. J. Garmoe 

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 CommiBBion. 

The report is published with the 

permission of the Commission. 

Washington, D. C., 1953 

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

STRATIGRAPHIC SECTIONS OF THE PHOSPHORIA FORMATION 

IN MONTANA, 1949-~ PART 1 

By E. R. Cressman. W~ H. Wilson, C. W. Tandy, and W. J. Garmoe 

CONTENTS 

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

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

Stratigraphy of the Phosphoria 

formation in Mo~tana ............ . 

Stratigraphic sections .............. . 

Selected bibliography .............. . 

Tables of stratigraphic 

sections 

Lot no. Page 

l 

1 

4 

4 

4 

Hogback Mountain . . . . . . . . . . . . . 1299 5 

Lot no. Page 

Tables of stratigraphic 

sections-Continued 

West Fork of 

Blacktail Creek.............. 1302 

West Fork of Madison River .... 1318 

Little Water Canyon............ 1341 

Little Sheep Creek . . . . . . . . 1294-1295 

Crooked Creek . . . . . . . . . . . 1296-1297 

Camp Frigid .................. 1343 

10 

13 

14 

16 

20. 

23 

ILLUSTRATIONS 

Page 

Figure 1. Outcrops of the Phosphoria. formation in Montana and localities sampled . . . . . . . . . . . . . . . . . . . . . . . . 2 

2. Generalized section of the Phosphoria formation at Sheep Creek, Montana, lot no. 1234.-........ 3 

INTRODUCTION 

The U. S. Geological Survey has recently measured and sampled the PhOSliJhoria 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 third report on Montana; it includes about 

half the data gathered during 1949-50. 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 

by V. E. McKelvey and the field program was supervised by R. W. Swanson. T. M Cheney, J. L. Elliott, 

F. D. Frieske, R. F. Gosman, R. S. Jones, B. K. 

Replogle, and R. G. Waring 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. 

1 

The P 20 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. TheA1 20 3, Fe 203, andloss-on-ignition 

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, 

T. Farley, C. Hoy, and M. Landers. 

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

under the supervision of R. W. Swanson. Organization 

of the tabular data has been largely by Anita Wise. 

ACKNOWLEDGMENTS 

Special thanks are due A. E. Weissenborn and 

M. R. Klepper, whogavemuchadviceandhelpincarrying 

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 acknowledgethefine cooperation extended to the field parties by the local residents 

and property owners, who furnished information and 

services and gave access to property. 
:!(., .... /1340 ~ .... 

~ J~:i' .... ' > 

PHILIPSBURG .! 

·'i ·:! 

,. 125'aJ 

12481 } 

1249~; e.., 

1257• 

,..... .. 

\ • • 

? 

1341 .. ~ 1225-6 27 

1294-5 

--~1296-7 

1283 ••• --

_./· .. ~ .. """"""-·· 

~t/\ 

I 

: 

INDEX MAP 

EXPLANATION 

Outcrop of Phosphoria formation, 

dotted where questionable 

0 1341 

Location and lot number of sample 

locality included in this report 

0 1256 

Location and lot number of sample 

locality to be included in other reports 

1218~ ...... ' 

}>1215 

f1214' 

oz. .. .... 

'"'" ... 

~ "'"6 

~217 

:·· .. 

j 

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

2 
30 

T 

0 

50 

100 

150 

200 

250 

300 

349 

PERCENT "2 0s 

20 10 0 LITHOLOGY 

THICK- AVERAGE 

NESS p2 °s 1

N 

IN FEET PERCENT DESCRIPTION 

:=.c-~ Dinwoody formation 

;:..::-.i ,___c: ,..-J--._j_.-' Mudstone: calcareous, soft, pale-yellow, thin-bedded 

~ PHOSPHORIA FORMATION 

Member E 

2 2 Sandstone: hard, pale, yellowish-orange, thick-bedded 

Chert: hard, light-gray, thick-bedded chert interbedded with medium-hard, pale X r 24 2 yellowish-orange, thick-bedded chert 

J( J( 

Sandstone and chert: medium-hard, light-gray, thick-bedded sandstone containing I·· ........ ~ .. ._ :.-1 J( 

~~ 14 2 ..... _.._.._._.._ some interbeds of hard, light-gray chert 

1 .................. Sandstone and chert: medium-hard, brownish-gray, thick-bedded sandstone 31 2 interbedded with hard, light-gray, thick-bedded chert 1 ...... •••••• ...... l 

......... ······ 14 3 Sandstone: medium-hard, yellow ish-brown, thick-bedded sandstone interbedded 

I"· .:·:·:: .. :: .. ::.:.:· with hard, brownish-gray sandstone I~· ............... 

3 Chert: ~: ~ dusky, ~ 

-., tO 

11 2 ~: light-gray • I: ~ . 

r=-- -=1 Sandstone: hard, light-gray to yellowish-brown, thick-bedded; lowermost 0. 75 5 5 foot phosphatic .... .......... ) 

I.L S2-~~ ~ l Member D 

.:.:--~"'1 19 12 Mudstone: phosphatic, soft, brownish-black, thin-bedded 

-~~ 15 2 Mudstone: soft, brownish-black to black, fissile 

Pho rock: -· 

22 14 Phosphate rock and mudstone: oolitic, medium-hard, brownish-gray, phosphate 

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

::: ~:: ~ ~:·.~ :.:: j:': :·:·:· ~ Member C 

12 1 ................. 

~ 3 Sandstone: soft, dusky yellowish-orange, thick-bedded 

. ............... ··-.i Sandstone and chert: medium-hard, light brownish-gray, massive sandstone 41 1 , ...... ........... interbedded with hard, yellowish-gray, massive chert 

..... ..... .... / Dolomite: sandy, medium-hard, medium- to light-gray; contains lenses and 45 1 nodules of chert 

~ 5 6 Sandstone: soft, dusky yellow, thin-bedded; contains many lenses and nodules 

of chert 

35 1 Chert: hard, medium-gray to yellowish-brown, thick-bedded; contains some 

interbeds of mudstone and sandstone 

/ Member B 

2 2 Mudstone: medium-hard, medium yellowish-brown, thin-bedded; contains several 

small lenses of oolitic phosphate rock 

1 14 Phosphate rock and mudstone: soft, brownish-gray, oolitic phosphate rock 

interbedded with soft, pale yellowish-brown mudstone 

Mudstone: _,. _, .L L 

==-== ' 

:=- ----::: / Member A 

:-:...=- --3 7 0 Mudstone: dolomitic, soft, light-gray, thin-bedded 

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

10 0 interbedded cherty mudstone 

·······>D 

- 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, although member correlation toward the east and northeast is much more diffkult. 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 having a maximum thickness of nearly 350 feet. It overlies the Pennsylvanian ~uadrant 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 southwest corner 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 limestoneand/ or chert and sandstone. The 

upper phosphatic shale or D member is similar and 

much more uniform and widespread than the B member, 

although minable phosphate is present only toward 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-gra.de phosphate rock. 

The uppermost or E member is the most widespread and uniform, averaging about 100 feet in 

4 

thickness and consisting chiefly of siliceous rockssiltstone, 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 seven localities follow.. Their 

locations as well as the locations of other sections 

previously reported (Swanson and others, 1953, 

Klepper and 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. 

Klepper, M. R., Honkala, F. S., Payne, 0. 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. S., 

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. 
CJ1 

Hogback Mountain, Mont. , lot 1299 

Phosphoria formation sampled on Hogback Mountain, stNwt sec. 8, T. 11 S., R. 4 W., Madison County, Mont., on overturned west limb 

of Ruby Valley syncline. A, C, and E members measured from natural exposure, and Band D members measured and sampled 

Bed 

no. 

E-27 

E-26 

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 

in hand trenches on east scarp of mountain. Beds strike N. 40• E. and dip so• W. Section measured by W. H. Wilson, R. S. Jones, 

W. J. Garmoe, and B. K. Replogle and sampled by Replogle, J. L. Elliott~ and R. F. Gosman in August 1949. Samplee analyzed by 

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

Rock description 

Overlying beds covered. Top of E-27 

may be Dinwoody contact. 

Mudstone, carbonatic; fos. col. no. 11680 1 --

Sandstone, carbonatic, contains glauconite -

Sandstone, carbonatic, contains glauconite -

Mudst~ne, carbon:~tic and dolomite, , 

conta1ns glaucomte ---------------------

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

Sandstone and carbonatic quartzite, 

contains glauconite----------------------

Sandstone, carbonatic, contains glauconite -

Mudstone, cherty, carbonatic ------------- Sandstone, contains glauconite ------------ Chert-----------------------------------

Sandstone, carbonatic, contains glauconite -

Sandstone, contains glauconite ------------

Sandstone carbonatic -------------------- Sandstone: carbonatic; fos. col. no. 11679---

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

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

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

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

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

Chemical analyses 

Sample Thickness (percent) 

no. (feet) P2os I Acid insoluble 

E member of Phosphoria formation 

7.3 

• 8 

2.9 

1.5 

1. 6 

1. 5 

• 5 

1. 9 

• 5 

3.4 

5.9 

17.0 

3.3 

7.5 

1.3 

3.6 

3.6 

11.9 

10. 7 

13.3 

2. 1 

3. 8 

Cumulative 

thickness 

(feet) 

7.3 

8. 1 

11.0 

12.5 

14. 1 

15.6 

16. 1 

18.0 

18.5 

21.9 

27.8 

44.8 

48.1 

55.6 

56.9 

60.5 

64.1 

76.0 

86.7 

100.0 

102.1 

105.9 

1 Fossil collection made by,W. R. Record, Paleontology and Stratigraphy Branch, U.S. Geological Survey. 

Thickness x 

percent P 20f 

(cumulative 
Hogback Mountain-Continued 

Chemical analyses Cumulative Thickness x Bed Rock description Sample Thickness (percent) thickness percent P 20 no~ no. (feet) P205 

Acid (feet) (cumulativef insoluble 

E- 5 Sandstone, car~onatic -------------------- -- 2. 8 -- -- 108.7 -- E- 4 Sandstone, carbonatic -------------------- -- 4.4 -- -- 103. 1 -- E- 3 Sandstone ------------------------------- -- 4.8 -- -- 117.9 -- E- 2 Chert----------------------------------- -- .8 -- -- 118.7 -- E- 1 Sandstone; fos. col. no. 11678 ------------- -- 3.6 -- -- 122.3 -- '---

D member of Phosphor1a formation 

D-53 Phosphate rock, argillaceous ------------- 3553- RSJ 1.0 26.7 22.9 1.0 26.70 

D-52 Phosphate rock-------------------------- 3552- RSJ 1.0 31.2 14.7 2.0 57.90 

D-51 Phosphate rock and mudstone ------------- 3551-WJG 1.2 13.6 42.0 3.2 74.22 

D-50 Mudstone, phosphatic -------------------- 3550-WJG 4.7 13. 7 42.5 7.9 138.61 

D-49 Mudstone and carbonatic mudstone--------- 3549-WJG 3.8 6.95 41.9 11.7 165.02 

D-48 Mudstone, phosphatic -------------------- 3548-WJG . 7 8.9 52.3 12.4 171. 25 

D-47 Mudstone-------------------------------- 3547-WJG . 9 5. 7 63.9 13.3 176.38 

D-46 Mudstone, phosphatic -------------------- 3546-WJG • 9 16.8 43.3 14.2 191. 50 

D-45 Mudstone and phosphatic mudstone--------- 3545-WJG • 8 8.3 54.7 15.0 198.14 

D-44 Mudstone-------------------------------- 3544-WJG 1.6 3.7 62.4 16.6 204.06 a;, 

D-43 Mudstone, phosphatic -------------·------ 3543-WJG 1.4 11.3 49.8 18.0 219.88 

D-42 Mudstone, phosphatic -------------------- 3542-WJG 1.3 8.8 63. 1 19.3 231.32 

D-41 Mudstone, phosphatic -------------------- 3541-WJG 2.4 '- 11.6 57.6 21.7 259.16 

D-40 Mudstone, phosphatic -------------------- 3540-WJG . 8 14.2 53.0 22.5 270.52 

D-39 Mudstone,_ carbonatic -------------------- 3539-WJG 1.5 1.8 55.5 24.0 273.22 

D-381 Mudstone, phosphatic -------------------- 3538-WJG 1.6 12.7 57.3 25.6 293.54 

D-37 Mudstone, phosphatic, carbonatic ··-------- 3537-WJG 1.1 8. 1 66.7 26.7 303.45 

D-36 Chert, carbonatic, and carbonatic 

mudstone ------------------------------ 3536-WJG 1.7 4.3 55.3 28.4 309.76 

D-35 !Chert----------------------------------- 3535-WJG 2.0 2.7 87.2 30.4 315.16 

D-34 Mudstone-------------------------------- 3534-WJG 1.1 6. 1 71. 7 31.5 321. 81 

D-33 Chert----------------------------------- 3533-WJG • 8 1.7 88.1 32..3 323.23 

D-32 Chert----------------------------------- 3532-WJG 2.6 1.1 92.8 34.9 32.6.09 

D-31 Mudstone-------------------------------- 3531-WJG 2.3 1.7 88.9 37.2 330.00 

D-30 Mudstone-------------------------------- 3530-WJG 2.3 2.8 85.7 39.5 336.44 

D-29 Mudstone-------------------------------- 352.9-WJG 2.6 3.4 81.4 42.1 345.28 

D-28 Mudstone, phosphatic -------------------- 3528-WJG 1.0 11. 2 54. 1 43.1 356.48 

D-27 Mudstone, carbonatic -------------------- 3527-WJG 1.7 5.7 35.4 44.8 366.17 

D-26 Mudstone, phosphatic -------------------- 3526-WJG 3.0 15.6 43.7 47.8 412.97 

D-25 Mudstone, phosphatic -------------------- 3525-WJG . 8 12..0 44.4 48.6 422.57 

D-24 Mudstone, phosphatic -------------------- 3524-WJG 1.3 12.3 37.5 49.9 438.56 
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-11 

D-10 

D- 9 

D- 8 

D- 7 

D- 6 

D- 5 

D- 4 

D- 3 

D- 2 

D- 1 

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

Mudstone and argillaceous phosphate rock---

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

Mudstone -------------------------------- Mudstone and argillaceous phosphate rock---

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

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

Mudstone, phosphatic, carbonatic ---------- Phosphate rock---------------------------

Phosphate rock, argilla~eous --------------

Mudstone, phosphatic--------------------...; 

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

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

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

Mudstone, phosphatic, and mudstone ------- Phosphate rock, argillaceous--------------

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

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

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

Mudstone and phosphate rock --------------

Mudstone --------~-----------------------

3523-WJG 

3522-WJG 

3521-WJG 

3520-WJG 

3519-WJG 

3518-WJG 

3517-WJG 

3516-WJG 

3515-WJG 

3514-WJG 

3513-WJG 

3512-WJG 

3511-WJG 

3510-WJG 

3509-WJG 

3508-WJG 

3507-WJG 

3506-WJG 

3505-WJG 

3504-WJG 

3503-WJG 

3502-WJG 

3501-WJG 

1.2 

1.2 

2.5 

. 8 

2.5 

.9 

3.0 

2.0 

1.0 

1.7 

1.9 

2.0 

• 8 

• 7 

1.7 

• 8 

1.6 

• 8 

. 5 

1.5 

1.2 

.4 

• 7 

11.0 

11.9 

6.3 

2.3 

13.1 

34.5 

8. 1 

10.7 

29.3 

17.3 

13.9 

5. 3 

5.7 

9.7 

16.6 

32.1 

10. 1 

29.7 

12.3 

6.0 

9.8 

22.8 

3. 1 

47.1 

43.4 

51.3 

71. 0 

48.7 

4.5 

55. 7 

37.3 

100 7 

32~7 

33.3 

59.0 

37.5 

43.3 

30.7 

5. 2 

• 57. 5 

18.5 

32.7 

64.5 

46.2 

23.6 

80.5 

51. 1 

52.3 

54.8 

55.6 

58.1 

59.0 

62.0 

64.0 

65.0 

66.7 

68.6 

70.6 

71.4 

72.1 

73.8 

74.6 

76.2 

77.0 

77.5 

79.0 

80.2 

80.6 

81.3 

451.76 

466.04 

481.79 

483.63 

516.38 

547.43 

571.73 

593.13 

622.43 

651. 84 

678.25 

688.85 

693.41 

700.20 

728.42 

754.10 

770.58 

793.34 

800.49 

809.49 

821. 25 

830.37 

832.54 -J --------~---------------------------------------------------------------------L-------------------~------------~--------------L-----------L _______________________ ._ _________________ ___ 

C-11 

C-10 

c- 9 

c- 8 

c- 1 

c- 6 

c- 5 

c- 4 

c- 3 

c- 2 

c- 1 

B- 4 

B- 3 

B- 2 

C member of Phosphoria formation 

Chert and sandstone ---------------------- Sandstone and quartzite -------------------

Limestone ------------------------------- Siltstone, calcareous --------------------- Limestone, silty, dolomitic ---------------

Limestone ------------------------------- Limestone; fos. col. no. 11677 ------------- Sandstone and carbonate rock--------------

Chert and carbonate rock -----------------

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

Chert, carbonatic ------------------------ 3374-WHW 

2.8 

18.2 

10. 1 

8.5 

24.0 

22.5 

46.0 

20.0 

23.5 

3Q.2 

i.8 0.4 

B member of Phosphoria formation 

Sandstone phosphatic' and mudstone ---------

Mudstone, phos'phatic --------------------- Phosphate rock---------------------------

3373-WHW 

3372-WHW 

3371-WHW 

3.0 

2. 1 

4.0 

6.0 

8.8 

28.8 

64.0 

67. 7 

66.5 

16.0 

2.8 

21.0 

31. 1 

39.6 

63.6 

86.1 

132.1 

152.1 

175.6 

205.8 

208.6 

3.0 

5. 1 

9. 1 

18.00 

36.48 

151.68 
Hogback Mountain-Continued 

Chemical analyses 

Bed Rock description Sample Thickness (percent} 

no. no. (feet) P 20 5 

Acid 

insoluble 

B- 1 Sandstone and phosphate rock; fos. col. 

no. 11676------------------------------- 3370-WHW 1.8 19.3 43.2 

-- Phosphate rock, argillaceous-------------- 3370b-WHW (. 7) 23.4 34. 1 

-- Sandstone-------------------------------- 3370a-WHW (1. 1) 0.8 91.8 

3370-WHW resamp1ed as two units. 

A member of Phosphoria formation 

A-45 Carbonate rock--------------------------- 3369-WHW 3.5 0.5 11.5 

A-44 Carbonate rock, argillaceous, silty--------- 3368-WHW 3.4 . 9 28.0 

A-43 Mudstone -------------------------------- 3367-WHW 7. 5 . 2 70.3 

A-42 Mudstone -------------------------------- 3366-WHW 6.2 . 2 68.2 

A-41 Sandstone and mudstone------------------- 3365-WHW 6.0 . 1 71. 8 

A-40 Mudstone -------------------------------- 3364-WHW 5.4 . 2 71.2 

A-39 Mudstone, carbonatic --------------------- 3363-WHW 5.5 . 2 67.8 

A-38 Mudstone, carbonatic --------------------- 3362-WHW 6.0 0 2 63.7 

A-37 Mudstone, carbonatic --------------------- 3361-WHW 4.8 . 1 64.6 

A-26 Mudstone -----------------.. -------------- 3360-WHW 4.9 . 1 70.5 (X) 

A-35 Mudstone -------------------------------- 3359-WHW 11.2 . 1 71.0 

A-34 Sandstone-------------------------------- -- 10.8 -- -- A-33 Carbonate rock--------------------------- -- 33.4 -- -- A-32 Carbonate rock--------------------------- -- 26.4 -- -- A-31 Carbonate rock;· fos. col. no. 11675 --------- -- 30.2 -- --

A-30 Sandstone, carbonatic--------------------- -- 7.3 -- -- A-29 Carbonate rock--------------------------- -- 15.0 -- -- A-28 Carbonate rock; fos. col. no. 11674 --------- -- 10.8 -- -- A-27 Carbonate rock, argillaceous-------------- -- 2.6 -- -- A-26 Carbonate rock--------------------------- -- 15.0 -- --

A-25 Carbonate rock--------------------------- -- 7.8 -- -- A-24 Carbonate rock--------------------------- -- 6.0 -- -- A-23 Sandstone-------------------------------- -- 6.5 -- -- A-22 Carbonate rock--------------------------- -- 12.8 -- -- A-21 Carbonate rock--------------------------- -- 13.0 -- -- A-20 Carbonate rock~-------------------------- -- 15.0 -- -- A-19 Carbonate rock and sandstone-------------- -- 4.9 -- -- A-18 Sandstone-------------------------------- -- 9.4 -- -- A-17 Carbonate rock--------------------------- -- 9.0 -- -- A-16 Carbonate rock--------------------------- -- 15.0 -- --

Cumulative 

thickness 

(feet) 

10.9 

--

--

3.5 

6.9 

14.4 

20.6 

26.6 

32.0 

37.5 

43.5 

48.3 

53.2 

64.4 

75.2 

108.6 

135.0 

165.2 

172.5 

187.5 

198.3 

200.9 

215.9 

223.7 

229.7 

236.2 

249.0 

262.0 

277.0 

281.9 

291.3 

300.3 

315.3 

Thickness x 

percent P 20 

(cumulativef 

186.42 

--

--

1. 75 

4.81 

6.31 

7.55 

8.15 

9.23 

10.33 

11. 53 

12.01 

12.50 

13.62 
(() 

A-15 

A-14 

A-13 

A-12 

A-11 

A-10 

A- 9 

A- 8 

A- 7 

A- 6 

A- 5 

A- 4 

A- 3 

A- 2 

A- 1 

Carbonate rock; fos. col. no. 11673 -------- Carbonate rock--------------------------

Mudstone, carbonatic, and carbonatic 

sandstone------------------------------

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

Sandstone and carbonate rock -------------

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

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

Carbonate rock, sandstone, and 

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

Carbonate rock and sandstone-------------

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

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

Sandstone and carbonate rock ------------- Carbonate rock--------------------------

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

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

10.5 

8. 5 

6. 1 

8.8 

10.2 

4.0 

2.6 

1. 0 

2.6 

• 3 

3.0 

6.8 

1.0 

2.7 

. 3 

Quadrant formation-top bed only 

325.3 

334.3 

340.4 

349.2 

359.4 

363.4 

366.0 

367.0 

369.6 

369.9 

372.9 

379.7 

380.7 

383.4 

383.7 

Cq-1 ~~~~=-=-=~-===----==~~=~=-==-=---- [m • -- -~ j ___ ~·~ __ ]_--==u I -- I 4.6j 
West Fork of Blacktail Creek, Mont., lot 1302 

Phosphoria formation measured and Band D members sampled near West Fork of Blacktail Creek, SE! sec. 26, T. 12 S., R. 6 W., 

Beaverhead County, Mont., on southeast limb of an anticline. Beds A-1 through C-3 measured in bulldozer trench near top of 

hill on northeast side of creek; beds C-15 through E-1 measured in hand trench 500 yards farther south and about 250 feet up the 

slope from Blacktail road; rest of section measured from natural exposures near road. Beds strike N. 73° E. and dip 37° S. 

Section measured by E. R. Cressman, C. W. Tandy,. and W. H. Wilson, and sampled by J. L. Elliott, B. K. Replogle, W. J. 

Garmoe, and R. F. Gosman in July 1949. Samples analyzed by U. S. Bureau of Mines laboratory, Albany, Oreg. 

Bed 

Chemical analyses 

Sample (percent) no. Rock description Thickness 

no. (feet) P20s 

Dinwoody formation-lower beds only 

'n'd-1 

'n'd-2 

'n'd-3 

'n'd-4 

'n'd-5 

Mudstone, calcareous--------------------

Covered -------------------------------- Limestone, argillaceous------------------

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

Covered --------------------------------

1.2 

8.0 

1.2 

• 3 

7. 2 

E member of Phosphoria formation 

E-10 

f-' E- 9 0 E- 8 

E- 7 

E- 6 

E- 5 

E- 4 

E- 3 

E- 2 

E- 1 

Limestone, sandy----------------------1-- Dolomite, argillaceous; fos. col. no. 11670 -- Dolomite, cherty, argillaceous-------------

Chert, dolomitic, argillaceous, and cherty 

dolomite-------------------------------

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

Sandstone, cherty------------------------

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

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

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

Sandstone, cherty------------------------

2.7 

3.4 

12.2 

4.6 

3.8 

2.0 

5. 1 

18.0 

11.9 

48.0 

D member of Phosphoria formation 

D-34 Phosphate rock, argillaceous ------------- 668- ERC 0.7 26.4 

D-33 Phosphate rock, argillaceous ------------- 667- ERC 1.0 27.5 

D-32 Phosphate rock, argillaceous; fos. col. 

no. 11669 ------------------------------ 666- ERC 2.7 16.3 

D-31 I Mudstone, phosphatic -------------------- 665- ERC 3.8 8. 1 

D-30 Mudstone, carbonatic -------------------- 664- ERC 2.4 5.6 

D-29 Mudstone, phosphatic ------------.-------- 663-,ERC 3.3 8.3 

D-28 Mudstone, phosphatic -------------------- 662- ERC 3.3 10.6 

D-27 Mudstone, carbonatic -------------------- 661- CWT 2.7 3.4 

D-26 Mudstone, phosphat\c, carbonatic; 

fos. col. no. 11668 ---------------------- 660-CWT I . 8 I 8. 1 

D-25 I Mudstone ------------------------------- 659-CWT 1.5 4.6 

I Acid 

insoluble 

I 25.8 

20.2 

37.8 

52.2 

40.8 

53. 7 

49.3 

46.7 

I 47.2 

63.4 

Cumulative Thickness x 

thickness percent P 20 

(feet) (cumulativef 

1.2 

9.2 

10.4 

10.7 

17.9 

-

-

2.7 

6. 1 

18.3 

22.9 

26.7 

28.7 

33.8 

51.8 

63.7 

111.7 

0.7 18.48 

1.7 45.98 

4.4 89.99 

8.2 120.77 

10.6 134. 2l 

13.9 161.60 

17.2 196.58 

19.9 205.76 

20.7 212.24 

22.2 219.14 
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-11 

D-10 

D- 9 

D- 8 

D- 7 

D- 6 

D- 5 

D- 4 

D- 3 

D- 2 ....., D- 1 1-' 

C-15 

C-14 

C-13 

C-12 

C-11 

C-10 

c- 9 

c- 8 

c- 1 

c- 6 

c- 5 

c- 4 

c- 3 

c- 2 

Phosphate rock, argillaceous-------------- 658- CWT 2. 5 16. 1 

Mudstone, phosphatic------:--------------- 657-CWT 2.9 12.0 

Mudstone, phosphatic, carbonatic ---------- 656- CWT . 8 11.4 

Mudstone, phosphatic--------------------- 655- CWT 2.0 8. 1 

Mudstone, carbonatic --------------------- 654-CWT 3.0 7. 3 

Mudstone, phosphatic--------------------- 653- CWT 2.4 10.2 

Carbonate rock--------------------------- 669- ERC . 8 1.7 

Phosphate rock, argillaceous-------------- 652- ERC 1.1 26.7 

Mudstone, carbonatic --------------------- 651- ERC 2.8 4.6 

Mudstone -------------------------------- 650- ERC 3.0 2. 5 

Mudstone -------------------------------- 649- ERC 1. 7 4.6 

Phosphate rock and phosphatic mudstone ---- 648- ERC . 9 21.6 

Phosphate rock; fos. col. no. 11667 --------- 647- ERC 1.3 30.6 

Mudstone, phosphatic, carbonatic ---------- 677-CWT 2.7 8.4 

Mudstone, phosphatic and phosphate rock---- 676-CWT 1.1 18.6 

Carbonate rock, argillaceous-------------- 675-CWT 1.5 3. 1 

Mudstone, phosphatic, carbonatic ---------- 674-CWT . 8 10.3 

Carbonate rock, argillaceous -------------- 673-CWT 1.0 1.2 

Mudstone, phosphatic, carbonatic ---------- 672-CWT . 8 13.8 

Carbonate rock--------------------------- 671-CWT 1.0 1.2 

Mudstone, phosphatic; fos. col. no. 11666---- 670-CWT 1.5 14.7 

Phosphate rock, argillaceous -------------- 680- ERC . 7 26.7 

Covered interval-------------------------- -- 1.0 -- Mudstone and argillaceous phosphate 

rock; fos. col. no. 11665------------------ 679- ERC 1.6 I 12.9 

C member of Phosphoria formation 

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

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

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

Covered interval--------------------------

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

Dolomfte-----------------------·----------

Chert, dolomitic,· and argillaceous 

dolomite--------------------------------

Dolomite--------------------------------- Dolomite, cherty, argillaceous-------------

Covered interval--------------------------

Dolomite, silty, and dolomitic chert--------

Covered interval-------------------------- Cher~-----------------------------------

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

Bed C-2 is cut by several faults, true 

thickness not known. 

678- ERC 

--

--

--

--

--

--

--

--

--

--

--

--

--

2.9 0.5 

3.0 -- 14.0 -- 47.0 -- 8. 1 -- 2.6 --

13. 5 -- 1.2 -- 4.2 -- 4.5 --

3.5 -- 9.5 -- 15.3 -- 7.9 --

34.6 24.7 

39.0 27.6 

37.8 28.4 

52.2 30.4 

44.8 33.4 

46.6 35.8 

9.8 36.6 

14.2 37.7 

52.7 40.5 

63.2 43.5 

58.0 45.2 

26.2 46.1 

11. 3 47.4 

44.8 50. 1 

27.9 5l. 2 

28. 1 52.7 

35. 1 53.5 

21. 2 54.5 

34.2 55.3 

17.2 56.3 

36.0 57.8 

20.5 58.5 

-- 59.5 

I 50.5 I 61. 1 

94.3 2. 9 

-- 5.9 

-- 19.9 

-- 66.9 

-- 75.0 

-- 77.6 

-- 91. 1 

-- 92.3 

-- 96.5 

-- 101.0 

-- 104.5 

-- 114.0 

-- 129.3 

-- 137.2 

1 Fossil collection made by W. R. Record, Paleontology and Stratigraphy Branch, U. S. Geological Survey. 

259.39 

294.19 

303. 31 . 

319.51 

341.41 

365.89 

367.25 

396.62 

409.50 

417.00 

424.82 

444.26 

484.04 

506.72 

527.18 

531.83 

540.07 

541. 27 

552.31 

553~51 

575.56 

594.25 
Bed 

no. 

c- 1 

B-10 

B- 9 

B- 8 

B- 7 

B- 6 

B- 5 

B- 4 

B- 3 

B- 2 

B- 1 

A- 9 ......., A- 8 t>:> A- 7 

A- 6 

A- 5 

A- 4 

A- 3 

A- 2 

A- 1 

West Fork of Blacktail Creek-Continued 

Sample 

Chemical analyses 

Rock description Thickness (percent) 

no. (feet) Acid 

P205 insoluble 

Chert ----------------------------------- -- 17. 3 -- --

B member of Phosphoria formation 

Chert, silty------------------------------ 646- ERC 0.5 0.3 94.0 

Mudstone and chert----------------------- 645-WHW 1.1 . 2 95.2 

Mudstone-------------------------------- 644-WHW 1.8 . 6 87.0 

Mudstone and phosphatic mudstone --------- 643-WHW 1.5 6.5 69.5 

Mudstone -------------------------------- 642-WHW 1.9 2.3 81.3 

Mudstone, phosphatic, and argillaceous 

phosphate rock-------------------------- 641-WHW 1.6 12.0 52.5 

Phosphate rock, argillaceous-------------- 640-WHW . 5 20.3 26.3 

Mudstone -------------------------------- 639- ERC . 6 3.2 71. 5 

Mudstone, phosphatic and phosphate rock---- 638- ERC 1.5 19.8 28.8 

Phosphate rock, cherty, and phosphatic 

sandstone; fos. col. no. 11664------------- 637- ERC 1.4 19.4 41.0 

A member of Phosphoria formation-upper part only 

Mudstone --------~----------------------- Dolomite, argi11aceous -------------------- Dolomite, argillaceous--------------------

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

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

Dolomite. argillaceous ------------------- Dolomite, argillaceous-------------------

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

Dolomite, argillaceous--------------------

3.4 

2.7 

6.0 

5. 6 

2.2 

2.9 

4.5 

5.0 

15.0 

Cumulative 

thickness 

(feet) 

154.5 

0.5 

1.6 

3.4 

4.9 

6.8 

8.4 

8.9 

9.5 

11.0 

12.4 

3.4 

6. 1 

12. 1 

17.7 

19.9 

22.8 

27.3 

32.3 

47.3 

Thickness x 

percent P 20 

(cumulativef 

--

0.15 

.37 

1. 45 

11.20 

15.57 

34.77 

44.92 

46.84 

76.54 

103.70 
..... 

w 

West Fork of Madison River, Mont., lot 1318 

D member of Phosphoria formation sampl~d and part of E member measured near West Fork oi Madison Rive.r, SEt sec. 30, T. 12 S., 

R. 2 W., Beaverhead County, Mont., on northeast limb of small anticline. D member sampled in bulldozer trench; E member 

measured from natural exposure at northeast end of trench. Beds strike N. 30• W. and dip 30° NE. Section measured by 

C. W. Tandy, J. L. Elliott, and E. R. Cressman and sampled by B. K. Replogle in August 1949. Samples analyzed by U.S. Bureau 

of M~n~s laboratory, Albany, Oreg. 

Chemical analyses 

Bed Sample Thickness (percent) Rock description no. (feet) P205 I Ac1a no. 

insoluble 

E member of Phos:pho,ria formation- top not exposed 

E- 8 Quartzite--------------------------------

E- 7 Quartzite -------------------------------- E- 6 Quartzite--------------------------------

E- 5 Quartzite --------------------------------

E- 4 Chert -----------------------------------

E- 3 

E- 2 

E- 1 

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

13.5 

10. 1 

1.9 

16.9 

10.6 

19.0 

1.3 

13.5 

D member of Phosphoria formation 

D-11 Mudstone -------------------------------- -- 13.0 -- n-io Mudstone -------------------------------- 3404- JLE 2.0 1.8 

D- 9 Mudstone -------------------------------- 3403- JLE . 8 . 8 

D- 8 Mudstone -------------------------------- 4402- JLE 3. 1 3.3 

D- 7 Phosphate rock, argillaceous -------------- 3401- JLE .9 17.8 

D- 6 Phosphate rock and argillaceous 

phosphate rock-------------------------- 3400- JLE . 8 28.4 

D- 5 Mudstone -------------------------------- 3399- JLE 4. 1 5.5 

D- 4 Phosphate rock and :phosphatic mudstone ---- 3398- JLE 1. 1 21.1 

-- Phosphate rock--------------------------- 3398b-JLE 

~: l~ 29.3 

-- Mudstone, phosphatiC?--------------------- 3398a-JLE 8.5 

3398-JLE resampled as two units. 

D- 3 Mudstone, phosphatic--------------------- 3397-CWT . 8 12.5 

D- 2 Phosphate rock--------------------------- 3396-CWT • 8 30.7 

D- 1 Mudstone, phosphatic--------------------- 3395-CWT 1. () 11.5 

--

81.3 

82.0 

74.0 

42.6 

20.0 

63.3 

27.5 

14. 7 

49.9 

49.3 

9.3 

55.0 

Cumulative 

thickness 

(feet) 

13.5 

23.6 

25.5 

42.4 

53.0 

72.0 

73.3 

86.8 

13.0 

15.0 

15.8 

18.9 

19.8 

20.6 

24.7 

25.8 

--

--

26.6 

27.4 

28.4 

C member of l?hosphoria formation-topped not logged, remainder not ex:poseq 

Thickness x 

percent P 20f 

(cumulative 

--

3.60 

4.24 

14.47 

30.49 

53.21 

88.()6 

111.27 

--

--

121.27 

145.83 

157.33 
~ 

foP. 

Little Water Canyon, Mont., lot 1341 

Band D members of Phosphoria formation sampled in two bulldozer trenches and C member measured from natural exposures near the 

head of Little Water Canyon between Timber Butte and Dixon Mountain on the north limb of a synclinal structure, SE;t sec. 4, 

T. 13 S., R. 10 W., Beaverhead County, Mont. Most beds strike N. so• W. and dip 45-so• SW. but faulted segment of E member 

is nearly horizontal. Section measured and sampled by R. F. Gosman, R. G. Waring, T. M. Cheney, and F. D. Frieske in 

September 1950. Samples analyzed by U. S. Bureau of Mines laboratory, Albany, Oreg. 

Bed Sample 

Chemical analyses Cumulative 

no. Rock description Thickness (percent) Thickness x 

no. (feet) l Acid 

thickness percent P 2o 

P205 insoluble (feet) (cumulative)S 

E member of Phosphoria formation-lower part(?) only 

E- 2 Chert and mudstone---------------------- -- 7.4 -- -- 7.4 --

Fault- unknown displacement. 

E- 1 Mudstone and chert ---------------------- -- 13.8 -- -- 21.2 --

Probable fault between D and E members. 

D member of Phosphoria formation 

I I I D-25 Mudstone, carbonatic--------------------- 5364-TMC 2. 6 4. 1 53.8 2.6 10.66 

D-24 Mudstone, carbonatic--------------------- 5363-TMC 2.4 4.5 49.2 5.0 21.46 

Beds D- 24 and D- 2 5 sheared and bedding 

indistinct. 

D-Z31 Mudstone, carbonatic--------------------- 5362-TMC 2.4 5.5 47.4 7.4 34.66 

D-22 Mudstone, phosphatic--------------------- 5361-TMC . 9 8.3 51.9 8.3 42.13 

D-21 Mudstone, carbonatic--------------------- 5360-TMC 2.2 6. 1 51. 7 10.5 55.55 

D-20 Mud~tone-------------------------------- 5359-TMC 1.5 6. 1 52.4 12.0 64.70 

D-19 Mudstone, phosphatic, carbonatic---------- 5358-RGW 1.1 10~4 39.7 13. 1 76.14 

D-18 Phosphate rock, argillaceous-------------- 5357-RGW 1.2 21.9 24.0 14.3 102.42 

D-17 Phosphate rock, argillaceous-------------- 5356-RGW 1.5 19.5 29.9 15.8 131. 67 

D-16 Phosphate rock -------------------------- 5355-RGW . 8 31.5 5. 0 16.6 156.87 

D-151 Mudstone, carbonatic--------------------- 5354-RGW . 6 4. 1 53.8 17.2 159.33 

D-14 Mudstone, carbonatic, and phosphatic 

mudstone ------------.------------------ 5353-RGW . 6 4.5 49.2 17.8 162.03 

D-13~ Mudstone, carbonatic-- ------------------- 5352-RGW . 8 5. 5 47.4 18.6 166.43 

D-12 Mudstone, phosphatic--------------------- 5351-RGW 1.4 13.3 40.3 20.0 185.05 

D-11 Phosphate rock and mudstone-------------- 5350-RGW 1.9 22.7 19.9 21.9 228.18 

0-10 I Mudstone-------------------------------- 5349-RGW 1.6 3.8 68.5 23.5 234.26 

D- 9 Mudstone, phosphatic--------------------- 5348-RFG 1.5 13.9 41.3 25.0 255.11 

D- 8 Phosphate rock, argillaceous-------------- 5347-RFG 1.8 21. 1 24.6 26.8 293.09 
....... 

c..n 

D- 7 Mudstone and phosphatic mudstone -------- 5346-RFG 1.2 10.2 52.6 28.0 

D- 6 Mudstone and phosphatic mudstone -------- 5345-RGW • 9 10.4 51. 8 28.9 

D- 5 Mudstone, phosphatic-------------------- 5344-RGW 1.8 13. 5 41.0 30.7 

D- 4 Mudstone ------------------------------- 5343-RGW 1.3 5.2 56. 1 32.0 

D- 3 Mudstone, phosphatic-------------------- 5342-RGW • 9 9.2 55.5 32.9 

D- 2 Sandstone, phosphatic-------------------- 5341-RGW 1.9 11. 1 58.2 34.8 

D- 1 Sandstone------------------------------- 5340-RGW . 9 6.4 64. 1 35.7 I 

C member of Phosphoria formation 

c- 8 Carbonate rock-------------------------- -- 2.9 -- -- 2.9 

c- 1 Covered interval ------------------------ -- 21. -- -- 23.9 

c- 6 Carbonate rock, cherty ------------------ -- 23.5 -- -~· 47.4 

c- 5 Covered interval ------------------------ -- 10. -- -- 57.4 

c- 4 Sandstone, calcareous ------------------- -- 14.2 -- -- 71.6 

C- 31 Carbonate rock-------------------------- -- 2.8 -- -- 74.4 

C- 2 Sandstone calcareous-------------------- -- 24.8 -- -- 99.2 

C- 1 Chert ---·------------------------------- -- 20.0 -- -- I 119.2 

B member of Phosphoria formation 

B-21 Phosphate rock, sandy------------------- 5373-TMC 0.2 18.2 45.6 0.2 

B-20 Carbonate rock and carbonatic chert------- -- . 9 -- -- 1.1 

B-19 Chert, carbonatic ----------------------- -- 1.6 -- -- 2.7 

B-18 Chert ---------------------------------- -- 14. 2 -- -- 16.9 

B-17 Mudstone------------------------------- -- 3.4 -- -- 20.3. 

B-16 Mudstone, cherty and chert--------------- -- 2.0 -- -- 22.3 

B-15 Mudstone------------------------------- -- 4.6 -- -- 26.9 

B-14 Chert----------------------------------- -- 1. 4 -- -- 28.3 

B-13 Mudstone------------------------------- -- . 6 -- -- 28.9 

B-12 Chert ---------------------------------- -- • 6 -- -- 29.5 

B-11 Mudstone------------------------------- -- 2.3 -- -- 31.8 

B-10 Mudstone, calcareous-------------------- -- 1.0 -- -- 32.8 

B- 9 Mudstone ------------------------------- -- 1.5 -- -- 34.3 

B- 8 Mudstone and phosphaterock-------------- 5372-RGW 2. 1 14.2 43.0 36.4 

B- 7 Phosphate rock-------------------------- 5371~RGW • 8 24.2 12.8 37.2 

B- 6 Mudstone, phosphatic and mudstone ------- 5370-RGW 1.6 17.0 28.2 38.8 

B- 5 Carbonate rock-------------------------- 5369-RGW 2.6 7. 0 17. 3 41.4 

B- 4 Mudstone, phosphatic -------------------- 5368-RGW 2.3 12.7 40.2 43.7 

B- 3 Phosphate rock and mudstone ------------- 5367-RGW . 8 20.2 22.2 44.5 

B- 2 Phosphate rock, argillaceous ------------- 5366-RGW 1.1 19.5 29.9 45.6 

B- 1 Phosphate rock-------------------------- 5365-TMC 1.5 31. 5 5. 0 47.1 

A member of Phosphoria formation-top bed only 

A- 11 Carbo~~te rock=~----------------------:_:1 -- } 5. 6 I -- I -- I 5. 6 J 

305.33 

314.69 

338.99 

345.75 

354.03 

375.12 

380.88 

--

--

--

--

--

--

--

--

--

--

--

--

--

29.82 

49.18 

76.38 

94.58 

123.79 

139.95 

161.40 

208.65 
........ 

()) 

Little Sheep Creek, Mont., lots 1294 and 1295 

Phosphoria formation sampled at Little Sheep Creek, Beaverhead County, Mont., on south end of major anticlinal structure. Beds A-1 to 

C-1 from bulldozer trench, and beds C-2 to C-12 from natural exposure near .Middle Fork of Little Sheep Creek, swt sec. 34, 

T. 14 S., R. 9 W. strike N. so• W. and dip zs• SE. Beds C-13 to E-6 from bulldozer trench near West Fork of Little Sheep 

Creek, st sec. 33, T. 14 s .. R. 9 W. strike N. so• E. and dip 10• S. Section measured by E.~. Cressman, W. H. Wilson, and 

C. W. Tandy and sampled by W. J. Garmoe, B. K. Replogle, R. F. Gosman, and J. L. Elliott in July 1949. Samples analyzed by 

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

Bed Sample 

!chemical analyses 

no. Rock description Thickness . {percent) Cumulative Thickness x 

no. (feet) p 0 I Acid 

thickness percent P 0 

2 5 insoluble (feet) (cumulati~ef 

E member of Phosphoria formation, lot 1295-lower part only 

E- 6 Chert and silty chert --------------------- -- 11.0 -- -- 11.0 -- E- 5 Chert, silty, silty dolomite, chert, and 

dolomite ----------·--------r----------- -- 22.8 -- -- 33.8 -- E- 4 Chert, silty; fos. col. no. 11663------------ -- 12.8 -- -- 46.6 -- E- 3 Chert, silty; fos. col, no. 11662------------ -- 5.5 -- -- 52. 1 -- E- 2 Chert, silty; fos. col. no. 11661 ------------ -- 10.4 -- -- 62.5 --

E- 1 Mudstofie, cherty; fos. col. no. 11660------- -- 15.0 -- -- 77.5 -- , __ 

D member of Phosphoria formation, lot 1295 

D-18 Mudstone, carbonatic; fos. col. no. 11659 --- 358- ERC 2.3 53.6 I 2.3 

D-17 Mudstone, carbonatic; fos. col. no. 11658 --- 357- ERC 5.3 46.0 7.6 

Beqs D-16 ;1nd :Q-1 7 separated by fault of 

unknown stratigraphic displacement. 

D-16 Muqstone-------------------------------- 356- ERC 3.7 1.0 84.5 11.3 3.70 

D-15 l\r{11dstone, carbona tic--------------------- 355- ERC 1.8 1.3 59.2 13. 1 6. 04 

D-14 Mudstone, carbonatic --------------------- 354- ERC 1.7 3.8 54.2 14.8 12.50 

D-13 Mud~;!tone, phosphatic, carbonatic, and 

carbona tic mudstone--------------------- 353- ERC 2.0 6.7 41.9 I 16.8 I 25.9-0 

D-12 I Carbonate rock, pposphatic, argillaceous--- 352-ERC • 7 11.5 20.9 17.5 33.95 

D-11 Mudstone, carbonatic~ phosphatic 

mudstone, anq phosphate rock------------ 351- ERC 2.0 10.7 41. 1 I 19.5 I 55.35 

Bed P-ll is sheared; D-10 to D-12 inverva1 

not more than 2 feet. 

D-10 I M~qstone, carbonatic, anq ph-osphatic, 

Cfl.rbonatic mudstone--------------------- ~50- ERC 1.0 14.3 26.'9 20.5 69.65 

P- 91 Carbonate rock, arg!llacepus -------------- 349-ERC . 5 2. 5 20.3 21.0 70.90 

D- 8 Mudstone, phosphatic; fos. col. no. 11657 -- 348-ERC 1.4 10.(> 45.1 22.4 85.74 
D- 71 Mudstone and argillaceous phosphate rock---

D- 6 Mudstone, phosphatic, and argillaceous 

phosphate rock--------------------------

g: ~ I ~~~:~~~~e-;~~k:-;h~;;h;ti~-~~d~~~~;:·----- and mudstone---------------------------

D- 3 I Mudstone--------------------------------

D- 21 Mudstone, phosphatic, calcareous --------- D- 1 Phosphate rock, sandy; fos. col. no. 11656-

347- ERC 

346-ERC 

345- ERC 

344-ERC 

343- ERC 

342- ERC 

341- ERC 

. 7 

1.7 

.45 

. 9 

. 5 

• 6 

1.1 

8·. 6 

17.0 

1.5 

23.7 

6.7 

8.5 

16.9 

54.9 

37. 1 

72.9 

23.7 

63.2 

56.3 

25.4 

C member of Phosphoria formation, lots 1294 and 1295 

C-13 

C-12 

C-11 

C-10 

c- 9 

c- 8 

c- 1 

~ c- 6 

c- 5 

c- 4 

c- 3 

C- 2 

lot 1295 

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

Limestone; fos. col. no. 11653 ------------- Limestone-------------------------------

Limestone; fos. col. no. 11652 ------------- Limestone, cherty, silty, and silty 

limestone ------------------------------

Mudstone, calcareous, dolomitic; fos. 

col. no. 11651-----.. --------------------- Chert and limestone; fos. col. no. 11650 ----

Limestone; fos. col. no. 11649 ------------- Limestone-------------------------------

Dolomite, sandy -------------------------

Dolomite -------------------------------- Sandstone, dolomitic ; fos. col. no. 11648--

Covered interval-------------------------

lot 1294 

C- 1 I Mudstone--------------------------------

340- ERC 

339-CWT 

1.8 

7.0 

9.0 

4.6 

31.0 

25.0 

11.0 

6.0 

4.7 

11.0 

24.0 

4. 5 

30 

6.0 

0.9 

• 6 

B member of Phosphoria formation, lot 1294 

B-15 

B-14 

B-13 

B-12 

B-11 

B-10 

B- 9 

B- 8 

Phosphate rock, argillaceous; fos. col. 

no. 11647 ------------------------------ Chert-----------------------------------

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

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

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

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

Mudstone, phosphatic and mudstone--------

Mudstone, phosphatj.c and mudstone--------

338-CWT 

337-CW'l' 

336-CWT 

335-CWT 

334-CWT 

333-CWT 

332-CWT 

331-CWT 

1.3 

13.3 

9.3 

. 8 

• 8 

2. 5 

i.7 

• 7 

25.3 • 3 

• 2 

2.9 

16.5 

• 3 

8.3 

9.2 

5.0 

88.7 

17.8 

92.5 

87.2 

83.8 

39.5 

79.7 

62.3 

51.8 

23.1 

24.8 

25.25 

26.15 

26.65 

27.25 

28.35 

1.8 

8.8 

17.8 

22.4 

53.4 

78.4 

89.4 

95.4 

100.1 

111. 1 

135.1 

139.6 

169.6 

175.6 

1.3 

14.6 

23.9 

24.7 

25.5 

28.0 

29.7 

30.4 

1 Fossil collection made by W. R. Record, Paleontology and Stratigraphy Branch, U. S. Geological Survey. 

91. 76 

120.66 

121.34 

142.66 

146.02 

151. 12 

169.70 

3.2.89 

36.88 

38.74 

41.06 

54.26 

55.01 

69.12 

75.56 
Little Sheep Creek-Continued 

Cherp.ical analyses 

Bed Rock description Sample Thickness (percent) 

no. no. (feet) P205 

Acid 

insoluble 

B- 7 ~udstone, phosphatic -------------------- 330-CWT 0.6 9.4 44.8 

B- 6 Phosphate rock, argillaceous ------------- 329-CWT 1.3 26.5 16.0 

B- 5 ~udstone ----------------=-------------- 328-CWT 1.4 6.4 65.3 

B- 4 Phosphate rock, sandy; fos. col. no. 

11645 --------------------------------- 327-CWT 1.5 20.3 24.3 

B- 3 Phosphate rock-------------------------- 326-ERC 1.2 33.0 1.7 

B- 2 ~udstone and phosphate rock-------------- 325- ERC . 8 21.2 28.5 

B- 1 Phosphate rock-------------------------- 324- ERC 1.5 32.4 5.0 

A member of Phosphoria formation, lot 1294-upper part only 

A-291 Sandstone, calcareous--------------------

A-28 ~udstone, dolomitic---------------------

A-27 

A-26 

A-25 

~ A-24 

A-23 

A-22 

A-21 

A-20 

A-19 

A-18 

A-17 

A-16 

A-15 

Bed A-28 is bounded by faults; it may 

be the equivalent of bed A-26. 

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

Mudstone, carbonatic -------------------- Carbonate rock--------------------------

Dolomite and dolomitic siltstone-----------

~udstone carbonatic --------------------

~udstone' carbonatic --------------------

~udstone' -------------------------------

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

Mudstone carbonatic -------------------- ~udstone: calcareous, dolomite, and 

dolomitic mudstone---------------------

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

Dolomite, argillaceous and dolomite-------

Dolomite; fos. col. no. 11644 --------------

A-141. Dolomite--------------------------------

A-13 Limestone dolomitic -------------------- A-12 Limestone'------------------------------

Bed A -12 is bounded by a fault of unknown 

displacement. 

A-ll I Dolomite--------------------------------

A-10 Dolomite; fos. col. no. 11643 --------------

A- 9 I Limestone, sandy; fos. col. no. 11642------

323-CWT 

322- ERC 

321-ERC 

320- ERC 

319-CWT 

318-CWT 

317-CWT 

316-ERC 

315- ERC 

6.2 

3.0 

10.6 

3.0 

4.7 

1.3 

6.2 

4.8 

11. 2 

13.4 

10.0 

3.5 

6.3 

4.5 

3.5 

7 0 1 

5.6 

3.8 

1.8 

14.4 

5. 5 

0.3 1.5 

. 2 55.5 

• 1 3.7 

. 1 25. 7 

. 2 57. 1 

. 1 63. 1 

. 0 70. 7 

• 0 72.3 

. 1 64.0 

-- -- -- -- -- -- -- --

-- -- -- -- -- --

Cumulative 

thickness 

(feet) 

31.0 

32.3 

33.7 

35.2 

36.4 

37.2 

38.7 

6.2 

9.2 

19.8 

22.8 

27.5 

28.8 

35.0 

39.8 

51.0 

64.4 

74.4 

77.9 

84.2 

88.7 

92.2 

99.3 

104.9 

108.7 

110.5 

124.9 

130.4 

Thickness x 

percent P 20 5 (cumulative) 

81..20 

115.65 

124.61 

155.06 

194.66 

211. 62 

260.22 

3.18 

3.78 

4.25 

4.38 

5.62 

6.10 

6. 10 

6.10 

7. 10 
1--' 

~ 

Faults of unknown displacement occur 

between beds A-9 and A-8 and beds 

A-6 and A-5 below. 

A- 8 I Dolomite, dolomitic siltstone, and 

calcareous siltstone 

A- 7 Dolomite, calcareous, silty 

A- 6 Sandstone, calcareous 

A- 5 Sandstone and calcareous sandstone 

A- 4 Sandstone and sandy limestone 

A- 3 I Dolomite, silty 

A- Z Dolomite, mudstone, and silty dolomite; 

fos. col. no. 11641 

A- 1 I Dolomite 

--

--

--

--

--

--

--

--

4.4 -- -- 134.8 

1.7 -- -- 136.5 

7.4 -- -- 143.9 

9.8 -- -- 153.7 

10.8 -- -- 164.5 

2.5 -- -- 167.0 

1.0 I -- I -- I 168.0 

z. 1 -- -- 170. 1 
1:\:) 

0 

Crooked Creek, Mont., lots 1296 and 1297 

Band D membe::.·s of Phosphoria formation sampled and parts of A, C, and D members described in two bulldozer trenches near the head 

of Crooked Creek, swt sec. 1, 'T. 15 S., R. 8 W., Beaverhead County, Mont., from southeastward-dipping strata near the south 

end of a large anticlinal structure. Beds A-1 through C-5 described at the upper trench (lot 1296) from beds striking N. 60• E. 

and dipping 6s• SE. Beds C-6 through E-2 described at the lower trench (lot 1297) 350 feet east from overturned beds striking 

N. so• E. and dipping 10• NW. D member is so strongly sheared that the thickness and stratigraphic sequence may be incorrect. Section measured by E. R. Cressman and W. H. Wilson and sampled by J. L. Elliott, B. K. Replogle, and W. J. Garmoe 

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

Bed Sample 

Chemical analyses 

no. Rock description Thickness (percent} 

no. (feet) j acra -----

P2os insoluble 

E member of Phosphoria formation, lot 1297 -lnwer part only 

E- 21 Mudstone-:-------------------------------

E- 1 Chert, arg11laceous----------------------- 636-WHW 

11. 7 

15.2 

D member of Phosphoria formation, lot 1297 

D-21 Mudstone, phosphatic·and mudstone-------- 635- ERC 2.3 4.4 

D-20 Mudstone-------------------------------- 634- ERC 4.3 7.4 

D-19 Mudstone, phosphatic--------------------- 633- ERC 4.3 13. 7 

D-18 Mudstone -------------------------------- 632- ERC 3.5 7.5 

D-17 Mudstone, carbonatic --------------------- 631- ERC 4.8 6.5 

D-16 Mudstone, carbonatic --------------------- 630- ERC 3.8 7. 1 

D-15 Mudstone, carbonatic --------------------- 629- ERC 4.3 6.4 

D-14 Mudstone, carbonatic --------------------- 628- ERC 4.0 5.5 

D-13 Mudstone, carbona tic--------------------- 627- ERC 4.2 3.6 

D-12 Mudstone, carbonatic --------------------- 626- ERC 4.4 7.5 

D-11 Mudstone, carbonatic --------------------- 625- ERC 4.5 7.6 

D-10 Phosphate rock, argillaceous -------------- 624-WHW 3. 5 14.5 

D- 9 Mudstone, carbonatic ------------------.. -- 623-WHW 5.0 7.4 

D- 8 Carbonate rock, argillaceous, phosphatic--- 622-WHW 1.7 8.6 

D- 7 Mudstone-------------------------------- 621-WHW 3.7 5. 2 

D- 6 Phosphate rock, argillaceous--------·----- 384-WHW • 8 18.3 

D- 5 Mudstone, phosphatic--------------------- 383-WHW 2.5 8. 1 

D- 4 Mudstone, phosphatic, carbonatic ---------- 382- ERC 1.2 8. 7 

D- 3 Phosphate rock, argillaceous -------------- 381- ERC 1.7 18.3 

D- 2 Mudstone, phosphatic mudstone, and 

phosphate rock-------------------------- 380- ERC • 9 13.7 

D- 1 Phosphate rock--------------------------- 379- ERC 1.6 27.9 ----

65.5 

56. 1 

45.8 

53.9 

48.0 

48.3 

47.3 

48.3 

53. 1 

36.0 

37.4 

32.9 

40.7 

18. 7 

59.6 

31. 3 

48.0 

45.3 

35.3 

47.0 

14.3 ....... 

Cumulative 

thickness 

(feet) 

11.7 

26.9 

2.3 

6.6 

10.9 

14.4 

19.2 

23.0 

27.3 

31.3 

35.5 

39.9 

44.4 

47.9 

52.9 

54.6 

58.3 

59. 1 

61.6 

62.8 

64.5 

65.4 

67.0 

-~~ 

Thickness x 

percent P 2o 

(cumulativef 

10. 12 

41.94 

100.85 

127. 10 

158.30 

185. 28 

212.80 

234.80 

249.92 

282.92 

317.12 

367.87 

404.87 

419.49 

438.73 

453.37 

473.62 

484.06 

515.17 

527.50 

572.14 
~ 

....... 

c- 1 

c- 6 

c- 5 

c- 4 

c- 3 

c- 2 

c- 1 

B-17 

B-16 

B-15 

B-14 

B-13 

B-12 

B-11 

B-10 

B- 9 

B- 8 

B- 7 

B- 6 

B- 5 

B- 4 

B- 3 

B- 2 

B- 1 

C member of Phosphoria formation, lots 1296 and 1297-upper and lower par.ts only 

lot 1297 

ldudstone ------------------------------- 378- ERC 1. 6 4.7 68.5 1.6 

Sandstone, phosphatic-------------------- 377- ERC 5.9 13.6 35.3 7.5 

Fos. col. no. 116941 4. 0 feet below base 

of bed c-6. 

Unknown stratigraphic interval between 

beds C-5 and C-6. 

lot 1296 

St!ndstone, dolomitic, and calcareous 

dolomite------------------------------- -- 11.9 -- -- 19.4 

Chert----------------------------------- -- 3.6 -- -- 23.0 

Dolomite, cherty ------------------------ I 

-- 9.9 -- -- 32.9 

Dolomite, mudstone, and chert ----------- -- 2.5 -- -- 35.4 

ldudstone ------------------------------- 376- ERC 4.3 1.2 84.8 39.7 

B member of Phosphoria formation, lot 1296 

Phosphate rock and mudstone ------------- 375- ERC 1. 1 24.5 26.0 1.1 

Chert and argillaceous phosphate rock; 

contains sponge spicules ---------------- 374- ERC 1.1 10.9 58.8 2.2 

Chert----------------------------------- 373- ERC 5.4 . 3 89.0 7.6 

Chert----------------------------------- 372- ERC 3.7 . 3 89.8 11.3 

Chert----------------------------------- 371- ERC 5.5 1.0 87.5 16.8 

Phosphate rock, cherty and phosphate 

rock ---------------------------------- 370- ERC . 6 23.1 28.0 17.4 

ldudstone ------------------------------- 369- ERC 1.9 . 5 80.8 19.3 

Carbonate rock, argillaceous ------------- 368- ERC 1.3 . 0 36.5 20.6 

Mudstone and phosphatic mudstone--------- 367- ERC 1.1 5.9 59.7 21.7 

Mudstone, carbonatic -------------------- 366- ERC 2.3 2. 1 64.5 24.0 

Mudstone, carbonatic, and phosphatic 

mudstone ------------------------------ 365- ERC 1.3 5. 8 49.7 25.3 

Mudstone, phosphatic, carbonatic --------- 364- ERC . 8 7.9 46.5 26.1 

Phosphate rock-------------------------- 363- ERC • 5 27.1 11. 6 26.6 

Mudstone, carbbnatic -------------------- 362- ERC 1.2 6.4 38.0 27.8 

Mudstone, carbonatic -------------------- 361- ERC . 6 3.9 58.0 28.4 

Phosphate rock; fos. col. no. 11693 -------- 360- ERC 1.5 31. 2 6.2 29.9 

Phosphate rock; fos. col. no. 11692 -------- 359- ERC . 5 27.3 17.2 30.4 

1 

Fossil collection made by W. R. Record, Paleontology and Stratigraphy Branch, U. S. Geological Survey. 

--

--

--

--

--

--

--

26.95 

38.94 

40.56 

41.67 

47.17 

61.03 

61.98 

61.98 

68.47 

73.30 

80.84 

87.16 

100.71 

108.39 

110.73 

157.53 

171. 18 
Bed 

no. 

A-24 

A-23 

A-22 

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 

t..:JA- 8 

A- 7 

A"- 6 

A- 5 

A- 4 

A- 3 

A- 2 

A- 1 

Crooked Creek-Continued 

Sample 

Chemical analyses 

Rock description Thickness (percent) 

no. (feet) I Acid P2o5 insoluble -~----~ 

A member of Phosphoria formation, lot 1296 

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

Dolomite -------------------------------- Dolomite, cherty -------------------------

Dolomite -------------------------------- Dolomite, silty---------------------------

Dolomite, calcareous---------------------

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

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

Mudstone -------------------------------- Dolomite, calcareous---------------------

Siltstone dolomitic-----------------------

Dolomite'; fos. col. no. 11690---------------

Mudstone dolomitic----------------------

Mudstone' dolomitic----------------------

Sandstone', calcareous---------------------

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

Dolomite -------------------------------- Dolomite --------------------------------·· Dolomite, sandy - ------------------------- Sandstone, dolomitic----------------------

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

Covered interval--------------------------

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

Covered to Quadrant contact---------------

3.3 

0 5 

. 6 

3.3 

8.9 

10.0 

6.3 

1.6 

. 9 

3.3 

4.5 

5.0 

5.8 

6.3 

8.0 

10.6 

7.2 

7.4 

14. 1 

7.5 

6.0 

10.0 

12.5 

13.2 

10.0 

Cumulative 

thickness 

(feet) 

3.3 

3.8 

4.4 

7.7 

16.6 

26.6 

32.9 

34.5 

35.4 

38.7 

43.2 

48.2 

54.0 

60.3 

68.3 

78.9 

86.1 

93.5 

107.6 

115. 1 

121. 1 

131. 1 

143.6 

156.8 

166.8 

Thickness x 

percent P 2o 5 ( cumulative) 
Camp Frigid, Mont. , lot 1343 

B member of Phosphoria formation measured and sampled at natural exposure i mile northeast of Camp Frigid, SWt sec. 34, T. 14 S., R. 1 w .• Beaverhead County, Mont., by B. K. Replogle in September 1950. Samples analyzed for P 2o5 and acid ~nsoluble by U. S. Bureau of Mines laboratory, 

Albany, Oreg .• and for other constituents by Trace Elements Section laboratory, U. S. Geological Survey, Washington, D. C. 

Bed Sample Thickness Chemical analyses (percent) Cumulative Thickness x 

Rock description I I I Loss on I Acid thickness percent P 2o no. no. (feet) 5 P205 Al203 Fe203 ignition insoluble (feet) (cumulative) ··--- ---

C member of Phosphoria formation-not measured 

B member of Phosphoria formation 

B-7 Sandstone and carbonate rock------------- 5561-BKR 1.0 4. 7 -- -- -- 62.2 1.0 -- B-6 Phosphate rock-------------------------- 5560-BKR . 7 32.4 -- -- -- 7. 0 1.7 -- B-5 Covered interval; some phosphate rock 

in float-------------------------------- -- 9.0 -- -- -- -- -- 10. 7 ~-

B-4 Phosphate rock-------------------------- 5559-BKR 1. 8 33.9 0.24 0.28 4.30 2. 8 12. 5 61.02 

B-3 Phosphate rock-------------------------- 5558-BKR 2.2 33.4 . 83 .38 3.45 6.3 14. 7 134.50 

B-2 Carbonate rock, sandy------------------- 5557-BKR 1.8 3.7 . 10 .43 24.01 39.7 16. 5 141. 16 

B-1 Phosphate rock ----- ---- -------- -- ------- 5556-BKR 2.4 31.0 .28 .43 5.68 9. 3 18.9 215.56 -- -:....--..---- --- -~-

A member of Phosphoria formation-top bed only 

~-------r---------------------------------------------------------------,-----------------.---------------.--------,---------~------~.-------------.--------------,---------------------.-----------------------

w A-1 I Carbonate rock--------------------------1 -- I 2. 5 I -- I -- I -- I -- I -- I 2. 5 I 

INT.-DUP. SEC., WASH., D.C&OittO