Pierre 

Shale 

Baculites scotti (fig. 2, zone 63)

Exiteloceras jenneyi (fig. 2, zone 66)

Didymoceras cheyennense (fig. 2, zone 67)

Baculites eliasi (fig. 2, zone 72)

Baculites reesidei (fig. 2, zone 70)

Baculites perplexus (fig. 2, zone 60)

 Niobrara 

Formation 

 Fox Hills 

Sandstone 

0

1,000

2,000

1,500

500

3,000

2,500

NW Black Hills—Crook County, WY—

T. 55–56 N., R. 67–68 W.

3,500

4,000

 Nonmarine 

 sandstone, 

 sandy shale,

and claystone 

4,500

 Lance 

Formation 

Baculites sp. (smooth) (fig. 2, zone 54)

Baculites gregoryensis (fig. 2, zone 61)

Didymoceras stevensoni (fig. 2, zone 65)

Didymoceras nebrascense (fig. 2, zone 64)

Red Bird Silty Member

Baculites sp. (weak flank ribs) (fig. 2, zone 55)

Scaphites hippocrepis III (fig. 2, zone 53) 

Mitten 

Member

Gammon Member

Scaphites hippocrepis I (fig. 2, zone 51) 

Carlile 

 Shale 

Sage Breaks Member

Scaphites mariasensis (fig. 2, zone 38) 

Turner Sandy Member Scaphites whitfieldi (fig. 2, zones 34–35) 

Pool Creek Member

Greenhorn 

Formation 

 Belle

Fourche 

 Shale 

Mowry 

 Shale

 (part) 

Dunveganoceras pondi (fig. 2, zone 15)

Plesiacanthoceras wyomingense (fig. 2, zone 14)

Inoceramus arvanus (fig. 2, zone 12)

Dunveganoceras conditum (fig. 2, zone 18)

Inoceramus pictus (fig. 2, zones 19–22)

Inoceramus howelli (fig. 2, zones 29, 30)

Scaphites nigricollensis (fig. 2, zone 36) 

Pierre 

Shale 

Baculites baculus (fig. 2, zone 73)

Baculites grandis (fig. 2, zone 74)

Baculites eliasi (fig. 2, zone 72)

Kara Bentonitic Member

Baculites eliasi (fig. 2, zone 72)

Baculites eliasi (fig. 2, zone 72)

Baculites perplexus (fig. 2, zone 60)

Gammon Member 

 Niobrara 

Formation 

Carlile 

 Shale

Turner Sandy Member

Pool Creek Member

Scaphites whitfieldi (fig. 2, zones 34, 35) 

Collignoniceras woollgari (fig. 2, zone 28) 

Greenhorn 

Formation 

Mytiloides mytiloides (fig. 2, zone 27) 

Metoicoceras muelleri (fig. 2, zone 17) 

 Belle 

Fourche 

 Shale

Mowry 

 Shale 

 (part)

Marker (gray-red) bentonite Acanthoceras amphibolum (fig. 2, zone 13) 

Acanthoceras alvaradoense (fig. 2, zone 12) 

Red Bird Silty Member

Mitten Member

Sage Breaks Member 

Scaphites warreni (fig. 2, zone 32) 

 Fox Hills 

Sandstone 

0

1,000

1,500

500

Thornton Dome—Weston County, WY—

Sec. 18, T. 48 N., R. 65–67 W.

 Nonmarine 

 sandstone, 

 sandy shale,

and claystone 

 Lance 

Formation 

Baculites scotti (fig. 2, zone 63)

Baculites gregoryensis (fig. 2, zone 61)

Cremnoceramus deformis dobrogensis (fig. 2, zone 40) 

Mytiloides scupini (fig. 2, zone 37) 

Dunveganoceras pondi (fig. 2, zone 15) 

Borissiakoceras compressum (fig. 2, zone 9) 

Clay Spur Bentonite Bed 

 Fox Hills 

Sandstone 

3,000

4,000

3,500

2,500

5,000

4,500

Red Bird—Niobrara County, WY—

Secs. 13, 14, and 24, T. 38 N., R. 62 W.

Baculites clinolobatus (fig. 2, zone 75) 

Baculites grandis (fig. 2, zone 74)

Baculites baculus (fig. 2, zone 73)

Endocostea typica (fig. 2, zone 73)

Cataceramus ? subcircularis 

Upper unnamed shale member 

Tenuiptera fibrosus 

Baculites grandis (fig. 2, zone 74)

Baculites grandis (fig. 2, zone 74)

Endocostea typica (fig. 2, zone 73)

Baculites eliasi (fig. 2, zone 72)

Kara Bentonitic Member

Baculites eliasi (fig. 2, zone 72)

Baculites eliasi (fig. 2, zone 72)

Baculites cf. B. jenseni 

Baculites reesidei (fig. 2, zone 70)

Baculites reesidei (fig. 2, zone 70) Exiteloceras jenneyi (fig. 2, zone 66) 

Didymoceras stevensoni (fig. 2, zone 65)

Didymoceras nebrascense (fig. 2, zone 64)

Baculites scotti (fig. 2, zone 63) Didymoceras nebrascense (fig. 2, zone 64)

Baculites scotti (fig. 2, zone 63)

Red Bird Silty Member

Lower unnamed shale member

Baculites scotti (fig. 2, zone 63) Baculites gregoryensis (fig. 2, zone 61)

Baculites gregoryensis (fig. 2, zone 61)

Baculites gregoryensis (fig. 2, zone 61)

Baculites perplexus (fig. 2, zone 60)

Baculites perplexus (fig. 2, zone 60) Baculites gilberti 

Baculites gilberti 

 Lance 

Formation 

0

1,000

2,000

1,500

500

 Mostly 

 continental 

 sandstone, 

 sandy shale, 

claystone and 

carbonaceous 

 shale 

Pierre 

Shale 

5,500

6,000

Mitten Member 

Baculites obtusus (fig. 2, zone 56)

Baculites gilberti 

Baculites perplexus (fig. 2, zone 60)

Baculites perplexus (fig. 2, zone 60)

Baculites perplexus (fig. 2, zone 60)

Baculites perplexus (early form) 

Baculites sp. (smooth) (fig. 2, zone 59)

Baculites maclearni (fig. 2, zone 57)

Baculites asperiformis (fig. 2, zone 58)

Sharon Springs Member 

Gammon Member 

 Niobrara 

Formation 

Carlile 

 Shale

Sage Breaks Member 

Turner Sandy Member

Pool Creek Member

Volviceramus involutus (fig. 2, zone 43) 

Mytiloides cf. M. incertus (fig. 2, zone 36) 

Scaphites whitfieldi (fig. 2, zones 34, 35) 

Collignoniceras woollgari (fig. 2, zone 28) 

Greenhorn 

Formation 

Mytiloides mytiloides (fig. 2, zone 27) 

Metoicoceras defordi (fig. 2, zone 17) 

 Belle 

Fourche 

 Shale

6,500

Mowry 

 Shale

 (part)

Marker (gray-red) bentonite 

Acanthoceras amphibolum (fig. 2, zone 13) 

Acanthoceras alvaradoense (fig. 2, zone 12) 7,000

7,500

 Fox Hills 

Sandstone 

0

1,000

2,000

1,500

500

3,000

2,500

Lewis 

Shale 

Glenrock, Converse County, WY—

T. 32–33 N., R. 75–78 W.

Baculites clinolobatus (fig. 2, zone 75) 

3,500

Baculites grandis (fig. 2, zone 74)

Baculites eliasi (fig. 2, zone 72)

 Lance 

Formation 

Continental 

 strata: 

 fluviatile 

 sandstone, 

sandy shale, 

 claystone, 

and carbonaceous shale. 

4,000

4,500

5,000

Baculites eliasi (fig. 2, zone 72)

7,500

Baculites jenseni (fig. 2, zone 71)

Baculites scotti (fig. 2, zone 63)

Didymoceras nebrascense (fig. 2, zone 64)

Baculites perplexus (fig. 2, zone 60)

Baculites perplexus (fig. 2, zone 60)

Niobrara Member 

Sage Breaks Member 

Inoceramus perplexus (fig. 2, zone 34) 

Nicaisolopha lugubris (fig. 2, zones 31–33) 

8,500

Mowry 

 Shale

 (part)

5,500

6,000

6,500

7,000

8,000

Didymoceras stevensoni 

(fig. 2, zone 65)

Teapot Sandstone Member

Parkman Sandstone Member

Mesaverde

Formation 

Cody 

Shale 

 Frontier 

Formation 

Wall Creek Member 

Belle Fourche Member 

Rock River—Albany County, WY—

Secs. 8–11, 14–16, 21, 29, T. 20 N., R. 76 W.

Baculites gregoryensis (fig. 2, zone 61)

Baculites perplexus (fig. 2, zone 60)

Baculites perplexus (fig. 2, zone 60)

Baculites eliasi (fig. 2, zone 72) 

Didymoceras stevensoni (fig. 2, zone 65) 

Baculites grandis (fig. 2, zone 74) 

Baculites jenseni (fig. 2, zone 71) 

Baculites eliasi (fig. 2, zone 72) 

Pine Ridge

Sandstone

Rock River

Formation

Baculites reduncus (fig. 2, zone 62) 

Placenticeras pinque (fig. 2, zone 62)

Endocostea typica (fig. 2, zone 73) 

7,500

8,000

8,500

9,000

9,500

10,000

10,500

5,000

Baculites clinolobatus (fig. 2, zone 75) 

 Fox Hills 

Sandstone 5,500

6,000

6,500

7,000

Lewis 

Shale 

 Frontier 

Formation 

Calycoceras obrieni

Sage Breaks 

 Shale 

Scaphites whitfieldi (fig. 2, zone 34, 35) 

Metoicoceras defordi (fig. 2, zone 17) 

Mowry 

 Shale

 (part)

 Niobrara 

Formation 

Steele 

Shale 

Mytiloides incertus (fig. 2, zone 36) 

Inoceramus prefragilis (fig. 2, zones 14, 15) 

11,000

11,500

12,000

12,500

13,000

13,500

 Fox Hills 

Sandstone 

0

1,000

2,000

1,500

500

3,000

2,500

Pierre 

Shale 

 Niobrara 

Formation

Fort Hays Limestone Member

Pseudoperna congesta

Mitten Member

Buckeye—Larimer County, CO—Sec. 2, T. 10 N., R. 69 W., 

Secs. 17–20, T. 11 N., R. 68 W., Secs. 22, 27, 34, 35, T. 11 N., R. 69 W.

Exiteloceras jenneyi (fig. 2, zone 66)

Cremnoceramus deformis (fig. 2, zone 40)

6,000

6,500

7,500

Baculites clinolobatus (fig. 2, zone 75) 

Hygiene Sandstone Member

Baculites gregoryensis (fig. 2, zone 61) 

Baculites perplexus (fig. 2, zone 60) 

Didymoceras nebrascense (fig. 2, zone 64) 

Baculites grandis (fig. 2, zone 74)

5,500

7,000

Baculites scotti (fig. 2, zone 63)

Smoky Hill Shale Member

Carlile Shale

Greenhorn 

Limestone

Sharon Springs Member

Inoceramus ginterensis (fig. 2, zones 16–18)

3,500

8,000

8,500

9,000

9,500

4,000

Gammon Member

Baculites obtusus (fig. 2, zone 56)

Baculites maclearni (fig. 2, zone 57) 

Baculites asperiformis (fig. 2, zone 58) 

Baculites perplexus (fig. 2, zone 60) 

Unnamed member

Terry Sandstone Member

Unnamed shale member

Didymoceras cheyennense (fig. 2, zone 67) 

Baculites cuneatus (fig. 2, zone 69)

Rocky Ridge Sandstone Member 

Baculites reesidei (fig. 2, zone 70)

Unnamed sandy shale member 

Larimer Sandstone Member 

Unnamed shaly sandstone member Baculites reesidei (fig. 2, zone 70)

Richard Sandstone Member Baculites jenseni (fig. 2, zone 71) 

Unnamed shale member 

Baculites baculus

Baculites eliasi (fig. 2, zone 72) 

Unnamed sandstone member 

Unnamed upper shale member 

Baculites baculus (fig. 2, zone 73) 

Upper transition member 

Baculites sp.

Endocostea typica 

Codell Sandstone and Blue Hill Members

Mytiloides mytiloides (fig. 2, zone 27)

Ostrea beloiti (fig. 2, zones 12–15) Graneros 

 Shale Conlinoceras gilberti (fig. 2, zone 9 ) 

(fig. 2, zone 73) 

Baculites eliasi (fig. 2, zone 72) 

Baculites asperiformis (fig. 2, zone 58) 

Baculites asperiformis (fig. 2, zone 58) 

Baculites asperiformis (fig. 2, zone 58) 

Baculites maclearni (fig. 2, zone 57) 

 Laramie 

Formation 

 Mostly 

 continental 

 sandstone, 

siltstone, and 

 shale, and 

 coal. 

4,500

5,000

47 miles

65 miles

85 miles

78 miles 72 miles

? ?

?

?

?

? ?

? ?

?

? ?

 * * * * *

 * * * *

 * * * *

 * * * *

 * * * *

 * * * *

 * * * *

 * * * *

 * 

EXPLANATION

Conglomerate

Sandstone

Sandstone with 

 shale partings

Sandstone, 

 calcareous

Siltstone

Shale

Shale with

 sandstone lenses

Limestone

Bentonite

Shale, 

 calcareous

Shale, 

 carbonaceous

Limestone, shaly

 * * * * Disconformity

Contact of 

 formations

Probable 

 correlation 

 of strata 

? ?

Approximate 

 contact of 

 formations

??

Approximate 

 correlation 

 of strata 

 * ?? Possible 

 disconformity 

A B

NORTHEASTERN WYOMING NORTH-CENTRAL COLORADO

0

1,000

2,000

1,500

500

3,000

2,500

3,500

 Continental 

 strata: 

 fluviatile 

 sandstone, 

siltstone, and 

 shale with 

coal in lower 

 part of 

 formation 

 

 Medicine

 Bow 

Formation 

 Ferris 

Formation

 (part) 

 Continental 

 strata: 

conglomeratic 

 sandstone, 

 sandstone, 

 and shale 

4,500

Thickness 

of sequence 

omitted

 * * * *

 * * * *

 * * * *

 ? * ? *

 * * * *

 * * * *

 * * * *

 * * * *

Marker (gray-red) bentonite 

Bridge Creek Member

Hartland Shale/Lincoln Members

Ardmore 

Bentonite

Bed 

Ardmore Bentonite Bed 

Marker (gray-red) bentonite 

Lower unnamed shale member

Lower unnamed shale member

Upper unnamed shale member

Steele Member 

 * * * *

?

?

?

 ?

?

 ? ?

?

 ? ? ? ?

Baculites asperiformis (fig. 2, zone 58)

?

? ?

? ?

Clay Spur Bentonite Bed 

Clay Spur Bentonite Bed 

 ?

 * 

2,000

3,000

2,500

3,500

4,000

4,500

5,500

5,000

6,000

9,000

9,500

10,000

C Concealed

C

C

C

C

C

C

C

C

C

C

C

C

C

C

Cremnoceramus deformis dobrogensis (fig. 2, zone 40) Cremnoceramus deformis erectus (fig. 2, zone 39)

Dunveganoceras conditum (fig. 2, zone 18)

Plesiacanthoceras wyomingense (fig. 2, zone 14)

Baculites obtusus (fig. 2, zone 56)

Ardmore Bentonite Bed 

 * ?? * 

 * ?? * 

 * ?? * 

?

Composite Biostratigraphic Outcrop Sections for Upper Cretaceous Formations along a South-trending Transect from Northeastern Wyoming to North-Central Colorado

By

E.A. Merewether, W.A. Cobban, and J.D. Obradovich

2011

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Scientific Investigations Map 3175

 Sheet 1 of 2

U.S. Department of the Interior 

U.S. Geological Survey