Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not 

imply endorsement by the U.S. Government

This map was printed on an electronic plotter directly from digital files. Dimensional calibration may vary 

between electronic plotters and between X and Y directions on the same plotter, and paper may change 

size due to atmospheric conditions; therefore, scale and proportions may not be true on plots of this map.

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225, 

1–888–ASK–USGS

Digital files available at http://pubs.usgs.gov/sir/2012/5041/

Suggested citation: Johnson, R.C., 2012, The systematic geologic mapping program and a 

quadrangle-by-quadrangle analysis of time-stratigraphic relations within oil shale-bearing rocks of the 

Piceance Basin, western Colorado: U.S. Geological Survey Scientific Investigations Report 2012–5041, 

28 p., 2 pls., CD-ROM, also available at http://pubs.usgs.gov/sir/2012/5041/.

Sampled tuff

Sampled tuff

Sampled tuff

8

7

6

5

4

3

2

1

0

Buff

Light

Medium

Dark

Black

Purple

Maroon

Clay

Silt

Very-Fine

Fine

Medium

Coarse

Conglomerate

17

16

15

14

13

12

11

10

9

18

8

7

6

5

4

3

2

1

0

17

16

15

14

13

12

11

10

9

18

19

Hundreds of

feet

2 in pinching tuff

Carbonate ripups, 3 pinching tuffs to 1 in

Some pinching bedding

2.5-4 in tuff, Mahogany marker

Chevron folds

Dolomite beds and nodules

Nonlaminated

Nonlaminated

Nonlaminated

Nonlaminated

Nonlaminated

Nonlaminated

Nonlaminated

Nonlaminated

Nonlaminated

Mostly nonlaminated

Nonlaminated, bright white

Large unusual crystals

Blades of calcite

Fissile, a few dolomite 

beds to 2 in thick

Fissile

Fissile, dolomitic

Fissile

Fissile

Fissile, alternating rich

and lean beds

Thin dolomite beds, 

carbonate ripups

Possible insects

33

50-53

65-72

110

125

405

418

430

395-400

558

550

507

530

495

497

450

565

595

130-131

150-153.5

157

325-326.5

312-314

335-340

261.5-276

170

175

160

223

230

210

252.252.3

260-261.5

365-365.7

370

567

576

583 580

668.5-673

630

698-700

706-709

713-715

727-728

742-743

760-762

635-637

650-651

654-656

665-667

682-687

625

770

810

814

816

825

855

857

880

957

1075

1066

1133

1139

1195

1191

1188

1177

1144-45

1164-65

1241

1250

1345

1410

1419

1423

1432-35

1451-55.5

1485-87

1440

1445

1510

1517

1260-63

1265-66

1322-25

1351-54

1357-59

1361-65

1369-71

1379-80

1388-95

1406-08.5

1347-47.5

1204

1205

1030-1032

1104-1105

1108-1110

1098-1102

1085-1087

1081.5-1083.5

1046-1046.3

884

832

891-893

898-900

910-911.5

913-914.3

927-928

938-939

1585

1610

1620

1635

1650

1653

1670

1690

1705

1730

1745

1770

1810

1855-58

1840

1793

1795

1763-65

1790-91

1639-41

5-in-thick sandy siltstone

Some very lean oil shale

Some very lean oil shale

Hard, dolomitic

White marl

White marl

(New to this report)

South–North Cross Section of the Piceance Basin Showing Variations in Oil and Water Yields from Fischer Assay and Major Water-Bearing Phases in Green River Formation

(Modified from Johnson and others, in press)

By

Ronald C. Johnson

2012

Carbonate and black chert grains

Black chert, secondary 

calcite, pinches out 

100 ft along outcrop 

Mostly light gray

Mostly light gray

Sharp base

Sharp base, persistent

Goniobasis, viviparids

Slightly fissile

Small scour-and-fill channels

A few ostracode 

beds to 1 in thick

15% light mud laminae

4 in thick

2 ft thick

0.7 ft thick

Some sand, carbonate ripups

slightly fissile, thin ostracode beds

10% light mud beds to 1 in

Ostracode beds to 4 in, 

carbonate ripups

one 2-inch dolomite bed

Dol

Dolomite concretions to 

10 in, distinctive cracks

Thin ostracodal ss beds

Fissile, 5% dolomite 

beds to 2 in thick

Rich, fissile, 2 ft thick

Fissile, very few

dolomite beds

1-in-thick tuff in rich oil shale

Slightly fissile

Slightly fissile, dolomitic

Slightly fissile, dolomitic

Moderately fissile

Moderately fissile

Very fissile

Interbedded shale and oil shale

Fissile, dolomite beds to 1 in

Dolomitic

Dolomitic

Dolomitic

Dolomitic

Dolomite concretions to 2 in.

1-in thick dolomite bed at top

Dolomitic, some very

lean oil shale zones

Tuff, 3-4 in thick, locally to 6 in thick

Carbonate ripups near base

Rich beds split by lean bed, carbonate ripups

Carbonate ripups

Nahcolite vugs to 6 in

Hard, dolomitic, buff

dolomite beds to 2 in

Carbonate ripups near top

Carbonate ripups near top

and base well laminated in 

middle

Carbonate ripups to 4 in

Carbonate ripups

Carbonate ripups

Pinching tuff to 2 in 

Pinching tuff 

Rich and moderate rich bands

Three 1-inch rich beds

All well-laminated 

siltstone

2-in tuff 6 in below rich bed

1 in pinching tuff 

Nahcolite vugs to 18 in

Distinctive droopy ledge

Hard, platy marl

Rust-weathering silty sandstone,

no discernible bedding, but 

exposure is poor

No apparent bedding

Mostly indistinct bedding,

bright, volcanic quartz,

5% dark grains

Chaotic 

Interbedded very lean

oil shale and white marl

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2012–5041

Plate 2

Oil shale zone

boundary

Mahogany

R-6

L-5

R-5

L-4

R-4

L-3

R-3

L-2

R-2

L-1

R-1

R-0

Mahogany

R-6

L-5

R-5

L-4

R-4

L-3

R-3

L-2

R-2

L-1

R-1

R-0

B-groove

A-groove

A-groove–

top Bed 44

Mahogany

zone

Top Mahogany bed

Top Bed 44

Garden Gulch Member Parachute Creek Member

500

1,000

1,500

2,000

2,500

3,000

3,200

100 80 60 40 20 0 5 10 15 20 25

100 80 60 40 20 0 5 10 15 20 25

500

1,000

1,500

2,000

2,500

3,000

3,200

500

1,000

1,500

2,000

2,500

2,800

100 80 60 40 20 0

100 80 60 40 20 0

500

1,000

1,500

2,000

2,500

2,800

5 10 15 20 25

5 10 15 20 25

500

1,000

1,500

2,000

2,200

0

100 80 60 40 20 0

100 80 60 40 20 0

500

1,000

1,500

2,000

2,200

0

5 10 15 20 25

5 10 15 20 25

0

100

100

150

50

200

300

400

500

METERS FEET

Vertical scale

R-0 zone

R-1 zone

R-2 zone

R-3 zone

R-4 zone

R-5 zone

L-1 zone

L-2 zone

L-3 zone

L-4 zone

L-5 zone

R-6 zone

L-0 zone

Long Point measured section

Secs. 7, 8, 19, T. 7 S., R. 97 W.

(from Johnson, 1975)

Lower Piceance Creek measured section

Secs. 11, 12, 14, T. 1 N., R. 87 W.

Major water-bearing phases

Index map

R 96 W R 95 W

R 101 W R 100 W R 99 W R 98 W R 97 W R 94 W

T

8

S

T

7

S

R 93 W

T

6

S

T

5

S

T

4

S

T

3

S

T

9

S

R 94 W

R 101 W R 100 W R 99 W R 98 W R 97 W

T

2

S

T

1

S

T

1

N

R 96 W R 95 W

T

2

N

108°30' 108°0'

40°0'

39°30'

EXPLANATION

A'

A

0 3 6 12 MILES

COLORADO

0 5 10 2.5 KILOMETERS

A

A'

14.9 GPT

13.7 GPT

23.3 GPT

24.4 GPT 27.5 GPT

20.6 GPT

2.1 GPT

2.3 GPT

10.5 GPT

8.2 GPT

15.9 GPT

27.2 GPT

41.3 GPT

29 GPT

1.5 GPT

6.3 GPT

3.6 GPT 4.32 GPTW

4.22 GPTW

3.85 GPTW

3.08 GPTW

3.99 GPTW

7.6 GPT 3.33 GPTW

2 GPT 5.72 GPTW

8.1 GPT 3.50 GPTW

2.2 GPT 2.60 GPTW

7 GPT 3.57 GPTW

23.2 GPT 2.73 GPTW

6.3 GPT 1.92 GPTW

1.4 GPT

4.7 GPT

3 GPT

10.3 GPT

6.4 GPT

9.6 GPT

3.6 GPT

10.1 GPT

3.3 GPT

25.5 GPT 2.30 GPTW

1.64 GPTW

3.57 GPTW

3.46 GPTW

3.74 GPTW

4.11 GPTW

5.09 GPTW

3.94 GPTW

3.12 GPTW

4.87 GPTW

4.41 GPTW

6.15 GPTW

10.2 GPT

13.1 GPT

10.1 GPT

18.2 GPT

13.5 GPT

16 GPT

10.9 GPT

21.8 GPT

4.5 GPT

28.4 GPT

5.5 GPT 1.45 GPTW

2.40 GPTW

0.825 GPTW

1.16 GPTW

2.01 GPTW

1.18 GPTW

3.51 GPTW

1.97 GPTW

2.00 GPTW

2.01 GPTW

3.70 GPTW

4.70 GPTW

5.50 GPTW

5.28 GPTW

4.89 GPTW

0.62 GPTW

4.1 GPT

9.6 GPT

6.7 GPT

20.6 GPT

12.6 GPT

16.8 GPT

12.9 GPT

22 GPT

3.6 GPT

25.7 GPT

5.8 GPT

15.9 GPT

3.64 GPTW

2.50 GPTW

2.60 GPTW

1.93 GPTW

1.66 GPTW

2.94 GPTW

1.59 GPTW

2.83 GPTW

0.697 GPTW

3.96 GPTW

6.13 GPTW

7.38 GPTW

4.70 GPTW

4.95 GPTW

7.60 GPTW

4.37 GPTW

2.53 GPTW

3.62 GPTW

3.37 GPTW

3.58 GPTW

2.91 GPTW

0.834 GPTW

4.32 GPTW

2.78 GPTW

3.06 GPTW

2.65 GPTW

3.57 GPTW

5.80 GPTW

6.36 GPTW

8.96 GPTW

9.84 GPTW

8.54 GPTW

3.71 GPTW

7.13 GPTW

5.94 GPTW

6.30 GPTW

5.99GPTW

2.11 GPTW

1.22 GPTW

1.01 GPTW

2.42 GPTW

2.85 GPTW

3.55 GPTW

5.87 GPTW

4.83 GPTW

2.50 GPTW

1.81 GPTW

3.38 GPTW

2.65 GPTW

3.33 GPTW

2.95 GPTW

2.63 GPTW

1.56 GPTW

1.21 GPTW

1.74 GPTW

2.44 GPTW

3.91 GPTW

2.29 GPTW

1.64 GPTW

1.80 GPTW

3.01 GPTW

6.13 GPTW

5.13 GPTW

5.56 GPTW

4.89 GPTW

3.28 GPTW

2.75 GPTW

1.39 GPTW

3.06 GPTW

3.34 GPTW

4.21 GPTW

2.27 GPTW

2.19 GPTW

2.47 GPTW

3.27 GPTW

4.78 GPTW

4.52 GPTW

5.00 GPTW

5.10 GPTW

1.50 GPTW

1.27 GPTW

4.9 GPT

11.6 GPT

6.5 GPT

28.3 GPT

14.1 GPT

20.4 GPT

13.3 GPT

25.5 GPT

5 GPT

27 GPT

13.9 GPT

24.6 GPT

14.6 GPT

31 GPT

22.3 GPT

31.3 GPT

20 GPT

31.5 GPT

31.1 GPT

12 GPT

12 GPT

23.4 GPT

31.6 GPT

22.1 GPT

41.8 GPT

25.3 GPT

41.4 GPT

17.1 GPT

27.9 GPT

8.7 GPT

29.9 GPT

6.1 GPT

6.5 GPT

17 GPT

26.3 GPT

17.8 GPT

33.2 GPT

17.5 GPT

21 GPT

9.9 GPT

7 GPT

22.4 GPT

2.7 GPT

0.4 GPT

About 7 GPT

About 4 GPT

1.2 GPT

11.4 GPT

2.2 GPT

12.1 GPT

About 4 GPT 6.1 GPT 8.2 GPT

14.1 GPT

3.1 GPT

9.2 GPT

8.5 GPT

13.8 GPT

15.7 GPT

12.4 GPT

14.7 GPT

11.8 GPT

6.3 GPT

5.4 GPT

1.8 GPT

11.6 GPT

1.9 GPT 2.48 GPTW

0.1 GPT

About 2 GPT

About 12 GPT

About 6 GPT

About 3 GPT

About 2 GPT

About 14 GPT

About 16 GPT

About 11 GPT

About 11 GPT

About 22 GPT

About 14 GPT

About 14 GPT

About 17 GPT

About 21 GPT

About 7 GPT

Sandstone

Oil shale

Nahcolite

Analcime and clay

Dawsonite

Clay

Dawsonite, analcime, and clay

Dawsonite and clay

Silty dolomitic

 limestone

Dolomitic and calcareous

 siltstone

Algal stromatolites

Dolomitic and calcareous

 claystone

Sandy limestone

Silty sandstone

Silty claystone

Kerogen-rich clay shale

Crossbedded sandstone

Long Point measured section

Correlation datum is the top of the R–4 zone

Limestone

Pelcypod

Climbing ripples

Symmetrical ripples

Horizontal stratification

Internal characteristics

Irregular stratification

Contorted stratification

Claystone, clayshale

or mudstone

Siltstone

Sandstone

LITHOLOGY

Large-scale

lateral 

accretion

10

11

12

Buff to white

Light gray/green

Medium gray/green

Dark gray/green

Black

Purple

Maroon

Pebbles and cobbles

Coarse sand

Medium sand

Fine sand

Very fine sand

Silt

Clay

Covered

 Irregular 

scour surface

 Pinches out

along outcrop

 Calcareous 

concretions

Thins along 

 outcrop

Partially 

covered

UNWEATHERED COLOR LITHOLOGY GRAIN-SIZE RANGE

Lower Piceance Creek measured section

EXPLANATION

Core holes

Hundreds of

feet

Oil shale

Calcareous and/or dolomitic 

rock

Ostracodes

Gastropods

Plant remains

Oolites

Oncolites

Hatched if

olive gray

Ripup clasts

Cross-stratification, 1 to 3 ft high

Cross-stratification, greater than 3 ft high

Fish bones or fish scales

Indistinct laminae

100 80 60 40 20 0

C0195

Arco-Mobil-Equity

Figure Four 31-1

Sec. 31, T. 3 S., R. 98 W. 

500 500

5 10 15 20 25

25.7 GPT

5.8 GPT

3.6 GPT

15.9 GPT

Average oil yield in gallons

per ton of oil shale (GPT)

for each oil shale zone

Average water yield in gallons

per ton of oil shale (GPTW)

for each oil shale zone

3.64 GPTW

3.28 GPTW

1.50 GPTW

1.27 GPTW

Depth in feet

Mahogany ledge outcrop

Base of Parachute Creek Member

Datum (base of Long Point Bed of Green River Formation)

100 80 60 40 20 0 5 10 15 20 25 30

100 80 60 40 20 0 5 10 15 20 25 30

500

1,000

1,500

2,000

2,500

2,700

500

1,000

1,500

2,000

2,500

2,700

100 80 60 40 20 0

100 80 60 40 20 0

C0195

Arco-Mobil-Equity

Figure Four 31-1

Sec. 31, T. 3 S., R. 98 W. 

C0248

Carter Oil Co.

Fawn Creek 2

Sec. 27, T. 3 S., R. 98 W. 

C0158

Shell Oil Co.

Greeno 1-4

Sec. 4, T. 3 S., R. 97 W. 

C0012

Pan American Oil Co.

Peterson 1

Sec. 4, T. 2 S., R. 98 W. 

C0034

U.S. Bureau of Mines/AEC

Colorado 1

Sec. 13, T. 1 N., R. 98 W. 

500

1,000

1,500

2,000

2,500

500

1,000

1,500

2,000

2,500

5 10 15 20 25

5 10 15 20 25

100 80 60 40 20 0 5 10 15 20 25

100 80 60 40 20 0 5 10 15 20 25

C0232

Humble Oil & Refining Co.

East Willow Creek 1

Sec. 28, T. 4 S., R. 97 W.

500

1,000

1,500

2,000

0

500

1,000

1,500

2,000

0

100 80 60 40 20 0 5 10 15 20 25

100 80 60 40 20 0 5 10 15 20 25

C0383

Shell Oil Co.

DH 8 (Pacific Property)

Sec. 14, T. 6 S., R. 98 W.

500

1,000

1,500

2,000

500

1,000

1,500

2,000

C0172

Shell Oil Co.

23X-10

Sec. 10, T. 7 S., R. 97 W.

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton (GPT) Water yield gallons per ton (GPTW) 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton Water yield gallons per ton 

Oil yield gallons per ton (GPT) Water yield gallons per ton (GPTW)

100 80 60 40 20 0 5 10 15 20 25

100 80 60 40 20 0 5 10 15 20 25

500

1,000

1,500

0

500

1,000

1,500

0