Detailed Cross Sections of the Eocene Green River 

Formation along the North and East Margins of the 

Piceance Basin, Western Colorado, Using Measured 

Sections and Drill Hole Information

Scientific Investigations Map 3276

U.S. Department of the Interior

U.S. Geological Survey
Front cover. Green River Formation at the mouth of Yellow Creek in the northern Piceance Basin. 

Yellow Creek is one of the measured sections on sheet 1. Photograph by R.C. Johnson, 2007.
Detailed Cross Sections of the Eocene 

Green River Formation along the North 

and East Margins of the Piceance Basin, 

Western Colorado, Using Measured 

Sections and Drill Hole Information

By Ronald C. Johnson

Pamphlet to accompany 

Scientific Investigations Map 3276

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Johnson, R.C., 2014, Detailed cross sections of the Eocene Green River Formation along the north and east margins 

of the Piceance Basin, western Colorado, using measured sections and drill hole information: U.S. Geological Survey 

Scientific Investigations Map 3276, 11 p., 2 sheets, http://dx.doi.org/10.3133/sim3276.

ISSN 2329-132X (online)
iii

Contents

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

Stratigraphic Subdivisions of the Green River Formation.......................................................................1

Constructing the Detailed Cross Sections.................................................................................................3

References Cited..........................................................................................................................................10

Figures

1. Map showing extent of Uinta, Piceance, and Greater Green River Basins and 

 approximate extent of oil shale in the Green River Formation..............................................2

2. Cross section showing oil-yield histograms, members of the Eocene Green River 

 Formation, correlation of rich- and lean-oil shale zones, and stages in the evolution 

 of Lake Uinta..................................................................................................................................4

3. East-west cross section through the Piceance Basin, the Douglas Creek arch, 

 and the eastern part of the Uinta Basin showing member subdivisions and stages 

 of Lake Uinta..................................................................................................................................6

4. North-south cross section through the Piceance Basin, northwestern Colorado, 

 showing member subdivisions and stages of Lake Uinta......................................................8

Sheets

1. Cross section A–A’ of the Eocene Green River Formation along the north margin 

 of the Piceance Basin, western Colorado........................................................................... link

2. Cross section B–B’ of the Eocene Green River Formation along the east margin 

 of the Piceance Basin, western Colorado........................................................................... link
iv

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Volume

gallon (gal) 3.785 liter (L) 

Mass

ton, short (2,000 lb) 0.9072 megagram (Mg) 

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Volume

liter (L) 0.2642 gallon (gal)

Mass

megagram (Mg) 1.102 ton, short (2,000 lb)

Altitude, as used in this report, refers to distance above the vertical datum.

SI to Inch/Pound
Introduction

The Eocene Green River Formation was deposited in 

Lake Uinta, a long-lived saline lake that covered much of the 

Piceance Basin in northwestern Colorado and the Uinta Basin 

in eastern Utah (fig. 1). This report presents 2 detailed cross 

sections of the Eocene Green River Formation in the Piceance 

Basin constructed from 8 detailed measured sections, 14 core 

holes, and 2 rotary holes. The cross sections extend across the 

northern and eastern margins of the basin and are intended to 

aid in correlating between surface sections and the nearby subsurface (fig. 1). Detailed measured sections new to this report 

are: (1) Smith Gulch, (2) Hay Gulch, and (3) Rio Blanco. 

Detailed measured sections that were previously published 

include: (1) Fletcher Gulch (Johnson and others, 1988), (2) 

Anvil Points (Self and others, 2010), (3) Spring Creek (Self 

and others, 2010), (4) Yellow Creek (Self and others, 2010), 

and (5) Lower Piceance Creek (Johnson, 2012). 

Core holes and rotary holes used include oil-yield histograms from Fischer assay analysis, a standardized laboratory 

test for determining the oil yield from oil shale that has been 

almost universally used to determine oil yields for Green 

River Formation oil shales (Stanfield and Frost, 1949; ASTM, 

1984). In addition, all measured sections except Anvil Points 

and Smith Gulch include estimates of oil yield based on 

appearance and density. According to Cashion (1967, p. 25) 

estimated oil yields from surface samples can give moderately 

accurate results when sampling is done by an experienced 

investigator, but should only be used if data are not available. 

These estimates are presented mainly as an aid to correlating 

oil shale units between surface sections and nearby drill holes, 

as sequences of oil shale beds have similar richness patterns. 

Correlation of oil shale units in both the Piceance Basin 

and the Uinta Basin to the west uses a comprehensive timestratigraphic system based on alternating rich and lean oil 

shale zones. This system, originally proposed by Cashion 

and Donnell (1972), has been used to subdivide the oil shale 

interval of the Green River Formation throughout much of 

both basins (fig. 2) and was recently used in the assessment 

of in-place oil shale in the two basins (Johnson and others, 

2010a; b). The system assumes that rich- and lean-oil shale 

units were deposited during alternating periods of high- and 

low-organic productivity, respectively, that occurred simultaneously across the entire area of Lake Uinta. 

The sequence of rich- and lean-oil shale zones, deposited 

in offshore areas of Lake Uinta, grade into marginal lacustrine 

clastic and carbonate sequences toward the lake margins. One 

of the purposes of this study is to better correlate these rich 

and lean zones into their largely marginal lacustrine equivalents. This was previously attempted by Johnson and others 

(1988) for the western margin of the Piceance Basin and the 

eastern margin of the Uinta Basin. Johnson (2012) used the 

1988 study, along with early versions of the detailed cross sections presented here, to correlate each of the marginal lacustrine units mapped on published quadrangle maps in the basin 

into this time-stratigraphic system of rich and lean zones. 

Thus, this publication provides additional supporting data to 

that used in Johnson’s 2012 study.

Stratigraphic Subdivisions of the Green 

River Formation.

The Green River Formation of the Piceance Basin was 

deposited in the Eocene Lake Uinta that formed when two 

much smaller fresh-water lakes, one in each the Piceance 

and Uinta Basins, expanded and merged into one large saline 

lake. Lake Uinta remained a single unbroken lake across both 

basins and the intervening Douglas Creek arch throughout 

most of its history, and as a result most stratigraphic units can 

be recognized in both basins (figs. 2 and 3). Several members 

of the Green River Formation are recognized, although the 

member designations have not always been applied consistently (figs. 3 and 4). For a recent compilation of how member 

names have been applied, see Johnson (2012). In the oil shale 

section deposited in the offshore areas of the lake, the name 

Garden Gulch Member is generally applied to the illitic oil 

shales that were deposited in the early history of Lake Uinta, 

Detailed Cross Sections of the Eocene Green River 

Formation along the North and East Margins of the 

Piceance Basin, Western Colorado Using Measured 

Sections and Drill Hole Information

By Ronald C. Johnson
2 Cross Sections of the Eocene Green River Formation along the North and East Margins of the Piceance Basin 

Figure 1. Map showing extent of Uinta, Piceance, and Greater Green River Basins and approximate extent of oil shale 

in the Green River Formation.

Oil shale-bearing rocks deposited in Eocene Lake Gosiute

EXPLANATION

Oil shale-bearing rocks deposited in Eocene Lake Uinta 

Uinta-Piceance Province boundary

Southwest Wyoming Province boundary

0 50 100 KILOMETERS

0 50 100 MILES

Green River

Colorado River

White River

Yampa 

Green River

Utah

Lake

Great

Salt

Lake

Colorado

River

River

WYOMING

UTAH

COLORADO

Hoback Basin

Washakie Basin

Piceance Basin

Uinta Basin 

Sand Wash Basin

Great Divide Basin

Southwestern Wyoming

Province boundary

(Greater Green River Basin)

Uinta-Piceance

Province boundary

G r e a t e r

G r e e n

R i v e r

Basin

Rock

Springs Uplift

Wampsutter 

Cherokee Ridge

Sandy Bend Arch

White River

Uplift

San

Rafael

Swell

Uinta uplift

Wyoming thrust belt

Wind

River

Uplift

Sierra

Madre

Uncompahgre

Uplift

Sawatch

Uplift

Sevier orogenic

belt

Park

Range

Axial arch

Arch

Rawlins

Uplift

82

789

70

6

50

70

40

30

26 20

89

25

80

191

6

30

50

89

40

15

191

15

15

84

80

30

191

287

189

91

189

189

112° 111° 110° 109° 108° 107°

43°

42°

41°

40°

39°

Eagle

Glenwood

Springs

Castledale

Aspen

Grand

Junction

Kemmerer

Moab

Gunnison

Montrose

Pinedale Soda

Springs

Delta

Lander Casper

Paris

Vernal

Preston

Logan

Rawlins

Green

River

Ogden Evanston

Coalville

Manila

Price

Provo

Craig Steamboat

Springs

Duchesne

Nephi

Meeker

Manti

Green River

Rock

Springs

Rangely

Salt Lake

City

Location of 

figure 2

Douglas Creek arch

A

A' B

B'

IDAHO
Constructing the Detailed Cross Sections 3

and the name Parachute Creek Member is applied to the 

dolomitic oil shales deposited later. The name Douglas Creek 

Member is applied to marginal lacustrine rocks along the west 

and southwest margins, and the name Anvil Points Member is 

applied to marginal lacustrine rocks along the east and southeast margins of the Piceance Basin. The names Garden Gulch 

Member, Parachute Creek Member, and Douglas Creek Member were first used by Bradley (1931), whereas Donnell (1953) 

was the first to use the name Anvil Points Member. The name 

Uinta Formation is applied to a sequence of sandstones and 

siltstones containing abundant volcanic debris that interfinger 

with the upper part of the Green River Formation (Cashion 

and Donnell, 1974). 

Cashion and Donnell (1972) recognized that the entire 

oil shale interval in the Piceance and Uinta Basins could be 

subdivided into a series of oil-rich zones (R–1 through R–6) 

and oil-lean zones (L–1 through L–5) (fig. 2). Later, the names 

R–0 and L–0 zones were applied to the lowest oil shale units 

in the Green River Formation that was deposited just after the 

Long Point transgression (fig. 2) (see, for example, Johnson 

and others, 1988). Previously named oil shale units above the 

R–6 zone are, in ascending order: B–groove, Mahogany zone, 

and A–groove. The oil shale interval above A–groove was not 

named by Cashion and Donnell (1972), but they traced several 

oil shale marker beds through that interval. Donnell (2008) 

correlated 44 individual oil shale beds above A–groove across 

much of the Piceance Basin and eastern part of the Uinta 

Basin (fig. 2). All of these oil shale beds and zones appear to 

closely represent time-stratigraphic units that reflect changing rates of organic matter production and preservation that 

occurred simultaneously throughout Lake Uinta. 

In the offshore areas of the lake, the boundary between 

clay-rich oil shale and carbonate-rich oil shale is near the 

base of the R–2 oil shale zone (fig. 2), however, the boundary between the Garden Gulch and Parachute Creek Members 

mapped in outcrop around the margins of the basin commonly 

does not correspond to that stratigraphic position. Johnson 

(2012) discusses the many reasons for these discrepancies, and 

it is suggested that the reader consult that report.

Constructing the Detailed Cross 

Sections

The individual measured sections include columns for 

color, lithology, grain size, bedding features, and in most 

cases, estimated oil yield based on the appearance and density 

of the oil shale in outcrop. The strata exposed at Anvil Points 

and Smith Gulch contain little oil shale, and estimates of oil 

yield in these two sections were not made. Datum for the two 

detailed cross sections is the base of the Long Point Bed of 

the Green River Formation (figs. 3 and 4), the basal transgressive bed that formed Lake Uinta. The detailed cross sections 

include the boundaries of stratigraphic units from published 

maps in the vicinity of each measured section (see Johnson, 

2012) and correlate stratigraphic units to the rich- and leanzone stratigraphy when it can be determined. Boundaries 

between various lithologic units shown may or may not correspond to the mapped outcrop boundaries of stratigraphic units 

or boundaries between the rich and lean zone.
4 Constructing the Detailed Cross Sections 5 Cross Sections of the Eocene Green River Formation along the North and East Margins of the Piceance Basin 

Figure 2. Cross section showing 

oil-yield histograms, members of 

the Eocene Green River Formation, 

correlation of rich- and lean-oil shale 

zones, and stages in the evolution of 

Lake Uinta.

0 20 40 60 80 100

C0195

Arco-Mobil-Equity,

Figure Four 31–1 

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

500

1,000

1,500

2,000

2,500

500

1,500

0

1,000

0 20 40 60 80 100

0 20 40 60 80 100

C0172

Shell Oil Co., 23X–10,

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

0 20 40 60 80 100

0 20 40 60 80 100

0 20 40 60 80

500

1,000

1,500

2,000

0

Mahogany bed

0 20 40 60 80 100

0 20 40 60 80 100

C0158

Shell Oil Co.

Greeno 1–4

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

TD 2,710 ft

500

1,000

1,500

2,000

2,500

3,000

100

Top Bed 44-

top A–groove

A–groove

Mahogany

zone

B–groove

R–6 zone

L–5 zone

R–5 zone

L–4 zone

R–4 zone

L–3 zone

R–3 zone

L–2 zone

R–2 zone

L–1 zone

R–1 zone

L–0 zone

R–0 zone

Stratigraphic nomenclature for 

oil shale zones from

Donnell and Blair (1970),

Cashion and Donnell (1972), 

Donnell (2008);

stages from Johnson (1985) Garden Gulch Member Parachute Creek Member Green River Formation

Oil yield (gallons per ton)

Oil yield (gallons per ton)

Oil yield (gallons per ton)

Oil yield (gallons per ton)

 U–53

Skyline Oil Co., Watson 1A

 Sec. 5, T. 11 S., R. 25 E.

Base Porcupine

Creek Tufftop Bed 44

Porcupine Cr. Tuff

Top bed 76-top

Porcupine Creek

Tuff

Stage 1 Stage 2 Stage 3 Stage 4 Stage 5

Top Bed 44-

top A–groove

A–groove

Mahogany

zone

B–groove

R–6 zone

L–5 zone

R–5 zone

L–4 zone

R–4 zone

L–3 zone

R–3 zone

L–2 zone

R–2 zone

L–1 zone

R–1 zone

L–0 zone

R–0 zone

Garden Gulch Member Parachute Creek Member

Green River Formation

Stage 1 Stage 2 Stage 3 Stage 4

Datum

Stage 5

Volcaniclastic rocks 

Mostly oil shale with some volcaniclastic material

Top of 

Long Point Bed

Sandstone, siltstone and mudstone

Carbonate-rich oil shale (>10 gallons per ton) 

Carbonate-rich oil shale (<10 gallons per ton) 

Clay-rich oil shale (>10 gallons per ton) 

Clay-rich oil shale (<10 gallons per ton) 

EXPLANATION
6 Constructing the Detailed Cross Sections 7 Cross Sections of the Eocene Green River Formation along the North and East Margins of the Piceance Basin

Figure 3. East-west cross section 

through the Piceance Basin, the Douglas 

Creek arch, and the eastern part of the 

Uinta Basin showing member subdivisions 

and stages of Lake Uinta.

Stage 2

Stage 1

Stage 3

Stage 4

Stage 4

R–0 and L–0 zones

White River Uplift

Douglas Creek

Member

Wasatch

Formation

Green River

Formation

Black Sulphur Tongue

of Green River Formation

Tongue of

Uinta Formation

Intersection with

cross section in figure 4

Base of

R–4 rich

oil shale

zone

Parachute Creek

Member of Green

River Formation

Garden Gulch

Member

Cow Ridge

Member of

Green River

Formation

Tongue of

Uinta Formation

Tongue of

Uinta Formation

Thirteenmile Creek

Tongue of Green

River Formation

Black Sulphur Tongue

of Green River Formation

Tongue of Uinta

Formation

Top of Mahogany

oil shale zone

Base of R–2 rich

oil shale zone

Anvil Points

Member

Datum is base of Long

Point Bed of Green

River Formation

Wasatch

Formation

Fort Union

Formation

Fort

Union

Formation

WasatchFort Union

Formation

contact

UTAH COLORADO

Douglas Creek Arch

Piceance Basin

Uinta Basin

West

East

Mahogany zone

Cretaceous rocks

Cretaceous rocks

Cretaceous rocks

R–1 and L–1 zones

R–2 through

L–3 zones

B-marker

I-marker

Land

surface

Land

surface

FEET METERS

2,000

1,000

0 0

600

400

200

0

0 10 20 30 40 KILOMETERS

10 20 30 MILES

Volcaniclastic rocks 

Mostly oil shale with some volcaniclastic material

Carbonate-rich oil shale (>10 gallons per ton) 

Carbonate-rich oil shale (<10 gallons per ton) 

Clay-rich oil shale (>10 gallons per ton) 

Clay-rich oil shale (<10 gallons per ton) 

Fresh-water lacustrine oil shale

Sandstone-rich marginal lacustrine

Carbonate-rich marginal lacustrine

Marginal fresh-water lacustrine

Paludal

Fluvial and alluvial

EXPLANATION

Location Map

Piceance

Basin

W

E
8 Cross Sections of the Eocene Green River Formation along the North and East Margins of the Piceance Basin Constructing the Detailed Cross Sections 9

R–4 zone

Top of Mahogany

oil shale zone

Long Point

Bed

Top of 

Cretaceous

South

North

R–0 and L–0 zones

R–1 zone

L–1 zone

R–4, L–4, 

R–5 zones

L–5 zone

R–6 zone and 

R–6 zone and 

B–groove

B–groove

Mahogany zone

Uinta 

Formation

Uinta 

Formation

 Wasatch 

Formation

 Wasatch 

Formation

Wasatch Formation

Fort

Union

Formation

Cow Ridge Member,

Green River Formation

Parachute

Creek 

Member

Douglas

Creek 

Member Garden Gulch Member

Green

River

Formation

Parachute

Creek Mbr.

Top of Bed 44

of Donnell (2008)

Intersection with 

cross section A–A’ Thirteenmile Creek Tongue

of Green River Formation

Stage 1

Stage 2

Stage 3

Stage 4

Stage 5

R–4 zone

B–marker

C–marker

D–marker

I–marker

L–5 zone

Mahogany zone

R–5 and 

L–4 zones

R–5 and 

L–4 zones

R–1 and L–1 zones

R–0 and L–0 zones

R–2 through

L–3 zones

Volcaniclastic rocks 

Mostly oil shale with some volcaniclastic material

Carbonate-rich oil shale (>10 gallons per ton) 

Carbonate-rich oil shale (<10 gallons per ton) 

Clay-rich oil shale (>10 gallons per ton) 

Clay-rich oil shale (<10 gallons per ton) 

Fresh-water lacustrine oil shale

Sandstone-rich marginal lacustrine

Carbonate-rich marginal lacustrine

Marginal fresh-water lacustrine

Paludal

Major nahcolite and halite zones

Fluvial and alluvial

Explanation

0 20,000 60,000 FEET

10 KILOMETERS

0

500

1,000

1,500

400

200

FEET METERS

VERTICAL EXAGGERATION X 40

Index Map

Piceance

Basin

N

S

40,000

Figure 4. North-south cross 

section through the Piceance Basin, 

northwestern Colorado, showing 

member subdivisions and stages of 

Lake Uinta.
10 Cross Sections of the Eocene Green River Formation along the North and East Margins of the Piceance Basin

References Cited

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Designation D 388–80, Standard test method for oil from oil 

shale: Annual Book of ASTM Standards, 1984, p. 513–525.

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of the Green River Formation of Colorado and Utah: 

U.S. Geological Survey Professional Paper 168, 58 p.

Cashion, W.B., 1967, Geology and fuel resources of the Green 

River Formation southeastern Uinta Basin, Utah and Colorado: U.S. Geological Survey Professional Paper 548, 48 p.

Cashion, W.B., 1973, Geologic and structure map of the Grand 

Junction quadrangle, Colorado and Utah: U.S. Geological 

Survey Miscellaneous Investigations Series Map I–736, 

scale 1:250,000.

Cashion, W.B., and Donnell, J.R., 1972, Chart showing 

correlation of selected key units in the organic-rich 

sequence of the Green River Formation, Piceance Creek 

Basin, Colorado, and Uinta Basin, Utah: U.S. Geological 

Survey Oil and Gas Investigations Chart OC–65.

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Piceance Creek Basin, Colorado, and Eastern Uinta Basin, 

Utah: U.S. Geological Survey Bulletin 1394–G, 9 p.

Chancellor, R.E., Barksdale, W.L., and Dolezal, George, Jr., 

1974, Occurrence of oil and gas in the Tertiary system, Rio 

Blanco unit, Rio Blanco County, Colorado, in Murray, D.K., 

ed., Guidebook to the Energy Resources of the Piceance 

Creek Basin, Colorado: Rocky Mountain Association of 

Geologists, 25th Field Conference, p. 225–233.

Donnell, J.R., 1953, Columnar section of rocks exposed 

between Rifle and DeBeque Canyon, Colorado: Rocky 

Mountain Association of Geologists Field Conference 

Guidebook to Northwestern Colorado, p. 14.

Donnell, J.R., 2008, Intertonguing of the lower part of the 

Uinta Formation with the upper part of the Green River 

Formation in the Piceance Creek Basin during the late 

stages of Lake Uinta, chap. 7 of U.S. Geological Survey 

Oil Shale Assessment team, eds., Oil Shale Resources of the 

Uinta Basin, Utah and Colorado: U.S. Geological Survey 

Scientific Investigation Report SIR 2008–5237, 25 p., http://

pubs.usgs.gov/dds/dds-069/dds-069-bb/REPORTS/69_BB_

CH_7.pdf.

Donnell, J.R., and Blair, R.W., 1970, Resource appraisal of 

three rich oil-shale zones in the Green River Formation, 

Piceance Creek Basin, Colorado: Colorado School of Mines 

Quarterly, v. 65, p. 73–87.

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of the Calamity Ridge quadrangle, Rio Blanco County, 

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Studies Map MF–690, scale: 1:24,000, http://pubs.er.usgs.

gov/usgspubs/mf/mf1690.

Hail, W.J., Jr., 1974, Geologic map of the Rough Gulch quadrangle, Rio Blanco and Moffat Counties, Colorado: U.S. 

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scale: 1:24,000, http://pubs.er.usgs.gov/usgspubs/gq/

gq1195.

Hail, W.J., Jr., 1988, Geologic map of the Barcus Creek SE 

quadrangle, Rio Blanco County, Colorado: U.S. Geological 

Survey Geologic Quadrangle GQ–1613, scale: 1:24,000, 

http://pubs.er.usgs.gov/usgspubs/gq/gq1613.

Johnson, R.C., 1984, New names for units in the lower part 

of the Green River Formation, Piceance Creek Basin, 

Colorado: U.S. Geological Survey Bulletin 1529–I, 20 p., 

1 pl.

Johnson, R.C., 1985, Early Cenozoic history of the Uinta and 

Piceance Creek Basins, Utah and Colorado, with special 

reference to the development of Eocene Lake Uinta, in

Flores, R.M., and Kaplan, S.S., eds, Cenozoic Paleogeography of the West-Central United States, Rocky Mountain 

Paleography Symposium 3: The Rocky Mountain Section, 

Society of Economic Paleontologists and Mineralogists 

p. 247–276.

Johnson, R.C., 2012, The systematic geologic mapping 

program and a quadrangle-by-quadrangle analysis of the 

time-stratigraphic relations within the oil shale-bearing 

rocks of the Piceance Basin, western Colorado: U.S. Geological Survey Scientific Investigations Report SIR 2012–

5041, 28 p., http://pubs.usgs.gov/sir/2012/5041/.

Johnson, R.C., Nichols, D.J., and Hanley, J.H., 1988, Stratigraphic sections of Lower Tertiary strata and charts showing 

palynomorph and mollusc assemblages, Douglas Creek 

arch area, Colorado and Utah: U.S. Geological Survey 

Miscellaneous Field Investigations Map MF–1997, two 

large foldouts.

Johnson, R.C., and Roberts, L.N., 2003, Depths to selected 

stratigraphic horizons in oil and gas wells for Upper 

Cretaceous and Lower Tertiary strata of the Uinta Basin, 

Utah, chap. 13, of U.S. Geological Survey Uinta-Piceance 

Assessment Team, eds., Petroleum systems and geologic 

assessment of oil and gas in the Uinta-Piceance Province, 

Utah and Colorado: U.S. Geological Survey Digital Data 

Series 69–B, chap. 13, 30 p.
References Cited 11

Johnson, R.C., Mercier, T.J., Brownfield, M.E., Pantea, M.P., 

and Self, J.G., 2010a, An assessment of in-place oil shale 

resources of the Green River Formation, Piceance Basin, 

Colorado, chap. 1 of U.S. Geological Survey Oil Shale 

Assessment Team, eds., Oil Shale and Nahcolite Resources 

of the Piceance Basin, Colorado: U.S. Geological Survey 

Digital Data Series 69–Y, 187 p., http://pubs.usgs.gov/dds/

dds-069/dds-069-y/REPORTS/69_Y_CH_1.pdf.

Johnson, R.C., Mercier, T.J., Brownfield, M.E., and Self, 

J.G., 2010b, Assessment of in-place oil shale resources of 

the Eocene Green River Formation, Uinta Basin, Utah and 

Colorado, chap. 1 of U.S. Geological Survey Oil Shale 

Assessment Team, eds., Oil Shale Resources of the Uinta 

Basin, Utah and Colorado: U.S. Geological Survey Digital 

Data Series 69–BB, 153 p., http://pubs.usgs.gov/dds/dds069/dds-069-bb/REPORTS/69_BB_CH_1.pdf.

Love, J.D., and Christiansen, A.C., 1985, Geologic map 

of Wyoming: U.S. Geological Survey and the Geological 

Survey of Wyoming, scale 1:500,000.

O’Sullivan, R.B., 1985, Preliminary geologic map of the Rio 

Blanco quadrangle, Rio Blanco and Garfield Counties, 

Colorado: U.S. Geological Survey Miscellaneous Field 

Studies Map MF–1816, scale 1:24,000, http://pubs.er.usgs.

gov/usgspubs/mf/mf1816.

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Johnson—Cross Sections of the Eocene Green River Formation along the North and East Margins of the Piceance Basin—Scientific Investigations Map 3276

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3276