Chapter 1

Assessment of In-Place Oil Shale 

Resources of the Eocene Green River 

Formation, Greater Green River Basin, 

Wyoming, Colorado, and Utah

By Ronald C. Johnson, Tracey J. Mercier, Robert T. Ryder, Michael E. 

Brownfield, and Jesse G. Self

Chapter 1 of 6

Oil Shale Resources of the Eocene Green River Formation, 

Greater Green River Basin, Wyoming, Colorado, and Utah

By U.S. Geological Survey Oil Shale Assessment Team

U.S. Geological Survey Digital Data Series DDS–69–DD

U.S. Department of the Interior

U.S. Geological Survey

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Volume Title Page
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2011

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Suggested citation:

Johnson, R.C., Mercier, T.J., Ryder, R.T., Brownfield, M.E., and Self, J.G., 2011, Assessment of in-place oil shale 

resources of the Eocene Green River Formation, Greater Green River Basin, Wyoming, Colorado, and Utah, in U.S. 

Geological Survey Oil Shale Assessment Team, ed., Oil shale resources of the Eocene Green River Formation, Greater 

Green River Basin, Wyoming, Colorado, and Utah: U.S. Geological Survey Digital Data Series DDS–69–DD, chap. 1, 

63 p., 1 plate.
iii

Contents

Abstract...........................................................................................................................................................1

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

Previous Assessments of the Greater Green River Basin .....................................................................4

Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin .....5

Ramsey Ranch Member of the Wasatch Formation ......................................................................6

Lumen Tongue of Green River Formation ..........................................................................................8

Niland Tongue of Wasatch Formation ...............................................................................................8

Tipton Shale Member of the Green River Formation ......................................................................8

Wilkins Peak Member of the Green River Formation ...................................................................13

Laney Member of the Green River Formation ................................................................................18

Factors Affecting the Precision of Oil-Yield Measurements ...............................................................26

Determining the Volume of Oil in a Given Volume of Rock...........................................................26

Anomalously High Oil-Yield Values from Cuttings .........................................................................27

Discrepancies Between Geophysical Logs and Cuttings Data ..................................................27

Broken Core and Missing Intervals .................................................................................................27

Zero Values on Assay Tables ............................................................................................................33

Problems Related to Saline Minerals ..............................................................................................33

Methods Used to Generate Isopach Maps and Isoresource Maps ...................................................35

Assessment Results ....................................................................................................................................36

Tipton Shale Member .........................................................................................................................36

Wilkins Peak Member ........................................................................................................................43

LaClede Bed of the Laney Member .................................................................................................50

Discussion.....................................................................................................................................................50

References cited..........................................................................................................................................60

Plate

 1. Isoresource map for the Piceance Creek Basin showing total barrels of 

 oil in each township for all the assessed oil shale units combined ............................... link

Figures

 1. Map showing extent of Uinta-Piceance and Greater Green River structural 

and sedimentary basin .................................................................................................................2

 2. Map showing major structural elements for the Greater Green River 

Basin, Wyoming, Colorado, and Utah ........................................................................................3

 3. Generalized east-west cross section of Eocene rocks in the Greater 

Green River Basin .........................................................................................................................6

 4. Paleogeographic map of the Ramsey Ranch Member of the Wasatch Formation ...........7

 5. Paleogeographic map of the Lumen Tongue of the Green River Formation .......................9

 6. Paleogeographic map of the Niland Tongue of the Wasatch Formation ..........................10
iv

 7. Paleogeographic map of the Scheggs Bed of the Tipton Shale Member of 
v

Tables

 1. Original volume-weight-oil yield relationships of Green River Formation oil shale ........28

 2. Recalculated volume-weight-oil yield relationships for Green River Formation 

oil shale ........................................................................................................................................30

 3. In-place oil resources, in barrels of oil, in the Green River Formation, 

Greater Green River Basin, Wyoming .....................................................................................37
Abstract

An assessment of in-place oil shale resources of the 

Eocene Green River Formation, regardless of grade, was 

conducted in the Greater Green River Basin of Wyoming, 

Colorado, and Utah. However, no attempt was made to 

estimate the amount of oil that is economically recoverable, 

largely because there has not yet been an economic method 

developed to recover the oil. The Radial Basis Function 

method was used to generate the isopach maps, resource 

maps, and resource estimates. The three units assessed here 

are, in ascending order, the Tipton Shale Member, the Wilkins 

Peak Member, and the LaClede Bed of the Laney Member. 

Four maps were generated for each zone: (1) isopach map, 

(2) isoresource map showing variations in gallons per ton, (3) 

isoresource map showing variations in barrels per acre, and 

(4) isoresource map showing total amount of in-place oil in 

each 6-mile by 6-mile township. Total in-place resources for 

the three assessed units are: (1) Tipton Shale Member, 362,816 

million barrels of oil (MMBO), (2) Wilkins Peak Member, 

704,991 MMBO, and (3) LaClede Bed of the Laney Member, 

377,184 MMBO, for a total of 1.44 trillion barrels of oil in 

place. This compares with estimated in-place resources for 

the Piceance Basin of Colorado of 1.53 trillion barrels and 

estimated in-place resources for the Uinta Basin of Utah and 

Colorado of 1.32 trillion barrels. The assessed area of the 

Greater Green River Basin–about 5,500 mi2

, however, is about 

1.4 times larger than the assessed area of the Uinta Basin 

(3,834 mi2

) and more than four times larger than the assessed 

area of the Piceance Basin (1,335 mi2

).

Introduction

This report presents an assessment of all in-place oil 

shale resources of the Eocene Green River Formation, regardless of grade, in the Greater Green River Basin of southwestern Wyoming, northwestern Colorado, and northeastern Utah 

(figs. 1 and 2). Green River oil shale is also present in the 

Piceance Basin of western Colorado and the Uinta Basin of 

eastern Utah and western Colorado (fig. 1), and the results of 

these assessments are published separately (Johnson and others, 2010a, b). 

A considerable amount of oil-yield data was collected 

subsequent to the previous assessments, making it possible 

to better assess in-place resources. Furthermore, there have 

been major advances in computational power and computer 

programming since the last assessments were published, and 

these were used to the extent possible for our assessment. All 

of the Fischer assay data, location data, and tops file were 

assembled into one Access database (Mercier and others, this 

report, chapter 6) similar to the one recently published for the 

Piceance Basin (Mercier, 2010). Due to the number of data 

records and the complexity of the spatial data involved in the 

assessment, Microsoft Access database management software 

and ESRI’s ArcGIS software were used to combine, store, and 

analyze the raw data. The ability to create custom forms in 

Access was a crucial element in the assessment methodology, 

as it allowed us to write Visual Basic scripts and SQL statements to filter subsets of the data and perform the necessary 

calculations using Access form controls. The public benefits 

from this process, as the original forms used to calculate 

resources also serve as the end-user interface to view the 

raw data in a more simplified and meaningful manner. After 

resources were calculated for each core hole, the resultant 

Access tables were linked seamlessly with ESRI’s ArcGIS 

software to model, extrapolate, and quantify the data spatially. 

The end product is a large database of tables (spreadsheets), 

forms to view the data, and a series of maps quantifying the 

results of those calculations. For a complete description of the 

process used for our resource assessment, see Mercier and others (chapter 6, this report).

In our assessment, we tried two extrapolation methods 

for spatial interpolation that are easier for a non-statistician 

to apply: the Radial Basis Function (RBF) method, and the 

Inverse Distance Weighted (IDW) method. Both methods gave 

similar results and we ultimately decided on the RBF method, 

which was recently demonstrated to give comparable results to 

those obtained from kriging (Rusu and Rusu, 2006). 

Assessment of In-Place Oil Shale Resources in the 

Eocene Green River Formation, Greater Green River Basin, 

Wyoming, Colorado, and Utah

By Ronald C. Johnson, Tracey J. Mercier, Robert T. Ryder, Michael E. Brownfield, and Jesse G. Self
2 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

112° 111° 110° 109° 108° 107° 106°

40°

39°

38°

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43°

Piceance

Basin

Sand Wash

Basin

Washakie

Basin

Great Divide Basin

Uinta Basin

COLORADO

UTAH

WYOMING

IDAHO

Provo

Utah

Lake

Vernal

Price

Rangely

Grand

Junction

Green River

Great Salt Lake

SALT LAKE CITY

Yampa River

Green River

White

White

Colorado River

ColoradoRiver

River

River

River

Meeker

Rifle

Craig

Baggs

Rawlins

Rock Springs

Green River Evanston

Green River

Basin

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Basin

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River

Yampa

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Gunnison

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789

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33

139

GREATER GREEN RIVER BASIN

(SOUTHWESTERN WYOMING

PROVINCE BOUNDARY)

UINTA-PICEANCE

PROVINCE BOUNDARY

EXPLANATION

U.S. Geological Survey

 Oil and Gas Province

Oil shale-bearing rocks

City or town

Major highway or road

Index map

Enlarged area

Figure 1. Extent of Uinta-Piceance and Greater Green River structural and sedimentary basin.
Introduction 3

Anticlinal axis

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 of Mesaverde Group

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111° 110° 109° 108° 107°

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UTAH 

WYOMING

COLORADO

CARBON

GRAND

GARFIELD

FREMONT

DAGGETT

EAGLE

JACKSON

LINCOLN

MOFFAT

NATRONA

RIO BLANCO

ROUTT

SUBLETTE

SUMMIT

SWEETWATER

TETON

UINTA

UINTAH DUCHESNE

SANDY BEND

ARCH

Hoback

Basin

Sand Wash

Basin

Washakie

Basin

Great Divide

Basin

River

Basin

CHEROKEE RIDGE

WAMSUTTER ARCH

MOXA ARCH

ROCK SPRINGS UPLIFT

Green

Outcrop of Mesaverde Group

Greater Green River Basin

 (Southwestern Wyoming Province)

Wyoming thrust belt

GRANITE

MOUNTAINS

RAWLINS

UPLIFT

SIERRA 

MADRE

PARK

RANGE

UINTA

MOUNTAINS

AXIAL

BASIN

UPLIFT

WIND

RIVER

RANGE

La Barge

platform

PINEDALE

ANTICLINE

T

13

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R 115 W R 114 W R 113 W R 112 W R 111 W R 110 W R 109 W R 108 W R 107 W R 106 W R 105 W R 104 W R 103 W R 102 W R 101 W R 100 W R 99 W R 98 W R 97 W R 96 W R 95 W R 94 W R 93 W R 92 W R 91 W R 90 W R89 W

T 12 N

EXPLANATION

Drillhole used in cross section

Line of cross section

County line

–6000

Figure 20

Figure 12

Plate 1

Surface Section

Figure 2. Major structural elements for the Greater Green River Basin, Wyoming, Colorado, and Utah.
4 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

This overall effort has been hampered by difficulties 

in recovering the digital files that were used in the previous 

assessments both by the U.S. Geological Survey (USGS) and 

the former U.S. Bureau of Mines (USBM). The USBM was 

disbanded in 1996, and the considerable amount of oil shale 

data stored on its computers is, at present, not accessible. From 

the late 1940s to the early 1980s, the former USBM analyzed 

many cores and cuttings from holes drilled in Green River oil 

shale deposits in the three-state area using the Fischer assay 

method, a standardized laboratory test for determining oil 

yield from oil shale. During the 1970s and 1980s, the USBM 

and USGS each prepared digital databases of Fischer assays of 

the Green River oil shale deposits, and these data were made 

available to the public through the National Technical Information Service (NTIS) (Pitman, 1982; Pitman and Van Trump, 

1974, 1975). However, it was later discovered that these tapes 

had degraded in storage and could no longer be read. 

In the early 1990s, the U.S. Department of Energy (DOE) 

and the USGS initiated a cooperative project to create a digital 

National Oil Shale Database (NOSDB) that would combine 

all available Fischer assay information in the possession of the 

USBM and the USGS and prepare it for publication. The original assay data sheets were scanned and saved as Adobe PDF 

files. As a result of this effort, Fischer assay data for boreholes 

in all three basins–Piceance, Uinta, and Greater Green River–

have now been published (Dyni, 1998; Dyni and others, 2006, 

2008). Oil-yield histograms that plot variations in oil yield 

with depth have also been published for the Greater Green 

River Basin (Brownfield and others, 2008). 

The reconstructed Fischer assay files constitute the foundation of this present assessment. In order to assess individual 

oil shale units in the basin, however, a file listing the tops and 

bases of the various oil shale units in all the drill holes used 

in the assessment was also needed. Such a file for the Green 

River Basin was not known to exist, so a new digital tops file 

was generated. A series of cross sections constructed to aid in 

this effort are published as chapter 5 of this report (Ryder and 

others, 2010). 

The Fischer assay method is a standardized laboratory 

test that has been almost universally used to determine oil 

yields from oil shale, including the Green River Formation 

oil shales (Stanfield and Frost, 1949; American Society for 

Testing Materials, 1984). The Fischer assay standard method 

consists of heating a crushed and screened (-8 mesh (2.38-mm 

mesh))100-gram sample in a small aluminum retort to 500°C 

at a rate of 12°C per min and then holding it at that temperature for 40 min. The volatile vapors of shale oil, gas, and water 

pass through a condenser cooled with ice water (about 5°C) 

and collected in a graduated centrifuge tube. The oil and water 

are then separated by centrifuging and weighed. The quantities 

reported in the original sample are the weight percentages of 

shale oil, water, shale residue (contains carbon char), and “gas 

plus loss” (noncondensable gas yield) by difference. The specific gravity of the shale oil is measured and used to calculate 

the oil yield in gallons per ton (GPT).

The Fischer assay method does not determine the total 

amount of hydrocarbons in an oil shale sample, and the 

method does not measure the amount or composition of the 

gases released during the heating of the sample. These gases—

chiefly light hydrocarbons, hydrogen, and carbon dioxide—are 

reported as the “gas plus loss.”

Fischer assay does not necessarily measure the maximum amount of oil that an oil shale can produce, and there 

are retorting methods that yield more than the Fischer assay 

yield (see Dyni, 2003, p. 196–196 for a discussion of methods 

to determine oil yields). However, the oil yields achieved by 

other technologies are typically reported as a percentage of the 

Fischer assay oil yield, and thus Fischer assay is still considered the standard by which other methods are compared.

Much of the Fischer assay data for the Greater Green 

River Basin is not from core holes drilled to evaluate oil shale 

resources but rather from cuttings collected from oil and gas 

tests. The cuttings analyses are quite old, mainly from the 

1950s and 1960s, and were done to supplement the limited 

core data available at the time. Although a significant number 

of oil shale core holes were drilled subsequent to the previous 

assessments of the Greater Green River Basin, there are still 

large areas where only cuttings data are available and in which 

resources could not be estimated using core data alone. There 

are, however, significant problems with cuttings data. Oil shale 

core is generally sampled every foot or so for Fischer assay. 

The sampling interval for rotary drill hole cuttings, in contrast, 

varies from about 5 ft to possibly as much as 50 ft, thus much 

of the detail of oil yield variation is lost. Up-hole cavings also 

pose a problem; average oil yield for rich zones is greater 

than the overlying strata, thus cavings from overlying leaner 

zones could dilute the samples resulting in a lowering of the 

average GPT. In like manner, cuttings from lean zones would 

be contaminated by cuttings from richer zones above resulting in an increase in oil yield as observed. This was recently 

demonstrated for cuttings data in the Uinta Basin of Wyoming 

and Colorado (Johnson and others, 2010 b). When a rotary 

hole is drilled, there is always a delay between the time the 

drill bit produces the cuttings and when the cuttings reach the 

surface. Drillers try to compensate for this delay, but they are 

not always entirely successful. A comparison between the geophysical logs and plots of the Fischer assay results revealed 

many relatively minor discrepancies in log depths and cuttings 

depths for oil shale zones. To minimize this problem, the 

depths at which oil shale zones appear in the cuttings based on 

Fischer assay were used in this assessment rather than the log 

depths. 

Previous Assessments of the Greater 

Green River Basin 

Trudell and others (1973) reported that several members 

of the Green River Formation along the west flank of the 

Washakie Basin contained significant oil shale resources but 
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 5

did not attempt to estimate resources in the entire Washakie 

Basin due to a lack of subsurface control. Culbertson and others (1980) assessed only the Green River Basin (figs. 1 and 2) 

and only those resources that averaged at least 15 ft thick and 

15 GPT. Culbertson and others (1980) separately assessed the 

oil shale resources of the three oil shale-bearing members of 

the Green River Formation: Tipton Shale Member, Wilkins 

Peak Member, and Laney Member (fig. 3), using oil-yield data 

from 32 cores, 40 rotary holes, and results from two channels 

cut in outcrops. Intervals thinner than 15 ft were included if 

they were sufficiently rich as to yield at least the same amount 

of oil as 15 ft of 15 GPT shale (about 17,300 barrels per acre). 

In some cases, the method resulted in the inclusion of significantly thick intervals of very low grade oil shale that would 

probably be discarded during the mining operation. As a result 

Culbertson and others (1980) eliminated lean intervals that 

were generally more than 10 ft thick. 

Culbertson and others (1980) had to contend with a 

sparse data set that included many drill holes in which only 

part of an oil shale zone had been recovered or only part of 

a core had been assayed. They filled in the missing data by 

“extrapolation of nearby core data or from the lithologic 

description of the unassayed core, or by using geophysical 

logs (sonic, neutron, density), where available.” In areas 

where no assay data were available, both geophysical logs and 

outcrop measurements were used. Based on these kinds of 

data, estimated in-place oil was estimated at 123 billion barrels in the Tipton Shale Member, 100.5 billion barrels in the 

Wilkins Peak Member, and 20.5 billion barrels in the Laney 

Member. Culbertson and others (1980, p. 14) also divided the 

resource into “demonstrated” which included resources near 

closely spaced cores and “inferred.” 

Culbertson and others (1980) manually calculated their 

resource numbers. Pitman and others (1989), in their assessment of the in-place oil shale resources of the Piceance Basin 

in western Colorado, used geostatisticial interpolation by 

kriging to generate resource maps and resource numbers. 

However, kriging requires an understanding of advanced statistical concepts and tools, and completely false results can be 

obtained if not done correctly. Pitman and others (1989) found 

that the method gave good results in areas with large numbers 

of control points, but that it produced unrealistic resource 

numbers with unreasonably large error limits in areas with 

little control. They resorted to manual contouring and calculation of resources in these problem areas. 

Geology of the Eocene Green River 

Formation and Related Strata, Greater 

Green River Basin

The Greater Green River Basin is a structural and sedimentary basin formed during the Laramide orogeny (Late 

Cretaceous through Eocene). It is bounded on the north by 

the Wind River Range and Granite Mountains; on the east 

by the Rawlins uplift, Sierra Madre, and Park Range; on the 

south by the Axial Basin uplift and Uinta Mountains; and on 

the west by the Wyoming and Utah portions of the Wyoming 

thrust belt. (fig. 2). The basin is subdivided by broad structural 

arches into five sub-basins, the Green River, Great Divide, 

Sand Wash, Washakie, and Hoback Basins (fig. 2). Arches 

include the Rock Springs uplift, the Cherokee ridge, Moxa 

arch (and La Barge platform), Wamsutter arch, and Sandy 

Bench arch (fig. 2). The term “Bridger Basin” is commonly 

applied to the Green River Basin (for example, Surdam and 

Stanley, 1979). The term Hoback Basin is not always used 

and is generally confined to a limited area in the extreme 

northwestern part of the Greater Green River Basin (fig. 2). 

As used here, the Green River Basin is applied to that part of 

the Greater Green River Basin lying west of the Rock Springs 

uplift and south of the Hoback Basin (fig. 2). It includes all the 

oil shale deposits of the Green River Formation west of the 

Rock Springs uplift.

The stratigraphy of the Green River Formation and associated rocks in the Greater Green River Basin is highly variable and complex (fig. 3). Only a brief discussion is included 

here, but detailed descriptions are given in many of the 

references that are cited herein (for example, Smith and others, 2008). There are many excellent recent studies covering 

various aspects of the Green River Formation in the Greater 

Green River Basin (for example, Smith and others, 2008). 

For our purpose, we used the work of Roehler (1992a; 1992b; 

1993) as a primary source of data, as it represents the latest 

comprehensive synthesis of the stratigraphic framework of 

the entire Green River Formation in the Greater Green River 

Basin including detailed measured sections and cross sections, 

paleogeographic maps, and isopach maps. 

The Green River Formation in the Greater Green River 

Basin was deposited in Eocene Lake Gosiute, a long-lived lake 

that occupied varying parts of the Greater Green River Basin 

from about 52.5 to 47.5 Ma (Smith and others, 2008). Paleogeographic maps presented here, representing various time 

periods in the development of Lake Gosiute, are from Roehler 

(1993), and isopach maps included with these reconstructions 

are from Roehler (1992b). The reconstructions and isopach 

maps were originally published separately, but are combined 

here. Isopach maps were also constructed for assessment 

purposes using the tops file that we assembled supplemented 

by surface sections measured by Roehher (1989a–e). These 

isopach maps are of different stratigraphic intervals than those 

constructed by Roehler (1992b). 

Lake Gosiute underwent two expansive periods, one early 

and one late in its history, during which the lake expanded to 

cover much of the Greater Green River Basin. A prolonged 

period, during which the lake contracted to a comparatively 

small area, separated these two expansive periods. The early 

expansion is represented by the Tipton Shale Member, the 

contracted period is represented by the Wilkins Peak Member, 

and the later expansion is represented by the Laney Member 

(fig. 3; pl. 1). Significant oil shale was deposited during all 

three periods. However, oil shales in the Tipton Shale and 
6 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Gray or tan fluviovolcanic sandstone

 deposits

Mixed tan or gray freshwater lacustrine 

 and sandstone deposits and gray or 

 green flood-plain mudstone and 

 sandstone deposits

Gray or tan lacustrine sandstone 

 deposits

Green River Basin ROCK SPRINGS UPLIFT Great Divide basin Great Divide Basin

Late

Eocene Middle Eocene Early Eocene

150 MILES

8,000 FEET

Bridger Formation

Adobe Town Member

Kinney Rim Member Washakie Formation

Hartt Cabin Bed

LaClede Bed

Laney Member of

Green River Formation

Cow Hollow Bed Sand Butte Bed

Craven Creek Bed Whiskey Butte Bed

Cathedral Bluffs

Tongue of

Wasatch Formation Wilkins Peak Member of

Green River Formation

Godiva Rim Member of

Green River Formation

Cathedral Bluffs

Tongue of

Wasatch Formation

Battle Spring

Formation

Ramsey Ranch Member of

Wasatch Formation

Niland Tongue of

Wasatch Formation

Luman Tongue of Green River Formation

Tipton Shale Member 

of Green River Formation

Rife Bed

Scheggs Bed

Main body of Wasatch Formation

Niland Tongue of

Wasatch Formation

Farson Sandstone

Member of Green River Formation

Alkali Creek Tongue of

Wasatch Formation

WEST EAST

EXPLANATION

Arkose (pediment) deposits

Red flood-plain deposits

Gray, and green floodplain deposits

Cyclic salt water lacustrine oil shale,

 evaporite, and mudflat deposits

Saltwater lacustrine (rich) oil shale deposits

Mudflat and some saltwater lacustrine

 oil shale deposits

Freshwater lacustrine (lean) oil shale deposits

Paludal (coal-bearing) deposits

Figure 3. Generalized east-west cross section of Eocene rocks in the Greater Green River Basin.

Laney Members are in thick continuous intervals over large 

areas of the basin, whereas oil shales in the Wilkins Peak 

Member are restricted to a much smaller area and are, for the 

most part, interbedded with sandstone, mudstone, and the 

saline minerals trona (a sodium bicarbonate mineral), shortite 

(sodium calcium carbonate), and halite (pl. 1). Although most 

of the oil shale in the Greater Green River Basin is in the 

Tipton Shale, Wilkins Peak, and Laney Members, low-grade 

oil shale is also present in the freshwater Lumen Tongue of 

the Green River Formation below the Tipton (fig. 3). Oil shale 

resources in these rocks are not assessed here due to a lack 

of data, but these rocks will be described briefly. Units of the 

Green River Formation and intertonguing strata of the Wasatch 

Formation will be described from oldest to youngest.

Ramsey Ranch Member of the Wasatch 

Formation 

Widespread lacustrine conditions first developed in the 

Greater Green River Basin during deposition of the Ramsey 

Ranch Member of the Wasatch Formation (figs. 3 and 4). 

Swamps, small shallow freshwater lakes and numerous ponds 

developed in the southernmost part of the basin north of the 

Uinta Mountains and into the central parts of the Washakie 

and Great Divide Basins (fig. 4). Carbonaceous shale, coal, 

freshwater limestone, and oil shale were deposited in these 

fresh-water lakes and ponds (Roehler, 1993). The Ramsey 

Ranch Member is more than 600 ft thick in the trough north 

of the Uinta Mountains and more than 800 ft in the center of 
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 7

Pass Peak

Formation

Main body of Wasatch Formation

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

107 ̊

108 ̊

109 ̊

0

0 50 KILOMETERS

50 MILES

EXPLANATION

 Main body of 

Wasatch Formation

Ramsey

Ranch

Member

WIND RIVER RANGE

WYOMIN

G THRUS

T BELT

Sand Wash Basin

Great Divide Basin

Battle Spring

Formation

SWEETWATER

ARCH

RAWLINS

UPLIFT

ROCK

SPRINGS

UPLIFT

Washakie SIERRA MADRE

Basin

UINTA MOUNTAINS

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

Gray or tan alluvial fan conglomerate deposits

Red or variegated flood-plain mudstone and sandstone

 deposits

Gray or green flood-plain mudstone and sandstone

 deposits

Gray, brown, or black paludal carbonaceous deposits

Tan or brown freshwater lacustrine oil shale deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Gray or brown freshwater pond limestone deposits

Gray or tan lacustrine sandstone deposits

Depositional axis 

Thickness of Ramsey Ranch Member

0 200 400

800

600

0

200400

400

600

Figure 4. Paleogeographic map of the Ramsey Ranch Member of the Wasatch Formation.
8 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

the Washakie Basin. It thins to less than 400 ft across the south 

part of the Rock Springs uplift (fig. 4).

Lumen Tongue of Green River Formation

The freshwater lakes and ponds expanded and coalesced 

during deposition of the Lumen Tongue of the Green River 

Formation (figs. 3 and 5) (Roehler 1993). The Lumen stage of 

Lake Gosiute, at its maximum extent, covered about 6,650 mi2

of the Washakie and Great Divide Basins, the western part of 

the Sand Wash Basin and the southern part of the Green River 

Basin (fig. 5, Roehler, 1993). The freshwater Lumen Tongue 

varies from about 200 to 400 ft thick along the trough, north 

of the Uinta Mountains and in the Washakie Basin (fig. 5). 

It consists of clay-rich oil shale, mollusk-bearing sandstone 

and limestone, carbonaceous shale with thin coal beds, and 

siltstone deposited mainly in lacustrine environments (Pipiringos, 1961; Roehler, 1993). Molluscs are freshwater types, 

consisting mainly of the gastropods Goniobasis terera and 

Viviparus sp., and the pelecypod Lampsilis sp. Roehler (1993, 

p. F38) believed that Lake Gosiute during the Lumen stage 

drained southward near the east end of the Uinta Mountains 

and into the Piceance Basin to the south. Johnson (1985) noted 

similarities between the Lumen Tongue of the Green River 

Formation and the Cow Ridge Member of the Green River 

Formation, a roughly contemporaneous freshwater lake phase 

in the Piceance and Uinta Basins.

Low-grade oil shales were deposited throughout much 

of the lake during Lumen time (fig. 5). There has been little 

Fischer assay data collected for the Lumen Tongue and it 

has not been the target of an oil shale project. The unit was 

assayed in the Farmers Union Twin Buttes Unit 1 well in sec. 

33, T. 14 N., R. 106 W., in the trough of the Green River Basin 

north of the Uinta Mountains where it is 380 ft thick and averaged 9.2 GPT. One 30-ft-thick interval in the lower part of the 

Lumen averaged 26.7 GPT, with a maximum reading of 31.6 

GPT. It appears that the tongue includes significant oil shale 

in the subsurface north of the Uinta Mountains, but at present 

there is too little information to assess it. 

Niland Tongue of Wasatch Formation

The Niland Tongue of the Wasatch Formation lies 

between the Lumen Tongue and the Tipton Shale Member of 

the Green River Formation and represents a contraction of 

lacustrine deposition from the preceeding Lumen phase into 

a comparatively small area north of the Uinta Mountains and 

in the trough of the Washakie and Great Divide Basins (figs. 

3 and 6). Maximum thickness is about 400 ft along the trough 

north of the Uinta Mountains and in the Washakie Basin 

(fig. 6). In the Great Divide Basin, the Niland Tongue consists 

of coal beds, clay shale, siltstone, sandstone, and low-grade 

oil shale (Pipiringos, 1961). It grades laterally into variegated 

mudstones and sandstones of the main body of the Wasatch 

Formation. Samples were assayed in the Farmers Union Twin 

Buttes Unit 1 well mentioned above, where the unit is 170 ft 

thick and averages 7.3 GPT; it does not appear to contain oil 

shale of high enough grade to be considered a resource.

Tipton Shale Member of the Green River 

Formation

The Tipton Shale Member is the oldest member of the 

Green River Formation in the Greater Green River Basin that 

contains widespread oil shale of sufficient grade to have been 

considered for oil shale development. The member has been 

subdivided into the lower Scheggs Bed and the upper Rife Bed 

(Roehler, 1991a), which are separated by the Farson Sandstone Member of the Green River Formation (fig. 3). Maximum expansion during Tipton time was during deposition of 

the Scheggs Bed, when Lake Gosiute expanded to cover most 

of the Greater Green River structural and sedimentary basin 

(fig. 7). Lake Gosiute was freshwater during deposition of 

the Scheggs Bed, as freshwater mollusks are present in lakemargin deposits. Roehler (1993, his fig. 50) believed that Lake 

Gosiute drained southward into Lake Uinta during deposition 

of the Scheggs Bed, keeping the lake’s waters fresh. By the 

beginning of deposition of the Rife Bed, Lake Gosiute had significantly shrunk in size, the outlet had been lost, and the lake 

waters evolved from fresh to saline (Roehler, 1993, p. F43). 

The Scheggs Bed consists, in offshore areas, of mostly 

brown-weathering, clay-rich oil shale with a few beds of thin 

tuff (Roehler, 1991a) (fig. 7). In lake-margin areas, it includes 

limestone, dolomite, conglomerate, sandstone, siltstone, 

carbonaceous shale, and coal (Roehler, 1991a). The bed is 

more than 200 ft thick along the trough of the Green River 

Basin just north of the Uinta Mountains, exceeds 300 ft in the 

troughs of the Washakie and Sand Wash Basins (fig 7), and is 

less than 50 ft thick throughout the northern part of the Green 

River Basin and Great Divide Basin (fig 7). The upper part 

grades into the Farson Sandstone Member toward the north in 

the Green River Basin. Two stacked sandy shoreline sequences 

consisting of, in ascending order, nearshore, strandline, 

swamp, mudflat, and fluvial channel have been described in 

the upper part of the Scheggs Bed along the southeast margin 

of the Sand Wash Basin (Roehler, 1990a). Total thickness of 

the two shoreline sequences is about 200 ft. Late in the deposition of the Scheggs Bed, marginal lacustrine sandstone of the 

Farson Sandstone Member prograded from north to south 

across the northern part of the Green River Basin (fig. 8).

A generally northward-thickening wedge of sandy marginal lacustrine rocks, the Farson Sandstone Member of the 

Green River Formation, overlies the Scheggs Bed throughout 

the northwestern part of the Green River Basin (Roehler, 

1992b) (figs. 3and 8) and is, in part, laterally equivalent to the 

upper part of that bed. The predominantly fluvial Alkali Creek 

Tongue of the Wasatch Formation overlies the Farson Sandstone in the northwest part of the Green River Basin (Roehler, 

1991a) (fig. 8). Where the Rife Bed is absent the Wilkins Peak 

Member directly overlies the Farson Sandstone Member and 
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 9

EXPLANATION

Luman Tongue of Green River Formation

Possible outlet

to Lake Uinta

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

107 ̊

108 ̊

109 ̊

ROCK

SPRINGS

UPLIFT UTAH COLORADO

UTAH IDAHO

WYOMING

COLORADO

WYOMING

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

0

0 50 KILOMETERS

50 MILES

Main body of 

Wasatch Formation

WIND RIVER RANGE

WYOMIN

G THRUS

T BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie

Basin

Green River Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

Sand Wash Basin

Red or variegated flood-plain mudstone and sandstone

 deposits

Gray or green flood-plain mudstone and sandstone

 deposits

Tan or brown freshwater lacustrine oil shale deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Gray or tan lacustrine sandstone deposits Depositional axis 

Thickness of Lumen Tongue (in feet)

Paleodrainage

300

0

100

200

100 200

300

300

0

100

0

200

400

300

200

1000

Figure 5. Paleogeographic map of the Lumen Tongue of the Green River Formation. 
10 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Red or variegated flood-plain mudstone and sandstone

 deposits

Gray or green flood-plain mudstone and sandstone

 deposits

Tan or brown freshwater lacustrine oil shale deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Gray or tan lacustrine sandstone deposits Depositional axis 

Gray, brown, or black paludal carbonaceous deposits

Gray or tan alluvial fan conglomerate deposits

EXPLANATION

 Niland Tongue of

Wasatch Formation

Main body of Wasatch Formation

 Main body of 

Wasatch Formation

WIND RIVER RANGE

Battle Spring

Formation

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

107 ̊

0

0 50 KILOMETERS

50 MILES

ROCK

SPRINGS

UPLIFT

Sand Wash Basin

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

WYOMIN

G THRUS

T BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie

Basin

Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

108 ̊

109 ̊

0

200 300

400

400

200

100

400

300

400

300

200

100

0

Thickness of Niland Tongue in feet

Figure 6. Paleogeographic map of the Niland Tongue of the Wasatch Formation.
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 11

ROCK

SPRINGS

UPLIFT

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

WIND RIVER RANGE

WYOMIN

G THRUS

T BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie Basin

Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

Scheggs Bed of Tipton Shale Member of

 Green River Formation

Possible outlet

to Lake Uinta

111 ̊ 110 ̊

42 ̊

41 ̊

108 ̊

109 ̊

EXPLANATION

 MAIN BODY OF 

WASATCH FORMATION

Sand Wash Basin

Battle Spring

Formation

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

43 ̊

107 ̊

 Main body of 

Wasatch Formation

0

0 50 KILOMETERS

50 MILES

Red or variegated flood-plain mudstone and sandstone

 deposits

Tan or brown freshwater lacustrine oil-shale deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift Gray or tan pediment arkose deposits

Gray or tan lacustrine sandstone deposits

Depositional axis

Algal reefs (stromatolites)

Paleodrainage

0

50

100

150

200

100 150200

0

50

0

50

100

150

200

300

250

250

100

50

0

150

250

200

300

Thickness of Scheggs Bed in feet

Figure 7. Paleogeographic map of the Scheggs Bed of the Tipton Shale Member of the Green Formation.
12 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

100

200

200

300

400

Thickness of Farson Sandstone in feet

 Main body of

Wasatch Formation

Scheggs Bed of Tipton Shale Member of

 Green River Formation

Farson Sandstone

Member of Green

River Formation

 Alkali Creek

 Tongue of

 Wasatch

 Formation

Battle Spring

Formation

Possible outlet

to Lake Uinta

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

107 ̊

108 ̊

109 ̊

EXPLANATION

 Main body of 

UTAH

Wasatch Formation

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

0

0 50 KILOMETERS

50 MILES

ROCK

SPRINGS

UPLIFT

Sand Wash Basin

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

WIND RIVER RANGE

WYOMIN

G THRUS

T BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie

Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

Red or variegated flood-plain mudstone and sandstone

 deposits

Gray or green flood-plain mudstone and sandstone

 deposits

Tan or brown freshwater lacustrine oil-shale deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Gray or tan lacustrine sandstone deposits

Depositional axis 

Gray or tan alluvial fan conglomerate deposits Thin shoreline sandstone

Paleodrainage

0

Green 

River 

B

as

in

Figure 8. Paleographic map of the Farson Sandstone Member of the Green River Formation.
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 13

Alkali Creek Tongue (fig. 3). According to Roehler (1992b), 

the Farson Sandstone Member reaches a maximum thickness 

of over 400 ft in the northeastern part of the Hoback Basin 

and wedges out in the southern part of the Green River Basin 

(fig. 8). We combined the Farson Sandstone Member and the 

Alkali Butte Member in our study because the two cannot be 

distinguished using only geophysical logs and Fischer assay 

results. Using our tops file, the combined Farson Sandstone 

Member and Alkali Creek Tongue reaches a maximum thickness of 790 ft in the northern part of the Green River Basin 

(fig. 9). The Farson Sandstone Member is represented in the 

Washakie Basin by a thin interval of lean, silty oil shale that is 

generally less than 10 ft thick between the Scheggs and Rife 

Beds. 

Roehler (1991a; 1992b) believed that the Farson Sandstone Member was deposited by drainages that originated in 

the Wind River Range, north of the Greater Green River Basin 

(fig. 8), and noted that the Farson contains pebbles of schist 

and gneiss sourced from the Precambrian core of that range 

as a result of a major tectonic uplift. More recently, Pietras 

and others (2003) and Smith and others (2008) suggested that 

(1) the Farson Sandstone Member was deposited by throughgoing drainage systems that originated north of, and flowed 

southward across the Wind River Range, which was characterized as being topographically subdued at the time; and (2) 

uplift of the range after deposition of the Farson Sandstone 

Member diverted these drainages to the north and away from 

the Greater Green River Basin, causing a retreat of Lake Gosiute during deposition of the overlying Wilkins Peak Member. 

The Rife Bed (figs. 3 and10) overlies the Scheggs Bed 

or Farson Sandstone Member where present. It consists of (1) 

light-gray-weathering, brown to black dolomitic oil shale with 

scattered lenses of dolomite, and thin layers of siltstone and 

tuff in offshore areas; (2) largely gray and green mudstone, 

algal limestone, and siltstone in lake-margin areas, strata that 

Roehler (1991a) included in the lithologically similar Wilkins 

Peak Member (fig. 3); and (3) mainly sandstone and conglomerate along the north margin of the Uinta Mountains (Roehler, 

1991a). According to Roehler (1992b), the Rife Bed attains a 

maximum thickness exceeding 200 ft along the trough north 

of the Uinta Mountains and in the Great Divide and Washakie 

Basins (fig. 10). The isopach map of the unit generated by 

the tops file compiled for this assessment indicates maximum 

thicknesses of 123 ft for the Rife Bed along the Uinta Mountain trough and 230 ft in the Washakie Basin (fig. 10). The area 

occupied by Lake Gosiute decreased throughout deposition of 

the Rife Bed with the lake retreating out of the northern part 

of the Green River Basin and most of the Sand Wash Basin 

(fig 10).

Figure 11 is a structure contour map on the top of the 

Tipton Shale Member. For most of the Greater Green River 

Basin the contour horizon is the top of the Rife Bed, but in 

the northern part of the Green River Basin, where the bed is 

missing, the contour horizon is the top of the Scheggs Bed. 

The map was constructed using subsurface data from core 

holes and oil and gas tests (Mercier and others, this report) 

and surface elevations and locations from published geologic 

maps. Published geologic maps used include Roehler (1972a, 

b; 1973b; 1974b, c, d, e; 1977; 1978a, b, c), Tweto (1976; 

1979), and W. C. Culbertson (USGS, unpub. mapping). 

Wilkins Peak Member of the Green River 

Formation

The Wilkins Peak Member, named by Bradley (1959), 

represents a major contraction of Lake Gosiute to mostly the 

central part of the Green River Basin and the western parts of 

the Great Divide and Washakie Basins (figs. 3 and 12). This 

contraction was attributed by Bradley (1963) to a shift to a 

hotter, drier climate. However, Wilf (2000), in his study of 

plant species in the Greater Green River Basin found little evidence that climate played the dominant role in the expansions 

and contractions of Lake Gosiute. Pietras and others (2003), as 

previously discussed, attributed the contraction of Lake Gosiute during Wilkins Peak time to a loss of water supply due to 

the diversion of major drainages entering the basin from the 

north due to uplift of the Wind River Range. 

Unlike the underlying Tipton Shale Member and overlying Laney Member the Wilkins Peak Member generally 

does not include thick intervals of continuous oil shale, but 

rather the oil shale beds are interbedded with other lithologies including sandstone, mudstone, and beds of the sodium 

bicarbonate mineral trona, shortite, and halite. The member 

intertongues with and is replaced by strata of the Wasatch 

Formation toward the basin margins (figs. 3 and 12). The 

world’s largest known deposit of trona is in the Wilkins Peak 

Member, and it is being extensively mined today. The Wilkins 

Peak Member was originally defined by Bradley (1959), who 

thought that it was confined to the Green River Basin. Subsequent work by Roehler (1989a, b) demonstrated that it is also 

present east of the Rock Springs uplift, in the western parts of 

the Great Divide and Washakie Basins. Lake Gosiute during Wilkins Peak time was described by Bradley and Eugster 

(1969) as a chemically stratified lake, with the deeper parts 

having a strong brine of sodium carbonate-sodium chloride 

composition. Eugster and Surdam (1973) and Eugster and 

Hardie (1975), however, interpreted the lake at that time to be 

a shallow “playa lake” complex that had many similarities to 

Lake Magadi in Africa . Roehler (1993) estimated that, during 

expanded lake stages, Lake Gosiute was a permanent lake that 

occupied as much as 8,700 mi2

 and persisted for as long as 20 

thousand years and thus could not be classified as a playa lake 

during these periods. 

Eugster and Hardie (1975) subdivided the Wilkins Peak 

Member into six major lithofacies: flat-pebble conglomerate, lime sandstone, mudstone, oil shale, trona-halite, and 

siliciclastic sandstone. Trona-halite beds generally range in 

thickness between 1 and 15 ft but are locally as much as 30 ft 

(Roehler, 1993). Not all trona beds contain halite. Culbertson 

(1971) identified 42 trona beds in the Wilkins Peak Member, with 25 attaining a thickness of at least 3 ft. Culbertson 
Figure 9. Isopach map of the Farson Sandstone Member of the Green River Formation. 

R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 100 W.

R. 105 W.

R. 110 W.

R. 115 W.

R. 95 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. 

367

15

298

213

235

275

45

570

790 640 383

383

430

640

530

375

370

360

370

200

270

328 344.4

280

125

170 210

190

270

40

270 130

60

38

210 60 270 60 100

50

130

11

10

84.9

55.7

10.3

6.3 13.2 10

100

80 24.1

10

8.5 4 8

50

40

40

6

11.7

5.5 25

30

50 4.1

4.3

10

50

20 40

50

4.2 9.9

150

123

120

T.

29

N.

T.

30

N.

T.

28

N.

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°

42°30’42°00’41°30’41°00’

COLORADO

WYOMING

UTAH

EXPLANATION

Farson Sandstone and Alkail C Tongue Interval, thickness in f

> 500251–500101–250

Borehole—Thickness of  in feet

!
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 15

WASATCH FORMATION

 Wasatch Formation

RIFE BED OF TIPTON SHALE MEMBER OF

 GREEN RIVER FORMATION

WILKINS PEAK MEMBER OF

 GREEN RIVER FORMATION

WILKINS PEAK MEMBER OF

 GREEN RIVER FORMATION

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

107 ̊

108 ̊

109 ̊

EXPLANATION

BATTLE SPRING

FORMATION

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

0

0 50 KILOMETERS

50 MILES

ROCK

SPRINGS

UPLIFT

Sand Wash Basin

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

WIND RIVER RANGE

WYOMING 

THR

UST BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie Basin

Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

Red or variegated flood-plain mudstone and sandstone

 deposits

Gray or green flood-plain mudstone and sandstone

 deposits

Brown or black saltwater lacustrine oil-shale deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Gray or tan lacustrine sandstone deposits

Gray or green mudflat mudstone and playa-lake dolomite

 deposits

Algal reefs (stromatolites)

0

50 100

150

200

0 50

100 150

200

200

200

150 100

50

0

Thickness of Rife Bed of 

 Tipton Shale Member in feet

Figure 10. Paleogeographic map of the Rife Bed of the Tipton Shale Member of the Green River Formation.
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R 117 W R 116 W R 115 W R 114 W R 113 W R 112 W R 111 W R 110 W R 109 W R 108 W R 107 W R 106 W R 105 W R 104 W R 103 W R 102 W R 101 W R 100 W R 99 W R 98 W R 97 W R 96 W R 95 W 

R 115 W

R 118 W 

6225

5583 5467 5485

5344

5454

5558

5724

5504 6030

5195

5140

5189 5298 5692.7

5849

5463

5893

5246

5519 5485 6823

5146

5019 5397

5158.4

5133

5904

4817

4629 5067

5028

4858 5562 5375

4502 4469

4449 6564

6787

6223

4749

4916.7 4659.6

5840 5982 6289

6303.5 5888.5

6054

4266 4092.5 4423.1

4421.1

4664

5594

5182.3

6270

6483

6963

6822

6949 497

55

4155

4227

4041 4503.1

4085

4994.6

4640

6612

6855 3999 2970

3831

3935

3920

3743

3864 4114.1

4146.3 4234

3647

3885

3769

3697

3739

3766

5314.9

5914

5250.7

3868

5132

4462.3

4183 4381

996

788

110°30' 110°0' 109°30' 109°0' 108°30' 108°

42°30'

42°0'

41°30'

41°0'

COLORADO

WYOMING

UTAH

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6030

> 8,5008,000–8,5007,501–8,0007,001–7,5006,501–7,0006,001–6,500

5,501–6,0005,001–5,5004,501–5,0004,001–4,5003,501–4,0003,001–3,500

0 6 12 MILES

0 5 10 KILOMETERS

Surface control point (top of Tipton Shale Member)

R. 100 W.

R. 105 W.

R. 110 W.

R. 95 W.

Map location

T.

27

N.

T.

28

N.

T.

29

N.

T.

30

N.

T.

26

N.

T.

25

N.

T.

24

N.

Elevation of the top of the Tipton Shale Member, elevati

EXPLANATION

Borehole–Depth to top of Tipton Shale Member, in feet

Assessment boundary for the Tipton Shale Member 

WYOMING

Figure 11. Structure contour map on the top of the Tipton Shale Member of the Green River Formation.
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 17

FEET

300

200

100

0

0 5 10 15 20 MILES

EXPLANATION

Lacustrine sandstone

Mostly gray and green lacustrine and fluvial sandstone

 and mudstone, with some evaporites in the Wilkins Peak Member

Mostly red fluvial sandstone and

 mudstone

Unconformity

24

2

NORTH

1 2 3 4 5 6 7 8 9 10

SOUTH

Hartt Cabin Bed of Laney Member of

Green River Formation

Sand Butte Bed of Laney Member of

Green River Formation

LaClede Bed of Laney Member of Green River Formation Wilkins Peak Member of Green River Formation

Cathedral Bluffs Tongue of Wasatch Formation

Cathedral Bluffs Tongue of

Wasatch Formation

Farson Sandstone Member of Green River Formation

Main body and Niland Tongue of Wasatch Formation

Rife Bed

Scheggs Bed

Tipton Shale Member of

Green River Formation

77

76

74

72

68

67

60

58

51

46

44

42

37

34

29

24

19

15

11

9

6

5

2

1

Gray or tan fluviovolcanic sandstone

 deposits

Cyclic salt water lacustrine oil shale, evaporite, and mudflat deposits.

 Numbered lacustrine oil-shale beds at the base of depositional cycles.

Saltwater lacustrine (rich) oil shale deposits

Freshwater lacustrine (lean) oil shale deposits

Figure 12. North-south cross section of the Wilkins Peak Member of the Green River Formation 

and adjacent formations.
18 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

(1971) noted that most trona and halite beds are underlain by 

oil shale. Roehler (1990b; 1992b) identified 77 depositional 

cycles in the depocenter of the Wilkins Peak Member, each 

consisting, in ascending order, of oil shale, trona and halite, 

and mudstone, but he observed that trona and halite beds were 

not present in every cycle (fig. 12). Beds 1–11 were placed by 

Roehler in the “lower part of the Wilkins Peak Member,” beds 

12–67 in the “middle part of the Wilkins Peak Member”, and 

beds 68–77 in the “upper part of the Wilkins Peak member.” 

Figures 13–15 show the various environments of deposition. 

The lower part, which extends across much of the Greater 

Green River Basin, is thickest in the southern parts of the 

Green River and Washakie Basins, locally reaching a maximum thickness of more than 200 ft (fig. 13). At least 10 beds 

of trona or trona and halite are present in the lower member in 

the southern part of the Green River Basin. The middle part is 

largely confined to the Green River Basin and is thickest just 

north of the Uinta Mountains where it reaches a maximum 

thickness of over 900 ft (fig. 14); it contains at least 28 beds 

of trona or trona and halite in the “middle member” (Roehler, 

1992b). The upper part is comparatively thin (40–125 ft thick), 

represents a transition to less saline conditions that characterize the overlying Laney Member, and contains no bedded 

trona or halite (fig. 15). Roehler (1993) believed that Lake 

Gosiute began to drain south into Lake Uinta in the Piceance 

and Uinta Basins at this time, causing the water in Lake Gosiute to become fresher (fig. 15).

Laney Member of the Green River Formation

The Laney Member of the Green River Formation 

overlies the Wilkins Peak Member and represents a major 

expansion of Lake Gosiute (figs. 3 and 16). At the onset of 

Laney deposition, Lake Gosiute evolved from a comparatively 

small, highly saline lake that may have periodically dried up 

to a much larger and deeper permanent lake that varied from 

saline-alkaline to fresh water (Roehler, 1973a; 1993; Surdam and Stanley, 1979). Bradley (1964) and Roehler (1993) 

attributed this expansion to a climatic shift from hot and dry to 

more humid. Surdam and Stanley (1980), in contrast, believed 

that the cause of this expansion was related to an enlargement 

of the drainage basin to include water from basins to the north 

and cited as evidence the sudden arrival of volcaniclastic sediments from the Absaroka volcanic field along the north margin 

of the Greater Green River Basin at the onset of this expansion. Surdam and Stanley (1979; 1980), and Roehler (1993) 

noted the abundant freshwater mollusks in parts of the Laney 

Member and suggested that Lake Gosiute drained southward 

into Lake Uinta near the eastern terminus of the Uinta uplift at 

this time (fig. 16). 

Originally named the “Laney Shale Member” by Schultz 

(1920) for exposures along Laney Rim in the northern part of 

the Washakie Basin, the name was shortened to Laney Member by Roehler (1973a) because it includes other lithologies 

besides shale at its type locality. It has been described by 

Bradley (1964), Culbertson (1969), Roehler (1973a), and Surdam and Stanley (1980), all of whom generally recognized a 

lower oil shale unit and an upper sandstone and mudstone unit. 

Roehler (1973a) subdivided the member, in ascending order, 

into the LaClede Bed, the Sand Butte Bed, and the Hartt Cabin 

Bed (figs. 3, 16–18). The LaClede Bed is mainly oil shale, the 

Sand Butte bed is tuffaceous sandstone and siltstone, and the 

Hartt Cabin Bed is interbedded sandstone, siltstone, mudstone, 

shale, oil shale, tuff, limestone, and dolomite. The Laney 

Member unconformably overlies the Wilkins Peak Member 

and Cathedral Bluffs Tongue of the Wasatch Formation in the 

vicinity of the LaBarge Platform in the northern part of the 

Green River Basin (Roehler, 1992b, p. E3) (fig. 2).

Figure 19 is a structure contour map drawn on the top of 

the LaClede Bed in the Green River and Washakie Basins. The 

map was constructed from subsurface data obtained from core 

holes and oil and gas tests (Mercier and others, this report) and 

surface elevations and locations from geologic maps including Roehler, (1972a, b; 1973b; 1974b– e; 1977; 1978a– c), 

Love and Christiansen (1985), and W. C. Culbertson (USGS, 

unpub. mapping). Elevation of the top of the LaClede varies 

from about 6,500 to 8,000 ft around the perimeter of the three 

basins to minimums of about 5,100 ft in the southeastern part 

of the Green River Basin and about 3,600 ft in the southwestern part of the Washakie Basin (fig. 19).

The Sand Butte and Hartt Cabin Beds are characterized 

by dacite and andesite fragments sourced from the Absaroka 

volcanic field north of the Greater Green River Basin (Ebens, 

1963; Surdam and Stanley, 1980). These volcaniclastics 

entered the Greater Green River Basin from one or more 

points along the north margin and first appeared about the 

same time as the transgression that initiated deposition of the 

Laney Member began. Volcanic-rich sediments prograded 

southward throughout deposition of the Laney Member, filling in Lake Gosiute from north to south. The volcaniclastic 

sediments complexly intertongue with oil shale of the LaClede 

Bed or the lower part of the Laney Member. This intertonguing and southward progradation of volcaniclastic sediments 

was documented in detail in the Green River Basin by Culbertson (1969, his fig. 3) and Culbertson and others (1980, their pl. 

1, C–C’) (fig. 20, sandstone, marlstone and thin beds of limestone and oil shale facies). Gilbert-type deltas, with foresets 

ranging from 10 to 25 meters high, have been described in the 

Laney Member in the northwestern part of the Washakie Basin 

(Stanley and Surdam, 1978). The upper part of the member is 

overlain by fluvial strata of the Washakie and Bridger Formations, indicating an end to the prolonged and widespread 

lacustrine conditions in the Greater Green River Basin.
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 19

Red or variegated flood-plain mudstone and sandstone

 deposits

Gray or green flood-plain mudstone and sandstone

 deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Depositional axis 

Thin shoreline sandstone

Algal reefs (stromatolites)

Cyclic saltwater lacustine oil shale deposits

White, gray, green, or brown bedded evaportie deposits

Gray or green mudflat mudstone and playa-lake dolomite

 deposits

Wasatch Formation

 Wasatch Formation

Maximum extent of

 lake basin

Lower part of Wilkins Peak Member of

 Green River Formation

10 beds of trona

or trona and halite

in 200 ft of rock

Bed No. 6. One of 11

saltwater lakes with thin

sandstone shorelines

and algal reefs

Wasatch Formation

111 ̊ 110 ̊

42 ̊

43 ̊

41 ̊

107 ̊

108 ̊

109 ̊

EXPLANATION

Battle Spring

Formation

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

0

0 50 KILOMETERS

50 MILES

ROCK

SPRINGS

UPLIFT

Sand Wash Basin

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

WIND RIVER RANGE

WYOMIN

G THRUS

T BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie

Basin

Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

100

50

0

150

200

200

200

150

10050

0

Thickness of lower part of Wilkins

 Peak Member in feet

Figure 13. Paleogeographic map of the lower part of the Wilkins Peak Member.
20 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Red or variegated flood-plain mudstone and sandstone

 deposits

Gray or green flood-plain mudstone and sandstone

 deposits Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Depositional axis 

Thin shoreline sandstone

Algal reefs (stromatolites)

Cyclic saltwater lacustrine oil shale deposits

White, gray, green, or brown bedded evaportie deposits

Gray or green mudflat mudstone and playa-lake dolomite

 deposits

Gray or tan alluvial fan conglomerate deposits

Paleodrainage

Maximum 

extent

 of lake basin

Middle part of Wilkins Peak 

 Member of Green River

 Formation

Bed No. 24. One of

55 saltwater lakes with

thin sandstone shorelines

and algal reefs

 Last movement of

Wind River thrust fault

 26 beds of trona or trona

and halite in 900 ft of rocks

 Cathedral Bluffs

 Tongue of

Wasatch Formation

 Canyon Creek

conglomerate deposits

 Last movement of

Sparks Ranch thrust fault

43 ̊

41 ̊

42 ̊

EXPLANATION

111 ̊ 110 ̊

107 ̊

108 ̊

109 ̊

 Wasatch Formation

 Wasatch Formation

Battle Spring

Formation

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

0

0 50 KILOMETERS

50 MILES

ROCK

SPRINGS

UPLIFT

Sand Wash Basin

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

Wasatch Formation

WIND RIVER RANGE

WYOMIN

G THRUS

T BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie

Basin

Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

100

0

200

300

400

500

600

600

700

800

900

Thickness of middle part of 

 Wilkins Peak Member in feet

Figure 14. Paleogeographic map of the middle part of the Wilkins Peak Member. 
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 21

Red or variegated flood-plain mudstone and sandstone

 deposits

Gray or green flood-plain mudstone and sandstone

 deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Depositional axis 

Algal reefs (stromatolites)

Brown or black saltwater lacustrine oil shale deposits

Gray or green mudflat mudstone and playa-lake dolomite

 deposits

Gray or tan lacustrine sandstone deposits

ROCK

SPRINGS

UPLIFT

Sand Wash Basin

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

Wasatch Formation

Wasatch Formation

Wasatch Formation

WIND RIVER RANGE

WYOMIN

G THRUS

T BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie

Basin

Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

 Laney Member of

Green River Formation

Upper part of Wilkins Peak

 Member of

 Green River Fromation LaClede Bed of Laney Member 

 of Green River Fromation

Cathedral Bluffs Tongue

 of Wasatch Formation

Godiva Rim Member

 of Green River

 Formation

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

107 ̊

108 ̊

109 ̊

EXPLANATION

Battle Spring

Formation

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

0

0 50 KILOMETERS

50 MILES

Paleodrainage

100

50

50

0

100

50 0 Thickness of upper part of 

 Wilkins Peak Member in feet

Figure 15. Paleogeographic map of the upper part of the Wilkins Peak Member.
22 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Gray or green flood-plain mudstone and sandstone

 deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Gray or tan pediment arkose deposits

Depositional axis 

Brown or black saltwater lacustrine oil shale deposits Algal reefs (stromatolites)

Gray or tan lacustrine sandstone deposits

 Bridger

 Formation

 Bridger

 Formation

LaClede Bed of Laney Member of Green River Formation

Battle Spring

Formation

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

107 ̊

108 ̊

109 ̊

EXPLANATION UTAH COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

0

0 50 KILOMETERS

50 MILES

ROCK

SPRINGS

UPLIFT

Sand Wash Basin

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

WIND RIVER RANGE

WYOMING 

THRUST BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

Washakie Basin

Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

800

700

600

600

500

400

300

200

100

0

Thickness of LaClede Bed in feet

Figure 16. Paleogeographic map of the LaClede Bed of the Laney Member.
Geology of the Eocene Green River Formation and Related Strata, Greater Green River Basin 23

Gray or green flood-plain mudstone and sandstone

 deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift Gray or tan fluviovolcanic sandstone deposits

Tan or brown freshwater lacustrine oil shale deposits Depositional axis

Gray or tan lacustrine sandstone deposits

Mixed tan or gray freshwater lacustrine and

 sandstone deposits and gray or green flood-plain

 mudstone and sandstone deposits

Anticlinal axis- Showing dip, strike and plunge

Bridger Formation

Bridger

Formation

 Bridger

 Formation

 Sand Butte Bed of Laney

Member of Green River Formation

Hartt Cabin Bed

Maximum extent of

lake basin and

ephemeral lakes

Hartt Cabin Bed

of Laney

Member of

Green River

Formation

LaClede Bed of Laney Member of Green River Formation

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

107 ̊

108 ̊

109 ̊

EXPLANATION

Washakie Basin

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

0

0 50 KILOMETERS

50 MILES

Sand Wash Basin

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

WIND RIVER RANGE

SWEETWATER

ARCH

RAWLINS

UPLIFT Green 

River 

 Basin

BOUNDARY OF

GREATER GREEN

RIVER BASIN

WYO

MING THRUST BELT

Paleodrainage

Figure 17. Paleogeographic map of the Sand Butte Bed of the Laney Member.
24 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Gray or green flood-plain mudstone and sandstone

 deposits

Contact of stratigraphic unit

Boundary of depositional environment

Outline of Rock Springs uplift

Depositional axis 

Tan or brown freshwater lacustrine oil-shale deposits

Gray or tan lacustrine sandstone deposits

Mixed tan or gray freshwater lacustrine and

 sandstone deposits and gray or green flood-plain

 mudstone and sandstone deposits

Bridger Formation

Maximum extent of Bridger Formation

 lake basin and 

ephemeral lakes

Hartt Cabin Bed of Laney Member of Green River Formation

Bridger Formation

Washakie

Formation

LaClede Bed of

Laney Member of 

Green River

Formation

111 ̊ 110 ̊

43 ̊

42 ̊

41 ̊

107 ̊

108 ̊

109 ̊

EXPLANATION

Sand Wash Basin

Washakie Basin

UTAH

COLORADO

UTAH IDAHO

WYOMING

WYOMING

COLORADO

Green 

River 

 Basin

0

0 50 KILOMETERS

50 MILES

ROCK

SPRINGS

UPLIFT

Great Divide Basin

SIERRA MADRE

UINTA MOUNTAINS

WIND RIVER RANGE

WY

O

MING 

THR

UST BELT

SWEETWATER

ARCH

RAWLINS

UPLIFT

BOUNDARY OF

GREATER GREEN

RIVER BASIN

Figure 18. Paleogeographic map of the Hartt Cabin Bed of the Laney Member. 
Map location

R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 105 W.

R. 100 W. R. 95 W

R. 110 W.

R. 115 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R

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6885

6739.5

6705

6757.2

6800

6795 6687

6575.9

6421

6670

6421

6593

6624 6440

6507 6357

6403 6301

6280

6265

6204

6324

6228

6374

6414.3

6279 6216 6204

6243.3

6195

6262

6237.3

6234

6365

5670

6048

5951 6058

6135

6043.2

6139

6203

6230 6155

6220 6195

6224

5729

5943.2

5942

6049

6032

6215 7393

6793

5819

5793

6474

5607.6

6018 6092 6175

5586

7061.2 7099.4

6995 6970.3

7274

7440

6973

5832 6898.1

6983.6 6994

5476

5824 6834

6279

7259.1

6254

5391 6283.5

5760 5900.5

7808

7659

7984

7115

7496

5260

5521

5615

5510

5503

5101

5370.8

5513

5614

7673.6

7710.3

7977.6

5964

4090 3905

5454

5505 5529 5297

5326 5534

6735.2 7347.7

4094

3519

4123.9

3838

3789 4112

4804

5586

5788

5413 5461

T.

27

N.

T.

29

N.

T.

30

N.

T.

28

N.

T.

26

N.

T.

25

N.

T.

24

N.

T.

23

N.

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’42°00’41°30’41°00’

Elevation of the top of the LaClede Bed of the Laney Member, e

> 8,0007,751–8,0007,501–7,7507,251–7,500

7,001–7,250

6,751–7,0006,501–6,750

6,251–6,5006,001–6,2505,751–6,000

5,501–5,7505,251–5,5005,001–5,2504,751–5,000

Borehole—Number is elevation of top of LaClede Bed of th Member, in feet

!

6030

Assesssment boundary for the LeClede Bed of the Laney Member

EXPLANATION

WYOMING

0 5 10 KILOMETERS0 6

COLORADO

WYOMING

UTAH

!!!

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!

!

!

!

!

!

12 MILES

! Surface elevation 

Figure 19. Structure contour map on the top of the LaClede Bed of the Laney Member.
26 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

0 10 MILES

0

500 FEET

Sequence containing beds of trona or trona/halite

Sandstone-mudstone unit 

Sandstone, conglomerate, and mudstone, locally red-bedded

Predominantly oil shale

Predominantly marlstone and oil shale

Sandstone, marlstone and thin beds of limestone and oil shale

EXPLANATION

SOUTH NORTH

UINTA 

MOUNTAINS

Bridger Formation

LANEY MEMBER

WILKINS PEAK MEMBER

Wasatch Formation.

TIPTON SHALE MEMBER

New Fork Tongue of Wasatch Formation

Cathedral Bluffs Tongue

of Wasatch Formation

Approximate 

LaClede 

Bed of 

Roehler (1973a)

Figure 20. South to north cross section across the Green River Basin. Modified from Culbertson and 

others (1980, their pl. 1, C–C’).

Factors Affecting the Precision of OilYield Measurements

Determining the Volume of Oil in a Given 

Volume of Rock

Determining GPT from a Fischer assay is a straightforward calculation that involves the weight of the original 

sample and the volume of oil generated, both of which are routinely measured. However, this is not the case for the density 

of the sample prior to retorting which is a part of the equation that must also be known in order to calculate the amount 

of oil present in an oil shale interval over a prescribed area. 

Typically, in-place oil in the Green River Formation is given 

in the rather arcane unit of barrels of oil per acre (BPA). The 

method used to convert GPT into BPA in the previous assessment by Pitman and others (1989) was not discussed in their 

publication. An equation that computes BPA was recovered 

with the FORTRAN program that was used at the time of the 

previous assessment. This equation seemed to generate reasonable results, but there was no reference as to its origin or an 
Factors Affecting the Precision of Oil-Yield Measurements 27

explanation of how the many constants used in the equation 

were generated, so we decided not to use it. 

Stanfield and others (1954) reported summary data on 

volume-weight and oil-yield relationships from about 20,500 

USBM oil-yield analyses (table 1). Smith (1956) reported that 

oil-yield values were related to the specific gravity of the oil 

shale. Table 1 contains original values for oil yield, gallons 

per ton, as well as specific gravity and was regenerated using 

Microsoft Excel. Values for weight of oil shale, volume of oil 

shale, and oil yield per unit volume were updated using currently accepted formulas (table 2). A 3rd-order trend line with a 

R2 value of 0.9998 was generated comparing oil yield vs. specific gravity (fig. 21). As the original table (table 1) contained 

only integer values for GPT, new records were inserted to fill 

in values to one decimal place (0.1 ft) creating a new look-up 

table (Mercier, chapter 3, this report). A linear-trend series 

fill function in Microsoft Excel 2007 was then used to calculate specific gravity values for each 0.1 ft value for the GPT 

column. A 3rd-order trend line was then regenerated comparing 

new oil yield vs. specific gravity data yielding a R2 value of 

0.9997. Values for weight of oil shale, volume of oil shale, and 

oil yield per unit volume were then calculated using the new 

values for oil yield and specific gravity. The final look up table 

contained records for oil yield in GPT, specific gravity, and oil 

yield per unit volume for oil values ranging from 1.0 to 80.0 

GPT.

Shale oil resource numbers in BPA were calculated using 

the formula:

 oil shale interval thickness × 43,560 (sq. ft/ acre) × oil yield

per unit volume

from the final look-up table, containing values on a 0.1 ft 

basis / 42 (gals/barrel of oil).

Anomalously High Oil-Yield Values from 

Cuttings

In a few cases, assay results from a particular rotary hole 

appeared to give anomalously high oil-yield values based on 

data from nearby core holes or from regional oil-yield trends; 

the cause for such values is unclear so they were not included 

in the resource calculations. One possibility is that the cuttings 

were high graded prior to assaying by removing sandstone and 

siltstone chips on the assumption that they were cavings from 

above rather than from interbeds from within the oil shale.

Discrepancies Between Geophysical Logs and 

Cuttings Data

The true tops and bases of oil shale intervals, such as for 

the LaClede Bed and the Tipton Shale Member, can commonly 

be picked on geophysical logs. However, when these identified well depths are compared to those reported for cuttings, 

there is commonly a discrepancy because of the difficulty in 

accurately compensating for the time delay between when a 

particular interval is drilled through and when the cuttings 

from that interval reach the surface. For this assessment, we 

chose to use the reported tops at which the oil shale units were 

encountered in the cuttings, because using the geophysical 

log data would have resulted in portions of rich oil shale units 

being excluded in many of the holes.

Broken Core and Missing Intervals

Almost all core holes and rotary holes have missing 

intervals that are not recovered during the drilling process. 

In addition, portions of a core can be moderately to severely 

broken, and only a quantity of rubble is recovered instead of 

a continuous core. These circumstances lead to difficulties 

in properly distributing that portion of the core that is recovered over the entire interval, and consequently to determining 

the average oil yield for that interval. In any case, assigning 

oil-yield values to all the missing intervals is essential for 

calculating resources. As previously discussed, Culbertson 

and others (1980) filled in the missing data by “extrapolation 

of nearby core data or from the lithologic description of the 

unassayed core, or by using geophysical logs (sonic, neutron, 

density) where available.” Pitman and others (1989) did not 

discuss how missing intervals were handled in their assessment of the Piceance Basin; however, Janet Pitman (U.S. Geological Survey, written commun., 2008) recalled that a missing 

interval was assigned the average of the oil-yield values of the 

intervals immediately above and below the missing interval. 

John R. Donnell (U.S. Geological Survey, oral commun., 

2008), who was involved in early assessments of the Piceance 

Basin, recalled that missing intervals were assigned values 

based on nearby core holes where the intervals were not missing. Vanden Berg (Utah Geological Survey, written commun., 

2009), used both methods in his recent assessment of the Uinta 

Basin, and stated that missing intervals were assigned oil yield 

values “based on oil shale above and below and based on 

nearby wells.” 

The method used here to assign values to missing intervals was to calculate the average oil yield for the recovered 

intervals for a particular oil shale zone in a given drill hole 

and assign that average to all the missing intervals in that 

zone. Johnson and others (2010a) used this method to assign 

values to missing intervals in their recent assessment of the 

oil shale resources in the Piceance Basin of western Colorado. 

In one example, Johnson and others (2010a) determined that 

this method calculated similar average oil yield values for 

the Mahogany zone, a rich oil shale zone in the Piceance and 

Uinta Basins in five closely-spaced core holes with missing 

intervals ranging from 0 to 41.2 percent of the total zone. One 

major concern is that the richness of the oil shale affected 

the probability of it being recovered. For instance, if rich 

beds were more likely to be preserved than lean beds, then 

the calculated average oil yield for a zone would be expected 
28 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Table 1. Original volume-weight-oil yield relationships of Green River Formation oil shale. From Stanfield and 

others (1954). 

[GPT, gallons per ton, lbs/ft3, pounds per cubic foot, ft3/ton, cubic feet per ton, gal/ft3, gallons per cubic foot]

Oil yield by

assay (GPT)

Specific gravity 

of oil shale

Weight of oil 

shale (lbs/ft3

)

Volume of oil 

shale (ft3/ton)

Oil yield, per 

unit volume 

(gal/ft3

)

1 2.740 170.98 11.70 0.085

2 2.715 169.42 11.80 0.169

3 2.690 167.86 11.91 0.252

4 2.655 166.30 12.03 0.333

5 2.640 164.74 12.14 0.412

6 2.618 163.36 12.24 0.490

7 2.596 161.98 12.35 0.567

8 2.574 160.61 12.45 0.642

9 2.552 159.24 12.56 0.716

10 2.530 157.87 12.67 0.789

11 2.508 156.49 12.78 0.860

12 2.486 155.12 12.89 0.930

13 2.464 153.75 13.01 0.999

14 2.442 152.38 13.13 1.067

15 2.420 151.01 13.24 1.133

16 2.400 149.76 13.35 1.198

17 2.380 148.51 13.47 1.262

18 2.360 147.26 13.58 1.325

19 2.340 146.02 13.70 1.387

20 2.320 144.77 13.80 1.448

21 2.302 143.64 13.92 1.508

22 2.284 142.52 14.03 1.567

23 2.266 141.40 14.14 1.625

24 2.248 140.78 14.26 1.683

25 2.230 139.15 14.37 1.740

26 2.216 138.28 14.46 1.797

27 2.202 137.40 14.56 1.854

28 2.188 136.53 14.65 1.910

29 2.174 135.66 14.74 1.966

30 2.160 134.78 14.83 2.022

31 2.147 133.97 14.92 2.077

32 2.134 133.16 15.02 2.131

33 2.121 132.35 15.11 2.184

34 2.108 131.54 15.20 2.236

35 2.093 130.73 15.30 2.288

36 2.082 129.92 15.44 2.339

37 2.069 129.11 15.49 2.389

38 2.056 128.29 15.59 2.438

39 2.043 127.48 15.69 2.486

40 2.030 126.67 15.79 2.534

41 2.018 125.92 15.88 2.581
Factors Affecting the Precision of Oil-Yield Measurements 29

Table 1. Original volume-weight-oil yield relationships of Green River Formation oil shale. From Stanfield and 

others (1954).—Continued

[GPT, gallons per ton, lbs/ft3, pounds per cubic foot, ft3/ton, cubic feet per ton, gal/ft3, gallons per cubic foot]

Oil yield by

assay (GPT)

Specific gravity 

of oil shale

Weight of oil 

shale (lbs/ft3

)

Volume of oil 

shale (ft3/ton)

Oil yield, per 

unit volume 

(gal/ft3

)

42 2.006 125.17 15.98 2.628

43 1.994 124.43 16.07 2.674

44 1.982 123.68 16.17 2.720

45 1.970 122.93 16.27 2.766

46 1.959 122.24 16.36 2.811

47 1.948 121.56 16.45 2.856

48 1.937 120.87 16.55 2.901

49 1.926 120.18 16.64 2.945

50 1.915 119.50 16.74 2.938

51 1.904 118.81 16.83 3.030

52 1.893 118.12 16.93 3.071

53 1.882 117.44 17.03 3.112

54 1.871 116.79 17.12 3.152

55 1.860 116.06 17.23 3.192

56 1.849 115.38 17.33 3.231

57 1.838 114.69 17.44 3.269

58 1.827 114.00 17.54 3.306

59 1.816 113.32 17.65 3.343

60 1.805 112.63 17.76 3.379

61 1.794 111.95 17.87 3.414

62 1.783 111.26 17.98 3.449

63 1.772 110.57 18.09 3.483

64 1.761 109.89 18.20 3.516

65 1.750 109.20 18.32 3.549

66 1.740 108.58 18.42 3.582

67 1.730 107.95 18.53 3.615

68 1.720 107.33 18.63 3.648

69 1.710 106.70 18.74 3.681

70 1.700 106.08 18.85 3.713

71 1.690 105.46 18.96 3.744

72 1.680 104.83 19.08 3.774

73 1.670 104.21 19.19 3.804

74 1.660 103.58 19.31 3.833

75 1.650 102.96 19.43 3.861

76 1.640 102.34 19.54 3.889

77 1.630 101.71 19.66 3.916

78 1.620 101.09 19.78 3.943

79 1.610 100.46 19.91 3.969

80 1.600 99.84 20.03 3.994

90 1.500 93.75 21.33 4.219
30 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Table 2. Recalculated volume-weight-oil yield relationships for Green River Formation oil shale. From 

Stanfield and others (1954). 

[GPT, gallons per ton, lbs/ft3, pounds per cubic feet, ft3/ton, cubic feet per ton, gal/ft3 , gallons per cubic foot] 

Oil yield by 

assay (GPT)

Specific gravity 

of oil shale

Weight of oil 

shale (lbs/ft3

)

Volume of oil 

shale (ft3/ton)

Oil yield, per 

unit volume 

(gal/ft3

)

1 2.740 171.06 11.69 0.086

2 2.715 169.50 11.80 0.169

3 2.690 167.94 11.91 0.252

4 2.655 165.75 12.07 0.332

5 2.640 164.82 12.13 0.412

6 2.618 163.44 12.24 0.490

7 2.596 162.07 12.34 0.567

8 2.574 160.69 12.45 0.643

9 2.552 159.32 12.55 0.717

10 2.530 157.95 12.66 0.790

11 2.508 156.57 12.77 0.861

12 2.486 155.20 12.89 0.931

13 2.464 153.83 13.00 1.000

14 2.442 152.45 13.12 1.067

15 2.420 151.08 13.24 1.133

16 2.400 149.83 13.35 1.199

17 2.380 148.58 13.46 1.263

18 2.360 147.33 13.57 1.326

19 2.340 146.09 13.69 1.388

20 2.320 144.84 13.81 1.448

21 2.302 143.71 13.92 1.509

22 2.284 142.59 14.03 1.568

23 2.266 141.47 14.14 1.627

24 2.248 140.34 14.25 1.684

25 2.230 139.22 14.37 1.740

26 2.216 138.34 14.46 1.798

27 2.202 137.47 14.55 1.856

28 2.188 136.60 14.64 1.912

29 2.174 135.72 14.74 1.968

30 2.160 134.85 14.83 2.023

31 2.147 134.04 14.92 2.078

32 2.134 133.23 15.01 2.132

33 2.121 132.41 15.10 2.185

34 2.108 131.60 15.20 2.237

35 2.093 130.67 15.31 2.287

36 2.082 129.98 15.39 2.340

37 2.069 129.17 15.48 2.390

38 2.056 128.36 15.58 2.439

39 2.043 127.54 15.68 2.487
Factors Affecting the Precision of Oil-Yield Measurements 31

Table 2. Recalculated volume-weight-oil yield relationships for Green River Formation oil shale. From 

Stanfield and others (1954).—Continued

[GPT, gallons per ton, lbs/ft3, pounds per cubic feet, ft3/ton, cubic feet per ton, gal/ft3 , gallons per cubic foot]

Oil yield by 

assay (GPT)

Specific gravity 

of oil shale

Weight of oil 

shale (lbs/ft3

)

Volume of oil 

shale (ft3/ton)

Oil yield, per 

unit volume 

(gal/ft3

)

40 2.030 126.73 15.78 2.535

41 2.018 125.98 15.88 2.583

42 2.006 125.23 15.97 2.630

43 1.994 124.49 16.07 2.676

44 1.982 123.74 16.16 2.722

45 1.970 122.99 16.26 2.767

46 1.959 122.30 16.35 2.813

47 1.948 121.61 16.45 2.858

48 1.937 120.93 16.54 2.902

49 1.926 120.24 16.63 2.946

50 1.915 119.55 16.73 2.989

51 1.904 118.87 16.83 3.031

52 1.893 118.18 16.92 3.073

53 1.882 117.49 17.02 3.114

54 1.871 116.81 17.12 3.154

55 1.860 116.12 17.22 3.193

56 1.849 115.43 17.33 3.232

57 1.838 114.75 17.43 3.270

58 1.827 114.06 17.53 3.308

59 1.816 113.37 17.64 3.344

60 1.805 112.69 17.75 3.381

61 1.794 112.00 17.86 3.416

62 1.783 111.31 17.97 3.451

63 1.772 110.63 18.08 3.485

64 1.761 109.94 18.19 3.518

65 1.750 109.25 18.31 3.551

66 1.740 108.63 18.41 3.585

67 1.730 108.00 18.52 3.618

68 1.720 107.38 18.63 3.651

69 1.710 106.76 18.73 3.683

70 1.700 106.13 18.84 3.715

71 1.690 105.51 18.96 3.745

72 1.680 104.88 19.07 3.776

73 1.670 104.26 19.18 3.805

74 1.660 103.63 19.30 3.834

75 1.650 103.01 19.42 3.863

76 1.640 102.39 19.53 3.891

77 1.630 101.76 19.65 3.918
32 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Table 2. Recalculated volume-weight-oil yield relationships for Green River Formation oil shale. From 

Stanfield and others (1954).—Continued

[GPT, gallons per ton, lbs/ft3, pounds per cubic feet, ft3/ton, cubic feet per ton, gal/ft3 , gallons per cubic foot] 

Oil yield by 

assay (GPT)

Specific gravity 

of oil shale

Weight of oil 

shale (lbs/ft3

)

Volume of oil 

shale (ft3/ton)

Oil yield, per 

unit volume 

(gal/ft3

)

78 1.620 101.14 19.78 3.944

79 1.610 100.51 19.90 3.970

80 1.600 99.89 20.02 3.996

90 1.500 93.65 21.36 4.214

0.000

0.500

1.000

1.500

2.000

2.500

3.000

Oil-yield, in gallons per ton 

0 10 20 30 40 50 60 70 80 90 100

Specific Gravity 

EXPLANATION

Specific gravity

Trendline

y = -1E-06x3 + 0.0003x - 0.0265x + 2.76562

R2 = 0.9998

Figure 21. Graph showing the relationship between oil yield for Green River oil shales and 

specific gravity.
Factors Affecting the Precision of Oil-Yield Measurements 33

to increase as the percentage of missing core increases. This 

does not seem to be the case. In addition (Johnson and others, 

2010a) demonstrated that both the number of missing intervals 

and thickness of individual missing intervals are also important because a large number of thin missing intervals randomly 

distributed throughout an oil shale zone are less likely to affect 

the average for that zone than if most of the missing core is 

concentrated in a single or a few missing intervals. Clearly, as 

the percent of missing intervals increases, the probability that 

the calculated oil-yield value for a zone will deviate from the 

true oil yield also increases. To minimize this problem, only 

those drill holes where there was 30 percent or less missing 

intervals for a particular oil shale zone were included in the 

assessment calculations.

Zero Values on Assay Tables

Zero values on the assay tables (chapter 2, this report) 

could represent (1) missing intervals; (2) intervals that were 

not assayed because they consist of lithologies, such as sandstone, siltstone, mudstone, limestone, and the saline minerals 

trona and halite, that were assumed to have no oil; and (or) 

(3) intervals that were assayed but produced no oil. As previously discussed, any missing interval in a particular oil shale 

zone was ascribed the average assay values of all core or 

cuttings for that zone, thus the missing intervals are assumed 

to have had “average” oil yields for that zone. If, however, 

an interval with a zero oil yield was assayed but produced no 

oil or was not assayed because it was assumed to have no oil, 

then assigning the average oil yield for the entire zone to that 

interval would artificially inflate the resource calculations for 

that zone.

 When a sample is analyzed using Fischer assay, it will 

invariably yield some water even if no oil is produced. Of the 

47,003 samples analyzed for the Greater Green River Basin, 

10,864 listed zero oil recovered. Of these, 4,681 reported that 

some water was recovered, and it is assumed that these were 

assayed samples that yielded zero oil. These were given a 

minimum oil-yield value of 0.0001 GPT to distinguish them 

from the first two possibilities. 

A large number of intervals with zero oil and zero water 

listed in the assay tables were apparently not assessed because 

they contain little or no kerogen. An examination of available sample descriptions revealed that many zero values 

corresponded to intervals in which sandstone, siltstone, and 

mudstone had been recovered. Unfortunately, sample descriptions were not recovered for many of the drill holes that were 

assayed, so other methods had to be used to try to identify 

unassessed intervals. 

The Tipton Shale Member is subdivided into the Rife and 

Scheggs Beds, separated by the Farson Sandstone Member 

of the Green River Formation (fig. 3), a clastic-rich, kerogenpoor interval. The Rife and Scheggs Beds consist of nearly 

continuous oil shale, and it is likely that zero oil-yield values 

in these units represent missing intervals instead of unassessed 

intervals. These intervals were assumed to be missing and 

were assigned the average GPT value of the recovered samples. The Farson Sandstone, however, appears to have rarely 

been assessed, as the assay results for that interval list mainly 

zero oil and water yield values. For simplicity, we eliminated 

the entire Farson interval from the assessment of the Tipton. 

Similarly, the LaClede Bed of the Laney Member consists mainly of oil shale, and any zero values were assumed 

to be missing intervals and assigned the average GPT value 

of the recovered samples. The LaClede Bed also contains a 

kerogen-poor clastic-rich zone, the buff marker bed, confined 

largely to the Washakie Basin. Like the Farson Sandstone, the 

carbonate marker appears to have been rarely assessed, and 

the interval was not included in the assessment of the LaClede 

Bed. Thus the Tipton Shale and the LaClede Bed both have 

clastic intervals that were not included when calculating the 

estimated GPT values for these zones. Had these clastic intervals been included the GPT values for the Tipton and LaClede 

would have been significantly lower. The BPA values for these 

assessed units should not be greatly affected by the omission 

of these clastic intervals as they contain little oil shale.

The Wilkins Peak Member throughout much of its extent 

consists of complexly interbedded oil shale and kerogen-poor 

lithologies such as sandstone, siltstone, mudstone, limestone, 

trona, and halite. Available sample descriptions and geophysical logs indicate that the majority of the intervals with zero oil 

and and water yields were not assessed rather than missing. 

The highest percentage of reported zero oil and water yield 

values is in the upper part of the Wilkins Peak near its western 

limit in the western part of the Green River Basin, where that 

part of the member grades into the Cathedral Bluffs Tongue of 

the Wasatch Formation (fig. 3). This “transitions zone”, which 

contains minor thin oil shale beds interbedded with kerogenpoor rocks, was excluded from the Wilkins Peak and thus was 

not assessed. Figure 22 shows the percent of missing core in 

drill holes of the assessed part of the Wilkins Peak, generally 

18 percent or less, except for six with 19 to 29 percent. All of 

the remaining zero GPT values reported within the assessed 

area were assumed to be missing intervals rather than nonanalyzed intervals and thus were assigned the average GPT 

for the recovered Wilkins Peak core in that drill hole. By using 

this assumption, the in-place oil shale resources in the Wilkins 

Peak could possibly have been overestimated by some small 

amount. However, GPT values for the six drill holes with the 

highest missing percentages are similar to nearby drill holes 

with much smaller percentages of missing intervals, so it is 

unlikely that this overestimation is large. This is clearly an 

imperfect process for evaluating resources; the results could 

be improved if additional sample descriptions are obtained in 

the future.

Problems Related to Saline Minerals

The Wilkins Peak Member contains significant thicknesses of trona and halite beds throughout much of the Green 
Map location R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R. 

4 2 2 33 1 1 1 6 1 1 3 2 5 92 122 227 5 2 4 1 3 2 3 2 13 1 1 13 1 4 11 7 1 9 3 1 1 1 7 10 9 61 7 2 1 1 12 0.4 20 10 10 1.6 10 40 10 1.3 20 5 0.3 0.5 6 3 30 1.225 68 10 2.5 18.2 1.3 22 1.3 10 60 3.7 70 51.2 10 10 6620 20 60 20 80 20 1 60 20 50 10 89.5 1.5 70 24.5 10 10 30 10 46.4 

T. 28N. T. 29N. T. 30N. 

110°30' 110°00' 109°30' 109°00' 108°30' 108°00

42°30' 42°00' 41°30' 41°00' 0 6 12 MILES WYOMING 0 5 10 KILOMETERS

COLORADO

EXPLANATION

Missing core in Wilkins Peak Memb in percent

19–29

11–186–103–50–2

WYOMING

UTAH

Figure 22. Percent missing intervals in the control points used to assess the Wilkins Peak Member.
Methods Used to Generate Isopach Maps and Isoresource Maps 35

River Basin that needed to be identified prior to making 

resource calculations. Sample descriptions of core holes indicate that trona and halite beds were commonly not analyzed. 

These beds were assigned minimum GPT value of 0.0001 GPT 

to distinguish them from missing intervals. In rotary holes, 

however, it is likely that all of the halite and much of the trona 

dissolved out of the cuttings before reaching the surface. Thus, 

the cuttings collected for these intervals would be largely from 

oil shale beds interbedded with the trona and halite and (or) oil 

shale cavings from above. Fischer assay analysis of intervals 

where geophysical logs indicated the presence of thick trona 

and halite beds commonly yielded significant oil apparently 

from the thin oil shale interbeds and oil shale cavings. There 

is no apparent way to precisely compensate for the dissolved 

trona and halite beds in these rotary holes, so we decided to 

simply calculate the percent of the total thickness that the 

trona and halite beds represented, and subtract that percent 

from the total BPA calculation for that hole. 

Methods Used to Generate Isopach 

Maps and Isoresource Maps

Pitman and others (1989), in their assessment of the 

Piceance Basin, used geostatistical interpolation by kriging to 

generate their resource maps and resource numbers. According to them, statistical tests that were done prior to kriging 

indicated that oil shale resource values were “statistically 

homogeneous” or that BPA resource values for oil shale core 

holes spaced a short distance apart tended to be more alike 

than values for core holes that were farther apart. Pitman and 

others (1989) used a computer program called BLUEPACK to 

determine that variations in oil yield were linear for all of the 

oil shale zones except for two. For these two zones there was 

a significant amount of variation that could not be predicted 

from available data and a “nugget-only” model was used to try 

to capture this variability. Pitman and others (1989) determined that universal kriging gave good results in areas with 

good control, but in areas with little control such as basin-margin areas, universal kriging calculated anomalously large error 

limits—as much as nearly 1,300 percent,—and several townships had insufficient control for universal kriging to calculate 

any resource numbers. They manually determined in-place oil 

shale resources using isoresource contours and compared the 

results with those obtained from kriging. Their results were 

comparable for areas with good control, but for areas with limited control, such as the basin-margin areas, universal kriging 

greatly overestimated resources. For example, in the township 

with the approximately 1,300 percent error, kriging estimated 

1.1 billion barrels of oil in place for one of the oil shale zones 

in the Piceance Basin, while hand contouring estimated only 

219 million barrels. 

We chose to use an RBF-multiquadric function instead 

of kriging as it facilitated a more rapid generation of models 

while providing better results than kriging in the areas with 

little data. The Inverse Distance Weighted (IDW) method was 

also tried. Both the RBF method and IDW method gave fairly 

similar results in areas with large numbers of control points, 

but the RBF method seemed to generate more reasonable 

results in marginal areas with little control. The RBF-multiquadric function in ESRI’s Geostatistical Analyst provided 

a quick, exact interpolator, and kept the model within our 

methodology’s native software format (ESRI’s ArcGIS). Rusu 

and Rusu (2006) recently demonstrated that “soft computing methods” such as Radial Basis Functions (RBF) compare 

favorably with conventional “hard computing methods” such 

as kriging, and compared results when the RBF method and 

kriging were applied to the same data set. They cited a recent 

study in which the Radioactivity Environmental Monitoring 

Group of the Institute for Environment and Sustainability 

at the Joint Research Center of the European Commission 

invited participants to apply both RBF and kriging to a data set 

depicting variations in daily mean values of gamma-ray doses 

in southwestern Germany. Part of the data points were hidden, 

and the participants were asked to estimate values at these 

hidden locations using the data points given. In general, both 

the RBF method and kriging were equally good at predicting 

the correct results, except for areas with limited data where a 

proper variogram required for kriging is difficult to construct. 

In these areas, the RBF method gave better results. According 

to Rusu and Rusu (2006, p. 126) “The results and the execution time are quite similar for RBF and kriging, but the ease of 

use of RBF is overwhelming, compared to the use of kriging. 

When using RBF, the user has to choose only the radial functions type and the smoothing parameter. When using kriging, 

complex variogram modeling has to be done.” The problems 

with generating a proper variogram with limited data may be 

in part why, in the previous assessment by Pitman and others 

(1989) kriging gave values with unacceptable margins of error 

for areas with limited data.

The RBF method in ESRI’s GeoStatistical Analyst (GA) 

is an exact interpolator that will honor all data points and not 

introduce errors at those data point locations unless a smoothing function is used. If a smoothing function is used, the RBF 

can also extrapolate values above or below the actual values 

outside the data point locations. The final resource models 

were created with the RBF method using a sampling method 

containing eight moving window sectors with eight neighbors 

in each sector. No smoothing function was used. After numerous iterations, we determined that the RBF method using these 

parameters yields surfaces that we believe to best fit geologic 

relations. 

Although the RBF method does not generate as complete 

an error estimate as kriging it does give the difference between 

the predicted and measured value for each control point, as 

well as the overall error for an entire map. To obtain the difference between the predicted value and the measured value, the 

RBF method predicts a value at a given control point from the 

eight nearest control points without knowing the actual value 

measured at that control point. That predicted value is then 
36 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

compared with the measured value, and the difference between 

the two is calculated. 

Four maps were generated for each oil shale zone 

assessed: (1) an isopach map, ( 2) variations in oil yield 

in GPT, (3) variations in BPA, and (4) total in-place oil in 

each 36 square mile township in the basin. The barrels-pertownship maps were generated by first intersecting the Greater 

Green River Basin township polygon file with the outcrop 

polygon files. The resultant files included only those townships or parts of townships that are underlain by the oil shale 

zones to be assessed. Using ESRI’s Spatial Analyst’s Zonal 

Statistics function, we were able to quantify each township 

in each BPA resource model (cell size = 1 acre) by using 

each “clipped” township polygon (the result of intersecting 

the township polygon with the outcrop polygon) as the zone 

to quantify. In short, the function totals the sum of all of the 

one-acre cells contained by each polygon to be assessed in the 

zone dataset. The resultant summary table (table 3) contains a 

sum total of barrels for each township, as well as several other 

statistics. Maps were then generated by joining the summary 

table to each zone polygon file. For a more complete explanation of this procedure see Mercier and others (this report).

Assessment Results

An assessment is presented here of all oil shale regardless of grade in the Tipton Shale Member, the Wilkins Peak 

Member and the LaClede Bed of the Laney Member in the 

Green River and Washakie Basins of the Greater Green River 

Basin (fig. 2). The oil shale resources in the Great Divide and 

Sand Wash Basins were not assessed because surface sections (Roehler, 1989a, d, e) and the limited Fischer assay data 

available indicate that only very low-grade oil shale is present 

there. No attempt was made to estimate the amount of oil that 

is economically recoverable, largely because there has yet 

to be a process developed to recover oil economically from 

Green River oil shale. Estimates of the amount of shale oil that 

is technically recoverable without considering economics have 

been made for the Piceance Basin of western Colorado but not 

for the Greater Green River Basin. Estimates for the Piceance 

Basin using underground room-and pillar mining methods 

vary from 45 percent (Taylor, 1987) to 55 to 75 percent (Prien, 

1974) and as high as 80 percent for open pit mining (Taylor, 

1987). Recoveries will be likely lower in the Greater Green 

River Basin, if indeed production does take place, because 

most of the oil shale in the Wilkins Peak Member (fig. 3) is 

interbedded with barren rock. At present, there are no estimates of the percent of the resource that could be recovered 

using the in-situ methods that are currently being developed. 

However, Taylor (1987) stressed that the amount of oil that 

can be recovered from any in-situ process depends on both the 

percent of oil that can be recovered from within the retort and 

the amount of oil left behind in the spaces between retorts. The 

in-situ method, currently being developed by Shell Exploration and Development in the Piceance Basin (Vinigar, 2006), 

uses a freeze wall to isolate the in-situ retort, and it would 

probably not be possible to recover oil in the area occupied 

by the freeze walls. The dimensions of the freeze wall that 

Shell will ultimately use in commercial retorts have not been 

established.

Although it is not feasible to estimate volumes of 

economically recoverable shale oil at this time, our primary 

goals here is to provide basic geologic and resource data that 

will facilitate the making of such estimates once extraction 

methods are developed. For instance, Mercier and others (this 

report) calculate cubic meters of overburden on the Laney and 

Tipton Shale Members. These calculations can be integrated 

with estimates of in place oil to generate “strip ratio” maps 

for strip mining the oil shale. For each of the three units of the 

Green River Formation included in this assessment in ascending order: the Tipton Shale Member, Wilkins Peak Member, 

and LaClede Bed of the Laney Member, four maps were generated: (1) isopach map, (2) isoresource map showing variations in GPT, (3) isoresource map showing variations in BPA, 

and (4) isoresource map showing total amount of in-place oil 

in each 36-square mile township. Figure 23 is an isopach map 

that includes all three assessed units, as well as the thick, unassessed clastic-rich intervals of the Farson Sandstone Member 

of the Green River Formation and the Cathedral Bluffs Tongue 

of the Wasatch Formation (fig. 3). Only in the southeastern 

part of the Green River Basin do all three assessed oil shale 

units occur in a continuous stratigraphic sequence, but even 

in this limited area there are numerous sandstone, siltstone, 

and mudstone units within the Wilkins Peak Member. The 

isopach interval thickens from 750 ft in the northern part of 

the Green River Basin to more than 2,200 ft in the southern 

part of the Green River Basin adjacent to the Uinta Mountains, 

and reaches a maximum of 3,360 ft in the central part of the 

Washakie Basin (fig. 23). The southward and southeastward 

thickening of this interval is largely due to increased subsidence in those directions. In addition, the upper contact of the 

LaClede Bed climbs stratigraphically to the south and southeast as northward-thickening units of mainly volcaniclastics 

rocks wedge out (pl. 1, fig. 20, sandstone, marlstone, and thin 

beds of limestone and oil shale facies).

Tipton Shale Member

The Tipton Shale Member is assessed as a single unit and 

not subdivided into the Scheggs and Rife Beds. This is in large 

part because the Farson Sandstone Member, which separates 

the Scheggs and Rife Beds, is thin or absent throughout much 

of the Green River and Washakie Basins, and in these areas it 

is difficult to distinguish between the Scheggs and Rife Beds 

in the subsurface. The base of the member as mapped by 

Tweto (1979) and Love and Christiansen (1985), was used to 

define its extent in the Washakie Basin and along the eastern 

margin of the Green River Basin. The base of the Wilkins 

Peak Member, as mapped by Love and Christiansen (1985), 

is used to define the extent of the Tipton in the western part 
Assessment Results 37

Table 3. In-place oil resources, in barrels of oil, in the Green River Formation, Greater Green River Basin, Wyoming.

Township Range Tipton Wilkins Peak LaClede Township

T29N R108W 0 118,371,000 0 118,371,000

T29N R107W 0 47,217,400 0 47,217,400

T28N R112W 0 364,673 55,265 419,938

T28N R111W 0 162,311,000 21,241,900 183,552,900

T28N R110W 567,039,000 983,327,000 0 1,550,366,000

T28N R109W 703,808,000 1,019,430,000 0 1,723,238,000

T28N R108W 0 764,592,000 0 764,592,000

T28N R107W 0 634,965,000 0 634,965,000

T27N R112W 0 189,180,000 29,545,100 218,725,100

T27N R111W 0 1,185,690,000 164,510,000 1,350,200,000

T27N R110W 940,662,000 1,869,190,000 0 2,809,852,000

T27N R109W 944,541,000 1,983,820,000 0 2,928,361,000

T27N R108W 0 1,507,820,000 0 1,507,820,000

T27N R107W 0 1,411,850,000 386,140,000 1,797,990,000

T27N R106W 0 1,179,830,000 347,082,000 1,526,912,000

T27N R105W 0 1,375,840,000 397,413,000 1,773,253,000

T27N R104W 0 0 121,845,000 121,845,000

T26N R112W 0 423,138,000 77,620,800 500,758,800

T26N R111W 0 1,304,840,000 235,771,000 1,540,611,000

T26N R110W 794,690,000 1,633,470,000 346,832,000 2,774,992,000

T26N R109W 821,072,000 2,399,880,000 466,563,000 3,687,515,000

T26N R108W 0 2,670,630,000 562,789,000 3,233,419,000

T26N R107W 0 2,481,340,000 674,743,000 3,156,083,000

T26N R106W 358,551,000 2,244,360,000 578,356,000 3,181,267,000

T26N R105W 174,846,000 2,253,530,000 536,132,000 2,964,508,000

T26N R104W 0 0 473,514,000 473,514,000

T25N R112W 364,385,000 968,957,000 147,107,000 1,480,449,000

T25N R111W 480,018,000 1,799,530,000 314,869,000 2,594,417,000

T25N R110W 591,912,000 2,020,850,000 502,032,000 3,114,794,000

T25N R109W 548,298,000 3,070,010,000 612,637,000 4,230,945,000

T25N R108W 774,453,000 5,000,210,000 877,371,000 6,652,034,000

T25N R107W 723,634,000 4,444,390,000 821,023,000 5,989,047,000

T25N R104W 0 2,470,920,000 648,569,000 3,119,489,000

T25N R105W 155,270,000 3,406,710,000 723,947,000 4,285,927,000

T25N R103W 0 189,488,000 0 189,488,000

T25N R106W 326,532,000 3,864,680,000 724,874,000 4,916,086,000

T24N R112W 640,307,000 1,965,960,000 265,792,000 2,872,059,000

T24N R111W 580,023,000 2,489,040,000 423,959,000 3,493,022,000

T24N R110W 434,462,000 3,625,670,000 478,522,000 4,538,654,000

T24N R109W 315,678,000 4,988,040,000 1,260,550,000 6,564,268,000

T24N R108W 717,101,000 5,307,110,000 1,550,220,000 7,574,431,000

T24N R107W 756,340,000 4,182,100,000 1,089,590,000 6,028,030,000

T24N R104W 0 614,855,000 166,798,000 781,653,000

T24N R105W 157,872,000 3,683,760,000 783,550,000 4,625,182,000

T24N R106W 474,460,000 4,665,350,000 971,158,000 6,110,968,000
38 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Table 3. In-place oil resources, in barrels of oil, in the Green River Formation, Greater Green River Basin, Wyoming.—Continued

Township Range Tipton Wilkins Peak LaClede Township

T23N R112W 793,128,000 2,663,720,000 304,983,000 3,761,831,000

T23N R109W 732,497,000 7,191,740,000 1,120,420,000 9,044,657,000

T23N R110W 636,501,000 5,313,160,000 658,092,000 6,607,753,000

T23N R105W 166,240,000 5,044,030,000 1,042,370,000 6,252,640,000

T23N R106W 919,517,000 7,391,330,000 1,126,240,000 9,437,087,000

T23N R107W 1,473,040,000 5,947,250,000 1,536,340,000 8,956,630,000

T23N R111W 713,382,000 3,201,840,000 447,111,000 4,362,333,000

T23N R108W 993,281,000 8,087,850,000 1,762,860,000 10,843,991,000

T22N R112W 805,259,000 3,229,930,000 0 4,035,189,000

T22N R111W 914,680,000 4,097,450,000 0 5,012,130,000

T22N R110W 956,437,000 5,480,680,000 814,455,000 7,251,572,000

T22N R105W 464,511,000 4,505,770,000 1,009,700,000 5,979,981,000

T22N R106W 1,820,580,000 8,837,310,000 1,471,140,000 12,129,030,000

T22N R107W 2,695,680,000 8,106,310,000 1,471,410,000 12,273,400,000

T22N R108W 1,654,720,000 8,291,250,000 1,122,970,000 11,068,940,000

T22N R109W 1,093,570,000 7,025,720,000 924,211,000 9,043,501,000

T21N R112W 944,487,000 4,108,300,000 0 5,052,787,000

T21N R111W 1,402,360,000 4,645,230,000 0 6,047,590,000

T21N R110W 1,547,710,000 5,942,400,000 534,469,000 8,024,579,000

T21N R109W 1,578,250,000 8,298,960,000 688,156,000 10,565,366,000

T21N R108W 1,978,500,000 9,803,840,000 873,463,000 12,655,803,000

T21N R107W 2,154,980,000 9,943,940,000 1,442,790,000 13,541,710,000

T21N R106W 2,575,180,000 8,351,110,000 2,045,170,000 12,971,460,000

T21N R105W 1,354,860,000 3,154,240,000 1,035,890,000 5,544,990,000

T20N R113W 691,468,000 4,709,110,000 0 5,400,578,000

T20N R112W 1,244,620,000 5,289,080,000 0 6,533,700,000

T20N R111W 2,112,160,000 4,631,450,000 273,540,000 7,017,150,000

T20N R110W 2,472,840,000 7,435,490,000 539,873,000 10,448,203,000

T20N R109W 2,272,600,000 13,158,600,000 778,710,000 16,209,910,000

T20N R107W 2,707,450,000 10,311,200,000 2,699,300,000 15,717,950,000

T20N R106W 3,416,220,000 5,640,800,000 2,507,170,000 11,564,190,000

T20N R105W 376,586,000 292,160,000 118,184,000 786,930,000

T20N R108W 2,277,180,000 17,353,600,00 1,312,040,000 20,942,820,000

T19N R113W 615,626,000 5,708,720,000 0 6,324,346,000

T19N R112W 1,286,320,000 7,335,280,000 50,875,500 8,672,475,500

T19N R111W 2,751,080,000 6,518,500,000 417,838,000 9,687,418,000

T19N R109W 3,094,890,000 14,722,300,00 1,422,870,000 19,240,060,000

T19N R110W 3,415,140,000 8,993,320,000 889,339,000 13,297,799,000

T19N R108W 2,853,190,000 17,088,600,00 2,034,990,000 21,976,780,000

T19N R107W 3,171,760,000 11,358,600,00 2,578,470,000 17,108,830,000

T19N R106W 3,559,460,000 8,704,130,000 2,264,880,000 14,528,470,000

T19N R105W 646,397,000 817,385,000 269,759,000 1,733,541,000

T19N R97W 373,225,000 0 0 373,225,000

T19N R94W 1,001,430,000 0 0 1,001,430,000

T19N R95W 2,167,270,000 0 0 2,167,270,000
Assessment Results 39

Table 3. In-place oil resources, in barrels of oil, in the Green River Formation, Greater Green River Basin, Wyoming.—Continued

Township Range Tipton Wilkins Peak LaClede Township

T19N R96W 1,734,000,000 0 0 1,734,000,000

T18N R113W 1,370,600,000 5,571,100,000 0 6,941,700,000

T18N R112W 2,201,250,000 6,677,730,000 112,916,000 8,991,896,000

T18N R111W 3,865,510,000 7,404,940,000 796,567,000 12,067,017,000

T18N R109W 3,798,490,000 14,240,100,00 2,637,050,000 20,675,640,000

T18N R110W 4,756,560,000 10,307,000,00 2,254,900,000 17,318,460,000

T18N R108W 3,076,960,000 14,961,800,00 2,826,470,000 20,865,230,000

T18N R107W 3,413,290,000 6,972,110,000 2,068,050,000 12,453,450,000

T18N R106W 2,921,200,000 3,004,000,000 585,228,000 6,510,428,000

T18N R105W 13,030,800 0 0 13,030,800

T18N R98W 360,180,000 0 11,752,900 371,932,900

T18N R97W 2,700,400,000 0 1,404,010,000 4,104,410,000

T18N R94W 2,301,010,000 0 0 2,301,010,000

T18N R93W 155,992,000 0 0 155,992,000

T18N R95W 3,286,470,000 0 0 3,286,470,000

T18N R96W 3,428,610,000 0 2,575,320,000 6,003,930,000

T17N R113W 2,254,450,000 4,677,370,000 30,926,300 6,962,746,300

T17N R112W 3,769,110,000 5,153,430,000 353,822,000 9,276,362,000

T17N R111W 5,247,060,000 6,662,620,000 1,293,510,000 13,203,190,000

T17N R110W 5,548,620,000 9,974,220,000 2,868,580,000 18,391,420,000

T17N R109W 4,111,750,000 13,645,200,00 3,409,900,000 21,166,850,000

T17N R108W 3,586,250,000 16,458,700,00 3,054,030,000 23,098,980,000

T17N R107W 4,585,560,000 10,432,800,00 3,056,280,000 18,074,640,000

T17N R106W 2,835,760,000 12,590,900 2,883,760 2,851,234,660

T17N R100W 235,093,000 0 11,922,000 247,015,000

T17N R99W 1,843,090,000 0 171,965,000 2,015,055,000

T17N R98W 2,517,620,000 0 2,646,740,000 5,164,360,000

T17N R97W 3,324,440,000 0 3,976,900,000 7,301,340,000

T17N R94W 1,537,990,000 0 0 1,537,990,000

T17N R93W 510,771,000 0 0 510,771,000

T17N R96W 4,098,010,000 0 3,932,250,000 8,030,260,000

T17N R95W 3,351,260,000 0 3,447,080,000 6,798,340,000

T16N R113W 3,075,390,000 3,616,660,000 312,939,000 7,004,989,000

T16N R112W 4,209,960,000 3,563,380,000 765,435,000 8,538,775,000

T16N R111W 6,047,200,000 6,058,530,000 1,691,340,000 13,797,070,000

T16N R110W 6,106,510,000 8,921,940,000 2,758,660,000 17,787,110,000

T16N R109W 4,556,530,000 10,939,600,000 3,561,850,000 19,057,980,000

T16N R108W 4,077,520,000 10,902,000,000 4,043,240,000 19,022,760,000

T16N R107W 4,359,320,000 4,993,070,000 2,090,310,000 11,442,700,000

T16N R106W 1,813,750,000 0 0 1,813,750,000

T16N R100.5 654,163 0 0 654,163

T16N R100W 1,484,400,000 0 3,450,770,000 4,935,170,000

T16N R99W 2,690,670,000 0 7,309,480,000 10,000,150,000

T16N R98W 3,135,460,000 0 7,892,140,000 11,027,600,000

T16N R96W 4,455,430,000 0 6,175,040,000 10,630,470,000
40 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Table 3. In-place oil resources, in barrels of oil, in the Green River Formation, Greater Green River Basin, Wyoming.—Continued

Township Range Tipton Wilkins Peak LaClede Township

T16N R97W 3,836,310,000 0 7,078,270,000 10,914,580,000

T16N R95W 2,811,110,000 0 4,655,720,000 7,466,830,000

T16N R94W 750,275,000 0 2,019,790,000 2,770,065,000

T16N R93W 320,025,000 0 1,466,460 321,491,460

T16N R92W 22,227,700 0 0 22,227,700

T15N R112W 4,640,330,000 2,868,270,000 1,146,440,000 8,655,040,000

T15N R111W 6,078,260,000 5,484,680,000 1,804,660,000 13,367,600,000

T15N R110W 6,565,230,000 7,891,340,000 2,795,220,000 17,251,790,000

T15N R109W 5,223,050,000 9,739,810,000 3,537,150,000 18,500,010,000

T15N R108W 4,615,580,000 9,605,490,000 4,590,050,000 18,811,120,000

T15N R107W 4,471,050,000 5,676,700,000 2,893,380,000 13,041,130,000

T15N R113W 3,075,170,000 2,402,210,000 575,103,000 6,052,483,000

T15N R106W 2,927,100,000 884,462,000 424,779,000 4,236,341,000

T15N R101W 596,454,000 0 0 596,454,000

T15N R100.5 42,345,200 0 0 42,345,200

T15N R100W 3,531,500,000 0 4,019,350,000 7,550,850,000

T15N R99W 3,918,240,000 0 10,112,400,000 14,030,640,000

T15N R98W 3,626,860,000 0 10,715,000,000 14,341,860,000

T15N R97W 3,765,790,000 0 10,000,900,000 13,766,690,000

T15N R96W 3,329,130,000 0 7,478,500,000 10,807,630,000

T15N R95W 0 0 5,600,990,000 5,600,990,000

T15N R94W 0 0 4,139,440,000 4,139,440,000

T15N R93W 0 0 1,380,870,000 1,380,870,000

T14N R112W 3,645,780,000 2,966,840,000 1,249,240,000 7,861,860,000

T14N R111W 4,264,060,000 4,279,390,000 1,965,630,000 10,509,080,000

T14N R108W 4,907,040,000 9,703,760,000 4,546,940,000 19,157,740,000

T14N R107W 4,822,490,000 7,752,330,000 4,023,480,000 16,598,300,000

T14N R110W 4,871,570,000 6,678,950,000 3,317,750,000 14,868,270,000

T14N R109W 5,192,870,000 9,240,780,000 4,457,840,000 18,891,490,000

T14N R106W 4,337,120,000 651,988,000 332,465,000 5,321,573,000

T14N R105W 740,429,000 0 0 740,429,000

T14N R113W 2,313,190,000 2,887,030,000 660,602,000 5,860,822,000

T14N R100W 3,260,940,000 0 358,705,000 3,619,645,000

T14N R99W 4,111,950,000 0 8,218,970,000 12,330,920,000

T14N R98W 2,886,920,000 0 10,532,500,000 13,419,420,000

T14N R97W 2,262,140,000 0 11,541,600,000 13,803,740,000

T14N R96W 2,097,770,000 0 9,887,620,000 11,985,390,000

T14N R95W 0 0 6,801,990,000 6,801,990,000

T14N R94W 0 0 5,589,650,000 5,589,650,000

T14N R93W 0 0 5,005,050,000 5,005,050,000

T14N R92W 0 0 572,058,000 572,058,000

T13N R111W 2,504,850,000 2,386,970,000 1,500,270,000 6,392,090,000

T13N R110W 3,631,030,000 5,052,830,000 3,219,030,000 11,902,890,000

T13N R112W 1,715,410,000 2,575,270,000 912,083,000 5,202,763,000
Assessment Results 41

Table 3. In-place oil resources, in barrels of oil, in the Green River Formation, Greater Green River Basin, Wyoming.—Continued

Township Range Tipton Wilkins Peak LaClede Township

T13N R108W 4,612,720,000 8,757,290,000 4,735,060,000 18,105,070,000

T13N R109W 4,480,920,000 7,791,190,000 4,657,260,000 16,929,370,000

T13N R107W 0 2,974,070,000 1,617,100,000 4,591,170,000

T13N R113W 1,243,750,000 3,203,940,000 0 4,447,690,000

T13N R100W 1,333,210,000 0 0 1,333,210,000

T13N R99W 2,017,270,000 0 3,652,090,000 5,669,360,000

T13N R98W 1,663,890,000 0 9,644,310,000 11,308,200,000

T13N R97W 1,178,630,000 0 10,951,600,000 12,130,230,000

T13N R96W 1,168,570,000 0 10,172,100,000 11,340,670,000

T13N R95W 0 0 7,763,970,000 7,763,970,000

T13N R94W 0 0 5,147,800,000 5,147,800,000

T13N R93W 0 0 1,188,330,000 1,188,330,000

T13N R92W 0 0 80,333,000 80,333,000

T12N R111W 0 1,564,730,000 1,087,430,000 2,652,160,000

T12N R112W 0 1,432,400,000 631,477,000 2,063,877,000

T12N R109W 0 3,167,760,000 2,032,660,000 5,200,420,000

T12N R108W 0 2,032,600,000 1,215,810,000 3,248,410,000

T12N R110W 0 2,833,810,000 1,980,000,000 4,813,810,000

T12N R107W 0 19,232,200 11,182,300 30,414,500

T12N R99W 717,026,000 0 0 717,026,000

T12N R98W 708,072,000 0 0 708,072,000

T12N R97W 529,838,000 0 0 529,838,000

T12N R96W 475,228,000 0 0 475,228,000

Total 377,184,520,285 1,444,991,951,321 362,816,116,863 704,991,314,173
R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R. 

Map location 750 1080 970 655 810 950950 710690 750 580 810 761 820 747.2 840 790 770 900 850 810 904.6 1530 720 1020 850 910 1150.1 1090 1480 1310 1440 1223.5 1640 1449.9 1270 2680 1880 1910 1950 1411.5 1580 3160 1810 1950 1790 1810 1650.8 2378.7 3360 2220 1500 1280 

T. 28N. T. 29N. T. 30N. 

110°30' 110°00' 109°30' 109°00' 108°30' 108°00' 

42°30' 42°00' 41°30' 41°00' 0 6 12 MILES EXPLANATION Base of Tipton Shale Member to top La

 thickness in feet > 2,000 1,501–2,000 1,001–1,500 

COLORADO

WYOMING

UTAH

0 5 10 KILOMETERS

WYOMING

Figure 23. Isopach map of the total assessed interval in the Green River Basin.
Assessment Results 43

of the Green River Basin where the base of the Tipton has not 

been mapped. In the northern part of the Green River Basin 

(fig. 3), the base of the Laney Member, as mapped by Love 

and Christiansen (1985) was used, as the base of the Tipton 

has not been mapped there. According to Roehler (1992b), the 

top of the Rife Bed is close to the base of the Laney in that 

area (fig. 12). 

The top and base of the Tipton, as defined by us in the 

Washakie Basin, are stratigraphically different than those of 

Roehler (1989d, e). He picked his contacts based on his concepts concerning the development of Lake Gosiute, whereas 

we chose contacts that would best characterize the oil shale 

deposit. Roehler (1989d, e) included an interval of lacustrine 

shale with low oil yields in the lower part of his Tipton that 

we excluded because it does not contain significant oil shale; 

if included, it would have significantly lowered the average oil 

yield of the Tipton Shale Member in the Washakie Basin. An 

oil shale sequence immediately overlying the Tipton as defined 

by Roehler (1989d, e) in the Washakie Basin, was included 

by him in the overlying Wilkins Peak Member because he 

believed it to be genetically related to the Wilkins Peak phase 

of the lake. This sequence forms a single unbroken oil shale 

sequence with the underlying Tipton Shale, and we included it 

in the Tipton for assessment purposes. 

Figure 24 is an isopach map of the Tipton Shale Member. In the Washakie Basin, it is 310 to 390 ft thick along a 

northeast-trending area that includes the deep trough of the 

basin and a portion of the southwest basin margin. In the 

Green River Basin, it varies in an irregular fashion from 128 

to over 400 ft thick. The Tipton thickens to as much as 411 ft 

in the northern part of the Green River Basin as a result of the 

northward thickening of the Farson Sandstone Member, which 

separates the Rife Bed and Scheggs Beds of the Tipton (fig. 3). 

The Farson thickens to the north across the Green River Basin 

from a minimum of less than 5 ft in the southeast part to a 

maximum of 790 ft in the northern part (figs. 8, 12). The Rife 

Bed, however, could only be recognized locally in the northern 

part of the Green River Basin. Where the Rife bed is absent, 

the Tipton consists of only the Scheggs Bed and thins to as 

little as 20 ft (fig. 24). 

A total of 18 core holes and 65 rotary holes were used in 

assessing the oil shale resources in the Tipton Shale Member 

(fig. 24); total area assessed is 5,088 mi2

, which excluded 

some basin margin areas where control is sparse (fig. 24). As 

previously discussed, the Farson Sandstone Member where 

present was subtracted from the Tipton Shale Member interval 

and not assessed. Figure 25 is an isoresource map showing 

variations in GPT; oil yields are generally greater than 15 GPT 

throughout much of Green River Basin, reaching a maximum 

of 22.3 GPT in the south-central part. Oil yields decrease to 

the north across the Green River Basin with values reaching 

a minimum of less than 7.5 GPT in the northern part of the 

Basin (fig. 25). Oil yields in the Washakie Basin vary from 

1.2 to 11.5 GPT, with the highest values along the northwest 

margin of the basin. Total in-place oil (1) reaches a maximum 

of 345,000 BPA in the south-central part of the Green River 

sub-basin, decreasing in all directions away from this depocenter, and (2) varies from 160,000 to 253,000 BPA along 

a northeast trend in the northern part of the Washakie Basin 

(fig. 26). Maximum in-place oil in a single township is nearly 

6.6 billion barrels in the south-central part of the Green River 

Basin (fig. 27). Total in-place oil in the Tipton Shale Member 

is estimated at 362,816,000,000 barrels, of which some 4.1 

billion barrels are in the Washakie Basin (table 3).

Wilkins Peak Member

The Wilkins Peak Member is assessed here as a single 

unit, however, as more data become available it should be possible to assess individual oil shale zones based on the regional 

stratigraphic framework that has been established (fig. 12). 

The top of the Wilkins Peak Member–base of the Laney Member as mapped by Love and Christiansen (1985) was used to 

define the limits of the Wilkins Peak assessment unit.

Figure 28 is an isopach map from the base of the LaClede 

Bed of the Laney Member to the top of the Tipton Shale 

Member (see fig. 3). It includes the entire stratigraphic interval 

of the Wilkins Peak as well as laterally equivalent parts of the 

Cathedral Bluffs Tongue of the Wasatch Formation in basin 

margin areas (fig. 3). In areas of the northern part of the Green 

River Basin where the Rife Bed of the Tipton Shale Member is absent, the isopach interval extends from the base of 

the LaClede Bed to the top of the Scheggs Bed of the Tipton 

Shale Member. Although both the upper and lower contacts 

of this interval are time transgressive, the thickness variations 

shown are generally related to variations in subsidence during 

this time period. The interval thickens to the south across the 

Green River Basin from less than 100 ft in the northern part of 

the basin to 1,800 ft along the south margin of the Green River 

Basin adjacent to the Uinta Mountains (fig. 28). There are only 

four control points in the Washakie Basin, but the interval is 

thickest near the middle of the basin, 2,160 to 2,440 ft and 

thinnest near the basin margins, 1,803 to1,870 ft (fig. 28).

Figure 29 is an isopach map of that part of the Wilkins 

Peak Member that was assessed. This interval reaches a maximum thickness of over 1,500 ft locally in the southern part of 

the Green River Basin. It thins to the west and south due to the 

upper part grading laterally into the Cathedral Bluffs Tongue 

of the Wasatch Formation. It also thins to the north due to a 

combination of lower subsidence rates and grading in part 

into the Cathedral Bluffs Tongue of the Wasatch Formation 

and Farson Sandstone Member of the Green River Formation (fig. 12). A comparatively thin interval of the member 

was identified along the west margin of the Washakie Basin 

between the Cathedral Bluffs Tongue of the Wasatch Formation and the Tipton Shale Member by Roehler (1989d), but 

was not assessed here because it lacks significant oil shale. 

Farther to the east in the Washakie Basin the entire Wilkins 

Peak grades into the Cathedral Bluffs Tongue. 

A total of 33 core holes and 58 rotary holes were used 

in our assessment of oil shale resources in the Wilkins Peak 
! ! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! !! 

! ! ! ! ! ! ! ! ! !! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R. 

Map location 90 70 80 20 30 9080 40 40 20 80 5070 50 410.5 80 50 310 60 280 330 80 70 220 240 80 90 370 190 220 150 280 140 160 189.7 161.6 133 128.3 140.5 150 270230 146 150 200 126.8 161 147.8 190 150 230 250 250 220 200 147.1 161 150 180 170 159130 360 390 

190 230 200 210 154.8 200 350 140 190 190 190 250 230.5 247.4 390 281.7 310 300 160 220.3 270 200 600 T. 27N. T. 28N. T. 29N. T. 30N. 

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’ 42°00’ 41°30’ 41°00’ 0 6 12 MILES EXPLANATION Tipton Shale Member—Interval thickness, in feet >350 301–350 201–300 101–200 < 100 Borehole—Tipton Shale Member thickness, in feet ! Extent of the Tipton Shale Member

COLORADO

WYOMING

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WYOMING

Figure 24. Isopach map of the Tipton Shale Member.
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R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 100 W.

R. 105 W.

R. 110 W.

R. 115 W.

R. 95 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R. 

Map location

6.1

5.3

6.6 7.4 3.5

5.9

1.6

1

12.4

12.4

4.2 4.7 11.8 8.5

7.3

14.7 6.7

7

1.5

11.2

12 11.2

12.1

13.5 15.4 13.7 14.9

11.4

11.6 1.8

13.5 13.4

16.1 15.7

16.4

15.1 15.8

16.1

14.3

15.4 16 13.8 18.1 17 14.113.6 10.3 7.7 4 6.5

11.5

12.8 12.5

16.1

13.4

15.5 12.5

5.8

1.7 4 6.7 

10

11.4

15.6

22.3 18.6

13.8

5.7

10.7

14.7

15.8

18.4

14.5

11.9

10.1

3.4

11.5

2.3

7.3

3.4

12.2

17.1 15.1

T.

27

N.

T.

28

N.

T.

29

N.

T.

30

N.

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’42°00’41°30’41°00’

0 6 12 MILES

Tipton Shale Member interval—Estimated oil yield, in gallon

> 2015.1–2010.1–15

5.1–10< 125

Borehole—Oil yield, Tipton Shale Member, in gallons per ton

!

Extent of the Tipton Shale Member

EXPLANATION

COLORADO

WYOMING

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0 5 10 KILOMETERS

WYOMING

Figure 25. Isoresource map showing the oil yield in gallons per ton for the Tipton Shale Member.
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! ! ! ! ! ! ! ! !! ! !! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R. 

Map location 46 31 44 12 9 4411 3 20 20 29 28 48 47 49 162 34 53 8 73 58 82 175 86 108 109 152 111 94 24 150 160 131 129 156 151 150 175 192180 152 164 262 155 175 151 16096 79136 186 184 160 194 160 187 170 77 19 124 218 

123166 243 345 213 208 167 78 196 234 210 228 217 196 115 253 62 92 47 95 197 236 T. 27N. T. 29N. T. 30N. T. 28N. 

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’ 42°00’ 41°30’ 41°00’ 0 6 12 MILES

COLORADO

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Tipton Shale Member interval—Oil yield, in thousands of ba

> 500376–500251–375

126–250< 125

Borehole—Barrels per acre, Tipton Shale Member in thousands of barrels

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EXPLANATION

WYOMING

0 5 10 KILOMETERS

Figure 26. Isoresource map showing the oil yield in barrels per acre for the Tipton Shale Member.
Map location

R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 100 W.

R. 105 W.

R. 110 W.

R. 115 W.

R. 95 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R. 

717 708 530 475

1,664 1,179 1,169 2,017 1,333 1,244 1,715 2,505 3,631 4,481 4,613

4,112 2,887 2,262 2,098 3,261 2,313

740

4,264 4,872 5,193 4,907 4,822 4,337 3,646

3,532 3,918 3,627 3,766 3,329 42 596 2,927 3,075 4,640 6,078 6,565 5,223 4,616 4,471

2,691 3,135 3,836 4,455 2,811 

1,484 1,814 4,210 6,047 6,107 4,557 4,078 4,359

4,098 3,351 

2,518 3,324 1,5

1,843

235

2,836 5,247 5,549 4,112 3,586 4,586 2,254 3,769

3,429 3,286

2,700 2,3

360

2,921 3,866 4,757 3,798 3,077 3,413 1,371 2,201

1,734 2,167 1,001

373

616 1,286 2,751 3,415 3,095 2,853 3,172 3,559 646

2,277

377

2,273 2,707 3,416 691 1,245 2,112 2,473

1,355 1,978 2,155 2,575 944 1,402 1,548 1,578

915 956 1,094 1,655 2,696 1,821 465 805

713 637 732 993 1,473 920 166 793

316 717 756 474 158 640 580 434

774 724 327 155 592 548 364 480

359 175 795 821

941 945

704 567

T.

27

N.

T.

28

N.

T.

29

N.

T.

30

N.

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’42°00’41°30’41°00’

0 6 12 MILES

Tipton Shale Member interval—Estima in millions of barrels per township

> 6,0004,501–60003,001–4,500

Extent of the Tipton Shale Mem

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EXPLANATION

WYOMING

UTAH

Figure 27. Isoresource map of the Tipton Shale Member showing barrels of oil in each Township.
! ! ! ! ! ! ! ! !! ! !! ! !! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! !! ! !! ! ! ! ! ! ! ! !! !! ! ! ! ! !! ! !!! ! ! ! ! ! ! ! !! ! !! ! ! ! ! ! !!! ! !! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! Map location R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R

228 205 432 715 90 115.770 77.8 170 220 220142.1 192 200 210 180 160 270 230 190 210 310 180 177.2221 295260 170270 290 215190 208.4 269.1 200.5 232.4200 226 310 285 270 420 353.4353 337 260 400 273.1 265 240 400 360 202 267 495 470 470 440480 433.7 580 587 580 470 765.1 570 960 490 610 540 370540 660650 940 710 928 872.8 860 1130 1040 1040 996.7 1350 1200 1056.9 1063.1 1000 1870 1570 1610 1440 1540 1165.9 1181.7 1175 2160 1750 1500 1570 1430 1165 1380 1140 1194.2 1803.2 2440 1800 1080 900 T. 27N. T. 28N. T. 29N. T. 30N. T. 26N. T. 25N. 

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’ 42°00’ 41°30’ 41°00’ 0 6 12 MILES Thickness of the Wilkins Peak Member and equivale

> 2,250 2,001–2,250 1,751–2,000 1,501–1,750 1,251–1,500 1,001–1,250 751–1,000 

Borehole—Thickness of the Wilkins Peak Member, in feet !6030 Top of Wilkins Peak Member WYOMING 0 5 10 KILOMETERS

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EXPLANATION

WYOMING

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Figure 28. Isopach map from the base of the LaClede Bed to the top of the Tipton Shale Member.
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Map location

R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 100 W.

R. 105 W.

R. 110 W.

R. 115 W.

R. 95 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R. 

90

115.7

70

77.8

170

220

220

142.1

192

200

210

180 160

270

230 190

210

310

180 177.2

221 295

260

170

270

290

215

190

208.4

269.1 200.5

232.4

200

226

310

285

270

420

353.4

353 337

260

400

273.1

265

240

400

360

202

267

495

470 470

440

440

480

433.7

580

587

580

470

765.1

570

960

490

610

540

370

540

660

650

710 928 872.8 860

330

1040 1040

996.7

230

350

350

1200 1056.9 1063.1

1000

430

200

310

420 1165.9

1181.7

1175

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350 450

460

1140 1194.2

270

390 900

T.

27

N.

T.

28

N.

T.

29

N.

T.

30

N.

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’42°00’41°30’41°00’

0 6 12 MILES

Wilkins Peak Member—Interval thic

>750501–750251–500

< 

Borehole—Wilkins Peak Mem thickness, in feet

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EXPLANATION

WYOMING

UTAH

Figure 29. Isopach map of the Wilkins Peak Member.
50 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

Member. Total area assessed is 4,102 mi2; the west margin of 

the Green River Basin and the northeastern part of the Green 

River Basin were not assessed due to lack of control (fig. 30). 

Oil yield is greatest in the north-central part of the Green 

River Basin, averaging between 12 and 18.2 GPT (fig. 30) 

in an area where the Wilkins Peak is comparatively thin but 

contains a higher proportion of oil shale beds as kerogen-poor 

lithologies pinch out. Oil yields in the saline depocenter in 

the central part of the Green River Basin (fig. 14) are much 

lower, averaging about 5 to 10.5 GPT (fig. 30). Maximum 

in-place oil, in contrast, is in the northern part of the saline 

depocenter, in large part because the Wilkins Peak is much 

thicker there than in the northern part of the Green River Basin 

(figs. 29 and 31). Maximum in-place oil in a township, over 17 

billion barrels, is in the central part of the Green River Basin 

(fig. 32). Total in-place oil in the Wilkins Peak Member is 

704,991,000,000 barrels (table 3).

LaClede Bed of the Laney Member

The LaClede Bed includes most of the oil shale in the 

Laney Member. It is the only unit in the member that was 

assessed, and is the area extending into the subsurface from 

mapped outcrops of the base of the Laney Member (base of 

LaClede). As the unit typically forms a steep slope or cliff in 

the lowermost part of the Laney Shale Member, the top of the 

LaClede Bed is generally shown in map view to be close to 

the base of the Laney. The top of the LaClede Bed has been 

mapped only locally in the Washakie Basin (Roehler, 1973b; 

1974b, c; 1977; 1978a, c). Laney Member strata above the 

LaClede Bed, which contains little oil, generally form a slope, 

and the top of the Laney typically crops out many miles from 

the outcrop line for the base of the Laney. Thus, assessing 

the LaClede Bed to the outcrop line at the base of the Laney 

Member very slightly overestimates its in-place resources as 

opposed to markedly underestimating the resources if the top 

of the Laney had been used. 

The lower part of the LaClede Bed, as defined by Roehler 

(1991b) in the Washakie Basin, is laterally equivalent to the 

upper part of the underlying Wilkins Peak Member in the 

Green River Basin to the west (pl. 1). The Sand Butte Bed, 

which overlies the LaClede Bed in the vicinity of the Rock 

Springs uplift, is tuffaceous sandstone and siltstone, and the 

Hartt Cabin Bed, which overlies the LaClede Bed in other 

areas of the Greater Green River Basin, is interbedded sandstone, siltstone, mudstone, shale, oil shale, tuff, limestone, and 

dolomite (figs. 3 and 17). 

The LaClede Bed thickens generally toward the southeast from less than 50 ft in the northwestern part of the Green 

River Basin to a maximum of 650 ft in the central part of the 

Washakie Basin (fig. 34). Most of this thickening is due to the 

inclusion of progressively younger tongues of oil shale in the 

LaClede Bed towards the southeast (fig. 20, plate. 1), which 

were not assessed until they merged with the LaClede Bed. 

In plate 1, for example, a tongue of oil shale that is separated 

from the LaClede Bed by 80 ft of marginal lacustrine rock 

containing little oil in the Union Pacific RR Co. El Paso 44-3 

well was not assessed, but was assessed as part of the LaClede 

Bed in the Natl. Pk. Serv. Buckboars Crossing well 5.7 miles 

to the southeast. 

A total of 54 core holes and 71 rotary holes were used to 

assess the LaClede; total area that was assessed is 4,686 mi2

, 

which did not include areas where control is absent in basin 

margin areas (fig. 33). Average GPT is highest, varying from 

about 11 to 23 GPT, along the east margin of the Green River 

Basin as well as along the west margin of the Washakie Basin 

(fig. 34). Maximum BPA is about 350,000 to 570,000 in the 

southwestern part of the Washakie Basin where the bed is 

thickest (fig. 35). Maximum in-place oil in a single township 

is more than 11.5 billion barrels in the southwestern part of the 

Washakie Basin (fig. 36). Total in-place oil is 377,185,000,000 

barrels (table 3).

Discussion

Estimated total in-place oil shale resources for the 

Eocene Green River Formation in the Greater Green River 

Basin is 1.44 trillion barrels (table 3), not too dissimilar from 

the estimated in-place resources of 1.52 trillion barrels for the 

Piceance Basin of Colorado of (Johnson and others, 2010a) 

and 1.32 trillion barrels for the Uinta Basin of Utah (Johnson 

and others, 2010a). However, the assessed area of the Greater 

Green River Basin, about 5,500 mi2

, is about 1.4 times larger 

than the assessed area of the Uinta Basin (3,834 mi2

) and over 

4 times larger than the assessed area of the Piceance Basin 

(1,335 mi2

). Thus, the oil shale deposits of the Greater Green 

River Basin are, overall, the lowest grade of the three basins. 

Maximum in-place oil in a single 6-mile by 6-mile township 

in the Greater Green River Basin is 23.1 billion barrels in T. 

17 N., R. 108 W (fig. 37). This compares with a maximum 

of 74.3 billion barrels of oil in place in a single township in 

the Piceance Basin (fig. 38). It should be noted that none of 

these estimates includes all of the oil shale that is present, as 

many marginal areas of the Greater Green River and Uinta 

Basins and the southernmost part of the Piceance Basin were 

not assessed due to lack of data. Oil shale in some of the early 

freshwater lacustrine stages in all three basins was excluded 

from all three assessments.
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Map location

R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 100 W.

R. 105 W.

R. 110 W.

R. 115 W.

R. 95 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. 

14.1

9.4

10.4

6.5

3.5

3.8 6.9

10.7

3.7

5

3.9

7.9 6.3 5.4

2.2 4.1

15.2

15.1

9.7 9.6

8.4 7.9

7

4.9

4.7

5.9

11

14.5

11.9

11.4 14.4

9.9

7.1

11.7

9

6.4

11.7

10.1

7.9

11.6 18.2

12.1

12.7

12.7

13.1

6.6

8.2

16.2 16.4

12.9

14.5

9.6 12.3

7.8

5.6

10.6 9.9

8.3

9

8.3

2.3

5.4

13.9 7.7

8.8

8.7

4.6 4

8.5 4.1

11.6

6.8

10.7 8.9

5.2

6.4

6.2

7.8

4.4

6.9

5.8

9.3

4.5

3.8

4.5

7.5

3

10.5

4.8 3.6

2.5

8.9

9

10.4

T.

27

N.

T.

28

N.

T.

29

N.

T.

30

N.

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°0

42°30’42°00’41°30’41°00’

0 6 12 MILES

Wilkins Peak Member interval—Average oil yield, in gallo

> 2015.1–2010.1–15

5.1–10< 125

Borehole—Oil yield, Wilkins Peak Member, in gallons per ton

!

Assesssment boundary for the Wilkins Peak Member

WYOMING

0 5 10 KILOMETERS

COLORADO

EXPLANATION

WYOMING

UTAH

Figure 30. Isoresource map showing the oil yield in gallons per ton for the Wilkins Peak Member.
! ! ! ! ! !! !! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! ! !! ! ! ! ! ! ! ! !! !! ! ! ! ! ! ! !!! ! ! ! ! ! ! ! !! ! !! ! ! ! ! ! !!! ! !! ! ! ! ! ! !! ! ! ! ! ! !! ! Map location R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R

100 90 5942 51 72 126 124 61 85 71 119 84 123 81 37 250 367143 140154194 153 71 109 143 192 217 200 248 227 189 119 213 231 152 255 347 233 331 465 389 277 277 132 273453 257275 299 299 371 464 287226 375 471 405 431 324 154 260 1056 315 444 389 260 224 654 308 805 187 906 766 438 123 182 228 401 575 97 238 450 387 453 18291 394 468 372 59 287 312 382 T. 27N. T. 28N. T. 29N. T. 30N. 

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’ 42°00’ 41°30’ 41°00’ 0 6 12 MILES Wilkins Peak Member interval—Oil yield, in thousands 

> 1,000 751–1,000 501–750 251–500 < 250 Borehole, barrels per acre, Wilkins Peak 

 in thousands of barrels ! Assesssment boundary for the Wilkins P

WYOMING 0 5 10 KILOMETERS

COLORADO

EXPLANATION

WYOMING

UTAH

Figure 31. Isoresource map showing the oil yield in barrels per acre for the Wilkins Peak Member. 
Map location

R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 100 W.

R. 105 W.

R. 110 W.

R. 115 W.

R. 95 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R

T.

27

N.

T.

28

N.

T.

29

N.

T.

30

N.

2,754 3,071 1,967 1,252 1,423

2,965

2,913

2,615 2,701 5,520 7,781 8,628

2,756 636 3,494 5,577 8,236 9,546 9,678 7,713

879

2,309 5,657 3,657 6,514 8,837 10,020 9,584

4,963 3,479 3,751 6,562 9,304 11,040 10,898

4,502 5,128 6,789 10,131 13,717 16,473 10,388

6,958 2,975

5,405 6,624 7,410 10,339 14,262 14,972

807 6,513 8,976 14,718 17,106 11,373 8,682 5,570 7,296

17,344

289

10,324 5,648 4,633 5,255 4,627 7,421 13,130

3,147 9,787 9,934 8,356 4,052 4,623 5,934 8,286

7,022 8,293 8,105 8,838 4,504 3,221 4,086 5,473

3,194 5,304 7,187 8,085 5,937 7,382 5,039 2,661

4,662 3,682

610

5,306 4,184 1,965 2,487 3,620 4,981

3,861

186

4,992 4,445 3,407 2,467 1,798 2,016 3,063 967

2,668 2,478 2,240 2,252 1,633 2,398 1,304

420

1,505 1,410 1,179 1,373 1,868 1,983 1,183 188

633 981 1,018 764 161

46 118

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’42°00’41°30’41°00’

0 6 12 MILES

Wilkins Peak Member interval—Oil yiein millions of barrels per township

> 14,00010,001–14,0007,001–10,000

Assesssment boundary for the Wilk

WYOMING

0 5 10 KILOMETERS

COLORADO

EXPLANATION

WYOMING

UTAH

Figure 32. Isoresource map of the Wilkins Peak Member of the Green River Formation showing total barrels of oil in each Township
! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! 

! ! ! ! ! !! !! ! ! ! ! !! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!! ! !! ! ! ! ! ! !! ! ! ! ! ! !!! !! ! !!!! ! ! !! ! ! ! ! !! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Map location R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. 

40 111 20 30 40 60 30 50 60 40 78.8 31 80 90 5070 80 90 67.9 84.5 69 40.1 58.5 55 55 60 49.6 60 50 60 16.9 76 95 80 50 77.4 60 100 6055 70 60 40 50 60 60 51.4 77.2 80 60 50 9050 50 90 90 50 73.6 80 100 25.5 200 150 190 73 104 50 70 145.7 100 140 155 136.8 122.6 80 80 120 200 200 281.6 340 90 150 225.8 120 103.8 290 292 281 289.9 294 420 120 70 150 220 163 151.4 185 205 331.1 335.8 356.8 350 600 570 650 2

120 190 170 180 170 226.1 448.5 540 557.1 610 600 600 610 650 450 120 150 180 T. 27N. T. 28N. T. 29N. T. 30N. 

110°30' 110°00' 109°30' 109°00' 108°30' 108°0

42°30' 42°00' 41°30' 41°00' 0 6 12 MILES LaClede Bed interval thickness, in 

>600 451–600 301–450 

Borehole LaClede Bed thi in feet ! Extent of Laney Member WYOMING 0 5 10 KILOMETERS

COLORADO

EXPLANATION

WYOMING

UTAH

Figure 33. Isopach map of the LaClede Bed of the Laney Member.
! !

!

!

!

! !

!

!

!

!

!

!

!

!

!

! 

! ! ! !

!

!

!

!

!

!

!

! !

!!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!!

!

! !

!

!

!

! !

!

!

!

!

!!

!

!!

!

!!!!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

! ! !

!

!

! !

!!

!

!

!

!

!

!

!

! !

! !

!

!

!

!

!

!

Map location

R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 100 W.

R. 105 W.

R. 110 W.

R. 115 W.

R. 95 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. 

2.8

1.6

9.2

5.1

8.8

6.2

10.1 2.2

3.5 11

6.7

9.5

4

4.3

4.4

3

5.1 11.9

7.5

12.8 9.4 20.4

5.8

10.2

8.7

5.9

12

10.7

7.8

10.8

9.3

8 12

9.1 10.7

12.8 12.9

7.5 6.3

12.7

15.4 9.4 13.5 8.3

10.8

9.7

10.3

9.4

20.4

18.3 5

21.3

11.6

7.5

11.4

13.5 11.6 4.7

19.6

8.2

2.6 12.8

9

21.5 16.3

14.4

10.8

8.8

5 9.7

11

14.6 15.4

2.9

9.1

9.2

12.1

11.5

5

2.4

13.1

23.1

15.6

15.6

12.5

11.7

11

10.9

11.4

7.1

2.95.4

6.4 3 10.7

12.5

12.7

12.9

11.3

11.4 12

18.6

7.5 10.7 8.1

4.5

4.6

9.1

17

14.8 10.7 10

9.1

10.8

10.9

10.8 9

9.3

8.1

4.8

1.9 10.8

T.

27

N.

T.

28

N.

T.

29

N.

T.

30

N.

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°0

42°30’42°00’41°30’41°00’

0 6 12 MILES

LaClede Bed interval—Average oil yield, 

> 2015.1–2010.1–15

5.1–1< 5

Borehole—Oil yield, LaClede Bed in gallons per ton

!

Extent of Laney Member

WYOMING

0 5 10 KILOMETERS

COLORADO

EXPLANATION

WYOMING

UTAH

Figure 34. Isoresource map showing the oil yield in gallons per ton for the LaClede Bed.
! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! 

! ! ! ! ! !! !! ! ! ! ! !! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! !! ! !! ! ! ! ! ! !! ! ! ! ! ! !!! !! ! !!!! ! ! !! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Map location R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R

10 16 15 13 29 31 25 10 18 36 44 24 28 33 1918 35 86 43 86 53 61 28 46 30 4048 52 33 5313 51 92 44 58 61 103 3837 56 48 46 64 3453 41 65 62 92 70 3879 47 56 83 54 69 32 148 17 45 153 141 117 131 57 128 73 60 123 122 141 96 20 90 152 195 262 145 19 236 203 126 291 276251 257271 250 3032 80 57 142 152 188 211 303 307 345 495 376 384 566 13

46 

75 128 236 197 197 367 405 489 489 540 527 454 498 303 49 25 158 T. 27N. T. 28N. T. 29N. T. 30N. 

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’ 42°00’ 41°30’ 41°00’ 0 6 12 MILES LaClede Bed interval—Oil yield, in thousands of barrels per 

> 500 376–500 251–375 126–250 < 125 Borehole—Barrels per acre, LaClede Bed, in thousands of barrels ! Extent of Laney Member WYOMING 0 5 10 KILOMETERS

COLORADO

EXPLANATION

WYOMING

UTAH

Figure 35. Isoresource map showing the oil yield in barrels per acre for the LaClede Bed.
Map location

R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W.

R. 100 W.

R. 105 W.

R. 110 W.

R. 115 W.

R. 95 W.

R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. R

1,980 2,033 1,216 631 1,087

5,

9,644 10,952 10,172 7,764 3,652 1,617 912 1,500 3,219 4,657 4,735

8,219 10,533 11,542 9,888 6,802 5

359

661 332 1,249 1,966 3,318 4,458 4,547 4,023

4,019 10,112 10,715 10,001 7,478 5,601 4

425

575

2,893

1,146 1,805 2,795 3,537 4,590

2,0

3,451 7,309 7,892 7,078 6,175 4,656

2,090 765 1,691 2,759 3,562 4,043 313

3,977 3,932 3,447

2,647

1,294 2,869 3,410 3,054 3,056 31 354

2,575 1,404

2,068 585

797 2,255 2,637 2,826 113

270 418 889 1,423 2,035 2,578 2,265 51

1,312

118

779 2,699 2,507 274 540

1,036 873 1,443 2,045 534 688

924 1,123 1,471 1,471 1,010 814

447 658 1,120 1,763 1,536 1,126 1,042 305

971 784

167

1,550 1,090 266 424 479 1,261

613 877 821 725 724 649 315 502 147

578 536 474 467 563 675 236 347

78

122 386 347 397 165 30

21

T.

27

N.

T.

28

N.

T.

29

N.

T.

30

N.

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°00

42°30’42°00’41°30’41°00’

0 6 12 MILES

LaClede Bed interval—Oil yield, in millions o

> 10,0007,501–10,0005,001–7,500

2,5< 2

Extent of the Laney Member

WYOMING

0 5 10 KILOMETERS

COLORADO

EXPLANATION

WYOMING

UTAH

Figure 36. Isoresource map of the LaClede Bed of the Laney Member of the Green River Formation showing total barrels of oil in e
Map location R. 117 W. R. 116 W. R. 115 W. R. 114 W. R. 113 W. R. 112 W. R. 111 W. R. 110 W. R. 109 W. R. 108 W. R. 107 W. R. 106 W. R. 105 W. R. 104 W. R. 103 W. R. 102 W. R. 101 W. R. 100 W. R. 100 W. R. 105 W. R. 110 W. R. 115 W. R. 95 W. R. 118 W. R. 99 W. R. 98 W. R. 97 W. R. 96 W. R. 95 W. 

2,064 2,652 4,814 5,200 3,248 30 717 708 530 475 1,333 5,669 11,308 12,130 11,341 7,764 

4,448 5,203 6,392 11,903 16,929 18,105 4,591 3,620 12,331 13,419 13,804 11,985 6,802 

5,861 14,868 18,891 19,158 16,598 5,322 740 7,862 10,509 4,236 596 42 7,551 14,031 14,342 13,767 10,808 5,601 

6,052 8,655 13,368 17,252 18,500 18,811 13,041 11,443 1,814 1 4,935 10,000 11,028 10,915 10,630 7,467 

13,797 17,787 19,058 19,023 7,005 8,539 13,203 18,391 21,167 23,099 18,075 2,851 247 2,015 5,164 7,301 8,030 6,798 1

6,963 9,276 8,992 12,067 17,318 20,676 20,865 12,453 6,510 13 372 4,104 6,004 3,286 2

6,942 13,298 21,977 17,109 14,528 1,734 373 1,734 2,167 1

8,672 9,687 19,240 6,324 10,448 16,210 20,943 15,718 11,564 787 5,401 6,534 7,017 12,656 13,542 12,971 5,545 5,053 6,048 8,025 10,565 9,044 11,069 12,273 12,129 5,980 4,035 5,012 7,252 4,362 6,608 9,045 10,844 8,957 9,437 6,253 3,762 6,111 4,625 782 4,539 6,564 7,574 6,028 2,872 3,493 6,652 5,989 4,916 4,286 3,119 189 3,115 4,231 1,480 2,594 3,233 3,156 3,181 2,965 474 1,541 2,775 3,688 501 1,798 1,527 1,773 122 219 1,350 2,810 2,928 1,508 1,723 765 635 184 1,550 0 118 47 

T. 28N. T. 29N. T. 30N. 

110°30’ 110°00’ 109°30’ 109°00’ 108°30’ 108°0

42°30’ 42°00’ 41°30’ 41°00’ 0 6 12 MILES > 20,000 15,000–20,000 10,000–15,000 

Township Summaries—Oil yield, i

barrels per township WYOMING 0 5 10 KILOMETERS

COLORADO

EXPLANATION

WYOMING

UTAH

Figure 37. Isoresource map for the Greater Green River Basin showing total barrels of oil in each township for all three assessed u
  

Total in place shale oil resource, in millions of barrels

< 15,000

15,001–25,000

25,001–50,000

50,001–65,000

> 65,000

Top of Mahogany zone

Base of Parachute Creek Member

Total in-place shale oil resource—

 By township, in millions of barrels 74430

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

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

R. 96 W. R. 95 W.

R. 94 W.

R. 94 W. R. 93 W.

R. 96 W. R. 95 W.

Map location

69 367

584

4,177

5,020

2,056 224

2,444

1,347 5,451

1,544

1,290 3,334

689 2,588

4,977

10,492

20,284 9,833 9,161 491

1,851 4,468

17,894 24,305

35,113

31,331

27,288

17,091

926

9,643

29,650 39,030 48,512 46,928 38,641

9,591 93 9,248

37,246 54,308, 64,779 58,562 41,267 4,139 3,903

50,265 69,927 74,430 60,565 27,986

353 15,478

19,072 18,746 1942 120

56,283 73,271 68,167 46,360

15,199

27,160

41,772 58,144 39,787

10,580

6037

T.

1

S.

T.

2

S.

T.

3

S.

T.

4

S.

T.

5

S.

T.

6

S.

T.

7

S.

T.

8

S.

T.

9

S.

T.

1

N.

T.

2

N.

108°30’ 108°00’

40°00’

39°30’

COLORADO

0

0 5 10 KILOMETERS

3 6 12 MILES

EXPLANATION

Figure 38. Isoresource map for the Piceance Creek Basin showing total barrels of oil in each township 

for all the assessed oil shale units combined.
60 Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Wyoming, Colorado, and Utah

References Cited

 American Society for Testing Materials, 1984, Designation D 

388–80, Standard test method for oil from oil shale: Annual 

Book of ASTM Standards, 1984, p. 513–525.

Bradley, W.H., 1959, Revision of stratigraphic nomenclature 

of Green River Formation of Wyoming: American Association of Petroleum Geologists Bulletin, v. 43, no. 5, 

p. 1072–1075.

Bradley, W.H., 1963, Eocene—Green River Formation,

in Frey, D.G., ed., Limnology in North America, The 

University of Wisconsin Press, p. 629–644.

Bradley, W.H., 1964, Geology of Green River Formation 

and associated Eocene rocks in southwestern Wyoming 

and adjacent parts of Colorado and Utah: U.S. Geological 

Survey Professional Paper 495–A, 86 p.

Bradley, W.H., and Eugster, H.P., 1969, Geochemistry and 

paleolimnology of the trona deposits and associated authigenic minerals of the Green River Formation of Wyoming: 

U.S. Geological Survey Professional Paper 496–B, 71 p.

Brownfield, M.E., Self, J.G., and Mercier, T.J., 2008, Fischer 

assay histograms of oil-shale drill cores and cuttings from 

the Great Divide, Green River, and Washakie Basins, 

southwestern Wyoming, in U.S. Geological Survey Oil 

Shale Assessment Team, eds., Fischer assays of oil-shale 

drill cores and rotary cuttings from the Greater Green River 

Basin, southwestern Wyoming: U.S. Geological Survey 

Open-File Report 2008–1152, chap. 2.

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.

Culbertson, W.C., 1969, Oil shale in the Green River Formation, Green River Basin, Wyoming: Wyoming Geological 

Association, 21st Annual Field Conference, Guidebook, 

p. 191–195.

Culbertson, W.C., 1971, Stratigraphy of the trona deposits in 

the Green River Formation, southwest Wyoming: Wyoming 

University Contributions to Geology, v. 10, no. 1, p. 15–23.

Culbertson, W.C., Smith, J.W., Trudell L.G., 1980, Oil shale 

resources and geology of the Green River Formation in the 

Green River Basin, Wyoming: U.S. Department of Energy 

Laramie Energy Technology Center LETC/RI-80/6, 102 p.

Dyni, J.R., 2003, Geology and resources of some world oilshale deposits: Oil Shale, v. 20, no. 3, p. 193–252, Estonian 

Academy Publishers.

Dyni, J.R., Mercier, T.J., and Brownfield, M E., 2008, Analyses of oil shale samples from core holes and rotary-drilled 

wells from the Green River Formation, southwestern 

Wyoming, in U.S. Geological Survey Oil Shale Assessment 

Team, eds., Fischer assays of oil-shale drill cores and rotary 

cuttings from the Greater Green River Basin, southwestern Wyoming: U.S. Geological Survey Open-File Report 

2008–1152, chap. 1.

Ebens, R.J., 1963, Petrography of the Eocene Tower Sandstone lenses at Green River, Sweetwater County, Wyoming: 

Laramie, University of Wyoming, M.S. thesis, 46 p.

Eugster, H.P., and Surdam, R C., 1973, Depositional environment of the Green River Formation of Wyoming—A 

preliminary report: Geological Society of America Bulletin 

v. 84, p. 1115–1120.

Eugster, H.P., and Hardie, L.A., 1975, Sedimentation in an 

ancient playa-lake complex—The Wilkins Peak Member of 

the Green River Formation of Wyoming: Geological Society 

of American Bulletin, v. 86, p. 319–334.

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., 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, in

U.S. Geological Survey Uinta-Piceance Assessment Team, 

eds., Petroleum systems and geologic assessment of the oil 

and gas in the Uinta-Piceance Province, Utah and Colorado: 

U.S. Geological Survey Digital Data Series DDS–69–B, 

chap. 13, 30 p.

Johnson, R.C., Finn, T.M., and Roberts, L.N., 2005, The 

Mesaverde Total Petroleum System, Southwestern Wyoming Province, in U.S. Geological Survey Southwestern 

Wyoming Province Assessment Team, eds., Petroleum Systems and geologic assessment of oil and gas in the southwestern Wyoming Province, Wyoming, Colorado, and Utah: 

U.S. Geological Survey Digital Data Series DDS–69–D, 

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