Chapter I

A Summary of the Stratigraphy, 

Coal Resources, and Coal-Bed 

Methane Potential of Northwest Colorado

By Michael E. Brownfield,1 Robert D. Hettinger,1

and Edward A. Johnson1

U.S. Geological Survey Professional Paper 1625–B*

U.S. Department of the Interior

U.S. Geological Survey

Chapter I of

Geologic Assessment of Coal in the Colorado Plateau:

Arizona, Colorado, New Mexico, and Utah

Edited by M.A. Kirschbaum, L.N.R. Roberts, and L.R.H. Biewick

1 U.S. Geological Survey, Denver, Colorado 80225

* This report, although in the USGS Professional Paper series,

is available only on CD-ROM and is not available separately

National Coal

Resource

Assessment

Click here to return to Disc 1 

Volume Table of Contents
Contents

Introduction ..................................................................................................................................................I1

Coal Fields of Northwest Colorado ............................................................................................................ 2

Coal in Northwest Colorado........................................................................................................................ 3

Lower White River Coal Field...................................................................................................................... 4

Location................................................................................................................................................. 4

Stratigraphy of Cretaceous and Tertiary Strata.............................................................................. 4

Coal Geology of the Deserado Coal Area ........................................................................................ 6

Coal Resources.................................................................................................................................... 7

Danforth Hills Coal Field .............................................................................................................................. 8

Location................................................................................................................................................. 8

Stratigraphy of Cretaceous and Tertiary Strata.............................................................................. 8

Coal Geology......................................................................................................................................... 9

Coal Resources.................................................................................................................................. 11

Yampa Coal Field......................................................................................................................................... 12

Location............................................................................................................................................... 12

Mesaverde Group.............................................................................................................................. 13

Coal Geology....................................................................................................................................... 14

Coal Resources.................................................................................................................................. 15

Southern Piceance Basin.......................................................................................................................... 16

Location............................................................................................................................................... 16

Coal Geology....................................................................................................................................... 16

Coal Resources.................................................................................................................................. 18

Coal-Bed Methane in Northwest Colorado............................................................................................ 19

Piceance Basin.................................................................................................................................. 19

Sand Wash Basin............................................................................................................................... 20

Summary ...................................................................................................................................................... 20

References Cited ........................................................................................................................................ 21

Figures

1. Priority coal assessment areas in the Rocky Mountains and Colorado

Plateau region, National Coal Resource Assessment Project............................................I1

2. Major coal fields in northwest Colorado.................................................................................. 2

3. Generalized geologic map of northwest Colorado ................................................................. 3

4. Stratigraphic correlations and facies relationships for part of the

Upper Cretaceous and Tertiary rocks in the Lower White River,

Danforth Hills, and Yampa coal fields, Colorado ..................................................................... 4
5. Generalized stratigraphic column for a portion of the Upper Cretaceous

rocks for the Deserado coal area, Lower White River coal field, Colorado....................... 5

6. Photograph, view looking north across the Rangely Reservoir at the

Deserado coal area...................................................................................................................... 6

7. Photograph of coal marker sands of the coal unit of the Mesaverde

Group in the Deserado coal area............................................................................................... 6

8. Photograph of the D coal zone of the main coal zone in the

Deserado coal area...................................................................................................................... 7

9. Photograph of contact between the Upper Cretaceous Iles Formation

and the Mancos Shale along the northern part of the Danforth Hills coal field................ 8

10. Generalized stratigraphic column showing depositional environments

for a portion the Upper Cretaceous and Tertiary rocks in the Danforth

Hills coal field, Colorado.............................................................................................................. 9

11. Photograph of Colowyo coal mine in the northern part of the

Danforth Hills coal field ............................................................................................................. 11

12. Photograph of the Trout Creek Sandstone Member of the Iles Formation

and the middle coal group in the Williams Fork Formation, Yampa coal field.................. 12

13. Photograph of Trout Creek Sandtone Member of the Iles Formation................................ 12

14. Generalized northwest-southeast cross section of Mesaverde Group

in the Yampa coal field............................................................................................................... 13

15. Stratigraphic column showing the middle and upper coal groups of

the Williams Fork Formation, Yampa coal field...................................................................... 14

16. Photograph of the Eagle # 5 longwall mine, middle coal group,

Williams Fork Formation, Yampa coal field ............................................................................ 15

17. Photograph looking north from the Trapper strip mine at the

Tri-State power plant................................................................................................................. 15

18. Photograph of the Cameo coal zone above the Rollins Sandstone Member

of the Mount Garfield Formation of the Mesaverde Group, Layton Wash,

southern Piceance Basin .......................................................................................................... 16

19. Stratigraphic correlations and facies relationships in the Mesaverde

Group and Mesaverde Formation, southern Piceance Basin, Colorado .......................... 16

20. Photograph of the Palisades on the western end of Grand Mesa

overlooking the town of Palisades, Colo. ............................................................................... 17

21. Stratigraphic correlations and facies relationships in the Mesaverde Group

and Mesaverde Formation, southern part of the Piceance Basin, Colorado................... 17

22. Photograph of Cameo-Wheeler coal zone above the Rollins Sandstone

Member of the Mount Garfield Formation of the Mesaverde Group near

Hunter Canyon, southern Piceance Basin............................................................................. 18

23. Map of gas fields producing coal-bed methane in northwest Colorado .......................... 19

24. Photograph of gas well in the southern Piceance Basin .................................................... 19
Table

1. Fairfield coal zones of the Williams Fork Formation showing thickness

range, average thickness, number of coal beds, general net-coal thickness

range, maximum net-coal thickness, and average stratigraphic distance above

Trout Creek Sandstone Member of the Iles Formation, Mesaverde Group,

Danforth Hills coal field ............................................................................................................I10
Figure 1. Priority coal assessment areas, shown in red, in the Rocky Mountains 

and Colorado Plateau region, National Coal Resource Assessment Project. Northwest 

Colorado assessment units highlighted in red in explanation. Modified after Kirschbaum 

(chap. A, this CD-ROM).

Introduction

The assessment of the coal resources of northwest Colorado, is part of the U.S. 

Geological Survey’s (USGS) National Coal Resource Assessment (NCRA) project 

to identify and characterize coal deposits that could potentially provide fuel for 

the Nation’s coal-derived energy needs during the first quarter of the 21st century. 

Twelve priority assessment units were designated in the Rocky Mountains and 

Colorado Plateau region (Kirschbaum, chap. A, this CD-ROM) because they are 

areas of active mining, contain large amounts of federally administered lands, have 

coal-bed gas production, and have potential for future development (fig. 1). 

Northwest Colorado contains 5 of the 12 priority assessment units (fig. 1). This 

paper summarizes the stratigraphy of coal-bearing rocks, coal resources, and coal-bed 

methane potential in northwest Colorado’s priority assessment units.

Danforth Hills, Lower White River, and Yampa assessment units (fig. 1) contain 

56 billion short tons of coal in beds greater than 1.2 ft thick and under less than 

3,000 ft of overburden. The Southern Piceance Basin assessment unit contains an 

estimated 48 billion short tons of coal in beds greater than 1 ft thick and under less 

than 3,000 ft of overburden. Coal resources were not calculated within coal leases. 

Although northwest Colorado contains a significant coal resource, the resource 

does not reflect economic, land-use, environmental, technological, and geologic 

constraints that might affect the availability and recoverability of the coal.

A Summary of the Stratigraphy, Coal Resources, 

and Coal-Bed Methane Potential of Northwest Colorado

By Michael E. Brownfield, Robert D. Hettinger, and Edward A. Johnson

113°

40°

113°

34° 34°

106°

106°

40°

0 100 Miles

Coal-bearing rocks

Rocky Mountains and

Colorado Plateau study area 

Coal assessment units

1. Kaiparowits Plateau

2. Henry Mountains

3. S. Wasatch Plateau

4. N. Wasatch Plateau

5. Lower White River,

 Deserado coal area

6. Danforth Hills,

 Fairfield coal group

7. Yampa, Williams Fork Formation

8. S. Piceance Basin

9. Somerset quadrangle

10. San Juan Basin

11. Bisti

12. Black Mesa Basin

Utah

Arizona

New Mexico

Colorado

1

2

3

4

5

6

7

8

9

10

12

11

I1
Figure 2. Major coal fi elds in northwest Colorado. Approximate boundaries of th

in shades of green.

Coal Fields of Northwest Colorado 

Northwest Colorado (fi g. 2) has been designated as a priority 

area for resource assessment because it has a large amount of federally owned coal lands and high coal production. The assessment units include the Deserado coal area in the Lower White River coal fi eld, the Williams Fork Formation in the Yampa coal fi eld, the Fairfi eld coal group in the Danforth Hills coal fi eld, 

the Southern Piceance Basin coal area (including the Book Cliffs, Grand Mesa, Somerset, Carbondale, southern Grand Hogback, and Crested Butte coal fi elds), and the Somerset quadrangle. The Somerset quadrangle was part of the USGS Coal Availability Program and was assessed in cooperation with the Colorado State Geological Survey (Rohrbacher and others, chap. F, this CD-ROM). The percent of federally owned assessed coal in each of the fi ve areas is: Deserado coal area, 99; Danforth Hills, 80; Yampa coal fi eld, 76; and southern Piceance Basin (includes Somerset quadrangle), 88. The northern part of the Grand Hogback coal fi eld was not assessed because there is no coal production from the coal fi eld.

Geoscientists with knowledge about each coal area have 

developed digital coal thickness and geographical databases and geologic maps to assess the coal resources in each major coal fi eld. Brownfi eld and others (chap. M and chap. N, this CD-ROM) have evaluated the coal resources in the Danforth Hills and Lower White River coal fi elds. Hettinger and others (chap. O, 

this CD-ROM) and Johnson and others (chap. P, this CD-ROM) have integrated geologic and drill-hole data to assess the Yampa coal fi eld and Southern Piceance Basin coal area, respectively.

Colorad

0 50 100 Miles

OURAY

MONTROSE

DELTA

GUNNISON

MESA

PITKIN

EAGLE

ROUTT

GARFIELD

RIO BLANCO

Dinosaur National MOFFATMonument

Axial Basin

Eastern SandWash Basin

Piceance Basin

Delta

Paonia

Somerset Crested Butte 

Grand Junction

Grand Mesa

Marble

Redstone

Rifle

New Castle

Rio Blanco

Meeker

Rangely

Dinosaur



3. Cr

8. So

6. Gr2. Ca1. Bo7. Lo5. Gr4. Da9. Ya

Coal f

Outcrcoal-b

1 2

3

4

5

6

7

8

9

Carbondale

Glenwood Springs

I2 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Figure 3. Generalized geologic map of northwest Colorado showing outcrops of the coal-bearing Mesaverde 

Formation and Group and major coal fields within the eastern Sand Wash and Piceance Basins. Modified from 

Brownfield and others (chaps. M and N, this CD-ROM) Hettinger and others (chap. O, this CD-ROM), and Johnson 

and others (chap. P, this CD-ROM). 

Coal in Northwest Colorado

The coal-bearing rocks in northwest Colorado (fig. 3) include 

the Upper Cretaceous Mesaverde Formation in the southern 

Piceance Basin, the Mount Garfield, Hunter Canyon, Iles, and 

Williams Fork Formations of the Mesaverde Group in the 

southern Piceance Basin, and Iles and Williams Fork Formations 

of the Mesaverde Group, the lower, coal, and upper units of 

the Mesaverde Group, Upper Cretaceous Lance Formation, and 

Paleocene Fort Union Formations in the eastern Sand Wash 

and northern Piceance Basins. The stratigraphic terminology and 

facies relations vary from coal field to coal field within the study 

area.

Only one mine, the Colowyo (Kennecott Mining Company) 

was producing coal in the Danforth Hills coal field at the end 

of 1999, while in the Lower White River coal field the only 

mine producing coal was the Deserado. In the Yampa coal field, 

four mines operated at the end of 1999 and included the Foidel 

Creek, Seneca II West, Trapper, and Yoast mines. Six mines 

were producing coal in the southern Piceance at the end of 1997; 

these include the Bowie No. 1, Bowie No. 2, McClane Canyon, 

Roadside North Portal, Sanborn, and West Elk mines. In 1997, 

coal production in northwest Colorado was about 24 million 

short tons of subbituminous and bituminous coal (Resource Data 

International, Inc.).

Crested Butte

Somerset 

Grand Mesa

Carbondale 

Book Cliffs

Lower White River

Grand

Hogback

Danforth Hills

Yampa 

10 0 50 Miles

Intrusive rocks

Mesaverde Formation or

Group coal-bering rocks

Map Explanation

Tertiary

Upper Cretaceous

Monocline

Fault - bar on

downthrown side

Anticline

Syncline

Piceance Basin

Eastern

Sand Wash Basin Grand

H

ogba

ck

Moncline

Axial Basin Anticline

109°00'

40°30'

40°00'

39°30'

39°00'

108°00' 107°00' White River Uplift

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potential of Northwest Colorado I3
Figure 4. Stratigraphic correlations and facies relationships for part of the Upper Cretaceous and Tertiary rocks 

in the Lower White River, Danforth Hills, and Yampa coal fields, Colorado. Named sandstones are in yellow. After 

Brownfield and others (chap. N, this CD-ROM). Abbreviations include: Sandstone (Ss.), sandstone (ss.) Member 

(Mbr.), and Formation (Fm.).

Lower White River Coal Field

Location

The Lower White River coal field (figs. 2 and 3) occupies 

parts of Garfield, Moffat, and Rio Blanco Counties. The coal field 

is located in the northern part of the Piceance Basin, which is part 

of the Uinta Region of the Rocky Mountain Coal Province (Tully, 

1996). In this study, the area of interest is restricted to the northern 

part of the Lower White River coal field where there is active 

coal mining. This area is referred to as the Deserado coal area 

(Brownfield and others, chap. N, this CD-ROM). The Deserado 

coal area is located north of Rangely, Colo., and south of the 

Dinosaur National Monument.

Stratigraphy of Cretaceous 

and Tertiary Strata

A generalized stratigraphic column showing a portion of the 

Upper Cretaceous rocks in northwest Colorado and the regional 

correlations between the Lower White River, the Danforth Hills, 

and Yampa coal fields is shown in figure 4.

Iles Fm.

Iles Fm.

Williams Fork Fm.

Williams Fork Fm.

Lewis Shale Lance Fm. Fort Union Fm.

Fort Union

Fm.

Wasatch Fm.

Wasatch

Fm.

Eocene Paleocene Upper Cretaceous

Mancos Shale (part)

Fox Hills Sandstone

Lower White River coal field Danforth Hills coal field Western Yampa coal field 

Castlegate Ss. of the Mesaverde Group

Mesaverde Group

coal unit

lower unit

upper unit

Upper Cretaceous Paleocene-Eocene

Fort Union Fm.

Black Diamond

coal group

Lower

coal group

Fairfield coal group

Goff coal group

Barren interval

Lion Canyon

Ss. Mbr.

Lion Canyon

coal group

Tow Creek Ss. Mbr.

Trout Creek Ss. Mbr.

Twentymile Ss. Mbr.

Mancos Shale (part)

lower coal group

middle coal group

upper coal group

marine shale

marine shale

Sego Ss.

Mancos

Sh. (part)

1000 Ft

Lewis Shale

Wasatch Fm.

(part)

? ?

West East

rimrock ss.

?

?

Lower White

River

Danforth

Hills

Yampa 

Inset

Line of

section

Alluvial, coastal plain, and mire

Upper shoreface 

and estuarine

Lower shoreface and 

offshore marine

Depositional environments

Buck Tongue of the Mancos Shale

?

?

I4 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Figure 5. Generalized stratigraphic column for a portion of the Upper 

Cretaceous rocks for the Deserado coal area, Lower White River coal 

field, Colorado. Shown are the major divisions of the coal unit of the 

Mesaverde Group and the Western Fuels, Inc., coal-zone names. Coal 

beds and coal marker sandstones not drawn to scale. Named sandstones 

are shown in yellow. After Brownfield and others (chap. N, this CD-ROM).

All the coal-bearing units considered in this study are part of the Mesaverde 

Group of Late Cretaceous age. Within the Deserado coal area, the Mesaverde 

Group is approximately 5,000 ft (1,500 m) thick and is composed of a thick 

succession of mostly nonmarine rocks, which overlie approximately 5,100 ft (1,570 

m) of marine mudrock in the Upper Cretaceous Mancos Shale. The Mesaverde 

Group has been divided into three informal formation-equivalent stratigraphic 

units (fig. 5) by the USGS (Barnum and Garrigues, 1980). These three units are 

designated the lower unit, coal unit, and upper unit. The lower unit is roughly 

equivalent to the Iles Formation in the Danforth Hills coal field about 60 mi to the 

east of the study area (fig. 4) and averages 690 ft (210 m) thick. The coal unit and 

upper unit, with a combined average thickness of 2,130 ft (650 m) are correlated to 

the Williams Fork Formation in the Danforth Hills (fig. 4).

Sego Sandstone

Buck Tongue of the

Mancos Shale

Castlegate Sandstone

of the Mesaverde Group

Mancos Shale (part)

lower unit

coal unit

upper unit

upper coal unit

main coal zone 

lower coal unit

Mesaverde Group

Upper Cretaceous

Series Stratigraphic Units

coal marker ss

Meters

0

50

100

0

250

500

Feet

200

Alluvial, coastal plain,

and mire

Shoreface 

and estuarine

Offshore marine

Depositional environments

f

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potential of Northwest Colorado I5
Coal Geology of the Deserado Coal Area

The coal unit (fig. 6) of the Mesaverde Group in the Lower White River coal 

field ranges in thickness from 300 to 600 ft (90 to 180 m) and is divided into 

three informal subunits (B.E. Barnum, U.S. Bureau of Land Management, written 

commun., 1988). The subunits are, in ascending order, the lower coal unit, the main 

coal zone, and the upper coal unit. A group of persistent sandstones is located at the 

top of the lower unit (fig. 7). These sandstones were named the coal marker sands by 

Barnum and Garrigues (1980). Within the Deserado coal area the coal unit averages 

about 490 ft (150 m) thick.

In the Deserado coal area the coal unit of the Mesaverde Group has been 

subdivided into nine coal zones, eight of which are shown in figure 5. Western 

Fuels, Inc., has named these coal zones A, lower B, upper B (C), D, E, F, G, 

H, and I, in ascending order, within the Deserado Mine area (B.E. Barnum, U.S. 

Bureau of Land Management, written commun., 1988). Although nine coal zones 

have been recognized in the coal unit, most coal resources in the Deserado area are 

contained within two zones, the B (includes the lower B, upper B, and C) and the D 

(Brownfield and others, chap. N, this CD-ROM). Only the B and D coal zones were 

assessed for this study. The B and D occur in the lower part of the main coal zone just 

above the coal marker sands (fig. 5). 

Figure 6. Looking north across the Rangely Reservoir at the Deserado coal 

area. Coal unit and coal marker sands of the Mesaverde Group in center of 

photo (see fig. 5). Photo by Bruce E. Barnum, Sage Discovery.

Figure 7. Coal marker sands of the coal unit of the Mesaverde Group in 

the Deserado coal area. The unit consists of well-sorted, fine-grained, planarbedded, ripple-marked sandstone beds located at the top of the lower coal 

unit (see fig. 5). Photo by Bruce E. Barnum, Sage Discovery.

I6 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Coal Resources

The Deserado coal area contains an estimated original coal resource of about 

440 million short tons (Brownfield and others, chap. N, this CD-ROM) with more 

than 80 percent of the total coal resource contained in the B and D coal zones (fig. 

8). Coal resources were not calculated within the Deserado mine lease boundaries. 

Coal is presently mined by underground methods at the Deserado mine operated by 

Western Fuels, Inc. Coal from the Deserado mine is transported about 20 mi over a 

dedicated electric railroad to the Deseret Generation and Transmission power plant 

in northeastern Utah. Coal production averaged 1.44 million short tons per year from 

1989 to 1994. In 1997 the Deserado mine produced 1.1 million short tons of coal, 

accounting for 5 percent of the total coal produced in northwest Colorado (Resource 

Data International, Inc., 1998). Within the Deserado coal area, the actual amount of 

coal that can be recovered will be less than the assessed resource because the two 

major zones are close together and contain partings and splits restricting underground 

mining. Figure 8. The D coal zone of the main coal zone in the Deserado coal 

area. Photo by Bruce Barnum, Sage Discovery.

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potential of Northwest Colorado I7
Danforth Hills Coal Field

Location

The Danforth Hills coal field (figs. 2 and 3) is situated in 

northwest Colorado in Moffat and Rio Blanco Counties within 

the Rocky Mountain Coal Province of Tully (1996). The coal 

field lies north of the White River in the northeastern part of 

the Piceance Basin. The western boundary of the coal field is 

northern extension of the Grand Hogback and the northern part 

of the coal field is bounded by the Axial Basin.

The northern part of the Danforth Hills coal field is characterized by north- and east-trending ridges that are separated by 

steep canyons. The southwestern part of the Danforth Hills is 

characterized by steeply dipping, long, narrow hogbacks. Elevations in the coal field range from 6,200 to 8,700 ft.

Stratigraphy of Cretaceous and Tertiary Strata 

All of the coal-stratigraphic units exposed within the 

Danforth Hills coal field are of Cretaceous and Tertiary age 

(fig. 10). All the coal-bearing rocks considered in this study are 

included in the Upper Cretaceous Mesaverde Group. The lowest 

unit is the thick marine Mancos Shale of Upper Cretaceous 

age, which is overlain by the mostly nonmarine, coal-bearing 

Iles and Williams Fork Formations of the Mesaverde Group. 

The Mesaverde in this area generally consists of a thin to 

thick interbedded succession of shale, siltstone, and sandstone. 

Carbonaceous rocks are common, and thick beds of coal occur 

throughout the Mesaverde Group. The Mesaverde Group was 

deposited largely in a terrestrial environment, although regional 

relations indicate that this sedimentation was directly influenced 

by sea-level changes. 

Figure 9. Contact between the Upper Cretaceous Iles Formation and the Mancos Shale along the northern part of 

the Danforth Hills coal field.

(Text continues on next page.)

I8 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Rocks of marine or marginal-marine origin do occur within the Mesaverde, most 

notably the Trout Creek Sandstone Member of the Iles Formation. This persistent 

marginal marine sandstone is one of the best stratigraphic markers in the area. It 

is directly overlain by the Fairfield coal group (Hancock and Eby, 1930), which 

contains the most extensive coal resources in the area.

The Williams Fork Formation rocks were deposited along the western margin 

of the late Campanian to Maastrichtian Western Interior Seaway (Roberts and 

Kirschbaum, 1995). The area was located in a very favorable position for coal 

deposition, at or near the margin of the sea, resulting in the stacking of several 

thousand feet of coal-bearing strata along the coastal plain. These coal-bearing rocks 

typically show a cyclic pattern of coal deposition, which is reflected in the coal 

zones assessed in this study. Sedimentary processes associated with near-shore and 

fluvial deposition in this area have influenced the geometry and distribution of these 

coal deposits.

Coal Geology

The coal-bearing intervals in the Iles and Williams Fork Formations of the 

Mesaverde Group in the Danforth Hills were stratigraphically subdivided into five 

coal groups by Hancock and Eby (1930). The Iles Formation was subdivided into two 

units, the lower and the Black Diamond coal groups (fig. 10). The Williams Fork was 

subdivided into three coal units and one barren interval in this study. The units are, in 

ascending order, the Fairfield coal group, the barren interval, and the Goff coal group, 

and the Lion Canyon coal group (fig. 10).

The Williams Fork Formation contains the thick and economically important 

coal beds in the Danforth Hills coal field. Data from drill hole geophysical logs and 

geologic maps indicates that the Williams Fork is about 3,000 to 3,500 ft thick. 

Figure 10. Generalized stratigraphic column showing depositional 

environments for a portion the Upper Cretaceous and Tertiary rocks in the 

Danforth Hills coal field, Colorado. Shown are the major divisions of the 

Fairfield coal group and the Yampa bed (a tonstein) of the Williams Fork 

Formation. Yampa bed not drawn to scale. Named sandstones are shown in 

yellow. After Brownfield and others (chap. M, this CD-ROM).

Iles Formation

of the Mesaverde group

Williams Fork Formation

of the Mesverde Group Wasatch Fm. Fort Union Fm.

Paleocene-Eocene Upper Cretaceous

MancosSh.(part)

Black Diamond

coal group

lower

coal group

Fairfield coal

group

Goff coal

group

barren interval

Lion Canyon Ss. Mbr.- 

Lion Canyon

coal group

Trout Creek Ss. Mbr.

FGA

FGB

FGC

FGD

FGE

FGF

FGG

1000 feet

250 feet

Yampa bed

vvvvvvvvvvvvvv Yampa bed

vvvvvvvvvvvvvv

Alluvial, coastal plain, and mire

Upper shoreface 

and estuarine

Lower shoreface and 

offshore marine

Depositional environments

(Text continues on next page.)

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potential of Northwest Colorado I9
The Fairfield coal group is located at the base of the Williams Fork and has an average thickness of 1,300 ft (Hancock and Eby, 1930). In the lower part of the 

Fairfield coal group is a regionally persistent unit consisting of altered volcanic ash named the Yampa bed. The Yampa bed, introduced by Brownfield and Johnson 

(1986), is a regionally extensive tonstein (altered ash-fall tuff) in the lower part of the Williams Fork Formation (fig. 10). The Yampa bed was used to facilitate 

the correlation of coal beds in the Fairfield coal group throughout the Danforth Hills coal field. The Fairfield coal group is predominately terrestrial in origin and 

coals developed from peat that accumulated in a coastal-plain environment. The Goff coal group averages 700 ft thick and is separated from the Fairfield group 

by about 1,000 ft of rock containing little coal. The Lion Canyon coal group (Lance Formation equivalent in this study) of Hancock and Eby (1930) averages 

1,000 ft thick and directly overlies the Lion Canyon Sandstone Member of the Williams Fork Formation (Fox Hills Sandstone?) in the southwestern and western 

part of the Danforth Hills coal field (figs. 4 and 10).

The Fairfield coal group (Hancock and Eby, 1930) contains many potentially economic coal beds in the Danforth Hills coal field (fig. 10) and was the only 

coal-bearing unit assessed in this study (Brownfield and others, chap. M, this CD-ROM). The Fairfield coal group was divided into seven coal zones, the FGA, FGB, 

FGC, FGD, FGE, FGF, and FGG (fig. 10). Coal resources were calculated on each of the seven coal zones (table 1). The Fairfield coal group contains at least 26 

coal beds that have maximum thicknesses greater than 5 ft; 20 of these coal beds have thicknesses greater than 12 ft. The deeper drill holes, which penetrated most 

of the Fairfield coal group, consistently indicate a total net-coal thicknesses greater than 100 ft. The most significant deposits of this type occur in the FGB and FGE 

zones, each of which locally have net-coal bed thicknesses greater than 60 ft.

Table 1. Fairfield coal zones of the Williams Fork Formation showing thickness range, average thickness, number of coal beds, 

general net-coal thickness range, maximum net-coal thickness, and average stratigraphic distance above the Trout Creek 

Sandstone Member of the Iles Formation, Mesaverde Group, Danforth Hills coal field. 

Fairfield 

coal zone

Thickness 

range (feet)

Average zone 

thickness 

(feet)

Average stratigraphic

distance above Trout Creek 

Sandstone Member (feet)

Number of coal 

beds in zone

General net-coal 

thickness range

(feet)

Maximum netcoal thickness 

(feet)

FGG 2.5-410 160 970 1 to 6 5-20 >30 

FGF 3-310 210 760 1 to 7 10-40 >40 

FGE 7.5-500 280 480 1 to 9 10-50 >60 

FGD 3.5-248 120 360 1 to 4 10-20 >30 

FGC 12-195 115 240 1 to 5 10-30 >40 

FGB 6-230 110 130 1 to 5 20-30 >60 

FGA 17-280 130 0 1 to 5 10-20 >30 

I10 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Figure 11. Colowyo coal mine in the northern part of the Danforth Hills coal field. The mine 

produces coal from FGF and FGG zones (as many as nine beds) in the Fairfield coal group by 

dragline and truck-and-shovel methods.

Coal Resources

Hancock and Eby (1930) reported an estimated original coal resource on a coalgroup basis of 10.6 billion short tons to a depth of 3,000 ft for the Meeker 15’

quadrangle which includes the southern two thirds of the assessment unit. Landis 

(1959) reported an estimated original coal resource on an individual bed basis of 7.9 

billion short tons to a depth of 3,000 ft for the Danforth Hills coal field. Hornbaker 

and others (1976) reported an estimated original coal resource of 10.5 billion short 

tons to a depth of 6,000 ft for the Danforth Hills coal field.

This assessment study (Brownfield and others, chap. M, this CD-ROM) 

determined that the Fairfield coal group contains an estimated original coal resource 

of about 21 billion short tons in coal beds greater than 1.2 ft thick to a depth of 6,000 

ft. About 90 percent of the coal resource (19 billion short tons) is under less than 

3,000 ft of overburden. Coal production averaged 4.5 million short tons per year from 

1989 to 1996 at the Colowyo mine (fig. 11). In 1997, the Colowyo mine produced 4.3 

million short tons of coal, accounting for 18 percent of the total study area production 

(Resource Data International, 1998).

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potential of Northwest Colorado I11
Yampa Coal Field

Location

The Yampa coal field, covering about 520 mi2, is located in northwest Colorado 

and occupies parts of Routt and Moffat Counties and a very small part of Rio Blanco 

County (figs. 2 and 3). The Yampa coal field is bounded by the Park Range uplift 

to the east, the White River uplift to the south, and the Axial arch to the west. The 

coal field is also transversed by the west-flowing Yampa and Williams Fork Rivers. 

Elevations in the coal field range from about 6,000 ft above sea level near the town of 

Lay to just over 9,800 ft at the top of Pilot Knob in the northeastern part of the coal 

field. The coal field is characterized by rolling hills and northward-dipping slopes. 

Along the southern boundary of the coal field are rugged southwestward-facing cliffs 

deeply incised by gulches extending northward.

Figure 13. View of Trout Creek Sandtone Member of the Iles Formation. Middle 

coal group in the Williams Fork Formation is above the Trout Creek and the lower 

coal group of the Iles Formation is below the Trout Creek.

Figure 12. View of the Trout Creek Sandstone Member of the Iles Formation 

(thick sandstone just below red-baked rock unit) and the middle coal group (redbaked rock unit) in the Williams Fork Formation, Yampa coal field.

I12 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Mesaverde Group

In the Yampa coal fi eld, the Mesaverde Group is divided into two formations 

(fi g. 4), the Iles in the lower part and the Williams Fork in the upper part (Hancock, 1925). Included in the Iles is the Trout Creek Sandstone Member (fi gs. 12 and 13) 

at the top of the formation, and included in the Williams Fork is the Twentymile Sandstone Member in the middle of the formation. Both of these sandstones are regressive shoreface deposits, each is transitional with an underlying marine shale, and each is overlain by a thick unit of nonmarine rocks including fl uvial sandstone, overbank sandstone and mudrock, and carbonaceous shale and coal (fi g. 14). Earlier workers (Fenneman and Gale, 1906) defi ned coal in the Iles as the lower coal group, coal between the Trout Creek and the Twentymile as the middle coal group, and coal above the Twentymile as the upper coal group (fi g. 4). The Mesaverde comprises an eastward thinning, wedge-shaped package of marine and nonmarine rocks that overlies and intertongues with the Upper Cretaceous Mancos Shale and underlies the Upper Cretaceous Lewis Shale. Toward the west, the Mesaverde becomes increasingly more nonmarine. In central Utah equivalent strata are composed almost exclusively of conglomerate of terrestrial origin.

Because most of the economic coal is contained in the Williams Fork, resources 

were calculated for only those coals in the middle and upper coal groups. Several large mines are currently extracting coal from these two groups, and future coal leasing and subsequent mining will undoubtedly be restricted to coal in these two groups. 

Figure 14. Generalized northwest-southeast cross sectYampa coal fi eld showing depositional environments ansandstone units. Modifi ed after Johnson and others (ch

Three White sandstones

Big White sandston

Sub-Twen

Tow Creek SandstoneMember of the Iles Forma

MANCOS SHALE

MESAVERDE GROUP

LEWIS SHALE

NW 

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potent
Coal Geology

Both Cretaceous- and Tertiary-age coal occurs in the Yampa coal fi eld. The 

Upper Cretaceous Lance Formation contains a minor amount of coal, and there is a signifi cant amount in the Paleocene Fort Union Formation. However, there is currently no interest in extracting coal from either of these formations, and therefore they were not included in the assessment. Of the three coal groups in the Mesaverde, only the middle and upper groups of the Williams Fork Formation (fi g. 4), were considered in this assessment (Johnson and others, chap. P, this CD-ROM). To better defi ne the occurrence of coal, four coal zones and three barren intervals were established (fi g. 15). The middle coal group contains the A coal zone (AZ), barren interval A (BIA), the B coal zone (BZ), and barren interval B (BIB), in ascending order. The upper coal group contains the C coal zone (CZ), barren interval C (BIC), and the D coal zone (DZ).

Within the A coal zone is a regional, altered, ash-fall tuff (tonstein) called the 

Yampa bed (Brownfi eld and Johnson, 1986). The unit is an important regional marker that is easily identifi ed on drill hole geophysical logs and was used to facilitate correlation of coals in the Williams Fork Formation (fi g. 15).

During deposition of the Williams Fork, the area that is now northwestern 

Colorado was at a latitude of about 42 degrees north (Roberts and Kirschbaum, 1995), and had a humid, subtropical climate. This, coupled with a high water table characteristic of a lower coastal plain depositional setting, was conducive to the development of a complex network of peat swamps.

Figure 15. Stratigraphic column showing the midgroups of the Williams Fork Formation, Yampa coafter Johnson and others (chap. P, this CD-ROM)drawn to scale.

Big WhitesandstoneThree WhitesandstonesTwentymile SandstoMemberSub-TwentymilesandstoneYampa bedTrout Creek SandstoMember 0

400'600'800'

1000'1200'1400'1600'1800'

BIC

CZ

BIB

BZ

BIA

AZAZDZDZ

200'

Iles Formation

Williams

Fork

Formation

Depo

I14 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Figure 16. View of the Eagle # 5 longwall mine, middle coal group, 

Williams Fork Formation, Yampa coal field. The Eagle # 5 mine is 

temporarily closed.

Figure 17. Looking north from the Trapper strip mine at the Tri-State power 

plant. Cedar Mountain, to the left of the plant, consists of Oligocene and 

Miocene Browns Park Formation capped by basalt. To the north is the Sand 

Wash Basin.

Coal Resources

The Yampa coal field contains an estimated coal resource of about 76 billion 

short tons in beds equal to or greater than 1.2 ft (Johnson and others, chap. P, this 

CD-ROM). Although a significant amount of coal remains in the coal field, this 

figure must be regarded with caution. For example, of the 76 billion tons, about 52 

percent is under more than 3,000 ft of overburden and thus with current technology is 

unavailable for underground mining. But even more significant, about 90 percent of 

the coal is under more than 500 ft of overburden, and is thus unavailable for surface 

mining. It is apparent that only a small percentage of the 76 billion tons of remaining 

coal resource could be recovered.

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potential of Northwest Colorado I15
Figure 19. Stratigraphic correlations and facies relationships in the Mesaverde Group and 

Mesaverde Formation, southern Piceance Basin, Colorado. Abbreviations include: Sandstone 

(Ss.), sandstone (ss.), Member (Mbr.), coal zone (cz), Shale (Sh.), Group (Gp.), Formation (Fm.), 

and part (pt.). After Hettinger and others (chap. O, this CD-ROM).

Figure 18. View of the Cameo coal zone (red baked strata) above the Rollins 

Sandstone Member of the Mount Garfield Formation of the Mesaverde Group, 

Layton Wash, southern Piceance Basin. Photo by Mark A. Kirschbaum, U.S. 

Geological Survey.

Southern Piceance Basin

Location

The Southern Piceance Basin study area is located in west-central Colorado and 

includes areas south of lat 39°42'30"N. that are underlain by the Mesaverde Group 

or Mesaverde Formation within the Piceance and Uinta Basins (fig. 3). The eastern 

boundary of the study area is delineated by the Grand Hogback monocline (fig. 3). 

The southeasternmost part of the study area is delineated along the beveled edge of 

the Mesaverde Formation below Oligocene volcanics in the West Elk Mountains. 

The study area occupies about 4,140 mi2 within parts of Delta, Garfield, Gunnison, 

Mesa, Pitkin, and Rio Blanco Counties (fig. 2). Transportation routes include 

Interstate 70, State and local highways, and the Denver and Rio Grande Western 

Railroad.

Coal Geology

In the southern part of the Piceance Basin, the coal beds of the Mesaverde 

Group or Formation are contained in the Black Diamond and Cameo-Fairfield coal 

groups. Details regarding the stratigraphic position and nomenclature of coal zones 

in each coal group are provided in Hettinger and others (chap. O, this CD-ROM). 

The Black Diamond coal group underlies the Rollins Sandstone (fig. 19) and Trout 

Creek Sandstone Members of the Iles Formation (fig. 21) and contains the Anchor, 

Palisade, and Chesterfield coal zones. The Cameo-Fairfield coal group overlies the 

Rollins Sandstone and Trout Creek Sandstone Members and contains the Wheller, 

South Canyon, and Coal Ridge coal zones. It contains the most extensively 

Book Cliffs coal field Grand Mesa and Somerset coal fields Carbondale coal field

Mesaverde Fm.

(part)

Mesaverde Fm. (part)

Coal-bearing 

Mbr.

Barren Mbr. (part)

Castle- gate Ss.

Upper part of the Sego Ss. Sego 

Ss. Anchor Mine Tongue of Mancos Shale

Buck Tongue of Mancos Shale

Corcoran Ss. Mbr.

Cozzette Ss. 

Mbr.

Rollins Ss. Mbr.

Rollins Ss. Mbr.

middle ss.

upper ss.

Cameo cz

Carbonera cz

Coal Ridge cz

South Canyon cz

Wheeler cz

Anchor cz

Palisade cz

Chesterfield cz

Mancos Sh. 

(part)Mount Garfield and Hunter Canyon Formations (part)

Measverde Gp. (pt) and tongues of the Mancos Shale

West East

Lower part of the Sego Ss.

Bowie 

Shale 

Mbr.

Paonia 

Shale 

Mbr. (part)

Williams Fork Fm. (part) Iles Formation

Mancos 

Shale 

(part)

Rollins 

Ss. Mbr.

Cozzette Ss Mbr. Cozzette

Ss Mbr.

tongue of

Mancos 

Shale

Mesaverde Group

Alluvial, coastal plain and mire; 

coal zones are in dark gray

Upper shoreface 

and estuarine

Lower shoreface and 

offshore marine Depositional environments

Inset

Book Cliffs

Carbondale

Crested

Butte

Lines of

section

Study

area

Grand Mesa

Grand Hogback

(Text continues on next page.)

I16 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Figure 21. Stratigraphic correlations and facies relations

Mesaverde Formation, southern part of the Piceance BasSandstone (Ss.), sandstone (ss.), Member (Mbr.), coal zonFormation (Fm.), and part (pt.). After Hettinger and others 

Figure 20. View of the palisades on the western end of Grand Mesa overlooking the town of Palisade, Colo. Cameo coal zone (burn zone) above Rollins Sandstone Member of the Mount Garfi eld Formation. The Corcoran Sandstone is the white sandstone in the lower cliff. Photo by Mark A. Kirschbaum, U.S. Geological Survey.

mined coals in the southern Piceance Basin and is also an important source for coal-bed gas (Johnson, 1989). The Cameo-Fairfi eld coal group is 4 to 1,400 ft thick and covers 4,140 mi2 in the southern Piceance Basin. It contains the Cameo and Carbonera coal zones (Book Cliffs coal fi eld), the Cameo (fi gs. 18, 20, and 22) coal 

zone (Grand Mesa coal fi eld), the coal-bearing member (Somerset coal fi eld), and 

the Wheeler-Fairfi eld, South Canyon, and Coal Ridge coal zones (Grand Hogback and Carbondale coal fi elds) (fi gs. 19 and 21). In the Crested Butte coal fi eld, the 

Cameo-Fairfi eld coal group contains the informally named lower, middle, and upper coal zones (fi g. 21).

Grand Hogback coal field (southern part) Carbondale coal fie

 Sego Ss. Mbr.

Corcoran Ss. Mbr.

Cozzette Ss. Mbr. 

middle ss.

Coal Ridge cz

South Canyon cz

Wheeler-Fairfield cz

Northwest 

upper ss.

Williams Fork Formation (part) Iles Formation

Mesaverde Group (part)

Mancos Sh. 

(part)

Rollins Ss. Mbr.

Cozzette Ss. Mbr

Alluvial, coastal plain and mire; coal zones are in dark gray 

Depositional environments

Trout Creek Ss. Mbr.

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potent
Figure 22. View of Cameo-Wheeler coal zone (red-baked rock) above the 

Rollins Sandstone Member of the Mount Garfield Formation of the Mesaverde 

Group near Hunter Canyon, southern Piceance Basin. Photo by Mark A. 

Kirschbaum, U.S. Geological Survey.

Coal Resources

Original coal resources have been determined for each coal zone in the CameoFairfield coal group in the southern Piceance Basin, and are reported by overburden, 

county, township, 7.5' quadrangle, and surface and coal ownership (Hettinger and 

others, chap. O, this CD-ROM). The Cameo-Fairfield coal group contains about 48 

billion short tons of coal that are in beds greater than 1 ft thick and under less than 

3,000 ft of overburden. The coal group also has about 72 billion tons of additional 

coal that are under 3,000 to 6,000 ft of overburden. Underground mining is the most 

likely method for extracting coal in this part of the Piceance Basin (Speltz, 1976), and 

historic production compiled by Eakins and Coates (1998) indicates that about 176 

million tons of coal has been mined. Hettinger and others (chap. O, this CD-ROM) 

estimate that only 34 billion tons of coal in the Cameo-Fairfield group meet favorable 

underground mining criteria of depth less than 3,000 ft and bed thickness greater 

than 3 ft. In 1997, the southern Piceance Basin produced 32 percent of the total coal 

production in northwest Colorado or about 7.7 million short tons of coal (Resource 

Data International, 1998).

I18 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
Coal-Bed Methane in Northwest Colorado

Piceance Basin 

The Piceance Basin is producing coal-bed gas from five fields (fig. 23): the 

Grand Valley, Parachute, and South Shale Ridge fields in the Southern Piceance 

study area (fig. 24) and the White River Dome and Pinyon Ridge fields in the 

northern part of the Piceance Basin (Johnson and Flores, 1998). Gas content for 

coals in the Piceance Basin is as much as 604 cubic feet per short ton (Tremain, 

1990; Reinecke and others, 1991). Scott and others (1996) estimated that the 

deepest part of the Piceance Basin has a gas-in-place coal-bed methane resource 

that exceeds 60 billion cubic feet of gas (BCFG) per square mile and that most of 

that resource is within the Cameo-Fairfield coal group.

The best production rates in the Piceance Basin thus far are from the 

White River Dome field a few miles southwest of the Danforth Hills coal field. 

Production rates have been gaged as high as 3,080 Mcf/d of gas and 96 barrels of 

water per day (Johnson and Flores, 1998). Through 1995, the White River Dome 

produced 3,656 MMcf of coal-bed gas (Tyler and others, 1995). The field has 

also produced 2,200 barrels of liquid hydrocarbons. White River Dome produces 

from the Fairfield coal group (Cameo-Fairfield coal zone in the southern Piceance 

Basin) of the Williams Fork Formation at depths ranging from about 5,400 to 

6,400 ft. North of the White River dome the Pinyon Ridge field also produces gas 

(at depths greater than 1,300 ft) from the Williams Fork.

Figure 24. Gas well in the southern Piceance Basin. Photo by 

Ronald Johnson, U.S. Geological Survey.

Figure 23. Gas fields producing coal-bed methane in northwest Colorado. Gas fields 

are approximately located.

0 50 100 Miles

Colorado

OURAY

MONTROSE

DELTA

GUNNISON

MESA PITKIN

EAGLE

ROUTT

GARFIELD

RIO BLANCO

Dinosaur National MOFFAT

Monument

Axial Basin

Eastern Sand

Wash Basin

Piceance Basin

Delta

Paonia

Somerset Crested Butte 

Grand Junction Marble 

Redstone

Rifle

New Castle

Rio Blanco

Meeker

Rangely

Dinosaur

g

Gas fields producing

coal-bed methane

1. Grand Valley

2. Parachute

3. South Shale Ridge

4. White River Dome

5. Pinyon Ridge

Outcrop of Cretaceous

coal-bearing rocks

Craig

Carbondale

Glenwood Springs 1

2

3

4

5

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potential of Northwest Colorado I19
The coals within Deserado coal area contain methane and must be degassed as 

part of the mining process (George Ohera, Western Fuels, oral commun., 1998). The 

potential for commercial production of natural gas in the Piceance Basin remains 

largely unproven; through 1994, cumulative production of natural gas from coals 

approached 19 BCFG (Scott and others, 1996).

Sand Wash Basin

Extensive coal resources occur in the Upper Cretaceous Mesaverde Group 

and Lance Formation, and the lower Tertiary Fort Union Formation in the Sand 

Wash Basin of northwest Colorado. These coals are mainly subbituminous to highvolatile B bituminous (rank determined by vitrinite reflectance) and have average gas 

contents of less than 200 cubic feet per short ton. However, some coals have a gas 

content exceeding 540 cubic feet per short ton (Kaiser and others, 1993). Kaiser and 

others (1993) estimate that the coal-bed methane resources of the Sand Wash Basin 

are at least 101 Tcf and that 24 Tcf is estimated to be at depths of less than 6,000 

ft. Cumulative gas production has been small, with 84 MMcf through 1992. The 

potential for commercial production of gas in the Sand Wash Basin is low because of 

the low gas content and largely unproven because of the large water volumes that are 

produced along with the gas (Kaiser and others, 1993).

Summary

The Lower White River, Danforth Hills, Yampa, and Southern Piceance Basin 

assessment units contain an estimated coal resource of about 217.4 billion short tons 

of coal to a depth of 6,000 ft. About 48 percent, or 104 billion short tons, of coal 

is under less that 3,000 ft of overburden. Although there is a significant amount of 

coal in northwest Colorado, this figure should be regarded with caution because it 

does not reflect economic, land-use, and environmental, technological, and geologic 

constraints that might limit coal availability and recoverability.

The future of coal mining appears bright. The industry will continue to support 

the local economy by providing jobs and by purchasing goods and services from 

local suppliers. However, over the next decade most of the coal produced will come 

from areas presently under lease and from coal mines already in existence. Coal 

mining will remain an important social and economic factor in northwest Colorado 

well into the 21st century.

I20 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah
References Cited

Barnum, B.E. and Garrigues, R.S., 1980, Geologic map and coal sections of the Cactus 

Reservoir quadrangle, Rio Blanco and Moffat Counties, Colorado: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-1179, scale 1:24,000.

Eakins, Wynn and Coates, M.M., 1998, Focus: Colorado coal: Colorado Geological Survey Rock 

Talk, v. 1, no. 3, 6 p.

Fenneman, N.M., and Gale, H.S., 1906, The Yampa coal field, Routt County, Colorado: U.S. 

Geological Survey Bulletin 297, 96 p.

Hancock, E.T., 1925, Geology and coal resources of the Axial and Monument Butte 

quadrangles, Moffat County, Colorado: U.S. Geological Survey Bulletin 757, 134 p.

Hancock, E.T., and Eby, J.B., 1930, Geology and coal resources of the Meeker quadrangle, 

Moffat and Rio Blanco Counties, Colorado: U.S. Geological Survey Bulletin 812-C, p. 191-242.

Hornbaker, A.L, Holt, R.D., and Murray, D.K., 1976, 1975 summary of coal resources in Colorado: 

Colorado Geological Survey Special Publication No. 9, 17 p.

Johnson, R.C., and Flores, R.M., 1998, Developmental geology of coalbed methane from shallow 

to deep in Rocky Mountain basins and in Cook Inlet-Matanuska Basin, Alaska, U.S.A. and 

Canada: International Journal of Coal Geology v. 35, p. 241-282.

Kaiser, W.R., Scott, A.R., Hamilton, R.T., McMurry, R.G., Zhou, Naijiang, Fisher, W.L., Tremain, 

C.M., 1993, Geologic and hydrologic controls on coalbed methane: Sand Wash Basin, 

Colorado and Wyoming: Gas Research Institute Topical Report, 151 p.

Landis, E.R., 1959, Coal resources of Colorado: U.S. Geological Survey Bulletin 1072-C, 

p. 131-232.

Resource Data International, Inc., 1998, COALdat database: Boulder, Colorado, Resource Data 

International, Inc. [1320 Pearl Street, Suite 300, Boulder, CO 80302]. 

Reinecke, K.M., Rice, D.D., and Johnson, R.C., 1991, Characteristics and development of fluvial 

sandstone and coalbed reservoirs of Upper Cretaceous Mesaverde Group, Grand Valley 

field, Garfield County, Colorado, in Murray. D.K., and Fahy, M.F., eds., Coalbed Methane of 

Western North America: Rocky Mountain Association of Geologists Guidebook, p. 209-225.

Roberts, L.N., and Kirschbaum, M.A., 1995, Paleogeography of the Late Cretaceous of the 

Western Interior of Middle North America—Coal distribution and sediment accumulation: 

U.S. Geological Survey Professional Paper 1561, 115 p.

Scott, A.R., Tyler, Roger, Kaiser, W.R., McMurry, R.G., Nance, H.S., and Tremain,C.M., 1996, 

Coal and coalbed methane resources and production in the Piceance Basin, Colorado, in

Geologic and Hydrologic Controls Critical to Coalbed Methane Producibility and Resource 

Assessment: Williams Fork Formation, Piceance Basin, Northwest Colorado: Gas Research 

Institute Topical Report 95/0532, December 1, 1993-November 30, 1993, p. 269-285.

Speltz, C.N., 1976, Strippable coal resources of Colorado—Location, tonnage, and 

characteristics of coal and overburden: U.S. Bureau of Mines Information Circular 8713, 70 p.

Tremain, C.M., 1990, Coalbed methane development in Colorado: Colorado Geological Survey 

Open-File Report 82, 48 p.

Tully, John, 1996, Coal fields of the conterminous United States: U.S. Geological Survey OpenFile Report 96-92, 1 plate, scale 1:5,000,000.

Tyler, Roger, Kaiser, W.R., Scott, A.R., Hamilton, D.S., and Ambrose, W.A., 1995, Geologic and 

hydrologic assessment of natural gas from coal: Greater Green River, Piceance, Powder 

River, and Raton Basins, Western United States: Austin Texas, Bureau of Economic Geology, 

Report of Investigation 228, 219 p.

National Coal

Resource

Assessment

Click here to return to Disc 1 

Volume Table of Contents

A Summary of the Stratigraphy, Coal Resources, and Coal-Bed Methane Potential of Northwest Colorado I21