Executive Summary—

Geologic Assessment of Coal

in the Colorado Plateau: Arizona,

Colorado, New Mexico, and Utah

By Mark A. Kirschbaum1

Executive Summary 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

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

U.S. Department of the Interior

U.S. Geological Survey

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 ................................................................................................................................................... 1

Previous USGS Assessments ..................................................................................................................... 1

Assessment Methodology........................................................................................................................... 2

Assessment Results ..................................................................................................................................... 2

Geology.................................................................................................................................................. 2

Databases ............................................................................................................................................. 3

Resources ............................................................................................................................................. 4

Coal Quality........................................................................................................................................... 5

Summary of Assessment Units.......................................................................................................... 6

Kaiparowits Plateau Assessment Unit.................................................................................... 6

Henry Mountain Basin Assessment Unit................................................................................ 6

Southern Wasatch Plateau Assessment Unit........................................................................ 6

Northern Wasatch Plateau Assessment Unit ........................................................................ 6

Deserado Assessment Unit of the Lower White River Coal Field....................................... 6

Danforth Hills Assessment Unit................................................................................................ 6

Yampa Assessment Unit ............................................................................................................ 7

Southern Piceance Assessment Unit...................................................................................... 7

Somerset Assessment Unit....................................................................................................... 7

San Juan Basin Assessment Unit............................................................................................ 7

Bisti Assessment Unit ................................................................................................................ 7

Black Mesa Basin Assessment Unit ....................................................................................... 7

Conclusions ................................................................................................................................................... 7

References Cited .......................................................................................................................................... 8

Figures

 1. Map showing location of Colorado Plateau study area in the United States 

in relation to other coal assessment areas of the National 

Coal Resource Assessment Project.......................................................................................... 2

 2. Map showing assessment units of the Colorado Plateau Project ....................................... 2

 3. Montage of geologists who worked for or in cooperation with the 

USGS on coal in the Colorado Plateau ..................................................................................... 3

 4. Diagrammatic cross section showing coal and sandstone correlations, 

and depositional environments from subsurface information interpreted 

from geophysical logs and outcrop measurements ............................................................... 3

 5. Diagrammatic maps showing total-coal thickness of selected 

assessment units with respect to their locations within the Colorado 

Plateau and the four-State region of Arizona, Colorado, New Mexico, and Utah............. 4
 6. Chart of combined original identified and hypothetical resources and 

median values of ash, sulfur, and heating values for priority assessment 

units of the Colorado Plateau ..................................................................................................... 5

 7. Chart of resource estimates for 20 selected coal zones of the Colorado Plateau ............ 5

 8. Uncertainty estimates for the identified category of coal resources of 

selected coal zones...................................................................................................................... 6
1

Introduction

In the Southwestern United States, signifi cant deposits of 

Cretaceous coal are concentrated in a coherent physiographic 

and geologic province known as the Colorado Plateau, located 

within a 165,000-mi2 area of the States of Arizona, Colorado, 

New Mexico, and Utah (fi gs. 1 and 2). The Colorado Plateau 

is one of fi ve coal-producing areas that are being studied as 

part of the National Coal Resource Assessment Project (fi g. 

1). Presented here is a geologic assessment of coal deposits 

of the Colorado Plateau region and new resource estimates 

for selected assessment units within the Colorado Plateau. 

Detailed cross sections and maps of coal distribution, structure, and overburden were produced for each assessment unit 

from digital stratigraphic and geographic databases newly created during this study. The geology was interpreted by individuals with long-term experience in coal geology and in 

the geographic areas chosen for assessment. Original resource 

estimates (in-place resources before production) for the 12 

priority assessment units of the Colorado Plateau exceed one 

half trillion short tons of coal in beds greater than 1 ft thick and 

under less than 6,000 ft of overburden. The original resource 

number provides a means of comparing one assessment unit 

to another and is useful for estimating the potential volumes 

of gas in the coal. The large total resource number in the 

Colorado Plateau is only a starting point for understanding 

how much coal is actually minable because of the many geologic, geochemical, economic, and technical restrictions that 

are limiting factors to the ultimate recovery of coal from the 

ground.

As of 1995, there were 10 major surface and 21 major 

underground mines on the plateau that produced more than 

85 million cumulative short tons of coal (Resource Data International, 1998). About 85 percent of the coal mined in the 

Colorado Plateau is used for the generation of electric power. 

Coal from this region was sold to electric generating power 

plants in 20 States in the United States (as of 1995), but the 

main consumers were the States of Arizona, New Mexico, 

Utah, Colorado, and Nevada. Between 1990 and 1997, Colorado Plateau coal was also shipped to Colombia, Chile, Hong 

Kong, Japan, Philippines, South Korea, and Taiwan; in 1995 

about 2.5 million short tons were exported (Resource Data 

International, 1998). The plateau is not only an important coalmining region, but also has large natural gas resources that 

are derived in part from the coal. The Colorado Plateau is 

estimated to contain as much as 173 trillion cubic feet of inplace coal-bed-gas resources within three producing areas: the 

Piceance Basin in Colorado, the San Juan Basin in Colorado 

and New Mexico, and the Uinta Basin (Wasatch Plateau) in 

Utah (ICF, 1989; Rice, 1996).

Previous USGS Assessments

The U.S. Geological Survey (USGS) has explored for 

coal and provided estimates of the coal resources within the 

Colorado Plateau region since the beginning of the 20th century (fi g. 3). The fi rst comprehensive studies of the original 

coal resources of the continental United States were compiled 

by Campbell and Parker (1909) and by Campbell (1917) as a 

result of the 1906 withdrawal from public acquisition of about 

66 million acres of coal lands by President Theodore Roosevelt 

following the misuse of the Homestead Act in acquiring federally administered lands for mining purposes. Detailed studies 

of all the major coal fi elds in the United States continued 

into the 1930’s, and the USGS and State geological surveys 

subsequently summarized the results for each State in the 

1950’s through the early 1970’s (e.g., Landis, 1959). These 

State reports were compiled and updated by Averitt (1975). 

Abundant data collected and analyzed during the last 30 years 

following the energy crisis of the early 1970’s supplements 

older data to provide the most up-to-date assessment of 12 

areas within the Colorado Plateau.

Executive Summary— 

Geologic Assessment of Coal 

in the Colorado Plateau: Arizona, 

Colorado, New Mexico, and Utah

By Mark A. Kirschbaum
2 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah

Assessment Methodology

Four main criteria were used to determine coal assessment units within the Colorado Plateau region: (1) areas with 

signifi cant amounts of federally owned coal, (2) areas with 

active coal mining, (3) areas where coal-bed methane is currently being produced, and (4) areas with a high coal resource 

or development potential.

Twelve areas ranging from 22 mi2 to 6,218 mi2 were 

assessed using different levels of detail (fi g. 2). In most of 

the assessment areas, digital databases were not available for 

analysis. Raw data was collected from outcrop measurements 

and interpreted from geophysical logs. Analysis was limited 

in some areas because data were sparse. In other areas, information was selected from large amounts of raw data—for 

example, in the Kaiparowits Plateau. The variability and availability of the data determined the scale and detail of the studies. Some areas were analyzed at a basin or coal-fi eld scale, 

in which case correlations were restricted to distinguishing 

coal zones, whereas, in other cases, for instance the Northern 

Wasatch Plateau assessment unit, it was possible to analyze 

individual coal beds.

Methods for gathering data and computing the volumes of 

coal were adapted from Wood and others (1983) (see Roberts 

and others, chap. C, this CD-ROM). Due to the digital nature 

of the data and the many data formats and sources, new methods were established to manipulate and manage the data. Ultimately, all data were managed and stored using a geographic 

information system (GIS) (see Biewick and Mercier, chap. 

D, this CD-ROM). An automated process was developed to 

extract data from the stratigraphic databases in order to generate structure, coal isopach, and overburden maps and to calculate coal resources. A new method for estimating uncertainty 

in calculating resource estimates was developed during the 

course of the National Coal Resource Assessment Project that 

places 90 percent confi dence limits on the volumes of coal 

calculated (see Schuenemeyer and Power, in press).

Assessment Results

Geology

Economically produced coals of the Colorado Plateau are 

entirely Cretaceous in age. The coal originally accumulated in 

coastal-plain wetlands located adjacent to ancient shorelines 

of a seaway that covered middle North America for much 

of the Cretaceous Period. A record of these paleoshorelines 

is preserved today as continuous sandstone deposits. An understanding of the sandstones is critical to correlating the associated coal deposits because the sandstones are more visible on 

outcrop, have a more consistent geophysical log signature, and 

can be used to predict the limits of thick coal deposits.

Therefore, a stratigraphic framework was developed from 

outcrop and drill-hole data for each of the assessment units, 

Appalachian

Basin

Northern

Rocky Mountains and

Great Plains

 Colorado

Plateau

Gulf Coast

Illinois Basin

Figure 1. Map showing location of Colorado Plateau study area 

(green) in the United States in relation to other coal assessment areas 

(other colors) of the National Coal Resource Assessment Project. 

Gray areas represent coal regions not studied in detail during this 

National Assessment. 

Coal-bearing

 strata

Study area

Assessment Units

1. Kaiparowits Plateau

2. Henry Mts Basin

3. S. Wasatch Plateau

4. N. Wasatch Plateau

5. Deserado

6. Danforth Hills

7. Yampa

8. S . Piceance Basin

9. Somerset

10. San Juan Basin

11. Bisti

12. Black Mesa Basin

1

2

3

4

5

6

7

8

9

10

12 11

113

113

34 34

40 40

106

106

0 100 Miles

Colorado Plateau study area

AZ

UT NMCO

Gallup

Durango

Cedar

 City

Moab

Price

Albuquerque 

Socorro 

Flagstaff

Grand 

Junction

40

25

40

15

70

Figure 2. Map showing assessment units of the Colorado Plateau 

Project. Twelve areas were studied in various levels of detail, and 

the results of these studies are presented within this CD-ROM. The 

Northern Wasatch Plateau (4) (Tabet and others, 1999), the Somerset 

(9) (Eakins and others, 1998), and the Bisti area (11) (Hoffman and 

Jones, 1998) are summarized in Rohrbacher and others (chap. F, this 

CD-ROM).
Executive Summary 3

and cross sections were generated. The cross sections show 

correlations of the sandstone units as well as the coals to 

illustrate the importance of the relationship of the shoreline 

deposits to the coal deposits (fi g. 4). Stratigraphic databases 

were assembled along with framework studies. The framework 

studies and accompanying databases were used to construct 

isopach maps that show the areal distribution of the coal (fi g. 

5) and overburden maps that show the depth of burial of the 

main coal deposits.

Databases

Stratigraphic databases are provided here for seven areas 

and contain public, but not proprietary, information on point 

location (latitude and longitude), key formation tops, and coal 

thickness. The databases include 226 locations for the Kaiparowits Plateau, 308 locations for the Southern Wasatch Plateau unit, 10 locations from the Lower White River (Deserado) 

coal fi eld (about 200 additional proprietary logs were used in 

this study), 108 locations from the Danforth Hills coal fi eld 

(another 432 are proprietary), 175 locations from the Yampa 

coal fi eld, 627 data points from the Southern Piceance Basin 

unit, and about 800 data points from the San Juan Basin. 

Although proprietary data was used in some of these projects, 

none of that proprietary data is included in the databases. The 

database fi les are stored on disc 2 of this CD-ROM in DBF, 

ASCII, and Excel formats. Databases are not provided for the 

Henry Mountains, Black Mesa, Bisti, Somerset, or Northern 

Wasatch Plateau assessment units.

Figure 3. Montage of geologists who worked for or in cooperation 

with the USGS on coal in the Colorado Plateau.

Southwest Northeast

Braided river Coastal plain Shoreface Offshore Coal Coal zone

14 miles

1000 ft

Modified from Hettinger and others (chap. T, this CD-ROM) Outcrop

UT

Figure 4. Diagrammatic cross section showing coal and sandstone correlations, and depositional environments 

from subsurface information interpreted from geophysical logs and outcrop measurements (after Hettinger and 

others, chap. T, this CD-ROM). Cross section is located southwest to northeast across the Kaiparowits Plateau; 

see inset of State of Utah for location of Kaiparowits Plateau.
4 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah

Resources

Original resource estimates for the 12 priority assessment 

units of the Colorado Plateau exceed one-half trillion short 

tons of coal (fi g. 6) in beds greater than 1 ft thick and under 

less than 6,000 ft of overburden. Resources do not include 

mined-out coal, and in most cases do not include areas currently under lease by mining companies. Twenty coal zones 

are compared to estimate the relative concentrations of coal 

in seven assessment units of the Colorado Plateau (fi g. 7). 

The Yampa A zone has the highest concentration of coal—68 

million short tons per square mile (mst/mi2)—and the Deserado D zone of the Lower White River coal fi eld has the 

lowest concentration—7 mst/mi2. Presenting the data in this 

way allows comparison between areas and may suggest areas 

of high potential for mining or gas exploration.

Once stratigraphic frameworks and databases have been 

created and original resources have been calculated, we can 

estimate how much of the resource is restricted from mining 

because of legal, regulatory, social, environmental, and technical considerations (see Rohrbacher and others, chap. F, this 

CD-ROM). Coal availability studies conducted in the Somerset, Bisti, and Northern Wasatch Plateau assessment units 

(Eakins and others, 1998; Schultz and others, 1999; Hoffman 

and Jones, 1998; and Tabet and others, 1999) show that a range 

of 40 to 86 percent of the original coal resource is available for 

mining. Recoverability studies have been completed on 14 7.5′

quadrangles, including one in Somerset, four in Bisti, and nine 

in the Northern Wasatch Plateau assessment unit.

Uncertainty estimates are provided for 10 coal zones from 

fi ve of the assessment units (fi g. 8). The estimated error for 

identifi ed resources (that is, coal resources within 3 miles of 

Southern Wasatch Plateau Southern Piceance Basin

Kaiparowits Plateau San Juan Basin

Coal-bearing

 strata

Study area

AZ

UT

NM

CO

20

Cuba

Figure 5. Diagrammatic maps showing total-coal thickness of selected assessment units with respect to their 

locations within the Colorado Plateau and the four-State region of Arizona, Colorado, New Mexico, and Utah. For 

details of maps see technical reports. On maps of the assessment units, yellow represents areas of thinner total 

coal (approximately 0–40 ft thick) and dark orange represents areas where total coal is greater than 100 ft thick. 

Areas of gray show where there is no coal or indicate the outcrop of the assessment unit; blue indicates igneous 

intrusions (Southern Piceance Basin assessment unit only).
Executive Summary 5

a coal measurement) ranges from 3 to 39 percent for the 10 

sampled areas. This error appears to be largely a function of 

the data density and the uniformity of data distribution.

Coal Quality

Coals of the Colorado Plateau are generally subbituminous to bituminous in rank, with mean calorifi c values as low 

as 8,130 Btu/lb in the Bisti coal fi eld to as high as 14,000 

Btu/lb in the Carbondale coal fi eld. The sulfur content is 

relatively low when compared to other U.S. coal, and the mean 

range of sulfur is between 0.3 and 1.6 percent throughout the 

Colorado Plateau. Within the assessment units, mean values 

are less than 1 percent sulfur. Ash yields are also generally 

low, although the range is from about 5 percent to almost 25 

percent. Mean values for the assessment units based on USGS 

data (see Affolter, chap. G, this CD-ROM) are provided in 

fi gure 6.

Assessment area Resources Ash yield* (percent)Sulfur*

(percent)

Calorific value*

(Btu/lb)

Black Mesa

Danforth Hills

Bisti 1,600 22.9

7.7

7.3

10.2

6.5

13.7

9.2

10.0

10.1

10.6

**  

8.1

20.1

0.5

0.5

0.5

0.6

0.6

0.6

0.6

0.6

0.5

0.4

0.7

0.7

8,130 

11,050 

11,090 

11,190 

10,790 

10,010 

10,050 

10,830 

12,480 

11,730 

9,360 

8,940 

** *

* Median values on as-received basis ** N. Wasatch is combined with S. Wasatch *** not calculated

21,000

1,700

61,000

370

6,800

230,000

120,000

9,200

3,100

Yampa 76,000

Grand total 530,000

Lower White River

S. Wasatch Plateau

San Juan Basin

S. Piceance Basin

Kaiparowits Plateau

N. Wasatch Plateau

Somerset

Henry Mountains

Figure 6. Chart of combined original identifi ed and hypothetical 

resources and median values of ash, sulfur, and heating values for 

priority assessment units of the Colorado Plateau. Coals assessed 

are in beds greater than 1 ft thick and under less than 6,000 ft of 

overburden. Resources are in millions of short tons and are rounded 

to two signifi cant fi gures; total will not sum due to independent 

rounding. Geochemistry is reported using data analyzed from USGS 

database.

Yampa A zone (7)

John Henry Member zone (1)

Cameo/Wheeler zone (8)

Danforth E zone (6)

Fruitland Formation zone (10)

Yampa D zone (7)

Yampa B zone (7)

Danforth B zone (6)

Danforth F zone (6)

Danforth C zone (6)

South Canyon zone (8)

 Blackhawk Formation zone (3)

Danforth A zone (6)

Danforth D zone (6)

Cameo/Fairfield east zone (8)

Coal Ridge zone (8)

Danforth G zone (6)

Yampa C zone (7)

Deserado B zone (5)

Deserado D zone (5)

0

10

20

30

40

50

60

70

80

Millions of short tons per square mile

Figure 7. Chart of resource estimates for 20 selected coal zones of the Colorado Plateau in millions of short tons 

per mi2

. Number in parentheses indicates assessment unit in fi g. 2. The John Henry Member, Blackhawk Formation, 

and the Fruitland Formation contain more than one coal zone, but these zones were not assessed individually. The 

total volume of coal was divided by the area of the assessment unit to give an average concentration of coal in 

millions of short tons per mi2.
6 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah

Summary of Assessment Units

Kaiparowits Plateau Assessment Unit

The Kaiparowits Plateau (fi g. 2) was initially 

assessed because the area contained the largest 

undeveloped coal resource in Utah and few comprehensive coal-resource studies were available. 

Our investigation was in progress when most of 

the plateau was included in the Grand Staircase–Escalante 

National Monument in 1996. A preliminary version of the 

assessment by Hettinger and others (1996) was released to the 

general public and land-use planners, and the fi nal version of 

the assessment is released here by Hettinger and others, (chap. 

T, this CD-ROM). Our study concentrated on the overall coal 

distribution in the John Henry Member of the Straight Cliffs 

Formation. Subsurface data collected during the investigation 

represent about 15 percent of the coal exploration holes drilled 

in the area by private companies, and, with their permission, 

these data are made available to the public.

Henry Mountain Basin Assessment Unit

The Henry Mountains Basin (fi g. 2) became important 

for coal resources following the inclusion of the Kaiparowits area in a National Monument. The Henry Mountains Basin contains signifi cant deposits of Federal coal. 

The assessment unit contains three main coal deposits, 

of which the coal in the Masuk Formation is the most important for possible mining (Tabet, chap. R, this CD-ROM). Limitations to future mining may be the lack of an infrastructure to 

transport the coal or energy out of the basin and its proximity 

to Capitol Reef and Canyonlands National Parks and Glen 

Canyon National Recreation Area.

Southern Wasatch Plateau Assessment Unit

The Southern Wasatch Plateau (fi g. 2) has high-quality 

coal and a very high potential for mining. About 4 million 

acres of land is unexplored for coal and likely contains 

large resources. One longwall mine (SUFCO) produces coal 

and trucks the coal to rail lines and power plants. In the assessment unit, the Federal Government owns 96 percent of the coal 

(6.5 billion short tons), and manages 94 percent of the land 

surface, most of which is administered by the Manti–LaSal 

National Forest. Four main coal beds are present in one thick 

zone in the Blackhawk Formation (Dubiel and others, chap. S, 

this CD-ROM). The main limitation for future mining is lack 

of direct access to rail transport.

Northern Wasatch Plateau Assessment Unit

The Northern Wasatch Plateau unit has been mined since 

the late 1800’s and has large deposits of coal underlying 

the Manti–LaSal National Forest (fi g. 2). Several highproduction longwall mines operate in the area. The main 

purpose of this study was to determine the availability and 

recoverability of coal following such intense mining (Rohrbacher and others, chap. F, this CD-ROM). Of the original 

resource, 8 percent of the total has been mined or is lost to 

mining, and 7 percent of the total is presently economic and 

compliant to the Clean Air Act. The area still has high mining 

potential—about 1.1 billion short tons of coal might ultimately 

be produced, but the best coals may be depleted by 2040.

Deserado Assessment Unit of the 

Lower White River Coal Field

A 22-mi2 area was assessed outside of the present longwall 

mining operation at the Deserado mine (fi g. 2). The coal is 

concentrated in two zones of the Mesaverde Group and has 

good development potential (Brownfi eld and others, chap. N, 

this CD-ROM). Ninety-nine percent of the coal is federally 

owned.

Danforth Hills Assessment Unit

The Danforth Hills (fi g. 2) has a high concentration of 

coal resources in its 162-mi2 area. The Colowyo surface 

mine produces coal from the area, and there is high potential 

for further development. The Federal Government owns 89 

percent of the coal, yet manages only 25 percent of the surface 

land. There are seven assessed coal zones within the Fairfi eld 

Coal zone

Cameo/Wheeler (8)

Coal Ridge (8)

Fruitland (10)

John Henry (1)

Blackhawk (3)

South Canyon (8)

Yampa A (7)

Yampa B (7)

Yampa C (7)

Yampa D (7)

136,200

11,290

204,600

41,830

3,449

22,090

19,28

3,940

1,164

4,836

141,000

14,100

214,600

47,150

4,231

24,750

21,480

5,066

1,893

6,851

145,800

16,900

224,500

52,460

5,013

27,400

23,690

6,192

2,622

8,866

111

42

200

26

8

42

11

6

6

7

3

20

5

11

18

11

10

22

39

29

Lower Mean Upper n* % error

Figure 8. Uncertainty estimates for the identifi ed category of coal 

resources of selected coal zones. Resources are reported in millions 

of short tons with four signifi cant fi gures to show details of 

statistical analysis. The n* is called the “pseudo n” by Schuenemeyer 

and Power (in press) and represents a calculated sample size 

that compensates for differences in data-point densities across an 

assessment area. Number in parentheses indicates study area shown 

in fi g. 2.
Executive Summary 7

coal group of the Williams Fork Formation (Brownfi eld and 

others chap. M, this CD-ROM).

Yampa Assessment Unit

This is the most important coal-producing area in 

Colorado (fi g. 2) with several large surface operations including the Seneca, Trapper, and Foidel 

Creek mines. Future expansion is expected to be underground 

using longwall technology. The Federal Government owns 69 

percent of the coal but manages only 7 percent of the surface. 

The area has coal-bed methane potential. Four coal zones 

were correlated and assessed in the Williams Fork Formation 

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

Southern Piceance Assessment Unit

The southern part of the Piceance Basin 

(fi g. 2) has a coal resource of about 120 

billion short tons within the Mesaverde, 

Mount Garfi eld, and Williams Fork 

Formations; however, only about 34 

billion short tons are in beds of minable 

thickness (greater than 3 ft) and depth (less than 3,000 ft). The 

coal is mined from several large underground mines along the 

basin’s southern boundary, and gas is also produced from coal 

in the basin’s interior. The Federal Government owns about 74 

percent of the coal and manages 64 percent of the surface land; 

much of the resource underlies the Grand Mesa and Gunnison 

National Forests. The distribution and resources of coal are 

assessed by Hettinger and others (chap. O, this CD-ROM).

Somerset Assessment Unit

This area has several large underground mines and a moderately high percentage (64 percent) of federally administered lands (fi g. 2). Within a one-quadrangle map area, 

the available coal resources may be as much as 75 percent 

of the remaining coal (Rohrbacher and others, chap. F, this 

CD-ROM). Potential problems are posed by the steep topography and associated landslide areas, by igneous intrusions (in 

adjacent areas), and by restriction of rail service to one line in 

the narrow valley of the North Fork of the Gunnison River.

San Juan Basin Assessment Unit

The Fruitland Formation contains 230 billion short tons 

of bituminous coal in the San Juan Basin, 160 billion short 

tons of which are federally owned. Most of these resources 

are less than 4,000 ft deep. Of this total, 

about six billion short tons are at strippable 

depths of less than 200 ft. Through 1998, 

three large strip mines had produced more 

than 350 million short tons of coal, most of 

which went to feed two mine-mouth power 

plants in the northwest part of the basin 

in New Mexico. These three mines produced more than 15 

million short tons of coal in 1998. The discovery of commercial coal-bed methane in Fruitland coals in the 1970’s 

spurred rapid development of this resource, and Fruitland coal 

beds today produce about one trillion cubic feet of gas annually, making the San Juan Basin the world’s largest coal-bedmethane-producing basin. Fruitland coals contain in excess 

of 50 trillion cubic feet of gas in place. The Fruitland coal 

data presented in this assessment will provide valuable insights 

for understanding coal-bed methane generation and reservoir 

characteristics that will enhance coal-bed methane exploration 

elsewhere (Fassett, chap. Q, this CD-ROM).

Bisti Assessment Unit

The coal seams in the Bisti area (fi g. 2) have good continuity and, in the San Juan Basin, are the closest undeveloped resource to a major highway and a population center 

(Farmington, N. Mex.). The area is about 50 mi from existing 

power plants, but there is currently no rail infrastructure to 

transport the coal to them effi ciently. Trucking the coal would 

be relatively expensive. Of the original resources in the area, 

1 percent has been mined out, 68 percent is available, and 47 

percent is recoverable (Rohrbacher and others, chap. F, this 

CD-ROM). Presently, none of this coal is considered economic 

or is compliant with the Clean Air Act.

Black Mesa Basin Assessment Unit

Coal of the Wepo Formation is produced from 

the Kayenta and Black Mesa surface mines, 

and the area has future development potential 

(Nations and others, chap. H, this CD-ROM). 

We provide a geologic assessment of the area 

(fi g. 2), but no new resource fi gures. The 

assessment unit is completely within the Hopi and Navajo 

Reservations.

Conclusions

The Colorado Plateau region contains a substantial quantity of high-quality, low-sulfur coal resources. A portion of 

these resources will provide future energy production for the 
8 Geologic Assessment of Coal in the Colorado Plateau: Arizona, Colorado, New Mexico, and Utah

United States in the 21st century. Coal that will be mined 

throughout the next 20 to 25 years is essentially known, most 

of it occurring within active mines or in adjacent leased areas. 

The geologic interpretations and digital data presented in this 

report provide industry geologists, land-use planners, Congress, and the public with comprehensive information on the 

location, distribution, and quality of these resources. The study 

also identifi es coal deposits that have future coal and coal-bedgas development potential. This knowledge and data will be 

crucial if unforeseen energy events, market trends, or environmental concerns require the transfer of emphasis from one 

coal region to another. This is especially relevant to federally 

owned coals, as seen recently in the case of the Kaiparowits 

Plateau and related land and resource trades. The digital data 

and interpretations presented in this study can be updated 

as new data become available to provide geologically based 

assessments within the region and can be used as a base of 

comparison to other important coal-producing regions of the 

Nation.

References Cited

Averitt, P., 1975, Coal resources of the United States, January 1, 1974: 

U.S. Geological Survey Bulletin 1412, 131 p.

Campbell, M.R., 1917 [reprinted 1922, 1929], The coal fi elds of the 

United States: U.S. Geological Survey Professional Paper 100-A, 

33 p.

Campbell, M.R., and Parker, E.W., 1909, Coal fi elds of the United 

States, in Papers on the Conservation of Mineral Resources: U.S. 

Geological Survey Bulletin 394, p. 7–26.

Eakins, Wynn, Tremain-Ambrose, C.M., Scott, D.C., and Teeters, D.D., 

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National Coal

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