DATA SERIES 683

PLATE 3 0F 5

Coal Field Coal bearing Formations Mine Mining History Age Coal Beds or Zones Depositional Environment Discovery Date Coal Geochemistry Infrastructure Location Production Rank Resources Structure Thickness

Green River Thumbnail graphic showing the Green River coal field (see plate 1).

Two operators are recovering 

coal from the Fort Union, Lance 

and Almond Formations (U.S. 

BLM, 2008a). Deeper 

Mesaverde Group coals targeted 

at the proposed Stansbury Mine.

Presently, mining at the Jim 

Bridger and Black Butte 

Mines on the northeastern 

flank of the Rock Springs 

Uplift (U.S. BLM, 2008a). 

Stansbury Mine proposed 

on the northwest portion of 

the Rock Springs uplift (see 

plate 2).

Coal mining in the Rock Springs uplift began as local house and wagon mines along the 

Overland Trail before 1865 (Evans, 1865). On land granted to the railroad in the Greater 

Green River Basin at Rock Springs, Black Butte, and Point of Rocks, commercial 

underground coal mines were opened from 1868 to 1870. The tonnage produced from 

Union Pacific mines nearly tripled, from 1875 to 1895, spurred on by mechanization. 

Because of the introduction of diesel locomotives on railroads, the 1940s through 1950s 

constituted a critical period for the Union Pacific mines in the Rock Springs area 

(Gardner and Flores, 1989). All but three Union Pacific coal mines were closed by the 

end of 1954. With the termination of the more than 100-year-long dependency on coal 

by the railroad, the last Union Pacific mine near Rock Springs closed in 1962. As a 

response to clean-air regulations, the need for cheaper energy, and the oil embargo, in 

the 1970s, energy suppliers built coal-fired power plants. Coal in the Rock Springs area 

once again was on the upswing, particularly in the Jim Bridger and Black Butte Mines as 

surface mining was introduced. Coal mined since 1974 at the Jim Bridger Mine has 

almost exclusively supplied the fuel for the nearby 2,100-megawatt Jim Bridger power 

plant (Flores and Bader, 1999). Paleocene and Late Cretaceous

As many as five coal beds of the Deadman 

coal zone of the Fort Union Formation are 

mined and leased within an area of about 25 

mi

2

 north and east of Point of Rocks and east 

and south of Black Buttes (Flores and Bader, 

1999). The Deadman coal zone (coal beds 

D1−D5) is exceptionally well developed 

along the eastern flank of the Rock Springs 

uplift where the beds have been referred to as 

the Jim Bridger deposit (Glass, 1976). The 

Deadman coal zone is subbituminous in rank 

and as much as 32 ft thick where the coal 

beds merge. Only three coal beds (A−C) of 

the Deadman coal zone may be traced 

southward into the Black Buttes area (Flores 

and Bader, 1999).

The Rock Springs area served as a depocenter, from Cretaceous to early Tertiary 

time, prior to uplift (Keith, 1965; Roehler, 1965; Weimer, 1970; Land, 1972; 

Levey, 1985). The area was part of a greater foreland basin that extended from 

western Wyoming to Nebraska. During Cretaceous time, sedimentary infilling of 

this basin by fluvial, deltaic, and marine deposits was controlled by tectonic 

movement of the Cordilleran thrust belt and the rise and fall (transgression and 

regression) of the epeiric sea. During early Tertiary time, Laramide tectonism was 

characterized by structural partitioning of the Cretaceous foreland basin that 

influenced the sedimentary infilling by fluvial environments (Perry and Flores, 

1994). Cyclic intervals of deposition of conglomeratic sandstone and coal-bearing 

rocks represent base-level rise and fall controlled by subsidence and tectonism 

(Flores and Bader, 1999). On fluvial floodplains and in abandoned fluvial channels, 

organic material that would later become coal, accumulated in peat swamps.

From 1848 to 1850, Howard Stansbury of the Bureau of 

Topographic Engineers, conducted a survey along the 

Overland Trail in southern Wyoming (Gardner and 

Flores, 1989). He labeled the area as a coal basin and 

reported the presence of coal around Evanston and 

eastward. He mentioned outcrops of coal along Bitter 

Creek and near the Point of Rocks, which include 

Cretaceous and Tertiary deposits (Flores and Bader, 

1999). By early 1869, Rock Springs became a significant 

mining area on the Union Pacific Railroad main line; 

coal production was mainly from Cretaceous deposits 

(Flores and Bader, 1999).

The USGS coal quality investigation of the Deadman coal zone indicated 

the following arithmetic mean values (on an as-received basis) : ash—11.18 

percent, total sulfur—0.56 percent, calorific value—9,000 Btu/lb (Stricker 

and Ellis, 1999). The trace elements that can affect coal utilization and are 

of environmental concern in the Deadman coal zone, include 0.97 ppm 

antimony, 21 ppm arsenic, 0.69 ppm beryllium, 0.28 ppm cadmium, 13 ppm 

chromium, 2.8 ppm cobalt, 5.5 ppm lead, 23 ppm manganese, 0.20 ppm 

mercury, 9.7 ppm nickel, 2.8 ppm selenium, and 5.1 ppm uranium (n=26; 

Stricker and others, 1998). Because of the low amounts of sulfur, ash, and 

trace elements, these coal deposits serve well as an energy resource 

throughout the next few decades (Flores and Bader, 1999).

For the Jim Bridger minemouth electric power plant, 

the coal resources are 

expected to continue to 

contribute fuel supplies 

(Flores and Bader, 1999).

Sweetwater County (U.S. 

BLM, 2008a)

One operation is surface, the other is 

underground, surface and highwall 

combined.

Subbituminous coal is present in the Fort 

Union Formation (Flores and Bader, 1999). 

Black Butte Mine coal specifications: 

Subbituminous C, 9,400−10,000 Btu/lb., 0.3-

0.7 percent sulfur; Union Pacific, 2010a, 

http://www.uprr.com/customers/energy/coal/

wyoming/blkbutte.shtml

For the U.S. Geological Survey 1999 resource 

assessment of selected Tertiary coals in the 

Northern Rocky Mountains and Great Plains 

Region, estimated coal resources of the Deadman 

coal zone in the Black Butte and Jim Bridger areas 

were 2.7 billion short tons (Ellis and others, 

1999a). Rock Springs Uplift

Coal deposits in the Deadman coal zone, in the lower 200 ft of the Fort Union Formation are as 

much as 32 ft thick. The USGS assessment of Fort Union Formation coal beds along the eastern 

flank of the Rock Springs uplift focused on beds D1, D2, D3, D4, and D5 of the Deadman coal 

zone (Jim Bridger mine) and the equivalent A, B, and C coal beds (Black Butte mine; Flores and 

Bader, 1999).

Little Snake River (from 

Ball, 1909, and Ball and 

Stebinger, 1910, in 

Hettinger and others, 

2008).

Thumbnail graphic showing coal stratigraphy in the Rawlins-Little Snake River Area and coalbed 

natural gas drilling on the Atlantic Rim (see plate 1).

Mesaverde Group and Fort 

Union Formation (Quillinan and 

others, 2009; Hettinger and 

others, 2008).

Exploration and production 

of coalbed natural gas is 

across the Atlantic Rim. Paleocene and Late Cretaceous

Fort Union Formation: coal zones of the 

China Butte Member and Cherokee coal zone 

of the Overland Member; Mesaverde Group: 

primarily the Allen Ridge and Almond 

Formations (Hettinger and others, 2008)

In the upper member of the Almond Formation, coals developed from peat deposits 

that accumulated in back-beach barrier islands adjacent to mainland beaches or 

sediment-filled lagoons. In the lower member, coal developed from peat that 

accumulated in marshes where splay deposits filled bays and water was shallow 

enough to allow the growth of vegetation (Hettinger and others, 2008). See also, 

Green River coal field.

The Atlantic Rim Natural Gas Project (ARPA) began 

with a 96-coal bed natural gas (CBNG) well proposal 

submitted by Stone & Wolf in 2000 (U.S. BLM, 2005). 

The development of natural gas resources in the ARPA 

involves drilling of approximately 2,000 CBNG wells to 

recover energy resources. Total new surface disturbance 

from the drilling program across the ARPA (Federal, 

State and fee minerals) is limited to a maximum of 7,600 

acres, at any given time, and a 6.5-acre/well site shortterm (less than 6 years) disturbance goal. The estimated 

number of gas wells is not a cap or limitation, but an 

approximation to help establish the surface disturbance 

limit (U.S. BLM, 2007).

As-received analysis of coal samples near the base of the Allen Ridge 

Formation shows 6.94 percent ash, 2.25 percent sulfur, and a heating value 

of 11,218 Btu/lb (Ball and Stebinger, 1910). A coal sample from the upper 

member of the Allen Ridge shows 8.44 percent ash, 0.49 percent sulfur, and 

a heating value of 11,009 Btu/lb (Ball, 1909). The average of six analyses 

of coal in the Almond Formation, show 6.61 percent ash, 0.58 percent 

sulfur, and a heating value of 10,359 Btu/lb (Ball and Stebinger, 1910). For 

coal in the China Butte Member of the Fort Union Formation, reported by 

Dames and Moore (1978a, b, c; 1979a, b, c), ash ranges from 4.8 to 14.63 

percent, sulfur content ranges from 0.15 to 1.31 percent, heating values 

range from 7,319 to 9,786 Btu/lb, and apparent rank varies from 

subbituminous B to subbituminous C. For coal beds in the Cherokee coal 

zone, ash yields range from 9.60 to 35.28 percent, sulfur content ranges 

from 1.03 to 5.74 percent, heating values range from 6,098 to 9,122 Btu/lb, 

and apparent rank varies from lignite to subbituminous C (Sanders, 1974 

and 1975; in Hettinger and others, 2008).

Atlantic Rim (RawlinsLittle Snake River Area, 

South-Central Wyoming)

Atlantic Rim: 54.9 billion cubic ft of 

coalbed natural gas was produced as of 

June, 2010 (WOGCC, 2010). Subbituminous

The proposed Atlantic Rim Natural Gas project is 

expected to produce nearly 1,350 billion cubic feet 

of natural gas, providing enough natural gas to 

heat 19.3 million homes for one year and 

generating approximately $958 million in total 

taxes and royalties (U.S. BLM, 2007).

Major structural components of the 

Rawlins–Little Snake River study area 

(Hettinger and others, 2008).

Hams Fork Thumbnail graphic of the Kemmerer Mine in the Hams Fork coal field (see plate 1).

This deposit is composed of 

multiple coal seams in the 

Adaville Formation that dip 

steeply to the west (U.S. BLM, 

2008a).

Kemmerer Mine near 

Kemmerer (U.S. BLM, 

2008a)

With the formation of the Kemmerer Coal Company in 1897 by Patrick J. Quealy, the 

town of Kemmerer was founded. The coal company and the town were named after 

Quealy's financial backer, Pennsylvania coal magnate Mahlon S. Kemmerer. Although 

the opening of the Kemmerer mines constituted the major impetus for growth in the area, 

some mining in the area dates back to the opening of mines by the Union Pacific Coal 

Co. in 1881 and the construction of the Oregon Short Line Railroad from Granger to 

Oregon. In 1950, the operation converted to surface mining. The Kemmerer "Big Pit" 

mine, one of three at the complex, began in 1971 and is the deepest open pit coal mine in 

the United States (©Union Pacific, 2010b). The mine has an annual output of about 5 

million short tons (©Chevron, 2009). Late Cretaceous

Glass (1977) reported that the Adaville 

Formation may be equivalent in age to the 

Mesaverde Group and Lewis and Lance 

Formations of the Green River region, and is 

the most important coal-bearing rock in the 

Hams Fork Region. Ranging from 2,900-

4,000 ft in thickness, the Adaville Formation 

contains more than 32 coals within a 1,000-ft 

interval, many of which are much thicker than 

other coals of this age in Wyoming (Glass, 

1977). The Adaville No. 1 has a measured 

thickness of greater than 80 ft.

Lawrence (1992) described the distribution and total coal resources within the 

Adaville coal field as being controlled by the geographic extent and number of 

transgressive-regressive pulses. These coals formed during a transgressive 

sequence with a controlled shoreline via growth faults. In regions where thrust and 

sediment loads contributed to rapid subsidence rates, the potential for thick coal 

deposits is greatest. In response to isostatic compensation to thrust and sediment 

loads of the Sevier orogenic belt during a period of general regression along the 

western margin of the Cretaceous seaway, stacked marine sand bodies and thick 

coal deposits accumulated in the Adaville Formation.

The first underground coal mine near Kemmerer, WY, 

opened in 1881. The Kemmerer mine operation moved 

above ground in 1950, is located six mi south of town, 

and is the world's deepest open pit coal mine (©Lasik 

Computer Services, 2010).

Oder (2003) reported that reductions of ash of 28 percent, pyritic sulfur of 

78 percent, arsenic of 31 percent, and mercury of 72 percent on a pounds 

per million Btu basis were achieved using a two stage ParaMagTM dry 

magnetic separator. Laboratory scale (200 lb/hr) dry magnetic separation 

tests of an Adaville series bituminous/subbituminous rank coal from 

southwestern Wyoming resulted in highly effective separations because of 

the synergism between the pulverizer and the dry magnetic separator. The 

clean coal product had a sulfur content of 1.17 LbSO2/MBtu and Btu 

recoveries of 95 percent for this coal. A practical method of achieving 

these levels of performance is to retrofit the separators to treat the internal 

circulation of a pulverizer at the coal-fired power plant (the MagMillTM; 

Oder, 2003). See also 

http://www.uprr.com/customers/energy/coal/wyoming/kemmerer.shtml See Kemmerer Mine, plate 2.

Lincoln County (US_BLM, 

2008a)

Wyoming's deepest open-pit coal mine 

(U.S. BLM, 2008b)

9,500-10,000 Btu/lb. 0.6−1.0 percent sulfur 

(©Union Pacific, 2010b)

Darby Thrust Fault system (Jones and others, 

2009). Southwestern Wyoming Thrust Belt.

This coal zone possibly best typifies the variable thickness of Wyoming coals, the splitting and 

coalescing aspect of coal beds, and the diversity of lithologies associated with the coals (Glass, 

1977). Several of these subbituminous coals are between 10−30 ft thick; the basal Adaville coal 

(Adaville No. 1) is locally 82 ft thick. Individual coal beds within the zone cannot be followed 

for any great distance, due to faulting; however, a zone of Adaville coals can be traced for 

almost 100 mi north to south. 

Hanna Thumbnail graphic of the Hanna coal field (see plate 1).

Ferris, Hanna and Medicine Bow 

Formations

Medicine Bow, Seminoe II, 

Elk Mountain

Coal was originally mined underground, and was used to fuel steam locomotives on the 

Union Pacific Railroad. Coal mining practically ceased in the Hanna basin, after the 

railroads switched from coal-fired to diesel-electric locomotives. Due to increased 

demand for coal to fuel electric power plants (brought about by passage of the Federal 

Clean Air Act), coal mining by both underground and surface methods resumed in the 

1970s. Because this coal must compete with the easily mined and much cheaper coal 

from the Powder River Basin, most coal mining activity in the basin has once again 

nearly ceased (Wyoming State Geological Survey, 2010b). Paleocene and Late Cretaceous Ferris and Hanna

These rocks lie in a deep structural trough divided into two separate basins by a 

large northeast-trending anticline. The Hanna Basin lies to the north; the Carbon 

Basin lies to the south. Like other intermontane basins in the Rocky Mountain 

region, this trough formed during the Laramide Orogeny. The Hanna Basin is 

rather atypical in that most of its sedimentary rocks are tightly folded and faulted, 

and it is extremely deep for its size with 30,000−35,000 ft of sedimentary rock 

overlying its crystalline basement (Glass, 1977). During early Ferris time and early 

Hanna time, major events of downcutting and subsequent infilling of paleovalleys 

occurred. Braided and meandering streams infilled these paleovalleys (Cavaroc and 

others, 1992). Base level rises during which alluvial plains were drained mainly by 

meandering and anastomosed rivers, are reflected by intervening coal-bearing 

intervals consisting of sandstone, siltstone, mudstone, and coal (Perry and Flores, 

1994).

Coal in the Hanna Basin was first discovered by James 

C. Fremont along the North Platte River near the mouth 

of Sage Creek (Dobbin and others, 1929). In Fremont’s 

accounts of the "Expedition to Oregon and North 

California in years 1843-1844", coal deposits elsewhere 

along the Overland Trail were reported. Coal was found 

from the North Platte River eastward to Rock Creek (23 

mi east of Elk Mountain) by James Evans, who surveyed 

the proposed Union Pacific rail line in 1865 (Gardner 

and Flores, 1989). The availability of significant 

amounts of coal along the Overland Trail, as reported by 

Fremont and Evans, helped influence the route of the 

transcontinental railroad.

These coal deposits have low sulfur, ash, and trace-element contents. 

Stricker and others (1998) reported arithmetic means for contents of arsenic 

(4.4 ppm), mercury (0.07 ppm), selenium (0.80 ppm), and uranium (1.9 

ppm) (n=14, arithmetic mean, on a whole-coal, as-received basis) of the 

Ferris and Hanna coals in the Hanna and Carbon Basins (Flores and others, 

1999a). 

There is currently an active 

mine, a load-out facility and 

rail spur northeast of Elmo, 

east of Hanna.

The Hanna and Carbon 

Basins are in Carbon 

County, east of the town of 

Hanna, WY.

Flores and others (1999a) reported that at 

the time of the 1999 USGS coal 

assessment, production from the Ferris 

coals was in open-pit mines, and 

production from the Hanna coals was in 

underground and open-pit mines. Arch 

Coal, Inc., operated surface mines in the 

Ferris and Hanna coal fields. An 

underground mine in the Hanna coal field 

was operated by the Cyprus Coal 

Company. Seven in-state electric power 

plants were supported from these coal 

mines. In 1998, coal production from three 

mines was more than 3.1 million short 

tons (Resource Data International, Inc., 

1998); as reported in Flores and others, 

1999a.

In the Hanna and Carbon Basins, 

subbituminous and bituminous coal exist in 

the Paleocene Ferris and Hanna Formations 

(Dobbin and others, 1929; Berryhill and 

others, 1950; Glass and Roberts, 1979); as 

reported in Flores and others, 1999a. Glass 

and Roberts (1979) reported that the 

apparent rank of the Ferris and Hanna coals 

varies from subbituminous A to high volatile 

C bituminous, ranging from 11,170 Btu/lb 

for the Ferris coal on the western part of the 

Hanna Basin to 11,590 Btu/lb for the Hanna 

coal in the east-central part of the Hanna 

Basin and 12,270 Btu/lb for the Hanna coal 

in the Carbon Basin to the east.

Assessment of Ferris and Hanna coal in the Hanna 

and Carbon Basins (Ellis and others, 1999b) 

concentrated on the compliant coals of the Ferris 

23, 25, 31, 50, and 65, Hanna 77−79, 81, and the 

Johnson-107 coal beds. Estimates of coal 

resources in beds thicker than 2.5 ft are : Ferris 

coals—1.75 billion short tons; Hanna coals—4.26 

billion short tons; and Johnson−107 coals—2.7 

billion short tons; the total for the two 

basins—8.71 billion short tons—is a significant 

regional energy resource (Flores and others, 

1999a).

The Hanna and Carbon Basins are structural 

and sedimentary basins, bounded on the south 

by the Medicine Bow uplift, on the north by 

the Sweetwater arch (consisting of the 

Granite, Shirley, and Seminoe Mountains) 

and on the west by the Rawlins uplift (Flores 

and others, 1999a).

In the Hanna and Carbon Basins, 77 coals were identified by Dobbin and others (1929) and 

Glass and Roberts (1980); of these 47 coals are in the Ferris Formation, and 30 beds are in the 

Hanna Formation (Flores and others, 1999a). Coal deposits in the Ferris Formation may split 

and merge within distances as short as 0.1 mi. In the Hanna Formation, coal deposits split and 

merge over a few mi. Most of the numerous Ferris coals measure less than 6 ft thick, although at 

least one of the Ferris coals reaches 24 ft thick. Locally, most of the Hanna Formation coals 

exceed 3 ft in thickness. Glass (1977) stated, "More importantly, the Hanna No. 1, No. 2, and 

No. 5 coals reach thicknesses of up to 30 ft, 36 ft, and 29 ft thick, respectively."

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U.S. DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY

Coal Fields in Southwestern Wyoming

Compiled by

Laura R.H. Biewick

2012

Publishing support provided by: 

Denver Publishing Service Center

Manuscript approved for publication on 03/30/2012

For more information concerning this publication, contact:

Center Director, USGS Central Energy Resources Science 

Center

Box 25046, Mail Stop 939

Denver, CO 80225

(303) 236-1647

Or visit the Central Energy Resources Team site at:

http://energy.cr.usgs.gov/

Hettinger and others (2008) report that, except for the Pine Ridge Sandstone 

that contains only discontinuous coals, each of the formations in the 

Mesaverde Group contains at least one coal bed that is more than 1 ft thick. 

The Haystack Mountains Formation contains one or two coal beds, 1–3 ft 

thick. In most of the lower nonmarine member, the Allen Ridge Formation 

contains lenticular coals, generally 1–2 ft thick. They also showed that 

southeast of the study area, the basal part of the formation contains as many 

as three coal beds that are 2–4 ft thick. Coals in the upper member are 

generally 1–7 ft thick and more numerous, but generally grade laterally and 

vertically to carbonaceous shale over short distances. Coal is present 

throughout the Almond Formation where coal deposits are 1–16 ft thick, with 

4–8 beds at least 5 ft thick. The Fox Hills Sandstone contains a few thin 

discontinuous coals, including the 8-ft-thick coal at the abandoned Nebraska 

Mine. The Lance Formation is divided into a lower member and the upper 

Red Rim Member. Several thin and discontinuous coals about 1–10 ft thick 

are near the base of the lower member. In the Cherokee coal zone of the 

Overland Member of the Fort Union Formation, maximum coal thicknesses 

range from 5 to 41 ft. Maximum coal bed thicknesses of coal zones in the 

China Butte Member range from 2.5 to 33 ft. Coals 1–30 ft thick are in the 

main body of the Wasatch Formation near Wamsutter and Creston Junction.