U.S. Department of the Interior

U.S. Geological Survey

Professional Paper 1809

Coal Geology and Assessment of Coal Resources and 

Reserves in the Powder River Basin, Wyoming and Montana
Cover: Photograph showing surface coal mining in the Powder River Basin.
Coal Geology and Assessment of Coal 

Resources and Reserves in the Powder 

River Basin, Wyoming and Montana

By James A. Luppens, David C. Scott, Jon E. Haacke, Lee M. Osmonson, 

and Paul E. Pierce

Professional Paper 1809

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2015

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Suggested citation:

Luppens, J.A., Scott, D.C., Haacke, J.E, Osmonson, L.M., and Pierce, P.E., 2015, Coal geology and assessment of 

coal resources and reserves in the Powder River Basin, Wyoming and Montana: U.S. Geological Survey Professional 

Paper 1809, 218 p., http://dx.doi.org/10.3133/pp1809.

Library of Congress Cataloging-in-Publication Data

Luppens, James A. (James Alan), 1946-

 Coal geology and assessment of coal resources and reserves in the Powder River 

Basin, Wyoming and Montana / by James A. Luppens, David C. Scott, Jon E. 

Haacke, Lee M. Osmonson, and Paul E. Pierce.

 pages cm. -- (Professional paper ; 1809)

 Includes bibliographical references and index.

 ISBN 978-1-4113-3875-3 (pbk. : alk. paper)

 1. Coal reserves--Powder River Basin (Wyo. and Mont.) 2. Coal--Geology--Powder 

River Basin (Wyo. and Mont.) I. Title.

 TN805.W8L87 2015

 553.2’4097871--dc23

 2015013801

ISSN 2330-7102 (online)

ISSN 1044-9612 (print)
iii

Contents

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

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

Approach and Objectives.............................................................................................................................2

Geologic Setting.............................................................................................................................................3

Coal Fields..............................................................................................................................................4

Influence of Geologic Conditions on Coal Mining ..........................................................................4

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

Previous and Current Coal Mining .............................................................................................................6

Coal Lease Areas..................................................................................................................................7

Previous Coal Resource Estimates....................................................................................................8

Previous Coal Bed Nomenclature......................................................................................................8

Methodology...................................................................................................................................................9

Phase One (Data Collection and Editing)..........................................................................................9

Data Collection.............................................................................................................................9

Phase Two (Modeling) .......................................................................................................................10

Coal Bed Correlations ...............................................................................................................10

Coalbed Modeling......................................................................................................................11

Restrictions to Mine Models....................................................................................................12

Factors Affecting Extraction of Coal Resources ..................................................................13

Airports...............................................................................................................................14

Alluvial Valley Floors .......................................................................................................14

Archaeological Areas .....................................................................................................14

Coalbed Methane .............................................................................................................14

Dwellings and Buildings ..................................................................................................15

Federal Land Systems......................................................................................................15

Historic Lands and Sites..................................................................................................15

Oil and Gas Development ................................................................................................15

Pipelines.............................................................................................................................16

Power Lines .......................................................................................................................16

Railroads.............................................................................................................................16

Rivers, Lakes, and Streams.............................................................................................16

Roads..................................................................................................................................16

State Lands and Trusts.....................................................................................................17

Towns..................................................................................................................................17

Phase Three (Assessment of Resources and Reserves).............................................................17

Coal Bed Assessment ..............................................................................................................17

Wasatch Formation Coal Beds .......................................................................................18

Upper Healy and Healy/Lower Ulm Coal Beds ...................................................18

Murray Coal Bed......................................................................................................18

Ucross Coal Bed ......................................................................................................18

Upper Felix, Felix, and Lower Felix Coal Beds ....................................................19

Fort Union Formation Coal Beds.....................................................................................19

Roland (Upper Rider), Roland (Lower Rider), Roland (Baker), 

and Roland (Taff) Coal Beds .....................................................................19

Upper Smith and Smith Coal Beds........................................................................20
iv

Anderson Upper Rider, Anderson Lower Rider, Anderson, 

and Lower Anderson Coal Beds ..............................................................20

Dietz 1, Dietz 2, Dietz 3, and Dietz 4 Coal Beds ...................................................21

Upper Canyon/Cox, Canyon, and Lower Canyon Coal Beds.............................22

Upper Ferry and Ferry Coal Beds..........................................................................22

Werner/Cook Coal Bed ...........................................................................................22

Upper Otter and Otter Coal Beds ..........................................................................22

Gates/Wall Coal Bed ...............................................................................................23

Pawnee Coal Bed ....................................................................................................23

Brewster-Arnold Coal Bed .....................................................................................23

Odell Coal Bed..........................................................................................................23

Cache Coal Bed........................................................................................................23

A Zone Coal Bed ......................................................................................................23

Upper Rosebud and Rosebud/Knobloch Coal Beds...........................................24

Calvert Coal Bed ......................................................................................................24

McKay/Nance and Lower McKay Coal Beds .....................................................24

Flowers-Goodale Coal Bed ....................................................................................24

Upper Witham and Robinson/Witham Coal Beds ..............................................25

Roberts/Terret Coal Bed .........................................................................................25

Burley Coal Bed .......................................................................................................25

Upper Stag and Lower Stag Coal Beds................................................................25

Coal Bed Cross Sections ..........................................................................................................25

In-Place Coal Resource Volumetrics......................................................................................26

Perspectives on Environments of Deposition .......................................................................27

Surface Coal Resource Assessment........................................................................................................29

Surface Mine Modeling.....................................................................................................................29

Geologic Aspects of Surface Mine Model Development ...................................................29

Modeling Stratigraphic Sequence for Surface Mining.......................................................30

Regional Surface Mine Modeling ...........................................................................................32

Surface Mine Model Design Assumptions...................................................................32

Surface Mine Plant Facilities..........................................................................................33

Surface Mine Reclamation .............................................................................................34

Surface Mine Supplies and Utilities ..............................................................................34

Surface Mine Reserve and Recoverable Resource Evaluation Results ..........................34

Determination of Reserves..............................................................................................34

Gillette Coal Field Assessment Area ....................................................................34

Northern Wyoming PRB Assessment Area.........................................................35

Montana PRB Assessment Area...........................................................................35

Combined PRB Reserve and Recoverable Resource Summary ......................36

Underground Coal Resource Assessment ..............................................................................................37

Underground Mine Model Design ...................................................................................................37

Underground Mine Layout Design..........................................................................................37

Surface Mine Plant...........................................................................................................38

Underground Mine Plant .................................................................................................38

Underground Mine Development Excavation..............................................................38

Longwall Panel and Pillar Recovery ...............................................................................38

Underground Coal Resources Results ............................................................................................39

Conclusions...................................................................................................................................................39

Acknowledgments.......................................................................................................................................40

References Cited..........................................................................................................................................40

Glossary.........................................................................................................................................................47
v

Figures

1. Map showing location of the Powder River Basin, Wyoming and Montana........................53

2. Map showing location of individual assessment areas in the Powder River 

Basin, Wyoming and Montana.......................................................................................................54

3. Map showing structure contours drawn on the top of the Tullock Member 

of the Fort Union Formation.............................................................................................................55

4. Map showing generalized surface geology of the Powder River Basin, 

Wyoming and Montana....................................................................................................................56

5. Generalized stratigraphic column for the Powder River Basin, Wyoming 

and Montana......................................................................................................................................57

6. Map showing location of coal fields in the Powder River Basin, Wyoming 

and Montana......................................................................................................................................58

7. Map showing location of significant clinker in the Powder River Basin, 

Wyoming and Montana....................................................................................................................59

8. West-east cross section A–A’ showing subsurface distribution of significant 

coal beds through the southern part of the Powder River Basin, Wyoming ........................60

9. West-east cross section B–B’ showing subsurface distribution of significant 

coal beds through the central part of the Powder River Basin, Wyoming............................62

10. North-south cross section C–C’ showing subsurface distribution of significant 

coal beds through the Powder River Basin, Wyoming and Montana....................................61

11. Map showing approximate location of faults within the Powder River Basin, 

Wyoming and Montana....................................................................................................................63

12. Map showing locations of mines, lease areas, and average coal quality basis 

within the Powder River Basin, Wyoming and Montana..........................................................64

13. Coal bed and coal zone names used in this assessment and previous publications 

in the Powder River Basin, Wyoming and Montana..................................................................65

14. Flow chart showing generalized U.S. Geological Survey methodology used for coal

resource and reserve assessment................................................................................................66

15. Map showing mines and nonproprietary drill holes and paleochannels within 

the Anderson coal bed in the Powder River Basin, Wyoming and Montana .......................67

16. Cross section A–A’ showing correlations used in the U.S. Geological Survey 

Miscellaneous Investigations Series Map I–1959–D by Molnia and Pierce (1992).............68

17. Cross section B–B’ showing comparison of coal bed correlations made 

in the Gillette coal field report to the U.S. Geological Survey Miscellaneous 

Investigations Series Map I–1959–D by Molnia and Pierce (1992).........................................69

18. Isopach map showing combined thickness of the Smith, Anderson, and Canyon 

coal beds and areas of thin or absent coal (“want area” after Flores and others, 

2010) within the Powder River Basin, Wyoming and Montana................................................70

19. Map showing land-use restrictions in the Powder River, Wyoming and Montana.............71

20. Map showing coal mineral estate ownership in the Powder River Basin, Wyoming 

and Montana......................................................................................................................................72

21. Illustration showing the effect of coal-bed depth upon restricted resource 

because of mine-pit highwall setback requirements ................................................................73

22. Map showing location of areas of low, moderate, and high coalbed methane 

potential in the Powder River Basin, Wyoming and Montana.................................................74

23. Coal bed stratigraphy, original and available resources, and maximum and average

thicknesses for coal beds in the Powder River Basin, Wyoming and Montana..................75
vi

24. Isopach map of the Upper Healy coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .............................................................................................76

25. Map showing depth to the top of the Upper Healy coal bed within the Powder 

River Basin...................................................................................................................................77

26. Isopach map of the Healy/Lower Ulm coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .........................................................................78

27. Map showing depth to the top of the Healy/Lower Ulm coal bed within the 

Powder River Basin....................................................................................................................79

28. Isopach map of the Murray coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .......................................................................................80

29. Map showing depth to the top of the Murray coal bed within the Powder 

River Basin...................................................................................................................................81

30. Isopach map of the Ucross coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .......................................................................................82

31. Map showing depth to the top of the Ucross coal bed within the Powder 

River Basin...................................................................................................................................83

32. Isopach map of the Upper Felix coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .........................................................................84

33. Map showing depth to the top of the Upper Felix coal bed within the Powder 

River Basin...................................................................................................................................85

34. Isopach map of the Felix coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .......................................................................................86

35. Map showing depth to the top of the Felix coal bed within the Powder 

River Basin...................................................................................................................................87

36. Isopach map of the Lower Felix coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .........................................................................88

37. Map showing depth to the top of the Lower Felix coal bed within the Powder 

River Basin...................................................................................................................................89

38. Isopach map of the Roland (Upper Rider) coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin...........................................................90

39. Map showing depth to the top of the Roland (Upper Rider) coal bed within 

the Powder River Basin .............................................................................................................91

40. Isopach map of the Roland (Lower Rider) coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin...........................................................92

41. Map showing depth to the top of the Roland (Lower Rider) coal bed within 

the Powder River Basin .............................................................................................................93

42. Isopach map of the Roland (Baker) coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .........................................................................94

43. Map showing depth to the top of the Roland (Baker) coal bed within the 

Powder River Basin....................................................................................................................95

44. Isopach map of the Roland (Taff) coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .........................................................................96

45. Map showing depth to the top of the Roland (Taff) coal bed within the Powder 

River Basin...................................................................................................................................97

46. Isopach map of the Upper Smith coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .........................................................................98

47. Map showing depth to the top of the Upper Smith coal bed within the Powder 

River Basin...................................................................................................................................99
vii

48. Isopach map of the Smith coal bed showing extent of coal at least 1.0 foot thick 

within the Powder River Basin ...............................................................................................100

49. Map showing depth to the top of the Smith coal bed within the Powder 

River Basin.................................................................................................................................101

50. Isopach map of the Anderson Upper Rider coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin.........................................................102

51. Map showing depth to the top of the Anderson Upper Rider coal bed within 

the Powder River Basin ...........................................................................................................103

52. Isopach map of the Anderson Lower Rider coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin.........................................................104

53. Map showing depth to the top of the Anderson Lower Rider coal bed within 

the Powder River Basin ...........................................................................................................105

54. Isopach map of the Anderson coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................106

55. Map showing depth to the top of the Anderson coal bed within the Powder 

River Basin.................................................................................................................................107

56. Isopach map of the Lower Anderson coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin.........................................................108

57. Map showing depth to the top of the Lower Anderson coal bed within the 

Powder River Basin..................................................................................................................109

58. Isopach map of the Dietz 1 coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................110

59. Map showing depth to the top of the Dietz 1 coal bed within the Powder 

River Basin.................................................................................................................................111

60. Isopach map of the Dietz 2 coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................112

61. Map showing depth to the top of the Dietz 2 coal bed within the Powder 

River Basin.................................................................................................................................113

62. Isopach map of the Dietz 3 coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................114

63. Map showing depth to the top of the Dietz 3 coal bed within the Powder 

River Basin.................................................................................................................................115

64. Isopach map of the Dietz 4 coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................116

65. Map showing depth to the top of the Dietz 4 coal bed within the Powder 

River Basin.................................................................................................................................117

66. Isopach map of the Upper Canyon (Cox) coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin.........................................................118

67. Map showing depth to the top of the Upper Canyon (Cox) coal bed within 

the Powder River Basin ...........................................................................................................119

68. Isopach map of the Canyon coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................120

69. Map showing depth to the top of the Canyon coal bed within the Powder 

River Basin.................................................................................................................................121

70. Isopach map of the Lower Canyon coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................122

71. Map showing depth to the top of the Lower Canyon coal bed within the 

Powder River Basin..................................................................................................................123
viii

72. Isopach map of the Upper Ferry coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................124

73. Map showing depth to the top of the Upper Ferry coal bed within the Powder 

River Basin.................................................................................................................................125

74. Isopach map of the Ferry coal bed showing extent of coal at least 1.0 foot thick 

within the Powder River Basin ...............................................................................................126

75. Map showing depth to the top of the Ferry coal bed within the Powder 

River Basin.................................................................................................................................127

76. Isopach map of the Werner/Cook coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................128

77. Map showing depth to the top of the Werner/Cook coal bed within the Powder 

River Basin.................................................................................................................................129

78. Isopach map of the Upper Otter coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................130

79. Map showing depth to the top of the Upper Otter coal bed within the Powder 

River Basin.................................................................................................................................131

80. Isopach map of the Otter coal bed showing extent of coal at least 1.0 foot thick 

within the Powder River Basin ...............................................................................................132

81. Map showing depth to the top of the Otter coal bed within the Powder 

River Basin.................................................................................................................................133

82. Isopach map of the Gates/Wall coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................134

83. Map showing depth to the top of the Gates/Wall coal bed within the Powder 

River Basin.................................................................................................................................135

84. Isopach map of the Pawnee coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................136

85. Map showing depth to the top of the Pawnee coal bed within the Powder 

River Basin.................................................................................................................................137

86. Isopach map of the Brewster-Arnold coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................138

87. Map showing depth to the top of the Brewster-Arnold coal bed within the 

Powder River Basin..................................................................................................................139

88. Isopach map of the Odell coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................140

89. Map showing depth to the top of the Odell coal bed within the Powder 

River Basin.................................................................................................................................141

90. Isopach map of the Cache coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................142

91. Map showing depth to the top of the Cache coal bed within the Powder 

River Basin.................................................................................................................................143

92. Isopach map of the A Zone coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................144

93. Map showing depth to the top of the A Zone coal bed within the Powder 

River Basin.................................................................................................................................145

94. Isopach map of the Upper Rosebud coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................146

95. Map showing depth to the top of the Upper Rosebud coal bed within the 

Powder River Basin..................................................................................................................147
ix

96. Isopach map of the Rosebud/Knobloch coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin.........................................................148

97. Map showing depth to the top of the Rosebud/Knobloch coal bed within 

the Powder River Basin ...........................................................................................................149

98. Isopach map of the Calvert coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................150

99. Map showing depth to the top of the Calvert coal bed within the Powder 

River Basin.................................................................................................................................151

100. Isopach map of the McKay/Nance coal bed showing extent of coal at 

least 1.0 foot thick within the Powder River Basin..............................................................152

101. Map showing depth to the top of the McKay/Nance coal bed within the 

Powder River Basin..................................................................................................................153

102. Isopach map of the Lower McKay coal bed showing extent of coal at 

least 1.0 foot thick within the Powder River Basin..............................................................154

103. Map showing depth to the top of the Lower McKay coal bed within the 

Powder River Basin..................................................................................................................155

104. Isopach map of the Flowers-Goodale coal bed showing extent of coal at 

least 1.0 foot thick within the Powder River Basin..............................................................156

105. Map showing depth to the top of the Flowers-Goodale coal bed within the 

Powder River Basin..................................................................................................................157

106. Isopach map of the Upper Witham coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................158

107. Map showing depth to the top of the Upper Witham coal bed within the 

Powder River Basin..................................................................................................................159

108. Isopach map of the Robinson/Witham coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin.........................................................160

109. Map showing depth to the top of the Robinson/Witham coal bed within 

the Powder River Basin ...........................................................................................................161

110. Isopach map of the Roberts/Terret coal bed showing extent of coal 

at least 1.0 foot thick within the Powder River Basin.........................................................162

111. Map showing depth to the top of the Roberts/Terret coal bed within the 

Powder River Basin..................................................................................................................163

112. Isopach map of the Burley coal bed showing extent of coal at least 1.0 foot 

thick within the Powder River Basin .....................................................................................164

113. Map showing depth to the top of the Burley coal bed within the Powder 

River Basin.................................................................................................................................165

114. Isopach map of the Upper Stag coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................166

115. Map showing depth to the top of the Upper Stag coal bed within the Powder 

River Basin.................................................................................................................................167

116. Isopach map of the Lower Stag coal bed showing extent of coal at least 

1.0 foot thick within the Powder River Basin .......................................................................168

117. Map showing depth to the top of the Lower Stag coal bed within the Powder 

River Basin.................................................................................................................................169

118. Pie diagram showing tonnages and percentages of individual coal beds in 

relation to the total 1.16 trillion short tons of original resources in the Powder 

River Basin, Wyoming and Montana.....................................................................................170
x

119. Isopach map of the Flowers-Goodale coal bed showing extent of resources 

at least 1.0 foot thick and location of lineaments described by Jones, 2010a, 

in the Powder River Basin, Wyoming and Montana...........................................................171

120. Isopach map of the Roberts/Terret coal bed showing extent of resources 

at least 1.0 foot thick and location of lineaments described by Jones, 2010a, 

in the Powder River Basin, Wyoming and Montana...........................................................172

121. Isopach map of the Smith, Anderson, and Canyon coal beds showing extent 

of resources at least 5 feet thick and location of lineaments described by 

Jones, 2010a in the Powder River Basin, Wyoming and Montana...................................173

122. Isopach map showing interburden thickness between the Anderson and 

Canyon coal beds in the Gillette coal field and location of lineaments 

described by Jones, 2010a in the Powder River Basin, Wyoming ...................................174

123. Generic cost curve showing 12.8 billion short tons (BST) reserve estimate 

at $13.20 per ton for the Powder River Basin, Wyoming and Montana...........................175

124. Map showing areal extent for the composite stripping ratio of the Roland 

(Baker), Smith, Upper Anderson, Anderson, Dietz, and Canyon coal beds 

in the Gillette coal field, Wyoming Powder River Basin.....................................................176

125. Cost curve showing reserve estimates at $10.47 per short ton (as of 

January 2007) and $14.00 per short ton (as of March 2008) for the Gillette 

coal field, Wyoming..................................................................................................................177

126. Map showing areal extent for the composite stripping ratio of the Roland 

(Baker), Smith, Anderson, Dietz 3, Canyon, Lower Canyon, and Werner/Cook 

coal beds where the stripping ratios are from 1:1 to 10:1, thicknesses are equal 

to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, 

in the Wyoming Powder River Basin.....................................................................................178

127. Cost curve showing 1.5 billion ton reserve estimate at $9.30 per short ton (as of 

February 2010) for the Northern Wyoming Powder River Basin assessment area.......179

128. Map showing areal extent for the composite stripping ratio of the Roland (Baker),

Smith, Anderson, Dietz 2, and Dietz 3 coal beds where the stripping ratios are 

from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is 

less than or equal to 500 feet thick, in the Montana Powder River Basin ......................180

129. Map showing areal extent for the stripping ratio of the Canyon coal bed where 

the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, 

and the overburden is less than or equal to 500 feet thick, in the Montana Powder

River Basin.................................................................................................................................181

130. Map showing areal extent for the stripping ratio of the Werner/Cook coal bed 

where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 

5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana

Powder River Basin..................................................................................................................182

131. Map showing areal extent for the stripping ratio of the Pawnee coal bed where 

the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, 

and the overburden is less than or equal to 500 feet thick, in the Montana Powder

River Basin.................................................................................................................................183

132. Map showing areal extent for the stripping ratio of the Rosebud/Knobloch coal 

bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at 

least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the 

Montana Powder River Basin.................................................................................................184
xi

133. Map showing areal extent for the stripping ratio of the Flowers-Goodale coal 

bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at 

least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the 

Montana Powder River Basin.................................................................................................185

134. Graph showing cost curve for the Montana Powder River Basin assessment 

area showing estimated recoverable coal resources compared to sales price 

per ton of coal ...........................................................................................................................186

135. Bar graph showing resource and reserve summary in the Powder River Basin, 

Wyoming and Montana ...........................................................................................................187

136. Graph showing cumulative cost curve for the Powder River Basin, Wyoming 

and Montana (Gillette coal field, Northern Wyoming Powder River Basin, and 

Montana Powder River Basin assessment areas)..............................................................188

Tables

1. 2012 and cumulative coal production from the Powder River Basin, Wyoming 

and Montana .............................................................................................................................191

2. Typical proximate analysis on an as-received basis of coal from mines in the 

Powder River Basin, Wyoming and Montana......................................................................192

3. Typical proximate analysis on an as-received basis of coal beds reporting 

sodium as percent of ash, percent sulfur, percent ash, and calorific value, 

in coal beds in the Wyoming Powder River Basin compared to the Montana 

Powder River Basin..................................................................................................................193

4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, 

reported in millions of short tons by reliability category for the Powder River Basin, 

Wyoming and Montana....................................................................................................................194

5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet 

thick, reported in millions of short tons by overburden depth for the Powder 

River Basin, Wyoming and Montana.....................................................................................198

6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet 

thick, reported in millions of short tons, by coal ownership categories for the 

Powder River Basin, Wyoming and Montana......................................................................204

7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet 

thick, reported in millions of short tons by assessment area............................................208

8. Summary of coal resources by reliability, depth, ownership, and assessment 

area categories in the Powder River Basin, Wyoming and Montana .............................214

9. Summary of resources by reliability categories for all 47 coal beds assessed 

in the Powder River Basin and comparison of reliability of previous assessment 

of the Wyodak-Anderson zone in the Gillette coal field to the current Powder 

River Basin assessment ..........................................................................................................215

10. Example of a regional mine model stratigraphic sequence used in the economic 

evaluation of the Northern Wyoming Powder River Basin assessment area, 

River Wyoming ..........................................................................................................................215

11. Estimated impacts of compositing the originally excluded shale, pyrite, and 

other high-ash parting material with the coal analyses for the USGS-1 core 

hole from the Lake DeSmet coal area, Wyoming................................................................216

12. Coal resources and reserves for beds greater than or equal to 5.0 feet thick 

in each assessment area in the Powder River Basin, Wyoming and Montana..............216

13. Underground resources for coal beds 10–20 feet thick and greater than 500 feet 

deep in the Powder River Basin, Wyoming and Montana.................................................217
xii

Conversion Factors

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

square mile (mi2

) 2.590 square kilometer (km2)

square feet (ft2

) 0.0929 square meters (m2)

Mass

pounds (lbs) 0.4536 kilograms (kg)

short tons (2,000 lbs) 0.90718474 metric tons (2,204.6 lbs)

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the Universal Transverse Mercator (UTM) 

map projection, using the following parameters: map units = meters; zone = 13; datum = NAD83; 

and spheroid = Clarke, 1866.

Abbreviations and Acronyms Used in This Report 

BST billion short tons

Btu/lb British thermal unit per pound

CARS coal availability and resource studies

CBM coalbed methane

DRB demonstrated reserve base

EIA U.S. Energy Information Administration

ERR estimated recoverable reserve base

Esri Environmental Systems Research International

ft feet

ft2 square feet

hr hour

GIS geographic information system

in inch

MBMG Montana Bureau of Mines and Geology

mi mile

mi2 square mile

MST million short tons

MST/yr million short tons per year

MTPRB Montana Powder River Basin assessment area

NCRA National Coal Resource Assessment

NCRDS USGS National Coal Resources Database System

NWPRB Northern Wyoming Powder River Basin assessment area

PRB Powder River Basin (both Wyoming and Montana)
xiii

PRLAs preference right lease applications

RAP resource allocation planning

SMCRA Surface Mining Control and Reclamation Act

SO2/lb sulfur dioxide per pound

SWPRB Southwestern Powder River Basin assessment area

USBLM U.S. Bureau of Land Management

USFS U.S. Forest Service

USGS U.S. Geological Survey

UTM Universal Transverse Mercator

WSGS Wyoming State Geological Survey

WOGCC Wyoming Oil and Gas Conservation Commission

yd3 cubic yards

yr year

Coal Geology and Assessment of Coal Resources 

and Reserves in the Powder River Basin, Wyoming 

and Montana 

By James A. Luppens, David C. Scott,Jon E. Haacke, Lee M. Osmonson, and Paul E. Pierce

Abstract

This report presents the final results of the first assessment of both coal resources and reserves for all significant 

coal beds in the entire Powder River Basin, northeastern 

Wyoming and southeastern Montana. The basin covers about 

19,500 square miles, exclusive of the part of the basin within 

the Crow and Northern Cheyenne Indian Reservations in 

Montana. The Powder River Basin, which contains the largest 

resources of low-sulfur, low-ash, subbituminous coal in the 

United States, is the single most important coal basin in the 

United States. In 2012, almost 420 million short tons were 

produced from this basin, which was about 42 percent of the 

total coal production in the United States.

Prior resource assessments relied on net coal thickness 

maps for only selected beds. Although net thickness maps 

are sufficient for estimating in-place (remaining) resources, 

the mapping of all individual beds is necessary for conducting economic studies to determine the coal reserve base 

for the Powder River Basin. The coal reserve base includes 

those resources that are currently (October 2014) economic 

(reserves), but also may encompass those parts of a resource 

that have a reasonable potential for becoming economically 

available. Thus, the coal reserve base provides a more realistic 

estimate of the portion of in-place resources that are potentially recoverable, which is important from a national energy 

standpoint. A key to the success of this current assessment was 

incorporating as much data as practical from the recent, extensive coalbed methane development in the basin. The interpretation of these new data proved critical to the development of 

a comprehensive geologic model needed for estimating coal 

resources and reserves in the Powder River Basin. A total of 

29,928 drill holes were used for this assessment, of which 

21,393 are in the public domain.

The U.S. Geological Survey used a geology-based assessment methodology to estimate an original coal resource of about 

1.16 trillion short tons for 47 coal beds in the Powder River 

Basin; in-place (remaining) resources are about 1.15 trillion 

short tons. The most significant resources are within the Tertiary 

(Paleocene) Tongue River Member of the Fort Union Formation 

and include the Roland (Baker, 1929), Smith, Anderson, 

Dietz 3, Canyon, Lower Canyon, Werner/Cook, Otter, Gates/

Wall, Rosebud/Knobloch, Flowers-Goodale, and Roberts/Terret 

coal beds. These resources represent about 944 billion short tons 

(81.5 percent) of the total 1.16 trillion short tons of original coal 

resource estimated for the Powder River Basin.

Not all 47 coal beds were included in the mining economics evaluation. Only those beds that exceeded 5.0 ft in thickness and had a significant areal extent with a stripping ratio of 

10:1 or less were included. A total of 162 billion short tons of 

recoverable coal resources (coal reserve base) are estimated 

at a 10:1 stripping ratio or less. An estimated 25 billion short 

tons of that coal reserve base met the definition of reserves, 

which are resources that can be economically produced at or 

below the current sales price at the time of the evaluation. This 

reserve estimate does not mean that the total amount of coal 

left in the Powder River Basin could be produced by surface 

mining technologies. The costs of mining and coal sales prices 

are not static as both tend to increase over time if supported by 

demand. If future market prices exceed mining costs, portions 

of the coal reserve base would be elevated to reserve status 

(and the converse).

There are no active underground mining operations in 

the Powder River Basin, nor are any anticipated in the foreseeable future. However, there are significant deeper coal resources 

in the basin that could be produced with current underground 

mining technologies. Therefore, a preliminary estimate of coal 

with thicknesses amenable for longwall mining was conducted. 

The total underground coal resource in coal beds 10–20 feet 

thick is estimated at 304 billion short tons.

Introduction

The U.S. Geological Survey (USGS) is responsible for 

providing objective scientific information to support decisions 

regarding land management, environmental quality, energy, and 

strategic policy. Therefore, the USGS periodically assesses the 

Nation’s endowment of various energy resources, including 

coal. The objective of the United States Coal Resources and 
2 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Reserves Assessment Project is to conduct regional-scale coal 

resource1

 and coal reserve assessments of coal beds in major 

coal basins. Coal resource and reserve estimates are essential 

for planning local, State, and Federal energy and land-use policy decisions now and for the foreseeable future. These estimates are also necessary to determine possible socioeconomic 

effects on a region as coal resources and reserves are developed and approach depletion (Luppens and others, 2008).

From 1999 to 2009, the USGS completed the first digital 

National Coal Resource Assessment (NCRA) of in-place

(remaining) coal resources (Pierce and Dennen, 2009); 

however, these estimates did not provide all the information 

needed for resource planning. Calculations of the portion of 

in-place coal resources that are economically recoverable 

(coal reserves) are equally important (Luppens and others, 

2009). Since the NCRA study, USGS methodology to calculate resources and reserves has been refined to take advantage 

of improvements in computer hardware, geologic and mine 

model software, and availability of data. As a result, the scope 

of coal resource and especially reserve assessment capabilities has grown in geographic size from a single topographic 

quadrangle to entire coal fields and geologic basins.

The first U.S. coal basin evaluated in the coal assessment project is the Powder River Basin (PRB) Wyoming and 

Montana (fig. 1). In this report, the abbreviation PRB refers 

to the entire Powder River Basin (Wyoming and Montana); 

Wyoming PRB refers only to the Wyoming portion of the 

basin, and Montana PRB refers only to the Montana portion 

of the basin. The PRB contains some of the most significant 

deposits of low-sulfur, low-ash, subbituminous coal in the 

world (Molnia and Pierce, 1992). In 2012, coal production 

from 16 mines in the basin totaled almost 420 million short 

tons (MST) (42 percent of the total coal production in the 

United States), making it the single most important coalproducing basin in the Nation (table 1). About 388 MST 

(93 percent of the total PRB coal production) came from the 

Gillette coal field, located in the eastern part of the Wyoming 

PRB (fig. 2, table 1).

There is often confusion regarding the use of the terms

coal resources and coal reserves as they relate to assessments. 

Although the two terms have been used interchangeably, 

there are significant differences between the definitions. Coal 

resources include those in-place tonnage estimates determined by summing the volumes for identified resources and

hypothetical resources, using coal zones of a minimum thickness and within certain depth limits (commonly 0–2,000 feet 

[ft] deep) (Pierce and Dennen, 2009). Coal reserves are a subset of coal resources and are considered economically minable 

at the time of classification (Wood and others, 1983).

Results presented in this report include not only an 

assessment of coal resources and reserves, but also the most 

current and comprehensive correlation of individual coal beds 

throughout the PRB. Other coal stratigraphers have attempted 

1

Technical terms used in this report requiring additional explanation are 

italicized when used for the first time and their definitions are given in the 

Glossary section at the end of the report.

to correlate the entire PRB (Flores and others, 2010); however, 

that assessment did not include all of the Montana PRB assessment area, nor did it include deeper coal beds in the PRB. This 

assessment is based on data from the entire PRB and correlates 

coal beds based on their stratigraphic position. 

 The Powder River Basin is a structural and sedimentary 

basin that is generally defined by Tertiary-age (Paleocene) 

rocks that crop out along the margins of the basin. The basin 

covers about 19,500 square miles (mi2

) exclusive of the part 

of the basin within the Crow and Northern Cheyenne Indian 

Reservations in the Montana PRB (fig. 1). The basin extends 

north-south from Miles City, Montana to Douglas, Wyoming; 

the west-east extent in the Wyoming PRB is from about 

Sheridan to Moorcroft and from about Decker to Broadus, 

in the Montana PRB (fig. 1).

The PRB was divided into five geographic areas to 

keep databases and modeled areas to a manageable size and 

permit timely publication of assessment results (fig. 2). Four 

of those areas are in the Wyoming PRB and one is in the 

Montana PRB: (1) Luppens and others (2008) reported on the 

first assessment area, summarizing geology, coal resources, 

and reserves for the Gillette coal field; (2) Scott and others 

(2010) summarized the second assessment area and presented results on geology, coal resources, and reserves for 

the Northern Wyoming Powder River Basin assessment area 

(NWPRB assessment area); (3) Osmonson and others (2011) 

summarized the third assessment area and presented results 

on geology and coal resources in the Southwestern Powder 

River Basin assessment area (SWPRB assessment area); and 

(4) Haacke and others (2013) summarized the fourth assessment area and presented results on geology, coal resources, 

and reserves for the Montana Powder River Basin assessment 

area (MTPRB assessment area). The fifth area (East Gillette 

coal field extension) extends east from the Gillette coal field 

and was evaluated for this report specifically to provide a more 

comprehensive mapping of coal beds below the WyodakAnderson coal zone and to complete the assessment of the 

entire PRB (fig. 2). This publication supersedes the four OpenFile Reports and presents estimates of coal resources and 

reserves for the entire PRB. Supplemental to this report are 

the geographic information system (GIS) data created using 

Environmental Systems Research International (Esri) ArcGIS 

(Environmental Systems Research International, 2006) that 

can be used to show the PRB boundary in map view along 

with other pertinent data layers (Kinney and others, 2015).

Approach and Objectives

To provide a meaningful estimate of the amount of coal 

that is potentially recoverable, the USGS and the former 

U.S. Bureau of Mines conducted initial coal availability and 

recoverability Studies (CARS) in the late 1980s (Luppens and 

others, 2009). These studies included both mine planning and 

economic studies that were used to derive estimates of the coal 

reserves for limited areas. The CARS methodology evolved 
Geologic Setting 3

from single 7.5-minute quadrangle maps containing an area of 

about 56 square miles (mi2

) (145.0 square kilometers [km2]) 

to entire coal fields containing greater than 2,000 mi2

 (greater 

than 5,180 km2

). These advances became feasible largely 

because of advances in computer hardware and software and 

the availability of digital information regarding geology, geography, and societal data and infrastructure.

One of the objectives of the USGS CARS project has 

been to provide data to update the U.S. Energy Information 

Administration (EIA) demonstrated coal reserve base

(DRB), the only publicly available, nationwide summary of 

the quantities of minable coal conforming to a unified set of 

criteria (EIA, 1997). The EIA has obtained valuable accessibility and recoverability data for recent coal reserve estimates 

from the USGS coal availability studies and from the former 

U.S. Bureau of Mines coal recoverability studies. The EIA use 

of revised CARS data in New Mexico, Illinois, and Eastern 

Kentucky document the increasing cooperation among EIA, 

the U.S. Geological Survey, and State geological agencies in 

order to share data and coordinate efforts in their coal resource 

and reserve programs (EIA, 1997).

Regardless of the size or generation of the particular 

CARS area, the methodology to estimate coal resources and 

reserves has remained standardized and consistent throughout 

the assessment process. For CARS assessments, coal beds must 

be correlated and modeled individually. Another key component is the systematic inventory of restrictions to mining to 

yield the volume of coal that could be potentially recovered.

Previous USGS resource assessments in the PRB have 

relied on the correlation of coal bed zones and overburden

depths based on depth to the uppermost coal bed in a zone 

(for example, Ellis and others, 1999, and Flores and others, 

2010). Flores and others (1999) defined a coal zone (WyodakAnderson) in the Gillette coal field that is within an interval 

almost 900 ft thick that consists of 11 coal beds totaling more 

than 200 ft thick. However, by reporting only the overburden 

to the top of the uppermost coal bed in a coal zone, as much as 

700 ft of interburden was unaccounted for assuming a 900-ftthick coal zone and a net coal bed thickness of 200 ft. Furthermore, there is a significant difference in terms of the cost of 

mining a single 200-ft-thick coal bed compared to mining seven 

coal beds (ranging in thickness from 3 to 50 ft) totaling 200 ft 

over a 900-ft-thick stratigraphic zone. Although a methodology 

based on coal zone correlations is suitable for calculating net inplace resources, it does not provide the comprehensive bed by 

bed geometry required for a mining and economic assessment 

of reserve potential. Therefore, another objective of the PRB 

coal assessment project was developing a correlated drill-hole 

database used to generate a multibed model that included all 

individual coal beds in the Powder River Basin.

Historically, the CARS project relied on interpretation of 

both existing oil and gas well and coal drilling data; however, 

because of the recent development of coalbed methane (CBM) 

in the PRB, an abundance of new data are now available. The 

interpretation of these new data proved critical to the development of a comprehensive geologic model needed for calculating coal resources and reserves in the PRB.

The principal objectives of this assessment are as follows:

1. Update the stratigraphic database, correlate individual 

coal beds, and unify coal bed names throughout the PRB.

2. Develop a comprehensive, multi-coal bed geological 

model for the PRB with the geological assurance to 

support regional resource and reserve estimates.

3. Complete an economic mining evaluation that incorporates the environmental and technological restrictions to 

mining for the PRB.

4. Summarize coal resources and reserves for all four coal 

resource and reserve assessment areas in the PRB, including the East Gillette extension.

5. Supply the EIA with updated coal availability and recoverability results.

Geologic Setting

The geologic history of the PRB has been extensively 

discussed by Flores and others (2010) and Jones (2010a); therefore, an in-depth discussion of geology and depositional history 

of coal beds in the PRB was not a primary objective of this 

assessment. However, the public available downhole data generated during this assessment does provide a foundation for future 

geologic studies (Haacke and Scott, 2013).

The PRB is an elongated, north-northwest-trending sedimentary and structural basin that forms a broad asymmetric syncline (depression) with a gently dipping east limb and a steeply 

dipping west limb. A structure contour map (sea level datum) 

drawn on top of the Tullock Member reveals the asymmetrical 

nature of the PRB, with the axis near the west margin of the 

basin (Ayers, 1986a) (fig. 3). Along the west margin of the 

PRB, rocks dip between 20° and 25° to the east, whereas rocks 

dip only about 2° to 5° to the west along the east margin of the 

basin (Flores and others, 1999). The synclinal axis of the basin 

is closer to the basin’s west margin, trending north-northwest in 

the Wyoming PRB, and gradually turning north-northeast in the 

Montana PRB (Lopez, 2005) (fig. 4). In the Montana PRB, the 

basin is bounded by structural uplifts—the Bighorn Mountains 

to the west, and the Black Hills to the east—and becomes shallow to the north against the southern flank of the Miles City 

arch, located northeast of the PRB.

Geologic strata exposed at the surface in the PRB consist 

almost entirely of lower Tertiary (Paleocene) Fort Union and 

(Eocene) Wasatch Formations with the (Oligocene) White River 

Formation (Oligocene) present in stream drainages (figs. 4 and 

5). The Lebo Shale Member and Tullock Members of the Fort 

Union Formation underlie the Tongue River Member of the Fort 

Union and are present along the margins of the basin (fig. 4).

The Wasatch Formation conformably overlies the Fort 

Union Formation in the center of the basin and unconformably 

overlies it along the basin margins. The Wasatch Formation 

covers about three fourths of the Wyoming PRB (fig. 4) and 
4 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

extends north into the southernmost part of the Montana PRB 

where it crops out along topographic highs that occur between 

river valleys, including the Tongue River, Hanging Woman 

Creek, and Otter Creek drainages (Vuke and others, 2001a). 

The underlying Fort Union Formation is exposed along the 

basin margins in the Wyoming PRB and throughout most of 

the Montana PRB (fig. 4). 

The Fort Union Formation covers about one-fourth of 

the surface area in the PRB, mostly in the Montana PRB, and 

underlies the Wasatch Formation in the Wyoming PRB (fig. 4).

The Fort Union Formation is composed of three members; 

from oldest to youngest they are the Tullock, Lebo, and 

Tongue River (fig. 5). Together, these members form a thick 

sequence of interbedded sands, gravels, silts, shales, and coals. 

These strata incorporate some of the thickest and most extensive deposits of low-sulfur, low-ash, subbituminous coal in the 

world (Molnia and Pierce, 1992). Most of the coal is contained in the Wyodak-Anderson coal zone in the Tongue River 

Member (Ellis and others, 1999). The Fort Union Formation 

ranges in thickness from a few hundred feet along the north 

margin of the Montana PRB, to approximately 4,000 ft at the 

Montana-Wyoming border (Jay Gunderson, Montana Bureau 

of Mines and Geology, written commun., 2011).

Underlying the Fort Union Formation in the Montana 

PRB, delta-plain sands and shales of the Upper Cretaceous 

Hell Creek Formation (equivalent to the Lance Formation 

in Wyoming) grade upward into fluvial-dominated sediments of the lowermost Tullock Member of the Fort Union 

Formation (fig. 5). The top of the Hell Creek Formation is 

generally placed at the base of the lowest coal bed found in 

the Tullock Member and generally corresponds to an upward 

change in sedimentary character from cross-bedded to 

planar-bedded sandstones (Vuke and others, 2001b). The GIS 

layer of geology for the PRB is available using Esri ArcGIS 

9.3.1 (Environmental Systems Research International, 2006) 

(Kinney and others, 2015).

Coal Fields

The Powder River Basin has been segregated into named 

coal fields based on geographic features or nearby towns. Previous investigations in the PRB often referred to areas of coal 

production and coal resources by coal field name; therefore, a 

map of all the coal fields in the PRB is included in this report 

(fig. 6). The Ashland, Birney-Broadus, Coalwood, Forsyth, 

Miles City, Mizpah, Moorhead, northward extension of the 

Sheridan, and Rosebud coal fields are all within the Montana 

PRB (Averitt, 1966; McLellan and others, 1990) (fig. 6). The 

Barber, Buffalo, Dry Cheyenne, Gillette, Glenrock, Little 

Powder River, Lost Spring, Powder River, Pumpkin Buttes, 

Sheridan, Spotted Horse, and Sussex coal fields are all within 

the Wyoming PRB (Glass, 1976) (fig. 6). The area east of the 

Gillette coal field is referred to as the East Gillette Extension 

coal field for this report (fig. 6).

Influence of Geologic Conditions on Coal Mining 

Almost everywhere in the PRB, coal beds greater than 

5 ft thick show evidence of burning. The heat from the burning coal on the overlying rock produces a reddish colored 

material known as clinker. The thickness of clinker is roughly 

2–3 times the thickness of the original coal that has burned; 

therefore, clinker thickness can be used in exploration as a 

relative indicator of the approximate thickness of a coal bed. 

A coal bed 5–10 ft thick can produce a clinker zone 10–30 ft 

thick, whereas a coal bed 50 ft thick may produce a clinker 

zone 100–200 ft thick (Matson and Blumer, 1973).

Large areas of original near-surface coal resources of 

the Tongue River Member of the Fort Union Formation have 

been destroyed by burning at the outcrop and beneath shallow cover (fig. 7). Approximately 1,000 mi2

 of the surface 

area in the Montana PRB is affected by clinker (Coates and 

Heffern, 1999; Roberts and others, 1999a, b, c) (fig. 7). 

Roberts and others (1999c) outlined large areas of clinker 

in the Spring Creek and Decker Mine areas (fig. 2) affecting 

the Anderson, Dietz 2, and Dietz 3 coal beds. At the Rosebud 

Mine, near Colstrip, Montana (fig. 2), where the Rosebud 

and McKay beds have merged to a single bed, clinker 

deposits have been reported to attain a thickness of as much 

as 120 ft (Tudor, 1975). In the Wyoming PRB, large areas of 

original near-surface coal resources have been burned at their 

outcrop and beneath shallow cover along the east margin of 

the basin; approximately 750 mi2

 in the Wyoming PRB is 

affected by clinker. 

The structural dip of coal beds can affect the mining 

method. A dip of 5° or less is optimal for both surface and 

underground mining. A dip of 20° or greater negatively 

affects both types of mining. Rocks along the west margin 

of the PRB dip steeply to the east (20o

 or more) towards the 

axis of the basin, whereas rocks along the east margin of 

the basin dip about 2–5o

 to the west, towards the axis of the 

basin. Surface coal mining has been more prevalent along the 

east margin of the Wyoming PRB because of the shallower 

dip, whereas underground mining was more prevalent along 

the west margin of the basin, in the area north of Sheridan, 

Wyoming. Figures 8 and 9 illustrate the relatively gentle dip 

of coal beds along the east margin of the PRB in contrast to 

the steeper dip of the same beds along the west margin of the 

basin. The stratigraphic sequence of significant coal beds in 

the subsurface geology of the PRB is shown in three cross 

sections (figs. 8–10).

In the northwest portion of the Wyoming PRB and 

southwest portion of the Montana PRB, numerous northeasttrending faults are present (fig. 11). The faults, most of which 

are downthrown on the east, postdate coal bed formation. 

Faults shown on figure 11 are based on Ellis and others (1999) 

and Roberts and others (1999a, b, c), or they were identified during the correlation phase of this assessment from 

observations of stratigraphic offset between drill holes. The 

faults range 0.5–6.0 mi long, with displacements of as much 

as 140 ft (Robinson and Van Gosen, 1986). In most cases, 
Geologic Setting 5

fault displacement is not much more than 100 ft. Areas where 

numerous high-angle faults are present are not conducive 

to either surface or underground mining operations. One 

such example in the PRB is near the abandoned Big Horn 

Mine (fig. 12), north of Sheridan, Wyoming, where previous 

underground mining in a highly faulted area has produced 

significant subsidence. 

Faults in coal beds also have an important effect on the 

selection of mining methods and on productivity. Major faults 

with vertical displacements greater than 65 ft commonly are 

used to delineate mine plan boundaries. Numerous minor 

faults are generally associated with and trend almost parallel 

to major faults. The adverse effects of faulting are greater 

on underground mining operations. A fault with a vertical 

displacement of 3–16 ft may not pose much of a problem in 

a surface mine, whereas it could be a serious impediment in 

underground mining (Thomas, 2002). For this report faults 

were not considered a restriction to mining. 

The method of underground mining can affect the amount 

of resources lost because of faulting. If the method is longwall 

mining, a larger resource loss will occur, because longwall 

operations need hazard-free runs in a designated panel of coal. 

Longwall panels are typically 5,000–10,000 ft in length and 

750–1,500 ft in width; thus, a large, relatively unfaulted block 

of coal is required. If coal panels between faults are too small, 

then whole blocks may be lost to mining (Thomas, 2002).

Coal Quality

Coal quality is a major factor in its marketability and also 

an important input parameter for coal reserve estimations. Coal 

is sold based on its calorific value expressed in British thermal 

units per pound of coal (Btu/lb). Quality parameters, such as 

increased ash content that lowers the calorific value, negatively 

affect the operating and maintenance costs at coal-fired power 

plants. Therefore, coals with lower ash and sulfur content and 

higher calorific values command a premium selling price.

A single set of typical coal quality values based on available data was estimated for each assessment area. The typical 

coal quality values were then used to determine the current 

freight on board (FOB) sales prices. Various trade publications 

publish periodic coal sales prices based on coal quality, primarily by gross calorific value measured in Btu/lb and sulfur dioxide per pound (SO2

/lb). Typically, the higher the gross calorific 

content and the lower the sulfur dioxide values, the higher the 

sales price. For example, for the week ending October, 5, 2012, 

the average price for Powder River Basin coal with 8,800 Btu/lb 

and 0.8 SO2

/lb was $10.20/ton, whereas at 8,400 Btu/lb and 

0.8 SO2/lb, the price was only $8.60/ton (Platts, 2012.) After the 

sales price for an assessed area was established, the volume of 

reserves could be determined. All recoverable coal resources

that could be produced at or below the current sales price at the 

time of the evaluation (discounted cash flow (DCF) cost per ton 

basis), by definition, are reserves.

The amendments of the Clean Air Act of 1990 

(42 U.S.C. 765d) enforced emission limits at coal-fired 

power plants to reduce certain air pollutants, such as sulfur 

dioxide. Sulfur dioxide emission limits for all new coal-fired 

power plants built after 1976 were capped at 1.2 lbs sulfur 

dioxide per million Btu (U.S. Environmental Protection 

Agency, 1980). Any coal that could be burned and meet the 

sulfur dioxide emission standards for air quality (emit 0.6 lbs 

or less sulfur per million Btu or 1.2 lbs sulfur dioxide per 

million Btu) without the need for flue-gas desulfurization 

was designated “compliance coal,” also known as low-sulfur 

coal (EIA, 2011). Subsequent phases of the Clean Air Act 

amendments have further restricted sulfur dioxide emissions. 

Currently, New Source Performance Standards establish uniform national Environmental Protection Agency air-emission 

standards that limit the amount of pollution allowed from new 

sources or from modified existing sources. Under New Source 

Performance Standards, Best Available Control Technology 

emission limitations are based on the maximum degree of 

reduction of each pollutant (U.S. Environmental Protection 

Agency, 2005). The current minimum Best Available Control 

Technology standard for sulfur dioxide emissions is 90 percent reduction regardless of the sulfur content.

 Former compliance coals still have a competitive 

advantage because the cost to meet the 90 percent emission 

reductions is typically lower than higher sulfur coals. The 

abundance of low-sulfur and low-ash coal in the PRB has 

been a significant factor in the steadily growing demand for 

coal from this region.

Coal quality information has been available since the 

early 1970s for most of the mines in the PRB. Figure 12 

shows the average coal quality for five areas in the PRB 

where significant mining is current or has been proposed 

(averages calculated from mine averages in table 2). Table 2 

summarizes coal quality for all mines in the PRB, as well as 

the Otter Creek lease area in the Montana PRB (fig. 12). In 

comparison to coal in the Wyoming PRB, coal in the Montana 

PRB is generally greater in sodium content (table 3). The 

Smith, Anderson, and Dietz 3 coal beds in the Decker and 

Spring Creek Mine areas generally have higher sodium content than the Rosebud/Knobloch coal bed in the Rosebud and 

Absaloka Mine areas in the Montana PRB (table 3, fig. 12). 

Increased sodium content in coal can cause excessive slagging and fouling in power plants and requires boilers specifically designed to successfully burn coal with higher sodium 

contents (Thomas, 2002).

In-place coal quality varies significantly within the 

Gillette coal field. The north, middle, and south areas (fig. 12) 

were defined on the basis of variations in coal quality which 

permitted estimates of sales price using averaged coal quality 

data for each area. From figure 12, the in-place coal quality trends by bed may be observed. The Btu is highest in the 

south area and lowest in the north area. Sulfur and ash generally increase from the south area to the north area.
6 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

In general, the apparent rank of coals in the PRB range 

from subbituminous C to subbituminous A. The lower rank 

subbituminous C coal is located primarily in the shallower 

part of the basin along the east margin of the PRB (Stricker 

and others, 2007). Subbituminous B ranked coal is found in 

the Sheridan and North Extension Sheridan coal fields (fig. 6) 

on the west side of the basin as well as at intermediate depths 

(Luppens, 2011). Subbituminous A ranked coal is generally 

found in the deeper parts of the basin (greater than 1,600 ft 

depth) (Luppens, 2011). Because the PRB contains subbituminous coal, all resource and reserve volumes were calculated 

using an average density factor of 1,770 tons per acre foot of 

coal (Wood and others, 1983).

Previous and Current Coal Mining 

In 2012, about 42 percent (420 million short tons) of 

the total coal production in the United States came from the 

PRB, distinguishing it as the most prolific coal basin in the 

United States (EIA, 2013). Coal production from the PRB 

from 1969 to 2012 has been almost 10 billion short tons (BST) 

(table 1). There are five areas within the PRB where current 

(December 2012) or previous coal mining has been significant (fig. 12): (1) Colstrip, Montana (includes the Rosebud, 

Absaloka, and abandoned Big Sky Mine); (2) Decker, Montana 

(includes the Decker and Spring Creek Mines); (3) Sheridan 

coal field, Wyoming (includes the abandoned Big Horn Mine); 

(4) Gillette coal field, Wyoming (includes the Antelope, Belle 

Ayr, Black Thunder, Buckskin, Caballo, Coal Creek, Cordero 

Rojo, Dry Fork, Eagle Butte, Jacobs Ranch, North Antelope/

Rochelle, Rawhide, and Wyodak Mines); and (5) Glenrock coal 

field, Wyoming (includes the abandoned Dave Johnston Mine 

and the Stevens lease areas). 

On July 28, 1806, Captain William Clark of the Corps 

of Discovery observed coal beds as he floated down the 

Yellowstone River along the north margin of the Montana PRB 

(Moulton, 2001). Less than a year later, Manuel Lisa built a 

trading post at the confluence of the Bighorn and Yellowstone 

Rivers and used lignite coal from nearby outcrops to heat 

buildings during the winter months (Morgan, 1966). Despite 

the early discovery and use of coal in the Montana PRB, it was 

more than 100 years later that coal was commercially mined. 

In 1923, the first modern-day strip mine (Rosebud Mine) in 

the western United States was opened near Colstrip, Montana 

(fig. 2). The coal was mined by Northern Pacific Railroad 

Company and used to fuel steam locomotives. In the mid-1940s, 

coal production from the Rosebud Mine reached production of 

just more than 4 MST per year. However, by 1957 the mine was 

closed after a decade-long decrease in coal demand as steam 

locomotives were gradually replaced by diesel locomotives 

(Morgan, 1966). Total coal production from 1923 to1968 for the 

Montana PRB was less than 45 MST (Department of Labor and 

Industry, Safety and Health Bureau, State of Montana, written 

commun., 2011).

Montana Power Company acquired the Rosebud Mine 

in 1968 and formed a subsidiary, Western Energy Company, 

to manage and develop the Colstrip properties (U.S. Office 

of Surface Mining, 1983). Western Energy Company began 

mining coal at the Rosebud Mine near Colstrip Montana in 

1968. One year later, Peabody Coal began operations at the Big 

Sky Mine just south of Colstrip, but closed operations in 2003 

(figs. 2 and 12). The Absaloka Mine, located 10–12 mi west 

of the Rosebud Mine, began production in 1974 and is owned 

and operated by Westmoreland Resources, Inc. (figs. 2 and 

12). Total production from the Colstrip area is about 708 MST 

(table 1). 

The Decker East, West, and North Mines near Decker, 

Montana (figs. 2 and 12), began operating in 1972 after 

development of a 19-mi-long railroad spur from Sheridan, 

Wyoming. Total production from the Decker/Spring Creek area 

is about 642 MST (table 1). The Spring Creek Mine, also near 

Decker, Montana, opened in 1979 and is operated by Spring 

Creek Coal, LLC (figs. 2 and 12).

Coal in the Wyoming PRB was first documented in 

1859-60 by Ferdinand V. Hayden, a member of Captain 

W.F. Raynolds’ expedition exploring the Lower Yellowstone 

River. Hayden reported extensive lignite coal between the North 

Platte River and Pumpkin Butte area northwest of Gillette, 

Wyoming (Bryans, 1987). Traveling through the Powder River 

Basin in 1865, James A. Sawyer observed sizeable coal deposits 

south of Gillette, Wyoming (Gardner and Flores, 1989).

In the Wyoming PRB, coal mining began about 1883 

near the towns of Glenrock and Douglas, Wyoming (fig. 1); 

however, it was the development of railroad lines in 1886 and 

1887 that greatly affected significant growth in coal mining 

activity (Gardner, and Flores, 1989). The first underground coal 

mines in 1888 were the Mine near Douglas, Wyoming, and the 

Deer Creek Mine near Glenrock, Wyoming (fig. 1), each with 

production of about 13,000 short tons of coal (Gardner and 

Flores, 1989).

In the Sheridan coal field area (fig. 12), the Buffalo Fuel 

Company No. 1 underground mine was developed in 1888 

(Gardner and Flores, 1989). The nearby Dietz Mine opened 

about 1890 and by 1925, 17 additional underground mines 

opened in close proximity to the Dietz Mine (Gardner and 

Flores, 1989). In 1905, mine production in Sheridan County 

was about 550,000 short tons of coal annually (Trumbull, 

1905). The first surface mine (Peerless) near Gillette, 

Wyoming opened in 1924, where a 90-ft-thick coal bed was 

mined (Gardner and Flores, 1989). The Wyodak Coal and 

Manufacturing Company opened a large surface mine and 

produced about 33,600 short tons of coal in 1925. By the 

mid-1900s, advancements in mining equipment and mining 

techniques made surface mining much more profitable. Most 

underground mines closed or the companies switched from 

underground to surface mining methods.

Until 1978, most of the coal production in the Sheridan 

coal field area was from underground mines. Of the Sheridan 

County cumulative coal tonnage of about 62 MST through 

1978, underground mining accounted for about 48 MST 
Previous and Current Coal Mining 7

(78 percent). This production came from about 70 underground 

mines, most of which are about 10 mi north of Sheridan, 

Wyoming (fig. 12). Surface subsidence pits and troughs mark 

locations of many of the abandoned underground mine workings (Glass, 1978). The Dietz 3 and Canyon coal beds in the 

Sheridan coal field area were surface mined at the Big Horn 

Mine from 1962 to 2000 (Ellis and others, 1999); more than 

47 MST of coal were produced from the mine (fig. 12). Total 

recorded production from the entire Sheridan coal field area 

is estimated at about 100 MST of coal (Nick Jones, Wyoming 

State Geological Survey, written commun., 2009) (table 1).

The need for coal increased dramatically in the mid1960s because of the increased demand for electricity from 

coal-fired power plants. For example, the Dave Johnston 

Mine in the Glenrock coal field opened in 1958 to supply 

coal to the adjoining power plant (fig. 12). Production from 

the Dave Johnston Mine from 1958 to 2000 totaled about 

104 MST (Nick Jones, written commun., 2010). The Dave 

Johnston Mine marked the beginning of large surface mines in 

the Gillette coal field in the Wyoming PRB. In response to the 

need for low-sulfur, low-ash coal, production from the Gillette 

coal field increased: 623,000 short tons in 1972 (Keystone 

Coal Industry Manual, 1973); 81 MST in 1982 (Keystone Coal 

Industry Manual, 1983); 151 MST in 1992 (Keystone Coal 

Industry Manual, 1993); 360 MST in 2002 (Keystone Coal 

Industry Manual, 2003); and 388 MST in 2012 (Mine Safety 

and Health Administration, 2012). 

Although coal production in the Gillette coal field 

came from 15 surface mines, only 11 are currently active 

(December 2012): Antelope, Belle Ayr, Black Thunder, 

Buckskin, Caballo, Cordero Rojo (Cordero Mine), Dry Fork, 

Eagle Butte, North Antelope/Rochelle, Rawhide, and Wyodak 

(fig. 12). Coal production is from the Anderson and Canyon 

coal beds (fig. 13), which when combined in some areas, 

attains more than 100 ft in thickness. Production in 2012 

from the Gillette coal field totaled more than 388 MST 

(table 1) with almost 52 percent of that total from two mines, 

the North Antelope Rochelle and the Black Thunder (EIA, 

2013). Production from these two mines alone represents 

about 20 percent of the total U.S. coal production in 2012 

(EIA, 2013). Total production (through 2012) from the Gillette 

coal field is about 8 BST (table 1).

Coal Lease Areas

In 1983, a report was submitted to the Bureau of Land 

Management (BLM) for the lease acquisition of Preference 

Right Lease Applications (PRLA) known as the Stevens North 

(W-12767, W-14390, W-14392) and the Stevens South (PRLA 

W-14355) (Western Fuels Association, Inc., 1983). The lease 

applications are north of the Dave Johnston Mine, in the Dry 

Cheyenne and Glenrock coal fields in the Wyoming PRB 

(figs. 2 and 12). These four PRLAs form one unit and are 

collectively known as the Stevens Project Area. Although no 

mining has taken place, in-place coal resources were estimated 

to be 625.3 MST (Western Fuels Association, Inc., 1983).

A report detailing the final Environmental Assessment of 

a lease area known as the Belco–BLM Coal Lease Exchange 

indicated that the Belco lease area located southeast of Buffalo, 

Wyoming (figs. 2 and 12) contained between 137 and 185 MST 

of minable coal at a stripping ratio of 5:1 or less. The minable 

coal beds in the Belco area are the Healy and the Ucross, in the 

Wasatch Formation (Bureau of Land Management, 1999).

In 2003, Pittsburg and Midway Coal Mining Company 

proposed a land exchange with the Federal government for 

lands within the Sheridan coal field in the Wyoming PRB. 

This land, which encompasses about 2,500 acres in sections 

20, 21, 22, 23, 27, 28, 29, 33, and 34, T. 58 N., R. 84 W., is 

referred to as the PSO lease area (figs. 2 and 12) and is located 

in the NE 1⁄4 sec. 22, T. 58 N., R. 84 W. (Bureau of Land 

Management, 2003).

Pittsburg and Midway Coal Mining Company estimated 

that the PSO lease area contains about 112.5 MST of minable 

Federal coal, of which 107 MST was classified as recoverable. 

The projected mining rate was estimated at one MST for 

the first year with subsequent production increasing to 

10 MST per year by year five. Within the PSO lease area, the 

Dietz 1 and Dietz 3 coal beds would be surface mined using 

a strip ratio of about 2.5:1. The Dietz 1 coal bed is present in 

the northern one-half of the lease area and is 5–20 ft thick. 

The Dietz 3 coal bed is present throughout the lease area and 

averages 41 ft thick. Overburden above the Dietz 1 coal bed is 

as much as 275 ft thick, whereas overburden above the Dietz 

3 where the Dietz 1 is not present, is 20–120 ft thick. The 

interburden thickness between the Dietz 1 and Dietz 3 beds 

is 20–140 ft, with a thickening trend from east to west. Two 

northeast-trending faults approximate the northwest and southeast boundaries of the lease area. Although these faults are 

known to be present, their exact locations and displacements 

have not been accurately defined by drilling. The displacements across each of these two major faults are estimated to be 

60–180 ft. Generally, the stratigraphic dip is to the northeast 

at approximately four degrees. There are local areas where the 

shallow strata dip at higher angles, generally because of local 

folding or faulting (Bureau of Land Management, 2003).

Pittsburg and Midway Coal Mining Company entered into 

a joint venture agreement with CONSOL Energy Inc. to develop 

the PSO lease area (Lynn Manning, CONSOL Energy, oral 

commun., 2009). CONSOL of Wyoming LLC, and Chevron 

NPRB, LLC, formed a new company, Youngs Creek Mining 

Company, LLC, to develop and operate the proposed mine 

(Lynn Manning, CONSOL Energy, oral commun., 2009). The 

PSO lease area contains coal reserves totaling approximately 

315 MST with an estimated heat content of 9,350 Btu/lb

and an average sulfur content of 0.47 percent. In July 2012, the 

PSO lease area was sold to Cloud Peak Energy (Bob Green, 

Cloud Peak Energy, oral commun., September 2012).

In 2010, Arch Coal Inc. acquired the right to mine 

572 MST of Montana State-owned coal in Otter Creek, 

south of Ashland, Montana (figs. 1 and 12); Arch Coal Inc. 

already controlled 731 MST of privately owned coal in the 

Otter Creek area (Dennison, 2010). The life-of-mine area 

includes areas known as Tracts I, II, and III. The proposed 
8 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

mine area (Tract II) is owned by Otter Creek Coal, LLC and 

encompasses approximately 7,640 acres, of which about 

4,100 acres would be disturbed under the proposed mine 

plan; tracts I and III total about 10,580 acres. The proposed 

project, Tract II, would have production of about 20 MST/yr 

for a 20-year period (Montana Department of Environmental 

Quality, 2013). Mining has not commenced at the Otter Creek 

lease area as of October 2014.

Previous Coal Resource Estimates

Estimates on coal resources and reserves in the Powder 

River Basin have been published since 1927 (Dobbins and 

others, 1927). These estimates were based on different coal 

beds, coal zones, reliability categories, and geographic 

boundaries. Differences in minimum coal thickness, maximum 

overburden depth, and minimum areal extent of coal beds have 

been used for calculations of coal tonnages. Nevertheless, 

these studies form the foundation for most of the coal resource 

compilations that followed. Detailed lists of references can be 

found in U.S. Geological Survey reports on the four assessment areas (Luppens and others, 2008; Scott and others, 2010; 

Osmonson and others, 2011; and Haacke and others, 2013). 

The following list contains some of the more significant estimates for coal resources and reserves in different portions of 

the PRB as well as the entire PRB.

The earliest published estimate of coal resources in 

the PRB was by Dobbin and others (1927) for the Gillette 

coal field (fig. 6). Their estimate, based on an area of about 

3,000 mi2, was about 14.4 BST; however, they were limited 

to outcrop measurements for their calculation because little 

subsurface data were available.

Combo and others (1949) published a detailed report summarizing Montana coal resources by county, rank, reliability 

category, and thickness. Their estimate for coal resources 

in the Montana PRB was 126 BST. This included reliability 

categories of measured resources, indicated resources, inferred 

resources, and hypothetical resources based on distance from 

drill holes or outcrop and depths up to 2,000 ft. The measured 

and indicated coal reserves for the Montana PRB were estimated to be 47 BST for coal beds greater than 2.5 ft thick.

Berryhill and others (1950) provided a calculation of total 

original reserves of subbituminous coal in Wyoming by township, overburden thickness, and coal bed thickness. Coal tonnage estimates given for 86 townships entirely or partly within 

the Gillette coal field totaled about 45 BST (fig. 6). Their 

estimate was made for all coal beds more than 2.5 ft thick and 

overburden less than 2,000 ft thick. Those estimates were the 

sum of measured, indicated, and inferred reserve tonnages.

Mapel (1954) estimated 3 BST of coal reserves in 

the Buffalo–Lake DeSmet area in the Wyoming PRB, in 

beds more than 2.5 ft thick and under less than 1,000 ft of 

overburden (fig. 6). Several years later, Mapel (1959) estimated total coal reserves in the Buffalo–Lake DeSmet area 

in beds more than 2.5 ft thick and under less than 1,000 ft of 

overburden at about 6.4 BST. 

Mapel (1958) estimated about 193 BST of coal was 

present in coal beds greater than 2.5 ft thick in the entire PRB. 

The estimate was based on 87 BST in the Montana PRB and 

106 BST in the Wyoming PRB.

Ayers (1986a) provided an estimate of 1.06 TST of coal 

greater than 2 ft thick to a depth of 3,000 ft within the Tongue 

River Member of the Fort Union Formation in the Wyoming 

PRB (fig. 4).

Glass (2001) published an estimate of 1.03 TST of coal 

for the Wyoming PRB, which included coal beds of any 

thickness and to all depths, even greater than 6,000 ft. The 

remaining strippable coal reserve base for the Wyodak coal 

bed was reported to be 17.9 BST, using a 200-ft cutoff depth 

for overburden.

Ellis and others (2002) estimated 136.1 BST of original coal resource for five coal beds in the Gillette coal field 

(fig. 6). These resources were calculated for an area of the 

Gillette coal field encompassing about 1,500 mi2. The estimates showed that the available coal resource already defined 

represents about 89 percent of the original coal resource.

As documented in these various estimates, coal resource 

and reserve estimates change as more data become available. 

Therefore, new estimates provided in this report prove the 

usefulness of periodically recalculating coal resources and 

reserves. Estimates of coal resources and coal reserves in this 

report are a significant refinement of previous coal resource 

and reserve studies in the PRB.

Previous Coal Bed Nomenclature

Various names for individual coal beds and coal zones in 

the PRB have been used since the early 1980s (fig. 13). In fact, 

as many as 60 different bed names have been used throughout 

the basin. Historically, coal beds in Wyoming and Montana 

were named on the basis of a geographic location or the person who identified or described the bed.

A report by Kent and others (1980) described the 

northern part of the Gillette coal field and established a coal 

bed nomenclature system that has become the standard for 

much of the PRB in Wyoming (fig. 13). In that report, Kent 

used the name “Wyodak” from Mapel (1973) to describe a 

thick sequence of coals in the PRB. Pierce and others (1990) 

followed most of the same coal bed nomenclature of Kent 

and others (1980); however, they mapped the Wyodak coal 

bed splitting it into the Upper and Lower Wyodak beds and 

used the Roland bed name in place of the Smith bed (fig. 13). 

Although Flores and others (1999) followed the Pierce and 

others (1990) nomenclature, they introduced the concept of 

the Wyodak-Anderson coal zone, which includes the Smith, 

Badger, School, Sussex, Big George, Wyodak, Anderson, 

Dietz, Canyon, and Werner coal beds (fig. 13). A more detailed 

review of the historical coal geology and stratigraphy is provided in Flores and others (2010).
Methodology 9

Methodology

A three-phase methodology for calculating coal resources 

and reserves in the PRB is outlined on the flow chart in figure 14. 

This methodology has been used consistently for the previous four PRB assessments: (1) Gillette coal field by Luppens 

and others (2008), (2) Northern Wyoming Powder River 

Basin assessment area (NWPRB) by Scott and others (2010), 

(3) Southwestern Powder River assessment area (SWPRB) by 

Osmonson and others (2011), and the (4) Montana Powder River 

Basin assessment area (MTPRB) by Haacke and others (2013). 

The first phase involved data collection and editing. The second 

phase consisted of modeling, including final coal bed correlations and creation of an inventory of land-use and technical 

restrictions. The data entry and coal bed correlations tasks collectively represented the most man-hour-intensive effort of this 

assessment, representing about eight man-years. The third and 

final phase involved coal resource and reserve analysis.

Phase One (Data Collection and Editing)

Data pertaining to coal bed geology, extent and thickness of coal beds, interburden thickness, parting thickness, 

overburden thickness, structure, factors affecting coal extraction, coal ownership, coal quality, coal sales price, and tax 

information were gathered during the initial phase of the 

assessment (fig. 14). The following summaries provide more 

detail on the collection and editing processes.

Data Collection

The tremendous growth of CBM development since the 

early 1990s has facilitated a unique perspective of the subsurface coal stratigraphy in the PRB. The potential to more accurately delimit and correlate individual coal beds has been greatly 

enhanced with the completion of more than 27,000 CBM wells 

with corresponding geophysical logs. The Wyoming Oil and 

Gas Conservation Commission (WOGCC) Web site contains digital images of the geophysical logs of wells drilled in 

Wyoming (Wyoming Oil and Gas Conservation Commission, 

2011). Initially, images for 694 logs were downloaded from 

that Web site to develop preliminary coal bed correlations 

throughout the Gillette coal field. These images were then used 

to construct both north-south and east-west hard copy geophysical log framework cross sections on approximately six-mile 

spacing. During the correlation of the framework cross sections, 

it was realized that the amount of data from these cross sections 

was insufficient to resolve the complex coal bed stratigraphy. 

More closely spaced data would be needed, which resulted in 

an intensive data entry program (Luppens and others, 2008).

A preliminary map of the overburden depth to the top of 

the Anderson coal bed was generated. Based on this overburden map, additional in-fill drill-hole logs were then selected 

for data entry at a spacing of about 0.25 mi for areas less 

than 500 ft of overburden, 0.5 mi for areas of 500–1,000 ft 

of overburden, and 1 mi for areas of greater than 1,000 ft of 

overburden. Additional data were added in areas of particularly 

complex correlations. A 3-mile-wide buffer zone surrounding 

the Gillette coal field was added to extend the stratigraphic 

correlations and minimize edge effects when modeling the coal 

beds. A data collection process similar to this was used for subsequent PRB assessment areas, where thick coal beds incurred 

closely spaced CBM development.

Well logs for oil and gas and CBM wells were obtained 

from the WOGCC and MJ Systems (2009, 5085 Oakland St., 

Denver, CO 80239). USGS personnel completed data entry for 

6,387 wells of the total 10,210 data points for the Gillette coal 

field assessment. Subsequently, USGS personnel entered data 

for 2,821 points for the NWPRB assessment area, 3,161 points 

for the SWPRB assessment area, 1,956 points for the MTPRB 

assessment area, and 276 points for the East Gillette coal 

field extension area, bringing the total number of data entry 

points to 14,601.

Data from an additional 15,327 drill holes were supplied by the Montana Bureau of Mines and Geology (MBMG) 

(accessed 2012 at http://www.mbmg.mtech.edu/gis/

gis-datalinks.asp), Wyoming State Geological Survey (WSGS), 

and the USGS National Coal Resources Database System 

(NCRDS). All of the drill-hole data were entered or imported 

into the StratiFact database program (GRG Corporation, 1998). 

A total of 29,928 drill holes (of which 21,393 holes were 

nonproprietary) were used in the PRB assessment (fig. 15). The 

database for the 21,393 nonproprietary drill holes was published 

by the USGS in 2013 (Haacke and Scott, 2013).

Gamma-ray geophysical logs were available for most of 

the wells and were the basis for most of the lithologic interpretation. Normally, oil and gas wells are logged in detail primarily for deeper target formations. The upper intervals were either 

not logged or only gamma-logged through the surface casing. 

Geophysical log data in older oil and gas wells usually consisted of a combination of spontaneous potential, resistivity, or 

conductivity logs. The most reliable log suite for coal interpretation consisted of natural gamma, gamma-gamma density, and 

resistivity traces; however, many coalbed methane wells were 

logged with gamma-ray only, either in open hole or through 

steel drill pipe or casing. Additionally, some of the coalbed 

methane wells were logged only to the top of the target coal 

bed which required consulting production records for the coal 

bed thicknesses.

Noncoal lithology was not essential for the coal resource 

assessment of the PRB; consequently, much of the noncoal 

lithology was coded generically as rock. It is estimated that the 

interpretation of all the noncoal intervals would have doubled 

or tripled the time needed to complete the total data entry 

effort. Parting intercepts within coal beds and interburden 

between coal beds were also coded as rock. Intervals that were 

not logged by geophysical methods, such as the shallow 

portion of an oil well or CBM well, were designated as “No 

Log.” However, if the thickness of the methane-producing 

interval was available from production records for those 

CBM wells not completely logged, that interval was entered 

as “coal, CBM perf.”
10 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Data on various restrictions to mining were gathered and 

incorporated into GIS. Additionally, information required for 

the mining and economic evaluation, such as tax information, 

lease royalty costs, and updated costs for equipment, supplies, 

and manpower wage scales were assembled. Site visits to 

operating mines in the PRB were conducted during this initial 

phase and were an important activity to help ensure that the 

mine models developed for the coal recoverability analyses 

reflected current mining practices and approaches.

Phase Two (Modeling)

Phase two involved the correlation of individual coal beds, 

creating integrated, multi-coal-bed models, creating land-use 

and technical restrictions to mining (fig. 14). The coal bed correlation process is included in the modeling section because the 

bed nomenclature had to consider some limitations of coal bed 

modeling to avoid making the models too complex.

Coal Bed Correlations

Coal bed stratigraphy in the PRB is often complicated 

because of complex channel systems that controlled coal 

deposition. Thus, the geology alone makes the task of correlating individual coal beds in the PRB a significant challenge. 

In cases where thick partings split coal beds into distinct 

beds, the coal bed is correlated as a “lower” or “upper” bed of 

the primary bed. Further complicating the correlation effort 

was the fact that coal beds extending from Wyoming into 

Montana often had different names. Also, thick, shallow coal 

beds in the eastern Gillette coal field and the western PRB, 

coupled with a lack of substantial subsurface data early in 

the reporting of the basin, led to a proliferation of local coal 

bed nomenclature.

Flores and others (2010) believed that there is confusion, 

basinwide, over the names, correlation, and distribution of 

individual coal beds that requires resolution in order to make 

meaningful estimates of both coal and CBM resources in the 

PRB. Because of the existing uncertainties in the correlation of individual thick coal beds, Flores and others (1999) 

suggested that coal resource estimates should be performed 

according to coal-zone intervals. However, meaningful 

coal resources, and especially reserve assessments, must be 

founded on geological models of individual coal beds, not 

by coal zones. Flores and others (2010) attempted to resolve 

some of the correlation confusion by publishing a database 

containing 1,715 well logs, with a network of 17 cross sections. The primary objectives of the Flores and others (2010) 

report were to revise and improve the mapping of coal beds 

in the Fort Union and Wasatch Formations. There were, 

however, numerous coal bed nomenclature conflicts with tie 

wells in the database between the north-south and east-west 

cross sections. The use of multiple bed names for identical coal bed intervals in the Flores and others (2010) report 

database precluded accomplishing the study’s objectives. 

Consequently, the only coal bed maps in the Flores and others 

(2010) report were based solely on the net thickness of coal 

beds within the Wyodak-Anderson coal zone, rather than 

individual coal bed isopach maps.

The Gillette coal field report (Luppens and others, 2008) 

was the first assessment to take advantage of recent CBM 

drilling, which provided sufficient data control to correlate 

and map individual beds on a regional scale (fig. 2). Extension of the coal bed correlations northward from the Gillette 

coal field to the Montana State line and westward across the 

Wyoming PRB to the Sheridan coal field was accomplished 

in the NWPRB assessment area report (Scott and others, 

2010). Completion of the correlation and mapping of the 

coal beds in the remaining Wyoming portion of the basin was 

accomplished in the SWPRB assessment area (Osmonson and 

others, 2011) (fig. 2). The MTPRB assessment area (Haacke 

and others, 2013) report was the completion of the correlation 

and mapping of coal beds in the Montana PRB (fig. 2).

The initial correlation and coal bed nomenclature 

stratigraphically below the Wyodak-Anderson coal zone were 

guided by five USGS cross sections: (1) McLellan and others 

(1990); (2) Pierce and others (1990); (3) Hardie (1991); 

(4) Molnia and Pierce (1992); and (5) McLellan (1991). 

Following data entry by USGS personnel for the Gillette 

coal field assessment, final correlations were refined from 

the preliminary framework cross sections.

A graphical interface to the StratiFact (GRG 

Corporation, 1998) database was a critical tool for managing the interpretation of large amounts of new stratigraphic 

data. Using StratiFact, cross sections were selected, edited, 

and correlations were completed onscreen. Both linear and 

circular cross sections were constructed to correlate coal beds 

across the PRB. Circular cross sections that verified closure were especially valuable when coal beds either split or 

thinned adjacent to channels systems. With this process, the 

beginning and ending drill holes of the cross section are the 

same, assuring that the coal beds align stratigraphically with 

each other and provide closure to the section.

Figures 16 and 17 show that with new data and circular cross sections, previous correlations can be verified or 

refined. As seen in figure 16, there is a 9-mi gap between drill 

holes API 49-005-24358 and API 49-005-33013. Both drill 

holes contain thick coal beds that were assumed to be the 

Upper Wyodak coal bed (Anderson coal bed in this assessment) (Molnia and Pierce, 1992). In the Gillette coal field 

assessment, nine additional drill holes were added between 

those two drill holes, demonstrating that the new data were 

essential in revising and improving the confidence in the 

correlations (fig. 17). Figure 17 shows that the Anderson and 

Canyon (Lower Wyodak) coal beds do not split and that the 

thick upper coal bed in API 49-005-24358 is actually the 

Smith coal bed, not the Anderson (Upper Wyodak) as shown 

in figure 16.
Methodology 11

The Anderson and Canyon coal beds split and thin as 

they extend towards the NWPRB assessment area from the 

northern part of the Gillette coal field (fig. 10) (Scott and 

others, 2013). Channel areas where coal beds are thin or 

absent (referred to as “want areas” by Flores and others, 2010) 

posed challenges for extending coal bed correlations west 

and north from the Gillette coal field. Figure 18 illustrates a 

significant “want area” in eastern Sheridan County, Wyoming. 

Not only were many of the coal beds thin or absent, but drilling data were relatively sparse because of a lack of sufficiently 

thick CBM development targets (fig. 15). To correlate around 

these “want areas,” the coal bed correlation process proceeded 

north through the east margin of the NWPRB assessment 

area and then westward through the southernmost townships 

in Montana. The coal beds remained relatively thick enough 

to extend correlations across the NWPRB assessment area 

(fig. 18) (Scott and Luppens, 2013).

Although correlations focused on the Wyodak-Anderson 

coal zone in the Gillette coal field, coal beds from the Felix to 

the Pawnee were correlated (fig. 13). Three relatively persistent deeper coal beds below the Pawnee bed were informally 

correlated to the Deep 1, 2, and 3, rather than trying to sort out 

the various local bed names. Figure 13 shows coal bed nomenclature used for the Gillette coal field, NWPRB assessment 

area, SWPRB assessment area, and MTPRB assessment area, 

and this report, as well as their relations to the coal bed names 

used in previous studies.

For the NWPRB assessment area, the Odell and Roberts 

coal beds, stratigraphically below the Pawnee coal bed, had 

significant areas 10-ft thick or greater in thickness and were 

therefore correlated and assessed. The Deep 1, 2, and 3 coal 

beds were also correlated, but these beds remained relatively thin and insignificant from a resource standpoint. In 

the SWPRB assessment area, the Deep 1, 2, and 3 coal beds 

had significant areas greater than 10 ft in thickness. For the 

MTPRB assessment report, local names were used for coal 

beds stratigraphically lower than the Pawnee bed such as the 

Knobloch (fig. 13). A “dash” was used for formal hyphenated 

names such as the Flowers-Goodale. Beds with equivalent 

local names were separated with a virgule (/) for example, 

the Rosebud/Knobloch bed. 

The final task of the correlation process was to unify 

the coal bed nomenclature of the four assessment areas into a 

single database to support coal bed mapping on a basinwide 

scale. The first step in this process was to complete the correlations for deeper coal beds below the Pawnee bed which 

were not originally assessed in the Gillette coal field report 

(Luppens and others, 2008). The eastern limit of the Gillette 

coal field assessment was the subcrop of the thick Anderson 

and Canyon beds; therefore, the area east of the depth where 

the deeper coals would crop out was not evaluated.

To complete the evaluation of these deeper coal beds, the 

East Gillette coal field extension was assessed (fig. 2). Setting 

the east boundary of the extension area at the limit of Tertiaryage rocks in the basin also coincided with the NWPRB and 

SWPRB assessment area eastern boundaries (fig. 2). The East 

Gillette coal field extension assessment required supplementing limited drilling information from the original Gillette coal 

field database with data entry of additional oil and gas wells. 

With these additional data, the correlation of the deeper coal 

beds from the Gillette coal field was expanded towards the 

east margin of the basin (fig. 8).

The last step in developing a unified, correlated database 

for the PRB was melding the Wyoming and Montana coal bed 

correlations into a single nomenclature. Since the Wasatch 

Formation is essentially confined to the Wyoming PRB, there 

are no significant State-to-State nomenclature issues. The principal coal beds within the Wyodak-Anderson coal zones were 

also straightforward as bed names such as the Smith, Anderson, 

and Canyon are used in both Wyoming and Montana. The 

coal bed nomenclature below the Wyodak-Anderson coal 

zone is especially problematic. Using StratiFact to display 

onscreen cross sections effectively resolved equivalent coal 

beds. Dual bed names separated by a virgule (/) were adopted 

where it made sense to keep ties to the regional nomenclature. 

For example, the Deep 3 bed in Wyoming correlated with the 

Flowers-Goodale bed in Montana. The final name used for 

this coal bed was the Flowers-Goodale. Figure 13 summarizes 

how the coal bed names evolved through the four assessment 

areas and the resultant coal bed nomenclature used for this 

summary report.

As a result of the correlations and unification of coal 

bed nomenclature, many coal bed names used in other reports 

were not used in this report. Names eliminated include: 

Badger, Broadus, Carney, Carlson, Carson, Elk, Kendrick, 

Kennedy, King, Mackin-Walker, Poker-Jim, Sawyer, Swartz, 

and Waddle.

Coalbed Modeling

The next step of Phase two of the assessment (fig. 14) 

was the creation of digital coal bed models to determine the 

original resources for all 47 beds. Preliminary coal isopach 

maps were created using the single-bed modeling program 

Surfer (Golden Software, 2002) to review coal bed areal 

extent. The basic assumption used to qualify coal beds for 

potential coal resource evaluation was a thickness of at least 

2.5 ft (Wood and others, 1983).

The integrated multibed modeling program PC/Cores

(Mentor Consultants, 2005) was used to produce gridded coal 

bed models for the 47 coal beds identified in the PRB assessment (fig. 13). This modeling program is designed for coal 

and mineral assessments and is especially effective for coal 

bed modeling because of the capability to simultaneously grid 

multiple beds. The program provides a considerable reduction 

in total modeling time compared to other programs that grid 

only one parameter at a time. Grids must be made for coal 

thickness, parting thickness, coal height (coal plus parting), 

roof and floor structures, and overburden and interburden 
12 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

thicknesses for each bed. The roof grid for each coal bed must 

be individually subtracted from the surface grid or the floor 

grid for the next stratigraphically higher coal bed.

Most multiple coal bed modeling programs are highly 

automated with a sophisticated subroutine that uses individual 

coal bed structure grids to check for drill holes too shallow to 

penetrate a given bed. This feature produces more accurate 

digital models without the need for extensive manual editing. 

The PC/Cores® program code was further modified to allow 

correlations to pass through the sections of the drill holes 

that were not logged to reduce the generation of “false zero” 

thickness values.

Quality control methods to verify coal bed correlations 

and coal bed areal distributions were essential to this assessment. This was accomplished by generating preliminary 

isopach and structure contour maps for each modeled bed to 

check for “bull’s eye” anomalies. Also, a routine within the 

PC/Cores modeling program was used to identify anomalous 

locations by comparing collar elevations to the digital elevation model (DEM) of the Earth’s surface; many location errors 

were resolved using this technique. 

Methods to reduce the effects of projected contours were 

also devised to limit erroneous data projections. A circle with 

a 0.75-mi radius was generated around every data location 

with at least one coal bed intercept. A line was then digitized 

through the updip sides of the circles using the locations closest to the basin margins. This digitized line was used as a gridding boundary to prevent gridding projections where coal data 

were insufficient. The boundary line was especially important 

on the west margin of the basin where the strata are steeply 

dipping and coal beds are thinning or pinching out (figs. 3, 

8, and 9).

To generate isopach grids for coal bed geometries, the 

use of an option in the PC/Cores modeling program known 

as “pinching” was used. While extracting X, Y, and Z coal 

bed thickness files to be gridded, the pinching option caused 

a negative thickness to be generated for a hole where the bed 

was missing. This resulted in the zero thickness value placed 

halfway between the nearest positive thickness data point and 

the actual zero value location. Therefore, use of the pinching 

function provided a slightly more conservative projection of 

coal bed areal extent, particularly where data points were more 

widely spaced.

For the final coal bed model, 5 grids including thickness, 

roof, floor, bed height, and parting, were generated for each coal 

bed for a total of 235 grids for the 47 coal beds modeled. The 

coal bed models were gridded at a resolution of 150 meters 

(m) (about 500 ft) with a total of about 3,954,000 cells in a 

single grid. The file size of individual grids ranged from about 

25 to 45 megabytes. 

The grids for the coal resource model (coal thickness, parting thickness, roof elevation, floor elevation, and 

bed height) for each of the 47 coal beds were converted in 

PC/Cores to a generic ASCII grid format. These ASCII grids 

were then exported to ArcView(Environmental Systems 

Research International, 2006) to perform the last step in Phase 

two of the assessment, modeling restrictions to mining.

Restrictions to Mine Models

The final step in Phase two of the assessment was to 

create grids of land-use and technical restrictions to mining by 

coal bed. The objective of this step in resource planning is to 

determine the amount of available coal resources. This process is accomplished by first subtracting the amount of mined 

coal and clinker from the amount of original resources; the 

result is remaining resources. Subtracting the amount of landuse restrictions and technical restrictions from the amount 

of remaining resources yields available resources. The following discussion details the methodology used in determining 

available resources.

The coal bed model files created in PC/Cores were 

imported into GIS. The GIS was used to allocate coal 

resources, by first subtracting amounts of various restrictions 

to mining (fig. 19) (for example, mined coal, towns, National 

forests, alluvial valley floors) in order to calculate the amount 

of available coal.

ArcView and the ArcView Spatial Analyst extensions 

(Environmental Systems Research Institute, Inc., 2006) were 

used to perform the various GIS analyses and ultimately 

calculate the amount of coal resources. In addition, ArcGIS 

(Environmental Systems Research Institute, Inc., 2006) was 

used to project digital coverages, shapefiles, and grids to 

the assessment area’s base map projection. The geographic 

referencing base for the digital data used for the GIS analysis 

was the Universal Transverse Mercator (UTM) map projection, 

using the following parameters: map units = meters; zone = 13; 

datum = NAD27; and spheroid = Clarke, 1866.

For this GIS assessment, a grid cell size of 30 m (about 

100 ft) was chosen. This smaller grid size was required to 

better define restrictions to mining. All grids used for the GIS 

analysis were either originally created with a grid cell size of 

30 m or resampled to 30 m from another cell size. In the case 

of the digital coal model grids, the cell size was resampled 

from 150 m to 30 m. 

The first task in the GIS process involved the creation 

of ArcView (Environmental Systems Research Institute, Inc., 

2006) grids from ASCII data representing files for coal, parting, 

and overburden isopach grids that were created from the digital 

coal models. These ArcView grids were then used to create 

a total thickness (coal plus parting) grid, and the areal extent 

grid for each coal bed to be evaluated. Grids were then created 

to categorize an extent of a specific theme for the entire PRB. 

These grid themes consisted of mined-out areas, burned coal 

areas, land-use restrictions, technical restrictions, overburdento-coal-bed ratios, counties, mineral ownership, stripping 

ratios, resource reliability categories, and coal bed depth.
Methodology 13

The grid theme for burned coal areas was developed from 

digital surface clinker information obtained from the Montana 

Bureau of Mines and Geology Geographic Information 

Systems Lab (2012) and Coates and Heffern (1999) (fig. 7). 

To estimate the amount of coal within the PRB that has been 

burned, it was assumed that there is up to a 3:1 ratio of clinker 

thickness to burned coal thickness (Coates and Heffern, 1999). 

Consequently, to estimate the areas of coal within each bed 

that has been burned, a combination of surface clinker extent, 

coal overburden thickness, and coal bed thickness was used 

during the assessment. Specifically, wherever surface clinker 

is present over a coal bed and the thickness of the overburden 

is three times (or less) the thickness of the coal, the coal within 

the bed was considered to be completely burned. This calculation produces a conservative estimate of the amount of burned 

coal throughout the PRB.

 The grid theme for mineral ownership was obtained 

from the USGS (2012, available at http://pubs.er.usgs.gov/

publication/ofr981) (fig. 20). The grid themes for mined coal, 

land-use restrictions, and counties, were derived from digital 

information obtained from the Natural Resource Information 

System GIS Data List of the Montana Bureau of Mines and 

Geology Geographic Information Systems Lab (2011) and 

the Wyoming Spatial Data Clearinghouse (2009) (fig. 19). 

The remaining grid themes were developed internally within 

the USGS using ArcView (Environmental Systems Research 

International, 2006).

The grid of land-use restrictions includes various buffer 

zones that surround each restricted area. The location and width 

of these buffers are typically mandated by State or Federal 

regulations. One of the important improvements in this USGS 

assessment methodology was revising a technique for defining 

surface restrictions at depth. Previous economic assessments 

applied a standard vertical projection downward through the 

coal beds when applying regulatory surface buffers (such as 

a 300-ft buffer around an inhabited house) below the surface. 

Because of the additional setback distance required to maintain a safe mining-pit highwall angle, a restricted area actually 

widens with depth when surface-mining operations are considered. Figure 21 illustrates the effect of depth on overall land-use 

restriction size. For example, a circular restriction having a 

diameter of 600 ft at the surface encompasses an area of about 

282,600 square feet (ft2

), or approximately 6.5 acres. However, 

at a depth of 200 ft, this same restriction has a diameter of 858 ft 

and encompasses an area of about 577,900 ft2

, or approximately 

13 acres. At a depth of 500 ft, the same restriction has a diameter of 2,144 ft and encompasses an area of about 3,608,400 ft2

, 

or approximately 83 acres.

The grid for mined coal accounts for all prior mining 

within the PRB including those mines shown in figure 12. The 

coal mineral ownership grid was divided into Federal, State, 

and private ownership categories (fig. 20). The resource reliability grids were divided into measured, indicated, inferred, 

and hypothetical coal categories (Wood and others, 1983). The 

overburden grids were reported in 5 depth categories: 0–500 ft; 

500–1,000 ft; 1,000–2,000 ft; 2,000–3,000 ft; and greater than 

3,000 ft. For this assessment, overburden depth is calculated 

where the coal bed is 2.5 ft thick or greater.

The next step in the methodology was to combine individual grids into one composite theme grid. The composite 

theme grid was then combined with each respective coal bed 

areal-extent grid. This was done in order to define the PRB 

resources on a bed-by-bed basis, using all attributes of the 

grid. Areas within each coal bed that represented mined coal, 

land-use, and technical restrictions were removed from consideration. Supplemental to this report are GIS data created using 

Esri ArcGIS 9.3.1 (Environmental Systems Research International, 2006) that can be used to show mineral ownership, 

mined out areas, land-use and technical restrictions for all 47 

coal beds in map view, along with other pertinent data layers 

(Kinney and Scott, 2015).

Although coal resources were calculated using a 

minimum thickness of 2.5 ft, coal beds less than 5.0 ft thick 

were considered technically restricted, for surface mining 

operations. Consequently, separate PC/Cores® models were 

produced for coal beds that excluded areas where the coal 

resources were less than 5.0 ft thick. Coal resources were allocated to separate stripping ratios for coal beds included in the 

economic evaluation.

Factors Affecting Extraction of Coal Resources

Many factors affect the availability of coal for mining and a four-step screening process defined in the 43 Code 

of Federal Regulations (CFR) 3420.1–4 was used to determine which areas of Federal coal are acceptable for leasing (Office of the Federal Register, 2003). The following 

20 coal-leasing unsuitability criteria are listed in the Code of 

Federal Regulations, Title 43 Subpart 3461.5 (43 CFR 3461.5). 

Unsuitability criteria

Alluvial valley floors

Bald and golden eagle roost and concentration areas

Bald or golden eagle nests

Critical habitat for threatened or endangered plants

Critical habitat for animal species

Dwellings, roads, cemeteries, and public buildings

Federal lands containing active falcon cliff nesting site

Federal land systems

Floodplains

Fish and wildlife habitat for resident species

Habitat for migratory bird species

Historic lands and sites

Lands used for scientific study

Lands with outstanding scenic quality

Municipal watersheds

National resource waters

Natural areas

State listed threatened or endangered species

State or Indian tribe proposed criteria

Rights-of-way and easements (for example, railroads)

Wilderness study areas
14 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

These criteria are used to determine if an area is unsuitable for 

leasing and surface mining and were originally established by 

the Surface Mining Control and Reclamation Act (SMCRA) 

of 1977 (30 U.S.C. 1201et seq.). Although developed for lands 

owned by the Federal government, many of the unsuitability 

criteria are also applicable to State owned and privately owned 

lands (fig. 20). For example, areas containing threatened or 

endangered plant or animal species are protected from destruction wherever they occur. Municipal watersheds are also 

protected from detrimental actions regardless of land ownership. Not all criteria in the Unsuitable Criteria list affect mining 

development within the PRB. Other potential land-use restrictions to mining include airports, archaeological areas, coalbed 

methane wells, oil and gas wells, pipelines, power lines, rivers, 

lakes, streams, and towns.

Restrictions to mining vary with location and local land 

management regulations. This report follows practices governing restrictions to mining in the PRB. In addition, BLM personnel in Casper, Wyoming, and Billings, Montana, provided guidance concerning restrictions to mining and the distances to be 

buffered around specific features. Required buffer distances can 

change through time; however, buffer distances for this assessment were selected based on current regulations (October 2014). 

A more detailed determination of restrictions and other availability considerations would be necessary as part of the leasing 

and mine-planning phases for any mining operation. Figure 19 

shows areas of land-use restrictions within the PRB; a discussion of identified mining restrictions follows.

Airports

The Broadus airport is located near the town of Broadus, 

Montana, about 2.5 mi northwest of the central business district 

(fig. 19). For this assessment, the airport (including a 300-ft 

buffer surrounding the airport) is considered a restriction to 

mining. The Colstrip airport is located about 4 mi southwest of 

the central business district of Colstrip, Montana, and is located 

on reclamation land that is surrounded by adjacent mining 

areas of the Rosebud Mine. Therefore, the Colstrip airport is 

not considered to represent a separate restriction to mining for 

this assessment.

The Sheridan County airport is adjacent to the city 

of Sheridan, Wyoming, and is included within the town of 

Sheridan restriction buffer area (fig. 19). The Johnson County 

airport is adjacent to the city of Buffalo, Wyoming, and is 

included in the town of Buffalo restriction buffer area (fig. 19). 

The Campbell County airport is adjacent to the city of Gillette, 

Wyoming, and is included within the town of Gillette restriction buffer area (fig. 19).

Alluvial Valley Floors 

Areas identified as alluvial valley floors, where mining 

would interrupt, discontinue, or preclude farming, are considered restrictions to mining, according to the Surface Mining 

Control and Reclamation Act of 1977 (30 U.S.C. 1201 et seq.) 

(fig. 19). In addition, areas outside the alluvial valley floors 

may also be designated unsuitable where mining might 

damage the quantity or quality of water supplying the alluvial 

valley floors. This assessment did not include these specific 

areas in the delineation of restrictions.

Archaeological Areas 

No major archaeological areas that would prevent mining 

have been identified in the PRB. However, there are several 

minor archaeological and historic sites within the PRB. A 

mitigation plan would need to be developed before coal mining disturbed any of these areas. Therefore, coal within these 

known sites was not excluded from this resource assessment.

Coalbed Methane

Disputes over ownership of CBM resources have arisen 

between coal mining and CBM development companies as to 

whether the CBM resources belong to the owner of the oil and 

gas estate or the owner of the coal estate. Determination of the 

ownership of CBM resources was resolved by the U.S. Supreme 

Court in 1999, ruling that CBM resources are part of the oil 

and gas estate (Supreme Court of the United States, Amoco 

Production Co. v. Southern Ute Tribe (98-830), 526, U.S. 865 

(1999). In addition, the court specified the owner of a CBM 

lease has the right to gain access and to develop its estate, and 

owners of the land surface should be adequately compensated 

for damage to their property resulting from CBM extraction. 

The BLM has established Conflict Administration Zones to 

guide development of CBM leases in the path of near-term 

coal mining (Bureau of Land Management, 2013). In these 

zones, standard guidelines offer a process for settling conflicts 

and scheduling development of each resource under a Federal 

mineral estate.

The production of CBM produces large volumes of 

groundwater that is pumped from the coal bed. The groundwater 

is generally discharged to holding ponds for consumption by 

livestock, discharged to existing drainage systems, released into 

the atmosphere through the use of misting towers, or reinjected 

into another stratigraphic unit. Rice and others (2000) investigated concerns over potential environmental effects of CBM 

development including possible contamination of surface water, 

water quality in holding ponds, formation of saline crust on 

the ground surfaces, lowering of the water table, and possible 

groundwater contamination or depletion of existing aquifers.

Since the early 1980s, more than 27,000 new CBM wells 

have been drilled in the Wyoming PRB (Wyoming Oil and 

Gas Conservation Commission, 2011) (fig. 15). Production of 

CBM is mostly from the Wyodak-Anderson coal zone (Smith, 

Anderson, and Canyon coal beds). The area of high CBM 

potential in Wyoming is controlled by the distribution of thick 

coal beds (fig. 22). In 2008, about 535 billion cubic ft of CBM 

was produced from 24 unique coal deposits in 10 Tongue River 

Member coal zones that occur in the Wyoming PRB (Jones, 

2010a). The CBM resource in the Wyoming PRB is estimated 

to be 37 trillion cubic ft assuming 65 cubic ft of CBM per 

ton of in-place coal (De Bruin, 2009; Nick Jones, Wyoming 

Geological Survey, oral commun., 2009). The production life 
Methodology 15

of CBM wells is estimated to be about 10–12 years, although 

production from multiple beds can extend the life of the well 

by an additional 10–30 years (De Bruin and others, 2004).

CBM development in the Montana PRB began in about 

1991, but has proceeded at a much slower pace than in the 

neighboring Wyoming PRB. Approximately 1,100 wells have 

been drilled near the Decker Mine, along the Montana–

Wyoming border (Montana Board of Oil and Gas, accessed 

June 2011, at http://www.bogc.dnrc.mt.gov). CBM development in the Montana PRB is restricted to a relatively small 

area in Big Horn County that includes T. 8–9 S., R. 39–41 W. 

(fig. 15). Although current (October 2014) CBM production is 

from the Smith, Anderson, Dietz 2, Dietz 3, Canyon, Werner/

Cook, and Gates/Wall coal beds, there may be additional 

potential for production from deeper coal beds in the Montana 

PRB. Van Voast and Thale (2001) identified areas of high, 

moderate, and low CBM potential for the MTPRB (fig. 22).

The lack of CBM expansion in the Montana PRB is 

because of a combination of less favorable coal bed targets 

and increased distance from existing infrastructure. Coal beds 

in the Montana PRB are not as well suited to CBM development as coal beds in the Wyoming PRB because they lack the 

overall depth and thickness when compared to the central and 

southern PRB coal beds. Coal beds become shallower and 

eventually crop out to the northern portion of the MTPRB in 

response to structural and topographic control. Although this 

may be advantageous for surface mining, it is not beneficial 

for CBM development. Coal beds at shallow depths or near 

outcrop are likely to have lower hydrodynamic pressures (the 

pressures necessary to retain the adsorbed methane). Under 

reduced pressures, methane gas in coal beds can migrate 

towards the outcrop and eventually escape.

Although there are thousands of CBM wells within the 

PRB, designating all of these wells and their accompanying 

pipeline infrastructure as being restrictive to mining would 

exclude a significant volume of coal resource from mining consideration. For the purpose of this assessment, it is 

assumed that coal within any part of the PRB will be mined 

after CBM operations have ceased in that area; therefore, the 

wells and accompanying pipeline infrastructure are not considered a restriction to mining.

Dwellings and Buildings

Individual dwellings and buildings that exist outside of 

incorporated areas (such as Colstrip, Montana) are not considered restrictions to mining within the PRB. These structures 

are typically purchased by a coal company, which could move 

or raze them in order to proceed with mining.

Federal Land Systems

Almost 86 percent of the coal in the PRB is owned by 

the Federal government and must be leased in order to be 

mined. The largest contiguous parcel of Federal-owned land 

in the PRB is the Custer National Forest, in the Montana PRB 

(fig. 19). The Custer National Forest covers an area of about 

783 mi2 in western Powder River County and extends into 

southern Rosebud County. The same unsuitability criteria and 

land-use conflicts discussed earlier in this report apply to coal 

mining in the Custer National Forest. Therefore, the national 

forest is a restriction to surface coal mining, and the restriction includes a buffer that extends 300 ft beyond the forest’s 

boundary. However, the BLM could develop coal leasing and 

mining stipulations in cooperation with the U.S. Forest Service 

(USFS) for underground coal mining. Federal subsurface coal 

ownership is shown in figure 20.

Fort Keogh National Wildlife Refuge is located immediately southwest of Miles City, Montana, at the northern 

boundary of the Montana PRB (fig. 19). A national refuge is 

typically a restriction to mining. Because the mapped coal 

beds do not extend into the refuge, the Fort Keogh refuge did 

not restrict any assessed resources. 

The southern part of the Gillette coal field is part of the 

Thunder Basin National Grassland that includes scattered 

Federal lands under the jurisdiction of the USFS. The same 

unsuitability criteria and land-use conflicts discussed in this 

report apply to coal mining on the Thunder Basin National 

Grassland. Where the mineral ownership is Federal, the BLM 

develops coal leasing and mining stipulations in cooperation with the USFS. Therefore, the Thunder Basin National 

Grassland is not considered a restriction to mining.

Historic Lands and Sites

The site of the “Battle of Wolf Mountains” is about 3 mi 

southwest of Birney, Montana, along the valley of the Tongue 

River (figs. 1 and 19). This site is the location of the last major 

battle of the Great Sioux War of 1876–1877 (National Park 

Service, 2012) and was added to the National Register of 

Historic Places in 2001. In 2008, the site became a National 

Historic Landmark; therefore, the 1,300-acre site is a restriction to mining.

Oil and Gas Development

The Hilight gas plant is approximately 7 mi northeast of 

the town of Wright, Wyoming, and connects to several major 

pipelines for gas and crude oil, as well as a pipeline for gas 

processing products (fig. 19). This installation, with a 100-ft 

buffer is considered a restriction to mining. The Kitty gas plant 

also connects to several major pipelines for gas and crude oil, 

and gas processing products. However, the plant is within the 

jurisdiction of the buffer zone restriction surrounding the town 

of Gillette, Wyoming.

Current infrastructure for production and transport of oil 

and gas in the area includes roads, pipelines, compressor stations, and separators. Generally, there is little conflict between 

coal development and conventional oil and gas development in 

the PRB, as oil and gas reservoirs are primarily in stratigraphic 

units below minable coal beds. Where oil and gas development 

and coal mining occur in the same areas, mining is confined to 

areas outside a specified buffer distance from wells, pipelines, 

and other oil and gas related structures. Resolution of land-use 
16 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

conflicts between coal mining and the oil and gas field development will depend on economic conditions, regulations, and 

negotiations between oil developers and coal developers.

Thousands of oil and gas wells are located throughout 

the PRB. An area around a major cluster of active wells might 

be eliminated from mining activities until these wells are no 

longer actively producing, or mining activities might proceed 

around individual active wells that are given a buffer zone. 

Conversely, specific wells might be plugged and then reestablished after mining. For this assessment, it was assumed that 

the wells will no longer be actively producing when mining 

operations affect them; they are not considered to be restrictions to mining.

Pipelines

There is a network of underground oil and gas pipelines 

throughout the entire PRB. Most of these pipelines could be 

moved so that surface mining could proceed. However, moving and restoring them would represent an added economic 

cost to mining. In any case, pipelines were not considered to 

be restrictions to mining for this assessment.

Power Lines

All power lines within the PRB could be moved to 

accommodate surface mining operations and are not considered a restriction to mining in the PRB.

Railroads

There are two main railroad routes through the Gillette 

coal field in the Wyoming PRB (fig. 19). The generally eastwest route in the north part of the Gillette coal field is a rail 

line of the Burlington Northern Santa Fe Railway that runs 

northwesterly through Sheridan, Wyoming. The north-south 

route in the eastern part of the Gillette coal field is a combination of rail lines of both the Burlington Northern Santa Fe 

Railway and the Union Pacific Railroad. This combination of 

rail lines is referred to in this report as the “Joint Line” and 

runs from Gillette, Wyoming, south to Douglas, Wyoming. 

In addition to the main rail lines, a number of additional spur 

rail lines serve existing coal mines. However, these spur lines 

can be moved as the mining operations progress, and they are 

not considered a restriction to mining. Although it is conceivable that the main lines of the existing rail routes could also be 

relocated to allow mining to proceed, it is assumed that these 

main rail lines would not be moved and are restrictions to mining. The total restricted width for each main rail line, including 

the right-of-way and a 100-ft buffer along each side, is 600 ft.

The main railroad route through the Montana PRB is 

an east-west rail section of the Burlington Northern Santa Fe 

Railway that is in the extreme northern part of the basin. It is 

not considered a restriction because coal beds do not extend 

into this area (fig. 19). In addition to the main rail line, there 

are three spur rail lines that exist over coal resource areas 

within the Montana PRB. Two of the spur lines connect to 

this main rail line and extend south to Absaloka and Rosebud 

Mines. The third spur rail line connects to the main rail line of 

the Burlington Northern Santa Fe Railway south of the assessment area (near Sheridan, Wyoming) and extends north to the 

Decker and Spring Creek Mines. It is assumed that the spur 

lines would be moved as necessary for mining. They are not 

considered to be restrictions to mining. 

Rivers, Lakes, and Streams

The most significant rivers in the PRB are the Powder 

and the Tongue. All of the rivers and tributaries in the PRB 

are shallow and slow moving. Surface mining operations 

could temporarily relocate the courses of smaller streams 

and then return them to their pre-mining locations during 

mine reclamation. Only the parts of these water courses that 

have been designated by the State Land Quality Division as 

alluvial valley floors significant to farming would need to be 

preserved with no modification. In contrast, the Yellowstone 

River is a more prominent water course and is considered to 

be a restriction to mining (fig. 19). However, like the main rail 

line and Interstate Highway 94, the Yellowstone River lies in 

the extreme northern part of the PRB beyond the extent of coal 

beds and subsequently has no restriction effect.

The North Platte River flows through a small part of the 

southern end of the Wyoming PRB (fig. 19). This prominent 

water course is considered a restriction to mining. In addition 

to the width of the river, the restriction includes a 100-ft buffer 

on each side. The most significant body of flowing water in 

the Gillette coal field is the Belle Fourche River. It is shallow 

and slow moving; therefore, surface mining operations could 

relocate the course of this river and return it to the pre-mining 

location during reclamation.

Shallow lakes and small ponds that exist within the PRB 

could either be temporarily moved during mining or simply 

reformed after the mining operation ceased. However, the 

Tongue River Reservoir, a recreational site and water supply 

source located about 2.5 mi northeast of Decker, Montana, is 

considered to be a restriction to mining for this assessment 

(fig. 19). The restriction includes a 100-ft buffer surrounding 

the reservoir. Lake DeSmet, a recreational site and water supply source located about 6 mi north of Buffalo, Wyoming, is 

considered a restriction to mining and includes a 100-ft buffer 

surrounding the lake (fig. 19).

Roads

County roads within the PRB are not considered to be 

a restriction to mining because they could be relocated or 

temporarily blocked off to allow mining to proceed. A number 

of State and U.S. highways including Interstate Highway 94, 

Interstate Highway 90, and Interstate Highway 25, are present 

within the area (fig. 19). For this assessment, it is assumed that 

any State highway could be relocated to allow for mining. The 

Interstate highways are considered a restriction to mining. The 

total restricted width is 450 ft, including the highway right-ofway and a 100-ft buffer on each side. 
Methodology 17

State Lands and Trusts

Two State parks are within the Montana PRB: the Rosebud 

Battlefield State Park and the Tongue River Reservoir State Park 

(fig. 19); both parks are considered to be restrictions to mining. 

The Rosebud Battlefield State Park is about 15 mi northwest of 

Decker, Montana, and the Tongue River Reservoir State Park 

is about 6 mi northeast of Decker. The restriction for each park 

includes a buffer that extends out to a distance of 300 ft beyond 

the park boundary.

Also within the Montana PRB are a fishing access site 

(Twelve Mile Dam) and two conservation easements (fig. 19). 

The fishing access site and one of the easements are under 

the jurisdiction of the Montana Fish, Wildlife & Parks. The 

other conservation easement is overseen by the Montana Land 

Reliance. These lands are considered to be restrictions to mining; however, they have no restriction effect on the coal beds 

because the coals do not extend into their locations.

Towns

The municipalities of Colstrip and Broadus are within 

the PRB and are permanent restrictions to mining (fig. 19). 

In addition to the actual incorporated area, the mining restriction for each municipality includes a buffer that extends 300 ft 

beyond the municipality limits (extraterritorial jurisdiction).

The entire municipalities of Buffalo, Clearmont, Gillette, 

Ranchester, Sheridan, and Wright, and parts of Douglas and 

Rolling Hills are within the Wyoming PRB (fig. 19). In addition to the actual incorporated area for each municipality, the 

mining restriction includes a buffer that extends beyond the 

municipality limit.

Phase Three (Assessment of Resources 

and Reserves)

The methodology for resource assessment in the geologically complex PRB was accomplished in two stages. The PRB 

was divided into five geographic areas to manage database size 

and publish more timely results. Four of those areas are in the 

Wyoming PRB and one is in the Montana PRB: (1) Luppens 

and others (2008) reported on the first assessment area, 

summarizing geology, coal resources, and reserves for the 

Gillette coal field; (2) Scott and others (2010) summarized the 

second assessment area and presented results on geology, coal 

resources, and reserves for the Northern Wyoming Powder 

River Basin assessment area (NWPRB assessment area); 

(3) Osmonson and others (2011) summarized the third assessment area and presented results on geology and coal resources 

in the Southwestern Powder River Basin assessment area 

(SWPRB assessment area); and (4) Haacke and others (2013) 

summarized the fourth assessment area and presented results 

on geology, coal resources, and reserves for the Montana 

Powder River Basin assessment area (MTPRB assessment 

area). The fifth area (East Gillette coal field extension) extends 

east from the Gillette coal field and was evaluated for this 

report specifically to provide a more comprehensive mapping of coal beds below the Wyodak-Anderson coal zone 

and to complete the assessment of the entire PRB. The 

Gillette coal field was assessed first, followed in order by the 

NWPRB assessment area, the SWPRB assessment area, and 

the MTPRB assessment area. This report represents the final 

stage of the PRB assessment, which includes the results of 

the four regional studies and the east extension of the Gillette 

coal field. This report provides the first published maps of 

individual coal beds for the entire PRB.

Two factors critical to this accomplishment were: 

(1) completion of the correlation of coal beds stratigraphically lower than the Wyodak-Anderson coal zone, including 

additional data entry in the east Gillette coal field extension 

(fig. 2) and (2) resolution of the proliferation of local bed 

names throughout the entire basin. Figure 13 illustrates the 

progressive inclusion of deeper coal beds through the four 

assessment reports. It was anticipated that minor revisions 

to coal bed correlations and names would be encountered 

between assessment areas. Correlations within the WyodakAnderson coal zone remained essentially consistent throughout each of the three Wyoming assessments; however, there 

were revisions in names for beds stratigraphically lower, 

especially from Wyoming into Montana. The discussion of 

the coal bed correlation process under the Phase two section 

of the Methodology section of this report addresses the conventions used to derive a uniform coal bed nomenclature for 

the entire PRB (fig. 13).

The data entry and correlation effort to produce this 

report represents approximately 14 man-years of work with 

more than 250,000 digital well logs and multiple onscreen 

cross sections viewed. The completed database was used to 

generate the final geologic model which included coal thickness, roof, and floor grids for each modeled coal bed.

The following sections provide a brief description of 

each assessed coal bed, including a discussion of cross sections to illustrate the regional coal geology trends, a summary 

of coal resource volumes, and perspectives on the depositional history provided by the geometry of the individual 

beds. The economic analyses for each of the assessment areas 

provides estimates of the volumes of available coal (after 

all restrictions to mining are subtracted) that are currently 

classified as reserves or potentially recoverable to a 10:1 

stripping ratio.

Coal Bed Assessment 

Coal resources were classified according to geologic 

assurances (certainty of existence) or reliability, which are 

directly dependent on the density of geologic data points 

(fig. 15). The different reliability categories are: (1) measured (0.25 mi from point of measurement); (2) indicated 

(0.250.75 mi from point of measurement); (3) inferred 

(0.75–3.0 mi from point of measurement); and (4) hypothetical (greater than 3.0 mi from point of measurement) (Wood 

and others, 1983). Supplemental to this report are the GIS 
18 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

data created using Esri ArcGIS 9.3.1 (Environmental System 

Research International, 2000) that can be used to show reliability categories in map view for all 47 coal beds, along 

with other pertinent data layers (Kinney and Scott, 2015).

Original, remaining, and available resources were calculated for all 47 coal beds in the PRB and are reported by 

reliability category (table 4), overburden category (table 5), 

ownership category (table 6), and assessment area name 

(table 7). Tables 4–7 also show tonnages for burned coal 

(clinker), mined coal, land-use restrictions, and technical 

restrictions for each coal bed.

In this report, the areal extent for overburden depth maps 

match the areal extent of the 1.0 ft (or greater) thickness isopach 

maps. The greatest depth to the top of the coal for most coal 

beds is along the axis of the basin. A typical surface mining 

sequence begins at the ground surface; therefore, the following 

descriptions of coal beds in the PRB are discussed from youngest to oldest. Seven coal beds occur in the Wasatch Formation 

(Upper Healy, Healy/Lower Ulm, Murray, Ucross, Upper Felix, 

Felix, Lower Felix); the remaining 40 beds are in the Tongue 

River Member of the Fort Union Formation (fig. 23).

Wasatch Formation Coal Beds

The Buffalo–Lake DeSmet area contains Wasatch 

Formation coal beds that have been previously evaluated for 

potential mining (fig. 12) (Osmonson and others, 2011). These 

coal beds are collectively known as the Lake DeSmet coal zone 

(fig. 13) and are estimated to be 250 ft thick (Mapel, 1959; 

Obernyer, 1978, 1980). Obernyer (1978, 1980) suggested that 

the Lake DeSmet coal zone represents the coalescing of several 

major coal beds, possibly in response to basin-margin faulting 

in Eocene time. To calculate resources for this assessment area, 

the Lake DeSmet coal zone was divided into four coal beds 

(Upper Healy, Healy/Lower Ulm, Murray, and Ucross).

Despite the fact, that the Lake DeSmet coal zone is the 

thickest known coal in the United States (Jones, 2010b), no 

significant, large-scale mining has occurred in the area. The 

largest coal resource in the Lake DeSmet coal zone is within the 

Upper Healy and Healy/Lower Ulm coal beds, which have a 

composite stripping ratio greater than 5:1, making it unfavorable 

from a mining standpoint. Land-use restrictions for Buffalo, 

Lake DeSmet, and Interstate Highway 90, negatively affect the 

availability of the coal beds for mining (fig. 19). Also, the upper 

portions of these coal beds have been burned or baked over 

much of the area (Smith and others, 1972; Glass, 1997). The 

extent of the resulting clinker can be seen in figure 7. Finally, 

the coal quality in the Lake DeSmet coal zone is significantly 

inferior to coal quality currently being produced from the PRB, 

which would pose a competitive disadvantage for developing 

these resources (Luppens, 2011; Osmonson and others, 2011).

Upper Healy and Healy/Lower Ulm Coal Beds

The Upper Healy is the uppermost (youngest) coal bed 

in the Wasatch Formation and is areally limited to the westcentral part of the Wyoming PRB (fig. 24). This bed is the 

uppermost bed that composes the Lake DeSmet coal zone of 

Obernyer (1978, 1980). The Upper Healy, which was identified on 186 geophysical well logs, has a maximum thickness 

of 77 ft and averages 12 ft (fig. 23). Of the 6.9 BST of original 

resource, about 5.3 BST are considered as available resources 

(tables 4–7). Depth to the top of the coal bed ranges from 

shallow subcrop along the eastern extent of the bed to about 

1,000 ft along the western extent of the bed. About 98 percent 

of the available resource is at a depth less than 500 ft (fig. 25, 

table 5). Of these available resources, about 69 percent of the 

coal mineral estate is owned by the Federal government (table 6).

The Healy/Lower Ulm coal bed identified in this assessment correlates to the Healy coal bed of Mapel (1959). This 

bed has approximately the same areal extent as the Upper 

Healy coal bed and is known as the Healy in the Lake DeSmet 

area and the Lower Ulm in the central part of the Wyoming 

PRB (fig. 26). Both areal extents are defined by outcrop and 

clinker. More than 50 percent of the area of coal bed thickness 

exceeds 20 ft with one small area of thickness more than 40 ft. 

The bed, which was identified on 658 geophysical well logs, 

has a maximum thickness of 83 ft and an average thickness 

of 14 ft (fig. 23). Of the 13.0 BST of original resource, about 

10.7 BST are considered as available resources (tables 4–7). 

Depth to the top of the coal bed ranges from shallow subcrop 

along the eastern extent of the bed to about 1,000 ft along the 

western extent of the bed. About 87 percent of the available 

resource is at a depth less than 500 ft (fig. 27, table 5). Of 

these available resources, about 65 percent of the coal mineral 

estate is owned by the Federal government (table 6).

Murray Coal Bed

The Murray coal bed was correlated in this report with 

the Murray coal bed of Mapel (1959) and is present only in 

the west-central Wyoming PRB (fig. 28). The coal bed has 

approximately the same areal extent as both the Healy/Lower 

Ulm and Upper Healy coal beds. Identified on 785 geophysical well logs, the Murray has a maximum thickness of 14 ft 

and an average thickness of 3 ft (fig. 23). Of the 2.7 BST of 

original resource, about 0.6 BST are considered as available 

resources (tables 4–7). Depth to the top of the coal bed ranges 

from shallow subcrop along the eastern extent of the bed, 

to about 1,000 ft along the western extent of the bed. About 

62 percent of the available resource is at a depth less than 

500 ft (fig. 29, table 5). Of these available resources, about 

63 percent of the coal mineral estate is owned by the Federal 

government (table 6).

Ucross Coal Bed

Equivalent to the Ucross coal bed of Mapel (1959), this 

bed is the lowest coal bed in the Lake DeSmet coal zone and 

is limited to the west-central Wyoming PRB (figs. 13 and 30). 

As seen in the isopach maps of the Upper Healy/Lower Ulm, 

Healy, Murray, and Ucross coal beds, (figs. 24, 26, 28, and 

30) the areal extent of all four beds is similar. The Ucross was 

identified on 591 geophysical well logs, has a maximum thickness of 40 ft, and an average thickness of 7 ft (fig. 23). Of the 
Methodology 19

6.8 BST of original resource, about 4.5 BST are considered 

as available resources (tables 4–7). Depth to the top of the 

coal bed ranges from shallow subcrop along the eastern extent 

of the bed, to about 1,500 ft along the western extent of the 

bed. About 34 percent of the available resource is at a depth 

less than 500 ft (fig. 31, table 5). Of those available resources, 

about 53 percent of the coal mineral estate is owned by the 

Federal government (table 6).

Upper Felix, Felix, and Lower Felix Coal Beds

The Upper Felix coal bed is an upper split of the Felix 

coal bed and is geographically limited to the central Wyoming 

PRB (fig. 32). This coal bed, which was identified on 1,989 

geophysical well logs, has a maximum thickness of 19 ft 

and an average thickness of 4 ft (fig. 23). Of the 2.1 BST of 

original resource, about 1.2 BST are considered as available 

resources (tables 4–7). Depth to the top of the coal bed ranges 

from shallow subcrop along the eastern extent of the bed, 

to about 1,000 ft along the western extent of the bed. About 

95 percent of the available resource is at a depth less than 

500 ft (fig. 33, table 5). Of those available resources, about 

94 percent of the coal mineral estate is owned by the Federal 

government (table 6).

The Felix coal bed has a larger areal extent than the Upper 

Felix and is limited to the central Wyoming PRB (fig. 34). The 

coal bed, identified in 4,444 geophysical well logs, has an 

average thickness of 12 ft and a maximum thickness of 55 ft 

(fig. 23). Of the 18.8 BST of original resource, about 16.8 BST 

are considered as available resources (tables 4–7). Depth to 

the top of the coal bed ranges from shallow subcrop along 

the eastern extent of the bed, to about 1,500 ft where the coal 

bed is thickest; about 85 percent of the available resource is 

at a depth less than 500 ft (fig. 35, table 5). Of those available resources, about 93 percent of the coal mineral estate is 

owned by the Federal government (table 6).

The Lower Felix is the lowest coal bed identified in the 

Wasatch Formation and is present in two large areas in the 

central and northwestern Wyoming PRB (fig. 36). Identified on 

4,109 geophysical well logs, this bed has an average thickness 

of 7 ft and a maximum thickness of 53 ft (fig. 23) along the 

western margin of the Wyoming PRB. Of the 19.4 BST of original resource, about 14.9 BST are considered available resources 

(tables 4–7). Depth to the top of the coal bed ranges from 

shallow subcrop along the eastern extent of the bed, to about 

2,000 ft along the axis of the basin; about 23 percent of the 

available resource is at a depth less than 500 ft (fig. 37, table 5). 

Of the total available resource, about 69 percent of the coal mineral estate is owned by the Federal government (table 6).

Available coal resources in the Wasatch Formation coal 

beds (Upper Healy, Healy/Lower Ulm, Murray, Ucross, Upper 

Felix, Felix, and Lower Felix) in the PRB total about 54 BST 

(tables 4–7). Of the total available coal resource, about 

75 percent of the coal mineral estate is owned by the Federal 

government. Available coal resources less than 500 ft in depth 

total about 64 percent (tables 4–7).

Fort Union Formation Coal Beds

Although coal beds can be present in all three members 

of the Fort Union Formation, minable beds in the PRB are 

limited to the Tongue River Member (fig. 5). Forty coal beds 

occur within this formation with some attaining a thickness 

of over 200 ft (fig. 23). Coal beds exposed at the surface in 

the PRB are progressively older in the northern part of the 

basin because of the south-dipping structure of the Montana 

PRB, combined with a decrease in topography. The Fort Union 

Formation contains some of the thickest and most extensive 

deposits of subbituminous coal in the world (Molnia and 

Pierce, 1992). Most of this coal is in the Wyodak-Anderson 

coal zone in the Gillette coal field in the Wyoming PRB 

(Flores and others, 1999). Generally, coal beds below the 

Wyodak-Anderson coal zone that are present in the Montana 

PRB tend to be thinner and more discontinuous, with the 

exception of the Pawnee, Rosebud/Knobloch, and FlowersGoodale beds (fig. 23). 

Roland (Upper Rider), Roland (Lower Rider), Roland (Baker), 

and Roland (Taff) Coal Beds

The Roland (Upper Rider) coal bed is an upper split 

of the Roland (Baker, 1929) bed and is present in the central 

and northern Wyoming PRB, where it reaches a maximum 

thickness of 32 ft (figs. 23 and 38). The bed, which was 

identified on 5,710 geophysical well logs, has an average 

thickness of 4 ft (fig. 23). Although most of this bed is less 

than 10 ft thick, it is significant because it marks the contact 

between the Wasatch and Fort Union Formations. Of the 

13.5 BST of original resource, about 8.3 BST are considered as available resources (tables 4–7). Depth to the top of 

the coal bed ranges from shallow subcrop along the eastern 

extent of the bed, to about 2,000 ft along the axis of the 

basin. Only about 30 percent of the available resource is at 

a depth less than 500 ft (fig. 39, table 5). Of the total available resource, about 90 percent of the coal mineral estate is 

owned by the Federal government (table 6).

Identified on 1,619 geophysical well logs, the Roland 

(Lower Rider) bed has a maximum thickness of 20 ft and an 

average thickness of 4 ft (fig. 23). Although less continuous 

extent than the Roland (Upper Rider), it is present in several 

small areas in the central and northwestern Wyoming PRB 

(fig. 40). Of the 3.3 BST of original resource, about 1.7 BST 

are considered as available resources (tables 4–7). Depth to 

the top of the coal bed ranges from shallow subcrop along 

the eastern extent of the bed, to about 2,000 ft along the axis 

of the basin; only about 7 percent of the available resource is 

at a depth less than 500 ft (fig. 41, table 5). Of the total available resource, about 87 percent of the coal mineral estate is 

owned by the Federal government (table 6).

For this assessment, the Roland of Baker (1929) is 

referred to as the Roland (Baker) coal bed. The bed was 

identified in 9,987 drill holes, has a maximum thickness of 

40 ft, and averages 10 ft thick (fig. 23). The coal bed is present 

in a large area in the central and northwest Wyoming PRB 
20 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

extending into the Montana PRB near the Decker and Spring 

Creek Mines (figs. 12 and 42). It crops out to the north and 

east and thickens to the northwest. The largest coal resource 

is in the northwestern part of the Wyoming PRB, where 

it attains a thickness of 40 ft. Of the 47.8 BST of original 

resource, about 43.3 BST are considered as available resources 

(tables 4–7). Depth to the top of the coal bed ranges from 

shallow subcrop along the eastern extent of the bed, to about 

2,000 ft south of the Decker and Spring Creek Mines; about 

35 percent of the available resource is at a depth less than 

500 ft (fig. 43, table 5). Of the total available resource, about 

83 percent of the coal mineral estate is owned by the Federal 

government (table 6). The Roland (Baker) was included for 

the economic analysis to determine the coal reserve base.

The Roland of Taff (1909) is the oldest bed of the Roland 

coal bed sequence. Hereafter the Roland of Taff (1909) will be 

referred to as the Roland (Taff) coal bed. The areal extent of 

the Roland (Taff) is limited to the northwest Wyoming PRB, 

extending into the southwest Montana PRB (fig. 44). This 

coal bed was identified in 953 geophysical well logs, has an 

average thickness of 3 ft and a maximum thickness of 27 ft 

(fig. 23). One small area along the western extent of the bed 

contains coal that exceeds a thickness of 20 ft. Of the 3.4 BST 

of original resource, about 1.3 BST are considered as available 

resources (tables 4–7). Depth to the top of the coal bed ranges 

from shallow subcrop along the eastern extent of the bed, to 

about 1,500 ft over the areas of the thickest areas the coal bed; 

about 52 percent of the available resource is at a depth less 

than 500 ft (fig. 45, table 5). Of the total available resource, 

about 78 percent of the coal mineral estate is owned by the 

Federal government (table 6).

Upper Smith and Smith Coal Beds

For this assessment, the Upper Smith, Smith, Anderson 

Upper Rider, Anderson Lower Rider, Anderson, Lower 

Anderson, Dietz 1, Dietz 2, Dietz 3, Dietz 4, Upper Canyon, 

Canyon, Lower Canyon, Upper Ferry, Ferry, and Werner/Cook 

coal beds constitute the Wyodak-Anderson coal zone (figs. 13 

and 23). The Upper Smith is stratigraphically the uppermost 

bed in the Wyodak-Anderson coal zone. The Upper Smith 

bed is present in small areas in the southwestern part of the 

Wyoming PRB and in the southwestern part of the Montana 

PRB (fig. 46). This coal bed was identified on 326 geophysical 

well logs, has a maximum thickness of 36 ft, and an average 

thickness of 3 ft (fig. 23). This coal attains a thickness of about 

20 ft in a small area near the abandoned Dave Johnston Mine 

(fig. 12). Of the 1.0 BST of original resource, about 0.4 BST 

are considered as available resources (tables 4–7). Depth to 

the top of the coal bed ranges from shallow subcrop along the 

eastern extent of the bed, to about 2,500 ft along the axis of the 

basin; about 46 percent of the available resource is at a depth 

less than 500 ft (fig. 47, table 5). Of the total available resource, 

about 81 percent of the coal mineral estate is owned by the 

Federal government (table 6).

The Upper Smith coal bed has approximately the same 

areal extent as the Roland (Baker) bed (fig. 42) in the western 

one-half of the Wyoming PRB, extending into the southwestern 

part of the Montana PRB near the Decker and Spring Creek 

Mines (figs. 12 and 48). The limits of the bed gradually thin 

and eventually pinch out. To the northwest, interburden between 

the Smith and the Anderson becomes very thin; however, the 

Smith does not merge with the Anderson in any drill holes. The 

bed thickens dramatically west of Wright, Wyoming, towards 

the center of the basin where it is locally referred to as the 

“Big George” coal bed (fig. 8). Jones (2010a) also verified that 

the Smith and Anderson do not merge by showing an angular 

relation between the Roland coal beds (Baker and Taff) and the 

lower Wyodak Rider coal zone (Smith Rider and Smith/Big 

George coal beds).

The largest coal resource in the Smith bed occurs in the 

central to southern part of the extent of the coal bed, where 

the bed attains a thickness of over 200 ft (fig. 48). The Smith 

coal bed, as interpreted from 9,334 drill holes, has a maximum 

thickness of 278 ft, and averages 24 ft thick (fig. 23). Of the 

126.4 BST of original resource, about 122.9 BST are considered 

as available resources (tables 4–7). Depth to the top of the bed 

ranges from shallow subcrop along the eastern extent of the bed, 

to about 2,500 ft along the axis of the basin (fig. 49); only about 

4 percent of the available resource is at a depth less than 500 ft 

making the strip ratio of coal to rock undesirable for surface 

mining. Therefore, despite the thickness of the Smith coal bed, 

most of the resource would be considered too deep for surface 

mining, but is a potential resource for future underground mining. Of the total available resource, about 88 percent of the coal 

mineral estate is owned by the Federal government (table 6). 

The Smith bed was included in the economic analysis to determine the coal reserve base.

Anderson Upper Rider, Anderson Lower Rider, Anderson, 

and Lower Anderson Coal Beds

The Anderson Upper Rider bed is the uppermost of two 

splits above the Anderson coal bed and is present only in 

small, isolated areas in the central part of the Wyoming PRB 

(figs. 23 and 50). This coal bed was identified in 343 drill 

holes, has an average thickness of 3 ft, and a maximum thickness of 18 ft (fig. 23). Of the 0.3 BST of original resource, 

about 0.04 BST are considered as available resources 

(tables 4–7). Depth to the top of the coal bed ranges from 

shallow subcrop along the eastern extent, to about 1,500 ft 

over the thickest portion of the coal bed; about 59 percent of 

the available resource is at a depth less than 500 ft (fig. 51, 

table 5). Of the total available resource, about 71 percent of 

the coal mineral estate is owned by the Federal government 

(table 6). The Anderson Upper Rider was included in the economic analysis to determine the coal reserve base.

The Anderson Lower Rider bed is the lower of two splits 

above the Anderson coal bed. This coal bed was identified 

in 480 drill holes, has a maximum thickness of 20 ft, and 
Methodology 21

averages 8 ft thick (fig. 23). The coal bed is only present in 

one small area in the south-central Wyoming PRB (fig. 52). 

Of the 0.8 BST of original resource, about 0.5 BST are considered as available resources (tables 4–7). Depth to the top 

of the coal bed ranges from shallow subcrop along the eastern 

extent of the bed, to about 3,000 ft over the thickest portion of 

the coal bed; about 96 percent of the available resource is at a 

depth less than 500 ft (fig. 53, table 5). Of the total available 

resource, about 94 percent of the coal mineral estate is owned 

by the Federal government (table 6).

The Anderson is the principal minable coal bed in the 

Wyodak-Anderson coal zone in the Gillette coal field and also 

a principal CBM production target coal bed in the Wyoming 

PRB. The bed is present in much of the Wyoming PRB and 

extends into the Decker and Spring Creek Mine areas in the 

southwest Montana PRB (figs. 12 and 54). A large area of 

thin coal separates the bed into two thick pod-like areas in 

the northwestern part of the Wyoming PRB (about T. 56 N., 

R. 78 W.) (fig. 54). A channel area in T. 46 N., R. 70 W. bisects 

the thickest part of the Anderson bed where the bed thins or 

is absent. The Anderson, Dietz 2, and Dietz 3 coal beds are 

presently mined at the Decker and Spring Creek Mines in the 

Montana PRB (fig. 12).

The Anderson coal bed was first correlated by Baker 

(1929) as the Dietz 1 bed. It was also referred to as the Dietz 

1 by the Pittsburg and Midway Coal Mining Company in 

the PSO lease area in the Sheridan coal field (figs. 2 and 

12). However, the Anderson and the Dietz 1 are correlated 

as separate beds for this report. Identified in 11,774 drill 

holes, the Anderson bed has an average thickness of 24 ft, 

and a maximum thickness of 225 ft near the Jacobs Ranch 

Mine (figs. 12 and 23). The Anderson bed crops out to the 

east and defines the eastern boundary of the Gillette coal 

field (Luppens and others, 2008). Of the 125.5 BST of 

original resource, about 101.8 BST is considered as available resources (tables 4–7). Depth to the top of the coal bed 

ranges from shallow subcrop along the eastern extent of the 

bed, to about 2,000 ft near the axis of the basin; about 40 percent of the available resource is at a depth less than 500 ft 

(fig. 55, table 5). The available resource percentage doubles 

to 89 percent for depths less than 1,000 ft. Of the total available resource, about 89 percent of the coal mineral estate is 

owned by the Federal government (table 6). The Anderson 

was included in the economic analysis to determine the coal 

reserve base.

The Lower Anderson bed splits from the base of the 

Anderson coal bed. It is interpreted from 883 drill holes, 

has a maximum thickness of 44 ft and an average thickness 

of 4 ft (fig. 23). The coal bed is present in the north-central 

Wyoming PRB as small isolated areas extending into the 

south-central Montana PRB (fig. 56). Of the 3.4 BST of 

original resource, about 2.0 BST are considered as available 

resources (tables 4–7). Depth to the top of the coal bed ranges 

from shallow subcrop along the eastern extent of the bed, to 

about 2,000 ft near the axis of the basin; about 42 percent of 

the available resource is at a depth less than 500 ft (fig. 57, 

table 5). Of the total available resource, about 90 percent of 

the coal mineral estate is owned by the Federal government 

(table 6).

Dietz 1, Dietz 2, Dietz 3, and Dietz 4 Coal Beds

The Dietz 1 coal bed was identified on 672 geophysical 

well logs, has a maximum thickness of 29 ft, and averages 4 ft 

thick (fig. 23). Dietz 1 coal thickness greater than 20 ft is limited 

to a small area in the northwest Wyoming PRB and small areas 

in the southwest Montana PRB (fig. 58). Of the 1.1 BST of 

original resource, only about 0.5 BST are considered as available resources (tables 4–7). Depth of the Dietz 1 coal bed ranges 

from shallow subcrop along the eastern extent of the bed, to 

about 2,500 ft along the axis of the basin (fig. 59, table 5).

Identified in 930 drill holes, the Dietz 2 coal bed has a 

maximum thickness of 37 ft, and averages 6 ft thick (fig. 23). 

It is present in a small area in the Decker and Spring Creek 

Mines (fig. 12) in the Montana PRB, where it is mined along 

with the Dietz 3 (fig. 60). The Dietz 2 is also present in a small 

area in the north-central part of the Wyoming PRB. Of the 

3.0 BST of original resource, about 2.0 BST are considered as 

available resources (tables 4–7). The Dietz 2 coal bed ranges 

in depth from shallow subcrop along the eastern extent of the 

bed, to more than 1,500 ft near the Decker and Spring Creek 

Mines (fig. 61, table 5). The Dietz 2 was included in the economic analysis to determine the coal reserve base.

The Dietz 3 coal bed is the thickest and most areally 

extensive of the Dietz coal beds. Interpreted from 4,816 drill 

holes, the Dietz 3 has a maximum thickness of 119 ft and an 

average thickness of 13 ft (fig. 23). The bed is present in two 

distinct areas; one near the Decker and Spring Creek Mines 

in the Montana PRB, where it exceeds a thickness of more 

than 40 ft, and the other in the north-central Wyoming PRB, 

where the bed attains a thickness of about 119 ft (fig. 62). Both 

northeast-trending and northwest-trending channels can be 

defined by observing where the bed thins and disappears, thus 

separating the bed into several pod-like areas. The combined 

Smith, Anderson, and Dietz 3 coal beds formed the most 

significant minable sequence of coals in the Decker and Spring 

Creek Mines (fig. 12). The Dietz 3 bed is a primary minable 

coal bed for the PSO lease area of Pittsburg and Midway 

Coal Mining Company (fig. 12). Of the 50.9 BST of original 

resource, about 45.1 BST are considered as available resources 

(tables 4–7). Of the total available resource, about 85 percent 

of the coal mineral estate is owned by the Federal government 

(table 6). Depth ranges from shallow subcrop along the eastern 

extent of the bed, to about 3,000 ft near the axis of the basin; 

about 29 percent of the available resource is at a depth less 

than 500 ft (fig. 63, table 5). The Dietz 3 was included in the 

economic analysis to determine the coal reserve base.

The Dietz 4 coal bed is present in relatively small, 

isolated areas in the northwest part of the Wyoming PRB and 

in the area surrounding the Decker and Spring Creek Mines 

(fig. 12) in the Montana PRB (fig. 64). This bed was identified 
22 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

on 624 geophysical well logs, reaches a maximum thickness 

of 20 ft and has an average thickness of 3 ft (fig. 23). Of the 

1.8 BST of original resource, about 0.8 BST are considered 

as available resources (tables 4–7). Depth ranges from shallow subcrop along the eastern extent of the bed, to more than 

3,000 ft along the axis of the basin (fig. 65, table 5).

Upper Canyon/Cox, Canyon, and Lower Canyon Coal Beds

The Upper Canyon coal bed is an upper split of the 

Canyon coal bed and correlates to the Cox coal bed identified 

by Haacke and others (2013) in the Montana PRB. Figure 66 

shows that the subsurface extent is limited mostly to one large 

area in the west-central Wyoming PRB and small, isolated 

areas are in the south-central Montana PRB. The coal bed 

was identified on 725 geophysical well logs, has a maximum 

thickness of 31 ft, and averages 7 ft thick (fig. 23). Of the 

6.0 BST of original resource, about 4.7 BST (86 percent) 

are considered as available resources and about 4.0 BST has 

Federal mineral ownership (tables 4–7). Depth of the coal bed 

ranges from shallow subcrop along the eastern extent of the 

bed, to more than 3,000 ft along the axis of the basin (fig. 67, 

table 5).

The Canyon coal bed, originally named the Monarch in 

1909, is equivalent to the Canyon coal bed of Baker (1929) 

(Law and others, 1979). Since 1929, it has been referred to 

as both the Canyon and the Monarch. The coal bed is present 

in much of the Wyoming PRB, extending northward into the 

southwest Montana PRB (fig. 68). The Canyon, along with 

the Anderson, is one of the principal CBM production targets 

in the Gillette coal field in the Wyoming PRB. Where the 

Anderson bed exceeds 60 ft thick in the Gillette coal field is 

where the Anderson and Canyon beds are a single thick bed 

(fig. 54).

The Canyon bed was identified in 9,353 drill holes and 

reaches a maximum thickness of 183 ft, with an average thickness of 21 ft (fig. 23). Of the 147.4 BST of original resource, 

about 135.4 BST are considered as available resources 

(tables 4–7). Of the total available resource, about 89 percent 

(120.3 BST) of the coal mineral estate is owned by the Federal 

government (table 6). Depth from the top of the coal bed 

ranges from shallow subcrop along the eastern extent of the 

bed to more than 3,000 ft along the axis of the (fig. 69). About 

19 percent of the available coal resource is at a depth of less 

than 500 ft (table 5). For the economic analysis, the Canyon 

was used in determining reserves.

The Lower Canyon coal bed is a lower split of the 

Canyon coal bed. It was identified in 4,374 drill holes, has a 

maximum thickness of 85 ft, and averages 11 ft thick (fig. 23). 

The coal bed is present in a large area in the west-central 

Wyoming PRB and extends into the Decker and Spring Creek 

Mine area in the Montana PRB (fig. 70). About 52.0 BST of 

the 59.5 BST of original resource are considered as available 

resources (tables 4–7). Only about 12 percent of the available 

coal resource is at a depth less than 500 ft (fig. 71, table 5). 

Of the total available resource, about 83 percent (44.8 BST) 

of the coal mineral estate is owned by the Federal government 

(table 6). Depth ranges from shallow subcrop to more than 

3,000 ft near along the axis of the basin (fig. 71). The Lower 

Canyon bed was included in the economic analysis to determine the coal reserve base.

Upper Ferry and Ferry Coal Beds

The Upper Ferry bed is an upper split of the Ferry 

coal bed and is present in a small area in the north-central 

Wyoming PRB (fig. 72). Based on 145 drill holes, it reaches 

a maximum thickness of 10 ft and has an average thickness 

of 4 ft (fig. 23). About 0.5 BST of the 0.8 BST of original 

resource are considered as available resources (tables 4–7). 

Depth to the top of the coal bed ranges from shallow subcrop to more than 1,500 ft near the center of the basin; about 

0.1 percent of the available coal resource is at a depth less than 

500 ft (fig. 73, table 5). 

 The Ferry coal bed was identified in 744 drill holes and 

is limited in areal extent to the northwest part of the Wyoming 

PRB and the southwest Montana PRB (fig. 74). The bed has a 

maximum thickness of 28 ft and an average thickness of 5 ft 

(fig. 23). About 4.3 BST of the 6.4 BST of original resource 

are considered as available resources (tables 4–7). Of the total 

available resource, about 84 percent (3.4 BST) of the coal 

mineral estate is owned by the Federal government (table 6). 

Depth to the top of the coal bed ranges from shallow subcrop 

along the eastern extent of the bed, to more than 3,000 ft along 

the axis of the (fig. 75). About 16 percent of the available coal 

resource is at a depth less than 500 ft (table 5).

Werner/Cook Coal Bed

The Werner/Cook bed, identified in 4,459 drill holes, 

has a maximum thickness of 90 ft and averages 13 ft thick 

(fig. 23). This is the oldest coal bed in the Wyodak-Anderson 

coal zone and is present in much of the Wyoming PRB, 

extending five townships northward into the Montana PRB 

(fig. 76). The Werner/Cook bed is known as the Werner coal 

bed in the Wyoming PRB and is equivalent to the Cook coal 

bed of Montana. The thickest part of the coal bed is present 

north of the Decker and Spring Creek Mines in the Montana 

PRB, where it exceeds a thickness of 60 ft. About 63.3 BST 

of the approximately 74 BST of original resource are considered as available resources (tables 4–7). Of the total available 

resource, about 88 percent (55.7 BST) of the coal mineral 

estate is owned by the Federal government (table 6). Depth 

to the top of the coal bed ranges from shallow subcrop along 

the eastern extent of the bed, to about 2,500 ft along the axis 

of the basin (fig. 77). About 26 percent of the available coal 

resource is at a depth of less than 500 ft (table 5). The Werner/

Cook was included in the economic analysis to determine the 

coal reserve base.

Upper Otter and Otter Coal Beds

The Upper Otter bed is an upper split of the Otter coal 

bed and is present in small, isolated areas in the north-central 

Wyoming PRB (fig. 78). Based on 328 drill holes, it reaches a 
Methodology 23

maximum thickness of 21 ft and has an average thickness 

of 4 ft (fig. 23). About 0.6 BST of the 0.9 BST of original 

resource are considered as available resources (tables 4–7). 

Of the total available resource, about 84 percent (0.5 BST) of 

the coal mineral estate is owned by the Federal government 

(table 6). Depth to the top of the coal bed ranges from shallow 

subcrop along the eastern extent of the bed, to about 2,500 ft 

along the axis of the basin (fig. 79). About 0.6 percent of the 

available coal resource is at a depth less than 500 ft (table 5).

Distribution of the Otter coal bed is shown in figure 

80. Based on 3,642 drill holes, the bed reaches a maximum 

thickness of 170 ft and has an average thickness of 14 ft 

(fig. 23). Areas of greatest thickness occur in the center of the 

Wyoming PRB where the depth to the top of the bed is more 

than 1,500 ft. The Otter crops out along its northern extent and 

thins and eventually pinches out to the south and east. About 

64.3 BST of the 71.0 BST of original resource are considered 

as available resources (tables 4–7). Of the total available 

resource, about 90 percent (58.0 BST) of the coal mineral 

estate is owned by the Federal government (table 6). Depth to 

the top of the coal bed ranges from shallow subcrop along the 

eastern extent of the bed, to about 2,500 ft along the axis of 

the basin (fig. 81). Only about 5.5 percent of the available coal 

resource is at a depth less than 500 ft (table 5).

Gates/Wall Coal Bed

Known as the Gates bed in Wyoming and the Wall bed 

in Montana, this bed is present in a large area in the central 

and northern Wyoming PRB, extending into the southwestern 

Montana PRB (fig. 82). The Gates/Wall crops out along its 

northern extent and thins and pinches out to the south and 

east. Identified in 3,412 drill holes, the coal has a maximum 

thickness of 125 ft, and averages 9 ft thick (fig. 23). About 

57.9 BST of the 66.4 BST of original resource are considered 

as available resources (tables 4–7). Of the total available 

resource, about 86 percent (49.8 BST) of the coal mineral 

estate is owned by the Federal government (table 6). The top 

of the coal bed ranges from shallow subcrop along the eastern 

extent of the bed, to more than 3,000 ft along the axis of the 

basin (fig. 83). About 8 percent of the available coal resource 

is at a depth less than 500 ft (table 5).

Pawnee Coal Bed

The Pawnee coal bed is present in the northern Wyoming 

PRB and extends into the southern one-half of the Montana 

PRB (fig. 84). The Pawnee crops out along its northern extent 

and thins and pinches out to the south and east. The coal bed 

was identified in 1,368 drill holes, has a maximum thickness 

of 34 ft, and averages 7 ft thick (fig. 23). About 17.0 BST of 

the 24.5 BST of original resource are considered as available 

resources (tables 4–7). Of the total available resource, about 

85 percent (14.5 BST) of the coal mineral estate is owned 

by the Federal government (table 6). Depth to the top of the 

coal ranges from shallow subcrop along the eastern extent 

of the bed, to more than 3,000 ft near the axis of the basin. 

About 30 percent of the available coal resource is at a depth 

less than 500 ft (fig. 85, table 5). In the Montana PRB there is 

significant area of thick coal less than 500 ft in depth, which 

is potentially surface minable (fig. 85). 

Brewster-Arnold Coal Bed

The Brewster-Arnold coal bed, identified in 110 drill 

holes, has a maximum thickness of 19 ft and averages 5 ft 

thick (fig. 23). This coal bed is present mostly in the central Montana PRB and small isolated areas in the Wyoming 

PRB (fig. 86). About 0.5 BST of the approximate 2.0 BST 

of original resources are considered as available resources 

(tables 4–7). Of the total available resource, about 0.3 BST 

of the coal mineral estate is owned by the Federal government 

(table 6). Depth to the top of the coal ranges from shallow subcrop along the eastern extent of the bed, to more than 1,500 ft 

along the axis of the basin (fig. 87, table 5).

Odell Coal Bed

Identified in 1,052 drill holes, the Odell bed is present 

in the northern Wyoming PRB and extends into the southern 

Montana PRB (fig. 88). The bed has a maximum thickness 

of 26 ft, and averages 4 ft thick (fig. 23). Of the 11.7 BST of 

original resource, about 6.6 BST are considered as available 

resources (tables 4–7). Of the total available resource, about 

85 percent (5.7 BST) of the coal mineral estate is owned by the 

Federal government (table 6). Depth to the top of the coal ranges 

from shallow subcrop along the eastern extent of the bed, to 

more than 3,000 ft along the axis of the basin (fig. 89, table 5).

Cache Coal Bed

The Cache bed is present primarily in the southern 

Montana PRB (fig. 90). The bed, which was identified on 

247 drill holes, reaches a maximum thickness of 26 ft, and 

has an average thickness of 3 ft (fig. 23). Of the 3.3 BST of 

original resource, about 0.8 BST are considered as available 

resources (tables 4–7). Of the total available resource, about 

0.7 BST of the coal mineral estate is owned by the Federal 

government (table 6). Depth to the top of the coal ranges from 

shallow subcrop along the eastern extent of the bed, to more 

than 2,000 ft along the axis of the basin (fig. 91, table 5).

A Zone Coal Bed

The A Zone bed is correlated in several drill holes in a 

cross section by McLellan and others (1990) and is present 

only in small isolated areas in the Montana PRB (fig. 92). The 

bed, identified in 24 drill holes, has a maximum thickness of 

9 ft and averages 3 ft thick (fig. 23). Of the 0.1 BST of original 

resource, about 0.01 BST are considered as available resources 

(tables 4–7). Depth ranges from shallow subcrop along the 

eastern extent of the bed, to about 1,000 ft along the axis of 

the (fig. 93, table 5).
24 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Upper Rosebud and Rosebud/Knobloch Coal Beds

Identified in 44 drill holes, the Upper Rosebud is an 

upper split of the Rosebud/Knobloch coal bed and is present in 

a small area near the Absaloka Mine (fig. 12) in the Montana 

PRB (fig. 94). The Upper Rosebud is referred to as the S1 coal 

bed by the Westmoreland Resources, Inc. Mining Company 

(J. Speake, Jr., Westmoreland Resources, Inc., oral commun., 

2010). The bed has a maximum thickness of 15 ft and averages 3 ft thick (fig. 23). Of the 0.2 BST of original resource, 

about 0.05 BST are considered as available (tables 4–7). 

Depth to the top of the bed ranges from shallow subcrop along 

the eastern extent of the bed, to about 1,000 ft along the axis 

of the basin (fig. 95, table 5).

The Rosebud/Knobloch coal bed is one of the thickest 

minable coal beds in the Montana PRB. The bed is known 

as the Rosebud west of Rosebud Creek and as the Knobloch 

east of Rosebud Creek (fig. 96) (Haacke and others, 2013). 

The Rosebud/Knobloch is equivalent to the Deep 1 coal bed 

in the SWPRB (Osmonson and others, 2011) and correlates 

to the Rosebud coal bed of Roberts and others (1999c) and 

the Sawyer coal bed of McLellan and others (1990). Near 

the town of Ashland, the Rosebud/Knobloch correlates to 

the Calvert and the McKay/Nance coal beds of Roberts 

and others, (1999a). This coal is mined in the Rosebud and 

Absaloka Mines and was also mined at the abandoned Big 

Sky Mine (fig. 12).

Identified in 2,203 drill holes, the coal bed has a maximum thickness of 73 ft, and averages 12 ft thick (fig. 23). 

Some of the thickest coal is located under the Custer National 

Forest (fig. 19). This bed is the minable bed target for the Otter 

Creek lease area (fig. 12). In the Montana PRB, the Rosebud/

Knobloch crops out along Otter Creek and pinches out to the 

east and west. About 47.1 BST of the 64.4 BST of original 

resource are considered as available resources (tables 4–7). 

Of the total available resource, about 80 percent (37.4 BST) 

of the coal mineral estate is owned by the Federal government 

(table 6). Depth to the top of the coal bed ranges from shallow 

subcrop along the eastern extent of the bed, to about 1,500 ft 

in the Montana PRB and about 4,000 ft along the axis of the 

basin in the Wyoming PRB. About 27 percent of the available 

coal resource is at a depth less than 500 ft (fig. 97, table 5). 

The Rosebud/Knobloch was included in the economic analysis 

to determine the coal reserve base.

Calvert Coal Bed

Present only in the Montana PRB, the Calvert coal bed 

was identified in 86 drill holes, has a maximum thickness 

of 18 ft and averages 3 ft thick (fig. 23). Near the town of 

Ashland (fig. 1) the bed is part of the base of the Rosebud/

Knobloch (fig. 98) (Roberts and others, 1999a). About 0.2 BST 

of the 1.2 BST of original resource are considered as available resources (tables 4–7). Depth to the top of the coal ranges 

from shallow subcrop along the eastern extent of the bed, to 

about 2,000 ft deep along the axis of the basin (fig. 99, table 5).

McKay/Nance and Lower McKay Coal Beds

The McKay/Nance coal bed is a lower split of the 

Rosebud/Knobloch coal bed. The thickest portion of the 

Rosebud/Knobloch coal bed east and south of the town of 

Ashland (figs. 1 and 96) reflects the area where the Rosebud/

Knobloch and McKay/Nance coal beds form a single bed. 

The McKay/Nance coal bed splits off the Rosebud/Knobloch 

coal bed peripherally from the thickest area of the Rosebud/

Knobloch coal bed (fig. 100). This split results in a corresponding thinning of the Rosebud/Knobloch coal bed in all 

directions. In the Montana PRB, the McKay/Nance coal bed is 

known as the McKay coal bed west of Rosebud Creek and the 

Nance coal bed east of Rosebud Creek (Roberts and others, 

1999c). The bed is present in both the Rosebud and Absaloka 

Mines, and the abandoned Big Sky Mine areas (figs. 12 and 

100). The McKay/Nance crops out along its northern extent 

and thins to the east, south and west (fig. 100).

The coal bed is also present throughout the Wyoming 

PRB, but at considerably greater depth. The McKay/Nance 

coal bed is equivalent to the Deep 2 coal bed identified in the 

SWPRB (Osmonson and others, 2011). The coal bed was 

identified in 2,499 drill holes, has a maximum thickness of 

36 ft, and averages 5 ft thick (fig. 23). Of the 33.3 BST of 

original resource, about 22.6 BST are considered as available 

resources (tables 4–7). Of the total available resource, about 

78 percent (17.7 BST) of the coal mineral estate is owned by 

the Federal government (table 6). Because of a topographic 

high (Little Wolf Mountains) (fig. 101), depth to the coal bed 

ranges from shallow subcrop along the eastern extent of the 

bed, to more than 2,000 ft between the Absaloka and Rosebud 

Mines (figs. 12 and 101). About 20 percent of the available 

coal resource is at a depth less than 500 ft (fig. 101, table 5). 

The Lower McKay bed, identified in 63 drill holes, has 

a maximum thickness of 7 ft and averages 3 ft (fig. 23). The 

coal bed is present only in small areas near the Absaloka Mine 

in the Montana PRB (figs. 12 and 102). The Lower McKay 

is also referred to as the S2 coal bed by Westmoreland 

Resources, Inc. (J. Speake, Jr., Westmoreland Resources, 

Inc., oral commun., 2010). Of the 0.2 BST of original 

resource, about 0.01 BST are considered as available resources 

(tables 4–7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 

1,500 ft (fig. 103, table 5).

Flowers-Goodale Coal Bed

The areal extent of the Flowers-Goodale is present 

in both the Montana and Wyoming PRB assessment areas 

(fig. 104). In the Montana PRB, the Flowers-Goodale bed 

crops out along the northern and eastern limits of its extent. 

Several lenticular pods of the bed are present in the central 

Wyoming PRB. In Wyoming, this bed is equivalent to the 

Deep 3 coal bed (Osmonson and others, 2011).

Identified in 2,752 drill holes, this bed occurs in a 

large area in the southern one-half of the Montana PRB and 

throughout the central part of the Wyoming PRB (fig. 104). 
Methodology 25

The bed has a maximum thickness of 40 ft and averages 8 ft 

thick (fig. 23). Of the 60.5 BST of original resource, about 

51.0 BST are considered as available resources (tables 4–7). 

Of the total available resource, about 85 percent (43.4 BST) 

of the coal mineral estate is owned by the Federal government 

(table 6). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 

3,000 ft in depth near the axis of the basin. About 12 percent 

of the available coal resource is at a depth less than 500 ft 

(fig. 105, table 5). The Flowers-Goodale was included in the 

economic analysis to determine the coal reserve base.

Upper Witham and Robinson/Witham Coal Beds

The Upper Witham coal bed has limited areal extent and is 

present only in the Montana PRB near the abandoned Big Sky 

Mine (fig. 106). Identified in 150 drill holes, the bed reaches a 

maximum thickness of 29 ft and has an average thickness of 4 ft 

(fig. 23). Of the 0.1 BST of original resource, about 0.07 BST 

are considered as available resources (tables 4–7). Depth to 

the top of the coal bed ranges from shallow subcrop along the 

eastern extent of the bed, to about 500 ft near the abandoned Big 

Sky Mine (figs. 12 and 107, table 5).

The Robinson/Witham is known as the Robinson coal 

bed west of Rosebud Creek and as the Witham coal bed east of 

Rosebud Creek in the Montana PRB (fig. 108). The bed crops 

out north of the Rosebud Mine (fig. 12), was identified in 

1,491 drill holes, has a maximum thickness of 41 ft, and averages 7 ft thick (fig. 23). The bed is also found in a large area in 

the west-central part of the Wyoming PRB and correlates with 

the Robinson coal bed of Roberts and others (1999c). Of the 

approximate 20.7 BST of original resource, about 15.0 BST 

are considered as available resources (tables 4–7). Of the total 

available resource, about 65 percent (9.9 BST) of the coal 

mineral estate is owned by the Federal government (table 6). 

Because of a topographic high (Little Wolf Mountains) 

(fig. 108), depth to the top of the coal bed ranges from shallow subcrop to more than 3,000 ft between the Absaloka and 

Rosebud Mines (fig. 12). About 30 percent of the available 

coal resource is at a depth less than 500 ft (fig. 109, table 5).

Roberts/Terret Coal Bed

The Roberts/Terret coal bed, identified in 1,768 drill 

holes, is present throughout much of the central part of both 

the Montana and Wyoming PRB (fig. 110). This bed correlates with the Roberts coal bed in Wyoming (Molnia and 

Pierce, 1992) and in the NWPRB assessment area of Scott and 

others (2010). The bed reaches a maximum thickness of 42 ft, 

and averages 8 ft thick (fig. 23). Of the 51.9 BST of original 

resource, about 44.5 BST are considered as available resources 

(tables 4–7). Of the total available resource, about 84 percent 

(37.1 BST) of the coal mineral estate is owned by the Federal 

government (table 6). Depth to the top of the Roberts/Terret 

coal bed ranges from shallow subcrop along the eastern extent 

of the bed, to more than 4,000 ft near the axis of the basin 

(table 5, fig. 111).

Burley Coal Bed

Identified in 50 drill holes, the Burley coal bed is present 

in two small areas in the Montana PRB and one isolated area 

in the Wyoming PRB. The largest area in the Montana PRB is 

near the Otter Lease, the other is south of the Rosebud Mine 

(figs. 12 and 112). The bed has a maximum thickness of 10 ft 

and averages 3 ft thick (fig. 23). Of the 1.6 BST of original 

resource, about 0.7 BST are considered as available resources 

(tables 4–7). The depth to the top of the coal bed ranges from 

shallow subcrop along the eastern extent of the bed, to more 

than 2,000 ft along the axis of the basin (fig. 113, table 5).

Upper Stag and Lower Stag Coal Beds

The Stag coal bed is correlated in several drill holes in a 

cross section in McLellan (1991). The name was expanded in 

this report to include an Upper and Lower Stag for correlating 

two minor coal beds. The Upper Stag bed is limited in areal 

extent to the northern Wyoming PRB extending into the southern Montana PRB (fig. 114). The bed, which was identified 

on 91 well logs, reaches a maximum thickness of 13 ft, and 

has an average thickness of 3 ft (fig. 23). Of the approximate 

1.9 BST of original resource, about 0.8 BST are considered 

as available resources (tables 4–7). Depth to the top of the 

coal bed ranges from shallow subcrop along the eastern extent 

of the bed, to more than 3,000 ft along the axis of the basin 

(fig. 115, table 5).

The Lower Stag bed is present in small, isolated areas 

in the southern Montana PRB (fig. 116); this bed is the lowest 

(oldest) coal bed evaluated in the PRB. The bed, which was 

identified on 8 well logs, reaches a maximum thickness of 6 ft 

and has an average thickness of 3 ft (fig. 23). Of the 0.2 BST 

of original resource, about 0.01 BST are considered as available resources (tables 4–7). Depth to the top of the coal bed 

ranges from shallow subcrop to more than 2,000 ft along the 

axis of the basin (fig. 117, table 5).

Coal Bed Cross Sections

Three cross sections (figs. 8–10) illustrate some of the 

more important features of the coal bed geometry in the PRB. 

The west-east, dip-oriented section labeled A–A' (fig. 8) illustrates the stratigraphic relation between the thick Anderson/

Canyon beds in the Gillette coal field to the thick Smith bed 

in the SWPRB area and the rapid splitting and thinning of the 

coal beds towards the western edge of the basin. In response 

to the Bighorn Mountains uplift along the western margin 

of the basin, several northeast-trending faults developed and 

terminated the coal beds from cropping out along the western 

margin of the basin (Ellis and Colton, 1994). Previous studies 

(Molnia and Pierce, 1992; Flores and others, 2010) correlated 

the Anderson/Canyon beds with the Smith coal bed; however, 

the large volume of new data for the current assessment provided sufficient control to confirm that these two coal beds are 

not equivalent (Luppens and others, 2008; figs. 16 and 17). A 

comparison of the Anderson bed isopach maps from the 2002 
26 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

and 2008 coal assessments (Ellis and others, 2002; Luppens 

and others, 2008) illustrate the substantial differences in coal 

bed correlations afforded by the abundance of additional data.

This revised interpretation is supported by several other 

recent studies. Ashley (2005) and Jones (2010b) have both 

correlated the Anderson/Canyon and the Smith (Big George) 

as separate coal beds. Cross section C–C′ from Jones (2010b) 

is remarkably similar the A–A′ cross section in this report 

(fig. 8). The revisions of the thick coal bed correlations within 

the Wyodak-Anderson coal zone have several ramifications. 

Rather than the Anderson and Smith beds (Big George) being 

a single continuous, thick bed as shown in figure 17, there is 

an interval in figure 8 where the Smith, Anderson, and Canyon 

coal beds are all relatively thin. The new correlations effectively result in a downdip, geological barrier to westward 

advances of surface mining of the thick Anderson/Canyon 

beds in the Gillette coal field (Luppens and others, 2008).

Several other important features of coal bed geometry 

in the PRB can also be observed in these three cross sections 

(figs. 8–10). The west-east, dip-oriented section B–B′ (fig. 9) 

through the northern portion of the NWPRB assessment area 

illustrates both the asymmetric nature of the basin and the 

thickening of the Wyodak-Anderson coal zone northward 

relative to the A–A′ cross section (fig. 8) through the Gillette 

coal field and SWPRB assessment area. In addition to the 

thickening of the Wyodak-Anderson coal zone, the thick coal 

beds in the Gillette coal field and the SWPRB assessment area 

split farther northward. Thinner coal beds spread over a larger 

stratigraphic interval and present a different set of mining 

conditions than currently found in the Gillette coal field where 

the thick, relatively shallow Anderson and Canyon beds are 

currently mined.

The northwest-southeast, strike-oriented section C–C′ 

(fig. 10) demonstrates the splitting and thinning of the thick 

Anderson and Canyon coal beds and an overall increase in 

thickness in the Wyodak-Anderson coal zone northward from 

the Gillette coal field into the NWPRB and MTPRB assessment areas. The Wyodak-Anderson coal zone is limited to the 

southernmost portion of the MTPRB where these beds crop 

out. Locally, thicker parts of coal beds below the WyodakAnderson coal zone (Rosebud/Knobloch, Flowers-Goodale, 

and Pawnee) crop out farther to the north.

Another important factor in the coal bed geometry is 

that any differences in the hydrochemistry of produced water 

may be explained by the updated correlations described in this 

report. For example, the Anderson (Big George) was previously assumed to be the same thick coal bed; however, in 

this assessment it was determined that the Anderson and the 

Big George are separate thick coal beds (Luppens and others, 

2008) (figs. 8, 17, and 18). 

In-Place Coal Resource Volumetrics

Calculation of coal resource volumetrics first requires 

converting the surface topography and coal thickness, roof, 

and floor grids for each coal bed from the final PRB geological 

model to ASCII grids. Using ArcView (Environmental 

Systems Research Institute, 2006), USGS in-house GIS 

resource allocation planning (RAP) scripts were developed to 

apply the appropriate density value to the coal thickness grids 

to calculate the tonnage of coal contained within each assessed 

area. Finally, additional RAP scripts were used to apply the 

original, remaining, and available coal tonnages to the grids 

of coal ownership, reliability categories, depth to coal, and 

assessment areas to create an even more detailed analysis of 

the assessment area’s coal resources. Original coal resources 

were calculated for all coal beds at least 2.5 ft thick and with 

no restrictions applied. Remaining resources were calculated 

using the volume of the original resource minus the volume 

of coal that had been mined. Land-use environmental) and 

technical restrictions were then calculated and subtracted from 

the remaining resource to determine available resources.

A total of 47 coal beds were identified during this final 

assessment. With no restrictions applied, the total original 

resource for these 47 beds was calculated to be about 

1.16 trillion short tons (TST) (fig. 23, tables 4–7). Available 

coal resources, which are part of the original coal resource 

after subtracting restrictions to mining and areas of burned 

coal, were calculated to be 975 BST. Restrictions included 

railroads, Federal Interstate highways, urban areas, alluvial 

valley floors, State parks, national forests, and mined 

coal areas.

Figure 118 provides the amount and percent of original coal resources for 12 significant coal beds with about 

50 BST resources or greater. Of these 12 beds, 6 are within 

the Wyodak-Anderson coal zone (Smith, Anderson, Dietz 

3, Canyon, Lower Canyon, and Werner/Cook). Collectively, 

the Wyodak-Anderson coal zones represent 50 percent of the 

total original in-place resources. The 12 major coal beds total 

about 81 percent of the original resources with the remaining 35 assessed beds totaling about 19 percent of the original 

resources. These 12 beds offer the most potential for recoverable coal resources. The total coal resource number of 1.16 TST 

is about 0.09 TST greater than the sum of 1.07 TST of original 

resources of the four assessment areas (Scott and Luppens, 

2013). The inclusion of deeper coal beds below the WyodakAnderson coal zone for this report, especially in the Gillette 

coal field, East Gillette coal field extension, and NWPRB 

assessment areas, accounted for the increase in this final inplace resource estimate.

Tables 4–7 provide resource summaries based on reliability, overburden thickness, coal ownership, and assessment area 

categories. Table 8 presents the summary results of tables 4–7 

to facilitate comparisons of the different coal resource categorizations. About 6.5 BST of the original resource was estimated 

to be burned (clinker) and 6.4 BST was previously mined, leaving a remaining resource of about 1.15 TST. Approximately 

174 BST (15 percent) of the original resource is affected by 

restrictions (mined coal, too thin, land use, and technical). 

Subtraction of these restrictions from the 1.15 TST leaves 

about 975 BST (84 percent) of the original resource available 

for potential development in the PRB (tables 4–7). The same 

set of coal resource summaries are included in each of the four 
Methodology 27

PRB area assessments if more detailed information is needed 

(Luppens and others, 2008, Scott and others, 2010, Osmonson 

and others, 2011, Haacke and others, 2013).

Coal resources for the 47 assessed coal beds are 

reported by reliability categories in tables 4, 8, and 9. The 

resources were classified according to geologic assurance 

of existence or reliability, which are dependent on the density 

of geologic data points. The different reliability categories—

measured (0.25 mi from point of measurement); indicated 

(0.25–0.75 mi from point of measurement); inferred 

(0.75–3.0 mi from point of measurement); and hypothetcal 

(greater than 3.0 mi from point of measurement)—were 

established on the basis of distance from a data point (Wood 

and others, 1983). 

About 76 percent of the original resources for all assessed 

beds can be classified as measured or indicated (table 9). 

About 99 percent of the original resources are in the measured, 

indicated, or inferred categories (table 9). This reflects a much 

higher relative degree of confidence than previous studies as 

a result of the substantial amount of new data incorporated 

into this assessment. Table 9 compares PRB resources in Ellis 

and others (1999) with resources in this assessment as well 

as a comparison of the total resources and reliability categorizes. The resources in the measured and indicated categories 

increased from 38 to 78 percent with a corresponding threefold decrease in the inferred and hypothetical categories 

from the 1999 assessment to the current assessment. It is 

interesting to note that the difference between the total estimated resource volumes for the two PRB assessments of the 

Wyodak-Anderson coal zone (table 9) was only about 16 BST. 

Thus, reasonable total coal resources can be estimated with 

less data using a net thickness isopach for a coal zone. However, more data were needed to confidently correlate the 

individual coal beds given the complex coal geology within 

the PRB if estimates of recoverable coal are required. An 

example of this revised coal bed correlation is shown in 

figures 16 and 17. Although the net total resources for the area 

represented in the two figures are similar, figure 17 represents 

a significantly different stratigraphic and mining economics 

scenario than figure 16.

Coal resources for the 47 assessed coal beds are reported 

by overburden depth categories in tables 5 and 8. Nearly 

90 percent of the available resources are less than 2,000 ft in 

depth. Only 22 percent of the resources are less from 0 to 

500 ft in depth, which is the interval where most of the current 

coal resources in the reserves category would be expected.

Coal resources for the 47 assessed coal beds are reported 

by ownership categories in tables 6 and 8. Eighty-six percent 

of the available coal resources are under Federal coal ownership for the greater PRB. South of T. 4 S. in Montana, the 

Federal coal ownership exceeds 90 percent (fig. 20). North 

of T. 4 S. in Montana, Federal coal ownership is less than 

50 percent in most townships.

In July 1864, the Northern Pacific Railroad was chartered 

(Malone and others, 1991) and the U.S. Government used a 

portion of the public domain (Federally owned land) to assist 

and encourage the building of transcontinental railroads. This 

land was granted in alternate sections, creating a checkerboard 

pattern, within an area lying 40 mi on either side of the proposed Northern Pacific Railroad right of way (fig. 20).

Coal resources for the 47 assessed coal beds are reported 

by assessment area in tables 7 and 8. Of the four assessment 

areas, the MTPRB assessment area contains the least amount 

of available resources. The dominant Wyodak-Anderson 

coal zone is limited to the southernmost four townships in 

Montana. Coal beds in the Wyodak-Anderson coal zone are 

much thinner in Montana relative to those beds in the Gillette 

coal field and SWPRB assessment area. The Werner/Cook 

bed, at the base of the Wyodak/Anderson coal zone, crops 

out in the southern one-half of Big Horn and Powder River 

Counties (fig. 76). 

Perspectives on Environments of Deposition

The primary goal of this assessment was to quantify and 

evaluate coal resources in the Powder River Basin. However, 

it is difficult to assess the coal beds in the PRB without speculating on the depositional history of such thick, extensive coal 

beds. Mapping of individual beds for the first time throughout the entire PRB was required to complete the economic 

assessment of in-place as well as recoverable coal resources. 

The correlation of the discrete coal beds in this assessment 

offers more information than simply the coal bed isopach 

maps needed for the coal resource inventory. The individual 

bed maps also enable the generation of interburden isopach 

maps between adjacent coal beds which provides the ability 

to investigate patterns of clastic deposition between periods 

of peat accumulation. The purpose of this section was not 

to revise depositional models, but to review several theories 

and to briefly discuss how the results of this assessment may 

provide new perspectives regarding depositional environments 

of the extraordinary PRB coal province.

Several depositional models have been proposed to 

explain the origin of the thick coal beds in the PRB. These 

models attribute the development of accommodation and the 

nature of coal splitting (parting geometry) to sedimentary 

processes (differential compaction, channel switching, and 

crevasse splay deposits) within specific depositional environments (raised mires, deltas, and basinwide wetlands) (Jones, 

2010a). Most of these models are based on peat-to-coal 

compaction ratios ranging from 3:1 to 20:1 (3–20 ft of peat 

compacts to form 1.0 ft of coal). Jones (2010a), however, 

proposes that sequence stratigraphy of coal beds and basement-related structural effects explain the origin of these thick 

coal deposits.

Flores and others (1999) proposed that the coal in the 

Fort Union Formation formed from peats that accumulated 

in swamps of northeast flowing fluvial systems. The sediments that formed these rocks were deposited in channels, 

overbank floodplains, floodplain lakes, and crevasse channel 

splays drained by meandering, anastomosing, and braided 

streams. Thick, low-ash, low-sulfur coal beds of the Tongue 

River Member formed in raised swamps that developed in 
28 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

interfluvial environments and on abandoned stream deposits. 

The regional paleogeographic patterns of the merged coal 

zones appear to be affected by peat deposition on noncompactable, sandstone-dominated, alluvial-belt deposits superimposed on paleotectonic platforms. The lateral migration, 

avulsion, and abandonment of these platforms resulted in 

random distribution of the merged coal bodies (Flores and 

others, 2010). Several of these channel systems were mapped 

in the Gillette coal field by Luppens and others (2008). Some 

channel locations can be seen on the drill hole location map 

(fig. 15) as areas of less dense drilling, because of relatively 

thin or absent coal beds in these channel areas. Examination 

of geophysical logs delineated a major basin-axis channel 

system. This channel system extends northward from T. 40 N., 

R. 73 W. (fig. 15). A relatively narrow, east-west trending 

channel can also be seen by the lack of drilling from T. 46 N., 

R. 71 W., west about three townships until it intersects the 

north-south channel system on the west side of the Gillette 

coal field (fig. 15).

Ayers (1986b) proposed a fluvial deltaic model where 

sediments filled the basin, primarily from the eastern margin, 

in a series of northeast southwest-trending delta systems with 

thick coal beds forming in an interdeltaic setting. Ayers and 

Kaiser (1984) stated that there is no evidence for a basin-axis 

fluvial system, as suggested by previous research (Flores, 

1982), as sand percentages are lowest along the axis of the 

basin. However, using geophysical logs, Luppens and others 

(2008) defined a channel system parallel to the basin axis. 

Furthermore, the split line between the Canyon and Anderson 

beds, especially in the south portion of the Gillette coal field, 

is also oriented to the basin axis with the split thickening 

westward. This basin-axis fluvial system and associated split 

geometry is perpendicular to the deltaic sand body framework 

geometry which trends northeast southwest (Ayers, 1986b).

An important factor regarding the deltaic models is the 

concept of peat compaction (Jones, 2010a). The raised mires 

model and the interdeltaic wetlands model both need tremendous amounts of accommodation to allow for great thicknesses 

of peat to accumulate. These models are based on the concept 

of peat-to-coal compaction ratios, wherein a given amount of 

peat is compressed to form a given thickness of coal.

An alternate hypothesis has been proposed to explain 

the genesis of the thick PRB coal sequences, based on 

chronostratigraphic correlation (sequence stratigraphy) of 

coal beds, basement-related structural effect on differential 

development of accommodation within the basin, and the 

coalification process (not compaction) (Jones, 2010a). Recurrent movement along postulated basement faults resulted 

in stacked organic deposits, alternating organic and clastic 

deposits, and heterogeneous clastic deposits. Subtle changes 

in surface topography resulting from structural movement of 

these basement blocks disrupt the process of peat accumulation by changing the water table, shifting fluvial systems, and 

affecting the stabilization of shorelines.

Jones (2010a) provides evidence that the thick PRB coal 

deposits are not a result of organics that accumulated in single, 

long-lived, stable wetlands; rather, these coal deposits are 

composed of numerous, stratigraphically adjacent coal beds 

that developed intermittently between periods of organic 

accumulation and periods of nondeposition and weathering. 

A key to this depositional concept is the coalification process. As peat accumulates, it undergoes progressive aerobic 

to anaerobic bacterial decay with depth. The end product 

of this bacterial reduction of accumulated plant material is 

a dark brown to black, semi-amorphous, organic-rich gel, 

known as gytta. During periods of subaerial exposure, the 

layer of partially decomposed peat is readily oxidized and 

prone to erosion when dried and thus, is often not preserved. 

Data that support subaerial exposure of the gytta include thin

paleosols such as fusain layers (discrete horizons of oxidized 

coal), evaporate minerals (for example gypsum and anhydrite), and variable ash content of the coal above and below 

the thin oxidized surfaces. The bottom and top of these 

paleosols mark periods between different depositional facies, 

and the spacing of these chronostratigraphic surfaces (time 

lines) represents equal amounts of time. These time lines 

are important because they indicate that thick coal deposits 

did not form from a singularly thick deposit of peat, but that 

thick coal deposits actually formed from numerous, stacked, 

thinner accumulations of gytta. The thickness of a coal bed 

generally corresponds to the final cumulative thickness of 

the relatively incompressible gytta layers. The heat-driven 

process (thermogenesis) converts the gytta to various grades 

of coal (Jones, 2010a). 

A lineament-based depositional model is summarized 

in figures A and B contained in a report by Jones (2010a). In 

this model, organic accumulation in a lower energy wetland 

environment supported subaqueous reducing conditions. 

Subsequent development of differential accommodation 

because of fault reactivation of basement blocks occurred 

along split lines. A period of high energy, localized clastic deposition occurred in the downthrown blocks, while 

topographically higher blocks were subjected to subaerial 

exposure and oxidation of the gytta surface. Repetition of 

the differential development of the accommodation process resulted in the unique geometry of coal deposits in the 

Tongue River Member of the Fort Union Formation in the 

PRB (fig. B in Jones, 2010a).

To test this model, several individual coal bed isopach 

maps, a combined isopach map of the major Wyodak-Anderson 

zone beds (Canyon, Anderson, and Smith), and an isopach 

of the interburden between the Anderson and Canyon coal 

beds were examined to see if there is a relation between coal 

thickness trends and lineament orientation trends in the basin. 

The isopach maps for the Flowers-Goodale and Roberts/Terret 

coal beds and superimposed lineaments are shown in figures 119 and 120. Interburden between these two beds ranges 

from about 125 to 200 in thickness. Flores (2010) States that 

the thicker (merged) coal bodies are randomly distributed. 
Surface Coal Resource Assessment 29

However, several of the thicker areas of coal in both beds 

overlie each other. They are generally bounded by the northwest-trending Buffalo/Douglas, Lightning Creek, and Black 

Butte lineaments, and the southwest-trending Casper/Bill, 

Fiddler Creek, South Coyote Creek, and Rozet lineaments, 

suggesting some structural effect.

The isopach map of the Smith, Anderson, and Canyon 

coal beds, with superimposed lineaments, is shown in figure 121. The thickness distribution appears to be controlled 

by the northwest-trending Buffalo/Douglas, Lightning Creek, 

and Black Butte lineaments, and the southwest-trending 

Fiddler Creek, Rozet, Tensleep/Harding, and Big Horn/Custer 

lineaments, which again suggests some structural influence. 

There also seems to be structural control affecting areas of 

little or no coal accumulation or “want areas” (Flores, 2010). 

This want area, bounded by the southwest-trending Tensleep/

Harding and Big Horn/Custer lineaments (fig. 121), coincides 

with the marked thickening of the Wyodak-Anderson coal 

zone interval, as well as the splitting and thinning of the coal 

beds within that zone just south of the Montana State line.

By mapping individual coal beds rather than net coal 

isopachs, the generation of interburden isopachs can be 

accomplished by subtracting the roof elevation grid of a lower 

bed from the floor elevation grid of an upper bed. When a coal 

bed splits, the net thickness of the two splits may be similar to 

the unsplit coal bed. Therefore, relying on net coal isopachs 

may mask the split line orientation of the parting between the 

two coal beds. Interburden isopachs can define the parting 

geometry. The interburden isopach between the Anderson and 

Canyon beds in the Gillette coal field (Luppens and others, 

2008) and the superimposed lineaments is shown in figure 122. 

The parting orientation in the southern portion of the coal field 

is parallel to the northwest-trending Lightning Creek lineament. The parting split line in the northern part of the coal 

field coincides with the Rozet lineament. The east-west parting 

in the central part of the coal field (T. 46 N. and T. 47 N.) is 

a fluvial channel system that splits the merged coal bed. This 

channel system is parallel to the Sussex/Osage lineament 

(fig. 122). Flores (2010) stated that this east-west “want” area 

was not parallel to lineament trends. However, that appraisal 

was based on a net coal isopach map with less data control 

than the current assessment, which precluded definitive orientation of the channel system.

Surface Coal Resource Assessment

The objective of the USGS Coal Assessment Project is 

to refine the Nation’s coal resource estimates and conduct the 

systematic determination of the coal reserve base on a regional 

basis in the major coal provinces in the Nation. The final 

and most important step in the coal assessment process is to 

derive estimates of that portion of in-place resources that can 

currently be classified as reserves and those resources that are 

potentially recoverable based on economic analyses. Regional 

estimates of coal reserves can provide energy planners a more 

meaningful appraisal of the amount of coal that is potentially 

recoverable in the foreseeable future. Therefore, the development of a regional mining economics model for each of the 

four assessment areas is essential to accomplish the goals of 

the PRB coal assessment. 

Surface Mine Modeling

Developing regional mine models is challenging because 

there are significant differences in the coal geology between 

the Gillette coal field (Luppens and others, 2008) and the other 

assessment areas within the PRB, which can appreciably affect 

the economic analysis. Mine engineering practices must be 

adapted to specific geologic conditions. Therefore, the mine 

modeling methodology was customized for each of the four 

PRB assessment areas. Despite geologic variations between 

assessment areas, a common methodology was followed 

(fig. 14). Replicating all assessment methodologies in this 

report would be impractical, but the individual PRB assessment reports include specific mine modeling details (Luppens 

and others, 2008; Scott and others, 2010; Osmonson and 

others, 2011; Haacke and others, 2013).

The USGS developed both surface and underground 

regional mine models for the assessment areas because there 

are significant areas within the PRB that are underlain by 

thick, deep, coal beds that are not amenable to surface mining recovery. Although no coal in the PRB is currently nor is 

anticipated to be recovered by underground mining in the foreseeable future, it was determined that for a holistic assessment 

of the coal resources in the PRB, underground mining should 

be evaluated at least on a preliminary basis.

Geologic Aspects of Surface Mine 

Model Development

Bed thickness is one of the most important factors affecting coal recoverability; thin coal beds may be unrecoverable. 

There is a significant inverse relationship between bed thickness and the mining disturbance area (Luppens and others, 

2009). A 4-ft bituminous coal bed requires 22.1 mi2

 for a 

100 million-ton resource block, whereas a 50-ft bed requires 

only 1.8 mi2. Clearly, it would be preferable to recover the 

thickest coal bed. However, coal bed thickness is not the only 

important criterion affecting coal recoverability.

The depth of a coal bed also affects coal recovery economics, especially for surface minable resources. The most 

important cost component in surface mining is the expense 

of removing the volume of rock above a minable coal bed 

(overburden) (Luppens and others, 2009). The cost of surface 

coal mining increases with increased depth because of the 

greater volume of material that needs to be removed per unit 

of coal. The relation between coal bed depth and thickness is 
30 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

referred to as the stripping ratio, which is the most significant 

economic factor in the evaluation of surface mining potential 

(Luppens and others, 2009). This ratio represents the volume 

of rock both above and within (parting) coal beds expressed 

by the number of cubic yards that must be mined to obtain one 

ton of coal. Although not an exact conversion, the stripping 

ratio can be estimated by dividing the thickness of the rock 

above the coal bed by the coal thickness. For example, given 

a 10-ft-thick coal bed and a 50-ft-thick bed, both at 100 ft 

depth, the approximate stripping ratios would be 10:1 and 

2:1, respectively. Therefore, for the 2:1 stripping ratio area 

only 2 cubic yards (yd3

) of rock would have to be removed per 

ton of coal produced, compared to 10 yd3 for the 10:1 area. 

Obviously, the 2:1 ratio area would have a significant production cost advantage. It is the combination of extensive, thick, 

relatively low stripping ratio resources, coupled with relatively 

low-sulfur and low-ash content in the PRB that has stimulated 

the rapid development in this region during the past 40 years. 

A maximum stripping ratio of 10:1 was used for the economic 

analyses. While a stripping ratio of 10:1 is higher than current 

(October 2014) average mining conditions in the PRB (typically less than 4:1 or less ratio), mining to 10:1 stripping ratios 

have been reported elsewhere in the United States (Schobert, 

1995; Kaiser, 1999).

Modeling Stratigraphic Sequence 

for Surface Mining

The first step in conducting a mining economic evaluation is deciding which coal beds to include in the mine 

models and then parsing out the coal resources by composite 

stripping-ratio increments. The criteria used to select coal 

beds for the mine models were depth, thickness, and areal 

extent. Generally, only beds with an areal extent of at least 

several townships, thicknesses 5.0 ft or greater, and depths 

less than 500 ft were evaluated. The minimum thickness of 

5.0 ft (Bureau of Land Management, 1986) and the maximum incremental stripping ratio of 4:1 criteria for beds 

below the Anderson or Canyon were selected on the basis 

of current mining practices in the Gillette coal field (Luppens 

and others, 2008). Subsequent to bed selection for the mining 

economic evaluation, a composite stripping-ratio map was 

generated and the recoverable coal resources for each stripping increment from 1:1 to 10:1 were calculated.

For the Gillette coal field assessment, the exceptionally thick Anderson and Canyon bed sequence dominated 

the economic evaluation. These two coal beds are generally 

close to each other stratigraphically with little or no separation by parting material. The Roland and Smith coal beds 

stratigraphically above the Anderson and Canyon beds were 

also included in the Gillette coal field mine models. No coal 

beds below the Canyon bed were economically assessed. The 

Anderson and Canyon beds accounted for about 82 percent 

of the total recoverable coal resources in the Gillette coal 

field (Luppens and others, 2008). Additionally, this thick coal 

interval represented more than 90 percent of the resources 

to the 6:1–7:1 stripping-ratio interval. Use of the USGS 

CoalVal program (Rohrbacher and McIntosh, 2010), which 

aggregates all coal beds into a single composited bed mine 

model provided an appropriate regional mine model for the 

Gillette coal field.

In the northern portion of the Gillette coal field, the Anderson and Canyon beds begin to separate and thin significantly to 

the north and northwest into the NWPRB assessment area continuing into the MTPRB assessment area. Similarly, the Canyon 

bed separates into the Canyon and Lower Canyon beds in these 

directions. Typically, mining costs are higher for the recovery 

of multiple beds as opposed to a single bed scenario, which was 

used in the Gillette coal field assessment. To address the mining 

conditions in the NWPRB and MTPRB assessment areas, a 

new surface mine model program was developed to evaluate 

multibed sequences, rather than the CoalVal program used for 

the Gillette coal field assessment (Scott and others, 2010). For 

the NWPRB assessment area, DCF mining costs were as much 

as $6/ton higher than the costs for the same stripping ratio increment for the Gillette coal field (Luppens and others, 2008).

The same methodology to parse out coal resources by 

composite stripping ratio increments in the Gillette coal field 

assessment (Luppens and others, 2008) was used for the 

NWPRB assessment area. However, with more beds having 

thinner average thicknesses throughout a larger stratigraphic 

interval, the approach to the coal reserve evaluation model 

for the NWPRB assessment area had to be modified. The 

Roland (Baker), Smith, Anderson, Dietz 3, Canyon, Lower 

Canyon, and Werner beds were selected for the economic 

evaluation. However, not all beds are present everywhere 

in the NWPRB, further complicating the development of a 

regional mine model for this area. This is especially true for 

lower stripping ratios. For example, in the 2:1 ratio areas, 

some areas contain the Werner and Lower Canyon or Lower 

Canyon and Canyon, or other bed combinations. For stripping ratios of 5:1 or greater, five or six of these assessed beds 

are typically present. Interburden thicknesses between the 

beds are also variable. Developing a single regional model 

with bed and interburden variability represented a challenge. 

A straightforward modeling approach was needed that still 

addressed the multibed situations in this area.

The regional mine models for the Wyodak-Anderson 

coal zone for the NWPRB and MTPRB assessment areas 

were formulated on a representative model-bed section 

based on approximate average thicknesses for the coal beds 

and average interburden intervals assessed for reserves. An 

example of a regional mine model stratigraphic sequence 

used for the economic evaluation of the NWPRB assessment area is shown in table 10. All strata in this model are 

assumed to be near horizontal. One coal bed is modeled 

at the 1:1 ratio, and additional coal beds are added from 

the 2:1 through 4:1 ratios. Because the coal beds in lower 
Surface Coal Resource Assessment 31

ratio models are highly variable, the coal beds are labeled 

beds 1–4, rather than using specific bed names. For the 5:1 

through 10:1 stripping ratios, six coal beds are modeled 

(table 10). To simplify the models, interburden thicknesses 

remain constant and overburden is increased for the 5:1–10:1 

ratio models. Although the mine model used is a simplification of the actual conditions, this approach still provided 

a more realistic representation than the single-bed model 

scenario used in the Gillette coal field assessment (Luppens 

and others, 2008).

Active coal mining in Montana occurs in two stratigraphic zones (Haacke and others, 2013). Coal mines near 

Decker, Montana, (figs. 2 and 12) are recovering coal from 

the upper Wyodak-Anderson coal zone (Anderson to the 

Dietz 3 beds) (fig. 13). For the MTPRB assessment area, 

a representative regional model was developed based on 

approximate average thicknesses of five coal beds (Roland 

(Baker), Smith, Anderson, Dietz 2, and Dietz 3) (Haacke and 

others, 2013). The first coal bed was modeled at the 1:1 stripping ratio; additional coal beds were added for stripping ratios 

from 2:1 through 4:1. To simplify the models, interburden 

thicknesses remained relatively constant and overburden was 

increased for the 5:1–10:1 stripping ratio models.

Currently, coal beds in the lower part of the WyodakAnderson coal zone are not mined in the MTPRB assessment 

area. However, there are areas where the Canyon and Werner/

Cook coal beds are relatively thick and occur at shallow depth 

with stripping ratios less than 10:1 (figs. 129 and 130). Therefore, in addition to the regional mine model sequence, single 

bed mine models of the Canyon and Werner/Cook coal beds 

were evaluated for reserve potential.

Active mining below the Wyodak-Anderson coal zone 

is unique to the MTPRB assessment area (Haacke and others, 

2013). Several mines are recovering coal from the Rosebud/

Knobloch coal bed (fig. 13) near Colstrip, Montana (figs. 2 

and 12). In addition to the Rosebud/Knobloch bed, the Pawnee 

and Flowers-Goodale coal beds locally contain thicker pods 

of coal below the Wyodak-Anderson coal zone at stripping 

ratios less than 10:1 (figs. 131–133). Therefore, single bed 

mine models of the Pawnee, Rosebud/Knobloch, and FlowersGoodale coal beds were also evaluated for reserve potential 

(Haacke and others, 2013).

For the SWPRB assessment area, a number of adverse 

geological factors were encountered. The most important 

factor was the thinning and splitting of the deep WyodakAnderson coal zone towards the southern and western flanks 

of the PRB shown on figures 8 and 9. Relatively steep dips 

(10–25°) (Flores and others, 1999) of coal beds on the western 

flank of the PRB, such as in the Sussex coal field (fig. 6), are 

also a limiting factor. Thin coal beds combined with relatively 

steep dips severely limit the potential for mining (Osmonson 

and others, 2011). 

Coal quality is an additional adverse factor in the SWPRB 

assessment area. Associated with the thinning and splitting 

of the coal beds in this area is the presence of numerous thin, 

high-ash partings within individual coal beds. These partings negatively affect coal quality by increasing ash content 

and lowering calorific values (Luppens, 2011). The potential 

for even lower grade coal quality was a factor in the decision to close the Dave Johnston Mine in 2000, the only large 

commercial mine developed in the SWPRB (fig. 12). Factors 

contributing to the mine closure were an increase in the stripping ratio, coupled with inherent adverse geologic conditions 

and deteriorating coal quality (PACIFICORP, 2008). Closure of this mine reflects the trend of decreasing coal quality 

along the shallow southern and western flanks of the SWPRB 

assessment area. 

The lack of extensive, thick, shallow coal bed exploration targets coupled with poor coal quality has resulted in a 

lack of sufficient drilling (both conventional coal exploration 

holes and coalbed methane) in this area. Additional drilling 

is necessary to adequately assess surface recoverable coal 

resources for the SWPRB assessment area on a regional basis. 

No economic analysis of surface recoverable Fort Union 

Formation coals–Roland (Baker) and Smith–was performed 

for the SWPRB assessment area.

The Wasatch Formation in the SWPRB assessment area 

locally contains thick coal beds (fig. 23), but these typically 

have higher ash and sulfur contents and lower gross calorific 

values (table 2) (Luppens, 2011; Osmonson and others, 

2011). The Lake DeSmet area in the SWPRB assessment 

area contains thick Wasatch Formation coals that have been 

commercially evaluated a number of times for potential mining. Despite the fact that the Lake DeSmet coal zone in the 

Wyoming PRB is the thickest known coal zone in the contiguous United States, no significant, large-scale mining has 

occurred in the Wasatch coal beds in the PRB.

Luppens (2011) noted that published coal quality values 

for the Lake DeSmet area (Mapel and others, 1953) were 

overly optimistic as all partings greater than 3/8 inch were 

included from the core samples prior to analysis. Furthermore, 

at least one of the cores (Bureau of Reclamation core) from 

Mapel and others (1953), experienced unaccounted moisture 

loss, which resulted in anomalously high calorific values. The 

results from the USGS-1 core hole (Mapel and others, 1953) 

were evaluated to estimate the effects on reported coal analyses using more likely moisture levels and with the estimated 

impacts of compositing the originally excluded shale, pyrite, 

and other high-ash parting material. The predicted moisture 

increased about 1.5 percent. More importantly, the predicted 

ash contents increased to a range of 12.9–15.6 percent with 

a corresponding decrease in calorific values with a range of 

6,986–6,694 Btu/lb depending on volumetric or mass weighting (table 11). The predicted quality is significantly lower than 

the original reported ash and calorific values of 5.0 percent 

and 7,970 Btu/lb, respectively (Luppens, 2011). It is suspected 

that the relatively inferior predicted coal quality may be a contributing factor to the lack of development in the area.
32 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

A surface mining reserve analysis was not performed for 

the Upper Healy or the Healy coal beds due to a combination 

of negative factors within the Lake DeSmet area including 

unfavorable stripping ratios, restrictions to mining including 

extensive areas of clinker, and predicted inferior coal quality. 

Although limited areas of these beds could possibly be mined 

in the future, this scenario was not addressed because of the 

regional scope of this assessment and the lack of sufficient 

data necessary to outline specific small areas for potential 

surface mining (Osmonson and others, 2011).

Regional Surface Mine Modeling

Once a simplified geologically based mining sequence was 

developed for an assessment area, the USGS estimated potential 

recoverable coal resources and evaluated the cost of developing 

and operating a typical coal mine. For each of the four assessment areas, a regional surface mine model was developed to 

calculate expected mining costs based on the bulk volume and 

mass excavation of overburden and coal, respectively. However, the Gillette coal field was an exception. Field mine plans 

from recently filed State mining permits and discussions with 

mine operators in the southern part of the coal field indicated 

that mining progress could be affected by the joint Burlington 

Northern Santa Fe and Union Pacific Railroad (Joint Line) 

(fig. 19) within 10–12 years (Luppens and others, 2008). In 

2006, two coal lease-by-applications (West Jacobs Ranch and 

West Hilight Field) confirmed that coal mining companies were 

planning to develop new mining pits west of the Joint Line 

(fig. 19) (Bureau of Land Management, 2013). Mining west 

of the railroad would require a deep box cut to extract the coal 

resources. The expense of this box cut would significantly affect 

the cost of mining west of the railroad, which would require a 

separate mine plan. Additionally, leaving the Joint Line intact 

produced two new restrictions to mining. One restriction 

accounted for the amount of coal resources affected beneath the 

Joint Line right-of-way, and the second estimated the amount of 

coal resources affected by the box cut development west of the 

Joint Line for overburden storage and mine facilities.

USGS regional modeling is different from evaluation of 

specific mining properties. With a single basinwide approach, 

some generalizations must be made. Certainly, customizing 

mine plans for each unique property within an assessment 

area would be better, but prohibitive in terms of time and 

manpower requirements. The regional mine models are used 

to produce a prefeasibility or conceptual level evaluation to 

determine which portion of the recoverable coal resources 

(reserves) could be economically extracted at the time of the 

determination. A conceptual economic study should have 

error limits of 30 to 50 percent (Rupprecht, 2004). The USGS 

assessment methodology is also consistent with EIA DRB 

criteria. Some USGS coal availability studies have already 

been used to update the EIA Agency coal resource and reserve 

data (U.S. EIA Agency, 1997).

The regional mine model developed for the Gillette coal 

field is a set of 10 mine models, one for each stripping ratio 

from 1:1 to 10:1. The 10:1 ratio was chosen based on geological constraints. The 10:1 stripping ratio limit in the Gillette 

coal field approximately coincides with a north-southtrending distributary channel against which the Anderson 

and Canyon coal beds thin and pinch out. This channel 

effectively poses a down dip barrier to surface mining in the 

Gillette coal field (Luppens and others, 2008). The USGS 

CoalVal program (Rohrbacher and McIntosh, 2010) was used 

to evaluate the regional mine model for the Gillette coal field 

assessment. This program combined total coal bed and burden 

thicknesses. To better address the thinner coal beds and larger 

interburden intervals for the NWPRB and MTPRB assessment 

areas, multibed regional mine models were created by USGS 

personnel using Microsoft EXCEL (2007) spreadsheets.

Both mining programs were used to calculate recoverable coal resources and capital and operating costs on a DCF 

basis. The DCF cost to produce a ton of coal is applied to all 

available coal resources within each stripping ratio increment of the ratio model. The breakeven cost is compared to 

the current (December 2013) sales price of coal on a per ton 

basis. The coal is economically minable when the DCF is less 

than the sales price and is uneconomical when the DCF cost 

is greater than the sales price.

Surface Mine Model Design Assumptions

Oral communication with existing PRB coal mining 

companies was valuable to the development of the regional 

mine models. Although many PRB mines have been in 

operation for 30 years or more, a 20-year economic life was 

used for all assessment models. Production rates were chosen 

for each assessment area based on a reasonable tonnage rate 

between the minimum and maximum yearly production rates 

for several mines within an assessment area. For the Gillette 

coal field, a production rate of 35 million short tons per year 

(MST/yr) for the regional mine model was used. A nominal 

production rate of 10 MST/yr was selected from numerous 

mine models as being most representative for mining cases 

for the NWPRB and MTPRB assessment areas.

Overburden removal for the Gillette coal field consisted of a large dragline used together with truck-shovel 

pre-stripping. This cost effective overburden removal system 

takes advantage of dragline efficiencies and the flexibility of 

the truck-shovel operation to strategically place the spoils 

near final reclamation grade. The dragline operation uses 

cast-blasting to move a portion of the overburden into its 

final location across the open pit rather than using mining 

equipment. Cast-blasting is more cost effective than moving 

the same volumes by dragline or dozers. The dragline and associated stripping dozer operation is scheduled to remove 140 ft 

of overburden directly above the Anderson coal bed. This 

schedule allows the dragline and its associated equipment 

and manning requirements to remain constant from model to 

model. As the stripping ratio increases, more equipment and 
Surface Coal Resource Assessment 33

manning requirements were added to the model. The mine 

models were designed to assume that new, optimally-sized 

equipment would be purchased and operated on a 24-hoursper-day, 7-days-per-week schedule. Except for the dragline, 

10 holidays were scheduled for all equipment operations. 

The amount of stripping equipment and coal production 

equipment was determined from truck-haulage simulations, 

shovel productivities, and reported dragline productivities at 

existing mines in the Gillette coal field (oral communication 

with various mine managers).

For the southern one-half of the Gillette coal field, where 

the Joint Line Railroad is located on available coal resources, 

a new box cut would be required to access the coal west of the 

railroad (fig. 19). This box cut is a challenge both economically 

and logistically (Luppens and others, 2008). The projected time 

required to open a box cut using truck shovel equipment could 

vary from more than one year for a 3:1 ratio box cut, to nearly 

three years for a box cut at a 9:1 ratio (Luppens and others, 

2008). Such operations would require additional equipment 

separate from the mining operations east of the Joint Line, 

which exacerbates the financial effects of the new box cut. 

During development of the new box cut, coal production would 

continue in the pits east of the Joint Line, as no coal would be 

produced during the new box cut construction. The long lead 

times necessary for box cut development presents a major timing challenge. Production in the new box cut west of the Joint 

Line must be ready to start as production east of the of the Joint 

Line finishes. When the dragline overburden removal operations 

east of the Joint Line are finished, the equipment would have to 

be moved across the railroad to begin overburden removal in 

the next cut. Back-filling the eastern pit with spoil from the box 

cut pit would not be possible, leaving an out-of-pit overburden 

dump immediately west of the Joint Line as the only feasible 

option for the box cut spoil.

Conventional truck-shovel operations were used for the 

NWPRB and MTPRB assessment area models, which facilitated more complex, multibed mining scenarios. The multibed 

model considered each bed in the stratigraphic sequence as a 

separate mining operation with the uppermost bed recovered 

before the next lower bed. A load-out capacity was calculated 

for each mining pass or bench. Equipment for overburden and 

interburden stripping and coal loading and hauling was sized 

for a 10 MST/yr mining operation. Shovel loading and rear 

dump-truck haulage were used to provide a common basis 

for the comparative modeling results produced in this assessment. Stripping shovels were sized for operating at 89 percent 

availability and 95 percent utilization for 6,300 hours per year. 

Coal-loading shovels were sized for operating at 89 percent 

availability and 85 percent utilization for 5,633 hours per year. 

These efficiencies allowed the calculated stripping volume to 

remain in advance of coal loading. Both operations were conducted on a two shift per day, 350-days-per-year basis. Stripping and coal-loading shovels have a range of 15–60 cubic 

yards in bucket capacity. Mining support equipment costs 

were included for haul-road maintenance, night illumination, 

in-pit water handling, and transportation.

In addition to the multibed model for the MTPRB assessment, single bed mine models were evaluated for five coal 

beds below the Dietz beds, including the Canyon, Werner/

Cook, Pawnee, Rosebud/Knobloch, and Flowers-Goodale coal 

beds. The same surface mining assumptions and parameters 

used for both the multibed and single-bed models. The singlebed models were comparatively simple as the logistics for 

the overburden stripping operations for multiple beds are 

more complex.

All coal beds in the Gillette coal field are blasted before 

loading. In the NWPRB and MTPRB assessment areas coal 

beds are ripped and heaped before loading. The mine models 

include initial capital, replacement capital, and operating costs 

for each major operational activity. Operational activities 

included overburden and interburden removal, coal loading 

and hauling, reclamation, general mine equipment application, 

and facilities use. Equipment and staffing costs and productivities were obtained from a variety of sources including the 

Society of Mining Engineers of The American Institute of 

Mining, Metallurgical, and Petroleum Engineers, Inc. (1973), 

Caterpillar, Inc. (2012), InfoMine USA, Inc. (2010), and 

discussions with coal companies (oral commun., 2006, with 

various PRB coal companies).

Surface Mine Plant Facilities

The mine plant contains those facilities essential for supporting mining. The mine plant facilities include an administration building, change house, maintenance shop, warehouse, 

laboratory building, emergency building, utility building, and 

guard house.

This assessment includes several mining scenarios 

(stripping ratios of 1:1–10:1) for which different plant space 

requirements are anticipated, and the buildings were sized 

accordingly. Coal handling at the mine plant includes truck 

scales, inclined and horizontal belt conveyors, stacking tubes, 

scalping screen, coal breaker, coal silo, belt sampler, belt 

scales, rail loop or spur, railcar mover, and associated equipment. The mine plant also includes multiple elevated steel 

structures, enclosures, and concrete foundations. Preliminary 

designs for a truck dump to accommodate a wide range of 

large rear-dump truck capacities and a railroad loop were 

developed, from which unit costing was performed.

The cost of a typical mine plant for the mining models 

were calculated for all case studies, which included costs for 

the following items:

• land improvements

• buildings

• coal handling equipment and structures

• truck dump

• railroad loop and access

• miscellaneous structures

• mobile and stationary equipment
34 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Surface Mine Reclamation

Reclamation is an additional ongoing function and 

significant cost factor in the surface mine model. A fleet of 

earthmoving and farm-type equipment perform a variety of 

activities from removal of vegetation and topsoil through 

contouring spoil piles, seedbed preparation, and planting. 

Scrapers remove and transport top soil to temporary storage 

piles and later transport top soil to contoured spoil piles 

for covering. Bulldozers remove brush, trees, and other 

debris during land clearing, rip topsoil, and assist scraper loading. Motor graders contour and scarify bare spoil piles for 

revegetation. Farm tractors with disc and seeder apparatus 

reestablish vegetation and mulch blowers are used to cover 

spoil piles.

Surface Mine Supplies and Utilities

Additional costing items in the surface mine model 

include equipment operating items, personnel wages, explosives, mulch, and seed. Utilities include electricity and natural 

gas/propane.

Surface Mine Reserve and Recoverable 

Resource Evaluation Results

All current mining operations in the Wyoming PRB 

recover coal from beds in the Wyodak-Anderson coal zone of 

the Fort Union Formation. The Wyodak-Anderson coal zone 

represents about one-half of the total remaining available coal 

resources in the PRB (fig. 118). The coal beds within this zone 

dominate the recoverable resource analyses. All coal beds in 

the Wyoming assessment areas that have been economically 

evaluated were within the Wyodak-Anderson coal zone. Several beds below the Wyodak-Anderson zone were evaluated in 

the Montana PRB.

Some additional data entry, coal bed correlation work, and 

consolidation of local bed names were completed for this final 

PRB assessment report. This work was essentially limited to 

beds stratigraphically below the Wyodak-Anderson coal zone 

in the three Wyoming PRB assessment areas and were not 

included in the reserve analyses for the four regional assessment reports. No significant recoverable coal resources were 

found in the East Gillette extension area, which was completed 

following the four PRB regional assessments. Therefore, 

revised reserves analyses for this report were not necessary.

Determination of Reserves

Once the available coal resources were allocated and 

economic mine models completed for an assessment area for 

each stripping ratio mine model (1:1–10:1), reserves were 

estimated from a portion of the total in-place (remaining) 

coal resources. The term “reserves” relates to that portion 

of demonstrated resources that can be recovered economically with the application of extraction technology available 

currently or in the foreseeable future (EIA Agency, 1997). 

Furthermore, the term “reserves” need not signify that 

extraction facilities are in place or operative (Woods and 

others, 1983).

To derive a reserve estimate for each assessment area, 

a composite cost curve was developed for the total recoverable coal resources by incremental DCF costs. Cost curves 

provide a straightforward method of relating recoverable tons 

of coal to current (December 2013) sales prices (for example, 

see figure 123). All of the recoverable tons of coal to a 10:1 

stripping ratio in a given area are sorted from lowest to highest 

DCF costs per ton and plotted against DCF cost. If the current 

(December 2013) market price for coal is $12.00/ton (fig. 123), 

30 BST tons by definition would be considered reserves 

(potentially produced at or below market price). Because a 

coal reserve estimate is based on a single reference point in 

time, the use of cost curves is particularly useful given typical 

fluctuations in the market price. From the cost curve, the relation between changes in the sales price and estimated reserves 

can readily be demonstrated. If the market price increases to 

$18.00/ton, the estimated reserves would double to 60 BST, 

assuming mining costs were similar.

Because reserves refer to that portion of the recoverable coal resource that can be mined at a profit at the time 

of the assessment, it was necessary to determine the current 

(December 2013) FOB market price. The sale of coal is 

normally based on heating value (Btu/lb, as-received basis); 

therefore, the average regional coal heating value for each 

PRB assessment area was required. On the basis of publicly available data, an average heating value (Btu/lb) was 

derived. Average coal quality was used because the lack 

of specific data for every coal bed precluded development 

of more precise coal quality models. For the Gillette coal 

field and MTPRB assessments, an average heating value of 

8,800 Btu/lb was used; an 8,400 Btu/lb average was used for 

the NWPRB assessment area.

The following sections provide a synopsis of the economic analyses for three of the four assessment reports and 

a summary of reserves and total recoverable coal resources 

for the entire PRB (table 11). As previously discussed, no 

economic analysis was conducted for the SWPRB assessment area because of a combination of negative factors. The 

individual PRB coal assessment reports (Luppens and others, 

2008; Scott and others, 2010; Haacke and others, 2013) can 

be reviewed for more detailed information. The DCF costs 

used a common 8 percent rate of return (ROR) for all assessment areas.

Gillette Coal Field Assessment Area

Six coal beds selected for the economic analyses in the 

Gillette coal field are listed in table 12. Four of these are of 

minor importance (Roland [Baker], Smith, Anderson Upper 

Rider, and Dietz 3). The total recoverable coal resources are 

dominated by the thick Anderson and Canyon bed sequence, 

which represents 83 percent of the total recoverable coal 

resources in the Gillette coal field (Luppens and others, 2008). 
Surface Coal Resource Assessment 35

The combination of extensive, thick, coal beds at shallow 

depth, with low-ash and low-sulfur content, makes the Gillette 

coal field the most important coal field in the United States.

All current coal production in the Gillette coal field is 

from the Anderson and Canyon coal beds along the eastern 

margin of the basin. As mining continues down dip from the 

east margin, progressively younger beds (Smith and Roland 

[Baker]) that lie above the primary Anderson-Canyon target 

beds would be exploited (fig. 10). The combination of extensive, thick, coal beds and relatively moderate topography 

resulted in broad areas in the Gillette coal field with stripping 

ratios of 10:1 or less (fig. 124) (Luppens and others, 2008).

With a January 2007 sales price of $10.47 per ton for the 

8,800 Btu/lb coal from the Gillette coal field for the Anderson 

and Canyon beds (Platts, 2007), an estimated 10.1 BST of 

the total 77 BST of recoverable coal resources are considered 

coal reserves (fig. 125). As of March 2008, the sales price for 

the Gillette coal field had increased to $14.00 per ton (Platts, 

2008). Assuming that operating costs remained essentially 

unchanged during the 15-month period since the reserve study 

was completed there would be approximately 18.5 BST of 

reserves (fig. 125). Thus, an increase in the sales price of only 

approximately $3.50/ton nearly doubled the reserves estimate.

Northern Wyoming PRB Assessment Area

Northward from the Gillette coal field, the coal beds split 

and thin presenting a different mining scenario. The Roland 

(Baker) and six beds from the Wyodak Anderson coal zone 

(table 12) were selected for the economic evaluation (Scott 

and others, 2010). There are two regions of shallow coal with 

cumulative stripping ratios of 10:1 or less (fig. 126). The more 

extensive of the two areas is found on the eastern side of the 

NWPRB assessment area where the regional dip is relatively 

low (fig. 9). The area of 10:1 ratios or less north of Sheridan, 

Wyoming, is much more restricted areally because of steeper 

dips on the west side of the basin. The most noteworthy aspect 

of figure 126 is the limited extent of areas less than a 5:1 

stripping ratio, where resources considered reserves would 

be found. Although mining has occurred in the NWPRB 

assessment area, there are no active mining operations in this 

assessment area.

With a January 2010 sales price of $9.30 per ton for the 

8,400 Btu/lb coal from the PRB (Platts, 2010), an estimated 

1.5 BST of the total 50 BST of recoverable coal resources 

are considered as coal reserves (table 12). The relatively low 

reserve estimate is directly related to the limited areal extent 

of resources found at less than a 5:1 stripping ratio (fig. 126).

The mining costs for the NWPRB assessment area are 

higher than those for the Gillette coal field assessment (Scott 

and others, 2010) because of the more complex coal geology 

and multibed mine models that are inherently more costly than 

the simpler single-bed model used for the Gillette assessment. 

Also, the mine model for the NWPRB assessment area used 

truck-shovel operations exclusively for more coal beds with 

thicker interburden intervals. For the Gillette coal field, a 

dragline operation combine with truck-shovel operations for 

prestripping was used to take advantage of the lower unit stripping costs that a dragline offers.

The cost curve (fig. 127) readily demonstrates the 

relation between sales price and estimated reserves. On 

January 5, 2009, the sales price per ton for the 8,400 Btu/lb 

coal from the PRB was $11.00 per ton (Platts, 2009a). An 

estimated 3 BST would be a reserves equivalent at this price. 

The $11.00 per ton price held steady through April 6, 2009, 

then suddenly dropped to $8.00 per ton in one week (Platts, 

2009b, c). By November 23, 2009, the sales price had bottomed out at $7.65 per ton (Platts, 2009d), which would be a 

reserves equivalent of 0.8 BST at this price. The sales price 

as of January 2010, for 8,400 Btu/lb coal from the PRB was 

$9.30 per ton (Platts, 2010) (fig. 127). The changes in the sale 

price during the 10-month period corresponded to a 1.9 BST 

swing in reserves estimates from a maximum of 3 BST 

to a low of 0.8 BST, emphasizing the value of preparing 

cost curves.

Montana PRB Assessment Area

The coal geology in the Montana PRB differs from the 

Wyoming PRB. The coal bed thicknesses in the MTPRB 

assessment area are more variable than in the NWPRB assessment area of Wyoming (Scott and others, 2010). Areas of 

thicker coal (greater than 20 ft thick) are more pod-like as 

illustrated by the isopach maps of the Dietz 3, Canyon, Lower 

Canyon, Werner/Cook, Pawnee, and Flowers-Goodale coal 

beds (figs. 62, 68, 69, 76, 84, and 104). Deeply-dissected 

drainages limit the areal extent of shallow, surface-minable 

coal beds in the MTPRB assessment area. Figure 10 illustrates 

the more deeply incised topography in Montana. The MTPRB 

assessment area is the only area in the PRB that contains 

potentially minable coal beds, below the Wyodak-Anderson 

coal zone (fig. 13) (Pawnee, Rosebud/Knobloch, and FlowersGoodale beds), that are both sufficiently thick and have a 

significant areal extent at stripping ratios at or less than 10:1 

(figs. 128–133).

Ten of the 18 coal beds had sufficient areal extent 

and thickness to be further evaluated for recoverable coal 

resources (Haacke and others, 2013). Five of these beds, 

the Roland (Baker), Smith, Anderson, Dietz 2, and Dietz 3 

were combined into a regional, multibed mine model. Portions of this sequence are currently being mined at the Decker 

and Spring Creek Mines in the southwestern portion of the 

MTPRB assessment area (fig. 12). The stripping ratio map for 

this mine model sequence is shown in figure 128.

In addition to the regional mine model sequence, the 

Canyon, Werner/Cook, Pawnee, Rosebud/Knobloch, and 

Flowers-Goodale coal beds were evaluated for reserve potential (table 12). Of these five beds, only the Rosebud/Knobloch 

bed is currently being mined in the Colstrip area (figs. 1 and 

12). Additionally, the Rosebud/Knobloch bed is the primary 

target in the Otter Creek lease area (fig. 12). The stripping 

ratio maps for these coal beds are shown in figures 128–133. 
36 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

The individual coal bed stripping ratio maps demonstrate the 

relation between the deeply-dissected surface morphology and 

coal thickness. A comparison of the isopach map and stripping 

ratio map for a given bed illustrates this relation. For example, 

the more extensive area of less than a 10:1 ratio in R. 39 E. 

to R. 41 E. for the Werner/Cook bed (fig. 130) corresponds 

to the thickest portion of the Werner/Cook bed (fig. 76). 

Elsewhere, the less than 10:1 ratio areas for the thinner portions of the Werner/Cook bed are confined to narrow bands 

along drainages.

A total of 39 BST, at a stripping ratio of 10:1 or less, 

remains in the 10 beds assessed for reserves. After mining and 

processing losses were subtracted, about 35 BST of coal were 

considered recoverable coal resources (table 12). To derive a 

reserve estimate for the MTPRB assessment area, a composite 

cost curve was developed for the cumulative total 35 BST of 

recoverable coal resources using the November 2011 FOB 

sales price for 8,800 Btu/lb coal from the PRB of $13.20 per 

ton (Platts, 2011a). The reserve estimate for the MTPRB was 

about 13 BST (table 12, fig. 134).

Combined PRB Reserve and Recoverable Resource Summary

Resources and reserves of the Gillette coal field, 

NWPRB, SWPRB, and MTPRB assessment area as well as 

total PRB resources and reserves are summarized graphically (fig. 135). The total coal reserves estimate for the PRB 

is 24.5 BST from the three areas assessed for surface minable coal. The most striking feature of these bar graphs is that 

the reserves are a small fraction (about 2.3 percent) of the 

total, original in-place resources. A significant amount of coal 

affected by all restrictions to mining (coal too thin, depth, 

towns, and other restrictions) and mining losses precludes 

recovery of most of the original in-place coal resources. The 

relation of original resources to reserves is consistent with 

previous USGS coal assessments, which typically determine 

the reserve fraction to be less than 20 percent (Luppens and 

others, 2009). The value of economic-based assessments is to 

provide resource planners with realistic estimates of resources 

that are recoverable and an understanding of the importance 

of differentiating between in-place resources and reserves. 

The PRB assessments were completed sequentially and 

consequently market prices were different at the time the cost 

curve for each study was generated. To simplify the process 

of generating a single, unified reserve estimate for the entire 

PRB, all recoverable coal resources needed to be evaluated on 

a common market sales price basis. The DCF costs for all the 

individual stripping ratio mine models from the Gillette coal 

field, NWPRB assessment area, and MTPRB assessment areas 

were combined into a single cost curve.

The result of the aggregation of mine model costs is the 

cost curve shown in figure 136. Using the FOB sales price 

of $10.90 per ton as of July 15, 2013 for PRB 8,800 Btu/lb 

coal (Platts, 2013), the coal reserve estimate for the entire 

PRB is about 23 BST (fig. 136). This is slightly lower than 

the simple addition of the reserve estimates from the Gillette 

coal field, NWPRB assessment area, and MTPRB assessment 

area reports because of a small decrease in market price in 

June 2013. This difference in reserve estimate underscores the 

fact that reserve estimates are a constantly moving target, as 

sales prices continually fluctuate, responding to variations in 

market demand. For example, in November 2009, the sales 

price for PRB 8,800 Btu/lb coal had dropped to $8.90 per ton 

(Platts, 2009c), and subsequently increased to $15.15 per ton 

in December 2011 (Platts, 2011b). The effect of this market 

price variation on the range of reserve estimates was a low of 

10 BST to a maximum of 43 BST (fig. 136). The use of cost 

curves provides flexibility to adjust the reserves estimates to 

fluctuations in market price. Single estimate results are essentially frozen in time based on the economic conditions at the 

time of the assessment.

While the estimates of reserves are important, the relation 

between reserves and recoverable coal resources is equally 

significant, especially in light of the fundamental mission of 

the USGS Coal Assessment Project which is to determine 

the coal reserve base in all major U.S. coal basins. The coal 

reserve base includes identified resources that meet specified 

minimum criteria related to current mining and production 

practices, including those for quality, depth, thickness, and 

rank (Woods and others, 1983).

These recoverable coal resources are essentially equivalent to coal resource categories included in the EIA-estimated 

recoverable reserves (ERR) database (Energy Information 

Administration, 1997). The ERR, which is updated by the EIA 

periodically, is currently the only published national summary 

of potentially recoverable coal in the United States. The ERR 

is the portion of the DRB coal that may be recoverable, based 

on regional estimates of coal resource accessibility and mining 

recovery rates. It is especially important to understand that 

the coal reserve base may encompass those parts of a resource 

that have a reasonable potential for becoming economically 

recoverable within planning horizons that extend beyond 

those which assume proven technology and current economics 

(Energy Information Administration, 1997). The ERR includes 

those resources that currently are classified as reserves and 

recoverable coal resources that may be mined in the future.

It is a common misconception that any given estimate 

of reserves implies that the volume of coal in the reserves 

category is all that is left to recover. From figure 136, it can 

be seen that as market prices increase, the reserve estimate 

increases while the amount of remaining currently uneconomic recoverable coal resources decreases and vice versa. 

Reserve estimates are by nature a moving target.

Typically, as mining progresses in a basin, resources 

become progressively more expensive to produce. Sale prices 

generally increase as long as demand supports higher prices. 

With continued favorable sales prices and increased productivity and advances in mining technology that positively affect 

economics, resources once considered to be subeconomic may 

be elevated to the reserve status. For example, typical average 

stripping ratios in the Gillette coal field in 1990 were about 2:1 

or less; therefore, resources greater than a 2:1 ratio would have 
Underground Coal Resource Assessment 37

been placed in the recoverable coal resources category. PRB 

coal reserves currently mined include coal resources up to ratios 

ranging from 3:1 to 4:1 Reserve studies should be considered 

a cyclic process and models should be adjusted periodically 

using the most recent data and reassessed using the most current 

recovery technology and economics.

Underground Coal Resource Assessment

A significant volume of coal resources in the PRB are contained in relatively thick coal beds at depths that may be impractical for surface mining. While no coal in the PRB is currently 

recovered by underground mining methods, nor expected to be 

in the near future, significant resources at depths of 2,000 ft or 

less are easily within the range of current underground mining technology. An evaluation of potential underground coal 

resources was also conducted to determine a preliminary estimate of the magnitude of underground resources.

There are precedents for transitioning from surface to 

underground mining operations. Several other surface coal 

mines in western United States basins have converted to underground longwall systems as surface coal reserves were depleted. 

For example, the San Juan operation near Farmington, New 

Mexico, consists of an underground mine accessed via the high 

wall of a closed strip mine (Mercier, 2010). The underground 

longwall operation has successfully extended coal extraction 

in a location where increasing overburden created unfavorable economics for further surface operations (Mercier, 2010). 

A similar situation developed at the Jim Bridger Mine near 

Rock Springs, Wyoming (PACIFICORP, 2011). The life of 

the mine was extended by developing an underground mine as 

surface minable reserves were nearing depletion to continue 

to provide fuel to the power plant for an additional 20 years 

(PACIFICORP, 2011). Underground longwall mining methods 

are used in a coal bed that has as much as 1,000 ft of overburden 

(PACIFICORP, 2011).

The assessment of underground resources consisted 

of two parts. First, a mining method was selected and then 

a mine model was selected to generate estimated DCF cost 

per ton. This cost could then be compared to the cost of 

surface mining. The amount of deep coal in the PRB that 

was amenable to development by the selected mining system 

was inventoried.

Two principal underground mining systems are used in 

the United States: continuous mining (commonly referred to 

as room and pillar) and longwall mining. The longwall mining system was chosen as the preferred method for several 

reasons. Although a longwall system requires higher capital 

and installation costs, it has higher productivity and recovery 

rate than the continuous mining system. Additionally, the 

longwall system offers safety improvements, and offers the 

best opportunity for automation (U.S. EIA Agency, 1995).

The minable coal bed thickness for longwall systems 

ranges from 5 to 13 ft (Thomas, 2002). Although longwall 

shearers are commonly used for bed thicknesses between 5 

and 20 ft (Myszkowski and Paschedag, 2009), a 10-ft minimum was used as a more conservative estimate of potential 

underground resources for longwall operations. For portions 

of coal beds that exceeded 20 ft in thickness, only a 20-ft 

slice of those beds was included to the underground resources 

estimate. All of the coal beds greater than 20 ft were considered unrecoverable by current underground technology.

As with other coal basins, only a fraction of the total 

underground resource is typically recoverable. Factors such 

as adverse roof, floor conditions, slope of the coal beds, and 

essential safety barriers are restrictions to mining. Although 

recovery in multiple bed areas is generally most efficient by 

mining from the uppermost bed downward, that situation is 

impossible to control. Interburden between beds must be thick 

enough to prevent interbed structural problems.

Underground Mine Model Design

A preliminary underground mine model provides a 

reasonable estimate of the economic tipping point where 

underground mining might be a more viable alternative to 

surface mining, which establishes a limit on recoverable coal 

resources by surface mining. No underground mines are currently operating in the PRB as discussed in the NWPRB (Scott 

and others, 2010), SWPRB (Osmonson and others, 2011), and 

MTPRB assessment areas (Haacke and others, 2013). For each 

of these assessments, a separate underground mine model was 

developed. The NWPRB assessment area model was based on 

a production rate of 11 MST/yr and the SWPRB assessment 

area model was based on a production rate of 6 MST/yr. The 

SWPRB assessment expanded the scope of both the NWPRB 

and the MTPRB assessments, by considering the effects of 

coal thickness and depth.

Potential underground coal reserves in the PRB assessment area were evaluated using a conventional, single-pass, 

continuous, longwall mining methodology. Current face 

shearer and roof support design are available for mining up 

to 20 ft thick (Myszkowski and Paschedag, 2009), which is a 

reasonable thickness in portions of the PRB. With the exception of the Gillette coal field, underground mine models were 

developed for all the PRB assessment areas to estimate potential deep, recoverable coal resources. To provide an example 

of the level of detail in the conceptual underground mine 

model, the following sections describe the underground mine 

design used for the MTPRB assessment area.

Underground Mine Layout Design

The underground mine model incorporates longwall 

technology, which includes four primary components: (1) surface mine plant; (2) underground mine plant; (3) development 

excavation; and (4) longwall panel. All openings, support 

pillars, and longwall panel dimensions were sized to provide 

an annual production of 6 MST/yr which is an average size 

for currently operating longwall mines (Paul Pierce, oral 

commun., 2013). This average annual production is acquired 
38 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

through development, production, and pillar recovery operations. The model can be used to evaluate mining thicknesses 

that vary from 8 to 20 ft and depths from less than 500 to 

3,000 ft. The model can also be used to evaluate a wide range 

of annual production rates with some adjustment to longwall 

panel access openings and pillar sizes.

The mine model was designed for primary entry to the 

longwall panel through five parallel main drifts. Additional 

excavation included a three-entry headgate for incoming airway 

and main access to longwall mining and two entry tailgates for 

return airway and supplies. Both the headgate and tailgate openings extend perpendicular from the main entries to the full panel 

length and are separated by the width of the longwall panel. An 

initial longwall face opening is excavated at the far end of the 

longwall panel that connects the headgate and tailgate.

Annual production for the underground mine model is the 

sum of coal mined from main access, headgate, and tailgate 

excavation, longwall production, and pillar recovery. Physical 

dimensions of the longwall panel and associated mine openings are adjusted to maintain 6 MST/yr of production. The 

effects of increased mining height and depth have been correlated with variable panel barrier-pillar size and overall pillar 

recovery. The longwall panel width varies only with mining 

height and the panel length and is adjusted to provide the overall annual production from entries, panel, and pillars.

Surface Mine Plant

Coal handling facilities are the primary purpose of the 

surface mine plant. The surface mine plant for the underground mine are those facilities essential for supporting 

mining, including buildings, coal handling equipment, rail 

loading facilities, and mobile and stationary equipment. The 

mine model surface plant includes an administration building, 

change house, maintenance shop, warehouse, laboratory building, emergency building, utility building, guard house and 

tool sheds, and hoisting and ventilation facilities to support 

underground operations.

Other facilities include a stacking tube, horizontal and 

inclined belt conveyors, scalping screens, coal breaker, 

coal silo, waste bin, rail loadout structure, rail loop, various 

elevated steel structures and housings, preparation plant, and 

concrete foundations. The inclined belt conveyor is included 

with the surface mine plant and the excavation for the incline 

is included with the underground mine plant. The use of a tandem ramp and shaft arrangement is assumed for medium mine 

depths. Shallow underground mines will likely use ramps and 

deep mines will use shafts. All stationary coal handling facilities have been oversized to move in excess of the 6 MST/yr 

production rate.

Hoisting facilities are included in the surface mine 

plant and shaft excavation and furnishing are included in the 

underground mine plant component of the mine model. One 

dedicated ventilation shaft is included in the mine plant, but 

hoisting facilities have not been provided. Ventilation facilities include two 10-ft-diameter 800-horsepower surface mine 

fans, ducting, concrete foundation, electrical controls and 

switchgear, and appropriate enclosures. Ventilation facilities are constructed adjacent to a dedicated shaft for primary 

incoming airflow.

Underground Mine Plant

Three excavations (men-and-materials shaft, ventilation 

shaft, and ramp) connect surface and underground mine plants. 

A nominal depth of 1,000 ft has been used for shafts and an 

inclined length of 2,280 ft for a ramp. Both shafts have been 

excavated with large-diameter drilling equipment and lined 

with concrete. The ramp is excavated with a continuous mining 

machine and lined with rock bolts, wire mesh, and shotcrete.

Primary excavations at the bottom of the underground 

mine plant at the men-and-materials shaft include a warehouse, shop, lunchroom, refuge chambers, water sump, 

electrical substation, and connecting runaround access way. 

The bottom of the ramp is located some distance away and 

has excavations for refuge chambers, electrical substation, 

and runabout access way. Both the shaft and ramp stations are 

lighted. Stationary equipment in the shaft station includes air 

compressors and centrifugal water pumps. Both the shaft and 

ramp stations include concrete flooring, steel equipment bases, 

and electrical cable distribution.

Fresh air provided by surface fans supplies the secondary 

air distribution using rigid ventilation ducts, which are boosted 

with auxiliary ventilation fans. This secondary system is used 

throughout the underground mine.

Underground Mine Development Excavation

Underground excavation that extends some distance 

beyond the shaft and ramp stations occurs prior to production 

mining as described for the production unit section of this 

assessment and is performed as a construction activity. Coal 

removed during this project phase is transported to the surface 

and disposed as a waste product.

Development excavation includes five parallel headings 

with connecting crosscut openings. These headings extend to 

the edge of the mine plant barrier pillar. This barrier pillar is 

sufficiently sized for underground mine plant facilities protection from structural instability because of mining production. 

All excavation during this phase is performed by a continuous 

miner and supporting mobile equipment.

Longwall 1anel and 1illar 3ecovery

The production unit is generally centered near the longwall panel. All pre-longwall mining following development 

excavation is considered production and transported offsite 

for sale. The production unit includes the main access way 

extending from the initial development excavation, gateway 

excavation, longwall opening, and longwall panel.

Gateway excavation starts at the main access way and 

extends to the full length of the longwall panel. A three-entry 

arrangement is developed for the headgate and two entries for 

the tailgate. A single longwall opening is excavated to connect 

the ends of the gateways. A longwall panel that is 1,000-ft 
Conclusions 39

wide is included in the underground mine model design. This 

panel size is estimated to provide sufficient coal for a continuous year of operation without moving to a new area. A 

complete suite of standard equipment is included in the model 

(face shearer, roof supports, armored face conveyor, and supporting systems).

Pillar recovery provides substantial coal production as 

a final activity in the typical production unit. This operation 

involves trimming single pillars to an extent that coal can be 

produced without collapsing the immediate roof area during 

the activity. Pillar recovery is included in the underground coal 

mine model for chain pillars, panel barrier, and main access 

pillars for the typical longwall unit.

High vertical stresses are applied to the lateral edges of the 

longwall panel as the shearer cuts across the face of the longwall and progresses toward the end of the panel. These stresses 

tend to concentrate over the rib line of the opening adjacent to 

the panel. The forward edge of the first row of support pillars 

in the gateways on either side of the panel, are expected to 

partially collapse. This collapse is likely to cause a yield zone 

that extends some distance into the pillar interior. The remaining 

portion of the pillar is expected to be competent enough to allow 

significant recovery by a continuous miner. The vertical stress 

concentration over the outer pillar line in the headgate should 

be less than the stress over the longwall panel periphery, and a 

higher pillar extraction rate can be expected.

All the coal on the panel side of the barrier pillar is 

expected to be unrecoverable. Pillar recovery will need to be 

conducted from the main access way. Excavation of the barrier 

pillar will be conducted in concert with main access-way pillar 

recovery. Only partial recovery will occur to leave sufficient 

natural support for retreating from the area.

Underground Coal Resources Results

Eleven coal beds within the PRB were assessed as potentially minable by underground operations. These coal beds, 

which have favorable thicknesses, depths, and areal extents for 

possible underground extraction in the future are the Roland 

(Baker), Smith, Anderson, Dietz 3, Canyon, Lower Canyon, 

Werner, Otter, Pawnee, Rosebud/Knobloch, and FlowersGoodale. Total resources in beds between 10 and 20 ft in 

thickness and 500 ft or greater in depth are about 304 BST 

(table 13). About 99 percent of the resources assessed were 

less than 2,000 ft in depth. Almost one-half (48 percent) 

of those deep resources are found in just two of the coal 

beds (Smith and Canyon) (table 13). Two-thirds of the deep 

resources are found within the SWPRB assessment area. This 

is not surprising given the extraordinary thickness of the Smith 

and Canyon beds in the deeper portions of the PRB.

Because of slightly different geological conditions and 

mining assumptions used in the three assessment areas evaluated for underground resources, the breakeven cost per ton 

ranged from $20 per short ton to about $31 short ton (Scott 

and others, 2010; Osmonson and others, 2011; and Haacke 

and others, 2013). Given the current sales price of about 

$11 per short ton for 8,800 BTU/lb for PRB coal (Platts, 2013); 

the estimated cost of underground mining is about 2–3 times 

the current (December 2013) FOB sales price. Therefore, none 

of the coal resources in the 11 deep coal beds in the PRB can 

currently be classified as reserves. A factor that will improve 

underground coal mining economics is that the heating value of 

coal increases with depth. The estimated calorific values of the 

deep coals range from about 9,300 Btu/lb at 1,000 ft depth to 

10,000 Btu/lb at 2,000 ft depth (Luppens, 2011; Osmonson and 

others, 2011). The higher cost of underground mining might be 

partially offset by progressively higher quality coal with depth. 

Various restrictions, such as the geotechnical constraints of 

adverse roof and floor conditions, local coal bed thinning, and 

hydrology issues, would reduce the amount of coal resources 

ultimately recovered. The deep, thick coal beds in the PRB 

represent a significant future, long-term resource. The longwall 

model analyses demonstrate that as the surface mining depths 

continue to increase in other parts of the PRB, underground 

exploitation of deep, thick coal, in the SWPRB assessment area 

may become an increasingly viable alternative as long as the 

demand for coal supports higher prices.

Conclusions

This report presents the final results of an 8-year effort 

to collect sufficient data to map and model 47 significant 

coal beds individually for the entire PRB. Previous resource 

assessments in the PRB have relied on net coal isopach maps, 

which provide reasonable estimates of in-place resources, but 

are insufficient for conducting economic analyses to derive 

reserve estimates and the total amount of recoverable coal. 

The tremendous amount of CBM development in the PRB 

during the last 10 years has provided a wealth of new, publicly 

available data, especially in the Gillette coal field. Because 

the PRB is the single most important coal basin in the United 

States in terms of yearly coal production, incorporating as 

much of these data as practical was warranted. Some of the 

key results of this assessment are:

• The total number of holes in the final PRB database 

increased to 29,928, about 13,700 holes entered and 

interpreted by USGS personnel. In the Gillette coal field 

alone, the original database was expanded from about 

2,391 to 10,210 data points. Additional data and support 

were provided by the Wyoming State Geological Survey 

and the Montana Bureau of Mines and Geology.

• The increased data control significantly improved the 

geological interpretation, including revision of coal bed 

correlations and increased geological assurance for the 

resource and reserve estimates.

• This report is groundbreaking as it provides the first 

published maps of the individual coal beds for the entire 

PRB. Unification of local bed names was crucial to 

this achievement.
40 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

• The new geologic coal bed models provide a more 

robust assessment of recoverable coal resources and 

also facilitate other resource planning, such as developing CBM and evaluating the environmental effects of 

energy-related production.

• The methodology for assessing the restrictions to 

mining was improved from the previous “cookie cutter” approach to allow for safety setbacks needed to 

maintain stable highwalls in the mined coal beds rather 

than simple surface-only expressions around identified buffers.

• An additional relatively deep box cut will be required 

in the southern one-half of the Gillette coal field to 

recover coal resources west of the Joint Line Railroad. 

The need for this additional box cut will result in a 

significant increase in overall mining costs for coal 

resources in that area.

• An important distinction of the SWPRB assessment 

area compared to the other PRB assessment areas is 

the absence of the extensive, thick, shallow WyodakAnderson coal zone.

• While no coal in the PRB is currently recovered by 

underground mining methods, nor is it expected to be 

in the near future, there are significant deep resources 

within the range of current underground mining technology. Underground resources for coal beds 10–20 ft 

thick and 500–2,000 deep were estimated at 304 BST.

• The mapping of individual coal beds for the first time 

throughout the entire PRB was required to complete an 

economic assessment of both available and recoverable 

coal resources and offers a unique perspective compared to previous work, which relied on less effective 

net coal isopach maps. This in turn may provide new 

viewpoints regarding depositional environments of this 

extensive, exceptionally thick, coal sequence.

• Regional prefeasibility mine models were developed to 

conduct mining economic evaluations to estimate the 

portion of the available resources that meet the definition of reserves and recoverable coal.

• Estimates of reserves and resources are important, 

however, the relation between reserves and recoverable 

coal resources is equally significant in understanding 

the potential coal reserve base of the United States. 

The coal reserve base provides estimates of coal 

resources that are currently economic (reserves), and 

those recoverable resources that may become economic using current technologies. This information is 

important from a national energy security and policy 

standpoint regardless of time frames.

• The cumulative results from the four PRB assessment 

areas are 24.5 BST of coal reserves and a total recoverable coal resource (coal reserve base) of 162 BST in 

coal beds greater than 5 ft in thickness and less than a 

10:1 stripping ratio.

With continued favorable sales prices, increased productivity, and technological advances in mining that positively affect economics, resources once considered to be 

subeconomic may be elevated to the status of reserves. Therefore, reserve studies should be considered a cyclic process and 

models should be adjusted and assessed periodically using 

the most recent data, which uses the most current recovery 

technology and economics.

Acknowledgments

This report was produced through the efforts and cooperation of many people. Susan Tewalt, Michael Brownfield, 

Tom Judkins, and David Ferderer, all presently or formerly 

of the USGS, provided in-depth technical reviews of the 

manuscript. Nicholas Jones (formerly with the Wyoming State 

Geological Survey), the staff of the Wyoming State Geological 

Survey, and Jay A. Gunderson of the Montana Bureau of 

Mines and Geology, supplied data and information pertaining to the Powder River Basin. Ed Heffern, formerly with the 

Bureau of Land Management in Cheyenne, Wyoming, supplied the digital files that show the extent of clinker within the 

Powder River Basin. 

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Glossary 47

Glossary

The present study includes determinations of original, available, and recoverable coal 

resources; reserves, and reserves, which are economically recoverable coal resources. This terminology has been used in many USGS coal studies (see Wood and others, 1983; Carter and Gardner, 1989; Eggleston and others, 1990; and Molnia and others, 1999). The following definitions 

were applied in this resource evaluation: 

Coal resources Naturally occurring concentrations or deposits of coal in the Earth’s crust, 

in such forms and amounts that economic 

extraction is currently or potentially feasible 

(Wood and others, 1983).

Continuous mining Mining in which the continuous miner machine cuts or rips coal from 

the face and loads it onto conveyors or into 

shuttle cars in a continuous operation (Thrush, 

1968).

D

Delta The low, nearly flat, alluvial tract 

of land at or near the mouth of a river, commonly forming a triangular or fan-shaped plain 

of considerable area (Jackson, 1997).

Deltaic Pertaining to or characterized 

by a delta (Jackson, 1997).

Demonstrated coal reserve base (DBR)

Includes publicly available data on coal 

mapped to measured and indicated degrees of 

accuracy and found at depths and in coalbed 

thickness considered technologically minable at 

the time of determinations (U.S. Department of 

Energy, 2013).

Dip (dipping) The angle at which a bed, 

stratum, or vein is inclined from the horizontal 

(Thrush, 1968).

Discounted cash flow (DCF) The stream 

of the net after-tax cash flows where the cash 

outlays include all operating costs, taxes, and 

investment costs, and where revenues include 

cash payments of product sales (Association for 

the Advancement of Cost Engineering, 1997).

F

Facies The aspect, appearance, and characteristics of a rock unit, usually reflecting the 

conditions of its origin, especially as differentiating the unit from adjacent or associated units 

(Jackson, 1997).

A

Alluvial Pertains to or composed of alluvium 

(sediments) deposited by a stream (Jackson, 

1997).

Available coal resources Remaining coal 

resources that are thick and shallow enough 

to be mined by either surface or underground 

methods and that are unencumbered by land-use, 

environmental, societal, regulatory, or technologic restrictions as they may apply in a specific 

State or region (Carter and Gardner, 1989).

B

Box cut The initial cut driven in a property, 

where no open side exists; this results in a highwall on both sides of the cut (Thrush, 1968).

C

Chronostratigraphic The organization of rock 

strata into units on the basis of their age or time 

of origin (Jackson, 1997).

Coalbed methane (CBM) Primary coal bed 

gas collected from unmined coal beds (Clarkeenergy, http//:Clarke-energy.com/gas-type/coalgas, accessed on May 7, 2013).

Coal reserves Virgin or accessed parts of a 

coal reserve base which could be economically 

extracted or produced at the time of determination considering environmental, legal, and technologic constraints. The term “reserves” need 

not signify that extraction facilities are in place 

or operative. Reserves include only recoverable 

coal; thus, terms such as “extractable reserves” 

are redundant and are not a part of the classification system. Reserves can be categorized as 

“measured” and “indicated,” as underground or 

surface minable, by thickness of overburden, by 

thickness of coal in the bed, and by various quality factors (Wood and others, 1983).

Coal reserve base The tonnage estimate for 

coal consisting of the sum of the estimates for 

measured and indicated reserves, marginal 

reserves, and a part of the measured and indicated 

subeconomic resources (Wood and others, 1983).
48 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Fault(s) A fracture or fracture zone along 

which there has been displacement of the two 

sides relative to one another parallel to the 

fracture (Thrush, 1968).

Fluvial Of or pertaining to a river or rivers 

(Jackson, 1997).

Freight on Board (FOB) A reference to the 

place where purchased goods will be shipped 

without transportation charge.

G

Gytta A dark, pulpy, freshwater mud characterized by abundant organic matter that is more 

or less cohesive, and deposited or precipitated 

in a marsh or in a lake whose waters are rich in 

nutrients and oxygen (Jackson, 1997).

H

Headgate The primary roadway access and 

egress through which equipment, personnel, and 

supplies are provided to a longwall face, through 

which coal is conveyed to the surface, and 

through which fresh air flows (Stermole, 1974).

Hypothetical resources Tonnage estimates 

computed by extrapolation of thicknesses 

of coal for a radius beyond 3.0 mi (4.8 km) 

from a point of measurement. Hypothetical 

resources are a class of undiscovered resources 

that are either similar to known coal deposits 

which may be reasonably expected to exist 

in the same region under analogous geologic 

conditions, or are an extension from inferred 

resources (Wood and others, 1983).

I

Identified resources Resources whose locations, rank, quality, and quantity are known 

or estimated from specific geologic evidence. 

Identified coal resources include economic, 

marginally economic, and subeconomic 

components. To reflect varying distances from 

points of control or reliability, these subdivisions can be divided into demonstrated and 

inferred, or preferably into measured, indicated, 

and inferred (Wood and others, 1983).

Indicated resources Tonnage estimates computed by extrapolation of thicknesses of coal 

for a radius of 0.25 to 0.75 mi (0.4 to 1.2 kilometers [km]) from a point of measurement 

(Wood and others, 1983).

Inferred resources Tonnage estimates computed by extrapolation of thicknesses of coal for 

a radius of 0.75 to 3.0 mi (1.2 to 4.8 km) from a 

point of measurement (Wood and others, 1983).

In-place resources Resources that currently 

exist within a geographic area. The term inplace resources is equal to the term available 

resources in this report.

Interburden The rock between two coal beds. 

When two potentially minable coal beds occur 

within a minimum acceptable distance above or 

below one another, one will not be mined–often 

the thinner of the two (Carter and Gardner, 1989).

Interdeltaic A term used by Ayers and Kaiser 

(1984) to describe coal beds forming between 

deltas.

L

Land-use restrictions Constraints placed upon 

mining by societal policies to protect those surface features or entities that could be harmed by 

mining. Since laws and regulations can be modified or repealed, the restrictions, including industrial and environmental restrictions, may change. 

Land use restrictions include railroads, cities, 

and towns, airports, and Interstate highways.

Longwall mining A system of underground 

mining on straight faces 80 yards (73 m) or 

more in length (Thrush, 1968).

M

Measured resources Tonnage estimates computed by extrapolation of thicknesses of coal 

for a radius of 0.25 mi (0.4 km) from a point of 

measurement (Wood and others, 1983).

Mined coal Coal that has already been 

extracted from a deposit (Association for the 

Advancement of Cost Engineering, 1999).

Mire(s) A small piece of marshy, swampy, or 

boggy ground (wet spongy earth) (Jackson, 1997).

O

Original coal resource The total amount of 

coal in-place before production. Where mining 

has occurred, the total of original resources is 

the sum of the identified resources, undiscovered resources, coal produced, and coal lost in 

mining (Wood and others, 1983). 

Overburden Rock including coal or unconsolidated material that overlies a specified 

coal bed. Overburden is reported in feet or 

meters and is used to classify the depth to an 

underlying coal bed (Wood and others, 1983).

Outcrop(s) That part of a rock formation (coal 

bed) that appears at the surface of the ground 

(Thrush, 1968).
Glossary 49

P

Paleosol(s) A soil that formed on a landscape 

in the past with distinctive morphological features resulting from a soil-forming environment 

that no longer exists at the site (Jackson, 1997).

Parting(s) A thin layer of stratum or noncoaly material within a coal bed which does 

not exceed the thickness of coal in either the 

directly underlying or overlying benches (Wood 

and others, 1983).

Peat(s) An unconsolidated deposit of semicarbonized plant remains in a water-saturated environment, such as a bog or fen (Jackson, 1997).

R

Recoverable coal resource Coal that is or 

can be extracted from a coal bed during mining. The term “recoverable” should be used 

in combination with “resources” and not with 

“reserves” (Wood and others, 1983). 

Reliability categories Based on the distance 

from points of measurement or sampling. The 

measured, indicated, inferred, and hypothetical resource categories, as defined, indicate the 

relative reliability of tonnage estimates as related 

to distance from points of thickness control of 

particular parts of a coal deposit. The reliability 

categories are not indicative of the reliability of 

the basic data (that is, the accuracy of coal measurements, or the accuracy of location of the coal 

outcrop). It is assumed that all basic data used in 

resource estimation have been judged reliable by 

the estimator and that unreliable data have been 

discarded (Wood and others, 1983). 

Remaining resources Represent resources in 

the ground after subtracting coal that has been 

previously mined from the original resource 

(Carter and Gardner, 1989).

Restrictions to mining Include land use 

restrictions, technical limitations, and unsuitability criteria that would prohibit mining.

Royalty A lease by which the owner or lessor 

grants to the lessee the privilege of mining and 

operating the land in consideration of payment 

(Thrush, 1968).

S

Strip (stripping) ratio Represents the ratio 

of the volume of overburden or interburden 

(waste) that must be removed to gain access to 

a unit amount of coal. For this assessment, the 

ratio is expressed as cubic yards of overburden to tons of coal. The stripping ratio can be 

approximated by dividing the total thickness 

of waste by the total thickness of coal. For 

example, given a coal bed, 10.0 ft thick, at 100 

ft in depth, the stripping ratio would be 10:1 (in 

cubic yards to a ton of coal) (Thrush, 1968).

Subaerial Means conditions and processes, 

such as erosion, existing or operating in the 

open air on or immediately adjacent to the land 

surface (Jackson, 1997).

Subbituminous coal Rank class of nonagglomerating coals having a heat value content of more than 8,300 Btu and less than 

11,500 Btu on a moist, mineral-matter-free 

basis (Wood and others, 1983).

Surface coal mining (strip) Mining at or near 

the ground surface and is generally done where 

the overburden can be removed economically. 

A strip mine is a surface mine in which the 

overburden is removed from a coalbed before 

the coal is removed (Thrush, 1968).

T

Tailgate The secondary roadway access or 

egress from a longwall face and through which 

return air flows (Society of Mining Engineers, 

1973). 

Technical restrictions Constraints, relating 

to economics and safety, placed upon mining 

by the state of technology or prescribed by law. 

These restrictions can change with advances 

in science and technology, or modifications in 

the law. In the report, some geologic factors are 

included as technologic restrictions. Technical restrictions include coal between 2.5 ft and 

5.0 ft thick and areas of clinker.

U

Unsuitability criteria Specific legal constraints used to determine if an area can be 

mined by surface mining methods. These 

include, but are not limited to, Federal land 

systems, dwellings, and alluvial valley floors.

Figures

Figures 53

Figure 1. Map showing location of the Powder River Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

Birney

Decker

Colstrip

Broadus

Gillette

Buffalo

Wright

Miles City

Douglas

Casper

Moorcroft

Decker

Colstrip

Broadus

Ashland

Forsyth

Lame Deer

Casper

Wright

Glenrock

Sheridan

§ ̈¦25

§ ̈¦94

§ ̈¦90

§ ̈¦90

§ ̈¦90

§ ̈¦90

§ ̈¦25

CROW 

RESERVATION

NORTHERN

CHEYENNE 

RESERVATION

Powder

River

Basin

NIOBRARA

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

TREASURE

COUNTY ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

POWDER RIVER COUNTY

CROOK COUNTY

CAMPBELL

COUNTY

WESTON

COUNTY

NATRONA

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

\\IGSKAHCMVSFS002\PubsCommon\Jeff\den14hdaa100122luppens\reportfigure01ai

BURLINGTON NORTHERN 

SANTA FE RAILROAD

BURLINGTON 

NORTHERN 

SANTA FE AND 

UNION PACIFIC 

RAILROADS
54 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 2. Map showing location of individual assessment areas in the Powder River Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

Glenrock

Birney

Decker

Colstrip

Broadus

Gillette

Buffalo

Wright

Miles City

Douglas

Casper

Moorcroft

Decker

Colstrip

Broadus

Ashland

Forsyth

Lame Deer

Casper

Wright

Glenrock

Sheridan

ANTELOPE MINE

NORTH ANTELOPE/

ROCHELLE MINE

JACOBS RANCH MINE

BLACK THUNDER MINE

CORDERO ROJO MINE

COAL CREEK

MINE

WYODAK MINE

DRY FORK

MINE

BUCKSKIN MINE

BELLE AYR MINE

CABALLO MINE

RAWHIDE MINE

ROSEBUD

MINE ABSALOKA

MINE

BIG SKY MINE (ABANDONED)

SPRING CREEK MINE

DECKER MINES

DAVE JOHNSTON MINE (ABANDONED)

BIG HORN MINE

EAGLE BUTTE MINE

CARTER

COUNTY

CROOK COUNTY

NIOBRARA

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

WESTON

COUNTY

NATRONA

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Gillette coal field

assessment area

(OFR-2008-1202)

Northern Wyoming

Powder River Basin

assessment area

(USGS OFR-2010-1294)

Montana Powder

River Basin

assessment area

(USGS OFR-2012-1111)

Southwestern Wyoming

Powder River Basin

assessment area

(USGS OFR-2011-1134)

Southwestern 

Belco lease area

Stevens North lease area

Stevens South lease area

East Gillette

coal field

extension

Stevens South lease area

PSO lease area

Otter Creek lease area

\\IGSKAHCMVSFS002\PbsCommon\Jeff\den14hdaa100122lppens\reportfigre02ai
Figures 55

Figure 3. Map showing structure contours drawn on the top of the Tullock Member of the Fort Union Formation.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

POWDER RIVER COUNTY

CROOK COUNTY CAMPBELL

COUNTY

WESTON

COUNTY

NATRONA

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

MONTANA

WYOMING

750

1,250

1,500

1,750

2,000

2,250

2,500

2,750

1,000

500

3,000

250

0

–500

–250

–750

–1,000

–1,250

3,000

4,000

4,500

4,250

4,000

3,750

3,500 3,000

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

EXPLANATION

Contour (feet) 

Basin axis 

Contour interval = 250 feet (76 meters)

3,000

Powder

River

Basin
56 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 4. Map showing generalized surface geology of the Powder River Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

BIG HORN COUNTY

TREASURE

COUNTY ROSEBUD COUNTY CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

NIOBRARA

COUNTY

CONVERSE

COUNTY

NATRONA

COUNTY

CARTER

COUNTY

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Basin axis (approximately 

 where dashed) 

Quaternary alluvium and terrace 

 deposits

Tertiary White River Formation

Tertiary Wasatch Formation

Tongue River Member 

Tullock Member 

Tertiary Fort Union Formation 

 (undifferentiated)

EXPLANATION

Lebo Shale Member

Tongue River and Lebo Shale 

 Members 

Tft

Tfl

Tftrl

Tftr

Tfu

Tw

Twr

Qal

Tftr

Tw

Tftrl

Tfu

Tft

Qal

Twr Twr

Tfl

Powder

River

Basin

WYOMING

MONTANA
Figures 57

Figure 5. Generalized stratigraphic column for the Powder River Basin, Wyoming and 

Montana.

Wyoming Montana

Quaternary

Age

Stratigraphic units in the

Powder River Basin

Late

 Cretaceous

Tertiary

Wasatch Formation

Lance Formation Hell Creek Formation

Fox Hills Sandstone

Bearpaw Shale

Mesaverde Formation

Pierre Shale

Tongue River Member

Lebo Shale Member Fort Union

Formation

Eocene

Oligocene

Paleocene

White River Formation

Surficial deposits

Tullock Member

Cody Shale

Niobrara Formation

Carlile Shale

Greenhorn Formation

Belle Fourche Shale

Mowry Shale

Muddy Sandstone

Thermopolis Shale

Fall River Formation

Lakota Formation

Frontier Formation

Early

Cretaceous

Cretaceous

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_05.ai
58 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 6. Map showing location of coal fields in the Powder River Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

CUSTER COUNTY

FALLON

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

ROSEBUD COUNTY

CARTER

COUNTY

POWDER RIVER COUNTY

CROOK COUNTY

CAMPBELL

COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

CUSTER COUNTY

FALLON

COUNTY

NIOBRARA

COUNTY

CONVERSE

COUNTY

NATRONA

COUNTY

ROSEBUD COUNTY

Little Powder

River coal

field Powder 

River

coal

field

Moorhead coal field

North Extension

Sheridan coal field

Sheridan coal field

Spotted

Horse

coal field

Gillette

coal field

Buffalo coal field

Barber

coal

field

Sussex coal field

Pumpkin

Buttes

coal

field East 

Gillette

coal field

extension

Forsyth coal field

Ashland coal field

Coalwood coal field

Birney-Broadus coal field

Miles City coal field

Rosebud coal field

Mizpah coal field

Dry Cheyenne

coal field

Lost Spring

coal field

Glenrock coal field

Powder

River

Basin
Figures 59

Figure 7. Map showing location of significant clinker in the Powder River Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

SHERIDAN

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

POWDER

RIVER

 COUNTY

NIOBRARA

COUNTY

WESTON

COUNTY

NATRONA

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

CONVERSE

COUNTY

CAMPBELL

COUNTY

CARTER

COUNTY

CROOK COUNTY

CAMPBELL

COUNTY

WESTON

COUNTY

NATRONA

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

MONTANA

WYOMING

Clinker

(burned coal)

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 30 10 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Powder

River

Basin

Powder

River

Basin

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_07.ai
Figure 8. West-east cross section A–A’ showing subsurface distribution of significant coal beds through the southern part of the Powder River Basin

0 10 20 MILES 0 10 20 KILOMETERS 2,000 3,000 4,000 5,000 ELEVATION ABOVE SEA LEVEL (FEET) 1,000 A Southwestern Wyoming Powder River Basin Wyodak-Anderson coal zone (Flores and Bader, 1999b) Smith (Big George) Werner Rosebud/Knobloch Axis of the basin Gates/Wall 

Roland (Baker) Smith Canyon Lower Canyon An

Dietz 3 

Flowers-Goodale Roberts/Terret Wyodak-Anderson coal zone (Flores and Bader, 1999b) Gillette coal field 

Approximate land surface Felix
Figure 9. West-east cross section B–B’ showing subsurface distribution of significant coal beds through the central part of the Powder River Basin, 

0 10 20 MILES

0 10 20 KILOMETERS

2,000 3,000 4,000 

ELEVATION

ABOVE

SEA LEVEL

(FEET)

1,000 

B 

Roland (Baker)

Smith

Anderson

Dietz 3

Canyon

Lower Canyon

Werner

Gates/Wall

Pawnee

Rosebud/Knobloch

Roberts/Terret

Axis of the basin

Approximate land surface

Wyodak-Anderson

coal zone

(Flores and Bader, 1999b)
Figure 10. North-south cross section C–C’ showing subsurface distribution of significant coal beds through the Powder River Basin, Wyoming and 

0 10 20 MILES 0 10 20 KILOMETERS 2,000 3,000 4,000 5,000 ELEVATION ABOVE SEA LEVEL (FEET) 1,000 A

Felix Dietz 3 A

Werner Gates/Wall Pawnee Rosebud/Knobloch Flowers-Goodale Roberts/Terret Wyodak-Anderson coal zone (Flores and Bader, 1999b) Wyodak-Anderson coal zone (Flores and Bader, 1999b) Canyon Roland (Baker) Lower Canyon MONTANA WYOMING C 

Smith
Figures 63

Figure 11. Map showing approximate location of faults within the Powder River Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 30 10 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Faults (approximate)

Basin axis

(approximate

where dashed)

Powder

River

Basin

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_11.ai
64 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 12. Map showing locations of mines, lease areas, and average coal quality basis within the Powder River Basin, 

Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER

RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

1

2

3

5

4

ABSALOKA MINE

ROSEBUD MINE

BIG SKY MINE

(abandoned)

SPRING CREEK MINE

DECKER MINES

BIG HORN MINE

(abandoned)

DAVE JOHNSTON MINE

 (abandoned)

ANTELOPE MINE

NORTH ANTELOPE/

ROCHELLE MINE

JACOBS RANCH MINE

(abandoned)

BLACK THUNDER MINE

CORDERO ROJO MINE

COAL CREEK MINE

(abandoned)

WYODAK MINE

DRY FORK MINE

BUCKSKIN MINE

BELLE AYR MINE

CABALLO MINE

RAWHIDE MINE

EAGLE BUTTE MINE

Stevens North

lease area

Stevens South

lease area

PSO lease area

British thermal unit per pound 

 average=8,750

Ash average=8.80 percent

Sulfur average=0.75 percent

Sheridan coal field area

Decker/Spring Creek area

Colstrip area

Gillette coal field/north

Gillette coal field/middle

Lake DeSmet area

Otter Creek lease area

Sheridan coal field area

Decker/Spring Creek area

Colstrip area

Glenrock coal field

Gillette coal field/north

Gillette coal field/middle

Lake DeSmet area

Otter Creek lease area

Gillette coal field/south

British thermal unit per pound 

 average=9,400

Ash average=4.15 percent

Sulfur average=0.39 percent

British thermal unit per pound 

 average=8,110

Ash average=5.50 percent

Sulfur average=0.15 percent

British thermal unit per pound 

 average=9,300

Ash average=5.7 percent

Sulfur average=0.60 percent

British thermal unit per pound 

 average=6,800

Ash average=15.0 percent

Sulfur average=0.70 percent

British thermal unit per pound 

 average=7,581

Ash average=12.1 percent

Sulfur average=0.45 percent

British thermal unit per pound 

 average=8,807

Ash average=5.43 percent

Sulfur average=0.28 percent

British thermal unit per pound 

 average=8,459

Ash average=5.86 percent

Sulfur average=0.35 percent

British thermal unit per pound 

 average=8,203

Ash average=6.29 percent

Sulfur average=0.39 percent Belco

lease

area

Lake

DeSmet

Powder

River

Basin

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_12.ai
Figure 13. Coal bed and coal zone names used in this assessment and previous publications in the Powder River Basin, Wy

Formation

name

Kent

and others

(1980)

Pierce 

and others

(1990)

Flores

and others

(1999)

Gillette coal field, 

Luppens and others

(2008)

Northern Wyoming 

Powder River Basin, 

Scott and others 

(2010)

Southwestern Wyoming 

Powder River Basin, 

Osmonson and others 

(2011)

Montana 

Powder River Basin, 

Haacke and others 

(2013)

Coal bed names

Wasatch Upper Healy Upper Healy, Healy 

Healy Murray 

Ucross Ucross 

Upper Felix 

Felix Felix Felix Felix 

Lower Felix Lower Felix 

Fort Union

(Tongue

River

Member)

Roland (Upper Rider) Roland (Upper Rider) 

Roland (Lower Rider) 

Smith Roland/Badger Roland Roland (Baker, 1929) Roland (Baker, 1929) Roland (Baker, 1929) 

Roland (Taff, 1909) Roland (Taff, 1909) 

Wyodak or

Upper Wyodak

(Anderson/

Canyon)

Wyodak-Anderson

coal zone=Smith 

(Swartz), Badger, 

School, Sussex,

Big George, Wyodak, 

Anderson, Dietz, 

Canyon (Monarch), 

Werner

Smith Smith Smith Smith 

Anderson Rider 

Upper

Wyodak

Anderson Anderson Anderson Anderson 

Lower Anderson 

Dietz 1 Dietz 1 Dietz 2 Dietz 2 

Dietz Dietz 3 Dietz 3 Dietz 3 

Dietz 4 Dietz 4 

Upper Canyon Cox 

Canyon Canyon Canyon Canyon Canyon 

Lower Canyon Lower Canyon Lower Canyon 

Ferry Ferry 

Werner Lower Wyodak Werner Werner Werner Werner/Cook 

Otter Otter Otter 

Gates/Kennedy Upper Kennedy Gates Gates Gates Gates/Wall 

Pawnee Pawnee Pawnee Pawnee 

Brewster-Arnold 

Odell Odell 

Cache 

Rosebud Dietz 1 Rosebud/Knobloch 

Calvert 

McKay Dietz 2 McKay/Nance 

Dietz 3 Flowers-Goodale 

Upper Witham 

Robinson Robinson/Witham 

Roberts Roberts Roberts/Terret 
66 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 14. Flow chart showing generalized U.S. Geological Survey 

methodology used for coal resource and reserve assessment.

Correlate coal beds

Create coal bed models

Create land-use and technical restrictions by bed

1.

2.

3.

1.

2.

3.

4. 

Coal bed geology (extent, thickness, partings, structure,

overburden)

Factors affecting extraction of coal (land-use and technical

restrictions)

State and county jurisdiction and coal ownership

Coal quality information, coal sales price, tax information 

Calculate tonnages and areas for original, mined out,

restricted and available resources by bed 

Create mine models (by stripping ratio)

Calculate available resources by mine model

Calculate mining costs by mine model 

1.

2.

3.

4.

PHASE THREE—RESOURCE/RESERVE ASSESSMENT

PHASE TWO—GEOLOGIC AND GEOGRAPHIC

 INFORMATION SYSTEM MODELING

PHASE ONE—DATA COLLECTION 

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_14.ai
Figures 67

Figure 15. Map showing mines and nonproprietary drill holes and paleochannels within the Anderson coal bed in the Powder River 

Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Drill hole location (approximate)

Mine location (approximate)

EXPLANATION

Paleo channel areas (approximate)

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Powder

River

Basin

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_07.ai
Figure 16. Cross section A–A’ showing correlations used in the U.S. Geological Survey Miscellaneous Investigations Series Map I–1959–D by Molnia and P

A 

B B' 

40-005-33013

Upper Wyodak

(Anderson)

Lower Wyodak

(Canyon)

Felix

Roland

49-005-24358

Oil and gas well 

substituted 

for original well

49-005-23052

49-005-24213

Total distance is approximately 9.0 miles (14.5 km)

Total distance is approximately

20.5 miles (30.0 kilometers)
Figure 17. Cross section B–B’ showing comparison of coal bed correlations made in the Gillette coal field report to the U.S. Geological Survey MiscellaMap I–1959–D by Molnia and Pierce (1992).

B 

B’

Gillette

B

Gillette

coal field

Wright

B'

LOCATION MAP

1.2 Miles

Lower Wyodak

(1959-D publication)

(dashed line)

Uppe

(1959-D 

(das

Canyon

Anderson

Smith

Roland

R

Nine drill holes added to 1959-D publication to show difference in correlations

(Total distance is approximately 9.0 miles (14.5 km)

49-005-44226

49-005-45557

49-005-45558

49-005-45555

49-005-33615

49-005-32817

49-005-35092

49-005-46566

49-005-50753

49-005-24358

Felix

Oil and 

substit

origin

Original well from

1959-D publication

(See figure 16)
70 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 18. Isopach map showing combined thickness of the Smith, Anderson, and Canyon coal beds and areas of thin or 

absent coal (“want area” after Flores and others, 2010) within the Powder River Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

5

25

50

75

100

125

150

200

250 

300 and greater

Mine area

Thickness (feet)

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Powder

River

Basin

“Want Area”

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_18.ai
Figures 71

Figure 19. Map showing land-use restrictions in the Powder River, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

MONTANA

WYOMING

§ ̈¦90

§ ̈¦25

§ ̈¦25

§ ̈¦90

§ ̈¦94

§ ̈¦90

§ ̈¦94

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

 Alluvial valley floor

Area of joint line box cut offset

 Mine area

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Powder

River

Basin

Broadus Airport

 Montana Fish, Wildlife,

 and Parks Conservation

 Easement

 Twelve Mile DamMontana Fish, Wildlife, 

and Parks

 Montana Land Reliance

Conservation Easement

 Twelve Mile DamMontana Fish, Wildlife, 

and Parks

 FORT KEOGH NATIONAL

 WILDLIFE REFUGE

 Montana Land Reliance

Conservation Easement

 Custer National Forest

 ROSEBUD

BATTLEFIELD

 STATE PARK

 TONGUE RIVER RESERVOIR

 AND STATE PARK

 WOLF MOUNTAINS

BATTLESITE

 NATIONAL HISTORIC

LANDMARK

THUNDER BASIN

NATIONAL GRASSLANDS

BURLINGTON NORTHERN

SANTA FE RAILROAD

THUNDER BASIN

NATIONAL

GRASSLANDS

 Hilight Gas

 Plant

THUNDER BASIN

NATIONAL

GRASSLANDS

 Hilight Gas

 Plant

BURLINGTON

NORTHERN

SANTA FE AND

UNION PACIFIC

RAILROADS

 Lake DeSmet

Yellowstone R

North Platte RNorth Platte R

Bell Fouche River Bell Fouche River

Miles City

Broadus

Colstrip

Decker

Clearmont

Sheridan

Buffalo Gillette

Wright

Rolling Hills

Glenrock

Casper

Douglas

Ranchester

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_19.ai
72 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 20. Map showing coal mineral estate ownership in the Powder River Basin, Wyoming and Montana.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Private coal 

State coal 

Federal coal

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Powder

River

Basin

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_20.ai
Figure 21. Illustration showing the effect of coal-bed depth upon restricted resource because of mine-pit highwall setback requirements.

Coal bedMine accessible coal-bearing rock Additional restriction due to required mine  pit highwall angle (coal unavailable  for mining) Surface restriction and buffer projected  downward (coal unavailable for mining)

Restriction to mining

EXPLANATION

Horizontal limits of vertically projected 

Mine bench surface restriction and buffer Mine bench

Surface

restriction

Buffer distance Buffer distance

2,144 feet

300 feet 300 feet

26° 26°

500 feet

200 feet

858 feet

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_21.ai
74 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 22. Map showing location of areas of low, moderate, and high coalbed methane potential in the Powder River 

Basin, Wyoming and Montana.

Campbell

Powder River

Birney

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER RIVER COUNTY DER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA

COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Powder

River

Basin

Area of low estimated

coalbed methane 

potential

Area of moderate

estimated coalbed

methane potential

Area of high

estimated coalbed 

methane potential

Area of low estimated

coalbed methane 

potential

Area of low estimated

coalbed methane 

potential

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_22.ai
Figures 75

Figure 23. Coal bed stratigraphy, original and available resources, and maximum and average thicknesses for coal beds 

in the Powder River Basin, Wyoming and Montana.

Coal bed stratigraphy, original and available resources, and thickness

Formation

name

Coal beds

identified in 

this assessment

Original

resources

calculate

(millions of tons)

Available

resources

calculated

(millions of tons)

Maximum

thickness

(feet)

Average

thickness

(feet)

Wasatch

Upper Healy 6,863 5,327 17 12

Healy/Lower Ulm 13,004 10,738 83 14

Murray 2,664 599 14 3

Ucross 6,808 4,492 40 7

Upper Felix 2,122 1,205 19 4

Felix 18,759 16,784 55 12

Lower Felix 19,385 14,929 53 7

Fort Union

(Tongue River

Member)

Roland Upper Rider 13,506 8,304 32 4

Roland Lower Rider 3,257 1,693 20 4

Roland (Baker, 1929) 47,774 43,336 40 10

Roland (Taff, 1909) 3,403 1,290 27 3

Upper Smith 1,036 430 36 3

Wyodak-Anderson coal zone

Smith 126,433 122,868 278 24

Anderson Upper Rider 272 44 18 3

Anderson Lower Rider 755 480 20 8

Anderson 125,481 101,825 225 24

Lower Anderson 3,382 2,039 44 4

Dietz 1 1,138 495 29 4

Dietz 2 2,992 2,032 37 6

Dietz 3 50,880 45,063 119 13

Dietz 4 1,765 807 20 3

Upper Canyon/Cox 5,968 4,711 31 7

Canyon 147,450 135,454 183 21

Lower Canyon 59,528 52,056 85 11

Upper Ferry 814 464 10 4

Ferry 6,396 4,277 28 5

Werner/Cook 73,986 63,353 90 13

Upper Otter 919 604 21 4

Otter 71,021 64,310 170 14

Gates/Wall 66,426 57,851 125 9

Pawnee 24,498 16,964 34 7

Brewster-Arnold 1,968 475 19 5

Odell 11,676 6,581 26 4

Cache 3,303 809 26 3

A Zone 111 15 9 3

Upper Rosebud/S1 209 54 15 3

Rosebud/Knobloch 64,401 47,091 73 12

Calvert 1,162 196 18 3

McKay/Nance 33,289 22,614 36 5

Lower McKay/S2 190 1 7 3

Flowers-Goodale 60,544 51,064 40 8

Upper Witham 117 68 29 4

Robinson/Witham 20,677 15,007 41 7

Roberts/Terret 51,866 44,467 42 8

Burley 1,632 684 10 3

Upper Stag 1,870 790 13 3

Lower Stag 151 11 6 3

TOTAL TONS 1,161,851 974,751
76 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 24. Isopach map of the Upper Healy coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

TREASURE

COUNTY CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

1

5

10

20

40

60

80

EXPLANATION

Thickness (feet)

Powder

River

Basin

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_24.ai
Figures 77

Figure 25. Map showing depth to the top of the Upper Healy coal bed within the Powder River Basin.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

Powder

River

Basin

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_19.ai
78 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 26. Isopach map of the Healy/Lower Ulm coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_26.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100

Powder

River

Basin
Figures 79

Figure 27. Map showing depth to the top of the Healy/Lower Ulm coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_27.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Depth to top of coal

 in feet

EXPLANATION

Basin axis

1

250

500

1,000

1,500

Powder

River

Basin

Powder
80 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 28. Isopach map of the Murray coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_28.ai

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

Thickness in feet

EXPLANATION

1

5

10

20

LOCATION MAP

Powder

River

Basin

Powder
Figures 81

Figure 29. Map showing depth to the top of the Murray coal bed within the Powder River Basin.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_29.ai

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Depth to top of coal

 in feet

EXPLANATION

Basin axis

1

250

500

1,000

1,500

Powder

River

Basin

Powder
82 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 30. Isopach map of the Ucross coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_30.ai

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 83

Figure 31. Map showing depth to the top of the Ucross coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_31.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

Basin axis

1

250

500

1,000

1,500

Powder

River

Basin

Powder
84 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 32. Isopach map of the Upper Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_32.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

Powder

River

Basin

Powder
Figures 85

Figure 33. Map showing depth to the top of the Upper Felix coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_33.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

Basin axis

1

250

500

1,000

Powder

River

Basin

Powder
86 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 34. Isopach map of the Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_34.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

Powder

River

Basin

Powder
Figures 87

Figure 35. Map showing depth to the top of the Felix coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_35.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
88 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 36. Isopach map of the Lower Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_36.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

Powder

River

Basin

Powder
Figures 89

Figure 37. Map showing depth to the top of the Lower Felix coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_37.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
90 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 38. Isopach map of the Roland (Upper Rider) coal bed showing extent of coal at least 1.0 foot thick within the Powder 

River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_38.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 91

Figure 39. Map showing depth to the top of the Roland (Upper Rider) coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_39.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
92 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 40. Isopach map of the Roland (Lower Rider) coal bed showing extent of coal at least 1.0 foot thick within the Powder 

River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_40.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

Powder

River

Basin

Powder
Figures 93

Figure 41. Map showing depth to the top of the Roland (Lower Rider) coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_41.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
94 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 42. Isopach map of the Roland (Baker) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_42.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 95

Figure 43. Map showing depth to the top of the Roland (Baker) coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_43.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
96 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 44. Isopach map of the Roland (Taff) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_44.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 97

Figure 45. Map showing depth to the top of the Roland (Taff) coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_45.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
98 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 46. Isopach map of the Upper Smith coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_46.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 99

Figure 47. Map showing depth to the top of the Upper Smith coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_47.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
100 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 48. Isopach map of the Smith coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_48.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100 and greater

Powder

River

Basin

Powder
Figures 101

Figure 49. Map showing depth to the top of the Smith coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_49.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
102 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 50. Isopach map of the Anderson Upper Rider coal bed showing extent of coal at least 1.0 foot thick within the Powder 

River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_50.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

Powder

River

Basin

Powder
Figures 103

Figure 51. Map showing depth to the top of the Anderson Upper Rider coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_51.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
104 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 52. Isopach map of the Anderson Lower Rider coal bed showing extent of coal at least 1.0 foot thick within the Powder 

River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_52.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

Powder

River

Basin

Powder
Figures 105

Figure 53. Map showing depth to the top of the Anderson Lower Rider coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_53.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
106 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 54. Isopach map of the Anderson coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_54.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100 and greater

Powder

River

Basin

Powder
Figures 107

Figure 55. Map showing depth to the top of the Anderson coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_55.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
108 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 56. Isopach map of the Lower Anderson coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_56.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

Powder

River

Basin

Powder
Figures 109

Figure 57. Map showing depth to the top of the Lower Anderson coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_57.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
110 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 58. Isopach map of the Dietz 1 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_58.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 111

Figure 59. Map showing depth to the top of the Dietz 1 coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_59.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
112 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 60. Isopach map of the Dietz 2 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_60.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 113

Figure 61. Map showing depth to the top of the Dietz 2 coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_61.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
114 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 62. Isopach map of the Dietz 3 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_62.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100 and greater

Powder

River

Basin

Powder
Figures 115

Figure 63. Map showing depth to the top of the Dietz 3 coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_63.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
116 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 64. Isopach map of the Dietz 4 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_64.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

Powder

River

Basin

Powder
Figures 117

Figure 65. Map showing depth to the top of the Dietz 4 coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_65.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
118 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 66. Isopach map of the Upper Canyon (Cox) coal bed showing extent of coal at least 1.0 foot thick within the Powder 

River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_66.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 119

Figure 67. Map showing depth to the top of the Upper Canyon (Cox) coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_67.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
120 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 68. Isopach map of the Canyon coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_68.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100 and greater

Powder

River

Basin

Powder
Figures 121

Figure 69. Map showing depth to the top of the Canyon coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_69.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
122 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 70. Isopach map of the Lower Canyon coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_70.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100

Powder

River

Basin

Powder
Figures 123

Figure 71. Map showing depth to the top of the Lower Canyon coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_71.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
124 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 72. Isopach map of the Upper Ferry coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_72.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

Powder

River

Basin

Powder
Figures 125

Figure 73. Map showing depth to the top of the Upper Ferry coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_73.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Depth to top of coal

 in feet

EXPLANATION

Basin axis

1

250

500

1,000

1,500

Powder

River

Basin

Powder
126 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 74. Isopach map of the Ferry coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_74.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100

Powder

River

Basin

Powder
Figures 127

Figure 75. Map showing depth to the top of the Ferry coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_75.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
128 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 76. Isopach map of the Werner/Cook coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_76.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100 and greater

Powder

River

Basin

Powder
Figures 129

Figure 77. Map showing depth to the top of the Werner/Cook coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_77.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
130 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 78. Isopach map of the Upper Otter coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_78.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 131

Figure 79. Map showing depth to the top of the Upper Otter coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_79.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

Basin axis

4,000

3,000

2,500

500

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
132 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 80. Isopach map of the Otter coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_80.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100 and greater

Powder

River

Basin

Powder
Figures 133

Figure 81. Map showing depth to the top of the Otter coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_81.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
134 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 82. Isopach map of the Gates/Wall coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_82.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100 and greater

Powder

River

Basin

Powder
Figures 135

Figure 83. Map showing depth to the top of the Gates/Wall coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_83.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
136 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 84. Isopach map of the Pawnee coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_84.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 137

Figure 85. Map showing depth to the top of the Pawnee coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_85.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
138 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 86. Isopach map of the Brewster-Arnold coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_86.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

Powder

River

Basin

Powder
Figures 139

Figure 87. Map showing depth to the top of the Brewster-Arnold coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_87.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
140 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 88. Isopach map of the Odell coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_88.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 141

Figure 89. Map showing depth to the top of the Odell coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_89.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
142 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 90. Isopach map of the Cache coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_90.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

100

Powder

River

Basin

Powder
Figures 143

Figure 91. Map showing depth to the top of the Cache coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_91.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
144 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 92. Isopach map of the A Zone coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_92.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

Powder

River

Basin

Powder
Figures 145

Figure 93. Map showing depth to the top of the A Zone coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_93.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Depth to top of coal

 in feet

EXPLANATION

Basin axis

1

250

500

1,000

Powder

River

Basin

Powder
146 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 94. Isopach map of the Upper Rosebud coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_94.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

Powder

River

Basin

Powder
Figures 147

Figure 95. Map showing depth to the top of the Upper Rosebud coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_95.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

Basin axis

1

250

500

1,000

Powder

River

Basin

Powder
148 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 96. Isopach map of the Rosebud/Knobloch coal bed showing extent of coal at least 1.0 foot thick within the Powder 

River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_96.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

80

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
Figures 149

Figure 97. Map showing depth to the top of the Rosebud/Knobloch coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_97.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
150 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 98. Isopach map of the Calvert coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_98.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
Figures 151

Figure 99. Map showing depth to the top of the Calvert coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_99.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
152 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 100. Isopach map of the McKay/Nance coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_100.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
Figures 153

Figure 101. Map showing depth to the top of the McKay/Nance coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_101.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
154 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 102. Isopach map of the Lower McKay coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_102.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
Figures 155

Figure 103. Map showing depth to the top of the Lower McKay coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_103.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
156 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 104. Isopach map of the Flowers-Goodale coal bed showing extent of coal at least 1.0 foot thick within the Powder 

River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_104.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 157

Figure 105. Map showing depth to the top of the Flowers-Goodale coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_105.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

Powder

River

Basin

Powder

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL

COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000
158 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 106. Isopach map of the Upper Witham coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_106.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder
Figures 159

Figure 107. Map showing depth to the top of the Upper Witham coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_107.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

Powder

River

Basin

Powder
160 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 108. Isopach map of the Robinson/Witham coal bed showing extent of coal at least 1.0 foot thick within the Powder 

River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_100.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
Figures 161

Figure 109. Map showing depth to the top of the Robinson/Witham coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_109.ai

Rosebud

Creek

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD

COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder

Little Wolf Mountains,

approximate trend
162 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 110. Isopach map of the Roberts/Terret coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_110.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE

COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

20

40

60

Powder

River

Basin

Powder
Figures 163

Figure 111. Map showing depth to the top of the Roberts/Terret coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_111.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE

COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
164 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 112. Isopach map of the Burley coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_112.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

Powder

River

Basin

Powder
Figures 165

Figure 113. Map showing depth to the top of the Burley coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_113.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
166 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 114. Isopach map of the Upper Stag coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_114.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

Thickness in feet

EXPLANATION

1

5

10

20

LOCATION MAP

Powder

River

Basin

Powder
Figures 167

Figure 115. Map showing depth to the top of the Upper Stag coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_115.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

4,000

3,000

2,500

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
168 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 116. Isopach map of the Lower Stag coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_116.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

EXPLANATION

1

5

10

Powder

River

Basin

Powder
Figures 169

Figure 117. Map showing depth to the top of the Lower Stag coal bed within the Powder River Basin.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_117.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

EXPLANATION

Depth to top of coal

 in feet

500

Basin axis

1

250

1,000

1,500

2,000

Powder

River

Basin

Powder
170 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 118. Pie diagram showing tonnages and percentages of individual coal beds in relation to the total 1.16 trillion short tons of 

original resources in the Powder River Basin, Wyoming and Montana.

Gates/Wall

66 billion short tons

5.7 percent

Rosebud/Knobloch

64 billion short tons

5.5 percent

Flowers-Goodale

61 billion short tons

5.2 percent

Roberts/Terret

52 billion short tons

4.5 percent

Remaining 35 beds

216 billion short tons

18.6 percent

Roland (Baker)

48 billion short tons

4.1 percent

Smith

126 billion short tons

10.9 percent

Anderson

125 billion short tons

10.8 percent

Dietz 3

50 billion short tons

4.4 percent

Canyon

147 billion short tons

12.7 percent

Lower Canyon

60 billion short tons

5.1 percent

Werner/Cook

74 billion short tons

6.4 percent

Otter

71 billion short tons

6.1 percent

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_118.ai
Figures 171

Figure 119. Isopach map of the Flowers-Goodale coal bed showing extent of resources at least 1.0 foot thick and location of lineaments 

described by Jones, 2010a, in the Powder River Basin, Wyoming and Montana.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_119.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

Lineament data modified from Jones (2010a)

2010 30 40 MILES

CONVERSE

COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK

COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK

COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

Powder

River

Basin

Powder

Cross Creek

Belle Creek

Big Horn/Custer

Parkman/Baker

Tensleep/Harding

LM

Springen Ranch

RozetWeston/Hat Creek

Sussex/Osage

South Coyote Creek

Gose Butte

Fiddler Creek

Clareton Trend

Black Butte

Buffalo/Douglas

Lightning Creek

Arminto/Upton

Natrona/Ross

Casper/Bill

Orpha/Redbird Gillette/Keeline

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

Lineament and identifier

EXPLANATION

1

5

10

20

40

Rozet
172 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 120. Isopach map of the Roberts/Terret coal bed showing extent of resources at least 1.0 foot thick and location of lineaments 

described by Jones, 2010a, in the Powder River Basin, Wyoming and Montana.

SKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_120.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE

COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK

COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK

COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

Powder

River

Basin

Powder

Cross Creek

Belle Creek

Big Horn/Custer

Parkman/Baker

Tensleep/Harding

LM

Springen Ranch

RozetWeston/Hat Creek

Sussex/Osage

South Coyote Creek

Gose Butte

Fiddler Creek

Clareton Trend

Black Butte

Buffalo/Douglas

Lightning Creek

Arminto/Upton

Natrona/Ross

Casper/Bill

Orpha/Redbird Gillette/Keeline

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

Lineament and identifier

EXPLANATION

Rozet

Lineament data modified from Jones (2010a)

1

5

10

20

40

60
Figures 173

Figure 121. Isopach map of the Smith, Anderson, and Canyon coal beds showing extent of resources at least 5 feet thick and location 

of lineaments described by Jones, 2010a in the Powder River Basin, Wyoming and Montana.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_121.ai

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

T. 3 N.

T. 5 N.

T. 7 N.

T. 33 N.

T. 35 N.

T. 37 N.

T. 39 N.

T. 41 N.

T. 43N.

T. 45 N.

T. 47 N.

T. 49 N.

T. 51 N.

T. 53N.

T. 55 N.

T. 57 N.

T. 9 S.

T. 7 S.

T. 5 S.

T. 3 S.

T. 1 N.

T. 1 S.

R. 35 E. R. 37 E. R. 39 E. R. 41 E. R. 43 E. R. 45 E. R. 47 E. R. 49 E. R. 51 E. R. 53 E. R. 55 E. R. 57 E.

R. 87 W. R. 85 W. R. 83 W. R. 81 W. R. 79 W. R. 77 W. R. 75 W. R. 73 W. R. 71 W. R. 69 W. R. 67 W. R. 65 W.

0 20 3010 40 KILOMETERS 

Base modified from U.S. Geological Survey and other 0

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

CONVERSE

COUNTY

TREASURE

COUNTY

POWDER RIVER

COUNTY

CAMPBELL

COUNTY

CONVERSE

COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK

COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK

COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON

COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

MONTANA

WYOMING

Powder

River

Basin

Powder

Cross Creek

Belle Creek

Big Horn/Custer

Parkman/Baker

Tensleep/Harding

LM

Springen Ranch

RozetWeston/Hat Creek

Sussex/Osage

South Coyote

Creek

Gose Butte

Fiddler Creek

Clareton Trend

Black Butte

Buffalo/Douglas

Lightning Creek

Arminto/Upton

Natrona/Ross

Casper/Bill

Orpha/Redbird Gillette/Keeline

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Thickness in feet

Lineament and identifier

Mine area

EXPLANATION

Rozet

Lineament data modified from Jones (2010a)

100

5

25

50

75

125

150

200

250

300 and greater
174 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 122. Isopach map showing interburden thickness between the Anderson and Canyon coal beds in the Gillette coal field and 

location of lineaments described by Jones, 2010a in the Powder River Basin, Wyoming. \\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_122.ai

T. 53 N.

T. 52 N.

T. 51 N.

T. 50 N.

T. 49 N.

T. 48 N.

T. 47 N.

T. 45 N.

T. 44 N.

T. 43 N.

T. 42 N.

T. 41 N.

T. 40 N.

T. 39 N.

R. 76 W. R. 75 W. R. 74 W. R. 73 W. R. 72 W. R. 71 W. R. 70 W. R. 69 W. R. 68 W.

Buckskin

Rawhide

Eagle Butte

Dry Fork

Wyodak

Caballo

Belle Ayr

Cordero Rojo

Coal Creek

Jacobs Ranch

Black Thunder

North Antelope/

Rochelle

Antelope

T. 46 N.

Clareton Trend

LM

Arminto / Upton

Gose Butte

Buffalo / Douglas

Gillette / Keeline

Weston / Hat Creek

South Coyote Creek

Sussex / Osage

Rozet

Springen Ranch

Lightning Creek

Fiddler Creek

Black Butte

Tensleep/Harding

44°30’

44°00’

43°30’

105°45’ 105°15’

Wright

Gillette

CONVERSE COUNTY

CAMPBELL COUNTY

WESTON COUNTY

CAMPBELL COUNTY

0 5 10 15 20 KILOMETERS 

0 Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

5 10 15 20 MILES

WYOMING

MONTANA

Powder

River

Basin

Gillette coal field

LOCATION MAP

Thickness in feet

EXPLANATION

25

0

10

50

75

100

200

300

400

500

Gillette coal field boundary

Mine area and identifier

Rozet Lineament and identifier

Lineament data modified from Jones (2010a)

Anderson/Canyon merged
Figure 123. Generic cost curve showing 12.8 billion short tons (BST) reserve estimate at $13.20 per ton for the Powder River Basin, W

$0

$10$20$40$30$50$70$60

0 10 20 30 40 50 60 70 80 90 100 110 120 130 1

Current market price, in cost per ton

Cummulative tons reported in bllions of short tons (BST)

Reserve estimate at $18.00 per short ton

30 BST 60 BST

Reserve estimate

at $12.00 per

short ton
176 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 124. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Upper Anderson, Anderson, 

Dietz, and Canyon coal beds in the Gillette coal field, Wyoming Powder River Basin. \\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_124.ai

T. 53 N.

T. 52 N.

T. 51 N.

T. 50 N.

T. 49 N.

T. 48 N.

T. 47 N.

T. 45 N.

T. 44 N.

T. 43 N.

T. 42 N.

T. 41 N.

T. 40 N.

T. 39 N.

R. 76 W. R. 75 W. R. 74 W. R. 73 W. R. 72 W. R. 71 W. R. 70 W. R. 69 W. R. 68 W.

Buckskin

Rawhide

Eagle Butte

Dry Fork

Wyodak

Caballo

Belle Ayr

Cordero Rojo

Coal Creek

Jacobs Ranch

Black Thunder

North Antelope/

Rochelle

Antelope

T. 46 N.

44°30’

44°00’

43°30’

105°45’ 105°15’

CONVERSE

COUNTY

CAMPBELL

COUNTY

WESTON COUNTY

CAMPBELL COUNTY

0 5 10 15 20 KILOMETERS 

0 Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

5 10 15 20 MILES

WYOMING

MONTANA

Powder

River

Basin

Gillette coal

field

LOCATION MAP

Stripping ratio

EXPLANATION

3:1

1:1

Less than 1:1

2:1

4:1

5:1

6:1

7:1

8:1

9:1

10:1

1,000 feet depth to Canyon

 coal bed

Mine area and identifier

Gillette coal field boundary
Figure 125. Cost curve showing reserve estimates at $10.47 per short ton (as of January 2007) and $14.00 per short ton (as of March 2Wyoming.

$0

$10$20$40$30$50$70$60

0 10 20 30 40 50 60 

Current market price, in cost per ton

Reserve estimate at $14.00 per short ton

Reserve estimate

at $10.47 per

short ton

Cummulative tons reported in bllions of short tons (BST)

10.1 BST 18.5 BST
178 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 126. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Anderson, Dietz 3, 

Canyon, Lower Canyon, and Werner/Cook coal beds where the stripping ratios are from 1:1 to 10:1, thicknesses are equal 

to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Wyoming Powder River Basin.

MONTANA

WYOMING

CAMPBELL COUNTY

POWDER RIVER COUNTY

JOHNSON COUNTY

SHERIDAN COUNTY

BIG HORN

COUNTY

BIG HORN COUNTY

Sheridan

R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E.

T. 9 S.

T. 57 N.

T. 56 N.

T. 55 N.

T. 54 N.

T. 53 N.

T. 52 N.

T. 51 N.

T. 50 N.

T. 8 S.

R. 87 W. R. 86 W. R. 85 W. R. 84 W. R. 83 W. R. 82 W. R. 81 W. R. 80 W. R. 79 W. R. 78 W. R. 77 W. R. 76 W. R. 75 W. R. 74 W. R. 73 W. R. 72 W. R. 71 W. R. 70 W. R. 69 W. R. 68 W.

107°00’ 106°00’ 105°00’

45°30’

45°00’

Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983 0 15 2010 5 25 KILOMETERS 

0 5 1510 20 25 MILES

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_126.ai

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP

Stripping ratio

EXPLANATION

3:1

1:1

Less than 1:1

2:1

4:1

5:1

6:1

7:1

8:1

9:1

10:1 or greater

Mine area 

Northern Wyoming Powder

 River Basin assessment

 area boundary

Northern Wyoming

Powder River Basin
Figure 127. Cost curve showing 1.5 billion ton reserve estimate at $9.30 per short ton (as of February 2010) for Powder River Basin assessment area.

$0$5

$15$10$35$30$25$20

0 5 10 15 20 25 30 35 40 

Current market price, in cost per ton

$9.30

Reserve

Cummulative tons reported in bllions of short tons (BST)

1.5

Recoverable resource
180 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 128. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Anderson, Dietz 2, and Dietz 3 

coal beds where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or 

equal to 500 feet thick, in the Montana Powder River Basin.

Forsyth

Colstrip

Lame Deer Crow Agency

Lodge Grass

Miles City

POWDER RIVER COUNTY

CARTER

COUNTY

CUSTER COUNTY

FALLON

COUNTY

BIG HORN COUNTY

TREASURE COUNTY

ROSEBUD COUNTY

R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E.

T. 6 N. 

T. 7 N. 

T. 8 N. 

T. 5 N. 

T. 4 N. 

T. 3 N. 

T. 2 N. 

T. 1 N. 

T. 1 S. 

T. 2 S. 

T. 3 S. 

T. 4 S. 

T. 5 S. 

T. 6 S. 

T. 7 S. 

T. 8 S. 

T. 9 S. 

107°00’ 106°00’ 105°00’

45°30’

45°00’

46°00’

Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

CUSTER NATIONAL FOREST

0 2010 30 KILOMETERS 

0 10 20 30 MILES

WYOMING

MONTANA

Powder

River

Basin

Montana Power

River Basin

LOCATION MAP

Stripping ratio

EXPLANATION

1:1 through 5:1

>5:1 through 10:1

Montana Powder River

 Basin assessment

 area boundary

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_128.ai
Figures 181

Figure 129. Map showing areal extent for the stripping ratio of the Canyon coal bed where the stripping ratios are from 1:1 to 10:1, 

thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin.

Forsyth

Colstrip

Lame Deer Crow Agency

Lodge Grass

Miles City

POWDER RIVER COUNTY

CARTER

COUNTY

CUSTER COUNTY

FALLON

COUNTY

BIG HORN COUNTY

TREASURE COUNTY

ROSEBUD COUNTY

R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E.

T. 6 N. 

T. 7 N. 

T. 8 N. 

T. 5 N. 

T. 4 N. 

T. 3 N. 

T. 2 N. 

T. 1 N. 

T. 1 S. 

T. 2 S. 

T. 3 S. 

T. 4 S. 

T. 5 S. 

T. 6 S. 

T. 7 S. 

T. 8 S. 

T. 9 S. 

107°00’ 106°00’ 105°00’

45°30’

45°00’

46°00’

Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

CUSTER NATIONAL FOREST

0 2010 30 KILOMETERS 

0 10 20 30 MILES

WYOMING

MONTANA

Powder

River

Basin

Montana Power

River Basin

LOCATION MAP

Stripping ratio

EXPLANATION

1:1 through 5:1

>5:1 through 10:1

Montana Powder River

 Basin assessment

 area boundary

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_129.ai
182 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 130. Map showing areal extent for the stripping ratio of the Werner/Cook coal bed where the stripping ratios are from 1:1 to 10:1, 

thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin.

Forsyth

Colstrip

Lame Deer Crow Agency

Lodge Grass

Miles City

POWDER RIVER COUNTY

CARTER

COUNTY

CUSTER COUNTY

FALLON

COUNTY

BIG HORN COUNTY

TREASURE COUNTY

ROSEBUD COUNTY

R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E.

T. 6 N. 

T. 7 N. 

T. 8 N. 

T. 5 N. 

T. 4 N. 

T. 3 N. 

T. 2 N. 

T. 1 N. 

T. 1 S. 

T. 2 S. 

T. 3 S. 

T. 4 S. 

T. 5 S. 

T. 6 S. 

T. 7 S. 

T. 8 S. 

T. 9 S. 

107°00’ 106°00’ 105°00’

45°30’

45°00’

46°00’

Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

CUSTER NATIONAL FOREST

0 2010 30 KILOMETERS 

0 10 20 30 MILES

WYOMING

MONTANA

Powder

River

Basin

Montana Power

River Basin

LOCATION MAP

Stripping ratio

EXPLANATION

1:1 through 5:1

>5:1 through 10:1

Montana Powder River

 Basin assessment

 area boundary

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_130.ai
Figures 183

Figure 131. Map showing areal extent for the stripping ratio of the Pawnee coal bed where the stripping ratios are from 1:1 to 10:1, 

thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin.

Forsyth

Colstrip

Lame Deer Crow Agency

Lodge Grass

Miles City

POWDER RIVER COUNTY

CARTER

COUNTY

CUSTER COUNTY

FALLON

COUNTY

BIG HORN COUNTY

TREASURE COUNTY

ROSEBUD COUNTY

R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E.

T. 6 N. 

T. 7 N. 

T. 8 N. 

T. 5 N. 

T. 4 N. 

T. 3 N. 

T. 2 N. 

T. 1 N. 

T. 1 S. 

T. 2 S. 

T. 3 S. 

T. 4 S. 

T. 5 S. 

T. 6 S. 

T. 7 S. 

T. 8 S. 

T. 9 S. 

107°00’ 106°00’ 105°00’

45°30’

45°00’

46°00’

Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

CUSTER NATIONAL FOREST

0 2010 30 KILOMETERS 

0 10 20 30 MILES

WYOMING

MONTANA

Powder

River

Basin

Montana Power

River Basin

LOCATION MAP

Stripping ratio

EXPLANATION

1:1 through 5:1

>5:1 through 10:1

Montana Powder River

 Basin assessment

 area boundary

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_131.ai
184 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Figure 132. Map showing areal extent for the stripping ratio of the Rosebud/Knobloch coal bed where the stripping ratios are from 1:1 to 10:1, 

thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin.

Forsyth

Colstrip

Lame Deer Crow Agency

Lodge Grass

Miles City

POWDER RIVER COUNTY

CARTER

COUNTY

CUSTER COUNTY

FALLON

COUNTY

BIG HORN COUNTY

TREASURE COUNTY

ROSEBUD COUNTY

R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E.

T. 6 N. 

T. 7 N. 

T. 8 N. 

T. 5 N. 

T. 4 N. 

T. 3 N. 

T. 2 N. 

T. 1 N. 

T. 1 S. 

T. 2 S. 

T. 3 S. 

T. 4 S. 

T. 5 S. 

T. 6 S. 

T. 7 S. 

T. 8 S. 

T. 9 S. 

107°00’ 106°00’ 105°00’

45°30’

45°00’

46°00’

Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

CUSTER NATIONAL FOREST

0 2010 30 KILOMETERS 

0 10 20 30 MILES

WYOMING

MONTANA

Powder

River

Basin

Montana Power

River Basin

LOCATION MAP

Stripping ratio

EXPLANATION

1:1 through 5:1

>5:1 through 10:1

Montana Powder River

 Basin assessment

 area boundary

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_132.ai
Figures 185

Figure 133. Map showing areal extent for the stripping ratio of the Flowers-Goodale coal bed where the stripping ratios are from 1:1 to 10:1, 

thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin.

Forsyth

Colstrip

Lame Deer Crow Agency

Lodge Grass

Miles City

POWDER RIVER COUNTY

CARTER

COUNTY

CUSTER COUNTY

FALLON

COUNTY

BIG HORN COUNTY

TREASURE COUNTY

ROSEBUD COUNTY

R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E.

T. 6 N. 

T. 7 N. 

T. 8 N. 

T. 5 N. 

T. 4 N. 

T. 3 N. 

T. 2 N. 

T. 1 N. 

T. 1 S. 

T. 2 S. 

T. 3 S. 

T. 4 S. 

T. 5 S. 

T. 6 S. 

T. 7 S. 

T. 8 S. 

T. 9 S. 

107°00’ 106°00’ 105°00’

45°30’

45°00’

46°00’

Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

CUSTER NATIONAL FOREST

0 2010 30 KILOMETERS 

0 10 20 30 MILES

WYOMING

MONTANA

Powder

River

Basin

Montana Power

River Basin

LOCATION MAP

Stripping ratio

EXPLANATION

1:1 through 5:1

>5:1 through 10:1

Montana Powder River

 Basin assessment

 area boundary

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_133.ai
Figure 134. Graph showing cost curve for the Montana Powder River Basin assessment area showcoal resources compared to sales price per ton of coal. $0$5 $15 $10 $35 $30 $25 $200 5 10 15 20 25 30 

Current market price, in cost per ton

Cummulative tons reported in bllions of short tons (BST)

$13.20

12.8 BST
Figures 187

Figure 135. Bar graph showing resource and reserve summary in the Powder River Basin, Wyoming and Montana.

Powder

River

Basin

107°00’ 106°00’ 105°00’

46°00’

45°30’

45°00’

44°30’

44°00’

43°30’

43°00’

0 20 3010 40 KILOMETERS 

0 Base modified from U.S. Geological Survey and other

Federal digital data, various scales

Universal Transverse Mercator, zone 13N

North American Datum of 1983

2010 30 40 MILES

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den14_hdaa10_0122_luppens\report_figure_135.ai

Miles City

Douglas

Moorcroft

Forsyth

Casper

Total resources

In-place resources

Recoverable resources

Reserves

Total resources

In-place resources

Recoverable resources

Reserves

Total resources

In-place resources

Recoverable resources

Reserves

Total resources

In-place resources

Recoverable resources

Reserves

Total resources

In-place resources

Recoverable resources

Reserves

1,070

474

162

24.5

285

158

50

1.5

369

215

151

35

13

201

165

77

10

0

0

0

Powder River Basin total (billions of short tons)

Northern Wyoming Powder River Basin

(billions of short tons)

Southwestern Powder River Basin

(billions of short tons)

Montana Powder River Basin

(billions of short tons)

Gillette coal field 

(billions of short tons)

Mine

model

beds

Mine

model

beds

No beds modeled

Mine

model

beds

Mine

model

beds

 Northern Wyoming

Powder River Basin

Southwestern

Powder River Basin Gillette

coal field

Glenrock

CONVERSE COUNTY

TREASURE

COUNTY

POWDER RIVER COUNTY

CAMPBELL COUNTY

CONVERSE COUNTY

BIG HORN COUNTY

CUSTER COUNTY

FALLON

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

BIG HORN COUNTY

TREASURE

COUNTY

ROSEBUD COUNTY

CUSTER COUNTY

FALLON

COUNTY

CARTER

COUNTY

CROOK COUNTY

WESTON

COUNTY

WASHAKIE

COUNTY

JOHNSON COUNTY

SHERIDAN

COUNTY

BIG HORN

COUNTY

NIOBRARA

COUNTY

NATRONA COUNTY

Montana Powder

River Basin

Birney

Gillette

Sheridan

Buffalo

Decker

Colstrip

Broadus

Ashland

Lame Deer

Wright

MONTANA

WYOMING

WYOMING

MONTANA

Powder

River

Basin

LOCATION MAP
Figure 136. Graph showing cumulative cost curve for the Powder River Basin, Wyoming and Montana (Gillette coal field, Northern Wyoming PowMontana Powder River Basin assessment areas). $0 $40 $50 $30 $10 $20 $60 $70 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 

Current market price, in cost per ton

Cummulative tons reported in bllions of short tons (BST)

Platt’s price on 

July 15, 2013

Powder River Basin 

coal at 8,800 British thermal 

units per pound

Reserve estimate

at $10.90 per

short ton

Reserve estimate

at $15.15 per

short ton

Reserve estimate

at $8.90 per

short ton

10 BST 23 BST 43 BST
Tables

Tables 191

Table 1. 2012 and cumulative coal production from the Powder River Basin, Wyoming and Montana (reported in short tons).

Area/location/

mine name

Dates of 

operation

Coal bed 

mined

2012

production

Total 

production

Colstrip area, Montana

Absaloka Mine 1974–present Rosebud/Knobloch 1

2,714,064 2174,377,733

Big Sky Mine 1969–2004 Rosebud/Knobloch Not applicable 2

104,210,898

Rosebud Mine 1924–present Rosebud/Knobloch 1

8,018,098 2429,523,899

Total 1

10,732,162 2708,112,530

Decker/Spring Creek area, Montana

Decker Mine 1972–present Smith, Anderson, Dietz 3 1

2,758,248 2359,497,693

Spring Creek Mine 1979–present Smith, Anderson, Dietz 3 1

17,199,485 2282,958,133

Total 1

19,957,733 2642,455,826

Sheridan coalfield area, Wyoming

Big Horn Mine 1944–2000 Dietz 1, Dietz 2, Dietz 3 Not applicable 3

47,000,000

Other mines 1944–2000 Dietz 1, Dietz 2, Dietz 3 Not applicable 3

53,000,000

Total 3

100,000,000

Gillette coalfield mines, Wyoming

Antelope 1993–present Anderson, Canyon 1

34,316,314 4502,990,481

Belle Ayr 1972–present Anderson, Canyon 1

24,227,846 4695,975,751

Black Thunder 1978–present Anderson, Canyon 1

93,082,919 41,630,468,969

Buckskin 1981–present Anderson, Canyon 1

18,058,827 4431,995,844

Caballo 1978–present Anderson, Canyon 1

16,841,183 4608,700,789

Clovis Point 1979–1988 Anderson, Canyon Not applicable 4

18,508,466

Coal Creek 1982–present Anderson, Canyon 1

7,564,231 4113,262,743

Codero Rojo (Codero Mine) 1976–present Anderson, Canyon 1

39,204,736 4823,471,485

Dry Fork 1990–present Anderson, Canyon 1

6,006,787 486,872,662

Eagle Butte 1978–present Anderson, Canyon 1

22,466,733 4583,877,198

Jacobs Ranch 1983–2009 Anderson, Canyon Not applicable 4

666,047,642

North Antelope/Rochelle 1986–present Anderson, Canyon 1

107,639,188 41,486,763,140

North Rochelle 1985–2004 Anderson, Canyon Not applicable 4

302,549,491

Rawhide 1978–present Anderson, Canyon 1

14,721,376 4336,434,632

Wyodak 1974–present Anderson, Canyon 1

4,245,981 4125,189,396

Total 1

388,376,121 48,377,108,689

Glenrock coalfield, Wyoming

Dave Johnston Mine 1958–2000 Baker (Roland), Smith Not applicable 3

104,000,000

Total 3

104,000,000

Grand total 419,066,016 9,931,677,045 1

Mine Safety and Health Administration (MSHA), Mine Yearly Production Information (www.msha.gov/drs/ASP/Mine).

2

Department of Labor and Industry Safety and Health Bureau, State of Montana, P.O. Box 1728, Helena, MT, 59624.

3

Wyoming Geological Survey, written commun., 2009.

4

Keystone Coal Industry Manual, years (1969–2000) and Mine Safety and Health Administration (MSHA), Mine Yearly Production Information 

(www.msha.gov/drs/ASP/Mine Action).
192 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 2. Typical proximate analysis on an as-received basis of coal from mines in the Powder River Basin, Wyoming and Montana.

Area/location/

mine name Owner Coal bed name

Calorific value

(British thermal 

unit per pound)

Sulfur

(percent)

Ash

(percent)

Colstrip area, Montana

Absaloka Mine1 Westmoreland Coal Co. Rosebud/Knobloch 8,750 0.60 9.00

Big Sky Mine2 Peabody Energy/abandoned Rosebud/Knobloch 8,750 0.75 8.80

Rosebud Mine1 Westmoreland Coal Co. Rosebud/Knobloch 8,750 0.80 8.50

Otter Creek area (Arch lease)3 Arch Coal Inc. Rosebud/Knobloch 8,497 0.19 6.21

Decker/Spring Creek area, Montana

Decker Mine1 Kiewit Mining Group (manager) Smith, Anderson, Dietz 3 9,450 0.40 4.20

Spring Creek Mine1 Cloud Peak Energy Smith, Anderson, Dietz 3 9,350 0.38 4.10

Sheridan coalfield area, Wyoming

Big Horn Mine2 Kiewit Mining Group/abandoned Dietz 1, Dietz 2, Dietz 3 9,300 0.60 5.70

Lake DeSmet area4

 (estimated) Not applicable Lake DeSmet zone 7,559 0.7 7.7

Gillette coalfield area Wyoming

Antelope1 Cloud Peak Energy Anderson, Canyon 8,800 0.24 5.25

Belle Ayr1 Alpha Natural Resources Anderson, Canyon 8,550 0.33 4.50

Black Thunder1 Arch Coal Anderson, Canyon 8,800 0.30 5.50

Buckskin1 Kiewit Mining Group Anderson, Canyon 8,400 0.30 5.00

Cabbalo1 Peabody Energy Anderson, Canyon 8,500 0.34 5.10

Clovis Point2 Kerr-McGee/abandoned Anderson, Canyon 8,050 0.40 6.00

Coal Creek1 Arch Coal Anderson, Canyon 8,325 0.30 6.00

Codero Rojo1 Cloud Peak Energy Anderson, Canyon 8,400 0.34 5.40

Dry Fork1 Western Fuels Anderson, Canyon 8,100 0.34 4.60

Eagle Butte1 Alpha Natural Resources Anderson, Canyon 8,400 0.34 4.50

Jacobs Ranch2 Arch Coal-combined/Black Thunder Anderson, Canyon 8,800 0.45 5.40

North Antelope/Rochelle1 Peabody Energy Anderson, Canyon 8,800 0.21 4.60

North Rochelle2 Triton Coal/abandoned Anderson, Canyon 8,673 0.24 8.00

Rawhide1 Peabody Energy Anderson, Canyon 8,300 0.37 5.40

Wyodak1 Wyodak Resources Anderson, Canyon 8,050 0.40 6.00

Glenrock coalfield, Wyoming

Dave Johnston Mine2 Glenrock Coal Co./abandoned Baker (Roland), Smith 7,581 0.45 12.1 1

Guide to Coal Mines, April 21, 2010.

2

Keystone Coal Industry Manuals, 1998–2000.

3

Minerals Management Service Memorandum July 22, 1982.

4

Luppens, 2011.
Tables 193

Table 3. Typical proximate analysis on an as-received basis of coal beds reporting sodium as percent of ash, percent sulfur, percent 

ash, and calorific value, in coal beds in the Wyoming Powder River Basin compared to the Montana Powder River Basin.

[All data from Guide to Coal Mines, April 21, 2010]

Mine name

and state

Coal bed

name

Sodium,

as percent of ash

Sulfur

(percent)

Ash

(percent)

Calorific value 

(British thermal 

unit per pound)

Wyoming

Antelope Anderson, Canyon 1.64 0.24 5.25 8,800

Belle Ayr Anderson, Canyon 1.90 0.33 4.50 8,550

Black Thunder Anderson, Canyon 1.30 0.30 5.50 8,800

Buckskin Anderson, Canyon 1.80 0.30 5.00 8,400

Cabbalo Anderson, Canyon 1.40 0.34 5.10 8,500

Clovis Point Anderson, Canyon 0.94 0.40 6.00 8,050

Coal Creek Anderson, Canyon 1.00 0.30 6.00 8,325

Codero Rojo Anderson, Canyon 1.40 0.34 5.40 8,400

Dry Fork Anderson, Canyon 1.50 0.34 4.60 8,100

Eagle Butte Anderson, Canyon 1.90 0.34 4.50 8,400

North Antelope/Rochelle Anderson, Canyon 1.80 0.21 4.60 8,800

Rawhide Anderson, Canyon 1.60 0.37 5.40 8,300

Wyodak Anderson, Canyon 0.94 0.40 6.00 8,050

Montana

Absaloka Rosebud/Knobloch 2.00 0.60 9.00 8,750

Decker Smith, Anderson, Dietz 3 1.00–8.00 0.40 4.20 9,450

Rosebud Rosebud/Knobloch 0.30 0.80 8.50 8,750

Spring Creek Smith, Anderson, Dietz 3 8.50 0.38 4.10 9,350
194 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

reliability category for the Powder River Basin, Wyoming and Montana. Reliability categories are based on distance from nearest data 

point. Measured: less than 0.25 mile; Indicated: 0.25–0.75 mile; Inferred: 0.75–3 miles; Hypothetical: greater than 3 miles. Totals may not 

sum exactly because of to rounding.—Continued

Coal bed

name

Reliability

category

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Healy Measured 676 27 0 649 35 20 593

Indicated 2,212 83 0 2,129 170 73 1,885

Inferred 3,672 95 0 3,577 617 277 2,683

Hypothetical 303 0 0 303 55 81 167

Total 6,863 206 0 6,657 878 452 5,327

Healy/ Lower Ulm Measured 1,677 4 0 1,673 76 58 1,539

Indicated 4,794 8 0 4,786 370 155 4,260

Inferred 6,320 14 0 6,306 1,119 287 4,900

Hypothetical 212 0 0 212 86 86 39

Total 13,004 26 0 12,977 1,652 588 10,738

Murray Measured 471 0 0 471 3 343 125

Indicated 980 0 0 980 9 699 271

Inferred 1,144 0 0 1,144 13 948 184

Hypothetical 68 0 0 68 2 47 19

Total 2,664 0 0 2,664 27 2,036 599

Ucross Measured 590 0 0 590 23 193 375

Indicated 1,820 0 0 1,820 100 437 1,283

Inferred 4,115 0 0 4,115 679 675 2,761

Hypothetical 282 0 0 282 142 65 74

Total 6,808 0 0 6,808 944 1,371 4,492

Upper Felix Measured 1,455 0 0 1,455 4 496 955

Indicated 625 0 0 625 3 377 243

Inferred 41 0 0 41 0 35 6

Hypothetical 0 0 0 0 0 0 0

Total 2,122 0 0 2,122 7 909 1,205

Felix Measured 9,838 5 0 9,833 482 322 9,028

Indicated 6,801 3 0 6,798 213 463 6,123

Inferred 2,046 1 0 2,046 19 400 1,626

Hypothetical 73 0 0 73 6 60 7

Total 18,759 9 0 18,750 720 1,246 16,784

Lower Felix Measured 4,376 1 0 4,375 232 948 3,196

Indicated 6,350 0 0 6,350 171 1,518 4,661

Inferred 8,100 0 0 8,100 565 836 6,700

Hypothetical 559 0 0 559 126 61 372

Total 19,385 1 0 19,384 1,094 3,361 14,929

Roland Upper Rider Measured 4,257 0 0 4,257 65 1,632 2,560

Indicated 5,873 0 0 5,873 57 2,097 3,719

Inferred 3,353 0 0 3,353 59 1,286 2,008

Hypothetical 23 0 0 23 0 6 17

Total 13,506 0 0 13,506 181 5,021 8,304

Roland Lower Rider Measured 1,014 0 0 1,014 4 509 501

Indicated 1,473 0 0 1,473 0 619 854

Inferred 770 0 0 770 4 429 338

Hypothetical 0 0 0 0 0 0 0

Total 3,257 0 0 3,257 8 1,555 1,693

Roland (Baker) Measured 14,647 3 0 14,646 529 1,171 12,947

Indicated 17,532 7 0 17,525 302 1,336 15,888

Inferred 15,475 2 0 15,472 123 890 14,460

Hypothetical 117 1 0 117 1 74 42

Total 47,774 13 0 47,761 954 3,471 43,336

Roland (Taff) Measured 776 0 0 776 12 263 501

Indicated 1,017 0 0 1,017 15 620 383

Inferred 1,574 0 0 1,574 6 1,161 407

Hypothetical 37 0 0 37 0 37 0

Total 3,403 0 0 3,403 33 2,079 1,290

Upper Smith Measured 260 0 0 260 0 114 145

Indicated 517 0 0 517 0 309 208

Inferred 259 0 0 259 0 183 76

Hypothetical 0 0 0 0 0 0 0

Total 1,036 0 0 1,036 0 607 430
Tables 195

Table 4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

reliability category for the Powder River Basin, Wyoming and Montana. Reliability categories are based on distance from nearest data 

point. Measured: less than 0.25 mile; Indicated: 0.25–0.75 mile; Inferred: 0.75–3 miles; Hypothetical: greater than 3 miles. Totals may not 

sum exactly because of to rounding.—Continued

Coal bed

name

Reliability

category

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Smith Measured 45,930 6 1 45,924 139 487 45,297

Indicated 61,361 13 0 61,348 108 945 60,294

Inferred 18,821 9 2 18,810 423 1,243 17,144

Hypothetical 322 3 0 319 151 36 132

Total 126,433 30 3 126,400 820 2,712 122,868

Anderson Upper Rider Measured 146 0 0 146 1 108 36

Indicated 102 0 0 102 0 94 8

Inferred 24 0 0 24 0 24 0

Hypothetical 0 0 0 0 0 0 0

Total 272 0 0 272 1 226 44

Anderson Lower Rider Measured 540 0 51 490 100 45 344

Indicated 207 0 29 179 18 26 135

Inferred 8 0 5 3 0 2 1

Hypothetical 0 0 0 0 0 0 0

Total 755 0 83 672 118 73 480

Anderson Measured 68,140 474 2,844 64,822 9,953 388 54,481

Indicated 43,040 846 1,502 40,692 3,656 1,053 35,983

Inferred 14,172 537 138 13,497 808 1,385 11,304

Hypothetical 129 21 0 108 29 21 57

Total 125,481 1,879 4,484 119,118 14,446 2,847 101,825

Lower Anderson Measured 922 1 0 921 0 255 667

Indicated 1,693 1 0 1,692 0 550 1,141

Inferred 765 0 0 765 0 534 231

Hypothetical 1 0 0 1 0 1 0

Total 3,382 2 0 3,380 0 1,340 2,039

Dietz 1 Measured 556 1 3 553 45 182 325

Indicated 385 3 3 379 75 154 150

Inferred 197 4 0 193 47 289 20

Hypothetical 0 0 0 0 0 0 0

Total 1,138 7 6 1,125 167 462 495

Dietz 2 Measured 1,222 10 40 1,172 109 157 906

Indicated 1,160 8 0 1,152 16 385 751

Inferred 605 6 0 598 1 104 373

Hypothetical 6 0 0 6 0 4 2

Total 2,992 24 40 2,928 126 770 2,032

Dietz 3 Measured 14,388 115 96 14,177 422 458 13,296

Indicated 23,975 176 45 23,754 561 1,068 22,125

Inferred 12,125 109 3 12,013 963 1,683 9,367

Hypothetical 393 7 0 386 52 59 275

Total 50,880 407 144 50,329 1,998 3,268 45,063

Dietz 4 Measured 495 1 0 494 19 205 270

Indicated 803 3 0 800 11 372 417

Inferred 451 1 0 449 23 306 119

Hypothetical 16 0 0 16 0 16 0

Total 1,765 5 0 1,760 54 899 807

Upper Canyon/Cox Measured 988 1 0 987 6 163 817

Indicated 2,182 1 1 2,180 15 380 1,784

Inferred 2,636 1 1 2,633 61 516 2,056

Hypothetical 162 0 0 162 0 108 53

Total 5,968 3 3 5,961 83 1,168 4,711

Canyon Measured 48,817 144 571 48,102 2,079 286 45,737

Indicated 64,531 408 302 63,821 2,107 876 60,838

Inferred 32,607 225 71 32,311 2,988 1,397 27,925

Hypothetical 1,495 20 0 1,475 360 160 954

Total 147,450 797 945 145,708 7,535 2,719 135,454

Lower Canyon Measured 13,948 11 1 13,936 258 328 13,350

Indicated 27,319 39 7 27,273 815 1,305 25,153

Inferred 17,206 77 9 17,120 1,525 2,557 13,038

Hypothetical 1,056 20 0 1,036 230 291 516

Total 59,528 146 17 59,365 2,827 4,482 52,056
196 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

reliability category for the Powder River Basin, Wyoming and Montana. Reliability categories are based on distance from nearest data 

point. Measured: less than 0.25 mile; Indicated: 0.25–0.75 mile; Inferred: 0.75–3 miles; Hypothetical: greater than 3 miles. Totals may not 

sum exactly because of to rounding.—Continued

Coal bed

name

Reliability

category

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Ferry Measured 141 0 0 141 0 57 84

Indicated 381 0 0 381 0 174 207

Inferred 292 0 0 292 0 118 175

Hypothetical 0 0 0 0 0 0 0

Total 814 0 0 814 0 349 465

Ferry Measured 748 0 0 748 14 226 507

Indicated 1,866 0 0 1,866 66 1,472 1,257

Inferred 3,646 2 0 3,645 254 919 2,471

Hypothetical 135 0 0 135 8 86 42

Total 6,396 2 0 6,394 343 1,774 4,277

Werner/Cook Measured 12,701 68 0 12,633 909 489 11,235

Indicated 31,534 238 0 31,296 1,668 1,487 28,141

Inferred 28,428 386 0 28,042 3,053 1,712 23,277

Hypothetical 1,323 15 0 1,308 498 110 700

Total 73,986 707 0 73,279 6,128 3,798 63,353

Upper Otter Measured 330 0 0 330 0 75 255

Indicated 486 1 0 485 0 167 318

Inferred 96 0 0 96 0 66 31

Hypothetical 6 0 0 6 0 6 0

Total 919 1 0 918 0 314 604

Otter Measured 13,446 1 0 13,445 47 548 12,851

Indicated 33,479 7 0 33,472 206 1,666 31,601

Inferred 23,742 12 0 23,730 616 3,293 19,822

Hypothetical 353 1 0 353 41 275 37

Total 71,021 21 0 71,000 909 5,781 64,310

Gates/Wall Measured 8,330 2 0 8,328 112 438 7,776

Indicated 25,828 20 0 25,809 460 1,868 23,481

Inferred 31,072 48 0 31,024 869 4,250 25,905

Hypothetical 1,196 1 0 1,195 133 373 689

Total 66,426 70 0 66,355 1,574 6,930 57,851

Pawnee Measured 2,105 6 0 2,098 70 267 1,761

Indicated 7,566 60 0 7,506 405 1,222 5,879

Inferred 13,842 153 0 13,689 1,928 2,984 8,777

Hypothetical 986 13 0 974 201 224 548

Total 24,498 231 0 24,267 2,603 4,699 16,964

Brewster-Arnold Measured 94 0 0 94 11 49 34

Indicated 355 2 0 354 79 155 120

Inferred 901 41 0 860 257 400 202

Hypothetical 617 32 0 585 429 36 119

Total 1,968 75 0 1,892 776 641 475

Odell Measured 1,415 1 0 1,414 14 274 1,127

Indicated 3,872 2 0 3,870 93 1,237 2,540

Inferred 5,858 4 0 5,854 210 3,030 2,614

Hypothetical 531 1 0 530 6 223 300

Total 11,676 8 0 11,668 322 4,765 6,581

Cache Measured 241 2 0 239 64 99 75

Indicated 952 9 0 944 204 483 255

Inferred 2,040 6 0 2,034 194 1,374 465

Hypothetical 70 0 0 69 0 56 14

Total 3,303 18 0 3,286 463 2,013 809

A Zone Measured 17 0 0 17 0 13 4

Indicated 38 0 0 38 0 29 9

Inferred 53 0 0 53 0 51 2

Hypothetical 3 0 0 3 0 3 0

Total 111 0 0 111 0 95 15

Upper Rosebud Measured 51 0 6 45 0 31 14

Indicated 75 0 0 74 0 51 24

Inferred 81 0 0 81 0 65 16

Hypothetical 2 0 0 2 0 2 0

Total 209 0 6 203 0 148 54
Tables 197

Table 4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

reliability category for the Powder River Basin, Wyoming and Montana. Reliability categories are based on distance from nearest data 

point. Measured: less than 0.25 mile; Indicated: 0.25–0.75 mile; Inferred: 0.75–3 miles; Hypothetical: greater than 3 miles. Totals may not 

sum exactly because of to rounding.—Continued

Coal bed

name

Reliability

category

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Rosebud/Knobloch Measured 7,021 139 439 6,442 729 416 5,297

Indicated 21,482 699 65 20,718 3,249 1,682 15,788

Inferred 34,764 557 3 34,203 6,202 2,912 25,088

Hypothetical 1,136 57 0 1,079 99 63 917

Total 64,401 1,452 507 62,442 10,279 5,072 47,091

Calvert Measured 118 0 0 118 24 42 52

Indicated 396 1 0 396 86 210 100

Inferred 611 0 0 611 31 538 43

Hypothetical 34 0 0 34 0 34 0

Total 1,161 1 0 1,160 140 823 196

McKay/Nance Measured 4,738 31 68 4,640 374 626 3,640

Indicated 12,689 24 0 12,664 884 2,692 9,088

Inferred 15,413 13 0 15,400 766 5,026 9,608

Hypothetical 448 6 0 442 1 164 277

Total 33,289 74 68 33,146 2,024 8,509 22,614

Lower McKay Measured 105 1 0 104 0 103 1

Indicated 54 0 0 54 0 54 0

Inferred 29 0 0 29 0 29 0

Hypothetical 3 0 0 3 0 3 0

Total 190 1 0 189 0 188 1

Flowers-Goodale Measured 5,647 3 0 5,645 413 560 4,672

Indicated 20,971 15 0 20,956 880 2,306 17,769

Inferred 32,716 29 0 32,686 691 4,407 27,589

Hypothetical 1,209 1 0 1,209 2 174 1,033

Total 60,544 48 0 60,496 1,986 7,447 51,064

Upper Witham Measured 68 2 0 66 0 26 40

Indicated 34 0 0 34 0 16 18

Inferred 15 0 0 15 0 5 10

Hypothetical 0 0 0 0 0 0 0

Total 117 2 0 115 0 46 68

Robinson/Witham Measured 4,112 63 0 4,049 384 289 3,376

Indicated 8,259 50 0 8,209 792 1,251 6,167

Inferred 7,714 17 0 7,697 296 2,373 5,029

Hypothetical 592 0 0 592 8 149 436

Total 20,677 130 0 20,547 1,479 4,061 15,007

Roberts/Terret Measured 3,453 3 0 3,450 66 390 2,994

Indicated 15,365 17 0 15,348 192 1,696 13,459

Inferred 31,487 39 0 31,448 138 4,450 26,860

Hypothetical 1,561 11 0 1,549 2 394 1,153

Total 51,866 71 0 51,795 398 6,930 44,467

Burley Measured 77 0 0 77 0 36 41

Indicated 334 0 0 334 0 163 171

Inferred 1,044 1 0 1,043 0 613 430

Hypothetical 178 0 0 178 0 136 41

Total 1,632 1 0 1,631 0 947 684

Upper Stag Measured 94 0 0 94 0 44 51

Indicated 490 0 0 490 0 230 260

Inferred 1,239 0 0 1,239 0 760 479

Hypothetical 47 0 0 47 0 47 0

Total 1,870 0 0 1,870 0 1,080 790

Lower Stag Measured 8 0 0 8 0 3 5

Indicated 46 0 0 46 0 40 6

Inferred 93 0 0 93 0 93 0

Hypothetical 4 0 0 4 0 4 0

Total 151 0 0 151 0 139 11

Total beds Measured 301,189 1,126 4,120 295,948 17,827 14,232 263,883

Indicated 463,304 2,744 1,954 458,609 18,056 36,262 405,215

Inferred 381,662 2,389 232 379,037 25,548 56,915 296,620

Hypothetical 15,688 210 0 15,480 2,668 3,775 9,032

Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
198 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden 

depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of 

rounding.—Continued

Coal bed

name

Overburden

thickness

(feet)

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Healy 0–500 6,681 206 0 6,475 815 435 5,225

500–1,000 183 0 0 183 63 17 103

1,000–2,000 0 0 0 0 0 0 0

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 6,863 206 0 6,657 878 452 5,327

Healy/Lower Ulm 0–500 11,228 26 0 11,202 1,334 513 9,355

500–1,000 1,774 0 0 1,774 318 74 1,381

1,000–2,000 1 0 0 1 0 0 1

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 13,004 26 0 12,977 1,652 588 10,738

Murray 0–500 1,681 0 0 1,681 16 1,292 372

500–1,000 960 0 0 960 11 744 206

1,000–2,000 23 0 0 23 0 1 21

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 2,664 0 0 2,664 27 2,036 599

Ucross 0–500 1,187 0 0 1,187 49 732 405

500–1,000 5,195 0 0 5,195 809 638 3,749

1,000–2,000 425 0 0 425 85 2 338

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 6,808 0 0 6,808 944 1,371 4,492

Upper Felix 0–500 2,033 0 0 2,033 7 879 1,147

500–1,000 87 0 0 87 0 31 57

1,000–2,000 1 0 0 1 0 0 0

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 2,122 0 0 2,122 7 909 1,205

Felix 0–500 15,881 9 0 15,872 713 888 14,270

500–1,000 2,803 0 0 2,803 5 342 2,456

1,000–2,000 71 0 0 71 2 15 54

2,000–3,000 5 0 0 5 0 0 5

Greater than 3,000 0 0 0 0 0 0 0

Total 18,759 9 0 18,750 720 1,246 16,784

Lower Felix 0–500 5,777 1 0 5,776 313 2,004 3,460

500–1,000 10,393 0 0 10,393 488 1,247 8,658

1,000–2,000 3,215 0 0 3,215 294 111 2,811

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 19,385 1 0 19,384 1,094 3,361 14,929

Roland Upper Rider 0–500 4,115 0 0 4,115 152 1,462 2,502

500–1,000 6,956 0 0 6,956 8 2,357 4,591

1,000–2,000 2,434 0 0 2,434 22 1,202 1,210

2,000–3,000 1 0 0 1 0 1 0

Greater than 3,000 0 0 0 0 0 0 0

Total 13,506 0 0 13,506 181 5,021 8,304

Roland Lower Rider 0–500 365 0 0 365 8 244 113

500–1,000 1,960 0 0 1,960 0 994 966

1,000–2,000 932 0 0 932 0 318 613

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 3,257 0 0 3,257 8 1,555 1,693
Tables 199

Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden 

depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of 

rounding.—Continued

Coal bed

name

Overburden

thickness

(feet)

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Roland (Baker) 0–500 16,907 13 0 16,894 796 1,108 14,990

500–1,000 17,993 0 0 17,993 93 1,274 16,625

1,000–2,000 12,848 0 0 12,848 64 1,089 11,695

2,000–3,000 26 0 0 26 0 1 25

Greater than 3,000 0 0 0 0 0 0 0

Total 47,774 13 0 47,761 954 3,471 43,336

Roland (Taff) 0–500 1,445 0 0 1,445 33 738 674

500–1,000 939 0 0 939 0 536 403

1,000–2,000 1,018 0 0 1,018 0 805 214

2,000–3,000 1 0 0 1 0 1 0

Greater than 3,000 0 0 0 0 0 0 0

Total 3,403 0 0 3,403 33 2,079 1,290

Upper Smith 0–500 584 0 0 584 0 385 199

500–1,000 332 0 0 332 0 185 148

1,000–2,000 119 0 0 119 0 37 82

2,000–3,000 1 0 0 1 0 0 1

Greater than 3,000 0 0 0 0 0 0 0

Total 1,036 0 0 1,036 0 607 430

Smith 0–500 6,583 30 3 6,550 151 999 5,400

500–1,000 41,135 0 0 41,135 149 892 40,094

1,000–2,000 78,389 0 0 78,389 518 818 77,053

2,000–3,000 320 0 0 320 3 2 315

Greater than 3,000 6 0 0 6 0 0 6

Total 126,433 30 3 126,400 820 2,712 122,868

Anderson Upper Rider 0–500 127 0 0 127 1 99 26

500–1,000 46 0 0 46 0 33 12

1,000–2,000 99 0 0 99 0 92 6

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 272 0 0 272 1 226 44

Anderson Lower Rider 0–500 716 0 69 648 118 69 460

500–1,000 24 0 4 20 0 3 16

1,000–2,000 10 0 6 4 0 1 4

2,000–3,000 5 0 5 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 755 0 83 672 118 73 480

Anderson 0–500 58,607 1,879 4,046 52,683 10,817 820 41,046

500–1,000 47,442 0 256 47,186 3,301 819 43,066

1,000–2,000 19,152 0 141 19,011 272 543 17,531

2,000–3,000 271 0 39 233 55 258 177

Greater than 3,000 8 0 2 6 2 0 5

Total 125,481 1,879 4,484 119,118 14,446 2,847 101,825

Lower Anderson 0–500 1,147 2 0 1,145 0 292 854

500–1,000 1,640 0 0 1,640 0 598 1,041

1,000–2,000 591 0 0 591 0 449 141

2,000–3,000 3 0 0 3 0 0 3

Greater than 3,000 0 0 0 0 0 0 0

Total 3,382 2 0 3,380 0 1,340 2,039

Dietz 1 0–500 464 7 6 451 119 163 168

500–1,000 485 0 0 485 46 152 287

1,000–2,000 189 0 0 189 2 146 40

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 1,138 7 6 1,125 167 462 495
200 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden 

depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of 

rounding.—Continued

Coal bed

name

Overburden

thickness

(feet)

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Dietz 2 0–500 1,677 24 40 1,612 126 334 1,153

500–1,000 846 0 0 846 0 315 530

1,000–2,000 470 0 0 470 0 121 349

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 2,992 24 40 2,928 126 770 2,032

Dietz 3 0–500 15,437 407 144 14,887 1,636 963 12,287

500–1,000 16,330 0 0 16,329 77 720 15,532

1,000–2,000 18,558 0 0 18,558 286 1,427 16,844

2,000–3,000 556 0 0 556 0 157 399

Greater than 3,000 0 0 0 0 0 0 0

Total 50,880 407 144 50,329 1,998 3,268 45,063

Dietz 4 0–500 521 5 0 516 26 342 148

500–1,000 344 0 0 344 0 208 136

1,000–2,000 882 0 0 882 28 343 512

2,000–3,000 17 0 0 17 0 6 10

Greater than 3,000 0 0 0 0 0 0 0

Total 1,765 5 0 1,760 54 899 807

Upper Canyon/Cox 0–500 555 3 3 549 7 432 110

500–1,000 132 0 0 132 0 118 14

1,000–2,000 4,226 0 0 4,226 40 420 3,766

2,000–3,000 1,055 0 0 1,055 37 197 821

Greater than 3,000 0 0 0 0 0 0 0

Total 5,968 3 3 5,961 83 1,168 4,711

Canyon 0–500 34,020 797 915 32,307 5,710 650 25,947

500–1,000 24,725 0 23 24,701 981 268 23,452

1,000–2,000 76,241 0 6 76,235 425 1,088 74,722

2,000–3,000 12,459 0 0 12,458 419 712 11,328

Greater than 3,000 6 0 0 6 0 0 6

Total 147,450 797 945 145,7 7,535 2,719 135,454

Lower Canyon 0–500 10,111 146 14 9,951 2,434 1,133 6,384

500–1,000 8,709 0 3 8,706 39 920 7,747

1,000–2,000 35,317 0 0 35,317 264 1,072 33,981

2,000–3,000 5,371 0 0 5,371 90 1,340 3,941

Greater than 3,000 20 0 0 20 0 17 23

Total 59,528 146 17 59,365 2,827 4,482 52,056

Upper Ferry 0–500 124 0 0 124 0 99 26

500–1,000 574 0 0 574 0 212 362

1,000–2,000 115 0 0 115 0 39 77

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 814 0 0 814 0 349 464

Ferry 0–500 1,449 2 0 1,446 327 403 717

500–1,000 1,568 0 0 1,568 3 363 1,202

1,000–2,000 1,197 0 0 1,197 11 593 594

2,000–3,000 2,182 0 0 2,182 2 416 1,764

Greater than 3,000 0 0 0 0 0 0 0

Total 6,396 2 0 6,394 343 1,774 4,277

Werner/Cook 0–500 22,968 707 0 22,261 4,888 824 16,549

500–1,000 23,553 0 0 23,553 666 482 22,406

1,000–2,000 18,304 0 0 18,304 193 1,929 16,181

2,000–3,000 8,710 0 0 8,710 354 539 7,818

Greater than 3,000 450 0 0 450 27 24 399

Total 73,986 707 0 73,279 6,128 3,798 63,353
Tables 201

Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden 

depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of 

rounding.—Continued

Coal bed

name

Overburden

thickness

(feet)

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Otter 0–500 530 0 0 529 0 176 353

500–1,000 101 0 0 101 0 55 46

1,000–2,000 201 0 0 201 0 41 159

2,000–3,000 83 0 0 83 0 37 45

Greater than 3,000 4 0 0 4 0 4 0

Total 919 0 0 918 0 314 604

Otter 0–500 5,503 21 0 5,482 864 1,100 3,518

500–1,000 10,143 0 0 10,143 29 1,649 8,465

1,000–2,000 38,786 0 0 38,786 6 1,600 37,182

2,000–3,000 16,297 0 0 16,297 10 1,212 15,075

Greater than 3,000 292 0 0 292 0 222 70

Total 71,021 21 0 71,000 909 5,781 64,310

Gates/Wall 0–500 6,441 70 0 6,371 859 1,039 4,473

500–1,000 10,771 0 0 10,771 32 1,552 9,187

1,000–2,000 26,324 0 0 26,324 428 2,248 23,647

2,000–3,000 192 0 0 192 129 2,008 18,512

Greater than 3,000 2,240 0 0 2,240 126 82 2,032

Total 66,426 70 0 66,355 1,574 6,930 57,851

Pawnee 0–500 9,110 231 0 8,878 2,562 573 5,743

500–1,000 5,215 0 0 5,215 8 1,139 4,068

1,000–2,000 5,704 0 0 5,704 23 1,512 4,170

2,000–3,000 2,920 0 0 2,920 6 1,262 1,652

Greater than 3,000 1,549 0 0 1,549 5 213 1,331

Total 24,498 231 0 24,267 2,603 4,699 16,964

Brewster-Arnold 0–500 1,490 75 0 1,415 776 416 223

500–1,000 417 0 0 417 0 168 250

1,000–2,000 61 0 0 61 0 59 2

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 1,968 75 0 1,892 776 641 475

Odell 0–500 2,870 8 0 2,862 318 1,181 1,363

500–1,000 2,352 0 0 2,352 0 552 1,801

1,000–2,000 1,684 0 0 1,684 0 1,129 555

2,000–3,000 3,646 0 0 3,646 4 1,193 2,449

Greater than 3,000 1,124 0 0 1,124 0 711 413

Total 11,676 8 0 11,668 322 4,765 6,581

Cache 0–500 1,927 18 0 1,910 463 959 488

500–1,000 1,198 0 0 1,198 0 903 295

1,000–2,000 178 0 0 178 0 152 26

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 3,303 18 0 3,286 463 2,013 809

A Zone 0–500 90 0 0 90 0 77 13

500–1,000 12 0 0 12 0 12 0

1,000–2,000 9 0 0 9 0 7 2

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 111 0 0 111 0 95 15

Upper Rosebud 0–500 159 0 4 155 0 118 37

500–1,000 28 0 1 27 0 16 12

1,000–2,000 18 0 1 17 0 12 5

2,000–3,000 3 0 0 3 0 3 0

Greater than 3,000 0 0 0 0 0 0 0

Total 209 0 6 203 0 148 54
202 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden 

depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of 

rounding.—Continued

Coal bed

name

Overburden

thickness

(feet)

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Rosebud/Knobloch 0–500 25,243 1,452 415 23,376 10,264 949 12,163

500–1,000 13,694 0 39 13,656 4 836 12,816

1,000–2,000 12,862 0 39 12,822 9 1,717 11,095

2,000–3,000 12,450 0 14 12,436 2 1,543 10,891

Greater than 3,000 153 0 1 153 0 27 125

Total 64,401 1,452 507 62,442 10,279 5,072 47,091

Calvert 0–500 596 1 0 595 140 355 100

500–1,000 499 0 0 499 0 416 84

1,000–2,000 65 0 0 65 0 53 12

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 1,161 1 0 1,160 140 823 196

McKay/Nance 0–500 7,669 74 53 7,541 1,130 1,506 4,904

500–1,000 6,175 0 8 6,167 204 1,686 4,277

1,000–2,000 10,476 0 5 10,471 678 2,706 7,087

2,000–3,000 8,449 0 1 8,447 12 2,366 6,069

Greater than 3,000 520 0 0 520 0 244 276

Total 33,289 74 68 33,146 2,024 8,509 22,614

Lower McKay 0–500 149 1 0 147 0 146 1

500–1,000 28 0 0 28 0 28 0

1,000–2,000 11 0 0 11 0 11 0

2,000–3,000 3 0 0 3 0 3 0

Greater than 3,000 0 0 0 0 0 0 0

Total 190 1 0 189 0 188 1

Flowers-Goodale 0–500 8,937 48 0 8,889 849 1,298 6,742

500–1,000 10,832 0 0 10,832 100 1,374 9,358

1,000–2,000 27,593 0 0 27,593 994 2,747 23,851

2,000–3,000 12,303 0 0 12,303 43 1,788 10,472

Greater than 3,000 879 0 0 879 0 239 640

Total 60,544 48 0 60,496 1,986 7,447 51,064

Upper Witham 0–500 116 2 0 114 0 46 68

500–1,000 1 0 0 1 0 0 0

1,000–2,000 0 0 0 0 0 0 0

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 117 2 0 115 0 46 68

Robinson/Witham 0–500 5,900 130 0 5,771 45 783 4,944

500–1,000 4,029 0 0 4,029 10 1,218 2,801

1,000–2,000 9,185 0 0 9,185 1,273 1,750 6,162

2,000–3,000 1,558 0 0 1,558 151 311 1,095

Greater than 3,000 5 0 0 5 0 0 5

Total 20,677 130 0 20,547 1,479 4,061 15,007

Roberts/Terret 0–500 4,733 71 0 4,662 134 1,307 3,222

500–1,000 3,436 0 0 3,436 0 1,279 2,157

1,000–2,000 18,718 0 0 18,718 95 2,084 16,537

2,000–3,000 17,459 0 0 17,459 164 1,815 15,479

Greater than 3,000 7,520 0 0 7,520 4 445 7,071

Total 51,866 71 0 51,795 398 6,930 44,467

Burley 0–500 390 1 0 389 0 298 90

500–1,000 436 0 0 436 0 257 179

1,000–2,000 780 0 0 780 0 365 415

2,000–3,000 14 0 0 14 0 14 0

Greater than 3,000 12 0 0 12 0 12 0

Total 1,632 1 0 1,631 0 947 684
Tables 203

Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden 

depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of 

rounding.—Continued

Coal bed

name

Overburden

thickness

(feet)

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Stag 0–500 11 0 0 11 0 4 7

500–1,000 32 0 0 32 0 28 4

1,000–2,000 717 0 0 717 0 611 107

2,000–3,000 1,027 0 0 1,027 0 358 669

Greater than 3,000 83 0 0 83 0 79 3

Total 1,870 0 0 1,870 0 1,080 790

Lower Stag 0–500 0 0 0 0 0 0 0

500–1,000 9 0 0 9 0 8 2

1,000–2,000 141 0 0 141 0 132 9

2,000–3,000 0 0 0 0 0 0 0

Greater than 3,000 0 0 0 0 0 0 0

Total 151 0 0 151 0 139 11

Total beds 0–500 304,254 6,467 5,712 292,073 49,000 30,633 212,439

500–1,000 286,536 0 334 286,201 7,444 27,718 251,042

1,000–2,000 428,340 1 198 428,141 6,012 31,597 389,863

2,000–3,000 107,387 0 59 107,327 1,481 17,543 109,015

Greater than 3,000 14,871 0 3 14,869 164 2,319 12,405

Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
204 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal 

ownership categories for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum 

exactly because of rounding.—Continued

Coal bed

name

Coal

ownership

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Healy Federal 4,277 146 0 4,131 170 299 3,661

State 1,105 47 0 1,058 156 46 855

Private 1,482 13 0 1,469 552 106 811

Total 6,863 206 0 6,657 878 452 5,327

Healy/Lower Ulm Federal 7,863 19 0 7,845 396 424 7,025

State 1,777 3 0 1,774 267 92 1,415

Private 3,363 4 0 3,358 989 72 2,298

Total 13,004 26 0 12,977 1,652 588 10,738

Murray Federal 1,777 0 0 1,777 0 1,385 380

State 408 0 0 408 27 271 132

Private 479 0 0 479 0 380 87

Total 2,664 0 0 2,664 27 2,036 599

Ucross Federal 3,457 0 0 3,457 119 968 2,369

State 949 0 0 949 173 226 550

Private 2,402 0 0 2,402 652 177 1,573

Total 6,808 0 0 6,808 944 1,371 4,492

Upper Felix Federal 1,975 0 0 1,975 6 834 1,135

State 88 0 0 88 0 41 47

Private 59 0 0 59 1 34 23

Total 2,122 0 0 2,122 7 909 1,205

Felix Federal 17,357 9 0 17,349 672 1,118 15,559

State 947 0 0 947 28 66 853

Private 455 0 0 455 21 61 372

Total 18,759 9 0 18,750 720 1,246 16,784

Lower Felix Federal 13,690 1 0 13,689 377 2,945 10,366

State 2,362 0 0 2,362 135 170 2,033

Private 3,334 0 0 3,334 582 221 2,530

Total 19,385 1 0 19,384 1,094 3,361 14,929

Roland Upper Rider Federal 11,835 0 0 11,835 115 4,272 7,448

State 739 0 0 739 27 333 379

Private 932 0 0 932 40 415 477

Total 13,506 0 0 13,506 181 5,021 8,304

Roland Lower Rider Federal 2,871 0 0 2,871 8 1,398 1,465

State 220 0 0 220 0 64 155

Private 166 0 0 166 0 94 72

Total 3,257 0 0 3,257 8 1,555 1,693

Roland (Baker) Federal 39,324 13 0 39,311 722 2,827 35,764

State 4,049 0 0 4,049 56 197 3,796

Private 4,401 0 0 4,401 176 448 3,777

Total 47,774 13 0 47,761 954 3,471 43,336

Roland (Taff) Federal 2,623 0 0 2,623 3 1,610 1,009

State 264 0 0 264 6 157 101

Private 516 0 0 516 23 313 180

Total 3,403 0 0 3,403 33 2,079 1,290

Upper Smith Federal 858 0 0 858 0 510 349

State 64 0 0 64 0 37 28

Private 114 0 0 114 0 60 53

Total 1,036 0 0 1,036 0 607 430

Smith Federal 110,339 30 3 110,307 270 2,090 107,947

State 7,242 0 0 7,242 95 168 6,978

Private 8,852 0 0 8,852 455 453 7,943

Total 126,433 30 3 126,400 820 2,712 122,868

Anderson Upper Rider Federal 166 0 0 166 1 133 31

State 25 0 0 25 0 21 4

Private 81 0 0 81 0 72 9

Total 272 0 0 272 1 226 44
Tables 205

Table 6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal 

ownership categories for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum 

exactly because of rounding.—Continued

Coal bed

name

Coal

ownership

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Anderson Lower Rider Federal 704 0 71 632 113 69 451

State 36 0 2 34 4 4 26

Private 14 0 9 5 1 0 3

Total 755 0 83 672 118 73 480

Anderson Federal 111,597 1,691 4,112 105,793 12,706 2,244 90,844

State 7,624 63 188 7,373 743 173 6,457

Private 6,259 124 183 5,952 997 430 4,524

Total 125,481 1,879 4,484 119,118 14,446 2,847 101,825

Lower Anderson Federal 3,021 1 0 3,020 0 1,189 1,831

State 215 1 0 214 0 58 156

Private 145 0 0 145 0 92 53

Total 3,382 2 0 3,380 0 1,340 2,039

Dietz 1 Federal 541 7 0 534 29 268 236

State 93 0 0 93 5 32 56

Private 505 0 6 498 132 163 203

Total 1,138 7 6 1,125 167 462 495

Dietz 2 Federal 2,561 23 29 2,510 30 704 1,776

State 173 2 10 161 7 47 107

Private 258 0 1 257 89 19 149

Total 2,992 24 40 2,928 126 770 2,032

Dietz 3 Federal 42,885 372 99 42,413 1,307 2,712 38,394

State 3,503 9 28 3,466 54 242 3,169

Private 4,493 26 17 4,450 637 314 3,500

Total 50,880 407 144 50,329 1,998 3,268 45,063

Dietz 4 Federal 1,228 4 0 1,224 15 652 558

State 175 1 0 174 0 82 92

Private 361 0 0 361 38 166 157

Total 1,765 5 0 1,760 54 899 807

Upper Canyon/Cox Federal 4,976 3 3 4,970 18 926 4,026

State 376 0 0 376 18 84 273

Private 616 0 0 616 47 157 412

Total 5,968 3 3 5,961 83 1,168 4,711

Canyon Federal 129,764 701 752 128,310 5,865 2,125 120,321

State 8,733 56 91 8,586 333 220 8,033

Private 8,954 40 101 8,811 1,336 375 7,100

Total 147,450 797 945 145,708 7,535 2,719 135,454

Lower Canyon Federal 50,659 130 2 50,528 2,211 3,515 44,801

State 4,027 13 2 4,012 105 346 3,561

Private 4,842 4 13 4,826 511 620 3,694

Total 59,528 146 17 59,365 2,827 4,482 52,056

Upper Ferry Federal 689 0 0 689 0 291 398

State 34 0 0 34 0 18 15

Private 91 0 0 91 0 39 52

Total 814 0 0 814 0 349 465

Ferry Federal 5,157 2 0 5,155 329 1,412 3,413

State 602 0 0 602 4 140 458

Private 637 0 0 637 10 221 406

Total 6,396 2 0 6,394 343 1,774 4,277

Werner/Cook Federal 64,995 653 0 64,342 5,435 3,253 55,653

State 4,487 21 0 4,466 240 205 4,021

Private 4,503 33 0 4,471 453 339 3,678

Total 73,986 707 0 73,279 6,128 3,798 63,353

Upper Otter Federal 838 1 0 837 0 278 559

State 66 0 0 66 0 24 41

Private 16 0 0 16 0 11 5

Total 919 1 0 918 0 314 604
206 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal 

ownership categories for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum 

exactly because of rounding.—Continued

Coal bed

name

Coal

ownership

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Otter Federal 63,828 20 0 63,808 860 4,849 58,097

State 4,167 0 0 4,167 26 414 3,728

Private 3,026 0 0 3,025 22 518 2,485

Total 71,021 21 0 71,000 909 5,781 64,310

Gates/Wall Federal 56,968 68 0 56,900 1,195 5,861 49,844

State 4,421 0 0 4,421 71 420 3,929

Private 5,037 2 0 5,037 308 649 4,078

Total 66,426 70 0 66,355 1,574 6,930 57,851

Pawnee Federal 21,156 231 0 20,948 2,504 3,939 14,505

State 1,564 0 0 1,560 27 342 1,191

Private 1,778 0 0 1,760 72 419 1,269

Total 24,498 231 0 24,267 2,603 4,699 16,964

Brewster-Arnold Federal 1,537 40 0 1,497 603 547 347

State 60 2 0 58 3 26 29

Private 371 33 0 338 170 69 99

Total 1,968 75 0 1,892 776 641 475

Odell Federal 10,013 6 0 10,007 312 3,983 5,712

State 812 0 0 812 2 358 452

Private 851 2 0 851 8 423 418

Total 11,676 8 0 11,668 322 4,765 6,581

Cache Federal 2,935 8 0 2,927 439 1,813 675

State 122 2 0 119 3 64 53

Private 246 7 0 239 21 137 81

Total 3,303 18 0 3,286 463 2,013 809

A Zone Federal 59 0 0 59 0 56 3

State 9 0 0 9 0 3 6

Private 43 0 0 43 0 36 6

Total 111 0 0 111 0 95 15

Upper Rosebud Federal 90 0 0 90 0 62 27

State 3 0 0 3 0 2 1

Private 115 0 5 110 0 84 26

Total 209 0 6 203 0 148 54

Rosebud/Knobloch Federal 51,662 654 222 50,786 8,947 4,395 37,444

State 2,435 91 9 2,335 119 250 1,966

Private 10,305 707 276 9,321 1,214 426 7,680

Total 64,401 1,452 507 62,442 10,279 5,072 47,091

Calvert Federal 1,021 0 0 1,020 124 762 135

State 39 0 0 39 1 31 7

Private 101 1 0 100 15 32 54

Total 1,161 1 0 1,160 140 823 196

McKay/Nance Federal 26,486 32 0 26,454 1,628 7,151 17,675

State 1,736 3 6 1,727 126 489 1,112

Private 5,066 39 62 4,965 270 860 3,827

Total 33,289 74 68 33,146 2,024 8,509 22,614

Lower McKay Federal 47 0 0 47 0 47 0

State 8 0 0 8 0 8 0

Private 135 1 0 134 0 133 1

Total 190 1 0 189 0 188 1

Flowers-Goodale Federal 51,020 25 0 50,995 1,453 6,187 43,356

State 2,984 4 0 2,980 138 432 2,410

Private 6,540 20 0 6,521 395 828 5,297

Total 60,544 48 0 60,496 1,986 7,447 51,064

Upper Witham Federal 54 1 0 52 0 17 35

State 5 0 0 5 0 5 1

Private 58 1 0 56 0 24 32

Total 117 2 0 115 0 46 68
Tables 207

Table 6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal 

ownership categories for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum 

exactly because of rounding.—Continued

Coal bed

name

Coal

ownership

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Robinson/Witham Federal 14,606 16 0 14,590 1,332 3,366 9,892

State 1,008 5 0 1,002 97 192 713

Private 5,063 109 0 4,955 51 502 4,402

Total 20,677 130 0 20,547 1,479 4,061 15,007

Roberts/Terret Federal 43,088 34 0 43,055 293 5,616 37,146

State 2,876 1 0 2,875 21 352 2,501

Private 5,902 36 0 5,866 84 963 4,820

Total 51,866 71 0 51,795 398 6,930 44,467

Burley Federal 1,314 0 0 1,313 0 723 590

State 31 0 0 31 0 25 5

Private 287 1 0 287 0 198 88

Total 1,632 1 0 1,631 0 947 684

Upper Stag Federal 1,634 0 0 1,634 0 998 637

State 77 0 0 77 0 42 35

Private 159 0 0 159 0 40 118

Total 1,870 0 0 1,870 0 1,080 790

Lower Stag Federal 147 0 0 147 0 136 11

State 2 0 0 2 0 2 0

Private 2 0 0 2 0 2 0

Total 151 0 0 151 0 139 11

Total beds Federal 985,692 4,941 5,293 975,480 50,607 90,959 833,900

State 72,742 324 336 72,076 3,117 7,021 61,930

Private 103,415 1,203 673 101,523 10,372 12,195 78,922

Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
208 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

assessment area.—Continued

[MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette 

coal field; East Gillette (area east of the Gillette coal field)]

Coal bed

name

Assessment

area name

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Healy MTPRB 0 0 0 0 0 0 0

NWPRB 1,889 45 0 1,845 34 55 1,755

SWPRB 4,974 161 0 4,813 843 398 3,572

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 6,863 206 0 6,657 878 452 5,327

Healy/Lower Ulm MTPRB 0 0 0 0 0 0 0

NWPRB 3,669 17 0 3,652 45 258 3,349

SWPRB 9,026 6 0 9,020 1,592 1,672 7,118

GILLETTE 308 3 0 305 15 20 270

EAST GILLETTE 0 0 0 0 0 0 0

Total 13,004 26 0 12,977 1,652 588 10,738

Murray MTPRB 0 0 0 0 0 0 0

NWPRB 926 0 0 926 0 673 252

SWPRB 1,718 0 0 1,718 27 1,356 335

GILLETTE 20 0 0 20 0 9 12

EAST GILLETTE 0 0 0 0 0 0 0

Total 2,664 0 0 2,664 27 2,036 599

Ucross MTPRB 0 0 0 0 0 0 0

NWPRB 2,205 0 0 2,205 11 933 1,261

SWPRB 4,602 0 0 4,602 933 438 3,231

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 6,808 0 0 6,808 944 1,371 4,492

Upper Felix MTPRB 0 0 0 0 0 0 0

NWPRB 0 0 0 0 0 0 0

SWPRB 626 0 0 626 6 367 253

GILLETTE 1,496 0 0 1,496 1 542 952

EAST GILLETTE 0 0 0 0 0 0 0

Total 2,122 0 0 2,122 7 909 1,205

Felix MTPRB 0 0 0 0 0 0 0

NWPRB 1,508 1 0 1,507 1 220 1,287

SWPRB 4,466 0 0 4,465 36 626 3,803

GILLETTE 12,786 8 0 12,777 683 400 11,695

EAST GILLETTE 0 0 0 0 0 0 0

Total 18,759 9 0 18,750 720 1,246 16,784

Lower Felix MTPRB 3 0 0 3 0 2 1

NWPRB 5,951 0 0 5,951 28 782 5,141

SWPRB 10,242 0 0 10,242 780 2,023 7,439

GILLETTE 3,189 1 0 3,188 286 555 2,347

EAST GILLETTE 0 0 0 0 0 0 0

Total 19,385 1 0 19,384 1,094 3,361 14,929

Roland Upper Rider MTPRB 1 0 0 1 0 1 0

NWPRB 4,799 0 0 4,799 94 1,480 3,225

SWPRB 6,681 0 0 6,681 56 2,609 4,016

GILLETTE 2,025 0 0 2,025 31 930 1,063

EAST GILLETTE 0 0 0 0 0 0 0

Total 13,506 0 0 13,506 181 5,021 8,304

Roland Lower Rider MTPRB 4 0 0 4 0 3 1

NWPRB 580 0 0 580 4 370 206

SWPRB 2,284 0 0 2,284 0 820 1,464

GILLETTE 389 0 0 389 4 362 23

EAST GILLETTE 0 0 0 0 0 0 0

Total 3,257 0 0 3,257 8 1,555 1,693
Tables 209

Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

assessment area.—Continued

[MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette 

coal field; East Gillette (area east of the Gillette coal field)]

Coal bed

name

Assessment

area name

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Roland (Baker) MTPRB 728 12 0 716 0 78 637

NWPRB 24,019 1 0 24,019 305 410 23,303

SWPRB 9,897 0 0 9,897 173 1,884 7,840

GILLETTE 13,130 0 0 13,130 476 1,099 11,555

EAST GILLETTE 0 0 0 0 0 0 0

Total 47,774 13 0 47,761 954 3,471 43,336

Roland (Taff) MTPRB 213 0 0 213 0 180 32

NWPRB 2,994 0 0 2,994 33 1,734 1,227

SWPRB 196 0 0 196 0 165 31

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 3,403 0 0 3,403 33 2,079 1,290

Upper Smith MTPRB 14 0 0 14 0 14 0

NWPRB 11 0 0 11 0 11 0

SWPRB 915 0 0 915 0 519 396

GILLETTE 95 0 0 95 0 61 34

EAST GILLETTE 0 0 0 0 0 0 0

Total 1,036 0 0 1,036 0 607 430

Smith MTPRB 1,869 30 0 1,840 48 165 1,627

NWPRB 10,273 0 0 10,273 125 1,229 8,919

SWPRB 87,868 0 2 87,866 513 852 86,501

GILLETTE 26,423 0 1 26,422 134 466 25,822

EAST GILLETTE 0 0 0 0 0 0 0

Total 126,433 30 3 126,400 820 2,712 122,868

Anderson Upper Rider MTPRB 0 0 0 0 0 0 0

NWPRB 181 0 0 181 1 154 26

SWPRB 32 0 0 32 0 25 6

GILLETTE 59 0 0 59 0 47 12

EAST GILLETTE 0 0 0 0 0 0 0

Total 272 0 0 272 1 226 44

Anderson Lower Rider MTPRB 0 0 0 0 0 0 0

NWPRB 0 0 0 0 0 0 0

SWPRB 0 0 0 0 0 0 0

GILLETTE 753 0 83 670 118 72 479

EAST GILLETTE 2 0 0 2 0 1 1

Total 755 0 83 672 118 73 480

Anderson MTPRB 15,437 1,226 467 13,744 954 106 12,684

NWPRB 19,613 10 0 19,603 628 1,404 17,571

SWPRB 9,442 0 0 9,442 35 1,085 8,322

GILLETTE 79,909 287 3,986 75,636 12,654 249 62,733

EAST GILLETTE 1,080 356 31 693 176 3 515

Total 125,481 1,879 4,484 119,118 14,446 2,847 101,825

Lower Anderson MTPRB 20 0 0 20 0 17 3

NWPRB 2,739 2 0 2,737 0 1,087 1,650

SWPRB 288 0 0 288 0 199 89

GILLETTE 335 0 0 335 0 38 297

EAST GILLETTE 0 0 0 0 0 0 0

Total 3,382 2 0 3,380 0 1,340 2,039

Dietz 1 MTPRB 121 7 0 114 0 73 40

NWPRB 1,017 0 6 1,011 167 388 455

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 1,138 7 6 1,125 167 462 495
210 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

assessment area.—Continued

[MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette 

coal field; East Gillette (area east of the Gillette coal field)]

Coal bed

name

Assessment

area name

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Dietz 2 MTPRB 1,669 24 40 1,605 44 401 1,160

NWPRB 1,216 0 0 1,216 81 292 843

SWPRB 105 0 0 105 0 76 29

GILLETTE 2 0 0 2 0 1 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 2,992 24 40 2,928 126 770 2,032

Dietz 3 MTPRB 9,682 343 131 9,207 1,225 644 7,338

NWPRB 27,797 63 13 27,721 768 1,502 25,451

SWPRB 12,121 0 0 12,121 0 794 11,328

GILLETTE 1,279 0 1 1,278 5 328 945

EAST GILLETTE 2 0 0 2 0 1 1

Total 50,880 407 144 50,329 1,998 3,268 45,063

Dietz 4 MTPRB 475 3 0 471 7 319 146

NWPRB 1,042 2 0 1,040 47 484 509

SWPRB 237 0 0 237 0 85 152

GILLETTE 12 0 0 12 0 12 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 1,765 5 0 1,760 54 899 807

Upper Canyon/Cox MTPRB 357 2 0 355 0 274 80

NWPRB 209 0 0 208 0 193 15

SWPRB 5,269 0 0 5,269 76 602 4,590

GILLETTE 109 0 3 106 7 81 19

EAST GILLETTE 25 1 0 24 0 17 7

Total 5,968 3 3 5,961 83 1,168 4,711

Canyon MTPRB 18,999 308 0 18,691 3,388 307 14,996

NWPRB 26,874 108 110 26,656 977 1,346 24,332

SWPRB 65,913 0 0 65,913 411 679 64,823

GILLETTE 34,938 155 797 33,986 2,660 322 31,004

EAST GILLETTE 726 226 38 462 98 65 299

Total 147,450 797 945 145,708 7,535 2,719 135,454

Lower Canyon MTPRB 10,200 104 0 10,096 2,165 1,183 6,748

NWPRB 19,080 43 17 19,020 572 2,078 16,370

SWPRB 29,410 0 0 29,410 89 1,166 28,155

GILLETTE 838 0 0 838 0 55 783

EAST GILLETTE 1 0 0 1 0 0 0

Total 59,528 146 17 59,365 2,827 4,482 52,056

Upper Ferry MTPRB 0 0 0 0 0 0 0

NWPRB 814 0 0 814 0 349 465

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 814 0 0 814 0 349 465

Ferry MTPRB 2,582 2 0 2,579 326 619 1,635

NWPRB 3,383 0 0 3,383 13 874 2,497

SWPRB 298 0 0 298 0 219 79

GILLETTE 108 0 0 108 4 58 45

EAST GILLETTE 26 0 0 26 0 3 22

Total 6,396 2 0 6,394 343 1,774 4,277

Werner/Cook MTPRB 25,428 626 0 24,802 4,061 709 20,033

NWPRB 30,342 29 0 30,313 127 851 29,334

SWPRB 11,277 0 0 11,277 377 1,501 9,399

GILLETTE 6,627 12 0 6,615 1,544 648 4,423

EAST GILLETTE 310 39 0 271 19 88 163

Total 73,986 707 0 73,279 6,128 3,798 63,353
Tables 211

Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

assessment area.—Continued

[MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette 

coal field; East Gillette (area east of the Gillette coal field)]

Coal bed

name

Assessment

area name

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Otter MTPRB 10 0 0 10 0 10 0

NWPRB 770 1 0 769 0 249 520

SWPRB 139 0 0 139 0 55 84

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 919 1 0 918 0 314 604

Otter MTPRB 4,990 20 0 4,970 888 2,150 1,933

NWPRB 30,459 1 0 30,458 4 1,633 28,822

SWPRB 28,726 0 0 28,726 7 1,071 27,648

GILLETTE 6,759 0 0 6,759 11 854 5,894

EAST GILLETTE 87 0 0 87 0 74 13

Total 71,021 21 0 71,000 909 5,781 64,310

Gates/Wall MTPRB 8,676 61 0 8,615 865 2,140 5,609

NWPRB 25,265 9 0 25,255 168 2,212 22,875

SWPRB 21,438 0 0 21,438 236 1,283 19,919

GILLETTE 10,975 0 0 10,975 306 1,226 9,444

EAST GILLETTE 73 0 0 73 0 68 4

Total 66,426 70 0 66,355 1,574 6,930 57,851

Pawnee MTPRB 13,923 231 0 13,691 2,537 1,927 9,227

NWPRB 6,868 0 0 6,868 36 1,611 5,220

SWPRB 3,303 0 0 3,303 6 1,032 2,265

GILLETTE 230 0 0 230 0 98 131

EAST GILLETTE 174 0 0 174 23 29 121

Total 24,498 231 0 24,267 2,603 4,699 16,964

Brewster-Arnold MTPRB 1,852 75 0 1,777 776 529 471

NWPRB 116 0 0 116 0 112 4

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 1,968 75 0 1,892 776 641 475

Odell MTPRB 2,164 8 0 2,157 318 1,401 438

NWPRB 7,930 0 0 7,930 4 2,355 5,570

SWPRB 1,537 0 0 1,537 0 972 566

GILLETTE 44 0 0 44 0 38 7

EAST GILLETTE 0 0 0 0 0 0 0

Total 11,676 8 0 11,668 322 4,765 6,581

Cache MTPRB 3,217 18 0 3,200 463 1,939 797

NWPRB 86 0 0 86 0 73 12

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 3,303 18 0 3,286 463 2,013 809

A Zone MTPRB 111 0 0 111 0 95 15

NWPRB 0 0 0 0 0 0 0

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 111 0 0 111 0 95 15

Upper Rosebud MTPRB 209 0 6 203 0 148 54

NWPRB 0 0 0 0 0 0 0

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 209 0 6 203 0 148 54
212 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

assessment area.—Continued

[MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette 

coal field; East Gillette (area east of the Gillette coal field)]

Coal bed

name

Assessment

area name

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Rosebud/Knobloch MTPRB 42,141 1,452 507 40,182 10,277 1,827 28,078

NWPRB 1,149 0 0 1,149 0 776 372

SWPRB 9,735 0 0 9,735 0 1,149 8,586

GILLETTE 10,847 0 0 10,847 1 1,019 9,827

EAST GILLETTE 529 0 0 529 1 300 228

Total 64,401 1,452 507 62,442 10,279 5,072 47,091

Calvert MTPRB 1,161 1 0 1,160 140 823 196

NWPRB 0 0 0 0 0 0 0

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 1,161 1 0 1,160 140 823 196

McKay/Nance MTPRB 11,139 74 68 10,997 1,070 2,622 7,304

NWPRB 5,926 0 0 5,926 0 2,178 3,748

SWPRB 7,484 0 0 7,484 24 2,010 5,451

GILLETTE 7,642 0 0 7,642 857 1,223 5,562

EAST GILLETTE 1,097 0 0 1,097 72 477 548

Total 33,289 74 68 33,146 2,024 8,509 22,614

Lower McKay MTPRB 190 1 0 189 0 188 1

NWPRB 0 0 0 0 0 0 0

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 190 1 0 189 0 188 1

Flowers-Goodale MTPRB 26,066 48 0 26,018 927 2,465 22,626

NWPRB 2,347 0 0 2,347 0 1,045 1,302

SWPRB 14,259 0 0 14,259 0 1,958 12,301

GILLETTE 16,595 0 0 16,595 1,053 1,441 14,101

EAST GILLETTE 1,276 0 0 1,276 6 537 733

Total 60,544 48 0 60,496 1,986 7,447 51,064

Upper Witham MTPRB 117 2 0 115 0 46 68

NWPRB 0 0 0 0 0 0 0

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 117 2 0 115 0 46 68

Robinson/Witham MTPRB 10,864 130 0 10,735 45 2,696 7,994

NWPRB 2,110 0 0 2,110 0 656 1,454

SWPRB 0 0 0 0 0 0 0

GILLETTE 6,780 0 0 6,780 1,391 496 4,892

EAST GILLETTE 922 0 0 922 43 211 668

Total 20,677 130 0 20,547 1,479 4,061 15,007

Roberts/Terret MTPRB 11,467 71 0 11,396 129 3,199 8,067

NWPRB 16,274 0 0 16,274 4 1,050 15,220

SWPRB 11,373 0 0 11,373 4 1,351 10,018

GILLETTE 11,930 0 0 11,930 259 1,142 10,528

EAST GILLETTE 823 0 0 823 0 189 633

Total 51,866 71 0 51,795 398 6,930 44,467

Burley MTPRB 1,606 1 0 1,605 0 921 684

NWPRB 26 0 0 26 0 26 0

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 1,632 1 0 1,631 0 947 684
Tables 213

Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by 

assessment area.—Continued

[MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette 

coal field; East Gillette (area east of the Gillette coal field)]

Coal bed

name

Assessment

area name

Original

resources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Upper Stag MTPRB 786 0 0 786 0 671 114

NWPRB 1,084 0 0 1,084 0 408 676

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 1,870 0 0 1,870 0 1,080 790

Lower Stag MTPRB 151 0 0 151 0 139 11

NWPRB 0 0 0 0 0 0 0

SWPRB 0 0 0 0 0 0 0

GILLETTE 0 0 0 0 0 0 0

EAST GILLETTE 0 0 0 0 0 0 0

Total 151 0 0 151 0 139 11

Total beds MTPRB 228,542 4,880 1,219 222,543 30,653 31,031 160,848

NWPRB 293,541 332 146 293,063 4,277 33,541 255,238

SWPRB 375,881 167 2 375,711 6,224 31,041 339,809

GILLETTE 256,632 466 4,871 251,294 22,500 13,892 214,899

EAST GILLETTE 7,153 622 69 6,462 438 2,063 3,956

Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
214 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 8. Summary of coal resources by reliability, depth, ownership, and assessment area categories in the Powder River Basin, 

Wyoming and Montana.

[MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette 

coal field; East Gillette (area east of the Gillette coal field)]

Coal bed

name Reliability Originalresources

Burned

coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Percent

of available

resources

Coal resources and restrictions for 47 coal beds greater than or equal to 2.5 feet thick, reported in millions of short tons by reliability

(see table 4)

Total beds Measured 301,189 1,126 4,120 295,948 17,827 14,232 263,883 27

Indicated 463,304 2,744 1,954 458,609 18,056 36,262 405,215 42

Inferred 381,662 2,389 232 379,035 25,548 56,915 296,620 30

Hypothetical 15,688 210 0 15,480 2,668 3,775 9,032 1

Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752

Coal bed

name

Overburden

depth

(feet)

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Percent

of available

resources

Coal resources and restrictions for 47 coal beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth

(see table 5)

Total beds 0–500 304,254 6,467 5,712 292,073 49,000 30,633 212,439 22

500–1,000 286,536 0 334 286,201 7,444 27,718 251,042 26

1,000–2,000 428,340 1 198 428,141 6,012 31,597 389,863 40

2,000–3,000 107,387 0 59 107,327 1,481 17,543 109,015 11

>3,000 14,871 0 3 14,869 164 2,319 12,405 1

Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752

Coal bed

name Ownership Originalresources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resources

Percent

of available

resources

Coal resources and restrictions for 47 coal beds greater than or equal to 2.5 feet thick, reported in millions of short tons by ownership

(see table 6)

Total beds Federal 985,692 4,941 5,293 975,480 50,607 90,959 833,900 86

State 72,742 324 336 72,076 3,117 7,021 61,930 6

Private 103,415 1,203 673 101,523 10,372 12,195 78,922 8

Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752

Coal bed

name

Assessment

area

Original

resources

Burned

 coal

Mined

coal

Remaining

resources

Land-use

restrictions

Technical

restrictions

Available

resource

Percent

of available 

resources

Coal resources and restrictions for 47 coal beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area

(see table 7)

Total beds MTPRB 228,542 4,880 1,219 222,543 30,653 31,031 160,848 17

NWPRB 239,541 332 146 293,063 4,277 33,541 255,238 26

SWPRB 375,881 167 2 375,711 6,224 31,041 339,809 35

GILLETTE 256,632 466 4,871 251,294 22,500 13,892 214,899 22

EAST GILLETE 7,153 622 69 6,462 438 2,063 3,956 0.4

Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
Tables 215

Table 9. Summary of resources by reliability categories for all 47 coal beds assessed in the Powder River Basin and comparison of 

reliability of previous assessment of the Wyodak-Anderson zone in the Gillette coal field (Ellis and others, 1999) to the current Powder 

River Basin assessment.

Reliability category Measured Indicated Inferred Hypothetical Total

Reliability of 47 coal beds assessed in the Powder River Basin

Tons (billions of short tons) 301,189 463,304 381,662 15,688 1,161,850

Percent of total 26 40 33 1 100

Reliability of coal beds in the Wyodak-Anderson coal zone assessed in the Powder River Basin

Powder River Basin Assessment

Tons (billions of short tons) 206,945 255,974 128,258 4,875 596,052

Percent of total 35 43 22 1 100

Ellis and others, 1999, Gillette coal field, Powder River Basin: 

Geology, coal quality, and coal resources, in U.S. Geological Survey Professional Paper 1625–A

Tons (billions of short tons) 43,670 167,700 303,700 35,610 550,700

Percent of total 8 30 55 6 100

Reliability of coal beds in the Wyodak-Anderson coal zone assessed in the Gillette coal field

Powder River Basin Assessment

Tons (billions of short tons) 94,433 51,950 10,769 214 157,366

Percent of total 60 33 7 0 100

Ellis and others, 1999, Gillette coal field, Powder River Basin: 

Geology, coal quality, and coal resources, in U.S. Geological Survey Professional Paper 1625–A

Tons (billions of short tons) 14,000 48,000 51,000 1,800 110,000

Percent of total 12 42 45 1 100

Table 10. Example of a regional mine model stratigraphic sequence used in the economic evaluation of the Northern Wyoming Powder 

River Basin assessment area, River Wyoming.

Coal bed

name

Interburden/overburden

(feet)

Stripping ratio

1:1 2:1 3:1 4:1 5:1 6:1 7:1 8:1 9:1 10:1

Bed 6 Average overburden thickness 146 263 380 498 615 732

Average thickness 11 11 11 11 11 11

Bed 5 Average overburden/interburden thickness 106 125 125 125 125 125 125

Average thickness 15 15 15 15 15 15 15

Bed 4 Average overburden/interburden thickness 51 95 95 95 95 95 95 95

Average thickness 22 22 22 22 22 22 22 22

Bed 3 Average overburden/interburden thickness 102 105 105 105 105 105 105 105

Average thickness 21 21 21 21 21 21 21 21

Bed 2 Average overburden/interburden thickness 26 55 55 55 55 55 55 55 55

Average thickness 16 16 16 16 16 16 16 16 16

Bed 1 Average overburden/interburden thickness 26 60 60 60 60 60 60 60 60 60

Average thickness 24 24 24 24 24 24 24 24 24 24

Total coal 24 40 80 98 109 109 109 109 109 109

Total burden 26 86 268 421 586 703 820 938 1,055 1,172

Total interburden 26 86 268 421 440 440 440 440 440 440
216 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 11. Estimated impacts of compositing the originally excluded shale, pyrite, and other high-ash parting material with the coal analyses for the USGS-1 core hole (Luppens, 2011) from the Lake DeSmet coal area, Wyoming. Because these coal quality parameters are reported on a weight basis, mass weighting is the more appropriate method of mathematically compositing samples (Luppens and others, 1992). Lithologies Total core thickness (feet) Analytical parameters Volumetric weighting Mass weighting Ash (percent)1 Calorific value (British thermal unit per pound) Volume (percent) Ash percent X volume (percent) Calorific value X volume percent (British thermal units per pound) Density (grams per cubic centimeter)2 Thickness X density Mass (percent) Ash percent X mass (percent) Calorific value X mass percent (British thermal units per pound) Shale excluded 7.1 65.0 1,500 13.1 8.5 196 1.9 13.5 17.7 11.5 266 Total coal analyzed 47.1 5.0 7,813 86.9 4.3 6,790 1.3 62.6 82.3 4.1 6,429 Total 54.2 100.0 12.9 6,986 76.1 100.0 15.6 6,694 1Ash and calorific values are the averages for USGS-1 core adjusted to 30.5 percent moisture and estimated values for the excluded shale.

2Density values are estimated.

Table 12. Coal resources and reserves for beds greater than or equal to 5.0 feet thick in each assessment area in the Powder River Basin, Wyoming and Montana. (Reported in billions of short tons.)

Resources/reserves East Gillette Gillette coal field Northern Wyoming Powder River Basin Southwestern Wyoming Powder River Basin Montana Powder River Basin Powder River Basin

Original Resource for 47 beds 7 257 294 376 229 1,156

Resources East Gillette Gillette coal field Northern Wyoming Powder River Basin Southwestern Wyoming Powder River Basin Montana Powder River Basin Powder River Basin

Roland (Baker), Smith, 

Anderson Upper Rider, 

Anderson, Dietz 3, 

Canyon

Roland (Baker), Smith, 

Anderson, Dietz 3, 

Canyon, Lower Canyon, 

Werner

Roland (Baker), Smith, Anderson, 

Dietz 2, Dietz 3, Canyon, Werner, 

Pawnee, Rosebud/Knobloch, 

Flowers-Goodale

Roland (Baker), Smith, Anderson 

Upper Rider, Anderson, Dietz 2, 

Dietz 3, Canyon, Lower Canyon, 

Werner, Rosebud/Knobloch, 

Flowers-Goodale

Original (listed beds) 0 164 158 0 151 473

Remaining (listed beds) 0 158 157 0 150 465Available (listed beds) 0 84 56 0 39 179Recoverable (listed beds) 0 77 50 0 35 162Reserves 0 10 1.5 0 13 24.5
Tables 217

Table 13. Underground resources for coal beds 10–20 feet thick and greater than 500 feet deep in the Powder River Basin, Wyoming 

and Montana (reported in millions of short tons). Columns may not sum exactly because of rounding.—Continued

Coal bed

name

Depth

(feet)

Northern

Wyoming Powder 

River Basin

Southwestern

Powder 

River Basin

Montana Powder 

River Basin

Total short

tons by bed

Percent of total 

underground

resource

Roland (Baker) 500–1,000 6,254 0 0 6,254

500–1,500 0 4,187 0 4,187

1,000–2,000 9,308 0 0 9,308

1,500–2,000 0 158 0 158

Greater than 2,000 109 0 0 109

Total 15,672 4,345 0 20,017 7

Smith 500–1,000 831 0 0 831

500–1,500 0 75,957 0 75,957

1,000–2,000 3,447 0 0 3,447

1,500–2,000 0 5,945 0 5,945

Greater than 2,000 67 0 0 67

Total 4,346 81,902 0 86,248 28

Anderson 500–1,000 3,540 0 897 4,437

500–1,500 0 6,420 0 6,420

1,000–2,000 2,547 0 0 2,547

1,500–2,000 0 53 0 53

Greater than 2,000 0 0 0 0

Total 6,087 6,473 897 13,457 4 

Dietz 3 500–1,000 5,610 0 754 6,364

500–1,500 0 8,303 0 8,303

1,000–2,000 5,322 0 6 5,328

1,500–2,000 0 1,980 0 1,980

Greater than 2,000 39 0 0 39

Total 10,972 10,283 760 22,015 7 

Canyon 500–1,000 3,334 0 4,163 7,497

500–1,500 0 28,846 0 28,846

1,000–2,000 3,319 0 70 3,389

1,500–2,000 0 22,767 0 22,767

Greater than 2,000 124 0 0 124

Total 6,777 51,613 4,233 62,623 21 

Lower Canyon 500–1,000 401 0 2,408 2,809

500–1,500 0 10,497 0 10,497

1,000–2,000 6,125 0 119 6,244

1,500–2,000 0 13,849 0 13,849

Greater than 2,000 954 0 0 954

Total 7,481 24,346 2,527 34,354 11 

Werner/Cook 500–1,000 2,871 0 6,963 9,834

500–1,500 0 934 0 934

1,000–2,000 4,282 0 39 4,321

1,500–2,000 0 2,386 0 2,386

Greater than 2,000 3,204 0 0 3,204

Total 10,358 3,320 7,002 20,680 7 

Otter 500–1,000 0 0 0 0

500–1,500 0 1,972 0 1,972

1,000–2,000 0 0 0 0

1,500–2,000 0 16,596 0 16,596

Greater than 2,000 0 0 0 0

Total 0 18,568 0 18,568 6

Pawnee 500–1,000 0 0 1,855 1,855

500–1,500 0 0 0 0

1,000–2,000 0 0 639 639

1,500–2,000 0 0 0 0

Greater than 2,000 0 0 0 0

Total 0 0 2,494 2,494 1
218 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana

Table 13. Underground resources for coal beds 10–20 feet thick and greater than 500 feet deep in the Powder River Basin, Wyoming 

and Montana (reported in millions of short tons). Columns may not sum exactly because of rounding.—Continued

Coal bed

name

Depth

(feet)

Northern

Wyoming Powder 

River Basin

Southwestern

Powder 

River Basin

Montana Powder 

River Basin

Total short

tons by bed

Percent of total 

underground

resource

Rosebud/Knobloch 500–1,000 0 0 10,271 10,271

500–1,500 0 0 0 0

1,000–2,000 0 0 1,251 1,251

1,500–2,000 0 0 0 0

Greater than 2,000 0 0 0 0

Total 0 0 11,522 11,522 4

Flowers-Goodale 500–1,000 0 0 6,468 6,468

500–1,500 0 0 0 0

1,000–2,000 0 0 5,854 5,854

1,500–2,000 0 0 0 0

Greater than 2,000 0 0 3 3

Total 0 0 12,325 12,325 4

Total 500–1,000 22,841 56,620 19

500–1,500 137,116 33,902 137,116 45

1,000–2,000 34,350 42,328 14

1,500–2,000 61,348 7,978 65,706 21

Greater than 2,000 4,497 41,880 4,500 1

Total 61,688 198,464 3 304,303

Percent of total underground resource 

by assessment area

20 66 14

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Luppens and others—Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana—Professional Paper 1809