THE GEOLOGICAL SURVEY OF WYOMING Daniel N. Miller, Jr., State Geologist

REPORT OF INVESTIGATIONS No. 22

COALS AND COAL-BEARING ROCKS OF THE HANNA COAL FIELD, WYOMING

By Gary B. Glass and Jay T. Roberts

Portions of this report were developed through the use of funds provided by the Laramie Energy Technology Center, U.S. Department of Energy

LARAMIE, WYOMING

1980 First printing of 1500 by the Pioneer Printing and Stationery Company, Cheyenne.

Additional copies of this report are available from: The Geological Survey of Wyoming Box 3008, University Station Laramie, Wyoming 82071

Copyright 1980, The Geological Survey of Wyoming

Front Cover: Typical strip mine in the Hanna coal field. THE GEOLOGICAL SURVEY OF WYOMING Daniel N. Miller, Jr., State Geologist

REPORT OF INVESTIGATIONS No. 22

COALS AND COAL-BEARING ROCKS OF THE HANNA COAL FIELD, WYOMING

By Gary B. Glass and Jay T. Roberts

Portions of this report were developed through the use of funds provided by the Laramie Energy Technology Center, U.S. Department of Energy

LARAMIE, WYOMING

1980 CONTENTS

Page

Introduction 1

Structural geology 2

Folds 2

Faults ...... 4

Joints 5

Coal-bearing rocks and coal beds 11

General 11

Lithologic character of coal-bearing rocks 12

Hanna Formation coal beds 14

Ferris Formation coal beds 17

Medicine Bow Formation coal beds 21

Mesaverde Group coal beds 21

History of coal deposition 23

Coal rank, chemical composition, physical properties, and petrography ...... • ...... 24

Rank ...... 24

Chemical com,position ...... 30

Physical properties • • • • • • . • • • • • • . • • • • • • • • . • . . • • • • • • • • • • • • • • • • • • • • • • • 30

Petrography • • • • • • • • • • • • • • . • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • . • • • • • • . • • • 31

Mining activity .•••••••••••••••••.•••••••••••••.••••••••••••••••••••••••• 32

coal resources and reserve base • • • • • • • • • • • • • • • • . • • • • • . • • • • • • • • • • • • • • • • . • • 34

References ...... • ...... 40 FIGURES

Figure Page

1 Wyoming coal-bearing areas ...... 1

2 Coal mining districts in the Hanna Coal Field •..•.••...... ••...•. 2

3 Generalized structural geology of the Hanna Coal Field .....•....• 3

4 Normal fault with 40 feet of vertical displacement •.•.••.••.•••.. 4

5 Closely spaced fracture zone immediately adjacent to a major fault • • • . . • . . • • • . • . • • • • • . . . • ...... • • • • • • . . • . • . • . • • • . • • • • . . . 5

6 Joint sets in the coals of the Hanna and Ferris formations •••.•.. 6

7 Systematic joints in coal 7

8 Geologic map of the Hanna Coal Field ••.•...•..••••.•••...... 9

9 Generalized stratigraphic columns for the Hanna Coal Field • • • • . . • . • • • • . • ...... • • • • • • . . . . • . . . • • • . . . • ...... • • • • • . . 10

10 Cut-bank side of ancient river channel, now filled with sandstone . . • • • . . . • • . • • ...... • ...... • • • . . . • • • • • • . 13

11 In situ tree trunks rooted in an interbedded coal and shale sequence overlying Bed No. 80 •...••.••••••....••..•..••••.. 13

12 Coal nomenclature in the Carbon Mining District of the Hanna Coal Field . . • ...... • . . . . • • . . • ...... • . • . . • . . • • ...... • . . 15

13 Coal nomenclature in the Hanna Mining District of the Hanna Coal Field • • ...... • • • • . • . . • • • . . • . • • • • • • • • . • ...... • . . • . . . . . • 16

14 Bed No. 79 in the Seminoe No.2 strip mine ...••..•...... ••.. • ... 17

15 Coal nomenclature in the Seminoe Mining District of the Hanna Coal Field .••••...... •.....•..•.•....•...•.••• , • . • • . • • . • • 18

16 Coal nomenclature in the eastern portion of the Corral Creek Mining District of the Hanna Coal Field .•.•.••....•..•.•..• 19

17 Coal nomenclature in the northern portion of the Corral Creek Mining Distirict of the Hanna Coal Field ..•..•...•.•••••••. 20

18 Coal nomenclature in the central portion of the Corral Creek Mining District of the Hanna Coal Field •.....••...... 22

19 Coal nomenclature in the southern portion of the Corral Creek Mining District of the Hanna Coal Field ..•..••...... 22

iii 20 Variation in apparent coal rank as indicated by moist, mineral-matter-free heat value ••.•••••••••••••••••••••••••••••••. 25

21 Fires often start in the strip mines by spontaneous combustion 31

22 Arch Minerals' Seminoe No. 1 strip mine in the Ferris Formation . • • • • . • . • • • • . • . . . • . • • . • . . • • . • . • • • . • • • • • • . • • . • . • . • • • • . • • . 32

23 Strippable coal deposits and mining activity in the Hanna Coal Field • . . . • • • • . . . • • . . • • . • • • • • • • . • • • • • • • • • • • • • • • • • • • • • • • 3 3

24 Mine subsidence often provides stark evidence of Wlderground mining . • . • • • • • • • • • • • • • . • • • • • • . • • • • • • • • • • • • • • • • • • • • • • • 34

TABLES

Table Page

l Estimated cumulative coal thicknesses in the Hanna Coal Field • . • • • • • • • • . • • . . • • . • • • • • • • • . • • • • • . • • • • • • • • • • . • • • • . 12

2 Summary table of ultimate and proximate analyses, heats of combustion, and major oxides of coal ash for coals in the Hanna Coal Field ••••••••••• , . • • • • • . . • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 26-27

3 Concentrations of trace elements in coals of the Hanna Coal Field • • . • • • • • • • • . • • • • • • • • • • • • • • • . • • • • • • . . • • • • • . • • • • • • • 28-29

4 Fusibility of coal ash •••••.•••••••••••••••.••••••••••••••••••••• 31

5 Current and proposed coal mining activities in the Hanna Coal Field • • • • • . • • . • • • • . • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 35

6 Remaining strippable coal resources and strippable reserve base of the Hanna Coal Field by mining district, January l, 1978 • • • . . • . . . • • • • • • • . • • • • . • • • • . • • • • • • . • • • • • • • • • • • • • . • • • • • • • • • • • • • 37

iv INTRODUCTION

Although most of the Hanna that are underlain by rocks of the Coal Field of southcentral Wyoming Mesaverde Group. With this conven­ lies within Carbon County, a small tion, all other coal-bearing rocks portion extends eastward into of the Hanna Coal Field occur with­ Albany County as well (Figure 1). in the outcrop of the Mesave rde This coal-bearing area coincides since they all overlie that group. with the Hanna and Carbon topo­ The boundary between this field and graphic and structural basins and the Rock Cree k Coal Field to the is considered part of the U.S. east is usually drawn to coincide Geological Survey's Rocky Mountain with the alluvial deposits associated Coal Province. As defined, how­ with Rock Creek. eve r, the coal field is limited to those portions of the basins Based on past and present mining

Yt liow t lon e

Po 1I

GOSHEN \HOLE COAL FIELD I \~. · I I ~~ ::! : A lban r ~- -L · ~ ?· I - ROCI( I CREEK Lo•om•t COAL I Cor bon Fl ELD

[ill] SUBBITUMINOUS ~BITUMINOUS S LIGNITE • STRIPPABLE DEPOSITS * Prtllmonory • baud on co111pony data Figure 1. Wyoming coal-bearing areas.

1 activity, Glass and Roberts (1979) boW1daries of these districts are defined four mining districts within shown on Figure 2. Areas barren of the field: the Hanna, Carbon, Serninoe, near-surface coals serve to roughly and Corral Creek districts. The delimit one district from another.

86 85 83 82

Milu 0 10 20 AA A AW 81

24 N MINING I ....:1~ "' .. 23 DISTRICT i ...... ,.. 711 77 MINING ...... ,.. 22 DISTRICT •••

CARBON 21 MINING DISTRICT

20

19

Figure 2. Coal mining districts in che Hanna Coal Field

STRUCTURAL GEOLOGY

Folds axes are nearly perpendi cular to one another (Figure 3). A low Host simply, the Hanna Coal northwest-southeast trending ridge Field coincides with two sediment­ separates the two synclines about filled intermontane basins between three miles northeast of Hanna. uplifted areas. These basins are The southernmost of these synclines separated from one another by the is called the Hanna Syncline; the Saddleback Hills Anticline with northernmost syncline is unnamed. the Hanna Basin lying to the north and the Carbon Basin lying to the Like other intermontane basins south . The Hanna Basin is itself of Wyoming, these depressions formed separated into two synclines whose during the Laramide Orogeny, some

2 Figure 3. Generalized structural geology of the Hanna Coal Field, Wyoming. EXPLANATION Figure 3.

FAULTS NORMAL FAULT ------••••••••• THRUST FAULT ------..,T - _... (DASHED WHERE APPROXIMATELY LOCATED ANO DOTTED WHERE 6 REVERSE FAULT A " A...b..1\ • .4'., CONCEALED) R 81 W FOLDS ANTICLINE ______,___ -- ...... -- - - SYNC LI NE • (DASHED WHERE APPROXI MATELY ---.------LOCATED) OVERTURN ED SYNCLINE ---fr------

STRIKE ANO DIP OF BEDS

STRUCTURAL FORM LINES DRAWN cf( ON TOPS OF VARIOUS COAL BEDS /~ ( CO NTOUR INTERVAL 400 FEET)

R 79 W R 78 W R 77 W

Jo i

1~1 ICJ-i

10~ 12:.. ,.. 0 ~ 60 16"' .... 16 FORM LINES DRAWN ' i 6.\ 16\ f-26 1-25 ON TOP Of FINCH COAL 9..j 101 12 BED IN CARBON BASIN f-40 y .J-\ "'I 40 ...... J- t6.\ ,.,}, l-:J1 -")( ~50 ~to f ..C35 tJ 20-\ ' 18)... \

EB f.1t .....22

T 19 N R 86W R 85W R 84 W R 83 W R82 W

..... "':.t·.. . "(" . T 16 . . ..,.. 1-,, --< L,.. 46 24 16 \To i ,( 111 I 4o ;.,6 \ ,(15 N J. 9 112 ' I " ,, l-15 -< Z/I l-101 ,/ \•6 $, /-10 1-; J.10 l-13 ),o t- 0 ! 1-zo \ --'-... ~ HANNA BASIN .... , fl f.16 '<'o '<.'' '- -., ,.._ T '<20 l-111 T ~, ._.,,,. -..;r..... rHERE IS NO SUBSURFAC 23 CONTROi.. ON ANY COAL -< ~ /$ l-18 l- 15 BED IN THIS AREA OF 15 j-ZI N THE BASIN 1-10 1-zo 'flO

f. 15 ~10 I-"' l-zzl-12

9 '< ':zo ': 2 '<.15 '<27 '<28 T 22 N

T 21 N

T O 5 10 MILES E::::3C:::::::J:e-+3:=::::i:=::::EE+3:=3:=:=:=:=:=:=:====::::::i 20 SCALE N

COMPILE D FROM: DOBBIN AND OTHERS (1929) KNIGHT (1951) LOVE AN 0 OTHERS ( 1900) BAYLEY (1968) MEREWETHER (1971),(1972) (1973) LOWRY ANO OTHERS (19nl) GLASS ANO OTHERS (1979) 3 38-65 million years ago. The Hanna dips are much flatter in the central Basin, however, is rather atypical portions of the three major synclines, in that it is not only extremely averaging 3-15 degrees (Figure 3). deep for its size (Knight, 1951, estimated more than 30,000 feet of sedimentary rock overlie its crys­ Faults talline basement) , but a good por­ tion of its sedimentary rocks are Faulting is not limited to the tightly folded and faulted. Even major reverse fault that separates some younger coal-bearing rocks the basin from uplifted areas to the (Paleocene age) steepen to vertical north or to the faulting that is dips or overturn on the northern flank common to the western and south­ western flanks of the basin (Figure 3). Normal faults occur within the more gently folded coal-bearing synclines as well. In these syncli­ nal areas, the frequency of faulting shows a direct correlation with the intensity of coal mining. More faulting is mapped in the mined areas than the outlying areas. This ob­ servation suggests that many faults probably remain undetected until an area is mined.

At least in the Hanna and Seminoe mining districts, the pre­ dominant trend of normal faults is northwest at 306-317 degrees (N.S4°W. to N.43°W.). Faults in the Seminoe District exhibit the slightly greater northerly trend (317 degrees). Cross-faulting be­ tween these major northwest-south­ east trending faults is quite common. It is also not uncommon for these major faults to occur within 500 feet of one another.

Unlike the northwest-south- eas t trending faults of the Hanna and Seminoe districts, normal faults in the carbon District trend more Figure 4. Normal fault with 40 feet nearly east-west, averaging about of vertical displace~nt. 76 degrees (N.76°E.). Elsewhere in the coal field, faults are more variable in orientation and type. of the basin as they approach a major fault that separates the basin from Typically, vertical displace­ the ranges to the north. Elsewhere ments on the normal faults in the in the coal field, rocks that crop Hanna and Carbon basins are less out on the flanks of the basin are than 200 feet although some greater folded and steeply dipping (greater displacements occur. Displacements than 25 degree dip). In contrast,

4 Figure 5. Closely spaced fracture zone immediately adjacent to a major fault (frac­ tures strike par­ allel to the fault).

on the order of tenci of fpet are Set A 290-295° (N. 70-65°W. ) most common (Figure 4). To date, Set B 320-330° (N. 40-30°w.) faults observer1 by the authors have Set C 23-25° (N. 23-25°E.) only exhibited vertical slickensides. Set D 60-70° (N. 60-70°E.) Dobbin, Bowen, nnd Hoors (1929), however, rPport seeing evidence of Figure 6 shows these joint measure­ horizontaJ movement as well. Re ­ ments plotted on two rose diagrams. cent coal i sopach maps, comp Ll ~d The left rose diagram shows the by the authors, also strongly sug­ joint sets measured in the Ferris gest that some faults have movea Formation coals. The right diagram laterally as well as vertically. is for Hanna Formation coals. Be­ While fault breccia has not been cause of the geographic distri­ observed in association wjth these bution of the sampling sites, all normal fauJts, jointing and/or minor the Ferris readings were taken in faulting p:l.rallel t o the trends of the Seminoe Mining District or the major faults have been notea. Typi­ western portion of the basin. All cally, these frcictured zones extend the Hanna Formation coal readings no more than a few feet from the were taken in the Hanna Mining main fault (Figure 5). District or the eastern portion of the basin. As evidenced by the rose diagrams, all joint sets ex­ Joints cept Joint Set D are apparently rotated slightly clockwise in the Based on joint orientations western portion of the basin. Joint taken at 32 different sites, four Set D, however, differs by 10 de­ joint sets are recognized in t he grees in a counterclockwise direc­ coals of the Hanna Basin portion tion. of the Hanna Coal Field:

5 FERR IS FORMATION HANNA FORMATION

{'J o· I / I / ' I/ c I /

>lo"-

Figure 6. Joint sets in the coals of the Hanna and Ferris formations.

Joint Set A (290-295°), which relationship might have. It may is well developed in the Ferris For­ simply be coincidental. It is pos­ mation coals, is almost unrecog­ sible that Joint Set B and Joint nizable in the Hanna coals to the Set D in the Ferris Formation coals east. This joint set and Joint comprise a second orthogonal joint Set C comprise one orthogonal system. Unfortunately, the exis­ joint system in this area as they tence of this second orthogonal are very nearly perpendicular to system is less convincing in the one another. Hanna Formation coals.

Joint Set B (320-330°), on the Joint Set c (23-25°) is the other hand, is most obvious in the most often observed joint set of the Hanna Formation coals and poorly four. Although it shows little developed in Ferris coals to the difference in orientation in the west. In the Hanna District this two formations, its average orien­ joint set exhibits the same orien­ tati on in the Ferris coals may be tation as the predominant faulting at least two degrees more eastward in that area. Incidentally, this than in the Hanna coals. As men­ is the only joint set that parallels tioned earlier, this joint set and the direction of local faulting. Joint Set A comprise an obvious It is unclear what significance this orthogonal joint system.

6 Figure 7. Systematic joints in coal.

Joint Set D (60-70°) is less These systematic joints are vertically commonly noted but nonetheless ob­ persistent; that is, they do not ter­ vious in coals of both areas. Its minate at petrographically different orientation in the Ferris coals zones in the coal (lithotypes) or (60°) is ten degrees north of the at bedding planes within the coal. 70° orientation typical of the Hanna Instead, they persist for many inches Formation coals. Again, Joint Sets to as much as several feet down- B and D may comprise a second or­ ward through the coal (Figure 7). thogonal joint system, but less They also do not terminate laterally well developed than Joint Sets A against joints of other orientations. and c. They cut through the other joint sets, exhibiting lateral extents on There is a possibility that the order of many inches to several other joint sets are also present. feet. But until more measurements are taken, the existence of more than In contrast, the less well de­ four joint sets remains specula­ veloped joint sets terminate against tive. Because no joint orienta­ the more persistent and pronounced tions were measured in the Carbon systematic joints and seldom cross Basin, nothing can be said about differing coal lithotypes or bed­ the joints in that area. ding planes in the coal. These joints are likened to the nonsys­ Because the vertical and la­ tematic joints of Nickelsen and Hough teral persistence of these various (1967). joint sets were not systematically noted, only a few general comments Nickelsen and Hough (1967) are possible. Some joint sets, felt that both the systematic and most notably Joint Set C and to a nonsystematic joints were extension­ lesser extent Joint Sets A and B, al in origin. While their syste­ might best be termed systematic matic joints were believed to form joints (Nickelsen and Hough, 1967). early, independent of folds and

7 8 EXPLANATION Figure 8.

TERTIARY CRETACEOUS

NORTH PAPK FORMATION IKmb I MEDICINE BOW FORMATION

~ rr;bl WAGON BED AND WHITE LEWIS SHALE (INCLUDES FO>C ~ l.!!.Ll RIVER FORMATIONS HILLS SAN DSTONE) R 81 W ~

1b a Twr HANNA FORMATION MESAVERDE GROUP

FERRIS FORMATION STEELE SHALE (OLDEST ROCKS (BASAL PORTION IS WITHIN THE COAL FIELD BUT CRETACEOUS) BARREN OF COAL)

•Tu TERTIARY UNDIVIDED FAULT ------••••••••• (DASHED WHERE APPROXIMATELY LOCATED ANO DOTTED WHERE CONCEALED)

COAL OUTCROP MORE THAN 5 FEET THICK------·- !DASHED WHERE APPROXIMATELY LOCATED)

R 78 W R 77 W

____ .,,,

Km~.l/' / /-) ..... / / ><.,_ mv t/'

T 19 N Figure B. Geologic map of the Hanna Coal Field, Wyoming. R 86W R 85W R 84 W R 83 W R82 W

Kmv

T

T Kmv N

~ ...... Kmb '-, \. Th T 23 N

' ' Km11

T 22 N

T 21 N Tnp

To Rowllna

N T 20 SCALE ~ N

COMPILED FROM: DOBBIN AND OTHERS (1929) LOVE AND OTHERS (19!S!S) BAYLEY (1968) MEREWETHER ( 1971 ), (1972), ( 19731 LOWRY ANO OTHER (1973) GLASS ANO ROBERTS (1979) 9 HYDEN AND McANDREWS ( 1967) HANNA BASIN CARBON BASIN

0

HANllA ~ 'OllMATIOll i.i \J ~ ~ i::. ~ ~ ~ ),.. ~ ~ ~ ~ i:: ~ q; ~ ~ MEDICINE IOW '"'~ '011MATION \J ~ ...... ~

10,000 ~ i:: L!Wll SHALE ~

~ LOWlll DANA COAL

"II) .... MEUVEllO! ~ ~ GllOU .. " 1!1,000 ~/

PORTIONS OF FORMATIONS

l0,000 BEARING STRIPPABLE COAL RESOURCES AND STRIPPABLE RESERVE BASE

"NE lllOH UNOITONE H,000 ALLEN 11100! ,OlllllATION I HAYSTACK MOUNTAIN I ,OllMATION H,000 ....._~~~--''--~...... ~~~---'

Verliul lc•I• IA,.. , Figure 9. Generalized stratigraphic columns for the Hanna Coal Field of southcentral Wyoming.

1 0 faults, their nonsystematic or trun­ coal fields of Pennsylvania. They cated joints were: noted that even bright and dull bands within a coal bed behave as minute probably late release type fractures structural rock units, and there­ resulting from a combination of re­ fore alter or deflect the strike of sidual tectonic stress differences joints as they pass from one band and surficial stress differences to another. This phenomenon is much arising in blocks between succes­ more pronounced when the joint orien­ sive systematic joints during ero­ tations found in coals are compared sion and unloading. with the orientations of the same joint sets in overlying sandstones At this time, it is not clear whether and shales. Glass (1972a) observed these conclusions are equally appro­ as much as a 2.5° shift in orienta­ priate to explain jointing in the tion as a joint passed from one Hanna Basin. lithology to another.

Lithologies also affect the Joint spacing also varies con­ orientation of joints. Although siderably with lithology. Generally not enough measurements were taken speaking, joints in sandstones are for a true comparison, the strikes the most widely spaced, measured in exhibited by most joint sets vary terms of feet or yards apart. Joint as they pass through different spacing in shales is best thought lithologies. Nickelsen and Hough of in feet or inches while spacing (1967) and Glass {1972a) mention in coals is more on the order of similar phenomena in the bituminous inches or centimeters.

COAL-BEARING ROCKS AND COAL BEDS

General Coal beds occur in a rock in­ terval up to an estimated 24,000 Although coal beds occur in the feet thick. Coal, of course, ac­ Upper Cretaceous Mesaverde Group and counts for only a minor portion the Medicine Bow Formation, the most of this great thickness of rock, significant beds are in the Ferris probably less than 2 percent (Table Formation of Upper Cretaceous and 1). Coals are most numerous in the Paleocene age and in the Hanna For­ upper 12,000 feet of rock, which mation of Paleocene and Eocene age. comprise the Hanna Formation and In general the older Mesaverde and the upper portion of the Ferris Medicine Bow formations crop out on Formation. These Tertiary age the flanks of the coal field while coals are the youngest in the the younger Ferris and Hanna for­ field (38-65 million years old) mations occupy the more central and also the most exploited coals. portions of the coal field (Fig- Mining of Tertiary coals in the ure 8) . Stratigraphic columns in Hanna Coal Field, which dates back Figure 9 show the approximate posi­ to the 1860's, is still occurring tion of the more persistent coal today. In fact, all the active beds in the Hanna and Carbon basins. mining in the coal field is on Correlation of coal beds between coals of the Hanna or Ferris for­ the two basins is not yet possible. mations.

11 Table 1. Estimated cumulative coal thicknesses ln the Hanna Coal Field. 1

Pomation, Estimated Range in Average Percent of Average int~rval District N of coals cumulative cumulative formation between minable > 5' thick thi ckness thickness thickness coals

Hanna Fm. Carbon Dist. 6 30-70 ft. so ft. l-5\ 300 ft. Hanna. Dist. 24 125-375 ft. 250 ft. 2- 5\ 330 ft. Ferris l'm. Seminoe Dist. 30 135-305 ft. 200 ft. 2-4\ 150 ft. Modiclne Bow Fm. Corral Creek Dist. 3 10-15 ft. 12 ft. l\ 465 ft. Al 1nond Fm. Corral Creek Dist. s 10-40 ft. 25 ft. 1-6!\ 140 ft.

l Generolly does not include coals less than 5 feet thick.

Lithologic Character Dobbin and others (1929) report of Coal-bearing Rocks coarser sandstones at the top of the formation interbedded with thick, Rocks associated with the coals dark gray shale units, Both fresh­ of the Hanna Coal Field are extreme­ and brackish-water fossils are ly variable, consisting of conglom­ found in the Medicine Bow Fonnation. erates, sandstones, siltstones, claystones, and shales. In the Rocks associated with the case of the Mesaverde Almond For­ Ferris and Hanna formation coals mation, Gill and others (1970) are perhaps the most variable in describe the rocks as predominately the coal field. Massive, cross­ very fine grained, thin bedded bedded, sometimes conglomeratic sandstones interbedded with shales. sandstone units are interpreted as Darker, gray shales contain lime­ fluvial in origin, deposited by stone concretions with marine meandering or braided streams. fossils. Other more brownish col­ These units are lenticular in cross ored shales, however, predominate. section and linear or sinuous in These shales contain abundant iron­ plan view. Although they frequently stone concretions and are fre­ crop out as impressive cliffs, in quently interbedded with sandstones reality they are not the dominant and carbonaceous shales. Brackish­ lithology of the coal-bearing rocks. water fossils are common in these By far, the finer grained siltstones , shales and sandstones. claystones, and shales predominate. These fine grained rocks are var­ Rocks of the Medicine Bow iously interpreted as overbank de­ Formation are described as sand­ posits laid down during flooding of stones and carbonaceous shales the major fluvial channels or (Dobbin and others, 1929). The lacustrine in origin, indicating the lower portion of the formation, existence of fresh-water lakes or where most of the coals occur, is ponds. Plant remains, fresh-water principally comprised of massive, invertebrates, and rare vertebrate cross-bedded brown sandstones. remains are the only fossils iden­ Above this basal sandstone and coal tified in these coal-bearing rocks. sequence are interbedded fine grained sandstones and dark shales. Commonly, very dirty coals or

12 Figure 10. Cut-bank side of ancient river channel, now filled with sandstone (note abrupt erosional contact of channel at center of picture).

interbedded coal and shale units All these various lithologies overlie some of the coals. These may abut or grade laterally or units, variously called coaly shale vertically into one another over or carbonaceous shales, are ex­ very short distances or vertical treme~y high in ash (greater than intervals. In the case of the 30%) and not coals in a strict sandstones, abrupt angular contacts sense. Sometimes individual zones with adjacent units are common within these interbedded units are (Figure 10) where sandstones now thick and clean enough to qualify fill erosional channels cut by the as coal, but these zones are not major streams that flowed into the persistent enough to be of much eco­ Hanna Basin from surrounding high­ nomical value in the conventional land areas and then eastward out sense. of the coal field (Ryan, 1977).

Figure 11. In situ tree trunks. rooted in an in­ terbedded coal and shale se­ quence overly­ ing Bed No. BO.

13 The coals of the Hanna Coal Hanna Formation Coal Beds Field are for the m::>st part typical of autochthonous peat accumulations. Although the 2,400 to 8,000 They are generally underlain by feet thick Hanna Formation apparent­ rootworked, hackly s iltstones or ly contains at least 32 coals greater claystones. Soft, plastic clays, than five feet thick, correlation which corrononly underlie Appala­ problems could account for some du­ chian and Midcontinent coals plication among the beds i.e., two are seldom observed, however. Up­ names applied to the same coal in right or in situ tree trunks within separated areas. In particular, the coal or rooted in the top of Hanna Formation coals of the Carbon the coal or in shale or sandstone Mining District (Figure 12) have deposits just over the coal are never been correlated with those particularly commonplace in the in the Hanna District (Figure 13). Tertiary coal deposits (Figure 11) . For this reason, coals in the two districts are treated as separate At least the Tertiary coals beds. There is, however, some evi­ vary considerably in thickness, dence that suggests there may not often quite irregularly. There is be any direct correlation of coals some indication that the more per­ between the two basins (Ryan, 1977). sistent coals may thicken toward the central areas of both the Hanna While the thicker coals of the and Carbon basins, but not all Hanna Formation are 20-60 feet coals exhibit this trend. The thick, most coals in this formation Tertiary coals appear to thin by are much thinner, probably better one or a combination of three ways. characterized as 5 to 11 feet thick. In a few cases they are thinned by At least on the basis of strippable erosion resulting from nearly con­ coal resources, the weighted average temporaneous uplift. Most, how­ thickness of Hanna Formation coals ever, either split into two or is 14.22 feet in the Hanna Mining more benches that gradually thin District and 11.14 feet in the Car­ or pinch out or they interfinger bon Mining District (Glass and with other lithologies, generally Roberts, 1979) . dark shales. In this latter case, the coals split into numerous, Various of the Eocene and Pale­ gradually thinning lenses of coal ocene coals of the Hanna Formation separated by shaly interbeds. occur in three of the mining dis­ This change from coal to interbedded tricts of the Hanna Coal Field: the coal and shale to shale (coaly carbon, Hanna, and Seminoe districts. shale) is usually very gradual and The stratigraphic position of four­ occurs over distances of many hun­ teen mappable Hanna Formation coals dreds of feet. in the Carbon Mining District is shown in Figure 12. This illus­ The variability of Mesaverde tration uses the coal bed nomencla­ and Medicine Bow formation coals ture of Glass (1978). Eight of is not as well understood. There these coal beds are greater than S is some indication that these coals feet thick although, as depicted on exhibit much smaller variations in Figure 12, two of the coals are thickness. No one has documented probably correlative with other the manner in thich these Creta­ coals in the district. The thick­ ceous coals thin, but reconnais­ est coals in the district are the sance work suggests that they Johnson and Finch beds, which are split into benches which gradually up to 32.5 feet and 14.3 feet thin or simply thin without split­ thick, respectively. A coal zone ting. between the Johnson and Finch coal

14 0 - UNNAMED COAL

200

CARBON NO. 6 RIDERS UPPER & LOWER CARBON NO. 6° (6' - 8')

UPPER & LOWEA CARBON NO. 7

BEDN0. 111 BED NO. 110 BED NO. 109, UPPER & LOWER BENCHES• (5'. 8') BED NO. 108 ~ C) ...... BED NO. 107 ..... BED NO. 106 1000 , .., Vertical Scale ~ BED NO. 105° (5') ~ .... - - FINCH BED· (5' - 12.5'), ?CARBON NO. 4• (5' • 12.5') Q: liiiiiii•ll / C) I(~ - JOHNSON RIDERS" (5' • 12.6')

~ . - JOHNSON BED" (5' · 23'); ?CARBON NO. 5• {6'·12.5') """ C) ~ .., ~ UNCONFORMITY ~ ... ~ VARIOUS PRE-HANNA C) ~ C) FORMATION ROCKS ~ ~

• Coala which account for the ah allow coal re1ource1 tabulated for this mining district. Thlcknenes shown In perenthes11.

Figure 12. Coal nomenclature in the Carbon Mining District of the Hanna Coal Field.

15 - -- BED NO. 89° (5' • 7')

500 BED NO. AME 93• (5' • 31 ')

BED NO. AME 92° (5' · 18') 1000 BED NO. as• (5' . 9')

BED NO. 87° (5' · 6 .5 ' )

BEDN0.86• (5'· 11')

BED NO. 86 (UPPER) BED NO. 85 (LOWER)

BED NO. 94• (4.5 ' · 6') 3000 Fut

Vertlc111 Seel•

BED NO. 83" (4.5 ' · 9 ' )

BED NO. 82° (6' · 16.6' ) HANNA NO. 1 BED· (4' . 27')

BED NO. so• (5'. 26' ) BED NO. 79• (5' - 23'1 BED NO. 79• (5' • 21 ') BED NO. 77• (5' · 9 ') •coel1 which account for the shellow coal rftourcft tebuleted for this mining distric t . Thic knesses shown In perentheses. HANNA NO. 2 BED· (5'. 38') BED NO. 75• (7' · 2B' ) BEDN0. 75• (4' ·11' ) BED NO. 74• (6' - 11 ') BED NO. 73• (!5 ' • 8')

HANNA NO. 5 BED• (5' . 31 ') HANNA NO. 6 (LOWER BENCH)• (5' • 8 ' ) BED NO. 72• (5' • 7') BED NO. 71 • (5' - 7')

Figure 13. Coal nomenclature in the Hanna Mi ning District of the Hanna Coal Field.

16 beds, called the Johnson Rider bed, Ferris Formation Coal Beds for simplicity, is locally charac­ terized by up to 12.5 feet of coal. Beneath the Hanna Formation, the upper part or Paleocene portion Most of the Hanna Formation of the Ferris Formation contains coals crop out in the Hanna Mining at least 28 minable coal beds. Ex­ District. Twenty-three out of tensive faulting in the Seminoe twenty-five persistent coals in Mining District, where these coals that district at least locally are mined, makes correlation dif­ equal or exceed 5 feet in thickness ficult and accounts for more than (Figure 13). Of these 23 coal one name being given to the same beds, 8 exceed 20 feet in thick- coal. Because of this duplication, ness (Bed No. RME 93, Hanna No. 1, more coals are identified than Bed No. 80, Bed No. 79, Bed No. 78, really exist. Figure 15 includes Hanna No. 2, Bed No. 76, and Hanna an attempt to show the approximate No. 5) (Figure 14). The other stratigraphic position of uncor­ coal beds are generally less than related or isolated coal beds in 12 feet thick. In places, the the northwestern portion of the thickest coals, Bed No. RME 93, Hanna Seminoe Mining District. Because No. 2, and Hanna No. 5, all exceed of these problems in correlation, 30 feet in thickness. there are as many as 45 coal beds mapped in the Seminoe Mining District. Although as many as five Hanna Correlation of Ferris coals beneath Formation coals occur in the Seminoe the Hanna Formation of the Hanna Mining District, only the Brooks Mining District is not yet possible coal bed is over five feet in since these Ferris coals lie at thickness (Figure 15) . The other great depths not yet penetrated four coals underlie the Brooks by exploratory coal drilling. bed and apparently are all less than five feet thick. Most minable coals in the Ferris

Figure 14. Bed No. 79 in the Semi­ noe No. 2 strip mine (20 feet thick).

17 8f'00KS 81!0' (8' 8'1 0

BEONO. H 1?1 8f0 No. 68 (11 no ;:::~ - ~ ~ 500 UNNAMEO BEO i elON0. 117 1?1 ~

8£0 NO 511' 111' 5,5'1

BlO N0, 115 ' (5' • 2'1 1000 ,.. , BEDNO. U' Ill'· 1'1 8EO ND. 113' I•' 1.11'1 V•rtlcel Seal• BEO NO. 62' 15' . ,., UD N0. 111A' 111'1 lll!D N0. 61' 15' • II")

BID NO. 80' 8 ,8'1 "' UNCORRELATED OR ISOLATED COAL BEDS IN Tl:IE NORTHWESTERN PORTION OF THE SEMINOE MINING DISTRICT 1

UNNAMED BED eeo NO. 119 ---

HD NO &a• 18' 8 5'1 HOC' 15"1 BED NO. 117 BED F• 16'1 BED 8' 18 ' 1 BED NO 56' (~· 15'1 HO NO 130' Ill' G' I BED NO 55 8£0 £ ' 111'1 IEO NO 121' 15'. 12'1 HOD' 111'1 BED NO. 5•' ID'. 11'1 HO NO, 121' 111'1 Fl HOA' 11'1 8EO NO 127' 15' 111'1 .. 8£0 NO. SJ' 15'1 HO N0, 128 BED NO 52 ~ 8£0 NO. 1211 OEON0. 111' Ill' 10"1 U!O NO 124' 1&' • 11"1 () UNNAMEO 8EO .. IEO NO. 123' 15' 40'1 B!D NO. 110' 15' l2'1 .. GEO NO. 122' (8" 17'1 960 NO, 121' 11' 1 Bf.0 H' (5'1 BED NO 49 BEO NO •B 8~D NO 47 eco c· 110'1 BlD NO$, •& & 45' Ill' l 'l ~ 1-----1- OliD NO ••• 18' . 7 '1 Oli.D NO 4J 1====:::1-::g~~ · :~ 1-----1-.IEO NO. 40 1 Thu• CO.If.,. dtOICHd '"' •h•lr IPPf01Clm1te Htltl tttc~h1c po1ltlon r111th,oe to th• rnt oi 1-----1 '::g ~~ : ~:. 14,5' D'l tht mlnlno district. ...._ BBO NO. 37' Ill' l"I t-----1-aeo NO. 36 BED NO. 3D' 18'1 t-----1 -BED NO, 3•' (5'1 lliD NO 33' (0' 21'1 • Co•ll which Kco1.1nt for the 1h1llow co1tl rot0urc.. t•t>ule1ed for thl\ mlnlnt dl•trlct. Thlckr'lht•t thown In p1r•ntht1u.

""'"""llii;:::::I - ::g ~~ : ~~. 15' 11·1 - BED NO, 30' Ct' l'I IEO NO. 21

-afD NO. 28' c•,5' · 11'1 BCD ND. ,,. 'cs· 11'1

HD NO. 26' 19' · 12')

llD NO. 25• (5" 11.&"I

lll D NO. 24

110 NO. 23

DANA IEO' : 110 NO 22 111 16' • 12') 1..0Wll'I DANA 9101 IEO NO, 21 (!1

Figure 15. Coal nomenclature in the Seminoe Mining District of the Hanna Coal Field.

18 MB 20

0

200

~ ~ ~

~ 1000 Fett Venlcel Seil• I(~

~ .... ~ ... MB19 ~ ~ MB 1e• (6') l4j () ~ ID MB17 ..... "' MB16 .....(..) "' MB1~ •coal which accountt for th• ~ MB14 shellow coil r11ourc11 ubuletad ~ MB13 MB12 for this port ion of th• c_orrel MB 11 Crnk mining district. Thlckn•• MB10 1hown In perenth•••· MB 9 MB Be MB B MB 7 MB 6 MB MB 5~· MB 4 MB 3

MB 2 MB 1 ---- LOCAL BED

FOX HILLS LOCAL BED FOAMATION ----

Figure 16. Coal nomenclature in the eastern portion of the Corral Creek Mining District of the Hanna Coal Field (modified from Texas Instruments, 197Bp).

19 • WH 13 WH12 0

WH 11 100

500 Fett Vertical Scale

WH 10• (5')

WH 9

PENN-WYOMING eeo• (5' . 9') WH 7

•coals which account for the shallow coal rhources tabulated for this portion of the Corral Creek mining dl1trlct. ThlcknesH1 shown In parenthese1.

Figure 17. Coaf nomenclature in the northern portion of the Corral Creek Mining District of the Hanna Coal Field ([Tr)dified from Texas Instruments, 1978u).

20 Formation are thinner than those between the two areas is currently in the Hanna Formation. In fact, impossible. The thickest of the the majority of the coals in the three coals is the Penn-Wyoming coal Ferris Formation are only 5-10 bed, which is up to nine feet thick feet thick. Based on strippable (Figure 17). The other two coal resources, Glass and Roberts (1979} beds are unnamed and only 5 to 6 report that the weighted average feet thick. With one exception, thickness of Ferris coals is 9.79 the informal bed designations in feet, compared to 11.14-14.22 feet Figures 16 and 17 are those of for Hanna Formation coals. Thicker Texas Instruments (19781 and 1978u) Ferris Formation coals are Bed and are not formal names. The No. SO, which is up to 22 feet Penn-Wyoming bed was formally given thick, Bed No. 33, which is up that name by Glass and Roberts (1979}. to 25 feet thick, and Bed No. 123, which at least locally is over 40 In the Corral Creek Mining feet thick (Blanchard and Pike, District and other portions of the 1977). In the case of Bed No. Hanna Coal Field, there are addi­ 123, its thickest expression may tional Medicine Bow Formation coals coincide with an area where an that at least locally exceed five underlying coal (Bed No. 122) has feet in thickness. The Medicine coalesced with it. According to a Bow coals in these other areas, local mining company, as much as 60 however, dip rather steeply, usually feet of coal locally is found at greater than 25 degrees. Little this horizon. Other coals also additional information is available coalesce and become quite thick in on these more steeply dipping coal places. For example, Bed Nos. 28 beds. through 32 apparently do this in the vicinity of the Seminoe No. 1 strip mine (T.22N., R.83W.) Mesaverde Group coal Beds

The oldest coals in the Hanna Medicine Bow Formation coal Field are found in the Upper Coal Beds Cretaceous rocks of the Mesaverde Group. Thicker, potentially minable The next older coal-bearing coals, however, are only reported unit below the Ferris Formation is in the uppermost formation of that the Upper Cretaceous Medicine Bow group, the Almond Formation (Gill, Fonnation (Figure 9). Persistent Merewether, and Cobban, 1970). The coals greater than five feet thick, Almond Formation has as many as however, are fewer in number than seven persistent coal beds that such coals of the Hanna and Ferris reach minable thickness (5 feet or formations. Medicine Bow coal greater). With the exception of beds are usually limited to the the Almond coals in the Corral lower 900-2,600 feet of that for­ Creek Mining District, Almond For­ mation (Merewether, 1971, 1972, mation coals dip at very steep and 1973). Although as many as angles. In the Corral Creek Mining thirty Medicine Bow Formation coals District, however, Almond Formation are mapped in the Corral Creek coal beds occur in two separated Mining District, there are only areas at shallow enough dips for three that are five feet or strip mining (less than 25 degrees). thicker (Figures 16 and 17). Be­ In those areas, several unnamed cause these coals occur in two Almond coals vary between 5-10 isolated areas of the Corral Creek feet in thickness, averaging closer Mining District, correlation to 6 feet thick. Because the two

21 0 0

100 100

WH 11• us·. 10'1

LH a• (II'· 71 WHll I LH 7 N N WH4" (111 ~ LHll () I i:: ~ ~ ... WH 3° Ill' - 6 .6 '1 () =: '°° , •• , ~ L. soo , ... WH2a V-oiScel• rt; ~ V.roc.IScel• "Q i ~ ~- 0 LH 5 i 0 WH 2 ' 15'- 71 ~ .. LJ ! ~ I LH 4° 15' - 7'1 .., WH 1' (5' • 8 .111 () ~ ~ ..,, I I LH3 - • COrell whicll eccount for 1h• lhatlow ~ ~ reoourc• Ub

Figure 18. Coal nozrenclature in the central Figure 19. Coal nomenclature in the southern portion of the Corral Creek Mining District portion of the Corral Creek Mining Di strict of the Hanna Coal Field (rrvdified from or the Hanna Coal Field (IOCJdif ied from Texas Instruments, 1978u) . Texas Instruments, 19781) . areas are isolated from one another, restricted to their outcrops or to correlation between them is impos­ very shallow drilling. sible at this time. There is every likelihood, however, that some of Some additional conunents about the coal beds in these two areas the coal geology are necessary. are correlative with one another. Particularly because of extensive faulting, many coal bed correlations For discussion purposes, Al­ in other reports do not agree with mond Formation coals in the Corral recent mapping by the author (Glass Creek Mining District are given the and Roberts, 1979). For this reason, infonnal designations shown in the coal bed nomenclature in this Figures 18 and 19. These designa­ report does not necessarily agree tions are those of Texas Instruments with coal bed designations of some (19781 and 1978u) and are not for­ mining companies or some published mal names at this time. reports. Every attempt, however, was made to adhere to the nomen­ Like the Ferris Formation coals, clature set up by Dobbin, Bowen, coals in both the Medicine Bow and and Hoots (1929). Pseudonymns for Almond formations cannot be corre­ the various coal beds in this re­ lated at any great depths in the port are provided in Appendix A of Hanna Coal Field. Knowledge of the Glass and Roberts (1979). coals in these two formations is

HISTORY OF COAL DEPOSITION

With the possible exception of Formation became more continental all or part of the uppermost Medi­ in nature as the sea retreated be­ cine Bow Formation, Upper cretaceous yond Wyoming's borders. The upper­ coals in the Hanna Coal Field are most Medicine Bow Formation contains probably all derived from peat only a few coals, which are proba­ swamps that accumulated in close bly derived from swamps growing on proximity to a sea some 70-130 a vast plain of low relief, charac­ million years ago. The coals of terized by meandering streams and the Cretaceous Almond Formation, even fresh-water lakes. in particular, are probably the remnants of transgressive and re­ By Paleocene time, Wyoming was gressive swamps that grew along the experiencing widespread erosion shoreline of a widespread Cretaceous and orogenic activity that parti­ seaway that periodically advanced tioned the state into various and retreated across vast portions intermontane basins, one of which of Wyoming and adjacent states, was the area now known as the Hanna including the area now occupied by Basin. The seaways of the Creta­ the Hanna Coal Field. ceous were long gone and the Cre­ taceous rocks were being folded The Upper Cretaceous Medicine and faulted within the basins as Bow Formation was deposited during mountains rose around them. and after the final regression of Detrital Tertiary sediments were the Cretaceous sea from the Western carried into the basins by rivers Interior. Although coals may have and deposited over these older rocks. been paralic in origin at the base of the Medicine Bow Formation, the During this period, peat swamps upper part of the Medicine Bow frequently accumulated over large

23 areas of the intermontane basins, deposits, some lacustrine deposits, including the Hanna Basin. It and flood-plain d eposits (Ryan, is these peats and their associated 1977; Brooks, 1977; Glass, 1979). sediments that became the thick, Although most of the Hanna and Tertiary age, continental se­ Ferris coals are apparently derived quences of rock now called the from peat swamps associated with Hanna and Ferris formations. the flood-plain deposits, others may Rocks observed in these formations be more closely allied with back­ indicate a depositional complex swamps adjacent to braided streams of alluvial fan and braided stream and shorelines of fresh-water lakes.

COAL RANK, CHEMICAL COMPOSITION, PHYSICAL PROPERTIES, AND PETROGRAPHY

Rank apparent rank of Ferris Formation coals is usually subbiturninous A, Based on standard calculations which is similar to that cited in {ASTM, 1974) , the apparent rank of the same older publications. These the coals in the Hanna coal Field observations present an obvious varies from subbituminous A to enigma since the younger coals of high volatile C bituminous. This the Hanna Formation are exhibiting variation in rank, however, is a higher rank than older coals of not simply correlative with the the Ferris Formation. age of the various coals. The Mesaverde Group coals, which are This observation is best ex­ tQe oldest in the field, do exhibit plained by noting the geographic the highest apparent ranks, high location of the coal samples that volatile C bituminous. on the were analyzed. All the analyzed other hand, published reports re- samples of Ferris coals came from fer to the overlying Upper Creta­ the Seminoe Mining District or ceous Medicine Bow Formation coals western part of the field. All as subbituminous in rank (Dobbin, of the analyzed samples of the Hanna Bowen, and Hoots, 1929; Berryhill Formation coals came from the Hanna and others, 1950). But the limited or Carbon mining districts in the number of analyses and the dubious eastern or central portions of the quality of the coal samples that field. Spatial variations in rank, were analyzed leave even the ap­ such as these, can be explained parent rank of the Medicine Bow by variations in depth of burial Formation coals open to question. or alternately by variable heat The rank of Medicine Bow coals must flow within the basin. In this await adequate sampling and analysis. case, variations in depth of burial are probably not the cause since Most surprisingly, recent anal­ some of the very shallowest coals yses of Hanna Formation coals indi­ are the highest in rank. There is cate an apparent rank of high vola­ no evidence to suggest that these tile C bituminous (Glass and RO­ particular coals were ever more berts, 1979, Appendix A). This deeply buried than older Ferris apparent rank contradicts the coals. More likely the variation subbituminous rank reported in in rank across the basin is the older publications (Dobbin, Bowen, result of variations in heat flow and Hoots, 1929; Berryhill and within the basin. The heat flow others, 1950). In contrast, the could have been higher in the central

24 and eastern portions of the basin There is also the intriguing or it may simply have been of longer possibility that the Medicine Bow duration. In either case, the and Mesaverde coals that underlie rank of coals in all the coal­ the central portions of the field bearing formations most probably or crop out on the eastern flanks increases eastward. And indeed, of the field could be high vola­ the highest rank Hanna Formation tile A or B bituminous coals. In coals occur in the Carbon Basin fact, the Mesaverde coals that crop or the east side of the coal out on the flanks of the Saddleback field (Figure 20). Hills Anticline are very probably some of the highest rank coals Whatever the reasons, Hanna that crop out in the field. At Formation coals in the Hanna Coal this time the lack of good analyses Field are best described as high of coals east of the Carbon Basin volatile C bituminous in rank. prevents any extrapolation of rank Ferris Formation coals are sub- eastward beyond that basin. bi tuminous A in rank at least in the Seminoe Mining District. A few parting words of caution Their rank in the other mining are warranted. Because of sampling districts is unknown since there are methods, very few analyses from no analyzed samples from those the Hanna Coal Field were collected areas. There is, however, no in a manner that permits a true reason to suspect that the Ferris rank determination as prescribed coals beneath the Hanna Mining by the American Society for Testing District would not be high vola­ and Materials (ASTM, 1974) . For tile C bituminous like the over­ this reason, the previous discussion lying Hanna Formation coals of of coal rank dealt with "apparent" that district. coal ranks. An "apparent" coal rank,

* 11,170 Btu/lb (FERRIS A"'D ' • MEOIC t"'E aow FORMAT IO,.,Sl •

• 111:)90 Btu/ lb. (HA,.,,.,A FORM­ ATIO,.,•HA,.,NA BASIN)

•12,210 Stu/lb. (HA,.,NA , FORMATION ­ CARBON BASINI D BITUMINOUS D SUBBITUMINOUS

• NONCOAL-BEARING ROCKS • AVERAGE HEAT VALUES IN BRITISH THERMAL UNITS PER POUND ON A MOIST, MINERAL-MATTER- FREE BASIS

Figure 20. Variation in apparent coal rank as indicated by moist, mineral­ matter-free heat value.

25 Table 2. Sunmary table of ultimate and proximate analyses, heats of combustion, and major oxides of coal ash for coals of the Hanna Coal Field.

Hanna Format:i:-0n Hanna Formation Ferris Formation Medicine Bow Me saver.de Hanna District Carbon District Foniation Forliation Mean #Samples Mean I Samples Mean ISamples Mean ISllllples Mean I Samples

Moisture (\) 12.76 155 10.00 so 12.58 139 13. 49 29 12.07 2 Volatile 36.68 " 36. 71 II 34.30 It 35.48 " 34.65 " Matter (\) Fixed 41.82 II 39.55 II 45.19 " 47.24 It 45. 71 " Carbon (\) Ash (\) 8.75 II 13.74 II 7. 93 It 3.81 II 7.57 "

Hydrogen (\) 5.70 34 4.84 14 5.31 33 5.51 7 S.45 2 60.44 46. 84 II 59.29 .. 60. 55 52.65 N Carbon (\) " " " °' Nitrogen (\) 1.14 It 0.97 " I.OS It 1.52 ti 1.15 " Oxygen (\) 24.13 It 16.64 It 25. 17 " 28. 31 " 32. 25 II Sulfur (\) 0. 76 It 2.72 II 0. 49 II 0.54 " 0.50 .. Ash (\) 7.84 ti 27.95 II 8.69 II 3.58 It 8.00 ..

Heat Value 10, 420 158 10,190 198 10,140 198 10,810 24 10,818 16 (Btu/lb) 1 Sulfur (\) 1.00 193 1.35 so 0.46 WO 0;69 27 0;67 23

1 Includes all available sulfur analyses Table 2. Continued.

Hanna Formation Hanna Formation Ferris Formation Medicine Bow Mesaverde Hanna District Carbon District Fonaation Formation Mean I Samples Mean ISamples Mean I Samples Mean ISamples Mean ISamples

Al o (\) 16.9 33 16.5 13 16.4 40 23.0 3 2 3 Cao (\) 16.4 II 7.6 " 17.2 " 2.6 " Fe 0 (\) 8.9 II 14.2 6.5 No 4.9 2 3 " " " 1(20 (\) 0.8 II 1. 9 " 1.0 II 0.3 " MgO (\) 3.4 " 1.5 " 2.7 " analyses 0.5 " Na 0 (\) 1. 0 II 0.2 0.4 II 0.1 II 2 " 1.0 1.1 0.8 0.1 p2°s (\) " " " available " Si0 (%) 32.6 47.3 36.l 53.7 2 " " " " so (\) 13.1 5.5 10.1 4.2 3 " " " " N Ti0 (\) 0.8 " 0.8 " 0.6 " 0.8 " -....i 2 Table 3. Concentrations of trace elements in coals of the Hanna Coal Field (in parts per million on a whole­ coal basis).

Trace Hanna Foraation Hanna Forwation Ferris Foraation Mesaverde For.ation Hanna District Carbon District Element Mean Range tSamples Mean Range ISamples Mean Range I Samples Mean Range tSamples

1 Arsenic (As) 3.3L 0.88 - 7. 7 17 2S 7 - 86 17 4.6 O.S8 - 35 34 1 1 3 Boron (B) 30 10 - 100 17 30 20 - 70 18 30 10 - 76.3 34 20 10 - 50 3

Barium (Ba) 200 100 - 450 20 200 100 - 500 18 300 148. 5 - 1000 36 150 70 - 300 3 2 Berylliua (Be) 0.3L MD - 0.5 19 1.0 NO - l.S 18 Q.SL NO - 2.0 36 l.S 0.7 - 1.5 3 CadJaiUll (Cd) 0.171L 0.060 - 0.50 17 0.54L O.lSL - l.4 18 0.176L .08L - 0.50 35 0.30 0.12 - 0.50 3 Ceriwa (Ce) lOL NO - 70 20 30 NO - 100 18 SL NO - 52L 26 70L SOL - 100 3 Chlorine (Cl) l90L so - 1000 22 Not Deterained 163L lOL - 800 35 Not Deterained Cobalt (Co) 2L 0.5 - 3.53 22 l 0.5 - 10 18 1.5 0.3 - 2.72 40 5 3 - 7 3

Chrom.iua Cr) 7 2.92 - 20 20 10 0.7 - 30 18 10 l.S - 16.l 37 7 3 - 10 3 N 00 Copper (Cu) 10. 0 2.6 - 20. l 20 29 10 - SS 18 11.6 3.3 - 41.3 37 12.4 9.3 - 16 .0 3

Fluorine (F) 78 20 - lSS 17 212 7S - soo 18 lllL 20L - 460 34 68 60 - 80 3 Galliwa (Ga) l.SL 0.37 - 3.18 21 7 2 - 15 18 2L O.SL - 5.97 2S 3 3 - 5 3

Genaaniwa (Ge) 0. 7L NO - 2 19 Not Oeterained 0.31. ND - 2L 36 ND 3 Mercury (Hg) 0.08 0.02 - O.lS 17 0.20 0.10 - 0.36 18 0.081. O.Ol L - 0.40 35 0.03 0.02 - 0.04 3

Lant hanU111 (La) 7 ND - 20 22 30 NO - 10 18 7L NO - SO 39 15 15 - 20 3 Lithiua (Li) 3. 9 0.05 - 8.9 17 19.7 0.49 - 60 18 8.1 0.60 - 20. 2 3S 4.6 4.5 - 4.8 3

Manganese (Mn) 63L UL - 165 19 192 S8 - 410 18 S9L SL - 430 37 11 4.5 - 18 3 MolybdenUll (Mo) 2 0.5 - 8.3 17 5 2 - IS 18 2 0.3 - 3.96 35 1.5 1 - 2 3

1 2 L = less than ND - not detected Table 3. Continued.

Trac.e Element Hanna Formation Hanna Formation Ferris Fol'lllation Mesaverde Fonaation Hanna District Carbon Dist rict Mean Range ISanples Mean Range 'Samples Mean Range ISamples Mean Range I Samples

Niobium (Nb) 1.5L NO - 4L 23 3 NO - 10 18 1.5L NO - 6.1 39 3 3 - 5 3 Nickel (Ni) 7 2 - 15 20 15 7 - 70 18 5 l - 15 36 10 7 - 10 3 Lead (Pb) 3.5L 0.04 - 12 23 11. lL 3 .1 - 25 18 5.2L l.S - 21.S 40 8.1 5.8 - 9.3 3 Anti110ny (Sb) 0.6L O.OlL - 1.2 17 1.6 0.8 - 6.0 18 0.7 0.18 - 1.38 34 0. 4 0.2 - 0.5 3

Scandillll (Sc) 1.5 0.65 - 3 23 7 1. 5 - 15 18 l.5L 0.2L - 7 38 l.S 1.5 - 2 3 Sel eni1111 (Se) 0. 79 0.29 - 2.31 15 3.2 1.5 - 5.1 18 0.67L O.OlL - 1.28 34 2.6 2.4 - 2.9 3

Strontiua (Sr) 150 30 - 470 20 150 30 - 500 18 150 30 - 500 36 100 20 - 200 3 Thoriua (Th) 3.7 0.86 - 8.9 17 6.9 1.8-12.7 18 5. 2L 2.0L - 15. 3 33 4. lL 3L - 6.3 3

Uraniua (U) 1.8 0.6 - 4.2 19 3.9 2.3 - 17 18 2.4 0.1 - 9.6 34 1. 7 1.0 - 2. 2 3 N Vanadiua (V) 15 7 - 30 20 70 10 - 150 18 20 3 - 100 37 15 7 - 15 3 ID Yttrillll (Y) 7 2 - 15 23 20 7 - 50 18 5 l - 20 39 15 7 - 20 3 Ytterbi1111 (Yb) o.s o.u - 1.4 22 2 1 - 5 17 0.7L 0.1 - 1.5 36 l.S 0. 7 - 2 3 Zinc (Zn) 11. 7 0.21 - 35.S 20 69 24 - 140 18 14.7L 0.3L - 97.2 37 22 17.4 - 30.9 3 Zirconiua (Zr) 15 4. 55 - 20 19 30 3 - 100 18 so 3 - 901 36 so 30 - 70 3

2 1 L = less than ND • not detected however, is precise enough on a Glass (1975, 1978), Lord (1913), fresh coal sample to document t he Texas Instruments (1978 a, c-h, j-m, relative differences in rank exhi­ o- s, u), and the U.S. Bureau of bited by coals in the various for­ Mines (1931) as well as unpublished mations and is probably very close company records and government analy­ to the true ASTM rank. ses on file at the Geological Survey of Wyoming. Glass and Roberts (1979) Another complication in any provide a comprehensive listing of discussion of the rank of these coals, coal analyses swrunarized on a bed by is the questionable reliability of bed basis in Appendix A of their ASTM procedures for the classifica­ report. tion of lower rank coals. In the Hanna Coal Field, ranks based strict­ ly on reflectance frequently do not Physical Properties agree with ASTM calculated ranks. It is premature to say that one of these All the coals in the Hanna Coal methods of rank determination is bet­ Field are reportedly nonagglomerating ter than the other, for indeed, neither and therefore exhibit no free-swelling may be wholly satisfactory for low indices. Although the specific gra­ rank coals. The resolution of this vity of the coals in the Hanna Field problem hopefully will come in the is reportedly 1.32 (1800 tons/acre near f uture. foot) for the bituminous Upper Cre­ taceous coals and 1. 30 (1770 tons/ acre foot) for the younger Tertiary Chemical Composition coals (Berryhill and others, 1950), the apparent ranks of various coals The older, Upper Cretaceous coals in this field suggest that these pub­ of the Hanna Coal Field now differ in lished specific gravities may be in­ quality from the younger coals partial­ accurate. Company resource estimates ly because of their different deposi­ also suggest that present information tional histories and partially because on the specific gravity of these coals of their higher rank. The higher rank warrants further investigation. of the Upper Cretaceous coals accounts for their lower moisture contents Glass (1975) swnmarized ash fu­ and higher heat values. Dissimilar sion temperatures for 12 Tertiary depositional histories as well as rank coals in the Hanna Coal Field (Table probably account for some differences 4). From this data, no significant in major, minor, and trace element differences in fusion temperatures for concentrations between the two ages ash of the Hanna and Ferris formation of coals. Unfortunately, there are coals are evident. Data on the fusion too few major, minor, and trace ele­ temperature of Upper Cretaceous coal ment analyses of the Upper Cretaceous ash from the Hanna Coal Field, on the coals of the Hanna Coal Field on other hand, are so rare that meaning­ which to draw any real conclusions ful comparisons are not possible at or comparisons . this time.

Tables 2 and 3 summarize prox­ Coals in the Hanna Coal Field do imate and ultimate analyses, heat not appreciably slake as they dry out. values, and concentrations of major, They are, however, highly prone to minor, and trace elements of coals spontaneous combustion, particularly on the basis of age and mining dis­ the Tertiary coals (Figure 21). This trict. The analytical data summa­ tendency to ignite apparently varies rized in these tables came from the along the strike of a coal bed with Bureau of Land Management (1975) , some areas igniting rapidly and others Dobbin, Bowen, and Hoots (1929), rarely if ever catching fire. No sys-

30 Table 4. Fusibility of coal ash. 1 Hanna Formation Coals Ferris Formation Coals2 Ransze Averasze Range Average Initial Deformation 2080-2230 2100 2080-2400 2190 Temperature(°F) Softening Temperature 2080-2280 2140 2120-2430 2230 (OF) Fluid Temperature 2130-2360 2200 2150-2460 2270 (OF)

1 5 samples 2 7 samples

Figure 21. Fires often start in the strip mines by spontaneous combustion. tematic observations of the sponta­ indicate that the vitrinite group of neity of coals in this field have macerals accounts for well over 80% been made. of the coal on a dry, mineral-rnatter­ free volume basis. The most common The Hardgrove Grindability In­ rnacerals of the inertinite group are dices of the Tertiary coals in the fusinite and semifusinite, which can Hanna Coal Field indicate that they account for over 9% of a coal. Spori­ are relatively hard to grind. In­ nite is the most common exinite group dices for these coals vary from 43 maceral followed by resinite. Scleroti­ to 53, averaging 49. nite, alginite, and cutinite are gen­ erally absent. Because of the sparcity of petrographic data from the Hanna Petrography Coal Field, no firm generalizations about the petrographic composition Limited petrographic analyses of of coals in this field are possible coal beds from the Hanna Coal Field at this time.

31 Macroscopically, the Cretaceous the f orm of honey-yellow, ambe r ­ and Tertiary coals of the Hanna like spheres and globules up to ~" Coal Field are banded varieties with in diameter also occur disseminated thin bands and/or thick lenses of in the coal or concentrated in vitrain in a bright to dull at­ bands that may or may not coincide tritus. Most of the thicker vitrain with bedding planes within the bed. lenses are obviously logs now par­ Joints or other fractures in the tially compressed and coalified and coal are often cemented or filled still exhibiting annular rings and with gypsum or calcite. The only cellular structure. Fusain lenses observable pyrite in any of the and bands are also commonly visible, Hanna Formation coals occurs as but seldom make up any appreciable very thin films on joint surfaces. portion of the beds. Resinite in

MINING ACTIVITY

Of approximately 189.6 million opment Company, Medicine Bow Coal tons of coal mined or lost as a re­ Company, Resource Exploration and sult of mining in the Hanna Coal Mining, Inc., and Rosebud Coal Sales Field prior to January 1, 1979, at Company. These companies are de­ least 79.7 million tons were de­ pleting coal reserves at the rate pleted by strip mining (this includes of 15 million tons per year (in­ an estimated 15.5 million tons cludes 20 percent mining losses lost during mining). Another 109.9 for strip mining and mining losses million tons were removed or lost equal to production for deep mining). by underground mining. Ninety-eight percent of this cur­ rent production, however, is from Currently, six companies are strip mines (Figure 22). Addition­ mining in the Hanna Coal Field: ally, the U.S. Department of Energy's Arch Mineral Corporation, Carbon Laramie Energy Technology Center County Coal Company, Energy Devel- is operating an experimental in situ

Figure 22. Arch Min­ erals' Semi.noe No. 1 strip mine in the Fer­ ris Formation.

32 R 86 W R 85 W R 84 W R 83 W R 82 W

Kmv

T 24 N

~ ...... Km b '-,-

Th T SEMINOE N0.2 NOii STRIP MINE '- 23 N SEMINOE NO. ':<;;'°:;t~=:;:=:;:::;:;::o STRIP MINI J'1J~a~~,~~-,;.,;;J SEM INOE NO. 2 SOUTH"-'\ ""' STRIP MINE ' '

T 22 N

T 2 1 N Tnp

To Rowlln1

T OE3:=:::e;;;;;;;c=iE;;!l[::======:::il0 MIL.ES 20 SCAL.E N

COMPILED FROM: DOBBIN AND OTHERS (1929) LOVE ANO OTHERS [19!1!1) BAYL.EY ( 1968) MEREWETHER (1971), (1912), (1973) LOWRY ANO OTHER ( 1973) GLASS AND ROBERTS (1979) 33 HYDEN ANO MCANDREWS (1967) coal gasification project just south went to depths in excess of 1 , 500 of Hanna (Figure 23). feet, more recent deep mining has seldom exceeded depths of 400 feet Edison Development, Arch Mineral, (Figure 24). Some of the proposed and Rocky Mountain Energy companies or active coal mines, however, may have proposed additional mines in go deeper in the future. Strip the field. Even with the opening of mining, on the other hand, has gone some new mines, annual production as deep as 250 feet after a 30 feet is not expected to exceed 17 million thick coal although the average tons per year by 1985. Coupled highwall is probably closer to 120 with mining losses, the annual de­ feet high. A highwall 300 feet pletion of coal reserves might high has already been proposed approach 20 million tons by that where a coal exceeds SO feet in same year (Table 5). thickness. Current mining ratios for strip mines in the Hanna Coal Although the older, now aban­ Field, which have been as high as doned, underground coal mines of 28:1, average less than 15:1. the early 1900's through the 19SO's

COAL RESOURCES AND RESERVE BASE

Dobbin, Bowen, and Hoots (1929) by coal thickness or reliability. were the first to report detailed In particular, they made no attempt information on the coal resources to break their estimates down any of the Hanna Coal Field. They further than 3,000 feet of cover. estimated that the field contained 4.2 billion tons of coal at depths Twenty-two years later, Berry­ up to 3,000 feet and that perhaps hill and others (1950) reexamined another 4 billion tons occurred at the coal resources of the Hanna greater depths. Their estimates, Coal Field, relying heavily on however, provided no breakdown the earlier report by Dobbin, Bowen,

Figure 24. Mine subsidence often pro­ vides stark evidence of underground mining (aban­ doned Hanna No. 3 mine area in Big Ditch).

34 Figure 2 3 . EXPLANATION

TERTIARY CRETACEOUS

QUATERNARY NORTH PARK DEPOSITS FORMATION B MEDICINE BOW FORMATION

WAGON BED AND WHITE LEWIS SHALE (INCLUDES FOX RIVER FORMATIONS HILLS SANDSTONE) R 81 W b a lwr HANNA FORMATION MESAVERDE GROUP

FERRIS FORMATION STEELE SHALE (OLDEST ROCKS (BASAL PORTION IS WITHIN THE COAL FIELD BUT CRETACEOUS) BARREN OF COAL)

*Tu TERTIARY UNDIVIDED FAULT ------······· ·· (DASHED WHERE APPROXIMATELY LOCATED ANO DOTTED WHERE CONCEALED)

COAL OUTCROP MORE THAN 5 FEET THICK - -•••• --···-·· •• (DASHED WHERE APPROXIMATELY LOCATED)

STRI PPA BLE COAL DEPOSITS FROM GLASS ANO R09ERTS ( 1979)

R 78 W R 77 W

To Mtdlcl"t Bow

,,.- .,,, Km1/ / -/ ) -" / I ~ mv {,/'

T 19 N Figure 23. Strippable coal deposits and mining activity in the Hanna Coal Field. Table 5. Current and proposed coal mining activities in the Hanna Coal Field.

CO>IPANY NAME MINE NAME M.IKE MllllNG DISTRICT PRODUCT IO,_ OESIG.~ ESTIMATED 1985 ~USED COAL BEDS 1 2 2 7 TYPE 1978, • CAPACITY PRODUCTIOS •

l\rch Mineral Corp. Seminoe No. l Strip Scminoe 2.50 3.0 3.0 65, 64•. 53", 52' 51, 50* 37, 35·, 34, 33, 31, 30, 28 , 26, 25, Dana•

Arch Minenl Corp. Seminoe No. 2 Strip Hanna 2.83 3.0 3.0 83*, 82* , so• , 79, Hanna No . 2, 76, 75, 74, Hanna No. s. 72•

•\rch ~linera l Corp. Hanna South Strip Hanna Proposed 0.8 0.8 Hanna No. t•, So•, 79?', 78*' 77•

Carbon County Coal Co. Carbon Count y Deep Hanna Opened 1979 l.S 0.8 82*, SO•, 79•, Hanna No. 2•

Department of Energy, Hanna In Situ Hanna llanna No. l Laramie Energy Gasification Technology Center Project VI c.n Edison Development Co. Carbon Basin Strip and Carbon Proposed 5.0 2.0 Finch•, Johnson Rider•, Deep Johnson•

Energy Development Co. Vanguard No. 2 Deep Se111inoe 0 .41 1.0 0.5 50

Medicine Bow Coal Co. Medicine Bow Suip Seminoe 3.13 3.0 3.0 65, 64, 63, 62, 61, 60, c•, F", 129•, 127" , 124•, 51•, 123*, 122*, 46", 44", 34*, 33*. 31•, 25* Resource Exploration Section 24 Pit Strip Seminoe 0 . 80 o. 70 0.7 Hanna No . 5, ?SO* and Mining, Inc.

Rocky Mountain Energy Corral Canyon Strip Corral Creek Proposed ?O.S o.s ?(11116*, WH4*, WH3*, Co. WH2*, WHl*)

Rosebud Coal Sales Rosebud Pit Strip Hanna 2. 92 2.5 2.5 83*, 82, 80, 79 Co. Nos. 4, 5, 6, 7, 8, 9

TCYrALS 12.59 ~ 16.8

2 Preliminary figures from the Wyoming State Inspector of Mines Millions of tons Coals that will be mined

0 and Hoots (1929). In this case, Int:erior study near Seminoe Reservoir however, they tabulate original re­ in the Seminoe Mining District sources on the bases of coal thick­ identified 41.21 million tons of ness, various depths of cover up "strippable resources" irt a 9.6 to 3,000 feet, and various reliabi­ square mile area (Bureau of Land lity categories. Their grand total Management, 1975). All these re­ was 3,9 billion tons or slightly sources were between O and 200 [eet less than the earlier estimate. of cover. The report did not identify the individual coal beds With the growing dominance of or the number of coal beds in- strip mining, the demand for esti­ cluded in the study, but they were mates of shallow (0-200 feet) re­ all Ferris Formation c oals. For sources grew. In 1971, the U.S. comparison, Glass and Roberts (1979) Bureau of Mines made the first es­ show 173.0l million tons of strip­ timate of "strippable coal reserves" pable resources underlying the in the Hanna Coal Field (U.S. :.ownsJ-.ips included in the Department Bureau of Mines, 1971). From a of Interior study. It must be re­ study of eight coal beds of the membered, however, that the earlier Hanna Formation, they identified 10 estimate only applied to a 9.6 million tons of stripvable resources. square mile portion of the four Applying an BO percent recovery townships. factor, they reported that eight million tons of that resource were A series of U.S. Geological strippable reserves. Tl•e estimate Survey open-file reports, prepared was so conservative l hat it provided by Texas Instruments, might have no insight into the total strippable provided the most 1~cent estimates coal resources of the field. of coal resources in the Hanna Coal F'ield, but contract require­ Glass (1972b) made a second ap­ ments forbade calculation of any proximation of the strjppable coal resources or reserves for any lands resources of 1_he coal field. That o~her than unleased Federal mineral estimate, however, was derived from lands (Texas Instruments, 1978 a-u). a simple manipulation of the earlier Because of this stipulation, and resource figures provided by Berry­ numerous other stipulations, the hill and others (1950). Glass (1972b) resource and reserve estin~tes in estimated that strippable resources these open-file reports provide were equal to two-tenths of the ljttle insight into the total coal remaining original resources for resources of the Hanna Coal Field. bituminous coals over 42 inches thick and uutler Jess Lhau 1,000 feet Glass and Roberts (l979) pro­ of cover plus two-tenths of the vide the most recent and most corn­ resources for subbituminous coals prehensive coal resource estimate over five feet thick and under less for the Hanna Coal Field, but than 1,000 of cover. This crude they on1y estimated strippable re­ approximation suggesled Lhat Lhere sources and reserve base As of were 312.98 million tons of strip­ January 1, 1978, they estimated pable resources in the Hanna Coal that 674.31 million tons of strip­ Field. Since resource reliability pable coal resources remained in categories were ignored, Glass' the Hanna Coal Field in southcentral (1972b) estimate was at best a Wyoming (Table 6). Of these strippable coal resource rather than strippable resources, 46 percent or strippable reserve base. 309.97 million tons lie between 0 and 100 feet of cover while the other In 1975, a U.S . Department of 54 percent or 364.34 million tons

36 Table 6. Remaining strippable coal resources and strippable reserve base of the Hanna Coa.l Field by mining

district 1 January 1 1 1978 (all figures in millions of tons).

MEASURED INDICATED TOTAL INFERRED RESERVE BASE RESERVE BASE RESERVE BASE RESOURCES GRAND TOTAL Overburden Overburden Overburden Overburden Overburden MINING thickness thickness thickness thickness thickness (feet): (feet) : (feet): (feet): (feet): DISTRICT 0-100 0-100 0-100 0-100 0- 100 100-200 100-200 100- 200 100-200 100-200 0-200 0- 200 0-200 0- 200 0-200

CARBON MINING DISTRICT 29.05 13 . 60 42.65 0. 35 43.00 20.53 55.68 76.21 2.34 78.55 1 (11 . 14 feet) 49.58 69.28 118. 86 2.69 121 . 55

HANNA MINING DISTRICT 86.18 43.87 130.05 2.44 132.49 85.67 58 . 16 143.83 2.36 146.19 t;I 1 -.J (14.22 feet) 171. 85 102. 03 273.88 4.80 278 . 68

SEMINOE MINING DISTRICT 76.15 38 . 25 114 .40 10.06 124.46 64.94 59.13 124.07 8.47 132.54 1 (9. 79 feet) 141.09 97.38 238.47 18 .53 257.00

CORRAL CREEK MINING 7.44 2.58 10.02 - - 10.02 DISTRICT l 4.51 2.55 7.06 -- 7.06 (5. 9 feet) 11. 95 5.13 17.08 -- 17.08

GRAND TOTAL FOR ALL 198.82 98.30 297.12 12.85 309.97 MINING DISTRICTS 175.65 175.52 351.17 13.17 364 . 34 (11. 77 feet) 1 374.47 273.82 648.29 26.02 674.31

1 (Weighted average thickness of coal) lie between 100 and 200 feet of cover. criteria that vary from mining Table 6 shows that most of these company to mining company. remaining s trippable coal r esource s (79%) occur in the Hanna and Se.mince Gl ass and Roberts (1979) also mining districts. These strippable point out that a portion of the resources include 26.02 million tons inferred strippable resources of coal in an inferred category will also become part of the reserve of reliability, which is usually base as drilling and mapping sub­ not considered part of the strippa­ stantiate its existence. Again, ble reserve base (U.S. Bureau of the percentage of the inferred Mines and U. S. Geological Survey, resources that will ultimately 1976) . become strippable reserve base is speculative at this time. For this reason, the remaining strippable reserve base or that part It is also noteworthy that of the strippable resources from although the four mining districts wh ich strippable reserves are derived in Fi9ure 2 contain all the known is reduced to 648.29 million tons strippable coal resources of the (96 percent of the strippable Hanna Coal Field that dip at 25 resources). Forty-six percent or degrees or less, they also contain 297.12 million tons of the reserve some c oals that dip more steeply. base occur under less than 100 Coals outside the four mining di s­ feet of cover while the remaining t r icts are either too thin to mine 351.17 million tons occur under or dip more than 25 degrees. thicker cover (100- 200 feet thick). Choate and Lent (1977) esti­ Although strippable reserves mate that the steeply dipping coal s per se (recoverable reserves) were of the Hanna Coal Field account not estimated, a fair app roximation for 240 million tons of coal. Their is that strippable rese rves equal steeply dipping resource includes at least BO percent of the reserve coal s between 5 and 30 feet thick base between 0 and 100 feet deep or with dips in excess of 20 degrees. 237.7 million tons. Although some This estimate, however, is nothing percentage of the reserve base be­ but an approximation derived from tween 100 and 200 feet deep is also the resource estimates of Berryhil l recoverable, the percentage is and others (1950). The estimate harder to e s timata. Applying i s apparently no more than a per­ the same rule of thumb that strip­ centage of the total coal resources pable reserves may equal 30 percent weighted to the areal extent of of that tonnage as well, another s teeply dipping coals ln the coal 280.94 million tons of reserves are field, Choate and Lent (1977) identified for a total of 518.64 also provide no depth cutoff for million tons of strippable reserves their estimated resource. in the Hanna Coal Field. Significant undergrowid coal A more conservative appraisal resources also underlie all four of strippable reserves in the 100- mining districts as well as some 200 feet depth range is hal f the other areas of the coal field. As reserve base or 175.59 million of January l, 1979, the remaining tons, thus reducing the remaining underground reserve base for the reserves to 413.29 million tons. Hanna Coal Field conservatively Unfortunately, accurate estimation approximates 768 million tons. This of strippable reserves is highly estimate was derived from Berryhill subjective since it is based on and others (1950) using the fol low-

38 ing procedure. The identified coal simplistic approach only provides resources under less than 1,000 a rough approximation of the under­ feet of cover were calculated by ground reserve base. adding Berryhill and others' (1950) estimates of the measured and in­ Because this estimated under­ dicated bituminous coal resources ground reserve base, which only re­ for coals greater than 42 inches fers to coals between 200 and 1,000 thick to the measured and indicated feet deep, is not much larger than resources for subbituminous coals the remaining strippable reserve greater than 5 feet thick in the base of 633.67 million tons, which 0-1,000 feet of cover category. only includes coals less than 200 The cumulative production and mining feet deep, there is a very good losses for the Hanna Coal Field chance that the preceding estimate were then subtracted from this total of underground reserve base could to get the remaining reserve base easily be 3 to 4 times too small. between O and 1,000 feet of cover. Only a more conventional reserve From this, the remaining strippable estimation, however, will improve reserve base of Glass and Roberts on the earlier methodology or (1979) was subtracted, leaving a re­ prove that the previous estimate maining underground reserve base of was inaccurate. 768 million tons. Obviously, this

39 REFERENCES

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Averitt, Paul, 1975, coal resources Gill, J.R., Merewether, E.A., and of the United States, January 1, Cobban, W.A., 1970, Stratigraphy 1974: U.S . Geological Survey Bul­ and nomenclature of some Upper letin 1412, 13lp. Cretaceous and lower Tertiary rocks in southcentral Wyoming: Bayley, R.W., 1968, Geologic map U.S. Geological Survey Professional of the Bradley Peak quadrangle, Paper 667, 53p. Carbon County, Wyoming : U.S. Geological Survey Geologic Quad­ Glass, G.B., l972a, Geology and rangle Map GQ-773, l plate. mineral resources of the Philips­ burg 7~-minute quadrangle, Centre Berryhill, H.L., Jr., and others, and Clearfield counties, Pennsyl­ 1950, Coal resources of Wyoming: vania: Pennsylvania Geological U.S. Geological Survey Circular Survey Atlas 95a, 24lp. 81, 78p. , 1972b, Mining in the Blanchard, L.F., and Pike, T.J., 1977, -----Hanna Coal Field: Geological Lithologic and geophysical logs Survey of Wyoming Miscellaneous of holes drilled in the Sominoe Report, 45p. Dam SE and Pats Bottom quadrangles, Carbon County, Wyoming: U.S. Geo­ ,1975, Analyses and mea- logical Survey Open-file Report -----sured sections of 54 Wyoming coal 77-119, 40p. samples (collected in 1974) : Geological Survey of Wyoming Brooks, K.J., 1977, Petrology and Report of Investigations No. 11, depositional environments of the 219p. Hanna Formation in the Carbon Basin, Carbon County, Wyoming: M.S. , 1978, Coal analyses and Thesis, University of Wyoming, -----lithologic descriptions of five 105p, core holes drilled in the Carbon Basin of southcentral Wyoming: Bureau of Land Management, 1975, Geological Survey of Wyoming Hanna Basin study site: U.S. Report of Investigations No. 16, Department of Interior EMRIA 97p. Report No. 2-1975, l93p. ~-----' 1979, (abstract) Coal Choate, Raoul and Lent, Judy, 1977, deposition in the Tertiary rocks Steeply dipping coal beds suitable of the Hanna Basin, southcentral for in situ gasification: a re­ Wyoming: Ninth International source assessment, in Proceedings , Congress of Carboniferous Stratig­ 3rd Annual Underground Coal Con­ raphy and Geology, Abstracts version Symposium, June, 1977: of Papers, University of Illinois, u.s. Department of Energy CONF- Urbana, Illinois, p. 74. 770652, p. 399-411.

40 ~~~~~' and Roberts, J.T., 1979, , 1973, Geologic map of ~~~~~ Remaining strippable coal resources the Lone Haystack Mountain and strippable reserve base of quadrangle, Carbon County, Wyoming: the Hanna Coal Field in south- U.S. Geological Survey Geologic cen tral Wyoming: Geological Sur­ Quadrangle Map GQ-1064, 1 plate. vey of Wyoming Report of Inves­ tigations No. 17, 166p. Nickelsen, R.P., and Hough, V. D., 1967, Jointing in the Appalachian Hyden, H.J., and McAndrews, Harry, Plateau of Pennsylvania : Geo­ 1967, Geologic map of the TL logical Society of America Bul­ Ranch quadrangle, Carbon County, letin, v. 78, p . 609-630. Wyoming: U.S. Geological Survey Geologic Quadrangle Map GQ-637, Ryan, J.D., 1977, Late Cretaceous l plate. and early Tertiary provenance and sediment dispersal, Hanna Knight, S.H., 1951, The late Cre­ and Carbon basins, Carbon County, taceous-Tertiary history of the Wyoming: Geological Survey of northern portion of the Hanna Wyoming Preliminary Report No . Basin-Carbon County, Wyoming: 16, 17p. Wyoming Geological Association Guidebook, 6th Annual Field Con­ Texas Instruments, Inc., 1978a, ference, p. 45-53. Coal resource occurrence and coal development potential maps Lord, N.W., and others, 1913, Analyses of the Carbon quadrangle, Carbon of coals in the United States: County, Wyoming: U.S. Geologi­ U.S. Bureau of Mines Bulletin cal Survey Open-file Report 78- 22, Part I, Analyses, 32lp. 044, 29p.

Love, J.D., Weitz, J.L., and Hose, ~~~~~' l978b, Coal resource R.K., 1955, Geologic map of Wyoming: occurrence maps of the Coal U.S. Geological Survey Map, scale Bank Basin quadrangle, Carbon 1:500,000. County, Wyoming: U.S. Geologi­ cal Survey Open-file Report 78- Lowry, M.E . , Rucker, S.J., and Wahl, 063, 17p. K.L., 1973, Water resources of the Laramie, Shirley, Hanna basins , 1978c, Coal resource and adjacent areas, southeastern ----~~~occurrence and coal development Wyoming : U.S. Geological Survey potential maps of the Como Hydrologic Investigations Atlas East quadrangle, Carbon County, HA-471, 4 sheets. Wyoming: U.S. Geological Survey Open-file Report 78-049, Merewether, E.A., 1971, Geologic 27p. map of the Wild Horse Mountain quadrangle, Carbon County, , 1978d, Coal resource Wyoming : U.S. Geological Survey --~~~--occurrence and coal deve lopment Geologic Quadrangle Map GQ-887, potential maps of the Como 1 plate. West quadrangle , Carbon County, Wyoming: U.S. Geological survey , 1972, Geologic map of Open-file Report 78-047, 3lp. ~~~~~ the Seminoe Dam SW quadrangle, Carbon County, Wyoming: U.S. Geological Survey Geologic

Quadrangle Map GQ-1017 1 1 plate.

41 -~----' 197Be, Coal resource ______, l97Bm, Coal resource occurrence maps of the Dana occurrence and coal development quadrangle, Carbon County, Wyoming: potential maps of the Pats U.S. Geological Survey Open-file Bottom quadrangle, Carbon Report 78-052, 23p. county, Wyoming: u.s. Geological survey Open-file Report 78-046, , 1978£, Coal resource 36p. ------occurrence maps of the Diffi- culty quadrangle, Carbon County, ------' l978n, Coal resource Wyoming: U.S. Geological Survey occurrence maps of the Schneider Open-file Report 78-056, 19p. Ridge quadrangle, Carbon County, Wyoming: U.S. Geological Survey ----~' 1978g, Coal resource Open-file Report 78-059, 22p. occurrence and coal develop­ ment potential maps of the Elk ______, 19780, Coal r esource Mountain quadrangle, Carbon occurrence and coal development County, Wyoming: U.S. Geological potential maps of the Seminoe Survey Open-file Report 78-051, Darn SE quadrangle, Carbon 28p. County, Wyoming: U.S. Geological Survey Open-file Report 78-048, ------' 197Bh, Coal resource 28p. occurrence and coal development potential maps of the Elmo ~----' 1978p, Coal resource quadrangle, Carbon County, Wyoming: occurrence maps of the Seminoe U.S. Geological Survey Open-file Dam SW quadrangle, Carbon Report 78-045, 27p. County, Wyoming: U.S. Geological Survey Open-file Report 78-060, , 1978i, Coal resource 20p. -----occurrence maps of the Ferris Lake quadrangle, Carbon County, ______, 1978q, Coal resource Wyoming: U.S. Geological Survey occurrence and coal development Open-file Report 78-057, 19p. potential maps of the TE Ranch quadrangle, Carbon County,

1 1978j, coal resource Wyoming: U. S. Geological Survey -----occurrence and coal development Open-file Report 78-055, 29p. potential maps of the Halfway Hill quadrangle, Carbon County, -~~~~' 1978r, Coal resource Wyoming: U.S. Geological survey occurrence and coal development Open-file Report 78-043, 3lp. potential maps of the Tenrnile Springs quadrangle, Carbon , 1978k, Coal resource County, Wyoming: U.S. Geological -----occurrence and coal development Survey Open-file Report 78-050, potential maps of the Hanna 22p. quadrangle, Carbon County, Wyoming: U.S. Geological Survey ~---- ' l978s, Coal resource Open-file Report 78-054, 26p. occurrence and coal development potential maps of the TL Ranch , 19781, Coal resource quadrangle, carbon county, -----occurrence maps of the Lone Hay- Wyoming: U.S. Geological survey stack Mountain quadrangle, Open-file Report 78-053, 23p. Carbon County, Wyoming: U.S . Geological Survey Open-file Report 78-062, 19p.

42 , 1978t, Coal £esource ~~~~~- occurrence maps of the Walcott quadrangle, carbon county, Wyoming: U.S. Geological Survey Open-file Report 78-058, 2lp.

~~~~~-' 1978u, Coal resource occurrence maps of the Wild Horse MOuntain quadrangle, Carbon County, Wyoming: U.S. Geological Survey Open-file Report 78-061, 20p.

U.S. Bureau of Mines, 1931, Analyses of Wyoming coals: U.S. Bureau of Mines Technical Paper 484, 159p.

, 1971, Strippable reserves ~~~~~ of bituminous coal and lignite in the United States: U.S. Bureau of Mines Information Circular IC 8531, 148p.

, and U.S. Geological ~~~~~ Survey, 1976, Coal resource classification systems of the U.S. Bureau of Mines and U.S. Geological Survey: U.S. Geologi­ cal Survey Bulletin 1450-B, 7p.

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