Chapter HF

FRAMEWORK GEOLOGY OF FERRIS AND HANNA

COAL IN THE HANNA AND CARBON BASINS

By R.M. Flores,1 V.V. Cavaroc, Jr.,2 and L.R. Bader1

in U.S. Geological Survey Professional Paper 1625-A

1

U.S. Geological Survey

2

North Carolina State University, Raleigh, North Carolina
HF-ii

Contents

Structural Setting..................................................................................................................HF-1

Stratigraphic Setting............................................................................................................HF-2

Depositional Setting............................................................................................................HF-2

Coal Quality..........................................................................................................................HF-3

Stratigraphy and Depositional Environments oc Coal-Assessment Units.............HF-3

Stratigraphy.....................................................................................................................HF-3

Depositional Environments.........................................................................................HF-4

Distribution of Ferris and Hanna Coal Beds and Zones in the Ferris, Hanna,

and South Carbon Coalfields............................................................................................HF-5

Stratigraphic Framework ...................................................................................................HF-6

Ferris 23-25 Coal Beds: Structural Cross Section A-A’...............................HF-7

Ferris 65 Coal Bed: Structural Cross Section B-B’........................................HF-8

Ferris 48-50 Coal Beds: Structural Cross Section C-C’................................HF-9

Hanna 77-78 Coal Beds: Structural Cross Section D-D’..........................HF-10

Hanna 81 Coal Bed: Structural Cross Section E-E’....................................HF-10

Hanna 78, 79, and 81 Coal Beds: Structural Cross Section F-F’.............HF-11

Hanna 78-79 Coal Beds: Structural Cross Section G-G’...........................HF-12

Hanna 78-81 Coal Beds: Structural Cross Section H-H’...........................HF-13

Johnson-107 coal zone: Structural Cross Section I-I’.................................HF-13

Johnson-107 coal zone: Structural Cross Section J-J’................................HF-14

References..........................................................................................................................HF-16
HF-iii

Figures

HF-1. Location map showing coalfields in the Hanna and Carbon 

Basins.

HF-2. Composite stratigraphic section for the assessment region showing the

studied coal beds and zones with age relationships based on palynology.

HF-3. Composite correlation of Paleocene sections based on palynostratigraphy.

HF-4. Braided, meandering, and anastomosed channels of the Tanana River in

Alaska.

HF-5. Sandstone interbedded with siltstone, mudstone, and coal in the Medicine

Bow mine.

HF-6. Siltstone and mudstone interbedded with minor sandstone and coal in the

Medicine Bow mine.

HF-7. Coal (upper part of picture) with siltstone and mudstone partings in the

Medicine Bow mine. Note normal fault on the right side of the picture.

HF-8. Coal interbedded with sandstone, siltstone, and mudstone in a mine north

of the town of Hanna.

HF-9. Interbedded sandstone, siltstone, and mudstone on a mine highwall north of

the town of Hanna.

HF-10. Thick coal and carbonaceous shale interbedded with siltstone and

mudstone, which in turn, are overlain by sandstone in a mine north of the

town of Hanna.

HF-11. Coal and carbonaceous shale interbedded with sandstone, siltstone, and

mudstone in an abandoned mine north of the town of Hanna.

HF-12. Location of the Ferris, Hanna, and South Carbon coalfields and cross

sections in the Hanna and Carbon Basins.

HF-13. Structural cross section A-A showing the Ferris 23-25 coal beds.
HF-iv

HF-14. Fluvial channels, floodplains, and swamps of the Columbia River in the

Province of British Columbia, Canada.

HF-15. Crevasse splay of the Saskatchewan River in the Province of

Saskatchewan, Canada.

HF-16. Structural cross section B-B’ showing the Ferris 65 coal bed.

HF-17. Fluvial channel of the Beluga River, Alaska.

HF-18. Fluvial channel and associated crevasse splay of the Saskatchewan River in

the Province of Saskatchewan, Canada.

HF-19. Structural cross section C-C’ showing the Ferris 48-50 coal beds.

HF-20. Structural cross section D-D’ showing the Hanna 77-78 coal beds.

HF-21. Structural cross section E-E’ showing the Hanna 81 coal bed.

HF-22. Structural cross section F-F’ showing the Hanna 78, 79, and 81 coal beds.

HF-23. Anastomosed fluvial channels and associated swamps of the Saskatchewan

River in the Province of Saskatchewan, Canada.

HF-24. Structural cross section G-G’ showing the Hanna 78-79 coal beds.

HF-25. Structural cross section H-H’ showing the Hanna 78-81 coal beds.

HF-26. Structural cross section I-I’ showing the Johnson-107 coal zone.

HF-27. Crevasse splays draining into floodplain lakes from anastomosed fluvial

channels of the Columbia River in the Province of British Columbia,

Canada.

HF-28. Structural cross section J-J’ showing the Johnson-107 coal zone.
HF-1

STRUCTURAL SETTING

• The Hanna and Carbon Basins are in Carbon County, south-central Wyoming

(fig. HF-1).

• The Hanna Basin is the deeper of these basins and contains more than 30,000 ft

of sedimentary rocks overlying crystalline basement (Knight, 1951).

• The Ferris and Hanna Formations (equivalent to the Fort Union Formation) are

present in the central part of the Hanna Basin. Exposed at the margins of the basin

are the Cretaceous Medicine Bow Formation, Fox Hills Sandstone, Lewis Shale,

and the undifferentiated Mesaverde Group, and lower Cretaceous formations (Love

and others, 1955; Lowry and others, 1973; Hansen, 1986)

• Ferris and Hanna rocks in the Hanna Basin occur over a 750 square mile area

and are about 13,500 feet thick.

• These rocks are tightly folded into synclines and anticlines and faulted into

normal and thrust faults particularly along the basin margins (Glass and Roberts,

1979). Unidentified Paleocene coal-bearing rocks steepen to vertical dips and

overturn on the northern flanks of the basin as the rocks approach a major thrust

fault that separates the basin from the Shirley Mountains to the north.

• Beds dip steeply, particularly along the northern flank of the Hanna Basin;

however, beds in the central part of the basin dip an average of 5-15 degrees.

• The Carbon Basin to the east-southeast is separated from the Hanna Basin to the

west by the large northeast-trending Saddleback Hills anticline (Ryan, 1977). The

two basins have a combined area of approximately 1,200 square mile.

• Ferris and Hanna rocks in the Carbon Basin are present over a 50 square-mile

area and are more than 9,600 ft in thickness.
HF-2

• Coal beds in the Carbon Basin are primarily in the Hanna Formation, which is as

much as 5,500 ft thick.

STRATIGRAPHIC SETTING

• The Ferris Formation is Late Cretaceous and early Paleocene in age, and the

Hanna Formation is middle to late Paleocene and early Eocene in age (fig. HF-2 and

fig. HS-3 in Chapter HS). These formations are conformable in the Hanna Basin

and unconformable in the Carbon Basin. More than 2,000 ft of rock is missing at

the contact of these formations in the Carbon Basin (Hansen, 1986). Biostratigraphic

zonations of the formations include Zones P1-P6 (fig. HF-3).

• Only the Paleocene parts of the Ferris and the Hanna Formations were studied

for this assessment. The Paleocene coal was about 0.5 percent of the total U.S. coal

production in 1997; it will continue to supply energy fuel during the next few

decades.

• The Ferris and Hanna Formations each may be divided into a sandstonedominated lower interval and coal-bearing middle and upper intervals.

• The lower sandstone-dominated interval ranges from 2,000-2,300 ft thick.

• Coal beds in the Ferris Formation are as much as 25 ft thick and in the Hanna

Formation are as much as 36 ft thick.

• Proprietary and non-proprietary data from 1,905 drill holes were used for the 

study of the Ferris and Hanna coal beds.

DEPOSITIONAL SETTING

• Depositional environments were primarily in fluvial systems such as braided,

meandering, and anastomosed streams (Hansen, 1986; Cavaroc and others, 1992;

Perry and Flores, 1994).
HF-3

• Minor depositional environments in the upper part of the Hanna Formation

represent lacustrine deltas and lake systems (Perry and Flores, 1994).

• Coal accumulated in peat swamps on fluvial floodplains, in abandoned fluvial

channels, and in lacustrine environments.

COAL QUALITY

• Coal rank is predominantly subbituminous with minor bituminous (Glass and

Roberts, 1979).

• Coal quality reflects low to intermediate sulfur and low to high ash contents

(Glass, 1978).

• Concentrations of selected trace-elements of environmental concern are low.

STRATIGRAPHY AND DEPOSITIONAL ENVIRONMENTS

OF COAL-ASSESSMENT UNITS

STRATIGRAPHY

• The Paleocene part of the Ferris Formation is more than 6,500 ft thick (see fig.

HS-3 in Chapter HS).

• The Ferris Formation is composed mainly of sandstone, siltstone, and mudstone

and subordinately of carbonaceous shale and coal beds.

• Assessment units include the Ferris 23, 25, 31, 50, and 65 (Dobbin and others,

1929) in the Hanna Basin.

• Coal beds 23, 25, and 31 are in the middle part of the Ferris Formation and coal

beds 50 and 65 are in the upper part of the formation.
HF-4

• The Paleocene part of the Hanna Formation is about 7,000 ft thick.

• The Hanna Formation consists primarily of sandstone, siltstone, and mudstone,

and subordinately of carbonaceous shale and coal beds.

• Sandstone makes up more than 50 percent of the Ferris and Hanna Formation.

Based on outcrop investigations, the sandstone beds exhibit an erosional base and

generally vary from 10 to 100 ft in thickness and were interpreted by Hansen (1986)

and Cavaroc and others (1992) as fluvial channel deposits. Some of these deposits

were interpreted by Ryan (1977) as braided stream deposits. Coarsening-upward

sandstone sequences as much as three ft thick were interpreted by Hansen (1986)

and Cavaroc and others (1992) as crevasse splay deposits. These characteristics

were used as a guide when interpreting the fluvial depositional environments (fig.

HF-4) in the subsurface.

• Assessment units include the Hanna 77, 78, 79, and 81 coal beds in the Hanna

Basin and the Johnson-107 coal zone (Dobbin and others, 1929) in the Carbon

Basin.

• These coal beds and zones (77-79, 81, and Johnson-107) are all in the middle to

upper part of the Hanna Formation.

DEPOSITIONAL ENVIRONMENTS

• Ferris and Hanna coal beds accumulated in peat swamps in fluvial environments

(Cavaroc and others, 1992). However, the Hanna coal beds were deposited

primarily in peat swamps of fluvial-floodplain lacustrine environments.

• As can be seen in mine highwalls, the Ferris coal beds are interbedded with

lenticular fluvial-channel sandstone bodies that grade laterally into floodplain, thinto thick-bedded, crevasse-splay, silty sandstone, siltstone, and mudstone (fig. HF5). The coal beds interbedded with floodplain-crevasse-splay and crevasse-channel
HF-5

deposits suggest accumulation in low-lying swamps (fig. HF-6). Coal formed in a

low-lying swamps contains detrital partings (see upper coal in fig. HF-7) indicating

influx of sediments from a nearby fluvial channel. The channel sandstone, which

overlies the coal with partings, indicates avulsion or shift of the fluvial channel into

the low-lying swamp.

• As can be seen in mine highwalls, the Hanna coal beds are interbedded with

fluvial-channel sandstone, crevasse-splay sandstone, and floodplain siltstone and

mudstone (fig. HF-8). The tabular crevasse-splay sandstone bodies grade laterally

into lens-shaped crevasse-channel sandstone (fig. HF-9). The coal is interbedded

with carbonaceous shale and mudstone, suggesting accumulation in a low-lying

swamp (fig. HF-10). Another indication of the low-lying nature of the swamp is the

presence of lenticular fluvial-channel sandstone beds between coal beds, which

merge as the sandstone pinches out (fig. HF-11).

• Fluvial environments developed in an eastward-flowing fluvial system that

included braided, meandering, and anastomosed streams (Ryan, 1977; Perry and

Flores, 1994).

DISTRIBUTION OF FERRIS AND HANNA COAL BEDS AND

ZONES IN THE FERRIS, HANNA, AND SOUTH CARBON

COALFIELDS

• The Ferris coalfield boundary (fig. HF-12) approximately follows the areal extent

of the Seminoe mining district defined by Glass and Roberts (1979; 1980) which

includes past and current mines that produced from the Ferris coal. The coalfield is

bounded on the west and south by the outcrop of the Ferris coal and Seminoe

Reservoir, on the north by the Medicine Bow River, and on the east by an arbitrary

line (5 mi from the outcrop line) based on the distribution of control points (see fig.

HS-1 in Chapter HS).
HF-6

• The Hanna coalfield boundary (fig. HF-12) approximately follows the areal

extent of the Hanna mining district as defined by Glass and Roberts (1979; 1980),

which includes past and current mines that produced from the Hanna coal. The

coalfield is bounded on the west, east, and south by the outcrop of the Hanna coal

and on the north by the Medicine Bow River.

• The South Carbon coalfield boundary (fig. HF-12) approximately follows the

southern area of the Carbon mining district as defined by Glass and Roberts (1979;

1980), which includes past and current mines that produced from the Hanna coal.

The coalfield is bounded on the west, east, and south by the outcrop of the Hanna

coal and on the north by the northern extent of the Johnson-107 coal zone, which is

targeted for leasing (U.S. Bureau of Land Management, 1998).

• More than 60 Ferris coal beds are vertically distributed as closely spaced units

separated by mudstone and thin sandstone beds in the Hanna Basin.

• More than 20 Hanna coal beds are distributed as widely spaced units separated

by thin to thick sandstone beds and minor mudstone interbeds in the Carbon Basin.

• Most coal beds are in the subsurface of Carbon County and there is indication

that the more persistent coal beds may thicken in the central areas of the Hanna and

Carbon Basins (Glass and Roberts, 1980).

• Surface occurrences and minable deposits of the Ferris coal are in the western

and southwestern parts of the Ferris coalfield.

• Most surface occurrences and minable deposits of the Hanna coal are in the

eastern part of the Hanna coalfield and the southern part of the South Carbon

coalfield.

STRATIGRAPHIC FRAMEWORK

• Ferris coal beds are interbedded with mudstone, carbonaceous shale, siltstone,

and sandstone.
HF-7

• Ferris coal beds 23 and 25 are within a 350-ft-thick interval, beds 31-39 are

within a 400-ft-thick interval, and beds 50 and 65 are within a 1,500-ft-thick interval.

Hanna coal beds 77-9 and 81 are within a 700-ft-thick interval, and the Johnson-107

coal zone is within a 200-ft-thick interval.

• Laterally these coal beds merge, split, and pinch out.

• Split coal beds are interbedded with mudstone, siltstone, and sandstone. Most

split into two or more beds, gradually thin or pinch out or interfinger with other

clastic rocks.

• Merged coal beds are interbedded with carbonaceous shale partings. Merging of

two or more beds results in a single, thicker bed. Intervening clastic rocks thin or

pinch out or interfinger with coal and carbonaceous shale.

• Rocks above and below the Ferris and Hanna coal beds consist of mudstone,

siltstone, and sandstone. Sandstone is the most common rock type; it has a salt and

pepper appearance that results from a mixture of quartz and rock fragments (Ryan,

1977).

• The sediments forming these rocks accumulated in channels and floodplains in a

fluvial system (Cavaroc and others, 1992).

• The coal beds accumulated in peat swamps formed in distal floodplains, at the

margins of floodplain lakes, and on abandoned fluvial-channel deposits.

FERRIS 23-25 COAL BEDS: STRUCTURAL CROSS SECTION A-A’

• This structural cross section (fig. HF-13) shows the Ferris 23, 24, and 25 coal

beds. These beds dip to the southeast. The cross section was drawn using data from

6 drill holes, which are not labeled on the cross section.

• The Ferris 23 coal bed is as much as 5 ft thick, the Ferris 24 coal bed is more

than 20 ft thick, and the Ferris 25 coal bed is as much as 17 ft thick.
HF-8

• The Ferris 23, 24, and 25 coal beds split locally; they thicken to the northwest

where they merge into an interval as much as 48 ft thick.

• The Ferris 23-25 coal-bed interval to the southeast is as much as 75 ft thick.

• Interburden rocks between the thick Ferris 23, 24, and 25 coal beds and partings

within these coal beds are dominated by mudstone (shown in green) with minor

sandstone (shown in yellow).

• The Ferris 23, 24, and 25 coal beds and interburden or partings accumulated in

peat swamps (fig. HF-14) that were intermittently overtopped by floodplain mud

and crevasse-splay sand (fig. HF-15).

• Overburden rocks above the Ferris 25 coal bed consist mainly of mudstone

(green), with subordinate sandstone (yellow) interbedded with minor coal beds

more than 5 ft thick.

• The overburden rocks are interpreted to have formed in fluvial channels

(sandstone) or on a floodplain (mudstone); the associated coal beds accumulated in

peat swamps.

FERRIS 65 COAL BED: STRUCTURAL CROSS SECTION B-B’

• This structural cross section (fig. HF-16) shows the Ferris 65 and associated coal

beds, which dip to the northeast. The cross section was drawn using data from 7

drill holes, which are not labeled on the cross section.

• The Ferris 65 coal bed is more than 7 ft thick and the associated coal beds vary

from 2 to 8 ft thick.

• The Ferris 65 coal bed is locally split but maintains a uniform thickness

throughout most of the 0.20-mi lateral extent of the cross section.

• Rock partings are composed mainly of mudstone (shown in green).

• The Ferris 65 coal bed and rock partings accumulated in peat swamps that were

intermittently overrun by floodplain mud.
HF-9

• The Ferris 65 coal bed is overlain by thick sandstone bodies (shown in yellow)

that were deposited in large fluvial channels (fig. HF-17).

• Rocks above and below the Ferris 65 coal bed consist mainly of mudstone

(green) and subordinate sandstone (yellow) interbedded with minor coal beds more

than 2 ft thick.

• The rocks above and below the Ferris 65 coal bed are interpreted to have formed

in small crevasse channels (sandstone) (fig. HF-18) or on a floodplain (mudstone);

the associated coal beds accumulated in peat swamps.

FERRIS 48-50 COAL BEDS: STRUCTURAL CROSS SECTION C-C’

• This structural cross section (fig. HF-19) shows the folded Ferris 50 coal bed

and associated Ferris 48 and 49 coal beds. The cross section was drawn using data

from 6 drill holes, which are not labeled on the cross section.

• The Ferris 50 coal bed is as much as 15 ft thick; the associated Ferris 48 and 49

coal beds vary in thickness from 2 to 14 ft.

• The Ferris 50 coal bed is locally split by partings composed of mudstone (shown

in green).

• The Ferris 50 coal bed and partings accumulated in peat swamps that were

intermittently overrun by floodplain mud.

• The Ferris 50 coal bed is overlain by rocks composed of vertically stacked, thick

sandstone bodies (shown in yellow) that were deposited in large, deep fluvial

channels.

• Rocks below the Ferris 50 coal bed consist of mudstone (green) with subordinate

sandstone (yellow) interbedded with minor coal beds (Ferris 48 and 49) that are less

than 2 ft thick.
HF-10

• Rocks below these coal beds are interpreted to have formed in small fluvial

channels (sandstone) or on a floodplain (mudstone); the associated coal beds formed

in peat swamps.

HANNA 77-78 COAL BEDS: STRUCTURAL CROSS SECTION D-D’

• This structural cross section (fig. HF-20) shows the Hanna 77 and 78 coal beds

and associated rocks dipping to the northeast. The cross section was drawn using

data from 4 drill holes, which are not labeled on the cross section.

• The Hanna 77 coal bed is as much as 20 ft thick and the Hanna 78 coal bed is as

much as 22 ft thick.

• The Hanna 77 and 78 coal beds are locally split by sandstone partings (shown in

yellow) and mudstone partings (shown in green).

• The Hanna 77 and 78 coal beds and partings accumulated in peat swamps that

were locally overtopped by floodplain mud and crevasses-splay sand.

• Interburden rocks between the Hanna 77 and 78 coal beds consist of four thin to

thick sandstone bodies (yellow) that were deposited in fluvial channels. This

indicates reoccupation of the channels several times.

• The fluvial channel sandstone bodies are interbedded with mudstone (green) that

was deposited in floodplain and overbank environments.

HANNA 81 COAL BED: STRUCTURAL CROSS SECTION E-E’

• This structural cross section (fig. HF-21) through the Hanna 81 coal bed shows

rocks dipping to the northeast. The cross section was drawn using data from 8 drill

holes, which are not labeled on the cross section.
HF-11

• The Hanna 81 coal bed is as much as 18 ft thick and is locally split by mudstone

partings (shown in green).

• The Hanna 81 coal bed and partings accumulated in peat swamps that were

locally overrun by floodplain mud.

• The overburden rocks above the Hanna 81 coal bed consist of numerous thin to

thick, laterally offset sandstone bodies (shown in yellow) that were deposited in

fluvial channels that were reoccupied at least three times.

• The fluvial-channel sandstone bodies are interbedded with mudstone (green) that

accumulated in floodplain and overbank environments.

HANNA 78, 79, AND 81 COAL BEDS: STRUCTURAL CROSS

SECTION F-F’

• This structural cross section (fig. HF-22) across the basin axis (low spot of the

cross section) shows steeply dipping rocks to the southeast and more gently dipping

rocks to the northwest. (Dips are greatly exaggerated due to compressed horizontal

scale.) Rocks include the Hanna 78, 79, and 81 coal beds and associated sandstone

and mudstone. The cross section was drawn using data from 12 drill holes, which

are not labeled on the cross section.

• The Hanna 78 coal bed is as much as 35 ft thick, and the Hanna 79 and 81 coal

beds vary from 2 to 10 ft in thickness.

• The Hanna 79 and 81 coal beds are thin and laterally uniform in thickness

throughout the cross section. The Hanna 79 coal bed is locally split by mudstone

partings (shown in green) toward the northwest; it thins to the southeast.

• The Hanna 78, 79, and 81 coal beds and partings accumulated in peat swamps

that were intermittently overtopped by floodplain mud.
HF-12

• The interburden rocks between Hanna 78, 79, and 81 coal beds consist of

stacked, thick and thin sandstone beds (shown in yellow). The thick sandstone beds

were deposited in large, deep fluvial channels, and the thin sandstone beds were

deposited in small, shallow fluvial channels (fig. HF-23).

• The fluvial channel sandstone bodies are interbedded with mudstone (green)

deposited in floodplain and overbank environments.

• The basin axis contains vertically stacked, thick fluvial-channel sandstone bodies

(yellow), indicating that it served as a depositional axis of the fluvial system.

HANNA 78-79 COAL BEDS: STRUCTURAL CROSS SECTION G-G’

• This structural cross section (fig. HF-24) shows the Hanna 78 and 79 coal beds

and associated rocks dipping to the southeast and northwest. The cross section was

drawn using data from 6 drill holes, which are not labeled on the cross section.

• The Hanna 78 coal bed is as much as 14 ft thick and the Hanna 79 coal bed is as

much as 10 ft thick.

• The Hanna 78 coal bed is laterally uniform in thickness throughout the cross

section but is locally split toward the northwest by a mudstone parting (shown in

green).

• The Hanna 78 and 79 coal beds and partings accumulated in peat swamps that

were locally overtopped by floodplain mud.

• The interburden rocks between the Hanna 78 and 79 coal beds consist of stacked,

thick and thin sandstone bodies (shown in yellow). The thick sandstone beds were

deposited in large, deep fluvial channels, and the thin sandstone beds were deposited

in small, shallow fluvial channels.

• The fluvial-channel sandstone bodies are interbedded with mudstone (green) that

accumulated in floodplain and overbank environments.
HF-13

HANNA 78-81 COAL BEDS: STRUCTURAL CROSS SECTION H-H’

• This structural cross section (fig. HF-25) shows the Hanna 78-81 coal beds,

which generally dip to the northwest. The cross section was drawn using data from

5 drill holes, which are not labeled on the cross section.

• The Hanna 78 coal bed is as much as 15 ft thick, the Hanna 79 coal bed is as

much as 22 ft thick, and the Hanna 81 coal bed is as much as 10 ft thick.

• The Hanna 78 and 81 coal beds are laterally uniform in thickness throughout the

cross section, and the Hanna 79 coal is locally split toward the northwest by

mudstone partings (shown in green).

• The Hanna 78, 79, and 81 coal beds and partings accumulated in peat swamps

that were intermittently overtopped by floodplain mud.

• The interburden rocks between the Hanna 78, 79, and 81 coal beds consist of

stacked, thick and thin sandstone beds (shown in yellow). The thick sandstone beds

were deposited in large, deep fluvial channels, and the thin sandstone beds were

deposited in small, shallow fluvial channels.

• The fluvial channel sandstone beds (yellow) are interbedded with mudstone

(green) that was deposited in floodplain and overbank environments.

JOHNSON-107 COAL ZONE: STRUCTURAL CROSS SECTION I-I’

• This structural cross section (fig. HF-26) through the Johnson-107 coal zone

shows rocks dipping about ten degrees to the north and six degrees to the south.

The cross section was drawn using data from 12 drill holes, which are not labeled

on the cross section.
HF-14

• The Johnson coal bed is as much as 20 ft thick and is the lowermost bed in the

Johnson-107 coal zone. The Finch coal bed is as much as 20 ft thick and is above

the Johnson coal bed. The 107 coal bed is as much 15 ft thick and is above the

Finch coal bed and is the uppermost bed of the Johnson-107 coal zone (see cross

section J-J’ to see detail).

• The Johnson, Finch, and 107 coal beds are vertically closely spaced; however,

they are split by sandstone partings (shown in yellow) and mudstone partings

(shown in green).

• The Johnson coal bed and partings accumulated in peat swamps that were locally

overrun by floodplain mud and crevasse-splay sand (fig. HF-27).

• The overburden rocks above the Johnson-107 coal zone consist of numerous,

stacked, thin to thick, laterally offset sandstone bodies (yellow) that were deposited

in fluvial channels that were reoccupied several times.

• The fluvial-channel sandstone bodies are interbedded with mudstone (green) that

was deposited in floodplain and overbank environments.

JOHNSON-107 COAL ZONE: STRUCTURAL CROSS SECTION J-J’

• This structural cross section (fig. HF-28) through the Johnson-107 coal zone

shows rocks dipping to the west and to the east. The cross section was drawn using

data from 6 drill holes, which are not labeled on the cross section.

• The Johnson coal bed is as much as 25 ft thick and is locally split by sandstone

beds (shown in yellow).

• The Johnson coal bed and partings accumulated in peat swamps that were locally

overrun by floodplain mud (shown in green) and crevasse-splay sand (yellow).

• The Finch coal bed, which is the upper bed of the Finch-Johnson coal zone, is as

much as 20 ft thick to the west and thins to the east.
HF-15

• The Johnson and Finch coal beds, interburden rocks, and partings accumulated in

peat swamps that were locally overrun by floodplain mud and crevasse-splay sand.

• The overburden rocks above the Johnson-107 coal zone consist of numerous,

stacked, thin to thick, laterally offset sandstone bodies (yellow) that were deposited

in fluvial channels that were reoccupied several times.

• The fluvial channel sandstone bodies are interbedded with mudstone (green) that

accumulated in floodplain and overbank environments.

• The overburden rocks immediately above the Finch-Johnson coal zone include

thin to thick coal beds. The coal beds are as much as 25 ft thick, but laterally they

thin and pinch out into the laterally equivalent fluvial channel sandstone beds.
HF-16

REFERENCES

Cavaroc, V.V., Flores, R.M., Nichols, D.J., and Perry, W.J., 1992, Paleocene

tectono-facies relationships between the Hanna, Carbon, and Cooper Lake

basins, Wyoming [abs]: American Association of Petroleum Geologists

Bulletin, v. 76, p. 1257.

Dobbin, C.E., Bowen, C.F., and Hoots, H.W., 1929, Geology and coal and oil

resources of the Hanna and Carbon basins, Carbon County, Wyoming: U.S.

Geological Survey Bulletin 804, 88 p.

Glass, G.B., 1978, Coal analyses and lithologic descriptions of five core holes

drilled in the Carbon Basin of south-central Wyoming: Geological Survey of

Wyoming Report of Investigations No. 16, 97 p.

Glass, G.B., and Roberts, J.T., 1979, Remaining strippable coal resources and

strippable reserve base of the Hanna coal field in south-central Wyoming:

Geological Survey of Wyoming Report of Investigations No. 17, 166 p.

_____1980, Coal and coal-bearing rocks of the Hanna coal field, Wyoming:

Geological Survey of Wyoming Report of Investigations No. 22, 41 p.

Hansen, D.E., 1986, Laramide tectonics and deposition of the Ferris and Hanna

Formations, south-central Wyoming, in Peterson, J.A., ed., Paleotectonics

and Sedimentation in the Rocky Mountain Region, United States: American

Association of Petroleum Geologists Memoir 41, p 481-495.

Knight, S.H., 1951, The Late Cretaceous-Tertiary history of the northern portion of

the Hanna Basin—Carbon County, Wyoming, in Wyoming Geological

Association Guidebook 6th Annual Field Conference, south-central

Wyoming: Wyoming Geological Association, p. 45-53.

Love, J.D., Weitz, J.L., and Hose, R.K., 1955, Geologic map of Wyoming: U.S.

Geological Survey, scale 1:500,000.
HF-17

Lowry, M.E., Rucker, S.J., Wahl, K.L., 1973, Water resources of the Laramie,

Shirley, and Hanna Basins and adjacent areas, southeastern Wyoming: U.S.

Geological Survey Hydrologic Investigations Atlas HA-471, 4 sheets.

Perry, W.J., Jr., and Flores, R.M., 1994, Sequential Laramide deformation and deep

gas-prone basins of the Rocky Mountain region, in Dyman, T.S., Rice, D.D.,

and Wescott, W.A., eds., Geologic Controls of Deep Natural Gas Resources

in the U.S.: U.S. Geological Survey Bulletin 2146-E, p. 49-59.

Ryan, J.D., 1977, Late Cretaceous and early Tertiary Provenance and sediment

dispersal, Hanna and Carbon Basins, Carbon County, Wyoming: Geological

Survey of Wyoming, Preliminary Report No. 16, 16 p.

U.S. Bureau of Land Management, and U.S. Office of Surface Mining, 1998,

Carbon Basin project environmental impact statement, Carbon County,

Wyoming: TRC Mariah Associates, Inc,. Laramie, Wyoming, MAI Project

20241-01, 261 p.
WYOMING

5 0 5 Miles

N

106°45' 106°30' 106°15'

42°00'

41°45'

Hanna Basin

Carbon

Basin

South Carbon

coalfield

Hanna

coalfield Ferris

coalfield

Medicine Bow River

Sem inoe Reservoir
Paleocene

late

(Zones

P5-P6)

middle

(Zones

P3-P4)

early

(Zones

P1-P2)

Wyodak-Anderson

Beulah-Zap 

Hagel 

Harmon

Hansen

Knobloch

Rosebud

Deadman Seams 1-5

}

}

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

......................................Williston Basin

...............................................Williston Basin

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

.........................................Williston Basin

....Greater Green River Basin

Hanna Nos. 77-79, 81

Ferris Nos. 23, 

25, 31, 50, & 65 }.............................Hanna Basin

.....................Hanna Basin

Johnson-107 ..................................Carbon Basin

Figure HF-2. Composite stratigraphic section for the assessment region showing the studied coal

beds and zones with age relationships based on palynology. Assessment units in the Hanna and

Carbon Basins are highlighted in red.
500 Meters

Greater

Green River

Basin

Hanna and

Carbon Basins Powder River

Basin

Williston

Basin

Zones: P1 P2 P3

P4 P5 P6

Figure HF-3. Composite correlation of Paleocene sections based on palynostratigraphy.
Figure HF-4. Braided, meandering, and anastomosed channels of the Tanana River in Alaska. 

Photograph by R.M. Flores.
Figure HF-5. Sandstone interbedded with siltstone, mudstone, and coal in the Medicine Bow mine. Photograph by 

R.M. Flores. 
Figure HF-6. Siltstone and mudstone interbedded with minor sandstone and 

coal in the Medicine Bow mine. Photograph by R.M. Flores.
Figure HF-7. Coal (upper part of picture) with siltstone and mudstone partings 

in the Medicine Bow mine. Note normal fault on the right side of the picture. 

Photograph by R.M. Flores.
Figure HF-8. Coal interbedded with sandstone, siltstone, and mudstone in a mine north of the town of Hanna. 

Photograph by R.M. Flores.
Figure HF-9. Interbedded sandstone, siltstone, and mudstone on a mine highwall north of the town of Hanna. 

Photograph by R.M. Flores.
Figure HF-10. Thick coal and carbonaceous shale interbedded with siltstone and mudstone, which in turn, are overlain 

by sandstone in a mine north of the town of Hanna. Photograph by R.M. Flores.
Figure HF-11. Coal and carbonaceous shale interbedded with sandstone, siltstone, and mudstone in an abandoned 

mine north of the town of Hanna. Photograph by R.M. Flores.
J

J'

I

I'

A

A'

B

B'

E

E'

G

G'

F

F'

C

C'

D

D'

H

H'

Basin

Carbon

Basin

Hanna

Ferris coalfield

Hanna coalfield

Cross section with nonproprietary

drill holes

Cross section with proprietary

drill holes

South Carbon coalfield

42°00'

41°45'

0 5 Miles

WYOMING

A A'

A A'

Figure HF-12. Location of the Ferris, Hanna, and South Carbon coalfields and cross

sections in the Hanna and Carbon Basins.

Medicine Bow River

Sem inoe Reservoir
Datum = Sea level

Coal

Sandstone

Mudstone

Ferris 23

Ferris 25

Ferris 24

)

Figure HF-13. Structural cross section A-A' showing the Ferris 23-25 coal beds.
Figure HF-14. Fluvial channels, floodplains, and swamps of the Columbia River in the Province of British 

Columbia, Canada. Photograph by D. Smith.
Figure HF-15. Crevasse splay of the Saskatchewan River in the Province of Saskatchewan, Canada. 

Photograph by N. Smith.
Datum = Sea level

Coal

Sandstone

Mudstone

?

?

}Ferris 65

Figure HF-16. Structural cross section B-B' showing the Ferris 65 coal bed.
Figure HF-17. Fluvial channel of the Beluga River, Alaska. Photograph by R.M. Flores.
Figure HF-18. Fluvial channel and associated crevasse splay of the Saskatchewan River in the Province of 

Saskatchewan, Canada. Photograph by N. Smith.
C C

atum = Sea level

Coal

Sandstone

Mudstone

Clinker

Ferris 50

erris 49

erris 48

Figure HF-19. Structural cross section C-C' showing the Ferris 48-50 coal beds.
atum = Sea level

Figure HF-20. Structural cross section D-D' showing the

Hanna 77-78 coal beds.

Coal

Sandstone

Mudstone

Hanna 78

Hanna 77
Datum = Sea level

Coal

Sandstone

Mudstone

Hanna 81

Figure HF-21. Structural cross section E-E' showing the

Hanna 81 coal bed.
Datum = Sea level

Coal

Sandstone

Mudstone

Clinker

Hanna 78

Hanna 81

Hanna 79

Hanna 78

Figure HF-22. Structural cross section F-F' showing the

Hanna 78, 79, and 81 coal beds.
Figure HF-23. Anastomosed fluvial channels and associated swamps of the Saskatchewan River in the Province of 

Saskatchewan, Canada. Photograph by N. Smith.
Datum = Sea level

Coal

Sandstone

Mudstone

Clinker

G G'

Hanna 78

Hanna 79

Figure HF-24. Structural cross section G-G' showing

the Hanna 78-79 coal beds.
Sea level

Coal

Sandstone

Mudstone

Clinker

0.41 Miles

SE

H H'

Hanna 78

Hanna 79

Hanna 81

Hanna 80

Figure HF-25. Structural cross section H-H' showing the Hanna 78-81 coal beds.
Datum = Sea level

Finch coal bed

107 coal bed

Johnson coal bed

Finch-Johnson

Coal Zone 

Johnson-107

Coal Zone 

Coal

Sandstone

Mudstone

Figure HF-26. Structural cross section I-I' showing the Johnson-107 coal zone.

For more detail

see figure HF-28

{

7500

(feet)

7400

7300

7200

7100

7000

6900

6800

6700

6600

6500

6400

6300

6200

6100

J-J'
Figure HF-27. Crevasse splays draining into floodplain lakes from anastomosed fluvial channels of the Columbia 

River in the Province of British Columbia, Canada. Photograph by D. Smith.
Datum = Sea level

Coal

Sandstone

Mudstone

Finch

coal bed

Johnson

coal bed

Finch-Johnson

coal zone

Johnson-107

coal zone

107

coal bed

{

Figure HF-28. Structural cross section J-J' showing the Johnson-107 coal zone. I-I'