Davis Coal Member or Bed

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Lithostratigraphy: Carbondale Formation >>Davis Coal Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Desmoinesian Series
Allostratigraphy: Absaroka Sequence

Primary source

Nelson, W.J., P.H. Heckel and J.M. Obrad, 2022, Pennsylvanian Subsystem in Illinois: Illinois State Geological Survey, Bulletin (in press).

Contributing author(s)

W.J. Nelson


Original description

Lee (1916, p. 29–30, 66) gave the name “Davis coal” to the seam being worked in the Davis Mine of the Crittenden Coal & Coke Company, about 3 mi (5 km) west of Sturgis in Union County, Kentucky.


As stated above, the name of the coal is derived from the Davis Mine in Union County, Kentucky. Norwood (1912, p. 333–335) described the Davis Mine in detail, although the exact location of the Davis Mine is uncertain. Without citing a source, Kosanke et al. (1960) located the mine ½ mi [0.8 km] east of Dekoven. However, it was more likely one of the two drift entries shown on the geologic map of Kehn (1974) adjacent to Davis Mine Road, about 2 mi (3 km) southeast of Dekoven and 4 mi (6 km) west of Sturgis. These adits are both adjacent to the Illinois Central Railroad, as Norwood indicated.

Other names

In the earliest Kentucky reports, the Davis was called the “Four-foot coal” in reference to its consistent thickness and was designated as Coal No. 5. This was revised to No. 6 around the time of Lee (1916). In Illinois, the Davis and overlying Dekoven were sometimes called No. 2 and No. 3 coals, respectively.


Lee (1916) was the first to extend the Carbondale Formation into Kentucky and the first to designate the Davis Coal as the formation base. Butts (1925) first extended the Davis Coal into Illinois, again at the base of the Carbondale. Like Lee, Butts (1925) mistakenly identified the Davis with the older Murphysboro Coal in the Tradewater Formation. Kosanke (1950) may have been the first to positively establish that the Murphysboro is older than the Davis.

Type section

No type section was designated. Norwood (1912, p. 333–335) gave a succinct description of the coal in the Davis Mine. The Davis Mine was sealed more than a century ago.

Reference section

Figure 4-13. Graphic log of the upper part of the Kentucky Geological Survey’s Gil-15 core, principal reference section for the Dekoven and Davis Coal Members. Location is in Carter section 5-M-18, Union County, Kentucky. © University of Illinois Board of Trustees.

Reference location

For a principal reference section, the core from the Kentucky Geological Survey’s Gil 15 borehole serves admirably. Drilled within about 2 mi (3 km) of the Davis Mine site, the Gil 15 core spans the interval from above the Survant Coal Member (Carbondale Formation) to the top of the Caseyville Formation. Williams et al. (1982) published a verbal description of the entire core; a graphic log of the relevant portion is presented here (Figure 4-13).

Reference author(s)

Present report.

Reference status

Original logs are on file with the Kentucky Geological Survey; the core resides at the Kentucky Geological Survey core facility in Lexington.

Stratigraphic relationships

See the discussion of the Seelyville Coal Member. The Davis is considered a member where it is separated from the younger Greenbush or Dekoven Coal by siliciclastic strata. Where it is a component of the Seelyville Member, the Davis is classified as a bed.

Extent and thickness

The Davis Coal is uniform in thickness and character across western Kentucky. A map by Greb et al. (1992) shows the coal to be between 28 and 56 in. (71 to 142 cm) thick except along the southern and eastern margins of the region and in small areas elsewhere, where it is thinner.

Extensive surface mining and small-scale underground mining have taken place near the outcrops in Gallatin, Saline, and eastern Williamson Counties of southeastern Illinois. In the former two counties, the coal ranges from less than 0.5 ft (15 cm) to more than 6 ft (1.8 m), but it is close to 4 ft (1.2 m) thick across most of the area. Northward in southeastern Illinois, the Davis is generally thicker than 28 in. (71 cm), and sizeable areas of coal are thicker than 42 in. (107 cm; Korose et al. 2002). The coal has not been mapped in the rest of Illinois, but probably only a few small areas exist where it is thick enough to mine. In a large area of western Illinois, Wanless (1957) reported that the Davis (formerly called Wiley Coal) ranges in thickness from a streak to 16 in. (451 cm) among nearly 250 control points.

Treworgy and Bargh (1982, 1984) mapped reserves of Wiley (Davis) coal ranging from 28 to 42 in. (71 to 107 cm) thick in Macoupin and Montgomery Counties, western Illinois. Drilling records indicate that this deposit contains a medial claystone layer and should be classified as Seelyville Coal.


The Davis is predominantly bright-banded coal that exhibits closely spaced cleat. Although thin laminae of fusain, pyrite, and shale are present, none is continuous across large areas. Pyrite is common as lenses, nodules, and cleat facings. In both southern Illinois and western Kentucky, the ash content averages about 8% and the sulfur content is close to 3% (Cobb et al. 1985; Jacobson 1993).

The Davis (and Seelyville) generally has well-developed underclay 3 to more than 8 ft (0.9 to 2.4 m) thick. This is mostly olive to greenish gray and tends to grade from siltstone in the lower portion to claystone in the upper part. Roots and slickensides are prevalent in the upper part, siderite-filled fractures in the lower part. Limestone and dolomite nodules seldom are present. The Davis underclay has characteristics of a vertisol, which implies a seasonally dry climate.

Overlying the Davis Coal is a clastic interval that ranges up to 90 ft (27 m) in thickness. Directly above the coal is a widespread unit of black, fissile shale that is herein named the Will Scarlet Shale Member. The remainder of the succession comprises medium to dark gray shale and siltstone and light to medium gray, fine-grained sandstone. These strata typically coarsen upward, but in places, channel-form sandstone cuts down close to, and rarely through, the Davis Coal.




Both contacts of the coal normally are abrupt. Regionally, the Davis merges with the Dekoven and Abingdon Coal Members to comprise the Seelyville Coal Member.

Well log characteristics

Figure 4-14. Gamma ray/density and neutron log from the Peabody Natural Gas No. 2 Short borehole in sec. 14, T 7 S, R 7 E, Hamilton County, Illinois, illustrating the log response of Davis, Will Scarlet, Dekoven, and associated units. © University of Illinois Board of Trustees.

The log response is typical for coal. The “hot” gamma-ray response of the Will Scarlet Shale overlying the Davis often helps distinguish this seam from the Dekoven, which lacks overlying radioactive shale (Figure 4-14).


Kosanke (1950) determined that the fossil spore assemblage of the Davis Coal closely resembles that of the Wiley Coal in western Illinois, and that both differ from the younger Dekoven and Greenbush Coals. This floral similarity confirms the equivalence of the Davis to the Wiley and of the Dekoven to the Greenbush. Peppers (1970) endorsed these correlations but suggested that the Seelyville Coal is slightly younger than the Dekoven. Peppers and Popp (1979) continued to chart the Seelyville as younger than the Dekoven but allowed that the seams “might be at least partly equivalent” (p. 71). Peppers (1996, chart) bowed to Jacobson’s direct physical correlation of the Davis, Dekoven, and Seelyville.

Age and correlation

Age is near the middle of the Desmoinesian Stage. As discussed under the Seelyville Coal Member, the Davis probably correlates with the Mineral Coal Bed in the Midcontinent Basin. In the northern Appalachian Basin, the position of the Davis is intermediate between the Clarion (older) and Lower Kittanning coal beds.

Environments of deposition

The Davis is a banded coal of regional extent, resting on a well- developed underclay and overlain by clastics, including basal black, slaty shale. Accordingly, it fits the general model for peat accumulation in the Illinois Basin.

Economic importance

The Davis Coal has been mined extensively in underground and surface mines in western Kentucky and in surface mines in Gallatin and Saline Counties, southeastern Illinois. The remaining resources have been estimated at 7.49 billion tons (6.79 billion metric tons) in Kentucky and 9.57 billion tons (8.68 billion metric tons) in Illinois (Keystone 2010).



  • Butts, C., 1925, Geology and mineral resources of the Equality-Shawneetown area: Illinois State Geological Survey, Bulletin 47, 76 p., 2 pls.
  • Cobb, J.C., R.A. Brant, J.C. Currens, and A.D. Williamson, 1985, Kentucky coal: Kentucky Geological Survey, Series 11, Reprint 20, 17 p.
  • Greb, S.F., D.A. Williams, and A.D. Williamson, 1992, Geology and stratigraphy of the western Kentucky coal field: Kentucky Geological Survey, Series 11, Bulletin 2, 77 p., 1 pl.
  • Jacobson, R.J., 1993, Coal resources of the Dekoven and Davis Members (Carbondale Formation) in Gallatin and Saline Counties, southeastern Illinois: Illinois State Geological Survey, Circular 551, 41 p., 5 pls.
  • Kehn, T.M., 1974, Geologic map of parts of the Dekoven and Saline Mines Quadrangles, Crittenden and Union Counties, Kentucky: U.S. Geological Survey, Geologic Quadrangle Map GQ-1147, 1 sheet, 1:24,000.
  • Keystone, 2010, Keystone Coal Industry manual: Jacksonville, Florida, Mining Media International, 631 p.
  • Korose, C.P., C.G. Treworgy, R.J. Jacobson, and S.D. Elrick, 2002, Availability of the Danville, Jamestown, Dekoven, Davis, and Seelyville Coals for mining in selected areas of Illinois: Illinois State Geological Survey, Illinois Minerals 124, 44 p.
  • Kosanke, R.M., 1950, Pennsylvanian spores of Illinois and their use in correlation: Illinois State Geological Survey, Bulletin 74, 128 p., 2 pls.
  • Kosanke, R.M., J.A. Simon, H.R. Wanless, and H.B. Willman, 1960, Classification of the Pennsylvanian strata of Illinois: Illinois State Geological Survey, Report of Investigations 214, 84 p. and 1 pl.
  • Lee, W., 1916, Geology of the Kentucky part of the Shawneetown Quadrangle: Kentucky Geological Survey, Series 4, Bulletin 4, Part 2, 73 p.
  • Norwood, C.J., 1912, Report of Inspector of Mines for the year 1910: Louisville, Kentucky Department of Mines and Minerals.
  • Peppers, R.A., 1970, Correlation and palynology of coals in the Carbondale and Spoon Formations (Pennsylvanian) of the northeastern part of the Illinois Basin: Illinois State Geological Survey, Bulletin 93, 173 p.
  • Peppers, R.A., 1996, Palynological correlation of major Pennsylvanian (Middle and Upper Carboniferous) chronostratigraphic boundaries in the Illinois and other coal basins: Geological Society of America, Memoir 188, 111 p. and correlation chart.
  • Peppers, R.A., and J.T. Popp, 1979, Stratigraphy of the lower part of the Pennsylvanian System in southeastern Illinois and adjacent portions of Indiana and Kentucky, in J.E. Palmer and R.R. Dutcher, eds., Depositional and structural history of the Pennsylvanian System in the Illinois Basin, Part 2, Invited papers: Ninth International Congress of Carboniferous Stratigraphy and Geology, Field Trip 9: Illinois State Geological Survey, Guidebook 15A, p. 65–72.
  • Treworgy, C.G., and M.H. Bargh, 1982, Deep-minable coal resources of Illinois: Illinois State Geological Survey, Circular 527, 62 p., 2 pls.
  • Treworgy, C.G., and M.H. Bargh, 1984, Coal resources of Illinois: Illinois State Geological Survey, 6 maps, 1:500,000.
  • Wanless, H.R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois State Geological Survey, Bulletin 82, 233 p.
  • Williams, D.A., A.D. Williamson, and J.G. Beard, 1982, Stratigraphic framework of coal-bearing rocks in the western Kentucky coal Field: Kentucky Geological Survey, Series 11, Information Circular 8, 201 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation
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