McCormick Group (abandoned)

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Lithostratigraphy: McCormick Group
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Morrowan 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

Kosanke et al. (1960, p. 28) established the McCormick Group, comprised of the Caseyville Formation and the newly designated Abbott Formation overlying the Caseyville. Compared with the overlying Kewanee Group (also newly named, but now also abandoned), the McCormick contained a greater proportion of sandstone, thinner and more lenticular shale and limestone, and less marked cyclicity.


The name alludes to the settlement of McCormick in northwestern Pope County, southern Illinois. Christian L. McCormic (no “k”) settled here in the 1880s and established a general store. A gristmill, hoop mill, blacksmith shop, and post office followed. McCormick boomed in the 1920s, when the Illinois Central Railroad built the Edgewood Cutoff and hundreds of workers drove a tunnel and deep cuts through the Shawnee Hills. After the railroad was completed, people moved away and the businesses closed (Sneed 1977). Today, McCormick is a small cluster of houses.

Other names

None. This name was never used outside Illinois.


With abandonment of the Abbott Formation (Nelson et al. 1991; Tri-State Committee 2001), the McCormick Group lost its upper portion. A group cannot contain only part of a formation (in this case, the Tradewater). Thus, having standardized the upper boundary, the Tri-State Committee extended the Raccoon Creek Group throughout the Illinois Basin and abandoned use of the McCormick Group.

Type section

Kosanke et al. (1960, p. 44) listed “Vicinity of McCormick, NW part of [Pope] County” but did not describe the section. Reference can be made to type sections of the Caseyville (Lee 1916) and Abbott (Kosanke et al. 1960). Appropriately, the latter consists of exposures along the Edgewood Cutoff past the site of McCormick.


  • 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., 1 pl.
  • Lee, W., 1916, Geology of the Shawneetown Quadrangle in Kentucky: Kentucky Geological Survey, Ser. 4, v. 4, part 2, 73 p.
  • Nelson, W.J., J.A. Devera, R.J. Jacobson, D.K. Lumm, R.A. Peppers, B. Trask, C.P. Weibel, L.R. Follmer, M.H. Riggs, S.P. Esling, E.D. Henderson, and M.S. Lannon, 1991, Geology of the Eddyville, Stonefort, and Creal Springs Quadrangles, southern Illinois: Illinois State Geological Survey, Bulletin 96, 85 p., 1 pl.
  • Sneed, G.J., 1977, Ghost towns of southern Illinois: Royalton, Illinois, G.J. Sneed, 309 p.
  • Tri-State Committee, 2001, Toward a more uniform stratigraphic nomenclature for rock units (formations and groups) of the Pennsylvanian System in the Illinois Basin: Illinois, Indiana, and Kentucky Geological Surveys, Illinois Basin Consortium Study 5, 26 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation