Womac Coal Member

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Lithostratigraphy: McLeansboro Group >>Modesto Formation >>Womac Coal Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Missourian Series
Allostratigraphy: Absaroka Sequence

Primary source

Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.

Contributing author(s)

M. E. Hopkins and J. A. Simon


Original description

The Womac Coal Member of the Modesto Formation (Kosanke et al., 1960, p. 38).


Named for Womac, Maccupin County.

Other names

It previously was called the Macoupin Coal (Wanless, 1931b, p. 810-811).


Type section

Type location

The type section consists of exposures in a ravine draining into Macoupin Creek 3 miles southwest of Womac (Wanless, 1956, p. 11).

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

Extent and thickness

This thin coal is widely traced in the Illinois Basin along with the overlying Macoupin Limestone, from which it is separated by 1-2 feet of black fissile shale.





Well log characteristics


Age and correlation

It is correlated with the Raben Branch Coal Member in Indiana.

Environments of deposition

Economic importance



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.
WANLESS, H. R., 1931b, Pennsylvanian section in western Illinois: Geological Society of America Bulletin, v. 42, p. 801-812.
WANLESS, H. R., 1956, Classification of the Pennsylvanian rocks of Illinois as of 1956: Illinois State Geological Survey Circular 217, 14 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation