Macoupin Limestone Member

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Lithostratigraphy: McLeansboro Group >>Modesto Formation >>Macoupin Limestone 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 Macoupin Limestone Member of the Modesto Formation (Wanless, 1931b, p. 810-811).


Named for Macoupin Creek in Macoupin County.

Other names


Type section

Type location

The type section is exposed along Macoupin Creek (NE NW 2, 9N-7W) (Wanless, 1956, p. 11; Ball, 1952, p. 85-86).

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

Extent and thickness

It is a widespread unit, found throughout much of the Illinois Basin. The limestone is generally less than 2 but locally as much as 5 feet thick.


In the type area it is composed of thin, even beds of crinoidal limestone separated in places by shale partings. Most of it is dark gray and very argillaceous.




Well log characteristics


Age and correlation

Environments of deposition

Economic importance



BALL, J. R., 1952, Geology and mineral resources of the Carlinville Quadrangle: Illinois State Geological Survey Bulletin 77, 110 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