Oak Grove Limestone Member

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Lithostratigraphy: Kewanee Group >>Carbondale Formation >>Oak Grove Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Desmoinesian 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 Oak Grove Limestone Member of the Carbondale Formation, originally called the Oak Grove beds (Wanless, 1931a, p. 184, 187, 192).


Named for Oak Grove School in Fulton County.

Other names


Type section

Type location

The type section is in a ravine just north of the Oak Grove School (SW SE 6, 5N-3E) (Wanless, 1956, p. 10; 1957, p. 91, 197).

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

The Lowell and Shawneetown Coals appear to occur within strata equivalent to the Oak Grove.

Extent and thickness

In western and northern Illinois the Oak Grove consists of a remarkably persistent sequence of thin, lithologically and paleontologically distinctive limestone beds. Most of them are only a few inches thick, but some are a few feet thick. They are interbedded with dark gray and black shale beds that also have characteristic properties (Wanless, 1957, p. 91-94). The total thickness of the Oak Grove seldom exceeds 15 feet. Limestone units are less abundant in the Oak Grove in southern Illinois.





Well log characteristics


Age and correlation

Limestones equivalent to the Oak Grove are present in western Indiana, southern Iowa, and western Missouri.

Environments of deposition

Economic importance



WANLESS, H. R., 1931a, Pennsylvanian cycles in western Illinois: Illinois State Geological Survey Bulletin 60, p.
WANLESS, H. R., 1956, Classification of the Pennsylvanian rocks of Illinois as of 1956: Illinois State Geological Survey Circular 217, 14 p.
WANLESS, H. R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois State Geological Survey Bulletin 82, 233 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation