Historical:Mt. Rorah Coal Member

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Handbook of Illinois Stratigraphy
Series Bulletin 95
Author H. B. Willman, Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, Jack A. Simon
Date 1975
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Lithostratigraphy: Kewanee Group >>Spoon Formation >>Mt. Rorah Coal Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Desmoinesian Series
Allostratigraphy: Absaroka Sequence


M. E. Hopkins and J. A. Simon

Name Origin

The Mt. Rorah Coal Member of the Spoon Formation (Kosanke et al., 1960, p. 33) is named for Mt. Rorah Church.

Type Section

The type locality is about 2 miles south of Mt. Rorah Church (SE 25, 10S-4E; erroneously listed as section 35 in Wanless, 1956, p. 9, and Kosanke et al., 1960, p. 45).

Other Names

It previously was called the Bald Hill Coal (Cady, 1926, p. 259-260).


It is correlated with the De Long Coal of western Illinois.

Extent and Thickness

The Mt. Rorah Coal occurs sporadically in a large part of southern Illinois, but it is seldom over 2 feet thick, generally no more than a few inches.


CADY, G. H., 1926, Areal geology of Saline County: Illinois Academy of Science Transactions, v. 19, p. 250-272.
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., 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