Mt. Rorah Coal Member

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Lithostratigraphy: Kewanee Group >>Spoon Formation >>Mt. Rorah Coal 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 Mt. Rorah Coal Member of the Spoon Formation (Kosanke et al., 1960, p. 33).


Named for Mt. Rorah Church.

Other names

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


Type section

Type location

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).

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

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.





Well log characteristics


Age and correlation

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

Environments of deposition

Economic importance



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
Penn symbol.pngtu-mr