Excello Shale Member
Lithostratigraphy: Kewanee Group >>Carbondale Formation >>Excello Shale 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
Name
Original description
The Excello Shale Member of the Carbondale Formation (Searight et al., 1953).
Derivation
Named for Excello, Macon County, Missouri.
Other names
History/background
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Stratigraphic relationships
It generally directly underlies the Hanover Limestone, but in some places in western Illinois a lighter colored shale a few feet thick intervenes. The Excello immediately overlies the Summum (No. 4) Coal, except locally in northern Illinois where a few feet of gray shale separates them.
Extent and thickness
Lithology
In Illinois, the Excello is composed of black fissile shale that is generally 1-3 feet thick and similar in character to the member in Missouri (Nance, 1970, p. 77). Large black limestone concretions commonly occur in the lower part.
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Remarks
References
NANCE, R. B., 1970, Limestones and phosphatic rocks from the Summum and Liverpool cyclothems in western Illinois: Illinois State Geological Survey Guidebook Series 8, p. 75-83.
SEARIGHT, W. V., et al., 1953, Classification of the Desmoinesian (Pennsylvanian) of the northern Mid-Continent: American Association of Petroleum Geologists Bulletin, v. 37, p. 2747-2749.
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