Excello Shale Member

Revision as of 22:54, 25 January 2017 by IlLex (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

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


Original description

The Excello Shale Member of the Carbondale Formation (Searight et al., 1953).


Named for Excello, Macon County, Missouri.

Other names


Type section

Type location

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

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


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.




Well log characteristics


Age and correlation

Environments of deposition

Economic importance



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.

ISGS Codes

Stratigraphic Code Geo Unit Designation