Excello Shale Member

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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

Type section

Type location

Type author(s)

Type status

Reference section

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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.

Core(s)

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Contacts

Well log characteristics

Fossils

Age and correlation

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Economic importance

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.

ISGS Codes

Stratigraphic Code Geo Unit Designation
2830
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