Assumption Coal Member

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Lithostratigraphy: Kewanee Group >>Spoon Formation >>Assumption 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 Assumption Coal Member of the Spoon Formation (Cady, 1935, p. 53).


Named for Assumption, Christian County, where the coal was mined at a depth of 1002 feet in the long-abandoned Assumption Coal and Mining Company Mine.

Other names


Type section

Type location

The type section is in the Assumption Coal and Mining Company Mine (NE NW SE 2, 12N-1E).

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

Extent and thickness

The extent of the Assumption Coal has not been ascertained, but a coal at approximately this position has been encountered in a few borings scattered throughout the Illinois Basin.


In the mine the coal was 3-4 feet thick and was commonly split into 2 benches. In part of the mine the coal was overlain by limestone correlated with the Seville Limestone, which overlies the Rock Island Coal. The two benches were within 2 feet of each other in some parts of the mine. Where the coal seam was more widely split, the limestone formed the roof of the lower bench, and the interval to the upper bench, as much as 25 feet, consisted of sandstone and carbonaceous shale. The lower bench is the Assumption Coal Member.




Well log characteristics


Age and correlation

The lower of the two benches is tentatively correlated with the Litchfield Coal of southwestern Illinois and the Rock Island (No. 1) Coal of western Illinois.

Environments of deposition

Economic importance



CADY, G. H., 1935, Classification and selection of Illinois coals: Illinois State Geological Survey Bulletin 62, 354p.

ISGS Codes

Stratigraphic Code Geo Unit Designation