Historical:Covel Conglomerate Member
Lithostratigraphy: Kewanee Group >>Carbondale Formation >>Covel Conglomerate Bed
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Desmoinesian Series
Allostratigraphy: Absaroka Sequence
Authors
M. E. Hopkins and J. A. Simon
Name Origin
The Covel Conglomerate Member of the Carbondale Formation (Willman, 1939, p. 174-176) is named for Covel Creek in La Salle County.
Type Section
The type section is along Covel Creek near its mouth (SE SW 26, 33N-3E) (Willman and Payne, 1942, p. 116; Wanless, 1956, p. 10).
Extent and Thickness
This unit is remarkably persistent in northern Illinois and is locally present in western and eastern Illinois. The Covel is generally 1-3 inches thick and is an easily recognized stratigraphic marker. It is also present in southern Iowa and western Indiana (Wanless, 1957).
Description
It is composed of rounded, dark gray to black, phosphatic limestone pebbles and water-worn marine fossils in a matrix of lighter gray limestone or of pyrite. In many places the member is covered with laminated algal growths.
References
WANLESS, H. R., 1956, Classification of the Pennsylvanian rocks of Illinois as of 1956: Illinois State Geological Survey Circular 217, 14 p.
WANLESS, H. R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois State Geological Survey Bulletin 82, 233 p.
WILLMAN, H. B., 1939, Covel Conglomerate, a guide bed in the Pennsylvanian of northern Illinois: Illinois Academy of Science Transactions, v. 32, p. 174-176; Illinois State Geological Survey Circular 60, p. 8-10.
WILLMAN, H. B., and J. N. PAYNE, 1942, Geology and mineral resources of the Marseilles, Ottawa, and Streator Quadrangles: Illinois State Geological Survey Bulletin 66, 388 p.
ISGS Codes
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