Cramer Limestone Member
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.
M. E. Hopkins and J. A. Simon
The Cramer Limestone Member of the Modesto Formation (Kosanke et al., 1960, p. 38).
Named for Cramer, Peoria County.
It previously was called Trivoli Limestone (Wanless, 1931a, p. 182, 190, 192).
The type section consists of exposures in a ravine northeast of Pea Ridge School, 1.3 miles northeast of the village of Cramer (Wanless, 1956, p. 11; 1957, p. 121, 193).
Extent and thickness
The Cramer is generally less than 1 foot thick. It is lenticular but widespread and is commonly found throughout the same area as the underlying Chapel (No. 8) Coal, from which it is commonly separated by 1-2 feet of black fissile shale.
The Cramer Limestone is normally very argillaceous.
Well log characteristics
The Cramer contains an abundant open-marine fauna.
Age and correlation
It is correlated with the Sniabar Limestone of southern Iowa, Missouri, and eastern Kansas.
Environments of deposition
KOSANKE, R. M., J. A. SIMON, H. R. WANLESS, and H. B. WILLMAN, 1960, Classification of the Pennsylvanian strata of Illinois: Illinois State Geological Survey Report of Investigations 214, 84 p.
WANLESS, H. R., 1931a, Pennsylvanian cycles in western Illinois: Illinois State Geological Survey Bulletin 60, p.
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.
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