Historical:Bonpas Limestone Member
Lithostratigraphy: McLeansboro Group >>Mattoon Formation >>Bonpas Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Missourian Series
Allostratigraphy: Absaroka Sequence
Authors
M. E. Hopkins and J. A. Simon
Name Origin
The Bonpas Limestone Member of the Mattoon Formation (Kosanke et al., 1960, p. 41) is named for Bonpas Creek, Richland County.
Type Section
The type section is in a roadcut exposure about 1.5 miles west of Bonpas Creek, the same location as the Calhoun Coal type section (Kosanke et al., 1960, p. 41, 82).
Other Names
It previously was called Calhoun Limestone (Weller, in Dunbar and Henbest, 1942, p. 27).
Correlation
It is correlated with the Omega Limestone of the western side of the area covered by the Mattoon Formation.
Extent and Thickness
The Bonpas is 3 feet thick in the type locality and is widely distributed in eastern Illinois.
Fossils
The Bonpas contains a varied open-marine fauna.
References
DUNBAR, C. O., and L. G. HENBEST, 1942, Pennsylvanian Fusulinidae of Illinois: Illinois State Geological Survey Bulletin 67, 218 p.
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.
ISGS Codes
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