Historical:Cooper Limestone Member
Lithostratigraphy: Hunton Limestone Megagroup >>Grand Tower Limestone >>Cooper Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Devonian System >>Middle Devonian Series
Allostratigraphy: Kaskaskia Sequence
Authors
Charles Collinson and Elwood Atherton
Name Origin
The Cooper Limestone Member of the Grand Tower Limestone (Swallow, 1855, p. 108, 196) is named for Cooper County, Missouri, where it is classified as a facies of the Calloway Limestone (Koenig, 1961).
Correlation
The Cooper Limestone Member is similar to the Wapsipinicon Limestone north of the Sangamon Arch and probably is continuous with it west of Illinois.
Extent and Thickness
In Illinois the Cooper Limestone Member is as much as 50 feet thick in a belt 60-90 miles wide that extends eastward across the state south of the Sangamon Arch (fig. D-14). It is exposed only in Calhoun County (Meents and Swann, 1965), where it previously was considered part of the Cedar Valley Limestone.
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Stratigraphic Position
On its northern margin the Cooper is overlapped by the Lingle Limestone, and on the south it grades laterally to the light-colored dolomite that overlies the Geneva Dolomite Member.
Description
The Cooper Limestone Member is sparsely fossiliferous, gray, dense, lithographic, pure limestone, but it contains scattered grains of quartz sand in some localities.
References
KOENIG, J. W., 1961, Devonian System, in Stratigraphic succession in Missouri: Missouri Geological Survey, v. 40, p. 36-49.
MEENTS, W. F., and D. H. SWANN, 1965, Grand Tower Limestone (Devonian) of southern Illinois: Illinois State Geological Survey Circular 389, 34 p.
SWALLOW, G. C., 1855, Geology of Missouri: Missouri Geological Survey 2nd Annual Report, p. 59-170.
ISGS Codes
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