Historical:Abernathy Member

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Handbook of Illinois Stratigraphy
Series Bulletin 95
Author H. B. Willman, Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, Jack A. Simon
Date 1975
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Lithostratigraphy: Ottawa Limestone Megagroup >>Ancell Group >>Joachim Dolomite >>Abernathy Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Blackriveran Stage
Allostratigraphy: Tippecanoe Sequence

Authors

H. B. Willman and T. C. Buschbach

Name Origin

The Abernathy Member of the Joachim Dolomite (Templeton and Willman, 1963, p. 58), the basal member, is named for Abernathy School, 2 miles north of the type section.

Type Section

The type section of the Abernathy Member is 1.5 miles east of Dutchtown, Missouri (SE NW NE 20, projected, 30N-13E). The upper 25.6 feet is exposed at the type section.

Extent and Thickness

In southern Illinois the Abernathy is present in the subsurface, extending northward as far as Jackson County. It is as much as 150 feet thick in a well in Pulaski County but more commonly is 50-100 feet thick.

Description

The Abernathy Member is largely silty, sandy, thick-bedded dolomite containing layers of dolomitic, medium-grained sandstone. It contains some dark brown layers of limestone and dolomite. A persistent layer of sandstone of St. Peter type 1.5-14 feet thick occurs at the top. Chert is common just below the sandstone.

References

TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation
8290
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