Historical:Joppa 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: Mammoth Cave Limestone Megagroup >>Ste. Genevieve Limestone >>Joppa Member
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Valmeyeran Series >>Genevievian Stage
Allostratigraphy: Kaskaskia Sequence

Authors

Elwood Atherton, Charles Collinson, and Jerry A. Lineback

Name Origin

The Joppa Member of the Ste. Genevieve Limestone (Swann, 1963, p. 29, 71), the uppermost member, is named for Joppa Junction, Johnson County.

Type Section

The type section of the Joppa Member of the Ste. Genevieve Limestone is located about a half a mile east of Joppa Junction, Johnson County (SW SW 32, 13S-2E), where the member comprises 32 feet of shale and limestone overlying the Karnak Limestone Member.

Extent and Thickness

The Joppa is 20-50 feet thick.

Description

In southeastern Illinois the Joppa generally includes prominent limestones that allow it to be readily separated from the Aux Vases Sandstone. However, in most of the western and northern parts of the basin it is impractical to separate the Joppa from the Aux Vases, and there the Joppa is terminated by a vertical cut-off. Most of the limestone is sandy and oolitic, and part of it is red and hematitic. The sandstone is generally very fine grained and calcareous, resembling that of the Aux Vases. The shale is largely dark greenish gray, but red and green shales are common.

References

SWANN, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation
5070
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