Historical:West Franklin Limestone 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: McLeansboro Group >>Modesto Formation >>West Franklin Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Desmoinesian Series
Allostratigraphy: Absaroka Sequence

Authors

M. E. Hopkins and J. A. Simon

Name Origin

The West Franklin Limestone Member of the Modesto Formation (Collett, 1884, p. 61-62) is named for West Franklin, Posey County, Indiana.

Type Section

The type section consists of outcrops near the town (24, 7S-12W) (Wanless, 1956, p. 11).

Correlation

It is likely that the West Franklin Limestone is equivalent to the entire interval from the Piasa Limestone upward through the Lake Creek Coal in southern Illinois and through the Scottville Limestone in southwestern Illinois. The Piasa Limestone also may be equivalent to the lower bench of the West Franklin (Andresen, 1956). The West Franklin is probably also equivalent to the interval including the Lonsdale and Exline Limestones of western Illinois and to the Madisonville Limestone of western Kentucky.

Extent and Thickness

The member is recognized largely in southeastern Illinois. It is a fine-grained limestone generally less than 15 feet thick and occurs in one to three benches, each generally less than 10 feet thick and separated by a few feet of greenish gray to variegated claystone. The number of limestone benches decreases to the west as the underlying shale, probably the Farmington Shale, thins from east to west.

Stratigraphic Position

In the eastern part of its area the West Franklin is closely overlain by the Chapel (No. 8) Coal.

References

ANDRESEN, M. J., 1956, Subsurface stratigraphy and sedimentation of the West Franklin-Cutler limestone zones of southern Illinois: University of Illinois M.S. thesis.
COLLETT, JOHN, 1884, Geology of Posey County, Indiana: Indiana Department of Geology and Natural History, 13th Annual Report, p. 45-70.
WANLESS, H. R., 1956, Classification of the Pennsylvanian rocks of Illinois as of 1956: Illinois State Geological Survey Circular 217, 14 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation
2360
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