Historical:Rock Branch Coal 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 >>Rock Branch Coal Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Desmoinesian Series
Allostratigraphy: Absaroka Sequence


M. E. Hopkins and J. A. Simon

Name Origin

The Rock Branch Coal Member of the Modesto Formation (Kosanke et al., 1960, p. 37) is named for Rock Branch in Macoupin County.

Type Section

The type section consists of exposures along Rock Branch (SW SW NW 16, 12N-9W).

Other Names

It previously was called the Scottville Coal (Payne, 1942, p. 4).


The Rock Branch Coal may be equivalent to the Pond Creek Coal of southern Illinois.

Extent and Thickness

This thin coal occurs in southwestern Illinois.


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.
PAYNE, J. N., 1942, Structure of Herrin (No. 6) coal bed in Macoupin County, eastern Jersey and Greene, southeastern Scott, and southern Morgan and Sangamon Counties: Illinois State Geological Survey Circular 88, 46 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation