Historical:Opdyke Coal Member
M. E. Hopkins and J. A. Simon
The Opdyke Coal Member of the Mattoon Formation (Cady et al., 1952, p. 90-91) is named for the village of Opdyke, Jefferson County.
The type section is in small mines in the vicinity of Belle Rive and Opdyke (3S-4E).
Extent and Thickness
In the type locality the Opdyke is fairly extensive and as much as 2 feet thick locally. It crops out in eastern and southeastern Jefferson County and northwestern Hamilton County. It is believed to be extensive in the subsurface of central Illinois.
It lies about 430 feet above the Shoal Creek Limestone and is tentatively correlated with a 12-inch coal that crops out on the Louden Anticline in eastern Fayette County, 60-70 feet above the Millersville Limestone.
CADY, G. H., et al., 1952, Minable coal reserves of Illinois: Illinois State Geological Survey Bulletin 78, 138 p.
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