Historical:O'Nan Coal Member
M. E. Hopkins and J. A. Simon
The O'Nan Coal Member of the Spoon Formation (Kosanke et al., 1960, p. 32) is named for Dennis O'Nan Ditch, which flows across the tip of Indian Hill, Union County, Kentucky, the type locality (Glenn, 1912, p. 25).
It previously was called the Curlew Coal (Owen, 1856, p. 47).
It is now believed to be equivalent to the Bidwell Coal.
Extent and Thickness
The O'Nan Coal is generally thin, seldom over 1 foot thick in its scattered occurrences in southern Illinois.
GLENN, L. C., 1912, A geological reconnaissance of the Tradewater River region, with special reference to the coal beds: Kentucky Geological Survey Bulletin 17, 75 p.
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.
OWEN, D. D., 1856, Report of the geological survey in Kentucky made during the years 1854 and 1855: Kentucky Geological Survey Bulletin, v. I, Series 1, 416 p.
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