Historical:Exline Limestone Member
M. E. Hopkins and J. A. Simon
The Exline Limestone Member of the Modesto Formation (Cline, 1941, p. 65-66) is named for Exline, Appanoose County, Iowa.
Exline is near the type section (SE 6, 67N-17W).
Extent and Thickness
The Exline occurs in western Illinois where it is dark gray to black, thin- and even-bedded limestone.
In some places the Exline lies immediately on the Lonsdale Limestone, but in others it is as much as 30 feet above the Lonsdale.
In Illinois it usually is less than 3 feet thick, is underlain by black fissile shale, and is overlain by gray marine shale.
It contains well preserved plant stems and leaves, the worm tube Spirorbis, and a few marine pelecypods (Wanless, 1957, p. 120). In Iowa, the Exline contains a normal marine fauna.
CLINE, L. M., 1941, Traverse of upper Des Moines and lower Missouri series from Jackson County, Missouri, to Appanoose County, Iowa: American Association of Petroleum Geologists Bulletin, v. 25, p. 23-72.
WANLESS, H. R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois State Geological Survey Bulletin 82, 233 p.
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