Exline Limestone Member
Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.
M. E. Hopkins and J. A. Simon
The Exline Limestone Member of the Modesto Formation (Cline, 1941, p. 65-66).
Named for Exline, Appanoose County, Iowa.
Exline is near the type section (SE 6, 67N-17W).
In some places the Exline lies immediately on the Lonsdale Limestone, but in others it is as much as 30 feet above the Lonsdale.
Extent and thickness
The Exline occurs in western Illinois where it is dark gray to black, thin- and even-bedded limestone.
In Illinois it usually is less than 3 feet thick, is underlain by black fissile shale, and is overlain by gray marine shale.
Well log characteristics
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.
Age and correlation
Environments of deposition
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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