Lawson Shale 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 Lawson Shale Member of the Carbondale Formation (Kosanke et al., 1960, p. 35).
Named for Lawson Creek in Bureau County.
It previously was called Sheffield Shale (Wanless, 1939, p. 102; 1956, p. 10; 1957, p. 112).
Lawson Creek is about a mile west of the type section (cen. 24, 16N-6E) (Wanless, 1956, p. 10; 1957, p. 112).
The upper part of the Lawson is in some places interbedded with sandstone that grades laterally into the Copperas Creek Sandstone. At other places the Copperas Creek lies unconformably on the shale. It is underlain throughout most of western Illinois by the Brereton Limestone or, locally, by either the Anna Shale or Herrin (No. 6) Coal.
Extent and thickness
The Lawson is typically a gray silty shale as much as 25 feet thick in western Illinois. In much of west-central and southwestern Illinois the Lawson is a weak, gray and green mottled shale.
Well log characteristics
Age and correlation
It probably correlates with a similar shale that underlies the Anvil Rock Sandstone in southern Illinois.
Environments of deposition
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.
WANLESS, H. R., 1939, Pennsylvanian correlations in the Eastern Interior and Appalachian coal fields: Geological Society of America Special Paper 17, 130 p.
WANLESS, H. R., 1956, Classification of the Pennsylvanian rocks of Illinois as of 1956: Illinois State Geological Survey Circular 217, 14 p.
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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