Schweizer Member
Lithostratigraphy: Hunton Limestone Megagroup >>Wilhelmi Formation >>Schweizer Member
Chronostratigraphy: Paleozoic Erathem >>Silurian System >>Alexandrian Series
Allostratigraphy: Tippecanoe Sequence
Primary source
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.
Contributing author(s)
H. B. Willman and Elwood Atherton
Name
Original description
The Schweizer Member of the Wilhelmi Formation (Willman, 1973, p. 13).
Derivation
Named for Schweizer School a mile east of the type section.
Other names
History/background
Type section
Type location
The type section of the Schweizer Member is part of the Wilhelmi Formation type section, located in a railroad cut about 5 miles southwest of Wilhelmi Airport (SE SW SE 35, 35N-9E).
Type author(s)
Type status
Reference section
Reference location
Reference author(s)
Reference status
Stratigraphic relationships
The Schweizer Member is the basal member of the Wilhelmi Formation.
Extent and thickness
Although widely present in subsurface in northeastern Illinois and as much as 80 feet thick, the Schweizer Member is well exposed only in and near the type section, where it is 25 feet thick.
Lithology
The Schweizer Member consists of medium to dark gray dolomitic shale at the base that grades to very argillaceous, silty dolomite at the top. A thin bed of limestone conglomerate marks the base in the type section.
Core(s)
Photograph(s)
Contacts
Well log characteristics
Fossils
Age and correlation
Environments of deposition
Economic importance
Remarks
References
WILLMAN, H. B., 1973, Rock stratigraphy of the Silurian System in northeastern and northwestern Illinois: Illinois State Geological Survey Circular 479, 55 p.
ISGS Codes
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