Walgreen Member
Lithostratigraphy: Ottawa Limestone Megagroup >>Platteville Group >>Plattin Subgroup >>Grand Detour Formation >>Walgreen Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Blackriveran Stage
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 T. C. Buschbach
Name
Original description
The Walgreen Member of the Grand Detour Formation (Templeton and Willman, 1963, p. 85).
Derivation
Named for the Walgreen estate, on which the type section (part of the Grand Detour type section) occurs.
Other names
History/background
Type section
Type location
The type section of the Walgreen Member is located above the Dement Member in the same type section as that of the Grand Detour (a quarry in the west bluff of the Rock River, on the Walgreen estate 2 miles north of Dixon (NE 20, 22N-9E)) where it is 8.3 feet thick.
Type author(s)
Type status
Reference section
Reference location
Reference author(s)
Reference status
Stratigraphic relationships
Extent and thickness
The Walgreen Member is generally 5-10 feet thick in the outcrop areas in northern Illinois and eastern Missouri.
Lithology
Most of the Walgreen Member is gray, thin- to medium-bedded, argillaceous, shaly limestone that contains disseminated fossil debris and thin beds of purplish gray calcarenite. In the southern outcrop area it is brown, thicker bedded, and less argillaceous than in northern Illinois.
Core(s)
Photograph(s)
Contacts
Well log characteristics
Fossils
Age and correlation
Environments of deposition
Economic importance
Remarks
References
TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
ISGS Codes
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