Stewartville Member
Lithostratigraphy: Ottawa Limestone Megagroup >>Galena Group >>Kimmswick Subgroup >>Wise Lake Formation >>Stewartville Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Trentonian 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 Stewartville Member of the Wise Lake Formation (Ulrich, 1911, pl. 27)(originally the Stewartville Formation).
Derivation
Named for Stewartville, Olmstead County, Minnesota, which is half a mile east of the type section.
Other names
History/background
Type section
Type location
The type section of the Stewartville Member is located half a mile west of Stewartville, Olmstead County, Minnesota, in a quarry on the north side of the Root River, where 28 feet of dolomite in the lower part of the member is exposed (Kay, 1935a, p. 567).
Type author(s)
Type status
Reference section
Reference location
Reference author(s)
Reference status
Stratigraphic relationships
The Stewartville Member is the upper member of the Wise Lake Formation.
Extent and thickness
The Stewartville Member is about 60 feet thick in the type locality, but only 30-35 feet thick in northern Illinois.
Lithology
The Stewartville Member is largely thick-bedded, pure dolomite, and many samples from the lower 10-15 feet (the Upper Receptaculites Zone) contain almost no insoluble residue. The bedding becomes thinner upward as a gradual transition to the shaly Dubuque Formation above takes place. The top of the Stewartville is placed at the lowest definitely argillaceous or shaly bedding plane. Above this position is the first occurrence of Pseudolingula iowensis, which is common in the higher, more shaly part of the Dubuque Formation. The Stewartville Member is the Maclurea bed of early reports.
Core(s)
Photograph(s)
Contacts
Well log characteristics
Fossils
Age and correlation
Environments of deposition
Economic importance
Remarks
References
KAY, MARSHALL, 1935a, Ordovician Stewartville-Dubuque problems: Journal of Geology, v. 43, p. 541-590.
ULRICH, E. O., 1911, Revision of the Paleozoic systems: Geological Society of America Bulletin, v. 22, p. 281-680.
ISGS Codes
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