T. C. Buschbach
The Dresbachian Stage (Winchell, 1886, p. 334-337), named for Dresbach, Winona County, Minnesota.
These strata were originally called the Dresbach Sandstone (or Formation) and in some areas are now referred to as the Dresbach Group.
Extent and Thickness
In Illinois the stage is represented by 1500-3500 feet of sandstone and dolomite that is differentiated into the Mt. Simon Sandstone (below), the Eau Claire Formation, and the Galesville Sandstone.
The Dresbachian Stage consists of all strata of Croixan age below the Elvinia Zone. It includes the Cedaria (oldest), Crepicephalus, and Aphelaspis Zones (Howell et al., 1944). As the Mt. Simon and Galesville Sandstones lack fossils, the precise boundaries of the stage are uncertain (Buschbach, 1964).
BUSCHBACH, T. C., 1964, Cambrian and Ordovician strata of northeastern Illinois: Illinois State Geological Survey Report of Investigations 218, 90 p.
HOWELL, B. F., et al., 1944, Correlation of the Cambrian formations of North America: Geological Society of America Bulletin, v. 55, p. 993-1003.
WINCHELL, N. H., 1886, Revision of the stratigraphy of the Cambrian in Minnesota: Minnesota Geological and Natural History Survey 14th Annual Report (1885), p. 325-337.
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