H. B. Willman and T. C. Buschbach
The Kimmswick Subgroup is named for Kimmswick, Jefferson County, Missouri.
The type section of the Kimmswick Subgroup is in a quarry about a mile west of Kimmswick on the north side of Rock Creek just west of the mouth of Black Creek (approximately SE NE 18, 42N-6E).
Extent and Thickness
The Kimmswick Subgroup occurs throughout the area of the Galena Group. It is about 250 feet thick in northern Illinois, thins rapidly in an east-west belt through the central part of the state, and it is only 90-125 feet thick in most of the southern half of the state.
The Kimmswick Subgroup (Ulrich, 1904, p. 111; Templeton and Willman, 1963, p. 114) consists of the dominantly pure limestone and dolomite formations that compose the middle part of the Galena Group. It excludes the shaly strata of the Dubuque Formation at the top and the shaly formations of the Decorah Subgroup at the base. It is dominantly limestone in the southern two-thirds of the state and dolomite north of there. It is subdivided into the basal Dunleith Formation, which contains some argillaceous beds and is medium bedded and generally cherty, and the Wise Lake Formation, which is pure, massive, and not cherty. Only the Dunleith Formation is present in the Kimmswick type locality because the Wise Lake is truncated by the Cincinnatian Series south of the belt through the central part of the state where the Galena Group thins.
TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
ULRICH, E. O., 1904, in E. R. Buckley and H. A. Buehler, Quarrying industry of Missouri: Missouri Bureau of Geology And Mines, v. 2, 371 p.
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