H. B. Willman and T. C. Buschbach
The Gordonville Member of the Dutchtown Limestone (Templeton and Willman, 1963, p. 54), the lower member, is named for Gordonville, Cape Girardeau County, Missouri.
The Gordonville Member type section is located 4.5 southeast of Gordonville, in the Geiser Quarry, 1.25 miles east of Dutchtown (SW NW NW 20, projected, 30N-13E), where the upper 5 feet is exposed.
Extent and Thickness
In wells in Illinois the Gordonville Member ranges from 130 feet thick in southern Pulaski County to 45 feet in southwestern Jackson County, north of which it thins out rapidly. It does not extend as far north as the overlying Sharpsboro Member.
The Gordonville Member normally consists of dolomite with subordinate amounts of limestone, but in southern Jackson County, close to the transition into the St. Peter Sandstone, it is composed mainly of dolomite-cemented, medium-grained sandstone. The dolomite and limestone are mostly sandy, silty, greenish gray to dark gray, and a few layers are dark brown to black.
TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
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