Karnak Member formally proposed in this report for relatively pure persistent limestone unit in Ste. Genevieve Limestone of Genevievian age. Commonly 10 to 35 ft thick. It overlies sandstone, siltstone, shale, or impure limestone assigned to Spar Mountain Member. At type section, the top 16 ft of an estimated 20 to 25 ft of cross-bedded oolitic limestone is exposed in cuts on IL Hwy 37. Lower beds inadequately exposed in hill slope southeast of junction of highway with gravel road to Belknap. About 300 ft east of junction, top of Karnak lies 51 ft beneath base of Levias Limestone Member of Renault and directly beneath type section of Joppa Member.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Usage of the Ste. Genevieve Limestone of the Blue River Group in Indiana is here revised. In the subsurface, unit is divided into (ascending) Fredonia, Karnak, and Joppa Members, which are basically equivalent to members of the same name in IL. Levias and Spar Mountain Members of Ste. Genevieve are no longer used in Indiana. This nomenclature replaces that of Shaver and others (1986) as the IN State usage. In outcrop, Joppa is replaced by rocks typical of upper Karnak. Uppermost rocks of the Ste. Genevieve on the surface and in the very shallow subsurface are assigned to the Bryantsville Breccia Bed of the Karnak Member. Bryantsville of previous usage marked the top of the Levias Member. Lost River Chert Bed marks the base of the Fredonia Member and therefore the base of the Ste. Genevieve. Fredonia is stratigraphically extended in this study to include the equivalent to both the Fredonia and Spar Mountain Members as previously used on the outcrop in Indiana.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Used as Mississippian (Valmeyeran) Karnak Member of Ste. Genevieve Limestone in IN. Usage follows Droste and Carpenter (1990).

Source: GNU records (USGS DDS-6; Reston GNULEX).