Geologic units in Boone county, Indiana

Borden Group (Mississippian) at surface, covers 60 % of this area

Mostly siltstone; lenses of crinodial limestone in upper part. Much cherty and silty limestone and dolomite in northwest. NP, top of New Providence Shale

New Albany Shale (Devonian-Mississippian) at surface, covers 22 % of this area

Black and greenish-gray shale

Muscatatuck Group (Devonian) at surface, covers 16 % of this area

Limestone and dolomite

Wabash Formation (Silurian) at surface, covers 2 % of this area

Limestone, dolomite, and argillaceous dolomite