Geologic units in Marion county, Indiana

Muscatatuck Group (Devonian) at surface, covers 44 % of this area

Limestone and dolomite

New Albany Shale (Devonian-Mississippian) at surface, covers 34 % of this area

Black and greenish-gray shale

Borden Group (Mississippian) at surface, covers 14 % 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

Wabash Formation (Silurian) at surface, covers 8 % of this area

Limestone, dolomite, and argillaceous dolomite

Pleasant Mills Formation (Silurian) at surface, covers 0.5 % of this area

Dolomite, limestone, and argillaceous dolomite