Geologic units in Washington county, Indiana

Borden Group (Mississippian) at surface, covers 37 % 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

Blue River Group (Mississippian) at surface, covers 35 % of this area

Mostly micritic, skeletal, and oolitic limestone

Sanders Group (Mississippian) at surface, covers 26 % of this area

Mostly skeletal limestone, cherty in lower part

West Baden Group (Mississippian) at surface, covers 2 % of this area

Shale, sandstone, and micritic and skeletal limestone