Geologic units in Martin county, Indiana

Raccoon Creek Group (Pennsylvanian) at surface, covers 67 % of this area

Mostly shale and sandstone; also includes thin beds of limestone, clay, and coal. B, Buffaloville Coal Member; LB, Lower Block Coal Member

Stephensport Group (Mississippian) at surface, covers 20 % of this area

Sandstone, micritic and skeletal limestone, and shale

West Baden Group (Mississippian) at surface, covers 11 % of this area

Shale, sandstone, and micritic and skeletal limestone

Blue River Group (Mississippian) at surface, covers 2 % of this area

Mostly micritic, skeletal, and oolitic limestone