Geologic units in Shiawassee county, Michigan

Saginaw Formation (Pennsylvanian) at surface, covers 84 % of this area

Saginaw Formation

Red beds (Jurassic) at surface, covers 5 % of this area

Red beds

Coldwater Shale (Mississippian) at surface, covers 3 % of this area

Coldwater Shale

Michigan Formation (Mississippian) at surface, covers 3 % of this area

Michigan Formation

Grand River Formation (Pennsylvanian) at surface, covers 2 % of this area

Grand River Formation

Marshall Sandstone (Mississippian) at surface, covers 1 % of this area

Marshall Sandstone

Bayport Limestone (Mississippian) at surface, covers 0.7 % of this area

Bayport Limestone