Geologic units in Roscommon county, Michigan

Michigan Formation (Mississippian) at surface, covers 48 % of this area

Michigan Formation

Saginaw Formation (Pennsylvanian) at surface, covers 36 % of this area

Saginaw Formation

Marshall Sandstone (Mississippian) at surface, covers 7 % of this area

Marshall Sandstone

Bayport Limestone (Mississippian) at surface, covers 6 % of this area

Bayport Limestone

Red beds (Jurassic) at surface, covers 2 % of this area

Red beds

Coldwater Shale (Mississippian) at surface, covers 0.4 % of this area

Coldwater Shale