Geologic units in Huron county, Michigan

Marshall Sandstone (Mississippian) at surface, covers 37 % of this area

Marshall Sandstone

Coldwater Shale (Mississippian) at surface, covers 27 % of this area

Coldwater Shale

Michigan Formation (Mississippian) at surface, covers 27 % of this area

Michigan Formation

Bayport Limestone (Mississippian) at surface, covers 7 % of this area

Bayport Limestone

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

Saginaw Formation

Sunbury Shale (Mississippian-Devonian) at surface, covers 0.2 % of this area

Sunbury Shale

Ellsworth Shale (Late Devonian) at surface, covers < 0.1 % of this area

Ellsworth Shale