Geologic units in Ottawa county, Michigan

Marshall Sandstone (Mississippian) at surface, covers 52 % of this area

Marshall Sandstone

Michigan Formation (Mississippian) at surface, covers 25 % of this area

Michigan Formation

Coldwater Shale (Mississippian) at surface, covers 23 % of this area

Coldwater Shale

Bayport Limestone (Mississippian) at surface, covers 0.2 % of this area

Bayport Limestone