Geologic units in Cheboygan county, Michigan

Traverse Group (Middle Devonian) at surface, covers 45 % of this area

Traverse Group

Detroit River Group (Middle Devonian) at surface, covers 25 % of this area

Detroit River Group

Antrim Shale (Late Devonian) at surface, covers 17 % of this area

Antrim Shale

Dundee Limestone (Middle Devonian) at surface, covers 6 % of this area

Dundee Limestone

Bois Blanc Formation (Early Devonian) at surface, covers 6 % of this area

Bois Blanc Formation

Bell Shale (Middle Devonian) at surface, covers 2 % of this area

Bell Shale