Geologic units in Charlevoix county, Michigan

Antrim Shale (Late Devonian) at surface, covers 35 % of this area: Antrim Shale
Lithology: black shale; limestone
Bois Blanc Formation (Early Devonian) at surface, covers 8 % of this area: Bois Blanc Formation
Lithology: limestone; dolostone (dolomite)
Traverse Group (Middle Devonian) at surface, covers 34 % of this area: Traverse Group
Lithology: limestone; shale
Detroit River Group (Middle Devonian) at surface, covers 8 % of this area: Detroit River Group
Lithology: dolostone (dolomite); limestone; sandstone
Ellsworth Shale (Late Devonian) at surface, covers 14 % of this area: Ellsworth Shale
Lithology: shale; siltstone; sandstone
Point Aux Chenes Shale (Late Silurian) at surface, covers 0.5 % of this area: Point Aux Chenes Shale
Lithology: shale