Geologic units in Allen county, Indiana

Muscatatuck Group (Devonian) at surface, covers 73 % of this area: Muscatatuck Group - Limestone and dolomite
Lithology: limestone; dolostone (dolomite)
Detroit River Group (Devonian) at surface, covers < 0.1 % of this area: Detroit River Group - Dolomite; brown to gray; medium to thick bedded; laminated; nodules or interbeds of anhydrite and/or gypsum; basal part becomes sandy dolomite or fine-grained sandstone; as much as 170 feet thick.
Lithology: dolostone (dolomite); evaporite; sandstone
Antrim Shale (Devonian) at surface, covers 11 % of this area: Antrim Shale - Black shale; gray shale and limestone in lower part
Lithology: black shale; shale; limestone
Salina Group (Silurian) at surface, covers < 0.1 % of this area: Salina Group - Dolomite, gray, yellow-gray to olive-gray, laminated to thin bedded; occasional thin bed and laminae of dark gray shale and anhydrite and/or gypsum; brecciated zones in part.
Lithology: dolostone (dolomite); shale; evaporite
Wabash Formation (Silurian) at surface, covers 16 % of this area: Wabash Formation - Limestone, dolomite, and argillaceous dolomite
Lithology: limestone; dolostone (dolomite)