Geologic units in Coles county, Illinois

Mattoon Formation (Pennsylvanian (Kasimovian)) at surface, covers 66 % of this area

Mattoon Formation.

Shelburn-Patoka Formations undivided (Pennsylvanian (Kasimovian)) at surface, covers 24 % of this area

Shelburn-Patoka Formations undivided.

Bond Formation (Pennsylvanian (Kasimovian)) at surface, covers 10 % of this area

Bond Formation

Carbondale Formation (Pennsylvanian (Moscovian to Kasimovian)) at surface, covers < 0.1 % of this area

Carbondale Formation.