Geologic units in Piatt county, Illinois

Bond Formation (Pennsylvanian (Kasimovian)) at surface, covers 57 % of this area

Bond Formation

Mattoon Formation (Pennsylvanian (Kasimovian)) at surface, covers 27 % of this area

Mattoon Formation.

Shelburn-Patoka Formations undivided (Pennsylvanian (Kasimovian)) at surface, covers 14 % of this area

Shelburn-Patoka Formations undivided.

Tradewater Formation (Pennsylvanian (Bashkirian to Moscovian)) at surface, covers 1 % of this area

Tradewater Formation

Carbondale Formation (Pennsylvanian (Moscovian to Kasimovian)) at surface, covers 0.9 % of this area

Carbondale Formation.