Geologic units in Sangamon county, Illinois

Shelburn-Patoka Formations undivided (Pennsylvanian (Kasimovian)) at surface, covers 82 % of this area

Shelburn-Patoka Formations undivided.

Bond Formation (Pennsylvanian (Kasimovian)) at surface, covers 16 % of this area

Bond Formation

Carbondale Formation (Pennsylvanian (Moscovian to Kasimovian)) at surface, covers 3 % of this area

Carbondale Formation.