Geologic units in Marshall county, Illinois

Shelburn-Patoka Formations undivided (Pennsylvanian (Kasimovian)) at surface, covers 45 % of this area

Shelburn-Patoka Formations undivided.

Carbondale Formation (Pennsylvanian (Moscovian to Kasimovian)) at surface, covers 32 % of this area

Carbondale Formation.

Mattoon Formation (Pennsylvanian (Kasimovian)) at surface, covers 15 % of this area

Mattoon Formation.

Bond Formation (Pennsylvanian (Kasimovian)) at surface, covers 9 % of this area

Bond Formation