Geologic units in Knox county, Illinois

Carbondale Formation (Pennsylvanian (Moscovian to Kasimovian)) at surface, covers 80 % of this area

Carbondale Formation.

Shelburn-Patoka Formations undivided (Pennsylvanian (Kasimovian)) at surface, covers 11 % of this area

Shelburn-Patoka Formations undivided.

Tradewater Formation (Pennsylvanian (Bashkirian to Moscovian)) at surface, covers 9 % of this area

Tradewater Formation

Meppen Limestone, Fern Glen Formation, and Burlington-Keokuk Limestone (Mississippian (Tourniaisian to Visean)) at surface, covers 0.1 % of this area

Meppen Limestone, Fern Glen Formation, and Burlington-Keokuk Limestone.