Geologic units in Webster county, Mississippi

Wilcox formation (Eocene) at surface, covers 73 % of this area

Irregularly bedded fine to coarse sand, more or less lignitic clay and lignite; includes bauxite bearing Fearn Springs sand member at base.

Naheola formation (Paleocene) at surface, covers 20 % of this area

(Midway group), Fine to coarse micaceous sand, kaolin, and bauxitic clay.

Porters Creek formation (Paleocene) at surface, covers 7 % of this area

(Midway group), Dark-gray clay, north of Clay County contains slightly glauconitic, micaceous sand lenses.