Geologic units in Madison county, Texas

Yegua Formation (Middle Eocene) at surface, covers 61 % of this area

Yegua Formation

Alluvium (Holocene) at surface, covers 17 % of this area

Alluvium

Cook Mountain Formation (Eocene) at surface, covers 15 % of this area

Cook Mountain Formation

Terrace deposits (Pleistocene and Holocene) at surface, covers 4 % of this area

Terrace deposits

Deweyville Formation (Quaternary; Pleistocene and Holocene?) at surface, covers 2 % of this area

Deweyville Formation

High gravel deposits (Pleistocene) at surface, covers 2 % of this area

High gravel deposits

Wellborn Formation (Eocene) at surface, covers < 0.1 % of this area

Wellborn Formation