Yegua Formation
(Middle Eocene) at surface, covers 17 % of this area Yegua Formation
Laredo Formation
(Middle Eocene) at surface, covers 15 % of this area Laredo Formation
Alluvium
(Holocene) at surface, covers 4 % of this area Alluvium
Terrace deposits
(Pleistocene and Holocene) at surface, covers 2 % of this area Terrace deposits
Goliad Formation
(Miocene) at surface, covers 0.6 % of this area Goliad Formation
Uvalde Gravel
(Pliocene to Pleistocene) at surface, covers 0.2 % of this area Uvalde Gravel