Ogallala Formation
(Pliocene to Miocene) at surface, covers 27 % of this area Ogallala Formation
Tecovas Formation
(Late Triassic) at surface, covers 22 % of this area Tecovas Formation
Trujillo Formation
(Late Triassic) at surface, covers 20 % of this area Trujillo Formation
Chinle Formation
(Late Triassic) at surface, covers 4 % of this area Chinle Formation
Alluvium
(Holocene) at surface, covers 1 % of this area Alluvium
Terrace deposits
(Pleistocene and Holocene) at surface, covers 1 % of this area Terrace deposits
Playa deposits
(Pleistocene and Holocene) at surface, covers 0.3 % of this area Playa deposits
Caliche deposits
(Pleistocene and Holocene) at surface, covers 0.2 % of this area Caliche deposits