Geologic units in Martin county, Texas

Blackwater Draw Formation (Pleistocene) at surface, covers 75 % of this area

Blackwater Draw Formation

Ogallala Formation (Pliocene to Miocene) at surface, covers 7 % of this area

Ogallala Formation

Sand sheet deposits (Holocene) at surface, covers 5 % of this area

Sand sheet deposits

Tahoka Formation (Pleistocene; Wisconsinan) at surface, covers 4 % of this area

Tahoka Formation

Pond deposits (Pleistocene) at surface, covers 4 % of this area

Pond deposits

Dockum Group, undivided (Late Triassic) at surface, covers 2 % of this area

Dockum Group

Caliche deposits (Pleistocene and Holocene) at surface, covers 1 % of this area

Caliche deposits

Quaternary deposit, undivided (Quaternary) at surface, covers 1 % of this area

Quaternary deposit, undivided

Antlers Sand (Early Cretaceous) at surface, covers 0.9 % of this area

Antlers Sand

Edwards Limestone (Early Cretaceous) at surface, covers 0.3 % of this area

Edwards Limestone

Playa deposits (Pleistocene and Holocene) at surface, covers 0.2 % of this area

Playa deposits

Alluvium (Holocene) at surface, covers 0.2 % of this area

Alluvium

Sand dune deposits (Holocene) at surface, covers < 0.1 % of this area

Sand dune deposits

Sand deposits, undivided (Holocene) at surface, covers < 0.1 % of this area

Sand deposits, undivided