Geologic units in Armstrong county, Texas

Blackwater Draw Formation (Pleistocene) at surface, covers 42 % of this area

Blackwater Draw Formation

Ogallala Formation (Pliocene to Miocene) at surface, covers 24 % of this area

Ogallala Formation

Quartermaster Formation (Permian; Guadalupe Series) at surface, covers 17 % of this area

Quartermaster Formation; North and central Texas including panhandle.

Dockum Group, undivided (Late Triassic) at surface, covers 6 % of this area

Dockum Group

Whitehorse Group, undivided (Permian; Guadalupe Series) at surface, covers 5 % of this area

Whitehorse Group, undivided

Lingos Formation (Middle (?) Pleistocene to Recent) at surface, covers 3 % of this area

Lingos Formation

Playa deposits (Pleistocene and Holocene) at surface, covers 2 % of this area

Playa deposits

Alluvium (Holocene) at surface, covers 0.4 % of this area

Alluvium

Terrace deposits (Pleistocene and Holocene) at surface, covers 0.4 % of this area

Terrace deposits

Quaternary deposit, undivided (Quaternary) at surface, covers 0.1 % of this area

Quaternary deposit, undivided