Geologic units in Randall county, Texas

alluvium (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 0.7 % of this area: alluvium
Lithology: sand; silt; clay or mud; gravel
Dockum Group, undivided (Phanerozoic | Mesozoic | Triassic-Late) at surface, covers 3 % of this area: Dockum Group
Lithology: fine-grained mixed clastic; limestone; conglomerate
Blackwater Draw Formation (Phanerozoic | Cenozoic | Quaternary | Pleistocene) at surface, covers 76 % of this area: Blackwater Draw Formation
Lithology: sand; silt; clay or mud
unnamed Pliocene deposits (Phanerozoic | Cenozoic | Tertiary | Pliocene) at surface, covers 3 % of this area: unnamed Pliocene deposits
Lithology: sand; gravel; silt
Quartermaster Formation (Phanerozoic | Paleozoic | Permian [Guadalupe]) at surface, covers 1 % of this area: Quartermaster Formation
Lithology: shale; sandstone; evaporite; dolostone (dolomite)
Ogallala Formation (Phanerozoic | Cenozoic | Tertiary | Pliocene Miocene) at surface, covers 14 % of this area: Ogallala Formation
Lithology: sand; silt; clay or mud; gravel; carbonate
sand dune deposits (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers < 0.1 % of this area: sand dune deposits
Lithology: sand; silt
playa deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 2 % of this area: playa deposits
Lithology: clay or mud; silt