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Geologic units in Dallam county, Texas

sand sheet deposits (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 55 % of this area

sand sheet deposits

Lithology: sand; silt

Ogallala Formation (Phanerozoic | Cenozoic | Tertiary | Pliocene Miocene) at surface, covers 23 % of this area

Ogallala Formation

Blackwater Draw Formation (Phanerozoic | Cenozoic | Quaternary | Pleistocene) at surface, covers 18 % of this area

Blackwater Draw Formation

Lithology: sand; silt; clay or mud

dune sand sheet deposits (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 2 % of this area

dune sand sheet deposits

Lithology: sand; silt

alluvium (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 0.7 % of this area

alluvium

Lithology: sand; silt; clay or mud; gravel

playa deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 0.3 % of this area

playa deposits

Lithology: clay or mud; silt

Terrace deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 0.2 % of this area

Terrace deposits

sand dune deposits (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 0.2 % of this area

sand dune deposits

Lithology: sand; silt

Ogallala Formation (Phanerozoic | Cenozoic | Tertiary | Pliocene) at surface, covers 0.1 % of this area

CIMARRON- Generally semiconsolidated clay, silt, sand, gravel, and caliche 0 to 400 feet thick. BEAVER- Interbedded sand, siltstone, clay, gravel lenses, and thin limestone. Caliche common near surface but occurrence is not limited to the surface. Caliche accounts for most of the white color in the Ogallala. Other colors generally light tan or buff but locally may be pastel shades of almost any color. The Laverne and Rexroad Formations of Pliocene age and the Meade Group and Odee (of local usage) and other formations of Pleistocene age occur locally and are included with the Ogallala Formation, 0-700 feet thick. WOODWARD- Gravel, sand, silt, clay, caliche, and limestone, locally cemented with calcium carbonate. Generally light-tan to gray to white. Thickness ranges up to 400 feet and probably averages 150 feet. CLINTON- Gray to light-brown, fine- to medium-grained sand with some, clay, silt, gravel, volcanic ash, and caliche beds; locally cemented by calcium carbonate. Thickness ranges from 0 to about 320 feet. The formation thins eastward.

Morrison Formation (Phanerozoic | Mesozoic | Jurassic-Late) at surface, covers < 0.1 % of this area

Morrison Formation

Lithology: shale; sandstone

Dakota and Purgatoir Formations, undivided (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers < 0.1 % of this area

Dakota and Purgatoir Formations, undivided

Lithology: sandstone; shale; coal

eolian deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area

Eolian deposits

Lithology: eolian

Dakota Formation (Phanerozoic | Mesozoic | Cretaceous-Early Cretaceous-Late) at surface, covers < 0.1 % of this area

Dakota Formation

Lithology: sandstone; shale; coal