Geologic units in Cimarron county, Oklahoma

Ogallala Formation (Pliocene) at surface, covers 61 % 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.

Dune Sand (Pleistocene) at surface, covers 16 % of this area

CIMARRON- Fine- to medium-grained sand 0 to 40 feet thick. TEXAS- Fine to coarse windblown sand. Maximum thickness about 30 feet. BEAVER- Fine to coarse, round to sub-round, windblown sand consisting mostly of quartz grains. 0-50 feet thick.

Dakota Sandstone (Early Cretaceous) at surface, covers 10 % of this area

CIMARRON- Buff to light-brown, fine- to medium-grained, thin bedded to massive sandstone with interbedded shales.

Morrison Formation (Late Jurassic) at surface, covers 4 % of this area

CIMARRON- Varicolored fine-grained sandstone, limestone, dolomite, shale, and conglomerate 0 to 470 +/- feet thick.

Alluvium (Holocene) at surface, covers 3 % of this area

CIMARRON- Clay, silt, sand, and gravel 0 to 100 feet thick. TEXAS- Sand, silt, clay, and gravel located in valleys of principal streams. Thickness not known but may exceed 100 feet in North Canadian River valley and may be 50 to 100 feet in lower parts of valleys of Coldwater and Palo Duro Creeks BEAVER - Sand, gravel, silt, and clay in discontinuous lenses along courses of larger streams. 0-50 feet thick.

Purgatoire Formation (Early Cretaceous) at surface, covers 3 % of this area

CIMARRON- Kiowa Shale Member: Gray to black fossiliferous shale with sandstone in the upper part. Thickness ranges from 0 to 50 +/- feet. Cheyenne Sandstone Member: Massive, white to buff, fine- to medium-grained sandstone, containing some conglomerate in the lower part, from 0 to 120 +/- feet thick.

Dockum Group (Late Triassic) at surface, covers 1 % of this area

CIMARRON- Upper shale unit: Varicolored siltstone or claystone, conglomerate, fine-grained sandstone, and limestone. Lower sandstone unit: Varicolored, fine- to coarse-grained sandstone with some clay and interbedded shale.

Colorado Group (Early Cretaceous) at surface, covers 0.9 % of this area

CIMARRON- includes: Greenhorn Limestone: Gray fossiliferous limestone and calcareous shale. Graneros Shale: Dark-gray shale.

Exeter (Entrada) Sandstone (Late Jurassic) at surface, covers 0.4 % of this area

CIMARRON- Massive, white to buff, fine- to medium-grained sandstone 0 to 50 +/- feet thick.

Pleistocene and Pliocene deposits, undifferentiated (Pleistocene to Pliocene) at surface, covers < 0.1 % of this area

TEXAS- Interfingering beds, tongues, and lenses of sand, silt, clay, gravel, sandstone, caliche, limestone, conglomerate, and volcanic ash. Includes Ogallala and Laverne Formations of Pliocene age and younger deposits of Pleistocene age. Locally the units are tightly cemented by calcium carbonate; other places, they are very poorly consolidated and nearly free of cementing materials. Thickness ranges from 0 to about 800 feet.

Basalt (Pliocene) at surface, covers < 0.1 % of this area

CIMARRON- Dark, dense to vesicular volcanic rock 50 to 85 +/- feet thick forming cap rock of Black Mesa.

Ogallala Fm (Tertiary) at surface, covers < 0.1 % of this area

Loose to well-cemented sand and gravel

Eolian deposits (Quaternary) at surface, covers < 0.1 % of this area

Includes dune sand and silt and Peoria Loess

Dakota Sandstone and Purgatoire Fm (Cretaceous) at surface, covers < 0.1 % of this area

Sandstone and shale

Dockum Group (Triassic) at surface, covers < 0.1 % of this area

Red sandstone, siltstone, and local limestone

Morrison, Ralston Creek, and Entrada (or Exeter) Fms (Jurassic) at surface, covers < 0.1 % of this area

Morrison, Ralston Creek, and Entrada (or Exeter) Fms

Blackwater Draw Formation (Pleistocene) at surface, covers < 0.1 % of this area

Blackwater Draw Formation