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Geologic units in Clay county, Texas

Archer City Formation (Phanerozoic | Paleozoic | Permian [Wolfcamp]) at surface, covers 32 % of this area

Archer City Formation

Petrolia Formation (Phanerozoic | Paleozoic | Permian [Wolfcamp Leonard]) at surface, covers 27 % of this area

Petrolia Formation

Markley Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 14 % of this area

Markley Formation

alluvium (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 10 % of this area

alluvium

Lithology: sand; silt; clay or mud; gravel

Nocona Formation (Phanerozoic | Paleozoic | Permian [Wolfcamp Leonard]) at surface, covers 8 % of this area

Nocona Formation

Terrace deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 5 % of this area

Terrace deposits

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

sand sheet deposits

Lithology: sand; silt

dune sand sheet deposits (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 0.5 % of this area

dune sand sheet deposits

Lithology: sand; silt

Terrace Deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene) at surface, covers < 0.1 % of this area

WOODWARD- Lenticular and interfingering deposits of light-tan to gray gravel, sand, silt, clay, and volcanic ash. Sand dunes are common in many places. Thickness ranges up to 150 feet and averages about 60 feet. ENID- Sand, silt, clay, and gravel. Maximum thickness, about 75 feet (23 m) along major streams. TULSA- Fine gravel, sand, silt, and clay. CLINTON- Stream-laid deposits of sand, silt, clay, gravel, and volcanic ash; thickness ranges from 0 to about 120 feet. OKLAHOMA CITY- Lenticular beds of sand, silt, clay, and gravel. Thickness ranges from a few feet to about 100 feet and probably averages about 50 feet along major streams. FORT SMITH- Gravel, sand, silt, and clay. LAWTON- Sand, clay, and gravel as much as 75 feet (23 m) in Tillman County, ranging from 5 to 50 feet (2 to 15 m) elsewhere. ARDMORE-SHERMAN- Gravel, sand, silt, clay, and volcanic ash; thickness, about 5 to 50 feet; at various levels, as high as 160 feet above present flood plains. McALESTER TEXARKANA- Gravel, sand, silt, clay, and volcanic ash; several levels 20 to 160 feet or more above present flood plains, with each level containing deposits that average 20 to 30 feet in thickness, some windblown sand on top; may include colluvial wash down sides of hills

Lithology: sand; gravel; volcanic ash