Geologic units in Lamar county, Texas

Bonham Formation (Late Cretaceous; Gulfian Series) at surface, covers 23 % of this area

Bonham Formation

Ozan Formation (Late Cretaceous; Gulfian Series) at surface, covers 14 % of this area

Ozan Formation

Eagle Ford Formation (Late Cretaceous) at surface, covers 12 % of this area

Eagle Ford Formation

Alluvium (Holocene) at surface, covers 12 % of this area

Alluvium

Brownstown Marl (Late Cretaceous; Gulfian Series) at surface, covers 8 % of this area

Brownstown Marl

Terrace deposits (Pleistocene and Holocene) at surface, covers 8 % of this area

Terrace deposits

Blossom Sand (Late Cretaceous; Gulfian Series) at surface, covers 7 % of this area

Blossom Sand

Gober Chalk and Roxton Limestone (Late Cretaceous; Gulfian Series) at surface, covers 7 % of this area

Gober Chalk and Roxton Limestone

Marlbrook Marl (Late Cretaceous; Gulfian Series) at surface, covers 4 % of this area

Marlbrook Marl

Pecan Gap Chalk (Late Cretaceous; Gulfian Series) at surface, covers 2 % of this area

Pecan Gap Chalk

Wolfe City Formation (Late Cretaceous; Gulfian Series) at surface, covers 2 % of this area

Wolfe City Formation

Woodbine Formation (Late Cretaceous; Gulfian Series) at surface, covers 1 % of this area

Woodbine Formation

Alluvium (Holocene) at surface, covers < 0.1 % of this area

WOODWARD- Lenticular and interfingering deposits of gravel, sand, silt, and clay. Generally light-tan to gray. Thickness along major streams ranges up to 100 feet and probably averages 40 feet; along minor streams the thickness ranges up to 45 feet and probably averages 20 feet. ENID- Sand, silt, clay, and locally gravel. Maximum thickness ranges from 30 to 80 feet (9 to 24 m) along major streams and from 0 to 60 feet (0 to 18 m) along minor streams. TULSA- Gravel, sand, silt, and clay. TULSA- Gravel, sand, silt, and clay. OKLAHOMA CITY- Sand, silt, clay, and lenticular beds of gravel. Thickness ranges from about 30 to 100 feet and probably averages about 50 feet along major streams. Along minor streams, thickness ranges from a few feet to about 50 feet and probably averages about 25 feet. LAWTON- Sand, clay, and gravel as much as 50 feet (15 m) thick; Shown only along major streams and tributaries. ARDMORE-SHERMAN- Gravel, sand, silt, and clay, including low terraces; thickness, about 25 to 100 feet. McALESTER TEXARKANA- Gravel, sand, silt, and clay, including low terraces about 30 feet above channels; thickness, about 50 feet along Little River and 110 feet along Red River.

Navarro Group, undivided (Late Cretaceous; Gulfian Series) at surface, covers < 0.1 % of this area

Navarro Group, undivided

Terrace Deposits (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.

Woodbine Formation (Late Cretaceous) at surface, covers < 0.1 % of this area

McALESTER TEXARKANA- Sand, dark-green, yellowish-red, white, gray, fine- to coarse-grained, tuffaceous in upper part; crossbedded, quartzose, and brownish-red noncalcareous clay; some gravel lentils with little to no quartz and some lignites and fossil plants; rests unconformably upon successively older Cretaceous units eastward; thickness, 325 to 455 feet, increasing eastward.