Geologic units in Crawford county, Arkansas

Atoka Formation, undivided (Middle Pennsylvanian- Atokan) at surface, covers 75 % of this area

Atoka Formation, undivided

Alluvium (Holocene) at surface, covers 11 % of this area

Alluvial deposits of present streams

McAlester Formation (Middle Pennsylvanian- Des Moinesian) at surface, covers 5 % of this area

McAlester Formation

Bloyd Shale, and Prairie Grove Member of the Hale Formation (Middle Pennsylvanian- Morrowan) at surface, covers 4 % of this area

Bloyd Shale, and Prairie Grove Member of the Hale Formation

Savanna Formation (Late Pennsylvanian- Des Moinesian) at surface, covers 2 % of this area

Savanna Formation

Terrace deposits (Late Pleistocene) at surface, covers 1.0 % of this area

Alluvial deposits on one or more terrace levels

Pitkin Limestone, Fayetteville Shale (including the Wedington Sandstone member), and Batesville Sandstone (including the Hindsville Limestone Member) (Late Mississippian- Chesterian) at surface, covers 0.6 % of this area

Pitkin Limestone, Fayetteville Shale (including the Wedington Sandstone member), and Batesville Sandstone (including the Hindsville Limestone Member)

Cane Hill Member of Hale Formation (Early Pennsylvanian- Morrowan) at surface, covers 0.5 % of this area

Cane Hill Member of Hale Formation

Harthshorne Sandstone (Middle Pennsylvanian- Des Moinesian) at surface, covers 0.4 % of this area

Harthshorne Sandstone

Atoka Formation (Middle Pennsylvanian) at surface, covers 0.2 % of this area

TULSA- IPat "Atoka Formation," shale, siltstone, sandstone, and thin limestone. FORT SMITH- IPat "Atoka Formation," shale and sandstone. ARDMORE-SHERMAN- Shale, dark-gray, and sandstone, buff to white, fine- to coarse-grained, with some chert conglomerates; thickness, 800 to 3,000 feet. McALESTER TEXARKANA- Shale, gray to tan, illitic, chloritic, with many sandstones, fine- to coarse-grained, quartzose, micaceous, well- to poorly sorted; "Fanshawe" and "Red Oak Sandstones" in middle and "Spiro Sandstone" at base; thickness, 3,000 to 10,000 feet, increasing southeastward in subsurface, south of growth faults.

Bloyd and Hale Formations (Early Pennsylvanian) at surface, covers < 0.1 % of this area

TULSA- "Bloyd Formation," limestone and shale. "Hale Formation," limestone and sandstone. FORT SMITH- IPbh "Bloyd Formation," shale and limestone; and "Hale Formation," limestone and sandstone.

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.