Geologic units in McIntosh county, Oklahoma

Senora Formation (Middle Pennsylvanian) at surface, covers 29 % of this area

TULSA- Shale with thin and lenticular sandstone, minor limestone, and coal. OKLAHOMA CITY- Mainly fine-grained micaceous sandstone and shale locally containing coal beds. Thickness ranges from about 500 to 950 feet. FORT SMITH- Shale, sandstone, and thin coal seams. ARDMORE-SHERMAN- Shale, gray, and light-brown medium-grained sandstone; thickness, 150 to 500 feet, decreasing southwestward. Subdivided into lower sandstone, 350 feet thick, and upper shale, 150 feet thick.

Boggy Formation (Middle Pennsylvanian) at surface, covers 28 % of this area

TULSA- Shale, sandstone, and coal. FORT SMITH- Shale, sandstone, and coal; includes Bluejacket Sandstone Member at base. ARDMORE-SHERMAN- Shale and sandstone, blue-gray to brown, fine- to coarse- grained, with some thin limestone lenses and a coal bed 2.5 feet thick about 400 feet above base. Thickness, 1,250 to 2,800 feet. "Bluejacket Sandstone," IPbj, at base, 8 to 12 feet thick, with 2-foot "Secor coal" 50 feet above top of Bluejacket. (Lower Franks Conglomerate) McALESTER TEXARKANA- Shale, brown, to blue-gray, illitic, chloritic, with many sandstones, fine- to coarse-grained, micaceous, quartzose, moderately to well-indurated, with "Secor coal" about 50 feet above base; thickness, 2,140 to 4,000 feet, increasing eastward.

Terrace Deposits (Pleistocene) at surface, covers 26 % 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.

Stuart Shale (Middle Pennsylvanian) at surface, covers 5 % of this area

OKLAHOMA CITY- Mostly laminated clay shale and minor amounts of silty sandstone. Thickness ranges from 80 to 180 feet. FORT SMITH- Shale and minor sandstone. ARDMORE-SHERMAN- Shale, blue to dark-gray, with some fine- to medium-grained brown sandstones; thickness, 80 to 300 feet, decreasing southwestward. McALESTER TEXARKANA- Shale, blue to dark-gray, with some fine- to medium-grained sandstones; top eroded; lower 20 feet exposed.

Alluvium (Holocene) at surface, covers 4 % 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.

McAlester and Hartshorne Formations (Middle Pennsylvanian) at surface, covers 4 % of this area

TULSA- "McAlester and Hartshorne Formations", shale and some sandstone and coal. FORT SMITH- IPmh "McAlester" and "Hartshorne Formations" (undifferentiated), shale, sandstone, and coal.

Savanna Formation (Middle Pennsylvanian) at surface, covers 2 % of this area

TULSA- "Savanna Formation," shale and thin sandstone, limestone, and coal. FORT SMITH- IPsa "Savanna Formation," shale, sandstone, and coal ARDMORE-SHERMAN- Sandstone and shale, gray to brown, fine- to coarse-grained, cherty, with several thin coal seams near middle; thickness, 1,120 to 1,600 feet (Lower Franks Conglomerate) McALESTER TEXARKANA- Shale, tan to brown, illitic, chloritic, and sandstone, fine-to coarse-grained, micaceous, quartzose, with several thin coal seams in middle, one of which is "Cavanal coal;" thickness, 1,470 to 2,000 feet, increasing eastward.

Atoka Formation (Middle Pennsylvanian) at surface, covers 1 % 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.

Calvin Sandstone (Middle Pennsylvanian) at surface, covers < 0.1 % of this area

OKLAHOMA CITY- Medium-grained, thin-bedded to massive sandstone nd silty shale. Thickness ranges from 230 to about 440 feet. FORT SMITH- Shale and sandstone. ARDMORE-SHERMAN- Sandstone, brown, medium-grained, with some gray shale; thickness, 40 to 320 feet, thinner southward.