Geologic units in Arkansas (state in United States)

Additional scientific data in this geographic area

Terrace deposits (Late Pleistocene) at surface, covers 19 % of this area

Alluvial deposits on one or more terrace levels

Alluvium - Alluvial deposits of local streams or of overbank flow of major streams (Holocene) at surface, covers 9 % of this area

Alluvial deposits of local streams or of overbank flow of major streams - In some areas includes deposits in abandoned meanders of major streams

Alluvium (Holocene) at surface, covers 8 % of this area

Alluvial deposits of present streams

Atoka Formation, undivided (Middle Pennsylvanian- Atokan) at surface, covers 6 % of this area

Atoka Formation, undivided

Alluvium - Alluvial deposits in major stream channels or in mappable meanders of major streams (Holocene) at surface, covers 6 % of this area

Alluvial deposits in major stream channels or in mappable meanders of major streams - Includes alluvial deposits in natural levees in some areas.

Boone Formation (Early Mississippian- Meramecian to Osagean) at surface, covers 5 % of this area

Boone Formation

Claibourne Group (Middle Eocene) at surface, covers 5 % of this area

Claibourne Group

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

Cotter and Jefferson City Dolomites (Early Ordovician) at surface, covers 4 % of this area

Cotter and Jefferson City Dolomites

Stanley Shale (Early Mississippian) at surface, covers 4 % of this area

Stanley Shale - Includes Chickasaw Creek Chert equivalent of Harlton (1938) near top and Hatton Tuff Lentil and Hot Springs Sandstone Member near base

Atoka Formation - Upper part (Middle Pennsylvanian- Atokan) at surface, covers 3 % of this area

Atoka Formation - Upper part

Wilcox Group (Early Eocene) at surface, covers 2 % of this area

Wilcox Group

St. Peter Sanstone and Everton Formation (Middle Ordovician) (Middle Ordovician) at surface, covers 2 % of this area

St. Peter Sanstone and Everton Formation (Middle Ordovician)

Atoka Formation - Lower part (Middle Pennsylvanian- Atokan) at surface, covers 2 % of this area

Atoka Formation - Lower part

Jackfork Sandstone (Early Pennsylvanian- Morrowan) at surface, covers 2 % of this area

Jackfork Sandstone

Atoka Formation - Middle part (Middle Pennsylvanian- Atokan) at surface, covers 2 % of this area

Atoka Formation - Middle part

Pitkin Limestone, Fayetteville Shale (including the Wedington Sandstone member), and Batesville Sandstone (including the Hindsville Limestone Member) (Late Mississippian- Chesterian) at surface, covers 2 % of this area

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

Jackson Group (Late Eocene) at surface, covers 2 % of this area

Jackson Group

Cane Hill Member of Hale Formation (Early Pennsylvanian- Morrowan) at surface, covers 1 % of this area

Cane Hill Member of Hale Formation

Powell Dolomite (Early Ordovician) at surface, covers 1 % of this area

Powell Dolomite

McAlester Formation (Middle Pennsylvanian- Des Moinesian) at surface, covers 1 % of this area

McAlester Formation

Womble Shale (Middle Ordovician) (Middle Ordovician) at surface, covers 0.9 % of this area

Womble Shale (Middle Ordovician)

Harthshorne Sandstone (Middle Pennsylvanian- Des Moinesian) at surface, covers 0.8 % of this area

Harthshorne Sandstone

Dune sand (Late Pleistocene) at surface, covers 0.7 % of this area

Deposited mostly on terrace deposits of the second level. Younger than some terrace deposits, older than others

Silt and sand (Early Pleistocene) at surface, covers 0.7 % of this area

Contains lenses of gravel and clay

Savanna Formation (Late Pennsylvanian- Des Moinesian) at surface, covers 0.6 % of this area

Savanna Formation

Arkansas Novaculite (Early Mississippian to Late Devonian) at surface, covers 0.6 % of this area

Includes upper division (Mississippian), middle division (Mississippian and Devonian), and lower division (Devonian)

Midway Group (Paleocene) at surface, covers 0.5 % of this area

Midway Group

Pole Creek Shale (Upper Ordovician) and Bigfork Chert (Upper and Middle Ordovician) (Late Ordovician to Middle Ordovician) at surface, covers 0.5 % of this area

Polk Creek Shale (Upper Ordovician) and Bigfork Chert (Upper and Middle Ordovician)

Cason Shale and Fernvale Limestone (Upper Ordovician) and Kimmswick Limestone, Plattin Limestone, and Joachim Dolomite (Middle Ordovician) (Late Ordovician to Middle Ordovician) at surface, covers 0.5 % of this area

Cason Shale and Fernvale Limestone (Upper Ordovician) and Kimmswick Limestone, Plattin Limestone, and Joachim Dolomite (Middle Ordovician)

Tokio Formation (Late Cretaceous) at surface, covers 0.4 % of this area

Tokio Formation

Trinity Group (Early Cretaceous) at surface, covers 0.4 % of this area

Trinity Group

Johns Valley Shale (Early Pennsylvanian- Morrowan) at surface, covers 0.4 % of this area

Johns Valley Shale

Nacatoch Sand (Late Cretaceous) at surface, covers 0.4 % of this area

Nacatoch Sand

Loess (Early Pleistocene) at surface, covers 0.3 % of this area

Loess

Missouri Mountain Shale and Baylock Sandstone (Late Silurian) at surface, covers 0.3 % of this area

The Baylock Sandstone is present only in the Cross, Cossatot, and Trap Mountains. Missouri Mountain Shale is mapped with Polk Creek Shale and Bigfork Chert in the area between Paron, Saline County, and Little Rock.

Mazarn Shale (Early Ordovician) at surface, covers 0.2 % of this area

Mazarn Shale

Arkadelphia Marl (Late Cretaceous) at surface, covers 0.2 % of this area

Arkadelphia Marl

Brownstown Marl (Late Cretaceous) at surface, covers 0.2 % of this area

Brownstown Marl

Blakely Sandstone (Middle and Lower Ordovician) (Middle Ordovician to Early Ordovician) at surface, covers 0.2 % of this area

Blakely Sandstone (Middle and Lower Ordovician)

Chattanooga Shale (Lower Mississippian and Upper Devonian), Clifty Limestone (Middle Devonian), and Penters Chert (Lower Devonian) (Early Mississippian to Early Devonian) at surface, covers 0.2 % of this area

Chattanooga Shale (Lower Mississippian and Upper Devonian), Clifty Limestone (Middle Devonian), and Penters Chert (Lower Devonian)

Woodbine Formation (Late Cretaceous) at surface, covers 0.2 % of this area

Woodbine Formation

Alluvium and terrace deposits (Holocene to Pleistocene) at surface, covers 0.1 % of this area

Alluvial deposits of present streams and on one or more terrace levels

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

Ozan Formation

Ruddell Shale (Late Mississippian- Chesterian) at surface, covers 0.1 % of this area

Ruddell Shale

Marlbrook Marl (Late Cretaceous) at surface, covers 0.1 % of this area

Marlbrook Marl

Cretaceous rocks (Cretaceous) at surface, covers 0.1 % of this area

Cretaceous rocks

Sand and gravel (Early Pleistocene) at surface, covers < 0.1 % of this area

Sand and gravel

Moorefield Formation (Late Mississippian- Meramecian) at surface, covers < 0.1 % of this area

Moorefield Formation

Sand and clay (Cretaceous) at surface, covers < 0.1 % of this area

Sand and clay

Crystal Mountain Sandstone (Early Ordovician) at surface, covers < 0.1 % of this area

Crystal Mountain Sandstone

Sartoga Chalk (Late Cretaceous) at surface, covers < 0.1 % of this area

Sartoga Chalk

De Queen Limestone (Early Cretaceous) at surface, covers < 0.1 % of this area

De Queen Limestone

Collier Shale (Early Ordovician) at surface, covers < 0.1 % of this area

Collier Shale

Dierks Limestone (Early Cretaceous) at surface, covers < 0.1 % of this area

Dierks Limestone

Igneous rocks (Cretaceous) at surface, covers < 0.1 % of this area

Includes undifferentiated altered sedimentary rocks of Paleozoic age at Granite Mountain, Pulaski County, and Mufreesboro, Pike County. Acid to intermediate - Nepheline syenite complexes at Magnet Cove and Potash Sulfur Springs, stocks at Granite Mtn., explosion breccias, and dikes and sills (principally trachyte,tinguaite, phonolite, some ranging from syenite to diabase). Basic to ultrabasic - Lamproite pipes (Murfreesboro, Pike County) and dikes and sills (principally lamprophyres of fourchite, ouachitite, and monchiquite).

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

Loam, sand, gravel, and clay; mapped only in Mississippi River Alluvial Plain.

Lafferty, St. Clair and Brassfield Limestones (Late Silurian to Early Silurian) at surface, covers < 0.1 % of this area

Lafferty, St. Clair and Brassfield Limestones

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

Gravel on isolated hills within 40 miles (64km) of the Mississippi Embayment. Many small deposits to the west not shown

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

Sand, silt, clay, and gravel. In flood plain of Mississippi River more than 100 feet thick; in smaller streams generally less than 20 feet thick.

Annona Chalk (Late Cretaceous) at surface, covers < 0.1 % of this area

Annona Chalk

Stanley Group or Stanley Shale (Mississippian) at surface, covers < 0.1 % of this area

ARDMORE-SHERMAN- "Stanley Shale"- Shale, dark-gray, siliceous,with some gray to buff fine-grained sandstones; thickness,10,000 feet Occurs in the OUACHITA MNTS. McALESTER TEXARKANA- "Stanley Group"- Shale, olive-green to gray, illitic, chloritic, with many5- to 30-foot-thick beds of poorly sorted, micaceous, quartzose sandstones and some thin siliceous cherty beds and black shales; several tuff beds occur in basal 1,000 feet and are indicated by red line in Stanley exposures as designated on map; many asphaltite, lead, and quartz veins occur along fault zones; mostly Chesterian age; thickness, 7,500 to 14,000 feet or more. Occurs in the OUACHITA MTNS SOUTH OF TI VALLEY FAULT.

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

Alluvium

Holocene series (Quaternary-Holocene Series) at surface, covers < 0.1 % of this area

Alluvium - clay, silt, sand, and gravel.

Terrace deposits (Pleistocene and Holocene) at surface, covers < 0.1 % of this area

Terrace deposits

Atoka Formation (Middle Pennsylvanian) at surface, covers < 0.1 % 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.

Boggy Formation (Late Pennsylvanian- Des Moinesian) at surface, covers < 0.1 % of this area

Boggy Formation

Queen City Sand (Eocene) at surface, covers < 0.1 % of this area

Queen City Sand

Jackfork Group or Jackfork Sandstone (Early Pennsylvanian) at surface, covers < 0.1 % of this area

ARDMORE-SHERMAN- "Jackfork Sandstone"- Sandstone, gray, white, and tan, coarse-grained, cherty, with gray shale and some boulders up to 7 feet in diameter; thickness 1,150 to 5,000 feet Occurs in the OUACHITA MNTS. McALESTER TEXARKANA- "Jackfork Group"- Sandstone, tan to gray, fine- to coarse-grained, quartzose, with some mica, poorly to well-indurated, quartzitic has some gray shale and several maroon shales; black, white-speckled "Chickasaw Creek Chert" is at base; thickness, 1,500 to 6,000 feet or more. Occurs in the OUACHITA MTNS SOUTH OF TI VALLEY FAULT.

Kiamichi Formation and Goodland Limestone (Early Cretaceous) at surface, covers < 0.1 % of this area

Kiamichi Formation and Goodland Limestone

Wilcox Group, undivided (Paleocene to Eocene) at surface, covers < 0.1 % of this area

Wilcox Group, undivided

Osagean Series (Early Mississippian-Osagean Series) at surface, covers < 0.1 % of this area

Keokuk Limestone, Burlington Limestone, Elsey Formation, Reeds Spring Formation, Pierson Limestone, Fern Glen Formation.

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

McALESTER TEXARKANA- Sand, light-gray, fine- to coarse-grained, quartzose, poorly sorted, crossbedded, and gray clay shale, with many cylindrical pipe structures, petrified wood and invertebrates; same as Bonham Marl and Austin Chalk of Texas; thickness ranges from 88 to 380 feet, increasing eastward; reaches thickness of 595 feet in subsurface southeastward.

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.

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.

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.

Weches Formation (Eocene) at surface, covers < 0.1 % of this area

Weches Formation

Cockfield Formation (Eocene) at surface, covers < 0.1 % of this area

Brown lignitic clays, silts and sands; some sideritic glauconite may weather to brown ironstone in lower part.

Smithville Dolomite, Powell Dolomite, Cotter Dolomite, Jefferson City Dolomite (Early Ordovician-Ibexian Series) at surface, covers < 0.1 % of this area

Fine crystalline, silty, cherty dolomite, and oolitic chert with local sandstone beds.

Reklaw Formation (Eocene) at surface, covers < 0.1 % of this area

Reklaw Formation

Pitkin + Fayetteville + Hindsville + Moorefield Formations (Late Mississippian) at surface, covers < 0.1 % of this area

FORT SMITH- Mp "Pitkin Formation," limestone; "Fayetteville Formation," shale and limestone; "Hindsville Formation," limestone and shale; and "Moorefield Formation," limestone.

Keokuk and Reeds Spring Formations and St. Joe Group (Early Mississippian) at surface, covers < 0.1 % of this area

TULSA- "Keokuk Formation," chert and limestone. "Reeds Spring Formation," chert and limestone. "St. Joe Group," limestone and shale. FORT SMITH- Mkr "Keokuk Formation," chert; "Reeds Spring Formation," chert and limestone; and "St. Joe 'Group,'" limestone and marlstone.

Kinderhookian Series (Early Mississippian-Kinderhookian Series) at surface, covers < 0.1 % of this area

Northview Shale, Sedalia Formation, Compton Limestone, Bachelor Formation Chouteau Group, Hannibal Shale, Horton Creek Limestone.

Brownstown Marl (Late Cretaceous) at surface, covers < 0.1 % of this area

McALESTER TEXARKANA- Marl and clay, gray, calcareous, micaceous, sandy and fine-grained sand, with some interbedded chalky limestones; same as upper Austin Chalk of Texas; thickness, about 100 feet.

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.

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

Gray to brownish gray clay and silty clay, reddish brown in the Red River Valley, some sand and gravel locally.

Braided Stream Terraces (Pleistocene) at surface, covers < 0.1 % of this area

Light gray, tan and brown fine to coarse sand; some clay silt and gravel. Overlain by 1-9 meters of loess.

Midway Group, undivided (Paleocene) at surface, covers < 0.1 % of this area

Midway Group, undivided

Holly Creek Formation (Early Cretaceous) at surface, covers < 0.1 % of this area

McALESTER TEXARKANA- Gravel, composed mostly of quartz and novaculite, with clay and silt, tan to red-brown; unconformable on Ouachita rocks; thickness, 30 to 100 feet, thickening to 1,070 feet in subsurface of southern McCurtain County.

Braided Stream Terraces (Pleistocene) at surface, covers < 0.1 % of this area

Light gray, tan and brown fine to coarse sand; some clay silt and gravel.

Arkansas Novaculite (Early Mississippian to Early Silurian) at surface, covers < 0.1 % of this area

McALESTER TEXARKANA- Chert, fine- to very fine-grained, gray, green, tan, black, white, and pink, with interbedded black to gray shale in 1-to 18-inch beds; some interbedded conglomerates and in places a basal conglomerate; upper part has been determined to be Mississippian in age and lower part to be Early Silurian, on basis of examination of palynomorphs from Potato Hills; thickness, 600 feet or more. Occurs in the OUACHITA MTNS SOUTH OF TI VALLEY FAULT.

Lynn Mountain Formation (Early Pennsylvanian) at surface, covers < 0.1 % of this area

McALESTER TEXARKANA- Shale, gray to tan, with many fine- to coarse-grained, quartzose, micaceous sandstone with many bottom markings; top eroded; thickness, 3,000 to 7,000 feet or more; unconformable upon Goddard, Delaware Creek, Woodford, and older beds that are exposed north and west of Ti Valley Fault. Occurs in the OUACHITA MTNS.

Olistoliths of Metagabbro and Soapstone-Serpentine (Paleozoic) at surface, covers < 0.1 % of this area

Olistoliths of Metagabbro and Soapstone-Serpentine - Altered peridotite

Blaylock Sandstone (Early Silurian) at surface, covers < 0.1 % of this area

McALESTER TEXARKANA- Sandstone, greenish-gray, fine grained, well indurated, alternating with dark-gray to brown phyllites and shales in lower 100 feet; occurs only in Broken Bow Uplift and adjacent area; thickness, 670 to 804 feet, with maximum thickness in Arkansas 1,500 feet. Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS.

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

McALESTER TEXARKANA- Marl and clay, light- to dark- to brownish-gray, micaceous, calcareous, sandy, fine-grained sand, with interbedded chalky limestone; glauconitic marl and sand at base; same as lower Taylor Marl of Texas; thickness, about 100 feet.

Missouri Mountain Shale (Early Silurian) at surface, covers < 0.1 % of this area

McALESTER TEXARKANA- Shale, greenish-gray to maroon to black; grades into phyllite in Broken Bow Uplift; contains some thin sandstones and gray conglomerates; a fossiliferous limestone occurs in Southeast quarter section 29, Township 4 South, Range 23 East; mapped as SmOp in Potato Hills, where it is included with Polk Creek Shale; thickness, 60 to 110 feet or less. Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS.

Devonian System (Late to Early Devonian) at surface, covers < 0.1 % of this area

Chattanooga Shale, Sylamore Sandstone, Fortune Formation, Holts Summit Sandstone, Snyder Creek Shale, Cedar Valley Limestone, Louisiana Limestone, Saverton Shale, Grassy Creek Shale, Turpin Sandstone, Bushberg Sandstone, Glen Park Limestone, St. Larent Limestone, Beauvais Sandstone, Grand Tower Limestone, Clear Creek Chert, Little Saline Limestone, Grassy Knob Chert, Bailey Formation.

Cook Mountain Formation (Eocene) at surface, covers < 0.1 % of this area

Greenish gray sideritic clay in upper part may weather to brown ironstone; yellow to brown clays and fossiliferous marl in lower part may weather to black soil. Ironstone concretions near base.

Kiamichi Formation (Early Cretaceous) at surface, covers < 0.1 % of this area

ARDMORE-SHERMAN- Shale, dark-gray, plastic, with oyster-shell limestones; thickness, about 30 feet. McALESTER TEXARKANA- Shale, dark-gray to black, with some brown fossiliferous limestones, with "Texigryphaea navia;" thickness, 28 to 36 feet, and up to 80 feet in subsurface of southern McCurtain County.Ouachita Mountain uplift; S. OK folded belt province.

Johns Valley Formation or Johns Valley Shale (Early Pennsylvanian) at surface, covers < 0.1 % of this area

ARDMORE-SHERMAN- "Johns Valley Formation"- Shale, dark-gray, with boulder conglomerate; thickness, 425 to 900 feet. Occurs in the OUACHITA MNTS McALESTER TEXARKANA- "Johns Valley Shale"- Shale, dark-gray, with some stringers of Wapanucka-like limestone in northwestern part of area; contains exotic boulders of southern Arbuckle Mountain facies, ranging from Fort Sill to Goddard and as large as 369 feet in diameter; some Wapanucka nodules are not exotic but were formed in place; thickness, 300 to 1,000 feet. Occurs in the OUACHITA MTNS SOUTH OF TI VALLEY FAULT.

Goodland Limestone and Walnut Clay (Early Cretaceous) at surface, covers < 0.1 % of this area

ARDMORE-SHERMAN- "Goodland Limestone," limestone, gray, dense, nodular to massive; thickness, 20 to 30 feet. At base is "Walnut Clay," tan clay, about 4 feet thick. McALESTER TEXARKANA- Limestone, white, fine crystalline, massive-bedded, with "Texigryphaea mucronata;" some argillaceous buff beds in lower few feet may be "Walnut Clay" equivalents; erodes into a mappable escarpment; thickness, 26 to 55 feet.

DeQueen Limestone (Early Cretaceous) at surface, covers < 0.1 % of this area

McALESTER TEXARKANA- Limestone and marl, blue- to pinkish- to yellowish-gray, locally siliceous, interbedded with varicolored calcareous shales; basal limestone conglomerate in places where unconformable upon Ouachita rocks but absent where conformable on Holly Creek Formation; contains 80 feet of gypsum and anhydrite in subsurface; thickness, 38 feet, lensing out to 1 foot westward but thickening to 190 feet southeastward in subsurface.

Antlers Sand or Antlers Sandstone (Early Cretaceous) at surface, covers < 0.1 % of this area

ARDMORE-SHERMAN- "Antlers Sand" Sand, white to yellow, medium-grained, weakly indurated, with varicolored clays. Contains arkosic conglomerates near Arbuckle Mountains and "Baum Limestone" near Mannsville anticline. Thickness, 200 to 700 feet. McALESTER TEXARKANA- "Antlers Sandstone" Sandstone and sand, white to reddish-yellow to orange-brown to gray, fine- to coarse-grained, quartzose, crossbedded, moderately to weakly indurated, interbedded with varicolored clays and conglomerates; contains fossil wood and dinosaurs; rests unconformably upon Ouachita rocks but conformably upon DeQueen Limestone; thickness, 0 to 320 feet, thickening southeastward to 900 feet in subsurface.

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

Gray and brown silt, silty clay, some very fine sand, reddish brown along the Red River.