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Mineral Resources > Online Spatial Data > Geology > by state > Arkansas Geology

Geologic units in Pulaski county, Arkansas

Alluvium - Alluvial deposits in major stream channels or in mappable meanders of major streams (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 18 % 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.

Lithology: alluvium

Missouri Mountain Shale and Baylock Sandstone (Phanerozoic | Paleozoic | Silurian) at surface, covers < 0.1 % of this area

Missouri Mountain Shale and Baylock Sandstone - 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

Lithology: sandstone; shale; conglomerate; siltstone

Pole Creek Shale (Upper Ordovician) and Bigfork Chert (Upper and Middle Ordovician) (Phanerozoic | Paleozoic | Ordovician-Middle Ordovician-Late) at surface, covers 3 % of this area

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

Lithology: chert; shale; limestone

Igneous rocks (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 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)

Lithology: alkalic intrusive rock; nepheline syenite; syenite; intrusive carbonatite; trachyte; lamprophyre

Womble Shale (Middle Ordovician) (Phanerozoic | Paleozoic | Ordovician-Middle) at surface, covers 3 % of this area

Womble Shale (Middle Ordovician)

Lithology: shale; limestone; sandstone

Wilcox Group (Phanerozoic | Cenozoic | Tertiary | Eocene-Early) at surface, covers 5 % of this area

Wilcox Group

Lithology: sand; silt; clay or mud; gravel; coal

Jackfork Sandstone (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Early [Morrowan]) at surface, covers 27 % of this area

Jackfork Sandstone

Lithology: sandstone; shale

Johns Valley Shale (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Early [Morrowan]) at surface, covers 0.3 % of this area

Johns Valley Shale

Lithology: shale; sandstone; limestone

Alluvium (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 7 % of this area

Alluvium - Alluvial deposits of present streams

Lithology: alluvium

Atoka Formation - Lower part (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Middle [Atokan]) at surface, covers 6 % of this area

Atoka Formation - Lower part

Lithology: sandstone; shale

Midway Group (Phanerozoic | Cenozoic | Tertiary | Paleocene) at surface, covers 3 % of this area

Midway Group

Lithology: clay or mud; mixed clastic/carbonate; sandstone; limestone

Stanley Shale (Phanerozoic | Paleozoic | Carboniferous Mississippian-Early) at surface, covers 2 % 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

Lithology: shale; sandstone; siltstone; chert; tuff

Terrace deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene-Late) at surface, covers 4 % of this area

Terrace deposits - Alluvial deposits on one or more terrace levels

Lithology: alluvial terrace

Atoka Formation - Upper part (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Middle [Atokan]) at surface, covers 4 % of this area

Atoka Formation - Upper part

Lithology: sandstone; shale

Claibourne Group (Phanerozoic | Cenozoic | Tertiary | Eocene-Middle) at surface, covers 0.4 % of this area

Claibourne Group

Lithology: sand; clay or mud; coal

Arkansas Novaculite (Phanerozoic | Paleozoic | Devonian-Late Carboniferous Mississippian-Early) at surface, covers 3 % of this area

Arkansas Novaculite - Includes upper division (Mississippian), middle division (Mississippian and Devonian), and lower division (Devonian)

Lithology: novaculite; shale

Alluvium - Alluvial deposits of local streams or of overbank flow of major streams (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 6 % 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

Lithology: alluvium

Atoka Formation - Middle part (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Middle [Atokan]) at surface, covers 3 % of this area

Atoka Formation - Middle part

Lithology: sandstone; shale

Blakely Sandstone (Middle and Lower Ordovician) (Phanerozoic | Paleozoic | Ordovician-Early Ordovician-Middle) at surface, covers 0.1 % of this area

Blakely Sandstone (Middle and Lower Ordovician)

Lithology: shale; sandstone; conglomerate