Geologic units in Saline county, Arkansas

Womble Shale (Middle Ordovician) (Middle Ordovician) at surface, covers 31 % of this area

Womble Shale (Middle Ordovician)

Wilcox Group (Early Eocene) at surface, covers 18 % of this area

Wilcox Group

Jackfork Sandstone (Early Pennsylvanian- Morrowan) at surface, covers 12 % of this area

Jackfork Sandstone

Stanley Shale (Early Mississippian) at surface, covers 7 % 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

Alluvium (Holocene) at surface, covers 6 % of this area

Alluvial deposits of present streams

Pole Creek Shale (Upper Ordovician) and Bigfork Chert (Upper and Middle Ordovician) (Late Ordovician to Middle Ordovician) at surface, covers 5 % of this area

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

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

Claibourne Group

Blakely Sandstone (Middle and Lower Ordovician) (Middle Ordovician to Early Ordovician) at surface, covers 4 % of this area

Blakely Sandstone (Middle and Lower Ordovician)

Terrace deposits (Late Pleistocene) at surface, covers 4 % of this area

Alluvial deposits on one or more terrace levels

Mazarn Shale (Early Ordovician) at surface, covers 3 % of this area

Mazarn Shale

Midway Group (Paleocene) at surface, covers 3 % of this area

Midway Group

Missouri Mountain Shale and Baylock Sandstone (Late Silurian) at surface, covers 1 % 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.

Arkansas Novaculite (Early Mississippian to Late Devonian) at surface, covers 1 % of this area

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

Igneous rocks (Cretaceous) at surface, covers 0.5 % 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).

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

Olistoliths of Metagabbro and Soapstone-Serpentine - Altered peridotite