Geologic units in Conway county, Arkansas

Atoka Formation, undivided (Middle Pennsylvanian- Atokan) at surface, covers 48 % of this area

Atoka Formation, undivided

Atoka Formation - Upper part (Middle Pennsylvanian- Atokan) at surface, covers 22 % of this area

Atoka Formation - Upper part

Alluvium (Holocene) at surface, covers 16 % of this area

Alluvial deposits of present streams

Terrace deposits (Late Pleistocene) at surface, covers 7 % of this area

Alluvial deposits on one or more terrace levels

Harthshorne Sandstone (Middle Pennsylvanian- Des Moinesian) at surface, covers 4 % of this area

Harthshorne Sandstone

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

Atoka Formation - Middle part

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

McAlester Formation