Geologic units in Franklin county, Arkansas

Atoka Formation, undivided (Middle Pennsylvanian- Atokan) at surface, covers 56 % of this area

Atoka Formation, undivided

Harthshorne Sandstone (Middle Pennsylvanian- Des Moinesian) at surface, covers 14 % of this area

Harthshorne Sandstone

Savanna Formation (Late Pennsylvanian- Des Moinesian) at surface, covers 12 % of this area

Savanna Formation

McAlester Formation (Middle Pennsylvanian- Des Moinesian) at surface, covers 10 % of this area

McAlester Formation

Alluvium (Holocene) at surface, covers 3 % of this area

Alluvial deposits of present streams

Bloyd Shale, and Prairie Grove Member of the Hale Formation (Middle Pennsylvanian- Morrowan) at surface, covers 3 % of this area

Bloyd Shale, and Prairie Grove Member of the Hale Formation

Terrace deposits (Late Pleistocene) at surface, covers 2 % of this area

Alluvial deposits on one or more terrace levels

Atoka Formation - Upper part (Middle Pennsylvanian- Atokan) at surface, covers 0.4 % of this area

Atoka Formation - Upper part

Cane Hill Member of Hale Formation (Early Pennsylvanian- Morrowan) at surface, covers < 0.1 % of this area

Cane Hill Member of Hale Formation

Atoka Formation - Middle part (Middle Pennsylvanian- Atokan) at surface, covers < 0.1 % of this area

Atoka Formation - Middle part

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

Boggy Formation

Atoka Formation - Lower part (Middle Pennsylvanian- Atokan) at surface, covers < 0.1 % of this area

Atoka Formation - Lower part