Geologic units in Stephens county, Texas

Thrifty and Graham Formations, undivided (Late Pennsylvanian; Virgil Series) at surface, covers 44 % of this area

Thrifty and Graham Formations, undivided

Harpersville Formation (Pennsylvanian; Virgil Series) at surface, covers 19 % of this area

Harpersville Formation

Pueblo Formation (Permian; Wolfcamp Series) at surface, covers 11 % of this area

Pueblo Formation

Home Creek Limestone and Colony Creek Shale, undivided (Pennsylvanian; Missouri Series) at surface, covers 8 % of this area

Home Creek Limestone and Colony Creek Shale, undivided

Alluvium (Holocene) at surface, covers 7 % of this area

Alluvium

Ranger Limestone and Placid Creek Shale, undivided (Pennsylvanian; Missouri Series) at surface, covers 3 % of this area

Ranger Limestone and Placid Creek Shale, undivided

Moran Formation (Permian; Wolfcamp Series) at surface, covers 2 % of this area

Moran Formation

Antlers Sand (Early Cretaceous) at surface, covers 2 % of this area

Antlers Sand

Winchell Limestone (Pennsylvanian; Missouri Series) at surface, covers 1 % of this area

Winchell Limestone

Terrace deposits (Pleistocene and Holocene) at surface, covers 1.0 % of this area

Terrace deposits

Wolf Mountain Shale (Pennsylvanian; Missouri Series) at surface, covers 0.8 % of this area

Wolf Mountain Shale

Sedwick and Moran Formations, undivided (Permian; Wolfcamp Series) at surface, covers 0.7 % of this area

Sedwick and Moran Formations, undivided

Palo Pinto Formation (Pennsylvanian; Missouri Series) at surface, covers 0.3 % of this area

Palo Pinto Formation

Sedwick Formation (Permian; Wolfcamp Series) at surface, covers < 0.1 % of this area

Sedwick Formation