Strawn Group
(Middle Pennsylvanian; Atoka and Des Moines Series) at surface, covers 28 % of this area Strawn Group
Tanyard Formation
(Early Ordovician) at surface, covers 16 % of this area Tanyard Formation
Gorman Formation
(Early Ordovician) at surface, covers 14 % of this area Gorman Formation
Marble Falls Limestone
(Pennsylvanian; Morrow Series) at surface, covers 10 % of this area Marble Falls Limestone
Terrace deposits
(Pleistocene and Holocene) at surface, covers 5 % of this area Terrace deposits
Smithwick Formation
(Middle Pennsylvanian; Atoka Series) at surface, covers 4 % of this area Smithwick Formation
Honeycut Formation
(Early Ordovician) at surface, covers 3 % of this area Honeycut Formation
Alluvium
(Holocene) at surface, covers 2 % of this area Alluvium
Barnett Formation, Chappel Limestone, Houy, Zesch, Bear Spring, and Stribling Formations, and Pillar Bluff Limestone, undivided
(Late; Middle; and Early Mississippian and Devonian) at surface, covers 2 % of this area Barnett Formation, Chappel Limestone, Houy, Zesch, Bear Spring, and Stribling Formations, and Pillar Bluff Limestone, undivided
Valley Spring Gneiss
(preCambrian (Proterozoic)) at surface, covers 0.7 % of this area Valley Spring Gneiss
Edwards Limestone
(Early Cretaceous) at surface, covers 0.4 % of this area Edwards Limestone
Packsaddle Schist
(preCambrian (Proterozoic); Llano Series) at surface, covers 0.2 % of this area Packsaddle Schist
