Geologic units in Williamson county, Texas

Edwards and Comanche Peak Limestones, undivided (Early Cretaceous) at surface, covers 18 % of this area

Edwards and Comanche Peak Limestones, undivided

Walnut Clay (Early Cretaceous) at surface, covers 14 % of this area

Walnut Clay

Austin Chalk (Late Cretaceous; Gulfian Series) at surface, covers 14 % of this area

Austin Chalk

High gravel deposits (Pleistocene) at surface, covers 12 % of this area

High gravel deposits

Navarro and Taylor Groups, undivided (Late Cretaceous; Gulfian Series) at surface, covers 10 % of this area

Navarro and Taylor Groups, undivided

Glen Rose Limestone (Early Cretaceous) at surface, covers 6 % of this area

Glen Rose Limestone

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

Midway Group, undivided

Navarro Group and Marlbrook Marl, undivided (Late Cretaceous; Gulfian Series) at surface, covers 3 % of this area

Navarro Group and Marlbrook Marl, undivided

Terrace deposits (Pleistocene and Holocene) at surface, covers 3 % of this area

Terrace deposits

Hooper Formation (Paleocene) at surface, covers 3 % of this area

Hooper Formation

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

Alluvium

Georgetown Limestone (Early Cretaceous) at surface, covers 2 % of this area

Georgetown Limestone

Fredericksburg Group (Early Cretaceous; Comanchean Series) at surface, covers 2 % of this area

Fredericksburg Group

Quaternary deposit, undivided (Quaternary) at surface, covers 2 % of this area

Quaternary deposit, undivided

Del Rio Clay and Georgetown Limestone, undivided (Late Cretaceous; Gulfian Series) at surface, covers 1 % of this area

Del Rio Clay and Georgetown Limestone, undivided

Eagle Ford Formation and Buda Limestone, undivided (Late Cretaceous) at surface, covers 1 % of this area

Eagle Ford Formation and Buda Limestone, undivided

Eagle Ford Formation (Late Cretaceous) at surface, covers 0.7 % of this area

Eagle Ford Formation

Ozan Formation (Late Cretaceous; Gulfian Series) at surface, covers 0.5 % of this area

Ozan Formation

Simsboro Formation (Paleocene) at surface, covers 0.4 % of this area

Simsboro Formation

Pecan Gap Chalk (Late Cretaceous; Gulfian Series) at surface, covers 0.3 % of this area

Pecan Gap Chalk

Buda Limestone and Del Rio Clay, undivided (Late Cretaceous) at surface, covers 0.3 % of this area

Buda Limestone and Del Rio Clay, undivided; Eastern part of Trans-Pecos and High Plains and Western part of Trans-Pecos and North, central, and south Texas including Quaternary for all of west Texas.

Calvert Bluff Formation (Paleocene to Eocene) at surface, covers 0.1 % of this area

Calvert Bluff Formation

Paluxy Sand and Glen Rose Limestone, undivided (Early Cretaceous) at surface, covers < 0.1 % of this area

Paluxy Sand and Glen Rose Limestone, undivided