Geologic units in Austin county, Texas

Fleming Formation (Miocene) at surface, covers 30 % of this area

Fleming Formation

Willis Formation (Pliocene) at surface, covers 28 % of this area

Willis Formation

Lissie Formation (Quaternary; Middle Pleistocene) at surface, covers 18 % of this area

Lissie Formation

Alluvium (Holocene) at surface, covers 12 % of this area

Alluvium

Beaumont Formation, areas predominantly clay (Quaternary; Late Pleistocene) at surface, covers 5 % of this area

Beaumont Formation, areas predominantly clay

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

Terrace deposits

Beaumont Formation, areas predominantly sand (Quaternary; Late Pleistocene) at surface, covers 3 % of this area

Beaumont Formation, areas predominantly sand