Geologic units in Waller county, Texas

Willis Formation (Pliocene) at surface, covers 43 % of this area

Willis Formation

Lissie Formation (Quaternary; Middle Pleistocene) at surface, covers 36 % of this area

Lissie Formation

Alluvium (Holocene) at surface, covers 19 % of this area

Alluvium

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

Terrace deposits

Beaumont Formation, areas predominantly clay (Quaternary; Late Pleistocene) at surface, covers < 0.1 % of this area

Beaumont Formation, areas predominantly clay

Fleming Formation (Miocene) at surface, covers < 0.1 % of this area

Fleming Formation