Geologic units in Polk county, Texas

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

Fleming Formation

Willis Formation (Pliocene) at surface, covers 24 % of this area

Willis Formation

Catahoula Formation (Oligocene) at surface, covers 12 % of this area

Catahoula Formation

Alluvium (Holocene) at surface, covers 11 % of this area

Alluvium

Lissie Formation (Quaternary; Middle Pleistocene) at surface, covers 8 % of this area

Lissie Formation

Beaumont Formation, areas predominantly sand (Quaternary; Late Pleistocene) at surface, covers 4 % of this area

Beaumont Formation, areas predominantly sand

Manning Formation (Eocene) at surface, covers 3 % of this area

Manning Formation

Whitsett Formation (Oligocene and Eocene) at surface, covers 3 % of this area

Whitsett Formation

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

Terrace deposits

Deweyville Formation (Quaternary; Pleistocene and Holocene?) at surface, covers 1.0 % of this area

Deweyville Formation

Wellborn Formation (Eocene) at surface, covers 0.9 % of this area

Wellborn Formation

Deweyville Formation with higher level? (Quaternary; Pleistocene and Holocene?) at surface, covers 0.2 % of this area

Deweyville Formation with higher level?

Queen City Sand (Eocene) at surface, covers < 0.1 % of this area

Queen City Sand