Geologic units in Caddo Parish, Louisiana

Wilcox Group (undifferentiated) (Paleocene) at surface, covers 38 % of this area

Gray to brown lignitic sands and silty to sandy lignitic clays, many seams of lignite; some limestone and glauconite.

Natural Levees (Holocene) at surface, covers 24 % of this area

Gray and brown silt, silty clay, some very fine sand, reddish brown along the Red River.

Alluvium (Holocene) at surface, covers 14 % of this area

Gray to brownish gray clay and silty clay, reddish brown in the Red River Valley, some sand and gravel locally.

Prairie Terraces (Pleistocene) at surface, covers 14 % of this area

Light gray to light brown clay, sandy clay, silt, sand, and some gravels.

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

White to light gray massive sands with interbedded clays; some thin beds of lignite or lignitic sands and shales.

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

Brown silty clay with basal glauconitic, fossiliferous silts which may weather to ironstone locally.

Deweyville Terrace (Pleistocene) at surface, covers 2 % of this area

Gray mixed with brown-to-red clay and silty clay; some sand and gravel locally.

Midway Group (undifferentiated) (Paleocene) at surface, covers 0.5 % of this area

Dark gray to black shale

Wilcox Group, undivided (Paleocene to Eocene) at surface, covers 0.3 % of this area

Wilcox Group, undivided

Terrace deposits (Pleistocene and Holocene) at surface, covers < 0.1 % of this area

Terrace deposits

Claibourne Group (Middle Eocene) at surface, covers < 0.1 % of this area

Claibourne Group

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

Queen City Sand

Alluvium (Holocene) at surface, covers < 0.1 % of this area

Alluvium

Reklaw Formation (Eocene) at surface, covers < 0.1 % of this area

Reklaw Formation

Quaternary deposit, undivided (Quaternary) at surface, covers < 0.1 % of this area

Quaternary deposit, undivided

Alluvium (Holocene) at surface, covers < 0.1 % of this area

Alluvial deposits of present streams

Weches Formation (Eocene) at surface, covers < 0.1 % of this area

Weches Formation