Geologic units in Allen Parish, Louisiana

Intermediate Terraces (Pleistocene) at surface, covers 36 % of this area

Light gray to orange-brown clay, sandy clay, and silt; much sand and gravel locally.

Prairie Terraces (Pleistocene) at surface, covers 31 % of this area

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

Alluvium (Holocene) at surface, covers 21 % of this area

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

High Terraces (Pleistocene) at surface, covers 6 % of this area

Tan to orange clay, silt, and sand with a large amount of basal gravels.

Deweyville Terrace (Pleistocene) at surface, covers 5 % of this area

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