Geologic units in Ouachita Parish, Louisiana

Additional scientific data in this geographic area

Alluvium (Holocene) at surface, covers 28 % of this area

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

Natural Levees (Holocene) at surface, covers 27 % of this area

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

Cockfield Formation (Eocene) at surface, covers 25 % of this area

Brown lignitic clays, silts and sands; some sideritic glauconite may weather to brown ironstone in lower part.

Deweyville Terrace (Pleistocene) at surface, covers 10 % of this area

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

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

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

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

Greenish gray sideritic clay in upper part may weather to brown ironstone; yellow to brown clays and fossiliferous marl in lower part may weather to black soil. Ironstone concretions near base.

Prairie Terraces (Pleistocene) at surface, covers 0.6 % of this area

Light gray to light brown clay, sandy clay, silt, sand, and some gravels. Overlain by 1-9 meters of loess.