Geologic units in Catahoula Parish, Louisiana

Alluvium (Holocene) at surface, covers 41 % 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 32 % of this area

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

Braided Stream Terraces (Pleistocene) at surface, covers 8 % of this area

Light gray, tan and brown fine to coarse sand; some clay silt and gravel. Overlain by 1-9 meters of loess.

Catahoula Formation (Oligocene) at surface, covers 7 % of this area

Gray to white sandstones; loose quartz sand, tuffaceous sandstone, volcanic ash, and brown sandy clays; petrified wood locally. Overlain by 1-9 meters of loess.

High Terraces (Pleistocene) at surface, covers 4 % of this area

Tan to orange clay, silt, and sand with a large amount of basal gravels. Overlain by 1-9 meters of loess.

Catahoula Formation (Oligocene) at surface, covers 3 % of this area

Gray to white sandstones; loose quartz sand, tuffaceous sandstone, volcanic ash, and brown sandy clays; petrified wood locally.

High Terraces (Pleistocene) at surface, covers 1 % of this area

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

Vicksburg Group (undifferentiated) (Oligocene) at surface, covers 1 % of this area

Brown to gray liginitic clays with thin interbeds of lignite or micaceous sands; calcareous shale, petrified wood, and bluish fossilferous clay locally.

Vicksburg Group (undifferentiated) (Oligocene) at surface, covers 0.9 % of this area

Brown to gray liginitic clays with thin interbeds of lignite or micaceous sands; calcareous shale, petrified wood, and bluish fossilferous clay locally. Overlain by 1-9 meters of loess.

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

Light gray, tan and brown fine to coarse sand; some clay silt and gravel.

Jackson Group (undifferentiated) (Eocene) at surface, covers 0.3 % of this area

Light gray to brown liginitic clays with thin interbeds of limonitic sands or lignite; near base,calcareous, glauconitic, and fossiliferous beds may weather to black soil.

Intermediate Terraces (Pleistocene) at surface, covers 0.2 % of this area

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

Jackson Group (undifferentiated) (Eocene) at surface, covers 0.1 % of this area

Light gray to brown liginitic clays with thin interbeds of limonitic sands or lignite; near base,calcareous, glauconitic, and fossiliferous beds may weather to black soil. Overlain by 1-9 meters of loess.