Geologic units in Natchitoches Parish, Louisiana

Additional scientific data in this geographic area

Natural Levees (Holocene) at surface, covers 22 % of this area

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

Alluvium (Holocene) at surface, covers 20 % of this area

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

Wilcox Group (undifferentiated) (Paleocene) at surface, covers 16 % of this area

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

Catahoula Formation (Oligocene) at surface, covers 8 % of this area

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

Prairie Terraces (Pleistocene) at surface, covers 7 % of this area

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

Carnahan Bayou Member (Miocene) at surface, covers 6 % of this area

Yellow to gray siltstones, sandstones, and clays with thin tuffaceous beds; some lenses of black chert gravel; petrified wood locally.

Sparta Formation (Eocene) at surface, covers 6 % 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 4 % of this area

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

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

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

Cockfield Formation (Eocene) at surface, covers 2 % of this area

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

Lena Member (Miocene) at surface, covers 2 % of this area

Gray calcareous clays which may weather to black soil; siltstone, taffaceous clays and some volcanic ash beds

Cook Mountain Formation (Eocene) at surface, covers 1 % 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.

Vicksburg Group (undifferentiated) (Oligocene) at surface, covers 0.5 % 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.

Jackson Group (undifferentiated) (Eocene) at surface, covers 0.5 % 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.

High Terraces (Pleistocene) at surface, covers 0.1 % of this area

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