Geologic units in Iberia Parish, Louisiana

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 20 % of this area

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

Prairie Terraces (Pleistocene) at surface, covers 19 % of this area

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

Delta Plain, Saline Marsh (Holocene) at surface, covers 18 % of this area

Gray to black clay of very high organic content, some peat.

Chenier Plain, Fresh Marsh (Holocene) at surface, covers 9 % of this area

Gray to brown to black clay and silt of high organic content.

Chenier Plain, Saline Marsh (Holocene) at surface, covers 6 % of this area

Gray to brown to black clay and silt of moderate organic content.

Intermediate Terraces (Pleistocene) at surface, covers 0.9 % of this area

Light gray to orange-brown clay, sandy clay, and silt; much sand and gravel locally. Overlain by 1-9 meters of loess.

Delta Plain, Fresh Marsh (Holocene) at surface, covers < 0.1 % of this area

Gray to black clay of very high organic content, some peat.