Geologic units in Saint Charles Parish, Louisiana

Delta Plain, Fresh Marsh (Holocene) at surface, covers 37 % of this area

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

Natural Levees (Holocene) at surface, covers 31 % of this area

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

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.

Delta Plain, Saline Marsh (Holocene) at surface, covers 3 % of this area

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