Geologic units in Bladen county, North Carolina

Black Creek Formation (Cretaceous) at surface, covers 67 % of this area

Clay, gray to black, lignitic; contains thin beds and laminae of fine-grained micaceous sand and thick lenses of cross-bedded sand. Glauconitic, fossiliferous clayey sand lenses in upper part.

Peedee Formation (Cretaceous) at surface, covers 20 % of this area

Sand, clayey sand, and clay, greenish gray to olive black, massive, glauconitic, locally fossiliferous and calcareous. Patches of sandy molluscan-mold limestone in upper part.

Yorktown Formation and Duplin Formation, Undivided (Tertiary) at surface, covers 11 % of this area

Yorktown Formation: fossiliferous clay with varying amounts of fine-grained sand, bluish gray, shell material commonly concentrated in lenses; mainly in area north of Neuse River. Duplin Formation: shelly, medium- to coarse-grained sand, sandy marl, and limestone, bluish gray; mainly in area south of Neuse River.

Waccamaw Formation (Tertiary) at surface, covers 2 % of this area

Fossiliferous sand with silt and clay, bluish-gray to tan, loosely consolidated. Straddles Pleistocene-Pliocene boundary.