Geologic units in Harnett county, North Carolina

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

Sand, sandstone, and mudstone, gray to pale gray with an orange cast, mottled; clay balls and iron-cemented concretions common, beds laterally discontinuous, cross-bedding common.

Cape Fear Formation (Cretaceous) at surface, covers 12 % of this area

Sandstone and sandy mudstone, yellowish gray to bluish gray, mottled red to yellowish orange, indurated, graded and laterally continuos bedding, blocky clay, faint cross-bedding, feldspar and mica common.

Felsic Mica Gneiss (Cambrian/Late Proterozoic) at surface, covers 6 % of this area

Interlayered with graphitic mica schist and mica-garnet schist, commonly with kyanite; minor hornblende gneiss.

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers 5 % of this area

Minor biotite and pyrite; includes phyllonite, sheared fine-grained metasediment and metavolcanic rock.

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 5 % of this area

Inequigranular and megacrystic; in places contains garnet; interlayered and gradational with mica schist and amphibolite; includes small masses of granitic rock.

Terrace Deposits and Upland Sediment (Tertiary) at surface, covers 5 % of this area

Gravel, clayey sand, and sand, minor iron-oxide cemented sandstone.

Metavolcanic-Epiclastic Rock (Cambrian/Late Proterozoic) at surface, covers 0.4 % of this area

Metamorphosed argillite, mudstone, volcanic sandstone, and conglomerate, and volcanic rock.

Castle Hayne Formation; Comfort Member and New Hanover Member, undivided (Tertiary) at surface, covers 0.3 % of this area

Comfort Member: bryozoan-echinoid skeletal limestone, locally dolomitized, solution cavities common. New Hanover Member: phosphate-pebble conglomerate, micritic, thin; restricted to basal part of Castle Hayne Formation in southeastern counties.

Granitic Rock (Permian/Pennsylvanian) at surface, covers 0.2 % of this area

Megacrystic to equigranular. Castalia, Lillington, Medoc Mountain, Sims, Contentnea Creek (?), and Elm City (?) intrusives.

Black Creek Formation (Cretaceous) at surface, covers < 0.1 % 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.

Metamorphosed Granitic Rock (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Megacrystic, well foliated, locally contains hornblende; Vance County suite and Buckhorn granite.