Geologic units in Halifax county, North Carolina

Yorktown Formation and Duplin Formation, Undivided (Tertiary) at surface, covers 47 % 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.

Metamorphosed Quartz Diorite (Paleozoic/Late Proterozoic) at surface, covers 12 % of this area

Foliated to massive.

Terrace Deposits and Upland Sediment (Tertiary) at surface, covers 10 % of this area

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

Foliated to Massive Granitic Rock (Permian/Pennsylvanian) at surface, covers 9 % of this area

Megacrystic to equigranular. Butterwood Creek intrusive and Rocky Mount intrusive suite.

Cape Fear Formation (Cretaceous) at surface, covers 8 % 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.

Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 7 % of this area

Bedding plane and axial-planar cleavage common; interbedded with metasandstone, meta-conglomerate, and metavolcanic rock.

Injected Gneiss (Cambrian/Late Proterozoic) at surface, covers 4 % of this area

Biotite gneiss and schist intruded by numerous sills and dikes of granite, pegmatite, and aplite; minor hornblende gneiss.

Mafic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 1 % of this area

Metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Intermediate Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 0.6 % of this area

Metamorphosed andesitic tuffs and flows, medium to dark grayish green; minor felsic and mafic metavolcanic rock.

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 0.6 % of this area

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

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

Metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; interbedded with mafic and intermediate metavolcanic rock, meta-argillite, and metamudstone.

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.

Meta-ultramafic Rock (Paleozoic/Late Proterozoic) at surface, covers < 0.1 % of this area

Metamorphosed dunite and peridotite; serpentine, soapstone, and other altered ultramafic rock. Only larger bodies shown.

Felsic Mica Gneiss (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

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