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Geologic units in Rockingham county, North Carolina

Newark Supergroup, Dan River Group; Stoneville Formation (Triassic) at surface, covers 24 % of this area

Stoneville Formation - conglomerate, sandstone, and mudstone, lenticular and laterally-gradational bedding.

Felsic Mica Gneiss (Cambrian/Late Proterozoic) at surface, covers 22 % of this area

Felsic Mica Gneiss - interlayered with biotite and hornblende gneiss and schist.

Metagraywacke and Muscovite-Biotite Schist (Cambrian/Late Proterozoic) at surface, covers 18 % of this area

Metagraywacke and Muscovite-Biotite Schist - metagraywacke (biotite gneiss) interlayered and gradational with muscovite-biotite schist; minor marble and granitic rock.

Newark Supergroup, Dan River Group; Pine Hall Formation (Triassic) at surface, covers 9 % of this area

Pine Hall Formation - sandstone, mudstone, and conglomerate, yellowish orange to brown.

Mica Schist (Cambrian/Late Proterozoic) at surface, covers 8 % of this area

Mica Schist - Garnet, staurolite, kyanite, or sillimanite occur locally; lenses and layers of quartz schist, micaceous quartzite, calc-silicate rock, biotite gneiss, amphibolite, and phyllite.

Newark Supergroup, Dan River Group; Cow Branch Formation (Triassic) at surface, covers 7 % of this area

Cow Branch Formation - mudstone with minor sandstone, gray, laterally-continuous bedding. Intertongues with Stoneville and Pine Hall formations.

Lithology: mudstone; sandstone

Shelton Granite Gneiss (Silurian) at surface, covers 5 % of this area

Shelton Granite Gneiss (429 my) - poorly foliated; lineated granitic to quartz monzonitic gneiss.

Lithology: granitic gneiss

Mafic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 3 % of this area

Mafic Metavolcanic Rock - metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 1 % of this area

Biotite Gneiss and Schist - inequigranular, locally abundant potassic feldspar and garnet; interlayered and gradational with calc-silicate rock, sillimanite-mica schist, mica schist, and amphibolite. Contains small masses of granitic rock.

Granitic Rock (Permian/Pennsylvanian) at surface, covers 0.6 % of this area

Granitic Rock (265-325 my) - megacrystic to equigranular. Castalia, Lillington, Medoc Mountain, Sims, Contentnea Creek (?), and Elm City (?) intrusives.

Lithology: granite

Metamorphosed Granitic Rock (Late Proterozoic) at surface, covers 0.6 % of this area

Metamorphosed Granitic Rock (680-710 my) - massive to foliated, locally mylonitic. Beech, Crossnore, Brown Mountain, Lansing, and other granitic rocks.

Lithology: granitoid; mylonite

Amphibolite (Cambrian/Late Proterozoic) at surface, covers 0.5 % of this area

Amphibolite - equigranular, massive to well foliated, dioritic to basaltic dikes and sills; variably metamorphosed.

Lithology: amphibolite; basalt; diorite

Metamorphosed Granitic Rock (Ordovician/Cambrian) at surface, covers 0.4 % of this area

Metamorphosed Granitic Rock (455-540 my) - equigranular to megacrystic, foliated to massive. Includes Toluca Granite.

Lithology: metamorphic rock

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers 0.3 % of this area

Phyllite and Schist - minor biotite and pyrite; includes phyllonite, sheared fine-grained metasediment and metavolcanic rock.

Rich Acres Formation (Cambrian) at surface, covers < 0.1 % of this area

Rich Acres Formation - Norite, metagabbro, and diorite.

Lithology: norite; gabbro; diorite

Felsic Volcanic and Volcaniclastic Rocks (Proterozoic Z) at surface, covers < 0.1 % of this area

Felsic volcanic and volcaniclastic rocks.

Fork Mountain Formation (Proterozoic Z-Cambrian) at surface, covers < 0.1 % of this area

Fork Mountain Formation - Quartzose mica schist, garnet-biotite gneiss, calc-silicate quartzite, and melange.

Bassett Formation - Amphibolite. (Proterozoic Z-Cambrian) at surface, covers < 0.1 % of this area

Bassett Formation - Amphibolite.

Lithology: amphibolite; gneiss; schist