Geologic units in North Carolina (state in United States)

Additional scientific data in this geographic area

Yorktown Formation and Duplin Formation, Undivided (Tertiary) at surface, covers 13 % 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.

Surficial Deposits, Undivided (Quaternary) at surface, covers 8 % of this area

Sand, clay, gravel, and peat deposited in marine, fluvial, eolian, and lacustrine environments. Quaternary deposits not shown at altitudes greater than approx. 205 feet above mean sea level (Suffolk Scarp, in part).

Black Creek Formation (Cretaceous) at surface, covers 7 % 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 5 % 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.

Middendorf Formation (Cretaceous) at surface, covers 4 % 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.

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 3 % of this area

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.

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

Megacrystic, well foliated; locally contains hornblende. Chapel Hill, Chatham, Farrington, Meadow Flats, Mt. Moriah, Parks Crossroads plutons, and Roxboro and Vance County suites.

Ashe Metamorphic Suite and Tallulah Falls Formation; Muscovite-biotite gneiss (Late Proterozoic) at surface, covers 2 % of this area

Locally sulfidic; interlayered and gradational with mica schist, minor amphibolite, and hornblende gneiss.

Felsic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 2 % 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.

Mica Schist (Cambrian/Late Proterozoic) at surface, covers 2 % of this area

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, Chatham Group; Chatham Group, Undivided (Triassic) at surface, covers 2 % of this area

Conglomerate, fanglomerate, sandstone, and mudstone. Conglomerate and fanglomerate shown by pattern.

Castle Hayne Formation; Comfort Member and New Hanover Member, undivided (Tertiary) at surface, covers 2 % 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.

Alligator Back Formation; Gneiss (Late Proterozoic) at surface, covers 2 % of this area

Finely laminated to thin layered; locally contains massive gneiss and micaceous granule conglomerate; includes schist, phyllite, and amphibolite.

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

Inequigranular and megacrystic; 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 1 % of this area

Megacrystic to equigranular. Churchland Plutonic Suite (Western group) - Churchland, Landis, and Mooresville intrusives.

Cid Formation; Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 1 % of this area

(Southwest of Asheboro) Thin to thick bedded; bedding plane and axial-planar cleavage common; interbedded with metasandstone, metaconglomerate, and metavolcanic rock.

Foliated to Massive Granitic Rock (Permian/Pennsylvanian) at surface, covers 1 % of this area

Megacrystic to equigranular. Rolesville suite, Wise and Lemon Springs (?) intrusives.

Cape Fear Formation (Cretaceous) at surface, covers 1 % 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.

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 1 % of this area

Unconformity; pinkish gray to light gray, massive to well-foliated, granitic to quartz monzonitic; includes variably mylonitized orthogneiss and paragneiss, interlayered amphibolite, calc-silicate rock, and marble. Includes granites of the Bryson City area, Straight Fork window, and Elk Park Plutonic Suite.

Ocoee Supergroup, Great Smokey Group; Copperhill Formation (Late Proterozoic) at surface, covers 1 % of this area

Metagraywacke, massive, graded bedding common; includes dark-gray slate, mica schist, and nodular calc-silicate rock.

Coweeta Group; Biotite Gneiss (Middle/Late Proterozoic) at surface, covers 1 % of this area

Migmatitic; interlayered and gradational with biotite-garnet gneiss and amphibolite; locally abundant quartz and alumino-silicates. Stratigraphic position uncertain.

Metamorphosed Quartz Diorite (Paleozoic/Late Proterozoic) at surface, covers 1 % of this area

Foliated to massive.

River Bend Formation (Tertiary) at surface, covers 1 % of this area

Limestone, calcarenite overlain by and intercalated with indurated, sandy, molluscan-mold limestone.

Waccamaw Formation (Tertiary) at surface, covers 1 % of this area

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

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

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

Amphibolite and Biotite Gneiss (Cambrian/Late Proterozoic) at surface, covers 0.9 % of this area

Interlayered; minor layers and lenses of hornblende gneiss, metagabbro, mica schist, and granitic rock.

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 0.9 % of this area

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

Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 0.9 % of this area

Interbedded felsic to mafic tuffs and flowrock.

Terrace Deposits and Upland Sediment (Tertiary) at surface, covers 0.9 % of this area

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

Uwharrie Formation; Felsic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 0.8 % of this area

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

Migmatitic Granitic Gneiss (Ordovician/Cambrian) at surface, covers 0.8 % of this area

Foliated to massive, granitic to quartz dioritic; biotite gneiss and amphibolite common.

Henderson Gneiss (Cambrian) at surface, covers 0.8 % of this area

Monzonitic to granodioritic; inequigranular.

Metagraywacke and Muscovite-Biotite Schist (Cambrian/Late Proterozoic) at surface, covers 0.8 % of this area

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

Metamorphosed Granitic Rock (Ordovician/Cambrian) at surface, covers 0.7 % of this area

Equigranular to megacrystic, foliated to massive. Includes Toluca Granite.

Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 0.7 % of this area

Thin to thick bedded; bedding plane and axial-planar cleavage common; interbedded with metasandstone, metaconglomerate, and metavolcanic rock.

Floyd Church Formation; Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 0.7 % of this area

(Southwest of Asheboro) Thin to thick bedded; bedding plane and axial-planar cleavage common; interbedded with metasandstone, metaconglomerate, and metavolcanic rock.

Metamorphosed Mafic Rock (Paleozoic/Late Proterozoic) at surface, covers 0.7 % of this area

Metagabbro, metadiorite, and mafic plutonic-volcanic complexes.

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 0.7 % of this area

Unconformity; contains paragneiss and granitic to quartz monzonitic orthogneiss; locally schistose and mylonitic. Locally includes tectonic slices, infolded remnants, or recrystallized equivalents of the Grandfather Mountain Formation. Equivalent to the Wilson Creek Gneiss.

Metamorphosed Gabbro and Diorite (Paleozoic/Late Proterozoic) at surface, covers 0.6 % of this area

Foliated to massive.

Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 0.6 % of this area

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

Migmatitic Biotite-Hornblende Gneisses (Middle Proterozoic) at surface, covers 0.5 % of this area

Unconformity; layered biotite-granite gneiss, biotite-hornblende gneiss, amphibolite, calc-silicate rock; locally contains relict granulite facies rock.

Tillery Formation; Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 0.5 % of this area

(Southwest of Asheboro) Thin to thick bedded; bedding plane and axial-planar cleavage common; interbedded with metasandstone, metaconglomerate, and metavolcanic rock.

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

Contains garnet, staurolite, kyanite, or sillimanite; includes lenses and layers of quartz schist, micaceous quartzite, biotite gneiss, amphibolite, and phyllite.

Ashe Metamorphic Suite and Tallulah Falls Formation; Metagraywacke (Late Proterozoic) at surface, covers 0.5 % of this area

Foliated to massive, locally conglomeratic; interlayered and gradational with mica schist, muscovite-biotite gneiss, and rare graphitic schist.

Ocoee Supergroup, Great Smokey Group; Metasandstone, Metagraywacke, Metasiltstone, and Mica Schist (Late Proterozoic) at surface, covers 0.5 % of this area

Beds and lenses of calc-silicate rock locally abundant; garnet, staurolite, and cross-biotite porphyroblasts common in fine-grained layers. Includes Hughes Gap and Hothouse formations in southern area; Horse Branch Member of Ammons Formation and Grassy Branch Formation in northern area.

Ashe Metamorphic Suite and Tallulah Falls Formation; Amphibolite (Late Proterozoic) at surface, covers 0.5 % of this area

Equigranular, massive to well foliated, interlayered, rarely discordant, metamorphosed intrusive to extrusive mafic rock; may include metasedimentary rock.

Ashe Metamorphic Suite and Tallulah Falls Formation; Biotite gneiss (Late Proterozoic) at surface, covers 0.5 % of this area

Interlayered with biotite-garnet gneiss, biotite-muscovite schist, garnet-mica schist, and amphibolite.

Belgrade Formation, Undivided (Tertiary) at surface, covers 0.4 % of this area

Pollocksville Member: oyster-shell mounds in tan to orange sand matrix, indurated locally. Haywood Landing Member: fossiliferous clayey sand, gray to brown. Members grade into each other laterally.

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.

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers 0.4 % of this area

Locally laminated and pyritic; includes phyllonite, sheared fine-grained metasediment, and metavolcanic rock. In Lilesville granite aureole, includes hornfels.

Granitic Rock (Permian/Pennsylvanian) at surface, covers 0.4 % of this area

Megacrystic to equigranular. Castalia and Wilton intrusives.

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

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

Alligator Back Formation; Mica schist and phyllite (Late Proterozoic) at surface, covers 0.4 % of this area

Laminated to thin layered; interlayered with minor biotite-muscovite gneiss and amphibolite.

Pinehurst Formation (Tertiary) at surface, covers 0.4 % of this area

Sand, medium- to coarse-grained, cross-bedding and rhythmic bands of clayey sand common, unconsolidated.

Quartz Diorite to Granodiorite (Devonian) at surface, covers 0.4 % of this area

Contains biotite, muscovite, and xenocrysts. Includes Whiteside Mountain, Stone Mountain, Mount Airy, Spruce Pine, and other smaller plutons.

Injected Gneiss (Cambrian/Late Proterozoic) at surface, covers 0.4 % of this area

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

Metagraywacke, Amphibolite, and Kyanite Schist (Cambrian/Late Proterozoic) at surface, covers 0.4 % of this area

Metagraywacke (biotite gneiss) interlayered and gradational with amphibolite and kyanite schist; minor ultramafic and granitic rock.

Banded Gneiss (Cambrian/Late Proterozoic) at surface, covers 0.3 % of this area

Interlayered with calc-silicate rock, metaconglomerate, amphibolite, sillimanite-mica schist, and granitic rock.

Castle Hayne Formation; Spring Garden Member (Tertiary) at surface, covers 0.3 % of this area

Molluscan-mold limestone, indurated, very sandy. Grades downward into a calcareous sand and laterally into Comfort Member.

Felsic Mica Gneiss (Cambrian/Late Proterozoic) at surface, covers 0.3 % of this area

Interlayered with biotite and hornblende gneiss and schist.

Ocoee Supergroup, Great Smokey Group; Wehutty Formation (Late Proterozoic) at surface, covers 0.3 % of this area

Slate to schist, dark gray, graphitic and sulfidic; includes mica schist, metagraywacke, and metaconglomerate.

Felsic Mica Gneiss (Cambrian/Late Proterozoic) at surface, covers 0.3 % of this area

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

Newark Supergroup, Chatham Group; Sanford Formation (Triassic) at surface, covers 0.3 % of this area

Conglomerate, fanglomerate, sandstone, and mudstone.

Ocoee Supergroup; Great Smokey Group, undivided (Late Proterozoic) at surface, covers 0.3 % of this area

Thick metasedimentary sequence of massive to graded beds of metagraywacke and metasiltstone with interbedded graphitic and sulfidic slate and schist.

Foliated to Massive Granitic Rock (Permian/Pennsylvanian) at surface, covers 0.3 % of this area

Megacrystic to equigranular. High Shoals Granite.

Intermediate Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 0.3 % of this area

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

Granodioritic Gneiss (Middle Proterozoic) at surface, covers 0.3 % of this area

Unconformity; greenish gray to pinkish gray, porphyroclastic to mylonitic; epidote, sericite, and chlorite common.

Battleground Formation (Late Proterozoic) at surface, covers 0.3 % of this area

Quartz-sericite schist with metavolcanic rock, quartz-pebble metaconglomerate, kyanite-sillimanite quartzite, and garnet-quartz rock.

Newark Supergroup, Chatham Group; Pekin Formation (Triassic) at surface, covers 0.3 % of this area

Conglomerate, sandstone, and mudstone.

Granitic Rock (Devonian/Ordovician) at surface, covers 0.3 % of this area

Locally pinkish gray, massive to weakly foliated; contains hornblende.

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

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

Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

Interbedded felsic to mafic tuffs and flowrock.

Nantahala Formation and Tusquitee Quartzite, undivided (Late Proterozoic) at surface, covers 0.2 % of this area

Nantahala Formation: slate and metasiltstone, dark gray, laminated to thin bedded, sulfidic; Tusquitee Quartzite: white to light yellowish gray, numerous, thin slate layers.

Gabbro of Concord Plutonic Suite (Devonian/Ordovician) at surface, covers 0.2 % of this area

Barber, Concord, Farmington, Mecklenburg, and Weddington intrusives.

Fine-grained Biotite Gneiss (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

Massive to strongly foliated; minor layers of amphibolite and muscovite schist.

Metamorphosed Quartz Diorite (Paleozoic/Late Proterozoic) at surface, covers 0.2 % of this area

Foliated to massive.

Newark Supergroup, Dan River Group; Stoneville Formation (Triassic) at surface, covers 0.2 % of this area

Conglomerate, sandstone, and mudstone, lenticular and laterally-gradational bedding.

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

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

Brasstown Formation (Late Proterozoic) at surface, covers 0.2 % of this area

Cross-biotite schist; includes micaceous quartzite in lower part.

Cid Formation; Felsic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

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

Yadkin Formation (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

Metamorphosed graywacke, volcanic sandstone, and siltstone; interbedded with mafic and intermediate metavolcanic flows and tuffs.

Ocoee Supergroup, Great Smokey Group; Dean Formation (Late Proterozoic) at surface, covers 0.2 % of this area

Sericite schist with cross-biotite, staurolite, and garnet porphyroblasts; interbedded metagraywacke and quartz-pebble metaconglomerate.

Granite of Salisbury Plutonic Suite (Devonian/Silurian) at surface, covers 0.2 % of this area

Pink, massive to weakly foliated. Gold Hill, Kannapolis, Salisbury, Southmont, and Yadkin intrusives.

Cherryville Granite (Mississippian) at surface, covers 0.2 % of this area

Massive to weakly foliated; contains pegmatites, lithium-bearing on east side.

Metamorphosed Granitic Rock (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

Megacrystic, well foliated; locally contains hornblende.

Blacksburg Formation (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

Sericite schist, locally with graphite, phyllite with sericite quartzite, banded marble, amphibolite, and minor calc-silicate rock.

Granitic Gneiss (Late Middle Proterozoic) at surface, covers 0.2 % of this area

Megacrystic, in places contains amphibolite.

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

Megacrystic to equigranular. Lilesville granite.

Mineral Bluff Formation (Late Proterozoic) at surface, covers 0.1 % of this area

Quartz-chlorite-sericite schist and phyllite with thin quartzite layers and minor interbedded graphitic schist, garnet-mica schist, staurolite schist, cross-biotite schist, and dark slate.

Inequigranular Biotite Gneiss (Cambrian/Late Proterozoic) at surface, covers 0.1 % of this area

Weakly foliated to massive, contains plagioclase megacrysts and, rarely, larger megacrysts of quartz and feldspar.

Granite Gneiss (Silurian/Ordovician) at surface, covers 0.1 % of this area

Poorly foliated; interlayered with biotite augen gneiss.

Rocks of Brevard Fault Zone (Uncertain, possibly Permian or Devonian) at surface, covers 0.1 % of this area

"Fish scale" schist and phyllonite, graphitic; interlayered with feldspathic metasandstone, marble lenses.

Garnet-Mica Schist (Cambrian/Late Proterozoic) at surface, covers 0.1 % of this area

Interlayered with amphibolite.

Grandfather Mountain Formation; Metagraywacke (Late Proterozoic) at surface, covers 0.1 % of this area

Cross-bedding and graded bedding common, locally conglomeratic; interlayered with metasiltstone and phyllite.

Blowing Rock Gneiss (Middle Proterozoic) at surface, covers 0.1 % of this area

Unconformity; abundant white potassic feldspar megacrysts in finely banded biotite schist, locally calcareous; interlayered with quartz-feldspar schist, calcareous biotite schist, phyllite, black slate, calcareous quartzite, sulfidic greenstone, and siliceous tuff.

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

Massive to foliated, granodioritic, migmatitic.

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

Contains quartz and microcline porphyroblasts.

Ocoee Supergroup, Snowbird Group, undivided (Late Proterozoic) at surface, covers < 0.1 % of this area

Feldspathic metasiltstone, metasandstone, and phyllite. Basal schist contains lenses of quartz-pebble conglomerate.

Ocoee Supergroup, Great Smokey Group; Slate of Copperhill Formation (Late Proterozoic) at surface, covers < 0.1 % of this area

Slate to phyllite, dark gray, graphitic, sulfidic; includes metagraywacke with local graded bedding.

Cid Formation; Mafic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

(Southwest of Asheboro) Metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Ocoee Supergroup, Snowbird Group; Longarm Quartzite (Late Proterozoic) at surface, covers < 0.1 % of this area

Cross-bedded, feldspathic, locally conglomeratic; includes dark slate and metasiltstone.

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

White to pink, with strong lineation of muscovite-biotite streaks and prismatic quartz aggregates; planar foliation and layering weak; minor mica schist and hornblende gneiss.

Grandfather Mountain Formation; Meta-arkose (Late Proterozoic) at surface, covers < 0.1 % of this area

Sericitic, conglomeratic, locally cross-bedded; interlayered metasiltstone and slate.

Ocoee Supergroup, Snowbird Group; Roaring Fork Sandstone (Late Proterozoic) at surface, covers < 0.1 % of this area

Greenish gray, fine to medium grained, locally cross-bedded, metamorphosed; interbedded metasiltstone and phyllite.

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

Metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; minor mafic and intermediate metavolcanic rock.

Toxaway Gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Unconformity; poorly foliated to well-foliated; equigranular to inequigranular, granitic.

Max Patch Granite (Late Proterozoic) at surface, covers < 0.1 % of this area

Mottled pink and light green, coarse grained to porphyritic, massive; contains biotite.

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

Massive to foliated, locally mylonitic. Beech, Crossnore, Brown Mountain, Lansing, and other granitic rocks.

Caesars Head Granite Gneiss (Devonian/Silurian) at surface, covers < 0.1 % of this area

Equigranular to porphyritic, massive to well foliated; contains biotite and muscovite.

Newark Supergroup, Dan River Group; Pine Hall Formation (Triassic) at surface, covers < 0.1 % of this area

Sandstone, mudstone, and conglomerate, yellowish orange to brown.

Alligator Back Formation; Amphibolite (Late Proterozoic) at surface, covers < 0.1 % of this area

Equigranular, massive to well foliated, interlayered, rarely discordant, metamorphosed intrusive and extrusive mafic rock; may include metasedimentary rock.

Beaufort Formation, Undivided (Tertiary) at surface, covers < 0.1 % of this area

Unnamed upper member: sand and silty clay, glauconitic, fossiliferous, and locally calcareous. Jericho Run Member: siliceous mudstone with sandstone lenses, thin bedded; basal phosphatic pebble conglomerate.

Chilhowee Group; Upper Chilhowee (Cambrian) at surface, covers < 0.1 % of this area

Vitreous quartzite, white to light gray; interbedded sandy metasiltstone and slate.

Fine-grained Biotite Gneiss (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Strongly foliated; minor layers of amphibolite and muscovite schist.

Coweeta Group (Late Proterozoic) at surface, covers < 0.1 % of this area

Quartz dioritic gneiss, feldspar-quartz-biotite gneiss, metasandstone and quartzite, alumino-silicate schist, garnetiferous biotite gneiss, and minor amphibolite. Quartz dioritic gneiss predominant.

Grandfather Mountain Formation; Felsic metavolcanic rocks and metasedimentary rocks (Late Proterozoic) at surface, covers < 0.1 % of this area

Tentatively correlated with Grandfather Mountain Formation.

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

Poorly layered to massive; megacrysts of microcline and quartz; local mica schist, amphibolite, and biotite gneiss

Chilhowee Group; Lower Chilhowee (Cambrian) at surface, covers < 0.1 % of this area

Feldspathic arenite, white to yellowish gray. Minor silty shale, feldspathic siltstone, and conglomerate in lower part. Includes Unicoi Formation of Hot Springs window.

Ocoee Supergroup; Walden Creek Group, undivided (Late Proterozoic) at surface, covers < 0.1 % of this area

Slate to metasiltstone, locally limy beds and pods; interbedded with quartz-pebble metaconglomerate and metasandstone.

Ocoee Supergroup, Great Smokey Group; Boyd Gap Formation (Late Proterozoic) at surface, covers < 0.1 % of this area

Dark gray, highly-sulfidic slate and metasiltstone interbedded and gradational with metagraywacke. Stratigraphic position uncertain. In Cherokee County includes upper part of Buck Bald Formation.

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Minor biotite, pyrite, and sillimanite; includes minor quartzite.

Shelton Granite Gneiss (Silurian) at surface, covers < 0.1 % of this area

Poorly foliated; lineated granitic to quartz monzonitic gneiss.

Chilhowee Group; Lower Chilhowee (Cambrian) at surface, covers < 0.1 % of this area

Feldspathic quartzite, white to yellowish gray. Minor silty slate, feldspathic metasiltstone, and metaconglomerate in lower part.

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

Massive to foliated, locally mylonitic.

Grandfather Mountain Formation; Metasiltstone (Late Proterozoic) at surface, covers < 0.1 % of this area

Locally contains thin bedded iron-bearing dolomitic marble; interlayered with phyllite, metagraywacke, and meta-arkose.

Newark Supergroup, Chatham Group; Cumnock Formation (Triassic) at surface, covers < 0.1 % of this area

Sandstone and mudstone, gray to black; coal beds and carbonaceous shale. Grades into Pekin and Sanford formations.

Granitic Rock (Permian/Pennsylvanian) at surface, covers < 0.1 % of this area

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

Coweeta Group; Amphibolite (Middle/Late Proterozoic) at surface, covers < 0.1 % of this area

Equigranular, massive to well foliated, interlayered, rarely discordant, metamorphosed intrusive to extrusive mafic rock; may include metasedimentary rock.

Newark Supergroup, Dan River Group; Cow Branch Formation (Triassic) at surface, covers < 0.1 % of this area

Mudstone with minor sandstone, gray, laterally-continuous bedding. Intertongues with Stoneville and Pine Hall formations.

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

Metamorphosed mafic extrusive and intrusive rock; includes hornblende gneiss, thin layers of mica schist, and small nonlayered masses of metadiorite and metagabbro.

Newark Supergroup, Chatham Group; Diabase (Jurassic) at surface, covers < 0.1 % of this area

Diabase - dikes and sills, gray to black.

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

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

Newark Supergroup, Dan River Group; Dan River Group, Undivided (Triassic) at surface, covers < 0.1 % of this area

Basin-margin conglomerate and sandstone, red to brown, interfingering with basin-center sandstone and mudstone, green to brown. Conglomerate shown by pattern.

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

Interlayered with quartz-muscovite schist, contains muscovite, andalusite, kyanite, or sillimanite.

Fine-grained Biotite Gneiss (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Strongly foliated; minor layers of amphibolite and muscovite schist.

Rabun Gneiss (Ordovician) at surface, covers < 0.1 % of this area

Weakly to well foliated, granitic to quartz monzonitic.

Metamorphosed Gabbro and Diorite (Paleozoic/Late Proterozoic) at surface, covers < 0.1 % of this area

Foliated to massive.

Murphy Marble, Andrews Formation, and Nottely Quartzite, undivided (Late Proterozoic) at surface, covers < 0.1 % of this area

Murphy Marble: calcareous to dolomitic; Andrews Formation: calcareous cross-biotite schist; Nottely Quartzite: meta-orthoquartzite with slate.

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

Massive to well foliated; contains andalusite, kyanite, or sillimanite, chloritoid, and pyrite.

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

(Located in the Lilesville granite aureole) 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.

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

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

Grandfather Mountain Formation; Greenstone (Late Proterozoic) at surface, covers < 0.1 % of this area

Schistose to massive, amygdaloidal; interlayered with metasedimentary rocks. Includes Montezuma Member (metabasalt) in upper part.

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Includes phyllonite and interlayered biotite gneiss.

Syenite of Concord Plutonic Suite (Devonian/Silurian) at surface, covers < 0.1 % of this area

Includes the Concord ring dike.

Amphibolite (Middle Proterozoic) at surface, covers < 0.1 % of this area

Unconformity; equigranular, massive to well foliated, interlayered, rarely discordant, metamorphosed intrusive to extrusive mafic rock; may include metasedimentary rock.

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.

Mount Rogers Formation; Metagraywacke (Late Proterozoic) at surface, covers < 0.1 % of this area

Interlayered with metaconglomerate, laminated metasiltstone, and slate; minor calcareous metasandstone, greenstone, and metarhyolite.

Ocoee Supergroup, Great Smokey Group; Anakeesta Formation (Late Proterozoic) at surface, covers < 0.1 % of this area

Slate to schist, dark gray, graphitic and sulfidic; includes interbedded argillaceous, feldspathic metagraywacke.

Ocoee Supergroup, Snowbird Group; Wading Branch Formation (Late Proterozoic) at surface, covers < 0.1 % of this area

Sandy slate to coarse-grained pebbly metagraywacke with local graded bedding. Basal quartz-sericite schist or phyllite.

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

Metamorphosed basaltic to andesitic tuffs and flows, grayish green to black. Locally includes hypabyssal intrusives and minor felsic metavolcanic rock.

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

Metamorphosed mafic extrusive and intrusive rock; includes hornblende gneiss, thin layers of mica schist, calc-silicate rock, and, rarely, marble. Also includes small masses of metadiorite and metagabbro.

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

Metamorphosed dunite, local peridotite, serpentinite, soapstone, and other ultramafic rock. Only larger bodies shown.

Metamorphosed Granite (Late Proterozoic) at surface, covers < 0.1 % of this area

Massive to foliated, locally mylonitic. Equivalent to Brown Mountain Granite.

Metamorphosed Quartz Diorite (Paleozoic/Late Proterozoic) at surface, covers < 0.1 % of this area

Foliated to massive.

Metamorphosed Gabbro and Diorite (Paleozoic/Late Proterozoic) at surface, covers < 0.1 % of this area

Foliated to massive.

Linville Metadiabase (Late Proterozoic) at surface, covers < 0.1 % of this area

Metadiabase, greenstone, and amphibolite dikes and sills; massive to schistose.

Mount Rogers Formation; Metafelsite (Late Proterozoic) at surface, covers < 0.1 % of this area

Light-colored porphyritic extrusive rock.

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

Metagabbro, metadiorite, and mafic plutonic-volcanic complexes.

Ocoee Supergroup, Great Smokey Group; Rich Butt Sandstone (Late Proterozoic) at surface, covers < 0.1 % of this area

Feldspathic; interbedded with dark argillaceous layers and laminae. Stratigraphic position uncertain.

Ocoee Supergroup, Snowbird Group; Pigeon Siltstone (Late Proterozoic) at surface, covers < 0.1 % of this area

Thin bedded to laminated, commonly cross-bedded, metamorphosed; locally includes argillite and calcareous and arkeritic metasiltstone grading to silty metalimestone.

Chilhowee Group; Upper Chilhowee (Cambrian) at surface, covers < 0.1 % of this area

Vitreous quartz arenite, white to light gray; interbedded sandy siltstone and shale. Erwin and Hampton formations of Hot Springs window.

Ocoee Supergroup, Walden Creek Group; Sandsuck Formation (Late Proterozoic) at surface, covers < 0.1 % of this area

Slate and metasiltstone, dark green to black. Metaconglomerate lentils in upper part; calcareous metasandstone, sandy metalimestone, and quartzite in lower part.

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

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

Metamorphosed Quartz Diorite (Paleozoic/Late Proterozoic) at surface, covers < 0.1 % of this area

Foliated to massive.

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

Equigranular, massive to well foliated, dioritic to basaltic dikes and sills; variably metamorphosed.

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

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

Ocoee Supergroup, Great Smokey Group; Phyllite (Late Proterozoic) at surface, covers < 0.1 % of this area

Dark olive gray, graphitic and sulfidic.

Ashe Metamorphic Suite and Tallulah Falls Formation; Mica schist (Late Proterozoic) at surface, covers < 0.1 % of this area

Locally sulfidic and graphitic; minor interlayered mica gneiss and amphibolite.

Great Smoky Group, includes Unnamed Sandstone Unit, Anakeesta Formation, Thunderhead Sandstone, and Elkmont Sandstone (Precambrian) at surface, covers < 0.1 % of this area

Great Smoky Group - Characterized by very massive layers of coarse graywacke and arkose. The formations at right have been mapped only in region of the Great Smoky Mountains. Thickness 14,000 to about 25,000 feet; includes Unnamed Sandstone Unit - Gray, coarse sandstone and fine conglomerate, similar to Thunderhead Sandstone. Thickness about 4,500 feet; Anakeesta Formation - Dark-gray, bluish-gray, and black slate with dark-gray interbeds of fine-grained sandstone. Thickness 3,000 to 4,500 feet; Thunderhead Sandstone - Coarse, gray feldspathic sandstone, graywacke, and conglomerate; occurs in massive ledges; graded bedding and blue quartz characteristic. Thickness 5,500 to 6,300 feet; Elkmont Sandstone - Coarse to fine, gray feldspathic sandstone, graywacke, and fine conglomerate; generally finer grained beds in lower part; graded bedding typical. Thickness 1,000 to 8,000 feet.

Pee Dee Gabbro (Pennsylvanian) at surface, covers < 0.1 % of this area

Dark gray to black, medium to fine grained, massive.

Grandfather Mountain Formation; Porphyritic felsic volcanic rock (Late Proterozoic) at surface, covers < 0.1 % of this area

Phyllitic to schistose, contains euhedral to subhedral phenocrysts of gray quartz and pink potassic feldspar. Resembles quartzite and meta-arkose.

Cherryville Granite (Mississippian) at surface, covers < 0.1 % of this area

Massive to weakly foliated; contains pegmatites.

Volcanic Metaconglomerate (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Includes metagraywacke and metamudstone.

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.

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.

Metamorphosed Gabbro and Diorite (Paleozoic/Late Proterozoic) at surface, covers < 0.1 % of this area

Foliated to massive.

Shady Dolomite (Cambrian) at surface, covers < 0.1 % of this area

Light gray, fine grained, massive, locally thin bedded or ribboned. Thin beds of phyllite.

Metavolcanic-Epiclastic Rock (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

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

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

Shale and siltstone, variegated red to brown; interbedded fine-grained sandstone and shaly dolomite.

Amphibolite (Middle Proterozoic) at surface, covers < 0.1 % of this area

Unconformity; equigranular, massive to well foliated, interlayered, rarely discordant, metamorphosed intrusive to extrusive mafic rock; may include metasedimentary rock.

Shady Dolomite (Cambrian) at surface, covers < 0.1 % of this area

Light gray, fine grained, massive, locally thin bedded or ribboned.

Great Smoky Group, including Anakeesta Formation, Thunderhead Sandstone, and Elkmont Sandstone (Precambrian) at surface, covers < 0.1 % of this area

Great Smoky Group - Characterized by very massive layers of coarse graywacke and arkose. The formations have been mapped only in the region of the Great Smoky Mountains. Near Ducktown, in ascending order, the Copperhill, Hughes Gap, Hothouse, and Dean Formations are recognized. Thickness 14,000 to about 40,000 feet. Includes Anakeesta Formation - Dark-gray, bluish-gray, and black slate with dark-gray interbeds of fine-grained sandstone. Thickness 3,000 to 4,500 feet; Thunderhead Sandstone - Coarse, gray feldspathic sandstone, graywacke, and conglomerate; occurs in massive ledges; graded bedding and blue quartz characteristic. Thickness 5,500 to 6,300 feet; Elkmont Sandstone - Coarse to fine, gray feldspathic sandstone, graywacke, and fine conglomerate; generally finer grained beds in lower part; graded bedding typical. Thickness 1,000 to 8,000 feet.

Cranberry Granite (Precambrian) at surface, covers < 0.1 % of this area

Complex of intertonguing rock types including migmatite, granitic gneisses, monzonite, quartz diorite, greenstone, mica and hornblende schists, abundant granitic pegmatite.

Quartzite and Quartz-Muscovite Schist (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Garnet, andalusite, kyanite, or sillimanite occur locally.

Biotite Gneiss (Proterozoic) at surface, covers < 0.1 % of this area

Light-gray, medium- to coarse grained, compositionally-layered and locally migmatitic rocks, include interlayered biotite gneiss, muscovite-biotite gneiss, muscovite-biotite schist, and sillimanite-mica schist; also includes minor interlayers and lenses of granitic gneiss, biotite-amphibole gneiss, amphibolite, garnet-mica schist, calc-silicate granofels, and rare ultramafic rocks. This unit correlates with Raleigh belt rocks in North Carolina (Parker, 1979; Geologic Map of North Carolina, 1985).

Persimmon Fork Formation (Cambrian to Neoproterozoic) at surface, covers < 0.1 % of this area

Predominately metatuff

Interlayered Mafic and Felsic Metavolcanic Rocks (Cambrian) at surface, covers < 0.1 % of this area

Heterogenous layered assemblage correlates with the Chopawamsic Formation and Ta River Metamorphic Suite, on strike to the northeast, and in traceable into the Milton belt in North Carolina (Geologic Map of North Carolina, 1985). Quartzofeldspathic biotite gneiss. Heterogeneous layered sequence consists of salt-and-pepper and segregation layered biotite granite gneiss interlayered with biotite schist; dark-gray to black, fine- to coarse-grained, thin- to thickly-laminated hornblende gneiss and schist; lesser quartz-muscovite schist; and, locally, gray to green, medium-grained, calcareous gneiss and calc-silicate granofels (Tobish and Glover, 1969). This unit includes the upper and lower felsic gneiss units and intermediate volcanic rocks in the Hyco Formation as used by Baird (1989, 1991); and biotite gneiss and interlayered gneiss of Kreisa (1980), correlative with the biotite gneiss unit of Marr (1980a; 1980b). Mineralogy: (quartzofeldspathic rocks), (1) quartz + albite + potassium feldspar + muscovite + chlorite + actinolite + epidote + calcite + magnetite + zircon; (2) quartz + oligoclase + muscovite + biotite + garnet + hornblende + magnetite + epidote + rutile + calcite + zircon; (mafic rocks), (1) quartz + albite + chlorite + epidote + actinolite + titanite + magnetite ilmenite. (2) quartz + oligoclase + andesine + hornblende + microcline + biotite + garnet + cordierite + magnetite + rutile + titanite + scapolite; (pelitic rocks), (1) quartz + albite + muscovite + chlorite + epidote + magnetite-ilmenite; (2) quartz + muscovite + biotite + kyanite + oligoclase + potassium feldspar + epidote + magnetite-ilmenite + garnet; (3) quartz + muscovite + sillimanite + magnetite-ilmenite; (calcareous rocks), (1) quartz + calcite + biotite + epidote + chlorite + tremolite + ilmenite; (2) calcite+ quartz + epidote + hornblende + pyroxene + scapolite. Geophysical signature: felsic rocks are delineated by strike-elongate positive radiometric anomalies (Henika and Johnson, 1980); mafic metavolcanic rocks and metasedimentary units are characterized by closed strike-elongate radiometric lows and closed strike-elongate aeromagnetic highs.

Cid Formation, Mudstone Member (Ordovician to Late Cambrian) at surface, covers < 0.1 % of this area

Thin bedded tuffaceous metasiltstone

Metamorphosed granite and granodiorite (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Metamorphosed granite and granodiorite

Phyllite and Metatuff (Proterozoic Z) at surface, covers < 0.1 % of this area

Includes light-gray, very fine-grained, foliated chlorite-sericite phyllite and phyllitic metamudstone, and dark-gray to white, fine- to medium-grained lithic and crystal dacite metatuff. Includes Goshen schist of Laney (1917).

Aaron Slate (Proterozoic Z) at surface, covers < 0.1 % of this area

Very-light-gray, fine-grained, bedded volcaniclastic sediments, conglomerate, lithic feldspathic arenite, micaceous sandstone, siltstone, phyllite, argillite, and vitric tuff, with minor greenstone. Lithic fragments and relict euhedral crystals are common. The lower part of the unit is dominantly grayish-green slate interbedded with light-gray to grayish-green micaceous metasandstone; bedding is conspicuous and graded-bedding is common. The unit grades upward to bedded light-gray to moderate-red phyllite, metasandstone and slate.

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

Sequence of gray feldspathic sandstone, arkose, conglomerate, graywacke, siltstone and shale; greenish amygdaloidal basalt flows near middle and base. Thickness 2,000 to 5,000 feet.

Biotite-Muscovite Granite (Proterozoic) at surface, covers < 0.1 % of this area

Light-gray, fine- to coarse grained, muscovite-biotite granite, biotite-muscovite granite, and leucogranite with accessory garnet. The granite is undated but interpreted as part of the Pennsylvanian-Permian suite of granites, and considered as part of the Wise pluton, which can be traced into North Carolina (McSween and others, 1991).

Metamorphosed quartz diorite to diorite (Early Paleozoic-Neoproterozoic) at surface, covers < 0.1 % of this area

Metamorphosed quartz diorite to diorite

Bacons Castle Formation (Tertiary) at surface, covers < 0.1 % of this area

Tb1/Tb2 Bacons Castle Formation (upper Pliocene, Coch, 1965). Gray, yellowish-orange, and reddish-brown sand, gravel, silt, and clay; constitutes surficial deposits of high plain extending from Richmond, eastward to the Surry scarp. Unit is subdivided into two members: Tb1, massive to thick-bedded pebble and cobble gravel grading upward into cross-bedded, pebbly sand and sandy and clayey silt, and Tb2, predominantly thin-bedded and laminated clayey silt and silty fine-grained sand. Tb2 is characterized by flaser, wavy, and lenticular bedding and rare to common clay-lined burrows including Ophiomorpha nodosa. Thickness is 0 to 70 feet.

Beech Granite (Precambrian) at surface, covers < 0.1 % of this area

Granite, porphyritic, light-gray to reddish; coarse potash feldspar crystals and clustered interstitial mafics (chloritized biotite and hornblende) give spotted appearance; includes Max Patch Granite.

Mount Rogers Formation - Conglomerate, graywacke, laminated siltstone, and shale. (Proterozoic Z) at surface, covers < 0.1 % of this area

Graywacke conglomerate, graywacke, tuffaceous sandstone, laminated siltstone, shale, and minor greenstone and rhyolite. Most of the sedimentary rocks are volcanigenic but contain a significant detrital contribution from the underlying crystalline rocks of the Grenville-age basement.

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

Equigranular, massive to well foliated, dioritic to basaltic dikes and sills; variably metamorphosed.

Ocoee Supergroup, including Walden Creek Group, (including Sandsuck Formation, Wilhite Formation, Shields Formation, Licklog Formation), Cades Sandstone, and Rich Butt Sandstone (Precambrian) at surface, covers < 0.1 % of this area

Ocoee Supergroup - Terrigenous clastic sedimentary rocks, for the most part poorly sorted and coarse. The groups are subdivided into formations only in the region of the Great Smoky Mountains. Thickness as much as 50,000 feet. Includes Walden Creek Group - The formations, other than the Sandsuck, have been mapped only in the region of the Great Smoky Mountains. Thickness about 8,000 feet; Sandsuck Formation - Olive-green and gray, argillaceous, micaceous shale with coarse feldspathic sandstone and quartz- pebble conglomerate. Thickness about 2,000 feet; Wilhite Formation - Gray to green siltstone and slate with interbeds of pebble conglomerate, sandstone, and quartzite. Thickness about 4,000 feet; Shields Formation - Massive conglomerate, sandstone, argillaceous slate; conglomerate (pebbles of various rock types) characteristic. Thickness about 1,500 feet; Licklog Formation - Feldspathic sandstone, greenish phyllite, and bluish-gray slate. Thickness about 1,500 feet; and the Cades Sandstone - Gray, well-bedded, fine- to medium-grained feldspathic metasandstone, with interbeds of dark slate and metasiltstone; precise stratigraphic position unknown. Thickness about 1,500 feet; and Rich Butt Sandstone - Gray, massive beds of feldspathic, fine- to medium-grained sandstone, with interbeds of dark slate and arkosic conglomerate; exact stratigraphic position unknown. Thickness about 1,500 feet.

Hyco Formation (Proterozoic Z) at surface, covers < 0.1 % of this area

Includes light-gray, fine- to medium grained, foliated quartz-muscovite schist with relict quartz and plagioclase phenocrysts; lithic and crystal metatuff with relict volcanic fragments; and, minor felsic breccia and tuffaceous greenstone. A penetrative schistosity is defined by aligned mica grains; a lineation is defined by the ellipsoidal relict phenocrysts. These rocks were originally named the Hyco quartz porphyry by Laney (1917); they were renamed the Hyco Formation by Kreisa (1980). The Hyco has been dated at 620±20 Ma (Pb-Pb zircon; Glover and others, 1971).

Snowbird Group, including Pigeon Siltstone, Roaring Fork Sandstone, Metcalf Phyllite, Longarm Quartzite, and Wading Branch Formation (Precambrian) at surface, covers < 0.1 % of this area

Snowbird Group - The formations at right are applicable chiefly in the area of the Great Smoky Mountains. Thickness 13,000 to about 20,000 feet. Includes Pigeon Siltstone - Laminated, greenish quartzose and feldspathic siltstone; minor fine-grained gray sandstone. Thickness as much as 10,000 feet; Roaring Fork Sandstone - Interbedded massive feldspathic sandstone, greenish siltstone, and greenish phyllite. Maximum thickness 7,000 feet; Metcalf Phyllite - Lustrous, pale-green and silvery sericitic and chloritic phyllite; siltstone interbeds abundant. Thickness uncertain; at least 5,000 feet; Longarm Quartzite - Feldspathic quartzite and arkose, conspicuously light-colored, current bedded and crossbedded. Thickness about 5,000 feet; Wading Branch Formation - Medium- to dark-gray sandy slate to coarse, pebbly feldspathic sandstone and graywacke; basal part is quartz-sericite phyllite; graded bedding common. Thickness about 1,500 feet.

Shirley Formation (Quaternary) at surface, covers < 0.1 % of this area

Shirley Formation (middle Pleistocene, Johnson and Berquist, 1989). Light- to dark-gray, bluish-gray and brown sand, gravel, silt, clay, and peat. Constitutes surficial deposits of riverine terraces and relict baymouth barriers and bay-floor plains (altitude 35-45 feet) inset below depositional surfaces of the Chuckatuck Formation (Johnson and Peebles, 1984). Upper part of unit is truncated on the east by the Suffolk and Harpersville scarps; locally, lower part occurs east and west of scarps. Fluvial-estuarine facies comprises (1) a lower pebble to boulder sand overlain by (2) fine to coarse sand interbedded with peat and clayey silt rich in organic material, including in-situ tree stumps and leaves and seeds of cypress, oak, and hickory, which grades upward to (3) medium- to thick-bedded, clayey and sandy silt and silty clay. Marginal-matrix facies in lower James River and lowermost Rappahannock River areas is silty, fine-grained sand and sandy silt containing Crassostrea virginica, Mulinia, Noetia, Mercenaria, and other mollusks. Astrangia from lower Rappahannock River area has yielded a uranium-series age of 184,000 ± 20,000 yrs B.P. (Mixon and others, 1982). Thickness is 0 to 80 feet.

Alluvium (Quaternary) at surface, covers < 0.1 % of this area

Fine to coarse gravelly sand and sandy gravel, silt, and clay, light- to medium-gray and yellowish-gray. Deposited mainly in channel, point-bar, and flood-plain environments; includes sandy deposits of narrow estuarine beaches, and mud, muddy sand, and peat in swamps and in fresh- and brackish-water marshes bordering tidewater rivers. Grades into colluvium along steeper valley walls at margins of unit. Mostly Holocene but, locally, includes low-lying Pleistocene (?) terrace deposits. As much as 80 feet thick along major streams.

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.

Metagabbro and minor metadiorite (Middle Paleozoic to Neoproterozoic) at surface, covers < 0.1 % of this area

Metagabbro and minor metadiorite

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

Very-light-gray, fine- to medium-grained crystal, lithic, and lithic-crystal andesitic metatuff with minor light-gray to white, fine-grained metasedimentary interbeds.

Biotite gneiss and muscovite-biotite gneiss (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Layered biotite-quartz-feldspar gneiss

Migmatitic granitoid gneiss (Ordovician) at surface, covers < 0.1 % of this area

Variably foliated, variably migmatitic, and granitic to quartz dioritic in composition

Mount Rogers Formation - Porphyritic felsite (Proterozoic Z) at surface, covers < 0.1 % of this area

Includes coarsely porphyritic felsite from the Pond Mountain volcanic center that could be a hypabys sal intrusive, and porphyritic rhyolite from the Razor Ridge volcanic center that is extrusive, as well as the Fees Rhyolite Member near the base of the formation.

Interlayered Mafic and Felsic Metavolcanic Rocks - Foliated felsite (Cambrian) at surface, covers < 0.1 % of this area

Foliated felsite; Heterogenous layered assemblage correlates with the Chopawamsic Formation and Ta River Metamorphic Suite, on strike to the northeast, and in traceable into the Milton belt in North Carolina (Geologic Map of North Carolina, 1985). Foliated felsite. Grayish-orange-pink to white, fine- to medium-grained, foliated to granular metavolcanic rocks range in composition from rhyolite to dacite. Includes muscovite feldspar- quartz schist, gneiss and granofels; massive crystal metatuff; welded ashflow tuff; and, inequigranular metavolcanic breccia. Relict primary volcanic textures are recognizable where metamorphic grade is low (Henika, 1975; 1977). This unit includes felsic gneiss with less common mafic and rare calcareous gneiss mapped by Tobisch (1972), in part the metamorphosed volcanic sequence of Gates (1981), and dominantly felsic-composition units mapped by Nelson (1992). The unit contains numerous granitic dikes, sills, and lit-par-lit injections where it occurs in close proximity to Shelton Formation (Ost). Felsites occur interlayered with amphibolite, amphibole gneiss and schist (Cmv), quartzofeldspathic biotite gneiss (Cbg), sillimanite-quartz-muscovite schist and gneiss (Csg), and ferruginous quartzite (Cfq).

Mylonite, Mylonite Gneiss, and Cataclastic Rocks (Proterozoic - Paleozoic ?) at surface, covers < 0.1 % of this area

Mylonite. Includes protomylonite, mylonite, ultramylonite, and cataclastic rocks. Lithology highly variable, depending on the nature of the parent rock, and on intensive parameters and history of deformation. In most mapped belts of mylonite and cataclastic rock (my), tectonized rocks anastomose around lenses of less-deformed or undeformed rock. In the Blue Ridge, some of these lenses are large enough to show at 1:500,000 scale. In many places mylonitic and cataclastic rocks are gradational into less deformed or undeformed adjacent rocks, and location of contacts between tectonized rocks (my) and adjacent units is approximate or arbitrary. These boundaries are indicated on the map by color-color joins with superimposed shear pattern. Most mapped belts of mylonite represent fault zones with multiple movement histories. In the Blue Ridge, Paleozoic age contractional deformation fabrics are superimposed on Late Precambrian extensional fabrics (Simpson and Kalaghan, 1989; Bailey and Simpson, 1993). Many Piedmont mylonite zones contain dextral-transpressional kinematic indicators that formed during Late Paleozoic collision al tectonics (Bobyarchick and Glover, 1979; Gates and others, 1986). Paleozoic and older faults were reactivated in many places to form extensional faults during the Mesozoic (Bobyarchick and Glover, 1979).

Tuffaceous metasiltstone (Early Paleozoic-Neoproterozoic) at surface, covers < 0.1 % of this area

Tuffaceous metasiltstone

Sillimanite-mica schist and muscovite-biotite schist (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Thin to thick layered sillimanite-mica schist and sillimanite-bearing muscovite-biotite schist

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

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

Interlayered Mafic and Felsic Metavolcanic Rocks - Quartz-muscovite schist and gneiss. (Cambrian) at surface, covers < 0.1 % of this area

Quartz-muscovite schist and gneiss; Heterogenous layered assemblage correlates with the Chopawamsic Formation and Ta River Metamorphic Suite, on strike to the northeast, and in traceable into the Milton belt in North Carolina (Geologic Map of North Carolina, 1985). Quartz muscovite schist and gneiss. Very-light-gray to light-bluish-gray, fine- to medium-grained, layered kyanite mica schist, kyanite and sillimanite quartzite, and interlayered biotite-garnet schist. Mineralogy: quartz + muscovite + plagioclase ± biotite ± garnet ± sillimanite ± kyanite ± magnetite. Includes the schist and gneiss unit of Tobisch (1972), and muscovite-quartz schist of Baird (1989, 1991).

Virgilina Greenstone (Proterozoic Z) at surface, covers < 0.1 % of this area

Virgilina greenstone (Laney, 1917). Grayish-green, fine- to coarse-grained basaltic tuff, metavolcanic breccia, and porphyritic to amygdaloidal greenstone, with minor interlayered metasedimentary rocks. Hydrothermally mineralized zones occur within the greenstones; these contain bornite, chalcocite, and chalcopyrite, and have been mined for copper. Mineralogy: plagioclase + hornblende + chlorite + epidote + calcite + apatite + quartz + opaque minerals. Geophysical signature: linear positive magnetic anomaly. Watson (1911) used the term Virgilina Group for a wide belt of rocks in the vicinity of Virgilina, Virginia. Mafic metavolcanic rocks in this sequence were named Virgilina greenstone, and felsic metavolcanic rocks and associated metasedimentary rocks were named Aaron slate by Laney (1917). Kreisa (1980) refined Laney's stratigraphy in defining the Aaron Formation as containing upper and lower members equivalent to Laney's Aaron slate, and a middle member equivalent to the Virgilina greenstone. The stratigraphy was further modified by Harris and Glover (1985), who combined the middle and upper members of Kreisa's Aaron Formation to make the Virgilina Formation. Virgilina greenstone is herein used in the sense of Laney (1917), but is equivalent to the middle member of the Aaron Formation of Kreisa (1980), and the lower portion of the Virgilina Formation of Harris and Glover (1985) (Figure 2).

Gabbro - Mecklenburg pluton (Devonian to Silurian) at surface, covers < 0.1 % of this area

Gabbro - Mecklenburg pluton

Chatham Group, undivided (Triassic) at surface, covers < 0.1 % of this area

Conglomerate, sandstone and mudstone

Elk Park Plutonic Group - Biotite quartz monzonite (Proterozoic Y) at surface, covers < 0.1 % of this area

Elk Park Plutonic Group (Yep, Yec; Rankin and others, 1972; 1973) Includes augen gneiss and porphyritic gneiss (Yep), and equigranular quartz monzonite, quartz monzonite flaser gneiss, and quartz monzonite gneiss (Yec). Rocks range in composition from diorite to quartz monzonite; most are quartz monzonite in which the primary dark mineral is biotite, with or without hornblende; epidote and titanite are common accessory minerals. Porphyritic rocks contain microcline phenocrysts. Augen gneiss was probably derived from porphyritic plutonic rocks by shearing. This unit includes in part the Little River Gneiss of Dietrich (1959) and Cranberry Gneiss (Rankin and others, 1972; 1973). U-Pb zircon data from the Cranberry has been interpreted to signify ages of 1050 Ma (Davis and others, 1962) and 1080 Ma (Rankin and others, 1969).

Phyllonite and phyllonitic schist (Late Paleozoic) at surface, covers < 0.1 % of this area

Phyllonite and phyllonitic schist

Felsic metavolcanic rocks and felsic gneiss interpreted to the metavolcanics (Ordovician to Neoproterozoic) at surface, covers < 0.1 % of this area

Felsic metavolcanic rocks and felsic gneiss interpreted to the metavolcanics

Granite gneiss (Silurian to Ordovician) at surface, covers < 0.1 % of this area

Equigranular to inequigranular granite gneiss and augen gneiss, undivided

Roan Gneiss (Precambrian) at surface, covers < 0.1 % of this area

Layered hornblende and garnet gneiss and granitic migmatite with zones of mica schist and amphibolite, foliation commonly contorted; contains numerous granitic and gabbroic dikes.

Metadiorite (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Metadiorite

Granite (Proterozoic) at surface, covers < 0.1 % of this area

Light-gray to pink, fine- to medium-grained granite and granodiorite; zoned plagioclase crystals with epidotized and saussuritized cores are characteristic. The granite contains xenoliths of mafic volcanic rocks near its margins. The granite intrudes volcanic rocks east of the Hollister fault zone southeast of Petersburg. Samples from the quarry at Skippers were dated by Rb-Sr whole-rock methods (Bottino and Fullagar, 1968); these data show considerable scatter, implying age of crystallization ranging from 460 Ma to as old as 690 Ma. This unit was shown as Petersburg Granite on the 1963 Geologic Map of Virginia, but field relations, petrology, and the apparent age indicate that it is a separate pluton.

Diorite and Quartz Diorite (Proterozoic) at surface, covers < 0.1 % of this area

Diorite, gray, fine- to medium-grained, well-foliated, locally trondhjemitic; composition locally grades into granodiorite; quartz diorite, white to gray, fine- to medium-grained, massive to layered, foliated. Mineralogy: plagioclase + quartz + biotite + amphibole + epidote.

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

Dark greenish-gray, silty and sandy, micaceous shale; numerous layers of medium-grained, feldspathic, thinly bedded sandstone. Thickness 500 to 2,000 feet.

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

Megacrystic, well foliated, locally contains hornblende; Fountain intrusive.

Socastee Formation (Pleistocene) at surface, covers < 0.1 % of this area

Low coastal formation in Carolinas like Penholoway but younger and lower in altitude.

Megacrystic biotite gneiss (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Variably layered biotite-quartz-feldspar gneiss having porphyroclasts and/or porphyroblasts of plagioclase and locally of quartz and potassium feldspar

Porphyroblastic Biotite Granite (Proterozoic) at surface, covers < 0.1 % of this area

Light-gray, medium to coarse-grained, compositionally layered, well-foliated, commonly lineated gneiss composed of metamorphosed granite, leucogranite, and granodiorite, which locally contains feldspar megacrysts. This unit includes the granite at Lawrenceville; the rocks are variably mylonitic and lineated along the Lake Gordon mylonite zone near Kenbridge (Horton and others, 1993).

Garnetiferous mica schist (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Aluminous muscovite-biotite schist, locally having subordinate amphibolite layers

Rich Butt Sandstone (Precambrian) at surface, covers < 0.1 % of this area

Gray, massive beds of feldspathic, fine- to medium-grained sandstone, with interbeds of dark slate and arkosic conglomerate; exact stratigraphic position unknown. Thickness about 1,500 feet.

Battleground Formation, Metasedimentary rocks, undivided (Neoproterozoic) at surface, covers < 0.1 % of this area

Quartz-sericite schist/phyllite and interlayered quartzite, quartz-pebble conglomerate, high-alumina quartzite, and manganiferous schist

Chesapeake Group (Tertiary) at surface, covers < 0.1 % of this area

May include the following fomations - Chowan River, Yorktown, Eastover, St. Marys, Choptank, and Calvert. Chesapeake Group (upper Pliocene to lower Miocene,Darton, 1891). Fine-to coarse-grained, quartzose sand, silt, and clay; variably shelly and diatomaceous, deposited mainly in shallow, inner- and middle-shelf waters. Ages of units based on studies of foraminiferal, nannofossil, diatom, and moluscan assemblages in Virginia and adjacent states (Andrews, 1988; Gibson, 1983; Gibson and others, 1980; Poag, 1989; Ward and Blackwelder, 1980; Ward and Krafft, 1984). Includes the following formations, from youngest to oldest: Chowan River Formation (upper Pliocene, Blackwelder, 1981). Gray to dusky-blue-green sand, fine- to medium-grained, clayey and silty, commonly very shelly; grades laterally into laminated, silty clay and upward into cross-bedded, biofragmental sand, clayey silt, and silty clay. Discontinuous pebbly to bouldery sand at very irregular base of unit. Mollusks include Glycymeris hummi, Noetia carolinensis, and Carolinapecten eboreus bertiensis. Thickness is 0 to 50 feet. Recognized only in southeasternmost Virginia and North Carolina. Yorktown Formation (lower upper Pliocene to lower Pliocene, Clark and Miller, 1906). Bluish-gray and brownish-yellow sand, fine- to coarse-grained, in part glauconitic and phosphatic, commonly very shelly, interbedded with sandy and silty blue-gray clay. In lower York and James River basins, unit includes cross-bedded shell hash. Mollusks in clude Glycymeris subovata, Chesapecten jeffersonius, Chesapecten madisonius, Mercenaria tridacnoides, Panopea reflexa. Coarse-grained sand and gravel facies of the Yorktown in updip areas is mapped separately as unit psg. Thickness is 0 to 150 feet. Eastover Formation (upper Miocene, Ward and Blackwelder, 1980). Dark-gray to bluish-gray, muddy sand, very fine to fine, micaceous, interbedded with sandy silt and clay. Lower part of unit is dominantly medium- to very-thin-bedded and laminated silt and clay interbedded with very-fine sand, lenticular and wavy bedding common; upper part is mainly very-fine- to fine-grained sand containing abundant clay laminae. Typical mol lusks include Chesapecten middlesexensis, Marvacrassatella surryensis, Glossus fraterna. Thickness is 0 to 270 feet. St. Marys Formation (upper and middle Miocene, Shattuck, 1902). Bluish- to pinkish-gray, muddy, very-fine sand and sandy clay-silt, locally abundantly shelly. Chesapecten santamaria, Buccinofusus parilis, and Ecphora gardnerae are characteristic mollusks. Occurs northeast of Mattaponi River. Thickness is 0 to 40 feet. Choptank Formation (middle Miocene, Shattuck, 1902). Olive-gray sand, fine to very-fine, clayey and silty, shelly, and diatomaceous clay-silt; common y forms fining-upward sequences. Mollusks include Chesapecten nefrens, Mercenaria cuneata, Ecphora meganae. Thickness is 0 to 50 feet. Calvert Formation (middle and lower Miocene, Shattuck, 1902). Commonly consists of 2 to 7 fining-upward sequences. Each sequence includes a light- to dark-olive-gray basal sand, very fine to fine, clayey and silty, very sparsely to abundantly shelly; grades upward to sandy, diatomaceous clay-silt and diatomite. Typical molluscs include Chesapecten coccymelus, Crassatella melinus, Ecphora tricostata. Thickness is 0 to 600 feet.

Mount Rogers Group including Bakersville Gabbro, Beech Granite, Cranberry Granite, and Roan Gneiss (Precambrian) at surface, covers < 0.1 % of this area

Mount Rogers Group - Metavolcanics, typically purplish and reddish; massive lavas and tuffs, altered rhyolites and quartz latites; strongly foliated; interbedded arkose, shale, and conglomerate. Thickness 1,000 to 3,000 feet; Includes Bakersville Gabbro - Metagabbro, dark, porphyritic; contains diorite, basalt, anorthosite, and diabase; occurs as thin to massive dikes and lenticular masses; Beech Granite - Granite, porphyritic, light-gray to reddish; coarse potash feldspar crystals and clustered interstitial mafics (chloritized biotite and hornblende) give spotted appearance; includes Max Patch Granite; Cranberry Granite - Complex of intertonguing rock types including migmatite, granitic gneisses, monzonite, quartz diorite, greenstone, mica and hornblende schists, abundant granitic pegmatite; and Roan Gneiss - Layered hornblende and garnet gneiss and granitic migmatite with zones of mica schist and amphibolite, foliation commonly contorted; contains numerous granitic and gabbroic dikes.

Marsh and Intertidal Mud Deposits (Quaternary) at surface, covers < 0.1 % of this area

Medium to dark-gray soft mud, and grayish-brown peat, comprising sediment of marshes in coastal areas and Chesapeake Bay; thickness is 0 to 10 feet. Also, sandy mud and muddy fine sand, light- to dark-gray. Locally, contains abundant shell material characterized by Crassostrea virginica and Mercenaria mercenaria. Comprises sediments of shallow bays and flats in area of Atlantic coastal lagoons of the Eastern Shore.

Caesars Head Granite (Ordovician to Silurian) at surface, covers < 0.1 % of this area

Well foliated, banded to non-banded biotite granitoid gneiss or gneissic granitoid; cuts Seneca thrust fault

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

Heterogeneous layered metavolcanic sequence includes crystal and lithic tuff, dacite porphyry, chert, phyllite, and greenstone metabasalt; greenschist-facies metamorphic mineral assemblages occur in the various lithologies. This unit correlates with the Roanoke Rapids volcanogenic complex of the eastern slate belt in North Carolina (Farrar, 1985a, 1985b; Geologic Map of North Carolina, 1985; Horton and Stoddard, 1986). To the extent that correlation with lithologically similar Carolina slate belt rocks is valid, mafic and felsic metavolcanic rocks (v) are Late Proterozoic to Cambrian in age.

Interlayered Mafic and Felsic Metavolcanic Rocks - Amphibolite, hornblende-biotite gneiss, and schist. (Cambrian) at surface, covers < 0.1 % of this area

Amphibolite, hornblende-biotite gneiss, and schist.; Heterogenous layered assemblage correlates with the Chopawamsic Formation and Ta River Metamorphic Suite, on strike to the northeast, and in traceable into the Milton belt in North Carolina (Geologic Map of North Carolina, 1985). Amphibolite, hornblende-biotite gneiss and schist. Black to moderate-olive-brown, medium- to coarse-grained, lineated and foliated; light-greenish-gray quartz-epidote stringers are common. Mineralogy: hornblende + tremolite-actinolite + oligoclase + biotite + epidote + garnet. Includes Blackwater Creek Gneiss and Catawba Creek amphibolite member of Hyco Formation of Baird (1989), hornblende gneiss of LeGrand (1960), gneiss unit of Kreisa (1980), and dominantly mafic-composition units mapped by Nelson (1992). Amphibolite is interlayered with biotite gneiss, as discussed above.

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

Rich Acres Formation (Conley and Henika, 1973; Conley, 1985). Dikes, sills, and irregularly-shaped plutons of dark-greenish-gray, medium-grained, locally porphryitic, biotite-hornblende gabbro. Mineralogy: plagioclase + clinopyroxene + orthopyroxene + hornblende + biotite + magnetite + quartz + rutile + apatite + zircon + epidote + calcite + pyrite + titanite; plagioclase is altered to epidote; pyroxenes are altered to uralite. Outer parts of some plutons are injected with thin veins composed of hornblende + plagioclase, and hornblende + pyroxene + plagiocase, and with quartz-microcline-oligoclase pegmatite. The unit includes small, irregularly-shaped plutons of porphyritic norite composed of 1- to 4-cm orthopyroxene and clinopyroxene and 1-cm plagioclase laths in ophitic texture, hornblende, biotite, and olivine. The Rich Acres is part of the Martinsville igneous complex of Ragland (1974).

Diorite Gneiss (Proterozoic) at surface, covers < 0.1 % of this area

White to gray, fine- to medium grained, massive to layered quartz diorite gneiss, contains minor biotite and epidote; lenses of gray to black, medium-grained, layered hornblende-plagioclase gneiss and quartz-epidote clinopyroxene- hornblende-plagioclase gneiss occur locally (Tobisch, 1972).

Buggs Island Pluton (Mississippian Pennsylvanian) at surface, covers < 0.1 % of this area

Light-gray, medium- to coarse grained, massive to strongly foliated biotite-muscovite granite. The name first appears in the literature as the Buggs Island granite gneiss (Kish and Fullagar, 1978); those workers report an Rb-Sr whole-rock age of 314±16 Ma.

Alluvial Valley Swamp (Quaternary) at surface, covers < 0.1 % of this area

Unconformable on all underlying units, fluvial sand and gravel at base, grading upwards into fine sands and silts, local peat. May be overrun with recent sediments from forest cutting and agriculture.

Pliocene Sand and Gravel (Tertiary) at surface, covers < 0.1 % of this area

Interbedded yellowish-orange to reddish-brown gravelly sand, sandy gravel, and fine to coarse sand, poorly to well-sorted, cross-bedded in part, in cludes lesser amounts of clay and silt in thin to medium beds. Commonly caps drainage divides (altitude 250-170 feet) in western part of Coastal Plain. Lower part of unit, showing flaser and lenticular bedding and containing rare to abundant Ophiomorpha nodosa represents deposition in marginal-marine environments and is, in part, a nearshore equivalent of the more downdip, marine facies of the Yorktown Formation. In the northern part of the Coastal Plain, the more poorly sorted and less cleanly washed upper part of unit, which lacks fossils, comprises fluvial-deltaic sediments that prograded eastward across the shelf during a regressive phase of the Yorktown. To the south, the upper part of unit is massively bedded clayey sand in places containing heavy mineral concentrations that average 8 percent or more; the sands are nearshore, beach and dune origin; interstitial clay was derived, in part, from in-situ weathering of feldspar sand. Thick ness is 0 to 50 feet.

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

Dark-gray to black, biotite- and pyrite-rich volcaniclastic rock interbedded with medium-gray, fine-grained rocks with numerous quartzfilled vesicles; upper part of the unit consists of medium dark-gray, fine-grained felsic rock with numerous clasts of fine-grained, white-weathering, vesiculated felsite interlayered with fine-grained, clast-free felsic rock. Dikes of clast-free felsic rock cut nearby Middle Proterozoic granitic gneiss (Ybp); conformably overlain by feldspathic metasandstones of the Fauquier Formation.

Charles City Formation (Quaternary) at surface, covers < 0.1 % of this area

Charles City Formation (lower Pleistocene (?), Johnson and Berquist, 1989). Light- to medium-gray and light-to dark yellowish and reddish-brown sand, silt, and clay composing surficial deposits of riverine terraces and coast-parallel plains at altitiudes of 70 to 80 feet. Unit is adjacent to, and inset below, the Windsor Formation and older deposits. Bay or shallow shelf facies of the Charles City (Johnson and Peebles, 1984), present beneath flat to gently seaward-sloping plain in Suffolk area, includes a thin, basal, gravelly sand grading upward into fine- to medium-grained sand and an uppermost clayey and sandy silt; lower and middle parts of unit contain clay-lined, sand-filled burrows. Fluvial-estuarine facies in terrace remnants along major rivers consists of cross-bedded gravelly sand and clayey silt. Thickness is 0 to 55 feet, or more.

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

Fork Mountain Formation (Conley and Henika, 1973; Conley, 1985). Light- to medium-gray, fine- to medium grained, polydeformed and polymetamorphosed porphyroblastic aluminosilicate-mica schist, interlayered with medium-gray irregularly-layered garnetiferous biotite gneiss, migmatitic in part; calcsilicate granofels; amphibolite; rare white marble; and, coarse calc-quartzite lenses. Complex schistosity, multiple crenulation cleavages, and partly-retrograded, polymetamorphic aluminosilicate and garnet porphyroblasts are diagnostic of Fork Mountain schists. Primary sedimentary structures rarely are preserved. A spectacular polymictic breccia bed that can be traced along strike for several miles within the Fork Mountain near Stuart is a notable exception. Medium- to coarse-granular, blue quartz lenses, angular to rounded inclusions of boudinaged fine-grained, color-laminated, calc-silicate rock, and thick beds of coarse, clast-supported, epidotized lithic breccia are typical of the Fork Mountain biotite gneiss. Prograde regional metamorphic mineral assemblages: (1) quartz + muscovite + biotite + garnet + staurolite + magnetite- ilmenite + rutile; (2) quartz + muscovite + paragonite + plagioclase + garnet + staurolite + sillimanite + magnetite-ilmenite + rutile; (3) quartz + biotite + sillimanite + potassium feldspar + plagioclase + garnet + magnetite-ilmenite; (4) quartz + plagioclase + biotite + muscovite + sillimanite + garnet + tourmaline; (5) quartz + plagioclase + potassium feldspar + biotite + hornblende + epidote + ilmenite; (6) quartz + plagioclase + potassium feldspar + muscovite + biotite + sillimanite + magnetite-ilmenite + garnet + kyanite. Retrograde metamorphic mineral assemblages: (1) quartz + muscovite + chlorite; (2) quartz + muscovite + chloritoid + chlorite; (3) quartz + muscovite + staurolite + chloritoid; (4) quartz + muscovite + kyanite. Contact metamorphic mineral assemblages: (1) andalusite + sillimanite + kyanite + corundum; (2) corundum + spinel + magnetite + kyanite. Geophysical signature: The Fork Mountain has a characteristic "curly maple" pattern on magnetic contour maps. This pattern is the result of isolated concentrations of highly magnetic minerals that produce rounded, high-intensity, positive and negative anomalies. The aluminosilicate-mica schist is the upper part of the Fork Mountain Formation and forms a series of northeastward-trending ridges along the northwest side of the Smith River allochthon. The garnetiferous biotite gneiss is at a lower structural level of the Fork Mountain Formation near Martinsville where lower strata have been intruded by the Martinsville igneous complex, and the remaining metasedimentary rocks contain extensive thermal meta mor phic zones locallized along the intrusive contacts (Conley and Henika, 1973). Biotite gneiss in the Fork Mountain Formation has been interpreted to be a highly metamorphosed diamictite (Rankin, 1975; Conley, 1985; and Pavlides, 1989). At the northeastern limit of the Fork Mountain outcrop belt, in Appomattox and Buckingham counties, the dominant lithologies are polydeformed yellowish-gray chloritoid-chlorite- muscovite quartzose phyllite and quartz-rich mica schist. Tightly-folded, transposed pinstriped segregation layering at a high angle to the penetrative schistosity defined by phyllosilicate minerals is characteristic; polycrystalline quartz-rich boudins are abundant. These rocks are lithologically indistinguishable from those along the highly-tectonized western margin of the metagraywacke, quartzose schist, and melange (CZpm) outcrop belt; current interpretation is that the Fork Mountain is correlative to some degree with CZpm.

Hornblende-plagioclase Gabbro (Proterozoic) at surface, covers < 0.1 % of this area

Dark-grayish-green, coarse- to medium-grained, massive to foliated metagabbro. Mineralogy: amphibole + plagioclase + clinopyroxene + quartz + biotite + muscovite + epidote ± magnetite. Geophysical signature: small circular positive magnetic anomalies. Plutons of these gabbros intrude interlayered mafic and felsic metavolcanic rocks.

Leatherwood Granite (Cambrian) at surface, covers < 0.1 % of this area

Leatherwood Granite (Jonas, 1928; Pegeau, 1932; Conley, 1985). Light-gray, medium- to coarse-grained, porphyritic biotite granite generally shows rapakivi texture. Mineralogy: quartz + potassium feldspar + plagioclase + biotite + muscovite + epidote + apatite + titanite + zircon + mag ne tite. Geophysical signature: positive radiometric, negative magnetic. The major part of the Leatherwood occurs as sheets at the top of the Martinsville igneous complex. Leatherwood Granite and associated Rich Acres gabbro are cut by dikes of dark-gray, coarse-grained, porphyritic olivine norite. The Leatherwood was dated at 450 Ma (U-Pb zircon; Rankin, 1975); 464±20 Ma (Rb-Sr whole-rock, Odom and Russell, 1975); and 516 Ma (U-Pb zircon; Sinha and others, 1989).

Bakersville Gabbro (Precambrian) at surface, covers < 0.1 % of this area

Metagabbro, dark, porphyritic; contains diorite, basalt, anorthosite, and diabase; occurs as thin to massive dikes and lenticular masses.

Windsor Formation (Tertiary-Quaternary) at surface, covers < 0.1 % of this area

Windsor Formation (lower Pleistocene or upper Pliocene, Coch, 1968). Gray and yellowish- to reddish-brown sand, gravel, silt, and clay. Constitutes surficial deposits of extensive plain (altitude 85-95 feet.) seaward of Surry scarp and of coeval, fluvial-estuarine terraces west of scarp. Fining upward sequence beneath plain consists of a basal pebbly sand grading upward into cross-bedded, quartzose sand and massive, clayey silt and silty clay; lower and upper parts of sequence were deposited, respectively, in shallow-marine or open-bay and restricted-bay or lagoonal environments. In terraces west of Surry scarp, fluvial-estuarine deposits comprise muddy, coarse, trough cross-bedded sand and gravel grading upward to sandy silt and clay. Thickness is 0 to 40 feet.

Henderson Gneiss (Cambrian) at surface, covers < 0.1 % of this area

Biotite granitoid augen gneiss having distinctive microcline augen; monzonite to granodiorite composition

Duplin Formation (Pliocene) at surface, covers < 0.1 % of this area

Coastal terrace of Carolinas. Pliocene equivalent to Yorktown. Deeply weathered.

Metavolcanic rocks, interlayered felsic to mafic, undivided (Ordovician to Neoproterozoic) at surface, covers < 0.1 % of this area

Metavolcanic rocks, interlayered felsic to mafic, undivided

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

White, vitreous quartzite, massive, with interbeds of dark-green silty and sandy shale, minor siltstone, and very fine-grained sandstone. Thickness 1,000 to 1,500 feet.

Alligator Back Formation - Feldspathic metagraywacke (Proterozoic Z-Cambrian) at surface, covers < 0.1 % of this area

Heterogeneous assemblage of rock-types includes medium- to light-gray, laminated quartzofeldspathic to calcareous gneiss with thin mica schist partings; white and gray, fine- to coarse-grained, generally laminated marble; gray to greenish-gray fine-grained graphitic mica schist and quartzite; light-gray, medium- to fine-grained mica schist; massive quartzite and micaceous blue quartz granule metasandstone; and, dark-greenish-black actinolite schist. Mineralogy: (1) quartz + potassium feldspar + pla ioclase + biotite + muscovite + calcite + epidote + titanite + magnetite- ilmenite; (2) quartz + muscovite + chlorite + graphite + titanite + ilmenite; (3) quartz + albite + muscovite + biotite + titanite + ilmenite; (4) quartz + mus co vite + garnet + kyanite; (5) chlorite + tremolite + magnetite-ilmenite; (6) chlorite + actinolite-tremolite + talc + dolomite + magnetite-ilmenite; (7) quartz + albite + actinolite + biotite + epidote + magnetite. Units here mapped as Alligator Back Formation were previously mapped as the Evington Group (Espenshade, 1954; Brown, 1958; Redden, 1963; Gates, 1986; Patterson, 1987) and considered to be younger than the Lynchburg Group. Regional mapping by Henika (1991) and Scheible (1975) indicates that rocks assigned to Alligator Back Formation by Rankin and others (1973) are continuous with the upper part of the Lynchburg Group in the type section along the James River at Lynchburg (Jonas, 1927) and that the Alligator Back consistently dips southeast beneath the overlying Candler Formation from the Virginia-North Carolina border to the James River at Lynchburg. Sedimentary and structural facing criteria indicate that rock units immediately southeast of the Candler Formation in an outcrop belt from Stapleton on the James River, southwest to Leesville Dam on the Roanoke River, are older than the Candler (Henika, 1992). Although previously mapped as upper Evington Group (Espenshade, 1954; Brown, 1958; Redden, 1963; Patterson, 1987), these rocks are herein correlated with the Alligator Back Formation (upper Lynchburg Group), having been uplifted against the Candler Formation to the northwest along the Bowens Creek fault (Henika, 1992). Rocks in the same outcrop belt along strike to the southwest of the Leesville Reservoir were previously correlated with the Alligator Back Formation by Conley (1985). The sequence of lithologic units within the Alligator Back Formation southeast of the Bowens Creek fault is the same as that proposed by Brown (1951; 1958), and Espenshade (1954) for the formations in the Evington Group, that are structurally above the Candler Formation. The sequence is based on the detailed structural and stratigraphic relationships first established by Brown (1958) in the Lynchburg 15-minute quadrangle.

Peedee Formation - Black Creek Group, undivided (Cretaceous) at surface, covers < 0.1 % of this area

Peedee Formation - Black Creek Group, undivided

Biotite Gneiss (Precambrian-Paleozoic) at surface, covers < 0.1 % of this area

Biotite gneiss

Tabb Formation; Poquoson Member (Quaternary) at surface, covers < 0.1 % of this area

Poquoson Member (Johnson, 1976). Medium to coarse, pebbly sand grades upward into clayey fine sand and silt, light- to medium-gray; underlies ridge and swale topography (altitude ranges from sea level to 11 feet) along the margin of Chesapeake Bay and in the lower and middle parts of Coastal Plain rivers. Thickness is 0 to 15 feet.

Phyllite and Metasiltstone (Proterozoic Z) at surface, covers < 0.1 % of this area

Dominantly light-gray, schistose chlorite-sericite phyllite and phyllitic metasiltstone with a well-developed phyllitic or slaty cleavage; includes minor interlayered mafic and felsic metavolcanic rocks.

Aaron Slate (Proterozoic Z) at surface, covers < 0.1 % of this area

Metaconglomerate (Kreisa, 1980). Metamorphosed sandy conglomerate, conglomeratic sandstone, and granule conglomerate containing pebbles and cobbles of polycrystalline quartz, with lesser diorite, diabase, chert, rhyolite, granite, schist, and quartz arenite. Cobbles are generally less than 2 cm but may range up to 25 cm in diameter (Kreisa, 1980). Unit occurs as beds of 0.3 to 6.1 meters thickness at base of and locally within the lower portion of Aaron section. Aaron slate (Zas) and metaconglomerate (Zac) herein includes the upper and lower members of the Aaron Formation of Kreisa (1980), and the Aaron Formation and upper portion of the Virgilina Formation of Harris and Glover (1985).

Mount Rogers Formation - Greenstone with interbedded sedimentary rocks (Proterozoic Z) at surface, covers < 0.1 % of this area

Greenstone with interbedded sedimentary rocks; relict plagioclase phenocrysts are prominent in some greenstone.

Sandsuck Formation (Precambrian) at surface, covers < 0.1 % of this area

Olive-green and gray, argillaceous, micaceous shale with coarse feldspathic sandstone and quartz- pebble conglomerate. Thickness about 2,000 feet.

Beach Sand and Dune Sand Deposits (Quaternary) at surface, covers < 0.1 % of this area

Pale-gray to light-yellowish gray, fine to coarse, poorly sorted to well-sorted, shelly in part; contains angular to rounded fragments and whole valves of mollusks. Comprises deposits of coastal barrier islands and narrow beach dune ridges bordering brackish-water marshes of Chesapeake Bay. Thickness is as much as 40 feet.

Tabb Formation; Lynnhaven Member (Quaternary) at surface, covers < 0.1 % of this area

Lynnhaven Member (Johnson, 1976). Pebbly and cobbly, fine to coarse gray sand grades upward into clayey and silty fine sand and sandy silt; locally, at base of unit, medium to coarse cross-bedded sand and clayey silt containing abundant plant material fill channels cut into underlying stratigraphic units. Unit is surficial deposit of broad swale that is traceable southward from Norfolk; extensive low lands bounded on landward side by river-, bay-, and ocean-facing scarps having toe altitudes of 15 to 18 feet. Thickness is 0 to 20 feet.

Waxhaw metagranite (Ordovician to Cambrian) at surface, covers < 0.1 % of this area

Metamorphosed fine- to medium-grained biotite granite and hypabyssal quartz porphyry, non-foliated except adjacent to Gold Hill and Waxhaw shear zones where it is gneissic to phyllonitic

Granite (Carboniferous to Permian) at surface, covers < 0.1 % of this area

Granite

Bassett Formation - Biotite gneiss and granite gneiss. (Proterozoic Z) at surface, covers < 0.1 % of this area

Light-gray to black-and-white, fine to medium-grained, leucocratic biotite gneiss that is mostly segregation-layered, but locally is a medium-grained quartzfeldspar granofels. Contains interlayers of muscovite-biotite schist, quartz schist, and epidote quartzite. Mineral assemblages: (1) quartz + plagioclase + potassium feldspar + biotite + muscovite + magnetite-ilmenite + tourmaline ± kyanite ± epidote ± titanite ± hornblende ± garnet; (2) quartz + plagioclase + epidote + pyroxene. Porphyroclasts of zoned plagioclase in an equigranular, polygonal quartz-potassium feldspar groundmass and medium to thick bedding suggest a volcaniclastic protolith (Conley, 1985). Gneisses are migmatitic and cut by numerous granite dikes and sills near the contacts with the Martinsville igneous complex. Geophysical signature: potassium feldspar-bearing gneisses have positive radiometric, and generally flat magnetic signatures relative to adjacent amphibolite units. In the core of the Sherwill anticline (Campbell and Appomattox counties), the dominant rock-type is graded salt-andpepper metagraywacke, interbedded with lesser mica schist and graphite schist. This association bears lithologic affinity to the Lynchburg Group, which occupies the cores of structural domes to the west; this correlation has been made by several workers (Brown, 1958; Kaldy, 1977; Gates, 1987).

Metatonalite (Proterozoic) at surface, covers < 0.1 % of this area

White to light-gray, medium- to coarse-grained, faintly foliated, locally porphyritic; ranges from granodiorite to quartz diorite. Mineralogy: quartz + plagioclase + biotite + microcline. This unit includes the Vance pluton of Horton and others (1993), dated at 571±17 Ma (U-Pb zircon; LeHuray, 1989).

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

Dark-greenish-gray to black-and-white, medium- to coarse-grained, layered to massive hornblende schist, hornblende gneiss, amphibolite, garnet-pyroxene granofels, and coarse uralitic hornblende metagabbro. Mafic rocks are interlayered with white to light-gray, medium- to coarse-grained quartz-feldspar granofels, and cut by alaskite and pegmatite dikes and sills. Ovoid masses of quartz, plagioclase, epidote and quartz that resemble flattened amygdules, and features that resemble graded bedding and cut-and-fill structures suggest a mixed volcanic-volcaniclastic protolith (Conley and Henika, 1970). Mineral assemblages: (1) hornblende + plagioclase + quartz + pyroxene + garnet + epidote + magnetite + titanite; (2) diopside + grossular + plagioclase + magnetite + quartz + epidote; (3) hornblende + plagioclase + potassium feldspar + quartz + epidote. Geophysical signature: Narrow, positive magnetic anomalies closely parallel amphibolite outcrops belts.

Tabb Formation; Sedgefield Member (Quaternary) at surface, covers < 0.1 % of this area

Sedgefield Member (Johnson, 1976). Pebbly to bouldery, clayey sand and fine to medium, shelly sand that grades upward into sandy and clayey silt; locally channel fill at base of unit includes as much as 50 feet of fine to coarse, cross-bedded sand and clayey silt and peat containing in-situ tree stumps. Sandy bay facies commonly contains Crassostrea biostromes, Mercenaria, Anadara, Polynices, Ensis, and other mollusks. Specimens of the coral Astrangia have yielded estimated uranium-series ages averaging 71,000 ± 7,000 yrs B.P. (Mixon and others, 1982). Unit constitutes surficial deposit to river and coast-parallel plains (altitude 20-30 feet) bounded on landward side by Suffolk and Harpersville scarps. Thickness is 0 to 50 feet.