Geologic units in Caldwell county, North Carolina

Additional scientific data in this geographic area

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 27 % 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.

Mica Schist (Cambrian/Late Proterozoic) at surface, covers 16 % 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.

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 13 % 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.

Migmatitic Granitic Gneiss (Ordovician/Cambrian) at surface, covers 12 % of this area

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

Blowing Rock Gneiss (Middle Proterozoic) at surface, covers 8 % 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.

Alligator Back Formation; Gneiss (Late Proterozoic) at surface, covers 7 % of this area

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

Grandfather Mountain Formation; Felsic metavolcanic rocks and metasedimentary rocks (Late Proterozoic) at surface, covers 5 % of this area

Tentatively correlated with Grandfather Mountain Formation.

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

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

Grandfather Mountain Formation; Metagraywacke (Late Proterozoic) at surface, covers 2 % of this area

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

Alligator Back Formation; Mica schist and phyllite (Late Proterozoic) at surface, covers 2 % of this area

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

Megacrystic Biotite Gneiss (Cambrian/Late Proterozoic) at surface, covers 2 % of this area

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

Metamorphosed Granite (Late Proterozoic) at surface, covers 1 % of this area

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

Inequigranular Biotite Gneiss (Cambrian/Late Proterozoic) at surface, covers 1.0 % of this area

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

Henderson Gneiss (Cambrian) at surface, covers 0.9 % of this area

Monzonitic to granodioritic; inequigranular.

Grandfather Mountain Formation; Porphyritic felsic volcanic rock (Late Proterozoic) at surface, covers 0.5 % of this area

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

Linville Metadiabase (Late Proterozoic) at surface, covers 0.4 % of this area

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

Quartz Diorite to Granodiorite (Devonian) at surface, covers 0.3 % of this area

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

Grandfather Mountain Formation; Greenstone (Late Proterozoic) at surface, covers 0.2 % of this area

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

Rocks of Brevard Fault Zone (Uncertain, possibly Permian or Devonian) at surface, covers 0.2 % of this area

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

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.

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.