USGS - science for a changing world

Mineral Resources On-Line Spatial Data

Mineral Resources > Online Spatial Data > Geology > by state

Geologic units containing phyllite

Earth material > Metamorphic rock
Phyllite
A metamorphosed rock, intermediate in grade between slate and mica schist. Minute crystals of graphite, sericite, or chlorite impart a silky sheen to the surfaces of cleavage (or schistosity).
Subtopics:
(none)

Alabama - Arizona - California - Colorado - Connecticut - Georgia - Idaho - Massachusetts - Maryland - Maine - Minnesota - North Carolina - New Hampshire - Nevada - New York - Oklahoma - Oregon - Pennsylvania - Rhode Island - South Carolina - South Dakota - Tennessee - Texas - Virginia - Vermont - Washington - West Virginia
Alabama
Hillabee Greenstone (Paleozoic)
Hillabee Greenstone - pale-green to light-olive-brown massive, fine-grained greenstone interbedded locally with well-foliated mafic phyllite.
Jacksons Gap Group; Jacksons Gap Group, Unnamed unit (Precambrian to Paleozoic)
Jacksons Gap Group; Jacksons Gap Group, Unnamed unit - unnamed comprised of masses of interbedded grayish-green sericite phyllite and sericite-quartz-chlorite phyllite.
Kahatchee Mountain Group; Brewer Phyllite (Precambrian?-Cambrian?)
Brewer Phyllite - dusky-red micaceous slate and phyllite, locally containing interbedded micaceous arkosic quartzite and metasiltstone; locally at the base is interbedded calcite and dolomite marble.
Kahatchee Mountain Group; Sawyer Limestone Member of Brewer Phyllite (Precambrian?-Cambrian?)
Sawyer Limestone Member of Brewer Phyllite - light to medium-gray argillaceous, silty to siliceous calcite and dolomite marble interbedded with phyllite and quartzite, locally cherty.
Kahatchee Mountain Group; Stumps Creek Formation (Precambrian?-Cambrian?)
Stumps Creek Formation - grayish-green micaceous metasiltstone and minor phyllite; grayish-green fine to medium-grained pyritic metasandstone in middle to upper part.
Metaclastic rocks of unknown affinity (Precambrian to Paleozoic)
Metaclastic rocks of unknown affinity - in the area south of Talladega, Talladega County, the unit includes greenish-gray chlorite-sericite phyllite; in small area south of Childersburg the unit consists of greenish-gray chlorite-sericite phyllite and slate locally containing interbeds of metagraywacke; and in the area east of Columbiana, Shelby County, the unit includes dark-greenish-gray slate and metasiltstone containing interbedded coarse-grained to conglomerate quartzite.
Sylacauga Marble Group; Fayetteville Phyllite (Cambrian?-Ordovician?)
Fayetteville Phyllite - dusky-red and medium-gray phyllite and slate interlayered with light-brown to light-gray feldspathic metasiltstone, fine-grained metasandstone and dolomite marble.
Sylacauga Marble Group; Gantts Quarry Formation (Cambrian?-Ordovician?)
Gantts Quarry Formation - white and pale-blue to light-gray calcite marble locally containing interlayered dolomite marble and thin phyllite layers.
Talladega Group; Jemison Chert and Chulafinnee Schist undifferentiated (Silurian?-Devonian)
Jemison Chert and Chulafinnee Schist undifferentiated - grayish-white to yellowish-orange massive, thick-bedded, fine-grained, locally argillaceous, locally fossiliferous metachert and light to dark-greenish-gray fine to medium-grained fissile quartz-sericite-chlorite phyllite and schist which locally includes thin chlorite phyllite and quartzose phyllite beds.
Talladega Group; Lay Dam Formation (Silurian?-Devonian)
Lay Dam Formation (Talladega Group) - interbedded dark-green phyllite, medium-gray to light-brown and black metasiltstone, dark-green feldspathic metagraywacke, and light-gray and dark-gray medium to coarse-grained arkosic quartzite and metaconglomerate; graphitic phyllite common in upper part. In Cleburne and Calhoun Counties, rocks mapped as the Lay Dam include the Abel Gap Formation of Bearce (1973) and consist of interbedded greenish-gray metasiltstone and quartzite, black phyllitic metasiltstone, medium-gray to greenish-gray arkosic quartzite, and dark-gray pyritic quartzite. In Clay Chounty the upper part of the Lay Dam includes black graphitic sericite phyllite and slate reportedly containing plant fossils (Erin Slate Member).
Wedowee Group; Wedowee Group undifferentiated (Precambrian to Paleozoic)
Wedowee Group undifferentiated - Wedowee Group undifferentiated includes the Cragford Phyllite and Cutnose Gneiss. Cragford Phyllite -- interbedded fine-grained graphite-chlorite-sericite schist and phyllite, garnet-sericite schist and phyllite, graphite-quartz-sericite phyllite, locally feldspathic biotite gneiss, calc-silicate rock, and quartzite. Cutnose Gneiss -- cyclically interbedded fine-grained quartz-biotite feldspathic gneiss, graphite-chlorite-sericite schist, locally thin interbeds of graphite-quartz-sericite phyllite, and quartzite. Rocks in the area northeast of Clanton in Chilton and Coosa Counties that are here assigned to the Wedowee Group also have been interpreted as part of the Higgins Ferry Group.
Arizona
Cretaceous to Late Jurassic sedimentary rocks with minor volcanic rocks (Late Jurassic to Cretaceous)
Sandstone and conglomerate, rarely forms prominent outcrops; massive conglomerate is typical near base of unit and locally in upper part. These deposits are nonmarine except in southeastern Arizona, where prominent gray marine limestone (Mural Limestone) forms the middle of the Bisbee Group. Sandstones are typically medium-bedded, drab brown, lithic-feldspathic arenites. Includes Bisbee Group (largely Early Cretaceous) and related rocks, Temporal, Bathtub, and Sand Wells formations, rocks of Gu Achi, McCoy Mountains Formation, and Upper Cretaceous Fort Crittenden Formation and equivalent rocks. (80-160 Ma)
Early Proterozoic metamorphic rocks (Early Proterozoic)
Undivided metasedimentary, metavolcanic, and gneissic rocks. (1600-1800 Ma)
Early Proterozoic metasedimentary rocks (Early Proterozoic)
Metasedimentary rocks, mostly derived from sandstone and shale, with minor conglomerate and carbonate rock. Includes quartz-rich, mostly nonvolcanic Pinal Schist in southeastern Arizona and variably volcanic-lithic sedimentary rocks in the Yavapai and Tonto Basin supergroups in central Arizona. (1600-1800 Ma)
Early Proterozoic metavolcanic rocks (Early Proterozoic)
Weakly to strongly metamorphosed volcanic rocks. Protoliths include basalt, andesite, dacite, and rhyolite deposited as lava or tuff, related sedimentary rock, and shallow intrusive rock. These rocks, widely exposed in several belts in central Arizona, include metavolcanic rocks in the Yavapai and Tonto Basin supergroups. (1650 to 1800 Ma)
Jurassic and Triassic sedimentary and volcanic rocks (Triassic and Jurassic)
Undivided massive quartz-feldspar porphyry of the Jurassic Planet Volcanics, quartz-rich metasandstone of the Jurassic Vampire Formation, and quartzite, phyllite, and fine grained, variably calcareous metasiltstone of the Triassic Buckskin Formation; exposed primarily in the Buckskin and Rawhide Mountains of western Arizona. This unit also includes sandstone and conglomerate beneath Jurassic volcanic rocks in the central Dome Rock Mountains. (160-240 Ma)
Jurassic sedimentary and volcanic rocks (Jurassic)
Sandstone and conglomerate derived from volcanic rocks with associated intermediate-composition lava flows, breccias, and tuffs. In southern Arizona this unit includes rocks of the Artesa sequence, Pitoikam Formation, Mulberry Wash volcanics, Rudolfo Red Beds, Recreation Red Beds, and Gardner Canyon Formation. In western Arizona it includes the Harquar Formation, rocks of Slumgullion, and related(?) unnamed units in the Kofa and Middle Mountains. This unit is characterized by maroon, brown, and purplish-gray volcanic-lithic sandstone and siltstone, with subordinate to abundant conglomerate, quartz-rich sandstone and sparse limestone. (150-170 Ma)
Jurassic to Cambrian metamorphosed sedimentary rocks (Cambrian to Jurassic)
Highly faulted and folded rocks of units Jv, J_, and Pz, deformed and metamorphosed in Jurassic, Cretaceous and Tertiary time. This unit is restricted to west-central Arizona. (160-540 Ma)
Middle Proterozoic sedimentary rocks (Middle Proterozoic)
Red-brown shale and sandstone, buff to orange quartzite, limestone, basalt, black shale, and sparse conglomerate. This unit includes the Grand Canyon Supergroup, Apache Group, and Troy Quartzite. These rocks were deposited in shallow marine, coastal nonmarine, and fluvial settings. (700-1300)
Paleozoic sedimentary rocks (Paleozoic)
Undivided Paleozoic limestone, dolostone, quartzite, shale, and related sedimentary rocks. (248-544 Ma)
California
Jurassic marine rocks, unit 4 (Peninsular Ranges and Western Transverse Ranges) (Paleozoic(?) to Late Jurassic)
Shale, sandstone, minor conglomerate, chert, slate, limestone; minor pyroclastic rocks
Paleozoic marine rocks, undivided, unit 2 (Northern Mojave Desert and Southeastern Sierra Nevada) (Cambrian to Jurassic)
Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite
Paleozoic marine rocks, undivided, unit 3 (Eastern Sierra Nevada) (Late Proterozoic(?) to Mesozoic(?))
Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite
Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada) (Ordovician to Triassic)
Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite
Paleozoic marine rocks, undivided, unit 6 (Northwestern Sierra Nevada) (Permian(?) to Jurassic(?))
Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite
Paleozoic marine rocks, undivided, unit 8 (Northeastern Klamath Mountains) (Ordovician(?) to Devonian(?))
Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite
Paleozoic marine rocks, undivided, unit 9 (Western Klamath Mountains) (Devonian to Jurassic)
Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite
Permian marine sedimentary rocks, unit 2 (Northwestern Sierra Nevada) (Paleozoic or Mesozoic)
Shale, conglomerate, limestone and dolomite, sandstone, slate, hornfels, quartzite; minor pyroclastic rocks
pre-Cenozoic metasedimentary and metavolcanic rocks undivided (Early Proterozoic to Cretaceous)
Undivided pre-Cenozoic metasedimentary and metavolcanic rocks of great variety. Mostly slate, quartzite, hornfels, chert, phyllite, mylonite, schist, gneiss, and minor marble.
Silurian and/or Ordovician marine rocks, unit 3 (Eastern Klamath Mountains) (Ordovician to Early Devonian)
Sandstone, shale, conglomerate, chert, slate, quartzite, hornfels, marble, dolomite, phyllite; some greenstone
Silurian and/or Ordovician marine rocks, unit 4 (Northern Sierra Nevada) (Ordovician to Devonian)
Sandstone, shale, conglomerate, chert, slate, quartzite, hornfels, marble, dolomite, phyllite; some greenstone
Colorado
Uncompahgre Fm (Proterozoic | Paleoproterozoic Mesoproterozoic)
Quartzite, slate, and phyllite
Connecticut
Allingtown Metavolcanics (Middle? Ordovician)
Allingtown Metavolcanics - Green, fine-grained, massive greenstone, composed of epidote, actinolite, albite, and chlorite, commonly with abundant megacrysts of saussurite, interlayered with minor green phyllite, generally containing quartz and sericite. Dark amphibole in western outcrops.
Allingtown Metavolcanics plus Maltby Lakes Metavolcanics (Middle? Ordovician)
Allingtown Metavolcanics plus Maltby Lakes Metavolcanics - Allingtown Metavolcanics - Green, fine-grained, massive greenstone, composed of epidote, actinolite, albite, and chlorite, commonly with abundant megacrysts of saussurite, interlayered with minor green phyllite, generally containing quartz and sericite. Dark amphibole in western outcrops. Maltby Lakes Metavolcanics - Green to gray-green, fine-grained, massive to well-foliated and layered greenstone, greenschist, and schist; also dark amphibolite to west and southwest.
Everett Schist (Cambrian?)
Everett Schist - Grayish to greenish (some rusty-weathering), fine- to medium-grained, foliated but poorly layered schist or phyllite, composed of quartz, albite or oligoclase, muscovite, garnet, staurolite or chloritoid, and generally chlorite. Local layers are dark-gray to silvery schist or phyllite.
Lower part [of Maltby Lakes Metavolcanics] (Middle? Ordovician)
Lower part [of Maltby Lakes Metavolcanics] - Gray-green to green, fine-grained, generally well foliated greenschist, greenstone, and schist or phyllite, composed of albite and chlorite, plus quartz and sericite or epidote and actinolite. Mixed metavolcanics and metasedimentary rocks.
Stockbridge Marble (Lower Ordovician and Cambrian)
Stockbridge Marble (including Inwood Marble) - White to gray, massive to layered marble, generally dolomitic but containing calcite marble in upper part, locally interlayered with schist or phyllite and with calcareous siltstone or sandstone.
Unit b [of Stockbridge Marble] (Upper and Middle? Cambrian)
Unit b [of Stockbridge Marble] - White, pink, cream, and light-gray, generally well bedded dolomitic marble interlayered with phyllite and schist and with siltstone, sandstone, or quartzite, commonly dolomitic.
Walloomsac Schist (Middle Ordovician)
Walloomsac Schist - Black to dark-or silvery-gray, rarely layered schist or phyllite, composed of quartz, albite, and commonly garnet and staurolite or sillimanite (locally strongly retrograded to chlorite and muscovite). Locally feldspathic or calcareous near the base.
Wepawaug Schist (Devonian or Silurian or both)
Wepawaug Schist - Medium- to dark-gray, medium- to fine-grained, well-layered schist or phyllite and metasiltstone, composed of quartz, muscovite or sericite, plagioclase, biotite, and in appropriate metamorphic zones chlorite, garnet, staurolite, and kyanite. Schist or phyllite generally graphic.
Georgia
Graphitic Phyllite (Precambrian-Paleozoic)
Graphitic Phyllite
Meta-argillite/ Phyllite (Precambrian-Paleozoic)
Meta-argillite/ Phyllite
Meta-argillite/ Sericite phyllite/ Metavolcanics (Precambrian-Paleozoic)
Meta-argillite/ Sericite phyllite/ Metavolcanics
Phyllite and Quartzite (Precambrian-Paleozoic)
Phyllite and Quartzite
Phyllite/ Quartzite/ Calc-silicate gneiss (Precambrian-Paleozoic)
Phyllite/ Quartzite/ Calc-silicate gneiss
Phyllite undifferentiated (Precambrian-Paleozoic)
Phyllite undifferentiated
Quartzite/ Phyllite (Precambrian-Paleozoic)
Quartzite/ Phyllite
Sericite Schist/ Micaceous Quartzite/ Sericite Phyllite (Precambrian-Paleozoic)
Sericite Schist/ Micaceous Quartzite/ Sericite Phyllite
Undifferentiated Metavolcanics/ Sericite phyllite/ Meta-argillite/ Quartz mica schist (Precambrian-Paleozoic)
Undifferentiated Metavolcanics/ Sericite phyllite/ Meta-argillite/ Quartz mica schist
Idaho
Limestone, slate; Upper Triassic greenschist-facies metamorphic rocks; western Idaho, Blue Mountains island-arc complex; (Late Triassic)
Upper Triassic shale overlying reefal limestone and dolomite in west-central Idaho.
Schist, phyllite, quartzite, and calc-silicate rock; Middle Proterozoic metasedimentary rocks of Wallace Formation; northern Belt province (Middle Proterozoic)
Intermediate Precambrian age metasediments; generally low-to-medium grade; carbonate bearing argillite and siltite of northern Idaho.
Massachusetts
Blackstone Group (Proterozoic Z)
Blackstone Group - Mica schist and phyllite - Includes Mussey Brook Schist and Sneech Pond Schist.
Blackstone Group (Proterozoic Z)
Blackstone Group - Undivided - Quartzite, schist, phyllite, marble, and metavolcanic rocks.
Boylston Schist (Silurian or Ordovician)
Boylston Schist - Carbonaceous phyllite and schist, locally sulfidic; quartzite; calc-silicate beds.
Coal Mine Brook Formation (Middle Pennsylvanian)
Coal Mine Brook Formation - Fossiliferous, carbonaceous slate and garnet phyllite with a lens of meta-anthracite; conglomerate and arkose.
Eliot Formation (Silurian)
Eliot Formation - Phyllite and calcareous phyllite. In New Hampshire: Used as Eliot Formation of Merrimack Group. Consists of gray to green phyllite, calcareous quartzite, quartz-mica schist, and well-bedded calc-silicate. Includes Calef Member, mapped separately. Age of all formations in Merrimack Group changed to Ordovician(?) to Silurian(?) based on isotopic age determinations of approx 440 and 420 Ma from detrital zircons from Berwick Formation (of Merrimack Group) by J.N. Aleinikoff (oral commun., 1994) (Lyons and others, 1997).
Everett Formation (Lower Cambrian and Proterozoic Z)
Everett Formation - Light-green and greenish-gray chlorite-muscovite-albite or chloritoid-rich phyllite. Predominantly dark-gray chloritoid-rich schist in Lenox Mountain.
Fitchburg Complex (Lower Devonian or younger)
Fitchburg Complex -Dark-gray, strongly foliated biotite granodiorite to tonalite gneiss; resembles Dht; intrudes and contains inclusions of Dl, some mappable; locally cut by sills identical to Dfgrg.
Fitchburg Complex (Lower Devonian or younger)
Fitchburg Complex - Light-gray, strongly foliated biotite-muscovite granite to granodiorite gneiss; common small to very large inclusions of Dl, some mapped separately.
Fitchburg Complex (Lower Devonian or younger)
Fitchburg Complex - Dfgd containing many zones of foliated biotite-muscovite granite gneiss and inclusions of mica schist and feldspathic granulite.
Gile Mountain Formation (Lower Devonian)
Gile Mountain Formation - Like Dgm but having a higher percentage of quartzite.
Gile Mountain Formation (Lower Devonian)
Gile Mountain Formation - Gray, slightly rusty, poorly bedded phyllite and schist containing 20 cm to 2 m beds of light-gray, fine-grained quartzite, local punky-brown weathering calcareous granofels or quartzose marble, and pods and stringers of vein quartz.
Greylock Schist (Lower Cambrian and Proterozoic Z)
Greylock Schist - Soft, lustrous green phyllite with minor beds of green quartzite and well laminated gray dolomitic phyllite; resembles Hoosac (CAZhg) and Nassau (CAZnp).
Greylock Schist (Lower Cambrian and Proterozoic Z)
Greylock Schist - Light-green to gray, white albite-spotted phyllite and interbedded blue-quartz metagraywacke, salmon-pink dolostone, and blue-quartz conglomerate. Minor interbeds of black and white albite-spotted phyllite resembles Hoosac (CAZhga).
Harvard Conglomerate (Pennsylvanian)
Harvard Conglomerate - Conglomerate and chloritoid-hematite phyllite.
Hoosac Formation (Lower Cambrian and Proterozoic Z)
Hoosac Formation - Undifferentiated Hoosac Formation.
Hoosac Formation (Lower Cambrian and Proterozoic Z)
Hoosac Formation - Green to gray-green chlorite-sericite-quartz phyllite; interbeds of chloritoid- or albite-rich schist and minor quartzite, locally rich in garnet and kyanite.
Kittery Formation (Silurian or Ordovician)
Kittery Formation - Quartzite, partly calcareous; phyllite, schist.
Littleton Formation (Lower Devonian)
Littleton Formation - Black to gray aluminous mica schist, quartzose schist, and aluminous phyllite.
Nassau Formation (Lower Cambrian and Proterozoic Z)
Nassau Formation - Gray to dark-greenish-gray, siliceous phyllite with abundant beds of quartzite, olive-gray metasiltstone and subgraywacke (includes Bomoseen Graywacke Member and Zion Hill quartzite Member).
Nassau Formation (Lower Cambrian and Proterozoic Z)
Nassau Formation- Greenish-gray albitic phyllite.
Nassau Formation (Lower Cambrian and Proterozoic Z)
Nassau Formation - Dark-gray to black chloritoid-rich phyllite.
Nassau Formation (Lower Cambrian and Proterozoic Z)
Nassau Formation - Lustrous, soft green, yellowish-green and purple laminated chloritoid-chlorite phyllite (Mettawee Member).
Putney Volcanics (Lower Devonian)
Putney Volcanics - Light greenish-gray plagioclase-quartz-muscovite phyllite and granofels.
Stockbridge Formation (Lower Cambrian)
Stockbridge Formation - Beige, tan, and dark-gray weathering quartzose dolomite marble containing interbeds of black, green and maroon phyllite and punky weathering blue quartz pebble quartzite.
Tadmuck Brook Schist (Silurian?, Ordovician, or Proterozoic Z)
Tadmuck Brook Schist - Andalusite phyllite and sillimanite schist, partly sulfidic; local quartzite in upper part.
Tectonic breccia (Ordovician)
Tectonic breccia - Consisting of completely mixed phyllites of Walloomsac Formation Taconic allochthon.
Tower Hill Quartzite (Silurian)
Tower Hill Quartzite - Quartzite and phyllite.
Tower Hill Quartzite (Silurian)
Tower Hill Quartzite - Gray phyllite associated with the Tower Hill Quartzite.
Vaughn Hills Quartzite (Silurian or Ordovician)
Vaughn Hills Quartzite - Quartzite, phyllite, conglomerate, and chlorite schist.
Walloomsac Formation (Middle Ordovician)
Walloomsac Formation - Orange-brown weathering, graphite-albite-biotite calcitic marble and schistose marble and interbedded black phyllite.
Walloomsac Formation (Middle Ordovician)
Walloomsac Formation - Dark-gray, graphitic quartz phyllite and schist containing minor lenses of limestone.
West Castleton and Nassau Formations, undivided (Lower Cambrian and Proterozoic Z)
West Castleton and Nassau Formations, undivided - Dark-gray to black calcareous slate interlayered with greenish-gray phyllite.
Worcester Formation (Lower Devonian and Silurian)
Worcester Formation - Carbonaceous slate and phyllite and minor metagraywacke.
Maryland
Catoctin Metabasalt (Late Precambrian)
Catoctin Metabasalt - Thick-bedded metabasalt with amygdaloidal layers and secondary veins of quartz, calcite, and epidote; interbedded green tuffaceous phyllite and blue amygdaloidal metaandesite.
Chilhowee Group; Antietam Formation (Cambrian)
Antietam Formation - White to dark gray and brown, thick-bedded, fine- to coarse-grained quartzite with thin argillaceous partings; first occurrence of Lower Cambrian fossils; cleavage generally obscures bedding; increasingly metamorphosed and phyllitic toward east; estimated thickness 300 to 800 feet.
Chilhowee Group; Harpers Formation (Cambrian)
Harpers Formation - Brown to dark bluish-gray banded shale, to light bluish-gray, finely laminated phyllite; distinctively pale purple in basal part; bedding obscured by cleavage; increasingly metamorphosed toward east from shale to slate and phyllite; estimated thickness 2,000 feet.
Chilhowee Group; Loudoun Formation (Cambrian)
Loudoun Formation - Basal phyllite member: Pale purple, discontinuous, lenticular; members are in gradational contact; total thickness 0 to 200 feet
Chilhowee Group; Weverton Formation (Late Precambrian - Cambrian)
Weverton Formation - Interbedded white to dark gray, thin-bedded, micaceous, ferruginous, and sericitic quartzites, phyllites, and white, thick-bedded, ledge-making quartzites; some gray to brown ferruginous quartz conglomerate and purple-banded phyllite; thickness approximately 100 feet in south, increases to 425 feet in north.
Ijamsville Formation (Late Precambrian (?))
Ijamsville Formation - Blue, green, or purple phyllite and phyllitic slate, with interbedded metasiltstone and metagraywacke; flattened pumiceous blebs occur locally.
Ijamsville Formation and Marburg Schist (Late Precambrian (?))
Ijamsville Formation - Blue, green, or purple phyllite and phyllitic slate, with interbedded metasiltstone and metagraywacke; flattened pumiceous blebs occur locally; and Marburg Schist - Bluish-gray to silvery-green, fine-grained, muscovite-chlorite-albite-quartz schist; intensely cleaved and closely folded; contains interbedded quartzites.
Libertytown Metarhyolite (Late Precambrian (?))
Libertytown Metarhyolite - Purple, bluish-black, and red, dense, fine-grained metarhyolite with feldspar phenocrysts; interbedded with blue and purple amygdaloidal metaandesite; both rhyolite and andesite interbedded with blue, purple, and green phyllitic slates.
Sugarloaf Mountain Quartzite (Late Precambrian (?))
Sugarloaf Mountain Quartzite - Massive white quartzite interbedded with softer sericitic quartzite, slate, and phyllite.
Swift Run Formation (Late Precambrian)
Swift Run Formation - Sericitic quartzite and phyllite; blue and green tuffaceous slate with sericitic blebs; some white marble with interbedded phyllite.
Urbana Formation (Late Precambrian (?))
Urbana Formation - Dark gray to green sericite-chlorite phyllite, metasiltstone, and quartzite; thin lenses of impure marble and calcareous phyllite occur locally.
Maine
Devonian - Precambrian Z Appleton Ridge Formation (Devonian - Precambrian Z)
Devonian - Precambrian Z Appleton Ridge Formation
Devonian - Precambrian Z Gonic Formation (Devonian - Precambrian Z)
Devonian - Precambrian Z Gonic Formation
Ordovician - Cambrian Cookson formation (Ordovician - Cambrian)
Ordovician - Cambrian Cookson formation
Ordovician - Cambrian Dead River formation (Ordovician - Cambrian)
Ordovician - Cambrian Dead River formation
Ordovician - Cambrian Dead River formation lower member (Ordovician - Cambrian)
Ordovician - Cambrian Dead River formation lower member
Ordovician - Cambrian Dead River formation upper member (Ordovician - Cambrian)
Ordovician - Cambrian Dead River formation upper member
Ordovician - Precambrian Z Cape Elizabeth Formation (Ordovician - Precambrian Z)
Ordovician - Precambrian Z Cape Elizabeth Formation
Ordovician - Precambrian Z Ellsworth formation (Ordovician - Precambrian Z)
Ordovician - Precambrian Z Ellsworth formation
Precambrian Z Rye Formation (Precambrian)
Precambrian Z Rye Formation
Silurian - Precambrian Z Eliot Formation (Silurian - Precambrian Z)
Silurian - Precambrian Z Eliot Formation
Silurian - Precambrian Z Kittery Formation (Silurian - Precambrian Z)
Silurian - Precambrian Z Kittery Formation
Silurian rocks of the Fivemile Brook sequence (Silurian)
Silurian rocks of the Fivemile Brook sequence
Minnesota
Felsic to intermediate volcanic and volcaniclastic rocks, mica schist, phyllite, and granitoid rocks (Late Archean)
Felsic to intermediate volcanic and volcaniclastic rocks, mica schist, phyllite, and granitoid rocks - Variably and cataclastically deformed. Unit forms aeromagnetic "quiet zone" and probably contains some rocks of Paleoproterozoic age.
Mille Lacs Group and related rocks of the Penokean fold-and-thrust bets; Graphitic schist, phyllite and slate interbedded on a fine scale (Early Proterozoic)
Mille Lacs Group and related rocks of the Penokean fold-and-thrust belt; Graphitic schist, phyllite and slate interbedded on a fine scale
North Carolina
Alligator Back Formation; Gneiss (Late Proterozoic)
Gneiss - finely laminated to thin layered; locally contains massive gneiss and micaceous granule conglomerate; includes schist, phyllite, and amphibolite.
Alligator Back Formation; Mica schist and phyllite (Late Proterozoic)
Mica schist and phyllite - laminated to thin layered; interlayered with minor biotite-muscovite gneiss and amphibolite.
Blacksburg Formation (Cambrian/Late Proterozoic)
Blacksburg Formation - sericite schist, locally with graphite, phyllite with sericite quartzite, banded marble, amphibolite, and minor calc-silicate rock.
Blowing Rock Gneiss (Middle Proterozoic)
Blowing Rock Gneiss (1000 my) - 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.
Grandfather Mountain Formation; Metasiltstone (Late Proterozoic)
Metagraywacke - cross-bedding and graded bedding common, locally conglomeratic; interlayered with metasiltstone and phyllite.
Grandfather Mountain Formation; Metasiltstone (Late Proterozoic)
Metasiltstone - locally contains thin bedded iron-bearing dolomitic marble; interlayered with phyllite, metagraywacke, and meta-arkose.
Mica Schist (Cambrian/Late Proterozoic)
Mica Schist - contains garnet, staurolite, kyanite, or sillimanite; includes lenses and layers of quartz schist, micaceous quartzite, biotite gneiss, amphibolite, and phyllite.
Mica Schist (Cambrian/Late Proterozoic)
Mica Schist - Garnet, staurolite, kyanite, or sillimanite occur locally; lenses and layers of quartz schist, micaceous quartzite, calc-silicate rock, biotite gneiss, amphibolite, and phyllite.
Mineral Bluff Formation (Late Proterozoic)
Mineral Bluff Formation - 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.
Ocoee Supergroup, Great Smokey Group; Phyllite (Late Proterozoic)
Phyllite - dark olive gray, graphitic and sulfidic.
Ocoee Supergroup, Great Smokey Group; Slate of Copperhill Formation (Late Proterozoic)
Slate of Copperhill Formation - slate to phyllite, dark gray, graphitic, sulfidic; includes metagraywacke with local graded bedding.
Ocoee Supergroup, Snowbird Group; Roaring Fork Sandstone (Late Proterozoic)
Roaring Fork Sandstone - greenish gray, fine to medium grained, locally cross-bedded, metamorphosed; interbedded metasiltstone and phyllite.
Ocoee Supergroup, Snowbird Group, undivided (Late Proterozoic)
Snowbird Group, undivided - feldspathic metasiltstone, metasandstone, and phyllite. Basal schist contains lenses of quartz-pebble conglomerate.
Ocoee Supergroup, Snowbird Group; Wading Branch Formation (Late Proterozoic)
Wading Branch Formation - sandy slate to coarse-grained pebbly metagraywacke with local graded bedding. Basal quartz-sericite schist or phyllite.
Phyllite and Schist (Cambrian/Late Proterozoic)
Phyllite and Schist - minor biotite and pyrite; includes phyllonite, sheared fine-grained metasediment and metavolcanic rock.
Phyllite and Schist (Cambrian/Late Proterozoic)
Phyllite and Schist - includes phyllonite and interlayered biotite gneiss.
Phyllite and Schist (Cambrian/Late Proterozoic)
Phyllite and Schist - minor biotite, pyrite, and sillimanite; includes minor quartzite.
Phyllite and Schist (Cambrian/Late Proterozoic)
Phyllite and Schist - locally laminated and pyritic; includes phyllonite, sheared fine-grained metasediment, and metavolcanic rock. In Lilesville granite aureole, includes hornfels.
Phyllite and Schist (Cambrian/Late Proterozoic)
Phyllite and Schist - minor biotite and pyrite; includes phyllonite, sheared fine-grained metasediment and metavolcanic rock.
Shady Dolomite (Cambrian)
Shady Dolomite - light gray, fine grained, massive, locally thin bedded or ribboned. Thin beds of phyllite.
New Hampshire
Fitch Formation (Upper Silurian; Pridolian and Ludlovian) (Upper Silurian - (Pridolian and Ludlovian))
Fitch Formation - Metamorphosed limestone, calcareous sandstone, siltstone, and dark pelitic schist; lower contact is disconformable on the Clough Quartzite. Fossiliferous.
Frontenac Formation, Graded-bedded metagraywacke and subordinate gray phyllite (Silurian?)
Frontenac Formation, Graded-bedded metagraywacke and subordinate gray phyllite.
Gile Mountain Formation, Interbedded gray slate or phyllite and brown-weathering calcite-ankerite metasiltstone (Lower Devonian)
Interbedded gray slate or phyllite and brown-weathering calcite-ankerite metasiltstone - Contains minor marble and quartzite. Resembles Waits River Formation in Vermont.
Gile Mountain Formation, Meetinghouse Slate Member (Lower Devonian )
Meetinghouse Slate Member - Gray to black phyllite and silty metasandstone turbidite.
Gile Mountain Formation, undivided (Lower Devonian)
Gile Mountain Formation, undivided - Gray to tan metawacke and schist or phyllite; gradational into Meetinghouse Slate Member but more thickly bedded and less pelitic than the member. Includes minor metavolcanic lentils.
Ironbound Mountain Formation, undivided (Lower Devonian)
Ironbound Mountain Formation, undivided - Interbedded gray phyllite, in places containing feldspathic clasts, and feldspathic metasandstone, variably graded.
Merrimack Group, Eliot Formation (Ordovician? - Silurian?)
Merrimack Group, Eliot Formation - Gray to green phyllite, calcareous quartzite, quartz-mica schist, and well-bedded calc-silicate.
Merrimack Group, Eliot Formation, Calef Member (Ordovician? - Silurian?)
Merrimack Group, Eliot Formation, Calef Member - Black phyllite at western contact of the Eliot Formation.
Merrimack Group, Kittery Formation (Ordovician? - Silurian?)
Merrimack Group, Kittery Formation - Tan, graded-bedded, calcareous metasandstone and purple and green phyllite. Grades into the Eliot formation but facing direction is uncertain.
Nevada
Conglomerate, limestone, meta-andesite, phyllite, and shale (Devonian to Mississippian)
CONGLOMERATE, LIMESTONE, META-ANDESITE, PHYLLITE, AND SHALE-Includes Grossman, Banner, Nelson, and Mountain City Formation. Northern Elko County
Quartzite and minor amounts of conglomerate, phyllitic siltstone, limestone, and dolomite (Late Proterozoic to Early Cambrian)
QUARTZITE AND MINOR AMOUNTS OF CONGLOMERATE, PHYLLITIC SILTSTONE, LIMESTONE, AND DOLOMITE-Includes Prospect Mountain Quartzite, Osgood Mountain Quartzite, and Gold Hill Formation in northern Nevada, and Stirling Quartzite, Wood Canyon Formation, and Zabriskie Quartzite in southern Nevada.
New York
Austerlitz Phyllite (Cambrian?)
Austerlitz Phyllite - minor quartzite
Walloomsac Formation (Middle Ordovician)
Walloomsac Formation - slate, phyllite, schist, metagraywacke.
Walloomsac Formation (Middle Ordovician)
Walloomsac Formation - phyllite, schist, metagraywacke.
Oklahoma
Blaylock Sandstone (Phanerozoic | Paleozoic | Silurian)
McALESTER TEXARKANA- Sandstone, greenish-gray, fine grained, well indurated, alternating with dark-gray to brown phyllites and shales in lower 100 feet; occurs only in Broken Bow Uplift and adjacent area; thickness, 670 to 804 feet, with maximum thickness in Arkansas 1,500 feet. Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS
Collier Shale (Phanerozoic | Paleozoic | Cambrian-Furongian Ordovician-Early)
McALESTER TEXARKANA- Shale and phyllite, dark-gray to black, with much limestone, some granitic and arkosic pebbles, many quartz and orthoclase pegmatities, and some galena and sphalerite; contains Lower Ordovician conodonts; base covered; exposed thickness, 200 feet. Viersen and Cochran's 25-1 Weyerhaeuser well (9-8-70), spudded in upper Collier to total depth of 10,019 feet in Southeast quarter of Northwest quarter of section 25, Township 5 South, Range 23 East, penetrated dark-gray to black phyllites, quartzites, and dolomitic marble without reaching basement (Goldstein, 1975). Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS
Mazarn Shale (Phanerozoic | Paleozoic | Ordovician-Early)
McALESTER TEXARKANA- Shale and phyllite, dark-gray to black, micaceous; estimated thickness, 1,000 feet, with maximum thickness in Arkansas 3,000 feet. Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS
Missouri Mountain and Polk Creek Shales (Phanerozoic | Paleozoic | Ordovician-Late Silurian)
McALESTER TEXARKANA- Shale, greenish-gray to maroon to black; grades into phyllite in Broken Bow Uplift; contains some thin sandstones and gray conglomerates; a fossiliferous limestone occurs in Southeast quarter section 29, Township 4 South, Range 23 East; mapped as SmOp in Potato Hills, where it is included with Polk Creek Shale; thickness, 60 to 110 feet or less. Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS
Missouri Mountain Shale (Phanerozoic | Paleozoic | Silurian)
McALESTER TEXARKANA- Shale, greenish-gray to maroon to black; grades into phyllite in Broken Bow Uplift; contains some thin sandstones and gray conglomerates; a fossiliferous limestone occurs in Southeast quarter section 29, Township 4 South, Range 23 East; mapped as SmOp in Potato Hills, where it is included with Polk Creek Shale; thickness, 60 to 110 feet or less. Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS
Polk Creek Shale (Phanerozoic | Paleozoic | Ordovician-Late)
ARDMORE-SHERMAN- Shale, black; thickness, 175 feet. Occurs in the OUACHITA MNTS. McALESTER TEXARKANA- Shale and phyllite, dark-gray to black, with some chert nodules; contains many graptolites; thickness, 75 to 140 feet. (Same as Sylvan Shale in Arbuckle Mountains.) Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS
Womble Formation or Womble Shale (Phanerozoic | Paleozoic | Ordovician-Early Ordovician-Middle)
ARDMORE-SHERMAN- "Womble Shale"- Shale, black to green; thickness, 250 feet, base covered. Occurs in the OUACHITA MNTS. McALESTER TEXARKANA- "Womble Formation"- Sandstone, phyllites, and shales, greenish-gray to dark-gray to black, weathering red-brown; some black to brown cherty limestones occur in upper part; Middle Ordovician graptolites are found in upper part, and Lower Ordovician graptolites in lower part; basal part faulted; estimated thickness, 1,000 feet or more, with maximum thickness in Arkansas 3,500 feet. Occurs in POTATO HILLS, BROKEN BOW UPLIFT or ADJACENT SMALLER UPLIFTS IN SOUTHEASTERN PART OF OUACHITA MOUNTAINS
Oregon
Marble (Permian to Triassic)
Informally called the "Nelson marble" by Prostka (1967). Light-gray, fine-grained marble and medium- to dark-gray calcareous phyllite, exposed in a nearly continuous band from the Snake River westward through Nelson Station, about 6 km southeast of Durkee, and westward to the area north of Pedro Mountain, southern Baker County. Prostka (1967) considers the Nelson correlative with Upper Triassic Martin Bridge Formation of Ross (1938), whereas Ashley (1967) and Brooks and Vallier (1967) consider it older (Permian?) and stratigraphically and structurally related to Elkhorn Ridge Argillite and Burnt River Schist
Sedimentary rocks (Jurassic) (Late Jurassic )
Black and gray mudstone, shale, siltstone, graywacke, andesitic to dacitic water-laid tuff, porcelaneous tuff, and minor interlayers and lenses of limestone and fine-grained sediments metamorphosed to phyllite or slate. Locally includes some felsite, andesite and basalt flows, breccia, and agglomerate. Marine invertebrate fauna indicates age range from Early Jurassic (Hettangian) to early Late Jurassic (Oxfordian). In Klamath Mountains of southwest Oregon, includes Galice Formation (Wells and Peck, 1961) and unnamed, hornblende- and (or) pyroxene-bearing clastic rocks of Jurassic age (Smith and others, 1982)
Pennsylvania
Antietam and Harpers Formations, undivided (Cambrian)
Antietam and Harpers Formations, undivided - Includes, in descending order, the Antietam (CAa) and Harpers (CAh) Formations. Antietam Formation - gray, buff-weathering quartzite. Harpers Formation - Dark-greenish-gray phyllite and schist containing thin quartzite layers; includes Montalto Member (CAhm) - gray quartztite
Conestoga Formation (Ordovician and Cambrian)
Conestoga Formation - Light-gray, thin-bedded, impure, contorted limestone having shale partings; conglomeratic at base; in Chester Valley, includes micaceous limestone in upper part, phyllite in middle, and alternating dolomite and limestone in lower part.
Elbrook Formation (Cambrian)
Elbrook Formation - Microcrystalline limestone and, in places, marble; includes subordinate dolomite containing abundant phyllitic layers; occurs in Chester and Montgomery Counties; relation to Elbrook of Cumberland Valley sequence is uncertain.
Harpers Formation (Cambrian)
Harpers Formation - Dark-greenish-gray phyllite and schist containing thin quartzite layers; includes Montalto Member (CAhm).
Harpers Formation (Cambrian)
Harpers Formation - Dark-greenish-gray phyllite and schist containing thin quartzite layers.
Lower (Middle?) Cambrian rocks, undivided (Cambrian)
Lower (Middle?) Cambrian rocks, undivided - Lower Cambrian of Berks County includes tectonic slices of many of the following rock units: Zooks Corner (CAzc), Ledger (CAl), Kinzers (CAk), Vintage (CAv), Antietam (CAa, CAah), and Harpers (CAh, CAah) Formations.
Marburg Schist (Probably lower Paleozoic)
Marburg Schist - Gray-green phyllite, mica-chlorite schist, and conglomerate.
Octoraro Formation (Probably lower Paleozoic)
Octoraro Formation - Includes albite-chlorite schist, phyllite, some hornblende gneiss, and granitized members.
Rhode Island
Conanicut Group - Dutch Island Harbor Formation (Cambro-Ordovician)
Conanicut Group - Dutch Island Harbor Formation - Dark gray phyllite, commonly with rhythmically bedded Bouma sequences and brown-weathering carbonate beds that contain concretions 10-30 cm long.
Conanicut Group - East Passage Formation (Cambro-Ordovician)
Conanicut Group - East Passage Formation - Red, orange-brown, and gray-green phyllite and thinly-bedded, nongraded sandstone and siltstone; rare limestone, and sparse volcanic rock including welded-tuff.
Conanicut Group - Fort Burnside Formation (Cambro-Ordovician)
Conanicut Group - Fort Burnside Formation - Buff siltstone at base grading upward into black to gray phyllite; units commonly cyclically repeated. Intimately interstratified with OCAcj, such that the two units are grouped together at the presented map scale.
Conanicut Group - Jamestown Formation (Cambro-Ordovician)
Conanicut Group - Jamestown Formation - Green to black phyllite interstratified with buff to pink siltstone; trilobite-bearing.
Conanicut Group - undifferentiated rock (Cambro-Ordovician)
Conanicut Group - undifferentiated rock - Consists of associations of the above rock types.
Narragansett Bay Group - Sachuest Arkose (Pennsylvanian)
Narragansett Bay Group - Sachuest Arkose - Gray, smoky-quartz granule-conglomerate, sandstone, and pebble to cobble conglomerate, interbedded with black carbonaceous phyllite. Includes some rock mapped formerly as Pondville Conglomerate.
Pirate Cove Formation (Cambrian)
Pirate Cove Formation - Pink to buff-white, thinly laminated marble units (~ 3 m thick) containing diagnostic hyoliths, interlayered with magenta slate. The basal marble varies from pink to red to orange, whereas the overlying 15-m-thick phyllite varies from maroon and red to green, gray and silver. Intimately associated spatially with OCAcj, such that the two units are grouped together at the presented map scale.
South Carolina
Battleground Formation, Metasedimentary rocks, undivided (Neoproterozoic)
Battleground Formation, Metasedimentary rocks, undivided: quartz-sericite schist/phyllite and interlayered quartzite, quartz-pebble conglomerate, high-alumina quartzite, and manganiferous schist
Blacksburg Formation (Neoproterozoic)
Blacksburg Formation: metamorphosed sedimentary sequence of interlayered sericite schist and phyllite, sericite quartzite, marble, amphibolite and calc-silicate rock
Little River Sequence, metasedimentary rocks (Cambrian or Neoproterozoic)
Little River Sequence, metasedimentary rocks: white-mica schist and phyllite, metatuff, quartz-muscovite schist, and minor quartzite
Quartz-sericite phyllite and schist (Cambrian to Neoproterozoic)
Quartz-sericite phyllite and schist
South Dakota
Metaconglomerate and Metaquartzite (Proterozoic | Paleoproterozoic)
Light-gray to gray, conglomeratic and feldspathic schist, biotite schist, taconite, and phyllite. Individual conglomerate and fanglomerate tongues from 100-500 ft (30-152 m) thick. Total thickness over 10,000 ft (3,048 m).
Metamorphosed Carbonaceous Shale (Proterozoic | Paleoproterozoic)
Dark-gray to gray, siliceous biotite phyllite, calcareous biotite phyllite, and schist. Minimum thickness 1,500 ft (457 m).
Metamorphosed Carbonaceous Shale (Proterozoic | Paleoproterozoic)
Dark-gray to gray, siliceous biotite phyllite and schist. Thickness greater than 2,500 ft (762m).
Metamorphosed Conglomerate (Proterozoic | Paleoproterozoic)
Gray to grayish-brown, conglomeratic biotite phyllite, siliceous biotite phyllite, mica schist, quartzite, and iron-formation. Thickness up to 2,000 ft (610 m).
Metamorphosed Dolomite (Proterozoic | Paleoproterozoic)
Light-gray to light-tan marble, phyllite, and calcareous phyllite. Thickness 60-300 ft (18-91 m).
Metamorphosed Shale (Proterozoic | Paleoproterozoic)
Gray to dark-gray phylite, slate, and mica schist. Estimated thickness at least 5,000 ft (1,524 m).
Metamorphosed Siltstone (Proterozoic | Paleoproterozoic)
Medium-gray to dark-greenish-gray phyllite, slate, and biotite schist containing minor chert and amphibolite. Locally intruded by thin metagabbro sills. Thickness 1,000-3,000 ft (305-914 m).
Metamorphosed Tuffaceous Shale (Proterozoic | Paleoproterozoic)
Light-gray to light-tan, muscovite schist and muscovite phylite. Thickness approximately 1,000-3,000 ft (305-914 m).
Older Metasedimentary Rocks (Archean )
Gray phyillite, mica schist, and biotite-plagioclase schist. Total thickness unknown; approximately 500 ft (152 m) exposed.
Tennessee
Ocoee Supergroup, including Walden Creek Group, (including Sandsuck Formation, Wilhite Formation, Shields Formation, Licklog Formation), Cades Sandstone, and Rich Butt Sandstone (Precambrian)
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.
Snowbird Group, including Pigeon Siltstone, Roaring Fork Sandstone, Metcalf Phyllite, Longarm Quartzite, and Wading Branch Formation (Precambrian)
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.
Walden Creek Group, including Sandsuck Formation, Wilhite Formation, Shields Formation, and Licklog Formation (Cambrian)
Walden Creek Group - The formations, other than the Sandsuck, are applicable mainly in the region of the Great Smoky Mountains. Thickness about 8,000 feet, Includes 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.
Walden Creek Group, including Sandsuck Formation, Wilhite Formation, Shields Formation, and Licklog Formation (Precambrian)
The formations, other than the Sandsuck, have been mapped only in the region of the Great Smoky Mountains. Thickness about 8,000 feet. Includes 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.
Texas
Allamore Formation (preCambrian-Proterozoic [Grenville])
Allamore Formation
Carrizo Mountain Group showing metasedimentary rocks (preCambrian-Proterozoic)
Carrizo Mountain Group showing metasedimentary rocks
Virginia
Aaron Slate (Proterozoic Z)
Aaron Slate - Phyllite and slate.
Ashe Formation -Mica schist or phyllite (Proterozoic Z)
Ashe Formation - Mica schist or phyllite
Buffards Formation (Ordovician)
Buffards Formation - Micaceous conglomerate, schist, and phyllite.
Candler Formation - Phyllite and schist (Cambrian)
Candler Formation - Phyllite in central Blue Ridge Anticlinorium; Phyllite, metasiltstone and quartz-mica schist in southwest Blue Ridge Anticlinorium
Catoctin Formation - Metasedimentary rocks (Proterozoic Z-Cambrian)
Catoctin Formation - Metasedimentary rocks
Chilhowee Group (Cambrian)
Chilhowee Group - Appalachian Plateaus and Valley and Ridge: Quartzite, conglomerate, feldspathic sandstone, phyllite, and minor ferruginous sandstone and volcanic rocks. Blue Ridge Anticlinorium: Conglomerate, quartzite, metasiltstone, and phyllite.
Everona Limestone (Cambrian)
Everona Limestone - Limestone.
Fauquier Formation - Metasiltstone and phyllite (Proterozoic Z)
Fauquier Formation - Meta-argillite is laminated metasiltstone; and phyllite.
Lynchburg Group; Charlottesville Formation (Proterozoic Z)
Lynchburg Group; Charlottesville Formation - Graphitic metasiltstone, feldspathic metasandstone, and quartzite.
Lynchburg Group; Graphitic phyllite and metasiltstone (Proterozoic Z)
Lynchburg Group - Graphitic phyllite and metasiltstone
Mafic Volcanic Rocks (Proterozoic Z)
Mafic volcanic rocks.
Metasedimentary Rocks Undivided (Cambrian-Ordovician)
Metasedimentary rocks
Metavolcanic and Metavolcanic Clastic Phyllite (Proterozoic - Cambrian)
Metavolcanic and metavolcanic clastic phyllite
Micaceous Quartzite (Cambrian)
Micaceous quartzite
Phyllite (Cambrian-Ordovician)
Phyllite.
Phyllite and Metasiltstone (Proterozoic Z)
Phyllite and metasiltstone.
Phyllite and Metatuff (Proterozoic Z)
Phyllite and metatuff.
Popes Head Formation - Station Hills Phyllite Member. Phyllite. (Cambrian-Ordovician)
Popes Head Formation - Station Hills Phyllite Member. Phyllite.
Swift Run Formation (Proterozoic Z)
Swift Run Formation - Phyllite, metasandstone, and metaconglomerate.
Unicoi Formation (Cambrian)
Unicoi Formation - Sandstone and quartzite with phyllite, tuffaceous phyllite, conglomerate, and minor basalt.
Vermont
Albee Formation (Ordovician)
Albee Formation - Massive, gray, white-weathered quartzite and feldspathic quartzite interbedded with greenish-gray slate, phyllite, feldspthic phyllite and quartzose argillaceous phyllite. Micaceous quartzite, quartz-mica schist, mica schist and hornfels contining porphyroblasts of biotite, garnet, staurolite and sillimanite in the vicinity of granitic plutons. Soda-rhyolite tuff occurs locally. Micaceous quartzite characterized by thin, schistose "pinstripe" partings is common in many areas.
Bascom Formation, and undifferentiated Luke Hill, Naylor Ledge and Hastings Creek Limestones; Brownell Mountain Phyllite Member (Ordovician)
Bascom Formation , and undifferentiated Luke Hill, Naylor Ledge and Hastings Creek Limestones; Brownell Mtn Phyllite Member - Calcareous phyllite in upper part of the Bascom Formation of east limb of Hinesburg synclinorium.
Brezee Formation (Cambrian)
Brezee Formation - Dark gray to black phyllite with beds of blue-gray marble, dark gray dolomite, sandy dolomite, and dolomitic sandstone, in upper part; beds of massive quartzite as much as 20 ft thick occur locally and in places contain pebbles of blue quartz. Phyllites are locally highly albitic.
Brezee Formation, quartzose green phyllite (Cambrian)
Brezee Formation, quartzose green phyllite.
Gile Mountain Formation (Devonian)
Gile Mountain Formation - Gray quartz-muscovite phyllite or schist, interbedded and intergradational with gray micaceous quartzite (graywacke northeast of Nulhegan River), calcareous mica schist, and, locally, quartzose and micaceous crystalline limestone like that of the Waits River formation. The phyllite and schist commonly contain porphyroblasts of biotite, garnet, or staurolite, and locally kyanite, andalusite, or sillimanite. Used as Early Devonian Gile Mountain Formation. Generally consists of gray to tan metawacke and schist or phyllite, gradational into its Meetinghouse Slate Member, but much more thickly bedded and less pelitic. Contains minor metavolcanic lentils. Unnamed metavolcanic member is possibly equivalent to Putney Volcanics of southeastern VT. Separately mapped interbedded gray slate or phyllite and brown-weathering calcite-ankerite metasiltstone, and minor marble and quartzite, resembles Waits River Formation of VT. Meetinghouse Slate Member consists of gray to black phyllite and silty metasandstone turbidite. Report includes geologic map, cross sections, correlation chart, and four 1:500,000-scale derivative maps (Lyons and others, 1997).
Gile Mountain Formation, Meetinghouse Slate Member (Devonian)
Gile Mountain Formation, Meetinghouse Slate Member - Chiefly gray slate or phyllite characterized by beds of gray schistose quartzite 1/8 inch to 3 inches thick. Gile Mountain Formation and its Meetinghouse Slate Member were previously considered to be Early Devonian based on Emsian plant fossils from Compton Formation of QUE (Hueber and others, 1990; Hatch, 1991). Age assignment here changed to Early Devonian(?) because recent mapping indicates that Gile Mountain and Compton are not coextensive across VT-QUE border as formerly believed by Doll and others (1961, State map) and St. Julien and Slivitsky (1987). Instead, the formations are separated by Ironbound Mountain Formation. Ironbound Mountain Formation is conformably overlain by Compton, but it is not yet known whether Ironbound Mountain is overlain or underlain by Gile Mountain; this is shown by queried Ironbound Mountain-Gile Mountain contact in area of Averill 7.5-min quad, VT. Correlation of Gile Mountain and Compton is justified only if Gile Mountain in this area conclusively is shown to be underlain by Ironbound Mountain; otherwise, Gile Mountain (with possible exception of its Meetinghouse Slate Member) would be coeval with Silurian Frontenac Formation. Hatch (1988) proposed that Meetinghouse represents upper part of Gile Mountain on basis of graded bedding seen south of map area. This relationship is not proven, however, because Gile Mountain-Meetinghouse contact is difficult to define and graded beds are not always easily interpreted. On this map, Meetinghouse is tentatively shown to occur below main body of Gile Mountain on basis of remarkable similarity between it and Ironbound Mountain Formation. This relationship easily explains highly pelitic character of the Meetinghouse with upward-coarsening character of Lower Devonian sequences elsewhere in map area. Meetinghouse Slate Member includes volcanic facies (Moench and others, 1995).
Hoosac Formation, Plymouth Member (Cambrian)
Hoosac Formation, Plymouth Member - Quartzite, schistose quartzite, dolomitic quartzite; carbonaceous phyllite; buff to dark gray dolomite with partings locally of carbonaceous phyllite; quartz-sericite-chlorite-albite schist; carbonaceous albite schist. (Southern and Central Vermont). Revised the Plymouth Member of the Hoosac Formation of Doll and others (1961) to the Plymouth Formation. Consists of a series of feldspathic and dolomitic quartzites, dolostones and black phyllites that overlie probable Middle Proterozoic gneisses. The Plymouth Formation can be divided into several informal members. The lower contact of the formation is below a sequence of dolomitic quartzites or thin bedded quartzite. Dark laminated silty phyllites laterally replace the more feldspathic quartzites and dark-gray schistose quartzites, massive vitreous quartzites, and dolomitic quartzites pass upward to the east into well bedded cream-weathered light-gray dolostone breccia; these lithologies make up the dolostone member of the Plymouth Formation. The upper member of the Plymouth Formation is a black graphitic and siliceous phyllite that contains 1 to 3 cm thick layers of dark-gray ferruginous quartzite, dolomitic quartzite, and ribbony beds of dolostone. The upper contact of the Plymouth Formation is placed at the first occurrence of light-silvery-green magnetite-muscovite-quartz knotted phyllites of the Pinney Hollow Formation (Ratcliffe, 1994).
Hortonville Formation (Ordovician)
Hortonville Formation - Black, carbonaceous and pyritic slate and phyllite, locally sandy; brown weathered limy beds are common near base. Occurs east of Highgate Springs, Champlain, and Orwell thrusts.
Hortonville, or Cumberland Head, and Glens Falls Formations, Undifferentiated (Ordovician)
Hortonville, or Cumberland Head, and Glens Falls Formations, Undifferentiated - Hortonville or Cumberland Head is combined with Glens Falls where the boundary with the Glens Falls is widely covered by surficial deposits, also where the Cumberland Head thins.
Littleton Formation (Devonian)
Littleton Formation - Gray slate and phyllite containing interbeds of gray schistose quartzite 1/4 inch to 6 inches thick. West of Guildhall are lustrous, light to dark gray biotite-garnet phyllite and schist, some slate, and subordinate quartzite and impure quartzite. South of Bellows Falls gray phyllite passes eastward into gray mica schist containing porphyroblasts of biotite, garnet, and staurolite.
Missisquoi Formation (Ordovician)
Missisquoi Formation - Carbonaceous phyllite and slate, black to light gray (where extensive enough to show on map).
Missisquoi Formation, Cram Hill Member (Ordovician)
Missisquoi Formation, Cram Hill Member - Pale greenish-gray to black phyllite grades locally into gray to black slate; felsic to mafic volcanic rocks.
Missisquoi Formation, Harlow Bridge Quartzite Member (Ordovician)
Missisquoi Formation, Harlow Bridge Quartzite Member - Buff to pale-green quartzite with interbeds of quartz-sericite-chlorite phyllite.
Missisquoi Formation, Moretown Member (Ordovician)
Missisquoi Formation, Moretown Member - Quartzite and quartz-plagioclase granulite, in layers 1/8 to several inches thick, separated by "pinstripe" partings that contain muscovite, chlorite, epidote, biotite, and locally garnet; also greenish quartz-sericite-chlorite phyllite and schist, and minor carbonaceous phyllite. Schist and phyllite commonly contain biotite and garnet porphyroblasts in southern Vermont.
Missisquoi Formation, Umbrella Hill Member (Ordovician)
Missisquoi Formation, Umbrella Hill Member - Quartz and slate pebble phyllitic conglomerate with interbeds of slate and phyllite - chiefly quartz-sericite-magnetite-chloritoid rocks.
Missisquoi Formation, Whetstone Hill Member (Ordovician)
Missisquoi Formation, Whetstone Hill Member - Carbonaceous black to light gray phyllite and schist containing porphyroblasts of biotite and garnet; beds of gray micaceous quartzite, fine-grained biotite gneiss and amphibolite.
Moosalamoo Phyllite (Cambrian)
Moosalamoo Phyllite - Gray to black sericite-quartz phyllite; sericite-quartz-chlorite phyllite occurs locally.
Northfield Formation (Devonian - Silurian)
Northfield Formation - Dark gray to black quartz-sericite slate or phyllite with fairly widely-spaced interbeds a few inches thick of siltstone and silty crystalline limestone like that of the Waits River Formation; calcareous slate north of Lamoille River; phyllite passes into gray quartz-sericite schist containing abundant porphyroblasts of biotite and garnet in southern Vermont.
Orfordville Formation (Ordovician)
Orfordville Formation - Carbonaceous phyllite; minor quartzite.
Ottauquechee Formation (Cambrian)
Ottauquechee Formation - Black carbonaceous phyllite or schist containing interbeds of massive quartzite commonly criss-crossed by veins of white quartz; quartzite is dark gray and carbonaceous, light gray, or white; also includes light green quartz-sericite-chlorite phyllite or schist and sercitic quartzite; beds of phyllitic graywacke and feldspar granule conglomerate are north of Lamoille River. Schist contains abundant porphyroblasts of garnet and biotite from Ludlow south. The Ottauquechee contains two major units: A black phyllite and the Thatcher Brook Member. The black phyllite contains a previously unreported sub-unit of gray carbonate schist. The Thatcher Brook Member (named in an abstract by Armstrong and others, 1988) is a carbonaceous albitic schist with greenstones and ultramafics. These rocks have previously been included in the Ottauquechee but have never been differentiated from the black phyllite. Member is in fault contact with the silvery green schist of the Pinney Hollow Formation to the west. Age is Cambrian (Ratcliff, in press).
Partridge Formation (Ordovician)
Partridge Formation - Dull gray to sooty black carbonaceous slate and phyllite; mostly fissile, but locally massive and tough. Contains a few beds of both schistose and massive soda-rhyolite tuff (not shown on map). (Northeastern Vermont).
Pinney Hollow Formation (Cambrian)
Pinney Hollow Formation - Pale green quartz-sericite (muscovite-paragonite)-chlorite phyllite and schist with abundant magnetite, chloritoid phyllite and schist, quartz-sericite-albite-chlorite schist, and rare beds of carbonaceous and schistose quartzite; garnet porphyroblasts common south of Ottauquechee River. (Southern and Central Vermont).
Pinney Hollow Formation, carbonaceous phyllite and schist (Cambrian)
Pinney Hollow Formation, carbonaceous phyllite and schist. (Southern and Central Vermont).
St. Catherine Formation (Cambrian)
St. Catherine Formation - Purple, gray-green, and variegated slate and phyllite containing minor interbeds of white to green quartzite; locally albitic. Purple and green chloritoid-bearing slate and phyllite is within dashed line in northern Taconic Range, but not separated farther south.
Stowe Formation (Cambrian-Ordovician)
Stowe Formation - Quartz-sericite (muscovite-paragonite)-chlorite phyllite and schist; porphyroblasts of albite, garnet, chloritoid, or kyanite common locally; includes phyllitic graywacke north of Lamoille River. Schist contains abundant segregations of granular white quartz. The Stowe Formation in the study are contains two unnamed members: a silvery green schist and a greenstone. The schist is a fine-grained, silvery to dark green quartz-muscovite-albite-chlorite schist. It is in fault contact with the black phyllite of the Ottauquechee Formation. The greenstone is a homogenous, fine-grained, light green actinolite-albite-epidote-calcite-chlorite schist. Large outcrops of the resistant greenstone are common. Age according to map symbols is Proterozoic and Cambrian. Unit is correlated with the Rowe Schist (of Zen, 1983). [Rowe Schist on 1983 MA map is Cambrian and Ordovician. No explanation here for older age.] (Walsh, 1992).
Stowe Formation, carbonaceous schist and phyllite (Cambrian-Ordovician)
Stowe Formation, carbonaceous schist and phyllite - north of Lamoille River. Occurs in several small areas to the south, not shown on map.
Tyson Formation (Cambrian)
Tyson Formation - Feldspathic quartz-mica schist containing biotite, chlorite, and carbonate; many beds contain pebbles of quartz and feldspar; cobble or boulder conglomerate commonly at base; thin beds of quartzite, carbonaceous phyllite, and schistose dolomite in upper part, overlain at top by massive buff dolomite as much as 30 ft thick. (Southern and Central Vermont). The Tyson Formation contains grits and conglomerates at its base that unconformably overlie basement. The conglomerates and grits are as much as 150 m thick and contain lenses of dolomitic quartzite and feldspathic grit. Unit also contains black carbonaceous phyllite and interbedded dolostone as much as 100 m thick, followed by beige to tan weathering beds of dolostone that increase in abundance toward the top of the unit and pass into punky weathering dolomitic and feldspathic quartzite at the top. From a point near the southwest corner of the Andover quad, the rocks of the Tyson Formation are laterally replaced by albitic schists and granofels of the Hoosac Formation to the south. Therefore, Tyson laterally replaces the Hoosac from south to north along the eastern margin of the Green Mountain massif. The Tyson Formation is of Late Proterozoic(?) and Early Cambrian age (Ratcliffe, 1994).
Underhill Formation (Cambrian)
Underhill Formation - Silvery, gray-green, quartz-sericite-albite-chlorite-biotite schist, containing abundant lenticular segregations of granular white quartz; locally quartz-sercite-albite-chlorite phyllite; porphyroblasts of albite, garnet, and magnetite are common and locally very abundant in gneissic facies in axial anticlines of the Green Mountain anticlinorium . (Northern and Central Vermont). In study area consists mainly of greenish quartz-chlorite-sericite phyllites lying stratigraphically between Pinnacle and Cheshire Formations, where author would place rocks of type locality within Underhill facies of Pinnacle Formation, for they are clearly stratigraphically equivalent to rocks of Pinnacle Formation in Enosburg area, being below an excellent horizon marker, the Whitebrook dolomite and slate. However, Underhill facies of the Pinnacle and phyllites of Underhill Formation are practically indistinguishable in the field, and it is unavoidable, wherever dividing White Brook dolomite and slate are absent, to map all rocks of Underhill facies as one unit. In western part of outcrop belt, Underhill rocks are well defined between White Brook Dolomite or coarse Pinnacle graywacke below and Cheshire Formation above. Rocks in this clearly defined area are here recognized as Fairfield Pond Member. As mapped, the Underhill includes Fairfield Pond Member, Bakersfield Greenstone, Peaked Mountain Greenstone, White Brook Member, Jay Peak Member, and West Sutton Slate Member. Eastern facies of Underhill is named Bonsecours facies (Dennis, 1964).
Underhill Formation, carbonaceous quartz-sericite-albite-chlorite schist and phyllite. (Cambrian)
Underhill Formation, carbonaceous quartz-sericite-albite-chlorite schist and phyllite. (Northern and Central Vermont).
Underhill Formation, Fairfield Pond Member (Cambrian)
Underhill Formation, Fairfield Pond Member - Greenish quartzitic schist (quartz-sericite-albite-chlorite-biotite); sericite-quartz-chlorite phyllite, locally purple or red, common in lower part. (Northern and Central Vermont).
Waits River Formation (Devonian)
Waits River Formation - Gray quartzose and micaceous crystalline limestone weathered to distinctive brown earthy crust; interbedded and intergradational with gray quartz-muscovite phyllite or schist. Where more metamorphosed the limestones contain actinolite, hornblende, zoisite, diopside, wollastonite, and garnet, and the phyllite and schist, biotite, garnet, and locally andalusite, kyanite or sillimanite.
Waits River Formation, Ayers Cliff Member (Devonian)
Waits River Formation, Ayers Cliff Member - Siliceous crystalline limestone containing thin beds of slate and phyllite north of the Lamoille River.
Waits River Formation, Barton River Member (Devonian)
Waits River Formation, Barton River Member - Interbedded siliceous crystalline limestone and sercite-quartz-chlorite phyllite in northern Vermont; diopsidic limestone and cordierite hornfels at contacts with granitic dikes and sills.
Washington
Cambrian limestone and dolomite (Early Cambrian-Middle Ordovician)
Mostly massive dolomite, with a basal unit of gray to dark-gray limestone interbedded with limy shale, and an upper unit of fine-grained massive limestone with some marble; Pend Oreille and northern and central Stevens Counties. Three-fold division less evident in Colville area. Dolomite, with minor basal unit of interbedded limestone and phyllite in the Addy-Dunn Mountain area of Stevens County. Marble, dolomite, limestone, and limy slate in Hunters' district. Dolomitic marble in southern Stevens and northern Lincoln Counties. Middle Cambrian fossils near base in Metaline district, and Bathyuriscus-Elrathina fauna in lower unit in Leadpoint district. Phosphatic brachiopods in upper unit in Leadpoint district tentatively assigned to Middle and Upper Cambrian.
Cambrian phyllite (Cambrian)
Predominantly gray-green, banded phyllite, some sericite schist, abundant thin beds of quartzite, especially in lower part of unit, and limestone in upper part; northern Pend Oreille County. Much the same lithology but more conspicuous subunits of quartzite, limestone, and schist in northeastern Stevens County. Gray phyllite, greenish argillite, andalusite schist, minor inerbedded quartzite and siliceous dolomite, especially in lower part, and much gray limestone in upper part; north-central Stevens County. Limestone bed in lower part of unit contains Lower Cambrian fossils (Archaeocyathus).
Cambrian quartzite (Cambrian)
Gritstone with conglomerate in lower part and gray, white, and buff platy quartzite in upper part grading upward into phyllite; northern Pend Oreille County. Light-gray, platy, medium- to thick-bedded quartzite in upper part and darker impure quartzite with some interbedded argillite or phyllite in lower part; north-central Stevens County. White, gray, and reddish, medium- to thick-bedded quartzite in lower part and thin interbeds of quartzite and argillite in upper part, with very low Lower Cambrian fossils (Nevadia, Hyolthellus, and three genera of brachipods) near base of upper part; Addy district of central Stevens County. Thick argillite and thin quartzite units form an uppermost zone in southwestern Stevens County. Conspicuous phyllite units near base in north-central Lincoln County.
Carboniferous-Permian sedimentary and volcanic rocks (Devonian to Permian; some Jurassic)
Sedimentary and volcanic rocks, undivided. Cherty and slaty argillite, siltstone, graywacke, chert, greenstone, tuff, andesite, and spilitic volcanics.
Carboniferous-Permian sedimentary and volcanic rocks (Devonian to Permian, minor Mesozoic)
Predominantly sedimentary rocks. Graywacke, argillite, and slate; includes minor marble, siltstone, arkose, conglomerate, ribbon cherts, and volcanic rocks. Some Devonian rocks may be included in northwestern Washington.
Cretaceous sedimentary rocks, mostly marine (Cretaceous)
Lower Cretaceous greenish-gray massive arkosic sandstone and light-gray sandy shale in western Okanogan County. Includes phyllite in eastern Whatcom County.
Mesozoic-Tertiary marine rocks, undivided (Miocene to Eocene)
Dark-gray, massive to poorly bedded gray-wacke of the interior Olympic Peninsula; commonly with interbedded slate, argillite, volcanic rocks, and minor arkosic sandstone. Includes rocks both older and younger than Ev2, some of which may be Paleozoic.
Ordovician rocks (Middle Ordovician)
Mainly black to gray slate or slaty argillite, argillite, black to dark-gray siltstone in north-central Stevens County and grayish olive-green silty argillite in west-central Stevens County. Many occurrences of Early and Middle Ordovician graptolites; also rare conodonts.
Precambrian conglomerate (Late-Proterozoic)
Gray-brown, coarse, poorly sorted pebbles and cobbles of limestone, dolomite, reddish-brown quartzite, black slate or phyllite, and rarely granitic rocks in a gray sandy phyllite matrix; northeastern Pend Oreille County and southwestern Stevens County. Rocks become finer grained and more schistose and the unit becomes thicker toward the southwest, where there is included an isolated subunit which may be a tillite, consisting of cobbles, boulders, and blocks of argillite and carbonate rocks in a fine silty matrix.
Precambrian (?) phyllite (Cambrian-Precambrian boundary)
Mostly phyllite with interbedded carbonate rocks, quartzite, and gritstone; some tufflike beds and conglomerate at the base. Rocks confined to northeastern Pend Oreille County and central Stevens County.
Precambrian rocks, undivided (Proterozoic)
Predominantly phyllite with some schist, limestone, dolomite, quartzite, and volcanic rocks; northeastern Pend Oreille County. Mainly quartzite sandstone in upper part, dark-gray argillite with sandstone and limestone in middle part, and sandstone with argillite in lower part; southeastern Pend Oreille County. Banded slate with quartzite and dolomite; southwestern Stevens County. Quartzite, siliceous argillite, and argilliceous quartzite grading into argillite and quartz-mica schists form south ot north; southeastern Stevens County. Quartzite, argillite, quartz-feldspar gneiss, and other metamorphic rocks in northeastern Whitman and southeastern Spokane Counties are partly if not all extenstions of the Belt strata.
Pre-Middle Jurassic sedimentary and volcanic rocks (Jurassic)
Predominantly sedimentary rocks. Graywacke, argillite, and slate; includes minor marble, siltstone, arkose, conglomerate, ribbon cherts, and volcanic rocks.
Pre-Tertiary metamorphic rocks, undivided (Probably Permian)
Schist, gneiss, marble, quartzite, amphibolite, greenstone, metaconglomerate, graywacke; includes metasedimentary, volcanic, and intrusive rocks. Some areas, as on San Juan Islands, show little if any metamorphism.
Pre-Tertiary sedimentary and metasedimentary rocks, undivided (Mostly Early Cretaceous to Middle Jurassic, possibly includes minor Eocene rocks)
Graywacke, argillite, phyllite, chert, talc, and graphite schist; some faulted-in blocks of serpentinite and greenstone. Includes minor limestone on San Juan Island.
Pre-Tertiary ultrabasic intrusive rocks (Late-Jurassic)
Peridotite and pyroxenite; generally altered partly or completely to serpentine. Includes serpentinite and saxonite on Sumas Mountain, Whatcom County.
Pre-Upper Jurassic gneiss (Mostly Cretaceous)
Biotite, quartz diorite, trondhjemite, and hornblende gneisses, many of which are migmatitic; includes small granitic bodies locally. Small areas of mica schist, marble, amphibolite, and lime-silicate rocks in Entiat Mountains area of Chelan County.
Pre-Upper Jurassic metamorphic rocks of the low-grade zone (Jurassic)
Greenschist, phyllite, and slate; includes some limestone, quartzose phyllite, schistose metaconglomerate, breccia, and basic igneous rocks. Includes schist locally.
Pre-Upper Jurassic metamorphic rocks of the medium and high-grade zone (Early Jurassic-Triassic)
Schist, amphibolite, and minor lime-silicate rocks, marble, quartzite, and metaconglomerate.
Upper Jurassic-Lower Cretaceous sedimentary and volcanic rocks (Late Cretaceous-Jurassic)
Sedimentary and volcanic rocks, undivided. Graywacke, argillite, siltstone, slate, volcanic rocks, phyllite, greenschist, and greenstone.
Upper Jurassic-Lower Cretaceous sedimentary and volcanic rocks (Late Jurassic-Early Cretaceous)
Predominantly sedimentary rocks. Graywacke, argillite, and siltstone with some slate and phyllite; includes graywacke breccia and ribbon chert with minor local limestone lenses and basalt flows.
Upper Paleozoic rocks, undivided (Ordovician)
Mostly graywacke, interbedded quartzite and phyllite, greenstone and serpentine, and black shale with minor limestone. Some quartz-mica schist in Bald Knob area of Ferry County. Schist, gneiss, and amphibolite in other parts of Ferry County. Some rocks of lower Paleozoic age, possibly Precambrian, and Mesozoic may be included.
West Virginia
Harpers Formation (Cambrian)
Harpers Formation (Chilhowee Group) - greenish-gray phyllite, with interbeds of fine-grained quartzite.

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://tin.er.usgs.gov/geology/state/sgmc-lith.php?text=phyllite
Page Contact Information: pschweitzer@usgs.gov
Page Last modified: 16:23 on 25-Apr-2014