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Mineral Resources > Online Spatial Data > Geology > by state > New Jersey Geology

Geologic units in Warren county, New Jersey

Albite-Oligoclase Granite (Middle Proterozoic) at surface, covers 0.3 % of this area

Albite-Oligoclase Granite - White-weathering, light-greenish-gray, medium- to coarse-grained granite composed of albite or oligoclase, quartz, and sparse amounts of hornblende or clinopyroxene. Petrogenetically related to quartz-oligoclase gneiss (Ylo) but Yla has a more granulitic texture. Includes small bodies of pegmatite not shown on map.

Lithology: granite; pegmatite

Wantage Sequence (Middle Ordovician) at surface, covers < 0.1 % of this area

Wantage Sequence (Monteverde and Herman, 1989) - Restricted, discontinuous sequence of interbedded limestone, dolomite, conglomerate, siltstone, and shale. Upper part is medium-yellowish-brown- to olive-gray-weathering, medium- to dark-gray, very fine to fine-grained, laminated to massive limestone and dolomite that grade down into underlying clastic rocks of lower part. Upper part locally absent. Lower part ranges from grayish-red, medium-gray, pale-brown, and greenish-gray to pale-green mudstone and siltstone containing disseminated subangular to subrounded chert-gravel, quartz-sand lenses, and chert-pebble conglomerate. Lower contact unconformable. Thickness ranges from 0 to 46 m (0-150 ft).

Lithology: limestone; dolostone (dolomite); conglomerate; siltstone; shale; chert

Hornblende Syenite (Middle Proterozoic) at surface, covers 1 % of this area

Hornblende Syenite - Tan- to buff-weathering, pinkish-gray or greenish-gray, medium- to coarse-grained, gneissoid syenite and lesser amounts of quartz syenite containing microcline microperthite, oligoclase, quartz, and hornblende. Some phases are monzonite or monzodiorite.

Lithology: syenite; quartz syenite; monzonite; monzodiorite

Allentown Dolomite (Lower Ordovician and Upper Cambrian) (Wherry, 1909) (Lower Ordovician and Upper Cambrian) at surface, covers 22 % of this area

Allentown Dolomite (Lowest Lower Ordovician and Upper Cambrian) (Wherry, 1909) - Medium- to very light gray, fine- to medium-grained, very thin to very thick bedded dolomite containing minor orthoquartzite and shale. Oolites and algal stromatolites occur throughout unit. Shaly dolomite increases downward towards lower conformable contact with the Leithsville Formation. Unit does not crop out but is known from subsurface borings near Flanders (Volkert and others, 1990). Thickness ranges from 0 to 73 m (0-240 ft) due to erosion.

Lithology: dolostone (dolomite); orthoquartzite; shale

Martinsburg Formation (Ordovician) at surface, covers < 0.1 % of this area

Martinsburg Formation - Gray to dark-gray, buff-weathering shale.

Lithology: shale

Ramseyburg Member (Upper and Middle Ordovician) at surface, covers 14 % of this area

Ramseyburg Member (Drake and Epstein, 1967) - Interbedded medium- to dark-gray, to brownish-gray, fine- to medium-grained, thin- to thick-bedded graywacke sandstone and siltstone and medium- to dark-gray, laminated to thin-bedded shale and slate. Unit may form complete turbidite sequences, Tabcde (Bouma, 1962), but basal cutout sequences Tcde dominate. Basal scour, sole marks, and soft-sediment distortion of beds are common in graywacke. Thermally metamorphosed near intrusive bodies. Lower contact placed at bottom of lowest thick- to very thick bedded graywacke, but contact locally grades through sequence of dominantly thin-bedded shale and slate and minor thin- to medium-bedded discontinuous and lenticular graywacke beds in the Bushkill member. Parris and Cruikshank (1992) correlate unit with Orthograptus ruedemanni to lowest part of Climacograptus spiniferus zones of Riva (1969, 1974). Thickness ranges from 640 m (2,100 ft) in Delaware River Valley, to 1,524 m (5,000 ft) near Stillwater, to 1067 m (3,500 ft) at New York State line.

Lithology: graywacke; siltstone; shale; slate

Jacksonburg Limestone and Sequence at Wantage, undivided (Middle Ordovician) at surface, covers 0.3 % of this area

Jacksonburg Limestone and Sequence at Wantage, undivided - Jacksonburg Limestone - Upper part is medium- to dark-gray, laminated to thin-bedded shaly limestone and less abundant medium-gray arenaceous limestone containing quartz-sand lenses. Upper part thin to absent to northeast. Lower part is interbedded medium- to dark-gray, fine- to medium-grained, very thin to medium-bedded fossiliferous limestone and minor medium- to thick-bedded dolomite-cobble conglomerate having a limestone matrix. Unconformable on Beekmantown Group and conformable on the discontinuous sequence at Wantage in the Paulins Kill area. Contains conodonts of North American midcontinent province from Phragmodus undatus to Aphelognathus shatzeri zones of Sweet and Bergstrom (1986). Thickness ranges from 41 to 244m (135-800 ft). Sequence at Wantage - Restricted, discontinuous sequence of interbedded limestone, dolomite, conglomerate, siltstone, and shale. Upper part is medium-yellowish-brown- to olive-gray-weathering, medium- to dark-gray, very fine to fine-grained, laminated to massive limestone and dolomite that grade down into underlying clastic rocks of lower part. Upper part locally absent. Lower part ranges from grayish-red, medium-gray, pale-brown, and greenish-gray to pale-green mudstone and siltstone containing disseminated subangular to subrounded chert-gravel, quartz-sand lenses, and chert-pebble conglomerate. Lower contact unconformable. Thickness ranges from 0 to 46 m (0-150 ft).

Lithology: limestone; dolostone (dolomite); conglomerate; siltstone; shale; chert

Bloomsburg Red Beds (Upper Silurian) at surface, covers 3 % of this area

Bloomsburg Red Beds (White, 1883) (High Falls Shale of previous usage) - Grayish-red, thin- to thick-bedded, poorly to moderately well sorted, massive siltstone, sandstone, and local quartz-pebble conglomerate containing local planar to trough crossbedded laminations. Conglomerate consists of matrix-supported quartz pebbles in grayish-red, fine-grained sandstone matrix. Locally, near base of unit, is greenish-gray, light-gray, or grayish-orange, massive, planar tabular to trough crossbedded quartz sandstone to siltstone with subrounded grains. Lower part of formation marked by several upward-fining sequences of light-gray sandstone grading through grayish-red, fine-grained sandstone and siltstone to grayish-red, mudcracked siltstone and mudstone. Each sequence is 1 to 3 m (3-10 ft) thick. Lower contact placed at bottom of lowermost red sandstone. Thickness approximately 460 m (1,510 ft).

Lithology: siltstone; sandstone; conglomerate; mudstone

Leithsville Formation (Middle and Lower Cambrian) at surface, covers 5 % of this area

Leithsville Formation (Middle and Lower Cambrian) (Wherry, 1909) - Light- to dark-gray and lightolive-gray, fine- to medium-grained, thin- to medium-bedded dolomite. Grades downward through medium-gray, grayish-yellow, or pinkish-gray dolomite and dolomitic sandstone, siltstone and shale to medium-gray, medium-grained, medium-bedded dolomite containing quartz sand grains as stringers and lenses near the base. Lower contact gradational. Thickness ranges from 0 to 56 m (0-185 ft) due to erosion.

Lithology: dolostone (dolomite); shale; siltstone; sandstone

Clinopyroxene-Quartz-Feldspar Gneiss (Middle Proterozoic) at surface, covers 0.2 % of this area

Clinopyroxene-Quartz-Feldspar Gneiss - Pinkish-gray- or pinkish-buff-weathering, white to pale-pinkish-white or light-gray, fine- to medium-grained, massive to moderately well-layered gneiss composed of microcline, quartz, oligoclase, clinopyroxene, and trace amounts of epidote, biotite, titanite, and opaque minerals. Commonly interlayered with amphibolite or pyroxene amphibolite.

Lithology: paragneiss; amphibolite

Biotite Granite (Middle Proterozoic) at surface, covers 0.3 % of this area

Biotite Granite - Pink- to buff-weathering, light-pinkish-gray, medium-grained, massive, moderately foliated granite composed of microcline microperthite, quartz, oligoclase, and biotite.

Lithology: granite

Pyroxene-Epidote Gneiss (Middle Proterozoic) at surface, covers 1 % of this area

Pyroxene-Epidote Gneiss - White- to light-gray-weathering, light-greenish-gray or greenish-buff, fine- to medium-grained, moderately layered and foliated gneiss composed principally of quartz, microcline, plagioclase, clinopyroxene, epidote, and sparse amounts of titanite. Some phases of this unit are quartz-rich. May be interlayered and probably related to pyroxene gneiss (Yp).

Lithology: paragneiss

Pyroxene Gneiss (Middle Proterozoic) at surface, covers 2 % of this area

Pyroxene Gneiss - White- to tan-weathering, greenish-gray, fine- to medium-grained, well-layered gneiss containing oligoclase, clinopyroxene, variable amounts of quartz, and trace amounts of opaque minerals and titanite. Some phases contain scapolite and calcite. Commonly interlayered with pyroxene amphibolite or marble.

Lithology: paragneiss; amphibolite; marble

Amphibolite (Middle Proterozoic) at surface, covers 1 % of this area

Amphibolite - Gray- to grayish-black, medium-grained amphibolite composed of hornblende and andesine. Some phases contain biotite and (or) clinopyroxene. Ubiquitous and associated with almost all other Middle Proterozoic units. Some amphibolite is clearly metavolcanic in origin, some is metasedimentary, and some appears to be metagabbro.

Lithology: amphibolite

Felsic to mafic gneiss (Precambrian) at surface, covers < 0.1 % of this area

Felsic to mafic gneiss - Light, medium grained; predominantly quartz and feldspar of igneous origin.

Lithology: felsic gneiss; mafic gneiss; orthogneiss

Beekmantown Group, Lower Part (Lower Ordovician) at surface, covers 8 % of this area

Beekmantown Group, Lower Part (Clarke and Schuchert, 1899) - Very thin to thick-bedded, interbedded dolomite and minor limestone. Upper beds are light-olive-gray to dark-gray, fine- to medium-grained, thin- to thick-bedded dolomite. Middle part is olivegray-, light-brown-, or dark-yellowish-orange- weathering, dark-gray, aphanitic to fine-grained, laminated to medium-bedded dolomite and light-gray to light-bluish-gray-weathering, medium-dark- to dark-gray, fine-grained, thin- to medium-bedded limestone, that is characterized by mottling with reticulate dolomite and light-olive-gray to grayish-orange, dolomitic shale laminae surrounding limestone lenses. Limestone grades laterally and down section into medium- gray, fine-grained dolomite. Lower beds consist of medium-light- to dark-gray, aphanitic to coarse-grained, laminated to medium-bedded, locally slightly fetid dolomite having thin black chert beds, quartz-sand laminae, and oolites. Lenses of light-gray, very coarse to coarse-grained dolomite and floating quartz sand grains and quartz-sand stringers at base of sequence. Lower contact placed at top of distinctive medium-gray quartzite. Contains conodonts of Cordylodus proavus to Rossodus manitouensis zones of North American Midcontinent province as used by Sweet and Bergstrom (1986). Unit Obl forms Stonehenge Formation of Drake and Lyttle (1985) and Drake and others (1985), upper and middle beds are included in Epler Formation, and lower beds are in Rickenbach Dolomite of Markewicz and Dalton (1977). Unit is about 183 m (600 ft) thick.

Lithology: dolostone (dolomite); limestone; chert

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

Trenton Gravel - Gray or pale-reddish-brown, very gravelly sand interstratified with crossbedded sand and clay-silt beds; includes areas of Holocene alluvium and swamp deposits.

Lithology: sand; clay or mud; silt; gravel; alluvium

Bushkill Member (Middle Ordovician) at surface, covers 9 % of this area

Bushkill Member (Drake and Epstein, 1967) - Interbedded medium- to dark gray, thinly laminated to thick-bedded shale and slate and less abundant medium-gray to brownish-gray, laminated to thin-bedded siltstone. To the southwest, fine-grained, thin dolomite lenses occur near base. Complete turbidite sequences (Bouma, 1962) occur locally, but basal cutout sequences (Tbcde, Tcde or Tde) dominate. Conformable lower contact is placed at top of highest shaly limestone; elsewhere, lower contact is commonly strain slipped. Correlates with graptolite Climacograptus bicornis to Corynoides americanus zones of Riva (1969, 1974) (Parris and Cruikshank, 1992). Thickness ranges from 1,250 m (4,100 ft) in Delaware River Valley to 457 m (1,500 ft) at New York State line.

Lithology: slate; shale; siltstone; dolostone (dolomite)

Hornblende gneiss (Precambrian) at surface, covers < 0.1 % of this area

Hornblende gneiss - Dark, medium grained; includes some rocks of probable sedimentary origin.

Lithology: mafic gneiss; paragneiss

Shawangunk Formation (Middle and Lower Silurian) at surface, covers 3 % of this area

Shawangunk Formation (Mather, 1840; Epstein and Epstein, 1972) - Upper part is medium- to medium-dark-gray, or dark-greenish-gray, medium- to thick-bedded sandstone and pebble conglomerate having well rounded grains, some of which are limonite stained. Conglomerate consists of matrix-supported quartz and subordinate shale pebbles as long as 5 cm (2 in.) in poorly to well-sorted, planar tabular to trough crossbedded sandstone. Local black to dark-greenish-gray, thin-bedded shale near upper contact. Middle part, occurring in southwest and sporadically in northeast, is light- to medium-dark-gray, greenish-gray, interbedded thin- to medium-bedded, planar tabular to trough cross-bedded shale and sandstone. Grains are well rounded and moderately to well sorted. Contains sparse graphite flakes. Lower part is light- to medium-gray to light-olive-gray, thin- to thick-bedded quartz and feldspathic sandstone, quartzite, and quartz-pebble conglomerate, which is matrix-supported, poorly to well sorted, cross to planar bedded. Clasts are primarily quartz and sparse dark-gray argillite and black chert. Sandstone is feldspathic and locally approaches an arkose in compostion. Lower contact unconformable and, at places, is a fault of small displacement. Thickness approximately 427 m (1,400 ft).

Lithology: sandstone; conglomerate; shale

Pyroxene Granite (Middle Proterozoic) at surface, covers 2 % of this area

Pyroxene Granite - Gray- to buff- or white-weathering, greenish-gray, medium- to coarse-grained, massive, gneissoid to indistinctly foliated granite containing mesoperthite to microantiperthite, quartz, oligoclase, and clinopyroxene. Common accessory minerals include titanite, magnetite, apatite, and trace amounts of pyrite. Some phases are monzonite, quartz monzodiorite, or granodiorite. Locally includes small bodies of amphibolite not shown on map.

Lithology: granite; monzonite; quartz monzodiorite; granodiorite; amphibolite

Migmatite (Middle Proterozoic) at surface, covers 0.8 % of this area

Migmatite - Mixed rock consisting of amphibolite containing veins, lenses, layers, and irregular clots of albite-oligoclase granite or microperthite alaskite.

Lithology: migmatite

Franklin Marble (Middle Proterozoic) at surface, covers 1.0 % of this area

Franklin Marble - White- to light-gray-weathering, white, grayish-white, or, less commonly pinkish-orange, coarse- to locally fine-crystalline calcite marble with accessory amounts of graphite, phlogopite, chondrodite, clinopyroxene, and serpentine. Contains pods and layers of clinopyroxene-garnet skarn, hornblende skarn, and clinopyroxene-rich rock. Thin layers of metaquartzite occur locally. Intruded by the Mount Eve Granite in the Pochuck Mountain area. Franklin Marble is host to the Franklin and Sterling Hill zinc ore bodies; exploited for talc and asbestiform minerals near Easton, Pennsylvania. Subdivided into an upper marble, "Wildcat marble," and a lower marble, "Franklin marble," by New Jersey Zinc Co. geologists (Hague and others, 1956).

Lithology: marble; skarn (tactite); quartzite

Franklin Marble (Precambrian) at surface, covers < 0.1 % of this area

Franklin Marble - White, coarsely crystalline; disseminated graphite flakes.

Lithology: marble

Hornblende Granite (Middle Proterozoic) at surface, covers 5 % of this area

Hornblende Granite - Pinkish-gray- to medium-buff-weathering, pinkish-white or light-pinkish-gray, medium- to coarse-grained, gneissoid to indistinctly foliated granite and sparse granite gneiss composed principally of microcline microperthite, quartz, oligoclase, and hornblende. Some phases are quartz syenite or quartz monzonite. Includes small bodies of pegmatite and amphibolite not shown on map. U-Pb age approximately 1,090 Ma (Drake and others, 1991b).

Lithology: granite; paragneiss; quartz syenite; quartz monzonite; pegmatite; amphibolite

Hornblende-Quartz-Feldspar Gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Hornblende-Quartz-Feldspar Gneiss - Pinkish-gray- to buff-weathering, light- pinkish-white to pinkish-gray, fine- to medium-grained, massive to moderately well layered gneiss containing microcline, quartz, oligoclase, hornblende, and magnetite. Locally contains garnet and biotite.

Lithology: paragneiss

Rickenbach Formation (Ordovician) at surface, covers < 0.1 % of this area

Rickenbach Formation - Gray, very finely to coarsely crystalline, laminated dolomite; dark-gray chert in irregular beds, stringers, and nodules; bands of quartz sand grains in lower half.

Lithology: dolostone (dolomite); chert

Graywacke and shale of Martinsburg Formation (Ordovician) at surface, covers < 0.1 % of this area

Graywacke and shale of Martinsburg Formation - Abundant impure sandstone (graywacke) interbeds.

Lithology: graywacke

Biotite-Quartz-Feldspar Gneiss (Middle Proterozoic) at surface, covers 2 % of this area

Biotite-Quartz-Feldspar Gneiss - Gray-weathering, locally rusty, gray to tan or greenish-gray, fine- to medium-coarse-grained, moderately layered and foliated gneiss that is variable in texture and composition. Composed of oligoclase, microcline microperthite, quartz, and biotite. Locally contains garnet, graphite, sillimanite, and opaque minerals.

Lithology: paragneiss

Hypersthene-Quartz-Oligoclase Gneiss (Middle Proterozoic) at surface, covers 0.4 % of this area

Hypersthene-Quartz-Oligoclase Gneiss - Gray- to tan-weathering, greenish-gray to greenish-brown, medium-grained, moderately well layered and foliated, greasy-lustered gneiss of charnockitic affinity composed of andesine or oligoclase, quartz, clinopyroxene, hornblende, hypersthene, and sparse amounts of biotite. Commonly interlayered with amphibolite and mafic-rich quartz-plagioclase gneiss.

Lithology: gneiss; amphibolite

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

Allentown Formation - Medium- to medium-dark-gray, thick-bedded dolomite and impure limestone; dark-gray chert stringers and nodules; laminated; oolitic and stromatolitic; some orange-brown-weathering calcareous siltstone at base.

Lithology: dolostone (dolomite); limestone; chert; siltstone

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

Leithsville Formation - Medium- to dark-gray, crystalline dolomite, light-olive-gray in places, weathering to light gray and yellowish brown; massive bedded; oolitic; pink to gray, mottled chert and dark-gray chert; thin shale and dolomitic shale interbeds; scattered sand grains; upper part is very shaly.

Lithology: dolostone (dolomite); shale; chert; sand

Bloomsburg Formation (Silurian) at surface, covers < 0.1 % of this area

Bloomsburg Formation - Grayish-red siltstone, shale, and sandstone arranged in fining-upward cycles.

Lithology: siltstone; shale; sandstone

Pyroxene Syenite (Middle Proterozoic) at surface, covers 0.3 % of this area

Pyroxene Syenite - Gray- to buff- or tan-weathering, greenish-gray, medium- to coarse-grained, massive, indistinctly foliated syenite composed of mesoperthite to microantiperthite, oligoclase and clinopyroxene. Contains sparse amounts of quartz, titanite, magnetite, and trace amounts of pyrite.

Lithology: syenite

Microantiperthite Alaskite (Middle Proterozoic) at surface, covers 0.4 % of this area

Microantiperthite Alaskite - White-weathering, locally rusty, light-greenish-gray medium- to coarse-grained, gneissic granite and alaskite containing microantiperthite, quartz, oligoclase, and sparse amounts of hornblende, clinopyroxene, biotite, and magnetite.

Lithology: granite

Beekmantown Group, Upper Part (Lower Ordovician) at surface, covers 4 % of this area

Beekmantown Group, Upper Part (Clarke and Schuchert, 1899) - Locally preserved upper beds are light- to medium-gray- to yellowish-gray-weathering, medium-light- to medium-gray, aphanitic to medium-grained, thin- to thick-bedded, locally laminated, slightly fetid dolomite. Medium-dark to dark-gray, fine-grained, medium-bedded, sparsely fossiliferous limestone lenses occur locally. Lower beds are medium-dark- to dark-gray, medium- to coarse-grained, mottled surface weathering, medium- to thick-bedded, strongly fetid dolomite that contains pods and lenses of dark-gray to black chert. Cauliflower-textured black chert beds of variable thickness occur locally. Gradational lower contact is placed at top of laminated to thin-bedded dolomite of the lower part (Obl) of the Beekmantown Group. Contains conodonts high in the Rossodus manitouensis zone to low zone D of the North American midcontinent province as used by Sweet and Bergstrom (1986). Upper beds are included in Epler Formation; lower beds are included in Rickenbach Dolomite of Drake and Lyttle (1985) and Drake and others (1985); entire upper part (Obu) is Ontelaunee Formation of Markewicz and Dalton (1977). Thickness ranges from 0 to 244 m (0-800 ft).

Lithology: dolostone (dolomite); limestone

Hardyston Quartzite (Lower Cambrian) at surface, covers 1 % of this area

Hardyston Quartzite (Lower Cambrian) (Wolff and Brooks, 1898) - Light- to medium-gray and bluish-gray conglomeratic sandstone. Varies from pebble conglomerate, to fine-grained, well-cemented quartzite, to arkosic or dolomitic sandstone. Conglomerate contains subangular to subrounded white quartz pebbles up to 2.5 cm (1 in.). Lower contact unconformable. About 0 to 9 m (1-30 ft) thick.

Lithology: quartzite; conglomerate; sandstone

Pyroxene Alaskite (Middle Proterozoic) at surface, covers 0.5 % of this area

Pyroxene Alaskite - Light-gray- or tan-weathering, greenish-buff to light-pinkish-gray, medium- to coarse-grained, massive, moderately foliated granite composed of mesoperthite to microantiperthite, oligoclase, and quartz. Common accessory minerals are clinopyroxene, titanite and magnetite. Locally includes small bodies of amphibolite not shown on map.

Lithology: granite; amphibolite

Epler Formation (Ordovician) at surface, covers < 0.1 % of this area

Epler Formation - Very finely crystalline, light-gray limestone interbedded with gray dolomite; coarsely crystalline limestone lenses present.

Lithology: limestone; dolostone (dolomite)

Jacksonburg Limestone (Middle Ordovician) at surface, covers 2 % of this area

Jacksonburg Limestone (Kummel, 1908; Miller, 1937) - Upper part is medium- to dark-gray, laminated to thin-bedded shaly limestone and less abundant medium-gray arenaceous limestone containing quartz-sand lenses. Upper part thin to absent to northeast. Lower part is interbedded medium- to dark-gray, fine- to medium-grained, very thin to medium-bedded fossiliferous limestone and minor medium- to thick-bedded dolomite-cobble conglomerate having a limestone matrix. Unconformable on Beekmantown Group and conformable on the discontinuous sequence at Wantage in the Paulins Kill area. Contains conodonts of North American midcontinent province from Phragmodus undatus to Aphelognathus shatzeri zones of Sweet and Bergstrom (1986). Thickness ranges from 41 to 244m (135-800 ft).

Lithology: limestone; conglomerate

Chestnut Hill Formation (Late Proterozoic) at surface, covers < 0.1 % of this area

Chestnut Hill Formation (Drake, 1984) - Interbedded arkose, ferruginous quartzite, quartzite conglomerate, metarhyolite, and metasaprolite. Confined to a few small areas north and east of Phillipsburg, on the western side of Bowling Green Mountain, northwest of High Bridge, and a few areas too small to show at this map scale.

Lithology: arkose; quartzite; conglomerate; meta-rhyolite

Microperthite Alaskite (Middle Proterozoic) at surface, covers 0.8 % of this area

Microperthite Alaskite - Pink- to buff-weathering, light-pinkish-gray or pinkish-white, medium- to coarse-grained, gneissoid to indistinctly foliated granite composed principally of microcline microperthite, quartz and oligoclase. Includes small bodies of amphibolite not shown on map.

Lithology: granite; amphibolite

Biotite-quartz-oligoclase gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Biotite-quartz-oligoclase gneiss - White- to light-gray-weathering, light- to medium-gray or greenish-gray, fine- to coarse-grained, massive to moderately well layered, foliated gneiss composed of oligoclase or andesine, quartz, biotite, and, locally, garnet. Commonly interlayered with amphibolite.

Lithology: gneiss; amphibolite

Decker Formation through Poxono Island Formation, undivided (Silurian) at surface, covers < 0.1 % of this area

Decker Formation through Poxono Island Formation, undivided -In descending order: Decker Formation--gray calcareous sandstone having lenses of calcareous conglomerate, siltstone, and shale, and lenses of limestone and dolomite (in Stroudsburg area, includes calcareous shale, limestone, and dolomite of Rondout Formation at top); Bossardville Limestone--gray argillaceous limestone and dolomitic limestone; Poxono Island Formation--thin-bedded dolomite, limestone, and shale; red shale in lower part. This undivided succession is equivalent to Keyser, Tonoloway, and Wills Creek (part) Formations of central Pennsylvania.

Lithology: dolostone (dolomite); limestone; siltstone; shale; sandstone; conglomerate

Quartz-Oligoclase Gneiss (Middle Proterozoic) at surface, covers 3 % of this area

Quartz-Oligoclase Gneiss - White-weathering, light-greenish-gray, medium- to coarse-grained, moderately layered to indistinctly foliated gneiss and lesser amounts of granofels composed of quartz, oligoclase or andesine, and, locally, biotite, hornblende and (or) clinopyroxene. Contains thin amphibolite layers.

Lithology: gneiss; granofels; amphibolite

Shawangunk Formation (Silurian) at surface, covers < 0.1 % of this area

Shawangunk Formation - Light- to dark-gray, fine- to very coarse grained sandstone and conglomerate containing thin shale interbeds. Includes four members, in descending order: Tammany--conglomerate and sandstone; Lizard Creek--sandstone and red or green shale; Minsi--sandstone and conglomerate; Weiders--conglomerate. Tammany and Lizard Creek Members together are approximately equivalent to Clinton Group to the west; Minsi and Weiders Members together are equivalent to Tuscarora Formation to the west.

Lithology: sandstone; conglomerate; shale

Potassic Feldspar Gneiss (Middle Proterozoic) at surface, covers 6 % of this area

Potassic Feldspar Gneiss - Light-gray- to pinkish-buff-weathering, pinkish-white to light-pinkish-gray, fine- to medium-grained, moderately foliated gneiss and lesser amounts of granofels composed of quartz, microcline, microcline microperthite and local accessory amounts of biotite, garnet, sillimanite, and opaque minerals.

Lithology: paragneiss; granofels

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

Microcline Gneiss - Light-gray- to pinkish-white-weathering, tan to pinkish-white, fine- to medium-grained, well-layered gneiss composed principally of quartz, microcline, and lesser amounts of oligoclase. Common accessory minerals include biotite, garnet, magnetite, and, locally, sillimanite.

Lithology: paragneiss