Geologic units in Passaic county, New Jersey

Quartz-Oligoclase Gneiss (Middle Proterozoic) at surface, covers 12 % of this area

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.

Hornblende Granite (Middle Proterozoic) at surface, covers 9 % of this area

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).

Diorite (Middle Proterozoic) at surface, covers 9 % of this area

Gray- to tan-weathering, greenish-gray to brownish-gray, medium- to coarse-grained, greasy-lustered, massive diorite containing andesine or oligoclase, clinopyroxene, hornblende, hypersthene, and sparse amounts of biotite and magnetite. Amphibolite layers common.

Preakness Basalt (Lower Jurassic) at surface, covers 7 % of this area

(Olsen, 1980) - Dark-greenish-gray to black, very-fine-grained, dense, hard basalt composed mostly of intergrown calcic plagioclase (An55-60) and clinopyroxene (pigeonite and augite). Crystals are generally less than 1 mm (0.04 in) long, but locally feldspar crystals are larger than 1.3 cm (0.5 in.). Small spherical to tubular cavities (gas-escape vesicles) may be filled by zeolite minerals or calcite. Consists of at least three major flows. Prominent amydaloidal zones occur at most contacts between flows. A thin, 2 to 8 m (6.6-26 ft) bed of siltstone (Jps) separates the lower flows. The basal 20 m (66 ft) of the lowest flow is commonly highly vesicular or brecciated. Radiating slender columns 20 to 71 cm (8-28 in) wide, caused by shrinkage while cooling, are most abundant in the highest flow. The small, circiular extrusive body forming Round Top west of Oldwick is identified as Preakness Basalt by geochemistry and position above the Orange Mountain Basalt (Houghton and others, 1992). Thickness ranges from 250 m (820ft) (Olsen and others, 1989) to 320 m (1,050 ft).

Passaic Formation Conglomerate and Sandstone facies (Lower Jurassic and Upper Triassic) at surface, covers 6 % of this area

Conglomeratic sandstone (JTrpsc) is brownish-red pebble conglomerate, medium- to coarse-grained, feldspathic sandstone and micaceous siltstone; unit is planar to low-angle trough cross laminated, burrowed, and contains local pebble layers. Unit forms upward-fining sequences 0.5 to 2.5 m (1.6-8 ft) thick. Conglomeratic sandstone thickness exceeds 800 m (2,625 ft).

Passaic Formation Sandstone and Siltstone facies (Lower Jurassic and Upper Triassic) at surface, covers 5 % of this area

Sandstone (JTrps) is interbedded grayish-red to brownish-red, medium- to fine-grained, medium- to thick-bedded sandstone and brownish-to-purplish-red coarse-grained siltstone; unit is planar to ripple cross-laminated, fissile, locally calcareous, containing desiccation cracks and root casts. Upward-fining cycles are 1.8 to 4.6 m (6-15 ft) thick. Sandstone beds are coarser and thicker near conglomerate units (JTrpcq, JTrpcl). Maximum thickness about 1,100 m (3,610 ft).

Skunnemunk Conglomerate (Middle Devonian) at surface, covers 5 % of this area

(Darton, 1894) - Grayish-purple to grayish-red, thin- to very thick bedded, locally cross-bedded, polymictic conglomerate and sandstone containing clasts of white vein quartz, red and green quartzite and sandstone, red and gray chert, and red shale; interbedded with medium-gray, thin-bedded sandstone and greenish-gray and grayish-red, mud-cracked shale. Conglomerate and sandstone matrix is primarily hematite and microcrystalline quartz. Conglomerate cobbles range to 16.5 cm (6.5 in) long, and average cobble size increases in upper part of unit. Lower contact conformable and gradational as defined by Kummel and Weller (1902). About 915 m (3,000 ft) thick.

Hypersthene-Quartz-Oligoclase Gneiss (Middle Proterozoic) at surface, covers 5 % of this area

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.

Bellvale Sandstone (Middle Devonian) at surface, covers 5 % of this area

(Bellvale Flags of Darton, 1894; Willard, 1937) - Upper beds are grayish-red to grayish-purple sandstone containing quartz pebbles as large as 3 cm (1.2 in) in diameter. Lower beds are light-olive-gray- to yellowish-gray- and greenish-black-weathering, medium-gray to medium-bluish-gray very thin to very thick bedded siltstone and sandstone cross-bedded, graded and interbedded with black to dark-gray shale that is locally fossiliferous. More sandstone in upper beds becomes finer downward. Lower contact conformable and placed where beds thicken and volume of shale and siltstone are about equal. The unit is 535 to 610 m (1,750-2,000 ft) thick.

Towaco Formation (Lower Jurassic) at surface, covers 5 % of this area

(Olsen, 1980) - Reddish-brown to brownish-purple, fine- to medium-grained micaceous sandstone, siltstone, and silty mudstone in upward-fining sequences 1 to 3 m (3-10 ft) thick. Distributed throughout formation are eight or more sequences of gray to greenish- or brownish-gray, fine-grained sandstone, siltstone and calcareous siltstone and black, microlaminated calcareous siltstone and mudstone containing diagnostic pollen, fish and dinosaur tracks. Sandstone is commonly trough cross laminated; siltstone is commonly planar laminated or bioturbated, but can be indistinctly laminated to massive. Thermally metamorphosed into hornfels where in contact with Hook Mountain Basalt. Conglomerate and conglomeratic sandstone with subrounded quartzite and quartz clasts in matrix of light-red sand to brownish-red silt (Jtc) interfingers with rocks of the Towaco Formation north and west of New Vernon. Maximum thickness is about 380 m (1,250 ft).

Pyroxene Gneiss (Middle Proterozoic) at surface, covers 4 % of this area

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.

Biotite-quartz-oligoclase gneiss (Middle Proterozoic) at surface, covers 4 % of this area

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.

Orange Mountain Basalt (Lower Jurassic) at surface, covers 4 % of this area

(Olsen, 1980) - Dark-greenish-gray to greenish-black basalt composed mostly of calcic plagioclase (typically An65) and clinopyroxene (augite and pigeonite); crystals are generally less than 1 mm (0.04 in) long. Consists of three major flows. The flows are separated in places by a weathered zone or by a thin, up to 3-m- (10-ft-) thick bed of red siltstone (not shown on map) or volcaniclastic rock. Lowest flow is generally massive and has widely spaced curvilinear joints; columnar joints in lowest flow become more common toward the northeast. Middle flow is massive or has columnar jointing. Lower part of the uppermost flow has pillow structures; upper part has pahoehoe flow structures. Tops and bottoms of flow layers are vesicular. Maximum thickness is about 182 m (597 ft).

Boonton Formation (Lower Jurassic) at surface, covers 3 % of this area

(Olsen, 1980) - Reddish-brown to brownish-purple, fine-grained sandstone, siltstone, and mudstone; sandstone commonly micaceous, interbedded with siltstone and mudstone in fining-upward sequences mostly 1.5 to 4 m (5-13 ft) thick. Red, gray and brownish-purple siltstone and black, blocky, partly dolomitic siltstone and shale common in lower part. Irregular mudcracks, symmetrical ripple marks, and burrows, as well as gypsum, glauberite, and halite pseudomorphs are abundant in red mudstone and siltstone. Gray, fine-grained sandstone may have carbonized plant remains and reptile footprints in middle and upper parts of unit. Near Morristown, beds of quartz-pebble conglomerate (unit Jbcq) as much as 0.5 m (1.6 ft) thick interfinger with beds of sandstone, siltstone, and shale. Northeast of Boonton, beds of quartz-pebble conglomerate (not mapped separately as Jbcq) occur locally with conglomerate containing abundant clasts of gneiss and granite in matrix of reddish-brown sandstone and siltstone. Maximum thickness is about 500 m (1,640 ft).

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

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.

Cornwall Shale (Middle Devonian) at surface, covers 2 % of this area

(Hartnagel, 1907) - Black to dark-gray, very-thin- to thickbedded, fissile shale, fossiliferous, interbedded with medium-gray and light-olive-gray to yellowish-gray, laminated to very-thin-bedded siltstone, that increases in upper part of unit. Lower contact probably conformable. About 290 m (950 ft) thick.

Feltville Formation (Lower Jurassic) at surface, covers 2 % of this area

(Olsen, 1980) - Interbedded brownish-red to light-grayish-red, fine- to coarse-grained sandstone, gray and black, coarse siltstone in upward-fining cycles, and silty mudstone. Fine-grained sandstone and siltstone are moderately well sorted, commonly cross-laminated, and have 15 percent or more feldspar; interbedded with brownish-red, indistinctly laminated, bioturbated calcareous mudstone. Thermally metamorphosed into hornfels where in contact with Preakness Basalt. Near the base are two thin, laterally continuous beds of black, carbonaceous limestone and gray, calcareous siltstone, each up to 3 m (10 ft) thick. These contain abundant fish, reptile, anthropod, and diagnostic plant fossils. Three or four, thin, gray to black siltstone and mudstone sequences occur in upper part of unit. Near Oakland, subrounded pebbles to cobbles of quartzite and quartz in a red siltstone and sandstone matrix (Jfc) interfinger with sandstone and siltstone of the Feltville Formation. Maximum thickness about 155 m (510 ft).

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

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.

Hook Mt. Basalt (Lower Jurassic) at surface, covers 2 % of this area

(Olsen, 1980) - Light- to dark-greenish-gray, medium- to coarse-grained, amygdaloidal basalt composed of plagioclase (typically An65 and commonly porphyritic), clinopyroxene (augite and pigeonite), and iron-titanium oxides such as magnetite and ilmenite. Locally contains small spherical to tubular cavities (gas-escape vesicles), some filled by zeolite minerals or calcite. Consists of two major flows. Base of lowest flow is intensely vesicular. Tops of flows are weathered and vesicular. Maximum thickness is about 110 m (360 ft) (Olsen and others, 1989).

Green Pond Conglomerate (Lower (?) and Middle Silurian) at surface, covers 1 % of this area

(Rogers, 1836) - Medium- to coarse-grained quartz-pebble conglomerate, quartzitic arkose and orthoquartzite, and thin- to thick-bedded reddish-brown siltstone. Grades downward into gray, very dark-red, or grayish-purple, medium- to coarse-grained, thin- to very thick bedded pebble to cobble conglomerate containing clasts of red shale, siltstone, and chert; yellowish-gray sandstone and chert; dark-gray shale and chert; and white-gray and pink milky quartz. Quartz cobbles are as long as 10 cm (4 in.), and rare red shale clasts as much as 46 cm (18 in.) across. Milky quartz pebbles average 2.5 cm (1 in.) in length. Red arkosic quartz-pebble conglomerate and quartzite are more abundant than gray and grayish-green quartzite. Unconformably overlies Martinsburg Formation, Allentown Dolomite, Leithsville Formation, or Proterozoic rocks. About 305 m (1000 ft) thick.

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

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.

Passaic Formation Quatzite-clast Conglomerate facies (Lower Jurassic and Upper Triassic) at surface, covers 1.0 % of this area

Quartzite conglomerate unit (JTrpcq) is reddish-brown pebble conglomerate, pebbly sandstone, and sandstone, in upward-fining sequences 1 to 2 m (3-6 ft) thick. Clasts are subangular to subrounded, quartz and quartzite in sandstone matrix. Sandstone is medium to coarse grained, feldspathic (up to 20 percent feldspar), and locally contains pebble and cobble layers. Conglomerate thickness exceeds 850 m (2,790 ft).

Kanouse and Esopus Formations and Connelly Conglomerate, undivided (Lower Devonian) at surface, covers 0.8 % of this area

Kanouse Sandstone (Kmmel, 1908) - Medium-gray, light-brown, and grayish-red, fine- to coarse-grained, thin- to thick-bedded sparsely fossiliferous sandstone and pebble conglomerate. Basal conglomerate beds are interbedded with siltstone similar to the upper part of the Esopus Formation and contain well-sorted, subangular to subrounded, gray and white quartz pebbles less than 1 cm (0.4 in.) long. Lower contact gradational. About 14 m (46 ft) thick. Esopus Formation - (Vanuxem, 1842; Boucot, 1959) - Light- to dark-gray, laminated to thin-bedded siltstone interbedded with dark-gray to black mudstone, dusky-blue sandstone and siltstone, and yellowish-gray fossiliferous siltstone and sandstone. Lower contact probably conformable with the Connelly Conglomerate. The formation is about 100 m (330 ft) thick at Greenwood Lake and estimated at 55 m (180 ft) thick in Longwood Valley. Connelly Conglomerate (Chadwick, 1908) - Grayish-orange weathering, very light gray to yellowish-gray, thin-bedded quartz-pebble conglomerate. Quartz pebbles average 1 to 2 cm (0.4-0.8 in.), are subrounded to well rounded, and well sorted. The unit unconformably overlies the Berkshire Valley Formation. About 11 m (36 ft) thick.

Pyroxene Granite (Middle Proterozoic) at surface, covers 0.7 % of this area

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.

Potassic Feldspar Gneiss (Middle Proterozoic) at surface, covers 0.5 % of this area

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.

Berkshire Valley and Poxono Island Formations, undivided (Upper Silurian) at surface, covers 0.4 % of this area

Thickness ranges from 76 m (250 ft) at Greenwood Lake to 122 m (400 ft) in Longwood Valley. Berkshire Valley Formation (Barnett, 1970) - Commonly yellowish-gray weathering, medium-gray to pinkish-gray, very thin to thin-bedded fossiliferous limestone interbedded with gray to greenish-gray calcareous siltstone and silty dolomite, medium-gray to light-gray dolomite conglomerate, and grayish-black, thinly laminated shale. Lower contact conformable. Thickness ranges from 27 to 38 m (90-125 ft) thick. Poxono Island Formation, (White, 1882; Barnett, 1970) - Very thin to medium-bedded sequence of medium-gray, greenish-gray, or yellowish-gray, mud-cracked dolomite; light-green, pitted, medium-grained calcareous sandstone, siltstone, and edgewise conglomerate containing gray dolomite; and quartz-pebble conglomerate containing angular to subangular pebbles as much as 2 cm (0.8 in.) long. Interbedded grayish-green shales at lower contact are transitional into underlying Longwood Shale. Thickness ranges from 49 to 84 m (160-275 ft) thick.

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

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.

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

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.

Microperthite Alaskite (Middle Proterozoic) at surface, covers 0.1 % of this area

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.

Longwood Shale (Middle (?) and Upper Silurian) at surface, covers < 0.1 % of this area

(Darton, 1894) - Dark-reddish-brown, thin- to very thick bedded shale interbedded with cross-bedded, very dark red, very thin to thin-bedded sandstone and siltstone. Lower contact conformable. About 100 m (330 ft) thick.

Hardyston Quartzite (Lower Cambrian) at surface, covers < 0.1 % of this area

(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.

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

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).

Bushkill Member (Middle Ordovician) at surface, covers < 0.1 % of this area

(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.

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

Light-gray, medium-grained, massive- to well-layered, vitreous, partly feldspathic quartzite having sparse flakes of graphite. Associated with potassium-feldspar gneiss (Yk), biotite-quartz-feldspar gneiss (Yb), pyroxene gneiss (Yp), Franklin Marble (Yf), and pyroxene-epidote gneiss (Ype).

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

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.

Quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

May contain pyroxenes, hornblende, biotite; locally interlayered with amphibolite; subordinate biotite mesoperthite gneiss.

Albite-Oligoclase Granite (Middle Proterozoic) at surface, covers < 0.1 % of this area

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.

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

Pyroxenic amphibolite, hornblende gneiss, commonly biotitic, garnetiferous; subordinate calcsilicate rock.

Hornblende granite and granite gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

With subordinate leucogranite.