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Geologic units in Rockland county, New York

Brunswick Formation (Upper Triassic) at surface, covers 26 % of this area

Sandstone and conglomerate.

Hornblende granite and granite gneiss (Middle Proterozoic) at surface, covers 19 % of this area

With subordinate leucogranite.

Brunswick Formation (Upper Triassic) at surface, covers 13 % of this area

Mudstone, sandstone and arkose.

Hammer Creek Formation (Upper Triassic) at surface, covers 11 % of this area

Conglomerate.

Interlayered amphibolite and hornblende granitic gneiss (Middle Proterozoic) at surface, covers 8 % of this area

Interlayered amphibolite and hornblende granitic gneiss.

Palisade Diabase (Early Jurassic) at surface, covers 7 % of this area

Palisade Diabase

Brunswick Formation (Upper Triassic) at surface, covers 5 % of this area

Sandstone, siltstone and mudstone.

Quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 5 % of this area

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

Rusty and gray biotite-quartz-feldspar gneiss (Middle Proterozoic) at surface, covers 2 % of this area

Rusty facies contains variable amounts of garnet, sillimanite, cordierite, graphite, sulfides; minor marble and calcsilicate rock.

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

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

Biotite-quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 0.9 % of this area

With subordinate biotite granitic gneiss, amphibolite, calcsilicate rock.

Manhattan Formation (A Member) (Middle Ordovician) at surface, covers 0.6 % of this area

Sillimanite-garnet-muscovite-biotite-quartz- plagioclase schists; calcite marble and calcsilicate rock at base.

Garnet-biotite-quartz-feldspar gneiss (Middle Proterozoic) at surface, covers 0.5 % of this area

Quartzite, quartz-feldspar gneiss, calcsilicate rock.

Ladentown diabase and basaltic lava (Upper Triassic) at surface, covers 0.5 % of this area

Ladentown diabase and basaltic lava

Balmville Limestone (Middle Ordovician) at surface, covers 0.4 % of this area

Balmville Limestone

Diorite with hornblende and/or biotite (Upper Ordovician) at surface, covers 0.3 % of this area

Diorite with hornblende and/or biotite.

Garnet-bearing gneiss and interlayered quartzite (Middle Proterozoic) at surface, covers < 0.1 % of this area

Contains varying amounts of biotite, garnet, sillimanite; minor marble, amphibolite, rusty paragneiss.

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

(includes local Dalton Formation at base)-locally conglomeratic.

Olivine pyroxenite (Upper Ordovician) at surface, covers < 0.1 % of this area

In part with poikilitic hornblende; local peridotite.

Hornblendite (Upper Ordovician) at surface, covers < 0.1 % of this area

Hornblendite

Stockton Formation (Upper Triassic) at surface, covers < 0.1 % of this area

(Kmmel, 1897) - Light-gray, light-grayishbrown, yellowish- to pinkish-gray, or violet-gray to reddish-brown, medium- to coarse-grained arkosic sandstone and reddish- to purplish-brown mudstone, silty mudstone, argillaceous siltstone, and shale. Mudstone, siltstone and shale beds thicker and more numerous in central Newark basin west of Round Valley Reservoir. Sandstones mostly planar-bedded, with scoured bases containing pebble lags and mudstone rip-ups. Unit is coarser near Newark basin border fault, where poorly exposed, reddish-brown to pinkish-white, medium- to coarse-grained, feldspathic pebbly sandstone and conglomerate (Trss) and pebble to cobble quartzite conglomerate (Trscq). Maximum thickness of formation about 1,240 m (4,070 ft).

Passaic Formation Sandstone and Siltstone facies (Lower Jurassic and Upper Triassic) at surface, covers < 0.1 % 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).

Passaic Formation Conglomerate and Sandstone facies (Lower Jurassic and Upper Triassic) at surface, covers < 0.1 % 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).