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

Geologic units in Bronx county, New York

Fordham Gneiss, undivided (Precambrian - Middle Proterozoic ) at surface, covers 18 % of this area

Fordham Gneiss, undivided - fe: garnet-biotite-quartz-plagioclase gneiss, and amphibolite; fd: sillimanite-garnet schistose gneiss, quartzite; fc: biotite- hornblende-quartz-plagioclase gneiss, quartz-feldspar lenses, amphibolite, biotite and/or hornblende-quartz-feldspar gneiss; fb: amphibolite, biotite and/or hornblende-garnet-quartz-plagioclase gneiss; fa: garnet-biotite-quartz-plagioclase gneiss, amphibolite, biotite-hornblende-quartz-plagioclase gneiss, quartz-feldspar granulite.

Lithology: gneiss; amphibolite; granulite; quartzite

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

Yonkers Gneiss - biotite and/or hornblende-quartz-feldspar gneiss.

Lithology: gneiss

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

Stockton Formation - Predominantly medium- to coarse-grained, light-gray, light-grayish-brown, or yellowish- to pinkish-gray arkosic sandstone and medium- to fine-grained, violet-gray to reddish-brown arkosic sandstone; with lesser, reddish to purplish-brown, silty mudstone, argillaceous siltstone, and shale. Some coarse-grained sandstone in lower part contains thick beds of conglomerate (Trsc) which have been mapped in the vicinity of Stockton. Sandstone, deposited in high-gradient stream channels, is mostly planar bedded with scoured bases containing pebble lags and mudstone rip-up clasts. Upper part of channel beds are burrowed. Large-scale trough crossbeds occur in some very coarse grained sandstone beds; smaller scale trough and climbing-ripple cross lamination occur in the upper part of channel sequences and in finer grained sandstone beds. Typical floodplain mudstones are irregularly thin bedded and extensively burrowed. Floodplain beds are thicker and more numerous in the central Newark basin, near the Delaware River. Thickness of the unit (including Trsc) near Stockton is about 1,240 m (4,068 ft).

Lithology: arkose; fine-grained mixed clastic; siltstone; shale

Manhattan Formation, undivided (Ordovician?) at surface, covers 33 % of this area

Manhattan Formation, undivided - pelitic schists, amphibolite; Units ?Omb, ?Omc, and ?Omd may be Cambrian eugeosynclinal rocks thrust upon Oma; ?Omd - sillimanite-garnet-muscovite-biotite-plagioclase-quartz gneiss; ?Omc - sillimanite-garnet-muscovite-biotite-quartz-plagioclase schistose gneiss, sillimanite nodules, local quartz-rich layers; ?Omb - discontinous unit of amphibolite and ?Omc-type schist.

Lithology: pelitic schist; gneiss; amphibolite

Hartland Formation (Ordovician?) at surface, covers 24 % of this area

Hartland Formation - basal amphibolite overlain by pelitic schists.

Lithology: amphibolite; pelitic schist

Inwood Marble (Early Cambrian - Lower Ordovician) at surface, covers 13 % of this area

Inwood Marble - dolomite marble, calc-schist, granulite, and quartzite, overlain by calcite marble; grades into underlying patchy Lowerre Quartzite of Early Cambrian age.

Lithology: marble; schist; granulite; quartzite