The Passaic Formation is a mapped bedrock unit in

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

, and

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

. It was previously known as the Brunswick Formation since it was first described in the vicinity of

New Brunswick, New Jersey New Brunswick is a city (New Jersey), city in and the county seat, seat of government of Middlesex County, New Jersey, Middlesex County, in the U.S. state of New Jersey.Passaic, New Jersey Passaic ( or ) is a city in Passaic County, in the U.S. state of New Jersey. As of the 2020 U.S. census, the city had a total population of 70,537, ranking as the 16th largest municipality in New Jersey and an increase of 656 from the 69,78 ...

, which is near where its type section was described by paleontologist

Paul E. Olsen Paul E. Olsen (born August 4, 1953) is an American paleontologist and author and co-author of a large number of technical papers. Growing up as a teenager in Livingston, New Jersey, he was instrumental in Riker Hill Fossil Site being named a Na ...

Description

The Passaic is defined as a reddish-brown

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...

and

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

with a few green and brown shale interbeds; red and dark-gray interbedded argillites near the base. In New Jersey, there are

conglomerate Conglomerate or conglomeration may refer to: * Conglomerate (company) * Conglomerate (geology) * Conglomerate (mathematics) In popular culture: * The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes ** Co ...

and

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

beds within the formation.

Depositional environment

The Passaic is mostly shallow lakes, playa, and alluvial fan deposits resulting from the rifting of Pangea. The red color is often evidence that the sediments were deposited in arid conditions.Faill, R.T., (2004). The Birdsboro Basin. ''Pennsylvania Geology'' V. 34 n. 4. The Passaic Formation overlies the

Lockatong Formation The Triassic Lockatong Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and New York. It is named after the Lockatong Creek in Hunterdon County, New Jersey. Description The Lockatong is defined as a light to dark gray, greenish-gra ...

deep lake sediment cycles, which were deposited during wetter climatic cycles during the Late Triassic. These sediments came from the northwest and contain clasts from Appalachian formations.

Fossils

*'' Clepsysaurus'' *''

Hypsognathus fenneri ''Hypsognathus'' (from el, ῠ̔́ψος , 'height' and el, γνάθος , 'jaw') is an extinct genus of procolophonid parareptile from the Late Triassic of New Jersey, Connecticut, and Nova Scotia.Sues, H.-D.,Olsen, P.E., Scott,D.M, and Spenc ...

Age

The Passaic is Late Triassic with an astronomically calibrated age of 219 to 201.7 million years ago (Ma) and is about 13,000 ft (~4 km) thick in the basin depocenter. It conformably overlies the

(darker, generally gray shales and mudrocks) and is overlain by the first Watching(Orange Mountain Formation) basalt. The Triassic/Jurassic boundary and correlated by pollen is located in the uppermost part of the formation, ~ 2 precessional cycles (~10-12 m) below the Orange Mountain Basalt. There are numerous

diabase Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-graine ...

intrusions into the Passaic with local

contact metamorphic Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

rocks.Berg, T.M., et al., (1983). Stratigraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geologic Survey, Harrisburg, Pennsylvania.

Description

Depositional environment

Fossils

Age

References

See also