Passaic Formation

The Passaic Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and New York. It was previously known as the Brunswick Formation since it was first described in the vicinity of New Brunswick, New Jersey. It is now named for the Passaic River in New Jersey.

Description

The Passaic is defined as a reddish-brown shale, siltstone and mudstone with a few green and brown shale interbeds; red and dark-gray interbedded argillites near the base. [Berg, T.M., Edmunds, W.E., Geyer, A.R. and others, compilers, (1980). Geologic Map of Pennsylvania: Pennsylvania Geologic Survey, Map 1, scale 1:250,000.] In New Jersey, there are conglomerate and sandstone beds within the formation.

=Depositional Environment=

The Passaic is mostly 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.] Interfingered with the Passaic, the Lockatong Formation are lake sediments, which grew during wetter climatic cycles during the late Triassic..] These sediments came from the northwest and contain clasts from Appalachian formations.

Fossils

Age

Relative age dating of the Passaic places it in the Late Triassic period to the early Jurassic, being deposited between 225 to 190 (±5) million years ago. It rests unconformably a top many different formations of the Appalachian Piedmont. It interfingers with the Lockatong Formation and also rests conformably atop the Stockton Formation. There are numerous diabase intrusions into the Passaic with local contact metamorphic rocks. [Berg, T.M., et al., (1983). Stratigraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geologic Survey, Harrisburg, Pennsylvania.]

Economic Uses

References

ee also

*Geology of Pennsylvania
*Geology of New Jersey