Passaic Formation
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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 vacinity of New Brunswick, New Jersey. It is now named for the Passaic River in New Jersey.
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[edit] 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.[1] In New Jersey, there are conglomerate and sandstone beds within the formation.
[edit] 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.[2] Interfingered with the Passaic, the Lockatong Formation are lake sediments, which grew during wetter climatic cycles during the late Triassic.[2] These sediments came from the northwest and contain clasts from Appalachian formations.
[edit] Fossils
[edit] 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.[3]
[edit] Economic Uses
[edit] References
- ^ 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.
- ^ a b Faill, R.T., (2004). The Birdsboro Basin. Pennsylvania Geology V. 34 n. 4.
- ^ Berg, T.M., et al., (1983). Stratagraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geologic Survey, Harrisburg, Pennsylvania.
