The Passaic Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and New York.

It is now named for the city of Passaic, New Jersey, which is near where its type section was described by paleontologist Paul E.

The Passaic is mostly shallow lakes, playa, and alluvial fan deposits resulting from the rifting of Pangea.

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.

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.