Feltville Formation

Feltville Formation Stratigraphic range: Early Jurassic
Exposure of Feltville Formation sandstone beneath a ledge of Preakness Basalt on Preakness Mountain in New Jersey.
Type	Geological formation
Unit of	Newark Supergroup
Underlies	Preakness Basalt
Overlies	Orange Mountain Basalt
Thickness	maximum of 1,968 feet (600 m)
Lithology
Primary	Sandstone, Siltstone, Mudstone
Other	Limestone
Location
Region	Newark Basin of Eastern North America Rift Basins
Extent	continuous for ~40 miles (64 km) in New Jersey, with outliers present in New Jersey, New York & Pennsylvania.
Type section
Named for	Deserted Village of Feltville, New Jersey
Named by	Paul E. Olsen, 1980

The Feltville Formation is a mapped bedrock unit primarily in New Jersey, with one known outlier in Pennsylvania and another one in New York. It is named for the Deserted Village of Feltville in Watchung Reservation, New Jersey, which is near where its type section was described by paleontologist Paul E. Olsen.

The Feltville Formation is composed of red, gray, and white Sandstone of varying grain thickness, as well as red, gray, and black siltstone and calcareous mudstone. Sandstone/siltstone layers tend to be alternatingly massive and cross-bedded. Black to white carbonaceous limestone layers exist near the base of the formation. Additionally, pebbles and cobbles of quartz are embedded within layers of sandstone and siltstone that interfinger with the Feltville Formation near Oakland, New Jersey.

The Feltville Formation can be characterized as a continuation of the Passaic Formation, which is mostly playa and alluvial fan deposits resulting from the rifting of Pangea. The primarily red color of this formation is often evidence that the sediments were deposited in arid conditions. However, the Feltville Formation differs from the Passaic Formation in that it contains a more significant portion of non-red layers, which were laid down by deep lakes present during wetter periods.

Fish fossils, commonly those of the ray-finned Semionotus, can be found in limestone layers within the formation. In other layers, indeterminate fossil ornithischian tracks have been noted, along with additional reptile and dinosaur prints. Fossil plant remains, as well as root structures and pollen, are also found in the formation.

The Feltville Formation rests conformably above the Orange Mountain Basalt and below the Preakness Basalt, placing its deposition somewhere between approximately 199 and 196 million years ago during the early Jurassic stage known as the Hettangian.