The Towaco Formation is a mapped bedrock unit in

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 ...

. It is named for the unincorporated village of Towaco, which is near the place 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 Towaco Formation is composed of reddish brown, reddish purple, gray, grayish-green, and white sandstone of varying grain thickness, as well as black siltstone and calcareous mudstone. Clastic/conglomerate beds are known to exist, including a 1-meter (~3 feet) thick

volcaniclastic Volcaniclastics are geologic materials composed of broken fragments (clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it ...

bed in the upper portion of the formation.Mineral Resources Online Spatial Data – Towaco Formation, New Jersey
U.S. Geological Survey. Accessed July 23, 2010.

Depositional environment

The Towaco Formation can be characterized as a continuation of the

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 city of ...

, which is mostly playa and

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

deposits resulting from the rifting of

Pangea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...

. The primarily red color of this formation is often evidence that the sediments were deposited in arid conditions.Faill, R.T., (2004). The Birdsboro Basin. ''Pennsylvania Geology'' V. 34 n. 4. However, the Towaco 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.Schlische, Roy W.
Geology of the Newark Rift Basin
Department of Geological Sciences, Rutgers University, Piscataway, NJ. Accessed July 23, 2010. One of the key differences between the Towaco Formation and earlier Triassic/Jurassic sedimentary formations of the Newark Basin is that it contains much longer cyclical deposition periods. Cycles in the Towaco Formation are represented by sequences of rock ten times thicker than sequences seen in the Lockatong and

Passaic 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 69,7 ...

formations. Additionally, compared to the underlying

Feltville Formation 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 ...

, the Towaco Formation contains a much more significant clastic component.

Fossil content

Fish fossil The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish ...

s, commonly those of the ray-finned ''

Semionotus ''Semionotus'' (from el, σημιον , 'mark' and el, νῶτος , 'back') is an extinct genus of ray-finned fish found throughout Northern Pangaea ( North America and Europe) during the late Triassic, becoming extinct in the Early Jurassic ...

'', can be found within the formation. In other layers, indeterminate fossil

ornithischian Ornithischia () is an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek s ...

tracks have been noted,Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607. along with additional reptile and dinosaur prints. Carbonized plant remains and impressions, as well as root structures and pollen, are present.

Coprolite A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name is de ...

can also be found within the formation.

Age

The Towaco Formation rests conformably above the Preakness Mountain Basalt and below the Hook Mountain Basalt, placing its deposition somewhere between approximately 198 and 197 million years ago during the early Jurassic stage known as the

Hettangian The Hettangian is the earliest age and lowest stage of the Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (My ...

References

In-line citations Additional references * Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. {{Geology of the Newark Basin Hettangian Stage Sandstone formations of the United States Siltstone formations Mudstone formations Ichnofossiliferous formations Geologic formations of New Jersey Paleontology in New Jersey

Description

Depositional environment

Fossil content

Age

See also

References