Towaco Formation
Encyclopedia
The Towaco Formation is a mapped bedrock unit in New Jersey
. It is named for the unincorporated village of Towaco
, which is near the place its type section was described by paleontologist Paul E. Olsen
.
bed in the upper portion of the 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 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.
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
formations.
Additionally, compared to the underlying Feltville Formation
, the Towaco Formation contains a much more significant clastic component.
, can be found within the formation. In other layers, indeterminate fossil ornithischian tracks have been noted , along with additional reptile and dinosaur prints. Carbonized plant remains and impressions, as well as root structures and pollen, are present. Coprolite
can also be found within the formation.
.
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
. It is named for the unincorporated village of Towaco
Towaco, New Jersey
Towaco is an unincorporated area within Montville Township in Morris County, New Jersey, United States. The area is served as United States Postal Service ZIP code 07082...
, which is near the place its type section was described by paleontologist Paul E. Olsen
Paul E. Olsen
Paul E. Olsen 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 National Natural Landmark as a teenager by sending President Richard Nixon a...
.
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. Clasitc/conglomerate beds are known to exist, including a 1 meter (~3 feet) thick volcaniclasticPyroclastic rock
Pyroclastic rocks or pyroclastics are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic...
bed in the upper portion of the formation.
Depositional environment
The Towaco Formation can be characterized as a continuation of the Passaic FormationPassaic 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 Passaic, New Jersey, which is near where its type...
, which is mostly playa
Dry lake
Dry lakes are ephemeral lakebeds, or a remnant of an endorheic lake. Such flats consist of fine-grained sediments infused with alkali salts. Dry lakes are also referred to as alkali flats, sabkhas, playas or mud flats...
and alluvial fan
Alluvial fan
An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...
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 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.
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
Lockatong Formation
The Triassic Lockatong Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and New York. It is named after the Lockatong Creek in Hunterdon County, New Jersey.-Description:...
and Passaic
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 Passaic, New Jersey, which is near where its type...
formations.
Additionally, compared to the underlying Feltville Formation
Feltville Formation
The Feltville Formation is a mapped bedrock unit primarily in New Jersey, with one known outlier in Pennsylvania. 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...
, the Towaco Formation contains a much more significant clastic component.
Fossils
Fish fossils, commonly those of the ray-finned SemiontusSemionotus
Semionotus is an extinct genus of ray-finned fish found throughout Northern Pangaea during the late Triassic, becoming extinct at the start of the Jurassic.-External links:...
, can be found within the formation. In other layers, indeterminate fossil ornithischian tracks have been noted , along with additional reptile and dinosaur prints. Carbonized plant remains and impressions, as well as root structures and pollen, are present. Coprolite
Coprolite
A coprolite is fossilized animal dung. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour rather than morphology. The name is derived from the Greek words κοπρος / kopros meaning 'dung' and λιθος / lithos meaning 'stone'. They...
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 HettangianHettangian
The Hettangian is the earliest age or lowest stage of the Jurassic period of the geologic timescale. It spans the time between 199.6 ± 0.6 Ma and 196.5 ± 1 Ma . The Hettangian follows the Rhaetian and is followed by the Sinemurian.In Europe stratigraphy the Hettangian is a part of the time span in...
.
See also
- Geology of New JerseyGeology of New JerseyThe Geology of New Jersey consists of four distinct physiographic provinces. They are: the Atlantic Coastal Plain Province, the Piedmont Province, the Highlands Province, and the Ridge and Valley Province.-Coastal Plain:...
- List of dinosaur-bearing rock formations
- List of stratigraphic units with ornithischian tracks
- Indeterminate ornithischian tracks
- List of stratigraphic units with ornithischian tracks