View source for Earth:Towaco Formation

{{Infobox Rockunit
| name = Towaco Formation
| period = Early Jurassic
| age = Early Jurassic
| image = 3rdWatchungMountain_TowacoFormationCollage.jpg
| type = [[Earth:Geological formation|Geological formation]]
| prilithology = [[Earth:Sandstone|Sandstone]], [[Earth:Siltstone|siltstone]], mudstone
| otherlithology = [[Earth:Conglomerate (geology)|Conglomerate]]
| namedfor = Towaco, New Jersey<ref name="Olsen">Olsen, P.E., 1980.  The Latest Triassic and Early Jurassic Formations of the Newark Basin (Eastern North America, Newark Supergroup): Stratigraphy, Structure, and Correlation. ''New Jersey Academy of Science Bulletin'', v. 25, no. 2, p. 25-51.</ref>
| namedby = Paul E. Olsen, 1980<ref name=Olsen/>
| region = Newark Basin of<br> Eastern North America Rift Basins
| caption = Various colors and textures of Towaco Formation seen within Pines Lake area of Wayne, New Jersey. 
| unitof = [[Earth:Newark Supergroup|Newark Supergroup]]
| underlies = Hook Mountain Basalt
| overlies = Preakness Basalt
| thickness = maximum of at least {{convert|1,115|ft|m|-1}}<ref name=Olsen/>
| extent = nearly continuous for ~{{convert|35|mi|km}} in New Jersey
| coordinates = {{coord|40.8|N|74.3|W|display=inline,title}}
| paleocoordinates = {{coord|21.4|N|20.6|W|display=inline}}
| map            = {{Location map+ | United States#New Jersey
| relief = 1
| width   = 250
| float   = center
| places  =
  {{Location map~ | United States#New Jersey
  | lat_deg = 40.8
  | lon_deg = -74.3
  | mark = Blue pog.svg
  | marksize = 12
  }}
}}
| map_caption    =
}}

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.<ref name=Olsen/>

== 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 [[Earth:Pyroclastic rock|volcaniclastic]] bed in the upper portion of the formation.<ref name=Olsen/><ref name="USGS Towaco">[https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=NJJt;5 Mineral Resources Online Spatial Data – Towaco Formation, New Jersey].  U.S. Geological Survey.  Accessed July 23, 2010.</ref>

=== Depositional environment ===
The Towaco Formation can be characterized as a continuation of the [[Earth:Passaic Formation|Passaic Formation]], which is mostly [[Earth:Dry lake|playa]] and [[Earth:Alluvial fan|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.<ref name="multiple">Faill, R.T., (2004). The Birdsboro Basin. ''Pennsylvania Geology'' V. 34 n. 4.</ref>  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.<ref name="Rutgers Newark Basin Geology">Schlische, Roy W.  [http://geology.rutgers.edu/103web/Newarkbasin/NB_text.html Geology of the Newark Rift Basin].  Department of Geological Sciences, Rutgers University, Piscataway, NJ.  Accessed July 23, 2010.</ref>

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 [[Earth:Lockatong Formation|Lockatong]] and [[Earth:Passaic Formation|Passaic]] formations.<ref name=Olsen/>

Additionally, compared to the underlying [[Earth:Feltville Formation|Feltville Formation]], the Towaco Formation contains a much more significant clastic component.<ref name=Olsen/>

=== Fossil content ===
Fish fossils, commonly those of the ray-finned ''[[Biology:Semionotus|Semionotus]]'', can be found within the formation.<ref name=Olsen/>  In other layers, indeterminate fossil ornithischian tracks have been noted,<ref name="dinosaurdistribution">Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.</ref> 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.<ref name=Olsen/>

== 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.

== See also ==
* Geology of New Jersey
* List of dinosaur-bearing rock formations
** List of stratigraphic units with ornithischian tracks
*** Indeterminate ornithischian tracks

== References ==
'''In-line citations'''
{{Reflist}}
'''Additional references'''
* Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp.&nbsp;{{ISBN|0-520-24209-2}}


[[Category:Sandstone formations of the United States]]
[[Category:Siltstone formations]]
[[Category:Mudstone formations]]
[[Category:Ichnofossiliferous formations]]

{{Sourceattribution|Towaco Formation}}