# Boonton Formation

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{{Short description|Lithostratigraphic unit}}
{{Infobox Rockunit
| name = Boonton Formation
| age = [Late Hettangian](/source/Hettangian)-[Sinemurian](/source/Sinemurian)<br>~{{fossil range|197|190}}
| period = Sinemurian
| image = NewarkBasin_BoontonFormation.jpg
| type = [Geological formation](/source/Geological_formation)
| prilithology = [Sandstone](/source/Sandstone), [siltstone](/source/siltstone), [mudstone](/source/mudstone)
| otherlithology = [Conglomerate](/source/Conglomerate_(geology)), [evaporite](/source/evaporite)
| namedfor = [Boonton, New Jersey](/source/Boonton%2C_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](/source/Paul_E._Olsen)<ref name=Olsen/>
| year_ts = 1980
| region = [Newark Basin](/source/Newark_Basin) of<br> [Eastern North America Rift Basins](/source/Eastern_North_America_Rift_Basins)
| caption = Exposure of the Boonton Formation along a road cut in [Pequannock Township, New Jersey](/source/Pequannock_Township%2C_New_Jersey).
| unitof = [Newark Supergroup](/source/Newark_Supergroup)<br>&nbsp;[Meriden Group](/source/Meriden_Group)
| underlies = [Potomac Formation](/source/Potomac_Formation)
| overlies = Hook Mountain Basalt
| thickness = maximum of over {{convert|1,640|ft|m|-1}}<ref name=Olsen/>
| extent = continuous for ~{{convert|30|mi|km}} in [New Jersey](/source/New_Jersey)
| coordinates = {{coord|40.9|N|74.4|W|display=inline,title}}
| paleocoordinates = {{coord|22.7|N|19.8|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 = 40.9
  | lon_deg = -74.4
  | mark = Blue pog.svg
  | marksize = 12
  }}
}}
}}

The '''Boonton Formation''' is a mapped bedrock unit in [New Jersey](/source/New_Jersey), formerly divided between the Boonton and Whitehall beds of the defunct Brunswick Formation.  It is named for the town of [Boonton, New Jersey](/source/Boonton%2C_New_Jersey), which is near where its type section was described by paleontologist [Paul E. Olsen](/source/Paul_E._Olsen).<ref name=Olsen/>

== Description ==
The Boonton Formation is composed of reddish-brown to reddish-purple fine grained sandstone, as well as red, gray, purple, and black siltstone and mudstone.  Siltstone and mudstone layers can be calcareous and feature dolomitic concretions.  A well known fossil fish bed is known to exist in a carbonate rich siltstone near the top of the formation.  Additionally, cross-bedded conglomerate layers interfinger with beds of the formation, usually bearing clasts of gneiss and granite.<ref name=Olsen/><ref name="USGS Boonton">[https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=NJJb;5 Mineral Resources Online Spatial Data – Boonton Formation, New Jersey].  U.S. Geological Survey.  Accessed July 23, 2010.</ref>

=== Depositional environment ===
The Boonton Formation can be characterized as the uppermost continuation of the [Passaic Formation](/source/Passaic_Formation), which is mostly [playa](/source/Dry_lake) and [alluvial fan](/source/alluvial_fan) deposits resulting from the rifting of [Pangea](/source/Pangea).  However, unlike the Passaic Formation, which is primarily red in color due to arid conditions at the time of deposition,<ref name="multiple">Faill, R.T., (2004). The Birdsboro Basin. ''Pennsylvania Geology'' V. 34 n. 4.</ref> the Boonton Formation contains a much more significant portion of non-red layers, indicative of lakes present during wetter periods.<ref name="Rutgers Newark Basin Geology">Schlische, Roy W.  [https://web.archive.org/web/20110603070142/https://geology.rutgers.edu/103web/Newarkbasin/NB_text.html Geology of the Newark Rift Basin].  Department of Geological Sciences, Rutgers University, Piscataway, NJ.  Accessed June 3, 2011.</ref>   
 
A chief difference between the Boonton Formation and all other formations of the Newark Basin is that the lower part of the formation lacks a cyclic deposition pattern.  Typically, the sedimentary formations of the Newark Basin feature recurring periods of wet and dry deposition, resulting in a series of alternating red and gray-black beds.  However, the lower beds of the Boonton Formation show a wide variety of color and texture arranged in no particular order.<ref name=Olsen/>

=== Fossils ===
Fish fossils, including the ray-finned [''Semiontus elegans''](/source/Semionotus), the [coelacanth](/source/coelacanth) [''Diplurus longicaudatus''](/source/Diplurus), and others, such as ''[Redfieldius](/source/Redfieldius)'' and ''[Ptycholepis](/source/Ptycholepis)'', can be found in the uppermost parts of the formation.<ref name=Olsen/>  In other layers, indeterminate fossil [ornithischian](/source/ornithischian) tracks have been noted<ref name="dinosaurdistribution">Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.</ref> (''[Anomoepus](/source/Anomoepus)'' is reported), along with additional reptile and dinosaur prints, such as those of ''Batrachopus'', and the [theropod](/source/theropod) ''[Grallator](/source/Grallator)''.  Fossil conifer remains, as well as other plant related fossils such as root structures and pollen, are also found in the formation.<ref name=Olsen/>

== Age ==
The Boonton Formation rests conformably above the Hook Mountain Basalt, placing its deposition sometime between approximately 197 and 190 million years ago during the late [Hettangian](/source/Hettangian) stage and [Sinemurian](/source/Sinemurian) stage of the Jurassic.

== See also ==
* [Geology of New Jersey](/source/Geology_of_New_Jersey)
* [List of dinosaur-bearing rock formations](/source/List_of_dinosaur-bearing_rock_formations)
** [List of stratigraphic units with ornithischian tracks](/source/List_of_stratigraphic_units_with_ornithischian_tracks)
*** [Indeterminate ornithischian tracks](/source/List_of_stratigraphic_units_with_ornithischian_tracks)

== References ==
{{Reflist}}

=== Bibliography ===
* 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}}.

{{Geology of the Newark Basin}}

Category:Geologic formations of New Jersey
Category:Jurassic geology of New Jersey
Category:Hettangian Stage
Category:Sinemurian Stage
Category:Sandstone formations of the United States
Category:Siltstone formations of the United States
Category:Mudstone formations of the United States
Category:Ichnofossiliferous formations
Category:Fossiliferous stratigraphic units of North America
Category:Paleontology in New Jersey
Category:Conglomerate formations of the United States

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Adapted from the Wikipedia article [Boonton Formation](https://en.wikipedia.org/wiki/Boonton_Formation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Boonton_Formation?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.