# Chagres Formation

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{{Short description|Geologic formation in Panama}}
{{Infobox rockunit
| name           = Chagres Formation
| image          =
| caption        =
| type           = [Formation](/source/Formation_(stratigraphy))
| age            = [Tortonian](/source/Tortonian)-[Messinian](/source/Messinian)<br />([Clarendonian](/source/Clarendonian)-[Hemphillian](/source/Hemphillian))<br />~{{fossil range|11.6|5.3}}
| period         = Messinian
| prilithology   = [Sandstone](/source/Sandstone)
| otherlithology = [Siltstone](/source/Siltstone)
| namedfor       = [Chagres River](/source/Chagres_River)
| namedby        = MacDonald
| year_ts        = 1919
| region         = [Colón Province](/source/Col%C3%B3n_Province)
| country        = [Panama](/source/Panama)
| coordinates    = {{coord|9.2|N|80.3|W|display=inline,title}}
| paleocoordinates = {{coord|9.0|N|79.4|W|display=inline}}
| unitof         =
| subunits       = Río Indio & Toro Limestone Members
| underlies      = ''[alluvium](/source/alluvium)''
| overlies       = [Gatún Formation](/source/Gat%C3%BAn_Formation)
| thickness      = ''uncertain''
| extent         = [Panama Basin](/source/Panama_Basin)
| area           =
| map            = {{Location map+ | Panama
| relief = 1
| width   = 250
| float   = center
| places  =
  {{Location map~ | Panama
  | lat_deg = 9.2
  | lon_deg = -80.3
  | mark = Yellow pog.svg
  | marksize = 12
  }}
}}
| map_caption    =
}}

The '''Chagres Formation''' (Tc)<ref name=GeoMap1980>Geologic Map, 1980</ref> is a [geologic formation](/source/Formation_(geology)) in the [Colón Province](/source/Col%C3%B3n_Province) of central [Panama](/source/Panama). The [sandstone](/source/sandstone)s and [siltstone](/source/siltstone)s were deposited in a shallow marine [environment](/source/depositional_environment) and preserve [fossils](/source/fossils) dating back to the [Middle to Late Miocene](/source/Miocene) ([Tortonian](/source/Tortonian) to [Messinian](/source/Messinian), [Clarendonian](/source/Clarendonian) to [Hemphillian](/source/Hemphillian) in the [NALMA classification](/source/North_American_land_mammal_age)) [period](/source/Period_(geology)).

== Description ==
The Chagres Formation is exposed in the northern part of the [Panama Canal Zone](/source/Panama_Canal_Zone). The formation overlies and partly overlaps the [Gatún Formation](/source/Gat%C3%BAn_Formation). The outcrop area lies entirely west of the [Panama Canal](/source/Panama_Canal), extending from the Canal Zone southwestward along the Caribbean coast, about {{convert|45|km|mi}} southwest of [Colón](/source/Col%C3%B3n%2C_Panama). Calcareous strata at the base of the formation throughout most of the outcrop area in the Canal Zone constitute the Toro limestone member.<ref name=Woodring1957_p47>Woodring, 1957, p.47</ref>

The name Chagres Sandstone was proposed by MacDonald in 1919 for the sandstone forming the hills that overlook the coast from Toro Point to the mouth of the [Chagres River](/source/Chagres_River). The sandstone is so massive that estimates of thickness are uncertain.<ref name=Woodring1957_p47/>

== Fossil content ==
Various fossils have been found in the Chagres Formation:<ref name=FWPina>[https://paleobiodb.org/classic/displayCollResults?collection_no=160781 Pina] at [Fossilworks](/source/Fossilworks).org</ref>

=== Fish ===
{{div col|colwidth=18em}}
* ''[Alopias superciliosus](/source/Alopias_superciliosus)''
* ''[Benthosema pluridens](/source/Benthosema_pluridens)''<ref name=Schwarzhans2013>Schwarzhans & Aguilera, 2013</ref>
* ''[Carcharhinus brachyurus](/source/Carcharhinus_brachyurus)''
* ''[Carcharhinus cionei](/source/Carcharhinus_cionei)''
* ''[Carcharhinus obscurus](/source/Carcharhinus_obscurus)''
* ''[Carcharhinus plumbeus](/source/Carcharhinus_plumbeus)''
* ''[Carcharhinus signatus](/source/Carcharhinus_signatus)''
* ''[Carcharodon plicatilis](/source/Carcharodon_plicatilis)''
* ''[Centrophorus granulosus](/source/Centrophorus_granulosus)''
* ''[Cynoscion prolixus](/source/Cynoscion_prolixus)''<ref name=Aguilera2016>Aguilera et al., 2016</ref>
* ''[Dalatias licha](/source/Dalatias_licha)''
* ''[Diaphus barrigonensis](/source/Diaphus_barrigonensis)'', ''[D. rodriguezi](/source/Diaphus_rodriguezi)''<ref name=Schwarzhans2013/>
* ''[Galeocerdo cuvier](/source/Galeocerdo_cuvier)''
* ''[Galeorhinus galeus](/source/Galeorhinus_galeus)''
* ''[Hemipristis serra](/source/Hemipristis_serra)''
* ''[Heptranchias perlo](/source/Heptranchias_perlo)''
* ''[Heterodontus sp.](/source/Heterodontus)''
* ''[Isistius sp.](/source/Isistius)''
* ''[Lampadena scapha](/source/Lampadena_scapha)''<ref name=Schwarzhans2013/>
* ''[Lepidophanes inflectus](/source/Lepidophanes_inflectus)''<ref name=Schwarzhans2013/>
* [Megalodon](/source/Megalodon)
* ''[Mustelus sp.](/source/Mustelus)''
* ''[Myctophum arcanum](/source/Myctophum_arcanum)'', ''[M. degraciai](/source/Myctophum_degraciai)''<ref name=Schwarzhans2013/>
* ''[Myliobatis sp.](/source/Myliobatis)''
* ''[Premontreia sp.](/source/Premontreia)''
* ''[Pristiophorus sp.](/source/Pristiophorus)''
* ''[Pseudocarcharias kamoharai](/source/Pseudocarcharias_kamoharai)''
* ''[Rhizoprionodon sp.](/source/Rhizoprionodon)''
* ''[Sphyrna lewini](/source/Sphyrna_lewini)''
* ''[Squalus sp.](/source/Squalus)''
* ''[Squatina sp.](/source/Squatina)''
* ''[Trigonognathus sp.](/source/Trigonognathus)''
{{div col end}}

=== Mammals ===
* ''[Isthminia panamensis](/source/Isthminia_panamensis)''<ref name=FWSTRI650009>[https://paleobiodb.org/classic/displayCollResults?collection_no=172931 STRI 650009] at [Fossilworks](/source/Fossilworks).org</ref><ref name=Pyenson2015>Pyenson et al., 2015</ref>
* ''[Nanokogia isthmia](/source/Nanokogia)''<ref name=Velez2015>Vélez Juarbe et al., 2015</ref>

=== Invertebrates ===
* ''[Fusiturricula fenimorei](/source/Fusiturricula_fenimorei)''<ref name=Hendy2008>Hendy et al., 2008</ref>

== See also ==
{{Portal|Earth sciences|Paleontology|Panama}}
* [List of fossiliferous stratigraphic units in Panama](/source/List_of_fossiliferous_stratigraphic_units_in_Panama)

== References ==
{{reflist|30em}}

=== Bibliography ===
* {{citation |last1=Aguilera |first1=Órangel A. |last2=Schwarzhans |first2=Werner |last3=Béarez |first3=Philippe |year=2016 |title=Otoliths of the Sciaenidae from the Neogene of tropical America |url=https://www.researchgate.net/publication/301301677 |journal=[Palaeo Ichthyologica](/source/Palaeo_Ichthyologica) |volume=14 |pages=7–90 |access-date=2019-02-09}}
* A. J. W. Hendy, D. P. Buick, K. V. Bulinski, C. A. Ferguson, and A. I. Miller. 2008. Unpublished census data from Atlantic coastal plain and circum-Caribbean Neogene assemblages and taxonomic opinions
* {{citation|author1-link=Nicholas Pyenson |last1=Pyenson |first1=Nicholas D. |last2=Vélez Juarbe |first2=Jorge |last3=Gutstein |first3=Carolina S. |last4=Little |first4=Holly |last5=Vigil |first5=Dioselina |last6=O'Dea |first6=Aaron |year=2015 |title=''Isthminia panamensis'', a new fossil inioid (Mammalia, Cetacea) from the Chagres Formation of Panama and the evolution of 'river dolphins' in the Americas |url=https://peerj.com/articles/1227.pdf |journal=[PeerJ](/source/PeerJ) |volume=3 |article-number=e1227 |doi=10.7717/peerj.1227 |doi-access=free |pmid=26355720 |pmc=4562255 |access-date=2019-02-09}}
* {{citation |last1=Schwarzhans |first1=Werner |last2=Aguilera |first2=Órangel |year=2013 |title=Otoliths of the Myctophidae from the Neogene of tropical America |url=http://www.pfeil-verlag.de/07pala/e4_66.php |journal=[Palaeo Ichthyologica](/source/Palaeo_Ichthyologica) |volume=13 |pages=83–150 |access-date=2019-02-09}}
* {{citation |last1=Stewart |first1=R.H. |last2=Stewart |first2=J.L. |last3=Woodring |first3=W.P. |year=1980 |title=Geologic Map of the Panama Canal and Vicinity |url=https://pubs.usgs.gov/pp/0306f/plate-1.pdf |publisher=[USGS](/source/United_States_Geological_Survey) |page=1 |access-date=2019-02-09}}
* {{citation |last1=Vélez Juarbe |first1=Jorge |last2=Wood |first2=Aaron R. |last3=De Gracia |first3=Carlos |last4=Hendy |first4=Austin J.W. |year=2015 |title=Evolutionary Patterns among Living and Fossil Kogiid Sperm Whales: Evidence from the Neogene of Central America |journal=[PLoS ONE](/source/PLoS_ONE) |volume=10 |issue=4 |article-number=e0123909 |doi=10.1371/journal.pone.0123909 |doi-access=free |pmid=25923213 |pmc=4414568 |bibcode=2015PLoSO..1023909V }}
* {{citation |last=Woodring |first=W.P |year=1957 |title=Geology and Paleontology of Canal Zone and Adjoining Parts of Panama - 306A Geology and description of Tertiary mollusks (Gastropods: Trochidae to Turritellidae) |url=https://pubs.usgs.gov/pp/0306a/report.pdf |publisher=[USGS](/source/United_States_Geological_Survey) |pages=1–186 |access-date=2019-02-09}}

Category:Geologic formations of Panama
Category:Neogene Panama
Category:Messinian
Category:Tortonian
Category:Clarendonian
Category:Hemphillian
Category:Sandstone formations
Category:Siltstone formations
Category:Shallow marine deposits
Category:Paleontology in Panama
Formations
Formations

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Adapted from the Wikipedia article [Chagres Formation](https://en.wikipedia.org/wiki/Chagres_Formation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Chagres_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.