{{Short description|Geologic formation in Panama}} {{Infobox rockunit | name = Chagres Formation | image = | caption = | type = Formation | age = Tortonian-Messinian<br />(Clarendonian-Hemphillian)<br />~{{fossil range|11.6|5.3}} | period = Messinian | prilithology = Sandstone | otherlithology = Siltstone | namedfor = Chagres River | namedby = MacDonald | year_ts = 1919 | region = Colón Province | country = 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'' | overlies = Gatún Formation | thickness = ''uncertain'' | extent = 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 in the Colón Province of central Panama. The sandstones and siltstones were deposited in a shallow marine environment and preserve fossils dating back to the Middle to Late Miocene (Tortonian to Messinian, Clarendonian to Hemphillian in the NALMA classification) period.

== Description == The Chagres Formation is exposed in the northern part of the Panama Canal Zone. The formation overlies and partly overlaps the Gatún Formation. The outcrop area lies entirely west of the Panama Canal, extending from the Canal Zone southwestward along the Caribbean coast, about {{convert|45|km|mi}} southwest of Colón. 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. 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.org</ref>

=== Fish === {{div col|colwidth=18em}} * ''Alopias superciliosus'' * ''Benthosema pluridens''<ref name=Schwarzhans2013>Schwarzhans & Aguilera, 2013</ref> * ''Carcharhinus brachyurus'' * ''Carcharhinus cionei'' * ''Carcharhinus obscurus'' * ''Carcharhinus plumbeus'' * ''Carcharhinus signatus'' * ''Carcharodon plicatilis'' * ''Centrophorus granulosus'' * ''Cynoscion prolixus''<ref name=Aguilera2016>Aguilera et al., 2016</ref> * ''Dalatias licha'' * ''Diaphus barrigonensis'', ''D. rodriguezi''<ref name=Schwarzhans2013/> * ''Galeocerdo cuvier'' * ''Galeorhinus galeus'' * ''Hemipristis serra'' * ''Heptranchias perlo'' * ''Heterodontus sp.'' * ''Isistius sp.'' * ''Lampadena scapha''<ref name=Schwarzhans2013/> * ''Lepidophanes inflectus''<ref name=Schwarzhans2013/> * Megalodon * ''Mustelus sp.'' * ''Myctophum arcanum'', ''M. degraciai''<ref name=Schwarzhans2013/> * ''Myliobatis sp.'' * ''Premontreia sp.'' * ''Pristiophorus sp.'' * ''Pseudocarcharias kamoharai'' * ''Rhizoprionodon sp.'' * ''Sphyrna lewini'' * ''Squalus sp.'' * ''Squatina sp.'' * ''Trigonognathus sp.'' {{div col end}}

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

=== Invertebrates === * ''Fusiturricula fenimorei''<ref name=Hendy2008>Hendy et al., 2008</ref>

== See also == {{Portal|Earth sciences|Paleontology|Panama}} * 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 |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 |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 |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 |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 |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 |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