The Chagres Formation (Tc)Geologic Map, 1980 is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

in the

Colón Province Colón () is a province of Panama. The capital is the city of Colón. It covers an area of 4,575.5 sq.km, and the latest estimate of population (for 2019) is 294,060.Instituto Nacional de Estadística y Censo, Panama. Overview This province h ...

of central

Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...

. The

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

s and

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...

s were deposited in a shallow marine

environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

and preserve

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating back to the Middle to Late Miocene (

Tortonian The Tortonian is in the geologic time scale an age or stage of the late Miocene that spans the time between 11.608 ± 0.005 Ma and 7.246 ± 0.005 Ma (million years ago). It follows the Serravallian and is followed by the Messinian. The Tort ...

Messinian The Messinian is in the geologic timescale the last age or uppermost stage of the Miocene. It spans the time between 7.246 ± 0.005 Ma and 5.333 ± 0.005 Ma (million years ago). It follows the Tortonian and is followed by the Zanclean, the fir ...

Clarendonian The Clarendonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 13,600,000 to 10,300,000 years BP, a period of . It is ...

Hemphillian The Hemphillian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 10,300,000 to 4,900,000 years BP. It is usually considered ...

in the NALMA classification) period.

Description

The Chagres Formation is exposed in the northern part of the

Panama Canal Zone The Panama Canal Zone ( es, Zona del Canal de Panamá), also simply known as the Canal Zone, was an unincorporated territory of the United States, located in the Isthmus of Panama, that existed from 1903 to 1979. It was located within the terr ...

. The formation overlies and partly overlaps the

Gatún Formation The Gatún Formation (Tg)Geologic Map, 1980 is a geologic formation in the Colón and Panamá Provinces of central Panama. The formation crops out in and around the Panama Canal Zone. The coastal to marginally marine sandstone, siltstone, c ...

. The outcrop area lies entirely west of the

Panama Canal The Panama Canal ( es, Canal de Panamá, link=no) is an artificial waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean and divides North and South America. The canal cuts across the Isthmus of Panama and is a Channel ( ...

, extending from the Canal Zone southwestward along the Caribbean coast, about 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.Woodring, 1957, p.47 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.

Fossil content

Various fossils have been found in the Chagres Formation:Pina
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cre ...

.org

Fish

* '' Alopias superciliosus'' * ''

Benthosema pluridens ''Benthosema'' is a genus of lanternfishes. Species The currently recognized species in this genus are: * ''Benthosema fibulatum'' ( C. H. Gilbert & Cramer, 1897) (spinycheek lanternfish) * ''Benthosema glaciale'' ( J. C. H. Reinhardt, 1837) (gl ...

''Schwarzhans & Aguilera, 2013 * '' Carcharhinus brachyurus'' * '' Carcharhinus cionei'' * '' Carcharhinus obscurus'' * '' Carcharhinus plumbeus'' * ''

Carcharhinus signatus The night shark (''Carcharhinus signatus'') is a species of requiem shark, in the family Carcharhinidae, found in the temperate and tropical waters of the Atlantic Ocean. An inhabitant of the outer continental shelf and upper continental slope ...

'' * ''

Carcharodon plicatilis ''Carcharodon'' () is a genus of sharks within the family Lamnidae. The only extant member is the great white shark (''Carcharodon carcharias''). Hubell's white shark (''Carcharodon hubbelli'') is an extinct member of this genus. Megalodon ...

'' * ''

Centrophorus granulosus The gulper shark (''Centrophorus granulosus'') is a long and slender dogfish usually about three feet in length generally found in deep, murky waters all around the world. It is a light grayish brown, paler ventrally, with a long snout and lar ...

'' * '' Cynoscion prolixus''Aguilera et al., 2016 * ''

Dalatias licha The kitefin shark or seal shark (''Dalatias licha'') is a species of squaliform shark in the family Dalatiidae, and the type species in its genus. It is found sporadically around the world, usually close to the sea floor at depths of . With ...

'' * '' Diaphus barrigonensis'', '' D. rodriguezi'' * '' Galeocerdo cuvier'' * ''

Galeorhinus galeus The school shark (''Galeorhinus galeus'') is a houndshark of the family Triakidae, and the only member of the genus ''Galeorhinus''. Common names also include tope, tope shark, snapper shark, and soupfin shark. It is found worldwide in temperate ...

'' * ''

Hemipristis serra ''Hemipristis serra'' is an extinct species of weasel shark which existed during the Miocene epoch. It was described by Louis Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born ...

'' * ''

Heptranchias perlo The sharpnose sevengill shark (''Heptranchias perlo''), also known as one-finned shark, perlon shark, sevengill cow shark, sharpsnouted sevengill or slender sevengill, is a species of shark in the family Hexanchidae, and the only living species ...

'' * '' Heterodontus sp.'' * '' Isistius sp.'' * '' Lampadena scapha'' * '' Lepidophanes inflectus'' *

Megalodon Megalodon (''Otodus megalodon''), meaning "big tooth", is an extinct species of mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. It was formerly thought to be a me ...

* '' Mustelus sp.'' * '' Myctophum arcanum'', '' M. degraciai'' * '' Myliobatis sp.'' * '' Premontreia sp.'' * '' Pristiophorus sp.'' * '' Pseudocarcharias kamoharai'' * '' Rhizoprionodon sp.'' * ''

Sphyrna lewini The scalloped hammerhead (''Sphyrna lewini'') is a species of hammerhead shark in the family Sphyrnidae. It was originally known as ''Zygaena lewini''. The Greek word ''sphyrna'' translates into "hammer" in English, referring to the shape of ...

'' * '' Squalus sp.'' * '' Squatina sp.'' * '' Trigonognathus sp.''

Mammals

* '' Isthminia panamensis''STRI 650009
at

.orgPyenson et al., 2015 * ''

Nanokogia isthmia ''Nanokogia'' is an extinct genus of pygmy sperm whale that lived off the coast of Panama during the Late Miocene. Description ''Nanokogia'' is distinguished from other kogiids in lacking functional teeth in the upper jaw, antorbital notches fo ...

''Vélez Juarbe et al., 2015

Invertebrates

* '' Fusiturricula fenimorei''Hendy et al., 2008

References

Bibliography

* * 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 * * * * * {{cite LSA , 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 The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

, pages=1–186 , accessdate=2019-02-09 Geologic formations of Panama Neogene Panama Messinian Tortonian Clarendonian Hemphillian Sandstone formations Siltstone formations Shallow marine deposits Paleontology in Panama Formations Formations

Description

Fossil content

Fish

Mammals

Invertebrates

See also

References

Bibliography