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 Cos ...
. 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, p ...
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 in ...
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 Torton ...
to
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 first ...
,
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 u ...
to
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 ...
period
Period may refer to:
Common uses
* Era, a length or span of time
* Full stop (or period), a punctuation mark
Arts, entertainment, and media
* Period (music), a concept in musical composition
* Periodic sentence (or rhetorical period), a concept ...
.
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 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 conduit ...
, 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
The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...
Carcharhinus plumbeus
The sandbar shark (''Carcharhinus plumbeus'') also known as the brown shark or thickskin shark, is a species of requiem shark, and part of the family Carcharhinidae, native to the Atlantic Ocean and the Indo-Pacific. It is distinguishable by it ...
Centrophorus granulosus
The gulper shark (''Centrophorus granulosus'') is a long and slender Squalidae, 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 snou ...
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 a s ...
Galeocerdo cuvier
The tiger shark (''Galeocerdo cuvier'') is a species of requiem shark and the last extant member of the family Galeocerdonidae. It is a large macropredator, capable of attaining a length over . Populations are found in many tropical and tempera ...
''
* ''
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 ...
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 member ...
Pseudocarcharias kamoharai
The crocodile shark (''Pseudocarcharias kamoharai'') is a species of mackerel shark and the only extant member of the family Pseudocarchariidae. A specialized inhabitant of the mesopelagic zone, the crocodile shark can be found worldwide in tropi ...
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 thi ...
Isthminia panamensis
''Isthminia'' is an extinct genus of river dolphin-like cetacean from the Late Miocene epoch (Hemphillian in the NALMA classification) that lived in Panama. The type species is ''I. panamensis''.STRI 650009 at
Fossilworks
Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database
The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...
.orgPyenson et al., 2015
* '' Nanokogia isthmia''Vélez Juarbe et al., 2015
*
* 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, a ...