Seymour Island
Encyclopedia
Seymour Island is an island in the chain of 16 major islands around the tip of the Graham Land
on the Antarctic Peninsula
. Graham Land is closer to continental land mass than any other part of that Antarctica. It lies within the section of the island chain that resides off the west side of the peninsula's northernmost tip. Within that section, it lies slightly to the north of Snow Hill Island
and just of east of the larger key, James Ross Island
, and its smaller, neighboring island, Vega Island
.
Seymour Island is sometimes called Marambio Island or Seymour-Marambio Island, taking its resident Argentine base as its namesake (see section, Base Antárctica Marambio, below).
base in Antarctica operating an airfield ( ICAO
SAWB ) for wheeled landing the whole year. In winter the base has an average of 55 crew members, but in summer the population of the base can grow to 180.
temperature as low as −60 °C.
to the Eocene
. Successively younger rock formations found on the island are the López de Bertodano Formation
(Cretaceous to early Paleocene
) Sobral Formation
and Cross Valley Formation (Paleocene) and La Meseta Formation (Eocene).
In November 1882, when Norwegian
Captain, Carl Anton Larsen
landed his ship, the Jason
, on Seymour Island, he returned with more than maps of the territory, he found fossils of long-extinct species. Interestingly, Larsen's trip aboard the Jason was significantly more successful than his Swedish Antarctic Expedition
journey between 1901 and 1904. During that trip, his ship, the Antarctic, was crushed and sunk by icebergs, and he and his crew were forced to weather fourteen months on the neighboring Snow Hill Island
, surviving on penguins and seals
. Ever since his voyage on the Jason, the island has been the subject of paleontological
study.
Seymour Island has been the site of much study of the Eocene
period of climatic cooling, a process that culminated in the initiation of Antarctic glaciation. Studies of the fine fraction carbonate from sites in the Southern Ocean
suggest that, rather than a monotonic decrease in temperature over the Eocene period, the middle of the epoch was punctuated by a brief duration of warming (Bohaty and Zachos, 2003).
Seymour Island has been a site of study of many fossils from this particular part of the Eocene period, during which there was a more flourishing ecosystem
with diverse biota
as a result of the warmer climate. A diverse array of fossilized species have been studied on the Island, including extinct penguin
species (such as Palaeeudyptes klekowskii
and Archaeospheniscus wimani
), various species in the bivalvia
class and various types of flora
and fauna
.
A fossil marsupial
of the extinct family Polydolopidae was found on Seymour Island in 1982. This was the first evidence of land mammals having lived in Antarctica.
Further fossils have subsequently been found, including members of the marsupial orders Didelphimorphia
(opossum) and Microbiotheria
, as well as ungulate
s and a member of the enigmatic extinct order Gondwanatheria
, possibly Sudamerica ameghinoi.
Graham Land
Graham Land is that portion of the Antarctic Peninsula which lies north of a line joining Cape Jeremy and Cape Agassiz. This description of Graham Land is consistent with the 1964 agreement between the British Antarctic Place-names Committee and the US Advisory Committee on Antarctic Names, in...
on the Antarctic Peninsula
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....
. Graham Land is closer to continental land mass than any other part of that Antarctica. It lies within the section of the island chain that resides off the west side of the peninsula's northernmost tip. Within that section, it lies slightly to the north of Snow Hill Island
Snow Hill Island
Snow Hill Island is an almost completely snowcapped island, long and wide, lying off the east coast of the Antarctic Peninsula. It is separated from James Ross Island to the northeast by Admiralty Sound...
and just of east of the larger key, James Ross Island
James Ross Island
James Ross Island is a large island off the southeast side and near the northeastern extremity of Antarctic Peninsula, from which it is separated by Prince Gustav Channel. Rising to , it is irregularly shaped and extends in a north-south direction. It was charted in October 1903 by the Swedish...
, and its smaller, neighboring island, Vega Island
Vega Island
Vega Island is a small island to the northwest of James Ross Island, on the Antarctic Peninsula.- See also :* Composite Antarctic Gazetteer* List of Antarctic islands south of 60° S* SCAR* Territorial claims in Antarctica- References :...
.
Seymour Island is sometimes called Marambio Island or Seymour-Marambio Island, taking its resident Argentine base as its namesake (see section, Base Antárctica Marambio, below).
Base Antárctica Marambio
Located in the island is the Marambio Base which is the main ArgentineArgentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
base in Antarctica operating an airfield ( ICAO
International Civil Aviation Organization airport code
The ICAO airport code or location indicator is a four-character alphanumeric code designating each airport around the world. These codes are defined by the International Civil Aviation Organization, and published in ICAO Document 7910: Location Indicators.The ICAO codes are used by air traffic...
SAWB ) for wheeled landing the whole year. In winter the base has an average of 55 crew members, but in summer the population of the base can grow to 180.
Climate
The average temperatures on Seymour Island, as measured at Base Antárctica Marambio, are 1 °C (33.8 °F) during the summer and −21 °C during the winter. In the wintertime, however, strong winds can lower the wind chillWind chill
Wind chill is the felt air temperature on exposed skin due to wind. The wind chill temperature is always lower than the air temperature, and the windchill is undefined at the higher temps...
temperature as low as −60 °C.
Paleontological significance
The rocks making up Seymour Island date mainly from the Late CretaceousLate Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
to the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
. Successively younger rock formations found on the island are the López de Bertodano Formation
Lopez de Bertodano Formation
The Lopez de Bertodano Formation is a geological formation in the James Ross archipelago of the Antarctic Peninsula. The strata date to the end of the Late Cretaceous , about 70-65 million years ago. Dinosaur remains are among the fossils that have been recovered from the formation....
(Cretaceous to early Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
) Sobral Formation
Sobral Formation
The Sobral Formation is a palaeontological formation located in Antarctica. It dates to the Danian stage of the Lower Paleocene period.Spectacular fossils documenting the wildlife soon after the dinosaurs became extinct are found in this formation. One of the most significant sites is on Seymour...
and Cross Valley Formation (Paleocene) and La Meseta Formation (Eocene).
In November 1882, when Norwegian
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
Captain, Carl Anton Larsen
Carl Anton Larsen
Carl Anton Larsen was a Norwegian Antarctic Explorer, who made important contributions to the exploration of Antarctica, the most significant being the first discovery of fossils, for which he received the Back Grant from the Royal Geographical Society...
landed his ship, the Jason
Jason (Ship)
Jason was a Norwegian whaling vessel laid down in 1881 in Rødsverven, Norway, the same shipyard which later built Ernest Shackleton's ship the Endurance...
, on Seymour Island, he returned with more than maps of the territory, he found fossils of long-extinct species. Interestingly, Larsen's trip aboard the Jason was significantly more successful than his Swedish Antarctic Expedition
Swedish Antarctic Expedition
The Swedish Antarctic Expedition was led by Otto Nordenskjöld and Carl Anton Larsen.-Background:Otto Nordenskjöld, a Swedish geologist and geographer, organized and lead a scientific expedition of the Antarctic Peninsula...
journey between 1901 and 1904. During that trip, his ship, the Antarctic, was crushed and sunk by icebergs, and he and his crew were forced to weather fourteen months on the neighboring Snow Hill Island
Snow Hill Island
Snow Hill Island is an almost completely snowcapped island, long and wide, lying off the east coast of the Antarctic Peninsula. It is separated from James Ross Island to the northeast by Admiralty Sound...
, surviving on penguins and seals
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
. Ever since his voyage on the Jason, the island has been the subject of paleontological
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
study.
Seymour Island has been the site of much study of the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
period of climatic cooling, a process that culminated in the initiation of Antarctic glaciation. Studies of the fine fraction carbonate from sites in the Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...
suggest that, rather than a monotonic decrease in temperature over the Eocene period, the middle of the epoch was punctuated by a brief duration of warming (Bohaty and Zachos, 2003).
Seymour Island has been a site of study of many fossils from this particular part of the Eocene period, during which there was a more flourishing ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
with diverse biota
Biota (ecology)
Biota are the total collection of organisms of a geographic region or a time period, from local geographic scales and instantaneous temporal scales all the way up to whole-planet and whole-timescale spatiotemporal scales. The biota of the Earth lives in the biosphere.-See...
as a result of the warmer climate. A diverse array of fossilized species have been studied on the Island, including extinct penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
species (such as Palaeeudyptes klekowskii
Palaeeudyptes klekowskii
Palaeeudyptes klekowskii was a species of the extinct penguin genus Palaeeudyptes. It was approximately the size of its congener Palaeeudyptes antarcticus: somewhat larger than the Emperor Penguin. It is known from an extensive collection of fossil bones from the Late Eocene of the La Meseta...
and Archaeospheniscus wimani
Archaeospheniscus wimani
Archaeospheniscus wimani is an extinct species of penguin. It was the smallest species of the genus Archaeospheniscus, being approximately 75-85 cm high, or about the size of a Gentoo Penguin. It is also the oldest known species of its genus, as its remains were found in Middle or Late Eocene...
), various species in the bivalvia
Bivalvia
Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
class and various types of flora
Flora
Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...
and fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
.
A fossil marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
of the extinct family Polydolopidae was found on Seymour Island in 1982. This was the first evidence of land mammals having lived in Antarctica.
Further fossils have subsequently been found, including members of the marsupial orders Didelphimorphia
Didelphimorphia
Opossums make up the largest order of marsupials in the Western Hemisphere, including 103 or more species in 19 genera. They are also commonly called possums, though that term technically refers to Australian fauna of the suborder Phalangeriformes. The Virginia opossum was the first animal to be...
(opossum) and Microbiotheria
Microbiotheria
The Monito del Monte is the only extant member of its family and the only surviving member of an ancient order, the Microbiotheria. The oldest microbiothere currently recognised is Khasia cordillerensis, based on fossil teeth from Early Palaeocene deposits at Tiupampa, Bolivia...
, as well as ungulate
Ungulate
Ungulates are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. They make up several orders of mammals, of which six to eight survive...
s and a member of the enigmatic extinct order Gondwanatheria
Gondwanatheria
Gondwanatheria is an extinct group of mammals that lived during the Upper Cretaceous through the Eocene in the Southern Hemisphere, including Antarctica...
, possibly Sudamerica ameghinoi.
See also
- Composite Antarctic Gazetteer
- List of Antarctic islands south of 60° S
- SCARScientific Committee on Antarctic ResearchThe Scientific Committee on Antarctic Research is an interdisciplinary body of the International Council for Science . It was established in February 1958 to continue the international coordination of Antarctic scientific activities that had begun during the International Geophysical Year of 1957-58...
- Territorial claims in Antarctica