Seymour Island
| Seymour Island | |
 Hercules aircraft landing on Seymour Island | |
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| Location: | 64°16’59"S, 56°45’0"W |
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| Population: | 0 |
Seymour Island is an island amongst the James Ross Island Group lying to the west of the northernmost tip of Graham Land in the British Antarctic Territory. Seymour is separated from Snow Hill Island to the south-west by Picnic Passage. It lies just east of the main island of the group, James Ross Island, separated from it by Admiralty Sound, and east its smaller, neighbouring island, Vega Island.
The island was sighted by James Ross in 1843 and named 'Cape Seymour' after Rear Admiral Sir George Francis Seymour (later Admiral of the Fleet), a Lord of the Admiralty. When the headland was found to be part of an island, it was renamed 'Seymour Island'.
Exploration
James Ross discovered the island 6 January 1843 without realising that it was an island separated from the mainland. He described it as the north-east headland of the sound and named it 'Cape Seymour'.
The feature was roughly charted by Carl Johan Larsen in 1892-93 and in 1893-94, at which time Larson found it to be an island. Larsen landed on the island on 2 December 1892 and on 18 November 1893: these are the occasions when he retrieved fossils: the first fossils recorded from the Antarctic.
The island was further charted by the Swedish Antarctic Expedition of 1902-03.
The island was surveyed by the Falkland Islands Dependencies Survey from "Hope Bay" in 1945-47. The island was rephotographed from the air by the United States Navy and from the helicopter of HMS Endurance in 1969, and further photographed from the air by the British Antarctic Survey in 1979.
Base and historic site
A wooden plaque and rock cairn stand at Penguins Bay, on the southern coast of Seymour Island. The plaque was placed on 10 November 1903 by the crew of the Argentinian Corvette Uruguay on a mission to rescue the members of the Swedish Antarctic Expedition led by Otto Nordenskiöld. The cairn was erected in January 1990 by Argentina at the site of the plaque in commemoration of the same event. The site has been designated a Historic Site or Monument (HSM 60), following a proposal by Argentina to the Antarctic Treaty Consultative Meeting.[1]
There is no British base on the island, but Argentina maintains a base there, named 'Marambio Base', operating an airfield for wheeled landing the whole year. It has a weather station.
Climate
The average temperatures on Seymour Island, as measured at the Argentine base are 1°C during the summer and −21°C during the winter. In the wintertime, however, strong winds can lower the wind chill temperature feeling to as low as −60°C on exposed skin.
On 9 February 2020, a temperature of 20.75°C was recorded on the island, which is the highest temperature ever recorded for the Antarctic region, breaking the previous record of 19.8°C recorded at Signy Island on 30 January 1982.[2][3]
Paleontological significance
The rocks making up Seymour Island date mainly from the Late Cretaceous 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). Seymour Island has been referred to as the Rosetta Stone of Antarctic palaeontology, due to the unparalleled insight it provides into the geological and palaeontological history of the continent.
In December 1892[4] when 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.
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 neighbouring Snow Hill Island, surviving on penguins and seals. Ever since his voyage on the Jason, the island has been the subject of paleontological study.
The Cretaceous-Paleogene boundary (K-Pg) outcrops on Seymour Island in the upper levels of the López de Bertodano Formation.[5] A small (but significant) iridium anomaly occurs at the boundary on Seymour Island, as at lower latitudes, thought to be fallout from the Chicxulub impactor in the Gulf of Mexico.[6] Directly above the boundary a layer of disarticulated fish fossils occurs, victims of a disturbed ecosystem immediately following the impact event.[5] Multiple reports have described evidence for climatic changes in Antarctica prior to the mass extinction,[7] but the extent to which these affected marine biodiversity is debated. Based on extensive marine fossil collections from Seymour Island, recent work has confirmed that a single and severe mass extinction event occurred at this time in Antarctica just as at lower latitudes.[8]
Seymour Island has also 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).[9]
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.[9]
A fossil marsupial of the extinct family Polydolopidae was found on Seymour Island in 1982.[10] 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,[11] as well as ungulates and a member of the enigmatic extinct order Gondwanatheria, possibly Sudamerica ameghinoi.[12][13][14]
See also
References
- ↑ "List of Historic Sites and Monuments approved by the ATCM (2012)". Antarctic Treaty Secretariat. 2012. http://www.ats.aq/documents/ATCM35/WW/atcm35_ww003_e.pdf. Retrieved 2014-01-04.
- ↑ Watts, Jonathan (2020-02-13). "Antarctic temperature rises above 20C for first time on record" (in en-GB). The Guardian. SSN 0261-3077. https://www.theguardian.com/world/2020/feb/13/antarctic-temperature-rises-above-20c-first-time-record. Retrieved 2020-02-13.
- ↑ "WMO verifies highest temperatures for Antarctic Region" (in en). 2017-03-01. https://public.wmo.int/en/media/press-release/wmo-verifies-highest-temperatures-antarctic-region. Retrieved 2020-02-13.
- ↑ Tønnessen, Joh. N. (1982). The History of Modern Whaling. University of California Press. pp. 150. ISBN 978-0-520-03973-5.
- ↑ 5.0 5.1 Zinsmeister, W.J. (1998). "Discovery of fish mortality horizon at the K-T Boundary on Seymour Island: Re-evaluation of events at the end of the Cretaceous". Journal of Paleontology 72 (3): 556–571. doi:10.1017/S0022336000024331. https://www.cambridge.org/core/journals/journal-of-paleontology/article/discovery-of-fish-mortality-horizon-at-the-k-t-boundary-on-seymour-island-re-evaluation-of-events-at-the-end-of-the-cretaceous/C6F72A86DAB664F2E2315A34B3875875.
- ↑ Elliot D.H.; Askin RA; Kyte FT; Zinsmeister WJ (1994). "Iridium and dinocysts at the Cretaceous-Tertiary boundary on Seymour Island, Antarctica: Implications for the K-T event". Geology 22 (8): 675. doi:10.1130/0091-7613(1994)022<0675:IADATC>2.3.CO;2. http://geology.gsapubs.org/content/22/8/675.short.
- ↑ Petersen, S.V.; Dutton A; Lohmann KC (2016). "End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change". Nature Communications 7: 12079. doi:10.1038/ncomms12079. PMID 27377632. Bibcode: 2016NatCo...712079P.
- ↑ Witts J.D.; Whittle RJ; Wignall PB; Crame JA; Francis JE; Newton RJ; Bowman VC (2016). "Macrofossil evidence for a rapid and severe Cretaceous-Paleogene mass extinction in Antarctica". Nature Communications 7: 11738. doi:10.1038/ncomms11738. PMID 27226414. Bibcode: 2016NatCo...711738W.
- ↑ 9.0 9.1 "Middle Eocene Warming On Seymour Island, Antarctica: Continental Shelf Paleotemperatures Recorded In Molluscan Carbonates". http://gsa.confex.com/gsa/2005AM/finalprogram/abstract_96130.htm. Retrieved 2007-02-09.
- ↑ Woodburne, Michael O.; Zinsmeister, William J. (Oct 1982). "Fossil Land Mammal from Antarctica". Science 218 (4569): 284–286. doi:10.1126/science.218.4569.284. PMID 17838631. Bibcode: 1982Sci...218..284W.
- ↑ Goin, Francisco J. (Dec 1999). "New Discoveries of "Opposum-Like" Marsupials from Antarctica (Seymour Island, Medial Eocene)". Journal of Mammalian Evolution 6 (4): 335–365. doi:10.1023/A:1027357927460.
- ↑ Reguero, Marcelo A.; Sergio A. Marenssi; Sergio N. Santillana (May 2002). "Antarctic Peninsula and South America (Patagonia) Paleogene terrestrial faunas and environments: biogeographic relationships". Palaeogeography, Palaeoclimatology, Palaeoecology 179 (3–4): 189–210. doi:10.1016/S0031-0182(01)00417-5. Bibcode: 2002PPP...179..189R.
- ↑ Mills, William James. Exploring Polar Frontiers: A Historical Encyclopedia, ABC-CLIO, 2003. ISBN 1-57607-422-6, ISBN 978-1-57607-422-0
- ↑ Goin, F.J.; Reguero, M.A.; Pascual, R.; von Koenigswald, W.; Woodburne, M.O.; Case, J.A.; Marenssi, S.A.; Vieytes, C. et al. (2006). "First gondwanatherian mammal from Antarctica". Geological Society, London, Special Publications 258 (1): 135–144. doi:10.1144/GSL.SP.2006.258.01.10. Bibcode: 2006GSLSP.258..135G.