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Adelaide Island

Coordinates: 67°15′S 68°30′W / 67.25°S 68.5°W / -67.25; -68.5
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For the island in Russia, see Adelaide Island (Russia).

Adelaide Island
Adelaide Base, February 1962
Adelaide Island shown within the Antarctic Peninsula
Geography
LocationAntarctica
Coordinates67°15′S 68°30′W / 67.25°S 68.5°W / -67.25; -68.5
Area4,663 km2 (1,800 sq mi)
Length139 km (86.4 mi)
Width37 km (23 mi)
Highest elevation2,315 m (7595 ft)
Highest pointMount Gaudry
Administration
Administered under the Antarctic Treaty System
Demographics
Populationaround 100

Adelaide Island or Isla Adelaida or Isla Belgrano is a large, mainly ice-covered island, 139 kilometres (75 nmi) long and 37 kilometres (20 nmi) wide, lying at the north side of Marguerite Bay off the west coast of the Antarctic Peninsula. The Ginger Islands lie off the southern end. Mount Bodys is the easternmost mountain on Adelaide Island, rising to over 1,220 m. The island lies within the Argentine, British and Chilean Antarctic claims.

History

Adelaide Island was discovered in 1832 by a British expedition under John Biscoe.[1] The island was first surveyed by the French Antarctic Expedition (1908–1910) under Jean-Baptiste Charcot.

According to a contemporary source, the island was named by Biscoe himself in honour of Queen Adelaide of the United Kingdom.[2]

Rothera Station November 2003, looking towards the Antarctic Peninsula

The Island has two bases on it. The old Adelaide Island base (also known as Base T) was set up by the Falkland Islands Dependencies Survey (FIDS), which became the British Antarctic Survey. The Base was closed due to an unstable skiway and operations were moved to the new Rothera Research Station during 1976-77; this base remains open. The old BAS base was transferred to the Chilean authorities in 1984, when it was renamed Teniente Luis Carvajal Villaroel Antarctic Base. The station was then used as a summer only station by the Chileans. However, the skiway and 'ramp' to the station from the plateau have all become so unstable that the Chilean Air Force (FACh) have ceased operating there. The Chilean Navy has visited the station almost every summer to ensure it is in good keeping. BAS employees also visit the station during the winter when access from the plateau is easier.

Due to the length of time that it has been inhabited the island is well mapped by Antarctic standards.

Geology

During the Mesozoic, the Antarctic Peninsula was the site of an active volcanic arc, with deposition of a fore-arc basin sequence. Included in that sequence is a 2-3 km succession of turbiditic coarse sandstones and volcanic rocks, exposed on the eastern portion of the Adelaide Island, which correlate with the Upper Jurassic-Lower Cretaceous Fossil Bluff Group on Alexander Island. The western portion of Adelaide Island is covered by the Fuchs Ice Piedmont. The oldest formation on Adelaide Island is the Late Jurassic Buchia Buttress Formation (149.5 Ma) of volcanic breccias, tuffs, and volcaniclastic rocks interbedded with coarse grained sandstones and pebble conglomerates. The Early Cretaceous Milestone Bluff Formation (113.9 Ma) is a sandstone-conglomerate indicating a shallowing trend. Volcanic formations on Adelaide Island include the Bond Nunatak Formation (75 Ma), which consists of basaltic andesite lavas interbedded with coarse grained volcaniclastics, and overlays the Buchia Buttress Formation. The Mount Leotard Formation (75-65 Ma), has up to 1800 m of basaltic andesite lavas, hyaloclastites and breccias. The Reptile Ridge Formation (67.6 Ma) is a rhyolitic ignimbrite up to 400 m thick. Finally, the Adelaide Island Intrusive Suite (45-52 Ma) are granodiorite-gabbro hybrid plutons with minor dolerite dykes.[3]

Geography

A number of features on and around Adelaide Island have been charted by various Antarctic expeditions, primarily the French Antarctic Expedition of 1909, under Charcot.

On the southeast coast of the island, 5 nmi (9.3 km) east of Mount Gaudry, 6 nmi (11 km) wide Ryder Bay indents the coast to a depth of 4 nmi (7.4 km). The Leonie Islands lie across the mouth of this bay. It was resurveyed in 1936 by the British Graham Land Expedition (BGLE) under Rymill, and in 1948 by the Falkland Islands Dependencies Survey (FIDS). The bay is named for Lisle C.D. Ryder, second mate on the Penola during the BGLE, 1934–37. Ives Bank is a submarine bank in the Bellingshausen Sea on the southern approaches to Ryder Bay.[4]

The southeast extremity of the island is Cape Alexandra, named by Charcot for Alexandra of Denmark, then Queen consort of England.[5]

See also

References

  1. ^ Stanton, William (1975). The Great United States Exploring Expedition. Berkeley: University of California Press. pp. 147. ISBN 0520025571.
  2. ^ Extract from the 'Tasmanian' of Hobart (11 October 1833). "Interesting to the World at Large". The Sydney Monitor, 2 November 1833. Retrieved 26 March 2015.
  3. ^ Riley, T.R.; Flowerdew, M.J.; Haselwimmer, C.E. (2011). Geological Map of Adelaide Island, Graham Land (1:200 00 scale), BAS GEOMAP 2 Series, sheet 2. Cambridge: British Antarctic Survey.
  4. ^ "Ryder Bay". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved 11 May 2020.
  5. ^ "Cape Alexandra". Geographic Names Information System. United States Geological Survey. Retrieved 11 May 2020.

Public Domain This article incorporates public domain material from websites or documents of the United States Geological Survey.

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