Montagu Island

Coordinates: 58°27′S 26°22′W / 58.45°S 26.36°W / -58.45; -26.36[1]
Source: Wikipedia, the free encyclopedia.

Montagu Island
Satellite image of Montagu, taken on 2 December 2019
Location of Montagu Island
Geography
Coordinates58°27′S 26°22′W / 58.45°S 26.36°W / -58.45; -26.36[1]
ArchipelagoSouth Sandwich Islands
Length12 km (7.5 mi)
Width10 km (6 mi)
Highest elevation1,370 m (4490 ft)
Highest pointMount Belinda
Administration
United Kingdom
Demographics
PopulationUninhabited

Montagu Island is the largest of the South Sandwich Islands, located in the Scotia Sea off the coast of Antarctica. It is almost entirely ice-covered with only sparse rocky outcrops, and consists of a large caldera with a large parasitic cone, Mount Oceanite. Several secondary volcanic cones have formed in the caldera, including Mount Belinda.

The island is rarely visited owing to the remote location, and there is only sparse vegetation. Penguins and seabirds live along the coasts. Before an eruption in 2001, which continued for several years and formed a lava delta on the northern coast, it was not known to have been active during the Holocene (the past 12,000 years).

Geography and geomorphology

Montagu Island is part of the

Thaddeus von Bellingshausen in 1815 determined that it was actually an island.[7]

With dimensions of 10 by 12 kilometres (6.2 mi × 7.5 mi), Montagu is the largest of the South Sandwich Islands.

coastal cliffs,[5] which alternate with ice falls.[13]

A 6 kilometres (3.7 mi) wide ice-filled

tidewater glacier exits the caldera to reach the sea. Several secondary cones have formed inside and around the caldera, including Mount Belinda[5] which is 1,125 metres (3,691 ft)[8] or 1,295 metres (4,249 ft) high.[14] The name has also been applied to the a peak on the southern caldera rim, which is the high point of Montagu Island[15] at 1,370 metres (4,490 ft).[2] Some parasitic cones rise above the cliffs.[16]

The submarine structure of Montagu Island is characterized by a largely regular, oval edifice with the pointy end to the west.

potassium-argon dating has yielded ages of 32–28 million years.[22]

Geology

During the past five million years, westward

Sandwich Plate has given rise to the island arc volcanism of the South Sandwich Islands. The islands are mostly stratovolcanoes consisting of basalt and basaltic andesite, and most islands feature active fumaroles, reports of steam emission or outright eruptions. Additional volcanoes are submarine volcanoes like Protector Shoal, which in 1962 produced a pumice raft that reached New Zealand.[2]

The few outcrops indicate that Montagu Island is formed by alternating layers of

oceanites;[24] Mount Oceanite is named after these rocks.[25] Diopside occurs also inclusions in other volcanic rocks.[26] Sediments subducted into the trench may play a role in the formation of Montagu magmas.[27]

Ecology

algae in penguin colonies.[29] Mites and springtails have been collected.[32]

Eruptive history

A rock from

potassium-argon dating.[33] Before 1990, there was no indication of any historical or Holocene activity at Montagu.[34] Other seabirds and seals occasionally come ashore on the island.[35] This probably reflects its remote location and extensive ice cover.[5] Landing parties likewise did not document any heated ground or fumarole activity.[29] Eruptions of low intensity may have taken place between 1995 and 1997.[2]

Pyroclastic cone formed by the 2001–2007 eruption, with melt pits, tephra-covered ice and a moat formed by ice melting[36]

lava bombs.[36] The eruption led to the pronounced melting and disruption of the ice cap,[43] with one glacier advancing into the sea.[44]

This eruption was discovered and followed almost exclusively through

satellite imaging,[45] which also recorded sulfur dioxide emissions[46] at a rate of 180 tons per day while the eruption was ongoing.[8]

Placenames

The island was named by Cook after John Montagu, 4th Earl of Sandwich, at the time First Lord of the Admiralty.[47] Most placenames including Mount Belinda were assigned during the Discovery Investigations, often after participants to the expeditions or their relatives.[48][49][50][51][52][53] Hollow Point is a translation of Spanish Hueca Point, a name used on Argentine maps in 1953.[54] Mathias Point was named after the helicopter pilot during the HMS Protector expedition in 1964,[55] Leeson Point after the lieutenant/pilot on the same ship,[56] and Poncet Point after a yachter who was the first person to land on this new land.[12]

References

  1. ^ LeMasurier et al. 1990, p. 363.
  2. ^ a b c d e f g Patrick et al. 2005, p. 416.
  3. ^ Liu et al. 2020, p. 3.
  4. ^ Holdgate & Baker 1979, p. 6.
  5. ^ a b c d e f g h Patrick et al. 2005, p. 417.
  6. ^ Holdgate & Baker 1979, p. 4.
  7. ^ Holdgate & Baker 1979, p. 5.
  8. ^ a b c d Liu et al. 2020, p. 13.
  9. ^ GVP 2023, General Information.
  10. ^ LeMasurier et al. 1990, pp. 382, 383.
  11. ^ Leat et al. 2013, p. 65.
  12. ^ a b c BASMaps 2013, Poncet Point.
  13. ^ Holdgate & Baker 1979, p. 46.
  14. ^ GVP 2023, Synonyms & Subfeatures.
  15. ^ a b GVP 2023, Bulletin Reports.
  16. ^ a b Holdgate & Baker 1979, p. 48.
  17. ^ a b Leat et al. 2013, p. 67.
  18. ^ Leat et al. 2013, p. 73.
  19. ^ Leat et al. 2013, p. 66.
  20. ^ Leat et al. 2016, p. 297.
  21. ^ Leat et al. 2016, p. 300.
  22. ^ Leat et al. 2016, p. 294.
  23. ^ Pearce et al. 1995, p. 1076.
  24. ^ LeMasurier et al. 1990, p. 364.
  25. ^ GNIS 2023c, Mount Oceanite.
  26. ^ Pearce et al. 1995, p. 1087.
  27. ^ Leat et al. 2003, p. 298.
  28. ^ Lynch et al. 2016, pp. 1620–1622.
  29. ^ a b c Holdgate & Baker 1979, p. 49.
  30. ^ Convey, Morton & Poncet 1999, p. 117,119.
  31. ^ Gressitt 1967, p. 342.
  32. ^ Convey, Greenslade & Pugh 2000, p. 602.
  33. ^ LeMasurier et al. 1990, p. 365.
  34. ^ LeMasurier et al. 1990, p. 382.
  35. ^ Holdgate & Baker 1979, p. 50.
  36. ^ a b Smellie 2023, p. 33.
  37. ^ Patrick et al. 2005, p. 415.
  38. ^ Patrick & Smellie 2013, p. 489.
  39. ^ Patrick et al. 2005, p. 419.
  40. ^ Patrick et al. 2005, p. 420.
  41. ^ a b Patrick & Smellie 2013, p. 488.
  42. ^ Patrick & Smellie 2013, p. 490.
  43. ^ Barr et al. 2018, p. 197.
  44. ^ Patrick & Smellie 2013, p. 477.
  45. ^ Fioletov et al. 2016, p. 11510.
  46. ^ GNIS 2023a, Montagu Island.
  47. ^ GNIS 2023b, Mount Belinda.
  48. ^ GNIS 2023k, Longlow Rock.
  49. ^ GNIS 2023h, Horsburgh Point.
  50. ^ GNIS 2023j, Borley Point.
  51. ^ GNIS 2023g, Scarlett Point.
  52. ^ GNIS 2023f, Allen Point.
  53. ^ GNIS 2023i, Hollow Point.
  54. ^ GNIS 2023e, Mathias Point.
  55. ^ GNIS 2023d, Leeson Point.

Sources

External links
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