South Sandwich Islands
The South Sandwich Islands are a remote group of islands located
in the extreme southern waters of the Atlantic Ocean, lying to the east of the Scotia Sea and just outside of the 60° South
line of latitude — a limit that is sometimes used to arbitrarily mark the northern boundary of the Southern Ocean. The
islands form part of the British overseas territory of South Georgia and the South Sandwich Islands (SGSSI).
The islands are located some 540 km southeast from South Georgia and 955 km east-northeast from the South Orkney Islands; to the southwest, 1,475 km of island-free Southern ocean waters lead to the Queen Maud coast of Antarctica at Cape Norvegia.
Of the 11 main islands that make up the South Sandwich Islands, the islands at the northern and southern end of the chain have been divided in to three groups: the Traversay Islands of the far north — Visokoi (35 km²), Zavodovski (25 km²) and Leskov (0.3 km²); the two islands of the Candlemas Islands group, also in the north — Candlemas Island (14 km²) and Vindication Island (5 km²); the three closely-spaced islands at the far southern end of the South Sandwich arc are collectively known as Southern Thule — Cook Island (20 km²), Thule (14 km²) and Bellinghausen (1 km²). The central islands of the arc form an unnamed chain that contains the largest islands of the South Sandwich Islands — Montagu Island (110 km²), Bristol Island (46 km²) and Saunders Island (40 km²).
The South Sandwich Islands are a 355 km long volcanic arc formation of 11 small islands and their minor offshore islets with a total land area of 310 km². These isolated islands are devoid of any significant vegetation cover other than lichens and can be characterised as being composed of bare rock, lava flows, ash and tephra deposits, with coasts lined by cliffs and steep rocky slopes interrupted by small beachs of dark volcanic sands and rock. Island interiors are draped in ice caps and glaciers where elevations permit. Most of the islands are dominated by a single stratovolcano — the islands are essentially the tips of emergent volcanoes that rise from the sea floor. A highest elevation of 1,371 m above sea level is reached at the cratered-summit of Mount Belinda on Montagu Island.
The South Sandwich Islands are a classic example of a youthful, volcanic island arc system. The deep South Sandwich Trench lies approximately 100 km to the east of the island arc, formed where the South American Plate subducts beneath the Scotia Plate. The islands themselves are located upon the small South Sandwich Plate, a plate that is bound by the subducting South American Plate on the east, the Antarctic Plate to the south and the Scotia plate to the west.
Active volcanism is a common feature on most of the islands, particularly on the larger islands of Bristol, Saunders and Montagu. 56 km northwest from the island of Zavodovski the conical-shaped Protector Shoal seamount rises to within 27 m of the sea surface; it is the northernmost volcano of the South Sandwich Islands.