Antarctic Islands:
Before Antarctica had been discovered, there was avid speculation as to what lay at the end of the southern world. Many an explorer, whaler, and adventurer sought their destinies and fortunes in the quest for the Southern Continent. Finally, after centuries, the Southern Ocean gave up its secrets and many islands were discovered dotted around Antarctica. The discoveries and histories of four of the biggest Sub-Antarctic islands are presented below.
The South Shetland Islands:
Only 1000km from Tierra del Fuego are the South Shetland Islands. There are four main groups in this 540km-long island chain, with one hundred and fifty or so islets approximately located 63-degrees south 54-degrees west. They are eighty percent glaciated and cover an area of 3688 sq km, the highest point Mt. Foster (2105m) on Smith Island. These islands, the closest of the big island-groups of the Peninsula, were discovered by William Smith in 1819 who was blown off-course in the Drake Passage.
Elephant Island is at the northeast end of the South Shetland chain. Chinstrap penguins reside here and 2000 year-old moss with 3m deep peat also appear. Landings are precarious due to craggy and rocky shores.
King George Island has less than ten percent of its 1295 sq km area free of ice. Large moss beds are present and it is home to gentoo and Adelie penguins. Upon it are stations and/or personnel from Argentina, Brazil, Chile, China, South Korea, Poland, Russia, Uruguay, Ecuador, Germany, Peru and the U.S., making the largest of the South Shetlands the unofficial capital of Antarctica.
Greenwich Island, a little south west of King George, is the site of Yankee Harbour, a protected almost circular, one-kilometre harbour on its southwest side. It was an anchorage point for 18th and 19th century sealers.
Livingston Island is the next largest island in the chain. It is also the Site of Special Interest No. 6 (according to the Antarctic Treaty) having the “greatest concentration of 19th century historical sites in Antarctica”.
Deception Island is a 12km wide broken ring of a collapsed volcano cone, making it one of the ‘safest natural harbours in the world despite periodic eruptions.’ The entrance is through a 230m wide and windy break in the 580m tall wall in which lies a potentially hull-piercing rock just below the surface. Underground volcanic vents remind one that the volcano is dormant, not extinct and had recently erupted in 1969 and again in 1991/2.
The South Orkney Islands:
Located around 47 degrees West and 60 degrees south, this group has four major islands: Coronation, the largest; Signy, Powell and Laurie Islands and includes the remote Inaccessible Islands. Eighty five percent glaciated and ranging over 622 sq km, the islands suffer cold westerly winds, with less than two hours sun on an overcast day. Discovered in 1821 by sealers; gentoo, Adelie and chinstrap penguins also roost here.
Signy Island, even though a small 6.5km by 5km island, is an important research base for biological studies, especially plant life such as the Colobanthus quintensis which can be abundant, grow around 25cm meters wide and make compacted cushions in sheltered low-altitude regions. Signy Island also has many small lakes located in well-vegetated, mossy areas, that are home to blue-green algae, microbes and bacteria, crustaceans, worms, and nematodes, which get enriched by salt spray and seal feces. Due to the remoteness and recent deglaciation, none of the Antarctic lakes have mollusks or fish.
South Georgia Island:
Discovered in 1675 by a merchant blown further south and off course while rounding Cape Horn, this island is 170km by 40km covering 3755 sq km. At 38 degrees west and 54 degrees south with smaller surrounding islands, it is rugged, heavily glaciated (more on its south side than the north due to its aspect) and mountainous, the Allardyce Range forming the backbone of the island, Mt. Paget at 2934m, the highest point. Mean average temperatures on South Georgia are two degrees Celsius, with seasonal variations of seven degrees, some summers being 15 to 20 degrees Celsius. This leaves a growing season of a hundred to hundred and thirty five growing days in the Maritime north, while the coastal continent receives around sixty days of growth. Eighteen thousand years ago, temperatures in the south east Atlantic were four degrees lower than today causing an ice cap to form on South Georgia.
While South Georgia is fifty-eight percent glaciated with a periglacial or tundra-like environment, eighty-five percent of the coasts are ice-free, comprised of hard rock cliffs. South Georgia also has twenty-six vascular plants, of which sixty-four percent of the flowering plants share an affinity with South America/Tierra del Fuego, this characteristic likely due to the ‘prevailing westerly winds’ which bring in nesting birds, air and ocean currents.
The northeast coast is fjorded, though harbour areas (used by early whaling stations) are protected from the westerlies by the mountains. The island is cold, cloudy and windy with hardly any seasonal change. South Georgia also has some of the best and largest sand and gravel beaches in the Polar Region, due to past glacial action. Ferns grow on the island, which is inhabited by elephant seals, seabirds, Antarctic fur seals, and macaroni and king penguins.
The South Sandwich Islands:
Almost covered in ice, this eleven-island group running in a rough north-south arc was discovered by Captain James Cook in 1775. The islands cover 310 sq km ranging approximately from 59 degrees south to 26 degrees west. There are three small, contained island groups, with three larger, individual islands strung out along the way. However, due to their position near active converging tectonic plates, the islands are volcanic with both basalt and andesite eruptions occurring in this island group.
All the islands, Montagu being the largest, were formed by volcanoes a “relatively short time ago” and some still show volcanic activity as observed in 1908 and by scientists in 1956 when “three jets of glowing material shot 300m into the air” for forty-eight hours. Thirty-five kilometres off the northwest of the chain is also a submarine volcano. The volcano on Bellingshausen Island in the Southern Thule group of the South Sandwich Islands causes snowmelt and fumaroles, which helps facilitate sporadic but rich vegetation growth. Though more northerly than the South Shetlands and the South Orkney Islands, the South Sandwich Islands are colder due to seawater coming from the Weddell Sea. Claimed by both Britain and Argentina, the islands also have the largest penguin colony in the world.
The four big Sub-Antarctic island groups are wonders in themselves, still holding on to some secrets, while providing springboards for human habitation and scientific experiences in other cases. They are unique worlds and long may they continue to be.
Sources:
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Crossley, L. 2000. Explore Antarctica. Cambridge: Cambridge University Press.
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