Geography of Tristan da Cunha
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Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...
of five islands in the southern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, the largest of which is the island of Tristan da Cunha
Tristan da Cunha
Tristan da Cunha is a remote volcanic group of islands in the south Atlantic Ocean and the main island of that group. It is the most remote inhabited archipelago in the world, lying from the nearest land, South Africa, and from South America...
itself and the second-largest the remote bird haven Gough Island
Gough Island
Gough Island , also known historically as Gonçalo Álvares or Diego Alvarez, is a volcanic island in the South Atlantic Ocean. It is a dependency of Tristan da Cunha and part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha...
. It forms part of a wider territory called Saint Helena, Ascension and Tristan da Cunha
Saint Helena, Ascension and Tristan da Cunha
Saint Helena, Ascension and Tristan da Cunha is a British overseas territory and overseas territory of the European Union consisting of the islands of Saint Helena, Ascension Island and the Tristan da Cunha group...
which includes Saint Helena
Saint Helena
Saint Helena , named after St Helena of Constantinople, is an island of volcanic origin in the South Atlantic Ocean. It is part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha which also includes Ascension Island and the islands of Tristan da Cunha...
and Ascension Island
Ascension Island
Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around from the coast of Africa and from the coast of South America, which is roughly midway between the horn of South America and Africa...
.
Location and description
This archipelago, 1500 miles (2500 km) from the continents of Africa and South America, is one of the most remote places on earth with human habitation. It consists of the following islands:- the main island Tristan da Cunha and its surrounding islands
- Tristan da CunhaTristan da CunhaTristan da Cunha is a remote volcanic group of islands in the south Atlantic Ocean and the main island of that group. It is the most remote inhabited archipelago in the world, lying from the nearest land, South Africa, and from South America...
, the main island and largest (37°6′44"S 12°16′56"W) area: 113 square kilometres (43.6 sq mi) - Inaccessible IslandInaccessible IslandInaccessible Island is an extinct volcano, 14 km² in area, rising out of the South Atlantic Ocean 45 km southwest of Tristan da Cunha. Inaccessible Island is located at . It is part of the archipelago of Tristan da Cunha, which is part of the overseas territory of the United Kingdom,...
area: 14 square kilometres (5.4 sq mi) - Nightingale IslandsNightingale IslandsThe Nightingale Islands are a group of three islands in the South Atlantic Ocean, part of the Tristan da Cunha territory. They consist of Nightingale Island, Middle Island and Stoltenhoff Island. The islands are administered by the United Kingdom as part of the overseas territory of Saint Helena,...
area: 3.4 square kilometres (1.3 sq mi)- Nightingale IslandNightingale IslandNightingale Island is an island in the South Atlantic Ocean, 3 km² in area, part of the Tristan da Cunha group of islands. They are administered by the United Kingdom as part of the overseas territory of Saint Helena, Ascension and Tristan da Cunha....
area: 3.2 square kilometres (1.2 sq mi) - Middle IslandMiddle Island, Tristan da CunhaMiddle Island is a small, uninhabited island in the South Atlantic Ocean, part of the Nightingale Islands. They are governed as part of Tristan da Cunha, an archipelago that is part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha.-External links:*...
area: 0.1 square kilometres (24.7 acre) - Stoltenhoff IslandStoltenhoff IslandStoltenhoff Island is a small uninhabited island in the South Atlantic Ocean, part of the Nightingale Islands. It is the smallest of the Nightingale Islands, and is to the north west of Nightingale Island itself...
area: 0.1 square kilometres (24.7 acre)
- Nightingale Island
- Tristan da Cunha
- Gough IslandGough IslandGough Island , also known historically as Gonçalo Álvares or Diego Alvarez, is a volcanic island in the South Atlantic Ocean. It is a dependency of Tristan da Cunha and part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha...
(Diego Alvarez) area: 68 square kilometres (26.3 sq mi) important as the largest undisturbed cool-temperate island habitat in the South Atlantic Ocean.
The main island is quite mountainous; the only flat area is the location of the capital, Edinburgh of the Seven Seas
Edinburgh of the Seven Seas
Edinburgh of the Seven Seas is the main settlement of the island of Tristan da Cunha, in the Saint Helena, Ascension and Tristan da Cunha overseas territory of the United Kingdom, in the South Atlantic Ocean...
, on the northwest coast. The highest point is a volcano called Queen Mary's Peak
Queen Mary's Peak
Queen Mary's Peak is the summit of the island of Tristan da Cunha, in the South Atlantic Ocean. It has an elevation of 2,062 metres above sea level. It is named after Mary of Teck, the Queen consort of King George V...
2062 metres (6,765.1 ft); it is covered by snow
Snow
Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...
in winter and is listed as an ultra prominent peak
Ultra prominent peak
An ultra prominent peak, or Ultra for short, is a mountain with a topographic prominence of or more. There are a total of roughly 1,524 such peaks in the world. Some are famous even to non-climbers, such as Mount Everest, Aconcagua, and Mount McKinley , while others are much more obscure...
. Tristan da Cunha is thought to have been formed by a long-lived centre of upwelling magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
called the Tristan hotspot
Tristan hotspot
The Tristan hotspot is a volcanic hotspot which is responsible for the volcanic activity which forms the volcanoes in the southern Atlantic Ocean. It is thought to have formed the island of Tristan da Cunha and the Walvis Ridge on the African Plate....
.
The climate is marine cool-temperate with small temperature differences between summer and winter (11.3° - 14.5°) and between day and night.
Flora
Even the smaller islands have some plant cover, with the larger ones dominated by fernFern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
s and moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
. Flora on the archiplego includes many endemic species and many that have a broad circumpolar distribution in the South Atlantic and South Pacific Oceans. Thus many of the species that occur in Tristan da Cunha occur as far away as New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
. For example the species Nertera depressa
Nertera depressa
Nertera depressa is a species of flowering plant in the family Rubiaceae. This species was first collected on Tristan da Cunha and Inaccessible Island, but has been found to be distributed in at broader distances from its original discovery such as New Zealand. An example plant associate of N...
was first collected in Tristan da Cunha, but has since been recorded in occurrence as far distant as New Zealand.
Fauna
Tristan da Cunha is home to ocean-going species including Subantarctic Fur SealSubantarctic Fur Seal
The subantarctic fur seal is a fur seal found in the southern parts of the Indian and Atlantic Oceans. It was first described by Gray in 1872 from a specimen recovered in northern Australia—hence the inappropriate tropicalis specific name.- Description :The subantarctic fur seal is...
, the Southern Elephant Seal
Southern Elephant Seal
The Southern Elephant Seal is one of the two extant species of elephant seal. It is both the most massive pinniped and member of the order Carnivora living today...
and birds such as Northern Rockhopper Penguin
Northern Rockhopper Penguin
The Northern Rockhopper Penguin, Eudyptes c. moseleyi, is usually considered a subspecies of rockhopper penguin, although fairly recent studies show evidence of distinction from the Southern Rockhopper Penguin group Eudyptes c. chrysocome/E. c. filholi.A study published in 2009 showed that the...
s and Macaroni Penguin
Macaroni Penguin
The Macaroni Penguin is a species of penguin found from the Subantarctic to the Antarctic Peninsula. One of six species of crested penguin, it is very closely related to the Royal Penguin, and some authorities consider the two to be a single species...
s. The islands are important for their bird life both those established on the islands and breeding seabirds, of which twenty species nest on Gough Island alone. Important species include Tristan Albatross
Tristan Albatross
The Tristan Albatross, Diomedea dabbenena, is a large seabird from the albatross family. One of the great albatrosses of the genus Diomedea, it was only widely recognised as a full species in 1998.-Taxonomy:...
, Tristan Thrush
Tristan Thrush
The Tristan Thrush , also known as the Starchy, is a species of bird in the thrush family that is endemic to the isolated Tristan da Cunha archipelago in the South Atlantic Ocean.-Description:...
, Tristan Bunting
Tristan Bunting
The Inaccessible Island Finch is a species of bird in the Thraupidae family .It is endemic to Inaccessible Island of the Tristan da Cunha archipelago....
, Gough Bunting
Gough Bunting
The Gough Bunting or Gough Finch is a songbird species. Traditionally considered a bunting and placed in the family Emberizidae, it is actually neither a bunting nor a true finch, but belongs to a group of finch-like birds or tanager-finches in the family Thraupidae...
, Gough Island Moorhen
Gough Island Moorhen
The Gough Moorhen, Gallinula comeri, is a medium-sized, almost flightless bird that is similar to the Common Moorhen , but is smaller, stockier, and has shorter wings. The bird has a distinctive bill that is reddish with a yellow tip. Its first account was written by the polar explorer George...
, Atlantic Petrel
Atlantic Petrel
The Atlantic Petrel is a gadfly petrel endemic to the South Atlantic Ocean. It breeds in enormous colonies on Tristan da Cunha and Gough Island, and ranges at sea from Brazil to Namibia, with most records at sea being to the west of the breeding islands, and along the subtropical convergence.The...
, and the Inaccessible Island Rail
Inaccessible Island Rail
The Inaccessible Island Rail is a small bird of the rail family, Rallidae. It is the only species in its genus. It is found only on Inaccessible Island in the Tristan Archipelago, and is notable for being the smallest extant flightless bird in the world...
. There are no native reptiles, amphibians, freshwater fish, or land mammals.
Human settlement
Apart from Tristan da Cunha, which was settled as a base for whalingWhaling
Whaling is the hunting of whales mainly for meat and oil. Its earliest forms date to at least 3000 BC. Various coastal communities have long histories of sustenance whaling and harvesting beached whales...
and sealing in the 18th century, the islands of the group are uninhabited except for a weather station on Gough Island belonging to South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
. Fishing is still an important economic activity especially for crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
and octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
but also the Tristan rock lobster
Tristan rock lobster
The Tristan rock lobster, Jasus tristani, is a species of rock lobster endemic to the Tristan da Cunha archipelago and Vema Seamount, north-east of Tristan. It is very closely related to J. paulensis and these two may represent a single species. The Tristan rock lobster features on the coat of...
(Jasus tristani). Gough Island has also been used as base for whaling and sealing but only ever temporarily. The islands do receive a small number of tourists.
Threats and preservation
Sheep and cattle have been introduced on Tristan da Cunha and their grazing, along with other human activity has caused damage to the island's ecosystems. Night fishing has caused the deaths of many seabirds as they crash into ships' lightsSee also
- List of mountains and hills of Saint Helena, Ascension and Tristan da Cunha
- List of towns in Saint Helena, Ascension and Tristan da Cunha
- Geography of Saint HelenaGeography of Saint HelenaSaint Helena is an island in the South Atlantic Ocean, about mid-way between South America and Africa, at the geographic coordinates . St Helena has a land area of 122 square kilometres and is part of a wider territory called Saint Helena, Ascension and Tristan da Cunha which includes Ascension...