viernes, 5 de marzo de 2010

La Antartida



Antarctica is the fourth largest continent, after Asia, America and Africa, with 14,107,637 square kilometers. Its shape is roughly circular and lies almost entirely south of the Antarctic Circle.

Its northern Antarctic Peninsula is only 1,000 km from South America, while the distances of the nearest coast of Africa are about 3,800 km, 2530 km from Tasmania, Australia about 3135 km and 2,200 km from New Zealand.

It is divided into West Antarctica or Lesser smaller. and East Antarctica or greater, the rest of the continent. Both areas are partially separated by a notch which is located between the Weddell Sea and the Ross Sea, this notch is called Antarctica is sunk and a large subglacial basin bounded by the Ellsworth Mountains Antartandes and west and the Mountains Transantarctic east, and by the Polar Plateau in the south. It was hypothesized that, in fact, much of the call Antarctica is sunk several feet below sea level due to the enormous weight of the ice shell, which has depths of over 2,000 m. To the east of the Ross Sea and west of the Weddell Sea, the two major seas and more penetrating to the South Pole, the rest of the continent. Emphasizes the Antarctic Peninsula in the West, the South American continent.

The South Pole of Inaccessibility is located in Antarctica, relatively close to the geographic South Pole. The Pole of Inaccessibility is the most inaccessible of all the planet Earth and is located at the coordinates (82 ° 58'S 54 ° 40'E / -82,967, 54,667). At an altitude of 3,718 meters, in the adjoining areas also houses the Russian base Vostok.

Geological formation:
The Antarctic is a land mass that occupies the geographic South Pole of our planet, and even 160 million years ago was linked to India, Africa, Australia, New Zealand and South America, forming the supercontinent called Gondwana. By fragmenting Gondwana continents were shifting and for a long time Antarctica and Australia were joined and went south until Antarctica separated from Australia finally ended some 80 million years to lead Australia to the north, reaching its current position and formed what is today.

Talking about geology is it also the potential mineral wealth of Antarctica: they have verified the existence of coal deposits, but the weather, the thick ice and the Antarctic Treaty restrictions remain very limited although there is speculation prospecting that there are significant deposits of oil and other mineral deposits (iron, gold, etc.)..

Subglacial topography and bathymetry of the Antarctic. (click on image to view detail)
Alleged aspect of Antarctica without the ice shell. This map does not consider areas that are flooded almost immediately if the shell is melted and thereby raise the sea level, areas not considered by isostacia-after tens of thousands of years, would rise as they are now sunk by the enormous weight of hielos.Sobre almost the entire surface of the polar climate prevails continent, where the average temperature of the warmest month does not exceed 0 ° C. The weather called tundra, where the average warmest month above 0 ° C, occurs only in the most northern coastal areas, as in the Antarctic Peninsula and islands adjacent subantarctic islands. The average temperature in this region is -17 ° Celsius, and the lowest was registered in the Russian Antarctic station Vostok, July 21, 1983 when temperatures reached -89.3 ° C, the lowest temperature recorded in Earth's surface. These low temperatures are due not only to its location in the polar zone, but their average height and very little solar radiation. In addition, between 80% and 90% of the radiation received is reflected by the ice through its albedo, preventing the warming of the surface. Antarctic albedo is precisely the one that gives great importance to the climate of this continent since, reflect the extensive white ice and returned the partially solar heat back into space, says properly that Antarctica is "cooler Earth.

Punta RenierMenos 3% of the Antarctic continent is ice-free during the height of summer (in January) and in such meager <3%, 90% corresponds to the most northern areas of the Antarctic Peninsula.
However, due to global warming, Antarctica is losing about 152 km ³ of ice per year, representing an increase of sea level about 0.4 millimeters. Possibly, data from meteorology and climatology of Antarctica [1], do not give the average temperatures required to melt continental ice (the only thing you can do very well up sea level) due to global warming in the southern summer 2002 was fragmented and melted the ice shelf Larsen B had an area of 3240 km ² and a length of approximately 10,000 years.

Life in Antartica:

Until about 55 million years most of the Antarctic locations (continental drift) less high-latitude (in this case, further north) and therefore warmer, thanks to this and an inclination less than the present Earth's axis provided that this vast territory was covered by dense forests. The earliest records known at present (July 2008) of plants on the Antarctic continent date back some 400 million years old (Devonian). Then during the Paleozoic forests of tree ferns proliferated called Glossopteridales. The Mesozoic was characterized by the presence of ferns Dicroidium, appeared in the Cretaceous flowering plants (angiosperms).

Cenozoic and some 60 million years ago when even the current Antarctic continent Gondwana was linked to abundant forests of giant trees (mainly deciduous Fagaceae) and tree ferns including rampant fauna of monotremes, marsupials and reptiles "primitives" of the family of the tuatara (Sphenodontidaes). The landscape would have been very similar to the current south of Tierra del Fuego, Tasmania and New Zealand. Makes about 37 million years ago when Antarctica began to be gradually covered by ice.

Due to extreme weather conditions in Antarctica there is little vegetation, and very simple shapes, such as algae, mosses (as Saniania uncinata), and lichens (such as Xantonia elegans), however the northern coast of the Peninsula Antarctica and South West Indies have two basculares native plants and flowering plants: the Antarctic carnation (Colobanthus quitensis) and the Antarctic grass (Deschampsia antarctica), both plants and grow into tundra (in the most northerly of the islands) tussoks small mattresses ; the Deschampia antarctica is known for its resistance to ultraviolet radiation, and the compounds synthesized are studied for their therapeutic use for skin cancers.
Apart from the flora, which thrives mainly on islands and coasts of the Antarctic Peninsula, can also be found in the same edge Antarctic fungus species (Deschapmsia, Cephalosporium balanoides, Acrostalagnus etc.)..

Antarctica has a very special feature: the flowers of ice. These are formed on layers of sea ice from water vapor escaping from the cracks and holes in the ice surface. When in contact with cold air vapors are frozen, and salt in the surface begins to crystallize, serving as a nucleus to begin forming the flower.

The fauna is very scarce in the continent itself, but abundant in the ocean that surrounds it thanks to the cold water (if not too long under freezing point, ie below 0 ° C) are very conducive to existence of large numbers of marine life. The leopard seal, Weddell seals and penguins are examples of wildlife in Antarctica, called particular attention to fish adapted to living under the 0 ° C as belonging to the family of Nototheniidae and this particular species of Antarctic cod (Antarctic cod), Trematomus bernacchii and Trematomus hansoni whose blood and other fluids have antifreeze glycoproteins also possess these qualities eelpout fish who live more than 550 m deep abyssal areas Bellinghausen Sea among which stands out anguiliforme Gosztonya antarctica.

The near-freezing waters surrounding Antarctica are the largest habitat of familiar animals of all time: the blue whale, and the largest known invertebrate: the colossal squid (Mesonychoteuthis hamiltoni), the squid can weigh about 500 kg and have (with the tentacles) a length of 15 meters.

The increase of only 1 ° C due to global warming in the waters of the Southern Ocean threatens to cause a significant and abrupt change ecosystem especially in the waters of the South and the West Indies in ocean waters surrounding the northern Antarctic Peninsula with the emergence of predatory species that until recently stayed away from the cold, already apparent in early XXI century and the outbreak of crabs, sharks more sporadically.

In the Antarctic Peninsula and subantarctic islands, are the skuas, birds of prey belonging to two different species, the larger schools or brown (Catharacta antarctica) and Antarctic schools (South Polar Skua), predators of fish and other birds (eg hunting petrels), including abundant cetaceans whales, southern right whales, minke (Baleanoptera acurostrata), sperm whales (particularly of the species Physeter catodon) and blue whales, in the volatile birds are counted: cormorants as the imperial cormorant (Phalacrocorax atriceps), petrels and giant petrels (Macronectes giganteus) and white (Snow Petrel), albatross, gulls, terns and Antarctic pigeon (Chionis alba).

Antarctica, Earth's last continent to be discovered and get more rigorous and exotic tourism since the 1950s, although the regular tourism has been developing since the second half of 1960 when the state-owned shipping company opened the ELMA tourist cruises to Antarctica Argentina and at present are quite frequent as the cruise ships that make preantártica last stop in Ushuaia in the Falkland Islands and Punta Arenas (all parts of the Southern Cone most extreme), these cruises are almost always, to the present , coastal, visiting the coast and sea bases in the Antarctic Peninsula and the multitude of islands annexed (eg South West Indies).

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