Antarctica 南极英文介绍

1、AntarcticaFrom Wikipedia, the free encyclopediaJump to: navigation, search This article is about the continent. For other uses, see Antarctica (disambiguation).AntarcticaArea14,000,000 km2 (5,400,000sqmi)1DemonymAntarcticanInternet TLD.aqAntarctica (i/ntrtk/ or /ntrktk/)Note 1 is Earths southernmost

2、 continent, containing the geographic South Pole. It is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14.0 millionkm2 (5.4 millionsqmi), it is the fifth-largest continent in area after Asia, Afr

3、ica, North America, and South America. For comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages at least 1 mile (1.6km) in thickness.Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average el

4、evation of all the continents.4 Antarctica is considered a desert, with annual precipitation of only 200mm (8inches) along the coast and far less inland.5 The temperature in Antarctica has reached 89 C (129 F). There are no permanent human residents, but anywhere from 1,000 to 5,000 people reside th

5、roughout the year at the research stations scattered across the continent. Only cold-adapted organisms survive there, including many types of algae, animals (for example mites, nematodes, penguins, seals and tardigrades), bacteria, fungi, plants, and protista. Vegetation where it occurs is tundra.Al

6、though myths and speculation about a Terra Australis (Southern Land) date back to antiquity, the first confirmed sighting of the continent is commonly accepted to have occurred in 1820 by the Russian expedition of Fabian Gottlieb von Bellingshausen and Mikhail Lazarev on Vostok and Mirny. The contin

7、ent, however, remained largely neglected for the rest of the 19th century because of its hostile environment, lack of resources, and isolation. The Antarctic Treaty was signed in 1959 by 12 countries; to date, 49 countries have signed the treaty. The treaty prohibits military activities and mineral

8、mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continents ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations.Contentshide 1 Etymology 2 History of exploration 3 Geography 4 Geology o 4.1 Geologic

9、al history and paleontology 4.1.1 Paleozoic era (540250 Ma) 4.1.2 Mesozoic era (25065 Ma) 4.1.3 Gondwanaland breakup (16023 Ma) 4.1.4 Neogene Period (230.05 mya)o 4.2 Geology of present-day Antarctica 5 Climate 6 Population 7 Biodiversity o 7.1 Animalso 7.2 Fungio 7.3 Plantso 7.4 Other organismso 7.

10、5 Conservation 8 Politics o 8.1 Antarctic territories 9 Economy o 9.1 Fisherieso 9.2 Tourismo 9.3 Scientific stations 10 Research o 10.1 Meteorites 11 Ice mass and global sea level 12 Effects of global warming 13 Ozone depletion 14 Notes 15 References 16 External linksEtymologyThe name Antarctica is

11、 the romanized version of the Greek compound word (antarktik), feminine of (antarktikos),6 meaning opposite to the Arctic, opposite to the north.7Before getting its present geographical connotations, the term was used for other locations which could be defined as opposite to the north. For example,

12、the short-lived French colony established at Brazil in the 16th Century was called France Antarctique.The first formal use of the name Antarctica as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew.8History of explorationMain article: History of Anta

13、rcticaSee also: List of Antarctic expeditionsAntarctica has no indigenous population and there is no evidence that it was seen by humans until the 19th century. However, belief in the existence of a Terra Australis a vast continent in the far south of the globe to balance the northern lands of Europ

14、e, Asia and North Africa had existed since the times of Ptolemy (1st century AD), who suggested the idea to preserve the symmetry of all known landmasses in the world. Even in the late 17th century, after explorers had found that South America and Australia were not part of the fabled Antarctica, ge

15、ographers believed that the continent was much larger than its actual size.A key part of the story of how Antarctica got its name is how it did not get named Terra Australis. Australia got named after this instead, and it was because of the mistake made by people who had decided that no significant

16、land mass further south of Australia would be found. Explorer Matthew Flinders, in particular, has been credited with popularizing the transfer of the name Terra Australis to Australia. He justified the titling of his book A Voyage to Terra Australis (1814) by writing in the introduction:There is no

17、 probability, that any other detached body of land, of nearly equal extent, will ever be found in a more southern latitude; the name Terra Australis will, therefore, remain descriptive of the geographical importance of this country, and of its situation on the globe: it has antiquity to recommend it

18、; and, having no reference to either of the two claiming nations, appears to be less objectionable than any other which could have been selected.9(For more info about how Australia got named after Terra Australis instead of Antarctica, see Australia#Etymology.)European maps continued to show this hy

19、pothesized land until Captain James Cooks ships, HMS Resolution and Adventure, crossed the Antarctic Circle on 17 January 1773, in December 1773 and again in January 1774.10 Cook came within about 75 miles (121km) of the Antarctic coast before retreating in the face of field ice in January 1773.11 T

20、he first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals. According to various organizations (the National Science Foundation,12 NASA,13 the University of California, San Diego,14 and other sources),1516 ships captained by three men sighted

21、Antarctica in 1820: Fabian Gottlieb von Bellingshausen (a Baltic German captain in the Imperial Russian Navy), Edward Bransfield (an Irish-born captain in the Royal Navy), and Nathaniel Palmer (an American sealer out of Stonington, Connecticut). Von Bellingshausen saw Antarctica on 27 January 1820,

22、three days before Bransfield sighted land, and ten months before Palmer did so in November 1820. On that day the expedition led by Von Bellingshausen and Mikhail Lazarev on ships Vostok and Mirny reached a point within 32km (20mi) of the Antarctic mainland and saw ice fields there. The first documen

23、ted landing on mainland Antarctica was by the American sealer John Davis in West Antarctica on 7 February 1821, although some historians dispute this claimcitation needed.On 22 January 1840, two days after the discovery of the coast west of the Balleny Islands, some members of the crew of the 1837-4

24、0 expedition of Jules Dumont dUrville disembarked on the highest islet17 of a group of rocky islands about 4km from Cape Godsie on the coast of Adlie Land where they took some mineral, algae and animal samples.18In December 1839, as part of the United States Exploring Expedition of 183842 conducted

25、by the United States Navy (sometimes called the Ex. Ex., or the Wilkes Expedition), an expedition sailed from Sydney, Australia, into the Antarctic Ocean, as it was then known, and reported the discovery of an Antarctic continent west of the Balleny Islands on 25 January 1840. That part of Antarctic

26、a was later named Wilkes Land, a name it maintains to this day.Nimrod Expedition South Pole Party (left to right): Wild, Shackleton, Marshall and AdamsExplorer James Clark Ross passed through what is now known as the Ross Sea and discovered Ross Island (both of which were named for him) in 1841. He

27、sailed along a huge wall of ice that was later named the Ross Ice Shelf. Mount Erebus and Mount Terror are named after two ships from his expedition: HMS Erebus and Terror.19 Mercator Cooper landed in East Antarctica on 26 January 1853.20During the Nimrod Expedition led by Ernest Shackleton in 1907,

28、 parties led by Edgeworth David became the first to climb Mount Erebus and to reach the South Magnetic Pole. Douglas Mawson, who assumed the leadership of the Magnetic Pole party on their perilous return, went on to lead several expeditions until retiring in 1931.21 In addition, Shackleton himself a

29、nd three other members of his expedition made several firsts in December 1908 February 1909: they were the first humans to traverse the Ross Ice Shelf, the first to traverse the Transantarctic Mountain Range (via the Beardmore Glacier), and the first to set foot on the South Polar Plateau. An expedi

30、tion led by Norwegian polar explorer Roald Amundsen from the ship Fram became the first to reach the geographic South Pole on 14 December 1911, using a route from the Bay of Whales and up the Axel Heiberg Glacier.22 One month later, the doomed Scott Expedition reached the pole.Richard E. Byrd led se

31、veral voyages to the Antarctic by plane in the 1930s and 1940s. He is credited with implementing mechanized land transport on the continent and conducting extensive geological and biological research.23 However, it was not until 31 October 1956 that anyone set foot on the South Pole again; on that d

32、ay a U.S. Navy group led by Rear Admiral George J. Dufek successfully landed an aircraft there.24The first person to sail single-handed to Antarctica was the New Zealander David Henry Lewis, in 1972, in a 10-meter steel sloop Ice Bird.GeographyMain article: Geography of AntarcticaSee also: Extreme p

33、oints of Antarcticaand List of Antarctic and subantarctic islandsLabelled map of Antarctica.Centered asymmetrically around the South Pole and largely south of the Antarctic Circle, Antarctica is the southernmost continent and is surrounded by the Southern Ocean; alternatively, it may be considered t

34、o be surrounded by the southern Pacific, Atlantic, and Indian Oceans, or by the southern waters of the World Ocean. It covers more than 14,000,000 km2 (5,400,000sqmi),1 making it the fifth-largest continent, about 1.3 times as large as Europe. The coastline measures 17,968km (11,165mi)1 and is mostl

35、y characterized by ice formations, as the following table shows:Coastal types around Antarctica25TypeFrequencyIce shelf (floating ice front)44%Ice walls (resting on ground)38%Ice stream/outlet glacier (ice front or ice wall)13%Rock5%Total100%Antarctica is divided in two by the Transantarctic Mountai

36、ns close to the neck between the Ross Sea and the Weddell Sea. The portion west of the Weddell Sea and east of the Ross Sea is called West Antarctica and the remainder East Antarctica, because they roughly correspond to the Western and Eastern Hemispheres relative to the Greenwich meridian.Elevation

37、 colored by relief heightAbout 98% of Antarctica is covered by the Antarctic ice sheet, a sheet of ice averaging at least 1.6km (1.0mi) thick. The continent has about 90% of the worlds ice (and thereby about 70% of the worlds fresh water). If all of this ice were melted, sea levels would rise about

38、60m (200ft).26 In most of the interior of the continent, precipitation is very low, down to 20mm (0.8in) per year; in a few blue ice areas precipitation is lower than mass loss by sublimation and so the local mass balance is negative. In the dry valleys the same effect occurs over a rock base, leadi

39、ng to a desiccated landscape.West Antarctica is covered by the West Antarctic Ice Sheet. The sheet has been of recent concern because of the real, if small, possibility of its collapse. If the sheet were to break down, ocean levels would rise by several metres in a relatively geologically short peri

40、od of time, perhaps a matter of centuries. Several Antarctic ice streams, which account for about 10% of the ice sheet, flow to one of the many Antarctic ice shelves.East Antarctica lies on the Indian Ocean side of the Transantarctic Mountains and comprises Coats Land, Queen Maud Land, Enderby Land,

41、 Mac. Robertson Land, Wilkes Land and Victoria Land. All but a small portion of this region lies within the Eastern Hemisphere. East Antarctica is largely covered by the East Antarctic Ice Sheet.Mount Erebus, an active volcano on Ross IslandVinson Massif, the highest peak in Antarctica at 4,892m (16

42、,050ft), is located in the Ellsworth Mountains. Antarctica contains many other mountains, both on the main continent and the surrounding islands. Located on Ross Island, Mount Erebus is the worlds southernmost active volcano. Another well-known volcano is found on Deception Island, which is famous f

43、or a giant eruption in 1970. Minor eruptions are frequent and lava flow has been observed in recent years. Other dormant volcanoes may potentially be active.27 In 2004, an underwater volcano was found in the Antarctic Peninsula by American and Canadian researchers. Recent evidence shows this unnamed

44、 volcano may be active.28Antarctica is home to more than 70 lakes that lie at the base of the continental ice sheet. Lake Vostok, discovered beneath Russias Vostok Station in 1996, is the largest of these subglacial lakes. It was once believed that the lake had been sealed off for 500,000 to one mil

45、lion years but a recent survey suggests that, every so often, there are large flows of water from one lake to another.29There is some evidence, in the form of ice cores drilled to about 400m (1,300ft) above the water line, that Lake Vostoks waters may contain microbial life. The frozen surface of th

46、e lake shares similarities with Jupiters moon Europa. If life is discovered in Lake Vostok, this would strengthen the argument for the possibility of life on Europa.30 On 7 February 2008, a NASA team embarked on a mission to Lake Untersee, searching for extremophiles in its highly alkaline waters. I

47、f found, these resilient creatures could further bolster the argument for extraterrestrial life in extremely cold, methane-rich environments.31GeologyMain article: Geology of AntarcticaSubglacial topography and bathymetry of bedrock underlying Antarctica ice sheetThe above map shows the subglacial t

48、opography of Antarctica. As indicated by the scale on left-hand side, blue represents portion of Antarctica lying below sea level. The other colors indicate Antarctic bedrock lying above sea level. Each color represents an interval of 2,500 feet in elevation. Map is not corrected for sea level rise

49、or isostatic rebound, which would occur if the Antarctic ice sheet completely melted to expose the bedrock surface.topographic map of Antarctica after removing the ice sheet and accounting for both isostatic rebound and sea level rise. Hence this map suggests what Antarctica may have looked like 35

50、million years ago, when the Earth was warm enough to prevent the formation of large-scale ice sheets in Antarctica.Geological history and paleontologyMore than 170million years ago, Antarctica was part of the supercontinent Gondwana. Over time, Gondwana gradually broke apart and Antarctica as we kno

51、w it today was formed around 25million years ago. Antarctica was not always cold, dry and covered in ice sheets. At a number of points in its long history it was farther north, experienced a tropical or temperate climate, was covered in forests, and inhabited by various ancient life-forms.Paleozoic

52、era (540250 Ma)During the Cambrian period, Gondwana had a mild climate. West Antarctica was partially in the Northern Hemisphere, and during this period large amounts of sandstones, limestones and shales were deposited. East Antarctica was at the equator, where sea floor invertebrates and trilobites

53、 flourished in the tropical seas. By the start of the Devonian period (416Ma), Gondwana was in more southern latitudes and the climate was cooler, though fossils of land plants are known from this time. Sand and silts were laid down in what is now the Ellsworth, Horlick and Pensacola Mountains. Glac

54、iation began at the end of the Devonian period (360Ma), as Gondwana became centered around the South Pole and the climate cooled, though flora remained. During the Permian period, the plant life became dominated by fern-like plants such as Glossopteris, which grew in swamps. Over time these swamps b

55、ecame deposits of coal in the Transantarctic Mountains. Towards the end of the Permian period, continued warming led to a dry, hot climate over much of Gondwana.32Mesozoic era (25065 Ma)As a result of continued warming, the polar ice caps melted and much of Gondwana became a desert. In Eastern Antar

56、ctica, the seed fern became established, and large amounts of sandstone and shale were laid down at this time. Synapsids, commonly known as mammal-like reptiles, were common in Antarctica during the Late Permian and Early Triassic and included forms such as Lystrosaurus. The Antarctic Peninsula bega

57、n to form during the Jurassic period (206146Ma), and islands gradually rose out of the ocean. Ginkgo trees and cycads were plentiful during this period. In West Antarctica, coniferous forests dominated through the entire Cretaceous period (14665Ma), though Southern beech began to take over at the en

58、d of this period. Ammonites were common in the seas around Antarctica, and dinosaurs were also present, though only three Antarctic dinosaur genera (Cryolophosaurus and Glacialisaurus, from the Hanson Formation,33 and Antarctopelta) have been described to date.34 It was during this period that Gondwana began to break up.Gondwanaland breakup (16023 Ma)The cooling of Antarctica occurred stepwise, as the continental spread changed the oceanic c