Geography of Antarctica


Geography of Antarctica

The geography of Antarctica is dominated by its south polar location and, thus, by ice. The Antarctic continent, located in the Earth's southern hemisphere, is centered asymmetrically around the South Pole and largely south of the Antarctic Circle. It is surrounded by the southern waters of the World Ocean – alternatively (depending on source), it is washed by the Southern (or Antarctic) Ocean or the southern Pacific, Atlantic, and Indian Oceans. With an area of more than 14 million km², it is the fifth-largest continent and about 1.3 times larger than Europe.

Some 98% of Antarctica is covered by the Antarctic ice sheet, the world's largest ice sheet and also its largest reservoir of fresh water. Averaging at least 1.6 km thick, the ice is so massive that it has depressed the continental bedrock in some areas more than 2.5 km below sea level; subglacial lakes of liquid water also occur (e.g., Lake Vostok). Ice shelves and rises populate the ice sheet on the periphery. Only about 2% of the continent is uncovered by ice.

Physically, Antarctica is divided in two by mountains close to the neck between the Ross Sea and the Weddell Sea. Western Antarctica and Eastern Antarctica correspond roughly to the eastern and western hemispheres relative to the Greenwich meridian. This usage has been regarded as Eurocentric by some, and the alternative terms Lesser Antarctica and Greater Antarctica (respectively) are sometimes preferred.

Western Antarctica is covered by the West Antarctic Ice Sheet. There has been some concern about this ice sheet, because there is a small chance that it will collapse. If it does, ocean levels would rise by a few metres in a very short period of time.

Volcanoes

There are four volcanoes on the mainland of Antarctica that areconsidered to be active on the basis of observed fumarolic activity or"recent" tephra deposits:
Mount Melbourne (2,730 m) (74°21'S., 164°42'E.), a stratovolcano;
Mount Berlin (3,500 m) (76°03'S., 135°52'W.), a stratovolcano; Mount Kauffman (2,365 m) (75°37'S., 132°25'W.), a stratovolcano; and
Mount Hampton (3,325 m) (76°29'S., 125°48'W.), a volcanic caldera. Several volcanoes on offshore islands have records of historic activity.
Mount Erebus (3,795 m), a stratovolcano on
Ross Island with 10 known eruptions and 1 suspected eruption.On the opposite side of the continent,
Deception Island(62°57'S., 60°38'W.), a volcanic caldera with 10 knownand 4 suspected eruptions, have been the most active.
Buckle Island in the Balleny Islands (66°50'S., 163°12'E.),
Penguin Island (62°06'S., 57°54'W.), Paulet Island (63°35'S., 55°47'W.), and Lindenberg Island (64°55'S., 59°40'W.) are also considered to be active.

ee also

* List of antarctic and sub-antarctic islands
* Geology of Antarctica

External links

* [http://sd-www.jhuapl.edu/FlareGenesis/Antarctica/1999/pictures/antarctica_pol_map.jpgPolitical Claims Map]
* [http://terraweb.wr.usgs.gov/TRS/projects/Antarctica/AVHRR.html USGS TerraWeb: Satellite Image Map of Antarctica]
* [http://erg.usgs.gov/isb/pubs/factsheets/fs05101.html United States Antarctic Resource Center (USARC)]
* [http://www.antarctica.ac.uk/aedc/bedmap/ BEDMAP]
* [http://www.add.scar.org/ Antarctic Digital Database (Topographic data for Antarctica, including web map browser)]
* [http://lima.usgs.gov/ Landsat Image Mosaic of Antarctica (LIMA; USGS web pages)]
* [http://lima.nasa.gov/ Landsat Image Mosaic of Antarctica (LIMA; NASA web pages)]


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