Feb 24 (Reuters) - Jagged mountains the size of the Alps have been found under Antarctica's ice, giving new clues about its vast ice sheet.

Here are some detailsabout the frozen continent:

GEOGRAPHY

-- If Antarctica were a country, it would be the second largest in the world after Russia, at 14.2 million sq km (5.5 million sq miles), including its floating ice shelves.

-- Antarctica has 30 million cubic km of ice -- around 90 per cent of the fresh water on Earth.

-- About 2 percent of the land mass is ice-free barren rock.

-- The average thickness of the ice sheet is more than a mile (1.6 km).

-- Floating ice shelves made up of ice and snow between 100 and 300 metres thick jut out from about half of the coastline, and account for 11 percent of Antarctica's area.

-- The United States has a large base and airstrip at the South Pole, named the Amundsen-Scott Base after two of the most important early 20th-century explorers who helped bring the continent to world attention.

GLOBAL WARMING

-- Antarctica is of particular significance to the international community because of its impact on global climate and sea conditions. If the ice sheet covering the continent ever all melted, world sea levels would rise by about 57 metres.

-- The Antarctic Peninsula, the most northerly part of the continent, opposite South America, has warmed by about 3 degrees Celsius (5.4 Fahrenheit) in the past 50 years. Most of the continent shows no sign of warming, though.

-- Several of the northernmost ice shelves have collapsed in recent years, which many scientists link to global warming.

Sources: Reuters/www.britannica.com (Writing by David Cutler, London Editorial Reference Unit; Editing by Kevin Liffey)

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