The Tibetan Plateau is so high it helps steer India's monsoon
At about 5,000 metres above sea level and roughly 2.5 million square kilometres across, the Tibetan Plateau is the largest and highest tableland on Earth. It is still rising as two tectonic plates collide, and it stands tall enough to reverse atmospheric circulation and help drive the Indian monsoon southward.
A plateau, also known as a high plain or tableland, is flat highland raised sharply above its surroundings on at least one side, often edged by steep escarpments. Some have only a small flat summit; others stretch for enormous distances. Geographers classify them by what surrounds them. Intermontane plateaus, the highest and broadest, are hemmed in by fold mountains, as the Altiplano is between two Andean ranges. Piedmont plateaus have mountains on one side and plain or sea on the other, and continental plateaus rise away from mountains entirely.
Several forces can build one. Magma welling up from the mantle can swell the ground until wide slabs of rock are lifted. Lava pouring out of cracks in the crust can stack up layer upon layer, which is how the Antrim Plateau in Northern Ireland and the Columbia Plateau in the United States formed. Tectonic uplift produces large plateaus of fairly even height, such as the Meseta Central of Iberia. Erosion works too: glaciers and rivers can grind mountains down, and a heavily dissected plateau, cut by narrow valleys, can look like the Scottish Highlands.
Africa's highest plateau is the Ethiopian Highlands, nicknamed the Roof of Africa, where little ground falls below 1,500 metres and summits reach about 4,556 metres. South Africa's Highveld, lying between roughly 1,500 and 2,100 metres, holds some of the country's biggest cities. The Deosai Plains in Pakistan, averaging over 4,100 metres, are considered the world's second-highest plateau.
The strangest may be the Antarctic Plateau, home to the South Pole and the Amundsen-Scott station. It has no known mountains, just ice about 3,000 metres thick creeping slowly towards the coast through vast glaciers. The ice is so heavy that large parts of the land beneath lie below sea level, though it would rebound if the ice melted.
Source: Plateau
