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PLATEAU

By : brainykey   May 25, 2014
A plateau is a large highland area of fairly level land separated from surrounding land by steep slopes. Some plateaus, like the plateau of Tibet, lie between mountain ranges. Others are higher than surrounding land. Plateaus are widespread, and together with enclosed basins they cover about 45 per cent of the Earth’s land surface.

Some plateaus, such as the Deccan of India and the Columbia Plateau of the United State are basaltic and were formed a the result of many lava flows covering hundreds of thousands of square kilometers that built up the land surface. Others are the result of upward folding; still others have been left elevated by the erosion of nearby lands. Plateaus, like all elevated regions, are subject to erosion, which removes great amounts of the upland surface. Low plateaus are often farming regions, while high plateaus are usually suitable for livestock grazing. Many of the world’s high plateaus are deserts. Other plateaus are the Colorado Plateau of the United States, the Bolivian plateau in South America, and the plateaus of Anatolia, Arabia, Iran and the Tibet region of China and the Canadian Shield or Laurentian Plateau, a U-shaped region of ancient rock, the nucleus of North America, stretching north from the Great Lakes to the Arctic Ocean. Covering more than half of Canada, it also includes most of Greenland and extends into the United States as the Adirondack Mountains and the Superior High-Lands. The first part of North America to be elevated above sea level, it has stayed almost wholly untouched by many encroachments of the sea upon the continent.

Classification based upon the methods of Formation – The plateaus are formed by many methods. The emission from the earth, water glacier, wind, etc., form plateaus.

  • Plateaus formed by Lava – Lava comes out of the surface of the earth through zones of weakness. This lava spreads in the surroundings areas and forms plateau. The southern plateau of India is an extensive lava plateau. Its area is 13 million sq. km. The plateau of Columbia has an area of 250,000 sq. km.
  • Plateaus formed by Running Water – High Mountains are eroded down by rivers. Plateau is formed as a landform in the last part of the cycle of erosion. Endogenetic force makes peneplain and plateaus. Brazil ii one such a Plateau.
  • Plateaus formed by Glaciers – Glaciers also do erosional and depositional work. Hence, glaciers form mountains in two ways:- (a) by deposition and (b) by erosion. The Russian plateau and the plateau of Finland are examples of plateaus formed by deposition. Among the plateau formed by erosion are the plateaus of Greenland and Antarctica.

 

  • Plateaus forrned by Wind  – When winds blow from a desert in a certain direction fine dust particles along with the winds reach far-off places. For example, the western winds coming from the Gobi desert have built up the loess plateau of China. The Potwar plateau of the district of Rawalpindi in Pakistan was built up in this way.

The Classification of plateau according to Situation – The plateaus are also classified according to their situations. Some plateaus are surrounded by mountains, others piedmont and continental.

  • Intermontanne plateau – These plateaus extend along with mountains and are known as the highest plateaus of the world. The plateaus of Bolivia and Tibet belong to this type. Other similar examples are the plateaus of Peru and of Mexico.

 

  • Piedmont plateaus – These plateaus extend along with mountains. One side of the plateaus is mountain while the other side has a. plain or a sea. It appears that these plateaus rose with the mountains under pressure of endogenetic forces. Examples of such plateaus are those of Colorado  (N. America), Patagonia (South America), etc.

 

  • Continental plateaus  – These plateaus are away from the mountains. They rise abruptly from the plains of seas. Some scholars think that these plateaus are created by the rise of a plain area under endogenetic forces. Sometimes the emission of lava and its spread close by form these plateaus. The Deccan plateau of India, the Arab plateau, plateaus of Spain and Australia are some of the examples of this type of plateaus.
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