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A plateau is an extensive landform with a plain crest area and is sufficiently high at least on one side of its land or water surroundings.
Its surface is usually plain because of its horizontal layers but if the layers are inclined, the surface becomes plain because of erosion. For example, the sedimentary rock layer of Colorado plateau is plain while those of the Appalachian plateau are inclined yet the crest area is plain because of erosion.
Classification of Plateaus. It is not simple to classify plateaus. Plateaus can be classified in many ways. The classification depends upon the situation, condition, method of formation etc.
(A) 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.
(i) 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.
(ii) 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 is one such a Plateau.
(iii) 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 plateaus formed by erosion are the plateaus of Greenland and Antarctica..
(iv) Plateaus formed 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.
(B) 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.
(i) 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.
(ii) 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.
(iii) 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, the plateaus of Spain and Australia are some of the examples of this type of plateaus.
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