World Geography : Classification and Significance of Plains. ( UPSC )

  • A plain is nothing but a low-lying relatively flat land surface with very gentle slope and minimum local relief.
  • About 55% of the earth’s land surface is occupied by plains.
World Geography : Classification of Plain. ( UPSC )
World Geography : Classification of Plain. ( UPSC )

Classification of Plains

World Geography : Classification of Plain. ( UPSC )
World Geography : Classification of Plain. ( UPSC )

On the basis of their mode of formation, plains can be classified as:

  1. Structural Plains
  2. Erosional Plains
  3. Depositional Plains
World Geography : Classification of Plain. ( UPSC )
World Geography : Classification of Plain. ( UPSC )
1. Structural Plain
  • These plains are mainly formed by the upliftment of a part of the sea floor or continental shelf.
  • They are located on the borders of almost all the major continents.
  • The structural plains may also be formed by the subsidence of areas.
  • Examples – Russian Platforms, Great plains of USA & Central lowlands of Australia.
2. Erosional Plain
  • The erosional forces remove the disparities of the land by erosion and convert the land area into a flat and shapeless plain.

Erosion by the River

  • Erode the high landmass and converts it into peniplain.
  • The resistant rocks found everywhere are called Monadnac.

Erosion by Glacier

  • Glacier erosion converts the highland section into a flat but relief plain.

Erosion by Wind

  • Rocks in arid and semi-arid regions get disintegrated by weathering and get converted into particles.
  • The winds carry these particles with them, due to which the rocky part gets eroded and turns into a plain.
  • The resistant rocks found are called Inselberg.
  • The plain formed on the mountain slopes is called pediplain.

Karst Plain

  • Conversion of lime rocks into plain due to erosion by underground water.
3. Depositional Plains
  • Various factors of erosion form the plains through the deposition process.

1. Alluvial Cone

  • Rivers descending from the hill slopes form alluvial cones / alluvial fans on the foothills.
  • This ground, made up of a pile of big pieces, is called Bhabar.

2. Flood Plain

  • During floods, rivers flow over the embankments and form a flood plain, which has alluvial/trembling or alluvial soil.

3. Delta Plains

  • When the rivers fall into the oceans, due to the slowdown in their velocity, they left deposition near the mouth, a triangular flat plain is formed which is called the delta plain.

4. Lacustrine Plain (Lake Plain)

  • Plains formed due to deposition by rivers falling into lakes or drying up of lakes.

5. Lava Plains

  • Plains formed by liquid lava emanating from a volcanic eruption.

6. Loess Plains

  • By depositing sand particles wind forms the plain.

The Economic Significance of Plains

1. Fertile Soil
  • The plains generally have deep and fertile soil.
  • As they have a flat surface, the means of irrigation can be easily developed.
  • That is why plains are called as the ‘Food baskets of the world’.
2. The Growth of Industries
  • The rich agricultural resources, especially of alluvial plains, have helped in the growth of agro-based industries.
  • Since the plains are thickly populated, plenty of labor is available for the intense cultivation and for supplying the workforce for the industries.
3. Expansion of means of Transportation
  • The flat surface of plains favours the building of roads, airports and laying down railway lines.
4. Centres of Civilizations
  • Plains are centres of many civilizations.
5. Setting up of Cities and Towns
  • Easy means of transportation on land and the growth of agriculture and industries in plains have resulted in the setting up and expansion of cities and towns.

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