Plains

Plains

Notes

A plain is a low-lying, flat or gently undulating land, usually below about 200 m in elevation. Plains are the most productive and densely populated landforms, supporting agriculture, industry and cities.

Types by origin

• Structural plains: formed by the uplift of a sea floor or by tectonic movement (coastal and interior plains such as the Great Plains of North America).
• Depositional plains: the most common.
  • Alluvial plains: deposited by rivers (Indo-Gangetic plain, Mesopotamian plain, Hwang Ho plain).
  • Flood plains and deltaic plains: the Ganga-Brahmaputra delta (the largest delta), Nile delta.
  • Lacustrine plains: from dried lake beds (the Kashmir Valley, parts of the Netherlands).
  • Loess plains: wind-blown dust (northern China).
  • Glacial (outwash and till) plains: northern Europe and Canada.
• Erosional plains: worn down by rivers, wind or ice. A peneplain is the last stage of the cycle of erosion (W.M. Davis). Others: karst plains, glacial scoured plains.

Grasslands (temperate plains)

• Prairies (North America), Pampas (Argentina), Steppes (Eurasia), Veld (South Africa), Downs (Australia), Canterbury Plains (New Zealand), Llanos (Orinoco, Venezuela), Campos (Brazil).

Plains of India

• Northern (Indo-Gangetic-Brahmaputra) plains: divided into Bhabar (pebbly belt at the foot of the Shiwaliks), Terai (marshy, damp belt), Bhangar (old alluvium, above flood level, with kankar nodules) and Khadar (new alluvium, renewed by floods, more fertile). Sub-divisions: Punjab plains, Ganga plain, Brahmaputra plain.
• Coastal plains: the Eastern plain (Coromandel and Northern Circars; deltas of the Mahanadi, Godavari, Krishna and Kaveri) is wide; the Western plain (Konkan, Kannad, Malabar) is narrow.
• Rajasthan plain (Thar, Marusthali and Bagar).

Importance: fertile soil for agriculture, high population density, transport networks, industries and urbanisation.

Key Points

• Plains: low and flat, below about 200 m; mostly depositional (alluvial).
• Bhangar is old alluvium; Khadar is new alluvium.
• Peneplain is the end-stage of erosion.
• Pampas (Argentina), Prairies (North America), Steppes (Eurasia), Veld (South Africa).
• The Ganga-Brahmaputra delta is the largest delta.

MCQs

Q1. The old alluvium of the northern plains of India is called:

(a) Khadar
(b) Bhangar
(c) Terai
(d) Bhabar
Ans: (b).

Q2. The temperate grasslands of Argentina are known as:

(a) Prairies
(b) Steppes
(c) Pampas
(d) Veld
Ans: (c).

Q3. The final stage of the cycle of erosion, a nearly flat erosional plain, is called a:

(a) Delta
(b) Peneplain
(c) Loess plain
(d) Playa
Ans: (b).