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UPSC Prelims 1979 · Indian Geography · Rivers, Lakes and Dams
The oldest mountains are
- (a) Himalayas
- (b) Aravalis
- (c) Satpura
- (d) Vindhyas
Show the answer and explanation
Answer: (b) Aravalis
The Aravallis are among the oldest fold mountains in the world.
The idea
An old mountain belt can survive after prolonged erosion has reduced its height. A tall, sharply rising range may be geologically young. The deciding idea is the age of mountain formation, not present height or the age of an individual rock.
Ancient crust is folded and uplifted → A mountain belt forms → Weathering breaks exposed rock → Rivers and wind remove material → Long erosion lowers the relief → Remnant ridges preserve the old belt
Why the others are wrong
(a) The Himalaya is the youngest.
(c) The Satpura is old but younger than the Aravallis.
(d) The Vindhyas are younger than the Aravallis.
Also know
Guru Shikhar at Mount Abu is a high point of the Aravalli system. The Delhi Ridge is its north-eastern continuation. Himalaya is a young fold mountain system, while the Vindhyan region contains extensive old sedimentary rocks; old rocks alone do not make every upland an old fold mountain.
🔒 Aravalli: oldest fold mountains of India (Precambrian).
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