UPSC Prelims 2011 · GS Paper I
Question 97: Geography
The Brahmaputra, Irrawady and Mekong rivers originate in Tibet and flow through narrow and parallel mountain ranges in their upper reaches. Of these rivers, Brahmaputra makes a "U" turn in its course to flow into India. This "U" turn is due to
AnswerThe answer is (b).
The Brahmaputra, called the Tsangpo in Tibet, flows east along the Himalaya and then turns sharply around the peak of Namcha Barwa to enter Arunachal Pradesh as the Siang. This hairpin lies at the eastern end of the Himalaya, where the ranges bend sharply southwards. That sharp bend of the young Himalaya, a syntaxial bend, explains the U-turn.
Why each option is right or wrong
- (a) General uplift of the folded Himalaya does not by itself explain the sharp U-turn.
- (b) Right: the syntaxial bend of the young Himalaya.
- (c) A general tectonic disturbance is vague and not the specific cause.
- (d) Only (b) gives the specific cause, so combining it with (a) fails.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2011, General Studies Paper I, Series A. The paper on upsc.gov.in.