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UPSC Prelims 2026 GS Paper 1, question 11

Topic: Indian geography

Q11

Consider the following assertion :

In the Pleistocene period either the Yamuna once flowed into the Indus, or the Sutlej flowed into the Yamuna and one major tributary of either had shifted from the Ganga to the Indus or vice versa.

Which of the following is/are the basis of the above assertion ?

  1. The Nadi-Sukta of the Rigveda

  2. The explorations of the Sutlej and the Yamuna by Robert Bruce Foote

  3. The presence of the same species of dolphins in both the Indus and the Ganga river systems

Select the answer using the code given below :

  1. (a) 1 only
  2. (b) 2 only
  3. (c) 1 and 2
  4. (d) 3Correct answer

Solution.

Answer: (d) 3

  1. Items 1 and 2 are incorrect: the Nadi-Sukta of the Rigveda (10.75) enumerates contemporary Vedic rivers, and Robert Bruce Foote was a pioneer of Indian prehistoric stone-tool archaeology rather than Pleistocene Sutlej-Yamuna river capture.
  2. Item 3 is correct: the presence of the same genus/species of obligate freshwater river dolphins (Platanista) in both the Indus and Ganga-Brahmaputra river systems provides classic zoogeographical proof that the two drainage systems were hydrologically connected during the Pleistocene.