UPSC Previous Year Question | Prelims GS | 2026

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. 1 only
  2. 2 only
  3. 1 and 2
  4. 3

Answer

Correct Answer

3

Explanation

The assertion concerns a possible ancient hydrological connection between the Indus and Ganga river systems. The presence of the same species of river dolphins in the two systems has historically been used as evidence suggesting that the river systems may once have been connected. The Nadi-Sukta is a textual enumeration of rivers and does not by itself establish a Pleistocene drainage shift. Robert Bruce Foote's explorations are not the basis intended by the question.

Topics: geography, indian rivers, paleogeography, river systems