Question

Q. Consider the following:

Assertion (A): The Narmada and the Tapi are west flowing rivers and drain into the Arabian sea.

Reason (R): Tilting of the peninsular block from southeast to the northwest direction.

Select the correct answer using the codes given below:

• A.
  Both (A) and (R) are true, and (R) is the correct explanation of (A).
• B.
  (A) is true, but (R) is false.
• C.
  Both (A) and (R) are true, but (R) is not the correct explanation of (A)
• D.
  (A) is false, but (R) is true.

Answer 1

The correct option is B

(A) is true, but (R) is false.
Explanation:

Assertion (A) is correct: The Peninsular drainage system is governed by many factors. Amongst them is the slight tilting of the peninsular block from northwest to southeast direction which gives the orientation to the entire drainage system towards Bay of Bengal. That is why many rivers like Krishna, Godavari, Cauvery drain towards Bay of Bengal.

Reason (R) is incorrect: But the Narmada and the Tapi are exceptions as they flow west, towards the Arabian sea. Direction of their flow is not governed by the tilting of the peninsular block as they flow through rift valleys which are formed due to multiple subsidence and upliftment of the Earth’s surfaces. Narmada's course is defined by the Son-Narmada Fault (NSF), which divides the Indian landmass into the peninsular block of the south and a northern foreland block. Moreover, the Peninsular block is tilted slightly eastwards.