UGC NET Geography UPSC

Indus and Brahmaputra are examples of—

(A) Subsequent drainage

(B) Superimposed drainage

(D) Consequent drainage

The correct answer is (C) Antecedent drainage.

Let's explain all the options:

(A) Subsequent drainage: Subsequent drainage refers to a river system that develops and follows the slope of the land that has been formed by tectonic forces or other geomorphic processes. It occurs after the formation of the land and is not related to the initial development of the landscape. It is not applicable to the Indus and Brahmaputra rivers.

(B) Superimposed drainage: Superimposed drainage occurs when a river cuts through existing rock structures and maintains its course regardless of the underlying geological features. This type of drainage develops over previously formed landscapes and is often influenced by erosion-resistant rock layers. It is not applicable to the Indus and Brahmaputra rivers.

(C) Antecedent drainage: Antecedent drainage occurs when a river system develops in a region before the surrounding landmass undergoes uplift or tectonic changes. The river maintains its course despite the subsequent changes in the landscape caused by geological forces. This is the correct option for the Indus and Brahmaputra rivers. These rivers existed before the Himalayan mountain range was uplifted and have maintained their courses by eroding through the rising mountains.

(D) Consequent drainage: Consequent drainage develops in response to the existing topography or landform patterns. It occurs as a result of the initial structure and relief of the area. This option is not applicable to the Indus and Brahmaputra rivers because their courses were established before the formation of the Himalayas.

Therefore, the correct answer is (C) Antecedent drainage, as the Indus and Brahmaputra rivers existed before the formation of the Himalayas and have maintained their courses by eroding through the rising mountains.

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