RAS question
The Indo-Gangetic Plain was formed by:
Correct answer: (C) Alluvial deposits brought by rivers from the Himalayas.
The Indo-Gangetic Plain was formed by alluvial deposits brought by the Indus, Ganga and Brahmaputra river systems and their tributaries from the Himalayas.
Explanation
The Indo-Gangetic Plain is an alluvial plain, not a landform created by ice, lava or uplift alone. The Northern Plain was formed by the interplay of the Indus, Ganga and Brahmaputra river systems with their tributaries. Alluvium was deposited in a vast basin at the foothills of the Himalayas over millions of years, producing a fertile plain. Sediments carried by these river systems accumulated across a long east-west belt, about 2,400 km in length and 150-300 km wide, making it one of the world's most fertile regions.
Why the other options are wrong
- (A) Glacial erosion removes and scours material, whereas the plain is a depositional alluvial plain made by river-borne silt and alluvium.
- (B) Volcanic activity would point to lava or ash-derived landforms, but this plain consists of alluvial soil deposited by major river systems.
- (D) Tectonic uplift raises land, while this plain was formed through the long-term deposition of alluvium in a basin at the Himalayan foothills.
Concept
This tests the geomorphology of India's Northern Plain, especially the distinction between erosional, volcanic, tectonic and fluvial depositional processes. It recurs in RAS because river systems, alluvial soils and agricultural productivity are core links between physical geography and Indian economy questions.