RAS question
Alluvial soils are most extensively found in:
Correct answer: (D) Indo-Gangetic Plain.
Alluvial soils are most extensively found in the Indo-Gangetic Plain, where river deposition has created a fertile and agriculturally important plain.
Explanation
Alluvial soil is the right match for the Indo-Gangetic Plain because this plain is built by river deposition. NCERT explains that the Northern Plain was formed by the Indus, Ganga and Brahmaputra river systems with their tributaries, and that the plain is made of alluvial soil. This fits the standard soil-distribution point in the question: alluvial soils cover about 40% of India's area and occur mainly in the Indo-Gangetic Plain, river deltas and coastal plains. Their fertility and agricultural importance also follow from the same setting, since NCERT links the rich soil cover, adequate water supply and favourable climate of the Northern Plain with high agricultural productivity.
Why the other options are wrong
- (A) The Deccan Plateau is not the most extensive alluvial-soil region because it is mainly associated with black soil, not the broad alluvial deposits of the northern plains.
- (B) The Chota Nagpur Plateau is not the answer because it is associated with red and laterite soils rather than the extensive alluvial cover of the Indo-Gangetic Plain.
- (C) The Western Ghats are not the main alluvial-soil belt because they are associated with laterite soils, unlike the river-deposited plains.
Concept
This tests the RAS geography concept of Indian soil distribution across physiographic regions. It recurs because soil type, river deposition and agricultural productivity are frequently linked in questions on Indian physical geography.