RAS question
Barchan sand dunes are commonly found in which part of Rajasthan?
Correct answer: (A) Western Thar Desert.
Barchan, or crescent-shaped, sand dunes are commonly found in the western Thar Desert of Rajasthan.
Explanation
Barchans are crescent-shaped sand dunes formed by wind action in arid regions. In Rajasthan, the relevant setting is the Western Sandy Plain, whose western portion is identified by Rajasthan Forest Department, A Manual for Dryland Afforestation and Management, as the Thar Desert. The Sandy Arid Plain, including Bikaner, Barmer, Jaisalmer, Jodhpur, Nagaur and Churu, is Marusthali, where sand dunes are a common feature and crescent-shaped dunes are one of the main dune types. Barchans occur in the western Thar Desert, especially around Jaisalmer, Barmer and Jodhpur, rather than in Rajasthan's plateau, hill or fertile plain regions.
Why the other options are wrong
- (B) Mewar is in southern Rajasthan and is hilly terrain, so it does not match the arid, windblown sandy setting in which barchan dunes form.
- (C) The eastern plains are fertile agricultural land, not the desert landscape associated with crescent-shaped sand dunes.
- (D) Hadoti Plateau lies in southeastern Rajasthan, whereas dune-rich sandy terrain lies in the western sandy and Thar Desert belt.
Concept
This tests Rajasthan geomorphology, especially the link between aeolian landforms and the Thar Desert. It recurs in RAS because dune types, arid-region processes and regional physiographic divisions are standard Rajasthan geography themes.