Consider the following statements about Barchans : 1. These landforms are found in Thar desert in India. 2. The windward side has concave slope with maximum height at the centre. 3. Two ends of the barchan are called horns. Which of the statements given above is/are correct ?
- A.1 and 2 only
- B.2 and 3 only
- C.1 and 3 only
- D.3 only
Correct answer
Explanation
The correct answer is C, 1 and 3 only. Barchans are common in the Thar and their two tips are called horns, but the windward side of a barchan is a gentle convex slope, not a concave one.
A barchan is a crescent-shaped sand dune formed where the wind blows steadily from one direction and the sand supply is limited. Sand is pushed up the long, gentle, convex windward slope and slides down the short, steep leeward face, called the slip face, which is concave. The two tips, or horns, point downwind because the thinner sand at the edges moves faster than the high centre. Barchans are found in western Rajasthan, especially around Jaisalmer, and in deserts such as the Sahara, and they slowly migrate in the wind's direction.
A is wrong because statement 2 is false and statement 3 is left out. B is wrong because it includes the false statement 2 and leaves out statement 1. D is wrong because statement 1 is also correct.
Exam tip: barchan = crescent dune; gentle convex windward side, steep concave slip face, horns point downwind.
Practice Questions
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