Which of the following statements regarding Barchan is/are correct ? 1. It is a crescent shaped mound of sand, which is deposited by the wind blowing constantly from one direction in a desert. 2. The windward side has a convex steep slope with maximum height at the centre. 3. Two ends of Barchan are called horns and point opposite to the direction the wind blows. Select the answer using the code given below :
- A.1 only
- B.1 and 2 only
- C.2 and 3 only
- D.1, 2 and 3
Correct answer
Explanation
The correct answer is A, 1 only. A barchan is a crescent-shaped sand dune built by wind from one steady direction, but its windward slope is gentle and its horns point downwind.
Barchans form in deserts where the wind blows constantly from one direction and the supply of sand is limited, as in parts of the Sahara and the Thar. Wind pushes sand up the long, gentle, convex windward slope and drops it over the crest on the other side, giving a short, steep, concave leeward slope called the slip face. The edges of the dune move faster than the thicker centre, so the two ends, called horns, stretch ahead in the direction the wind blows.
B is wrong because statement 2 is false: the windward side is gentle, and the steep side is the leeward slip face.
C is wrong because both statements 2 and 3 are false; the horns point downwind, not against the wind.
D is wrong because only statement 1 is correct.
Exam tip: barchan has a gentle windward slope, a steep leeward slip face, and horns pointing downwind.
Practice Questions
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2. Imphal
3. Agartala
4. Aizawl
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- B.2-1-4-3
- C.1-4-3-2
- D.4-3-2-1
Show answer
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- A.300 km
- B.5 km
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