A barchan or barkhan dune is a dune in the shape of the crown. It's a dune in the shape of a middle crescent. The term for crescent-shaped sand dunes in Turkestan and other inland desert regions was introduced in 1881 by Russian naturalist Alexander von Middendorf.
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A barhan or barkhan dune is a dune in the shape of a crown. The term for crescent-shaped sand dunes in Turkestan and other inland desert regions was introduced in 1881 by Russian naturalist Alexander von Middendorf. Barchans face the wind, which appear convex and are mainly created from one direction by wind.
Barchans are convex in the direction of the wind, with crescent horns pointing downwind and marking sand's lateral development. These dunes are slightly asymmetrical in cross sections, with a moderate path to the wind and a steeper path, known as the slippery face, which faces the wind. At the base measured on the perpendicular side by the wind, Barchans can be 9–30 m (30–100 feet) tall and 370 m (1,214 feet) high.
As a consequence of wind erosion and deposition, they move progressively with the wind. The migration rate varies from 1 to 100 metres annually. Barchans are typically created as isolated groupings of dunes and can form chains that stretch over the plain towards the wind.
Near to the Indo-Pakistan frontier, barchans (crease dunes) cover larger areas but longitudinal dunes. There are dunes in Jaisalmer.
Inland desert regions such as Turkistan where the name came from are typical of the Barchans accessible. The revival of the word in scientific literature by Alexander von Middendorf is credited in 1881.