| Homepage | A sand dune is a pile of sand formed by the Eolian (wind) process, and a barchan dune is an arc-shaped sand ridge that has a slipface (the concave downwind slope) at about 32 degrees, an upwind side at about 15 degrees, and sometimes two horns that extend downwind. Barchan dunes migrate downwind and join others to form bigger dunes called megabarchans. In this picture an army of barchan dunes move along the plain and will later form megabarchans when they reach uphill or collide with other dunes. | Prev | Index | Next |
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