Other forms: barchans
A barchan is a crescent-shaped sand dune with "horns" that point in the direction the wind is blowing. Over time, barchans migrate across sandy desert surfaces.
The word barchan comes from the Kazakh language of Central Asia, a region with large areas of desert containing many barchans. A barchan forms in areas with a steady wind and limited sand. The wind pushes the sand up a gentle windward slope and over the crest, where it avalanches down the dune's steep slip, or leeward, face. The wind moves faster around the dune's edges, creating the crescent shape. Barchans are not stationary; they move, either alone or in long "trains," up to 100 feet per year.