A crescent-shaped sand dune, in which the horns point downwind in the direction of dune migration. Barchans are a type of transverse dune that tends to form where either sand transport rates are high and/or sand supply is limited; thus, they frequently occur on the margins of sand seas and migrate over nonsandy surfaces. Barchan dunes are not necessarily a very common type of dune, but the frequent simplicity of form has made them the source of investigations into aeolian sand transport on dune forms. (See dune.)
A gently sloping, moving sand dune having a crescent shape with horns pointing downwind and lying transverse to the direction of the...
pronunciation (1888) : a moving crescent-shaped sand dune
A large-scale accumulation of aeolian sand dunes geographically distinct from other sand fields but smaller than a sand sea.