Sand dunes are formed by Aeolian processes. Aeolian processes basically concern the action of the winds and mainly, the wind's capability to mould and shape the surface of the Earth. Sand bodies which are formed due to the deposition by wind are of three types, sand sheets, ripples and dunes.
Dunes are formed when sand that is blown by winds moves upwards, to a side of a body by way of saltation or creep. Sand gets collected at the edge, on the top of the slip face. When the build up of sand at the edge becomes more than the angle of repose, a little avalanche of sand grains slides downwards on the slip face. In this way, grain by grain, the sand dune is formed and moves forward in the process.
Dunes are formed when sand that is blown by winds moves upwards, to a side of a body by way of saltation or creep. Sand gets collected at the edge, on the top of the slip face. When the build up of sand at the edge becomes more than the angle of repose, a little avalanche of sand grains slides downwards on the slip face. In this way, grain by grain, the sand dune is formed and moves forward in the process.
