Asked in Sand Dunes
How do sand dunes form?
January 24, 2018 2:22AM
Dunes are formed when wind and waves transport sand onto the beach. The ultimate source of the sand is often glacial till that resides offshore, or is eroded from nearby cliffs by waves, and transported along the shoreline by long shore currents (see coastal sediment processes). Rivers can also transport sand to the coast from inland deposits. Waves wash this sand up on the beach, and also remove it during storms.
Sand particles can be carried away by strong winds. These particles eventually fall when the wind if not strong enough to keep them aloft. Sand dunes form in areas where wind routine occurs. The dunes start when an obstruction of some sort acts as a barrier to block the wind. The wind slows down when it hits the barrier, allowing the sand particle to fall to the ground Eventually, the obstruction, which may be a stump or rock, will become completely buried by sand. The dune continues to grow by the same process as more and more sand particles are released by the winds that slow down when they hit the dune. Interestingly, dunes move slowly. This occurs when the wind lifts sand up on the windward side and the sand falls down on the leeward side.