<P> Constructive waves move material up the beach while destructive waves move the material down the beach . During seasons when destructive waves are prevalent, the shallows will carry an increased load of sediment and organic matter in suspension . </P> <P> On sandy beaches, the turbulent backwash of destructive waves removes material forming a gently sloping beach . On pebble and shingle beaches the swash is dissipated more quickly because the large particle size allows greater percolation, thereby reducing the power of the backwash, and the beach remains steep . </P> <P> Compacted fine sediments will form a smooth beach surface that resists wind and water erosion . During hot calm seasons, a crust may form on the surface of ocean beaches as the heat of the sun evaporates the water leaving the salt which crystallises around the sand particles . This crust forms an additional protective layer that resists wind erosion unless disturbed by animals, or dissolved by the advancing tide . </P> <P> Cusps and horns form where incoming waves divide, depositing sand as horns and scouring out sand to form cusps . This forms the uneven face on some sand shorelines . </P>

Why is there more sand at the northern end of most beaches on the east coast