What are the two factors that influence the composition of beach material

Two things that determine or influence the composition or the size of sand on beaches. The energy or height of the waves, and the size of material furnished to the beach. The higher the average waves on a beach, the coarser the sand. This is because higher waves tend to move the smaller grains offshore. The difference in size is due to winds that generally pick up and carry finer grains and leave the heavier, larger sand grains behind.