wave refraction

Distortion of waves as they reach the coast, due to variations in the depth of the water and shape of the coastline. It is particularly evident where there are headlands and bays.

The bending of a wave crest as it approaches a headland concentrates the energy of the wave in the direction of that headland, and increases its power of erosion. By contrast, the bending that a wave crest experiences when it moves into a bay causes its energy to be dissipated away from the direction of the shore. As a result the wave loses its erosive power and becomes more likely to deposit sediment on the shore.