Waves and their erosive power

A wave train is a sequence of waves. The size of these waves is determined by the velocity and duration of the wind, and the fetch, or distance of interrupted wind.
These waves cause erosion in two ways. Firstly the waves have hydraulic action, which is the power of water alone. Secondly, the combination of the salty water and the abrasive power of the waves pushing sediments together causes corrasion.Together these erosive processes flatten coastlines and form beaches.