Beach erosion
Coastal erosion is a term for the removal of beaches or dunes  by waves, tidal currents, wave currents, or drainage.  Waves, caused by storms and wind cause coastal erosion. On rocky coasts, coastal erosion results in dramatic rock formations in areas where the coastline contains rock layers. Softer areas become eroded much faster than harder ones, which can cause things like tunnels, bridges, columns, and pillars.