1. Hydraulic action: Lines of weakness are created between the high and low tide levels by the force of the destructive wave crashing against the coast
2. Compression: The destructive wave also forces air into cracks and joints of rock surfaces, where it is compressed. As the wave retreats, the air decompresses and rapidly expands, causing an explosion. Rocks are shattered into little pieces that fall into the sea, increasing the size of cracks and joints.
3. Abrasion: The shattered pieces of rock are picked up by strong waves and used as another tool of erosion against the coastline
4. As the notch gets bigger, the rock overhead is left overhanging and unsupported. Over time, the overhang becomes more vulnerable to the influence of gravity, until it eventually collapses under its own weight, forming a small cliff. Destructive waves continue the process of undercutting the coast, causing the cliff to retreat inland getting taller each time.
5. Acids in the sea (e.g. carbonic acid) also erode the cliff face through the process of solution
