The aim of this lecture is to present on Coastal Erosion. Coastal Erosion occur when a wave impacts a cliff face, air is forced into cracks under high pressure, widening them. Over long periods of time, the growing cracks destabilize the cliff and fragments of rock break off of it. The compressed air exerts enormous pressure at the tip of the crack. As the water falls back the air pressure is released and rock is pulled out from the crack further enlarging the hole. Corrosion/solution is when certain types of cliff erode as a result of weak acids in the sea.