Erosion is the wearing away of the land by the sea. This often involves destructive waves wearing away the coast. There are five main processes which cause coastal erosion. These are corrasion, abrasion, hydraulic action, attrition and corrosion/solution.
Corrasion is when waves pick up beach material (e.g. pebbles) and hurl them at the base of a cliff.
Abrasion occurs as breaking waves which contain sand and larger fragments erode the shoreline or headland. It is commonly known as the sand paper effect.
The video below shows abrasion in action at Flamborough on the Holderness Coast.
When waves hit the base of a cliff air is compressed into cracks. When the wave retreats the air rushes out of the gap. Often this causes cliff material to break away. This process is known as hydraulic action.
Attrition is when waves cause rocks and pebbles to bump into each other and break up.
Corrosion/solution is when certain types of cliff erode as a result of weak acids in the sea.