This document discusses coastal erosion processes. Hydraulic action involves air being forced into cracks in rock by waves, building enormous pressure that breaks off rock pieces when the water falls. This type of erosion is called hydraulic action. Coastal erosion forms headlands and bays as harder rock headlands project into the sea while softer bays erode back. Arches, stacks and stumps can form from erosion and collapse of the rock structures. Wave cut platforms are formed between high and low tides as waves erode the cliff but not the platform. Longshore drift involves waves carrying sediment up beaches at an angle due to wind direction and then carrying it down coast at 90 degrees due to gravity, moving material along the coast in