cave, arch, stack, stump

• 1. erosional processes*
• 2. rocks contain weak points that are eroded easier
• 3. overtime lines of weaknesses are enlarged and developed into small sea caves by erosion
• 4. sometimes a blowhole forms in the caves roofs compressed air is pushed upwards by the waves power causing vertical erosion
• 5. erosion may occur both sides of the headland due to wave refraction , until the sea cuts through the backwall of the caves forming an arch. eg. Durdle Door
• 6. continued erosion enlarges the arch
• 7. base of arch is undercut by erosion so the arch is unsupported and collapses due to gravity, forming a stack eg. Old Harry