Formation of Caves, Arches, Stacks, and Stumps

• when headlands made of resistant rock are attacked by waves, the processes of hydraulic action, abrasion, and solution occur.
• these processes enlarge the cracks, creating a cave
• when two waves are formed back to back, they meet to form an arch
• the rock above the arch is subject to hydraulic action by storm waves and freeze thaw weathering. a blow hole can also form
• the rock above the arch becomes unstable and collapses due to gravity
• this leaves a rock separated from the headland called a stack
• the stack will continue to be attacked by wave action and by chemical and physical weathering. It will eventually be worn down to sea level leaving a stump
• example of stack and stump: Old Harry’s Rock
• example of an arch: Durdle Door