SEACAVES: Waves crashing against the base of a cliff can sometimes form a sea cave. Sea caves form along a crack in a rock or an area where the rock is softer. Because the abrasive action of waves is concentrated at the base of the cliff, an overhang forms.
SEAARCHESANDSEASTACKS:They are formed when part of a headland is eroded by hydraulic action, which is the force of the sea or water crashing against the rock. ... Erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast—the stack. Eventually, erosion will cause the stack to collapse, leaving a stump.
SEASTUMP: A sea stump is formed when a tall sea stack is eroded and worn down until it juts just above the surface of the sea.
