Wave-cut notch Wave-cut platform 4. How a cliff is formed Feature: Sea Cave, Arch, Stack and Stump
How Sea Caves, Arches, Stacks and Stumps Form 1. Strong waves attack cracks and weaknesses in the base of a cliff. Through hydraulic action, abrasion and compressed air, they erode a large hole at the foot of the cliff. 2. This continues over thousands of years. The hole is known as a sea cave .
3. If a sea cave erodes all the way through the headland (or if two caves erode back to back), a sea arch will form. This is an archway straight through the headland.
4. If the roof of the arch collapses, a pillar of rock will remain standing alone in the sea. This pillar is known as a sea stack .
5. If over time the sea stack collapses into the sea, all that remains is a small stump of rock. This is known as a sea stump .
Examples: These can be seen at the Old Head of Kinsale, Co. Cork (sea caves and arch), and Hook Head, Co. Wexford (sea stack).
Cave Arch Stack Stump
Processes at work Hydraulic action Abrasion Compressed air
Processes at work Hydraulic action Abrasion Compressed air