Wave Refraction: As waves approach an irregular coastline, they bend toward headlands, concentrating energy on the sides of the rocky outcrops.
Cave to Arch: Erosion exploits joints or faults in the headland to form a cave. When caves on opposite sides meet, or a cave erodes through the headland, an arch is formed.
Stack and Stump: The roof of an arch eventually collapses, leaving an isolated pillar of rock called a stack. Further erosion at the base causes the stack to collapse into a stump.
| Feature | Destructive Waves | Constructive Waves |
|---|---|---|
| Energy | High energy, plunging waves | Low energy, spilling waves |
| Frequency | High (10–14 per minute) | Low (6–8 per minute) |
| Dominant Motion | Strong backwash, weak swash | Strong swash, weak backwash |
| Result | Removes material (Erosion) | Deposits material (Deposition) |
Sequence is Critical: When describing landforms like stacks, always present them as a chronological sequence: Crack → Cave → Arch → Stack → Stump.
Terminology Precision: Do not confuse Abrasion (rocks hitting the cliff) with Attrition (rocks hitting each other). Examiners look for this specific distinction.
Link to Energy: Always mention that erosion is highest where wave energy is concentrated, such as on headlands due to wave refraction.
Check the Tide: Remember that wave-cut platforms are erosional features that are often submerged; mentioning their visibility at low tide demonstrates deeper understanding.
