Erosional landforms, weathering and mass movement

Wave-cut notches and platforms

1. Waves attack the base of a cliff between high and low tide, cutting a wave-cut notch by hydraulic action and abrasion.

2. The notch deepens until the overhanging rock above collapses.

3. The cliff retreats inland, leaving a gently sloping rocky wave-cut platform exposed at low tide.

4. As the platform widens, waves break further out and lose energy before reaching the cliff, so the rate of retreat slows (a negative feedback).

Cave, arch, stack, stump

On headlands:

1. Waves exploit a joint or fault, widening it into a cave.

2. Caves on either side of a headland (or one cave cutting right through) join to form an arch.

3. The arch roof is weakened by erosion beneath and weathering above until it collapses, leaving a stack.

4. The stack is undercut and collapses into a low stump, covered at high tide.

The January 2024 mark scheme credited labelling a cliff, headland, notch or cave on a photograph.

Subaerial processes

Weathering breaks rock down in place:

• Mechanical: freeze-thaw (water freezes in cracks and expands), salt crystallisation, and exfoliation from repeated heating and cooling.
• Chemical: carbonation of limestone, hydrolysis (minerals react with water and lose structure), oxidation (iron minerals rust and crumble).
• Biological: plant roots widen cracks, burrowing animals, rock-boring shellfish.

Mass movement moves material downslope under gravity:

• Rockfalls: blocks detach from steep cliffs, often after undercutting or freeze-thaw.
• Rotational slides (slumps): saturated clay or till fails along a curved slip plane, leaving a back-tilted block and a terraced cliff.
• Also slides along bedding planes and mudflows.

Weathering weakens the cliff face; mass movement delivers material to the base, where waves remove it. Together they set the overall recession rate.

Worked example

Explain why the rate of cliff retreat may slow down as a wave-cut platform widens.

1. A wider platform means shallower water in front of the cliff.
2. Waves break further out and lose energy crossing the platform.
3. Less energy reaches the cliff base, so notching and collapse slow.

Answer: The widening platform dissipates wave energy: a negative feedback.

Check yourself

1. What is the correct order of headland erosion?
   • Cave, arch, stack, stump
   • Arch, cave, stump, stack
   • Stack, arch, cave, stump
   • Cave, stack, arch, stump
   Show answer

   Cave, arch, stack, stump. Cracks become caves, caves become arches, arches collapse to stacks, stacks erode to stumps.

2. A gently sloping rocky surface exposed at low tide in front of a cliff is a
   • berm
   • spit
   • wave-cut platform
   • salt marsh
   Show answer

   wave-cut platform. It is left as the cliff retreats.

3. Which mass movement typically happens in saturated clay cliffs along a curved slip plane?
   • Rotational slide
   • Rockfall
   • Freeze-thaw
   • Solution
   Show answer

   Rotational slide. Slumping rotates blocks back along a curved surface.

4. Iron minerals in rock rusting and crumbling is
   • hydrolysis
   • freeze-thaw
   • abrasion
   • oxidation
   Show answer

   oxidation. Oxidation of iron weakens the rock (credited in January 2024).

5. Which is an example of biological weathering on a cliff?
   • Waves compressing air
   • Plant roots widening cracks
   • Salt water dissolving limestone
   • Pebbles colliding
   Show answer

   Plant roots widening cracks. Roots and burrowing animals break rock.

6. Explain how freeze-thaw weathering weakens a cliff face.
   Show answer

   Water enters cracks in the rock and freezes at night and expands; this pressure widens the cracks, and repeated freezing and thawing breaks pieces of rock off.. Water, freezing, expansion, breakage.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Geography specification, Issue 3 (September 2025)
• Pearson IAL Geography Getting Started Guide
• Pearson WGE02/01 mark scheme, January 2024

Last updated 8 November 2026. Spotted a mistake? Tell us.