Coastal landscapes: processes and landforms

Coastal landforms appear on nearly every OCR J383 Paper 1. Expect 4-mark describe questions and 8-mark explain questions. Like rivers, you must be able to sequence processes and explain landform formation using correct terminology.

Wave processes

Types of waves

Wave type	Characteristics	Dominant action
Constructive	Low frequency; long wavelength; low height; strong swash, weak backwash	Deposition
Destructive	High frequency; short wavelength; tall; weak swash, strong backwash	Erosion

Coastal erosion processes

Process	Description
Hydraulic action	Wave crashes into cliff; air trapped in cracks is compressed then decompresses violently, breaking rock
Abrasion	Waves throw sediment against the cliff face — sandpaper effect
Attrition	Rocks and pebbles knock together and break into smaller, rounder pieces
Solution	Soluble minerals in cliff rock dissolved by sea water

Longshore drift

• Waves approach the coast at an angle (driven by prevailing wind direction).
• Swash moves sediment up the beach at the same angle as the wave.
• Backwash moves sediment straight back down the beach at 90° (due to gravity).
• Net movement of sediment along the coast = longshore drift.
• Direction of longshore drift is controlled by the prevailing wind direction.

Erosional landforms

Headlands and bays

• Alternating bands of hard (resistant) and soft (less resistant) rock at the coast.
• Soft rock erodes faster → bays form.
• Hard rock erodes slower → headlands protrude into the sea.
• Once headlands form, they concentrate wave energy → further erosion of headland features.

Cliffs, wave-cut platforms, and notches

1. Waves erode the base of a cliff (hydraulic action + abrasion) → wave-cut notch forms.
2. Notch undercuts the cliff → cliff collapses.
3. The process retreats → wave-cut platform (gently sloping rocky surface exposed at low tide) left behind.

Caves, arches, stacks, stumps

1. Cave: hydraulic action exploits a joint or weakness in a headland.
2. Arch: two caves erode from either side and meet through the headland.
3. Stack: the roof of the arch collapses, leaving an isolated pillar.
4. Stump: continued weathering and erosion reduces the stack to a low stump (visible only at low tide).

Depositional landforms

Beaches

• Swash-aligned beaches: waves approach parallel to coast → constructive waves deposit material evenly.
• Material size decreases from coarse (near cliff) to fine (towards sea).

Spits

1. Longshore drift transports sediment along the coast.
2. Where the coastline changes direction (e.g. estuary), sediment continues in the original direction.
3. A ridge of sand and shingle extends into the sea or across an estuary — a spit.
4. The hooked end (recurved) of the spit forms because the wind direction changes temporarily.
5. Behind the spit: sheltered water → salt marsh develops.

Bars and tombolos

• Bar: a spit that grows all the way across a bay, enclosing a lagoon behind it.
• Tombolo: a spit that connects the mainland to an offshore island.

Common OCR exam mistakes

1. Saying headlands are hard rock without explaining why hard rock resists erosion longer — differential erosion between hard and soft rock.
2. Confusing the cave→arch→stack sequence — the arch forms first, then collapses to form the stack.
3. Forgetting the recurved/hooked end of a spit and not explaining why it curves (changing wind direction).
4. Mixing up constructive and destructive waves — constructive = deposition; destructive = erosion.