Coastal Landscapes in the UK
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Wave types
Waves are created by wind blowing over the sea. The two main types have opposite effects on beaches.
Understanding swash vs backwash is key to explaining whether a beach grows or shrinks.
Wave types — Key Knowledge
- Fetch distance of open water over which wind blows — longer fetch means larger waves
- Constructive waves low frequency 6-8 per minute, strong swash, weak backwash — deposit material and build up beaches
- Destructive waves high frequency 10-14 per minute, weak swash, strong backwash — erode material and strip beaches
Weathering and mass movement
Weathering breaks down rock in situ (no movement), while mass movement shifts material downslope under gravity.
Both weathering and mass movement shape cliffs alongside wave erosion — examiners expect students to distinguish all three.
Weathering and mass movement — Key Knowledge
- Freeze-thaw weathering water enters cracks, freezes, expands, widens the crack
- Chemical weathering acidic rainwater dissolves limestone and chalk
- Biological weathering plant roots and burrowing organisms widen cracks
- Sliding material moves along a flat plane
- Slumping rotational movement, often after heavy rain saturates cliffs
- Rockfall fragments break away from steep cliff faces
Erosion processes
Waves erode coastlines through four distinct processes.
These four processes are frequently tested — students must name and explain the mechanism, not just list them.
Erosion processes — Key Knowledge
- Hydraulic action force of water compresses air in cracks, weakening rock
- Abrasion rocks carried by waves scrape the cliff face like sandpaper
- Attrition rocks smash into each other, becoming smaller and rounder
- Solution/corrosion seawater chemically dissolves rock, especially limestone and chalk
Transport and deposition
Longshore drift moves sediment along the coast in a zigzag pattern determined by prevailing wind direction.
Longshore drift explains both where sediment ends up and why management at one point affects beaches elsewhere.
Transport and deposition — Key Knowledge
- Longshore drift waves approach at an angle, swash carries material up the beach at that angle, backwash pulls it straight back under gravity — zigzag movement along shore
- Traction large rocks rolled along seabed
- Saltation pebbles bounced along
- Suspension fine material carried in the water
- Solution dissolved minerals carried invisibly
- Deposition occurs when waves lose energy — sheltered bays, changes in coastline direction, sudden depth changes
Erosional landforms
Erosion creates distinctive landforms along coastlines, especially where hard and soft rock alternate.
The headland erosion sequence (cave-arch-stack-stump) is one of the most commonly examined landform processes at GCSE.
Erosional landforms — Key Knowledge
- Headlands and bays discordant coastline — soft rock erodes faster forming bays, hard rock remains as headlands; wave refraction concentrates energy on headlands
- Cliffs and wave-cut platforms waves erode base creating a wave-cut notch, cliff collapses, process repeats, cliff retreats leaving a gently sloping rock platform exposed at low tide
- Caves arches stacks stumps waves exploit weaknesses — crack widens to cave, cave erodes through headland to arch, roof collapses leaving stack, stack undercut to stump
Depositional landforms
Deposition by constructive waves and longshore drift creates beaches, spits, bars, and sand dunes.
Students must distinguish spits from bars — a spit is attached at one end, a bar encloses a lagoon.
Depositional landforms — Key Knowledge
- Beaches sand beaches are gently sloping, shingle beaches are steeper
- Spits longshore drift deposits sediment past a bend in the coastline into open water, curved end caused by secondary wave direction, salt marshes form behind — e.g. Spurn Point
- Bars spit that grows across an entire bay mouth, creating a lagoon behind — e.g. Slapton Ley
- Sand dunes wind blows dry sand inland, embryo dunes form around obstacles, stabilised by marram grass, youngest dunes nearest the sea
Dorset coast case study
The Dorset coast (Jurassic Coast) is a discordant coastline with textbook examples of erosional and depositional landforms.
Dorset provides named examples for almost every coastal landform — essential for case study answers.
Dorset coast case study — Key Knowledge
- Lulworth Cove almost circular bay — sea eroded through narrow limestone band into softer clay behind
- Old Harry Rocks chalk stacks on Ballard Point headland
- Chesil Beach tombolo connecting Isle of Portland to the mainland
- Headlands Ballard Point, Durlston Head
Hard engineering
Hard engineering uses man-made structures to defend the coast against erosion and flooding.
Every hard engineering method has trade-offs between cost, effectiveness, and impact on neighbouring stretches of coast.
Hard engineering — Key Knowledge
- Sea walls concrete/rock barriers, curved to reflect wave energy — effective but expensive at 5000-10000 pounds per metre, strong backwash can scour the beach
- Groynes wooden/rock barriers perpendicular to coast trapping sediment from longshore drift — cheap but starve beaches further along the coast
- Rock armour/rip-rap large boulders absorb wave energy — cheaper than sea walls but unattractive and dangerous to walk on
- Gabions wire cages filled with rocks — cheap but not durable and unsightly
Soft engineering
Soft engineering works with natural processes to manage coastal erosion and flooding.
Soft engineering is generally cheaper and more sustainable but may not protect high-value areas quickly enough.
Soft engineering — Key Knowledge
- Beach nourishment adding sand/shingle to widen the beach — looks natural but needs constant replenishment
- Dune regeneration planting marram grass and fencing to encourage dune growth — cheap and sustainable but slow
- Managed retreat/coastal realignment allowing sea to flood low-value land creating salt marshes — cheap and creates habitats but landowners must be compensated
- Shoreline Management Plans divide coast into units: hold the line, advance the line, managed retreat, or no active intervention
Holderness Coast case study
The Holderness Coast is the fastest eroding coastline in Europe, averaging 1.8 metres per year.
Holderness illustrates the central dilemma of coastal management — protecting one area can worsen erosion elsewhere.
Holderness Coast case study — Key Knowledge
- Boulder clay cliffs easily eroded by destructive North Sea waves
- Mappleton defences rock groynes and rock armour costing 2 million pounds in 1991
- Knock-on effects protection at Mappleton accelerated erosion further south at Great Cowden
Map your gaps
Coastal Landscapes in the UK
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