Coastal Landscapes in the UK Flashcards
All 39 cards in this deck
Which type of wave has a strong swash and a weak backwash, and what effect does it have on the coast?
Constructive waves — they build up the beach (deposition). They are low, with a long wavelength and low frequency (6–8 per minute).
True or false? Destructive waves are low with a long wavelength.
False. Destructive waves are tall and steep with a short wavelength and high frequency, and a strong backwash that removes beach material.
What are the steps of freeze–thaw (mechanical) weathering on a cliff?
e.g. a cliff with cracks in winter- Water collects in cracks in the rock — rain or spray fills the cracks.
- Temperature falls below 0°C and the water freezes and expands by about 9%, widening the crack.
- Repeated freezing and thawing breaks fragments off the cliff face.
Which chemical weathering process breaks down chalk and limestone cliffs?
Carbonation (solution) — rainwater with dissolved carbon dioxide forms a weak carbonic acid that dissolves the rock.
Which type of mass movement is a rotational movement of saturated soft rock down a curved slip surface?
Slumping — common on soft boulder clay cliffs (e.g. Holderness) after heavy rain.
In sliding (a landslide) at the coast, how does the material move?
Material moves rapidly downslope in a straight line along a flat slip plane, staying largely intact.
Which type of mass movement leaves scree at the base of a steep cliff?
Rock fall — fragments loosened by weathering break off the cliff face and fall to the base.
How does hydraulic power erode a cliff?
Waves trap and compress air in cracks in the rock; the pressure widens the crack and breaks pieces of rock away.
How does abrasion erode the coast?
Sand and pebbles carried by the waves are thrown against the cliff, scraping and wearing it away like sandpaper.
What does attrition wear down at the coast?
The sediment itself — rock fragments carried by the sea collide and knock against each other, becoming smaller, rounder and smoother.
What are the steps of longshore drift?
e.g. a beach with waves driven by a south-westerly prevailing wind- Waves approach the beach at an angle, set by the prevailing wind — from the south-west.
- Swash carries sediment up the beach at that same angle.
- Backwash drags it straight back down under gravity, so sediment zigzags along the coast — towards the north-east.
Why is sediment deposited in coastal areas?
Because the waves lose energy and can no longer transport their load — e.g. in sheltered bays, in shallow water, or where constructive waves dominate.
What is the difference between a discordant and a concordant coastline?
Discordant: bands of hard and soft rock meet the coast at right angles, giving headlands and bays. Concordant: the bands run parallel to the coast, giving a fairly straight coastline.
True or false? Chalk cliffs are eroded faster than boulder clay cliffs.
False. Chalk is a more resistant rock, so it erodes slowly and forms headlands; soft boulder clay (e.g. Holderness) erodes much faster.
How do headlands and bays form?
e.g. Swanage Bay and Durlston Head, Dorset- A discordant coastline has alternating bands of hard and soft rock at right angles to the sea.
- The softer rock (clay/sand) is eroded faster to form a bay — Swanage Bay.
- The more resistant rock is left jutting out as a headland — Durlston Head.
How does a cliff retreat and a wave cut platform form?
e.g. below the cliffs at Flamborough Head- Waves erode a wave cut notch at the base of the cliff between high and low tide.
- The notch deepens until the overhanging rock collapses, so the cliff retreats inland.
- The gently sloping rocky surface left behind, exposed at low tide, is the wave cut platform.
What is the sequence of formation of a stack?
e.g. Old Harry Rocks, Dorset- Hydraulic power and abrasion widen a crack in a headland into a cave.
- The cave is eroded right through the headland to form an arch.
- The arch roof collapses, leaving an isolated pillar — a stack, which later erodes to a stump.
How does a spit form?
e.g. Spurn Head, Holderness- Longshore drift transports sediment along the coast until the coastline changes direction.
- Sediment is deposited in the sheltered, shallower water, building a ridge out to sea.
- A change in wind or wave direction curves the end (recurved end); salt marsh forms behind it.
Which waves form a shingle beach and which form a sandy beach?
Shingle beaches (steep and narrow) are formed by high-energy destructive waves; sandy beaches (wide and gently sloping) are formed by low-energy constructive waves in sheltered bays.
What conditions are needed for sand dunes to form?
A large supply of dry sand, a large tidal range, strong onshore winds, and an obstacle (e.g. driftwood) to trap the sand; marram grass then stabilises it.
What is a bar, and what forms behind it?
A spit that has grown right across a bay, joining two headlands; the water trapped behind it becomes a lagoon.
Name three landforms that show, on a map or photograph, that a UK coastline is being eroded.
Any three of: cliffs, wave cut platform, caves, arches, stacks, stumps, headlands and bays.
Name two landforms of erosion and one landform of deposition found on the Dorset coast.
Erosion: Durdle Door (arch), Old Harry Rocks (stacks), Lulworth Cove (cove/bay). Deposition: Chesil Beach (tombolo/barrier beach) or the beach and dunes at Studland Bay.
Give one benefit and one cost of a sea wall.
Benefit: reflects waves back out to sea, preventing erosion and flooding, and can include a promenade. Cost: very expensive to build and maintain, and looks unnatural.
Give one benefit and one cost of rock armour (rip rap).
Benefit: large boulders absorb and break up wave energy, and it is cheaper and quicker than a sea wall. Cost: boulders are usually imported from elsewhere, look out of place and can be dangerous to climb on.
What are gabions, and what is their main disadvantage?
Wire cages filled with rocks built at the foot of a cliff to absorb wave energy; they are cheap, but look ugly and the cages rust and break within about 5–10 years.
How do groynes protect the coast, and what problem do they cause?
Wooden or rock barriers built at right angles to the beach trap sediment moved by longshore drift, creating a wider beach that absorbs wave energy; but they starve beaches further along the coast, increasing erosion there.
What is beach nourishment, and give one disadvantage of it.
Adding sand or shingle (often dredged offshore) onto an existing beach so it absorbs more wave energy; it is expensive and has to be repeated regularly.
What is beach reprofiling?
Reshaping the beach by moving sediment from the lower beach back up to the upper beach, usually after a storm; cheap and simple, but only works in low-energy conditions and must be repeated.
What does dune regeneration involve, and give one benefit.
Planting marram grass and fencing off dunes or adding boardwalks to stop trampling; it is cheap and creates a natural barrier to flooding as well as a wildlife habitat.
What does managed retreat (coastal realignment) mean?
Allowing the sea to flood or erode an area of low-value land, which then usually becomes salt marsh or mudflat.
True or false? Managed retreat is normally used where the land is of low value, such as farmland.
True. It would not be used to protect high-value land such as a town centre, where hard engineering is more likely.
Give two benefits of managed retreat compared with hard engineering.
It is much cheaper with low maintenance costs, and the salt marsh created stores water, buffers wave energy and provides a wildlife habitat.
Give two reasons why the coastline at Lyme Regis, Dorset, needed managing.
Unstable cliffs with frequent landslips threatened homes and roads, and erosion of the beaches and old sea walls threatened the town and its tourist economy.
Which management strategies were used in the Lyme Regis coastal scheme, Dorset?
New sea walls and promenades, rock armour, beach nourishment to create a wider sand and shingle beach, plus cliff drainage and nailing to stabilise the land.
Give one conflict or negative effect resulting from the Lyme Regis coastal management scheme.
It cost around £43 million of public money; more visitors bring traffic and litter, and some residents object that the defences spoil the natural look of the coast.
True or false? Mass movement is a type of coastal erosion.
False. Mass movement is the downhill movement of material under gravity (sliding, slumping, rock falls); erosion is the wearing away of the coast by waves.
True or false? A spit grows across a river mouth until it joins the land on the other side.
False. River flow keeps a channel open, so a spit stops short; a bar forms when a spit grows right across a bay.
True or false? Rock armour is an example of soft engineering.
False. Rock armour is hard engineering – an artificial structure built to resist the sea.