Coastal Landscapes of the UK

Question 1

What is a landscape?

Answer 1

An area whose character is the result of action and interaction between natural and human actions

Question 2

What is relief?

Answer 2

The physical features of a landscape, including height above sea level, steepness of slopes and shapes of landscape features

Question 3

What are the different types of rock in terms of resistance?

Answer 3

Resistant rocks - hard igneous rocks e.g. granite and basalt e.g. the north coast of Cornwall
Fairly resistant rocks - sedimentary rocks e.g. sandstone, chalk, limestone e.g. the Dorset coast
Least resistant rocks - weak sedimentary rocks e.g. clay, shale e.g. Holderness coast in Yorkshire

Question 4

What is a coast?

Answer 4

A transition zone between the edge of the land where it meets the sea

Question 5

What are the differences between hard and soft rock coasts?

Answer 5

Hard rock coast: tall rugged steep cliffs leading directly into the sea, cliff face often bare, rocks and boulders at the foot of the cliff, sea is clear
Soft rock coast: cliff less rugged and not so steep, trees and vegetation grow on the cliff face, very few rocks and boulders and some sand and mud at the foot of the cliff, sea is muddy as it is filled with sands and clay

Question 6

What is rock structure?

Answer 6

The different ways rock types are arranged. Rocks are generally found in layers, called strata

Question 7

What is a concordant coastline?

Answer 7

Where layers of rock are found parallel to the sea, with resistant rock found closest to the sea, followed by a band of softer rock, followed by a layer of resistant rock. It is found at Lulworth cove in Dorset. Features include coves, caves, and wave platforms.

Question 8

What is a discordant coastline?

Answer 8

Where layers of rock are found perpendicular to the sea. They are found in alternating layers of hard and soft rock, which creates headlands and bays. It is found at Swanage bay. Features include stumps, stacks, headlands, bays, and arches.

Question 9

What affects the size of waves?

Answer 9

The speed of the wind, the time the wind blows, and the distance of water the wind blows over (the fetch - the longer the fetch the stronger the waves) all affect the size of the waves.

Question 10

What is swash?

Answer 10

Water that rushes up the sand. It happens at the direction of the prevailing wind

Question 11

What is backwash?

Answer 11

Water rolling back into the sea. It happens at 90 degrees, from gravity

Question 12

What are constructive waves like?

Answer 12

Low wave height (<1m) with a long wave length, a spilling wave break, a strong swash and a weak backwash, a net gain in beach sediment, and a low (8-10) frequency per minute. It results in a gently sloping beach with a beach berm

Question 13

What are destructive waves like?

Answer 13

High wave height (>1m) with a short wave length, plunging wave break, a weak swash and a strong backwash, net loss in beach sediment, and a high (10-14) frequency per minute. It results in a steep beach with an offshore bar where sand is deposited

Question 14

How is sediment transported?

Answer 14

Traction - large pebbles rolled along the seabed
Saltation - a ‘hopping’ or ‘bouncing’ motion of particles too heavy to be suspended
Suspension - particles carried (suspended) within the water
Solution - dissolved chemicals often derived from limestone or chalk

Question 15

What is longshore drift?

Answer 15

When waves approach the beach at an angle, the continual movement of the waves up and down the beach as swash and backwash eventually causes material to move along the coastline in a zigzag pattern.

Question 16

What is weathering?

Answer 16

The breakdown of rock in situ caused by day-to-day changes in the atmosphere. It is a sub areal process. Types of weathering are chemical, biological and mechanical.

Question 17

What is mass movement?

Answer 17

The downslope movement of rock, soil or mud under the influence of gravity. Heavy rainfall is often a trigger, but the scale of movement is determined by the extent of weathering on the slope.

Question 18

How does chemical, biological and mechanical weathering break down rocks?

Answer 18

Mechanical: freeze thaw weathering results in rocks being disintegrated. Water enters gaps in rocks, then freezes and expands, putting pressure on the rock and expanding the gap.
Biological: plant roots penetrate rocks over time, breaking them apart. Animals walk on or dig holes in rocks, weakening them.
Chemical: rainwater is acidic from carbonic acid. It reacts with calcium carbonate in limestone and chalk, forming soluble calcium bicarbonate. Acid rain makes this happen faster

Question 19

What is sliding?

Answer 19

On steep cliffs weakened by weathering heavy rain infiltrates soil and percolates down the rock. Heavy mass falls away along a slip plan. Slides happen quickly, starting with tearing away vegetation at the top and aided by lubrication of wet rock below. Two types: rockslides and mudslides.

Question 20

What is rockfall?

Answer 20

Bare rocks with joints and faults are prone to mechanical weathering, resulting in them falling. At the bottom they fan out to form a scree slope. They are most common on vertical cliffs.

Question 21

What is slumping?

Answer 21

The bottom of cliffs is eroded by waved, the top is weakened by weathering and saturated by rain. Cliff material is made heavier and pulled down the cliff along its slip plane. The slip plane is concave so that material is rotated backwards into the cliff face as it slides.

Question 22

What are the types of marine erosion?

Answer 22

Hydraulic action: water hits the cliff, compressing air into cracks, faults and bedding plains. As the wave retreats, pressure is suddenly released, breaking apart the cliff
Abrasion: waves throw rocks and sediment at the cliff face, causing rock to crumple away as cracks form
Attrition: rocks and pebbles grind against each other during transport in waves, breaking into smaller rocks or shingle and becoming smooth and round
Solution: chemical reaction between acid in sea water and rock, causing some cliffs to erode

Question 23

What will make the rate of erosion faster?

Answer 23

Weather, location of coastline, geology of coast, faults and bedding planes on a cliff, weathering, lack of a beach to buffer, the arrangement of rocks leading to mass movement.

Question 24

What is a landform?

Answer 24

A feature of the landscape that has been formed or sculpted by processes of erosion, transportation, and/ or deposition

Question 25

What are the main characteristics of headlands and bays?

Answer 25

Bare resistant rock cliff face - stacks/ arches jutting out
Strong waves at headland
Discordant coastline
Sand beach formed in bay
Low energy constructive waves in bay

Question 26

How are headlands and bays formed?

Answer 26

At a discordant coastline differential rates of erosion mean softer rock erodes faster than resistant rock. Then wave refraction means headlands are eroded more and there are gentler, constructive waves in the bay, so a beach forms. E.g. at Swanage

Question 27

What is wave refraction?

Answer 27

As a wave approaches land, the crest at the headland is the first to experience shallower water and slow. On either side of the headland, faster parts of the wave refract towards it to keep the line of the crest intact. This concentrates more energy on the headland, so erosion increases

Question 28

What are the characteristics of cliffs and wave cut platforms?

Answer 28

Steep sides, bare cliff face, rockfall, resistant rock, very tall, wave cut notch at bottom
Horizontal and flat, smooth, made of same resistant rock, pools of water form, covered at high tide

Question 29

How does a wave cut platform form?

Answer 29

Cliffs slowly erode and get weathered over time. Between high and low tide erosion is fastest, causing a wave cut notch by undercutting. As it gets larger and the top gets weaker, it gets more precarious, before the cliff falls away onto the beach. This breaks up by attrition. The former base of the cliff is left behind as a wave cut platform. E.g. at Kimmeridge on the Dorset coast

Question 30

What are the characteristics of caves, arches, stacks, and stumps?

Answer 30

Caves: have a wide entrance and get narrower towards the back, made of resistant rock like chalk, a blow hole may form in the roof.
Arches: unsupported top, water continues all the way through, extension of the headland, wave cut notches at the base
Stacks: detached pillars of rock off a headland, several metres high, some are pinnacle shaped, made of resistant rock, wave cut notches
Stumps: much smaller than stacks, only visible at low tide

Question 31

How are caves, arches, stacks, and stumps formed?

Answer 31

Over time erosion from the sea causes cracks to form in them. Erosion causes these cracks to widen into crevices. Weathering and erosion causes these to widen into caves. Waves refraction on both sided of the cliffs as well as erosion and weathering means the sea will break through the back of the cave, turning it into an arch. Weathering weakens the too until it collapses, forming an stack. Notches form in the bottom of this, causing it to collapse into a stump. E.g. Ballard Down cliffs in Dorset

Question 32

How are coves formed?

Answer 32

In a concordant coastline, processes of erosion create a cave in the resistant rock next to the sea. The rock eroded away breaks up and further erodes the rock, causing the sea to break through. The softer rock behind erodes much faster. It becomes a circular shape because of wave diffraction, which causes waves to bend into an arched shape. E.g. Lulworth Cove

Question 33

When does coastal deposition take place?

Answer 33

When the flow of water slows down because the waves have lost some of their energy, so more sediment stays on the beach than is taken away

Question 34

What conditions cause deposition?

Answer 34

Low energy, sheltered bays
If there is a large source of sediment updrift e.g. a rapidly eroding headland
Where there is a large expanse of flat beach so swash spreads over a large area, weakening the wave
Where water is trapped so that energy is lost

Question 35

What are characteristics of sandy and shingle/ pebble beaches?

Answer 35

Sandy beach: shallow gradient, dominant waves are low energy constructive, beach stretches a long way inland, at the back sand dunes are sometimes found, there may be a berm. Sandbanks beach in Poole
Shingle/ pebble beach: steep gradient, dominant waves are higher energy destructive, beach stretches not far inland, large pebbles are found at the back, often an offshore bar is created. West Bay on the Dorset coast

Question 36

What is a spit?

Answer 36

A narrow ridge of sand and shingle that extends into the sea. There may be a marsh formed behind in stagnant water, there is a narrow ridge, it cuts off in deeper water, and there is a recurved end.

Question 37

How are spits formed?

Answer 37

The coastline changes direction. Longshore drift causes sediment to be deposited in the sea, forming a spit. As it gets longer longshore drift gets weaker so there are smaller rocks further along. A marsh forms behind in stagnant water. It ends when longshore drift gets too weak to carry material. There may be a recurved end if the current or prevailing wind changes direction. E.g. Sandbanks, Dorset

Question 38

What are bars and tombolos?

Answer 38

Bars are spits that rejoin the coastline further on. They require shallow water across a bay, one longshore drift direction, and a good supply of material. E.g. Slapton Sands, Devon
Tombolos are spits that join an island e.g. Chesil Beach to the Isle of Portland

Question 39

What is needed for a sand dune to form?

Answer 39

A large flat beach
A large supply of sand
A large tidal range, so there is time for sand to dry
An onshore wind to move sand to the back of the beach
An obstacle such as drift wood for the dune to form against

Question 40

What are the three main ways wind transports sand?

Answer 40

Suspension - sand is picked up and carried within wind
Saltation - grains of sand bounce along in the wind as they are alternatively raised then dropped
Creep - sand grains collide when each other and push other grains along

Question 41

How do sand dunes form?

Answer 41

Sand moves along the beach from an onshore wind. It continues to move up the windward slope. The height builds up until the structure becomes unstable. Sand then slips down the leeward slope

Question 42

What are the main characteristics of sand dunes?

Answer 42

Marram grass that can stabilise the dune
Gentle slope on windward side
Crests (heights vary up to ~15m)
Unstable steep slip slope (30-34 degrees) on sheltered leeward side

Question 43

What is holding the line?

Answer 43

Managing coastal erosion by keeping the coastline in the same place

Question 44

What is a holistic approach?

Answer 44

Taking into account all social and economic factors as well as physical conditions. The main purpose of this strategy is to make management of coastal areas more sustainable

Question 45

What is hard engineering?

Answer 45

The building of coastal defences using man-made materials such as concrete

Question 46

What is soft engineering?

Answer 46

The building of coastal defences using natural resources. It often requires less intervention

Question 47

What is rip rap/ rock armour?

Answer 47

Putting resistant ricks along the coastline to protect weak cliffs behind. Act as a barrier to reduce wave energy. They are effective for many years and habitats can develop around them over time, but they can restrict beach axis, are expensive at £300/m and can disrupt processes of deposition on the beach.

Question 48

What is managed retreat?

Answer 48

Allowing the sea to take its course and erode the coastline. Moving houses away from the coastline. It makes flooding less likely, is free and creates new habitats for plants and animals, but it is upsetting for landowners, costs to compensate people, and is difficult to estimate the extent if sea movement.

Question 49

What is beach nourishment?

Answer 49

Taking sand from the sea bed or other areas and using it to build up a beac. It is soft engineering. It does not look ugly, is quite cheap at £50/m and encourages visitors, but large lorries carrying sand disrupt locals, needs to be maintained every year or two and alters animal habitats.

Question 50

What is dune regeneration?

Answer 50

Creating or restoring dunes by nourishment (using fencing to trap sand) or by planting vegetation to stabilise it. They absorb wave energy. They do not spoil the landscape and look natural and protect against flooding, but they are very fragile, only offer protection for a small area and take time to grow Marram grass

Question 51

What is a sea wall?

Answer 51

A large concrete structure that acts as a barrier, as the sea hits them instead of the softer cliff face. The top of the wall is curved to reflect the force. They protect the coastline for many years and can protect larger towns, but are large and unattractive, very expensive at £3000/m and need maintenance and can stop a natural beach forming.

Question 52

What are groynes?

Answer 52

Wooden, rock or concrete fences built along a beach, perpendicular to the coastline. They stop longshore drift by trapping sand and stopping it being washed away. As the beach is larger, the area is eroded less. It encourages people to visit the area as there is a beach, but is unattractive, quite expensive at £5000 each and rot over time and mean beaches further down the coastline do not have enough sand, causing faster erosion there.

Question 53

What are gabions?

Answer 53

Rocks held together by wire mesh placed along the coastline to reduce wave power to slow erosion. They can be buried around vegetation, making them more attractive, they are quite cheap at £11/m and can stop habitats eroding away, but they are unattractive, they rust over time so require regular maintenance and they need to be replaced every 5-10 years.

Question 54

Why was coastal management needed in Medmerry?

Answer 54

The area was at risk of flooding
The only protection was a shingle ridge and beach nourishment that cost £200,000 per year
Flood defences were breached in 2008, costing £5m

Question 55

What management took place in Medmerry?

Answer 55

A new clay embankment was created 2km inland
A channel to drain excess water was built behind this
Rock armour was built against the embankment for support
A 110m breach was made in the shingle bank, allowing sea water to flood the area and create a salt marsh

Question 56

What were the benefits of coastal realignment in Medmerry?

Answer 56

Flood risk has been reduced
Tourism is increasing, especially from birdwatchers
The flooded area will become a nursery to boost the local fishing industry
Saltmarshes are being used to graze cattle to make expensive ‘salt marsh beef’
3000 hectares of inner tidal habitats have been created, encouraging birds. It is managed by the RSPB

Question 57

What were the costs of coastal realignment in Medmerry?

Answer 57

It was expensive at £28m, compared to the £0.2m/year beforehand
Good quality farmland was lost
Habitats of badgers and other land animals were lost