The Coastal Zone

Question 1

How is sediment moved at the coast? Give a small definition for each transportation method.

Answer 1

Traction: when pebbles and larger sediment is rolled along the sea bed
Saltation: load is bounced along the seabed
Suspension: small particles are carried in water
Solution: minerals are dissolved and carried in solution

Question 2

How is the coast eroded? Give an explanation for each type

Answer 2

Solution: acids contained in the sea water dissolve rock such as chalk and limestone
Attrition: waves smash rocks and pebbles on the shore into each other, they break and become smoother
Abrasion: bits of rock and sand in waves grind down cliff and surfaces
Hydraulic action: air may become trapped in joints and crack of a cliff which then freezes breaking the cliff by freeze-thaw

Question 3

Describe the qualities of a destructive wave.

Answer 3

High wave
Breaks in a downward movement onto the shore
Weak swash
Strong backwash
Occurs when wave energy is high or there is a storm

Question 4

Describe the qualities of a constructive wave.

Answer 4

Low wave
Strong wash
Weak backwash
They break on the shore and deposit material
Created in calm weather

Question 5

Give some examples of depositional landforms.

Answer 5

Beaches
Spits
Tombolos

Question 6

What are beaches and how are they formed?

Answer 6

Beaches are mad up of eroded material that has been transported from elsewhere and deposited by the sea.

Question 7

What are spits and how are they formed?

Answer 7

A spit is an extended stretch of beach material and is joined to mainland at one end.
Longshore drift moves material along the coastline
A spit forms when the material is deposited
Overtime the spit grows and develops a hook if the wind direction changes further out
Waves can’t get past a spit, which create a sheltered are where silt is deposited and mud last or salt marshes form

Question 8

What are Tombolos and how are they formed?

Answer 8

A Tombolo is a spit connecting an island to the mainland, they are formed the same way spits are.

Question 9

Give an example of a tombolo

Answer 9

Chenille beach connects the isle of Portland to the mainland Dorset coast.
It stretches for 18 miles.
Lagoons have formed behind the stretch of beach.

Question 10

List some erosion landforms

Answer 10

Caves, arches, stacks and stumps
Headlands and bays
Cliffs

Question 11

How are caves, arches, stack and stumps formed?

Answer 11

Caves occur when waves force their way into cracks in the cliff face. The water contains sand and other ,are rials that grind way at the rock until the cracks become a cave. Hydraulic action is the predominant process.
If the cafe is formed in a headland, it may eventually break through the other side forming an arch.
The arch will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack on the other.
The stack will be attacked at the base which weakens the structure.
Eventually it will collapse to form a stump.

Question 12

How are headlands and bays formed?

Answer 12

They are formed when the sea arak a a section of coast with alternating bands of hard and soft rock.
The sea will erode the soft rock quicker, which creates a bay and the hard rock will stick out crating a headland.

Question 13

How are cliffs eroded?

Answer 13

Weather weakens the top of the cliff.
The sea attacks the base of the cliff forming a wave-cut notch
The notch increases in size causing the cliff to collapse.
The backwash carries the rubble towards the sea forming a wave-cut platform
The process repeats and the cliff continues to retreat.

Question 14

List some examples of hard engineering solutions.

Answer 14

Sea walls
Groynes
Rock armour

Question 15

List some advantages and disadvantages of building a sea wall

Answer 15

Advantages: protects the base of cliffs, land and buildings against erosion. Can also prevent coastal flooding in some areas.
Disadvantages: expensive to build (can be up to £6 million per kilometre to construct), reflects wave energy back to sea so they remain powerful, overtime they will begin to erode so cost of maintenance is high.

Question 16

List some advantages and disadvantages of building groynes.

Answer 16

Advantages: prevents the movement of beach material along the coast by L.S.D. Allows the build up of beach. Beaches are a natural defence against erosion and an attraction for tourists.
Disadvantages: can be seen as unattractive. Are costly to build and maintain (£10,000 each).

Question 17

List some advantages and disadvantages of rock armour.

Answer 17

Advantages: absorbs the energy of waves. Allows the build up of beach.
Disadvantages: can be expensive to obtain and transport the boulders (they cost between £1000-4000 per metre)

Question 18

List some examples of soft engineering.

Answer 18

Beach management
Managed retreat
Dune regeneration

Question 19

List some advantages and disadvantages of beach management.

Answer 19

Advantages: beaches are a natural defence against erosion and coastal flooding. Beaches also attract tourists. It is a relatively inexpensive option (£3000 per km).
Disadvantages: it requires constant maintenance to replace the beach material as it is washed away.

Question 20

List some advantages and disadvantages of a managed retreat.

Answer 20

Advantages: it encourages the development of beaches and salt marshes. The cost is low.
Disadvantages: people will need to be compensated for the loss of their buildings and farmlands.

Question 21

Give some advantages and disadvantages of dune regeneration

Answer 21

Advantages: encourages wildlife and plants to grow, absorbs storm and wave energy, relatively low costs (£2,000 per metre)
Disadvantages: time consuming as it needs a lot of maintenance, less effective than hard engineering schemes.

Question 22

List some types of mass movement.

Answer 22

Rockfall
Mudflow
Landslips
Slumping

Question 23

Give a definition of rockfall

Answer 23

It is the rapid, free fall of rocks from a steep cliff face. Rock fragments fall from the face of the cliff cause of the action of gravity. This is made worse by freeze-thaw action loosening the rock.

Question 24

Give a definition of mudflow

Answer 24

Mudflow occurs on steep slopes over 10 degrees. It’s a rapid sudden movement which occurs after periods of heavy rain. When there is not enough vegetation to hold the soil in place, saturated soil flows over impermeable sub soil.

Question 25

Give a definition of landslips

Answer 25

They are occasional, rapid movements of earth or rock sliding along a concave plane. They can occur after periods of heavy rain, when the water saturates overlying rock, making it have and liable to slide. Undercutting of a steep slip by river or sea erosion weakens the rock above, also making a slump likely.

Question 26

Give a definition of slumping.

Answer 26

A mass of soil, or clay, slides downwards along a curved slip-plane, forming a ‘scar’ on the upslope and a ‘to ‘ on the downslope.

Question 27

How could rising sea level impact East Anglia?

Answer 27

Economic: buildings worth £80bn will need replacing
Social: settlements, such as king’s Lynn, will struggle to move as they are under threat.
Environmental: low lying mudflats and marshes are vulnerable. An estimate of 22% lost by 2050.

Question 28

Give an example place where there are arguments for hard or soft engineering.

Answer 28

Happisburgh, east of England, Norfolk.

Question 29

Why is Happisburgh vulnerable?

Answer 29

It is vulnerable as it is located on soft rocks such as clay, which are quicker to erode. These are easily eroded by the North Sea as the waves are powerful, due to the long fetch they have.

Question 30

What defences are currently in place?

Answer 30

Wooden groynes, which are dated and are not working properly so are not preventing LSD, which is depriving the beach which is protecting housing.

Question 31

What else has been placed?

Answer 31

Residents and council raised money in order to buy 6,000 tonnes of granite rock, which is igneous and will erode slowly. This has been placed along the coast in hope that the sea will erode that before the cliff.

Question 32

What will happen if coastal erosion continues in Happisburgh?

Answer 32

More housing will be lost, which may result in some people becoming homeless

Question 33

Give a CSI study for a coastal habitat.

Answer 33

Key haven salt marsh.

Question 34

What wildlife inhabits the key haven salt marsh?

Answer 34

Eel grass
Glass wort
Brown hare 
Barn owl
Ringed plover
Ruddy darter

Question 35

What are the threats to the salt marshes?

Answer 35

They are under threat from the construction of groynes down the current to the west. This has starved the spit which shelters the salt marsh. The spit has often been breached by erosion. The marsh has been retreating by 6m per year and is threatened by sea level rise and storms.

Question 36

What management strategies have been used in order to save the salt marsh?

Answer 36

The plan was put into place in 1996 which added 300,000 cubic metres of shingle to the spit, and added 550m of rock armour at the western end of the spit, this has been put in place to stabilise the marsh.
It is also part of the SSSI and a part of a national reserve. This is to protect the biodiversity and plants of the area and so the area is carefully monitor and managed to help maintain biodiversity.