Coasts (Yr 10)

Question 0

What is mechanical weathering?

Answer 0

The breakdown of rocks and soil through direct contact with atmospheric conditions such as heat water ice and pressure.
E.g. Frost shattering & exfoliation

Question 1

What are the three types of weathering?

Answer 1

Mechanical
Chemical
Biological

Question 2

What is chemical weathering?

Answer 2

The direct effect of atmospheric chemicals or biologically produced chemicals in the breakdown of rocks, soils and minerals.
E.g. Oxidation

Question 3

What is biological weathering?

Answer 3

Living organisms work both mechanically and chemically to breakdown of rocks and minerals.
E.g. Animals burying down into the ground.

Question 4

What is Frost shattering?

Answer 4

A method of mechanical weathering where water expands when it freezes (increasing its volume by 10%)
The expansion places huge pressure on the rock eventually causing it to crack.

Question 5

What is exfoliation or onion skin weathering?

Answer 5

The method of mechanical weathering where, during the day, the surface of the Rock heats up and expands. At night it cools and contracts.
This causes the surface of the rock to flake off.

Question 6

What is oxidation?

Answer 6

A method of chemical weathering where oxygen combines with iron bearing silicate minerals minerals, causing rusting. This weakens and breaks down rock.
Iron oxide produced makes the rocks red-brown.

Question 7

What is dissolution (or solution)?

Answer 7

A method of chemical weathering where acidic water reacts with some minerals found in rocks causing them to dissolve.
Calcite is particularly vulnerable and found in limestone and chalk.

Question 8

What are carbonic acids?

Answer 8

A method of chemical and biological weathering where, as plants decompose, they release acids into the soil which react with rocks and break them them.

Question 9

How do animals and plants effect weathering?

Answer 9

Animals bury down into the ground breaking up rocks as do plants. Sand wasps create circular holes in Stanson cliffs.
This weakens the rock and allows it to break easily.

Question 10

What is the coastal system?

Answer 10

The coastal system is ultimately the erosion and movement of rock and land due to the sea and waves.
The coast acts as a giant conveyor belt; material is worn away from some places, moved by waves and deposited in a different place.

Question 11

What are the 4 types of erosion?

Answer 11

Hydraulic pressure
Abrasion / corrasian
Attrition
Corrosion / solution

Question 12

What is hydraulic pressure?

Answer 12

A type of erosion when the force of the waves, especially when they trap and compress air into cracks and holes in a cliff, blasting away fragments of rock.

Question 13

What’s abrasion / corrasian?

Answer 13

A type of erosion when, in stormy conditions, waves have enough energy to pick up large quantities of sand, pebbles and beach material which are then hurled against the cliffs, breaking rock.

Question 14

What’s corrosion / solution?

Answer 14

A type of erosion when (certain cliff types) are slowly dissolved by acids in sea water.

Question 15

What’s attrition?

Answer 15

A type of erosion when waves cause rocks and pebbles on the beach to bump into each other and breakdown in size.

Question 16

What’s the rotational stumping process?

Answer 16

A mass movement process.
Rainfall saturates the cliff and also lubricates the rocks. (This is also the place for sub-Ariel processes - weathering on the cliff face.)
The cliff then gradually becomes heavier and more unstable and so the cliff face falls/the cliff fails along the glide plane.
The cliff then slumps under its own weight and the toe of the slump is removed by the sea.

Question 17

What’s the undercutting process?

Answer 17

A mass movement process
Sub-Ariel weathering, especially in winter seasons of frost and storms, takes place on the cliff top/face.
There’s undercutting at the foot of the cliff due to wave motion (hydraulic pressure and abrasion)

Soft cliffs are quickly undermined and collapse with winter storms and high tides.
The cliffs result in retreating as the base/foot of the cliff is eroded so the heavy and unsupported cliff tops fall and wash away.
This is repeated as the cliff retreats.

Question 18

What are destructive waves?

Answer 18

The effects of a high wave

Destructive waves are created in storm conditions.

They are created from big, strong waves when the wind is powerful and has been blowing for a long time.

They occur when wave energy is high and the wave has travelled over a long fetch.

They tend to erode the coast.

They have a stronger backwash than swash.

They have a short wave length and are high and steep.

Question 19

What are constructive waves?

Answer 19

They are created in calm weather and are less powerful than destructive waves.

They break on the shore and deposit material, building up beaches.

They have a swash that is stronger than the backwash.

They have a long wavelength, and are low in height.

Question 20

What’s transportation?

Answer 20

Waves can approach the coast at an angle because of the direction of the prevailing wind.
The swash of the waves carries material up the beach at an angle.
The backwash then flows back to the sea in a straight line at 90°. This movement of material is called transportation.

Question 21

What’s longshore drift?

Answer 21

Continual swash and backwash transports material sideways along the coast.
This movement of material is called longshore drift and occurs in a zigzag.

Waves follow the direction of the prevailing wind.

They usually hit the coast at an oblique angle

The swash carries material up the beach in the same direction as the waves.

The backwash then carries material down the beach at right angles.

Question 22

What are the methods of coastal transport?

Answer 22

Solution
Minerals are dissolved in sea water and carried in solution. The load is not visible. Load can come from cliffs made from chalk or limestone, and calcium carbonate is carried along in solution.

Suspension
Small particles are carried in water, eg silts and clays, which can make the water look cloudy. Currents pick up large amounts of sediment in suspension during a storm, when strong winds generate high energy waves.

Saltation
Load is bounced along the sea bed, eg small pieces of shingle or large sand grains. Currents cannot keep the larger and heavier sediment afloat for long periods.

Traction
Pebbles and larger sediment are rolled along the sea bed.

Question 23

What’s deposition?

Answer 23

When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition.
Deposition happens when the swash is stronger than the backwash and is associated with constructive waves.

Deposition is likely to occur when:
   waves enter an area of shallow water.
   waves enter a sheltered area, eg a cove or bay.
   there is little wind.
   there is a good supply of material.

Question 24

What are the different types of rock and what’s it like?

Answer 24

Sedimentary - weaker than other rock and is found in rivers deposited as layers.

Metamorphic - formed by lots of heat and pressure which morphs the other two types of rock.

Igneous - formed by volcanos when magma is erupted and cooled. They’re hard to erode and weather.

Question 25

What’s the prevailing wind and the fetch?

Answer 25

The most common wind direction.

The fetch is the distance which the wind has travelled.

Question 26

What are concordat and discordant coastlines?

Answer 26

Concordant is when the coastline is made up of the same rock

Discordant is when the coastline is made up of different types of rock; both resistance and non-resistant.

Question 27

What’s the fetch?

Answer 27

The distance of water over which the wind has blown to produce a wave.

The greater the fetch the bigger and more powerful the wave.

Question 28

What are the three types of mass movements that can affect cliffs?

Answer 28

Slides - material shifts in a straight line

Slumps - material shifts with a rotation

Rockfalls - material shifts vertically

Question 29

How do cliffs retreat?

Answer 29

As a result of erosion, weathering and mass movement.

Waves cause most erosion at the foot of the cliff.
This forms a wave cut notch which makes the cliff above the notch unstable.
The part above sea level is also affected by mechanical and chemical weathering making it more unstable until it collapses.

The collapsed material is washed away

Repeated collapsing results in cliff retreating

A wave cut platform is the platform is left behind as the cliff retreats

The rate of this depends on geology and vegetation

Question 30

How do headlands and bays form?

Answer 30

From where erosion resistance is different due to how some types of rock are more resistant to erosion than others e.g. resistant rocks such as chalk are eroded more slowly forming headlands whereas less resistant rock such as clay is eroded quickly which forms a bay.

Question 31

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

Answer 31

From the erosion of headlands.

Waves crash into the headlands and enlarge the cracks.
Repeated erosion and enlargement of the cracks causes a cave to form.
Continued erosion deepens the cave until it breaks through the headland forming an arch.
When it collapses it forms a stack.
This gets worn away to form a stump.

Coves form where there are parallel bands of hard and soft rock.

Question 32

What’s a spit and a bar?

Answer 32

Spit - deposited sand which sticks out into the sea

Bar - a spit which sticks out so far that both ends are connected to mainland.

Question 33

Why protect coastlines?

Answer 33

Economic:
Loss of tourism
Property prices fall
Flooding damages agricultural land

Social:
Deaths
Water supplies affected
Loss of housing
Loss of jobs
Damage to infrastructure 

Environmental:
Ecosystems affected

Question 34

What are the costal management strategies?

Answer 34

Sea wall

Rip rap (boulders piled up along the coast)

Groynes

Revetments (slanted wooden, rock or concrete structures)

Gabions (rock filled cages)

Breakwaters (concrete blocks)

Beach replenishment

Managed retreat