Coastline

Question 1

What’s mechanical weathering?

Answer 1

The break up of rocks without any chemical changes occurring. Usually resulting in piles of rock fragments called scree found at foo of rocky outcrops

Question 2

Define chemical weathering

Answer 2

When a chemical change takes place when weathering occurs. Acidic rainwater slowly dissolve soft rocks such as limestone/chalk. Minerals left behind form clay deposit

Question 3

What’s biological weathering?

Answer 3

The actions of Flora and fauna. Eg: Plant roots grow and expand in rock cracks. Rabbits can burrow into weak rock (i.e: sand)

Question 4

Freeze - Thaw

Answer 4

Water find it’s way into cracks when waves and rain water find their way into cracks. It freezes and thaws as temperatures fluctuate. This process repeats and gradually weakens the rock until sections break away from the cliff face

Question 5

Mass movement

Answer 5

The downhill movement of material under the influence of gravity

Question 6

Effects of mass movement

Answer 6

• people are evacuated
• houses/businesses destroyed
• roads/public services damaged

Question 7

What is Rockfall?

Answer 7

fragments of rock break away from the cliff face (often due to freeze thaw)

Question 8

What is a landslide?

Answer 8

Blocks of rock slide downhill

Question 9

Mudflow

Answer 9

Saturated soil and weak rock flows down a slope

Question 10

Rotational slip

Answer 10

Slump of saturated soil and weak rock along a curved surface

Question 11

How are waves formed?

Answer 11

Waves are a result of wind blowing over the sea. Friction with the surfaces causes ripples to form and these turn into waves.

Question 12

What does wave energy depend on?

Answer 12

It depends on the fetch (the distance which the wind has blown over) , the strength of the wind and the length of time over which the wind has blown

Question 13

Compare the two types of waves

Answer 13

Constructive
- low in proportion to height
- shape is spilling 
- strong swash, weak backwash
- build up beach 
- summer season
-less than 11 per minute 
Destructive
- high in proportion to length
- shape is plunging
- weak swash, strong backwash!
- erode beach
- winter season
- 13+ per minute

Question 14

What are the four types of erosion?

Answer 14

Hydraulic action
Corrosion
Attrition
Abrasion

Question 15

Hydraulic action

Answer 15

The impact of a wave on a cliff face, air is forced into cracks under high pressure which widens them. Over long periods of time, the growing cracks break parts of the rock off

Question 16

Corrosion

Answer 16

Carbon dioxide in the atmosphere is dissolved into water which causes a weak carbonic acid to form. When the water hits the rocks, this erodes the material. Acidic rain also plays a part in this.

Question 17

Attrition

Answer 17

Beach material is knocked together in the water, which reduces their size and they become smoother and rounder

Question 18

Abrasion

Answer 18

The repeated action of waves breaking on a cliff is enough to remove material from it over time. The sand and shingle in the water acts like sandpaper so erosion takes place faster

Question 19

What four factors effect coastal erosion?

Answer 19

Rock type - some rocks easily erode

Fetch - the larger the fetch the more wave energy..so more erosion

Type of wave - destructive waves have a steep angle of break and have lots of energy

Shape of coastline - certain areas (eg: bays) are more sheltered by headlands so erosion is slower

Question 20

What are the main coastal features caused by erosion?

Answer 20

1: headlands and bays
2: caves, arches and stacks
3: wave cut platforms

Question 21

How are headlands and bays formed?

Answer 21

• alternating layers of (non)resistant rock at right angles to the coast
• less resistant rock erodes quicker which forms a dent in coastline (bay)
• more resistant rock to the north and South are eroded more slowly hence the coast at theses points protrudes into the sea (headlands)

Question 22

Explain the process of caves, arches and stacks

Answer 22

1: the headland is made of resistant rock with natural cracks/ joints in it
2: the breaking waves exploit the cracks and erode them through hydraulic action & corrosion until small caves form
3: the sea continues to erode caves so they get larger. The caves on either side of the headland erode backwards until they meet in the middle to form an arch
4: the sea keeps eroding the arch which becomes larger until the roof collapses and forms a stack
5: the headland retreats and new caves are forming all the time

Question 23

Definition of:

• cave
• arch
• stack

Answer 23

Cave - a hollowed out feature at the base of an eroding cliff

Arch - a headland that’s been partly broken through by the sea to form a thin roofed arch

Stack - an isolated pinnacle of rock sticking out of the sea at the end of a headland

Question 24

Explain how a wave cut platform is formed

Answer 24

When waves break against the cliff face near the high tide line, the rock is attacked by the processes of erosion which form a wave-cut-notch. Over time and repetition the notch deepens and the overlying cliff collapses under the influence of gravity. Over time the cliff line retreats and extending seawards from the base of the cliff will be a rocky, gently sloping platform called a wave cut platform.

Question 25

What is weathering?

Answer 25

The break up and decay of exposed rock at the Earths surface

Question 26

What is longshore drift?

Answer 26

The transport of sediment along a stretch of coastline caused by waves approaching the beach at an angle

Question 27

Which direction does backwash flow during longshore drift

Answer 27

At right angles to the cliff due to the force of gravity

Question 28

Main landforms of costal deposition

Answer 28

1- Beaches 2- Spits 3- Tombolos and Bars

Question 29

What is coastal deposition?

Answer 29

When the sea loses energy and deposits sand, rock particles and pebbles that it's been carrying.

Question 30

When is coastal deposition likely to occur?

Answer 30

It's often associated with constructive waves and is likely to occur when waves enter shallow water or an area of shelter and no wind. This is because it's the times when waves lose energy

Question 31

What are beaches and what are the main sources of material?

Answer 31

``` Beaches are made up of material lying between the high & low tide mark. Sources: - cliff erosion - constructive waves - longshore drift ```

Question 32

What is it called when waves enter a bay and mirror the shape of the coastline?

Answer 32

Wave refraction

Question 33

What does wave refraction result to?

Answer 33

Wave refraction spreads out and reduces wave energy so deposition occurs.

Question 34

What is a tombolo?

Answer 34

It's a spit connecting an island to the mainland. It's an accumulation of sand and shingle.

Question 35

What is a bar? What feature will it create?

Answer 35

And accumulation of sand and shingle (also known as spit) that blocks off a bay or river mouth. It will create a lagoon around it.

Question 36

Why is the sea level rising and at what rate?

Answer 36

- Global warming! - 2mm per year - 20 in past century

Question 37

Name some effects of Coastal flooding

Answer 37

``` Economic: - loss of tourism - damage repair - loss of agricultural land Social: - deaths - water supplies affected - loss of housing/businesses (jobs) Environmental: - ecosystems affected - vegetation killed - increased erosion ```

Question 38

What's the cause of cliff collapse?

Answer 38

The rocks that make up the cliff are weak and easily eroded by the sea. Also permeable sands sit on impermeable clay which means when water infiltrates into the cliff, it will 'pond up' when it reaches the layers of clay. Over time the weight of the cliff increases and so it will collapse.

Question 39

What is - hard engineering - soft engineering

Answer 39

Hard engineering - building artificial structures such as sea walls aimed at controlling natural processes Soft engineering - a sustainable approach to managing the coast without using artificial structures

Question 40

Examples of hard engineering. What are they

Answer 40

Sea wall - curved concrete/rock barrier placed at base of cliffs or top of a beach which reflects the waves back into the sea Groynes - Timber/rock structures built out to sea from the coast at 90degrees. They trap sediment being moved by LSD. So the beach area is increased Rock armour - pile of large boulders dumped at foot of cliff. They absorb the waves energy, protecting cliffs

Question 41

Examples of soft engineering. What are they?

Answer 41

Beach nourishment - addition of sand to existing beach to make it higher or broader. Dune regeneration - sand dunes act as buffers to the sea. Marram grass is planted to stabilise them Marsh creation - Allowing low lying coastal areas to be flooded by the sea to become salt marshes that act as barriers to the sea.

Question 42

Advantages & disadvantages of hard engineering process. - sea wall - groynes - rock armour

Answer 42

Sea wall - expensive! (6m per km), looks unnatural but very effective Groynes - not too expensive (£10,000 each at 200m intervals). Forms bigger beach for tourism:) starve beaches downdrift causing erosion in other places Rock armour - £1000/4000 per metre. (Quite cheap) easy to maintain. Expensive to transport. Obtrusive

Question 43

Benefits and drawbacks of soft engineering processes - beach nourishment - dune regeneration - marsh creation

Answer 43

Beach nourishment - quite cheap (3000 per m), blends in, bigger beach so tourism increase. Needs constant maintenance Dunes - cheap (2000 per m), natural! Time consuming, damaged by storms Marsh creation - cheap option, crates habitat for wildlife, farming land is lost

Question 44

Cost of schemes per 1km

Answer 44

Sea wall - 6 million Groynes - 50,000 Rock armour - 1-4 million Beach nourishment - 3 million

Question 45

How is a salt marsh formed?

Answer 45

- start as accumulation of mud in a sheltered coastal area (eg: behind spit) - as more sediment builds up, mud level rises so becomes less covered in water - improves fertility of soil - plant species colonise (vegetation succession)

Question 46

Describe impacts of sea level rising in maldives

Answer 46

- 350,000 people would evacuate - wildlife (180 bird species, 18 dolphin species, 1000 fish species) - TOURISM LOSS - job losses (fishing community)