Topic 1 - Coastal Landscapes

Question 1

What is deposition?
What factors lead to it?

Answer 1

Deposition occurs when material being transported by the sea is dropped due to the sea losing energy.
[Occurs on coastlines that have constructive waves]

Factors leading to deposition include:
waves starting to slow down and lose energy
shallow water
sheltered areas, eg bays
little or no wind

Question 2

What is transportation?
What is longshore drift?

Answer 2

Transportation - the movement of eroded material

Longshore drift - a form of transportation. The zigzag movement of sediment along a shore caused by waves going up the beach at a 45 degree angle (swash) and returning at right angles (backwash). This results in the gradual movement of beach materials along the coast. Often controlled by the direction of the prevailing wind.

Question 3

What is erosion?
What are the erosional processes?

Answer 3

Erosion is the wearing away and removal of material by a moving force.

Hydraulic action - process where breaking waves compress pockets of air in cracks in a cliff - pressure can cause widening of cracks = break off rock

Abrasion - rocks carried along by the river grind against the coastline, wearing it down

Attrition - rocks knock against each other, becoming smaller and more rounded

(Solution- this is when sea water dissolves certain types of rocks)

Question 4

What is mass movement?
Describe the 4 different types of mass movement.

Answer 4

Mass movement is the downhill movement of weathered material under the force of gravity.

Rockfall - when fragments of rock fall off the cliff face, (usually due to mechanical weathering)
Landslide - large blocks of weak rock slide downhill
[Mudflow - soil and weak rock flows down a slope]
Rotational slip - saturated soil and weak rock slumps down a curved surface

Question 5

What is weathering?
What is mechanical weathering?
What is chemical weathering?

Answer 5

Weathering: deterioration of rocks, soils and miner

Chemical: decomposition (or rotting) of rock caused by a chemical change within that rock

Mechanical: repeated cycles of freezing and thawing that can make cracks in rock bigger (also known as freeze-thaw)

Question 6

What are the different types of waves and their characteristics?

Answer 6

Constructive waves:
low waves - powerful swash and weak backwash
carry and deposit large amounts of sand and shingle
‘construct’/build up the beach, making it more extensive
wave crests are further apart = lower frequency

Destructive waves:
formed by local storms close to the coast and they can ‘destroy’ the beach.
waves are closely spaced = high frequency and often interfere with each other, producing a chaotic swirling mass of water.
high and steep, powerful backwash.

Question 7

Where are lowland areas primarily found in the UK?
What is the shape of the landscape largely determined by?

Answer 7

Lowland areascan be found in the following places:
the Fens in East Anglia - the lowest place in the UK
the Midlands
the London Basin

Reliefrefers to the way the landscape changes in height. Upland areas are high above sea level. They are often (but not always) mountainous. Lowland areas are not very high above sea level. They are often flat. The shape of the landscape is largely determined by:
glaciation
rivers

Question 8

Where are upland areas mainly found across the UK?

Answer 8

Upland areasare mainly found in:
Scotland- Lots of upland areas, the Northwest Highlands, the Cairngorm Mountains, the Grampian Mountains and the Southern Uplands. Ben Nevis is the UK’s highest peak.
England- The Pennines, Lake District, Dartmoor and Exmoor. Scafell Pike is the highest mountain in England and is found in the Lake District.
Wales- Snowdonia and the Brecon Beacons. Snowdon is the highest mountain in Wales and is found in Snowdonia.

Question 9

Where is the Holderness Coast? Why is it at risk?

Answer 9

The Holderness Coast is in the north-east of England and is one of the most vulnerable coastlines in the world due to being made of soft boulder clay. Coastline retreats st a rate of 1-2m/year putting the lives of over 95,000 people at risk.

In the UK, the Holderness Coast experiences the worst types of erosion, where till deposits have eroded by 120m in the past century.

Question 10

How does the depositional landform of sand dunes change over time?

Answer 10

Moving inland, sand dunes become taller. Embryo dunes (youngest sand dunes) = only a few metres high whereas mature dunes are up to 15m high. = because marram grass + other vegetation colonise the sand dune and hold it together with long roots, stopping the migration of the sand dune.

Sand dunes closer to the beach are more yellow in colour - further away = greyer due to to bacteria from plants and animals being added.

Each sand dune is separated by a trough - known as a slack. Formed from the removal of sediment from the sheltered lee side of the dune and the windward side of the next dune. Slacks can be eroded so much that they reach the water table - result in formation of salty dunes.

Question 11

What is the depositional landform of sand dunes?
What do they need to form?

Answer 11

Sand dunes - coastal sand hills above the high tide mark, shaped by wind action which are found on sandy beaches.

To form, sand dunes need:
Large sandy beaches
Large tidal zones (expose considerable amount of beach between low and high tide, allowing it to dry out - they are lighter and less compact so can be moved more easily)
Gentle beach gradient - so low tide reveals a large body of beach and there is a significant amount of sand to dry out and be moved
Persistent onshore wind to dry sand and move particles by saltation
Constructive, low energy beaches

Question 12

What are the differences between sandy and pebble beaches?

Answer 12

Sandy beaches are usually found in bays where the water is shallow and the waves have less energy. Pebble beaches often form where cliffs are beingeroded, and where there are higher energy waves.

Sandy beach:
flat gradient
low energy
constructive waves
waves do not stretch far inland
sand dunes
ridges and runnels can form on this beach

Pebble beach:
steep gradient
high energy
destructive waves
waves stretch far inland
storm beach with large pebbles
pebbles increase in size at the back of this beach

Question 13

How is the depositional landform of beaches formed?

Answer 13

Beaches are deposits of sand and shingle (pebbles) at the coast. Sandy beaches are mainly found in sheltered bays. The waves entering the bay are constructive waves which build up the beach.

[Ridge - terrace of a beach that has formed in the backshore above the water level at high tide
Runnel - water filled trough during high tide
Ripples - a slight wave in the sand from waves
Beach cusps - shoreline formations made up of various grades of sediment
Berm - wave-swept ridge running parallel to the shore line]

Question 14

How is the depositional landform of beach bars formed?

Answer 14

A beach bar is a spit that has grown across a bay - formed by longshore drift powered by a strong prevailing wind. A beach bar can eventually enclose across the bay to create a lagoon (shallow water protected from a larger body of water by sandbars/coral reefs).

Headlands and bays are formed at discordant coastlines which have alternating coastlines of soft and hard rock. Bays are composed of soft rock and erode quicker.
Longshore drift is the transportation of sediment across a coastline due to the prevailing wind which moves in an easterly direction.
This creates a lagoon enclosed by a beach bar.

Question 15

What is a spit?
How is the depositional landform of spits formed?

Answer 15

A spit is a narrow beach of sand/shingle that are attached to the land at one end. They extend across a bay/estuary or where the coastline changes direction, formed by longshore drift powered by a strong prevailing wind.

Waves approach bend at 45 degree angle (swash) and leave the beach at a right angle due to the prevailing wind = longshore drift!!
The prevailing wind causes sediment to be carried to the land through longshore drift which allows it to build up. The prevailing wind changes direction and curves.
The spit can end abruptly due to a lack of sediment (which gets smaller and smaller), the prevailing wind changing and deeper water. The smaller, lighter sediment is transported further.
Mudflats and saltmarshes (coastal wetlands which are flooded and drained by tides, marshy because of the deep mud) are formed because of the lack of wind and higher shelter from the sea.

Question 16

Stuff not mentioned on the spec - but still useful?
What is wave refraction?
What is the fetch?
What are waves?

Answer 16

Wave refraction is the change in direction of a wave passing from one place to another because of a change in speed, e.g. waves travel faster in deep water.

Fetch - distance of open water the wind travels over. Longer the wind blows = more powerful waves become, therefore larger fetch = more powerful waves.

Waves - movement of water on and off the shore which move in the direction of the prevailing wind.

Question 17

How are the erosional landforms caves, arches, stacks and stumps formed?

Answer 17

Headlands are made of hard rock that have lines of weakness which the sea would erode through the processes of hydraulic action and abrasion (define!).
Over many years, a hollow is cut out which would widen and deepen, through processes like hydraulic action and abrasion - making a cave.
When destructive waves force their way into the cave, the water contains sand and other materials, that grind away at the rock through erosional processes until the cave becomes an arch.
Over time, through constant erosion at the base and weathering at the top, the rocks supporting the arch will weaken, resulting in the arch collapsing and leaving behind a stack.
The stack will be attacked at the base of the cliff, which weakens the structure which will eventually collapse to form a sea stump.

Question 18

How are the erosional landforms of cliffs and wave-cut platforms formed?

Answer 18

Cliffs are shaped througherosionandweathering. Soft rock erodes quickly and forms gentle sloping cliffs, whereas hard rock is more resistant and forms steep cliffs.

A wave-cut platform is an area of bedrock visible at the base of some cliffs. Gently slopes to the sea at and angle of 3-4 degrees. Generally only visible at low tide, bare rock smoothed in places by attrition.

Erosion at the coast is concentrated in one place where high/low tide sea levels are. Hydraulic action and abrasion (define!) erode a notch into the cliff.
Weathering attacks the face of the cliff, making it weaker. Waves hit the bottom of the cliff, eroding a wave-cut notch.
Overtime, the notch will deepen undercutting the face of the cliff and it collapses into the sea, leaving a steep cliff face.
The collapsed rocks are smoothed by abrasion into a platform of rock that overhangs out into the sea.
This process continues and the cliff retreats, creating a wave-cut platform.

Question 19

How does geology and rock type influence coastal forms?
What are the different types of rock?
Where are they found?

Answer 19

Geology is the structure of the Earth, the processes that have shaped that structure and the rocks found in a given location.

Igneous rock - made from lava from cooled volcanoes (ign = ignite)
Sedimentary rock - made from the seafloor from dead animals (sediment = broken rock)
Metamorphic rock - change over time (meta = after, morph = change)

Most sedimentary rock is found in England, Wales and the Republic of Ireland.
Igneous rock is predominantly found in Scotland and Northern Ireland.
Volcanic rock is a large feature of Northern Ireland.
The north west is an anomaly to the rest of England (=sandstone + mudstone)
The majority of metamorphic rock is found in north-western Scotland on the islands.

Question 20

How is the erosional landform of headlands and bays formed?

Answer 20

Cliffs along the coastline do not erode at the same pace.
Abayis a crescent-shaped indentation in the coastline found between two headlands - usually has a beach. Comprised of soft rock, like sand and clay.
A headland is a cliff that juts out into the sea. Composed of hard rock, like granite, chalk or limestone.

Headlands and bays occur at discordant coastlines (coastline formed from different types of rock) where waves attack, meaning hydraulic action and attrition (define!) cause the cliff to retreat.
Weaker, less resistant rock, like clay, erode more easily to form bays. As the bays are sheltered with constructive waves, deposition takes place and forms sandy beaches.
The tougher more resistant rock, like limestone and chalk, erode less quickly. They stick out into the sea to form headlands.

Erosional features such aswave-cut platformsand cliffs can be found on headlands, since they are more open to the waves.

Question 21

What are the factors affecting coastal erosion?

Answer 21

Waves: erosion experienced on coast is influenced by size + type of waves reaching it - stronger (destructive) waves cause a higher rate of erosion.

Rock type: Harder, more resistant rock like granite erodes more slowly compared to weaker rocks like clay - stronger rock reduces erosion rate.

Beaches: absorb wave energy + reduce impact of waves on a cliff - no beach = faster erosion.

Subaerial processes - weathering + mass movement will weaken cliffs, therefore less resistant to erosion by waves

Question 22

What were the different coastal management strategies at the Holderness Coast?
How much did they cost, where were they implemented?
How do they work and what are the disadvantages?

Answer 22

Groynes at Hornsea:
£5.2 mill
slows down erosion by trapping sediment transported by longshore drift, building up the beach and reducing their energy = less erosive
causes erosion at Mappleton as sand is no longer carried there via longshore drift

Sea wall at Hornsea:
£6.4 mill
curved face throws wave back to sea slowing down next wave, so less erosive
caused erosion at Mappleton as powerful waves moved along the coast

Beach nourishment at Mappleton:
£2.1 mill
sand added to beach = bigger so slows down waves, making them less erosive
protection was failing and cliffs slumped - erosion increased

Rock armour at Withernsea:
£6.3 mill
water enters gaps in boulders, releases pressure and reduces wave energy = less erosive
reduced access to beach + increased wave noise

Question 23

Why is the Holderness Coastline eroding so quickly?

Answer 23

The Holderness coastline is located on the east coast of England. It is the fastest eroding coastline in Europe.

The coastline is rapidly eroding at an average of 1.8 metres a year. There are several reasons why the coast at Holderness is eroding so quickly:
Rock type- the cliffs are made from less-resistant boulder clay (made from sands and clays) which slumps when wet.
Naturally narrow beaches- these beaches give less protection to the coast as it doesn’t reduce the power of the waves.
Man-made structures-groyneshave been installed to stop long-shore drift. This narrows unprotected beaches elsewhere even more.
Powerful waves- waves at Holderness travel long distances over the North Sea (so have a long fetch) which means they will increase in energy.

Question 24

What is managed retreat?
What are the advantages and disadvantages?

Answer 24

Managed retreat:
Managed retreatis the controlled flooding of low-lying coastal areas. If an area is at high risk of erosion, managed retreat could be an option. It usually occurs where the land is of low value, for example farm land.

Advantages
This is a cheap option compared to paying for sea defences.
Creates a salt marsh which can provide habitats for wildlife and a natural defence against erosion and flooding.
Salt marshes are diverse ecosystems supporting many species.

Disadvantages
Land is lost as it is reclaimed by the sea.
Landowners need to be compensated - this can cost between £5,000 - £10,000 per hectare.

Question 25

What is the soft engineering strategy of sand dune protection?
What are its positives and negatives?

Answer 25

Sand dune protection:
Marram grassplanted on sand dunes stabilises the dunes and helps to trap sand to build them up.

Advantages
Relatively cheap.
Maintains a natural-looking coastline.

Disadvantages
Can be damaged by storm waves.
Areas have to be zoned off from the public, which is unpopular.

Question 26

What is the soft engineering strategy of beach reprofiling?
What are its positives and negatives?

Answer 26

Beach reprofiling:
The sediment is redistributed from the lower part of the beach to the upper part of the beach.

Advantages
Cheap and simple.
Reduces the energy of the waves.

Disadvantages
Only works when wave energy is low.
Needs to be repeated continuously.

Question 27

What is the soft engineering strategy of beach nourishment?
What are its positives and negatives?

Answer 27

Beach nourishment:
Sand is pumped onto an existing beach to build it up.

Advantages
Blends in with the existing beach.
Larger beaches appeal to tourists.

Disadvantages
Needs to be constantly replaced.
The sand has to be brought in from elsewhere.

Question 28

What is the hard engineering strategy of rock armour?
What are its positives and negatives?

Answer 28

Rock armour (rip rap):
Large boulders placed at the foot of a cliff. They break the waves and absorb their energy.

Advantages
Cheaper than a sea wall - £1000-£3000/m and easy to maintain.
Can be used for fishing.
Cause less visual pollution over time + increase biodiversity

Disadvantages
They look different to the local geology, as the rock has been imported from other areas.
The rocks are expensive to transport.
Can make getting onto the beach difficult

Question 29

What is the hard engineering strategy of sea walls?
What are its positives and negatives?

Answer 29

Sea walls:
Concrete walls that are placed at the foot of a cliff to prevent erosion + extra stability. They are curved to reflect the energy back into the sea.

Advantages
Effective at protecting the base of the cliff.
Sea walls usually have promenades so people can walk along them.
75 year lifespan.
Sense of security + effective.

Disadvantages
Waves are still powerful and can break down and erode the sea wall.
Expensive - approximately £5,000 per metre.
Constant maintenance
Visual pollution + prevent access to the beach

Question 30

What is the hard engineering strategy of gabions?
What are its positives and negatives?

Answer 30

Gabions:
Rocks are held in mesh cages and placed in areas affected by erosion.

Advantages
Cheap - approximately £100 per metre.
Absorbs wave energy.
If placed next to a cliff - can give stability + reduce landslide risk.
Last 20-25 years
Can be covered by sand/vegetation to blend in

Disadvantages
Not very strong.
Looks unnatural.
Constant maintenance needed.
Only last 5-10 years before rust.

Question 31

What is hard engineering strategy of groynes?
What are its positives and negatives?

Answer 31

Groynes:
Groynesare wooden or rock structures built out at right angles into the sea.

Advantages
Builds a beach - which encourages tourism.
They trap sediment being carried by longshore drift.
Last up to 40 years.
£400/m

Disadvantages
By trapping sediment it starves beaches further down the coastline, increasing rates of erosion elsewhere.
They look unattractive.
Need regular maintenance.

Question 32

What is coastal management?
What is the difference between hard and soft engineering?

Answer 32

Coastal management are strategies that stop or slow down erosion at the coastline from rising sea levels and an increase in storms.

Hard engineering = man-made structures control the sea to reduce erosion - normally more expensive but last longer, e.g. groynes, gabions, sea walls and boulder barriers.

Soft engineering = using knowledge of the sea to reduce the effects of erosion and these are normally cheaper but need constant maintenance, e.g. beach reprofiling, nourishment, dune regeneration and managed retreat.