Coasts Flashcards
(78 cards)
1
Q
What are the five oceans?
A
Pacific Ocean
Atlantic Ocean
Indian Ocean
Southern Ocean
Artic Ocean
2
Q
What is swash?
A
Water rushes up the beach
3
Q
What is backwash?
A
Water retreats back due to gravity
4
Q
How are waves formed?
A
Waves are formed by the wind blowing over the sea
5
Q
What is the size of the waves influenced by?
A
- Fetch (length of the water the wind blows over)
- Strength of the wind
- How long the wind blows
6
Q
What are constructive waves?
A
Strong swash, weak backwash
Build up wide flat beaches
Sediment left or beach which makes it bigger
7
Q
What are destructive waves?
A
Strong backwash, weak swash
Make narrow, steep beaches Sediment left
Very little sediment carried up but a lot taken back to make small beaches
8
Q
What is weathering?
A
Weathering is the breakdown of rock in-situ (in place)
9
Q
What are the three types of weathering?
A
Chemical weathering
Mechanical weathering
Biological weathering
10
Q
What is chemical weathering?
A
It is caused by a chemical reaction when rainwater hits a rock and breaks it down.
Process:
1. Rock dissolved or weakened
2. Acid attacks rocks. Rainwater contains weak acid.
3. Rocks are worn away or broken
11
Q
What is mechanical weathering?
A
Rocks being disintegrated - usually caused by extreme temperatures.
Process:
1. Rocks fall to pieces
2. Water gets into cracks
3. Crack opens up
4. Water freezes
12
Q
What is biological weathering?
A
Rocks being broken apart by living things (e.g. plants, tree roots)
Process:
1. Rocks collapse or fall apart
2. Rocks loosened and broken up
3. Rocks undercut and crack
13
Q
Describe Slumping
A
Rain seeps through permeable rock such as sandstone. At the junction where the permeable rock meets impermeable rock, such as clay, the saturated soil and a weaker rock slumps in a rotational manner along a curved surface
14
Q
Describe sliding
A
The movement of material occurs along a flat surface, usually a bedding plane.
Large amounts of rock and soil can move downslope rapidly and can cause a lot of damage.
15
Q
Describe rockfall
A
When fragments of rock are weathered or eroded and fall from the cliff as while parts.
16
Q
What is geomorphology?
A
The shape and structure of the land.
17
Q
What is a concordant coastline?
A
Rocks are parallel to the wave front and therefore rates of erosion are similar along the coastline.
18
Q
What is a discordant coastline?
A
Differential erosion may occur, where bands of hard and soft rock outcrop at right angles to the sea.
19
Q
What factors might make erosion rates higher?
A
— strong winds
— an area with no beach to buffer the waves
— outcrops of rock (headlands) junting out to the sea being very exposed
— winds that have been blowing for a long time
— faults/joints in rocks
20
Q
How does a stump form?
A
- Large crack, opened up by hydraulic action
- The crack grows into a cave by hydraulic action and abrasion
- The cave becomes larger
- The cave breaks through the headland forming a natural arch
- The arch is eroded and collapses into a stack
- The stack is eroded forming a stump
Examples: Old Harry, Durdle Door
21
Q
What are wave-cut platforms?
A
When waves break against a cliff, erosion close to the high tide line will wear away and the cliff will form a wave cut notch.
Eventually the overlaying cliff can no longer support its own weight and it collapses.
The cliff will gradually retreat.
22
Q
What is traction?
A
Traction is material which is rolled along the bed (rolling stone).
23
Q
What is saltation?
A
Saltation is the material which moves by bouncing along the seabed.
24
Q
What is solution?
A
Solution is dissolved material carried in solution.
25
What is suspension?
Suspension is when material light enough to be carried in the sea’s current without hitting the bed.
26
What is longshore drift?
Longshore drift is a process of transportation that shifts eroded material along the coastline.
27
What is deposition and when does it occur?
Deposition is the laying down (dropping) of material.
It occurs when:
-Shallow
-Calm
-Sheltered
-Low energy
28
What is deposition?
Deposition is when material being carried by the sea water is dropped on the coast.
29
What is a beach?
A beach is an example of a depositional landform. It is a large deposit of sediment which can be either pebbles or sand.
30
Where is Lyme Regis?
Lyme Regis is a small costal town on the cough coast of England. It is in Dorest and it lies on the Jurassic Coast.
31
What are the issues at Lyme Regis?
Due to powerful waves the coastline is eroding from the south west. The sea walls have been breached many times as a result of this many properties have been destroyed or damaged.
32
Give an example of soft engineering found at Lyme Regis
Beach nourishment
33
Give an example of hard engineering found at Lyme Regis
Sea Wall
Groynes
Rock armour
34
What happened in phase one of the Lyme Regis coastal protection scheme?
It started in the 1990’s. They built a new sea wall and promenade to the east of the mouth of the river.
In 2003-2004 a £1.4 million emergency project was completed to stabilise the cliffs.
35
What happened in phase two of the Lyme Regis coastal protection scheme?
In 2002-2007. Cost £22 million. Constructed new sea wall and promenade. Creation of wide sand and shingle beach to absorb wave energy and increase the use of the shore; came from France and English Cannel.
Rock armour was used to absorb wave energy and help retain the new beach.
36
What happened in phase three of the Lyme Regis protection scheme?
The initial plan was to help prevent landslips and coastal erosion to the west of the cobb. It was decided to leave this alone as it was too expensive for the little benefits.
37
What was phase four of the Lyme Regis coastal protection scheme?
2013-2015. Cost £20 million. Constructed a new 390 m sea wall in front of the existing one.
Extensive nailing piling and drainage to provide cliff stabilisation to protect 480 homes for the next 50 years
38
When was the Lyme Regis coastal protection scheme finished?
2015
39
What are the positives of the Lyme Regis costal protection scheme?
The new sea defences have stood up to recent stormy winters.
The harbour is now better protected benefiting but boat owners and fisherman.
Overall, this scheme is expected to protect approximately 480 homes for the next 50 years.
The new beaches have increased visit numbers and seafront businesses are thriving.
Stabilising cliffs will prevent landslips.
40
What are the negatives of the Lyme Regis costal protection scheme?
Increased visitor numbers have led to conflict with the local people who think that traffic congestion and litter have increased.
Some people think the new defences have spoiled the natural coastal landscape.
The new sea wall may interfere with coastal processes and affect neighbouring stretches of coastline causing conflict elsewhere.
The prevention of landslips may stop the cliff from revealing important fossils.
41
Where is Medmerry?
Medmerry is in West Sussex which is in South-East England and it is near Selsbury. It was the largest managed coastal realignment scheme in Europe.
42
What are the positives of Medmerry managed retreat?
The scheme means that existing species such as water voles, crested newts and badges will be protected.
The newly flooded area is expected to become an important fishing nursery that will boost the local fishing industry in Selsey.
A maintenance access track behind the environment provides a cycle route and footpath.
Selsey now has a 1 in 1000 chance of coastal flooding which provides the best level of protection in the UK.
Mudflats, salt marshes and transitional grasses have already attracted large numbers of ducks lapwings. The area is turning into a huge nature reserve managed by the RSPB.
Tourism, a main contributor to the local economy, is expected to increase. Two new car parks and four viewing points give easy access.
43
What are the problems with the Medmerry managed retreat scheme?
Locals didn’t agree with giving up land
Some habitat/species were impacted, e.g. badges
Farmers didn’t agree as agricultural land was lost e.g. three farms abandoned
Very expensive as it cost £28 million whereas maintenance of the sea wall was only £0.2 million a year.
44
Why was the Medmerry management scheme needed?
This was to protect the homes in Selsey and the roads between the big towns. Also a lot of money was lost last time it happened.
45
What was put in place in this scheme?
—New embankment, up to 2km inland from the shore
—Extra channel built along its whole length to collect draining water
—Rock armour and more sand added, this allows the sea to flood the land to create a new intertidal area
—60,000 tonnes of hard rock from Norway to make the rock armour, this was placed on the seaward edges of the embankment
46
When was the Medmerry management scheme?
The work to realign the coast began in 2011
It was finished in 2014
47
What would happen if this was breached?
If breached then 348 properties in Selsey, a water treatment plant and the main road between Chichester and Selsey would be flooded. The last breach, in 2008, caused £5 million of damage.
48
What are the features of a pebble beach?
Dominated by destructive waves
Stretches short distances inland
Steep gradient
Contains a storm beach with large pebbles
49
What are the features of a sandy beach?
Dominated by constructive waves
Stretches far inland
Shallow gradient
Contains sand dunes
50
What is a beach profile?
It is the side profile of a beach
51
What is a sand dune?
A sand dune is a coastal hill above the high tide mark, shaped by wind
52
What do sand dunes need to form?
:A large flat beach
:A large supply of sand
:A large tidal range
:An obstacle such as driftwood for a dune to form against
:Onshore wind
53
How does a sand dune form?
1. Embryo dune- youngest dune(few months), obstide slowes down wind causing deposition, prickly salt water -> stabilises sand
2. Foredune- Salt-tolerant vegetation e.g Lyme grass
3. Yellow dune- 30-40 years old, marram grass, yellow sand
4. Grey dune- More diverse vegetation, more nutrients in soil, mosses, permanent
5. Mature dune- A kilometre inland, shrubs, woodland, lots of hummus in soil, 250+ years old
54
What is a spit?
A spit is an extended stretch of beach material that only joins the mainland at one end.
55
What is a bar?
If a spit joins one part of the mainland to another, it is called a bar.
It creates a lagoon( area of water dammed by the bar )
56
What is a tombolo?
A tombolo is formed when a spit extends out to sea from the mainland and joins itself to an island
57
Where is Swanage?
It is in the south of UK
County of Dorset
Located near Southampton
South of Studland bay
58
What are the depositional landforms in Swanage?
Large sheltered bay. Two spits are found in Poole Harbour. There are lagoons, salt marshes and sand dunes in this area
59
What is the coastline like in Swanage?
It has a discordant coastline. So it has different bands of hard and soft rock. South coast only has one type of hard rock (lime rock).
Studland Bay- soft
Ballard Point- hard
Swanage Bay- soft
Durlston Bay- hard
60
What erosional landforms are in Swanage?
Old Harry rocks found two miles north east of Swanage, the rocks are made of chalk and are constantly eroding
61
Why do humans visit Swanage?
Swanage attracts tourists all year round but most people go in summer because you can: go walking, go cycling, go paddle boarding, go canoeing, go fossil hunting
62
What is the climate like in Swanage?
Swanage experiences a maintime climate with warm (but not hot) summers and cool winters. It rains most in December and January
63
What is hard engineering?
Hard engineering is when solid man-made materials (like steel or concrete) are used to protect the rocks from erosion by waves. It is usually very costly.
64
What are the features of hard engineering?
- Damage to the environment
- Expensive
- Man-made
65
What are the different types of hard engineering?
Rock armour/Rip-rap
Gabions
Groynes
Sea wall
Revetment
Off-shore break water
66
What is Rock armour/ rip-rap and what are the positives and negatives?
It is made from granite or other hard rocks. It is placed at the bottom of cliffs to absorb energy of waves but let water drain through.
Positive:
- Relatively cheap
- Natural resource
Negatives:
- Some erosion takes place
- Looks ugly
- Easily moved by waves
67
What are gabions and what are the positives and negatives?
They are wire cages filled with boulders, rear the beach to keep it together.
They protect from erosion and cause sand dunes.
Positives:
- Last 5-10 years
- £50 per cubic metre
Negatives:
- Cages can rust
- Easily destroyed
68
What are Groynes and what are the positives and negatives?
They are wooden fences or walls made from piles of rocks built out into sea.
Positives:
- Last 30-40 years
- Reduce rate of long-shore drift
- Extra beach protects the coast from the sea
Negatives:
- Can cause erosion rates to increase further down the coat
- Cost £1000 per metre for wooden
- Cost £1000 per cubic metre for rock
69
What is a sea wall and what are the positives and negatives?
It is a concrete barrier along the coast which absorbs the energy of the waves.
Some are curved to deflect power of waves.
Positives:
- Protects coastline very effectively
- Last around 100 years
Negatives:
- Need maintenance which is very expensive
- Initially very expensive
- Not nice to look at
70
What is revetment and what are the positive and negatives?
It is a sloping concrete or wooden defence facing the sea that absorb wave energy.
They also trap beach material.
Positives:
- Wooden last 10 years
- Concrete last 30 years
Negatives:
- Less durable that sea wall
- Need replacing often
- Not give enough protection
- Expensive
71
What is off-shore break water and what are the positives and negatives?
They are built parallel to coast, off the from rock.
Force waves to break before they reach shore.
Positives:
- Reduce wave energy
- Do not spoil beach
- Very effective
Negative:
- Expensive (£1.3 million)
- Tricky to maintain as out at sea
72
What is soft engineering?
Soft engineering is a sustainable and cheap way of protecting the coast from erosion. It works with natural processes within an area.
73
What are the different types of soft engineering?
Managed Retreat
Beach recycling
Sand dune regeneration
Beach replenishment
Beach profiling
74
What is managed retreat and what are the positives and negatives?
It allows the coat to take back the land, by removing existing sea defences and allowing the land behind them to flood.
Positives:
- Land will become marsh land allowing habitats to form
- This marshland will act as a natural sea defence
- It is cheap
Negatives:
- Land floods
- Erodes more
75
What is beach recycling and what are the positives and negatives?
Involves moving material from one end of the beach where it has been deposited back to the other, eroded, end.
Positives:
- Only three times a year
- No material is needed to be dredged from the sea
- Ensures an even beach profile
Negatives:
- Maintenance is costly
- Putting large trucks in beach disturbs costal wildlife and puts tourists off going
- Economical impacts
76
What is sand dune regeneration and what are the positives and negatives?
Artificial sand dunes created or restoration of existing sand dunes. Act as a physical barrier between sea and land.
Positives:
- Protect land behind them
- Popular picnic and walking area
- Cheap
- Voluntary
Negatives:
- No guarantee that they are stable
- Can be damaged by storms
- Short life
- Need to be checked twice a year
77
What is beach replenishment and what are the positives and negatives?
It is the process by which sand is replaced along the beach.
Positives:
- More effective at dispersing waves energy
- It replaces the material lost by long-shore drift
- Avoids negative effects of hard engineering structures
Negatives:
- Not prevent long-shore drift
- Expensive
- Carried out regularly
- Kills marine life
78
What is beach profiling and what are the positives and negatives?
It is the shaping of the land in a particular way so that it absorbs more energy during storms. Bulldozers give it a gentle curve to reflect wave energy.
Positives:
- Natural look
- Cheap
Negatives:
- Noisy
- Scare wildlife
- Carry out regally
