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Geography > 10. Coastal Landscapes > Flashcards

10. Coastal Landscapes Flashcards

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1
Q

what factors is the height and stregnth of a wave dependent on?

A
  1. the fetch of the wave (the distance the wind blows over the sea)
  2. the amount of time the wind blows
  3. the stregnth of the wind
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2
Q

What are the properties of a constructive wave?

A
  • larger swash than backswash, so sediment is deposited on the beach
  • low frequency waves
  • wave height is low
  • wavelegnth is long
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3
Q

what are the properties of destructive waves?

A
  • weak swash, strong backswash, so sediment is taken from the beach
  • short wavelegnth
  • waveheight is high
  • high frequency waves
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4
Q

What is weathering?

A
  • the breakdown of rock in the original place
  • does not involve movement of rock
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5
Q

What is mechanical weathering and give an example

A

**- mechanical weathering is where the rock is physically broken up **
- an example is freeze-thaw weathering
- this is where water gets into the cracks between rocks
- when night comes, the water freezes and due to the negative thermal expansion of water it expands putting more pressure on the cracks
- the water then thaws
- this cycle continues until parts of the rock are broken off

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6
Q

what is chemical weathering and give an example

A

**- chemical weathering is the breakdown of rocks using a chemical process **
- an example is acid rain (due to the carbon dioxide in the clouds)
- the rainwater is slighlty acidic and this causes some types of rock (limestone) to weather away
- the hotter the temperature, the faster this happens

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7
Q

what is biological weathering and can you give an example?

A

**- biological weathering is when living animals wear out rocks **
- trees and other plants can grow between cracks in rocks
- over time the roots and the trees will break the rock
- rabbits can also put pressure on a rock

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8
Q

What is mass movement?

A
  • mass movement is the movement of material under the influence of gravity
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9
Q

What is this mass movement (mudflow)

A
  • occurs on slopes betwene 5 and 15 degrees
  • usually happens after soil has been saturated with flow of water across the surface
  • vegetation is also carried away
  • soil literally flows away
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10
Q

What is this mass movement (rockfall)

A
  • rockfall is caused by the slopes being steep, and is where the rocks simply fall down the cliff due to something
  • caused by:
  • extreme weathering (freeze-thaw)
  • rainfall
  • earthquakes
  • hot weather drying the soil
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11
Q

What is this mass movement (landslide)

A
  • the movement of materials all together
  • this is where blocks of rock slide downhill
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12
Q

What is this mass movement (rotational slumping)

A
  • usually found in weaker rock types like clay that become saturated and heavy
  • large area of land moving in 1 piece and leaves a slump indentation
  • the saturated soil slumps over a curved surface
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13
Q

What are the 4 types of erosion

A
  • solution
  • abrasion
  • attrition
  • hydraulic power
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14
Q

what is this type of erosion (solution)

A
  • this is where soluble chemicals are dissolved in rocks, e.g limestone
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15
Q

what is this type of erosion (hydraulic power)

A
  • the sheer force of the water waves when they hit the rocks
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16
Q

what is this type of erosion (abrasion)

A
  • abrasion is the sandpapering effect of sediment from the waves grinding over the rocks
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17
Q

what is this type of erosion (attrition)

A
  • materials in the waves bump against each other and become more rounded
  • this forms shingle and sand
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18
Q

what are the 4 types of transportation?

A
  • solution
  • suspension
  • traction
  • saltation
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19
Q

what is this type of transportation (solution)

A
  • solution is dissolved material carried in the water
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20
Q

what is this type of transportation (suspension)

A
  • this is where smaller sediment is held in the water and taken along with the waves
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21
Q

what is this type of transportation (saltation)

A
  • larger pieces of sediment are bounced up and down the ocean floor as they are too heavy for suspension
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22
Q

what is this type of transportation (traction)

A
  • this is where the the heaviest sediment is rolled along the ocean floor using the energy of the waves
23
Q

What is longshore drift?

A
  • waves approach the beach at an angle due to prevailing wind but come back perpendicular
  • therefore sediment is moved along the beach due to longshore drift but in the direction of the prevailing wind
24
Q

what direction is UK prevailing wind?

A

SOUTH WEST

25
Q

What is wave refraction?

A
  • This is where the waves hits the headland, but the water near is a headland is shallower
  • so there is more friction in the wave causing the wave to bend and lose energy
  • so the lower energy waves hit the bay, causing them to become constructive waves, which means they deposit their sediment on the beach either side of the headland
26
Q

When does coastal deposition occur?

A
  • when the waves lose energy and can no longer carry sediment, so they deposit and beaches are made
27
Q

What is a discordant coastline?

A

Where the coastline is made of different types of rock, meaning erosion is conducted at different rates, usually leading to bays and headlands

28
Q

What is a concordant coastline?

A

This is where the coastline is made of one type of rock, meaning erosion is conducted at the same rate, for example the south coast of England

29
Q

What are bays and why are they formed?

A
  • Bays are usually areas of rock types on a discordant coastline that erode faster compared to other rock types
  • this leads to indents in the coastline where beaches are formed due to wave refraction
  • the beach is sheltered due to the headland taking the high energy so there are beaches here.
30
Q

What are headlands and why are they formed?

A
  • Headlands are areas of rock types on discordant coastlines that erode slower compared to other rock types
  • leading to parts that jut out in the coastline, there are no beaches here.
  • Some stronger rocks include limestone and sandstone.
31
Q

Explain CASS in 5 steps

A
  1. Cracks in the rock form due to erosion, abrasion, or freeze thaw weathering or something similar
  2. The energy from the waves erode the crack and make it into a cave through abrasion and hydraulic action
  3. Over time the cave is eroded on both sides to create an arch
  4. The arch is eroded to a point that the roof is not supported and falls down creating a stack
  5. The stack is eroded the same way a wave cut platform is eroded, over time just leaving a stump
32
Q

What is a wave cut notch?

A

This is where the waves erode a notch in the cliff at high tide, through the process of abrasion, and over time will carve a notch into the cliff.

33
Q

What is a wave cut platform

A

After the wave cut notch has been formed, the cliff underlying cannot be held up, so it collapses (ROCKFALL). There is a layer of harder rock underneath which is exposed at low tide.

34
Q

How are beaches formed?

A
  • deposits of sand and shingle in sheltered bays (between headlands)
  • made by constructive waves
  • pebble or sand
35
Q

How are sand dunes formed?

A
  1. embryo dunes form around deposited obstacles such as wood or rock
  2. develop to form fore dunes and yellow dunes (stabilised by marram grass which holds sand together and stabilises dune)
  3. rotting vegetation makes sand more fertile and plants take over back dunes
  4. winds form depression which can form dune ponds
36
Q

how are spits formed?

A
  • forms on coasts with major longshore drift when the coastline bends sharply
  • sediment is the deposited out to the sea which keeps going as the spit gradually grows out to the sea
  • winds and current can cause a recurved end
  • on the inside of a spit a saltmarsh forms due to mud build up
37
Q

How are bars formed?

A
  • longshore drift causes a spit to grow across a bay trapping the water behind it making a lagoon
  • an offshore bar can also form, but this is further out at sea (where waves deposit sediment on the seabed of a gently sloping coast due to friction)
38
Q

Where is Swanage and what are it’s features?

A
  • town in Dorset
  • on the discordant coastline
  • south has only 1 type of rock (limestone), east has discordant
  • Studland Bay - bay, ballard point headland
39
Q

What landforms are there in Swanage?

A
  • CASS (old harry stack)
  • headlands + bays (swanage and studland bay between the Foreland (headland))
40
Q

What are 3 coast managing options?

A
  • managed retreat - controlled retreat of coast, often allowing sea to flood over low lying land
  • soft engineering - environmentally friendly, less intrusive methods of controlling natural processes
  • hard engineering - artificial structures to control natural processes
41
Q

What are groynes + advantages and disadvantages?

A
  • HARD ENGINEERING - timber and rock structures out to sea that trap sediment being moved by longshore drift and make beach wider, protecting against waves (buffer)
  • less expensive
  • wider beach
  • useful structures for piers
  • BUT they starve beaches down the coast of sediment
  • BUT can be viewed as unattractive
42
Q

What is rock armour + advantages and disadvantages?

A
  • HARD ENGINEERING - piles of boulders on the foot of a cliff that cause the wave to break, which protects the cliff
  • cheap and easy to maintain (200k for 10m)
  • interest to coast
  • BUT rocks are imported
  • BUT expensive transport
  • BUT do not fit in with local geology
  • BUT obtrusive
43
Q

What are gabions + advantages and disadvantages?

A
  • HARD ENGINEERING - wire cages filled with rocks that provide a buffer against the sea
  • cheap (50k per 100m)
  • improves drainage of cliffs
  • can merge into landscape as they become vegetated
  • BUT look unnatractive
  • BUT cages only last 50-10 years
44
Q

What is a sea wall + advantages and disadvantages?

A
  • HARD ENGINEERING - concrete/rock barrier at the end of a beach or the foot of cliff (can be curved to reflect waves back)
  • 10,000 per metre
  • promenade which is good for business on top
  • BUT obtrusive and unatural
  • BUT expensive with high maintenance costs
45
Q

Why are hard engineering processes less commonly used now?

A
  • expensive with high maintenance costs
  • look unnatural
  • intefere with natural processes
46
Q

What is beach nourishment + advantages and disadvantages?

A
  • SOFT ENGINEERING - adding sand or shingle to an existing beach to make it wider
  • blends in with existing beach
  • increases tourist potential
  • BUT constant maintenance
  • BUT expensive (500k per 100m)
47
Q

What is dune regeneration + advantages and disadvantages?

A
  • SOFT ENGINEERING - sand dunes are effective buffers to sea, so marram grass (to stabilise dunes) and fences to keep people off can be used to regen dune
  • natural coastal environment which is popular with people
  • cheap
  • BUT time conumsing
  • BUT people may go onto fenced off areas anyway
  • BUT storm damage
48
Q

What is dune fencing + positives and negatives?

A
  • SOFT ENGINEERING - fences constructed around existing dunes to protect them
  • minimal impact on people
  • cheap
  • controls public access to ecosystems
  • BUT unsightly if broken
  • maintenenace needed
49
Q

What is managed retreat?

A
  • deliberate policy of allowing the sea to flood lowe level, low value land
  • more sustainable long term option
50
Q

What is the Medmerry Managed Retreat case study?

A
  • land near Sussex mostly used for farming and caravans
  • it was protected by sea wall, but was now in need of upgrading, and since it was low value land, it was allowed to flood some farmland
  • cost £28 million
  • it will create a large salt marsh
  • create a wildlife habitat that attracts visitors
  • protect neigbouring farmland and parks
51
Q

What was the need for management at Lyme Regis?

A
  • much of the town is built on unstable cliffs
  • it is eroding rapidly due to strong waves from south west
  • sea walls have been breached many times
  • coastal town on the South Coast of England (populat tourist area)
52
Q

How has the Lyme Regis coastline been managed?

A
  • PHASE 1 - 1990’s - new sea wall and promenade constructed, with 1.4 million project to stabilise cliffs
  • PHASE 2 - 22 million pounds costing sea walls and promenades, new sand and shingle beach (sand from France), and more rock armour at The Cobb
  • PHASE 4 (3 was scrapped) - 2015 - 20 million, new sea walls, and cliff stabilisation for 480 homes
53
Q

What have the positives of the Lyme Regis management scheme been?

A
  • new beaches have lead to more visitors and boosted local economy
  • new defences succeded in stormy winters
  • new harbour is good for fishing and boat owners
54
Q

What have the negatives of the Lyme Regis management scheme been?

A
  • increased vistor count has lead to alleged more littering and congestion
  • new defences have spoiled natural landscape
  • sea wall will inteferes with coastal processes and affect neighbouring coasts

Geography (19 decks)

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