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Geography > coastal landforms > Flashcards

coastal landforms Flashcards

1
Q

erosion

A

Erosion is the process that wears away the river bed and banks. Erosion also breaks up the rocks that are carried by the river.

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2
Q

types of erosion

A

Hydraulic action - This is the sheer power of the water as it smashes against the river banks. Air becomes trapped in the cracks of the river bank and bed, and causes the rock to break apart.
Abrasion - When pebbles grind along the river bank and bed in a sand-papering effect.
Attrition - When rocks that the river is carrying knock against each other. They break apart to become smaller and more rounded.
Solution - When the water dissolves certain types of rocks, eg limestone.

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3
Q

transportation

A

river picks up sediment and carries it downstream

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4
Q

types of transportation

A

Traction - large, heavy pebbles are rolled along the river bed. This is most common near the source of a river, as here the load is larger.
Saltation - pebbles are bounced along the river bed, most commonly near the source.
Suspension - lighter sediment is suspended (carried) within the water, most commonly near the mouth of the river.
Solution - the transport of dissolved chemicals. This varies along the river depending on the presence of soluble rocks.

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5
Q

deposition

A

When the river loses energy and drops any of the material it has been carrying

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6
Q

factors of deposition

A
  • shallow water
  • loss of energy in waves
  • little or no wind
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7
Q

how do headlands form

A

Headlands are formed when the sea attacks a section of coast with alternating horizontal bands of hard and soft rock.

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8
Q

how wave cut platforms form

A
  • The sea attacks the base of the cliff between the high and low water mark.
  • A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action - this is a dent in the cliff usually at the level of high tide.
  • As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
  • The backwash carries away the eroded material, leaving a wave-cut platform.
    The process repeats. The cliff continues to retreat.
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9
Q

erosional features commonly found on a headlands

A
  • Cracks are widened in the headland through the erosional processes of hydraulic action and abrasion.
  • As the waves continue to grind away at the crack, it begins to open up to form a cave.
    The cave becomes larger and eventually breaks through the headland to form an arch.
  • The base of the arch continually becomes wider through further erosion, until its roof becomes too heavy and collapses into the sea. This leaves a stack (an isolated column of rock).
  • The stack is undercut at the base until it collapses to form a stump.
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10
Q

spit

A

an extended stretch of sand or shingle jutting out into the sea from the land

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11
Q

how do spits form

A
  • Sediment is carried by longshore drift.
  • When there is a change in the shape of the coastline, deposition occurs. A long thin ridge of material is deposited. This is the spit.
  • A hooked end can form if there is a change in wind direction.
  • Waves cannot get past a spit, therefore the water behind a spit is very sheltered. Silts are deposited here to form salt marshes or mud flats.
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12
Q

bar

A

when a spit grows across a bay and joins two headlands together

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13
Q

fetch

A

how far the wind has travelled

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14
Q

The size and energy of the wave depends on

A

the fetch
strength of wind
how long the wind has been blowing for

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15
Q

wave types

A

constructive
destructive

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16
Q

swash

A

The water flowing towards a beach when a wave breaks

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17
Q

backwash

A

The movement of water down the beach

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18
Q

characteristics of a destructive wave

A
  • weak swash and strong backwash
  • the strong backwash removes sediment
    from the beach
  • the waves are steep and close together
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19
Q

characteristics of a constructive wave

A
  • strong swash and weak backwash
  • the strong swash brings sediments to build up the beach
  • the backwash is not strong enough to remove the sediment
  • the waves are low and further apart
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20
Q

types of mass movement

A

rockfall
landslide
mudflow
rotational slip

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21
Q

what is rockfall

A

Bits of rock fall off the cliff face, usually due to freeze-thaw weathering

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22
Q

what is mass movement

A

A large-scale downward movement of rocks and material

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23
Q

what is mudflow

A

Saturated soil (soil filled with water) flows down a slope

24
Q

what is landslide

A

Large blocks of rock slide downhill

25
Q

what is rotational slip

A

Saturated soil slumps down a curved surface

26
Q

explain the process of transportation

A
  • The swash will carry the sediment towards the beach at an angle due to prevailing winds
  • The backwash then flows back to the sea, down the slope of the beach
  • The process repeats itself along the coast in the zigzag movement
27
Q

hard engineering

A

using man-made structures to manage the coast

28
Q

examples of hard engineering

A
  • sea walls
  • dams
29
Q

advantages of hard engineering

A
  • Effective at protecting the base of the cliff
  • Sea walls usually have promenades so people can walk along them
30
Q

disadvantages of hard engineering

A
  • expensive
  • waves can break down and erode the sea wall
31
Q

rock armor

A
  • large boulders placed at the foot of the cliff
  • used to absorb the impact of the waves
32
Q

advantages of rock armor

A
  • cheaper than a sea wall
  • easy to maintain
  • can be used for fishing
33
Q

disadvantages of rock armor

A
  • They look different to the local geology, as the rock has been imported from other areas
  • expensive to transport
34
Q

gabions

A
  • rocks held in mesh cages to prevent erosion
35
Q

advantages of gabions

A
  • cheap
  • absorbs the impact of waves
36
Q

disadvantages of gabions

A
  • not very strong
  • looks very unnatural
37
Q

groynes

A
  • Wooden or rock structures built out at right angles into the sea
38
Q

advantages of groynes

A
  • Builds a beach - which encourages tourism
  • They trap sediment being carried by longshore drift
39
Q

disadvantages of groynes

A
  • By trapping sediment it starves beaches further down the coastline, increasing rates of erosion elsewhere
  • They look unattractive
40
Q

soft engineering

A
  • The use of natural, sustainable solutions to control the coast
41
Q

beach nourishment

A

sand is pumped into the existing beach to build up

42
Q

advantages of beach nourishment

A
  • blends in with the existing beach
  • larger beaches appeal to tourists
43
Q

disadvantages of beach nourishment

A
  • needs to be constantly replaced
  • the sand has to be brought in from elsewhere
44
Q

reprofiling

A
  • The sediment is redistributed from the lower part of the beach to the upper part of the beach
45
Q

advantages of reprofiling

A
  • cheap
  • simple
  • reduces energy of the waves
46
Q

disadvantages of reprofiling

A
  • Only works when wave energy is low.
  • Needs to be repeated continuously
47
Q

dune nourishment

A
  • Marram grass planted on sand dunes stabilises the dunes and helps to trap sand to build them up
48
Q

advantages of dune nourishment

A
  • cheap
  • maintains a natural looking coastline
49
Q

disadvantages of dune nourishment

A
  • can be damaged by storms
  • areas have to be zoned off by the public, making it unpopular
50
Q

managed retreat

A
  • The controlled flooding of low-lying coastal areas
51
Q

advantages of managed retreat

A
  • 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
52
Q

disadvantages of managed retreat

A
  • Land is lost as it is reclaimed by the sea
  • Landowners need to be compensated, making it expensive
53
Q

give an example of coastal management and the reason for its management

A

holderness coastline:
- the cliff were made of clay which erodes easily
- the beaches have less protection against the waves and doesn’t reduce the power of the waves
- groynes have been installed to stop long-shore drift which narrows unprotected beaches elsewhere even more

54
Q

management strategies for the example fo coastal management

A
  • Bridlington has a 4.7 km sea wall
  • Hornsea is protected by a sea wall, groynes and rock armour
  • Coastal management at Withersea has tried to make the beach wider by using groynes
55
Q

landforms at holderness coastline

A

headlands and bays

56
Q

conflicts with the holderness coastline

A
  • increase in erosion at Great Cowden because of the groynes used in Mappleton
  • people disagree with where the sea defences are located, as their land may not be protected
  • sea defences negatively impacts tourists

Geography (12 decks)

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