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geography > coasts > Flashcards

coasts Flashcards

1
Q

what is hydraulic action?

A

the sheer force of the waves wearing away at sea cliffs

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2
Q

what is solution?

A

slightly acidic water can dissolve some rocks

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3
Q

what is abrasion?

A

erosion caused by waves picking up sediment and rubbing them against cliffs

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4
Q

what is attrition?

A

erosion where sediment carried by waves is worn down as they collide with each other, they become smaller

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5
Q

what is chemical weathering?

A
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6
Q

what is mechanical weathering?

A
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7
Q

what is biological weathering?

A
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8
Q

what is traction?

A

larger sediment is rolled along the sea bed

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9
Q

what is saltation?

A

sediment is repeatedly picked up and dropped as river energy fluctuates

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10
Q

what is suspension?

A

smaller sediment particles are carried within the water flow

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11
Q

what is solution ?

Transportation

A

dissolved sediment in the sea is moved by wave action

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12
Q

what does the size and quality of sediment transported depend on?

A

the strength of the waves and tidal currents

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13
Q

what is the 5th type of transportation called?

A

longshore drift

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14
Q

can you explain the four steps of longshore drift?

A
  1. waves approach the shore at an angle determined by the direction of the prevailing wind
  2. the swash moves sediment up the beach at an angle
  3. the backwash drags the sediment at right angles down the beach due to gravity
  4. slowly the sediment moves along the beach as the process repeats
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15
Q

what is coastal deposition?

A

when material is dropped by the sea

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16
Q

what are the two factors that increase the amount of material deposited on the beach?

A
  1. there’s lots of erosion elsewhere on the coast = so there’s an increase in sediment being transported
  2. the waves have low energy so cannot carry the material being transported anymore
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17
Q

what are the five factors which show when deposition is likely to occur?

A
  1. when there is little wind
  2. when waves enter a shelter area of land
  3. when waves enter an area of shallow water
  4. a river or estuary flows into the sea reducing wave energy
  5. there’s a good supply of material and the material being transported is greater than the wave energy can transport
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18
Q

Cave, arch, stack and stump formation

A
  1. large crack opened up by hydraulic action
  2. the crack grows into a cave by hydraulic action and abrasion
  3. the cave becomes larger
  4. the cave breaks through the headland forming a natural arch
  5. the arch is eroded and collapses
  6. this leaves a tall rock stack
  7. the stack is eroded forming a stump
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19
Q

wave cut platform formation

A
  1. the waves attack the base of the cliff at high tide through the processes of hydraulic action, abrasion, attrition and solution
  2. over time the cliff will be undercut and a wave cut platform is formed
  3. eventually the cliff becomes unstable and collapses
  4. further cliff retreat will form a wave cut platform
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20
Q

what is a wave cut notch?

A

a small indentation cut into a cliff roughly at the level of high tide due to concentrated erosion here

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21
Q

formation of headland and bays

A
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22
Q

what is a beach?

A

a beach is a landform of coastal deposition that lies between high and low tide levels. most beaches are formed of sand shingles or pebbles

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23
Q

describe beach formation

A
  1. deposition is the main process which creates a beach
  2. this occurs when waves has less energy so beaches often form in sheltered areas such as bays
  3. waves are constructive where the swash is stronger than the backwash, therefore sediment is left on the beach rather than being taken away
  4. over time the beach material will accumulate in the sheltered bay
  5. beaches are under constant change, they can grow and shrink
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24
Q

what is a bar?

A

a bar is a ridge of sand or shingle that joins two headlands either side of a bay

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25
Q

describe bar formation

A
  1. longshore drift carries material across the front of the bay
  2. material is pushed up onto beaches at an angle when swash brings it onto the beach
  3. the backwash takes it back towards the sea at a right angle to the coast
  4. the deposited material eventually joins up with the other side of the bay and a strip of material blocks off the water in the bay
  5. the area behind the newly formed bar is known as a lagoon
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26
Q

what is the area behind a bar called

A

a lagoon

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27
Q

spit formation

A
  1. Spits are formed when large amounts of sediment are transported by longshore drift and where the coastline suddenly changes direction to leave a sheltered, shallow area of water
  2. Deposition occurs in the water sheltered by the headland and the spit slowly builds up and extends in length
  3. When the wind changes direction it causes the waves to alter their direction. This may result in some material at the end of the spit being forced inland to form a curved end
  4. A salt marsh often develops in the sheltered environment behind the spit
  5. Spits cannot grow across an estuary as the river current carries the material out to sea
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28
Q

what causes waves?

A

wind blowing over the surface of the sea

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29
Q

what is fetch?

A

distance of the ocean which the wind blows and the waves build up

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30
Q

what is swash?

A

water running up the beach

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31
Q

what is backwash?

A

what running back down the beach

32
Q

what controls the angle of the swash?

A

the prevailing wind

33
Q

what is the size and energy of a wave dependent on?

A
  1. the strength of the wind
  2. the distance which the wind blows over
  3. how long the wind has been blowing for
34
Q

why do waves break?

A

in the open sea the water has a circular motion in a wave

the sea bed interrupts the circular motion, causing motion to become more elliptical as the water becomes shallower towards the shore

this causes the crest of the wave to rise up and topple onto the beach

then the wave breaks

35
Q

what is the height of a constructive wave?

A

low wave height, under one metre

36
Q

what is the wave length of a constructive wave?

A

long wave length

37
Q

what is the wave frequency of a constructive wave?

A

low frequency, 8-10 waves per min

38
Q

is swash or backwash stronger in a constructive wave?

A

strong swash, weak backwash

39
Q

what is the beach gradient like in a constructive wave?

A

gently sloping, flatter beach

40
Q

does erosion or deposition dominate a constructive wave?

A

deposition

41
Q

height of a destructive wave

A

wave height over 1m

42
Q

what is the wave length of a destructive wave

A

short wave length

43
Q

wave frequency of a destructive wave

A

high frequency

44
Q

swash or backwash is stronger in a destructive wave

A

weak swash, strong backwash

45
Q

beach gradient in a destructive wave

A

steep beach

46
Q

does erosion or deposition dominate a destructive wave?

A

erosion

47
Q

what is mass movement?

A

the movement of material down a slope due to gravity

48
Q

what is slumping?

A

where material moves downslope in a rotational manner along a curved surface

49
Q

what is sliding?

A

where material moves rapidly downslope in one go

50
Q

what is a discordant coastline?

A

where bands of hard and soft rock lie at right angles to the coastline forming headlands and bays

51
Q

what is a concordant coastline?

A

when a rock type runs parallel to the coastline

52
Q

what is a fault?

A

a fracture or break in rocks caused by tectonic activity

53
Q

what is a joint?

A

a vertical crack within a layer of rock formed as a rock cools during the metamorphic processes

54
Q

headland and bay formation

A

Found in areas of alternating bands of resistant (hard) and less resistant (soft) rocks running perpendicular to oncoming waves (discordant coastline)
Initially, less resistant rock (e.g. clay) is eroded back, forming a bay
A bay is an inlet of the sea where the land curves inwards, usually with a beach
The more resistant rock (e.g. limestone) is left protruding out to sea as a headland

55
Q

how do human activities affect the landscape?

A

though urbanisation and development, agriculture and industry

56
Q

how do human activities affect the landscape?

expand:
Urbanisation and Development

A
  1. housing = many people who work in London can no longer afford housing so many move to coastal towns and cities and these are good alternative for commuters
  2. office development = the high cost of London’s properties means many companies such as J.P Morgan have moved their office buildings tp bournemouth
57
Q

how do human activities affect the landscape?

expand:
agriculture

A

. the price of good farmland has risen sharply from £2400 per hectare in 1995 to £30,000 in 2015. farmers have to maximise their income by using whatever land they can

. they need for extra grazing is putting pressure on wildlife habitat

. climate change and rising sea levels are likely to lead to flooding by salt water during winter high tides which could threaten pastures

58
Q

how do human activities affect the landscape?

expand:
industry

A

its an example of how an essential development brings conflict with tourists

a holiday next to a gas terminal is not what tourists want.

59
Q

hard or soft?

sea wall

A

hard

60
Q

hard or soft?

rip-rap

A

hard

61
Q

hard or soft?

groynes

A

hard

62
Q

hard or soft?

beach nourishment

A

soft

63
Q

hard or soft?

managed retreat

A

soft

64
Q

what does coastal management aim to do?

A

reduce risks of flooding and erosion

65
Q

what is hard engineering?

A

building physical structures to prevent coastal erosion

these options tend to be expensive and long term

they also might have an impact on the landscape or environment and be unsustainable

66
Q

what is soft engineering?

A

is working with nature to limit coastal erosion

these options are often less expensive

they are usually short term and sustainable with less environmental impact

67
Q

advantages of a sea wall

A

barrier to flooding
prevents erosion
visible which makes residents feel safe
reflects and absorbs wave energy

68
Q

disadvantages of a sea wall

A

. they are ugly put tourists off
. it creates a strong backwash which erodes under the wall
. expensive to build and maintain

69
Q

cost and length of protection for a sea wall

A

£6000 per m
effective for many years

70
Q

advantages of riprap

A

fairly cheap defence
cheap to maintain
can be put in place quickly
by absorbing wave energy is reduces flooding and erosion

71
Q

disadvantages of riprap

A

. they don’t fit in with the local geology
. not effective in storm conditions
. unattractive
.boulder are from other regions so transportation costs can be high

72
Q

cost and length of protection for riprap

A

£1000-4000 per m
effective for many years

73
Q

advantages of groynes

A

. quick to construct
. fairly cheap
. create wider beaches which slow the waves and protect the land from flooding and erosion
. bigger beaches attract more tourists

74
Q

disadvantages of groynes

A

unsightly
interrupts movement of sediment and can have an impact further along the coast
prevents longshore drift - sand builds up on one side of the groyne

75
Q

cost of groynes and length if protection

A

£5000 per m
effective for many years
30 years

geography (3 decks)

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