coasts Flashcards

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1
Q

features of destructive waves

A

high frequency
high
steep

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2
Q

features of constructive waves

A

low frequency
low
long

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3
Q

destructive waves

A

backwash is more powerful than swash so material is removed

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4
Q

how do constructive waves build beaches

A

swash is more powerful than backwash so material is deposited

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5
Q

mechanical weathering

A

breakdown of rock without changing it’s chemical composition
e.g. freeze thaw weathering

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6
Q

chemical weathering

A

breakdown of rock by changing its chemical composition
e.g. carbonation weathering

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7
Q

process of freeze-thaw weathering (mechanical)

A
  1. water enters rock that has cracks
  2. it freezes overnight which makes the crack bigger
  3. in the day, it melts and more water fills into the crack
  4. the water freezes again making the crack bigger
  5. this repeats until the rock breaks
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8
Q

process of chemical weathering

A
  1. rainwater has carbon dioxide dissolved in it —> makes it a weak carbonic acid
  2. carbonic acid reacts with limestone —> so rocks break
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9
Q

define hydraulic action

A

waves crash against rock and pushes air into cracks —> the force of this causes bits of rock to break off

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10
Q

define abrasion

A

loose rocks (sediment) are thrown against the cliff by waves. this wears away at the cliff and chips bits of rock

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11
Q

define attrition

A

eroded particles in water collide and knock into each other to become smaller and more rounded

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12
Q

define solution

A

seawater dissolves material from the rock

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13
Q

what is mass movement

A

shifting of rocks and loose material down a slope e.g. a cliff

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14
Q

why does mass movement happen

A

it happens when the force of gravity acting on a slope is greater than the force supporting it

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15
Q

define slide

A

material shifts in a straight line along a slide plane

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16
Q

define slump

A

material rotates along a curved slip plane

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17
Q

define rockfall

A

material breaks up and falls down a slope

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18
Q

3 types of mass movement

A

slides
slumps
rockfall

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19
Q

describe longshore drift

A
  1. waves follow the direction of the prevailing wind and approach beach at an angle
  2. swash carries material up the beach at the same angle
  3. backwash carries material straight back down the beach at right angles
  4. overtime, material moves along beach in zigzag pattern
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20
Q

define deposition

A

when water loses energy and drops the material it is carrying

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21
Q

when does deposition on an area of a coast increase?

A

there’s lots of erosion elsewhere (so more material is available)

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22
Q

how do headlands and bays form

A
  1. alternating bands of resistant and less resistant rock
  2. less resistant rock is eroded faster, forming a bay
  3. resistant rock erode more slowly and forms a headland which sticks out

forms along discordant coastlines

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23
Q

how is a wave cut platform formed

A
  1. sea attacks base of cliff forming a wave cut notch
  2. repeated erosion causes rock above notch to become unstable and it eventually collapses
  3. collapsed material is washed away and a new wave cut notch starts to form
  4. repeats, the cliff retreats, leaving a wave cut platform
24
Q

how do caves, arches, stacks and stumps form

A
  1. resistant rock headland have cracks
  2. abrasion and hydraulic action widens the cracks
  3. repeated erosion of cracks causes cave to form
  4. continued erosion deepens the cave until it breaks through the headland to form an arch
  5. arch is eroded until the roof collapses leaving a stack
  6. stack eventually collapses leaving a stump
25
Q

example of hard rock and soft rock

A

hard rock - granite
soft rock - sandstone

26
Q

define discordant coastlines

A

alternating bands of hard and soft rock at right angles to the coast

27
Q

define concordant coastline

A

alternating hands of hard and soft rock that are parallel to the coast

28
Q

how are sand beaches formed

A

constructive waves build up beaches as they have a strong swash and a weak backwash

form in sheltered areas like bays where waves have limited energy

29
Q

how are shingle beaches formed

A

high energy waves and are steep and narrow

sand particles are washed away but larger shingle left behind

30
Q

what is a bar

A

a bar forms when a spit joins 2 headlands together

31
Q

how is a bar formed

A
  1. a bar forms when a spit joins 2 headlands together
  2. bay between headlands gets cut off from the sea
  3. lagoon forms behind the bar
32
Q

what feature lays behind a bar

A

lagoon

33
Q

why do spits have a hooked or recurved end

A

strong winds and waves can change the direction of it

34
Q

what are spits

A

long narrow ridges of sand and shingle stretching out from the coast

35
Q

how is a spit formed

A
  1. longshore drift transports sand and shingle past the bend and deposits it in the sea
  2. strong winds and waves can curve the end of a spit (forming recurved end)
  3. area behind the spit is sheltered from waves so material accumulates and plants are able to grow
  4. overtime, the sheltered area can become a mud flat or a salt marsh
36
Q

what feature lies behind a spit

A

salt marsh and mud flats

37
Q

what 3 features are formed by deposition

A

spits, bars, sand dunes

38
Q

how are sand dunes formed

A
  1. Sand is blown over an obstacle like a dead animal or a rock by wind
  2. When the sand comes into contact with the obstacle, the wind slows down and the sand is deposited
  3. This forms an embryo dune
  4. Over time, plants like Marram Grass stabilise the sand and encourage more sand to accumulate there
  5. The dunes steadily get bigger as you move back from the coast because the amount of vegetation increases.
  6. d’une slacks can form in hollows between dunes
39
Q

what grass grows on sand dunes and holds them in place

A

marram grass

40
Q

coast

A

A part of land that joins the sea.

41
Q

what causes waves to form

A

Wind blowing over the sea

42
Q

What does the size and strength of waves depend on?

A

• How strong the wind is
• How long it blows for
• How far it travels

43
Q

swash

A

Water rushing up the beach

44
Q

backwash

A

Water draining back down the beach

45
Q

fetch

A

The distance a wave has travelled

46
Q

constructive waves

A

Waves that have a very strong swash and a weak backwash

They build up the beach

47
Q

marine processes

A

The base of cliffs being eroded by hydraulic action and abrasion

48
Q

waves associated with coastal erosion

A

Destructive waves

49
Q

erosion

A

Wearing away of rocks by water, weather or ice

50
Q

4 types of erosion

A
  1. Hydraulic action
  2. Abrasion
  3. Attrition
  4. Solution
51
Q

How is sediment transported along the coastline?

A

longshore drift

52
Q

define landform

A

A feature in the landscape that has been formed by erosion, transportation and/
or deposition.

53
Q

What factors influence the landforms found along a coastline?

A

Hard rock (resistant rock) - does not erode easily - likely to find headlands
Soft rock (less resistant rock) - erodes easily - more likely to be a bay

54
Q

coastal landforms that result from erosion

A
  1. Headlands and bays
  2. Cliffs
  3. Wave cut platforms
  4. Caves, arches, stacks and stumps
55
Q

coastal landforms that form as a result of deposition

A
  1. Beaches
    2 Sand dunes
  2. Spits
  3. Bars