Coastal landscapes Flashcards

1
Q

what 3 factors is the energy of a wave determined by

A
  • strength of wind
  • duration of wind
  • distance / fetch
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2
Q

how does wave height increase

A

the wind pulls waves the surface through friction causing ripples to form

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3
Q

give me 3 features of constructive wave

A
  • depositional
  • strong swash weak backwash
  • low frequency
  • low wave height
  • large wavelength
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4
Q

give me 3 features of a destructive wave

A
  • strong backwash weak swash
  • short wave length
  • high wave height
  • erosional
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5
Q

what are the 3 erosional process along a coastline and define them

A

abrasion - when sediment scrap and bang against coast wearing it away
attrition - rocks and pebbles hit each other wearing each other down and get smaller
hydraulic action - waves cause air to force through cracks the high pressure cause it to crack open and widen and air expands

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6
Q

give me a example of mechanical weathering and define it

A

freeze thaw - water enters cracks and freezes and expands to up to 10% causing more cracks to grow due to pressure and fragments to break away over a repeated cycle

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7
Q

give me a example of chemical weathering with an example

A

carbonation - this is when acid rain reacts with calcium carbonate to form soluble which is carried away by water

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8
Q

What are some common forms of mass movement

A

rockfall
landslides
mudflow
rotational slump

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9
Q

what is a rockfall

A

fragments and chunks of rock falling off a cliff face resulting in freeze thaw

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10
Q

what is landslide

A

sliding of chunks of rock due to lack of friction as water lubricates

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11
Q

what is mudflow

A

when saturated soil flows down hill /slumping causing bulge at bottom

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12
Q

what is rotational slump

A

when soil and rock fragments become saturated due to water and instead create a head at the bottom of cliff

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13
Q

tell me the 4 method of transportation in rivers

A

traction
saltation
suspension
solution

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14
Q

what is traction

A

the rolling of large boulders along seabed

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15
Q

what is saltation

A

the bouncing of pebbles too heavy

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16
Q

what is suspension

A

the particles suspended under the water / float

17
Q

what is solution

A

the chemicals dissolved in water

18
Q

what is longshore drift

A

this is the movement of sediment along coastline due to wind direction if prevailing winds which pushes the sediment in direction of wind due to swash then carry back due to back wash in zig zag
- longshore drift form spit and beaches

19
Q

what is coastal deposition

A

where sediment is dropped off by waves which have low wave energy normally constructive waves

20
Q

What is a headland

A

bit of coast jutting out to sea exposed to high energy waves and contain landforms such as cliffs , wave-cut platforms stacks

21
Q

what is a bay

A

sheltered by headlands , experienced by low energy waves resulting in deposition and beaches

22
Q

how are wave cut platforms formed

A
  • when waves erode a cliff forming wave cut notch due to hydraulic action and abrasion
  • undercutting the cliff causing it to collapse through mass movement
  • cliff line retreats leaving behind rocky wave-cut platform which is smoothed by pebbles due to abrasion
23
Q

What are caves arches and stacks stumps

A
  1. crack formed in headland due to hydraulic action
  2. crack grows and become cave
  3. wave pressure causes caves to break through and from arch which is widen due to erosion
  4. weathering (freeze-thaw) cause it to become unstable and top collapse into sea leaving behind stack
  5. stack is eroded at base to make it unstable
  6. stack is collapsed into sea forming stump
24
Q

how are beaches formed

A

depositional landforms of sand and pebbles

25
Q

what are sandy beaches

A

low energy constructive waves deposit sand

26
Q

what are pebble beaches

A

when high energy destructive waves remove sand and leave behind pebbles

27
Q

what are sand dunes

A

formed at back of beach due to prevailing winds

28
Q

what are spits

A

extended stretch of sand or shingle jutting out into the sea from the land. Spits occur when there is a change in the shape of the landscape or there is a river mouth.

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.

29
Q

what are bars

A

Sometimes a spit can grow across a bay, and joins two headlands together. This landform is known as a bar. They can trap shallow lakes behind the bar, these are known as lagoons

30
Q

describe the erosional and depositional landforms at Dorset coast

A

Swanage is an example of a headland and bay
Old Harry Rocks is an example of caves, stacks and stumps
at Chesil Beach there is a bar

31
Q

what are three ways to manage coasts

A

soft hard and managed retreat

32
Q

what are sea walls and advantages and disadvantages

A

structure placed at barrier of sea absorb and reflecting wave preventing erosion

  • expensive
  • unattractive
  • successful
33
Q

what are rock armour

A

Large boulders placed at the foot of a cliff. They break the waves and absorb their energy.
- Cheaper than a sea wall and easy to maintain.
- They look different to the local geology, as the rock has been imported from other areas.
The rocks are expensive to transport

34
Q

gabions

A
Rocks are held in mesh cages and placed in areas affected by erosion.
Cheap - approximately £100 per metre.
Absorbs wave energy.
Not very strong.
Looks unnatural.
35
Q

Groynes

A

Wooden or rock structures built out at right angles into the sea.
- Builds a beach - which encourages tourism.
They trap sediment being carried by longshore drift
- By trapping sediment it starves beaches further down the coastline, increasing rates of erosion elsewhere.
They look unattractive

36
Q

what is beach nourishment and the advantages and disadvantage

A
when addition of sediment and sand is added to beach to replace material via erosion
good for tourism
cheap to start and maintain
natural look
regular requirements of sand
37
Q

What is dune regeneration

A
marram grass being planted to stabilise dunes and fences catch wind 
cost effective
biodiversity and develop habitats 
tourism
time consuming
damage by storms
38
Q

what is managed retreat

A
when sea is eroded and flooded 
- decisions made prior 
cost effective
land owners compensated
low land value
locals lose land
long term good for tourism
attractive
sustainable
39
Q

why is managed retreat popular

A

too costly so efficient methods for local councils