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Flashcards in The Coastal Zone Deck (58)
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1
Q

What causes tides

A

Gravitational pull between moon and earth

2
Q

High tides are

A

12 hours apart

3
Q

2 types of tides

A

Spring and neap

4
Q

What’s a wave

A

Friction on water surface which agitates particles

5
Q

Wave length

A

Distance between two successive troughs/peaks

6
Q

Wave height

A

Distance between troughs and peaks

7
Q

Fetch

A

Amount of open ocean wind has blown across

8
Q

Waves break because

A

Particles become distorted and water is held back by friction on sea bed, surface of water carries on travelling and spills over the shoreline

9
Q

Destructive waves

A

Longer, higher, more frequent, 14 pm, winter

10
Q

Constructive waves

A

Lower, shorter, 10pm, summer

11
Q

Weathering

A

The breakdown of rocks

12
Q

4 type of weathering

A

Mechanical, physical, biological, chemical

13
Q

Mechanical/physical weathering

A

Eg freeze thaw- water seeps into cracks, freezes, expands 9% causes rock to crack then melts and seeps further into rock

14
Q

Chemical weathering

A

Eg limestone and rain- weak carbonic acid+CaCO2 causes corrosion

15
Q

Biological weathering

A

Roots grow through rocks/animals burrow in cracks

16
Q

Rockfalls

A

Fragments of rock break away from cliff face

17
Q

Mudflow

A

Saturated soil and weak rock flows down slope

18
Q

Landslide

A

Blocks of rock slide down hill

19
Q

Rotational slip

A

Slump of saturated soil and weak rock along curved surface

20
Q

General mass movement

A

Permeable/semi permeable rock collects on surface of impermeable rock- layer of water collect in between the two layers preventing them form join and so top layer eventually shifts

21
Q

Hydraulic action

A

Water hits shore and enters cracks- air pushed back and when water seeps back out pressure built up with air being pulled forward again causes rock to crack

22
Q

Wave pounding

A

Cliff worn away from force of waves hitting surface

23
Q

Corrosion

A

Acid in sea water dissolves the rock

24
Q

Attrition

A

Materials being carried by the water collide and become smoother and small particles

25
Q

Formation of stump

A
  • waves pick out weak spot in rock
  • this becomes a notch and later a cave
  • abrasion and solution persist so both side of headlands are wearing away
  • 2 caves meet and become an arch
  • sea rain and frost cause roof of arch to collapse creating a stack
  • stack vulnerable to low tide and so becomes a stump
26
Q

Examples of stacks/stumps

A

Old Harry’s Rocks’- Dorset

‘Needles’- Isle of Wight
‘Etratat’- Normandy

27
Q

Features of deposition

A

Beaches, spits and tombolos

28
Q

Where do beaches form?

A

Sheltered areas where swash is greater than backwash

29
Q

Spits

A

Long narrow strips of land formed when coastline changes direction causing deposition

30
Q

Examples of spits

A

Dawlish warren and slapton key

31
Q

Cliff collapse

A

Permeable rock on top of impermeable rock- water pool created between layers saturating the permeable rock, causing it to slip off

32
Q

Hold the line

A

Take action to preserve the coastline as it is

33
Q

Advance the line

A

Improve coastal defence

34
Q

Hard engineering

A

Artificial structures built to control nature- intrusive and expensive

35
Q

Soft engineering

A

Working with nature to preserve coastline- low maintenance and inexpensive with low impact on landscape

36
Q

Sea walls

A

Absorb wave energy/ send waves back to sea - sloped, recurved and stepped

37
Q

Advantages of sea walls

A

Strong and effective

38
Q

Disadvantages of sea walls

A

Expensive

High maintenance
Intrusive
Unattractive

39
Q

Groynes

A

Right angle to shoreline to interrupt longshore drift

40
Q

Advantages of grounds

A

Cheaper than sea wall

Sustainable
Low maintenance
Maintains beach tourism
Good for fishers

41
Q

Disadvantages of groynes

A

Major construction

Interrupt coastline- destroy beaches along the coast
Must be frequently rebuilt

42
Q

Rock amourment

A

Boulders at bottom of cliff to absorb wave energy

£1000-£5000 per metre
Could also be gabions (wire boxes full of rocks)

43
Q

Advantages of rock amourment

A

Relatively cheap

Look more natural than others

44
Q

Disadvantages of rock amourment

A

Difficult to get rocks

May be unattractive
Dangerous for animals/children

45
Q

Tetrapods

A

Large concrete structures with 4-5 arms eg Scarborough

33 million to install

46
Q

Advantages of tetrapods

A

Very effective

Protects coastline well

47
Q

Disadvantages of tetrapods

A

Expensive

Ugly
Dangerous
Large construction
When they erode the metal structure is exposed

48
Q

Beach nourishment

A

Extra sediment placed on beach to increase size

49
Q

Advantages of beach nourishment

A

Relatively cheap

Looks natural
Remains attractive
Sustainable

50
Q

Disadvantages of beach nourishment

A

Constant maintenance needed (twice a year) eg Seaford

51
Q

Sand dunes/dune regeneration

A

Found on large beaches, occur when plants trap sediment being carried by wind and fences can be installed to encourage this

52
Q

Advantages of sand dunes/dune regeneration

A

Natural looking

Maintains sand dune ecosystem
£2000 per 100m
Good for tourism
Brings plant diversity

53
Q

Disadvantages of sand dunes/dune regeneration

A

Easily destroyed by people

Storms destroy them
Time consuming installation

54
Q

Managed retreat

A

Allowing the sea to reclaim the land and flood it creating a salt marsh

55
Q

Advantages of managed retreat

A

Cheap

Increased biodiversity
Natural

56
Q

Disadvantages of managed retreat

A

Lost value of land

Farmers lose land
Tourism lost

57
Q

Salt marshes

A

Causes mud accumulation in sheltered areas (spits or estuaries)as they provide habitats. Once it reaches water level it’s called a mud flat

58
Q

Cord grass

A

Pioneer species- can grow in first stage of salt marsh as it tolerates being submerged in water. It traps sediment and holds land together with roots