Coasts Flashcards

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1
Q

What’s a coastline

A

A place at which land meets the sea

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2
Q

What’s weathering

A

The break down of rocks at earths surface by rain water, temperature, biological, chemical and physical activity

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3
Q

What’s biological weathering

A

Roots from plants find a way into gaps in rock and weaken as gaps expand and widen so pieces fall off

Animal burrowing and walking over surface can wear away and weaken surface so prices fall away

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4
Q

What’s physical weathering

A

Wind can blow small grains of sand against rock and wear it away

Rain and waves hit rock - wear it away

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5
Q

Tell me about freeze thaw weathering which is physical btw

A

What expands when it freezes, so water enters cracks and freezes, the crack expands and when ice melts it can get further in crack and freeze and melt and so on until crack is so big the rock is to weak so it falls off

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6
Q

What’s chemical weathering

A

Reactions break down bonds holding rock together so they fall apart

More common in location with a lot of water as it is needed for for chemicals to reach the rock

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7
Q

What’s oxidation (chemical weathering)

A

When oxygen combines with other elements to make another type of rock, it’s broken down Becuase it’s become softer

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8
Q

What’s hydrolysis (type of chemical)

A

When water combines with substances in rock to form new substances which are softer than original rock

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9
Q

What’s carbonation (chemical)

A

Carbon Dioxide reacts with rock to become a solution and is carried away

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10
Q

What are mud slides, rock falls and slumping?

A

Types of mass movements

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11
Q

Tell me about mud slides

A

They occur on steep cliffs that have been weakened by weathering

The saturated mass falls down along a distinct SLIP PLANE which is likely a fault

Occur after heavy rain

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12
Q

Tell me about rock slide

A

Where a large amount of rock slides down the cliff, it happens along a fairly straight slip plane- something along natural plane in rock

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13
Q

Tell me about rock falls

A

Rocks prone to freeze thaw weathering result in falling rocks losing contact with cliff face
Need a vertical cliff and seasonal climates

At bottom of cliff they land and fan out to form a SCREE SLOPD

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14
Q

Tell me about slumping

A

Soft rock saturates permeable surface but stops at impermeable surface beneath, the saturated rock slips along curved plane towards beach

Happens again as waves undercut cliff base do its unstable and slumps

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15
Q

Define a mass movement

A

Downslope movement of rock or mud and soil under influence of gravity

Heavy rain usually triggers it

Scale of movement is determined by extent of weathering

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16
Q

What’s a wave

A

A body of water moving towards the coastline at a higher than average level

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17
Q

Tell me about waves approaching the coast

A

First there is a circular orbit in open water

Friction with seabed sorrows the circular orbital motion

There’s an increasing elliptical orbit at the top of wave moves faster

Wave begins to break

Then hits beach

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18
Q

What’s the backwash

A

ALWAYS AT RIGHT ANGLE TO SEA its water from a wave that returns

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19
Q

What’s swash

A

Water that rushes up the beach and goes up at angle of the wind

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20
Q

What’s a destructive wave like

A

High wave in proportion to length

A tall wave breaks downwards with great force near Beach

Long fetch

Short wavelength

Strong backwash

Weak swash

Created in storm conditions

Tend to erode coast

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21
Q

What’s a constructive wave like

A

Low wave in proportion to length

Strong swash

weak backwash

Long wavelength

Created in calm weather

Break at shore and deposit material to build up beaches

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22
Q

What’s the fetch

A

Distance wing travels to create a wave

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23
Q

Define erosion

A

Break down and removal of rock

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24
Q

What can affect rates of erosion

A

Rates of weathering

Power of backwash

Location

Fetch length

Rock type/resistance

Direction of wing

Shape of coastline

Human intervention

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25
Q

What’s attrition

A

Material carried by waves bump info eachother and are smoothed and broken down into smaller pieces

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26
Q

What’s hydraulic action

A

Waves enter cracks (faults ) in coastline and compress air within crack
When wave retreats the wake expands causing a minor explosion

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27
Q

What’s corrosion/ solution

A

Chemical action of sea water, acids in salt water dissolve rocks on the coast

Limestone and chalk prone to it

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28
Q

What’s abrasion and corrasion

A

This is a process where coast worn down by matieral carried by waves hit the rock sometimes at high velocity

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29
Q

What’s a headland

A

Area of resistant rock which protude (stick out) from coastline

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30
Q

What’s a bay

A

Area of soft rock between 2 headlands that erodes quickly

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31
Q

How does a bay form

A

When there’s is variation in rock type the softer rock erodes faster and over hundreds of years a bay is formed

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32
Q

What’s the difference between coves and bays

A

Coves due to rock type changing parallel to sea

Bays due to variation so bands of rock meet at a right angle to sea

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33
Q

Describe formation of a wave cut platform

A

Waves break on cliff face and erode

Erosion continues between high and low water mark and undercut(called a wave cut notch) rest of cliff face over hundreds of years

The notch becomes deeper and wider and overhand formed

The overhand collapsed and cliff retreats leaving a wave cut platform (bur of rock at bottom of cliff face)

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34
Q

Explain the formation of a stack

A

Lines of weakness in headland form form erosion

Continues to form a small sea cave

Over hundreds of year it deepens and widens to make a cave

Cave erodes back and breaks through other side forming an arch

Weathering breaks down roof of arch and collapsed leaving stack

Erosion weakens it to form a stump as it collapsed

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35
Q

What is the cause of waves

A

Waves are caused by wind the direction the waves travels depends on sing direction

The direction most win travels in is prevailing wind - it’s south westerly in uk

36
Q

What’s traction

A

Pebbles and larger sediment rolled along sea bed

37
Q

What’s saltation

A

Load bouncing/hopping along the sea bed eg small pieces of shingle

38
Q

What’s suspension

A

Small particles eg silts are carried in water which make it appear cloudy

39
Q

What’s solution (transportation)

A

Dissolved chemicals in sea water carried in solution - not visible

40
Q

Define longshore drift

A

The transport of sediment along a stretch of coastline caused by waves approaching the beach at an angle that’s not 90 degrees

41
Q

When does deposition occur?

A

When a wave enters shallow water

Waves enter a sheltered area eg a cover or bay

There’s little wind

There is a good supply of material

Wide expanse of beach so swash expands out and weakens waves - weaker backwash

42
Q

What is a beach/ tell me some stuff

A

Formed by deposition

A beach is a gently sloping area of land between the high and low water marks

Beaches are no permanent they are altered by waves

43
Q

Where does sea material come from

A

Material at mouth of rivers

Cliff erosion

44
Q

What are orthogonals

A

Lines to show concentrations of wave energy in wave refraction

45
Q

What’s wave refraction

A

As waves approach the coast they are refracted so that their energy is concentrated around headlands(shallow water) but reduced around bays. Waves tend to approach the coastline parallel to it, their energy decreases as water depth increases

46
Q

What are the 2 types of beach

A

Sandy and pebble

47
Q

Tell me about sandy beaches

A

Sometime is has sand dunes behind it

Very gently sloping - almost flat

Formed by generally constructive waves

At low tide water filled depressions called tunnels form

48
Q

Tell me about pebble beaches

A

Storm beach with large pebbles at the back of it

Pebbles get generally larger towards the back of the beach

Generally quite steep

Don’t stretch far inland

Formed largely by powerful destructive waves

49
Q

Tell me the orders of shores starting from furthest away from cliff face

A

Offshore, nearshore, foreshore, backshore, coastal terrain

50
Q

Tell me about the offshore

A

Destructive waves drag beach depositors offshore from berms or sand dunes: forming an offshore bar- lowers height of beach

Waves are not breaking

51
Q

Tell me about the nearshore

A

This is where waves breaks

52
Q

Tell me about the foreshore

A

Inter tidal zone that is covered then uncovered by changing tides - where sea hits sand

53
Q

Tell me about the Backshore

A

Not usually affected by waves so usually dry

Berms form

54
Q

Tell me about coastal terrain

A

Dunes or storm beach

cliffs or plain too

Rarely affected by waves

55
Q

What’s a berm

A

Terrace in backshore, above the water level at high tide, formed in calm weather when constructive waves transport material

56
Q

What’s a spit

A

A spit is a finger of land made of sand and shingle thag extends into the sea from a coastline

57
Q

How does a spit form

A

Longshore drift carries sediment along the coast, the swash is how the material is carried up the beach and the backwash takes it back down, in this way material is moved along the coast in the direction of the prevailing wind. If the coast changes direction then sediment is continued to be dropped in original direction. In this way a long ridge of material is deposited - this is a spit. Further out to sea the end of the spit it often curved due to waves approaching from a different direction

58
Q

How does a bar form

A

Longshore drift caused by prevailing wind deposits material in that direction

When there is a bay - LSD direction does not change and so form a spit to enclose the bay from headland to headland leaving a lagoon

59
Q

Where are sanddunes found

A

On the backshore of the beach

60
Q

What are some essential conditions for sand dunes to form

A

Large flat beach - wind can blow sand across beach

Large supply of sand - needed to build up sand dune

Onshore Wind - needed so material can be pushed into beach

Large tidal range - allows sand to dry out to be blown by wind

Obstacle such as drift wood
Sand hits obstacle and so sand can build up around it

61
Q

Tell me what creep is

Aeolian transportation

A

Large material rolled along beach surface

62
Q

What’s saltation

Aeolian transportation

A

Small material bounced along surface by wind

63
Q

What’s suspension

Aeolian transportation

A

Smaller/ fine sand and material carried in wind

64
Q

Tell me how a sand dune forms

A

At back of beach there’s an obstacle eg drift wood
The heaviest grains settle against obstacle and lighter ones on other side
Side facing wind begins to form a crest
Because the pile of sand is too steep to build up the crest collapses under own weight
Sand stops slipping at a gradient of 30-34 degrees
Sand dunes migrate inland as repeated movement of material up windward side and down leeward side
Sand dune itself becomes and obstacle so others form In front of it

65
Q

Tell me the order of the way sand dunes are named starting from the sea moving back inland

A

Embryo dune

Fore dune

Yellow dune

Grey dune

Mature dunes

66
Q

What’s a concordant coastline

A

Where bands of different rock types run parralel to coastline

67
Q

What’s a discordant coastline

A

Layers of rock run at right angles to coast

68
Q

Tell examples of bays on Dorset coastlines

A

Swanage bay

Christchurch bay

Pool bay

Stud land bay

69
Q

Tell me examples of a cove at Dorset coastline

A

Lulworth cove

70
Q

tell me examples of headlands on Dorset coastline

A

Durlston head

Ballard point

71
Q

Tell me some beaches on Dorset coastline

A

Broad bench beach

72
Q

Tell me an example of an arch on Dorset coastline

A

Durdle door

73
Q

Tell me some cliff names on Dorset coastline

A

Seacombe cliff

Canford cliff

74
Q

Tell me some examples of spits on Dorset coastline

A

Sandbanks

Hurst spit

75
Q

Tell me an example of a salt marsh on Dorset coastline

A

Keyhaven salt marsh

76
Q

How is a cove formed

A

A line of weakness in a hard rock eg Portland stone allowed water through
Behind this hard concordant layer, soft rock allows erosion
Over time cove widens due to lateral erosion but neck stays quite narrow
When is reached a hard rock at back of cove, erosion is slowed and lateral erosion of soft rock continues

77
Q

Tell me the options of coastal management

A

Do nothing - let sea undertake natural processes

Hold the line- build protection st the current cliff face to prevent further damage

Advance the line - build defences aimed at reclaiming small areas of land to assist with protection

Managed retreats - allow some managed loss

78
Q

Tell about groynes

A

Designed to build up material on one side to prevent it being moved by LSD

Starved material downwind of material
Life span 20-30 years
Relatively cheap £5000 each
Cause barrier for pedestrians

79
Q

Tell me about rock armour

A

Large boulders piled along shoreline to form a sea wall

Allows some water through to disperse energy but reduces erosion of cliffs

Must be large strong rocks eg granite or basalt with are expensive
Quick to build

Natural looking

80
Q

Tell me about beach nourishment

A

Sand added to replace sand washed away

Absorb wave energy so it can’t reach cliffs to erode it

Must be replaced regularly
Natural appearance
Little environmental impact

81
Q

Tell me about gabions

A

Large steel mesh cages filled with Rocks at right angles to coastline

Absorb wave energy
Cheap £110 a metre
Only work on sandy beaches (pebbles would break them down)

Can be hazardous if not replaced when needed

82
Q

Tell me about sea walls

A

Concrete walls built to protect coast from erosion
Stops waves hitting coastline

Seen as ugly
Gives tourists place to walk
If poorly maintained could collspse leading to damage

83
Q

Tell me about dune regeneration

A

Artificial creation of dunes

Can take several heart for dunes to be established

Must provide walkways to avoid trampling

Cheap £2000 per 100m stretch

Improved coastal Eco systems

Natural and appealing

84
Q

Tell me about managed retreat

A

Creating a man made position for coastline - generally moving coast inland

Less chance of area flooding somewhere else

Long term sustainable

Less money spent on other problems

Can disrupt other area

Compensation for land and housing being destroyed a lot

Very expensive eg medmerry land £28 million

85
Q

Tell me about beach profiling

A

Material moved back by a storm is brought forward to protect areas behind

Expensive £200,000 a year due to time and equipment

Can seem artificial looking as high crest

No new material needed to be bought just added

86
Q

Tell me some reasons Bournemouth is worth protecting

A

Tourism £472.8 a year

Toursism employs 11,600

3000 homes at erosion risk

100 businessss at erosion risk

87
Q

Tell me some stakeholder groups

A

Tourist board

Bournemouth council

People further down coast

Environmental groups

Bournemouth locals

Developers eg builders