Coasts Flashcards

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
What's attrition
Material carried by waves bump info eachother and are smoothed and broken down into smaller pieces
26
What's hydraulic action
Waves enter cracks (faults ) in coastline and compress air within crack When wave retreats the wake expands causing a minor explosion
27
What's corrosion/ solution
Chemical action of sea water, acids in salt water dissolve rocks on the coast Limestone and chalk prone to it
28
What's abrasion and corrasion
This is a process where coast worn down by matieral carried by waves hit the rock sometimes at high velocity
29
What's a headland
Area of resistant rock which protude (stick out) from coastline
30
What's a bay
Area of soft rock between 2 headlands that erodes quickly
31
How does a bay form
When there's is variation in rock type the softer rock erodes faster and over hundreds of years a bay is formed
32
What's the difference between coves and bays
Coves due to rock type changing parallel to sea Bays due to variation so bands of rock meet at a right angle to sea
33
Describe formation of a wave cut platform
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)
34
Explain the formation of a stack
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
35
What is the cause of waves
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
What's traction
Pebbles and larger sediment rolled along sea bed
37
What's saltation
Load bouncing/hopping along the sea bed eg small pieces of shingle
38
What's suspension
Small particles eg silts are carried in water which make it appear cloudy
39
What's solution (transportation)
Dissolved chemicals in sea water carried in solution - not visible
40
Define longshore drift
The transport of sediment along a stretch of coastline caused by waves approaching the beach at an angle that's not 90 degrees
41
When does deposition occur?
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
What is a beach/ tell me some stuff
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
Where does sea material come from
Material at mouth of rivers Cliff erosion
44
What are orthogonals
Lines to show concentrations of wave energy in wave refraction
45
What's wave refraction
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
What are the 2 types of beach
Sandy and pebble
47
Tell me about sandy beaches
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
Tell me about pebble beaches
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
Tell me the orders of shores starting from furthest away from cliff face
Offshore, nearshore, foreshore, backshore, coastal terrain
50
Tell me about the offshore
Destructive waves drag beach depositors offshore from berms or sand dunes: forming an offshore bar- lowers height of beach Waves are not breaking
51
Tell me about the nearshore
This is where waves breaks
52
Tell me about the foreshore
Inter tidal zone that is covered then uncovered by changing tides - where sea hits sand
53
Tell me about the Backshore
Not usually affected by waves so usually dry Berms form
54
Tell me about coastal terrain
Dunes or storm beach cliffs or plain too Rarely affected by waves
55
What's a berm
Terrace in backshore, above the water level at high tide, formed in calm weather when constructive waves transport material
56
What's a spit
A spit is a finger of land made of sand and shingle thag extends into the sea from a coastline
57
How does a spit form
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
How does a bar form
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
Where are sanddunes found
On the backshore of the beach
60
What are some essential conditions for sand dunes to form
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
Tell me what creep is Aeolian transportation
Large material rolled along beach surface
62
What's saltation Aeolian transportation
Small material bounced along surface by wind
63
What's suspension Aeolian transportation
Smaller/ fine sand and material carried in wind
64
Tell me how a sand dune forms
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
Tell me the order of the way sand dunes are named starting from the sea moving back inland
Embryo dune Fore dune Yellow dune Grey dune Mature dunes
66
What's a concordant coastline
Where bands of different rock types run parralel to coastline
67
What's a discordant coastline
Layers of rock run at right angles to coast
68
Tell examples of bays on Dorset coastlines
Swanage bay Christchurch bay Pool bay Stud land bay
69
Tell me examples of a cove at Dorset coastline
Lulworth cove
70
tell me examples of headlands on Dorset coastline
Durlston head Ballard point
71
Tell me some beaches on Dorset coastline
Broad bench beach
72
Tell me an example of an arch on Dorset coastline
Durdle door
73
Tell me some cliff names on Dorset coastline
Seacombe cliff Canford cliff
74
Tell me some examples of spits on Dorset coastline
Sandbanks Hurst spit
75
Tell me an example of a salt marsh on Dorset coastline
Keyhaven salt marsh
76
How is a cove formed
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
Tell me the options of coastal management
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
Tell about groynes
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
Tell me about rock armour
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
Tell me about beach nourishment
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
Tell me about gabions
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
Tell me about sea walls
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
Tell me about dune regeneration
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
Tell me about managed retreat
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
Tell me about beach profiling
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
Tell me some reasons Bournemouth is worth protecting
Tourism £472.8 a year Toursism employs 11,600 3000 homes at erosion risk 100 businessss at erosion risk
87
Tell me some stakeholder groups
Tourist board Bournemouth council People further down coast Environmental groups Bournemouth locals Developers eg builders