Coasts Flashcards
(128 cards)
1
Q
Name the sections of the littoral zone from cliffs/dunes to out at sea.
A
Backshore, foreshore, nearshore, offshore.
2
Q
Broadly outline the lithology of the UK coastline.
A
South East - mostly sedimentary
North - igneous and metamorphic
Cornwall - sedimentary and igneous
Wales - sedimentary (slate)
Norther Ireland got it all
3
Q
Give 2 example of low-energy coastlines.
A
Mediterranean Sea locations
East-Anglian coasts
4
Q
Give 2 examples of high-energy coastlines.
A
Atlantic coast of Norway
Atlantic coast in Scotland
5
Q
Give a UK example of a concordant coast.
A
South-facing Dorset coast line.
6
Q
Give a UK example of a discordant coast.
A
East-facing Dorset coast line.
7
Q
What rock types are present in the Dorset concordant/discordant example?
A
Clay/sand, chalk, limestone.
8
Q
What are rock strata?
A
Layers of rock
9
Q
What are bedding planes?
A
Horizontal cracks in strata (caused by gas)
10
Q
What are joints?
A
Vertical cracks in strata (caused by movement)
11
Q
What are folds?
A
Rocks buckling/crumbling due to pressure
12
Q
What are faults?
A
Stress/pressure is greater than internal strength, rock fractures and moves.
13
Q
What is dip?
A
The angle at which the strata lie.
14
Q
What rock characteristics produce steep cliff profiles?
A
Uniformed horizontal strata
15
Q
What rock characteristics produce overhanging cliffs with unstable tops?
A
Rocks dip gently towards sea with almost vertical joints.
16
Q
What rock characteristics produce a steep slope towards the sea?
A
Steep dip towards the sea (susceptible to rock slides).
17
Q
What rock characteristics produce stable, steep cliffs?
A
Rocks dip inland
18
Q
What rock characteristics form rough slopes towards the sea?
A
Rocks dip inland d with well developed joints at right angles to bedding planes.
19
Q
Explain the formation of a cove on a concordant coastline.
A
River flows overland into sea.
River cuts valley, exposing weaker soft rock behind hard rock layer.
Erosion on weaker rock forms small cove.
Continued erosion produced semi-landlocked cove (hard rock erodes much slower).
20
Q
Explain the formation of a Dalmatian coastline on concordant coastlines.
A
Valleys and ridges inland run parallel to coastline due to alternating hard/soft rock types. Sea level rise and land floods. Tops of ridges remain above sea level - now islands.
21
Q
Give the best example of a Dalmatian coastline.
A
Croatian coastline (Adriatic Sea - Mediterranean). >1000 islands, limestone cliffs and coves = tourism.
22
Q
Explain the formation of half coastlines on concordant coastlines.
A
Large amounts of sediment from a river settle in specific shallow ridges along a coastline. Stabilised by vegetation and forms an island/spit. Separates lagoons from the ocean.
23
Q
Give an example of a haff coastline.
A
South coasts of the Baltic Sea - Poland, Lithuania.
24
Q
Give an example of a coastal igneous rock and its erosion rate and permeability.
A
Granite. 1mm per year. Impermeable.
25
Give an example of a coastal sedimentary rock and its erosion rate and permeability.
Limestone/chalk. 2.5cm per year. Permeable (porous).
26
Give an example of a coastal metamorphic rock and its erosion rate and permeability.
Gneiss/marble. Almost entirely resistant. Impermeable.
27
Give an example of coastal unconsolidated material and its erosion rate and permeability.
Boulder clay. 1m per year. Very permeable.
28
How does vegetation stabilise sandy coastlines?
Roots bind sediment (less erosion). Reduce wind speed at ground level (less erosion more deposition). Dying plants add organic matter to sand - soil.
29
What is plant succession?
The way in which the vegetation on a sandy coastline changes over time influencing sand dunes and/or salt marshes.
30
What are pioneer species in reference to sand dune succession?
The initial plant species that colonise bare sand. Adapted to harsh conditions (e.g salt tolerant). Bind sand to form embryo dunes. Examples: sand couch, sea rocket.
31
What is the role of creeper plants in plant succession on sand dunes?
Creeper plants with leaves improve soil qualities of the sand by providing shade and binding qualities. Allows less adapted plants than pioneer species to colonise.
32
What is the role of marram grass in the second stage of sand dune plant succession?
Form yellow dunes by binding more sand by roots. Highly adapted - limited transpiration. Causes salt content to decline (rainwater removes salt content).
33
What is the name for the next-most-developed sand dune after yellow dunes that have less harsh conditions and can support a wider range of species?
Grey dunes / mature dunes.
34
What is a climactic climax community?
A local ecosystem of plants and animals that, through plant succession and development of vegetation, have reached a steady state.
35
What are waves caused by?
Friction between the wind and the sea surface.
36
What happens to a wave as it approaches the coastline (regular deep-shallow gradient)?
Velocity decreases and wave height increases.
37
Describe nearshore depth of destructive vs constructive waves.
Destructive deeper. Constructive shallower.
38
Compare beach profile of constructive vs destructive waves.
Destructive - steep shingle
Constructive - gently sloping sand
39
Compare frequencies of constructive and destructive waves.
Destructive: 13-15 per minute
Constructive: 6-8 per minute
40
Compare the type of movement within the wave in constructive and destructive waves.
Destructive - circular (deep + tall waves)
Constructive - elliptical (shallow + flatter waves)
41
Compare beach profiles of summer and winter beaches.
Summer (constructive): deposition at top of wave/beach forms berms. Steeper beach profile overall
Winter (destructive): backwash transports sediment offshore to form offshore bar. Shallower profile overall.
42
What is abrasion and attrition?
Attrition - rocks, sediment, pebbles hit each other to become smaller and more rounded.
Abrasion - destructive waves pick up this stuff and hit it against the cliff causing erosion.
43
Name the erosional landforms on a headland.
Crack, cave, arch, stack stump
44
Name an example of a wave-cut platform.
Lyme Regis (Dorset). Layers of limestone and shale eroded.
45
What are the 4 forms of marine transportation of material?
Traction (roll), saltation (bump/bob), suspension, solution.
46
Describe process of longshore drift.
Wave washes up beach at angle with prevailing wind. Backwash pulls back perpendicular to coastline. Net effect is lateral shift of material. Destructive waves (removes sediment) erode beach.
47
Describe the formation of a spit.
Dominant LSD direction. Gap in coastline (estuary/bay). LSD causes sediment to still be carried a short way then be deposited. Narrow strip of land forms. If estuary: flow prevents further deposition + split ends (double spit = spit on other side also ends). If bay: spit may continue to other end to form barrier beach / bar. Recurve spit due to tides, river current, wind direction change. Salt marsh forms behind.
48
What are the two types of deposition?
x - sediment in a salt marsh binds together and settles
y - sediment settles because gravity exceeds kinetic energy of the particles
49
Describe beaches and their depositional landforms.
Temporary store in sediment cell / coastal system. Berm - sediment deposited in same place at top of constructive waves. Beach cusp - waves that break at an angle are bent and have energy focused in certain areas, forming 'small hills' of sand along the beach. Storm ridge - extreme berm formed higher up the beach during a storm.
50
How do offshore bars form?
Destructive waves break before beach. Waves scour seabed and beach, deposit material offshore in a heap. + currents supplying sediment.
51
How do tombolos form?
Lower wave energy between a small offshore island and the mainland allows deposition. Sand and shingle forms beach/ridge between. May be covered at high tide.
52
How do cuspate forelands form?
Longshore drift in opposite directions meet. Sediment deposits and is consolidated by vegetation to prevent erosion. Can extend 3m or 3 miles out to sea.
53
What is the sediment cell concept?
A relatively self-contained closed system of sediment sources, transports and sinks along a coastal stretch.
54
How many sediment cells are there in England and Wales?
11
55
Sediment cells are theoretically in what?
Dynamic equilibrium.
56
How does a sediment cells maintain equilibrium?
Negative feedback - one change causes another change which reduces the impact of the initial change, maintaining equilibrium.
Positive feedback - increases change in a system until a new equilibrium is reached.
57
What are the 3 types of weathering?
Mechanical, chemical, biological.
58
Describe salt crystallisation weathering.
Waves splash on rocks - puddles evaporate to leave behind salt crystal compounds in joins and cracks. Crystals grow - pressure on rock forcing it apart. Process is more damaging when in porous rock.
59
What landforms are seen as a result of mechanical weathering?
Angular rock fragments fall to create scree slopes at the base of a cliff.
60
Name and describe a type of chemical weathering.
Carbonation. CO2 in atmosphere combines with rainwater to form weak carbonic acid. Reacts with calcium carbonate in specific rocks - limestone & chalk.
61
What is seen on a rock that is being chemically weathered?
Crumbling.
62
Name 3 ways in which biological weathering can take place.
Roots in rock cracks - widen and weaken
Water running though decaying vegetation becomes slightly acidic (chemical weathering)
Animals burrowing into cliffs weaken structure
63
What is the slowest form of mass movement?
Soil creep (slow, continuous movement)
64
What causes an earthflow or a mudflow?
Increase in the amount of water reduces friction - earth/mud slides over bedrock. Material becomes jumbled up (so it isn't a slide).
65
What are the most likely conditions to cause rockfall?
Strong, jointed, steep cliffs exposed to mechanical weathering. Slope over 40 degrees.
66
What are the conditions most likely to cause rock slides?
Rocks that are jointed or have bedding planes parallel to the slope or cliff surface.
67
What is the difference between sliding and slumping?
Slumping has rotational movement and is more common steeper slopes.
68
What conditions of rock are most likely to cause slumping?
Softer materials - clay/sand - overlie harder rock - limestone/granite.
69
What landforms does slumping cause?
Terraced cliff profile and rotational scars.
70
How much have global average sea levels risen since pre-industrial levels?
21cm
71
What is the difference between isostatic and eustatic change?
Eustatic - sea level itself rises globally
Isostatic - local land level changes relative to the sea
72
What are the 2 contributors to eustatic change?
End of glacial period or global warming means:
Land ice melts and flows into the sea
Thermal expansion
73
What type of isostatic change happens during a glacial period and why?
Isostatic subsidence. Ice gives weight and pressure, land sinks.
74
Outline a case study for isostatic change.
North of UK isostatic rebound due to inter-glacial period. Scottish Highlands glacial rebound creating elevated plateaus. Other areas of Scotland have raised beaches.
75
What are the two emergent coastlines? Give an example of where are they found.
Raised beaches and fossil cliffs. Isle of Arran, west coast of Scotland.
76
What is a raised beach?
Former beach that is now above the high tideline due to isostatic recovery. Old wave cut platforms and caves become exposed.
77
What is a fossil cliff?
Near-vertical slope initially formed by marine processes found some distance inland due to isostatic recovery. May have erosional features on them. Found behind a raised beach.
78
What are 3 submergent coastlines?
A ria, a fjord, a Dalmatian coast
79
What is a ria and give an example.
Flooded river valley (V-shaped). Sydney, Australia - natural, deep harbour.
80
What is a fjord and give an example.
Flooded glacial valley (U-shaped). May go deeper in land than rias. Multiple ares of Norway.
81
How many islands are in Kiribati?
33 islands across a wide area in the Pacific.
82
What are Kiribati's islands and how low do most of them lie?
Sand and mangrove atolls. 1m or less above sea level in most places.
83
How much are sea levels rising in Kiribati in some areas?
1.2cm / year (4x higher than global average).
84
What problems is Kiribati facing currently?
Saltwater intrusion impacting food security.
Increased vulnerability to storm surges.
85
What problems will Kiribati face in the future?
Many islands may be underwater in the next 50 years.
86
What action has Kiribati taken so far?
Purchased 20km^2 of land in Fiji to guarantee food security and provide land for the first people displaced by rising sea levels.
'Migration with dignity' policy allows smooth transition (including a job) into neighbouring countries e.g. New Zealand.
87
List physical factors that impact rate of coastal retreat.
Geology and lithology
Marine processes (wave type, tides, submergent coastlines)
Subaerial processes
88
List human factors that impact rate of coastal recession.
Coastal defences and management
Offshore dredging
Coastal development
89
Explain a human impact on rates of coastal recession in Egypt.
95% Egypt population on Nile Delta. Aswan dam built and reduced sediment flow from Nile from 130mil tonnes per year to 15mil. Erosion rates at some places increased 10x. Nile delta also subsiding. Massive risks of: salt pollution, coastal flooding and retreat.
90
Explain a human impact on rates of coastal recession in Australia.
Dredging offshore great barrier reef for sand for beach nourishment. Increased swell due to deeper bay: more erosion required defences and impacted business (fishing and tourism). Marine ecosystems impacted.
91
Why is coastal erosion at Holderness, Yorkshire such an issue?
The coastline is mostly boulder clay.
Powerful swell from Atlantic ocean.
Eroded material transported away from Holderness (South or out to sea).
92
What are rates of coastal recession in Holderness?
About 1-3m per year, up to 7m one year.
93
Why has much of the Holderness coastline been left undefended?
It is 80km. Economic cost of coastal defences would outweigh the benefits.
94
What have the responses to the rapid rates of coastal recession in Holderness been?
Sea walls built in front of most highly populated ares.
Groynes put in many places to reduce loss of sediment South. Causes chronic groin syndrome.
95
What is the average rate of coastal erosion in Cornwall and what is the most common rock type?
0.03-0.3cm per year. Granite - igneous.
96
How do mangroves reduce the risk of coastal flooding (3 reasons)?
Dissipate wave energy slowing erosion.
Roots trap sediment, raising height of the coast and further slowing erosion.
Reduce storm surge levels by 0.5m for every 1km of seawater that the seawater has to pass through.
97
Why is Bangladesh at risk to coastal flooding?
70% of land <10m above sea level.
One of most densely populated countries in the world.
Lies on flood plains of 3 major rives ad many other minor ones.
Have monsoon seasons.
Head of Bay of Bengal which funnels storm surges.
98
How has subsidence worsened Bangladesh's flood risk?
Some islands sunk up to 1.5m last 50 years. This + eustatic change ain't good.
99
How has removal of mangroves worsened the flood risk in Bangladesh?
Up to 200m of mangrove removal on Bangladesh coastline for economic (tourism and shrimp aquaculture) purposes. Massively exposes coastline to erosion and flooding.
100
What was the most recent impactful cyclone in Bangladesh?
Cyclone Sidr 2007.
101
What was the category of Cyclone Cidr and what was the height of the storm surge?
Category 4, 6m.
102
What was the death toll of Cyclone Sidr?
>3000
103
What was the total economic cost of Cyclone Cidr?
$2bn
104
What was the height of the 2013 storm surge on the East coast of England during the North Sea storm surges?
6m in places such as Norfolk.
105
What was the death count of the 2013 storm surges in Britain?
Zero, nil, nothing, 0.
106
What was the cost of the 2013 UK storm surges?
$1bn
107
Why were the flooding impacts of the 2013 storm surges limited?
Thames barrier, good sea defences, good forecasting and 18,000 evacuated.
108
Describe the Philippines in terms of population and geography.
Roughly 100 mil population spread over many low-lying islands.
109
Why is the Philippines experiencing twice the global average of sea level rise?
Isostatic sinking due to excessive groundwater abstraction.
110
Why is the Philippines so vulnerable to coastal flooding?
20 tropical cyclones per year. Typhoons can leave 80% of the capital city (Manila) underwater.
111
What was the death toll of Typhoon Haiyan 2013?
6000
112
Why is coastal flooding in the Philippines so economically destructive?
Rapid urbanisation in areas at risk of flooding. 2% GDP per year lost in activity and further 2% in damages due to coastal flooding.
113
What are revetments?
Sea walls for brokies.
114
What are offshore breakwaters?
Granite boulders dropped in shallow nearshore waters aligned parallel to shore. Dissipate wave energy before they reach the coast.
115
What is cliff re-grading?
Adjusting the gradient of the cliff to reduce erosion as the destructive wave simply washes up and down.
116
Why is Lyme Regis vulnerable to coastal recession?
Town constructed on unstable cliffs. Limestone and Clay. Once clay is eroded, Limestone cliffs become vulnerable - issues of mass movement (destroy houses).
117
What was phase 1 (around 1990s) of the Lyme Regis management scheme?
Small sea wall constructed near the river protecting housing. Emergency cliff stabilisation: large nails hold cliff together and drainage improved.
118
What was phase 2 of the Lyme Regis management scheme around 10 years later?
£22 mil. Creation of new sea walls and promenades. Creation of sand and shingle beach in front of sea walls to absorb energy. Rock armour to protect harbour wall (the Cobb).
119
What was phase 3 of the Lyme Regis management scheme?
Plans to prevent landslides and erosion West of the Cobb scrapped as costs outweighed benefits (less housing here).
120
What was phase 4 of the Lyme Regis management scheme?
£20 mil. 390m sea wall built in front of existing one. Cliffs stabilised by 19m long nails and improved drainage. Large long-term mesh also introduced over clay cliffs. Protected 480 homes.
121
3 positive impacts of Lyme Regis management scheme.
Harbour protected - fishing industry can thrive.
Sea front more attractive (promenade, beach nourishment) - tourism.
Effective against recent storms.
122
3 negative impacts of Lyme Regis management scheme.
Impact coastal processes causing less deposition elsewhere, causing displaced conflicts.
Stabilised cliffs reduce numbers of fossils found
Negative impacts of increased tourism such as litter.
123
What modern approach to coastal management is used?
Integrated Coastal Zone Management (ICZM) which is a holistic management strategy which considers entire littoral cells.
124
What ICZM strategy is recommended at all England and Wales sediment cells?
Shoreline Management Plans (SMPs).
125
What are the 4 options for SMPs?
Hold the line
Advance the line
Managed retreat
No active intervention
126
Where was the first SMP in England?
Yorkshire - sediment cell including Holderness 2002.
127
What processes are carried out to decide what action takes place in SMPs?
Cost-Benefit Analysis (CBA)
Environmental Impact Assessment (EIA)
128
What did the Holderness CBA conclude?
Cost outweighed benefits on majority of natural coastline - no active intervention.
Benefits outweighed costs at town/villages e.g. Hornsea.
Gas terminal protection benefits outweighed costs.
Spurn point managed retreat benefits outweighed costs.
