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Geogrpahy Igcse > Coasts > Flashcards

Coasts Flashcards

(61 cards)

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1
Q

What is a coast?

A

Where land meets the sea

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2
Q

What is a coastline?

A

the edge of the land marked though the high water mark on a low lying coast or the foot of steep sloped coasts

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3
Q

What is a shore?

A

Area between lowest and highest tide points

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4
Q

How often do tides occur? What is tidal range? How do tides affect waves and costal features?

A

Tides are twice a day (vary)
Difference between high and low tide = tidal range
-> Tide controls how waves work
-> Action of waves and currents contribute to coastal features

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5
Q

What are waves?

A

marine processes that erode, transport and deposit materials

Transfer of energy from wind blowing over the sea (result of friction)
Water doesn’t more -> energy is transferred

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6
Q

What affects the size of a wave?

A

Velocity of wind

Fetch (distance of water wind blows over (same direction as wind))

Time duration of wind (24 hours for full potential)

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7
Q

How do waves break onto the beach?

A

Wave approaches coast (shallower waters -> friction with sea bed -> wave leans forward -> breaks

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8
Q

What is the movement of the water on the beach called?

A

Swash -> up the beach
Backswash -> down the beach

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9
Q

What are the two types of waves ?

A

Constructive -> builds up beaches

Destructive -> erodes the beach

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10
Q

What are the characteristics of constructive waves?

A

Strong swash, weak backwash
Long wavelength (100+ m)
Low frequency (6-8/min)
Low energy
Low height (less than 1 m)

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11
Q

What are the characteristics of a destructive wave?

A

Weak swash, strong backwash
Short wavelength (20+ m)
High frequency (10-12/min)
High energy
High height (more than 1 meter)

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12
Q

What is marine erosion?

A

The process when marine processes (sea levels rise, strong wave action, coastal flooding) wears down the coast

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13
Q

What are the 4 processes in marine erosion?

A

Hydraulic action

Attrition

Corrosion/solution

Abrasion/corrasion

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14
Q

What is hydraulic action?

A

The force of the wave compressing air in the cracks of a cliff/rock

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15
Q

What is attrition?

A

Rocks and boulders are carried by the wave and bump into each other (smaller and smoother -> form shingles and sand)

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16
Q

What is corrosion/solution?

A

Slightly acidic and salty sea water gradually dissolves certain costal rocks

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17
Q

What is abrasion/corrasion?

A

Large waves pick up and throw rocks at the coast

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18
Q

What is marine transportation?

A

Movement of material in the sea and along the coast

Materials arrive from:
Erosion
Long shore drift
Constructive waves
Rivers

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19
Q

What are the 4 processes in marine transportation (+ definition)?

A

Traction: heavy material dragged along sea floor

Saltation: smaller material bounced along sea floor

Suspension: fine material held in water

Solution: dissolved material is carried in the water

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20
Q

How does long shore drift occur?

A

Prevailing wind makes waves approach at an angle -> wave breaks + swash carries material onto the beach (same angle as wave)-> swash dissipates and backswash carries material down perpendicular to the beach (gravity)

Creates zig-zag movement -> material transported down the coast

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21
Q

What is marine deposition?

A

When material is transported and dropped off by constructive waves

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22
Q

How is sediment sorted on the beach?

A

Largest material -> furthest from the sea -> swash deposits heaviest material first

Backwash lose energy/water as it moves back down because of sand porosity -> deposition of sediment gets finer and finer

Sorted by wave deposition

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23
Q

What is a beach berm and how is it formed?

A

If a destructive waveform due to a storm, then a large shingle is thrown above the usual high tide level to form a ridge at the top of the beach called a berm

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24
Q

How are cliff and wave cut platforms formed?

A

Many cliffs have wave cut notch (indent in foot of cliff)

Abrasion, corrosion and hydraulic action push the notch back

Cliff becomes unstable and collapse

Backwash carries the eroded material, and leaves a wave cut platform

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25
What is coastal retreat?
As the cliff is eroded and retreated, this is referred to as costal retreat
26
How are caves, arches, stacks and stumps formed?
Cliff -> resistant rock Erosion at weak points (crack, faults) and widens the weak points Weakness widens -> cave If located at a headland and erodes further (cuts through the platform)-> arches Base of arch -> wider but thinner -> roof of arch collapse -> stack Stack is undercut and collapses -> stump CASS
27
How are bays and headlands formed?
Found in areas with alternating resistant and soft rocks, perpendicular to waves Less resistant rock eroded back -> bay (inlet of sea where land curves inward, usually with a beach) More resistant rock -> left protruding -> headland
28
What are some features of headland?
Cliffs along all sides of the Projects into the sea Longer than it is wide Resistant rock
29
What are some features of bays?
Wide open entrance Roughly semicircular shape Land is lower than headlands Many beach (sheltered area -> good for deposition)
30
How are beaches formed?
Beaches -> best natural defense Tide and current move sediment and debris -> changes the beach (erodes and builds up) Formed in sheltered areas Constructive waves Usually formed in the summers (calmer weather)
31
What are the features of well sorted and poorly sorted beaches?
Well sorted: Uniform sediment and size Low energy conditions Sandy/muddy beaches Poorly sorted: Variety of sediment and size High energy conditions or extreme weather
32
How are spits formed?
Extended stretches of sand or shingle that extends out to sea from the shore Occur at change in coastline or mouth of river May have hooked end (if wind direction changes) Area behind spit -> sheltered (salt marshes or mud flats) Sediment transported by long shore drift -> coastline change have shallow shelter area for deposition of sediment -> more friction more deposition -> spit builds to sea level and extends
33
How are bars formed?
Spit grows across a bay -> bar is the bit of sand created
34
How are lagoons formed?
When a bar goes fully across a headland, a small body of water is isolated from the sea -> lagoon May fill with sediment to form land
35
What is a tombolo?
When a spit joins an island to the mainland
36
What is a barrier island?
Like a bar, but both ends are open
37
What are sand dunes?
Dynamic environment -> changes quickly Sandy beaches backed by sand dunes Winds + transport move dried and exposed sand -> sand trapped by obstacles -> Dune slowly moves inland
38
How are sand dunes formed?
Wind blown sand deposited against obstruction (pebbles or driftwood) -> more sand particles caught and dune grows -> ridges colonized and fixed by vegetation (succession)
39
What do pioneer species in sand dunes have to deal with with?
Salinity Lack of moisture (sand drains quick) Wind Temporary submergence in sand Rising sea levels
40
What are the different stages of sand dune formation?
Embryo dunes: Sand is trapped and deposition starts Pioneer: Lyme grass and sea couch grass Alkaline and little soil Max 1m tall Fore dunes: Embryo dune brings protection against winds Organic matter -> hospitable for plants Species: Marram grass -> stabilises the dune (roots) Max 5m tall Yellow dune: Initially yellow but darken (organic material) Marram grass dominates -> other flowering plants and insects in slacks 20% exposed Max 8m tall Gray dunes: More stable -> less than 10% exposed Good biodiversity Shrubs and bushes appear Soil acidity and water content increase 8-10m tall Mature dunes: Most old and stable Soil -> can support many varieties Final stage of succession
41
What is succession?
The change in an ecosystem, over time, of the species that occupies it
42
What is a dune slack?
Low lying areas in a dune system -> seasonal flooding and nutrients levels are low
43
Where can salt marshes form?
Aren’t temp dependent Intertidal ecosystem Flat with many channels Costal areas that are sheltered Tidal waters flow gently and deposits sediment Brackish (salty and fresh) water
44
What are the features of a salt marsh?
non-woody, salt tolerant plants Begin as tidal mud flats then gain height with sediment Tidal flooding ensured that the soil never dries out (daily floods) Pioneer species of halophyte plants Dead plants add nutrients and sediment to the soil
45
How are coral reefs formed?
Build up and compression of skeletons of lime secreting marine animals -> polyps Living coral polyps -> outer and upper parts Skeletons (hard masses) -> formed when one generation dies and next grows on top -> cause of direction of coral growth Need a solid surface to start Parallel to coast Sensitive -> need certain conditions
46
What conditions are needed for coral reefs to form?
within 30°N and 30°S latitudes Temperature (min 18°C, but ideally 22-25°C) Light (need to photosynthesis for algae (zooxanthellae) that live in the tissue) Water depth (less than 25m (light), clear and clean water) Salinity (33-42% salty water) Wave action (provide oxygen) Cannot be exposed to air
47
What are the 3 types of coral reefs?
Fringing (ex: coral coast of Fiji): Low and borrow bands of coral Parallel to coast around a land mass Covered by narrow and shallow lagoon at high tide Outer slopes -> steep into sea Barrier (ex: Great Barrier Reef): 500m-multiple km Separated from coast by by deep lagoons Atolls (Maldives Suvadiva): Narrow ring shaped reef Encircles lagoon Channels -> connects lagoon to sea
48
Why are mangroves the most successful ecosystem on earth?
Warm tropical areas, but is highly adaptable to changing conditions
49
What are some facts about mangroves?
Originated from Southeast Asia Mainly found in warm tropical waters and coastal swaps within 30° N and S Intertidal zones of the coast
50
What are some characteristics of mangroves?
Range in size from small shrubs to 60m Tangled roots form a dense thicket 75-80% humidity 1500-3000mm rainfall Ideal temp-27 degree Filtration system to keep salt out Snorkel like root -> easier to get air Prop roots -> trunks kept upright in soft sediment Colonises new land Fruit and seedling -> travel very far
51
What are some opportunites presented by coast?
Development (houses, shops, hotels, roads, school, restaurants, etc.) Nature reserves Swimming and sports Industry Dishing and aquaculture Tourism Agriculture Ports and harbors
52
What are some human induced hazards of coast?
Urbanisation and transport Change in land use, disposal of sediments and waste, congestion Loss of habitat, pollution, health risk, etc. Industry Land use change, power stations, extraction of natural resources Loss of habitats, pollution, costal erosion, decreased fresh water, etc. Agriculture Land reclamation, fertiliser/pesticide use, livestock density Loss of habitat, pollution, etc. Fisheries and aquaculture Ports and harbors, fishing gear, shrimp/fish farming Overfishing, impact of other species, pollution, invasive species Tourism and recreation Development, congestion, pollution, waste disposal, water activities Loss of habitat, disturbance of migration patterns, pollution, health risk
53
What are some nature induced hazards to coast (tropical storms)?
Tropical storm Hurricanes, typhoons, cyclones, tsunamis Destruction of infrastructure Heavy rainfall and storm surges Loss of ecosystem, habitats, etc Ship wrecks Losss of power and communication Millions of dollars in damage Reduce risks: Sea walls and artificial levees Evacuation plan Tracking and warning systems Good and strong Infrastructure Supplies and shelter
54
What are some nature induced hazards to coast (changing sea levels)?
Rising sea levels -> Ria and fjords Falling sea levels -> emergent coastlines Poses danger for low lying coasts and islands
55
What are some nature induced hazards to coast (erosion)?
Geology shapes the coastline Erosion: Less resistant rock -> faster erosion Long shore drift and destructive waves move sand and expose base of cliff -> coastal erosion Coastal management can cause erosion further down Other factors speed rate of erosion
56
What are some methods of costal erosion (soft engineering)?
Natural processes Less expensive and preserves looks Sustainable, but not as effective Beach replenishment Fencing, hedging, replacing vegetation Cliff regrading Managed retreat
57
What are some methods of costal erosion (hard engineering)?
Sea defenses Expensive to maintain and build Used when thing protected has great economic benefit Sea wall Groynes Rip rap Revêtements Gabions Offshore barriers
58
How can prediction help prepare for a flood?
Past records Modern tech -> satellite, monitoring system, weather stations, etc. Indicates possible strength and scale of damage can be predicted
59
What are some methods of prevention for coastal flooding?
Flood defenses Emergency centers Early warning systems Education Planning Designing buildings to withstand flooding Buffer zones
60
What are the four shoreline management plans?
Hold the line Long term and high cost Build and maintain costal defenses Hard engineering + soft engineering support Advance the line Build new defenses to extend the shoreline Land reclamation Both types of engineering Managed realignment Coastline moves naturally Process monitored and directed Soft engineering + hard engineering support Do nothing Controversial and cheap Allow erosion and retreat
61
How do governments decide what type of engineering is best?
Economic value of resources Cultural value of land Community pressure Social and historical communities

Geogrpahy Igcse (6 decks)

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