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Edexcel IGCSE Geography > Coastal Environments > Flashcards

Coastal Environments Flashcards

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1
Q

What are the four different types of (marine) erosion?

A
  • Solution
  • Abrasion
  • Hydraulic Action
  • Attrition

Erosion is the process where rocks are displaced, weathering is just where they are degraded

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2
Q

What is solution?

A

Chemicals like salts and acids react with and dissolve minerals and rocks, eroding them

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3
Q

What is abrasion?

A

A type of erosion where eroded material already in the waves are thrown at the cliffs at force, eroding parts of the cliff and breaking away rocks

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4
Q

What is attrition?

A

A type of erosion where rocks and pebbles already eroded into the sea collide with eachother repeatedly, eroding eachother and becoming smaller and smoother overtime

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5
Q

What is hydraulic action?

A
  • A type of erosion where destructive waves hit the base of a cliff, causing cracks to start appearing
  • When further waves hit the same cliff, water will penetrate the cracks and cause them to expand (from the force of the water)
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6
Q

What are the differences between a destructive and a constructive wave?

A
  • Constructive waves deposit sediment, building up beaches, while destructive waves tend to erode beaches
  • Constructive waves have a stronger swash, while destructive waves have a stronger backwash
  • Constructive waves have a long wavelength and are low in height, while destructive waves have a short wavelength and are high and steep
  • Constructive waves break at 6-8 waves per minute, while destructive waves break at 10-15 (the frequency is higher)

The point about swash and backwash is why constructive waves build beaches and destructive waves erode beaches

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7
Q

Which three factors affect how big a wave is?

A
  • The fetch (how far it has travelled)
  • Wind speed
  • How long the wind has been blowing for
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8
Q

What are the four movements of marine transportation and what do they do?

A
  • Traction (Stones rolling along the sea-bed)
  • Supension (Fine materials being carried by the sea)
  • Saltation (Small pebbles bouncing along the sea-bed)
  • Solution (Dissolved materials being carried by the sea)
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9
Q

What is longshore drift and what is its process?

A
  • Longshore drift is the main process of transportation of sediment along the coast
  • The prevailing wind causes waves to approach the beach at an angle
  • The swash of the wave carries material up the beach at that angle, but the backwash will take material down back to the sea in a straight line or a 90 degree angle, resulting in a zig-zag pattern
  • This process repeats, and sediment makes its way down the coast
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10
Q

What are the three types of sub-aerial weathering?

Subaerial means on land, not underwater or underground

A
  • Mechanical (freezethaw)
  • Chemical
  • Biological
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11
Q

What is mechanical weathering (freezethaw?)

A
  • Freezethaw is a type of weathering which is mechanical
  • Water gets in cracks in rocks during the day, and then at night when temperatures drop below zero, the water freezes
  • This causes the cracks to expand and the rocks to potentially break after this process repeats day and night many times
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12
Q

What is chemical weathering?

A
  • Rain reacts with carbon dioxide to form carbonic acid
  • This acid reacts with minerals in the rocks (like calcium carbonate)
  • Overtime, the rocks will dissolve
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13
Q

What is biological weathering?

A
  • Animals like rabbits can burrow in cracks making them bigger, breaking the rocks overtime
  • Tree roots can do a similar thing
  • Lichens and mosses can release chemicals which dissolve the rock overtime also
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14
Q

What is mass movement?

A

The downhill mass-movement of material under the influence of gravity

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15
Q

What are the three types of mass-movement?

A
  • Slumping
  • Landslides
  • Rockfall

They are usually caused by weathering, earthquakes or heavy rainfall

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16
Q

What is slumping?

A

When a large area of land on a cliff becomes saturated and heavy “slumps” down the cliff in one peice with the assistance of gravity, leaving a curved surface

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17
Q

What are landslides?

A
  • When a section of material slides down a slope
  • The section of material will stay together until it hits the bottom of the slope
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18
Q

What is rockfall?

A

When fragments of debris break away from a cliff and fall quickly down a cliff- face and land at the bottom of the cliff

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19
Q

What is a headland?

A

An area of land formed of resistant rock which protrudes out to sea

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20
Q

What is a bay?

A

An inland area made of less resistant rock which is usually found between headlands on a discordant coastline

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21
Q

How is a headland formed?

A
  • They are formed on a discordant coastline
  • The areas with rocks of lower resistance are eroded by marine erosional processes at a faster rate than the areas of higher resistant rock
  • The areas of higher resistant rock, which were not eroded as much, protrude out - this is a headland
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22
Q

How is a wave cut platform formed?

A
  • The power of the waves and erosional processes lead to the creation of a wave cut notch (an eroded hole at the bottom of a cliff)
  • Eventually, the wave cut notch gets so big that the section of cliff above cannot support its own weight and it collapses
  • This process repeats, and the cliff moves back and back, leaving an exposed section of hard rock visible at low tides known as the wave cut platform
  • The wave cut platform can be an emergent feature
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23
Q

What are the landforms of marine erosion which form on a headland in the order of which they form?

A
  • Cracks
  • Wave Cut Notch
  • Caves
  • Arches
  • Stacks
  • Stumps
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24
Q

How do these erosional landforms which form on a headland progress to become one another?

A

Marine processes of erosion and subaerial processes cause one to progress to another in a logical way

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25
Q

How are beaches formed?

A
  • Constructive waves deposit material such as shingle or sand onto the shore with their swash
  • This sediment is eroded over time through marine process of erosion such as attrition, making it smaller and smoother (rocks become sand)
26
Q

What is a spit how are they formed?

A
  • Spits are narrow projections of sand or shingle that are attached to the coastline at one end which extend across a part of the coastline where it changes direction
  • Sediment moving along the shore by longshore drift is deposited on an area of the coastline which is sheltered and shallowed where there is insufficient energy to carry the sediment further, and it builds up to form a spit with a salt marsh forming behind it
27
Q

What are bars?

A

Bars are when a spit full extends across the bay, leaving a lagoon behind it

28
Q

How does geology affect the coast?

A
  • Soft rock like sand and clay will be eroded easy to form low flat beaches and bays
  • Hard rock will be eroded less easily and will form headlands and steep cliffs
  • Soft = Smooth, gently sloping cliffs with vegetation
  • Hard = Rugged, bare, steep cliffs.
29
Q

How does vegetation affect the coast?

A
  • The main role is the protection of landforms from erosion and wind, preserving them
  • They also stabilise landforms like sand dunes and provide habitats for wildlife
  • It is an indication of how long the cliff has been there, as well as its gradient and how resistant the rock is
  • Vegetation can, however, contribute to biological weathering
30
Q

What are 2 ways in which people affect the coast?

A
  • Deforestation: More sediment is washed into the sea which destroys habitats like coral reefs, less protection is provided to landforms, the likelihood of flooding is increased (from the removal of trees like mangroves)
  • Ports and trade: Pollution is created by boats which degrades the water quality and can kill marine life, dredging of harbours can be required which will significantly disrupt marine flora and fauna
31
Q

How does sea level change affect the coast?

A
  • Sea levels can change from eustatic change (change of water levels) or isostatic change (change of land levels)
  • Rising sea levels create submergent coastlines, with submergent features like rias and fjords forming
  • Falling sea levels create emergent coastlines, with emergent relic features like raised beaches, wave cut notches and arches
32
Q

What is the distribution of mangrove swamps?

A
  • They are found 25 degrees north and south of the equator in warm tropical waters
  • Specific places include: The Carribean, Californian coast and Indonesia
33
Q

What are the features/characteristics of mangrove swamps? (What conditions are needed)

A
  • They are trees that live on coastlines with their roots submerged in shallow water of 0.5 to 2.5 metres
  • They need high levels of humidity (75-80%) and rainfall (1500mm-3000mm per annum)
  • They need temperatures of 27 degrees
  • Their roots trap mud and sand which builds up the intertidal zone into the new land
  • They help to prevent flooding and erosion by reducing wave energy and depositing sediment

The intertidal zone is the area above land at low tide and submerged at high tide

34
Q

What is the distribution of salt marshes?

A
  • They are found all over the coasts of the world
  • They are found in sheletered areas with low wave energy, such as behind a spit or sea defenses
35
Q

What are the features/characteristics of salt marshes?

A
  • They are areas of brackish (salty and fresh) water with nonwoody, salt-tolerant plants
  • It is constantly flooded, and is full of vegetation which forms over time
  • Because of the vegetation as well as creeks found in the marsh, the wave energy is slowed down and flooding is reduced
36
Q

How and where do sand dunes form?

A
  • Sand dunes form on any beach with sand, usually with a high tidal range and onshore wind
  • They form when wind blown sand is deposited against an obstruction and continues to grow in size
  • As they keep growing in size, more and more vegetation will colonise it, making it more stable
37
Q

What are coral reefs?

A

Coral reefs are depositis of calcium carbonate built on living organisms called coral polyps with algae growing on them in a symbiotic relationship

38
Q

What is the distribution of coral reefs?

A
  • They are found 30 degrees north and south of the equator
  • They are found around the Carribbean Islands, Florida and Australia
39
Q

What conditions are needed for coral reefs to form and why?

A
  • Temperatures between 23 and 29 degrees to survive
  • Shallow water and light for their algae to photosynthesise
  • Salinity between 32% and 42% to survive
  • Water with some wave action clear of sediment which could block light
40
Q

What are some biotic features of coral reefs?

A
  • The coral polyps
  • Producers like seaweed and phytoplankton (which grows on algae, providing nutrients from photosynthesis)
  • Consumers like turtles, dolphins and stingrays
  • Decomposers like bacteria and sea cucumbers
41
Q

What are some abiotic features of coral reefs?

A
  • Light
  • Depth
  • Temperature
  • Water
  • Salinity
42
Q

How are coral reefs threatened?

A
  • Pollution and intoxication from things like pesticide runoff
  • Acidification from carbon dioxide dissolving into the water, which causes bleaching
  • Overfishing messing up the ecosystem
  • Industrialisation and climate change causing rising sea temperatures and levels
  • Tourist activites like diving, and pollution and anchors from boats
  • Increased sediment in the water from things such as deforestation can block light, killing the algae and thus killing the polyps
43
Q

How are mangroves threatened?

A
  • Deforestation for timber and building materials, or for urban development
  • Mangroves are removed to make space for aquaculture
  • Overfishing damages ecosystems
  • Agriculture pollutes water with pesticides, damaging the mangroves
44
Q

How are salt marshes threatened?

A
  • Industrial and agricultural pollution (such as pesticides) which harms the wildlife
  • Salt marshes being cleared for development or agriculture
  • Noise and light pollution disturbing wildlife
45
Q

How are sand-dunes threatened?

A
  • Tourist activites, such as dune jumping can disrupt animal and plant life as well as destabalise the dunes
  • Sand-mining
46
Q

What might people want to use the coast for?

A
  • Development, such as homes, shops, roads ect.
  • Nature reserves
  • Industry
  • Agriculture
  • Fishing
  • Ports
  • Tourism
47
Q

Why might there be conflict at the coast?

A
  • The coast is a valuable area, and there are many different stakeholders who want it for different things, so there is a competition for space
  • Many of these things cannot both happen, such as conservation vs developement
  • For example, you cannot have a nature reserve and a harbour in the same place
48
Q

What are the causes of coastal flooding?

A
  • Low pressure storms like tropical cyclones cause sea levels to rise and then strong winds push the water on shore
  • Rising sea levels due to climate change
  • Particularily high tides, often combined with low pressure storms
  • Tsunamis
  • Estuaries can overflow due to heavy rainfall and high tides, causing coastal flooding
49
Q

How can you predict coastal floods?

A
  • Past records and patterns
  • Modern technology such as GIS and satellite tracking things like tropical cyclones and earthquakes
50
Q

How can you protect against coastal floods?

A
  • Coastal defences
  • Emergency centres on higher ground
  • Early warning systems
  • Don’t build in high risk areas and build flood-proof buildings
  • Education
51
Q

What are the four options for shoreline management plans?

A
  • Hold the line
  • Advance the line
  • Managed retreat
  • Do nothing

Decisions depend on money available, worth of the land in question and more

52
Q

What are hard engineering methods?

A
  • Methods of coastal defense where permanent and man-made structures are built and maintained
  • They are more expensive and unsightly, but are usually more effective
53
Q

What is a sea-wall and what are its advantages and disadvantages?

A
  • A wall, usually concrete, used to deflect wave energy
  • It is very effective at protecting against erosion
  • However, it is expensive, unsightly, restricts beach access and needs maintaining
54
Q

What are groynes and what are their advantages and disadvantages?

A
  • Wood or metal pilings built at right angles to the shore which traps material being moved by longshore drift
  • It slows down beach erosion and creates wider beaches
  • However it stop material from moving down the coast which may have been building and protecting a cliff downstream, and makes walking along the shoreline difficult
55
Q

What is rip rap and what are its advantages and disadvantages?

A
  • Large boulders piled up to protect a stretch of coast
  • They work well to absorb wave energy, and are fairly cheap
  • However, the boulders can be eroded or dislodged in storms, and it makes makes the beach less accessible
56
Q

What are gabions and what are their advantages and disadvantages?

A
  • Stacked wire cages filled with rock
  • They are extremely cheap and absorb wave energy fairly well
  • However they can break easily, need to be tied down and are not as effective as something such as a sea wall
57
Q

What are revetments and what are their advantages and disadvantages?

A
  • Sloping wooden or concrete fence with an open plank structure
  • As they have cracks they can break the force of the waves. They trap material behind them and are cheaper than sea walls but less effective
  • However, they are unsightly, inaffective in stormy weather and can make the beach inaccessible
58
Q

What are soft engineering methods?

A
  • Methods of coastal defence which work with natural processes rather than against them
  • They are cheaper, do not damage the coast, and do not look bad
  • However, they are not as effective
59
Q

What is beach-replenishment and what are its advantages and disadvantages?

A
  • Dumping sand or shingle onto a beach to replace eroded material
  • It absorbs wave energy and widens the beach front
  • However, it is quite expensive as it has to be repeated, and impacts sediment transportation
60
Q

What is cliff-regrading and what are its advantages and disadvantages?

A
  • The angle of a cliff is reduced to reduce mass movement
  • It prevents sudden loss of a large section of the cliff
  • However it does not stop cliff erosion
61
Q

What is sand-dune stabilisation and what are its advantages and disadvantages?

A
  • Fencing, hedging or revegatating to stablise sand dunes and reduce wind erosion
  • It is cheap, and protects against flooding and erosion
  • However, it is hard to protect larger areas of coastline cliffs

Edexcel IGCSE Geography (6 decks)

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