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A level Geography > Coasts > Flashcards

Coasts Flashcards

1
Q

what are the processes affecting coasts?

A
  • weathering
  • erosion
  • transportation
  • deposition
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2
Q

what is dynamic equilibrium?

A

when inputs and outputs are balanced

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3
Q

what is negative feedback?

A

negative feedback reduces some of the change by reducing some of the inputs, returning the system to stability

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4
Q

what type of system are coastal environments?

A

open systems with inputs, stores, flows and outputs

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5
Q

what is positive feedback?

A

moves the system away from its equilibrium state causing further change

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6
Q

what are high energy coasts characterised by?

A

destructive waves, long fetches, high rates of erosion, caves, cliffs, wave-cut platforms, arches, stumps

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7
Q

what are low energy coasts characterised by?

A

constructive waves, shorter fetches, high rates of deposition, sand dunes, spits and bars

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8
Q

what are constructive waves?

A
  • low frequency
  • long and low
  • swash stronger than backwash= deposition
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9
Q

what are destructive waves?

A
  • erosional
  • high frequency
  • steep and high
  • backwash stronger than swash
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10
Q

what are littoral/longshore currents?

A

when a flow of water runs parallel to the shoreline in areas where waves approach at an angle, moving water and sediment along

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11
Q

what are rip currents?

A

strong currents that flow away from the shoreline

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12
Q

what is upwelling?

A

movement of cold water to the surface

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13
Q

how do tides work?

A
  • water is pulled towards the moon, bringing a high tide on each side of the Earth
  • these high tides follow the moon as it orbits the sun
  • when the moon, sun and earth line up a spring tide occurs- happening twice a month
  • when the moon and sun are perpendicular, a neap tide occurs- twice a month
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14
Q

what is the tidal range?

A

the difference in height between high tide and low tide

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15
Q

what is abrasion?

A

where pieces of rock are picked up by waves and hit against the bed, the beach or the cliffs

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16
Q

what is corrosion?

A

chemical reaction between sea water and susceptible rock eg. limestone

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17
Q

what is attrition?

A

where piece of bedload are hit against one another

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18
Q

what is hydraulic action?

A

force of waves being compressed into cracks of the rock. Breaks down rocks and cliff

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19
Q

what is suspension?

A

small material is picked up and carried by sea water

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20
Q

what is mechanical weathering?

A

when rocks are broken down without their chemical composition being changed
salt weathering is the main type:
- seawater gets into cracks in rocks
- salt crystals form when the seawater evaporates, these crystals then expand and put pressure on the rock
- the repeated evaporation of saltwater widens the cracks in the rocks until they break apart

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21
Q

what is biological weathering?

A

biological weathering is when rocks are broken down by living things eg. animals/plants

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22
Q

what is chemical weathering?

A

when rocks are broken down because of their chemical composition being changed eg. carbonation weathering

23
Q

what is mass movement?

A

when rocks and loose material shift down slopes. This happens when gravity overcomes the force supporting the material

24
Q

what are the coastal transfers?

A

LSD, onshore and offshore winds and tides

25
Q

how does LSD work?

A
  • wind approaches the coast at an angle because of prevailing wind direction- this is the way swash moves
  • gravity is the only force that acts on backwash, so it falls back to the sea at right angles to the coastline
  • because of the difference between the angles of swash and backwash, sediment repeatedly moves in the shape of a right-angled triangle
26
Q

what is a concordant coastline?

A

have alternating bands of hard rock and soft rock parallel to the coast

27
Q

what is a discordant coastline?

A

alternating bands of hard rock and soft rock at 90° to the coastline eg. Dorset coastline

28
Q

what is a Dalmatian coast?

A

made up of offshore islands and coastal inlets running parallel to the coastline eg. lulworth cove

29
Q

what is usually found on discordant coastlines?

A
  • bays and headlands
  • retreating less resistant rock changes shape of coastline and causes wave refraction- increasing rate of erosion= formation of headland features
30
Q

how is a wave cut platform formed?

A
  • sea attacks base of cliff between the high and low water mark
  • a wave cut notch is formed by erosional processes- a dent in the cliff
  • as the notch becomes bigger in size the cliff becomes unstable and collapses and retreats
  • continues to make platform
31
Q

how are caves formed?

A
  • cracks are widened in the headland through the erosional processes of hydraulic action and abrasion
  • as the waves continue to erode the crack, it begins to open up and hollow out to form a cave
32
Q

how are arches formed?

A
  • when caves are eroded right the way through the headland, an arch is created eg. durdle door
33
Q

how are stacks formed?

A

when the top of an arch collapses a column called a stack is formed
continued erosion of a stack forms a stump

34
Q

how is a bar formed?

A

when a spit grows across a bay

35
Q

how is a spit formed?

A
  • an extended stretch of beach material that projects out to sea and is joined to mainland on one end
  • LSD moves material along coastline
  • spit forms when material is deposited, waves cannot get past spit
36
Q

what is a tombolo?

A

when a spit joins an offshore island

37
Q

what is an emergent coastline?

A
  • emergent coastlines cause the formation of raised beaches and fossil cliffs caused by isostatic rebound
  • a raised beach and fossil cliffs are formed when, following an ice age, the land rebounds. This causes the original height of land to increase.
  • this leaves behind a beach and fossil cliff higher than their original position
38
Q

what is a submergent coastline?

A
  • submergent coastlines cause the formation of rias, fjords and Dalmatian coasts
39
Q

what is isostatic sea level change?

A
  • isostatic change refers to the level of land, which is also influenced by ice ages
  • during an ice age, the weight of the ice forces land to sink
  • when the ice age has finished, the melting of the ice causes the land to rebound back up, like a spring
40
Q

what is tectonic change?

A
  • tectonic change causes land to either rise or sink at the boundaries where tectonic plates meet
  • a sudden change in the movement can lead to a rise or fall in the seabed
41
Q

what is eustatic change?

A
  • eustatic change is the rising and falling of sea levels
  • water is stored in the form of ice, ice age=sea levels fall
  • ice melting= rising sea level
42
Q

why are higher sea levels a risk?

A
  • cause higher tides increasing frequency of coastal flooding
  • higher tides can remove materials from beaches, leaving cliffs less protected
  • increased frequency of storms due to higher energy of the sea
43
Q

what are the impacts of climate change?

A
  • climate change is changing the frequency and intensity of low-pressure depressions and tropical storms
  • rising global temps are causing oceans to warm, triggering these low pressure systems
  • this increases the risk of coastal flooding and creates unusual weather conditions
44
Q

what is a storm surge?

A

a coastal flood of rising water commonly associated with low pressure weather systems

45
Q

what are the consequences of coastal recession?

A
  • damage to houses and businesses mean that people are forced to relocate whilst repairs are done and financial support is needed to support this
  • many people in less developed countries depend on intl aid
  • in developed countries many people cannot get enough insurance to cover potential damages, and many houses lose value as the rate of coastal recession increases
46
Q

what are groynes?

A
  • stone or wooden fences that stick out at 90° to the coast to stop material being transported by LSD
  • they are cheap and effective
  • beaches further down get starved
47
Q

what are sea walls?

A
  • hard concrete walls that deflect waves, refract wave energy back to the sea
  • good long-term solution as requires little maintenance
  • expensive/ugly
48
Q

what are revetments?

A
  • angled walls placed just offshore to assist in breaking down the force of the waves
  • cost effective
  • regular maintenance needed
49
Q

what is rip-rap?

A
  • a pile of boulders to dissipate the waves energy
  • long lasting and relatively cheap
  • hazard for people accessing beach
  • gaps between rocks allow erosion to cotinue
50
Q

what is beach nourishment and reprofiling?

A
  • moving material from the upper sections of a beach elsewhere
  • slows down waves by widening beaches and so reduces the risk of erosion and flooding
  • maintains beach for tourism, supporting local economy
  • threatens organisms
51
Q

what is ICZM?

A

ICZM (integrated coastal zone management) deals with holistic coastal management strategies

  • careful consideration for the most effective management approach
  • considers risk to building/local economy/natural environment
52
Q

what are the benefits of ICZM?

A
  • promotes careful conservation of natural environment
  • encourages efficient use of resources
  • tries to reduce potential loss to stakeholders who rely on coastal regions for their livelihoods
  • inclusive of all parties
53
Q

what is a ria?

A

a valley that has been partially submerged by water formed by a substantial rise in sea level or a fall of landmass on a coastline

54
Q

what is fjord?

A

an inlet that is long and narrow in shape, with steep cliffs on either side. Formed by the movement of a glacier that cuts rock formations, forming steep ridges either side of a valley and the valley fills with water

A level Geography (17 decks)

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