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Full geog > Coasts (KQ1) > Flashcards

Coasts (KQ1) Flashcards

1
Q

What is the coastal area made up of?

A
  • offshore
  • nearshore
  • foreshore
  • backshore
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2
Q

What different coastal environments are there?

A
  • cliffed
  • sandy
  • muddy
  • rocky
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3
Q

What factors affect coastal environments?

A
  • geology
  • waves
  • ecosystems
  • tides
  • currents
  • human activities
    (remember GWETCH)
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4
Q

How do waves develop?

A
  • waves develop when energy from wind blowing across seas and oceans are transferred to the water surface
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5
Q

What is wave movement affected by?

A
  • wind direction
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6
Q

How do waves crash onto the shore?

A
  • onshore winds push waves towards the coast
  • this results in waves crashing onto the shore
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7
Q

What is wave length?

A
  • horizontal distance from crest to crest
  • or trough to trough
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8
Q

What is wave frequency?

A
  • number of wave crests or troughs that pass a fixed point in one second
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9
Q

What is wave height?

A
  • vertical distance between the crest and trough
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10
Q

What is a crest?

A
  • highest part of the wave
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11
Q

What is a trough?

A
  • lowest part of the wave
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12
Q

How do water particles move?

A
  • in an orbit
  • decreases with depth
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13
Q

What factors affect wave energy?

A
  • wind speed
  • wind duration
  • fetch
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14
Q

What is fetch?

A
  • distance that wind has travelled over seas and oceans to form waves
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15
Q

How does wind speed affect wave energy?

A
  • the faster the wind blows, the greater the wave energy
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16
Q

How does wind duration affect wave energy?

A
  • the longer the wind blows, the larger the waves
  • results in greater wave energy
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17
Q

How does fetch affect wave energy?

A
  • the greater the fetch, the more energy waves have
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18
Q

How can the amount of energy present in a wave be told?

A
  • wave steepness
  • wave period
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19
Q

What is wave steepness?

A
  • ratio of wave height to wave length
20
Q

What is wave period?

A
  • the time waves take to travel through one wave length
21
Q

What is the relationship between wave energy and wave steepness as well as wave period?

A
  • the higher the wave energy, the steeper the wave and the shorter the wave period
22
Q

What do waves in the open ocean have?

A
  • long wave length
  • low wave energy
23
Q

What happens to waves near the coastline?

A
  • water is shallow
  • waves interact with sea bed
  • waves start to change shape at a depth equivalent to about half their wave length
24
Q

What happens to waves nearer the coastline?

A
  • base of the wave starts slowing down due to friction
  • thus, wave height increases and wave length decreases
25
Q

What happens to waves nearest the coastline?

A
  • base of the wave stops but wave crest becomes steeper and topples over
  • causes wave to break onto coast
  • releases energy of the wave
  • surfers ride on these
26
Q

What is the difference between backwash and swash?

A
  • backwash carries sediments from the shore into the sea
  • swash carries sediments onto the shore
27
Q

What are the two types of waves?

A
  • constructive
  • destructive
28
Q

What do constructive waves do?

A
  • strong swash, weak backwash
  • strong swash deposits materials on the coast
  • weak backwash only removes some materials
  • landforms on beaches are ‘constructed’ by strong swash and weak backwash
29
Q

What do destructive waves do?

A
  • weak swash, strong backwash
  • instead of depositing sediments onto the coast, destructive eaves erode coasts and transport rocks and beach materials away
30
Q

What are some differences between destructive and constructive waves?

A
  • constructive waves break on low gradient, low energy environments while destructive waves break on steep gradient, high energy environments
  • constructive waves are small and low while destructive waves are large and high
  • constructive waves have low wave height and long wave length while destructive waves have high wave height and short wave length
  • constructive waves have a lower wave frequency than destructive waves (6-8/minute vs 10-14/minute)
  • constructive waves have stronger swash and weaker backwash while destructive waves have weaker swash and stronger backwash
  • constructive waves occur on gentle coastal slopes and sheltered coasts and destructive waves occur on steep coastal slopes and open coasts
  • the deposition process is more prominent in constructive waves while the erosion process is more prominent in destructive waves
31
Q

What is wave refraction?

A
  • the process by which waves change direction as they approach the coast
  • this occurs as waves slow down due to interaction with the sea bed as they move towards the coast
32
Q

What is the process of wave refraction?

A
  • waves approach the headland and bend towards it
  • thus, more erosion will occur due to the wave energy being concentrated there
  • waves diverge when they reach the adjacent bays
  • more deposition will occur in bays where wave energy is spread out
33
Q

What are the different coastal processes present?

A
  • coastal erosion
  • sediment transportation
  • sediment deposition
34
Q

What are the 4 ways in which coastal erosion happens?

A
  • hydraulic action
  • abrasion
  • attrition
  • solution
35
Q

How does hydraulic action happen?

A
  • when waves strike against a rock surface, the waves trap air in the rock joints
  • the air is compressed by the oncoming waves
  • this exerts pressure on the joints
  • as air is repeatedly compressed, joints weaken and rocks shatter
36
Q

How does abrasion happen?

A
  • as waves break, sediments carried by waves such as sand and rocks are hurled against the coast
  • the loosened sediments knock and scrape against the coastal cliffs
  • this weakens the surface and breaks down the coast
  • over time, the impact from abrasion undercuts a cliff
37
Q

How does attrition happen?

A
  • when rock particles carried by waves rub or hit against one another
  • they break down into smaller pieces and become smoother and more rounded
38
Q

How does solution happen?

A
  • sea water chemically reacts with water soluble minerals in coastal rocks and dissloves them
  • for example, limestone rocks are easily eroded by carbonic acid
  • when solution of minerals occurs, rocks are weakened and disintigrate
39
Q

How are sediments transported along coasts?

A
  • beach drift
  • longshore drift
40
Q

What is beach drift the result of?

A
  • waves approaching the coast at an oblique angle
  • as waves approaching the coast at an oblique angle break on the beach, sediments move up the beach at an angle as swash and move perpendicularly down as backwash
  • the zigzag movement along the beach is known as beach drift
41
Q

How are longshore currents generated?

A
  • when waves approach the coast at an oblique angle, they generate longshore currents in the nearshore zone
  • they move sediments along the shore
42
Q

What are longshore currents?

A
  • ocean currents that flow parallel to the coast
43
Q

What is longshore drift made up of?

A
  • combined effect of sediment movement by longshore currents and beach drift
44
Q

When is longshore drift the most rapid?

A
  • when waves approach a straight coast at an angle of about 30 degrees
45
Q

How are the landforms present on cliffed coasts?

A
  • cliffs
  • shore platform
  • headland
  • bay
  • cave
  • arch
  • stacks

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