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• Demonstrate an understanding of wave processes in eroding a
coastline and re-sorting and depositing materials removed through
erosion. Candidates should understand the types of waves
(constructive and destructive) and the components of waves, swash
and backwash. The erosional processes of wave action should
include an understanding of corrasion, hydraulic action, corrosion
and attrition.
Transport of material along a coastline should be appreciated;
onshore and offshore movements together with an understanding of
movement along a coastline (longshore drift). The action of wind in
shaping coastal sand dunes should also be understood.
• Describe and explain the landforms associated with these
processes.
• Describe the conditions required for the development of coral
reefs.
• Describe fringing and barrier reefs and atolls.
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A study should be made of the following coastal landforms:
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Cliffs, wave-cut platforms, caves, arches, stacks, bay and headland
coastlines, beaches, spits and bars, coastal sand dunes and marsh.
Powerful swash moves material up beach;
Weak backwash does not get chance/have
energy to remove it; or swash is stronger
than backwash. Therefore beach material
builds up over time;
Larger material carried further up beach;
Gentle slope reduces speed – causes
sedimentation;
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Abrasion, hydraulic action, attrition and
solution
These depend upon the energy of the wave,
i.e. they are strongest during high tides and
storms
Cliffs and wave cut
platforms
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There are hard/soft rocks (or
examples) outcropping/rocks of
different resistance;
rocks at right angles to coast;
discordant coastline;
bays formed in soft rocks,
Headlands hard rocks;
differential erosion occurs;
soft rocks worn more
rapidly/hard rocks worn less
rapidly etc
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Longshore drift
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LSD moves material from the cliffs at
Dawlish
The power of the Exe stops the spit
growing across the estuary.
Salt marsh behind with low energy
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deposition by wind as energy of winds
blowing from Poole Bay is reduced,
Easterly onshore winds pick up dry sand from
the beach,
obstruction on beach/pebble/seaweed causes
eddies/sheltered area; marram grass
colonizes dunes and traps further sand etc.
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Deposition of sediment/alluvium by
river, as speed of flow reduced
when it reaches Gulf of Mexico so it
slows down and cannot carry load,
especially as river is heavily laden
with silt due to it eroding its banks
in states such as Missouri,
absence of major tidal flows or
currents in Gulf of Mexico,
impact of salt water causes further
deposition,
growth of vegetation raises it
above sea level,
distributaries form as the channel
splits south of New Orleans
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Warm water/seas; temperatures above 20
degrees C
Shallow water; not more than 60 metres deep
Water free from sediment with availability of
light;
Plentiful supply of oxygen in water
unpolluted;
Plentiful supply of plankton;
Lack of strong currents.
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We can look at the reefs off Mombasa which
form part of the Mombasa Marine park. Here
the average water temperatures vary between
25°C and 31°C. the water off Jomo Kenyatta
beach is shallow, less than 10 m at 500m off
shore. There is no sedimant from any nearby
rivers and the strict pollution laws mean that
the water has a plentiful supply of oxygen