revision notes for Geography GCSE

1. Coasts GCSE
Revision

2. Erosion : breaking down of the rock particles being
carried downstream by the river.
TYPES OF EROSION:
•Hydraulic Action- water continually hits the rocks and
compresses air into cracks, when the wave goes out
the air rushes out and rock breaks away. The cracks
thus get bigger.
•Abrasion (or corrasion)-waves break and hurl rocks
and debris at the rocks to erode.
•Corrosion/ Solution- Chemicals within the water wear
away rock. Sea water and weak acids dissolve the rock
and minerals.
•Attrition- When rocks hit one another and get smaller
and break up.

3. WEATHERING
Weathering- the breakdown and decay of rock by
natural processes, without the involvement of any
moving forces.
•Chemical Weathering- Breakdown of rock by
changing its chemical composition (Acid Rain)
•Mechanical Weathering- Breakdown of rock without
changing its chemical composition( freeze-thaw)
•Biological Weathering- Roots of vegetation can grow
into cracks in a rock and split the rock apart.

4. COASTAL PROCESSES
• Swash- the process of the wave coming in.
• Backwash- the process of the wave going out.
• Constructive waves have strong swash and weak
backwash. They break about 6-9 times a minute, and
are long in relation to their height. They need calm
conditions. (BUILD UP THE COASTLINE)
• Destructive waves have a weak swash and strong
backwash. This erodes pebbles and shingle. High in
proportion to their length. -happen in Autumn or
Winter (ERODE THE COASTLINE)
• Fetch- the distance a wave has travelled.

5. WAVE CUT PLATFORMS
1. Weather weakens the top of the cliff.
2. The sea attacks the base of the cliff forming a wave-cut notch.
3. The notch increases in size causing the cliff to collapse.
4. The backwash carries the rubble towards the sea forming a
wave-cut platform.
5. The process repeats and the cliff continues to retreat.

6. • Cliff Recession-The process of a cliff
getting small and falling apart.
• Causes of Cliff Recession-
• Erosion- Hydraulic Action, Abrasion
• Geology- Soft rock, Resistant Rock
• Fetch- Destructive Waves, Constructive
Waves
• Impermeable rock- can’t absorb water
• Permeable rock- takes in water

7. CLIFF COLLAPSES ARE MASS MOVEMENTS
Mass Movement- the downslope movement of material
due to gravity.
Slides -
Material shifts
in a straight
line.
Slumps –
material shifts
with a rotation
Rockfalls-
material shifts
vertically

8. BAYS AND HEADLANDS

9. FORMATION OF A COVE
• When alternating bands of hard and soft
rock running parallel to the coast (e.g.
LULWORTH COVE IN DORSET)

10. EROSIONAL AND DEPOSITIONAL
PROCESSES CHANGING A LANDFORM
OVERTIME
• Caves occur when waves force their way into cracks in the cliff face.
The water contains sand and other materials that grind away at the
rock until the cracks become a cave. Hydraulic action is the
predominant process.
• If the cave is formed in a headland, it may eventually break through
to the other side forming an arch.
• The arch will gradually become bigger until it can no longer support
the top of the arch. When the arch collapses, it leaves the headland
on one side and a stack (a tall column of rock) on the other.
• The stack will be attacked at the base in the same way that a wave-
cut notch is formed. This weakens the structure and it will
eventually collapse to form a stump.
• One of the best examples in Britain is Old Harry Rocks, a stack
found off a headland in the Isle of Purbeck.

12. THINGS THAT AFFECT THE SIZE
AND ENERGY OF A WAVE:
– Length of time the wind is or has
been blowing
– Strength of the wind
– Fetch- distance of water over which
the wind has blown to produce a
wave.
– Other waves

13. LONGSHORE DRIFT
Longshore drift- material movement along a coastline. (takes material with it)
•Waves move towards the coast at an angle, as they break,
swash carries material up and along the beach at the same
angle. As the swash dies away, backwash and material fall at 90°
because of gravity. Material goes in a zig-zag pattern. The
prevailing wind is South Westerly and the backwash continues at
90°.
•Longshore drift is continuous and can take a lot of a beach.

14. PROCESSES OF TRANSPORTATION
Solution Minerals are dissolved in sea
water and carried in solution.
The load is not visible.
Suspension Small particles are carried in
water, eg silts and clays,
which can make the water
look cloudy.
Saltation Load is bounced along the
sea bed, eg small pieces of
shingle or large sand grains.
Traction Pebbles and larger sediment
are rolled along the sea bed.

15. DEPOSITION
When the sea loses energy, it drops the sand, rock
particles and pebbles it has been carrying. This is
called deposition. Deposition happens when the
swash is stronger than the backwash and is
associated with constructive waves.
Deposition is likely to occur when:
•waves enter an area of shallow water.
•When a wave loses energy
•waves enter a sheltered area, eg a cove or bay.
•there is little wind.
•there is a good supply of material.

16. COASTAL AND
DEPOSITIONAL LANDFORMS

17. BEACHES
Beaches are areas of sand, pebbles and shingle
that are formed by deposition produced by wave
processes. Beaches are by no means uniform and
contain a huge variety of sediment types and
sizes, and have many different shapes.
Gently sloping beaches are formed by strong
destructive waves that backwash more material
away from the beach that they swash up the
beach.
Steeply sloping beaches occur by constructive
waves that swash more material up the beach
than they backwash away, building up a steep
beach gradient.

18. Features Spits Tombolos Bars
What is it? a ridge of sand
and shingle
projecting from
the mainland into
the sea
a ridge of sand
and shingle
joining the
mainland to an
island
a ridge of sand
and shingle
which has joined
two headlands,
cutting off a bay
How does it
form?
when there is a
break in the
coastline and
drop in energy,
long-shore drift
deposited the
material and build
up spit
formed when spit
continue to grow
outwards
connecting the
mainland to the
offshore island
just like bridges
(a)form when a
spit grows the
whole way across
a bay
(b) a sandbank
develops
offshore, parallel
to the shore until
it joins the
mainland
Example Hurst Castle
Spit
Isle of Portland Slapton Sands

20. CASE STUDY : DORSET
• Durdle Door - cave, arch
• Lulworth Cove
• Chesil Beach- tombolo,
lagoon
• Swanage and Studland
bay – stack, stump

22. WHY SHOULD WE PROTECT
THE COAST

23. METHODS OF PRESERVING
THE COAST

24. ARE THE METHODS
SUSTAINABLE ?