AQA Geography A - The Coastal Zone

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The Coastal Zone
Shaping of the Coast
· Freeze thaw
Water fills a crack or joint in a rock
The water freezes and expands exerting pressure on the
The crack is widened as a result.
Repeated freeze-thaw action weakens the rock.
Eventually the rock splits and loose parts fall away.
· Exfoliation
Expansion during the day creates cracks parallel to the
Contraction during the night creates cracks perpendicular to
the surface.
As more and more cracks form, slabs break off and fall to
the ground.
· Solution
Rain water can contain dilute acids as a result of pollution.
This erodes certain rocks.
The rock is slowly dissolved by the acid.
· Carbonation
Rainwater reacts with CO2 in the air to create a dilute
carbonic acid.
Limestone and chalk are easily eroded by this as they are
mainly made of calcium carbonate.
They react with the acid to form calcium bicarbonate.
Mass movement
Rock fall
· Fragments of rock breakaway from the surface, often as a result of
freeze thaw weathering.
· Saturated soil and weak rock flow down a slope
Rotational slip
· Slump of saturated soil and weak rock along a curved surface
· Blocks of rock slide downhill
· If sand is found on top of a non permeable rock such as boulder clay
then slumping can occur.
· Rainwater filters through the sand but stops at the clay and forms a
film of water.
· This creates a slippery surface for the sand and so it slips off the clay.

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· They do most of the deposition
· They have a stronger swash than backwash which allows material to
be carried up the beach.
· Found in sheltered areas such as bays.
· They do most of the erosion
· Their backwash is stronger than the swash which allows loose
peoples and sand to be carried out to sea.
Processes of erosion
Hydraulic power
· Sheer force of the waves causes cavitation (trapped air in rocks)
which makes the rock break apart.…read more

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Calm seas and light winds.
· Where waves meet a bend in the coast line.
As a result of erosion
Headlands and bays
· Characteristics
Headlands are areas of land protruding out into the sea.
Bays are found between two headlands and often have a
beach in them due to their sheltered location.
· Formation
Where outcrops of hard and soft rock alternate bays and
headlands are formed.…read more

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· Characteristics
The temporary deposition of sand and shingle along the
Pebble beaches may have berms which are small ridges of
pebbles. The ridges usually show high, low and storm tides.
· Formation
Wherever waves lose power they deposit material that they
In bays beaches are formed because as the waves enter the
bay they diffract and spread out.
This makes them lose energy therefore making them
deposit material and become constructive waves.…read more

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They therefore expand and take up more room.
· This causes sea levels to rise.
The South East is sinking into the sea.
· During the ice age there was lots of ice in the north of the UK.
· This was very heavy and so weighed the North West down and lifted
the South East up.
· Although the ice has retreated the UK is still recovering and
subsequently the South East is being returned to its natural level.…read more

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Rocks with more joints and bedding planes are more susceptible to
erosion as the waves can exploit these weaknesses.
· Hardness of rock is also a factor: hard rocks, such as granite, are less
susceptible to erosion than a softer rock such as boulder clay, which
is loosely bound.…read more

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Provides useful structures for people interested in fishing.
Rock armour
· Costs
Expensive to transport because the stone is often from
abroad or somewhere else along the coast.
Look out of place as the stone often doesn't fit in with the
local geology.
Can be obtrusive.
· Benefits
Relatively cheap and easy to maintain.
Adds interest to the coast and easy access for fishermen.
Soft engineering
Beach nourishment
· Costs
Needs constant maintenance as the sand is washed away
easily.…read more

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Rich diversity of wildlife.
The resulting habitat and species that inhabit it
Cord grass
· Pioneer species
· Can grow in salt water
· Its roots help to trap mud and are long to stop it being swept away
by the sea.
· Helps improve soil fertility
Ringed plover
Common blue butterfly
Wold spider
· Reasons why.
Strategies to ensure the environment is conserved but also allow sustainable use of
the area.
Rock armour and beach nourishment to reinforce the spit.…read more


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