Coastal Landscapes
How do waves shape and change our coastline? -
- When wind blows over the sea, it creates waves. The size and energy of the wave depends on: the
fetch (how far it has travelled), the strength of the wind and how long the wind has been blowing for.
- There are two different types of waves – constructive and destructive. When a wave reaches the
shore, the water that rushes up the beach is the swash. The water that flows back down towards the
sea is known as backwash. The energy of these determine the type of wave.
- Destructive waves have a WEAK SWASH and STRONG BACKWASH. The strong backwash
removes sediment from the beach. The waves are steep and close together.
- Constructive waves have a STRONG SWASH and WEAK BACKWASH. The strong swash brings
sediment to build up the beach. The backwash is not strong enough to remove the sediment. The
waves are low and far apart.
How does weathering and mass movement contribute to our changing coastlines?
- Weathering is the natural processes that cause breakdown of rocks and minerals by chemical,
biological or physical agents. Exposed rocks on the coastline experience this.
- Freeze-thaw weathering occurs when rocks are porous (contains holes) or permeable (allows
water to pass through). Water enters into cracks in rocks, when temp drops water freezes and
expands causing the crack to widen. The ice melts and water makes its way deeper into cracks. This
process repeats until the rock splits entirely in half.
- Biological weathering is when roots enter smell cracks, growing and weakening the structure of
rocks until they break away.
- Chemical weathering – Rainwater and seawater can be a weak acid. If a coastline is made up of
rocks such as limestone or chalk, over time they can be dissolved by the acid in the water.
What are the erosional processes? -
- Erosion is the wearing away of rocks along a coastline. Destructive waves are responsible for this.
There are 4 types:
- Hydraulic action is the sheer power of water smashing against cliffs. Air becomes trapped in cracks
of rocks and causes them to break apart.
- Abrasion is when pebbles grind along a rock platform like sandpaper. Over time the rock becomes
smooth.
- Attrition is when rocks knock against each other and break apart becoming smaller and more
rounded.
- Solution is when sea water dissolves certain types of rocks, especially chalk and limestone cliffs.
What are other marine processes?
- Mass movement is the downhill movement of sediment due to gravity.
- Rockfall is when bits of rock known as scree fall of the cliff face, usually due to freeze-thaw
weathering.
- Mudflow is when saturated soil (soil filled with water) flows down a slope.
- Landslide is when large blocks of rock slide down a hill.
- Rotational slip is when saturated soil slumps down a curved surface.
- Transportation is the movement of material. Sediment is carried by waves along the coastline.
,- Solution is when minerals in rocks like chalk and limestone are dissolved in sea water and then
carried in solution. The load is not visible.
- Suspension is when small particles such as slits and clays are suspended in the flow of water.
- Saltation is when small pieces of shingle or large sand grains are bounced along the sea bed.
- Traction is when pebbles and larger material are rolled along the sea bed.
- The movement of material is known as longshore drift. Waves approach the coast at an angle
because of the direction of prevailing wind. The swash will carry the material towards the beach at
an angle. The backwash then flows back to the sea down the slope, repeating in a zigzag pattern.
- Deposition is when material is dropped due to the sea losing energy. It occurs on coastlines with
constructive waves. Factors leading to this are: Waves slowing down and losing energy, shallow
water, sheltered areas e.g. bays, little or no wind.
What landforms are found at the coast? -
- Coastlines where the geology alternates between strata (or bands) of hard rock and soft rock are
called discordant coastlines. A concordant coastline has the same type of rock along its length, and
tend to have fewer bays and headlands.
- Cliffs are shaped through a combination of erosion and weathering.
- Hard rocks such as chalk and limestone are more resistant than soft rocks, such as clay and
sandstone, so they erode more slowly. Hard rock creates steeper cliffs, soft rock creates gently
sloping cliffs.
- Wave cut platform – The sea attacks the base of a cliff between high and low tide marks, hydraulic
action and abrasion create a wave-cut notch. Over time this notch increases in size and the upper
cliff is unsupported while weathering weakens the upper cliff. They cause it to collapse, and a
wave-cut platform is the bedrock left behind as the cliff moves backwards. The backwash carries the
rubble towards the sea smoothening it. The process repeats and the cliff continues to retreat.
- Headlands are a stretch of coast made of rock that juts out into the sea made of harder rock and is
left because the surrounding softer rock has been eroded away. Bands of soft rock erode more
quickly. The areas next to headlands are called bays.
- Erosion creates caves, arches, stacks and stumps along a headland.
1. Cracks in the rock erode through abrasion.
2. Caves occur when waves force their way into cracks in a cliff face. The water contains sand and
other materials that grind away at the rock until the cracks become a cave. Hydraulic action and
abrasion are the predominant erosion processes.
3. If the cave is formed in a headland, it may eventually break through to the other side to form an
arch.
4. The arch will continue to be eroded (attrition) and 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.
5. 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.
- Beaches are made up of eroded material transported from elsewhere and deposited. Constructive
waves help to build beaches. Material (e.g. sand, shingle) depends on geology of area and wave
energy. A cross-section is called a beach profile. The smallest material is deposited near the water
and larger material is found nearer to cliffs at the back. Larger material is deposited in times of high
energy such as a storm. Most waves break near the shoreline so sediment near the water is more
effectively broken down by attrition. Waves need limited energy so beaches often form in sheltered
areas like bays where the water is shallow.
, - Shingle beaches are where strong swash waves are assisted by windy and stormy conditions to
throw large pieces of shingle further up. Smallest material at beach face and larger thrown to the
back. Steeper profiles than usually as wave percolates through shingle, making backwash too weak
to remove sediment.
- Sandy beaches have strong swash waves moving sandy material up. Backwash is weaker.
Coarsest/biggest sand found at wave limit further up the beach. Gently sloping profile as less
percolation of water and sand is lighter so can be removed more easily.
- Spits are created by deposition. They are an extended stretch of beach material that projects out to
sea and joined to the mainland at one end. Spits are formed where prevailing wind blows at an angle
to the coastline resulting in longshore drift. Longshore drift moves material in the direction of
prevailing wind, the angled swash brings material onshore whilst the backwash removes the material
in a straight line, perpendicular to the coastline. Spits occur when there is a change in the shape of
the landscape or there is a river mouth (longshore drift continues). Waves cannot get past a spit
creating a sheltered area where slit is deposited and mud flats or salt marshes are formed.
- A spit can grow across a bay and joins two headlands together, known as a bar. They can trap
shallow lakes known as lagoons. These don’t last forever and can fill with sediment.
- Sand dunes are accumulations of sand on a beach. Obstacles such as drift wood are dropped and
wind blows sand up the beach, which gets trapped on the obstacle. Colonising pioneer plants like
marram grass grow on the dune and stabilise it with their roots and trap more sand, creating an
‘embryo dune’. As plants die they add organic matter to the soil improving it for other plants to live in.
How are coasts managed through hard engineering? -
- Erosion can cause cliff collapse due to erosion therefore coasts need to be managed. Hard
engineering involves building artificial structures which try to control natural processes.
- Sea walls are concrete walls placed at the foot of cliffs to prevent erosion. They are curved to
reflect the energy back into the sea. They are effective at protecting the base of a cliff and usually
have promenades for people to walk along, however waves can break down and erode it due to their
power and they are expensive (approx. £2000 per metre).
- Rock armour is large boulders placed at the foot of a cliff that break the waves and absorb their
energy. It’s cheaper than a sea wall and easy to maintain, and can also be used for fishing. However
they look out of place to the local geology and are expensive to transport.
- Gabions are rocks held in mesh cages placed in areas affected by erosion. They are cheap
(approx. £100 per metre) and absorb wave energy, however not very strong and look unnatural.
- Groynes are wooden or rock structures built out at right angles into the sea. They build a beach
encouraging tourism and trap sediment being carried by longshore drift. However, by doing this it
starves the beach further down the coastline increasing rates of erosion. They also look unnatural.
How are coasts managed through soft engineering? -
- Soft engineering does not involve artificial structures and takes a more sustainable and natural
approach to managing the coast.
- Beach nourishment involves pumping sand onto an existing beach to build it up. It blends in with
the existing beach and larger beaches appeal to tourists, however it needs to be constantly replaced
and the sand has to be brought in from elsewhere.
- Reprofiling is redistributing sediment from the lower part of the beach to the upper part. It is cheap
and simple and reduces the energy of waves, however only works for low wave energy and needs to
be constantly repeated.
- Dune nourishment is when marram grass is planted on sand dunes to stabilise them and help to
trap sand to build them up. It is relatively cheap and maintains a natural looking coastline, however
can be damaged by storm waves and areas have to be zones off from the public which is unpopular.
How do waves shape and change our coastline? -
- When wind blows over the sea, it creates waves. The size and energy of the wave depends on: the
fetch (how far it has travelled), the strength of the wind and how long the wind has been blowing for.
- There are two different types of waves – constructive and destructive. When a wave reaches the
shore, the water that rushes up the beach is the swash. The water that flows back down towards the
sea is known as backwash. The energy of these determine the type of wave.
- Destructive waves have a WEAK SWASH and STRONG BACKWASH. The strong backwash
removes sediment from the beach. The waves are steep and close together.
- Constructive waves have a STRONG SWASH and WEAK BACKWASH. The strong swash brings
sediment to build up the beach. The backwash is not strong enough to remove the sediment. The
waves are low and far apart.
How does weathering and mass movement contribute to our changing coastlines?
- Weathering is the natural processes that cause breakdown of rocks and minerals by chemical,
biological or physical agents. Exposed rocks on the coastline experience this.
- Freeze-thaw weathering occurs when rocks are porous (contains holes) or permeable (allows
water to pass through). Water enters into cracks in rocks, when temp drops water freezes and
expands causing the crack to widen. The ice melts and water makes its way deeper into cracks. This
process repeats until the rock splits entirely in half.
- Biological weathering is when roots enter smell cracks, growing and weakening the structure of
rocks until they break away.
- Chemical weathering – Rainwater and seawater can be a weak acid. If a coastline is made up of
rocks such as limestone or chalk, over time they can be dissolved by the acid in the water.
What are the erosional processes? -
- Erosion is the wearing away of rocks along a coastline. Destructive waves are responsible for this.
There are 4 types:
- Hydraulic action is the sheer power of water smashing against cliffs. Air becomes trapped in cracks
of rocks and causes them to break apart.
- Abrasion is when pebbles grind along a rock platform like sandpaper. Over time the rock becomes
smooth.
- Attrition is when rocks knock against each other and break apart becoming smaller and more
rounded.
- Solution is when sea water dissolves certain types of rocks, especially chalk and limestone cliffs.
What are other marine processes?
- Mass movement is the downhill movement of sediment due to gravity.
- Rockfall is when bits of rock known as scree fall of the cliff face, usually due to freeze-thaw
weathering.
- Mudflow is when saturated soil (soil filled with water) flows down a slope.
- Landslide is when large blocks of rock slide down a hill.
- Rotational slip is when saturated soil slumps down a curved surface.
- Transportation is the movement of material. Sediment is carried by waves along the coastline.
,- Solution is when minerals in rocks like chalk and limestone are dissolved in sea water and then
carried in solution. The load is not visible.
- Suspension is when small particles such as slits and clays are suspended in the flow of water.
- Saltation is when small pieces of shingle or large sand grains are bounced along the sea bed.
- Traction is when pebbles and larger material are rolled along the sea bed.
- The movement of material is known as longshore drift. Waves approach the coast at an angle
because of the direction of prevailing wind. The swash will carry the material towards the beach at
an angle. The backwash then flows back to the sea down the slope, repeating in a zigzag pattern.
- Deposition is when material is dropped due to the sea losing energy. It occurs on coastlines with
constructive waves. Factors leading to this are: Waves slowing down and losing energy, shallow
water, sheltered areas e.g. bays, little or no wind.
What landforms are found at the coast? -
- Coastlines where the geology alternates between strata (or bands) of hard rock and soft rock are
called discordant coastlines. A concordant coastline has the same type of rock along its length, and
tend to have fewer bays and headlands.
- Cliffs are shaped through a combination of erosion and weathering.
- Hard rocks such as chalk and limestone are more resistant than soft rocks, such as clay and
sandstone, so they erode more slowly. Hard rock creates steeper cliffs, soft rock creates gently
sloping cliffs.
- Wave cut platform – The sea attacks the base of a cliff between high and low tide marks, hydraulic
action and abrasion create a wave-cut notch. Over time this notch increases in size and the upper
cliff is unsupported while weathering weakens the upper cliff. They cause it to collapse, and a
wave-cut platform is the bedrock left behind as the cliff moves backwards. The backwash carries the
rubble towards the sea smoothening it. The process repeats and the cliff continues to retreat.
- Headlands are a stretch of coast made of rock that juts out into the sea made of harder rock and is
left because the surrounding softer rock has been eroded away. Bands of soft rock erode more
quickly. The areas next to headlands are called bays.
- Erosion creates caves, arches, stacks and stumps along a headland.
1. Cracks in the rock erode through abrasion.
2. Caves occur when waves force their way into cracks in a cliff face. The water contains sand and
other materials that grind away at the rock until the cracks become a cave. Hydraulic action and
abrasion are the predominant erosion processes.
3. If the cave is formed in a headland, it may eventually break through to the other side to form an
arch.
4. The arch will continue to be eroded (attrition) and 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.
5. 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.
- Beaches are made up of eroded material transported from elsewhere and deposited. Constructive
waves help to build beaches. Material (e.g. sand, shingle) depends on geology of area and wave
energy. A cross-section is called a beach profile. The smallest material is deposited near the water
and larger material is found nearer to cliffs at the back. Larger material is deposited in times of high
energy such as a storm. Most waves break near the shoreline so sediment near the water is more
effectively broken down by attrition. Waves need limited energy so beaches often form in sheltered
areas like bays where the water is shallow.
, - Shingle beaches are where strong swash waves are assisted by windy and stormy conditions to
throw large pieces of shingle further up. Smallest material at beach face and larger thrown to the
back. Steeper profiles than usually as wave percolates through shingle, making backwash too weak
to remove sediment.
- Sandy beaches have strong swash waves moving sandy material up. Backwash is weaker.
Coarsest/biggest sand found at wave limit further up the beach. Gently sloping profile as less
percolation of water and sand is lighter so can be removed more easily.
- Spits are created by deposition. They are an extended stretch of beach material that projects out to
sea and joined to the mainland at one end. Spits are formed where prevailing wind blows at an angle
to the coastline resulting in longshore drift. Longshore drift moves material in the direction of
prevailing wind, the angled swash brings material onshore whilst the backwash removes the material
in a straight line, perpendicular to the coastline. Spits occur when there is a change in the shape of
the landscape or there is a river mouth (longshore drift continues). Waves cannot get past a spit
creating a sheltered area where slit is deposited and mud flats or salt marshes are formed.
- A spit can grow across a bay and joins two headlands together, known as a bar. They can trap
shallow lakes known as lagoons. These don’t last forever and can fill with sediment.
- Sand dunes are accumulations of sand on a beach. Obstacles such as drift wood are dropped and
wind blows sand up the beach, which gets trapped on the obstacle. Colonising pioneer plants like
marram grass grow on the dune and stabilise it with their roots and trap more sand, creating an
‘embryo dune’. As plants die they add organic matter to the soil improving it for other plants to live in.
How are coasts managed through hard engineering? -
- Erosion can cause cliff collapse due to erosion therefore coasts need to be managed. Hard
engineering involves building artificial structures which try to control natural processes.
- Sea walls are concrete walls placed at the foot of cliffs to prevent erosion. They are curved to
reflect the energy back into the sea. They are effective at protecting the base of a cliff and usually
have promenades for people to walk along, however waves can break down and erode it due to their
power and they are expensive (approx. £2000 per metre).
- Rock armour is large boulders placed at the foot of a cliff that break the waves and absorb their
energy. It’s cheaper than a sea wall and easy to maintain, and can also be used for fishing. However
they look out of place to the local geology and are expensive to transport.
- Gabions are rocks held in mesh cages placed in areas affected by erosion. They are cheap
(approx. £100 per metre) and absorb wave energy, however not very strong and look unnatural.
- Groynes are wooden or rock structures built out at right angles into the sea. They build a beach
encouraging tourism and trap sediment being carried by longshore drift. However, by doing this it
starves the beach further down the coastline increasing rates of erosion. They also look unnatural.
How are coasts managed through soft engineering? -
- Soft engineering does not involve artificial structures and takes a more sustainable and natural
approach to managing the coast.
- Beach nourishment involves pumping sand onto an existing beach to build it up. It blends in with
the existing beach and larger beaches appeal to tourists, however it needs to be constantly replaced
and the sand has to be brought in from elsewhere.
- Reprofiling is redistributing sediment from the lower part of the beach to the upper part. It is cheap
and simple and reduces the energy of waves, however only works for low wave energy and needs to
be constantly repeated.
- Dune nourishment is when marram grass is planted on sand dunes to stabilise them and help to
trap sand to build them up. It is relatively cheap and maintains a natural looking coastline, however
can be damaged by storm waves and areas have to be zones off from the public which is unpopular.
