Landscapes in the UK: Coasts1. Wave types and characteristics

What causes waves?

Wind blowing over the sea. Friction with the surface of the water leads to the formation of waves.

The amount of energy in a wave depends on:

1. Wind speed

2. How long the wind has been blowing.

3. The fetch. What is this?

The distance the wind blows across the water.

What happens when the wave reaches the coast?

As the water gets shallower, the circular motion of the wave becomes more elliptical as friction with the sea bed slows the wave down. This causes the wave to break.

What is swash?

Water rushing up the beach.

What is backwash?

Water flowing back towards the sea due to gravity.

Landscapes in the UK: Coasts1. Wave types and characteristics

Constructive wave:

• Strong swash

• Weak backwash

• Build up the beach by depositing material on it

• Long wavelength, low frequency.

• Formed by storms a long way away.

• Form a gently sloping beach

Destructive wave:

• Weak swash

• Strong backwash

• Therefore they erode (destroy) the beach by carrying material from it back out to sea.

• Short wavelength, high frequency

• Form a steep beach.

Landscapes in the UK: Coasts2. Processes: Weathering

You need to know a variety of coastal processes – these are the things that go on along the bach to change the landscape in some way.

A) Weathering processes. What is weathering?

The wearing way of rock in situ (in its original place). It is mostly caused by weather factors such as rainfall and changes intemperature.

1. Mechanical weathering:

Weathering processes that cause physical disintegration or break up of exposed rock without any change in the chemical composition of the rock, for instance freeze thaw.

What is freeze thaw weathering?

When water gets into cracks in the rock, if the temperature falls below zero, the water will freeze, expand by 9% and make the cracks bigger. In the day the water thaws again and the process repeats itself.

2. Chemical weathering:

The decomposition (or rotting) of rock caused by a chemical change within that rock; sea water can cause chemical weathering of cliffs.

An example is carbonation where rainwater absorbs CO2 from the atmosphere making it slightly acidic. When this comes into contact with rocks such as limestone or chalk there is a chemical reaction and they dissolve.

Landscapes in the UK: Coasts2. Processes: Mass movement

B) Mass Movement. What is this?

The downslope movement of weathered material due to gravity.

1. Sliding:

Occurs after periods of heavy rain when loose surface material becomes saturated and the extra weight causes the material to become unstable and move rapidly downhill, sometimes in an almost fluid state. 2. Slumping:

Rapid mass movement which involves a whole segment of the cliff moving down-slope along a saturated shear-plane or line of weakness. 3. Rock falls:

Fragments of rock break away from the cliff face, often due to freeze thaw weathering and fall to the base of the cliff.

Landscapes in the UK: Coasts2. Processes: Erosion

C) Erosion. What is this?

The wearing away and removal of rock, in this case by the sea.

1. Hydraulic power:

The process by which breaking waves compress pockets of air in cracks in a cliff. The pressure may cause the crack to widen, breaking off rock.

2. Abrasion:

The wearing away of cliffs by sediment flung by breaking waves.

3. Attrition

Erosion caused when rocks and boulders transported by waves bump into each other and break up into smaller pieces.

Common mistakes:

Pupils refer to freeze thaw as erosion or hydraulic action as weathering. Make sure you know the difference between weathering and erosion and which processes are examples of each.

Do not talk about attrition when talking about how landforms are created. Hydraulic power and abrasion are the most important processes to talk about.

Landscapes in the UK: Coasts2. Processes: Transportation - Longshore drift

D) Transportation: What is this?

The carrying of material, in this case by the sea. There are lots of ways the sea does this. The one you have to know is…

1. Longshore drift:

The zigzag movement of sediment along a shore caused by waves going up the beach at an oblique angle(swash) due to the prevailing wind and returning at right angles(backwash) due to gravity. This results in the gradual movement of beach materials along the coast.

Try drawing a diagram!

Does it look like this one?

Landscapes in the UK: Coasts2. Processes: Deposition

E) Deposition – what is this?

Occurs when material being transported by the sea is dropped due to the sea losing energy. You need to know the reasons why this happens:

• The sea loses energy when water slows down. This might happen in a sheltered area such as a bay or behind a spit.

• Water also slows down at a river estuary (where the river meets the sea). Here, water flowing down the river is cancelled out by waves coming from the sea which slows the water down, leading to the material being carries to be deposited.

• Deposition may also occur when the sea is overloaded with sediment so it doesn’t have the energy to carry it all. This might occur along the coast from a rapidly eroding headland.

• Deposition may also occur where a structure such as a groyne has been built to trap the sediment being carried by the sea.

Landscapes in the UK: Coasts3. Characteristics and formation of landforms caused by coastal erosion:

You need to be able to describe the characteristics of and explain the formation of the following coastal landforms:

1. Headlands and Bays

2. Cliffs and wave-cut platforms

3. Caves, arches and stacks.

In order to explain the formation of a landform you need to do two things:

1. Give a full sequence – what was needed for the landform to start to be created, then what happened, then what happened, then always say that this repeated over time leaving the landform in the landscape.

2. Name and explain the processes involved.

For all the erosional landforms you need to explain the role of hydraulic power and abrasion in their formation. (DON’T MENTION ATTRITION!!)

You should also make sure you can draw a sequence of diagrams showing their formation and recognise photographs of the landforms and what they look like on an OS map.

What is a headland?

A rocky coastal promontory made of rock that is resistant to erosion (a bit of land jutting out into the sea)

What is a bay?

An indent in the coastline between two headlands, created where there is less resistant rock.

Explain the formation of Headlands and Bays. (4marks)In order for headlands and bays to form, the coastline needs to have bands of more and less resistant rock.The less resistant rocks are eroded more quickly through processes of hydraulic power (the force of the waves against the coast) and abrasion (where material in the water is thrown against the coast, wearing it away.) This creates an indent in the coast line.This continues over a long period of time leaving headlands of hard rock sticking out from the coast and indents (bays where the softer rock has been eroded away.

Headland (made of harder rock)

Bay (made of softer rock)

(When labelling with arrows. Make sure the arrow touches the feature you are labelling!)

What do headlands and bays look like on an OS map?

Headlands (areas of harder rock.)

Bays (areas of softer rock)

What is a cliff?

A steep high rock face formed by weathering and erosion along the coastline.

What is a wave-cut platform?

A rocky, level shelf at or around sea level representing the base of old, retreated cliffs.

Explain the formation of a cliff/wave cut platform. (4marks)Cliffs and wavecut platforms form where waves attack a coastline between the high and low water mark through processes of erosion such as hydraulic power (the force of the water against the cliff) and abrasion (where material in the water is flung against the cliff wearing it away.This creates a wavecut notch in the coastline.The land above the wave-cut notch is unsupported (and may also be being attached by weathering processes.) and therefore will collapse due to gravity. This causes a steep rock face known as a cliff to form.This repeats over time causing the cliff face to retreat back, leaving a flat, wave cut platform stretching in front of it.

This arrow is no good – it is pointing to the sea, not the cliff. Make sure your arrows touch the thing you are talking about!!

What do cliffs and wavecut platforms look like on an OS map?

Cliff

Wave cut platform

Caves arches and stacks:

What is a cave?

A large hole in the cliff caused by waves forcing their way into cracks in the cliff face.

What is an arch?

A wave-eroded passage through a small headland. This begins as a cave formed in the headland, which is gradually widened and deepened until it cuts through.

What is a stack?

An isolated pillar of rock left when the top of an arch has collapsed. Over time further erosion reduces the stack to a smaller, lower stump.

Explain the formation of a stack. (4marks)Stacks form where the sea attacks a headland through processes of hydraulic power (the force of the water against the coast) and abrasion (where material in the water is flung against the coast, wearing it away.)These processes of erosion first erode a cave in a headland as waves force their way into cracks.Over time caves erode back to back and are widened and deepened until they cut right through the headland.Weathering processes will attack the roof of the arch until it collapses due to gravity leaving an isolated pillar of rock in the sea called a stack.

Stack

Arch

Cave

Stacks

Stack

Landscapes in the UK: Coasts4. Characteristics and formation of landforms caused by deposition:

You need to be able to describe the characteristics of and explain the formation of the following coastal landforms:

1. Beaches

2. Sand dunes

3. Spits

4. Bars

In order to explain the formation of a landform you need to do two things:

1. Give a full sequence – what was needed for the landform to start to be created, then what happened, then what happened, then always say that this repeated over time leaving the landform in the landscape.

2. Name and explain the processes involved.

You should also make sure you can draw a sequence of diagrams showing their formation and recognise photographs of the landforms and what they look like on an OS map.

Beaches:

What is a beach?

The zone of deposited material that extends from the low water line to the limit of storm waves. The beach or shore can be divided in the foreshore and the backshore.

Beaches may be made of sand or shingle (pebbles)

They may have ridges on them called berms.

Explain the formation of beaches. (4marks)Beaches form where there is a build up of material. Deposition is dominant and outweighs any erosion therefore they will form where constructive waves are more dominant.There may be a clear source of sediment near by e.g. cliffs made of soft, easily eroded material.In sheltered areas such as bays, over long periods of time constructive waves with a strong swash and weak backwash will deposit more and more material forming a beach.

This beach is made of shingle (pebbles because it has dots on.

This beach is made of sand. Both beaches are shown by their beige colour

Sand dunes.

What is a sand dune?

A coastal sand hill above the high tide mark, shaped by wind action, covered with grasses and shrubs.

More vegetation grows as more organic matter is added to the sand over time.

Explain the formation of sand dunes. (4marks)Sand dunes start to form where there is an object or obstacle on the beach which traps sand being blown by the wind.Over time the sand builds up and marram grass starts to grow which stabilises the dune. These baby dunes are called embryo dunes.As the grasses die, organic matter is added to the sand forming a better soil so more plants start to grow so until the dunes at the back of the beach have fertile soil and a range of plants growing on them.Wind can form depressions in the sand in which water can collect. These are called dune slacks.

Embryo dunes at the back of a beach

Marram grass

There is no symbol for sand dunes – they will just be marked on the map

Spit

What is a spit?

A depositional landform formed when a finger of sediment (sand or shingle) extends from the shore out to sea, often at a river mouth. It usually has a curved end because of opposing winds and currents.

Explain the formation of a spit. (4marks)Waves move material up the beach at an angle due to the prevailing wind and it comes back don the beach at right angles to the coast due to gravity. In this way material is moved sideways along the coast through the process of longshore drift.Where the coastline changes direction such as at a river estuary a reduction in the speed of the water leads to a reduction in energy and deposition of material. (at a river estuary the water from the river and waves from the sea cancel each other out slowing down the flow of water.) In this way a finger of land is built up extending away from the coast. This builds up over time and may have a curved tip due to changes in wind direction.In the sheltered area behind the spit, further deposition may occur leading to the formation of a salt marsh.

Spit made of sand.

Salt marsh forming in the sheltered area behind the spit.

River estuary –where the river meets the sea.

This spit is made of shingle (pebbles) shown by the dots on the sand

The tip of the spit is curved due to changing wind direction

A salt marsh has formed behind the spit due to slow moving water leading to deposition. Marsh is shown by the brown colour and tufts of grass.

A Bar.

What is a bar?

Where a spit grows across a bay, a bay bar can eventually enclose the bay to create a lagoon. Bars can also form offshore due to the action of breaking waves.

Explain the formation of a bar. (4marks)Waves move material up the beach at an angle due to the prevailing wind and it comes back don the beach at right angles to the coast due to gravity. In this way material is moved sideways along the coast through the process of longshore drift.Where the coastline changes at a bay which is a more sheltered area, a reduction in the speed of the water leads to a reduction in energy and deposition of material. Over time, a finger of land extends across the bay as a spit which may join with the headland at the other side of the bay to form a bar. The water trapped behind the bar is known as a lagoon.

Bar

Lagoon

Bar

Lagoon

Landscapes in the UK: Coasts5. An example of a section of coastline in the UK to identify it major landforms of erosion and deposition

Major landforms of erosion along this coastline are found in the north at Flamborough Head (headland) where stacks and caves can be found.

There is a bay to the south of Flamborough Head at Bridlington.

The eroded material from this coastline is then transported south by longshore drift until it eventually is deposited on the spit know as Spurn Head. This occurs where the coastline changes direction at the Humber estuary at Easington.

The idea is that you understand how landforms along a coastline are linked together and that erosion at one place along the coastline (e.g. at Flamborough Head) will provide the material which will later be deposited at Spurn Head.

Landscapes in the UK: CoastsThe costs and benefits of different coastal management strategies.

Key idea: different management strategies can be used to protect the coastline from the effects of physical processes.

What is hard engineering?

The use of concrete and large artificial structures by civil engineers to defend land against natural erosion processes.

Name examples.

Sea walls, rock armour, gabions and groynes

What are the advantages of hard engineering:

• If successful, hard engineering stops erosion in that particular place, therefore protecting the land behind.

• You can also refer to advantages of individual methods.

What are the disadvantages of hard engineering?

• Expensive to build and have high maintenance coasts.

• Can interfere with coastal processes elsewhere e.g. by stopping erosion, beaches further down the coast will not be supplied with enough sand.

• Look unnatural and some people argue they spoil the surroundings.

• You can also refer to disadvantages of individual methods.

Landscapes in the UK: CoastsThe costs and benefits of different coastal management strategies.

Key idea: different management strategies can be used to protect the coastline from the effects of physical processes.

What is soft engineering?

Managing erosion by working with natural processes to help restore beaches and coastal ecosystems.

Examples of soft engineering:

Beach nourishment and reprofiling and dune regeneration

Advantages of soft engineering

• Work with coastal processes to protect the coast.

• Tend to be cheaper than hard engineering

• Considered to be the more sustainable option.

• The preferred option by the government today.

Disadvantages:

• May require more maintenance

• May be unpopular with those with property along the coastline as they don’t actually stop erosion.

SeaSea Wall

Hard engineering:

Concrete barrier against the sea placed at the foot of cliffs or at the top of a beach. May have a curved face to reflect the waves back to sea.

Advantages:• Effecting at stopping the sea eroding the

coast.• May have other uses such as a promenade

(walkway) along the coast/

Disadvantages:• Looks unnatural and many people say it spoils

the look of the coast.• Very expensive and high maintenance costs.

Cost: £5,000-£10,0000 per m

Groynes

Hard engineering:

Wooden or rock structures built extending out to sea from the coast. They trap sediment being moved along by longshore drift. This bigger beach then absorbs the wave energy and protects the coastline behind from erosion.

Advantages:• Create a wider beach which protects the coast

behind from erosion.• Wider beach attracts tourists• Not too expensive

Disadvantages:• Beaches further down the coast may be

starved of sediment which could lead to increased erosion further down the beach.

• They look unnatural.• The can get damaged fairly quickly and require

maintenance.

Cost: £150,000 each

Rock armour

Hard engineering:

Piles of large boulders dumped at the foot of a cliff. The waves break on the rocks instead of the coastline behind and therefore lose the energy that they had to erode. Barges usually carry the rocks to the coast.

Advantages:• Effecting at stopping the sea eroding the

coast.• Relatively cheap and easy to maintain• Often used for fishing.

Disadvantages:• Looks unnatural and many people say it spoils

the look of the coast.• Rocks can be expensive to transport as they

may come from abroad

Cost: £200,000 per 100m

Gabions

Hard engineering:

Wire cages filled with rocks that can be built up to support a cliff or provide a buffer against the sea.

Advantages:• Effective at stopping the sea eroding the

coast.• May have other uses such as a promenade

(walkway) along the coast/

Disadvantages:• Looks unnatural and many people say it spoils

the look of the coast.• Very expensive and high maintenance costs.

Cost: £50,000 per 100m

Beach Nourishment

Soft engineering:

The addition of sand or shingle to an existing beach to make it higher or wider. The extra sediment provides a barrier which protects the coast from erosion. The sediment is usually got from offshore so that it blends in with the beach material which is already there.

Advantages:• Relatively cheap and easy to maintain.• Blends in with existing beach – looks natural.• Increases tourism because of the better beach.

Disadvantages:• Needs constant maintenance as the material can be washed out to

sea or along the coastline through longshore drift.

Cost: £500,000 per 100m

Beach reprofiling is when bulldozers are used to shape the new material into a nice beach.

Dune regeneration

Soft engineering:

Sand dunes (grassy areas at the back of the beach) can protect the coast behind them from being eroded however they are often damaged by people walking on them. Marram grass is planted in areas to restabilise the dunes (hold the sand together) to prevent damage. Fences are used to stop people walking on the area.

Advantages:• Maintains a natural coastal environment which

is popular with people and also provides important habitats for wildlife.

• Relatively cheap.

Disadvantages:• Time consuming as it takes a while for the

grasses to establish themselves.• People dot like being kept out of areas of the

beach.• Can be damaged by storms.

Cost: £400-£2000 per 100m

Landscapes in the UK: CoastsManaging coasts through managed retreat and coastal realignment

There is a third way to manage the coastline which is managed retreat. What is this?

Allowing cliff erosion to occur as nature taking its course: erosion in some areas, deposition in others. It may involve settingback or realigning the shoreline and allowing the sea to flood areas that were previously protected by embankments and seawalls. This has happened at Wallersea on the Thames Estuary.

Benefits:

• May reduce coastal erosion further down the coast as more sediment can move along the coast through longshore drift.

• Often cheaper than maintaining hard engineering structures although some compensation may have to be paid for land lost.

• Creates new intertidal habitats for wildlife. E.g. at Wallersea, 38 species of birds have been seen at the new mudflats.

• With rising sea levels and increasing costs of defending the coast, this offers a sustainable long term solution. It is better to plan this that o cope with it when areas are flooded unintentionally.

Costs (problems)

• Relocation of people to new homes leads to he break up of coastal communities and unhappiness for the people affected.

• In the short term, this cold cost a lot of money as compensation has to be paid.

• Large areas of agricultural land are lost. Habitats of some coastal birds such as bitterns might be affected.

Landscapes in the UK: CoastsAn example of coastal management: Lyme Regis

Where is Lyme Regis?

A small coastal town on the south coast of England, a popular tourist destination.

Why does the coastline need managing?

• The town is built on unstable cliffs and is the fastest eroding coastline in Europe.

• There are powerful waves coming from the south west.

• Many properties have been destroyed or damaged. The sea walls have been breached many times.

How has the coastline been managed?

The Lyme Regis Environmental Improvement Scheme was set up by West Dorset District Council in the early 1990s with the aim of providing long term coastal protection.

Works were completed in 2015.

Phase 1 completed 1995: New Sea wall constructed to the east of the town. And emergency project completed to restabilise the unstable cliffs. Nails were used to hold the cliffs together and drainage was improved to stop the cliffs becoming saturated and slumping.

Phase 2 2005-2007: Improvements to sea wall: new sea walls, creation of a wide beach to absorb energy of the waves, extension of rock armour at Cobb.

Phase 3: It was decided to leave the area to the west to managed retreat because the costs of defending the area outweighed the benefits.

Phase 4: constructing second sea wall in front of the other one.

Landscapes in the UK: CoastsAn example of coastal management: Lyme RegisPositive effects of the scheme:

• The new beaches have increased visitor numbers and local businesses near the beach are thriving. This has led to jobs and the local economy has seen a boost.

• The new defences are holding up to storms so are working.

• The harbour is better protected to fisherman’s livelihood and boats are better protected.

Negative effects of the new scheme:

• Increased visitor numbers have increased traffic congestion and litter.

• Some people say the natural landscape has been spoilt.

• Neighbouring stretches of coastline have seen an increase in erosion.

• Stabilising cliffs has meant that crumbling cliffs no longer reveal fossils.

The following conflicts have been created by the schemes:

• Some local people are unhappy with the increase in tourists and the damage they do to the environment through litter and traffic congestion.

• Environmentalists have clashed with supporters of the scheme and the local council as they say the natural environment has been damaged.

• Fossil hunters have been unhappy as an important location for research and fossils has been lost through the stabilisation of the cliffs.

• Older members of the community have been critical of the scheme where younger members of the community have benefited from opportunities brought about by increasing tourists.