AS Geography Coasts Case Studies

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Coastal Erosion

The Holderness Coast

The Holderness Coastline is 61km long – it stretches from Flamborough Head to Spurn Point. In some places, eg. Great Cowden, the rate of erosion has been over 10m per year in recent years, but the average rate of erosion at the Holderness is about 1.8m per year.

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Reasons

1.  Easily eroded rock type – the cliffs are mostly made of till (or ‘boulder clay’). Not only is till easily eroded through abrasion, but it’s also prone to slumping when wet.

2.  Narrow beaches – beaches slow the waves, reducing their erosive power. Narrow beaches protect the cliff less.  Beaches along the Holderness coast are narrow for two main reasons:

  • Flamborough Head stops sediment from the north replenishing the beaches along the Holderness. It’s also made of chalk, which dissolves when eroded rather than making sand for the beaches.
  • Coastal defences, eg. at Mappleton. This is a human cause of erosion.

3.  Powerful waves – the waves are powerful because of:

  • The long fetch (all the way from the Arctic Ocean).
  • The coast faces the dominant wind and wave direction (from north-east).
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Impacts

SOCIAL

  • Property prices along the coast have fallen sharply for those houses at risk from erosion.
  • Around 30 villages have been lost since Roman times.

ECONOMIC

  • Visitor numbers in Bridlington dropped by over 30% between 1998 and 2006 (though this could have also been due to other reasons).
  • Many caravan parks are at risk from erosion, eg. Seaside Caravan Park at Ulrome is losing an average of 10 pitches a year.
  • £2 million was spent at Mappleton in 1991 to protect the coast.
  • The Gas Terminal at Easington is at risk (it’s only 25m from the cliff edge). This terminal accounts for 25% of Britain’s gas supply.
  • 80,000m squared of good quality farmland is lost each year. This has a huge effect on farmers’ livelihoods.
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Impacts

ENVIRONMENTAL

  • Some SSSIs (Sites of Special Scientific Interest) are threatened – eg. The Lagoons near Easington are part of an SSSI. It has a colony of over 1% of the British breeding population of little terns. The Lagoons are separated from the sea by a narrow ***** of sand and shingle. Erosion of this would connect the lakes to the sea and ‘The Lagoons’ would be destroyed.
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Coastal Flooding

Tsunami in Southern Asia, 2004

The tsunami that devastated areas of Indonesia, Sri Lanka, Thailand and India on 26th December 2004 was caused by a submarine earthquake in the Indian Ocean. The earthquake is estimated to have measured 9.0 on the Richter scale, making it one of the strongest earthquakes ever recorded.

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Effected Areas

  • The epicentre of the earthquake was off the western coast of Sumatra in Indonesia.
  • Waves up to 30m high struck the Indonesian island of Sumatra within minutes of the earthquake.
  • The tsunami reached more than 2km inland at Trincomalee in the north east of Sri Lanka.
  • The tsunami travelled across the Bay of Bengal at speeds up to 800km per hour. The waves struck south eastern India just two hours after the earthquake.
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Impacts

SOCIAL

  • It was the deadliest tsunami ever recorded, with an estimated 230,000 people killed or missing.
  • It’s estimated that 1.7 million people were made homeless.
  • Many sources of fresh drinking water were polluted, either by sewage or by saltwater.
  • An estimated 400,000 lost their jobs in Sri Lanka alone.

ENVIRONMENTAL

  • 8 million litres of oil was released into the environment after 2 oil plants in Indonesia were destroyed. The oil caused wide spread pollution at sea and contamination of the soil, posing health risks to humans in the area.
  • Mangrove forests as far away as the East African coast were damaged by the force of the waves, or covered in layers of silt.
  • The high salt content of the floodwater destroyed the natural balance of many ecosystems, eg. the Karagan Lagoon in southern Sri Lanka.
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Impacts

ECONOMIC

  • Estimates of the cost of the initial damage caused by the tsunami are between $8 billion and $15 billion.
  • Fishing is a large part of the economy for many of the areas hit by the tsunami. Boats, nets and other equipment were destroyed or lost, severely affecting the livelihood of fishermen.
  • Salinisation (increase in salt content) of land has severely reduced soil fertility. Crop production will be lower for several years to come.
  • Tourism is important to the economy of many of the countries affected. 25% of hotels in southern Thailand were closed for at least 6 months because of damage and the number of foreign visitors to the island of Phuket dropped 80% in 2005 as the areas was perceived to be less safe.
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Human Activity

Human activity increased the impact of the flooding

  • Mangrove forests protected parts of the Sri Lankan coast by absorbing wave energy. Pressure for tourist development and the creation of intensive prawn fisheries has led to the destruction of mangrove forests in other areas around the Indian Ocean. It’s estimated that Thailand has lost up to half of its mangrove forests since 1975. The lack of protection meant that waves could reach further inland and the flooding was much worse than in areas protected by mangroves.
  • It’s thought that the healthy coral reefs surrounding the Maldives acted as a breakwater (reducing the power of the tsunami waves) and prevented the complete destruction of the low-lying islands. Illegal coral mining and the use of dynamite in explosive ‘blast fishing’ has destroyed many offshore coral reefs in the Indian Ocean. This reduced the level of natural protection from the waves.
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Coastal Management - Hard Engineering

The Holderness Coast

The Holderness coast is the fastest eroding coastline in Europe. A total of 11.4km of the 61km coastline is currently protected by hard engineering:

  • Bridlington is protected by a 4.7km long sea wall as well as timber groynes.
  • There’s a concrete sea wall, timber groynes and riprap at Hornsea that protect the village.
  • Gabions just south of Hornsea help protect Hornsea Caravan Park.
  • Two rock groynes and a 500m long revetment were built at Mappleton in 1991. They cost £2 million and were built to protect the village and the B1242 coastal road.
  • There are groynes and a sea wall at Withernsea. Some riprap was also placed in front of the wall after it was damaged in severe storms in 1992.
  • Easington Gas Terminal is protected by a revetment.
  • The eastern side of Spurn Head is protected by groynes and riprap.
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Schemes

The schemes are locally successful but cause problems down-drift.

  • The groynes trap sediment, increasing the width of beaches. This protects the local area but increases erosion of the cliffs down-drift (as the material eroded from the beaches there isn’t replenished), eg. the Mappleton scheme has caused increased erosion of the cliffs south of Mappleton, for example in Aldbrough. Cowden Farm, just south of Mapleton, is now at risk of falling into the sea.
  • The sediment produced from the erosion of the Holderness coastline is normally washed into the Humber Estuary (where it helps to form tidal mudflats) and down the Lincolnshire coast. Reduction in this sediment increases the risk of flooding along the Humber Estuary, and increases erosion along the Lincolnshire coast.
  • The protection of local areas is leading to the formation of bays between areas. As bays develop the wave pressure on headlands will increase and eventually the cost of maintaining the sea defences may become too highAll these problems make the existing schemes unsustainable.
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Possible Schemes

Possible schemes all pave problems:

  • The Shoreline Management Plan (SMP) for the Holderness for the next 50 years recommends ‘holding the line’ at some settlement (eg. at Bridlington, Withernsea, Hornsea, Mappleton and Easington Gas Terminal) and ‘doing nothing’ along more unpopulated stretches. However, this is unpopular with owners of land and property along these stretches where nothing is being done.
  • Coastal realignment of businesses has been suggested, eg. relocating caravan parks further inland. This would be a more sustainable scheme as it would allow the coast to be eroded as normal without endangering businesses. However, there are issues surrounding how much businesses will be compensated by for relocating. Also, relocating isn’t always possible, eg. farmland can’t be ‘relocated’, and there may be no land for sale to relocate buildings to.
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Possible Schemes

  • A sea wall has been proposed to better protect Easington Gas Terminal. This would cost £4.5 million. The problem is that it would reduce sediment flow to the south, increasing erosion at the village of Easington (with a population of 700 people). A longer sea wall could be built that would protect the village as well as the Gas Terminal, but that would cost £7 million.
  • Offshore reefs made from concrete-filled tyres have been proposed to protect the coastline. They act like breakwaters. Similar reefs have been built in the USA and have reduced erosion. Some people think that the reefs will harm the environment though (although there’s currently no evidence for this).
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Coastal Management - Soft Engineering

Blackwater Estuary

Soft Engineering has been used along Blackwater Estuary. Blackwater Estuary is part of the Essex coastline. Land in the estuary is being eroded at a rate of 0.3-1m per year. In some exposed areas (eg. Cobmarsh Island) the erosion rate is 2m per year. The area is also at risk of flooding as sea level is rising and the South of England is sinking relative to the sea.

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Soft Engineering

There are some hard engineering schemes in the estuary, but these are becoming too expensive to maintain, so soft engineering approaches are now being implemented:

  • Coastal realignment was implemented at Tollesbury Fleet in 1995. An existing sea wall was breached and 21 hectares of farmland were flooded to encourage a marshland to form. A new lower sea wall was built further back on higher ground to protect from flooding.
  • Beaches have been nourished along the estuary, eg. at Mersea Island.
  • Marsh establishment has been carried out by planting stakes and brushwood on water line to encourage sediment to build up, eg. at Ray Creek.
  • In 1991 an existing sea wall was lowered and breached flooding 0.8 hectares of land at Northey Island.
  • In 1995 a sea wall was breached and 40 hectares of farmland at Orplands were flooded as part of coastal realignment.
  • Coastal realignment has been carried out at Bradwell-on-Sea by breaching an old sea wall.
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Sustainability

The schemes are more sustainable than hard engineering schemes:

  • The schemes are more sustainable in the long term, eg. to repair the sea wall at Orplands would have cost more than £600,000 (and it would only last for 20 years). The 40 hecares of farmland flooded was valued at around £600,000, but the marshland created would defend the coast for longer as its self-repairing.
  • The schemes have created more marshland, which provides a larger habitat for wildlife.
  • However, some areas haven’t changed to marshland (e.g parts of the Orpland site are still bare mud, which is easily eroded). Also, grazing land has been lost.
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Comments

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The image of Lulworth that many people have is of a picture postcard fishing village nestled in the Purbeck hills. Old cottages and a thatched pub, with lobster pots in the Cove. Unspoilt by modern development and a place where time has stood still. This is also the image sold to the general public by tourist offices and hotels.

However, this village has not stood still. It was made popular by writers such as Hardy, and grew in popularity in the late 19th and early 20th centuries. Tourism developed, with both the car and caravan parks opening in the 1920s as a result of public demand.

Lulworth has managed to avoid the urbanisation that can be seen further east on the Dorset coast. Poole and Bournemouth used to be small villages on the heath, but have now merged into an urban conurbation. To understand why Lulworth still exists as it is, we must look at the history of the area.

Lulworth is part of a large estate, and the land area has been managed as a single entity for 1000 years. (For 400 years as two estates, and the last 350 years by a single family.) The Estate must generate its own income and therefore aims to move with the times and progress without detracting from the beauty of Lulworth. Lulworth has also been relatively isolated in terms of transport. The railway stops short of Lulworth and early visitors would have made the trip by paddle steamer from Swanage or Weymouth.

As the Lulworth area is largely unspoilt, in the last 50 years (since planning regulations were introduced), it has been covered by several designations to help protect the area and to conserve it for future generations.

Lulworth comes under:

  • World Heritage Coast
  • Area of Outstanding Natural Beauty
  • Site of Special Scientific Interest (Geology and Wildlife)
  • Conservation Area
  • Ancient Monuments
  • A Council of Europe Diploma Holding Area

Does such a small place as Lulworth really require management and conservation action? Its beauty, wildlife, good walking and a tendency to be mentioned in almost every geography text book means that Lulworth receives around 750,000 visitors every year. It is especially popular as an escape point from London and the South Eat as it is only two hours away by car.

The volumes of people visiting the area bring with them many positive aspects:

  • The local community and employment are sustained directly and indirectly through tourism revenue
  • Funds generated by tourism provide capital for investment at the Cove and for general Estate improvements
  • The Estate employs approximately 70 staff, of which about 30 are involved directly with tourism and leisure

However, so many visitors are not always desirable. There are many problems associated with tourism:

  • A large car park for vehicles
  • A caravan site for accommodation
  • Unsuitable or unsightly tourist shops
  • Erosion of footpaths
  • Pollution, rubbish and sewage
  • Erosion of Geological SSSI

The conflicts are clear. Lulworth provides a classic case study of countryside management needs with three main areas to consider:

  • The local community, economy and farming
  • The visitors
  • Conservation

To ensure that the character and amenity of Lulworth are retained, a sustainable balance between the three areas must be found. This may appear easy in theory, but it is not so easy in practice.

If we look at the major players which influence the area, we see that they are many and varied:

  • The Lulworth Estate
  • Dorset County Council
  • Purbeck District Council
  • The Ministry of Defence
  • The Council of Europe and other bodies influencing designations
  • The local community

The aims and requirements of each of the groups will vary according to their priorities, be it income, conservation or working policies.

So, what is actually happening on the ground towards better management in the Lulworth area?

In the 1990s the West Purbeck Warden wrote an assessment report on the management needs of the Lulworth area. The report contains information on:

  • Statutory designations
  • The physical environment
  • History and archaeology
  • Land use
  • Terrestrial ecosystem
  • Marine environment
  • Recreation and tourism
  • Visitor surveys

This creates a suggested basis for a broad management plan to tackle issues in connection with one another, and at the root of the problems. There is no sense in reviewing symptoms if the underlying cause remains the same.

The Heritage Coast plan cannot exist in isolation. It has to take into consideration the needs of all the aforementioned groups. Bringing everyone together at grass roots level and changing attitudes so that all groups are working towards a commend end is a lengthy process.

Management: Work done

Rangers

  • Footpath Management:
    • Rerouting
    • Reseeding
    • Geo-jute on loose areas
    • Signing
    • Hard pathway (around Stair Hole)
    • Stile counters
    • Step building
    • Improve access
  • Helpers in the effort to gain renewal of a Council of Europe Diploma
  • Interpretation
    • Boards
    • Leaflets
    • Guided walks and talks
    • Educational Displays
  • Screening
    • Looking at eyesore sites

The estate

  • Many of the above done with the involvement and cooperation of the Estate
  • There are a number of public rights of way (in effect created and consented to by the Estate) on the coastal area, but public access to other areas of the coast has been provided by the Estate for more than 100 years
  • The Estate have opened a number of permissive rights of way from the coast to the area inland and have also opened the Castle grounds which helps to reduce impact on the Cove area
  • An historic landscape survey produced
  • Involvement of tenant farmers in the Countryside Stewardship Scheme

Wessex Water

Have recently completed a scheme to screen all sewage before discharge.

The Purbeck Heritage Committee

This committee was created to examine problems on the Heritage Coast as a whole. It was formed in 1993 and brings together representatives from conservation, landowners, tourism and local government to co-ordinate the activities of the many bodies involved in managing, conserving and enjoying Purbeck.

The committee has recently published the Strategy for the Purbeck Heritage Area.

Management: Future issues

There are many issues to tackle in the future. A few of the issues named in reports and strategies that concern the Lulworth area are:

Council of Europe recommendations

  • Integrate footpaths into the surrounding area
  • Screen or re site the car park
  • Screen or camouflage the caravan park
  • Develop database on wildlife
  • Reduce water pollution
  • Make efforts to release pressure of tourism in the area

Heritage Committee Strategy

  • Examine unregulated parking and curb congestion
  • Look at erosion of cliff tops
  • Improve signing for pedestrians
  • Provide interpretation
  • Examine buildings of temporary/inappropriate construction

Estate improvements

  • Heritage Centre, Restaurant, Coast Guards, Landscaping and Building improvements
  • Continuing long term scheme to screen the caravan park

The most important factor in successful management is the commitment and working relationship between the major groups involved. A recent improvement in involvement and cooperation means that everyone concerned is hopeful that future management will be successful and progressive.

Geology

The rocks at the seaward side are the oldest, and now lie vertical to the earth after an earthquake that happened 30 million years ago when Africa collided with Europe.

The creases in the rock here are known as the ‘Lulworth Crumple'

The rocks

Portland Stone - 150 million years old

  • Made up of shells laid down in a calm shallow sea
  • Strong and hard rock

Purbeck Beds - 147 million years old

  • Made up of clays, shales, mudstones and limestone containing many fossils and crushed shell beds
  • Laid down in different climate and environmental conditions in salty, brackish and freshwater lagoons

Wealden Beds - 140 million years old

  • Made up of sand, marl, clay and grit
  • Laid down in a series of earth movements
  • The sediments were deposited from a large river into a large freshwater lake
  • Soft and easily eroded
  • Contains water fleas, snails and Lignite coal

Greensand - 125 million years old

  • Made up of layers of sandstone deposited in a shallow sea with some urchin and bivalves
  • Stained green by an iron and potassium mineral glauconite
  • Well drained, soft rock and easily eroded

Chalk - 97 million years old

  • Made up of trillions of minute marine organisms deposited slowly in a clear shallow sea
  • Flints were once areas of sponge beds
  • Considered a soft rock but is resistant to erosion by the sea

Stair Hole

An embryo cove with various breaches through the rock, the main breach is at west gap after an arch collapsed, other geological features includes; arches, caves and blow holes as well as stumps, which will eventually collapse to form a larger cove.

The Lulworth Crumple is most evident in the Purbeck beds.

Lulworth Cove

A circular eroded cove after a break in the Portland and Purbeck rocks allowing the softer greensand, Wealden and chalk to be eroded away with the two Portland stone rock headlands protecting the ‘harbour from stormy seas.

The origins of Lulworth cove started during the last ice age where a melt water river found a weak point in the rocks allowing the sea and the river to exploit it. The diffraction of the waves in the cove matches that of the circular beach.

Man O' War/St Oswald's Bay

This is the remains of a former cove, similar to Lulworth Cove, which has been opened up by the sea. The ‘w' shaped cliff and foreshore headland is the result of the stumps acting as break water protecting the beach from the sea.

Durdle Door

A natural arch of Portland limestone was once part of a long line of stone but has now collapsed leaving several stumps off of Bat's Head to cow rock. The stumps from Durdle Door are the bull, the blind cow, the cow and the calf. At a closer look at Durdle Door there are several holes which were once trees.

Coastal geomorphology

  • Lulworth Cove is a World Heritage site and part of the Heritage Coastline
  • It is one of the best examples in Europe of the stages of erosion on a concordant coastline
  • The coast is very young due to recent ice ages and resulting sea level change. The processes have been operating over the last 8000 years
  • A Concordant Coastline
  • Bays more elongated and ovoid in shape
  • Headlands do not stick out as much
  • Rock strata parallel to sea
  • One rock type facing the sea, therefore rocks erode at the same rate.
  • A Discordant Coastline
  • Bays deep
  • Headlands stick out
  • Different rates of erosion, alternating hard and soft rock

Rock types

  • Portland Limestone - 150 million years (hardest)
  • Purbeck Limestone - 147 million years
  • Wealden Beds of sand and clay - 140 million years (softest)
  • Greensand (sandstone) - 125 million years
  • Chalk - 97 million years

Due to major movements of the earth's crust, streams have turned the rocks on their side and subsequent erosion, sea, weather and man have shaped the coast.

At each of the stages recommended the students to an annotated field sketch.

First stage - Stair Hole

  • An embryo cove - Represents sea's first breach of the Portland Limestone
  • Rocks behind Portland
  • Purbeck Limestone - Thinner bedding so more weaknesses for processes to attack
  • Wealden Clay - Susceptible to erosional processes other than the sea, roatoinal slumping and weathering
  • Processes utilise weaknesses in rocks - joints and bedding planes
  • Processes: hydraulic action, attrition, abrasion and corrosion

Second stage - Lulworth Cove

  • What happens as the processes happening at Stair Hole occur over a longer period of time
  • At the cove the sea and the river breached the Portland. After the last ice age a swollen river broke through the chalk and limestone. The sea has carved the core out
  • Portland limestone forms the barrier entrance to the cove as its more resistant. The sea hits here first and waves are detracted
  • Behind the limestone the sea has carved out the other rocks, as they are less resistant to erosion
  • Order of rocks for the sea inland - Portland, Purbeck, Wealden, Greensand and Chalk
  • Other features - dry valley, steam and cut through the chalk
  • Evidence of erosion:
    • Wealden: slumping of the clay and the sand as beach material
    • Chalk: pebbles on the beach and clue as to when cliffs last fell with level of vegetation on the cliffs
    • Purbeck: can see the blocks that have broken off on the beach

Third stage - St. Oswalds Bay

  • This is what occurs when two coves join up. Still evidence of two coves
  • Limestone blocks in water. Evidence that this is the most resistant as it is left
  • Sea is trying to straighten the coast again
  • Clay is a thinner band here, squashed by earth movements

Fourth stage - Durdle Door

  • Here you can see how the bay has been straightened - example of dynamic equilibrium
  • Sea attacked rock - once all limestone will go to being all chalk
  • See erosion of the chalk with arches and stacks
  • Caves due to faulting
  • Dry valleys
  • Durdle Door
  • Shingle Beach. Sorting and storm beaches and berms. Wave energy dissipated on shingle beaches
  • Limestone blocks in the water - trace to Isle of Portland

Site overview

Lulworth Cove, Stair Hole and Durdle Door: Coastal processes and Tourism

Coastal processes: Key points

  • What features can be found at these locations and what reasons have been suggested for their formation?
  • In what succession have these processes happened?
  • How do coastal processes affect these structures?

Project/hypothesis ideas

  • What will be the next evolutionary step at each of these key sites
  • Too many visitors to a honeypot site can do as much damage as natural erosion
  • How do you think global warming might affect this coast in the future
  • The sea is not the only factor responsible for the landforms of the Dorset coast

Tips/pitfalls

  • If possible visit the site during stormy weather conditions to see the power of the sea
  • Take spare camera batteries and film

Data collection

  • Photographs
  • Field sketches
  • Environmental quality survey
  • Use maps
  • Beach profiles/beach processes data

Review - Statistical

  • Analysis of beach processes data

Review - Presentation

  • Profiles
  • Bi-polar surveys

Tourism: Key points

  • Has tourism been of benefit to Lulworth Cove as a settlement?
  • How is tourism managed in Lulworth Cove?
  • Lulworth Cove and Durdle Door are tourist honey pot sites that require sensitive forms of management. What are these?
  • How can physical environments be managed to preserve their characteristics yet meet people's need for recreation?

Project/hypothesis ideas

  • What are the impacts of management schemes?
  • How much should be charged for parking and how should it be used?
  • How far have visitors travelled and how long is their stay?

Tips/pitfalls

  • If possible visit the site during different times of the day or year to see the difference in visitor numbers

Data Collection

  • Questionnaires
  • Photographs
  • Use maps

Review - Presentation

  • Isopleth maps
  • Bi-polar

Curriculum links

Links to Key Stage 3 Specifications

Geographical enquiry and skills
1 Undertaking geographical enquiry:
1b - Suggest appropriate sequences of investigation (gathering views and factual evidence about a local issue)
1c - Collect, record and present evidence
1d - Analyse and evaluate evidence and draw and justify conclusions
1e - Appreciate how people's values and attitudes affect issues

2 Developing geographical skills:
2a - To use an extended geographical vocabulary
2b - To select appropriate fieldwork techniques and instruments

Knowledge and understanding of places
3c - Describe physical and human features that give rise to the distinctive character of places
3d - Explain how and why changes happen in places, and the issues that arise from these changes

Knowledge and understanding of patterns and processes
4a - Describe and explain patterns of physical and human features
4b - Identify, describe and explain physical and human processes and their impact on places and environments

Breadth of study
6c - Geomorphological processes6f - Population6h - Economic activity6j - Environmental issues and management7c - Carry out fieldwork investigations outside the classroom

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