Coasts revision booklet


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Booklet containing the essentials of revision on the topic of Coasts for GCSE Geography.

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Coasts revision booklet

  2. 2. Note: To use with the work you have in your exercise books and further revision Helpful links FRONTER there are all powerpoints as used in your lessons, with working links to theonline resources/ clips etc that have been used in lessons.On FRONTER there is a link to an electronic version of the OCR GCSE Geography textbookMiss Nash will be doing LOTS of revision with you in the run-up to your exams!There will be afterschool sessions held in the run up to exams if required. These will beinformal, and will involve things like practising exam technique, and help with generalrevision technique.
  3. 3. UNDERSTANDING THE QUESTIONWhen completing your GCSE Geography exam you must read the question carefully and answer itin the right way to make sure that you get as many marks as possible. Always use geographicalterms in your answers e.g. compass directions, use the scale of the map, give grid references.Here are some of the command words that you may be given:Annotate - add notes or labels to a map or diagram to explain what it shows.Compare - look for ways in which features or places are similar or different. e.g. a city in a LEDCcompared to a MEDCComplete - add to a map or graph to finish it off.Contrast - look for the differences between features or places. Often the question will ask you tocompare and contrast.Define - explain what something means e.g. hydraulic action.Describe - give details about what a map or diagram shows.Discuss - usually wants a long answer, describing and giving reasons for or explaining argumentsfor and against.Draw - a sketch map or diagram with labels to explain something.Explain or account for - give reasons for the location or appearance of something.Factors - reasons for the location of something such as a factory.Give your ( or somebody else’s) views- say what you or a particular group think aboutsomething , for example should limestone quarries be allowed in the Peak District.Identify - name, locate, recognise or select a particular feature or features, usually from a map,photo or diagram.Mark - put onto a map or diagram.Name, state, list - give accurate details or features.Study - look carefully at a map, photo, table, diagram etc. and say what it shows.With reference to /refer to examples you have studied - give specific details about your casestudies.With the help of/using the information provided - make sure you include examples from theinformation, including grid references if it is a map
  4. 4. Content Revised? CoastsHow weathering, erosion, transport and depositionoperate along constructive and destructive coastlines. The formation of landforms along a stretch of coastline,including cliffs, headland, cave, arch, stack, beach, spit -with appropriate examples. Human and physical reasons why the protection ofcoastlines is necessary.Different methods of coastline protection including thesustainability of each (examples include groyne, offshorebreakwater, sea wall, rip-rap, revetment, gabion, beachreplenishment and managed retreat). Case studies Named example CoastsA case study of one coastal area and its landforms.A case study of coastline management, including reasonsfor protection, measures taken, resulting effects andpossible conflicts.
  5. 5. Destructive or constructive?Consider the wave characteristics carefully and identify whether they are for destructive or constructivewaves.Destructive or Wave descriptionconstructive? weak backwash Short wavelength Steep waves Erodes the beach Long wavelength Low waves Strong swash Deposits materials and builds beaches Weak swash Strong backwash1. Read through each definition carefully and then choose the key term you think it is related to and write this into the attempt box. Definition Key term - Attempt Key term - Correct answerThis is the force of water hitting thecliff and squeezing air into the cracksin the rock. As the air is squeezed intothe cracks this puts pressure on thecracks and pieces of rock may breakoff.This is the process of rocks hittingeach other and breaking into smallerrocks when they are in the sea.This is the breakdown of rock in situcaused by the weather and animals.The force of the waves flings sandand pebbles against the cliffs. This isknown as a sandblasting effect.This is when animals such as rabbitsburrow into rocks or the roots ofplants widen cracks in rocks, puttingthem under pressure.This is a chemical reaction betweenthe sea water and the minerals in therocks. The sea water can slowlydissolve chalk and limestoneincreasing the size of cracks andjoints.These processes occur on the cliff-face and include mass movement andweathering. ENSURE YOU USE THESE PROCESSES AND EXPLAIN THEM WHEN YOU DESCRIBE OR EXPLAIN THE FORMATION OF A LANDFORM
  6. 6. 2. Read through the descriptions of the landforms and then complete the name and case study section of the table. Name Description of landform Case study example Extended stretch of beach material that projects out to the sea and is attached to the mainland at one end. An area of hard rock that extends out into the sea. An isolated pillar of rock that is separated from the headland by sea. DAWLISH WARREN STACKOLD HARRY ROCKS HEADLAND SPIT3. What coastal landforms can you indentify in the map extracts?
  7. 7. Landforms of erosion: Headlands and BaysHeadlands and bays form in area where there are alternating layers of hard rockand soft rocks.An example is Lulworth Cove in Dorset.At Lulworth Cove the outer layer of hard rock is limestone.The marine processes of hydraulic action, solution and abrasion have erodedthrough this hard rock to soft clays and sands behind it.As the clays and sands behind the limestone rock are less resistant to erosion, thesea erodes sideways and backwards forming a bay in the soft rock.The development of the bay was stopped when the sea had eroded back to thelayer of chalk, a hard rock which is resistant to erosion at the back of the bay.
  8. 8. REMEMBER LONGSHORE DRIFT CAN BE DESRCRIBED WITH A SIMPLE LABLLED DIAGRAM Deposition Landforms: Spit, Bars and TombolosA spit is a long narrow piece of land made of sand and shingle.This feature is joined to the land at one end and projects out into the sea or across ariver estuary at the other end.They are features of coastal deposition.Spits are formed when the sea moves particles of sand along the coast in a zig zagpattern.This is called long shore drift.The direction of long shore drift depends on the prevailing wind direction.When the coastline suddenly changes direction, usually at a headland, the sand andshingle continue to be moved along the coast out to sea building upwards andoutwards.The spit cannot grow right across to the other side of the river due to the rivercurrents.When the wind changes direction it causes the waves to change direction and thiscan lead to the end of the spit forming a curved end as the material gets blown in adifferent direction.Salt marsh often develops behind the spit from the deposition of fine silt and mud.An example of a spit is found at Dawlish Warren. The salt marsh behind the spit is anature reserve.If a spit grows across a bay (that has no river feeding it) and connects to the otherside it is called a bar (For example, Slapton Sands).If a spit joins the mainland to an offshore island it is called a tombolo (For example,Chesil Beach)
  9. 9. DEPOSITIONAL LANDFORMS: Spits, Bars and Tombolos
  10. 10. WHEN DESCRIBING THE FORMATION OF COASTAL LANDFORMS MAKE SURE YOU SEQUENCE THE FORMATION TO ACHIEVE THE HIGH GRADES Landforms of erosion: Headland erosionThe sea attacks a crack in the headland.Hydraulic action opens up the crack to form a cave.Over time, the sea will erode the cave until it goes through the headland to form anarch.The roof of the arch will collapse as there is nothing to support it. This is because ofconstant erosion and weathering.This leaves a pillar of rock which has broken away from the headland called a stack.Eventually, erosion will cause the stack to become a stump.An example is Old Harry in Dorset.
  11. 11. Landforms of erosion: Wave cut platformThe sea moves against the case of the cliff, abrasion and hydraulic action will slowlyerode the base of the cliff.The continuous erosion creates a wave-cut notch which begins at the high tide leveland ends at the low tide level.As the erosion continues the wave-cut notch gets bigger. Overtime the overhang ofrocks above the notch will fall into the sea due to it not being able to support its ownweight and the pull of gravity.The sea will then continue to attack the cliff and form another notch. In this way, thecliff will retreat (move backwards), becoming higher and steeper.The remains of the cliff rock, now below the sea at high tide, form a rocky, wave-cutplatform.
  12. 12. As the width of the wave-cut platform increases, the powers of the wave’sdecreases, as the waves have further to travel to reach the cliff. Soft coastlines Storm waves attack the base of the cliff. Cracks appear after dry weather. Rain soaks into cliff. The cliff becomes increasingly heavy and unstable.Mass movement occurs along slipping planes (lines of weakness in the rock).The cliff retreats (moves back) away from the sea.The Holbeck Hotel near Scarborough on the Holderness Coastline is a case study.
  13. 13. PROTECTING THE COASTAL AREA FROM NATURAL PROCESSESOver 4 billion people worldwide live in coastal areas, and they are also used heavily by industry.There is a growing threat of flooding due to sea-level rise, and erosion is increasing. As a result,many areas of coastline are now being protected. Coastal environments can provide uniquehabitats for wildlife, and so the challenge is to find ways of balancing the competing needs ofpeople, wildlife and the environment.Hold the line - maintain the existing coastline by building defencesAdvance the line - build new defences seaward of the existing defences
  14. 14. Managed realignment - allow the land to flood, and construct a new line of defences landward ofthe existing coastlineNo intervention - allow natural processes to shape the landThe map below shows the policies set out for sub-cell 11c.Hard Engeneering Method of Protection how does it work? Advantages DisadvantagesLipped sea wall Concrete Wall, curved under the side to deflect the power of the waves. Sea walls reflect rather than absorb wave energy Most effective means of preventing erosion Most expensive (up to £2.5 million / km)
  15. 15. Deflected waves often scour the base, undermining the wall (may eventually collapse)Large boulders on the beach - lesson the force of the waves by absorbing the wave energy within the gaps between the rocks Relatively Cheap Use natural materials / rocks Environmentally ugly Can be undermined and removed by waves due to washing away of sand and shingle beneath. Cages of boulders built into the cliff face - small rocks help to absorb the wave energy Effective where severe erosion and cheaper than sea walls Environmentally ugly (usually used in large numbersWooden or concrete structures break the force of the waves and trap beach material behind them Much cheaper than a sea wall Effective at breaking the force of the waves Less durable than a sea wall - may need replacing quicker Dont give total protection to base of cliff Environmentally ugly
  16. 16. Wooden or in some cases steel structures that stop longshore drift and build up / anchor the beach, protecting the base of a cliff Stops longshore drift encouraging the build up of the beach and effectively reducing erosion. Can increase erosion further down coast by stopping longshore drift and starving areas further down coast of sediment.A Tale of two villages- North East Norfolk LEARN A CASE STUDY OF A STREATCH OF COASTLINE THAT HAS BEEN MANAGED TO PROTECT IT FROM THE SEA AND AN AREA WHERE NO PROTECTION HAS BEEN PROVIDED TO PREVENT EROSIONSo what are the existing defences at Sea Palling? Following some of the worst storms in the history of the East Coast, a seawall was built at SeaPalling in 1953 to protect inland areas from flooding. It was to work alongside a wide sandy beach,which would absorb much of the power of the waves. However, by the 1990s, most of the beachhad been washed away so the seawall was being directly attacked by the waves during storms. Inorder to protect the seawall, 100,000 tonnes of boulders were places in front of the sea wall asrock armour. These were imported from Scandinavia. 1,000,000 cubic metres of sand were alsobrought in and dumped on the beach (beach replenishment) and four offshore reefs were builtparallel to the coast using huge granite boulders. The offshore reefs break the waves before theyreach the beach and the absorb their energy. Sediment is trapped on their landward side, creatinga wide beach which is then very effective in absorbing wave energy. The reefs worked so well thata second set was added later (to the south of Sea Palling). You can see the impact of the reefs inbuilding up the beach very clearly on an OS map or on an aerial photograph.
  17. 17. Happisburgh is a village with a population of about 1400 people in about 600 houses. This is oneof the fastest eroding coastlines in Europe, and thousands of tonnes of cliff material are washedaway every winter. It has been estimated that the Happisburgh cliffs are now retreating at a rate of10-15 metres every year. More than 30 buildings have been lost so far.In 1959, timber sea defences were constructed between Ostend and Cart Gap, including along thefront at Happisburgh. These were wooden revetments and groynes. They worked very well for anumber of years, but started failing in the 1980s due to lack of maintenance and repair. As aresult, the soft boulder clay cliffs took a severe battering from the waves. By 1989, North NorfolkDistrict Council identified the need for a major investment in new defences. Local government isresponsible for repairs and upkeep of sea defences, but any capital scheme such as renewal ofexisting defences or creation of new ones requires the acceptance, approval and funding ofcentral government.
  18. 18. In 2000, the Ministry of Agriculture, Farming and Fisheries (the body in charge of coastaldefence at the time) agreed to fund a study of the coast between Ostend and Cart Gap toinvestigate the coastal processes and if possible to develop a strategy to renew the defences. Areport and scheme was advertised in December 2001 recommending a 3-stage approach, startingwith the construction of a rock groyne at the south end of Beach Road. Objections werereceived from Professor Clayton and Lord of the Manor Eric Couzens. Despite 325 letters ofsupport, it was not possible to progress the scheme until these objections had been resolved.While the scheme was tied up in red tape at Whitehall, the sea continued its erosion at a rate far inexcess of any forecasts. The end result was that in December 2002 the scheme was withdrawnas it no longer met financial or technical criteria. The diagram below shows the outline of thescheme. North Norfolk District Council recognised that this was an emergency situation and they provided funding for 4000 tonnes of rock to be placed at the toe of the cliff as rock armour to give some short term protection. The Council emphasised that this was only intended as a temporary measure, and was not expected to withstand anything other than normal weather conditions.The 2006 SMP proposes that Happisburgh is no longer protected from erosion. This ispartly because the financial costs of protection are very high in relation to the value of property inthe village, and partly because the eroded material from the cliffs at Happisburgh forms the beachsediment that is so virtually needed to protect down drift locations from erosion.
  19. 19. Protecting the coastline: beach replishmentBeaches are a superb defence against storm waves and coastal erosion as they absorb thepower of the breaking waves. Having a wide beach can also protect from the threat of coastalflooding. Soft engineering is where beaches (or naturally formed materials) are used to control, reduce orredirect erosion processes. Soft engineering options are often less expensive than hardengineering options. They are usually also more long-term and sustainable, with less impact onthe environment, as they work with natural processes rather than against them. Beach replenishment (sometimes called beach nourishment) is an example of softengineering. Beach replenishment means that sand is dumped or pumped from elsewhere ontothe beach. Beach recycling is an attempt to even out the natural process of longshore drift. You could thinkof it as being the opposite of long shore drift - sand and shingle is moved from areas where it hasbuilt up from long shore drift and put back to its original position. It is most common for beachrecycling to happen after winter storms when large amounts of material have been moved bynatural processes. Beach reprofiling happens where bulldozers are used to move material up the beach. Afterstorms, the upper beach levels can get very low because materials have been removed in thewave backwash. Bulldozers are used to push material back up the beach to create gently slopingprofile. A gently sloping beach can absorb more wave energy than a steep beach, so it is a betternatural form of defence.Using the Natural environment to help prevent floodingManaged realignment (also known as managed retreat) means that the land is allowed to flooduntil it reaches a new line of defence inland. This defence may be natural (eg. a ridge of higherland) or built. This is shown in the animation below (wait until the Existing hard flood defencesstatement at the top of the list is highlighted in green for the start of the animation; the picturechanges to reflect the highlighted text on the right hand side of the image). Note that if there is nonatural ridge of earth, an earth bund may be constructed. This is a mound of earth that is built toseparate freshwater from saltwater.Managed retreat is often the policy where existing sea defences are allowed to fail. The sea floodsthe land behind the breached defences, but builds up its own natural defences such as mudflats,
  20. 20. marshes and beaches. This can only really work where population density is low and there is littleinfrastructure to protect. It is seen as being a much more sustainable way of the managing thecoastline than using hard engineering methods. It can also be much cheaper than hardengineering projects. Managed retreat is well suited to low-lying, saltmarsh environments, for example the estuaries ofEssex and Suffolk. Over time, the broad tidal marshes will help absorb and reduce wave energy,providing a low-cost coastal defence. They also enhance the ecosystem. A problem with this form of management is that good quality agricultural land may be lost.Settlements and property along the coastal strip may also be destroyed. Coastal blight occurswhere the price of properties in an area subject to managed retreat falls signficantly, meaning thathomeowners may find themselves in negative equity and unable to afford the cost of a moveinland. There have been reports of properties in the village of Happisburgh, North Norfolk beingvalued at just £1 due to the policy of managed retreat being proposed for the area. KEY WORDSSustainable management Management which meets the needs of the present while preserving the area for future generations.Integrated coastal zone management (ICZM) Management of the coastal zone to protect areas from over development and environmental damage. Was introduced by the EU in 1996.Coastal area/ zone The built-up area that stretches inland and the shallow seas and marshes that border the land. It is not just the point where the sea meets the land.Integrated management Management of the whole area/ system rather than just parts of it.Coastal flooding Storms and increased sea levels can lead to submergence of coastal areas.Salt marsh A natural habitat which lies between the sea and land. It acts as a natural defence to flooding.Managed retreat Restoring salt marshes so that the land can be used as a natural buffer from flooding, therefore, protecting the land behind it.Mediterranean A large area of water which borders Southern Europe and Northern Africa.UK England, Scotland, Wales and Northern Ireland make up this country.
  21. 21. Remember if there is anything you need help with you can come and speak to Miss Nash Or attend the revision club after schoolIf you would like additional help speak to Miss Nash and she will arrange a time to work with you. GOOD LUCK andremember to read the question and think what the command word is asking you to do- look at the number to marks they will tell you how many points you need to make.