1.Welcome to GCSE Geography

2. Name Mr Rogers Geography June 2012 Exam Coasts and Rivers Hazards Economic Geography 3. Rivers and Coasts 32% of final Mark Final exam June 2011 and Controlled Assessment 4. Economic Geography 16% of final Mark Final exam June 2011 5. Settlement and Population 25% of final Mark Sustainable Decision Making Exam Jan 2012 6. Hazards 16% of final Mark Final exam June 2011 7. Where are you now? 0 240 C - 144 Your target in to get at least 40 / 60 marks in the Controlled Assessment. 24 available for this project. CA SDME 8. Help! drogers@priory.portsmouth.sch.uk www.facebook.com/classroomgeography @priorygeography www.classroomgeography.blogspot.com Workshop Wednesday 9. Homework Due Wednesday 14th September Produce a factfile of a place that has been eroded by the coast Email to drogers@priory.portsmouth.sch.uk 10. Starter: How did this feature form? (4) 11. Marine Erosion Processes VV 05 12. The force of waves hitting a cliff (or sea wall) compresses water and air into cracks and joints. This can be equivalent to 30,000kg per square metre. This increase in pressure may lead to cracks widening and pieces of rock breaking off. Hydraulic Action 13. Corrasion (abrasion) Rock fragments may be picked up by waves and thrown against the rock face of cliffs by subsequent waves. The effectiveness of the corrasion depends on the strength of the wave, the nature of its load and the resistance of the rock in the cliff face. Corrasion is most effective at the base of cliffs 14. Attrition Currents and tidal movements cause the fragments to be swirled around and to grind against each other. This type of erosion produces pebble beaches. 15. Corrosion Salts and acids in sea water can react with rocks , slowly dissolving them away. . 16. Why does erosion matter? Video 17. Create four Kung Fu actions to represent each coastal erosion process 18. How have coastal processes shaped this landform? (4 marks) 19. http://www.flickr.com/photos/geographyal ltheway_photos/sets/72157621775281810 /with/319733211/ Look at the landforms. What factors affect the rate of erosion? 20. http://www.bgs.ac.uk/opengeoscience/go oglemaps625/default625.htm Google mash up 21. Rates of erosion depend on many factors: Waves strength, frequency, height Weather frequency of storm conditions Geology of the coastline : type of rock degree of resistance stratification stability 22. Coastlines of Erosion 1. Headlands and bays 2. Cliffs and wave cut platforms 3. Headland erosion and the formation of caves, blowholes, arches, stacks and stumps 23. Headlands and bays These are most likely to be found in areas where alternating resistant and less resistant rock meets the coast at right angles Erosion erodes the softer rocks more quickly forming bays Headlands are formed of rocks which are more resistant to erosion 24. Softer rock Harder rock Harder rock 25. chalk clay limestone Swanage Bay An example of headlands and bays on the Dorset coastline 26. The waves attack the base of the cliff through the processes of abrasion, corrosion, hydraulic action and attrition. Over time the cliff will be undercut and a wave-cut notch is formed. Eventually the cliff becomes unstable and collapses. Further cliff retreat will form a wave-cut platform. The formation of cliffs and wave cut platforms 27. Wave cut notch - Auchmithie 28. Destructive coastlines 29. Destructive Waves BACKwash is stronger than the Swash Cause EROSION Draw the annotated Destructive wave diagram on p 89 30. Exam Question: Name features X and Y. Explain how they formed. Use an annotated diagram in your answer. (5) X Y 31. The waves attack the base of the cliff through the processes of abrasion, corrosion, hydraulic action and attrition. Over time the cliff will be undercut and a wave-cut notch is formed. Eventually the cliff becomes unstable and collapses. Further cliff retreat will form a wave-cut platform. The formation of cliffs and wave cut platforms 32. 1 High Tide Low Tide Corrasion occurs between high and low tide- rocks are hurled at the base of the cliff. 33. 2 Wave Cut Notch Eroded material available to take part in corrasion. Cliff is undercut, leaving it unstable. 34. 3 Cliff retreats Wave Cut Platform- corrasion can not occur below low tide. Wave Cut Notch The process of corrasion will continue 35. 4 Cliff retreats Wave Cut Platform. 36. Using the terms below, produce a four picture storyboard explaining the process that produces a wave cut platform. High Tide Low Tide Wave Cut Notch Corrasion Retreat Wave cut platform Cliff 37. Headland erosion 38. Caves, arches, stacks and stumps 39. Caves Caves usually develop from widening and deepening of notches where there are weaknesses in the cliff face This large cave at Arbroath is fault guided. Can you see the fault? 40. Erosive waves may blast their way vertically through lines of weakness in the roofs of caves. This produces a blowhole on the cliff top. In stormy conditions sea spray may spout from blowholes. Blowholes 41. This huge blowhole is the Gaylet Pot near Auchmithie. The tractor on the skyline is at the top of the cliffs. 42. Arches These are formed by the wearing away of narrow headlands often by two back-to-back cave systems joining. Durdle Door The waves continue to erode at the foot of the arch widening it. Eventually the roof of the arch can no longer be supported and it will collapse. 43. Here a cave and arch are forming on the same headland at Auchmithie 44. Stacks and stumps Stacks often represent the seaward remnant of a collapsed arch. These tall, isolated pillars of rock such as The Pinnacles on the Dorset coast, are reduced by further wave action to stumps. 45. The Deils Heid stack at Arbroath is interesting because sea level has fallen since it was formed. There is very little erosion around its base so it is unlikely to become a stump for a very long time. 46. We can now imagine how the headland at Durdle Door might be evolving Durdle Door in the past 47. Durdle Door As it is at present 48. Durdle Door sometime in the future? 49. Old Harry Rocks in Dorset which show many of the features of headland erosion 50. http://www.flickr.com/photos/sacherfire/217113480/ 51. 1 You need your template. This will represent a chalk headland. 52. 2 53. 3 Using a green crayon- shade the middle horizontal strip- this represents the top of the headland- exposed to weathering. 54. 4 55. 5 Carefully cut out all the black areas on the template- with the exception of the wave- cut notch. 56. 6 It should look like this... 57. 7 58. 8 59. 9 60. 10 61. 11 62. 12 63. 13 64. 14 65. 1 2 3 4 5 6 66. About the template... You could draw your own template or print this slide and use for the model. The template should be A5 to fit into across a A4 exercise book- of course you could supersize the model. 67. Write a voice over for the next clip. Your script should explain how the feature formed 68. Destructive Coastlines Feature or Land use Grid Square Bay Headland Stack Cave Ancient use of land Tourism Car Park 82 80 Camping 69. Why are maps and grid references vital? 70. Why Grid References? 71. All about Grid References 72. For the exam Have to be happy with 4 and 6 figure grid references 73. Contructive Coastlines 1. Processes of Transportation 2. Features of Coastal Deposition : Beaches and Sand Dune Systems Spits Bars and Tombolos VV 05 74. Constructive waves Diagram on page 89 75. BackwashSwash Transportation of beach material Prevailing winds cause waves to approach the beach at an oblique angle Swash pushes beach material diagonally up the beach Gravity pulls the backwash at right angles back to the sea taking beach material with it Over time this moves material along the beach in a zig-zag fashion 76. This movement of sediment along the coastline is called.. Direction of movement swas h Backwash is always at right angles to the beach Longshore Drift 77. Groynesare sometimes built (as here on Aberbeen beach) to counteract the process of longshore drift and encourage the accumulation of sand. This can, however, result in depletion of sand and an increase in erosion further along the coastline 78. such as here at Barton-on-Sea on the south coast of England where the groynes at Christchurch have deprived this stretch of coastline of beach material. As a consequence, the beach at Barton has almost disappeared and the cliffs are eroding. To prevent further erosion, rock armour (rip rap ) has been placed on what is left of the beach 79. Beaches develop where the supply of sediment exceeds loss through backwash and longshore drift. Beaches are usually distinguished as either Shingle or Sand Shingle beaches are free draining so there is little backwash of material to sea. As a consequence, they are usually steeper. 80. Some features of a shingle beach .. largest material is furthest from the sea Successively lower berms Berms represent successive levels of beach material from storms and high tides 81. Sand beaches have a more gentle profile. This is the result of a number of factors Wet sand compacts so water doesnt drain through it. This means that backwash, and the material it is carrying, is able to return to the sea. Sand is smoother than shingle so there is less friction to prevent the return of beach materials to the sea 82. But thats a story for another As on-shore winds blow across dry beach sand, it carries material inland to form sand dune systems 83. Spits and Bars Where there is a change in the coastline e.g. a headland or an estuary mouth, longshore drift may continue to deposit sediments into the sea forming a spit. 84. Spurn Head at the mouth of the Humber estuary is a fine example of a spit. 85. Local currents and changes in wind direction may curve the end of the spit landwards creating a hooked tip. The presence of the estuary discharging river water into the sea prevents the spit from developing into a bar. Such a feature is known as a recurved spit wind 86. If a spit joins one part of the mainland to another it is called a bar. 87. For example, there is a bar at Slapton Sands in Devon. 88. Tombolo Where a spit joins the mainland to an island a tombolo may be created . The longest and best known tombolo in Britain is Chesil Beach. 89. Chesil Beach viewed from the Isle of Portland 90. How people use coastal landforms Landform How used Constructive or Destructive? Beachy Head Headland Tourism sight seeing Destructive 91. With thanks to: Val Vannet, Dan Raven-Ellison, and Tony Cassidy