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Coastal processes this one

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  • Give out target sheets. Get each pupil to work out how many marks they need to get to 40 out of 60 and how many to get a C.
  • Bawdsey Suffolk – measure out. Picture of flags Picture of flags http://www.youtube.com/watch?v=gqc7wXdkOp4 17 meters in one year.
  • Coastal Kung fu

Transcript

  • 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
    CA
    SDME
    Your target in to get at least 40 / 60 marks in the Controlled Assessment. 24 available for this project.
  • 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. Hydraulic Action
    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.
  • 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/geographyalltheway_photos/sets/72157621775281810/with/319733211/
    Look at the landforms.
    What factors affect the rate of erosion?
  • 20. http://www.bgs.ac.uk/opengeoscience/googlemaps625/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. An example of headlands and bays on the Dorset coastline…
    chalk
    clay
    Swanage Bay
    limestone
  • 26.
  • 27. The formation of cliffs and wave cut platforms
    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.
  • 28.
  • 29. Wave cut notch - Auchmithie
  • 30. Destructive coastlines
  • 31. Destructive Waves
    BACKwash is stronger than the Swash
    Cause EROSION
    Draw the annotated Destructive wave diagram on p 89
  • 32. Exam Question: Name features X and Y. Explain how they formed. Use an annotated diagram in your answer. (5)
    X
    Y
  • 33. The formation of cliffs and wave cut platforms
    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.
  • 34. Development of
    Wave Cut Platforms
  • 35. High Tide
    Low Tide
    1
    Corrasion occurs between high and low tide- rocks are hurled at the base of the cliff.
  • 36. Cliff is undercut, leaving it unstable.
    Wave Cut Notch
    Eroded material available to take part in corrasion.
    2
  • 37. Cliff retreats
    Wave Cut Notch
    The process of corrasion will continue…
    Wave Cut Platform- corrasion can not occur below low tide.
    3
  • 38. Cliff retreats
    Wave Cut Platform.
    4
  • 39. Task
    Using the terms below, produce a four picture storyboard explaining the process that produces a wave cut platform.
    Corrasion
    High Tide
    Low Tide
    Wave Cut Notch
    Cliff
    Retreat
    Wave cut platform
  • 40. Headland erosion
  • 41. Caves, arches, stacks and stumps
  • 42. 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?
  • 43. Blowholes
    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.
  • 44. This huge blowhole is the Gaylet Pot near Auchmithie. The tractor on the skyline is at the top of the cliffs.
  • 45. Durdle Door
    Arches
    These are formed by the wearing away of narrow headlands often by two back-to-back cave systems joining.
    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.
  • 46. Here a cave and arch are forming on the same headland at Auchmithie
  • 47.
  • 48. 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.
  • 49. The ‘Deil’s 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.
  • 50. We can now imagine how the headland at Durdle Door might be evolving
    Durdle Door in the past………
  • 51. As it is at present ………
    DurdleDoor
  • 52. Durdle Door
    sometime in the future?
  • 53.
  • 54.
  • 55.
  • 56. Old Harry Rocks in Dorset which show many of the features of headland erosion
  • 57.
  • 58. Pop-up headland..
    http://www.flickr.com/photos/sacherfire/217113480/
  • 59. 1
    You need your template. This will represent a chalk headland.
  • 60. 2
    Using a blue crayon- shade the outside horizontal strips- these represent the sea.
  • 61. 3
    Using a green crayon- shade the middle horizontal strip- this represents the top of the headland- exposed to weathering.
  • 62. Just above the horizontal blue lines- shade a grey line- make sure it reaches the top of the wave-cut notch. This represents wave action between high and low tide.
    4
  • 63. 5
    Don’t cut off your stump!
    Carefully cut out all the black areas on the template- with the exception of the wave-cut notch.
  • 64. 6
    It should look like this...
  • 65. 7
    Using a ruler, carefully fold the horizontal lines.
  • 66. 8
    Like this...
  • 67. 9
    Glue along the two blue horizontal strips- on the reverse!
  • 68. 10
    Position the green strip over the centre of your book. Gently glue down the blue horizontal strip- the one with the stump.- Practice your positioning first.
  • 69. 11
    Carefully practice folding the model... are the folds the right way?
  • 70. 12
    Finally, glue the final blue strip down. Practice the positioning first...
  • 71. 13
    Gently close your book...
  • 72. 14
    Magic...
  • 73. 4
    5
    1
    3
    2
    6
    Arty shot...
  • 74. 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.
  • 75. Write a voice over for the next clip. Your script should explain how the feature formed
  • 76.
  • 77. Destructive Coastlines
  • 78.
  • 79. Why are maps and grid references vital?
  • 80. Why Grid References?
  • 81. All about Grid References
  • 82. For the exam
    Have to be happy with 4 and 6 figure grid references
  • 83. Contructive Coastlines
    1. Processes of Transportation
    2. Features of Coastal Deposition :
    Beaches and Sand Dune Systems
    Spits
    Bars and Tombolos
    VV ‘05
  • 84. Constructive waves
    Diagram on page 89
  • 85. 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
    Swash
    Backwash
  • 86. This movement of sediment along the coastline is called..
    Longshore Drift
    Direction of movement
    swash
    Backwash is always at right angles to the beach
  • 87.
  • 88. Groynes are 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……
  • 89. ……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
  • 90. Beaches develop where the supply of sedimentexceeds 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.
  • 91. 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
  • 92. Sand beaches have a more gentle profile. This is the result of a number of factors…
    Sand is smoother than shingle so there is less friction to prevent the return of beach materials to the sea
    Wet sand compacts so water doesn’t drain through it. This means that backwash, and the material it is carrying, is able to return to the sea.
  • 93. As on-shore winds blow across dry beach sand, it carries material inland to form sand dune systems
    But that’s a story for another day!
  • 94. 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.
  • 95. Spurn Head at the mouth of the Humber estuary is a fine example of a spit.
  • 96. Local currents and changes in wind direction may curve the end of the spit landwards creating a hooked tip.
    wind
    Such a feature is known as arecurved spit
    The presence of the estuary discharging river water into the sea prevents the spit from developing into a bar.
  • 97. If a spit joins one part of the mainland to another it is called a bar.
  • 98. For example, there is a bar at Slapton Sands in Devon.
  • 99. 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.
  • 100. Chesil Beach viewed from the Isle of Portland
  • 101. How people use coastal landforms
  • 102. With thanks to:
    Val Vannet,
    Dan Raven-Ellison, and
    Tony Cassidy