Lithosphere Coasts


Published on

Published in: Education
1 Like
No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Lithosphere Coasts

  1. 1. Coastal Features Higher Geography Lithosphere
  2. 2. ‘ A recent estimate of the coastline of England and wales is 2750 miles and it is very rare to find the same kind of coastal scenery for more than 10 to 15 miles together’ J.A. Sheers, The Coastline of England and Wales, 1969
  3. 3. Introduction <ul><li>For its size, Scotland has a very long coastline. </li></ul>If you straightened out all of the bends and twists, you would have coastline about 10, 000km long. Top Geography Fact!
  4. 4. Map <ul><li>The west coast of Scotland has more inlets and sea lochs than the east and tends to be more rugged. </li></ul>
  5. 5. Waves
  6. 6. Waves <ul><li>Waves are caused by the wind dragging on the surface of the water. The length of water the wind blows over is called its fetch . </li></ul>
  7. 7. When waves reach the coast (1) <ul><li>Out at sea, the waves roll. In a gale they can be over 30m high! </li></ul>
  8. 8. The sea kayak is 4m long
  9. 9. The sea kayak is 4m long
  10. 10. The sea kayak is 4m long
  11. 11. <ul><li>They break in shallow water. The water that rushes up the sand is called the swash . </li></ul>When waves reach the coast (2)
  12. 12. When waves reach the coast (3) <ul><li>The water rolling back into the sea is called the backwash . </li></ul>Backwash
  13. 16. The waves at work Waves have energy. That means they can work. They work non-stop, night and day shaping the coastline.
  14. 17. Erosion Waves erode in the same way as rivers
  15. 18. Human Activity <ul><li>The increase in pressure resulting from building on cliff tops and the removal of beach material which may otherwise have protected the base of the cliff both contribute to more rapid coastal erosion. </li></ul>
  16. 20. Transport
  17. 21. Deposition <ul><li>Waves continually carry material on and off the land. If they carry more on than off – a beach forms! </li></ul><ul><li>Some beaches are made of sand. Some are made of shingle or small pebbles. </li></ul>
  18. 22. Coastal Landforms Old Harry Rocks in Dorset
  19. 23. Coastal Landforms <ul><li>Coastal landforms include: </li></ul><ul><ul><li>Wave cut platforms </li></ul></ul><ul><ul><li>Coves & Bays </li></ul></ul><ul><ul><li>Sea arches </li></ul></ul><ul><ul><li>Sea stacks and stumps </li></ul></ul><ul><ul><li>Spits </li></ul></ul>
  20. 24. Introduction <ul><li>Day and night, the waves are hard at work. They erode parts material from some parts of the coast and deposit it in other parts. </li></ul><ul><li>The coast is made of hard and soft rock and over time it makes various landforms . </li></ul>
  21. 26. This coastlines is made of different rock types, some hard, some soft. Once upon a time it was straight.
  22. 27. This coastline consists of parallel bands of hard and soft rock which were perpendicular to the sea. As a result of differential erosion, the bands of soft rock are eroded much more quickly than the bands of resistant rock to form bays and headlands . The headland is eroded back as a result of wave refraction. Caves , arches , stacks and stumps will form which will eventually be eroded away. The bays will advance as deposition will take place at their heads to form Beaches . Eventually, the coastline will become straight again and the whole process of differential erosion will start again and result in an irregular coastline.
  23. 29. As waves enter the shallow waters of the headland, the influence of the shallow waters causes the wave fronts to bent and get refracted. Due to the wave refraction, wave energy is more concentrated towards headlands and dissipated towards bays. Differential rates of erosion along a coast with alternate bands of hard and soft rocks results in an irregular coastline - Headland and Bay. Marine processes - hydraulic action and corrosion erode along lines of weakness (e.g. joints, faults and bedding planes).
  24. 30. The top portion of the sea caves becomes an arch, linking the tip of the headland with the mainland. Continuous erosion causes back-to-back caves to extend backward until the sea caves meet and a natural tunnel is formed. When the arch collapses, the sea ward pillar is left standing and becomes a stack. Continual wave erosion eventually reduces the stack into a stump.
  25. 32. How caves, arches and stacks form (1) <ul><li>The sea attacks cracks in the cliff at the headwall. The cracks grow larger – and form a cave . </li></ul>
  26. 33. How caves, arches and stacks form (2) <ul><li>The cave gets eroded all the way through. It turns into an arch . Then one day … </li></ul>
  27. 35. How caves, arches and stacks form (3) <ul><li>… the arch collapses, leaving a stack . In time, the waves erode the stack to a stump . </li></ul>
  28. 39. Coves Lulwoth Cove, Dorset
  29. 41. Stair Hole Lulworth Cove Stair Hole Lulworth Cove
  30. 43. Cove formation (1) The Lulworth coast was once a solid cliff with a stream running down to the sea
  31. 44. Cove formation (2) Once breached, the softer cliffs behind were rapidly eroded
  32. 45. Cove formation (3) This process continues for many years
  33. 46. Lulworth today
  34. 48. Lulworth tomorrow!
  35. 49. The next Durdle Door could well form between Lulworth Cove and Stair Hole
  36. 50. The future? Could Lulwoth become like Manowar Cove, Dorset Coast? Old Lulworth Cove? Old Stair Hole? Place of old arch? Sea Stump
  37. 51. Wave Cut Platforms
  38. 52. Destructive waves at an exposed coast erode a steep coastal slope through processes like hydraulic action and abrasion . The waves erode along lines of weakness in the rock face to form a notch. Continued erosion enlarges the notch and causes its roof to collapse, and a cliff is formed. Further undercutting at the base of the cliff results in an overhanging cliff which eventually collapses. As the steep cliff retreats landwards, a flat terrace at the foot of the cliff is exposed - wave-cut platform. The eroded materials which are transported away may be deposited in the sea to form an offshore terrace.
  39. 55. Coastal Spits
  40. 56. Coastal spits <ul><li>Spits are long, narrow accumulations of sand and/or shingle with one end joined to the mainland and the other projecting out into the sea. </li></ul><ul><li>Sandy are formed by longshore drift . </li></ul>
  41. 57. The end of spit is curved by the waves Direction of longshore drift
  42. 59. Your turn