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Erosion New

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Erosion New

  1. 1. EROSION
  2. 2. EROSION: <ul><li>TRANSPORT OF SEDIMENTS </li></ul>
  3. 3. AND DEPOSITING THEM ELSEWHERE
  4. 5. EROSION IS DRIVEN BY THE FORCE OF GRAVITY
  5. 6. THE AGENTS OF EROSION ARE: <ul><li>RUNNING WATER </li></ul><ul><li>WIND </li></ul><ul><li>MOVING ICE (GLACIERS) </li></ul>
  6. 7. Each Agent of Erosion Produces it’s Own Characteristic shape and Texture in the Sediment :
  7. 9. ROUNDS AND SMOOTHES THE ROCK SURFACE ALSO MAKES IT SMALLER
  8. 10. WIND BLOWN SEDIMENTS FROST AND PIT THE ROCK SURFACE
  9. 11. SMALL SEDIMENTS IN THE GLACIER POLISHES & SMOOTHES THE ROCK SURFACE LARGE SEDIMENTS SCRATCH AND STRIATE THE ROCK SURFACE
  10. 12. FALLEN ROCKS ARE SHARP & ANGULAR
  11. 13. RUNNING WATER The primary agent of erosion is:
  12. 14. Colorado River
  13. 15. Grand Canyon
  14. 16. Niagra Falls
  15. 20. EROSION BY WATER: <ul><li>PARTICLES ARE CARRIED IN SEVERAL WAYS DEPENDING ON THEIR </li></ul><ul><li>SIZE </li></ul>
  16. 21. THREE ways streams transport sediment:
  17. 22. SEDIMENTS IN SOLUTION : <ul><li>DISSOLVED IONS </li></ul>
  18. 23. examples : <ul><li>Salt </li></ul><ul><li>calcite </li></ul>
  19. 24. Dissolved ions in solution
  20. 25. SEDIMENTS IN SUSPENSION : COLLOIDS
  21. 26. Can you think of examples : <ul><li>SILT </li></ul><ul><li>CLAY </li></ul>
  22. 28. SEDIMENTS ROLLED AND BOUNCED: <ul><li>LARGE SEDIMENTS dragged along the bottom </li></ul>
  23. 30. VELOCITY OF A STREAM DEPENDS ON: <ul><li>SLOPE (GRADIENT) AND </li></ul><ul><li>DISCHARGE </li></ul><ul><li>volume of water </li></ul>
  24. 35. Water moves faster on the outside of a bend EROSION Water moves slower on the inside of a bend DEPOSITION LABEL YOUR DIAGRAM (EROSION) & (DEPOSITION) EROSION DEPOSITION
  25. 36. Erosion occurs at points Depsosition occurs at points B & E A & F A B C D F E
  26. 37. B C D E F Maximum erosion occurs where there is maximum _____________ On a straight path the maximum velocity is in the ___________ below the ____________ center surface velocity
  27. 38. EROSION OCCURS AT THE OUTSIDE DEPOSITION OCCURS AT THE INSIDE
  28. 40. THE MOVEMENT OF THE WATER CAN EVENTUALLY FORM AN OXBOW LAKE
  29. 41. SEDIMENTS LEFT BEHIND BY STREAMS AND WIND ARE ________ <ul><li>SORTED </li></ul><ul><li>dropped off in size order </li></ul>
  30. 42. CALCULATE THE MINIMUM VELOCITY OF A STREAM NEEDED TO CARRY A PEBBLE:
  31. 43. (SEE REF. TABLE PAGE 6)
  32. 44. APPROXIMATELY 50 CM/SEC
  33. 45. WHAT IS THE MINIMUM VELOCITY NEEDED TO CARRY A BOULDER? 200 CM/SEC
  34. 46. SORTING
  35. 47. WIND:
  36. 49. EROSION BY WIND OCCURS PRIMARILY IN: <ul><li>DRY CLIMATES </li></ul>
  37. 50. The particles transported (eroded) by wind are _________ <ul><li>Sorted </li></ul>
  38. 56. Severe draughts in the mid-west during the 1920’s and 30’s caused this area to be known as the “Dust bowl”
  39. 57. Glacial Erosion: <ul><li>When more snow in winter accumulates than _______ in the summer the snow at the bottom turns to _________. </li></ul>melts ice gravity advance <ul><li>If it becomes thick enough, it’s weight will cause it to move under the pull of___________. </li></ul><ul><li>This is called a glacial _________ </li></ul>
  40. 62. <ul><li>1.Glaciers create </li></ul><ul><li>U- shaped valleys </li></ul>Characteristics of Glacial Erosion:
  41. 66. escarpment U-shaped valley
  42. 69. Advancing glacier
  43. 70. Retreating glacier
  44. 72. Long Island Sound South Shore North Shore
  45. 73. <ul><li>2. Sediments left behind by glaciers are </li></ul>STRIATIONS SHOW THE DIRECTION OF MOVEMENT OF THE GLACIER polished & striated (scratched)
  46. 75. 3. SEDIMENTS LEFT BEHIND BY GLACIERS ARE: <ul><li>UNSORTED </li></ul>
  47. 76. Advancing glacier MORE SNOW FALLS THAN MELTS
  48. 77. Retreating glacier ICE BEGINS TO MELT DUE TO CLIMATE CHANGE
  49. 87. Terminal end of advancing glacier Latest advance Melt-water carrying sorted Sediment toward the ocean
  50. 89. THE SOUTH SHORE OF LONG ISLAND
  51. 91. Glacial Till F FOUND ON THE NORTH SHORE OF LONG ISLAND
  52. 92. FASTEST VELOCITY IS AT THE CENTER OF THE VALLEY
  53. 93. Some glacial features include: escarpment U-shaped valley
  54. 94. drumlins outwash plain
  55. 95. <ul><li>Some Glacial Features include : </li></ul><ul><li>U-shaped valleys </li></ul><ul><li>Moraines: unsorted sediments </li></ul><ul><li>Drumlins: elongated moraines </li></ul><ul><li>kettle lakes: round glacial lake </li></ul><ul><li>finger lakes: elongated glacial lake </li></ul><ul><li>outwash plains: deposited by melt-water streams </li></ul><ul><li>Erratic: large rock </li></ul><ul><li>deposited by a glacier </li></ul><ul><li>Escarpment: steep cliff </li></ul><ul><li>Horn: sharp peak </li></ul>Drumlins outwash plain Kettle lakes
  56. 96. River erosion: notice the V-shaped valleys and meanders (bending)
  57. 98. Valley glacier eroding a U-shape
  58. 99. Glacial features left behind
  59. 100. Glaciers / Rivers
  60. 101. A B C A B C Match the cross sections below with the lines on the stream A B C

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