Weathering and Erosion

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Weathering and Erosion

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Weathering and Erosion

  1. 1. WEATHERING Definition: Any of the chemical or mechanical processes by which rocks exposed to the weather undergo changes in character and break down.  Agents act to physically disintegrate and chemically decompose the rock and the minerals of the land surface, thus freeing elements and rendering them more mobile. This process is called weathering.
  2. 2. The breakdown do the materials of Earth’s crust into smaller pieces.
  3. 3. WEATHERING & GRADATION  The process by which land is leveled off through erosion or the transportation or deposition of sediments.  Especially the process by which a riverbed is brought to a level where it is just able to transport the amount of sediment delivered to it.
  4. 4. EXPLANATION • Gradation – Erosion: Removal of material – Deposition: Filling of depressions – Transportation of materials • Gradational agents – Water, wind, ice – All agents are powered by solar radiation and gravity
  5. 5. Weathering process Weathering can be divided into three types  MECHANICAL WEATHERING  CHEMICAL WEATHERING  BIOTIC WEATHERING
  6. 6. Mechanical Weathering Rock and mineral fragments are reduced to small size by purely physical means, without change in composition.
  7. 7. TYPES OF MECHANICAL WEATHERING There are many types of MECHANICAL WEATHERING such as  FROST WEDGING  SALT CRYSTALLIZATION  SHEETING  EXFOLIATION  SPHEROIDAL WEATHERING
  8. 8. FROST WEDGING  A PROCESS BY WHICH WATER SEEPS INTO ROCK JOINT, FREEZS AND WEDGES LIKE ROCK APART.  WATER SEEPS INTO THE ROCK FRACTURES, EXPANDS AS IT CHANGES INTO ICE, AND DISLODGES ROCKS. THE PROCESS IS CALLED FORST WEDGING.
  9. 9. SALT CRYSTALLIZATION WHEN WATER PRESENT IN THE PORES OF ROCK EVAPORATES MINUTE SALT CRYSTALLS ARE PRECIPITATED. THIS PROCESS IS CALLED SALT CRYSTALLIZATION.
  10. 10. SHEETING A TYPE OF JOINTING PARALLEL TO THE ROCK SURFACE CAUSE BY PRESSURE RELEASE.
  11. 11. EXFOLIATION THE FLAKING OR STRIPPING OF A ROCK BODY IN CONCENTRIC LAYERS.
  12. 12. SPHEROIDAL WEATHERING  THE PEELING OF A SMALL ROCK BODIES INTO ONIONLIKE LAYERS
  13. 13. CHEMICAL WEATHERING THERE ARE VARIOUS TYPES OE CHEMICAL WEATHERING SUCH AS  DIRECT SOLUTION  HYDROLYSIS  OXIDATION
  14. 14. DIRECT SOLUTION  THIS IS A PROCESS IN WHICH SOME OF THE MINERALS GET DISSOLVED IN WATER. THEY ARE THEREFORE REMOVED IN SOLUTION. ROCK SALT AND GYPSUM ARE REMOVED IN BY THIS PROCESS.
  15. 15. HYDROLYSIS  THIS IS A PROCESS BY WHICH WATER IS ABSORBED BY THE MINERAL OF THE ROCK. DUE TO THE ABSORBTION OF WATER BY THE ROCK ITS VOLUME INCREASES AND THE GRAINS LOSE THEIR SHAPE.  THE REACTION BETWEEN THE MUNERALS, ESPECIALLY SILICATES AND WATER.
  16. 16. OXIDATION  THIS IS A PROCESS IN WHICH ATMOSPHERIC OXYGEN REACTS WITH THE ROCK TO PRODUCE OXIDE IS CALLED OXIDATION.  RUSTING
  17. 17. RATE OF WATHERING  THE RATE AT WHICH ROCKS DISINTIGRATE DEPNDS BOTH ON THE TYPE OF ROCK INVOLVED AND THE EXTERNAL FORCES TO WHICH THE ROCK S EXPOSED.  BOWEN’S REACTION
  18. 18.  The process that breaks down rock through chemical changes.  The agents of chemical weathering  Water  Oxygen  Carbon dioxide  Living organisms  Acid rain
  19. 19.  Water weathers rock by dissolving it
  20. 20.  Iron combines with oxygen in the presence of water in a processes called oxidation  The product of oxidation is rust
  21. 21.  CO2 dissolves in rain water and creates carbonic acid  Carbonic acid easily weathers limestone and marble
  22. 22.  Lichens that grow on rocks produce weak acids that chemically weather rock
  23. 23.  Compounds from burning coal, oil and gas react chemically with water forming acids.  Acid rain causes very rapid chemical weathering
  24. 24.  The word ‘bio’ means life. Thus biotic weathering is any type of weathering that is caused by living organisms. Most often the culprit of biotic weathering are plant roots. These roots can extend downward, deep into rock cracks in search of water, and nutrients. In the process they act as a wedge, widening and extending the cracks.  Other causes of biotic weathering are digging animals, microscopic plants and animals, algae and fungi.
  25. 25. EROSION  PROCESS OF REMOVING EARTH MATERIALS FROM THEIR ORIGINAL SITES THROUGH WEATHERING AND TRANSPOORT.  THE WEARING AWAY OF THE EARTH’S SURFACE BY ANY NATUAL PROCESS.
  26. 26. TYPES OF EROSION THERE ARE VARIOUS TYPES OF EROSION. SOME OF IT ARE MENTIONED HERE: WATER EROSION  WIND EROSION  GLACIAER EROSION  SEA EROSION  SOIL EROSION
  27. 27. WATER EROSION  Water erosion occurs from the chemicals in the water, and the force of the flow of water in the river. There are many chemicals in the water of a river, and those chemicals can break down certain rocks, such as limestone or chalk.  This eroded rock is carried down the river. Sometimes, a crack or crevice develops. When the force of the flowing river smashes into that crack, the rock can break away, and again be carried down the river.
  28. 28. WATER EROSION
  29. 29. WIND EROSION  LIGHT OBJECTS, SUCH AS ROCKS AND PEBBLES ARE CARRIED BY THE WIND AND CAN HIT LANDFORMS, ERODING MATERIALS OFF THEM, THAT ARE CARRIED OFF IN THE WIND.  WIND EROSION, THOUGH IT MAY BE SMALL WHERE YOU LIVE, CAN TAKE QUITE A TOLL ON AREAS OF THE WORLD COVERED IN DESERT. WIND EROSION IS SIMPLE
  30. 30. WIND EROSION
  31. 31. GLACIER EROSION  ICE EROSION, BESIDES THAT OF HAIL, COMES MOSTLY IN THE FORM OF GLACIER EROSION. GLACIERS ARE GIANT BODIES OF ICE THAT CAN PICK UP HUGE PIECES OF ROCK, SOME EVEN AS BIG AS HOUSES. A COMBINATION OF THE WATER, ICE, AND PICKED UP SEDIMENT, CREATE A POWERFUL ERODING MACHINE.  GLACIERS CAN CARRY ALMOST ANYTHING, AND LIKE SANDPAPER, THE SEDIMENT JUST KEEPS INCREASING. GLACIERS ARE SUCH A POWERFUL FORCE THAT THEY CAN CARVE VALLEYS, DEPOSIT MORAINES, OR LEAD TO THE CREATION OF LANDFORMS SUCH AS DELTA'S
  32. 32. GLACIER EROSION
  33. 33. SEA EROSION  EROSION IN THE SEA ALSO OCCURS. THE SALTS AND OTHER CHEMICALS CAN ERODE WEAK ROCKS ON THE COAST, SUCH AS LIMESTONE AND CHALK. THE ERODED MATERIALS ARE CARRIED UP THE SHORE BY THE MEANS OF A LONG SHORE DRIFT.  WAVES CRASHING AGAINST THE SHORE CAN CREATE AIR PRESSURE INSIDE CRACKED ROCKS, THAT CAN EVENTUALLY BREAK THEM. FURTHERMORE, IF ROCKS, PEBBLES OR SEDIMENT IS CARRIED IN THE WAVES, THEY CAN SMASH UP AGAINST THE SHORE AND ERODE IT EVEN MORE.
  34. 34. SOIL EROSION  SOIL EROSION PAYS THE BIGGEST PRICE TO FARMERS. FLOODING, WIND ETC. CAN CARRY THE TOPSOIL AWAY FROM FARMLANDS, AND MAKE THE SOIL UNFERTILE.
  35. 35.  Process by which rocks are broken down into smaller pieces by external conditions.  Types of Physical weathering  Frost heaving and Frost wedging  Plant roots  Friction and impact  Burrowing of animals  Temperature changes
  36. 36.  The process by which water, ice, wind or gravity moves fragments of rock and soil.
  37. 37.  Rivers, streams, and runoff
  38. 38.  Glaciers
  39. 39.  Landslides, mudslides, slump and creep

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