Sedimentary rock

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Sedimentary rock

  1. 1. Sedimentary Rock
  2. 2. Sedimentary Rock  Sedimentary rock is created when existing rock breaks down into sediments, and then the sediments are recombined by compaction and cementation
  3. 3. Sedimentary Rock  Sediments are created by three forces:  Weathering  Erosion  Deposition
  4. 4. Weathering  Weathering is any process that breaks down rock.  There are two types of weathering  Chemical weathering  Mechanical weathering
  5. 5. Chemical Weathering  Chemical Weathering is the transformation of rock into one or more new compounds  Water is the most important agent of chemical weathering
  6. 6. Mechanical Weathering  Mechanical weathering occurs when physical forces break rock into smaller and smaller pieces without changing its composition
  7. 7. Mechanical Weathering  Three forces account for the majority of mechanical weathering:  Frost wedging  Unloading  Biological Activity
  8. 8. Frost Wedging  When liquids freeze they expand, causing rock to break apart.
  9. 9. Unloading  Unloading occurs when pressure is removed from a rock body causing it to expand and break
  10. 10. Biological Activity  The activities of plants and animals can cause rock to break apart  For example tree roots can break through rock layers, or borrowing animals creating holes in rock.
  11. 11. Erosion  Erosion is the removal of rock and its movement by water, wind, ice, or gravity.
  12. 12. Deposition  When water, wind, ice or gravity loses energy the sediments are released and deposited in a new area.  Sediments are deposited according to size, with larger sediments being released first
  13. 13. Sedimentary Rock  Compaction and cementation are the two processes that change sediment into sedimentary rock.
  14. 14. Compaction  Compaction is a process that squeezes, or compacts sediments
  15. 15. Cementation  Cementation takes place when dissolved minerals are deposited in tiny spaces among the sediments.  These minerals hold the sedimentary rocks together
  16. 16. Classification of Sedimentary Rock  Sedimentary rocks like igneous rock can be classified into two groups based on how the form:  Clastic Sedimentary Rock  Chemical Sedimentary Rock
  17. 17. Clastic Sedimentary Rock  Clastic Sedimentary Rocks are created when weathered bits of rocks or minerals are cemented together
  18. 18. Chemical and Biochemical Sedimentary Rocks  Chemical Sedimentary rocks are created when dissolved minerals precipitate from water solutions  Biochemical Sedimentary rocks are created when living or once living materials are cemented together
  19. 19. Features of Sedimentary Rock  Sedimentary rock can have unique features that can help us interpret the history of the Earth.  Some Features include:  Ripples  Mud Cracks  Fossils

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