Sedimentary Rocks

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Author:
Cheetah13
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296559
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Sedimentary Rocks
Updated:
2015-02-22 22:16:48
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Geology
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Test 2
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Test 2
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  1. __________  preserve a record of the past earth surface.

    A) igneous rocks
    B) metamorphic rocks
    C) people
    D) sedimentary rocks
    D) sedimentary rocks
    (this multiple choice question has been scrambled)
  2. What is a sedimentary environments?
    A place where sediments occur over long period of time
  3. What are the 2 classifications of sedimentary rocks?
    • Clastic sedimentary rocks
    • chemical sedimentary rocks
  4. how are clastic sedimentary rocks formed?
    Clastic sedimentary rocks are rocks made of grains that were transported (gravel, sand, mud)
  5. What are the types of clastic sedimentary rocks?
    • conglomerate/breccia
    • sandstone
    • shale
  6. How are chemical sedimentary rocks formed?
    • Chemical sedimentary rocks are made by organisms from chemicals dissolved in water or less commonly minerals chemically precipitate out of evaporating water
    •        -most common way is marine organisms take chemical and use them for shells and such
    •        -less common way is evaporating
  7. What are they types of chemical sedimentary rocks?
    • limestone
    • dolostone
    • evporites
  8. Where do clastic sedimentary rocks accumulate?
    • glacial deposits
    • alluvial fans
    • rivers, streams
    • barrier island
    • delta
    • reef
  9. What are the characterisitcs/ properties of sedimentary rocks?
    • composition
    • texture
    • sedimentary structures
    • bed geometry
    • vertical variations
    • fossils
  10. What does composition tell about the past earth environment?
    • most limestone forms in warm, shallow, sediment-free seas
    • dolomite forms from diagenesis of limestone
    • evaporate rocks are indicative of dry climate
  11. What does texture tell about the past earth environment?
    • grain size- coarse grain size is produced by high energy flows--fine grain size reflects deposition by slow moving flows or still water
    • sorting- well sorted deposits consist of a narrow range of grain sizes; tends to form from deposition by water or wind--poorly sorted deposits consist of a wide range of grain sizes; tends to form from deposition by melting glacial ice or mass wasting
    • grain shape- transport in water/winder produces rounded grains; angular grains indicate deposition directly from melting ice or from mass wasting
  12. What does sedimentary structures tell about the past earth environment?
    • Cross-bedding- forms from migration of ripples or dunes; found in sediments deposited by rivers, waves, or wind; characteristics of cross-bedding differ in different environments
    • planar lamination- forms most commonly in high energy flows
    • mudcracks- found on some bedding surfaces; form from periodic wetting and drying of fine-grained sediment
  13. What does bedding geometry tell about the past earth environment?
    • beds may not be horizontal
    • point bar deposits have inclined beds
    • delta foresets have inclined beds
    • river channel fills may have trough-shaped beds
  14. What does lateral/vertical variations tell about the past earth environment?
    how they change going up vertical
  15. What does fossils tell about the past earth environment?
    • body fossils- hard parts organisms or impressions of hard parts
    • trace fossils- things like trackwave or burrows that indicated an organism moved on/through sediment
  16. what are glacial deposits?
    Edge or glacial melts the ice releasing large amounts of sediments where it can be picked up or transported. If lithofied it becomes a clastic sedimentary rock.
  17. What are alluvial fans?
    (dry regions adjacent to mountains) streams coming down from mount dry up and leave sand and gravel
  18. What are rivers, streams?
    deposited sediments on flood plans
  19. What are barrier islands?
    elongated strip of sand and gravel going parallel to separated by shallow water (lagoon)
  20. What are deltas?
    formed by sand and mud dumping into the sea
  21. What are reefs?
    Shallows marine built by corals (organism) take calcum carbonate and surcrete to build its hard parts
  22. What are salt flats?
    shallow lake that the water dries up the evaporation leaves salt deposits on top  (evaporate deposits)
  23. what are deep sea fans?
    form from like an earthquake looses the sediment and water going down continental shelf form the sedimentary rock
  24. what is lithofication?
    The process of converting sediment into sedimentary rock by compaction and cementation.
  25. What is compaction?
    reduction in the volume of a sedimentary deposit that results from its own weight and the weight of any additional sediment deposited on top of it
  26. What is cementation?
    The process where by minerals crystallize in the pore spaces of sediment and bind the loose particles together
  27. What is diagenesis?
    any process that occurs in sediments after they are deposited
  28. The diagentic process commonly occurs after sediments are _____

    A) buried
    B) exposed
    C) in water
    D) transported
    A) buried
    (this multiple choice question has been scrambled)
  29. What are carbonate environments?
    • *most carbonate sediments are formed by organisms
    • *carbonate sediments accumulate primarily in warm, relatively shallow, ocean waters that are clear (free of clastic sediment input)
    • *where carbonate-producing organisms flourish
  30. What is an example of carbonate environments?
    coral reef areas
  31. How is dolostone formed?
    • *dolomite does not form at earth's surface
    • *dolostone forms from diagenesis on limestone
  32. Where is an example of where dolostone forms?
    Trucial Coast
  33. What are evaporates?
    rocks formed from minerals that precipitate out of evaporating water
  34. What is an example of evaporates?
    evaporate seawater in coastal area one will see calicite, gypsum, anhydrite, halite precipitate out of water as it evaporates
  35. What are the different kinds of limestones?
    • fossiliferous limestone- gray contain fossils
    • coquina- shell fragment cemented together
    • chalk- white, massive (homogeneous) lime stone
    • micritic limestone- limestone mud texture
  36. Shale forms from lithification of ________.
    mud
  37. What are the processes that act to lithify sediments during diagenesis?
    • compaction
    • cementation
  38. Planar lamination is commonly found in sands deposited _____.
    on the beaches
  39. Sedimentary rocks provide geologists with information about _____.
    the processes that were occurring on Earth's surface in the past
  40. Which type of rock would form from deposition on a coral reef?
    limestone
  41. Which of the following would form if deposits of a desert dune were lithhified?

    A) shale
    B) conglomerate
    C) well-sorted sandstone
    D) poorly-sorted sandstone
    C) well-sorted sandstone
    (this multiple choice question has been scrambled)

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