Clastic Sedimentology And Petrography-jan 2018-quiz II-

30 Questions | Total Attempts: 93

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Clastic Sedimentology And Petrography-jan 2018-quiz II-

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Questions and Answers
  • 1. 
    At high wind velocities silt- and clay-sized particles are carried as bed load.
    • A. 

      True

    • B. 

      False

  • 2. 
    A desert is a continental area that receives little precipitation.
    • A. 

      True

    • B. 

      False

  • 3. 
    Draa is an area where sand has accumulated as a result of aeolian processes.
    • A. 

      True

    • B. 

      False

  • 4. 
    Sand grains that have undergone a sustained period of aeolian transport therefore become angular, or even very angular.
    • A. 

      True

    • B. 

      False

  • 5. 
    Effective and selective separation of grains during transport means that aeolian deposits are typically well-sorted
    • A. 

      True

    • B. 

      False

  • 6. 
    This winnowing effect, the selective removal of finer grains from the sediment in a flow, also occurs in water flows, but is more effective in the higher density and viscosity medium of water.
    • A. 

      True

    • B. 

      False

  • 7. 
    Most modern and ancient wind-deposited sands are quartz arenites.
    • A. 

      True

    • B. 

      False

  • 8. 
    Aeolian carbonate deposits are lessstable features than dunes made of quartz sand.
    • A. 

      True

    • B. 

      False

  • 9. 
    Ripple heights (bottom of the trough to the top of a crest) range from less than a meter to more than ten of meter.
    • A. 

      True

    • B. 

      False

  • 10. 
    Where a crest becomes well-developed grains may avalanche down into the adjacent trough forming plannar-lamination.
    • A. 

      True

    • B. 

      False

  • 11. 
    Sand dunes built up by aeolian action can form adjacent to beaches in any climatic setting.
    • A. 

      True

    • B. 

      False

  • 12. 
    Oxidising conditions in deserts preclude the preservation of much fossil material, and sediments are typically red–yellow colours.
    • A. 

      True

    • B. 

      False

  • 13. 
    Debris flow material form any size from clay to large boulders may be present
    • A. 

      True

    • B. 

      False

  • 14. 
    Turbidity current  are more dense mixtures than debris flows and with a relatively low Reynolds number are usually turbulent flows.
    • A. 

      True

    • B. 

      False

  • 15. 
    Turbidity current flow down slopes or over a horizontal surface provided that the thickness of the flow is greater downflow than it is upflow.
    • A. 

      True

    • B. 

      False

  • 16. 
    Turbidity currents, and hence turbidites, can occur in water anywhere that there is a supply of sediment and a slope
    • A. 

      True

    • B. 

      False

  • 17. 
    The last material to be deposited from a turbidity current will be the coarsest as this will fall out of suspension first.
    • A. 

      True

    • B. 

      False

  • 18. 
    High-density turbidity currents have a bulk density of at least 1.1 g cm-3 .
    • A. 

      True

    • B. 

      False

  • 19. 
    Avalanches are mechanisms of mass transport down a steep slope, which are also known as grain flows.
    • A. 

      True

    • B. 

      False

  • 20. 
    Grain flow  mechanism is most effective in poorly sorted material falling under gravity down a steep slope such as the slip face of an aeolian dune.
    • A. 

      True

    • B. 

      False

  • 21. 
    Small-scale erosional features on a bed surface are referred to as sole marks.
    • A. 

      True

    • B. 

      False

  • 22. 
    Flute casts are symmetric in cross-section with one steep edge opposite a tapered edge.
    • A. 

      True

    • B. 

      False

  • 23. 
    Rill marks are small-scale dendritic channels  formed by the erosion of non-cohesive sand.
    • A. 

      True

    • B. 

      False

  • 24. 
    Desiccation cracks are often filled with finer sediment.
    • A. 

      True

    • B. 

      False

  • 25. 
    Raindrop impressions are formed by rain falling onto a non-cohesive sediment surface.
    • A. 

      True

    • B. 

      False

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