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Author Question: Briefly describe two hypotheses used to explain the formation of desert pavement. What will be an ... (Read 57 times)

Chelseaamend

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on: Jul 14, 2018
Briefly describe two hypotheses used to explain the formation of desert pavement.
 
  What will be an ideal response?

Question 2

Describe how sand dunes migrate.
 
  What will be an ideal response?


katieost

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Reply #1 on: Jul 14, 2018
Answer to Question 1

Desert pavement is thought to form by either (1) deflation lowering the land surface by removing sand and silt from poorly sorted sediment, leaving only gravel and pebbles behind in a cobblestone-type arrangement, or (2) a surface that initially consists of pebbles trapping fine wind-blown sediment at protruding cobbles, forcing the fine grains to settle downward between the pebble spaces.

Answer to Question 2

Due to obstacles (vegetation, rocks, and so on) creating shadows that protect from prevailing winds, grains of sand can be deposited and remain in these wind shadows. Eventually, the sand accumulates into a dune with an asymmetrical profile, the windward slope being gently inclined and the leeward slope being steep. Between this profile and the prevailing winds, sand is continually rolled up the gentle slope and falls down the steep slope (slip face), slowly migrating the dune in the direction of air movement.


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