CHEMICAL WEATHERING PROMOTED BY PRECIPITATION OF SALTS

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Part 7

• CHEMICAL WEATHERING PROMOTED BY PRECIPITATIONOF
  SALTS

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• Lichens secrete acidic enzymes which can react
  with host rock, accelerating chemical weathering.
  This shows an assortment of lichens developed on
  granite in a humid environment in the Ouachita
  Mtns of Arkansas

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• Lichens and sponge moss growing on a
  carbonate-cemented sandstone. Moss absorbs and
  retains water, hastening the weathering process,
  causing a pitted texture.

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• Precipitation of sodium chloride from Vishnu
  Schist along Clear Creek in the Grand Canyon a
  very arid environment

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• Precipitation of sodium chloride on Precambrian
  granite in the Gulf of Thailand in the tropics.