Part 7 CHEMICAL WEATHERING PROMOTED BY PRECIPITATION OF SALTS

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

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

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

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