Thursday, May 8, 2014

Year 9 - Geography - 8.5.14

Thai Sikh International School
Year 9,Geo Notes[ Topic 12,Weathering]
     1.      How is weathering different from erosion?
Weathering is the breakdown of rock by mechanical, physical and biological forces that do not remove it. No transport of material is involved apart from the weathered material slipping or falling down wards under the influence of gravity.
Erosion is the breakdown of rock by moving water, ice and to a small extent, wind which then transport the eroded material away.
      2.      What is the difference between Mechanical and chemical weathering?
Mechanical (physical) weathering involves disintegration of rocks into smaller pieces with no chemical change in their composition. It takes place in all regions where there are changes in temperature and is seen in hot tropical desert areas where there is a large daily temperature range.
Chemical weathering involves the decomposition of rocks by changing their chemical composition. It takes place in all regions where there is rain but is seen mostly in humid tropical areas with high temperatures.
      3.      In what ways do plants and animals contribute to mechanical and chemical weathering?
Plants contribute to mechanical weathering by using their roots to force apart rocks along bedding planes, joints or cracks. Burrowing animals contribute to the breaking up and loosening of rocks. Both plants and animals contribute to chemical weathering by releasing acids and other chemicals in their life cycle, including during their own decomposition.


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