Sescribe how human activities can affect the rate of weathering.
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Soil erosion is caused typically by wind and rain run-off. Two deterrants to soil erosion are plant cover and limiting the speed at which water runs off the slope of the soil. Soil erosion is a natural process, but human activity can speed this process. (http://www.bcb.uwc.ac.za/Envfacts/facts/erosion.htm)
The types of tillage, planting, and deforestation being done today have caused approximately 1/5 of the world's soil be become eroded since 1950. (http://www.informaction.org/cgi-bin/gPage.pl?menu=menua.txt&main=soilerosion_gen.txt)
The Dust Bowl conditions of the 1930s were combined with overgrazing and over tilling of dry ground to cause the dry conditions that created the massive erosion of the Great Plains regions of the U.S. in the 1930s. Extended Drought was probably the factor that pushed the condition to the extreme. (http://weather.about.com/od/weatherfaqs/f/dustbowl.htm)
One factor that results from drainage of wetlands is that the buffer of the wetlands weeds, reeds and root systems cannot hold against the hurricane tidal surge and forces of winds. The U.S. experienced much devastation of coastal areas of Alabama, Mississippi and Louisiana during Hurricanes Katrina and Rita in 2005. "The dredging of many canals to provide access to oil and gas wells. The canals help salt water reach further inland, resulting in death of trees and vegetation that stabilizes wetlands. Wind blowing along the canals produces waves that erode the banks. And, storm surges produced by storms travel along canals causing erosion further inland." (http://oceanworld.tamu.edu/resources/oceanography-book/coastalerosion.htm)
Positive action can be taken to protect fragile soil from erosion. Avoid deforestation by not clear-cutting timber. Terrace fields on hillsides to avoid rapid run-off. Protect wetlands from damage by limiting canals and exposure to excessive saline conditions. Avoid over tilling and use no-till crop methods to plant and harvest. Avoid over-grazing by sheep, cattle and other ruminants.
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