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Impacts: Alteration to geographical landscapes: Landslide
Landslide is a mass descent of earth and rock down the gradient of mountain slope. Rapid rainfall and melting snow which acts as the initiator, sinks through the earth on the top slope, penetrating the ‘fault lines’ such as cracks and pore spaces in underlying sandstone, encounters a bed of shale towards the valley. Accumulation of water along the upper surface of the shale, which becomes loose and softens into slippery clay. As the grip and foundation holding the earth weakens, rapids of earth and rocks slides down the well lubricated bedding of shale, scraping the top layer of fertile topsoil together. In earlier years, great landslides move slowly and spasmodically, causing little destruction. However currently, due to excessive logging and mass emission of acidic gases to the atmosphere which is the ingredient for acid rain, barren and exposed earth and rock, which are less intact are prone to external forces of rain can easily be washed down to the mountain foot, thereby causing mass destructions to the ecosystems below. Mass of earth and rocks which rush down to valley would cause silting of rivers, making the valley more shallow.
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