Weathering and Erosion

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Weathering is the process whereby rocks exposed to the atmosphere are broken down into soil. Erosion is the process by which the land is sculpted or worn away by agents of erosion (wind, rivers etc) and material is transported and deposited away from its source. What is the difference between weathering and erosion? When a rock or particle is loose it is weathering and once that particle starts moving from its original place it is erosion. The main types of Weathering 1. Mechanical / Physical weathering – is the disintegration/ breakdown of rocks into smaller fragments. 2. Chemical weathering – is the decomposition/ decay of minerals in rocks or organic materials. 3. Biological / Biotic weathering- is the crumbling of rocks through the work of plants and animals. Mechanical / Physical Weathering Mechanical weathering breaks up rocks but does not change its mineral composition. The rock particles are not softened, and do not change their colour. Rock particles created by physical weathering can be further altered and broken down by chemical weathering. Physical weathering takes place mostly in regions where there is considerable daily range of temperature. Some rocks that are jointed break up into blocks and this is known as block disintegration. Some rocks peel off into layers, like onions this process is called exfoliation. Abrasion -physical wearing down of rocks as they rub or bounce against each other--most common in windy areas, under glaciers, or in stream channels. Process of Mechanical weathering: Frost action - Weathering occurs in places with temperatures varying above and below 0ºC. During the day water from rain, dew or melting snow seeps into cracks in rocks. At night the temperatures fall and the water in the rocks is turned into ice. When the ice freezes it expands creating pressure and the cracks are forced wider,
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