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Sedimentary
Rocks
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Sandstone - very
prevalent sedimentary rock
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| "Whereas
igneous and metamorphic rocks are produced by internal processes within
the Earth, sedimentary rocks are formed by processes which are active at
the Earth´s surface. The surface of the land is continually being attacked by agents of weathering and erosion, such as rain and rivers, wind and moving ice. These physical agents are helped by chemical decay from percolating waters, and together they break up even the toughest rocks and produce rock waste. This is transported, mainly by rivers but also by wind, and in higher latitudes by ice. Eventually this material, now referred to as sediment, is deposited at river mouths, in lakes and in the sea. It is the accumulation of this material, often in deposits many kilometers thick, which goes to make up the sedimentary rocks." (Hamilton et al 1976, 151) |
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