Sedimentary rocks are one of the three main rocks groups including igneous and metamorphic rocks.The Sedimentary rocks are formed in four different ways: by the deposition of the weathered remains of other rocks, by the accumulation and consolidation of other sediments, by the deposition of the results of biogenic activity, and by precipitation from solution.
Clastic sedimentary rocks are formed by erosion by friction of waves, and by transportation where the sediment is carried along by a current. The rock is then formed by disposition and compacting where the sediment is squashed together to form a rock.
The rocks can also be formed by overburden pressure as particles of sediment are accumulated from air, ice, or water sources carrying the particles.
Chalk, limestone, sandstone, clay, and shale are a few types of common Sedimentary rocks.
Sedimentary rocks cover 75% of the Earth's surface and around 8% of the total volume of the crust. They form a bedding (also known as "strata") just above igneous rocks which cover 90-95% of the earths crust below the Sedimentary rocks. Metamorphic rocks also make up part of the Earth's crust.
Sedimentary rocks are used for coal, fossil fuels, drinking water, and ores. The rocks are also an asset to roads, houses, canals, and tunnels.
Website: http://www.sciencedaily.com/articles/s/sedimentary_rock.htm
Picture 1:http://blessan.files.wordpress.com/2010/03/sedimentary-rocks1.jpg
Picture 2: http://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Helgoland_Lummenfelsen_22067.JPG/500px-Helgoland_Lummenfelsen_22067.JPG
. Breccia
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