Sedimentary Rocks - Sedimentary Rocks The earth's surface...

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Sedimentary Rocks The earth's surface is constantly being eroded. This means that rocks are broken up into smaller pieces by weathering agents such as wind, water, and ice. These small pieces of rock turn into pebbles, gravel, sand, and clay. They tumble down rivers and streams. These pieces settle in a new place and begin to pile up and the sediments form flat layers. Over a long period of time, the pieces become pressed together and form solid rock called sedimentary rock. Most sedimentary rocks form under water. Most of the earth has been covered by water some time in the past. 70% of the earth is covered by water now. So sedimentary rocks are common all over the world. Sedimentary rocks are often rich in fossils. Sedimentary rocks occur when sediments, weathered fragments from older rocks as well as biological debris like leaves, trees, and dead animals, are deposited and stay in place long enough for rock to form. Some sedimentary rocks include sandstones, shales, and coal seams. Sedimentary deposits are very important in economic geology for they include coal seams and oil deposits. Sediments can harden into sedimentary rock in two ways. 1. Pressure-As layer after layer of sediments are deposited, the lower layers are pressed together
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This note was uploaded on 07/28/2010 for the course BIO 100 taught by Professor Dddd during the Fall '09 term at A.T. Still University.

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Sedimentary Rocks - Sedimentary Rocks The earth's surface...

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