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pg. D 74 |
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Sedimentary Rock - Bits and pieces of rocks clumped together. Sedimentary Rock is formed when particles that were picked up and carried away by wind, moving water, or other forces is dropped off and deposited in a new location. Layers build up under pressure and this causes fine particles to squeeze together and harden into a layer of solid rock. (see diagram on p6. D 74) Some sedimentary rocks form as mineral crystals after water disolves minerals from other rocks. Pieces of sediment can become cemented together. Sed. Rock may also be made up of sediments that were once part of or made by living things (shells in limestone). Examples: granite, sandstone, shale ++++++++++++++++++++++++++++++++ Page D 76 and D 77 Metamorphic rock - Rock that was another kind of rock that "changed." Great heat, great pressure, and even chemical reactions change them. They become rocks with different properties. Most form underground. Metamorphic rocks can form when rocks come in contact with hot magma or lava. When a metamorphic rock forms, it does not melt. Changes occur in the structure and texture of metamorphic rock as it forms. Layers are visible effect of change. Some layers are not visible, but the rock breaks in layers. Example: Slate. Examples: Gneiss, quartzite, slate |