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rock
| Term | Definition |
|---|---|
| rock | Make up the earth's crust, that are made of a mixture of minerals and other materials. Classifying Rocks: 3 ways of classifying |
| texture | the look and feel of the rocks surface; the grain: what gives the rock its texture. Grain size, grain shape, grain pattern, no visible grain |
| minerals composition | geologists use a microscope to observe the shape and size of the rock’s crystals. |
| origin | Sedimentary: forms in layers from sediment 2. Igneous: forms from magma or lava 3. Metamorphic: formed deep underground with heat & pressure |
| igneous | formed from intense heat that comes from magma or lava. |
| extrusive | igneous rocks formed from lava that erupted onto Earth's surface |
| intrusive | igneous rocks formed from magma that hardens beneath Earth's surface. |
| texture | depends upon the size and shape of the crystals |
| porphyritic texture | large crystals surrounded by small crystals, which form when magma cools in two stages. |
| uses of igneous rocks | Used because they are hard, dense, and durable |
| Basalt | gravel |
| pumice | cleaning and polishing |
| perlite | soil mixes |
| obsidian | sharp tools |
| granite | building materials |
| sedimentary rocks | formed from layers of sediment deposited by water and wind; |
| sediment | small solid pieces of rock or living things. |
| changing sediments to rocks | A. Erosion: wind or water carry sediments B. Deposition: when the water or wind stops carrying the sediments C. Compaction: presses sediments together D. Cementation: when dissolved minerals and sediment glue together. |
| clastic rocks | formed sedimentary rocks are squeezed together |
| examples of clastic rocks | shale, sandstone, conglomerate, and breccia |
| organic rocks | formed when layers of plants and animals are deposited in thick layers |
| examples of organic rocks | coal, and limestone |
| chemical rocks | when minerals are dissolved in a solution crystallize |
| uses of sedimentary rocks | A. Limestone and sandstone: building materials B. Coal: fossil fuel |
| metamorphic rocks | formed from heat and pressure deep beneath the earth's surface change sedimentary and igneous rocks into metamorphic |
| grains | the arrangement of the grains |
| foliated | grains arranged in parallel layers or bands |
| non- foliated | mineral grains are arranged randomly |
| uses of metamorphic rocks | A. Marble: building materials B. Slate: flooring, roofing, chalkboards |
| limestone changes to | marble |
| sandstone changes to | quartzite |
| shale changes to | slate |
| granite changes to | gneiss |
| The rock cycle | Forces inside the Earth and at the surface of the Earth produce a rock cycle that builds, destroys, and changes the rocks in the crust. |
| sub-ducting oceanic plates | Plate movements (downward) drive the rock cycle by pushing rocks back into the mantle, where they melt and become magma again. |
| colliding continental plates | Plate movement that causes folds, faulting, and uplifting of the crust that move rocks through the rock cycle. |