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Rock and Roll Making the earth under your feet Rocks v. Minerals Minerals Rocks • Made of ONE compound • Made of a bunch of different compounds • Crystalline structure (same arrangement of atoms the whole way through) • Inorganic • Different structures (mostly where there are different compounds) • Can have organic components (ex. Fossils or calcites) Minerals combine to make rocks Three forms of rocks • Igneous: made from cooled lava • Can be intrusive or extrusive • Sedimentary: existing rocks or sediment gets smashed together into one rock • Can be clastic, chemical, or organic • Metamorphic: existing rocks are changed • Can be foliated, non-foliated, or parent Igneous Rocks • Made from cooled molten rock • Intrusive rocks: the molten rock cooled below the earth’s surface • Have large mineral crystals • Rough and speckled appearance, course texture • Granite, diorite, or gabbro • Extrusive rocks: molten lava cooled above the earth’s surface • Very small mineral crystals • Fairly smooth and uniform appearance, fine texture • Basalt, obsidian, rhyolite obsidian Diorite Sedimentary Rocks • Small, fine pieces of existing rock (sediment are compressed together • Often forms in water. Why? • Often found near water, canyons, or windy places. Why? • Often forms long visible bands. Why? • Three different types: clastic, chemical, and organic Sedimentary • Clastic: can be made of very tiny or very large particles or clasts • Mudrocks < sandstones < breccia < conglomerate • Chemical: made when water evaporates from the sediment • Limestone, gypsum, halite, dolomite • Organic: compressed organic material • Fossils, coal, bio-clastic limestone Metamorphic Rocks • Existing rocks are changed using high heat, pressure, and/or very hot fluids (ex. Magma) • Parent rock: rock that existed before metamorphism • Can be igneous, sedimentary, or metamorphic • Contact with magma = contact metamorphism • Often happens where Earth’s tectonic plates meet • Makes large area of metamorphic rocks = regional metamorphism Metamorphic Rocks • Identified using texture • Foliated: high pressure squeezes rock from opposite sides • Makes altering dark and light-colored bands (slate, schist, and gneiss) • Non-foliated: made from high heat or fluids • Have one color and interlocking crystals (marble, quartzite, hornblende) • Usually made from contact metamorphism The rock cycle Rocks: breaking it down • Weathering: any process that breaks rocks into smaller pieces • Usually uses the process of erosion • Erosion: the carrying away of rocks • Common erosion forces are wind, water, and ice • Time and natural forces can have massive impacts on the appearance of rocks What are rocks good for • Ores are mined in quarries • Ore: Material that is naturally occurring and can be used for profit • Some rocks are good for construction or craftsmanship • Some rocks are used to extract precious minerals or metals found deposited inside the rock (ex. Gold, silver, silica) • Some are important parts of our diet (ex. Salt, calcium) • Coal is used for energy