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Rocks Pieces of the Earth’s crust. Types of Rocks • Igneous- Rocks that formed from the fiery depths of the Earth. They form from magma and lava. – Extrusive – Intrusive • Sedimentary- Rocks that formed from the eroded sediment of other rocks through lithification (compaction, cementation) • Metamorphic- Rocks that have been changed or morphed through heat and pressure Igneous Rock • Rock that forms from cooled magma or lava. • Crystalline or glassy structure • Extrusive or Intrusive • Felsic- Thick viscous, silica rich, light colored • Mafic- Hot, thin, fluid-like, often Iron rich, dark colored Igneous Rock • Igneous Rock Examples Igneous Rock • Structure depends upon freezing temperature of rock and rate of cooling • Bowen’s reaction series – High freezing temperatures crystallize first – Depends upon composition – Discontinuous series- Mafic magma • Olivine, pyroxine, amphibole, biotite, potassium feldspar, muscovite, quartz – Continuous series- Felsic magma • Calcium rich, calcium/sodium rich, sodium rich Bowen’s Reaction Series Igneous Rocks • Crystal size depends upon rate of cooling • Fast cooling lava produces small crystals, or even no crystals (glassy) • Slow cooling magma produces large crystals. • When magma cools at different rates, large and small crystals may result creating porphoritic rock Igneous Rocks • Rock Families – Read about the 3 main types of rock families in your text. pgs 123-125 – Summarize each type of igneous rock family in your notes Igneous Families • • • • Granite (Felsic) Gabbro (Mafic) Diorite (Intermediate) Peridotite (Ultramafic) Granite Family • Mostly coarse grained felsic rocks that are generally light in color. Most granite family rocks cool slowly due to the thick sticky magma that they form from. Gabbro Family • Dark, dense coarse grained mafic rocks. • Contain the minerals pyroxene, olivine, plagioclase feldspar, amphibole, and biotite. Diorite Family • A mixture of felsic and mafic rock. • Darker than granites but lighter than gabbros. Peridotite Family • Dense coarse grained ultramafic rock. • Contain the minerals olivine and pyroxene. Sedimentary Rocks • Sedimentary rocks form from fragments of other rocks producing clastic rocks. • Through weathering and erosion, sediment is carried by wind and water. • This sediment is eventually deposited. • Deposition occurs when the moving water or wind slows down. Sedimentary Rock • Deposited material often gets sorted by size. • Large sediment often only makes it part way down rivers. • Small sediment makes it to the mouth of rivers. • Fine silts and clays gets carried out to the middle of the oceans and lakes Sedimentary Rock Sedimentary Rocks • Eventually material is formed into rock through lithification • This sorting gives rise to different types of clastic rock such as – Conglomerate – Sandstone – Shale Conglomerate Sandstone The layering that is shown here is called stratification. Shale Sedimentary Rock • Other types of sedimentary rock can be formed through chemical processes and organic material – Limestone (organic and chemical) – Halite (chemical) – Coquina (organic) Limestone Halite Coquina Sedimentary Rock • Sedimentary Rock Examples Metamorphic Rock • Metamorphic rock is rock that has been changed over time due to heat and pressure. • Crystals get squished and the texture becomes foliated • Foliated metamorphic rocks have a layered or banded appearance that is produced by exposure to heat and directed pressure. Metamorphic Rock Foliation Crystal are flattened Orientation becomes aligned Metamorphic Rock • Metamorphic Rock Examples • Foliation process animation