Classifying Rocks • 3 rock types • Sedimentary • Igneous • Metamorphic
Metamorphism • The process by which existing rock is changed by pressure or heat
Metamorphic Rocks • “change” • Igneous and sedimentary rocks that have changed due to heat and pressure • Heat and pressure cause new combinations or new crystals to form • **heating and cooling of in mantle layer may lead to this formation
Parent Rock • The original rock went through metamorphism. (the rock changed) • Ex: igneous rock and sedimentary rock “melting” together to form this new metamorphic rock) • A metamorphic rock CAN be a parent to another metamorphic rock • One rock, “melting” and turning into another
Changes in Metamorphism • Rocks may flatten and pushed together • Rocks may “melt” together to form new rocks
Recrystallization • The process by which bonds between atoms in minerals break and re-form in new ways during metamorphism
Bands in Rocks • Foliation: the arrangement of minerals in flat or wavy parallel bands. • Found in rocks made of 2 or more minerals
Nonfoliated Rock • Metamorphic rock without foliation (bands/stripes) • Primarily made of 1 mineral • Not subject to high pressure
Brain Pop http://www.brainpop.com/science/earthsystem/typesofrocks/preview.weml
Discussion • What is metamorphism? • It is any process that affects the structure or composition of a rock in a solid state as a result of changes in temperature, pressure, or the addition of chemical fluids. • Under what conditions do metamorphic rocks form? • Metamorphic rocks can form due to changes in temperature and pressure.
Discussion • What type of metamorphic rock has layers? • Foliated metamorphic rock has layers (stripes).
Challenge • Refer to book… • Compare and contrast contact metamorphism and regional metamorphism. • Contact metamorphism occurs where magma comes in contact with parent rock. Regional metamorphism occurs over a much larger area and results from increases in pressure and temperature and chemical fluids.