Metamorphic Rocks SWBAT compare and contrast the different types and causes of metamorphism; distinguish among metamorphic textures; explain how mineral and compositional changes occur during metamorphism; understand how rocks continuously change from one type to another in the rock cycle

Types of Metamorphism How do metamorphic rocks form? –Pressure and temperature are not enough to melt a rock, but alter the texture, mineralogy, or chemical composition of a rock. Regional metamorphism –High temperature and pressure affect large regions of Earth’s crust.

Types of Metamorphism Contact metamorphism –Molten rock come in contact with solid rock, without melting the contact rock. Why is contact metamorphism usually limited to thin zones? –Lava cools too quickly for the heat to penetrate into the surface rocks.

Types of Metamorphism Hydrothermal metamorphism –Hydro – water –Thermal - heat –Very hot water reacts with rock and alters its chemistry and mineralogy

Metamorphic Textures Foliated Nonfoliated Metamorphic rocks with wavy layers and band of minerals, in long needle like crystals. Lack mineral grains with long axes in one direction. Composed of minerals that form with blocky crystal shapes

Metamorphic Textures Porphyroblasts –New metamorphic minerals that grow quite large What is the rock cycle? –The continual change of rocks from one type to another.

Rock Cycle Igneous rock Sedimentary rock Metamorphic rock Melting and cooling Weathering,erosion Lithification Weathering,erosion Lithification Heat and pressure