How are Rocks classified Chapter 7 Lesson 2 Pages 274-281
Igneous Rock p. 274 • Igneous rock is rock that is formed when melted rock hardens. • Magma is melted rock inside the Earth. • Lava is melted rock at the Earth’s surface. • Crystallization is the hardening of magma into rock.
Igneous Rock p. 274Intrusive • Intrusive rock cools underground, deep within the Earth’s crust. • Characteristics of intrusive igneous rock: • --Intrusive rocks cooled slowly. • --Intrusive rocks have large crystals. • --These rocks have coarse texture. • Examples: Granite and Diorite
Igneous Rock p. 274Extrusive • Extrusive igneous rock is rock that cools on the Earth’s surface. • Extrusive rock cools quickly on the surface. • Extrusive rock has fine grains or even no crystals at all and • looks glassy • Examples: Obsidian, Pumice and Rhyolite
Sedimentary Rock p. 276 • Sedimentary rock is rock that forms when layers of sediment settle and bind together. • There are two main groups of sedimentary rock, Clastic and Chemical
Sedimentary Rock p. 276Clastic • Clastic-The word comes from the Greek word that means “broken”. • Process begins when rock is broken through weathering. • Wind and water move sediment to new places, layers build up; minerals bind layers. • Layers are pressed and cemented together. • Clastic rocks are classified by size of particle.
Sedimentary Rock p. 276Clastic • Examples of clastic sedimentary rock • Fine particles form shale. • Medium particles form sandstone. • Coarse pebble-sized particles with smooth edges form conglomerates.
Sedimentary Rock p. 276Chemical • Chemical sedimentary rocks form when chemicals in water come out of the water (evaporate) and form solids. • Example: Limestone (may contain fossils)
Metamorphic Rock p. 278 • - Meta means “change”. • How metamorphic rock is made: • Igneous or sedimentary rock is changed by • PRESSURE • HEAT – high temperature, very hot water • BOTH
Metamorphic Rock p. 278 • Metamorphism is the process by which rock is changed into metamorphic rock. • The main cause is high temperature-deep inside the Earth or in lava/magma. • Minerals melt and then crystalize into new minerals.
Metamorphic Rock p. 278 • Regional Metamorphism takes place over a large area • Mountain building • Contact metamorphism changes a smaller area by magma or lava touching rock and changing the rock that was touched.
Metamorphic Rock p. 278 • Examples • Shale becomes SLATE. • Slate becomes SCHIST. • Schist becomes GNEISS. • Limestone becomes MARBLE.
Metamorphic Shale becomes SLATE.
Metamorphic Slate becomes SCHIST.
Metamorphic Schist becomes GNEISS.
Metamorphic Limestone becomes MARBLE.