Download - How are Rocks classified
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
Granite
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
Obsidian
Igneous
Igneous
Rhyolite
Igneous
Pumice
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
Shale
Sedimentary
Sandstone
Sedimentary
Conglomerate
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)
Sedimentary
Limestone
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.
MetamorphicSlate becomes SCHIST.
MetamorphicSchist becomes GNEISS.
MetamorphicLimestone becomes MARBLE.
Uses of Rock p. 280
Rock UseGranite BuildingsSandstone GlassObsidian Jewelry, blades (in history)Pumice Cleaning productsShale ConstructionMudstone ConstructionMarble Buildings and sculpturesSlate Roofs, floors, chalkboards