The Rock Cycle

Section 3.2 Vocabulary to know: Igneous rock Magma Lava Extrusive igneous rock Intrusive igneous rock Texture Composition Silicate

What are igneous rocks? Igneous rock- Form from molten rock deep within the Earth that has cooled… OR… From molten rock that has reached the surface and cooled lava Temperatures deep within the Earth are hot enough (14000F to 23000F) to melt rock

Where do igneous rocks come from? Volcanoes! Extrusive igneous rock- Forms when lava cools on Earth’s surface Intrusive igneous rock- Forms when magma cools within the Earth

Textures of igneous rocks Texture = size of the rock’s mineral crystals Large crystals- slow cooling time Intrusive rocks commonly have large crystals Small/No crystals- fast cooling time Extrusive rocks commonly have small or no crystals

How can you tell the difference between salt and sugar?

Answer = look at their composition! Igneous rocks are mainly made up of silicate minerals

Ship Rock Formed 1km below Earth’s surface It was once intrusive igneous rock It is what’s left behind of magma that once fed a volcano Through weathering and erosion, surface rock has been worn away… …Ship Rock survives because igneous rock is usually harder than other types of rocks

Section 3.3 Vocabulary to know: Sedimentary rock Sediment Cementation Coal Limestone Crossbeds Ripples

What are sedimentary rocks? Forms from loose material (sediments) that get pressed together (cemented) into rock Sediments- Can be pieces of rocks, minerals, plants, or animals

Sedimentary rock formation… Rainwater washes away rock particles… Flow downhill to streams and rivers… Eventually these sediments reach the ocean… Settle on the bottom of the ocean… Pressure eventually forces these sediments together… Sedimentary rock is formed!

Fossils can also make sedimentary rock Coal- Made up of remains of plants (dead wood, bark, leaves, etc.) Started forming millions of years ago Limestone- Made up of remains of ocean organisms (shells, bones, etc.) Pressure “squishes” these materials together into rock

Coal formation A- Dead pieces of plant matter collecting on lake bottom B- sediments applying pressure on top of plant matter C- Even greater pressure applied D- Coal is created

Limestone towers (Mono Lake) Minerals can dissolve in water … …and then re-form as the water evaporates Often they form underwater… …and as the water level drops they become visible

Sedimentary rocks can teach us about the past… Crossbeds- These layers were once moving sand dunes Ripples- The surface of this sandstone preserves ancient sand ripples

Section 3.4 Vocabulary to know: Metamorphic rock Metamorphism Recrystallization Foliation Foliated rock Nonfoliated rock

What are metamorphic rocks? Forms when heat or pressure cause older rocks to change into new types of rocks Metamorphism- The process in which existing rock is changed by heat or pressure

Metamorphic rock formation During metamorphism rocks undergo many changes Heat and pressure can break the bonds that join the atoms in minerals… the atoms then join together differently Recrystallization Rocks do not melt during this process!!!

Foliation Foliation- Foliated rocks- Nonfoliated rocks- An arrangement of minerals in flat or wavy parallel bands Foliated rocks- Develop under pressure Minerals flatten out or line up in bands Nonfoliated rocks- Develop if rock is made up of only one type of mineral May not be under enough pressure

The Rock Cycle