The rock cycleThe rock cycleUnderstanding how the Earth Understanding how the Earth

recycles materials and recycles materials and creates new creates new ““stuffstuff”” from the from the

old old ““stuffstuff””

What is the rock cycle?What is the rock cycle? All rock (except for All rock (except for

meteorites!) on Earth meteorites!) on Earth today is made of the same today is made of the same stuff as the rocks that stuff as the rocks that dinosaurs and other dinosaurs and other ancient life forms walked, ancient life forms walked, crawled or swam over. crawled or swam over.

While the stuff that rocks While the stuff that rocks are made from stays the are made from stays the same, the rocks do not. same, the rocks do not. Over millions of years, Over millions of years, rocks are recycled into rocks are recycled into other rocks. other rocks.

What are the three types of What are the three types of rocks in the rock cycle?rocks in the rock cycle?

The three types of The three types of rocks are:rocks are:

1) Igneous1) Igneous

2) Metamorphic2) Metamorphic

3) Sedimentary3) Sedimentary

Igneous rockIgneous rock Igneous rocks form when molten Igneous rocks form when molten

rock cools and becomes solid.rock cools and becomes solid. Molten rock is called Molten rock is called magmamagma when it when it

is below the Earthis below the Earth’’s surface and s surface and lavalava when it is above.when it is above.

Igneous rocks are divided into two Igneous rocks are divided into two groups, based on where the rock groups, based on where the rock forms. forms. Intrusive (or plutonic) Igneous RocksIntrusive (or plutonic) Igneous Rocks: :

Igneous rocks that form below the Igneous rocks that form below the EarthEarth’’s surface s surface

They form when magma enters an They form when magma enters an underground chamber, cools very slowly, underground chamber, cools very slowly, and forms rocks full of large crystals.and forms rocks full of large crystals.

Extrusive Igneous RocksExtrusive Igneous Rocks: Igneous : Igneous rocks that form above the Earthrocks that form above the Earth’’s s surface. surface.

Also called volcanic rocks, these form when Also called volcanic rocks, these form when lava cools quickly at or above the Earthlava cools quickly at or above the Earth ’’s s surface. surface.

Sedimentary RockSedimentary Rock Sedimentary rocks make up Sedimentary rocks make up

about three-quarters of the about three-quarters of the rocks at the Earths surface. rocks at the Earths surface.

They form at the surface in They form at the surface in environments such as environments such as beaches, rivers, the ocean, and beaches, rivers, the ocean, and anywhere that sand, mud, and anywhere that sand, mud, and other types of sediment other types of sediment collect. collect.

Sedimentary rocks preserve a Sedimentary rocks preserve a record of the environments record of the environments that existed when they formed. that existed when they formed. By looking at sedimentary rocks By looking at sedimentary rocks

of different ages, scientists can of different ages, scientists can figure out how climate and figure out how climate and environments have changed environments have changed through Earththrough Earth’’s history. Fossils of s history. Fossils of ancient living things are ancient living things are preserved in sedimentary rocks preserved in sedimentary rocks too. too.

Metamorphic RockMetamorphic Rock Have you have heard that Have you have heard that

caterpillars metamorphose caterpillars metamorphose into butterflies? Well, rocks into butterflies? Well, rocks can metamorphose too! They can metamorphose too! They don't grow wings like a don't grow wings like a butterfly. But they do change! butterfly. But they do change! Rocks metamorphose when they Rocks metamorphose when they

are in a place that is very hot are in a place that is very hot and pressure is high. You can and pressure is high. You can find such a place where Earth's find such a place where Earth's tectonic plates are coming tectonic plates are coming together. There, the colliding together. There, the colliding plates squish rocks, and hot plates squish rocks, and hot pools of magma heat them deep pools of magma heat them deep underground. underground.

The rock cycleThe rock cycle