Igneous Rocks

All About Rocks:Classroom LessonColleen FaddenRenee PollardAndrea Popolizio

Igneous RocksIgneous rocks are the oldest type of rocks.

Deep inside the earth where it is very hot, there is melted rock called magma.

As the magma comes up to the surface, it starts to cool and turns into solid igneous rock.

How are igneous rocks formed?All igneous rocks do not cool the same way, that is why they do not look all the same.

Depending on how the rocks cool, they are classified as either intrusive or extrusive.

Intrusive igneous rock is formed when the magma cools slowly deep under the earths surface, causing large crystals.

Extrusive igneous rock is formed when the magma comes from the volcano and reaches the earths surface through big cracks. The lava cools fast which cause small crystals.

Major characteristics of Igneous RocksNormally contains no fossils Rarely reacts with acid Usually have no layering Usually made of two or more minerals May be light or dark colored Usually made of mineral crystals of different sizes Sometimes have openings or glass fibers May be fine-grained or glassy (extrusive)

Common types of Igneous Rocks

GranitePumiceObsidianPegmitatite

Sedimentary RocksSedimentary rocks are rocks that are formed by sediments from the earth pressed together. This usually occurs underwater.

Sediments are small pieces of rocks.

How are Sedimentary Rocks Formed?Sedimentary rocks are formed by broken pieces of rocks that pile up.

When the sediments pile up they form layers.

Over a long period of time, the pieces pile up and get pressed together to form rocks.

Characteristics of Sedimentary RocksContain fossils most of the timeReact with acidHave layersMade up of pieces cemented or pressed togetherContain a variety of colorsParticle sizes are sometimes different

SandstoneCoalShaleLimestoneExamples of Sedimentary Rocks

Metamorphic RocksMetamorphic rocks are rocks that have been changed.

They are formed deep within the Earth.

Metamorphic rocks were once igneous and sedimentary rocks.

They are the least common of the three types of rocks.

How Are Metamorphic Rocks Formed?Metamorphic rocks are formed when heat and pressure are applied to sedimentary and igneous rocks.

The heat and pressure cooks the rocks and changes their structure.

The chemical changes that take place are what makes the appearance of rocks very different.

SimulationTo demonstrate how metamorphic rocks are formed, try this:Squeeze you hands together very hard. You will begin to feel heat and pressure. When the Earths crust moves, the heat and pressure cause the rocks to squeeze together so hard that the rocks change shapes.

Types of Metamorphic RocksThere are two types of metamorphic rocks: foliated and non-foliated.

Foliated metamorphic rocks have layers, or banding.

Examples of foliated metamorphic rocks are:Slate SchistGneiss

Types of Metamorphic RocksNon-Foliated Rocks are not layered

Examples of non-foliated rocks are:Marble Quartzite

Examples of Metamorphic Rocks

MarbleQuartizeMarbleGneiss

Learning More About Rocks

MaterialsEach student needs1 notebook1 hand lens

Each group needs1 Set of 12 rocks1 cardboard tray

Procedure1. Look back at your notes in your notebook from the last lesson.

Think aboutWhat properties you used to sort the rocks.Could some rocks be placed in more than one rock category?Were some rocks difficult to categorize?

Get your materials from the material table.

You need12 rocks1 tray2 hand lenses

Observe the rocks with your partner. Think about

What does each rock feel like?What does each rock look like?Which rocks are heavy?Which rocks are light?How are the rocks alike and how are they different?

4. After observing the rocks, write down some questions you have in your notebook. Share these questions with the class.

5. Put all of your materials back on the material table.

6. Read Rocks-Here, There, Everywhere with your partner.

Write in your notebook what you learned from reading Rocks-Here, There, Everywhere. Include in your writing

How rocks are formedWhere rocks are foundHow rocks change

8. Share with the class what you wrote in your notebook!

More you can doHere are two links to lessons/activities about rocks

http://www.bbc.co.uk/schools/scienceclips/ages/7_8/rocks_soils.shtml - This website allows you to virtually test different properties of rocks.

http://www.gamequarium.org/cgi-bin/search/linfo.cgi?id=9686 This is a link to a Magic School Bus episode about rocks and erosion.

Resourceshttp://library.thinkquest.org/J002289/rocks.html#http://www.kidsgeo.com/geology-for-kids/0028-metamorphic-rocks.phphttp://www.rocksforkids.com/RFK/howrocks.html#Metamorphic http://www.historyforkids.org/scienceforkids/geology/rocks/metamorphic/