RocksRocks and theand the Rock CycleRock Cycle

Image source: www.missouristateparks.netImage source: www.missouristateparks.net

Can you think of some places where rocks and minerals can be found?

… and what about in cities or towns?

Rocks and minerals are all around us.

It takes millions of years for rocks to form - we must use our natural resources wisely.

1. IGNEOUS (Latin for fire)

2. SEDIMENTARY (Latin for settle)

3. METAMORPHIC (Greek for change)

Three Types of RocksThree Types of Rocks

• Formed when magma (the molten rock that lies under the earth’s crust) is forced to higher layers of the crust – cools & solidifies.

• There are 2 types of igneous rocks – Intrusive & extrusive

• INTRUSIVE - Formed when magma slowly solidifies inside earth. Takes thousands of years to harden. Not seen until surface rocks have been eroded away. Coarse-grained.

• EXTRUSIVE – Formed when magma ERUPTS from volcanoes or escapes through cracks to form lava. Lava cools quickly – and forms into rocks. Fine-grained, e.g. Pumice and basalt.

Igneous RocksIgneous Rocks

http://www.youtube.com/user/Sciencebox2010#p/search/0/d4XAOY-VEEI

Igneous rock is a volcanic rock that forms when magma cools and hardens. Intrusive igneous rock solidifies underground. Extrusive igneous rock solidifies above ground.

DEFINITIONDEFINITION

Images source: www.geology.comImages source: www.geology.com

Igneous RocksIgneous Rocks

Earth’s SurfaceEarth’s Surface

Molten RockMolten Rock

Volcanic eruptionVolcanic eruption

Igneous RockIgneous Rock

LET’S VIEW A VOLCANIC ERRUPTION!!!

http://www.youtube.com/watch?v=s2i4XS0Esks&feature=related

Image source: www.bprc.osu.edu/

• Erosion --> rocks and minerals break down into small pieces called sediments.

• Carried by ‘the elements’ & deposited in river beds or sea beds.

• Accumulate (build-up) in layers --> pressed together by weight of new sediments. Compressed sediments are ‘cemented’ & harden to form new rock.

Sedimentary RocksSedimentary Rocks

• Have you ever noticed layers or bands in rocks? These are the layers of sediment.

• Examples: Sandstone, limestone, chalk and shale

• Fossils are often found in sedimentary rocks. Why do you think this might be?

Sedimentary RocksSedimentary Rocks

Sedimentary rock is a rock formed near Earth’s surface from pieces of other rocks, plant or animal remains, or by the build-up of chemical solids.

DEFINITIONDEFINITION

Images source: www.geology.com

Sedimentary RocksSedimentary Rocks

Weight and pressure of sediment particlesWeight and pressure of sediment particles

LandLandSeaSea

http://www.youtube.com/user/Sciencebox2010#p/search/0/9Df4CtlZ0AQ

Image source: www.bprc.osu.edu/Image source: www.bprc.osu.edu/

• Igneous and sedimentary rocks can be changed into a

different kind of rock by extreme heat or pressure – the changed rock is called metamorphic rock.

• Original rock may be forced into new arrangements, sometimes new minerals form.

• Metamorphic rocks can also change again.

Examples:Shale --> Slate Limestone --> MarbleGranite --> Granite gneiss Sandstone --> Quartzite

Metamorphic RocksMetamorphic Rocks

Metamorphic rock is a rock formed by the transformation of existing rock, as a result of extreme heat and/ or pressure.

DEFINITIONDEFINITION

http://www.youtube.com/user/Sciencebox2010#p/search/0/ggIpPHIeJu4

Images source: www.geology.com

Metamorphic RocksMetamorphic Rocks

http://www.youtube.com/watch?v=G7AWGhQynTY&feature=related

Image source: www.bprc.osu.edu/

• Animation of the rock cycle: www.youtube.com/watch?v=U7YQ5vwaL98&feature=related

The Rock CycleThe Rock Cycle • Rock is constantly being changed by; heat, pressure, melting, crystallization, compaction, cementation and weathering.

• Move rock material through the states of; melts, igneous rock, sediments, sedimentary rock and metamorphic rock.

• This natural and ongoing cycle is known as the rock cycle.

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