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What is a rock?
Where do we find rocks?
How are rocks classified?
What is the Rock Cycle?

What is a Rock?
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Naturally-occurring mixtures of minerals, glass or organic matter.

Where do we find rocks?

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Hard
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Soft
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Shiny
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Dull
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Smooth
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Rough
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One color
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Many colors

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Classifying Rocks
Rocks are divided into 3 groups based on how they were formed:
Igneous Sedimentary Metamorphic

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Igneous Rock is formed when magma or lava cools.
Igneous rock can form:
– underground, where the magma (a hot liquid) cools slowly OR
– above ground, where the magma cools quickly.

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Igneous Rocks formed underground
(from lava or magma) usually have
LARGE crystal grains (they cooled
slowly)

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Igneous Rocks formed above ground
(from lava) usually have SMALL or NO crystals (they cooled too quickly)

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Sedimentary Rock is formed from sediments (rock fragments, mineral grains, animal & plant remains) that are pressed or cemented together.
Sedimentary rocks form at or near the earth's surface at relatively low temperatures and pressures
These sediments are moved by wind, water, ice or gravity.
Sedimentary rocks are fossil-carrying rocks. They can be formed underwater, too, and can be made up of bits of shells and skeletons of sea animals.

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Metamorphic Rocks are those that have changed due to intense temperature and pressure.
Metamorphic rocks CHANGE FORM. Both igneous rocks and sedimentary rocks can change into metamorphic rocks
Heat and pressure do not change the chemical makeup of the parent rocks but they do change the physical properties of those rocks. This rock has many layers.

The Life of a Rock
Igneous
Layers of sediment join together.
Sedimentary Rock
Melted rock cools and hardens
Metamorphic
Changes are made from pressure and heat.

Once a rock is formed, does it stay the same rock forever?
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NO!

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Rocks are continually changed by many processes, such as weathering, erosion, compaction, cementation, melting, and cooling
Rocks can change to and from the three types

Rocks become bigger
, and bigger
, and bigger , and bigger . . .
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By earthquakes
By volcanoes
By heat and pressure

Rocks become smaller , and smaller
, and smaller
, and smaller
. . .
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By erosion
By wind
By earthquake
By floods
By rain
By mudslides

The Rock Cycle Song
(Sing to the tune of "Row, Row,
Row Your Boat")
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SEDIMENTARY rock
Has been formed in layers
Often found near water sources
With fossils from decayers
Then there's IGNEOUS rock
Here since Earth was born
Molten Lava, cooled and hardened
That's how it is formed
These two types of rocks
Can also be transformed
With pressure, heat and chemicals
METAMORPHIC rocks they’ll be.

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IGNEOUS

This type of rock can be formed underwater. It is made up of bits of shells and skeletons of sea animals.
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SEDIMENTARY

This rock is formed by intense heat & pressure.
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METAMORPHIC

This rock is formed when tiny grains of sand become cemented together.
 SEDIMENTARY

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IGNEOUS

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Sedimentary rocks are formed when tiny grains of
_______ become cemented together.
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SAND

Let’s Review
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A rock that has many layers, is flat, and comes apart easily is most likely which type?
– A. granite
– B. igneous
– C. metamorphic
– D. sedimentary