8H the rock cycle

8H The Rock Cycle

8H The Rock Cycle
Rock types
Changing rocks
The rock cycle

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8H The Rock Cycle

Rock types

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8H Name that rock...

?
Believe it or not, rocks can be classified into groups
– just like living organisms.
The three main groups are:
igneous

sedimentary

What are the clues to help classify rocks?
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metamorphic

8H Sedimentary

Sedimentary rocks

Often look like flat plates stuck together.
Grains often visible, these can crumble apart.
Fossils can be present.
Rocks come from flat beds.
Often porous (let water pass through easily).

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8H Rock factory

A volcano is a giant rock factory.
Magma (molten rock) from below the ground is
pushed to the surface and cools.
The rock that forms is called igneous rock.
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8H Igneous rocks

Igneous rocks

Tough rocks with no plates visible.
The crystals (if you can see them) often interlock

and run in different directions.
No fossils present – EVER!
Rocks do not form in flat beds.
Non-porous (will not let water through)

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8H Metamorphic rock

Metamorphic rocks

Often ‘sugary’ with particles that can be arranged in
sheets or randomly.
Remains of fossils sometimes present – but not often.
Beds often have wavy bands.
Often less porous than sedimentary rocks – but
metamorphic rocks show a wide range of porosity.

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8H Your first specimen...

?
Clues:
Crystals visible
Very tough rock
Water cannot pass through (not porous)
Is it sedimentary, igneous or metamorphic?

Igneous!

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8H How about this one...

?
Clues:
Fossils present
Very porous
Layers visible
Is it sedimentary, igneous or metamorphic?
Sedimentary!

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8H And this one...

?
Clues:
Grains very small
Clear layers
Not porous
No fossils
Is it sedimentary, igneous or metamorphic?
Metamorphic!
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8H Last chance...

?
Clues:
Grains very small
No layers
Not porous
No fossils
Is it sedimentary, igneous or metamorphic?
Metamorphic!
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8H True or false?

True or false?
1. Igneous rocks form from cooling magma
produced by volcanoes.

TRUE

2. Sedimentary rocks never contain fossils.

FALSE

3. Igneous rocks are usually very porous.

FALSE

4. Sedimentary rocks often have layers.

TRUE

5. Granite is a metamorphic rock.

FALSE

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8H The rock cycle

Changing rocks

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8H All change!

Reminder:
Rocks may last a long time but they do change.
Even tough igneous rocks may be broken down to
smaller particles. We call this process weathering.
Small particles may be moved to new areas. We
call this transportation.
The two processes together (weathering and
transportation) are called erosion.

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8H Squeezing rocks

What happens to particles from eroded rock?
Sediments may be laid down by water. Over many
years the sediments build up and stick together to
form a new sort of rock.
Sometimes earthquakes and volcanoes bury old
rocks underground. Very high temperatures and
pressures change these rocks into new ones called
metamorphic rocks.

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8H The rock cycle

The rock cycle

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8H The rock cycle

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8H Rock cycle quiz

1. Metamorphic rocks are made by…
a) heat and pressure acting on other rocks
b) particles dropping out of suspension in streams and
rivers
c) a small factory outside Manchester.
2. Which of these would you NOT find in sedimentary
rocks…
a) fossils
b) layered structure
c) interlocking crystals of minerals.
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8H Rock cycle quiz

3.

The rock cycle is…
a) a way to explain how types of rocks are converted
to other forms
b) an explanation of how heating and cooling can
break down rocks
c) a musical by Andrew Lloyd Webber.

4. You could find the density of a rock sample by…
a) dividing its mass by its volume
b) dividing its volume by its mass
c) multiplying its volume by its mass.
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8H Rock cycle quiz

5. Slow cooling of magma produces rocks with…
a) large crystals
b) small crystals
c) no crystals.
6. You can dissolve the carbonate in a limestone sample
using
a) hydrochloric acid
b) cold water
c) boiling water.
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