Transcript Rocks and their forming NH

Types of Rock
There are 3 types of rock:
Sedimentary
Metamorphic
Igneous
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Sedimentary Rock – Deposition
At this stage dead creatures may
become trapped within the sediment
giving rise to fossils.
Slow water
Pressure
cementation
Over millions of years, the pressure of
the layers formed above and the
effects of salts cement the sediment
together to give sedimentary rocks like
sandstone and mudstone.
Fast flowing water
sedimentation
Small particles of rock formed by
weathering are transported into the sea
where they are deposited (sink) and
form a sediment.
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Sedimentary Rock – Sedimentation
Sedimentation + effects of pressure and minerals.
Layers of
sediments
getting older
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Sedimentary Rock - Evaporation
Some sedimentary rock is formed in
a different way.
Dissolved minerals
Precipitation
evaporation
Certain minerals are dissolved in
seas and lakes.
Over millions of years these seas or
lakes have dried up.
As the water disappeared the
dissolved minerals precipitated.
Pressure
Chalk and limestone, common in the
UK, are often formed in this way.
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Sedimentary Rock - appearance
Sedimentary rocks consist of lots of
small particles and may be soft and
crumbly
They do not normally contain crystals
but may have fossils trapped within
them.
When viewing a whole cliff face of
sedimentary rock it is often possible to
see layers where slightly different
sediments have been deposited.
Sedimentary rocks consist of lots of
small particles.
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Sedimentary Rocks
sandstone
sandstone
limestone
chalk
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sandstone
orangey coloured rock
looks like lots of sand grains stuck together
quite soft
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limestone
grey/white coloured rock
mostly made from crushed sea-shells
may contain fossilised shells
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chalk
grey/white coloured rock.
mostly made from crushed sea-shells
may contain fossilised shells
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Match the rock with the description:
Rock
Picture
Sandstone
Limestone
Mudstone and shale
Chalk
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Metamorphic Rock - formation
Metamorphic rocks are formed by the effect of extreme
pressures and temperatures deep within the Earth.
This alters the structure of the existing rock.
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Metamorphic Rock - properties
They are usually denser and harder than
sedimentary rocks.
They often have layer structures of crystals
caused by the effect of heat and pressure.
They sometimes show distortions caused
by the movements that led to their
formation. This may give rise to wavy or
zig-zag patterns within the rock.
Regular layers of crystals that
sometimes also have a wavy or
zig-zag arrangement
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Metamorphic Rocks
marble
slate
Enlargements on next two slides
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marble
High temperatures cause the shells in limestone to break
down into crystals giving a harder smoother rock.
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slate
Pressure and some heat makes the particles in mudstone
line up in one direction. This makes a rock that can be
split into sheets.
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Which description goes with the rock?
Description
Rock
Dark grey rock used for roofing
because it is easily split into thin
layers.
Marble
Mica
Smooth, hard white rock often used
for kitchen cutting “boards.”
Transparent sheets are used as an
insulator in some electrical devices.
It is also ground up and used as a
“filler” in plastics, and cosmetics
such as lipsticks.
Slate
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Igneous Rocks - Formation
Deep within the ground is molten rock called magma.
Sometimes this bursts through the surface in the form
of volcanoes.
Igneous rocks are
formed when molten
magma cools and
solidifies.
This may happen within
the ground, or in the
case of volcano lava,
above ground.
extrusive
igneous rock
intrusive
igneous rock
magma
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Igneous Rocks – Rate of Solidification
The appearance of igneous rocks is
affected by how fast they cool.
Rocks formed within the ground are known as
intrusive igneous rocks . They cool slowly
and this gives time for large crystals to grow.
Rocks formed once the magma has
burst through the surface are called
extrusive igneous.
They cool quickly.
As a result crystals are much smaller.
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Igneous Rocks - intrusive
granite
A hard grey rock consisting of randomly arranged crystals.
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Igneous Rocks - extrusive
pumice
Extrusive igneous rocks, like pumice and basalt, do not have large
crystals and tend to be less dense than intrusive rocks like granite.
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Igneous Rocks - extrusive
basalt - pillars
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Igneous Rocks – Properties
Igneous rocks are hard.
They contain crystals. The the size of the crystals
depends on how quickly the rock solidified.
The crystals are disordered (unlike some
metamorphic rocks.)
They never contain fossils.
Igneous rocks consist of a
disorderly collection of crystals
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Am I igneous, sedimentary or metamorphic?
Description
I am formed by heat and pressure.
I contain some really big crystals.
I am mudstone.
I contain many small grains
“cemented” together.
My particles are arranged in bands
that are easily split apart.
I am pumice.
I contain many fossils.
Type
metamorphic
igneous (intr)
sedimentary
sedimentary
metamorphic
igneous (ext)
sedimentary
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Rock Formation
rocks are broken
up by the action
of weather
volcano
Igneous rocks
basalt
rises to
surface
where it
cools
rapidly
rocks rise
to surface by
uplift and erosion
transportation
and deposition
sea
Sedimentary rocks
mudstone
Igneous rocks
granites
slow
solidification
high pressure
and temperature
Metamorphic rocks
slate and marble
magma
melt
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Fill in the gaps in the sentences.
• Rocks take part in a rock cycle.
magma
• Molten ___________
solidifies at or near the
igneous
surface of the Earth to form ___________
rocks.
weathering
• These undergo ___________
where they are
physical
broken up by ___________
and chemical
processes.
magma
metamorphic
weathering
physical
sedimentary
igneous
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Fill in the gaps in the sentences.
• The fragments of rock are carried to the
sea
___________
by rivers. Here they sink and form
sedimentary rocks.
___________
pressure
• Over millions of years heat, ___________
and
movement may change these sedimentary rocks
metamorphic rocks. Some of these will
into ___________
sink deep into the Earth and turn into
magma
___________
and the cycle is repeated.
magma
metamorphic
pressure
sedimentary
sea
igneous
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What type of rocks do these diagram represent?
igneous
metamorphic
sedimentary
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1. What type of rock is granite?
A
B
C
D
Intrusive Igneous
Extrusive Igneous
Metamorphic
Sedimentary
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2. What type of rock is slate?
A
B
C
D
Intrusive Igneous
Extrusive Igneous
Metamorphic
Sedimentary
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3. What type of rock is limestone?
A
B
C
D
Intrusive Igneous
Extrusive Igneous
Metamorphic
Sedimentary
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4. What type of rocks are pumice and basalt?
A
B
C
D
Intrusive Igneous
Extrusive Igneous
Metamorphic
Sedimentary
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5. What type of rock is mudstone?
A
B
C
D
Intrusive Igneous
Extrusive Igneous
Metamorphic
Sedimentary
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6. What type of rocks is made from
mudstone or shale?
A
B
C
D
Pumice
Limestone
Slate
Granite
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7. In this diagram showing a cross section of a
volcano, where would granite form?
A 1
B 2
1
2
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