8G/H
Rocks and the Rock Cycle
Colour in the box next to each statement using the following key:
Green = I completely understand this
Orange = I am quite comfortable with this but could do some more
work to understand fully
Red = I don’t understand this and need to do some more work on this
By the end of the topic you should know the following:
How the Earth is made up of crust, mantle and core.
The approximate size of the Earth and its layers.
How igneous rocks are made.
How sedimentary rocks are made.
How metamorphic rocks are made.
How to identify the three main rock types.
Be able to explain how the Rock Cycle works.
Know the part played by a Volcano in the Rock Cycle.
Understand what Physical Weathering is.
Understand what Chemical Weathering is.
Explain what a Fossil is.
Name:
Form:
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The Earth
8G/H
This is what the Earth looks like….
If you search on the internet you will
see lots of pictures taken by astronauts
when they are in space!
Geologists are scientists that study the
earth and rocks. They have been clever
enough to work out what is INSIDE the
earth as well.
They think that the Earth is made up of THREE main layers.
CRUST
MANTLE
CORE
The THREE main layers are
1._________________ 2.__________________ 3._________________
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The Earths Structure
8G/H
The CRUST contains the least dense rock. It’s much cooler than the rest of
the earth.
The MANTLE is hotter than the crust but cooler than the core. The rocks
have a temperature of about 1600oC and they are less dense than the rocks
found at the core of the earth.
THE CORE is mostly made of IRON. It is very dense and hot with
temperatures between 2000oC and 5000oC. The INNER core is SOLID and
the OUTER core is red hot liquid rock.
WHAT ARE ROCKS MADE OF?
A set of cards will be issued to you (8Ga.1.b). These are a mixture of words
and definitions and it is your job to match the correct word to the correct
definition.
Now look at the rock samples laid out for you and the data cards (8G.a.2.a)
you have been given by your teacher.
Match your sample rock to a particular data card and write your answers
below.
Rock Name
A – Granite
B–
Limestone
C – Marble
D – Slate
E – Soil
F Chalk
Data Information Cards
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Sanstone & Granite
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We have been looking at Granite and Sandstone to name but a few of the rock
samples.
Granite is made up of interlocking minerals with NO spaces between them and
that makes them hard dense rocks that do not usually absorb water.
Sandstone has non-interlocking minerals WITH SPACES between them that
allows water to be absorbed.
PRACTICAL
Take one piece of granite and one piece of sandstone and weigh each of them.
Record you results in the table below.
Drop each one into a small beaker of water. Make sure each rock is covered
completely by the water.
Describe what you see in each beaker.
Take each rock out of the water, dry them with paper towel and reweigh them.
Rock
Sample
Initial
Weight
Observations
in water
Final
Weight
Gained/Lost
Weight
Granite
Sandstone
Conclusion
__________________________________________________________
__________________________________________________________
Questions Time 1
8G/H
Use the internet to answer the following questions:
1. Where do we find most of our rocks and minerals?
__________________________________________________________
2. Name one mineral.
_______________________
3. Name one rock.
_______________________
4. Fill in the missing vowels. These are KEY WORDS for this topic
a)
Grnt
b)
Crystls
c)
Ntrlckng
d)
Sndstn
e)
Prtcls
f)
Prs
g)
R spcs (two words)
h)
txtr
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Igneous Rock
8G/H
Deep down inside the Earth, it is very hot. In fact by about 16 Km down into
the Earth, rocks will have already melted into a liquid. This rock is MOLTEN
which is another word for MELTED. We call this kind of rock MAGMA.
There are THREE major types of rock that we must learn about. These are
_____________________
_____________________
_____________________
IGNEOUS ROCK
When magma cools down and becomes a solid it forms IGNEOUS ROCK.
Usually it cools down just underneath the surface of the Earth, but sometimes
it comes out on to the surface through a VOLCANO. When the magma (or
molten rock) flows out of the VOLCANO it is called LAVA. When the LAVA
cools you are able to see small crystals in this igneous rock.
When it cools SLOWLY underneath the earth it makes BIG CRYSTALS.
When it cools QUICKLY on the earth (LAVA) it makes SMALL CRYSTALS.
This helps us recognise and identify igneous rock.
Can you see the
crystals ?
Look at:
The Earths Structure/The Earth/Igneous Rock on the yr 8 science menu
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8G/H
Igneous Rock Formation
You can see the ‘cooling effect’ on crystals if you follow the practical below:
METHOD
1.
Warm a glass slide to around 50oC by pacing it in a warm oven.
2.
Use a glass rod to spread out some molten SALOL onto the slide.
3.
Leave the slide to cool SLOWLY on a heat proof mat.
4.
Repeat this procedure with a cold slide and after adding the SALOL
place the slide in a freezer for 10 minutes. (You can use a ice water bath
but the freezer is easier!
SLOW COOLING
FAST COOLING
After 10 minutes take the slides and look at each of them under a microscope.
Draw what you see in the boxes below:
SLOW COOLING
FAST COOLING
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8G/H
Crystal Size
This is how igneous rock is formed
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8G/H
Sedimentary Rock
Over many years the rocks that are on the surface of our Earth get worn
away. They get turned in to tiny particles of sand and dust called
SEDIMENT. This sediment gets washed away into rivers and streams by the
rain. When the rivers reach the sea, the sediment (which has been dragged
along the bottom) finally settle on the bottom of the ocean.
Over many years it gets buried by more sediment and many LAYERS build up.
The particles below get squashed and stick together forming the new
SEDIMENTARY ROCK.
We can always identify sedimentary rock because we can clearly see the
layers and sometimes dead animals get trapped in it making FOSSILS.
Sometimes this rock rises above the surface of oceans or the oceans recede
following earthquakes.
Can you see the layers
This is a picture of sedimentary
rock on the road to Dibba. Can you
see the layers in this rock?
All of this rock used to be under the
sea but the movement of the Earths
crust have pushed it up.
Look at:
The Earths Structure/The Earth/Sedimentary Rock on the yr 8 science menu
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8G/H
Fossils
If an animal or plant dies and falls to the ground as the layers are forming
they can sometimes get trapped. They will then leave a pattern or imprint in
the rock showing their shape. We call these FOSSILS
Below are some pictures of FOSSILS that people have found.
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8G/H
Sedimentary Challenge!
Use the Framework Science 8 text book to complete the following task.
Read page 84 and 85 of the text book, then write two paragraphs in the space
below describing in your own words how sedimentary rock is formed.
Include in your description the following words:
Accumulation
Cementation
Consolidation
Strata
Deposited
Evaporites
Fossils
Minerals
Sediments
Sedimentary Rock
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
Name THREE common examples of SEDIMENTARY ROCK
1._______________________
2._______________________
3._______________________
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8G/H
Do Sedimentary Rocks Differ?
You have named three different sedimentary rocks and we are going to test
them to see if they all behave in the same way.
METHOD
1. Place 2g of Chalk on a watch glass and on a balance and record the weight.
2. Add two drops of Hydrochloric Acid and observe.
3. Record your observations in the table below (including any change in mass).
4. Repeat the experiment with Chalk, Sandstone, Limestone and Shale.
Initial Mass and
observations
Final Mass and
observations
Chalk
Sandstone
Limestone
Shale
These stones are ALL sedimentary rock. What can you conclude about the way
__________________________________________________________
This is no surprise because all these rocks contain Calcium Carbonate.
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8G/H
Igneous vs Sedimentary (extension)
For homework: Complete the boxes below to show a comparison of igneous and
sedimentary rock.
How are sedimentary rocks
formed
How are igneous rocks
formed
What are the characteristics
of sedimentary rocks?
What are the characteristics
of igneous rocks?
How are different types of
sedimentary rocks formed?
How are different types of
igneous rocks formed?
Name three sedimentary
rocks
Name three igneous
rocks
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8G/H
Metamorphic Rocks
If igneous rock or sedimentary rock is buried deep in the Earth it gets very
hot and squashed. The rock is then changed by this HEAT and PRESSURE to
make METAMORPHIC ROCK. (Metamorphic means to change)
If any of these rocks gets pulled or pushed right down into the Earth, it melts
and becomes MAGMA again!
If the magma rises up and cools on the surface it can make igneous rock and
the cycle starts all over again!
MARBLE is the best known example of this type of rock. When limestone is
heated by a volcano it changes into MARBLE. Other minerals that are in
limestone give it the different colours we can see in it.
Where do you use MARBLE in your house?___________________________
Look at:
The Earths Structure/The Earth/Metamorphic Rock on the yr 8 science menu
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Identifying Rocks
8G/H
Use information from the previous pages to complete this table below:
Type of Rock
What you might see in it
Igneous
Sedimentary
Metamorphic
Use a hand lens to look at the different types of rock around the room.
Write the name of the rock in one column and say whether you think it is
igneous, sedimentary or metamorphic rock in the other column.
Name of Rock
Type of Rock
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8G/H
Rock Tests
You should now know that the three rock types will have certain FEATURES
that you can look for, to help you identify them.
IGNEOUS
Looks like cool lava
Porous
Small crystals
No reaction with acid
Can be scratched
Examples:
or
lots of colours can be see
looks MOTTLED
Large crystals
No reaction with acid
Not easy to scratch
GRANITE, BASALT
SEDIMENTARY
Made up of tiny particles or grains
Can usually see layers
Can sometimes see FOSSILS
Will react with acid to give off carbon dioxide gas
Can be easily scratched
Examples:
LIMESTONE, SANDSTONE
METAMORPHIC
Can be very dark or have coloured patches
Cannot see any particles
Sometimes you can split it into flat sheets
No reaction with acid
Not easy to scratch
Examples:
MARBLE, SLATE
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8G/H
Rock Practical
Carry out the following tests and then use the information on the previous
page to help you classify the rock type. (Say whether it is igneous,
sedimentary or metamorphic)
ACID TEST
Using a pipette, put two drops of acid on each rock you are testing. On the
table overleaf, write down your observations (LOOK & LISTEN!)
HARDNESS TEST
With the help of your teacher using the tools we have to try and scratch the
surface of each of your rocks. Write down your observations overleaf.
HAND LENS TEST
Use a hand lens to look closely at the rocks. Describe what you see.
WRITE YOUR RESULTS ON THE TABLE ON THE NEXT
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Rock Test Results
8G/H
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Practical results.
Type of
Rock
Acid Test
Hardness
Test
Hand Lens
Test
Granite
(________)
Limestone
(________)
Marble
(________)
If you complete this task try to work through Year 8/rocks 1
This is a drag and drop exercise that your teacher can put on the
interactive white board
8G/H
The Rock Cycle
After watching the video completely label the diagram of the rock cycle
with help from your teacher. (DVD 8/Scientific Eye/Program 3)
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Question Time 2
8G/H
1.
Name THREE sedimentary rocks.
------------------------
----------------------- ----------------------------
2. How are sedimentary rocks formed?
3. State 3 characteristics of sedimentary rock.
4. What is the glue that sticks the grains together in sedimentary rocks
made of?
5. Which of the following types of rock is made of the largest particles?
A)
Sandstone
B) Limestone
C) Conglomerate
6. Why are fossils found in sedimentary rock?
7. What is the main compound in sedimentary rock?
8. How are weathered pieces of rock generally transported?
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8G/H
Weathering
We use the word WEATHERING to describe what happens to rocks when they
get worn away or broken down into smaller pieces. There are THREE main
types of weathering that we are going to look at:
PHYSICAL WEATHERING
CHEMICAL WEATHERING
BIOLOGICAL WEATHERING
PHYSICAL WEATHERING
This can happen in a number of different ways:
HEAT
Rocks heat up in the sun. The outside of the rock expands _________
__________. While the inside stays cooler and ___________ and
this causes the rock to crack.
Did You Know!!!!
Gold miners in ancient Egypt heated rocks using fires and then they throw
cold water on them to make them crack open. Then they could get at the gold
inside them!
What happens to stones in the desert?:
At night:____________________________________________________
In the day:__________________________________________________
The TWO major types of physical weathering that we need to know about are:
ONION SKIN weathering and FREEZE THAW weathering
(Onion skin weathering is also know as EXFOLIATION)
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8G/H
Physical Weathering
Onion Skin Weathering
Your teacher will repeatedly heat up and cool down a piece of GRANITE. This
rock contains three minerals (white quart, pink feldspar and grey feldspar).
As the granite gets red hot and then quickly cooled in a cold beaker of water,
the rock will get weaker.
Now compare this rock to a fresh piece of granite that has not been heated.
Your teacher will hit both samples with a hammer. What do you see
__________________________________________________________
__________________________________________________________
The rock particles have been put under a great deal of stress as the rock was
heated. The spaces between the particles expand as the rock gets hotter
(Note it is not the particles that expand – just the spaces between them). The
spaces around the three main minerals all expand to different sizes and it is
this that causes the weakness and the rock to crack. This is known as Onion
Skin weathering.
Freeze Thaw
In colder climates, water gets into
cracks in the rocks. At night when the
temperature falls, this water freezes
and expands or____________
___________ and the rock
__________ apart.
Look at the two bottles of water your
teacher shows you. And record your observations
Bottle A – water at room temp
Bottle B – frozen for 24 hours
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8G/H
Wind & Water
WIND
When the wind blows hard in the desert, sand rises and acts like sandpaper on
the rocks. It gradually wears them away making more sand.
Look at the nose on the sphinx.
Why has the face worn away after many years in the desert?
__________________________________________________________
WATER
Streams and rivers carrying small particles also wear away rocks and the river
bed. This is called EROSION and usually produces the round pebbles and
stones we see in the wadis.
The sea also erodes the land as it washes against it. The waves beat against
the pebbles making them smoother and smaller over but this takes a very long
period of time.
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8G/H
Chemical Weathering
When carbon dioxide (CO2) gas dissolves in rain water it turns the rain drop
slightly ACIDIC. This means that the rain water can now attack and react
with rock that contains carbonates (e.g. limestone). The rain water will slowly
dissolve this type of rock over many years. This rain is known as ACID RAIN
Underground rivers and their caves are often formed this way.
Chemicals that pollute our atmosphere can make this happen much faster.
1. ______________ 2. ______________ 3. _____________
Look at the pictures below of examples of chemical weathering. Many statues
and buildings have been made of limestone and they are now being ‘eaten away’
by the acid rain!
For homework you are to explain the effects of acid rain on buildings, trees
and lakes. You might need to use books or the internet to help you with this
work. Include pictures in your answer.
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8G/H
Sedimentary Rock & Weather
Look at the pictures below. These are all examples of sedimentary rock that
has formed due to some kind of weathering. Can you give a suggestion of how
these rocks have been weathered over time.
________________________
________________________
________________________
________________________
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Transportation
The flow of water can move mountains!
We have seen evidence throughout this topic that water can have a big effect
on rocks.
Acid Rain, streams, rivers and glaciers are just a few ways in which water can
effect the rocks around them.
You are to research using the internet and answer the following questions on
A4 paper or in a word document
How are fossils formed?
What does strata mean?
What is the name of the famous female scientist who discovered many
fossils?
What is accumulation?
Write a sentence that uses the words Sediment, Layers and Deposits
What happens when sea water evaporates?
What is the name of the rock made from the remains of shelly sea
creatures?
What are the three different types of weathering called?
Give an example of an ‘evaporates’ rock.
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