Rock Your World SG

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Part 4:
Contents
Unit map
Part 1:
2
Rocks – part of the Earth System
3-9
Activity 1.1
Activity 1.2
Activity 1.3
Activity 1.4
Summary
Every rock tells a story
The deep Earth
Cycling rocks
It’s all in the crust
Lesson Outcomes Checklist Part 1
Part 2:
Minerals – ingredients in the rock recipe 10-23
Activity 2.1
Activity 2.2
Activity 2.3
Activity 2.4
Activity 2.5
Activity 2.6
Activity 2.7
Summary
Rock or mineral?
Diagnostic properties
Testing minerals
Rock identification
Mining our everyday minerals
Careers in mineral exploration
Money for rocks
Lesson Outcomes Checklist Part 2
Part 3:Rocks from the earth’s furnace
– igneous rocks
Activity 3.1
Activity 3.2
Summary
Big and small crystals
Erupting and intruding
Lesson Outcomes Checklist Part 3
4
5
7
8
9
11
12
15
19
20
21
22
23
24-29
25
27
29
Activity 4.1
Activity 4.2
Activity 4.3
Activity 4.4
Activity 4.5
Summary
Grain by grain – sedimentary rocks
Breaking rocks
Which sediments where?
Sticking things together
Grains and rocks
Making rocks from body parts
Lesson Outcomes Checklist Part 4
30-39
31
33
34
35
37
39
Part 5:Shearing, baking and burying
– metamorphic rocks
40-47
Part 6:
48-62
Activity 5.1
Activity 5.2
Activity 5.3
Summary
Activity 6.1
Activity 6.2
Activity 6.3
Activity 6.4
Activity 6.5
Activity 6.6
Activity 6.7
Summary
These rocks are so hot!
Regional metamorphosis
A tortured history
Lesson Outcomes Checklist Part 5
41
43
45
47
The rock cycle
Rocks into rocks
On the level
How do fossils form?
Is this the same as that?
Relative geological time
How long does it take?
Forming landforms
Lesson Outcomes Checklist Part 6
49
52
54
55
56
58
61
62
Part Summaries
63
Glossary
69
Icon
Meaning
Digital interactive
Hands-on inquiry
Classroom activity
Notebooking
Discussion
1
Part 1
Part 2
Rocks – part of
the Earth System
Minerals – ingredients
in the rock recipe
Part 3
Part 4
Part 5
Part 6
Rocks from the Earth’s
furnace
– igneous rocks
Grain by grain –
sedimentary rocks
Shearing, baking
and burying –
metamorphic rocks
The rock cycle
2
Activity 1.1
Activity 1.2
Activity 1.3
Activity 1.4
Every rock tells a story
The deep Earth
Cycling rocks
It’s all in the crust
1
PART
Part 1: Rocks – part of the Earth System
Rock Your World
Part 1
3
Activity
1.1
Activity type
Every rock tells a story
ROCKS HELP US:
?
What stories
could a rock
tell?
We often see rocks lying
around, but how did
they get there? Where
did they come from?
•understand how the landscapes
around us were formed
•know where it is safe to build and to
farm
•find valuable minerals.
A field
geologist
reading the
story in the
rocks.
They seem to have been
there forever, but even
rocks change. It just
takes a very long time.
Some have experienced
violent events in the
past. Others have
formed beneath warm,
shallow seas.
This is Connie Conglomerate.
Click here to hear her and her
friends' interesting stories.
A geologist knows their
stories.
Rock Your World
Part 1
Rocks – part of the Earth System
4
Activity
1.2 The deep Earth
It is very difficult
What's
to see into the
on the
Earth because it is
inside? somewhere very
?
Activity type
difficult for us to go.
Mining takes humans
deep beneath the
Earth’s surface but
how deep can they
really go?
Several types of
mines can be found around the world.
Vertical shaft mines hold the record for being
the deepest mines in the world. The deepest
mine is the Mponeng gold mine in South
Africa at 4 km. (The centre of the Earth is
6400 km deep.)
The LITHOSPHERE
is a thin crust of rock that
surfaces the Earth, but what
lies below?
?
How deep can
we dig?
The characters in
the book "Journey
To The Center Of
The Earth", the 1864
science fiction novel
by Jules Verne, look
up inside a cavern.
Does this picture
seem realistic?
Could we really
make a journey to
the Earth’s centre?
Many problems arise when digging so deep
into the Earth.
HEAT: At 5 km the temperature reaches
70ºC and therefore massive cooling
equipment is needed to allow workers to
survive at such depths.
WEIGHT: At 3.5 km the pressure of rocks
above you is 9,500 tonnes per square metre,
or about 920 times normal atmospheric
pressure. When rock is removed through
mining this pressure triples in the surrounding
rock. This effect coupled with the cooling of
the rock causes a phenomenon known as rock
bursts, which accounts for many of the 250
deaths in South African mines every year.
Rock Your World
Part 1
Rocks – part of the Earth System
5
Activity 1.2 The deep Earth Continued
?
What lies
beneath the
surface?
Lava flowing out of Mt Etna is red hot and flows like
a gooey liquid. It comes from deep underground. It
provides clues about what conditions are like deep
beneath the Earth’s surface.
An erupting volcano in Hawaii
produces a long river of lava.
UNDERLYING MAGMA CHAMBER
Click on the link to explore some
imaginary and real trips deep
below Earth’s surface.
Rock Your World
Part 1
Rocks – part of the Earth System
6
Activity
Activity type
1.3 Cycling rocks
Where do
rocks
come from?
?
ROCKS ARE MADE FROM:
other, broken down rocks
melted rock.
What are the
different types of
rocks?
Mt Everest is the highest mountain on Earth. It is
part of the Himalayas, the most massive mountain
range. It is made of rock, but how did it form?
The cliffs at the entrance to Sydney
Harbour look like solid layers of
sand. How did they form?
The island of Hawaii has one of the most
active volcanoes on Earth: Kilauea. It is a
place where new rocks are being made.
Click here to learn how rocks are
made and break down.
Rock Your World
Part 1
Rocks – part of the Earth System
7
Activity
Activity type
1.4 It’s all in the crust
DOWNLOAD e-NOTEBOOK
?
What is the lithosphere?
Describing rocks
What to use:
The lithosphere is the part of the Earth
that is made up of rock and soil.
Each GROUP will require:
•collection of rocks including common
examples of the 3 rock groups
•dissecting microscope
•camera (if available)
•internet access.
THERE ARE 3 COMMON ROCK TYPES.
These are sedimentary, igneous and
metamorphic rocks.
Each STUDENT will require:
•Notebook.
What to do:
Step 1
You have been given some examples of
three types of rocks, which have been
labelled. Your task is to examine the
rock.
Step 2
In your Notebook write a brief
description of each rock.
Click here to learn more
about the lithosphere.
Rock Your World
Part 1
Sedimentary
Sandstone
Igneous
Granite
Metamorphic
Marble
Rocks – part of the Earth System
8
1
Rocks are more than just small features that are found occasionally lying on the ground. They are the
fundamental part of the crust on which we live.
There are different types of rock, which form under different conditions and have different geological
histories.
The Earth consists of several distinct layers, including the crust, mantle, outer core, and inner core.
A combination of very high temperatures and pressures produce conditions in the mantle and core that
are quite different to those found at the Earth’s surface. As the surface is approached the pressure and
temperature drops until you reach the crust where the rock is relatively cool and solid.
Although most rocks appear to be endlessly durable they have a life story. Rocks are broken down and
rebuilt over very long periods of time.
PART
All rocks on Earth can be broadly categorised into three groups; sedimentary, igneous and
metamorphic. These groups of rocks have different characteristics that relate to the manner in which
they are formed.
DOWNLOAD LESSON
OUTCOMES CHECKLIST
Rock Your World
Part 1
Rocks – part of the Earth System
9
Activity 2.1
Activity 2.2
Activity 2.3
Activity 2.4
Activity 2.5
Activity 2.6
Activity 2.7
Rock or mineral?
Diagnostic properties
Testing minerals
Rock identification
Mining our everyday minerals
Careers in mineral exploration
Money for rocks
PART
Part 2: Minerals – ingredients in the rock recipe
2
Rock Your World
Part 2
10
Activity
Activity type
2.1 Rock or mineral?
Comparing rocks and minerals
What to use:
?
DOWNLOAD e-NOTEBOOK
What is the
difference between
rocks and minerals?
Each GROUP will require:
•samples of granite, sandstone, and calcite
•dissecting microscope.
Each STUDENT will require:
•Notebook.
What to do:
Step 1
Run your finger over the surface of the sandstone. What does it feel like?
Step 2
In pairs, take turns looking at the two rock samples (the granite and
sandstone) under the microscope. When you look closely at these rocks,
what do you notice about their structure?
Granite
Marble
Sandstone
ROCKS AND MINERALS ARE ALL AROUND US.
Step 3
Look at the mineral sample (calcite) under the microscope. How does it
compare to the rock samples?
Calcite
Gold
Quartz
Click here to discover some differences between rocks and minerals.
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
11
Activity
Activity type
2.2Diagnostic properties
WHAT IS WHAT?
We tell OBJECTS apart in
our everyday lives.
How do we do this?
?
How do we identify
different objects?
DOWNLOAD e-NOTEBOOK
CLEVER MARKETING
When you go to the grocery store
you see shelves full of breakfast
cereal.
If you already know which brand
of cereal you are looking for,
how do you locate it on the shelf?
What to do:
Write your answers in your Notebook.
How do we remember
which ones are hot?
We use
DIAGNOSTIC PROPERTIES
of objects to keep ourselves safe.
Marketing organisations
spend a lot of time putting
their clients' products in
distinctive packaging.
This allows customers to
target their product on a
shelf.
Rock Your World
Part 2
We use
DIAGNOSTIC
PROPERTIES
of objects to find
things we are
looking for.
Minerals – ingredients in the rock recipe
12
Activity 2.2 Diagnostic properties Continued
?
How can we tell
these minerals
apart?
Quartz
Potassium feldspar
Muscovite
Biotite
Calcite
Hornblende
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
13
Activity 2.2 Diagnostic properties Continued
What to use:
•specimens of common rock forming minerals (e.g.
quartz, potassium feldspar, muscovite, biotite, calcite,
hornblende) or selected images of these minerals in the
online collection Rocks and Minerals
•Notebook
•internet access.
What to do:
Step 1
In groups of 3-4, compare the six minerals provided. What
diagnostic properties of minerals could we use to tell them
apart? Record at least five of these in your Notebook.
Step 2
In your Notebook make a table with a description of each
of these six minerals.
Quartz
Potassium feldspar
Muscovite
Biotite
Calcite
Hornblende
Discussion:
How would you explain the term "diagnostic property" to
one of your friends?
Diagnostic properties of minerals
Mineral
Quartz
Potassium
feldspar
Colour
White
Muscovite
Biotite
Calcite
Hornblende
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
14
Activity
2.3Testing minerals
DIAGNOSTIC TESTS FOR MINERALS
Mohs scale of hardness was created in 1812 by the geologist
Friedrich Mohs. It describes how hard it is to scratch a mineral.
Gypsum (2) is harder than talc (1). Gypsum can scratch talc but
talc cannot scratch gypsum.
Some common tests that can be used to test hardness are
included in the following table.
Mohs Hardness Scale
Hardness
Talc
1
Gypsum
2
Calcite
3
Fluorite
4
Apatite
5
Common tests
Fingernail (2.5) will scratch it
Glass or paper clip (5.5) will
scratch it
Potassium feldspar 6
Quartz
7
Topaz
8
Corundum
9
Diamond
10
DOWNLOAD e-NOTEBOOK
Geologists use the following diagnostic tests to help identify minerals.
HARDNESS
Mineral
Activity type
Will scratch glass
Diamond (10) will scratch all
CLEAVAGE
Does the mineral split in patterns with a particular
shape? This usually reveals the shape of the crystals
it is made from. Do not break the crystals you are
examining. Try to work out the cleavage by observing
the crystal intact.
Cubic
When a mineral breaks in
three directions and the cleavage
planes form right angles (90° to each
other). Results in pieces in the shape
of a cube.
Octahedral When a mineral
breaks in the form of a diamond,
resulting in 8 nearly equal faces.
STREAK
What colour is the
powder if you scratch
the crystal on a hard,
rough surface? Often
a rough ceramic tile is
used for this test.
Rhombohedral
When a mineral
breaks in three directions and the
cleavage planes form angles that are
other than 90°. The shape formed is
called a rhombohedron.
Pinacoidal When a mineral
breaks in one direction, leaving a
single flat surface (cleavage plane).
When a mineral breaks into very
thin sheets, like mica minerals,
the pinacoidal cleavage is called
micaceous.
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
15
Activity 2.3 Testing minerals Continued
DIAGNOSTIC TESTS FOR MINERALS
Geologists use the following diagnostic tests to help identify minerals.
LUSTRE
COLOUR
How does the light shine off
the mineral? The descriptions
used for this characteristic
include:
•
•
•
•
•
•
vitreous (or glassy)
dull
waxy
metallic
silky
pearly.
Can you think of any other
terms that might fit the
minerals you are observing?
What colour is the mineral. The same mineral
can come in a few different colours, making
this a difficult test to apply sometimes.
Pyrite has a metallic lustre
Fluorite has a vitreous lustre
Kyanite has a pearly lustre
Kaolinite has a dull lustre
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
16
Activity 2.3 Testing minerals Continued
Testing quartz and biotite
?
What to use:
Can you
perform
mineral tests?
•biotite
•quartz
•streak plate
•glass slide, steel paper clip
•Science by Doing Notebook.
What to do:
Mineral
Step 1
Copy the results table into your
Notebook or download the
e-Notebook.
Step 2
In small groups conduct diagnostic
tests on biotite and quartz and
record your results in the table.
Hardness
1 to 10
Mineral
hardness is
described on
the Mohs scale,
ranging from 1
to 10.
Cleavage
Streak
Does it split in
particular ways,
revealing the
shape of its
crystals?
What colour is
its powder if it
is scratched on
a rough, hard
surface?
Colour
What colour/
colours is it?
Lustre
How does it
shine in the
light?
Quartz
Biotite
Step 3
Now obtain a copy of Activity sheet 2.3
Testing minerals. Check your results for
quartz and biotite against the entries in the
table on the Activity sheet. How did your
results compare?
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
17
Activity 2.3 Testing minerals Continued
?
Can you identify
the unknown
minerals?
A new geologist dropped a box of labeled minerals when
she was out in the field. After picking them up, she
discovered she had two unlabeled specimens.
Testing unknown minerals
What to use:
•unknown mineral A
•unknown mineral B
•mineral study kit
•streak plate
•glass slide, steel paper clip
•Science by Doing Notebook
•Activity sheet 2.3 Testing minerals.
Can you help her identify the unknown
minerals using their diagnostic properties?
What to do:
Step 1
The unknown minerals are rock forming
minerals listed in the table on Activity
sheet 2.3. Working in small groups,
test each of the unknown minerals and
complete the rows in the table.
Step 2
Explore the other minerals in the mineral
study kit. Test them and compare your
results with the table in Activity sheet
2.3.
Discussion:
Take turns to report back to the class
on each of the mystery minerals.
Explain the properties you used to
‘fingerprint’ the mineral.
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
18
Activity
Activity type
2.4Rock identification
Augite
c la s e f el ds
p
Pl
ar
io
ag
ANDESITE
The igneous rock Andesite is comprised of
the minerals plagioclase feldspar, augite
and hornblende.
?
If you know what
minerals are in a
rock, can you then
identify the rock?
Ho
r nblende
Click here to identify three rocks from their mineral makeup.
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
19
Activity
2.5Mining our everyday minerals
Activity type
MINERAL EXTRACTION
?
How do we get
minerals out of
the ground for
our own use?
10m @ 1.1g/t Au
5m @ 1.58g/t Au
Kalgoorlie Superpit
An ore is a natural deposit of rocks or minerals from which we
can extract elements (e.g. iron or aluminium) profitably. We
typically extract or mine ores from the ground using an open
pit excavation (a big hole) or by excavating underground (a
big tunnel).
Mining an ore depends on:
•the shape of the ore deposit
•how deep it is
•safety and environmental considerations, and
•how expensive it is to get the ore out of
the ground.
3m @ 0.73g/t Au
1m @1.47g/t Au
12m @ 0.38g/t Au
2m @ 4.00g/t Au
20m @0.86/t Au
15m @ 0.30g/t Au
2.15m @ 6.29g/t Au
incl 1m @ 12.06g/t Au
56m @ 0.46g/t Au
191m
0.47m @ 30.98g/t Au
121.57m @ 0.98g/t Au
Visible Gold in Quartz Vein
Basalt
2.08m @ 5.72g/t Au
Fesic Volcanics
0.21m @ 3.42g/t Au
Granite
11m @ 0.32g/t Au
6m @ 6.57g/t Au
incl 0.21m @ 1.28g/t Au
204m
Regolith
180m
8.68m @ 1.28g/t Au
Click here to find out
more about mining
and minerals.
14.66m @ 0.15g/t Au
East Kalgoolie Gold Mine Cross Section
546m
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
20
Activity
2.6Careers in mineral exploration
Activity type
A ROCKY CAREER
Finding mineral deposits that
are worth mining, takes a team
of scientists from different fields
of science...
Click here to find out
about their work.
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
21
Activity
?
Activity type
2.7 Money for rocks
THE "WELCOME STRANGER"
What are
Australia’s most
valuable rocks?
Diamonds are
very valuable.
NUGGET
The "Welcome Stranger" is
a famous 72 kg gold nugget
discovered in 1869 by John
Deason and Richard Oates
under 3 cm of soil under a
stringybark tree. In today’s
prices the nugget was worth
$2.8 million.
A very dull looking rock.
Iron ore – banded iron
formation.
Looks like gold,
sometimes called ‘fools’
gold’. Actually a mineral
called chalcopyrite. It
contains copper.
15cm
Click here to learn more about Australia’s mineral wealth.
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
22
We identify objects and separate them from others using diagnostic properties.
Geologists use diagnostic tests to help identify minerals. The hardness test is a measure from 1 (soft like
talc) to 10 (hard like diamond). Cleavage describes how the mineral splits (cubic, octahedral, etc.). Streak
is the colour when the mineral is scratched across a white tile. Colour is the colour of the mineral and
lustre is how light shines off the mineral.
Each rock type is always comprised of the same rock forming minerals. Identification of these minerals
can be used to identify the rock.
Minerals are typically the raw materials that many of our material items (e.g. cars, telephones) are made
of, or the energy supplies (e.g. coal, oil) that we use to make them operate.
The scientists that find the minerals we need for our technological society include:Geophysicists – study the physics of the Earth (gravitational, magnetic, electrical, and seismic
properties).
Geochemists – study the chemistry of rocks, soils and water bodies.
Geologists – collect rock and soil samples to test for minerals.
Minerals that seem to be most valuable, such as gold and diamonds, do not actually account for the
majority of Australia’s export income. Iron ore and coal are our main export earners.
2
PART
Minerals are not rocks. Minerals are the pure substances, or chemicals, that rocks are made from. Most
rocks contain a mixture of several minerals, as individual crystals and grains.
DOWNLOAD LESSON
OUTCOMES CHECKLIST
Rock Your World
Part 2
Minerals – ingredients in the rock recipe
23
Activity 3.1 Big and small crystals
Activity 3.2 Erupting and intruding
3
PART
Part 3: Rocks from the Earth’s furnace - igneous rocks
Rock Your World
Part 3
24
Activity
?
3.1 Big and small crystals
Activity type
DOWNLOAD e-NOTEBOOK
Why do some rocks have bigger crystals than others?
The size of
crystals in a rock
tells us about
how and where
they were made.
Comparing crystal size
What to use:
Each GROUP will
require:
GOGGLES
GLOVES
LAB COAT
SHOES
•sample of molten
phenyl salicylate (in
hot water bath)
•2 glass slides
•dissecting microscope
or compound
microscope at low
power
•pipette
•paper towel.
What to do:
Step 1
Cool a slide in the fridge. Wrap a
slide in a paper towel and warm it in
your hands.
Step 2
Place a few small seed crystals on the
centre of each slide.
Step 3
Using the pipette, add a drop of
molten phenyl salicylate over the
seed crystals on each slide.
!
ARNING: AVOID CONTACT
W
WITH SKIN AND EYES.
drop of phenyl salicylate
Step 4
Inspect the two slides using the
microscope on the lowest power.
You may be able to watch the
crystals growing.
Step 5
Record your observations in your
Notebook.
Discussion:
1. Was there a difference in the
growth and final size of the
crystals on the two slides?
2. How does this experiment model
the formation of crystals in
igneous rocks?
3. Could you design an experiment
to produce even bigger or
smaller crystals?
Rock Your World
Part 3
Rocks from the earth’s furnace – igneous rocks
25
Si
Activity 3.1 Big and small crystals Continued
Silicate TetrahedronAs magma cools it forms into crystals.
Did you know that the chemical structure
of the crystals in rocks is very similar to the
structure in glass?
IT IS BASED ON THE
ELEMENTS SILICON (SI)
AND OXYGEN (O).
Silicate Tetrahedron
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Na+
Si
Na+
Si
Si
Si
Si
Si
Si0² in its crystalline form, quartz
Si0 in it’s glass form
²
Si
What to do:
Si
Na+
Si0² in its glass form
Quartz is a true crystal,
but glass is not. What do
you notice that is different
about the structure of
quartz and glass?
Si
Make a brief note in your
Notebook.
Si0 in it’s crystalline form, quartz
²
Rock Your World
Part 3
Rocks from the earth’s furnace – igneous rocks
26
Si0
Activity
Activity type
3.2Erupting and intruding
DOWNLOAD e-NOTEBOOK
IGNEOUS ROCKS form when molten rock
called magma cools. Let’s see how geologists
sort out which ones are which.
Molten rock cooling
deep underground
Large crystals
Cools slowly
?
Molten rock might solidify deep beneath the Earth’s surface.
These form
Karlu Karlu or Devils Marbles are
located 105 km south of Tennant Creek
in the Northern Territory.
These boulders cooled slowly, deep
beneath the surface of the Earth.
How did they get to the surface?
PLUTONIC rocks. They are also called INTRUSIVE rocks.
Why?
A piece of granite
Notice the large
crystals in the
magnified image.
Rock Your World
Karlu Karlu or Devils Marbles
Part 3
Rocks from the earth’s furnace – igneous rocks
27
Activity 3.2 Erupting and intruding Continued
Notice the small
crystals in the
magnified image.
?
A volcano erupts on
Hawaii forming new
basalts. These are
no longer formed on
mainland Australia.
Why?
Comparing intrusive
and extrusive rocks
A piece of basalt
What to do:
Observe the samples of igneous
rock provided by your teacher.
Examine the rocks with a hand lens
or dissecting microscope.
Molten rock, or lava, flows from
volcanoes and solidifies on the surface.
VOLCANIC rocks.
They are also called EXTRUSIVE rocks.
These form
What differences do you observe
between the granite and basalt samples?
Make a note of these in your Notebook.
?
IGNEOUS CRYSTAL FORMATION
Why?
COOLS QUICKLY
ABOVE THE SURFACE
COOLS SLOWLY
BELOW THE SURFACE
The lava on the volcano
SMALL CRYSTALS
BIG CRYSTALS
EG BASALT
Cools quickly
Small crystals
Rock Your World
Part 3
EG GRANITE
Click here to test your understanding
of volcanic and plutonic rocks
Rocks from the earth’s furnace – igneous rocks
28
Plutonic igneous rocks form when molten rock called magma is intruded below the Earth surface. The
magma cools slowly because it is insulated by the enclosing rock, and there is time for large crystals to
grow forming a coarse-grained rock. An example of a plutonic igneous rock is granite.
3
PART
Volcanic igneous rocks form when molten rock called lava is erupted at the Earth surface. The lava cools
rapidly because there is a large temperature contrast between the lava and the air. This quenched rock
forms very small crystals resulting in a fine-grained rock. An example of a volcanic igneous rock is basalt.
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OUTCOMES CHECKLIST
Rock Your World
Part 3
Rocks from the earth’s furnace – igneous rocks
29
Activity 4.1
Activity 4.2
Activity 4.3
Activity 4.4
Activity 4.5
Breaking rocks
Which sediments where?
Sticking things together
Grains and rocks
Making rocks from body parts
PART
Part 4: Grain by grain - sedimentary rocks
4
Rock Your World
Part 4
30
Activity
4.1 Breaking rocks
Part 1: Physical weathering
What to use:
Each GROUP will require:
•9 sugar cubes
•medium glass jar and lid for
shaking the cubes
•2 beakers
•warm and cold water
•Science by Doing Notebook
•access to electronic balance.
What to do:
Activity type
DOWNLOAD e-NOTEBOOK
?
Step 2
Place the cubes in the jar and shake
20 times. Then weigh the whole
cubes again.
How do
rocks
break down?
Step 3
Repeat this step four more times.
Record the weights of the remaining
whole cubes and a photo or sketch
each time in your data table.
Discussion:
1.What changes did you observe in
Part 1: Physical weathering
the cubes?
Step 1
2.How were the changes affected by
Weigh 5 sugar cubes and record this in
the number of shakes?
your Notebook. Take a photo or draw
3.Look up the word abrasion and
a simple sketch of the cubes showing
explain how it is relevant to this
their overall shape and appearance.
experiment.
Shaking trial
Drawing/photo of 5 cubes
Mass of 5 cubes (g)
0 shakes
20 shakes
40 shakes
60 shakes
80 shakes
100 shakes
Rock Your World
Part 4
Grain by grain – sedimentary rocks
31
Activity 4.1 Breaking rocks Continued
Part 2: Chemical weathering
What to do:
Part 2: Chemical weathering
Step 1
Using only 4 sugar cubes design an
experiment to test the difference in
how quickly the cubes dissolve in
water when:
a) T
he surface area of the sugar is
increased by crushing.
b) T
he temperature of the water is
increased.
Discussion:
Chemical weathering occurs
mostly through the action of water.
Sometimes the water contains small
amounts of dissolved chemicals such
as carbon dioxide.
In your Notebook record how the
chemical weathering (dissolving)
of the sugar cubes was affected by
surface area and temperature.
Click here to see a video on
weathering and erosion.
Rock Your World
Part 4
Grain by grain – sedimentary rocks
32
Activity
Activity type
4.2Which sediments where?
When rocks weather at the Earth’s surface they break down
to form sediments.
?
What are sediments? Where do they come from?
Where are they deposited in our landscapes?
These sediments can be formed, transported and deposited in
many different places.
These places are
SEDIMENTARY ENVIRONMENTS
Sediments formed in different places have different shapes, sizes
and compositions.
Sand
dunes
River Glacier Beach
Coral
reef
These places are called
SEDIMENTARY ENVIRONMENTS
Salt lake
River
estuary
Deep
marine
Click here to look at sedimentary environments
and their sediments in more detail.
Rock Your World
Part 4
Grain by grain – sedimentary rocks
33
Activity
Activity type
4.3Sticking things together
DOWNLOAD e-NOTEBOOK
Making sedimentary rocks
What to use:
Each GROUP will require:
•a selection of gravels, sands and
silt
•a selection of possible binders
including
- PVA glue
- lime
- silica (silicon dioxide)
- gypsum
- commercial cement
- plaster of paris
•small beaker (200 ml)
•plastic cups with holes in the
bottom, and spoons.
Each STUDENT will require:
•Notebook
•camera (if available).
What to do:
Part 1
Step 1
Your task is to design an experiment
to determine which binding material
produces the most durable rock.
Step 2
Put 1-2 cm of sand or gravel in a
beaker and mix with some binding
material and a small amount of
water. You may choose which binder
to use, or which combination of
binders to use.
Step 3
Pour the mixture into a cup and
press down. Any free water will be
squeezed out of the hole at the
bottom.
?
How do
rocks
stick
together?
Step 4
Repeat this process with sediments
of different sizes, until you have
a range of ‘rocks’ using different
binders. Leave aside to set.
Part 2
Design a test that gives you
measurements that you could use
to compare the hardness of your
different rocks. How can the results
be presented in a table and also
displayed in a graph? Record your
results in your Notebook.
Discussion:
Compare your results with other
groups in the class and write a
conclusion for your experiment.
Rock Your World
Part 4
Grain by grain – sedimentary rocks
34
Activity
Activity type
4.4Grains and rocks
When sediments pile on top of each other, and water
with minerals in solution pass through, they become
compacted and cemented together. This turns them
from sediments into sedimentary rocks.
DOWNLOAD e-NOTEBOOK
The grains in a sedimentary rock are called
CLASTS
So, rocks that are made up of compacted and cemented rock fragments are called:
CLASTIC SEDIMENTARY ROCKS
Sediments are described using 5 features:
Composition
A piece
of calcareous sandstone
Grain size
Sorting
?
How are common sedimentary
rocks like mudstones, sandstones
and conglomerates formed?
What are the clasts made of?
How big are the clasts in the rock?
Are the clasts all the same size or different sizes?
Rounding
Do the clasts have smooth surfaces or rough surfaces?
Shape
Are the clasts round like a ball or long and thin, smooth
or angular?
Rock Your World
Part 4
Grain by grain – sedimentary rocks
35
Activity 4.4 Grains and rocks Continued
Characterising sedimentary rocks
What to use:
Each GROUP will require:
•specimens of sandstone, mudstone
and conglomerate
•specimens of beach sand, dried
mud or silt, pebbles
•dissecting microscope and hand lens.
Each STUDENT will require:
•internet access
•Activity sheet 4.4 Grain size
comparator
•scissors
•Notebook.
What to do:
Your task is to characterise the grains,
or clasts, that make up three different
sedimentary rocks; sandstone,
mudstone and conglomerate. Each
of these rocks is called a clastic
sedimentary rock, because they are
all made of grains or fragments that
are glued together.
Step 1
Cut out the
Grain Size
Comparator
provided in
Activity Sheet
4.4 so that you
can use it to
analyse each
specimen.
Step 2
Examine the beach sand using
the hand lens and the dissecting
microscope. Use the descriptions
provided in the table below to help
you complete your observations
table for the beach sand specimen.
Step 5
Examine the mudstone in the same
way. How easy was it to characterize
the clasts in mudstone?
Step 6
Repeat these steps using the piece
of conglomerate. You may like to
Clast characteristics
Composition
What are the clasts (grains) made of?
Grain size
How big are the clasts (grains) in the rock?
Sorting
Are the clasts all the same size or different sizes?
Rounding
Are the clasts smooth or rough?
Sphericity
Do the clasts have blocky, flat or elongated shapes?
Discussion:
Look at the clasts making up each of
the three rocks. Can you determine
which sedimentary environment
produced each rock?
Observations table
Sediment or rock Composition Grain size Sorting Rounding Sphericity
Beach sand
Sandstone
Mud or silt
Step 4
Examine the sample of mud or
silt using the hand lens and the
dissecting microscope. Fill in its line
in the table.
Sedimentary
environment
Rock
Mudstone
Step 3
Examine the piece of sandstone in the
same way and fill in its line in the table.
How did the clasts in the sandstone
compare with the beach sand?
You might like to revisit Activity 4.2
Which sediments where? and watch
the videos at the link below. Then
complete the table below.
examine the 3D conglomerate
sample in the online collection
Rocks and Minerals.
Click on the
link above and
use the tools
provided to
observe it from
all angles and
measure its clasts.
Rock Your World
Mudstone
Sandstone
Conglomerate
Click here to watch videos
about sedimentary rocks
and complete a Click-andDrag exercise.
Part 4
Grain by grain – sedimentary rocks
36
Activity
Activity type
4.5Making rocks from body parts
What rocks are formed when dead
plants or animals accumulate?
?
The southern region of
South Australia is famous
for vineyards and wine
production.
South Australia
Wine Region
This region is known as the
limestone coast.
Spencer
Gulf
ADELAIDE
PLAINS
Gulf
St Vincent
Adelaide
Calcium carbonate is quite
reactive, as you will notice in
this activity.
Activity 1: Testing for calcium carbonate
BAROSSA
VALLEY
EDEN
VALLEY
ADELAIDE
HILLS
40 million years ago the
LANGHORNE
McLAREN
whole region was beneath a
CREEK
VALE
shallow sea. Gradually shells
and other marine animals
SOUTHERN
CURRENCY
FLEURIEU
CREEK
collected on the ocean floor.
KANGAROO
As they were buried they
ISLAND
formed into sediments; and
finally into a sedimentary
rock called LIMESTONE
If dead plants and animals are buried in
the sedimentary pile, leaves and branches,
Just like the shells and
shells and bones are commonly preserved
corals they are made from,
as fossils, and sometimes even the soft
limestone is made of a
parts are preserved if they are buried fast
chemical called CALCIUM
enough.
CARBONATE (CaCO3).
.
DOWNLOAD e-NOTEBOOK
What to use:
What to do:
Each GROUP will require:
•limestone, egg shells, small
amount of calcium carbonate, sea
shells, some sand, sandstone
•dissecting microscope, hand lens
•dropper bottle of dilute HCl.
Each STUDENT will require:
•Notebook.
A piece of limestone
Step 1
Test each sample you have with
a few drops of HCl. Record your
observations in your Notebook.
Step 2
Now observe the piece of limestone
under the microscope. Can you
observe individual grains?
Discussion:
This means that the individual
grains often disintegrate and
are no longer visible in the
final rock.
All the samples that fizzed contained
calcium carbonate. Which samples
did not?
Rock Your World
Part 4
Grain by grain – sedimentary rocks
37
Activity 4.5 Making rocks from body parts? Continued
COAL, OIL AND GAS
300 million years ago in what is now Eastern Australia
the climate was warm and wet. The swampy land was
covered with great forests of ancient trees. They shed
their leaves into the mud and over time the dead plant
material compacted in deep layers.
At first it become a mushy black material called PEAT.
peat
Eventually it turned into COAL.
coal
Coal is one of Australia’s biggest
export items. The world mostly uses
coal to make electricity in enormous
power stations. According to the
World Coal Association there are
over 2300 coal-fired power stations
worldwide. Approximately 620 of
these power stations are in China.
Many countries are gradually
reducing the number of these
power stations.
NE
WS
Activity 2: Burning coal
BEFORE
What to use:
Each GROUP will require:
•a small piece of coal
•a crucible (without lid)
•Bunsen burner, tripod, clay triangle
•dissecting microscope, hand lens.
Each STUDENT will require:
•Notebook.
AFTER
What to do:
Step 1
Examine the piece of coal under the
microscope. Describe its appearance.
Step 2
Crush a small quantity into the
crucible and heat with the Bunsen.
Observe its reaction.
Rock Your World
Part 4
Click here to explore some
Australian rocks that have
been made from body parts.
Grain by grain – sedimentary rocks
38
4
Rocks can be broken down through a combination of chemical and physical processes. These processes
are referred to as weathering.
Sediments created through the processes of weathering can be moved from one place to another by a
variety of physical agents, including water, glaciers and wind. This process is called erosion.
Different parts of the landscape are characterised by different sediments because the processes taking
place there contribute specific sediment types. High parts of mountain ranges typically have poorlysorted, angular, coarse sediments that have formed locally. River mouths typically have well-sorted,
rounded, fine sediments that have been transported a long distance from the original site of formation.
Sediments solidify into sedimentary rock in a process called that typically involves compaction and
cementation of sediment particles together. The more compacted and the better cemented (dependent
on cement type) the sedimentary rock, the more resistant this rock is to subsequent weathering and
erosion.
PART
The grains in rocks are called clasts. Any sedimentary rock that is comprised of grains cemented
together is called a clastic rock. The grains in different rocks are characterized by the nature of the
sediments from which the rocks are formed. These, in turn, are characterized by how the sediments
were formed in the first place, and what they have experienced since.
Biogenic rocks are formed from sediments of accumulated body parts. Key examples are coal formed
from plant matter and limestone formed from animal remains.
DOWNLOAD LESSON
OUTCOMES CHECKLIST
Rock Your World
Part 4
Grain by grain – sedimentary rocks
39
Activity 5.1 These rocks are so hot!
Activity 5.2 Regional metamorphosis
Activity 5.3 A tortured history
5
PART
Part 5: Shearing, baking and burying – metamorphic rocks
Rock Your World
Part 5
40
Activity
5.1 These rocks are so hot!
In this activity you will compare
the properties of clay that has
been exposed to different
conditions.
What to use:
Each GROUP will require:
•potter’s clay
•access to a clay firing oven, or
•a crucible with lid, pipe clay
triangle, tripod, Bunsen burner and
matches.
Each STUDENT will require:
•Notebook.
What to do:
Part 1: Drying clay bricks
Step 1
Take some of the damp clay and
shape it into four identical, small
bricks. The size of the bricks will
depend on where you are going to
‘fire’ it: in an oven or in the crucible.
Step 2
Place your four bricks on a shelf in
the lab to dry for a few days.
Part 2: Firing a brick
Step 3
When dry heat two of the bricks in the
?
Activity type
DOWNLOAD e-NOTEBOOK
What happens
when rocks are
heated?
hot oven or in the crucible. If using
the crucible you will need to place
the brick inside the crucible, cover it
with a lid, position it on the pipe clay
triangle and light the Bunsen. Heat
your brick for at least 15 minutes.
Heat it longer if using an oven.
Step 4:
Once the bricks have been heated
sufficiently, allow them to cool to
room temperature.
Part 3: Comparing bricks
Step 5:
Design some tests to assess the
‘rockiness’ of your bricks. What
characteristics do rocks have? How
do they react to water or to pressure?
Are they hard or soft?
Discussion:
1.In your Notebook describe
how the properties of your rock
changed in response to high heat.
2.How does this relate to the formation
of some metamorphic rocks?
Rock Your World
Part 5
Shearing, baking and burying – metamorphic rocks
41
Activity 5.1 These rocks are so hot! Continued
METAMORPHOSE – to change form or appearance
Contact metamorphism
Pr
es
Surrounding
rock
su
re
P
re
This process is similar to BAKING
What happens when hot
magma intrudes into
cooler surrounding rocks?
su
s
re
?
BRICKS
When hot magma intrudes
into cooler rocks it bakes them
in a narrow zone around the
intrusion.
In this zone minerals change
their structure. They might melt
and recrystallise.
Magma
Hot magma is typically intruded at temperatures between 700°C and 1200°C.
Let's find out what this can do to the rock around the intrusion?
MUDSTONE
MIGHT CHANGE TO
HORNFELS
The
CONTACT METAMORPHIC rock is typically denser, harder
Click here to see how baked clay forms
bricks and tiles, and how this relates to the
formation of metamorphic rocks.
and more brittle than the original (parent) rock.
Rock Your World
Part 5
Shearing, baking and burying – metamorphic rocks
42
Activity
Activity type
5.2Regional metamorphosis
N
Thrus
t
Sometimes many layers are formed, one on top of the other. This process can go on for
thousands or even millions of years, forming sediments many kilometres thick. The rocks lower
down experience extremely high pressures and temperatures. Occasionally these rock layers
are tipped onto their side, providing an indication of how thick the original sediments were.
DOWNLOAD e-NOTEBOOK
Moin
e
Scotland has some spectacular scenery, but its geology
is remarkable for displaying a metamorphic gradient.
Buchen
Zones
ul
t
Inverness
Gr
ea
tG
le
n
Fa
Aberdeen
Youngest rocks buried less deep
Moiniam
Oldest rocks buried the deepest
h
lig
gh
Hi
u
o
tB
ry
a
nd
ult
Fa
0
Area investigated
by Barrow
Scale, km
50
Simplified map of the Scottish
Highlands showing the main
metamorphic Precambrian units
which decrease in age from
northwest to southeast (from
Turner, 1968)
In north Scotland, layers of buried sediment have been
tipped on their side.
Today, if we travel from east to west, we see rocks that have
been buried deeper and deeper in the metamorphic pile.
This gives us an idea of how incredibly deep some of these
sediments were buried.
Refer to a map of Scotland to estimate how deep these
sediments were when they were originally horizontal.
?
What
happens
when
rocks are
progressively
buried because
other rocks are
layered on top of them?
Rock Your World
Part 5
Shearing, baking and burying – metamorphic rocks
43
Activity 5.2 Regional metamorphosis Continued
MARBLE is a metamorphic rock that has experienced both immense
heat and pressure. It is formed from the parent rock, limestone.
Are the new rocks made
from the same chemicals?
?
What to use:
Each GROUP will require:
•samples of limestone and marble
•dilute hydrochoric (0.5M) acid in a
dropper bottle.
Each STUDENT will require:
•Notebook.
What to do:
Use the acid test you have conducted
before to test whether marble has a
similar chemical composition to its
parent rock; limestone.
Discussion:
In your Notebook describe whether
marble responded in the same way to
the acid test.
What can you conclude from this?
A piece of marble
Click here to learn how a sediment became
a famous sculpture through the process of
metamorphosis.
Rock Your World
Part 5
Shearing, baking and burying – metamorphic rocks
44
Activity
?
Activity type
5.3A tortured history
What does
extreme heat
and pressure do
to rocks?
Most metamorphic rocks have experienced high
temperatures and pressures.
METAMORPHIC ROCKS often look very
different to their parent rock.
This might simply be because they have been buried
very deep within the Earth’s crust, where it is very hot.
This process can occur on enormous scales, producing
metamorphic formations that are tens of kilometres
deep.
Eventually geological processes, such as weathering and
erosion, expose these rocks at the surface once again.
MUDSTONE changes to SLATE
LIMESTONE changes to MARBLE
Enormous layers
of rock might
be buried many
kilometres below
the surface, and be
changed by heat
and pressure.
SANDSTONE changes to QUARTZITE
The metamorphic rock is typically harder
and more brittle than the original
(parent) rock. It might appear foliated
(consisting of thin sheets) – e.g. slate,
gneiss, schist, or non-foliated – e.g.
marble, quartzite, hornfels.
Rock Your World
Part 5
Shearing, baking and burying – metamorphic rocks
45
Activity 5.3 A tortured history Continued
?
If shale (or mudstone) is
metamorphosed under different
pressures or temperatures, will it make
different metamorphic rocks?
Increasing pressure
Increasing temperature
Shale
Hornfels
Low
Grade
Slate
Schist
Incr
eas
ing
met
amo
rph
ic g
Gneiss
Migmatite
rad
e
High Grade
All of these
different
rocks started
as mudstone
(shale) a
sedimentary
rock, but
they end up
as different
metamorphic
rocks
because they
experience
different
conditions
of heat and
pressure.
A metamorphic rock
forms when any rock
is exposed to very
high temperatures or
pressures, or both.
The type of rock
formed depends on the
combination of pressure
and temperature.
Where do rocks experience
these?
What is the difference
between a metamorphic
rock and an igneous rock?
Click here to explore
how the rocks
change the deeper
they are buried.
Blueschist
Rock Your World
Part 5
Shearing, baking and burying – metamorphic rocks
46
Contact metamorphism (increased temperature alone) occurs when hot magma is intruded nearby and
it bakes shale into hornfels.
Regional or burial metamorphism occurs when sediments are buried deep underground and subjected
to increased temperature and pressure.
Shale progressively changes into slate, schist and gneiss.
Sandstone changes into quartzite.
Limestone changes into marble.
The metamorphic rock is typically harder and more brittle than the original (parent) rock. It might appear
foliated (consisting of thin sheets) – e.g. slate, gneiss, schist, or non-foliated – e.g. marble, quartzite,
hornfels.
5
PART
Different metamorphic rocks can form under a range of different conditions of heat and pressure.
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OUTCOMES CHECKLIST
Rock Your World
Part 5
Shearing, baking and burying – metamorphic rocks
47
Activity 6.1
Activity 6.2
Activity 6.3
Activity 6.4
Activity 6.5
Activity 6.6
Activity 6.7
Rocks into rocks
On the level
How do fossils form?
Is this the same as that?
Relative geological time
How long does it take?
Forming landforms
6
PART
Part 6: The rock cycle
World PART
Part 66
ROCK Rock
YOURYour
WORLD
48
Activity
Activity type
6.1 Rocks into rocks
?
DOWNLOAD e-NOTEBOOK
The ROCK CYCLE shows how SEDIMENTARY, IGNEOUS and METAMORPHIC rock
processes are related to each other. It allows us to integrate all of the ideas we have learned about
rocks and minerals so far!
Where do rocks
come from and
where do they go?
Rock Your World
Part 6
The rock cycle
49
Activity 6.1 Rocks into rocks Continued
Rocks and minerals are continuously formed and broken down as part of the Rock Cycle. Let’s re-visit some of these processes.
SEDIMENTARY PROCESSES
•sediments accumulate
•sediments undergo compaction and cementation to
form rock
IGNEOUS PROCESSES
•molten rock called magma cools slowly
underground to form plutonic rocks with large
crystals
•molten rock called lava erupts on Earth’s surface
to form volcanic rocks with small crystals
METAMORPHIC PROCESSES
•rocks subjected to high heat and/or pressure change in
texture to have a foliated (layered) appearance (e.g. slate,
gneiss, schist) or a non-foliated appearance (e.g. marble,
quartzite, hornfels)
Click here to test
your knowledge of
the Rock Cycle.
Rock Your World
Part 6
The rock cycle
50
Activity 6.1 Rocks into rocks Continued
Modelling the rock cycle
In this activity you will compare the properties of wax crayon that has been
exposed to different conditions.
What to use:
Each GROUP will require:
•wax crayons in 3 contrasting
colours
•sharp knife or grater (or pencil
sharpener – see below)
•aluminium foil (or metal cupcake
cases)
•very hot water
•rolling pin or heavy book
•candle
•iced water
•kitchen paper.
What to do:
Step 1
Grate or chop the crayons into small
pieces, keeping the colours separate.
Step 2
Sprinkle a layer of each colour crayon
into a small piece of tin foil.
Step 3
Fold up the foil and press down on it
with great pressure. You might want
to slip it into your shoe and walk on
it for ten minutes. Open the foil and
observe any changes.
Step 4
Re-wrap your squished crayon
(sedimentary rock) and heat it by
dunking it in very hot water for a
few moments, then squish it some
more. You could also use other
metamorphic crayon-rocks or
igneous crayon-rocks to make your
metamorphic rock.
Step 5
Re-wrap your heated, squished
“metamorphic rock”. This time
dunk it in the very hot water for
long enough for the crayon to melt
completely. Alternatively, briefly
hold your foil packet in a candle
flame which will melt your crayon
more quickly.
Discussion
In your Notebook answer the
following questions.
1.How was weathering and erosion
modelled in this activity?
2.Which part of the activity modelled
the laying down of sediments,
and then the pressure that creates
sedimentary rocks?
3.How did the model represent the
heat and pressure that creates
metamorphic rocks?
4.How was the formation of igneous
rocks modelled in this activity?
Rock Your World
Part 6
The rock cycle
51
Activity
Activity type
6.2On the level
Activity 1: Making sediments
What to use:
How do we figure out which
sediment was deposited first and
which ones were deposited later?
Each GROUP will require:
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SEDIMENTARY ROCKS
Sediments settle out in layers. This
might be happening in an ocean,
a shallow sea or river system.
•1.25 litre PET bottle with lid
•pebbles about 10mm in size
•granules about 4mm in size
•sand about 1mm in size.
Each STUDENT will require:
•Notebook.
What to do:
Step 1
Fill 1.25 litre PET bottle half full with
water.
Law 1: The oldest sediments are on the bottom
Sedimentary layers are deposited in a time sequence, with oldest on the
bottom and youngest on the top.
Step 2
Add a handful of one of the
sediments to your bottle.
Step 3
Add a handful of a different sediment
to your bottle.
Step 4
Add a handful of the third sediment
to your bottle.
Step 5
Add further handfuls of different
sediments to your bottle.
Make a note of any things you notice
during the settling process in your
Notebook. Include a drawing or
photo of your sediments.
Discussion:
1.Which is the oldest sediment (first
deposited) in your bottle?
2.Did each of the sediments settle
out evenly in your bottle?
Law 2: The sediments are deposited horizontally
If undisturbed the layers settle out horizontally.
Rock Your World
Part 6
The rock cycle
52
Activity 6.2 On the level Continued
Activity 2: Graded bedding
What to do:
Step 1
Fill 1.25 litre PET bottle half full with
water.
Step 2
Mix some pebbles, granules and
sand together. Add a handful of the
mixed sediment to your bottle.
Step 3
Let the sediment settle. Then add a
second handful of mixed sediment to
your bottle.
Step 4
Add a few more handfuls of mixed
sediment, waiting each time for the
sediment to settle.
Step 5
Include a drawing or photo in your
Notebook of your sediments.
GRADED BEDDING occurs when sediments settle out with heavy
particles at the bottom and finer particles towards the top.
Sometimes multiple beds can settle out in a series of separate
storm events.
Graded Bedding
Discussion:
Fine
1.The pattern produced in this experiment was different to the one produced
in Activity 1. How was it different?
Coarse
2.How might a pattern like this one be produced in real life, for example in a
shallow sea with a large river flowing into it?
Rock Your World
Part 6
The rock cycle
53
Activity
Activity type
6.3How do fossils form?
A FOSSIL is the trace or remains of an
organism that lived long ago, most commonly
preserved in sedimentary rock. Fossils are found
in successive beds until they become extinct.
?
What are
fossils
and how
do they form?
Some fossils are small and seem insignificant.
Some fossils are large and spectacular
FOSSILS ARE USEFUL TO SCIENTISTS IN TWO
WAYS.
They tell us about what life was like in prehistoric times.
They also help geologists identify different rock layers, or stata.
By identifying specific fossils, they can match up rock types and
strata in different parts of the world.
Click here to explore
how fossils form.
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Part 6
The rock cycle
54
Activity
Activity type
6.4Is this the same as that?
Can we use fossils to figure
out which sediments were
deposited first and which ones
were deposited later?
DOWNLOAD e-NOTEBOOK
Sandstone cliffs near Sydney
?
Rock layers above the platform near
Depot Beach, NSW.
Cliffs containing layers of sandstone can be found all down the south
coast of NSW, from Sydney to Ulladulla.
Many of the layers look the same, but how could we tell if they
belonged to the same formation?
Often geologists identify layers of sedimentary rock by the fossils they
contain.
The study of rock layers is called STRATIGRAPHY.
In the early 19th century geologists noticed that rock layers in different
parts of the world could be correlated and matched because they
contained the same fossils. This was at a time when they didn’t fully
understand what fossils were. They used the pattern of fossils in different
rock strata to identify their relative ages.
Relative dating tells scientists if a rock layer is “older” or “younger” than
another. This would also mean that fossils found in the deepest layer of
rocks in an area would represent the oldest forms of life in that particular
rock formation.
What to do:
Learn how fossils are used to map the stratigraphy of different
sedimentary rock beds by completing the tasks in Activity sheet 6.4
Stratigraphy and your e-Notebook.
Rock Your World
Part 6
The rock cycle
55
Activity
Activity type
6.5Relative geological time
A LONG STORY IN THE ROCKS
Many things happen to rock beds once they are laid down, making it difficult to interpret
their history.
But in some places the beds remain lying as they first did. One of the most spectacular
examples in the world is the Grand Canyon, in Colorado, USA
270 million years
275 million years
340 million years
The Grand Canyon, in the USA, is one of the world’s most famous tourist destinations. The layer cake structure
makes the major ideas about sedimentary rocks easy to see.
These rock layers lie as they were
first formed.
They are horizontal.
The oldest layers are at the
bottom.
The fossils found in the different
layers tell the story of evolution
over a period of 100 million years.
The layers you see here are
around 1km thick. On average,
how much sediment was
deposited per year. You may be
surprised at the answer.
Rock Your World
Part 6
The rock cycle
56
Activity 6.5 Relative geological time Continued
GEOLOGIC TIME SCALE: 650 MILLION YEARS AGO TO THE PRESENT
1.8
50
Era
Neogene
Paleogene
Events
Evolution of humans
Mammals diversify
Extinction of dinosaurs
100
Cretaceous
Mesozoic
150
Jurassic
Permian
Major extinctions
Reptiles diversify
Carboniferous
550
600
650
Late Proterozoic
500
Dinosaurs diversify
First mammals
First dinosaurs
300
450
First birds
Triassic
250
350
First primates
First flowering plants
200
400
Click here to
explore the
Grand Canyon
and journey
back in time.
Period
Quaternary
Cenozoic
0
Paleozoic
Using our understanding of how
sedimentary rocks are laid down, and by
studying the fossils they contain, geologists
have been able to devise a geological time
scale. This is used to identify and sequence
any rock strata that are discovered. This is
known as the relative geological time scale.
Once the
sequence was
understood,
scientists used
radiometric dating
to put dates to the
different periods
represented.
Radiometric dating
uses the decay
of radioactive
elements in the
rocks to determine
their age.
Devonian
First Reptiles
Scale Trees
Seed Ferns
First amphinians
Jawed fishes diversify
Silurian
First vascular land plants
Ordoviciar
Sudden diversification of
metazoan families
Cambrain
First fishes
First chordates
First skeletal elements
First soft-bodied metazoans
First animal traces
Rock Your World
Part 6
The rock cycle
57
Activity
Activity type
6.6How long does it take?
THESE GEOLOGICAL
PROCESSES TAKE
A LONG, LONG,
LONG TIME…
GEOLOGICAL TIME
IS MEASURED IN
THOUSANDS
OR MILLIONS
OF YEARS.
DOWNLOAD e-NOTEBOOK
Weathering
Erosion
Solidification
Metamorphism
Melting
Compaction
& cementation
Rock Your World
Part 6
The rock cycle
58
Activity 6.6 How long does it take? Continued
Rock Cycle Game
What to use:
Each STUDENT will require:
•Science by Doing Notebook.
Each GROUP will require:
•Rock Cycle Game instructions and dice
•scissors
•sticky tape.
What to do:
Step 1
Set up five stations around the room labelled:• Magma station
• Sediment station
• Igneous rock station
• Metamorphic rock station
• Sedimentary rock station
Step 2
In small groups, cut out, fold and sticky tape
the five dice. Put the completed dice at their
respective stations.
Step 3
Download the e-Notebook or draw up a table like
this one in your Notebook to record the 10 rolls
of the dice.
Dice roll
Time (yrs)
1
200,000
2
400,000
3
600,000
What happened?
Step 4
Individually, choose the station you would
like to begin with. Roll the die to determine if
you stay at that station or move to a different
station. Write your result into your log. Each roll
of the die is equivalent to 200,000 years.
Step 5
After 10 rolls of the dice you have experienced 2
million years of the geological rock cycle.
Step 6
Draw a rock cycle diagram in your Notebook and
show the pathway your rock took. Compare your
rock’s history with other students in your group.
Discussion:
1.In what ways did the rock histories differ?
2.In which part of the rock cycle did your rock
spend the most time?
3.Which part/s of the rock cycle did your rock miss?
Rock Your World
Part 6
The rock cycle
59
Activity 6.6 How long does it take? Continued
?
Two or more periods
comprise a geological era.
Two or more eras form an
eon, the largest division of
geologic time.
System/Period
Erathem/Era
Eonothem/Eon
Quaternary
Micocene
Neogene
~129.4
~132.9
~139.8
~145.0
Hauterivian
Valanginian
Berriasian
100.5
Cenomonain
~125.0
93.9
Turonian
Barremain
89.8±0.3
Coniacian
~113.0
86.3±0.5
Santonian
Paleogene
Upper
Aptain
83.6±0.2
Campanian
Eocene
Albain
37.8
41.2
47.8
56.0
59.2
61.60
66.00
72.1±0.2
33.9
Rupelian
Priabonian
Bartonian
Lutetian
Ypresian
Thanetian
Selandrian
Danian
Maastrichtian
28.1
23.03
5.333
7.246
11.63
13.82
15.97
20.44
3.600
Pleistocene Pliocene
Paleocene
Series/Epoch
Oligocene
The period is the basic unit
of geological time in which a
single type of rock system is
formed.
Holocene
divided into
epochs.
Messinian
Tortonian
Serravallian
Langhian
Burdigalian
Aquitanian
Chattian
Stage/Age
How has the Earth
changed over
Geological Time?
Zanclean
periods are
Middle
Some
Piacenzian
0.126
0.781
1.80
2.58
Calabrian
DEFINITION:
Gelasian
0.0117
Upper
Numerical
Age (Ma)
present
The International Commission on Stratigraphy provides the most up-todate version of the Geological Time Scale for use worldwide.
The ‘Period’ term (e.g. Jurassic – like in Jurassic Park) is most widely used
by geologists.
Lower
Cretaceous
Cenozoic
Mesozoic
Phanerozoic
Click here to see the whole geological time scale and find out how geology helps us.
Rock Your World
Part 6
The rock cycle
60
Activity
Activity type
6.7 Forming landforms
?
How do these
processes produce the
landforms we see around
us?
Once upon a time the Australian continent had mighty
mountain ranges. Today the Australian landscapes show
the signs of millions of years of erosion.
THREE DISTINCTIVE AUSTRALIAN LANDFORMS. Where are they, and which is which?
Beds of limestone formed from layers of broken down coral reefs. These were worn away by
the ocean waves over millions of years.
Great beds of sandstone have been worn away by dry, desert winds, exposing dramatic
features surrounded by sandy desert.
Click here and match these landforms with
the processes that made them.
A high mountain range was worn down by glaciers as they slowly ground their way down to
the sea, leaving valleys behind.
Rock Your World
Part 6
The rock cycle
61
Sediments accumulate in horizontal layers with the oldest sediment on the bottom and the youngest
layer on the top. Graded bedding occurs when sediments settle out with heavy particles at the bottom
and finer particles towards the top within the one layer. This typically occurs during a storm event when
sediments of all sizes are transported and deposited.
A fossil is the trace or remains of an organism that lived long ago, most commonly preserved in
sedimentary rock. Fossils are found in successive layers until that organism became extinct. Fossils are
useful to us because:• They tell us about what life was like in prehistoric times
• They help us identify different rock layers and match up with rock layers in different parts of the world.
The study of rock layers is called stratigraphy. Rock layers in different parts of the world can be
correlated and matched because they contain the same fossils. This relative dating tells scientists if a
rock layer is older or younger than another. Using our understanding of how sedimentary rocks are laid
down, and by studying the fossils they contain, geologists have been able to devise a relative geological
time scale. This divides time up into periods, eras, eons and epochs. Scientists have calculated the actual
ages of rock layers using radiometric dating which uses the decay of radioactive elements in the rocks to
determine their age.
6
Australia has many iconic landforms (e.g. Uluru, Snowy Mountains, 12 Apostles), each of which has been
influenced by geological processes like weathering, erosion or deposition.
PART
The Rock Cycle describes the slow, continual recycling of rocks and sediments in the lithosphere. It
shows how sediments can be formed into sedimentary rocks, then possibly metamorphic rock, magma
and then igneous rock or any combination of the processes.
DOWNLOAD LESSON
OUTCOMES CHECKLIST
Rock Your World
Part 6
The rock cycle
62
1
Rocks are more than just small features that are found occasionally lying on the ground. They are the
fundamental part of the crust on which we live.
There are different types of rock, which form under different conditions and have different geological
histories.
The Earth consists of several distinct layers, including the crust, mantle, outer core, and inner core.
A combination of very high temperatures and pressures produce conditions in the mantle and core that
are quite different to those found at the Earth’s surface. As the surface is approached the pressure and
temperature drops until you reach the crust where the rock is relatively cool and solid.
Although most rocks appear to be endlessly durable they have a life story. Rocks are broken down and
rebuilt over very long periods of time.
Rock Your World
PART
All rocks on Earth can be broadly categorised into three groups; sedimentary, igneous and
metamorphic. These groups of rocks have different characteristics that relate to the manner in which
they are formed.
Part 1
Rocks – part of the Earth System
63
We identify objects and separate them from others using diagnostic properties.
Geologists use diagnostic tests to help identify minerals. The hardness test is a measure from 1 (soft like
talc) to 10 (hard like diamond). Cleavage describes how the mineral splits (cubic, octahedral, etc.). Streak
is the colour when the mineral is scratched across a white tile. Colour is the colour of the mineral and
lustre is how light shines off the mineral.
Each rock type is always comprised of the same rock forming minerals. Identification of these minerals
can be used to identify the rock.
Minerals are typically the raw materials that many of our material items (e.g. cars, telephones) are made
of, or the energy supplies (e.g. coal, oil) that we use to make them operate.
The scientists that find the minerals we need for our technological society include:Geophysicists – study the physics of the Earth (gravitational, magnetic, electrical, and seismic
properties).
Geochemists – study the chemistry of rocks, soils and water bodies.
Geologists – collect rock and soil samples to test for minerals.
Minerals that seem to be most valuable, such as gold and diamonds, do not actually account for the
majority of Australia’s export income. Iron ore and coal are our main export earners.
Rock Your World
Part 2
2
PART
Minerals are not rocks. Minerals are the pure substances, or chemicals, that rocks are made from. Most
rocks contain a mixture of several minerals, as individual crystals and grains.
Minerals – ingredients in the rock recipe
64
Plutonic igneous rocks form when molten rock called magma is intruded below the Earth surface. The
magma cools slowly because it is insulated by the enclosing rock, and there is time for large crystals to
grow forming a coarse-grained rock. An example of a plutonic igneous rock is granite.
3
PART
Volcanic igneous rocks form when molten rock called lava is erupted at the Earth surface. The lava cools
rapidly because there is a large temperature contrast between the lava and the air. This quenched rock
forms very small crystals resulting in a fine-grained rock. An example of a volcanic igneous rock is basalt.
Rock Your World
Part 3
Rocks from the earth’s furnace – igneous rocks
65
4
Rocks can be broken down through a combination of chemical and physical processes. These processes
are referred to as weathering.
Sediments created through the processes of weathering can be moved from one place to another by a
variety of physical agents, including water, glaciers and wind. This process is called erosion.
Different parts of the landscape are characterised by different sediments because the processes taking
place there contribute specific sediment types. High parts of mountain ranges typically have poorlysorted, angular, coarse sediments that have formed locally. River mouths typically have well-sorted,
rounded, fine sediments that have been transported a long distance from the original site of formation.
Sediments solidify into sedimentary rock in a process called that typically involves compaction and
cementation of sediment particles together. The more compacted and the better cemented (dependent
on cement type) the sedimentary rock, the more resistant this rock is to subsequent weathering and
erosion.
PART
The grains in rocks are called clasts. Any sedimentary rock that is comprised of grains cemented
together is called a clastic rock. The grains in different rocks are characterized by the nature of the
sediments from which the rocks are formed. These, in turn, are characterized by how the sediments
were formed in the first place, and what they have experienced since.
Biogenic rocks are formed from sediments of accumulated body parts. Key examples are coal formed
from plant matter and limestone formed from animal remains.
Rock Your World
Part 4
Grain by grain – sedimentary rocks
66
Contact metamorphism (increased temperature alone) occurs when hot magma is intruded nearby and
it bakes shale into hornfels.
Regional or burial metamorphism occurs when sediments are buried deep underground and subjected
to increased temperature and pressure.
Shale progressively changes into slate, schist and gneiss.
Sandstone changes into quartzite.
Limestone changes into marble.
The metamorphic rock is typically harder and more brittle than the original (parent) rock. It might appear
foliated (consisting of thin sheets) – e.g. slate, gneiss, schist, or non-foliated – e.g. marble, quartzite,
hornfels.
Rock Your World
Part 5
5
PART
Different metamorphic rocks can form under a range of different conditions of heat and pressure.
Shearing, baking and burying – metamorphic rocks
67
Sediments accumulate in horizontal layers with the oldest sediment on the bottom and the youngest
layer on the top. Graded bedding occurs when sediments settle out with heavy particles at the bottom
and finer particles towards the top within the one layer. This typically occurs during a storm event when
sediments of all sizes are transported and deposited.
A fossil is the trace or remains of an organism that lived long ago, most commonly preserved in
sedimentary rock. Fossils are found in successive layers until that organism became extinct. Fossils are
useful to us because:• They tell us about what life was like in prehistoric times
• They help us identify different rock layers and match up with rock layers in different parts of the world.
The study of rock layers is called stratigraphy. Rock layers in different parts of the world can be
correlated and matched because they contain the same fossils. This relative dating tells scientists if a
rock layer is older or younger than another. Using our understanding of how sedimentary rocks are laid
down, and by studying the fossils they contain, geologists have been able to devise a relative geological
time scale. This divides time up into periods, eras, eons and epochs. Scientists have calculated the actual
ages of rock layers using radiometric dating which uses the decay of radioactive elements in the rocks to
determine their age.
6
Australian has many iconic landforms (e.g. Uluru, Snowy Mountains, 12 Apostles), each of which has
been influenced by geological processes like weathering, erosion or deposition.
Rock Your World
PART
The Rock Cycle describes the slow, continual recycling of rocks and sediments in the lithosphere. It
shows how sediments can be formed into sedimentary rocks, then possibly metamorphic rock, magma
and then igneous rock or any combination of the processes.
Part 6
The rock cycle
68
Glossary
Term
Description
Basalt
An igneous rock derived from molten lava that has flowed out onto the surface of the Earth.
Biogenic
A rock or mineral formed from any dead organisms.
Calcite
Crystal of calcium carbonate.
Calcium carbonate
A compound found in minerals such as calcite and rocks such as limestone and marble.
Cement
A substance that solidifies and hardens used in building. Made from limestone.
Cementation
The gluing together of rock particles (clasts) by the precipitation of mineral matter in the pore spaces.
Clastic
A type of rock made from grains, or clasts, cemented together.
Clasts
The grains found in sedimentary rocks.
Cleavage
The typical shape of the crystals of a mineral when it is broken.
Coal
A mineral, consisting mostly of carbon, formed from partially decomposed plants 100s of millions of years ago.
Compaction
The process by which a sediment is squeezed together by the weight of overlying sediments.
Concrete
An aggregrate of pebbles bonded together by cement.
Conglomerate
A sedimentary rock derived from a mix of fine sediments, pebbles and boulders.
Contact metamorphism
Metamorphism (change) caused by intrusion of hot magma.
Core
The central layer of the Earth, mostly comprised of iron and nickel.
Crust
The surface layer of the Earth, comprised of rock.
Crystalline
Formed from crystals of a pure substance.
Deposition
Wind, ice and water transport eroded sediment to a distant location where it is deposited.
Diagnostic property
A property used to identify a particular type of rock or mineral.
Eon
Two or more eras form an eon. It is the largest unit of geological time.
Epoch
A division of geological time that is a subdivision of a period.
Era
A span of geological time marked by a beginning and an end. E.g. Cenozoic era 66 million years ago to present day.
Erosion
The movement of sediments from one place to another through agents such as wind and water.
Extrusive
Extrusive rock is also called volcanic rock. It is rock formed from quickly cooling lava that has erupted at the Earth's surface.
Foliated
Consisting of thin sheets.
Fossil
The remains, or impression, of dead organisms preserved in a layer of sedimentary rock.
Fracture
The shape and texture of the surface of a crystal when it is fractured.
Rock Your World
Glossary
69
Glossary
Term
Description
Geochemist
A scientist who studies the chemistry of rocks, minerals or mining.
Geologist
A scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes that shape it.
Geophysicist
A scientist who studies physical processes and structure of the Earth's crust, often related to mining.
Glass
A material produced from Silicon dioxide, which is molded into particular shapes rather than forming pure crystals.
Graded sediment
A sediment where different sized particles have settled out separately in distinct layers.
Grain comparator
A device for analysing the size and shape of grains found in sediments or a sedimentary rock.
Hardness scale
A scale, from 1 to 10, used to describe the hardness of different minerals. Diamond has a hardness of 10 and talc has a hardness of 1.
Hematite
A mineral composed of one form of iron oxide. Conducts electricity and is sometimes magnetic.
Hornfels
A metamorphic rock formed by the contact between a mudstone or shale and a hot igneous intrusion.
Igneous
A rock derived from molten rock.
Intrusive
Intrusive rock is also called plutonic rock. It is rock that forms from slowly cooled magma at depth.
Lava
Molten rock that erupts on Earth's surface.
Limestone
A type of sedimentary rock formed from broken down shelled marine organisms or coral.
Lithosphere
The rigid outer part of the Earth consisting of the crust and upper mantle.
Lustre
The way that light interacts with the surface of a rock or mineral, giving it a certain appearance.
Magma
Molten rock formed below the Earth's surface.
Magnetism
One of the forces of nature that can act through a vacuum and at a distance.
Mantle
The largest layer of the Earth lying below the crust, comprised of very hot rock.
Melting
When rock is heated and it turns to magma.
Metamorphic
A type of rock that has been subjected to high temperature and/or pressure.
Mineral
A naturally occurring chemical compound, usually crystalline in form.
Moh's scale of hardness
Friedrich Moh created a scale of hardness describing numerically the hardness of minerals from soft (1) to hard (10).
Mudstone
A type of sedimentary rock formed from fine, silty sediments.
Onion skin weathering
Occurs in regions which experience big differences between day and night temperatures. Rocks expand and contract and the outer layers flake off
creating rounded rocks called tors.
Ore
A naturally occurring solid material from which a metal or valuable mineral can be extracted profitably.
Palaeontologist
A scientist who studies fossils.
Rock Your World
Glossary
70
Glossary
Term
Description
Parent rock
The original rock that a metamorphic rock, or a sediment, may have formed from.
Peat
Deposits of partially decayed plant material, usually forming in wet, boggy environments.
Period
Geological time unit given to a specific stratigraphic sequence of rock. E.g. Carboniferous period (359 - 299 mya) was a time of low sea levels when
much algae,zooplankton and plant life was transformed into coal, oil and natural gas.
Plutonic
The solidification of rock from magma at considerable depth underground.
Quartz
A hard, glassy mineral, composed mainly of silicon dioxide.
Radioactivity
Particles and rays that come from some unstable atoms.
Radiometric dating
Determining the age of rocks or minerals using the decay of radioactive elements they contain.
Regional metamorphism
Metamorphism (change) caused by increased heat and pressure due to burial.
Regolith
The layer of loose material including dust, soil and broken rock, that covers the solid bedrock below.
Relative dating
The science of determining the relative order of past events; i.e. which rock layer is older than which.
Rock
The basic building block of the Earth's crust and mantle. Usually a collection of minerals joined together in some way.
Rock cycle
A model that explains the processes involved in the breaking down and creation of different types of rocks.
Sandstone
A rock derived from deposits of sand.
Sediment
Layers of broken down rock and soil.
Sedimentary
A rock made from sediments.
Seismic
Referring to vibrations in the Earth's crust, often associated with earthquakes.
Solidification
When molten rock cools to form rock.
Steel
A form of iron hardened by the addition of carbon.
Stratigraphy
A branch of geology that studies rock layers, how they form and can be dated.
Streak
The colour of the powder of a mineral that has been scraped across a rough, hard surface.
Tor
Rounded boulder.
Trilobite
Ancient hard-shelled arthropod (invertebrate with an exosketeton) that lived on the sea-floor 520 million years ago.
Volcanic
Formed from magma (actually lava) erupted from a volcano.
Vulcanologist
A scientist who studies volcanoes.
Weathering
The wearing down of rocks and minerals through physical or chemical processes.
Rock Your World
Glossary
71
Project Management
Disclaimer
Executive Director: Professor Denis Goodrum, FACE (Australian Academy of Science)
Director of Curriculum Development: Jef Byrne
Web and Digital Co-ordinator: Dr Jen Liu
Education Specialist: Dr Jim Woolnough
Administrative Coordinator: Katie Ryan
Administrative Officer: Kathy Hamilton
The views expressed herein do not necessarily represent the views of the Australian
Government, Department of Education or Education Services Australia.
Authors
The Australian Academy of Science accepts no responsibility for any loss or damage
whatsoever suffered as a result of direct or indirect use or application of any of these
training materials.
This resource was originally written in 2015 by: Dr Leah Moore, Dr Jim Woolnough
and Jef Byrne.
This resource was revised in 2017 by: Jef Byrne.
These materials are intended for education and training only. Every effort is made
to ensure the accuracy of the information presented in these materials. We do not
assume liability for the accuracy or completeness of the information contained
within.
© Australian Academy of Science, 2017.
Funding Acknowledgement
• You may freely use this resource for non-commercial educational purposes but
please acknowledge the resource and the Australian Academy of Science as the
source. Please note there are third party items in this resource that are outlined. To
use these items other than in this resource you must obtain permission from the
third party owners.
Science by Doing is supported by the Australian Government.
• Under no circumstances may copies be sold in any form.
Science by Doing would like to thank Spinks and Suns for the design and
development of this resource.
ISBN 978 0 85847 525 0
Published by the Australian Academy of Science
GPO Box 783
Canberra ACT 2601
Telephone: 02 62019400
Fax: 02 6201 9494
www.science.org.au
Click here for a full version of unit acknowledgements and sources or logon to
www.sciencebydoing.edu.au
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