3
WORK AND EXPERIMENTATION TECHNIQUES
In this section, you’ll find out about interesting methods and
procedures for handling instruments and for carrying out your
study. These will help you learn about your surroundings and the
things found there. With these techniques, you will be able to put
into practice what you have learnt in this unit.
FINAL TASK
We will guide you through the task you have to carry out, and
explain how you should present your results. This final task for the
unit is also available in digital format in
Oxford Investigation.
CONSOLIDATION
This is a double page of activities that relate to the unit content.
There are two highlighted sections:
Read and understand science
and
Study skills.
These consist of a summary, a conceptual map
and a glossary of scientific terms.
62
63
3. Thegeosphere
3
Theenvironmental impactofmineral extraction
FINAL TASK
The textureof rocks
WORK AND EXPERIMENTATION TECHNIQUES
1.
Whichof theobserved rocks ishomogeneous?Howdid you know?
2.
What are themaindifferencesbetween conglomeratesand sandstone?
3.
What typeof igneous rocks aregranite andbasalt?Can youobserveanydifferences in their textures?
4.
Basedon the resultsof this sciencepractical,define in yourownwords thedifferent typesof rocks (igneous,
sedimentaryandmetamorphic).
5.
Whichof the rocksobservedwere formed in theexteriorof theEarth’s crust?And in the interior?
1.
Puteach rock,onebyone,on theslideof thebinocular loupe.Look through theeyepieces
andmove themacrometric screwuntil the rock is sharply focused.
2.
Observe each rock and drawwhat you see for each rock.
3.
Place a rulernext to the rock and,with the help of the loupe,measure the crystals
or fragments that compose the rock.
4.
Do another drawing of each rock observed.
Procedure
Somecharacteristicsof rockscannotbe seenby just lookingat
them. In this sciencepractical,youwill learn touseabinocular
loupe to compare different rocks and distinguish them
according to texture.
Materials
❚
Binocular loupe
❚
Five different rocks, for example,
conglomerate, sandstone,basalt,
granite and gneiss
❚
Ruler
Textureof conglomerate
Textureofgneiss
Textureof sandstone
To analyse the resultsand compare the rocks,use the following tablenext to yourdrawings:
Analysis of results
Nameof rock
Minerals it is
composedof
Sizeof the
components
Typeof rock
...
...
...
...
Follow these steps for your research:
Search for information
❚
Findat least fourdifferentways inwhichmines impact theenvironmentandpeople.Suggest somepossible solutions
to the problems.
❚
Do not trust only one source of information. Check that the answers to your questions are repeated in different
sources.
❚
Make a bibliography of all sources consulted.
Organise the information
❚
Make a tablewith themain impactsof coltanmining.
❚
Write the answers to the questions in the
Research
section.
Obtain conclusionsandverification
❚
As a resultof yourwork, resolve the initialquestions of the Final task.
❚
Verify your answers.
❚
Check that youhave answered all thequestions.
Procedure
The objective of this task is to research
the environmental and social impact of
extracting coltan. You will present your
information in a slideshow presentation
and suggest somemeasures to contribute to solving the
problems.
a)
Whatare thenegativeeffectsofmineralextractionon theenvironment?
b)
What is coltan andwhat it is used for?
c)
Where are themain coltanmines located?Are there any in Spain?
d)
How does the behaviour of the consumer affect the exploitation of
children in coltanmines?What canwe do to help solve this problem?
1. Research
a)
Prepare a slideshow presentation.
b)
Make a list of threeways inwhichwe can contribute to the
sustainablemanagement ofmineral resources.
2. Tasks
❚
Answer thesequestions to evaluate yourwork.
1.
Have you resolved all the questions in the
Research
section?
2.
Have you used reliable sources to find information?
3.
Have you checked that the answerswere repeated in various sources?
4.
What rating, from1 to 5,would you give yourpresentation?
SELF-ASSESSMENT
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3. Thegeosphere
3
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The Earth:origin and composition
33.
Find out the thicknesses of the different layers of
theEarthandorder them from thickest to thinnest.
34.
Make a table to compare the characteristicsof the
continental crust and theoceanic crust.
35.
Were all materials distributed according to their
density from the very beginning? Explain your
answer.
36.
Explainwhy the following statements are true or
false.
a)
The seismic method only allows us to know the
compositionof the Earth’s crust.
b)
The Earth ismadeupof solidmaterials.
c)
The Earth’s crusthas auniform thicknessof50 km.
d)
Denser materials in the geosphere are found on the
Earth’s surface.
e)
The Earth’smantle is located between theMohorovičić
discontinuity and the Lehmanndiscontinuity.
f)
TheEarth’s inner core is solidbecause the temperature is
lower than in theouter core.
37.
The following graph shows how seismic waves
move around the planet.Which seismicwaves are
travelling at a higher speed?Which layers of the
Earthdo theygo through?
Minerals
38.
Whichpropertyofmaterials
does the image show?
Theuseof rocks
53.
Explainwhich rocksprovide the followingbuilding
materials:
54.
Whyarecoalandpetroleumreferredtoasfossilfuels?
55.
What is sandpaper? Explainwhy it is notmade of
fragmentsofgypsumor talc.
56.
Copyand complete the table in yournotebook for
the following rocks: petroleum, chalk, limestone,
clay and coal.
57.
Researchhow concreteandbricksaremade.Make
adiagram.
Extractionofminerals and rocks
58.
Complete the sentences in yournotebook.
a)
The rocks extracted from….. are cut intoblocks.
b)
….. arehorizontal tunnels inundergroundmines.
c)
….. is sediment that is usually extracted in or near large
riverbeds.
59.
Explain themeaningof the terms
deposit
and
mine
.
39.
Describe fourpropertiesofminerals.
40.
Explain if an ice cube and coral used in jewellery
aremineralsornot.
41.
Investigate and then copy and complete the table
in yournotebook.
42.
According to theMohs scale,what is the hardness
of a mineral that scratches orthoclase but is
scratchedbyquartz?
43.
Explain how to distinguish white quartz from
orthoclase,which is the same colour?
44.
Find outwhy the colour and streak of amineral
isn’t always the same.
45.
Findoutwhypyrite isalso referred toas ‘fool’sgold’.
Rocks
46.
Explain the three characteristics that are used to
classify rocks.
47.
Pumice is a rock that floats inwater.Why do you
think this is? Is it a natural or an artificial rock?
Justify your answer.
48.
Copy the following terms in two columns in your
notebook and thenmatch them.
A:
limestone,granite, clay,marble,basalt, chalk
B:
detrital sedimentary, non-detrital sedimentary, plutonic,
volcanic, foliatedmetamorphic,non-foliatedmetamorphic
49.
Are there any rocks which are not composed of
minerals?What typeof rocks are they?
50.
When1kgofgranitewasanalysed inthe laboratory
using different chemical processes they obtained
250gofawhitemineral,300gofanothermineral,
almostblack, and the restwas agreymineral.
a)
What is thenameofeachmineral thatcomposesgranite?
b)
Which mineral corresponds to the grams of minerals
above?
51.
On an excursion,Ana found a rock that contained
a plant fossil that lived on Earthmillions of years
ago.What typeof rockdoyou think itwas?Explain
your answer.
52.
Which rock forms quartzite aftermetamorphism?
What size are thegrainsof theoriginal rock?
60.
Find outwhat a
slag heap
is.What environmental
problemsdo they cause?
61.
Discuss this statement: ‘New generation mobile
telephones aremadeof stone’.
Speed of siesmicwave (km/s)
Depth (km)
0
Moho
Gutenberg Lehmann
Waves S
Mantle
Outer
core
Inner
core
Waves P
0
3
6
9
12
1000 2000 3000 4000 5000 6000
Rock
Use
Objects createdwith it
...
...
...
a)
glass
c)
cement
e)
brick
b)
concrete
d)
lime
f)
tile
STUDY SKILLS
❚
Create your own summary of the unit using
the
Key concepts
. Add any other important
information.
❚
Copy the following diagram in your
notebook and add themissing information
to create a conceptualmapof theunit.
Slowbut sure
InChihuahua,Mexico,giant crystalswere found in the
caveofNaica.Theyaremega-crystalsofselenite(avariety
of gypsum). For years, the Spanish investigator Juan
ManuelGarcía has been studying how fast they grow.
Thanks to a specialmicroscope designed by Japanese
engineers,we now know that these formations grow
at theequivalentofonehairevery100 years.However,
theirgrowthhas stopped in recent yearsdue tomining
activities to extract minerals from the underground
water that themineralsneed togrow.
E
VA
VAN
DEN
B
ERG
NationalGeographic,
November 2011
(Translated and adapted)
a)
What is the textabout?
b)
Can you explain the title?
c)
Whyhave the crystals stoppedgrowing?
d)
Doyou think thegrowthof these formations canbe
observedby anyperson?
e)
Find out about selenite. Explain why water is
essential for its formation.
READANDUNDERSTAND SCIENCE
You can record your
summary and listen
to it asmany times
as you like to revise.
Mineral
Ore
Cassiterite
...
...
Lead
Hematite
...
...
Zinc
Chalcopyrite
...
❚
Createyourown scientificglossary.Define the following terms:
quarry,clast, sedimentarybasin,deposit,discontinuity,
reef,phytoplankton, fossil,gallery,gangue,geosphere,gravel,magma,metamorphism,mineral,ore, rock, sediment,
seismicwave
.Add anyother terms you consider important.
Thegeosphere
layers
isdivided in
is composedof
minerals
rocks
are classifiedby
are classifiedby
...
...
...
CONSOLIDATION
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PRESENTATION
In order to give you an overview of the unit, there’s a large picture
and some questions to stimulate previous knowledge. This will
help you relate the unit content to some aspects of your daily life,
and show you how the content can be applied to real life. We
recommend that you answer the questions throughout the unit.
There’s also a
final task
which we will prepare you for as you go
through the unit. The same task is also presented in digital format
in
Oxford Investigation.
The link near the picture will take you
to a short introductory video.
You have a
DUAL BOOK
:
a printed book and its electronic version,
which includes resources for you to use together with the unit. In
order to access the electronic version, use the code in the book
and follow the instructions. You will be able to work either online
or offline.
Digital icon:
This icon reminds you that there is a digital
version of your DUAL BOOK, Oxford Investigation. In this
version,youwill find reading comprehensionworksheets,animated
videos, videos, relevant web links and interactive versions of all the
course book activities.
CONTENT DEVELOPMENT
On these pages, there is an explanation of the material you are
going to study. The activities are categorised based on Bloom’s
taxonomy, in order to develop critical thinking skills. There is a brief
summary of the content
(key concepts)
at the end of each lesson
in the margin.
O
Understand theoriginsof theEarth.
O
Differentiatebetween the layers
of thegeosphere anddescribe
the characteristicsof thematerials
they are composedof.
O
Identifyminerals and their
properties.
O
Identify and classify rocks.
O
Evaluate the importanceof
minerals and rocks for humans
andofmanaging these resources
in a sustainableway.
O
Carryout a research task.
3
YOUWILLLEARNTO…
THE GEOSPHERE
Whatdo you think theEarth’s interior is like?Couldwe travel
there
?
Whatqualitiesmakesomemineralssoappreciatedbypeople
?
Rocksareused inconstruction.Whatelsecan rocksbeused for
?
Whydo you think it’s important tomanagemineral resources
responsibly
?
Whatcan you see in thephoto
?Wheredo you think it is?
Final
task
45
3. Thegeosphere
Theenvironmental impactofmineralextraction
Minerals are extremely useful to us.Minerals have great economic
value and are often obtained without thinking about the
environmental and social impact of their extraction.
Mineral extraction in third world countries is directly related to
smuggling, poorwork conditions and child labour.
One of themost sought afterminerals is coltan,which is used to
make parts of electronic devices. In this unit, youwill research this
mineral and create a slideshow presentation.
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3. Thegeosphere
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1.
THE EARTH:ORIGINANDCOMPOSITION
TheEarth is the thirdclosestplanet to theSun. It isa rockyplanetand theonlyplanet
thathaswater inall three states.Asa result, it is theonlyplanetwith living things.
The Earth can be divided into four layers: the
geosphere
or solid layer; the
atmosphere
orgaseous layer; the
hydrosphere
which containswater inall three
states and the
biosphere
where life exists.
1.1.
Theoriginof the Earth
According to the latest studies, 4600
million years ago the Sun formed from
chemical reactions in a giant cloud of
dust and gas, called a nebula. In the
cloud of matter that surrounded the
Sun, smaller dust particles collided and
grew in size.Thisprocess,which formed
the planets, is called
accretion of
planetesimals
.
For 1billion years the Earth was
incredibly hot. Due to the immense
heat stored in theEarth’s interior, there
was a lot of volcanic activity during
thisperiod.As the Earth’s temperature
decreased, gravity pushed denser
materials, such as iron, towards the
Earth’s interior. Less densematerials,
such as oxygen, moved towards the
Earth’s surface. This process is called
density differentiation
.As the Earth
cooled, itmaintained this structure of
layers.
1.2.
Studying the Earth’s interior
The Earth is 6370 km at the Equator butwe only have direct knowledge of the
most superficial layersunder theEarth’s surface.Minesordrillholes
1
haveallowed
us to reachdepthsof8-12 km.
Tounderstand thecompositionof theEarth’s interior, scientistshave touse indirect
methods.Themostcommonmethod is thestudyofearthquakescalled the
seismic
method
. Thismethod analyses theenergygeneratedby earthquakes.
When you throw a pebble intowater, thewatermoves across the surface in
all directions inwaves. Similarly,when an earthquake occurs, themovement
generateswavesof energy that travel to the interiorof the Earth, called
seismic
waves
. Thesewaves can be detected by an apparatus called a
seismograph
.
This shows us that the speed of thewaves vary as they pass from one layer to
another.
The studyof thedataobtained from seismographshasallowed scientists todeduce
the compositionof the Earth’s interior. This informationhasbeenused to create a
modelof the Earth’s structure. It isdivided into three layers: the crust,mantle and
core.
1.3.
Layersof thegeosphere
The solid part of the Earth is divided into different layers separated by areas
knownas
discontinuities
. In theseareas the seismicwaves change velocity.This
allowsus to identifywhere each layer ends.
1.3.1.
The crust
This is a thin layer covering the Earth’s surface and it
is the leastdense layer. Thereare two typesof crust:
❚
The
continental crust
ismore than 1billion years
old and it is between 10 and 70 km thick. The
continental shelf, continents and islands are allpart
of the continental crust. It is composed of rocks
such asgranite, clay and slate.
❚
The
oceanic crust
is 200million years old and it is
between 6 and 10 km thick. It forms the seafloor
and is composedmainlyofbasaltic rock.
1.3.2.
Themantle
The density of this layer varies. It is composed
mainly of a type of rock called peridot. Themantle
has two parts.
❚
The
upper mantle
has a higher density than
the crust and it is solid. However, scientists have
discovered some areasof liquidormolten rock.
❚
The
lower mantle
is the densest layer of the
mantle and containsmaterials in a solid state.
1.3.3.
The core
This is the most internal and densest layer of the
geosphere. It is composedmostly of iron, although
othermetals such as nickel can be found. It is divided
into two layers.
❚
The
outer core
is not as dense as other layers. It is
composed ofmoltenmaterials and it is constantly
moving.
❚
The
inner core
has the densestmaterials. It is the
hottest layer. Even though the temperatures are so
hot, thematerials in this layerare ina solid statedue
to the immensepressure found in it.
Key concepts
❚
TheEarthwas formedby the
accretion of planetesimals.
Thematerials thatmake up
the Earth were distributed
in layers according to their
density.
❚
There are three layers in
the geosphere: the crust
(continental and oceanic),
mantle (upper and lower)
and thecore (outerand inner).
1
drill hole
:
a perforation in the
ground inorder tostudy the rocks
under theEarth’s surface
Seismograph
Formationof the Solar System
Layersof thegeosphere anddiscontinuities that separate them
Understand
1.
Explain inyourownwords themeaningof
accretionofplanetesimals
.
2.
Listenand find thepartsof thegeosphereon thediagram.
Create
3.
Findoutabout thedensityof the layersof thegeosphere.Makea table
with the information in theorderof leastdense todensestmaterials.
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