Download UD 3 THE GEOSPHERE - IES Gabriela Mistral

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Introduction.
1. What are the differences between a mineral and
a rock?
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Introduction.
2. What do we use minerals and rocks for?
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Introduction.
3. What is an opencast mine?
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Introduction.
4. What does the Earth look like inside?
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1. THE EARTH. ORIGIN AND COMPOSITION.
The earth can be divided into four layers: the geosphere, the
atmosphere, the hydrosphere and the biosphere.
1.1 THE ORIGIN OF THE EARTH.
ACCRETION OF PLANETESIMALS.
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1. THE EARTH. ORIGIN AND
COMPOSITION.
The Earth is made
up of 3 main layers:
Core
Mantle
Crust
Mantle
Outer core
Inner core
Crust
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1. THE EARTH. ORIGIN AND COMPOSITION.
CRUST: is the thin layer or rocks that covers the Earth´s
surface above the mantle. Its depth varies between 5 km and
70 km. There are two types of crust:
Continental crust is the layer of rocks
which forms the continents, the shallow
areas of the oceans (continental shelf)
and some islands. Its thickness varies
between 10 km (Atlantic continental
shelves) and more than 70 km (below the
great mountain ranges, such as the
Himalayas and the Andes).
Oceanic crust is thinner than
continental crust, between 5-8 Km, but
it is denser than the continental crust.
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1. THE EARTH. ORIGIN AND
COMPOSITION.
•The Mohorovicic discontinuity: marks the boundary between the crust
and the mantle.
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1. THE EARTH. ORIGIN AND
COMPOSITION.
MANTLE: it is believed that the mantle was formed when
primitive Earth started to cool down. The mantle has two
areas of different density: the density of the upper is smaller
than the density of the lower mantle.
It is made up of denser rocks like peridotite and magnesium.
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1. THE EARTH. ORIGIN AND
COMPOSITION.
•The Gutenberg discontinuity: marks the boundary between the
mantle and the core.
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1. THE EARTH. ORIGIN AND COMPOSITION.
CORE: the most abundant element in the Earth´s core is
probably iron. For this reason, the Earth behaves like an
enormous magnet. But other substances are also believed to
be inside the Earth, such as nickel and sulphur.
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Activities 3. PAGE 47.
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Introduction.
1. MINERALS.
Minerals have the following features:
They are inorganic solids: they are not formed by living things.
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1. MINERALS.
Introduction.
Minerals have the following features:
They occur naturally, they don´t contain artificial matter.
They have definitive chemical compositions, Some mineral have
one single chemical element (gold…) but most are compounds
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Introduction.
1. MINERALS.
Minerals have the following features:
They have a crystalline structure: the atoms and molecules that
compose the solid have a specific pattern.
Crystallisation is a very slow process.
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Activities 4, 5, 6, 7, 8, 9. PAGE 48.
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Introduction.
2.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
HARDNESS: resistance to scratching or abrasion. To find out the
hardness of a mineral, we use the MOHS SCALE.
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Introduction.
1.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
LUSTRE: how light is reflected from the surface of a mineral.
Lustre can be metallic or non-metallic.
Non-metallic lustre can be VITREOUS (the mineral looks like broken
glass):
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Introduction.
1.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
LUSTRE: how light is reflected from the surface of a mineral.
Lustre can be metallic or non-metallic.
Non-metallic lustre can be PEARLY (the mineral changes colour
according to the light):
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Introduction.
1.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
LUSTRE: how light is reflected from the surface of a mineral.
Lustre can be metallic or non-metallic.
Non-metallic lustre can be GREASY (the mineral looks like oil on
water):
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Introduction.
1.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
COLOUR: some minerals can be easily identified as they are
always the same colour, but others, such as quartz, can be
different colours.
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Introduction.
1.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
STREAK: the colour of the mineral in powder form. This is
constant in each mineral.
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4. THE EARTH´S INTERNAL STRUCTURE.
1.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
TRANSPARENCY: the amount of light able to pass through a
mineral. A mineral can be transparent, translucent or opaque.
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4. THE EARTH´S INTERNAL STRUCTURE.
1.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
CLEAVAGE: the ability of a mineral to break along planes of
weakness: this produce regular fragments. Mica breaks into thin
sheets, so it has basal cleavage. Galena breaks into cubes, so it
has cubic cleavage.
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4. THE EARTH´S INTERNAL STRUCTURE.
1.1 THE PROPERTIES OF MINERALS.
The properties of minerals help us to identify them. The most
important ones are:
MAGNETISM: some minerals attract magnets.
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Activities 12, 13. PAGE 50.
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2.1 THE IMPORTANCE OF MINERALS.
Many minerals give us useful materials. Minerals that contain
enough of a metal or compound to be extracted in a profitable
way are called
ores.
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4. THE EARTH´S INTERNAL STRUCTURE.
1.1 THE IMPORTANCE OF MINERALS.
Other minerals, such as gypsum, form the materials used to make
useful substances. Gypsum is used for many different things and
is abundant in the Earth´s crust.
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4. THE EARTH´S INTERNAL STRUCTURE.
1.1 THE IMPORTANCE OF MINERALS.
Minerals are also used to make paint and pigments. From example
ochre comes from haematite.
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4. THE EARTH´S INTERNAL STRUCTURE.
1.1 THE IMPORTANCE OF MINERALS.
GEMS or PRECIOUS STONES are not very common minerals. They are
valuable because of their colour, rarity and beauty. They are
used to make jewels.
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4. THE EARTH´S INTERNAL STRUCTURE.
1.1 THE IMPORTANCE OF MINERALS.
NOBLE METALS, such as gold, silver and platinum are used in
jewellery. They are soft and easy to work with. Platinum is very
valuable because it is very rare and doesn´t degrade over time.
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Activities 15, 16 PAGE 51.
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3. ROCKS.
Most rocks are made of mixture of minerals.
Some rocks are made of only one mineral, like limestone,
gypsum or halite. They are called unconsolidated rocks.
Other rocks, like granite, are made of combination of
different minerals: these are called consolidated rocks.
Some rocks, such as coal, aren´t made of minerals but of
the remains of living thing.
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2.1 TYPES ROCKS.
Rocks are classified according to their:
ORIGIN, how they were formed: sedimentary, igneous or
metamorphic.
STRUCTURE: the properties that we can see.
TEXTURE: the position, size and crystal arrangement of their
component minerals.
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Igneous rock.
The temperature inside the Earth is extremely high, so rocks
there, melt and mix with water and gases to form a hot thick
substance called magma.
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Igneous rock.
When magma cools down, it solidifies and forms igneous
rocks. If magma cools down slowly inside the Earth, it forms
intrusive igneous rocks, such as granite. If magma, in the form
of lava, comes to the Earth´s surface when a volcano erupts
and then cools down quickly, it forms extrusive igneous rocks.
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Igneous rock.
INTRUNSIVE IGNEOUS ROCKS.
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Igneous rock.
EXTRUSIVE IGNEOUS ROCKS.
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Activities 20 PAGE 53.
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Sedimentary rock.
Geological agents erode the rocks on the Earth´s surface.
Water and wind carry the eroded pieces of rock (sediments)
to the lowest areas of land and to the ocean floor into
sedimentary basins. (1)
Due to the weight of the material that
accumulates on top of them, sediments
combine with the water in the ground and
form sedimentary rocks. COMPACTION (2)
AND CEMENTATION (3)
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Activities 21, 22 PAGE 54.
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Metamorphic rock.
Any rock can be transformed into a different type of rocks if
subjected to high pressure or high temperature.
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Metamorphic rock.
Any rock can be transformed into a different type of rocks if
subjected to high pressure or high temperature.
Metamorphic refers to the process that changes the
composition and appearance of rocks. It is usually occurs
inside the Earth.
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Metamorphic rock.
Metamorphic usually have a specific texture called foliation:
the minerals are arranged in bands; this occurs in slate and
shale.
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Metamorphic rock.
Other metamorphic rocks such as marble and quartzite are
non-foliated rocks.
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Activities 24 PAGE 56.
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4 THE USE OF ROCKS.
Rocks are mined to extract the minerals they contain or are
used directly to make building materials or as ornamental
objects.
•USE OF SEDIMENTARY ROCK.
Conglomerate: produces gravel, which is extracted and used
to make concrete.
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2.2 THE IMPORTANCE OF ROCKS.
Rocks are mined to extract the minerals they contain or are
used directly to make building materials or as ornamental
objects.
•USE OF SEDIMENTARY ROCK.
Sandstone: produces sand, which is extracted and used to
make concrete. Very pure sand is used to make glass.
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Activities 28, 29, 30 PAGE 58.
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5. EXTRACTION OF MINERALS AND ROCKS.
Human have always used the rocks and minerals on the
Earth´s surface for different purposes.
The mining of an area depends on:
The potential financial benefits.
What type of rock is needed.
How easy it is to reach the rocks and mine them.
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5. EXTRACTION OF MINERALS AND ROCKS.
MINERAL MINING. There are two basic methods of mining:
UNDERGROUND MINING takes place deep in the subsoil. It
is used to extract minerals from below the surface of the
ground.
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5. EXTRACTION OF MINERALS AND ROCKS.
There are two basic methods of mining:
OPEN-PIT MINING takes place in an open pit. It is used to
extract minerals that are near the surface. Enormous holes
are dug into the surface of the land.
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5. EXTRACTION OF MINERALS AND ROCKS.
ROCK MINING. Rocks are usually mined in open-cast mines,
quarries or sometimes in underground mines. There are also
other methods of extracting rocks:
GRAVEL PITS produce gravel. Gravel is not strictly a rock, but
a sediment. It is found near riverbeds.
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5. EXTRACTION OF MINERALS AND ROCKS.
ROCK MINING. Rocks are usually mined in open-cast mines,
quarries or sometimes in underground mines. There are also
other methods of extracting rocks:
OIL DRILLING is used to extract oil. This takes place either
on land or on floating platforms in the sea.
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5. EXTRACTION OF MINERALS AND ROCKS.
ROCK MINING. Rocks are usually mined in open-cast mines,
quarries or sometimes in underground mines. There are also
other methods of extracting rocks:
DRILLING is also used to extract soluble rocks, such as
halite. Water is injected to dissolve the rock and pump it to
the surface.
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Activities 31, 32. PAGE 59.
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FINAL TASK.
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