1.2 why is our e arth u nstable ?
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1.2 Why is our e arth u nstable ?. _______. _______. _______. What is the structure of the earth?. Our earth can be divided into _______ layers. three. Crust. From the surface to the centre, they are:. Mantle. Core. What is the structure of the earth?. - PowerPoint PPT PresentationTRANSCRIPT
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1.21.2 Why is our Why is our eeartharth u unstablenstable??
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Our earth can be divided into _______ layers.three
From the surface to the centre, they are:
Crust
_______
_______
_______
Mantle
Core
What is the structure of the earth?
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What is the structure of the earth?
They are arranged according to their _________.density
In general, layers with ( lighter / heavier ), ( less dense / denser ) minerals lie on the top.
In what ways are the three
layers arranged?
In what ways are the three
layers arranged?
Density of minerals:Magnesium: 1,738 kg/m3
Silica (silicon): 2,330 kg/m3
Aluminium: 2,700 kg/m3
Iron: 7,874 kg/m3
Nickel: 8,908 kg/m3
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Crust
Mantle
Core
Let’s study these three layers.
What is the structure of the earth?
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What are plates? These pieces are called plates.
Forces are constantly generated from within the earth.
They break the solid lithosphere into pieces.
Which plate does Hong Kong rest on?
Which plate does Hong Kong rest on?
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( Regular / Irregular ) in shapeVariable in thickness from 100 to 200 kilometres
Great differences in sizes, varying from a few hundred to thousands of kilometres acrossLying and floating on the asthenosphere and moving slowly in different directions at a rate of a few centimetres per year
What are plates?Plates have the following characteristics:Some of the plates carry both oceanic crust and continental crust
Eurasian Plate
Indo-Australian Plate
Pacific Plate
, while some of them only carry oceanic crust
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How do plates move?Footage
01_e_movie_01.mpg
Simulation experiment on how plates are driven (Old, but have to modify)
NSS Part 1 1-13
Please click above for footage
This experiment simulates how
the plates move.
Convection currents occur in the water when it is heated. They drag the wood pieces at the
surface.
The wood pieces sometimes knock against each other
and sometimes flow apart. The higher the heat,
the faster the movement.
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How do plates move?The plates float on the ______________.asthenosphere
The heat in the asthenosphere creates powerful ___________ __________. They drag the plates to move in different directions.
currentsconvection
Plate
Upper mantle(asthenosphere)
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How do plates move?The plate movements result in _______ different types of plate boundaries.
three
Destructive plate
boundaries
Constructive plate boundaries
Conservative plate
boundaries
Plate boundaries
The theory that describes how convection currents in the mantle cause plate movement is known as __________ __________.
platetectonics
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If the plates move in the directions shown throughout the history, imagine how the continents were distributed
in the distant past.
If the plates move in the directions shown throughout the history, imagine how the continents were distributed
in the distant past.
How do plates move?
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Core
MantleCrust
Continental crust
Oceanic crust
CrustCrust is made up of two types.Continental crust
Making up the continents and the continental shelves, which are gently sloping plains bordering the continents
Thick and light
Rich in _________ and ____________
silicaaluminium
Continental crust
0 km
6–70 km
0 km
100–200 k
m
350– 500 kmConvection currents of magma
Oceanic crust
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CrustOceanic crust
Oceanic crust
0 km
6–70 km
0 km
100– 200 km
350– 500 kmConvection currents of magma
Under the oceans
Thinner, denser and heavier than continental crust
Rich in silica and ____________magnesium
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MantleMantle lies below the _______, as it is denser.
It can be divided into three parts:
0 km
100– 200 km
350–500 km
Asthenosphere
Lower mantle
Uppermost part of the mantle
( solid / plastic / liquid )
( solid / plastic / liquid )
( solid / plastic / liquid )
Magma flows in convection
Under high pressure
Up
per m
antle
crust
This layer and the crust are collectively called lithosphere
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CoreThe core is the ( hottest / coldest ) and the ( densest / least dense ) part of the earth.
It can be subdivided into two layers:
Outer core
Inner core
( solid / plastic / liquid )
( solid / plastic / liquid )
Why is the outer core in liquid form but the inner core
in solid form?
Why is the outer core in liquid form but the inner core
in solid form?
The intense heat causes the materials of the outer core to melt
The inner core is under the greatest pressure. The materials are kept in
solid form
Core
Mantle
Crust
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1 Constructive plate boundaries
Please click above for animation
When convection currents diverge or move apart:
Plates _____ _____ from each other
split
________ wells up and fills the gap betwee
n the plates
Magma
New crust is formed when solidified
away
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2 Destructive plate boundaries
Please click above for animation
When convection currents converge:
Plates move ( towards each other / apart )
When plates collide, the denser one _____, or subducts into the a
sthenosphere
sinks
The sinking part of the plate melts into
magma