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Earth Model
In this presentation you will:
 explore the structural layers of Earth
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Introduction
The Earth is somewhat
like an onion, in that it is
made from lots of
different layers.
The different layers are
composed of different
materials. This gives
the Earth some of its
characteristics.
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Composition of the Earth
Each of the layers has
different characteristics.
Crust
The crust is the outer
layer of the Earth, made
from solid rock. It is
much thinner than the
lower layers of the Earth.
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Composition of the Earth
The crust has two
main parts:
Oceanic
crust
Continental
crust
 Continental crust – this
forms the continents.
Its thickness varies
from 20 km to 80 km.
 Oceanic crust – the
thin crust under the
oceans. It is around
10 km thick.
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Composition of the Earth
The mantle is underneath
the crust. It is made of
rock but, due to intense
heat, it behaves like an
extremely thick liquid!
Mantle
The mantle moves very
slowly. So slowly in fact
that its motion would
only be noticeable over
hundreds of years.
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Composition of the Earth
The mantle has two parts:
 Upper mantle – the
more solid portion.
At the top, the
temperature is
around 1,000 °C.
Upper mantle
Lower
mantle
 Lower mantle – the
less solid portion.
At the bottom, the
temperature is
around 3,700 °C.
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Composition of the Earth
Below the mantle is
the outer core. It is
mostly made of iron
but, because of the
extremely high
temperatures, the iron
has melted
and become liquid.
A solid inner core is
suspended in the outer
core. Although the
temperatures at the core
are around 4,300 °C,
the pressure is so great
that the iron stays solid.
Outer core
Inner core
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Depths
The inner core is about
2,440 km in diameter.
Crust
The outer core is about
2,250 km thick.
Upper
mantle
The lower mantle is about
2,130 km thick.
The upper mantle is
about 670 km thick.
Lower mantle
The crust ranges from
10 km to 80 km thick.
Outer core
Inner core
The thickest parts of the
crust are the mountain
ranges, while the thinnest
are the ocean floors.
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Structure Regions
The top of the upper
mantle and the crust
form the lithosphere –
the solid outer layers
of the Earth.
Lithosphere
Asthenosphere
The upper mantle and
the top section of the
lower mantle make up
the semi-liquid
asthenosphere.
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Question 1
Which of the following mostly consists of liquid iron?
A) Crust
B) Mantle
C) Outer core
D) Inner core
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Question 1
Which of the following mostly consists of liquid iron?
A) Crust
B) Mantle
C) Outer core
D) Inner core
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Question 2
“The lithosphere is made up of the crust and part of the lower mantle”.
Is this statement true or false?
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Question 2
“The lithosphere is made up of the crust and part of the lower mantle”.
Is this statement true or false?
False
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Modeling the Planet!
We cannot dig down to
the center of the Earth to
find out exactly how it’s
made. So, models have
to be used to represent
this information.
Drill
Crust
Mantle
12 km
(max)
Models can be made in
a variety of ways:
Outer core
Inner core
 drawing
 mathematically
 physical
 computer generated
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Predictions
Models can be used to
predict future events. This
is accomplished by using
information from previous
events and by applying
mathematical probability of
events happening again.
This is what is happening
when you watch a weather
forecast!
A weather model has
been used to predict what
will happen in the coming
hours, days or weeks.
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Predictions
A detailed model of the
Earth can be built using
scientifically recorded data.
This model can then be
used to predict, for
example, how the Earth’s
magnetic field will change
over the coming years.
USGS
Kristian Birkeland's electrical terella
(Field-aligned currents)
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Predictions
By looking at models
of the Earth’s crust,
scientists are working
towards being able to
predict when and
where geological
events may occur.
USGS
Examples of
geological events are
earthquakes and the
eruption of volcanoes.
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Visualization
Sometimes it is difficult
to understand the scale
of a concept. Building a
3D model or drawing a
model can make it
easier to understand.
0.5 mm thick
For example, a 3D model
of Earth’s structure the
same size as a soccer
ball would require the
crust layer to be less than
0.5 mm thick!
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Question 3
Why might scientists want to model the structure of the Earth?
A) To predict future events that relate to movement in the Earth’s crust
B) To make it easier to explain what is going on under the surface
C) To better understand why geological events occur
D) All of the above
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Question 3
Why might scientists want to model the structure of the Earth?
A) To predict future events that relate to movement in the Earth’s crust
B) To make it easier to explain what is going on under the surface
C) To better understand why geological events occur
D) All of the above
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Summary
In this presentation you have seen:
 the structure of the Earth including, inner and outer core, mantle and crust
 the layers making the asthenosphere
 the layers making the lithosphere
 advantages and disadvantages of modeling the natural world
End