Transcript Plate Tectonics - Grade 9 Geography

The Lithosphere!”The
Structure of the Earth & Plate
Tectonics.
Date: 02/08/12.
Lesson Objective ~
• To become familiar with the
structure of the Earth
• To look at plates
•Then volcanoes
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How old is the Earth?
The Earth is…
2 million years old
100 million years old
4600 million years old
30 million years old
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Lets look at internet clip and get
some data!
• Does the data collected, correlate with the
information on the handout? If yes/no explain
reasons why
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Cross section of the Earth
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Write your name and form on the worksheet!
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Q: Does this third set of data correlate with the
previous two sets of data? Explain with ©examples.
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Answers:
1.
2.
3.
4.
Trenches
Basalt
Lithosphere
Convection
currents
5. Granite
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Answers:
1.
2.
3.
4.
Trenches
Basalt
Lithosphere
Convection
currents
5. Granite
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Lets watch the clip
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Plate boundaries
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Continental drift
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Evidence for plate tectonics
1. Study of fossils – similar fossils are found on different
continents. This is evidence that these regions were once
very close or joined together.
2. Pattern of rocks – similar pattern of rock layers on
different continents is evidence that the rocks were once
close together or joined.
3. Shape of continents fit together like a jigsaw.
Africa
South
America
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Evidence for plate tectonics
4. Magnetic field pattern in iron containing rocks
The reversal of the Earth’s magnetic field is recorded in
the rocks that solidify at constructive margins. The
symmetry around the margin is evidence that the rocks are
moving apart.
constructive
margin
SN S S S
N N
N
N
S N
pattern same both sides
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Why do the plates move?
Crust
Convention
Currents
Mantle
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Eurasian
North
American
Pacific
African Plate
Nazca
South
American
Indo Australian
Plate
Antarctic
Plate Names
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AfricanAPlate
Indo Australian
Plate B
Plate Boundaries
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Can you name plates A and B?
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Constructive
Plate
Boundary
At a constructive plate boundary, two
plates move apart. As the two plates
move apart, magma rises up to fill
the gap. This causes volcanoes at
this type of boundary. However, since
the magma can escape easily at the
surface the volcano does not erupt
with much force. Earthquakes are
also found at constructive
boundaries.
An example of a constructive
boundary is the Mid-Atlantic Ridge.
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Constructive plate boundary
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Mid-Atlantic ridge
Sea Floor Spreading!
Did you know that the
ocean floor in the
Atlantic is growing by
3cm per year?
Which of the following pairs of continents are moving
further away from each other?
1) Europe and Africa
2) Europe and North America
3) South America and North America
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Title:_______________________
Put these labels on your diagram:
volcanic island / North American plate / Eurasian
plate / Volcano / Crust / Mantle
In your own words; At a
_______plate boundary, two plates
move apart. As the two plates move
apart, magma rises up to fill the gap.
This causes volcanoes at this type of
boundary. However, since the magma
can escape easily at the surface the
volcano does not erupt with much
force. Earthquakes are also found at
constructive boundaries.
An example of a constructive
boundary is the Mid-Atlantic Ridge.
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Title:_______________________
Put these labels on your diagram:
volcanic island / North American plate / Eurasian
plate / Volcano / Crust / Mantle
In your own words; At a
_______plate boundary, two plates
move apart. As the two plates move
apart, magma rises up to fill the gap.
This causes volcanoes at this type of
boundary. However, since the magma
can escape easily at the surface the
volcano does not erupt with much
force. Earthquakes are also found at
constructive boundaries.
An example of a constructive
boundary is the Mid-Atlantic Ridge.
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How fast do plates move?
The plates move at different rates.
The Nazca and Pacific plates are moving apart at a rate of
18cm per year while the Eurasian and North American
plates are moving apart at a rate of 3cm per year.
To the nearest metre, how far will the Nazca and Pacific
plates have moved over the next 200 years?
6 metres
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36 metres
200 metres
928 metres
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A destructive plate boundary is found
where a continental plate meets an
oceanic plate.
Destructive
Plate
Boundary
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The oceanic plate descends under the
continental plate because it is denser.
As the plate descends it starts to melt
due to the friction caused by the
movement between the plates. This
melted plate is now hot, liquid rock
(magma). The magma rises through
the gaps in the continental plate. If it
reaches the surface, the liquid rock
forms a volcano.
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Title:___________________
Put these labels on your diagram:
Andes (fold mountains) / Pacific Ocean /
Nazca Plate (Oceanic Crust) / Magma rises /
Mantle / Volcanic eruption/ Oceanic crust
melts due to friction and heat from the mantle
In your own words: ________plate
boundary is found where a
continental plate meets an oceanic
plate.
The oceanic plate descends under
the continental plate because it is
denser. As the plate descends it
starts to melt due to the friction
caused by the movement between
the plates. This melted plate is now
hot, liquid rock (magma). The
magma rises through the gaps in the
continental plate. If it reaches the
surface, the liquid rock forms a
volcano.
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Title:___________________
Put these labels on your diagram:
Andes (fold mountains) / Pacific Ocean /
Nazca Plate (Oceanic Crust) / Magma rises /
Mantle / Volcanic eruption/ Oceanic crust
melts due to friction and heat from the mantle
In your own words:________ plate
boundary is found where a
continental plate meets an oceanic
plate.
The oceanic plate descends under
the continental plate because it is
denser. As the plate descends it
starts to melt due to the friction
caused by the movement between
the plates. This melted plate is now
hot, liquid rock (magma). The
magma rises through the gaps in the
continental plate. If it reaches the
surface, the liquid rock forms a
volcano.
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Collision
Boundary
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Collision boundaries occur when 2
plates of similar densities move
together (i.e. a continental plate and a
continental plate). This causes the
material between them to buckle and
rise up, forming fold mountains.
The Himalayas are an example of a
chain of fold mountains. They have
been formed by the African plate
colliding into the Eurasian plate.
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Title:_________________________
Put these labels on your diagram:
collision zone / mantle / Himalayas / Eurasian plate.
Collision margins / Constructive
margins
In your own words: _________
boundaries occur when 2 plates of
similar densities move together (i.e. a
continental plate and a continental
plate). This causes the material
between them to buckle and rise up,
forming fold mountains.
The Himalayas are an example of a
chain of fold mountains. They have
been formed by the African plate
colliding into the Eurasian plate.
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Title:_________________________
Put these labels on your diagram:
collision zone / mantle / Himalayas / Eurasian plate.
Collision margins / Constructive
margins
In your own words: _________
boundaries occur when 2 plates of
similar densities move together (i.e. a
continental plate and a continental
plate). This causes the material
between them to buckle and rise up,
forming fold mountains.
The Himalayas are an example of a
chain of fold mountains. They have
been formed by the African plate
colliding into the Eurasian plate.
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Conservative plate boundaries
exist where two plates do not
directly collide but slide past
each other along a fault
(weakness).
Conservative
Boundary
No volcanoes are found along
these plate boundaries, but
earthquakes do occur.
An example of such a boundary
is the San Andreas Fault in
California.
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Title:_______________________
In your own words: _________
plate boundaries exist where two
plates do not directly collide but slide
past each other along a fault
(weakness).
No volcanoes are found along these
plate boundaries, but earthquakes do
occur.
An example of such a boundary is the
San Andreas Fault in California.
Fill in the blanks, two plates, a
country name and 3 places,
S___D____, L__ A______ &
S_____________, ocean.
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Let’s shake and bake!!!
• In your groups quietly decide which one of the
four plates you are going to act out, remember
try and act out as many features and process of
your chosen plate.
• Can you guess which “plate” your fellow
classmates are?? Ask them where they may
find this plate on planet earth or any other
question.
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Homework, due in
st
Thursday/Friday20/21 of October.
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Attach labels to the correct part of the diagram.
Outer core
Crust
Mantle
Inner core
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Name this plate boundary
A
G
B
E
C
F
D
Match the labels to the letters
Earthquakes occur due to friction
The oceanic crust sinks under
the less dense continental crust
Oceanic plate
Continental crust
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Explosive volcanoes
The oceanic crust
melts and rises
Mantle
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Constructive plate boundaries
MID OCEAN
RIDGE
B
A
Ocean
Mantle
Where would you find older rocks – at A or at B?
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Mark the following events on your time line.
What do you notice?
India collides with Asia – 50 m
First flowers appear – 100 m
Man (homo sapiens) inhabits the Earth – 0.1 m
Formation of the Alps – 30 m
Dinosaur extinction – 65 m
You were born! – 0.00013 m
Industrial Revolution (UK) - 0.0001 m
(figures are in ‘millions of years ago’)
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