Plate tectonics
by Alexander Jankovics
Plate Tectonics
At the end of the lesson,
students will be able to:
 describe the structure of the
Earth and the characteristics of the
different layers
 explain the theory of plate
tectonics
 sketch a labelled drawing of the
Earth structure and a world map
with the major tectonic plates .
STARTER
Engage the Brain
What’s the difference?
Mt Fuji
Mt Everest
VS
.
In pairs, you have 3 minutes
to discuss what you think
the main difference is in
how Mt Fuji was formed,
compared to the Mt Everest
STARTER
Engage the Brain
Can you remember the
layers of the Earth?
??
??
??
??
This is the basic
structure of the
earth which you
might have been
shown before.
At IGCSE you
need to know a
more detailed
version of this…
MAIN ACTIVITIES
Gain knowledge &
show understanding
A cross-section of the
Earths structure
Crust 0-100 km
thick
Make your own
diagram in your
notebook!
MAIN ACTIVITIES
Gain knowledge &
show understanding
The Crust
The Earth’s crust is very
thin compared to the
diameter of the planet.
Think of it
like the skin
on an apple.
MAIN ACTIVITIES
Gain knowledge &
show understanding
The Crust
The crust is made up of sections, called plates, ranging
from the very small to the size of an entire continent.
Continental crust is
much thicker than
oceanic crust.
Oceanic crust is
more dense than
continental crust.
MAIN ACTIVITIES
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show understanding
The Crust
Annotate the diagram in your notebook!
Continental Crust
Oceanic Crust
• Below land
• Thicker
• Below ocean
• Thinner
• Less dense
• More dense
• Granite
rock
• Basaltic
rock
(35-100 km)
(lighter)
• (large crystals)
(5-10 km)
(heavier)
• (black/dark grey)
The crust is moving!!!
Convection heat
transfer
MAIN ACTIVITIES
Gain knowledge &
show understanding
Crust
Convection
Currents
Mantle
*THINK*
Convection
Cell
Convection Currents
MAIN ACTIVITIES
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show understanding
Core
Convection
Cell
Theory of plate
tectonics
Tectonic theory
People once thought that the oceans and the continents were formed by
shrinkage from when the Earth cooled down after being formed.
Alfred Wegener proposed something different. Consider Africa and South
America:
These continents look
like they “fit”
together. They also
have similar rock
patterns and fossil
records. These two
pieces of evidence led
me to believe that
there was once a
single land mass. This
is my TECTONIC
THEORY.
Forming mountains
The formation of mountain ranges can be explained by tectonic
theory. Consider the Himalayas at the top of India:
This is where
India is now
This is where
India was millions
of years ago
The intense heat and pressure from this process causes the
rocks to change structure into metamorphic rocks.
The Evidence:
Tectonic theory
1) Some continents look like they used to “fit” together
2) Similar rock patterns and fossil records
The Problems:
Wegener couldn't explain
how continental drift
happened so nobody
believed him
The Answer:
1) Scientists discovered 50 years later that the Earth generates
massive amounts of heat through radioactive decay in the core.
This heat generated convection currents in the mantle causing the
crust to move
2) We also now know that the sea floor is spreading outwards from
plate boundaries
Conclusion – scientists now believe Wegener’s Tectonic Theory
MAIN ACTIVITIES
Gain knowledge &
show understanding
With your partner
Name that plate!
?
?
?
?
? ?
?
?
?
?
?
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Tectonic Plates
MAIN ACTIVITIES
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show understanding
North
American
Caribbean
Pacific Cocos
Nazca
Eurasian
Pacific
Arabian
Philippine
African
South
American
IndoAustralian
Antarctic
Tectonic Plates
MAIN ACTIVITIES
Gain knowledge &
show understanding
North
American
Caribbean
Pacific Cocos
Nazca
Eurasian
Pacific
Arabian
Philippine
African
South
American
IndoAustralian
Antarctic
Map of Plate Boundaries
Exit ticket
Answer these exam style
questions:
a)What is a plate?
b)What causes plates to
move?
c)How fast do plates
move?
4
minutes