Download Plate Tectonics

Presented By
Rana Faizan Saleem
Roll.No.(10)
This Presentation explain you:
Pangea/Continental Drift Theory.
 Why Pangea Theory Rejected?
 What are Tectonic Plates?
 Tectonic Plate Theory.
 Different Plate Boundries.
 How Earth Magnetic Field Formed?
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Pangaea is a theory that a young German
scientist named Alfred Wegener came up with
in 1910.
 The Theory stated:
“All the Continents were joined together
about 250 million years ago to form a Supercontinent, called Pangaea.
Over time this super-continent drifted apart
to make continents on which we are living
today,This theory is called continental drift
theory.”
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This theory rejected by scientists because
Alfred Wegener could not explain what force
pulls or pushes Continents.
He died in Greenland on his expedition.At the
time of his death no one believed his theory.
There are following evidences for his theory:
(i) Same Fossils
(ii) Landforms
(iii)Shapes like Jigsaw Puzzle
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Lithosphere is divided into small and large
plates,called Tectonic Plates.These plates
floating on the suface of Asthenosphere.
Plate Tectonics Explain:
(1) Earthquakes
(2) Mountains
(3) Volcanos
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Hot magma in the Earth moves toward the
surface, cools, then sinks again.
Creates convection currents beneath the
plates that cause the plates to move.
There are three types of Plate Boundries:
(1)Divergent Boundaries
(2)Convergent Boundaries
(3)Transform Fault Boundaries
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When two plates diverge or moving far apart
from each other due to magma eruption.
Mid-Oceanic ridges happens in this type.
When two plates collide into one another.
 One of the plates will Subduct under
other,Subduct means slide underneath.
 There are three types of convergent plate
boundaries:
(1) Ocean to Ocean
(2) Continent to Continent
(3) Ocean to Continent
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When two ocean’s crust collide together.
When this happens the older oceanic crust
will be subducting under the younger crust.
And Island arcs are created by this type of
collision.
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When two continental plates collide together.
Both plates have same density due to which
no plate subducting other.
Both plates applied equal force due to which
rock crumble and Himalayas formed.
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Oceanic crust is more denser than
Continental crust.
Due to high density oceanic plate underneath
the continental plate,this process is called
“Subduction”.In this process continental plate
forced on oceanic plate to subduct.
When oceanic crust enters into mantle it
starts floating backward,in other words
magma erupts and Volcanoes created.
When two plates neither moves apart nor
collide towards but moves along side each
other.
 The plates can move side wise in same
direction or in different direction also.
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Earthquakes happens due to movement of
these plates.
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It is produced by outer-core of earth which is
made of liquid iron and nickel.
Moving magnetic material produced moving
magnetic field which then turns to create
moving electric field,called as geodynamo.
It helps us to find directions.
 It protect us from cosmic rays.
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