Heat and Plate Tectonics - Western Reserve Public Media

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Heat and Plate Tectonics
Inside the Earth
The part of Earth we live on is called the
crust. This is a very tiny layer on the planet.
Beneath that is the mantle. This is a semiliquid layer that is very hot.
Temperature range from 5000 F to 7,0000 F,
depending how deep you are.
At the center is the core. This is even hotter,
but is a solid due to the immense pressure
on it.
Earth
Where Did All the Heat Come From?
Most of it came from the formation of the
planet. When Earth formed, it was a molten
ball of rock.
It cooled from the outside in.
Think of a recently hard -boiled egg. The
outside gets cool relatively quickly, but the
inside stays warm for a long time because it
is harder to transfer the heat out.
Earth
The earth is a big rock:
5,973,600,000,000,000,000,000,000 kg
How long does it take the center of
something that big to cool down?
It has been cooling for 4.7 billion years
and is not cool yet!
Radiation
There is also another factor heating the
interior of the crust.
Radioactive elements, like uranium, are in
the Earth.
These elements are releasing radiation
which is warming the interior of the Earth.
Heat in the Mantle
What does this heat do?
It causes objects to expand, changing their
density, causing them to rise.
Other objects fill in the spaces they just left.
This is a convection current.
Convection and Radiation
A quick look at convection on the surface
The sun radiates heat in the form of light toward
the planet. This heats the surface, which
conducts heat to the air touching it.
The hot air expands, and begins to rise
Cooler air fills the void the
hot air left.
The air begins to circulate.
The circulation is convection,
light (energy) is radiation.
Earth
Radiant Energy
Radiation can be visible light, but can also
be a large spectrum of things such as …
Plate Tectonics
The theory that explains why geologic
phenomena such as earthquakes,
volcanoes and continental drift occur in
terms of the movement of the earth’s
lithospheric plates.
On top of the mantle are several plates of
rock that the crust sits on.
Energy
The top part of the mantle is called the
aesthenosphere.
The plates sit on this layer and move
around slightly due to the convection
currents.
The energy from an earthquake or a
volcanic eruption is simply energy from the
mantle that is being transferred.
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