Transcript Earth`s Interior (What`s down there below us?)

Earth’s Interior
(What’s down there below us?)
There are 4 main layers inside Earth
How THICK are the layers?
(entire Earth is ~ 8000 miles wide)
Crust: oceanic crust
3-6 miles thick
continental crust 6-30 miles thick
Mantle: about
1700 miles thick
(2/3 of Earth’s mass)
Outer core: about
1400 miles thick
Inner core: about
1500 miles thick
How HOT are the layers?
Crust: 0oC at surface  400oC where it
contacts mantle
Mantle: ~500oC to
~3700oC deeper down
Outer core: ~4000oC
Inner core: ~7000oC
(hotter than the surface
of the sun!!)
What are the layers made of?
Crust: Rock
Mantle: Dense rock
Outer core:
Liquid metal (iron) !!
Inner core:
Solid metal
(mostly iron)
Of course, it’s not quite that simple:
The “lithosphere” is the crust + part of the upper mantle.
It is made of rock and is brittle. The “plates” of the earth’s
crust make up the lithosphere.
Below the lithosphere
is a softer layer called
the “asthenosphere”.
In the asthenosphere,
The rock is near it’s
melting point, and
flows very slowly, kind
of like asphalt or tar.
Why the partly melted
asthenosphere??
MELTING
POINT OF
ROCK
(yellow)
ACTUAL
TEMP
(green)
This graph shows why there is a
layer of soft, partially melted
rock (the ASTHENOSPHERE) in
the top part of the mantle of the
earth.
From 100 to 200 km (60-120
miles) below the surface, the
temperatures are above the
melting point of the rock - even
at the very high pressure at this
depth.
This layer - the ASTHENOSPHERE - is what the plates of the crust
“float on” and explains why they can move around.
Finally – a very cool map showing
thickness of earth’s crust (in km)
Continental crust
is thick.
Oceanic crust
is thinner