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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: about1400 miles thick
Inner core: about1500 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 lithosphereis a softer layer calledthe “asthenosphere”.
In the asthenosphere,The rock is near it’s melting point, and flows very slowly, kindof like asphalt or tar.
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.
MELTINGPOINT OFROCK(yellow)
ACTUALTEMP(green)
Why the partly melted asthenosphere??