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Asked by ellz13 to Angus, Christian, Hannah, Laura, Simon on 18 Jun 2013.
Question: How does Earth's interior work, and how does it affect the surface?
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Hannah Bentham answered on 18 Jun 2013:
The Earth’s interior is made up of 4 basic zones: the Crust (down to about 70 km), the Mantle (70-2981 km), the liquid Outer Core (2891-5154km) and then the solid Inner Core.
In the Mantle, the rocks move slowly over million of years due to convection (think of a lava lamp with hot blobs moving up and cold blobs moving down). There are many theories as to what pattern of convection we have, but currently geophysicists and geodynamicists think that the whole of the mantle convects together such that convection cells span from top to bottom. The motion of the cell is driven by the subduction of the cold oceanic plates from the surface as they descend through the mantle. Heat rises to the surface from the core-mantle boundary bringing hot rocks with it and the rocks explore out of the surface at hot spots like Hawaii. So you can see that the Mantle and the surface are directly connected. My research looks for subducted plates in the Mantle so we can find out more about Mantle convection, both in the present and the past.
Also, the Outer Core generates the Earth’s magnetic field and this is useful for us for navigation. But more importantly, the magnetic field protects us from asteroids!
By studying the interior of the Earth we can find out more about the surface we live on.
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Simon Holyoake answered on 18 Jun 2013:
I’d like to add that the earth’s magnetic field also protects us from the solar wind, which is a stream of highly charged particles emitted from the sun, without the magnetic field, these particles would rapidly ‘blow’ our atmosphere away, much as happened to Mars
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Laura Roberts Artal answered on 19 Jun 2013:
The core looses heat very very slowly (over millions of years it is cooling down) and the loss of this heat is linked to the motion of the mantle that Hannah discribed. If we can understand more of how the core works (and we don’t really understand that much) then we can say more things about how the mantle works and what impact it has on the surface of the Earth.
Some people believe that without plate tectonics a planet cannot have life and they also believe that the how big a planet is determins whether plate tectonics are active or not. We are very lucky that the Earth meets all this conditions.
Studying the magentic field (which is what I do) can hopefully give us a lot of information about what happens at the surface of the Earth.
Comments
Hannah commented on :
Excellent addition Simon!