Plate Tectonics Notes

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  • The Earth is a solid sphere of various layers. (How many layers?)
  • At the very centre is the core – inner and outer. The inner is solid, however the outer is liquid. (How do we know?)
  • Because the pressure increases as depth does, material gets denser and denser and denser. Inner core perhaps Ni/Fe. Therefore the Earth’s magnetic field comes from the Fe in the core.
  • Beyond the core is the mantle. It’s probably solid, but as it nears the crust it’s perceived as plasticky and ‘soft’.
  • Above that, the crust – between the crust and the mantle is the ‘Moho’ line, the boundary. Solid. (in most places) and not very thick.
  • Diff. between tallest/highest – highest is actual point. Tallest is amount from summit to land around.
  • Crust thickness can vary from 20 to 70km thick. (Why does it vary?)
  • Why is the core so hot?  
  • For example, on the Sun there are multiple thermonuclear explosions. On the core of this planet there’s low-level, minor radioactivity taking place.
  • Where does the heat go?
  • Radiates out and starts to reach the surface. It doesn’t reach the surface evenly. It reaches the upper mantle at points, called hot spots (heat source). As that heat is released, and it reaches the crust, it melts it slightly and spreads. Therefore our crust is starting to break apart, it’s spreading (tectonic plates). When it comes together, one…

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