Earth's Internal Structure and Theoretical Frameworks

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  • Earth's Internal Structure and Theoretical Frameworks
    • The Core
      • inner core is solid, the outer core is liquid, both are made from iron and nickel, is a source of radioactive heat
    • The Mantle
      • semi molten body of rock between the Earth's crust and its core
      • Asthenosphere
        • part of the mantle, semi molten, below the lithosphere which floats on top of it
    • the lithosphere
      • crust and upper mantle which form the plates, together they are 80-90km thick
      • changes in thickness under oceans and continents - under oceans the crust is 6-10km thick, under continents it is 30-40km thick
    • Wegener's continental drift (1912) said that there was once a supercontinent (pangea)
    • Holmes (1930s) said that the Earth's internal radioactive heat was the driving force of convection currents in the mantle that could move plates
    • 1960s - Paleomagnetic signals - magnetic stripes in the oceanic crust of the seabed that reverses in the Earth's magnetic field proves that new crust is created due to seafloor spreading
    • elevated altitudes of oceanic crust at ridges at divergent plates create a slope down which oceanic plates slide - gravitational sliding
    • slab pull - convergent boundaries - ocean floor is dragged down by a downward gravitational force

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