How fast do the Earth's tectonic plates move per year?
2-5cm
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Give an example of a major plate.
African, Eurasian
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What was Alfred Wegener's discovery?
1912 - he postulated that now-separate continents had once been joined.
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What were the key ideas of Arthur Holmes?
1930s - Earth's internal radioactive heat was the driving force of mantle convection that could move tectonic plates
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What was the discovery made in the 1960s?
The athensophere is a weak deformable layer beneath the rigid lithosphere.
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What was the second discovery made in the 1960s?
The existence of magnetic strips in the oceanic crust of the sea bed; palaeomagnetism (ancient magnetism) signals past reversals of the Earth's magnetic field.
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What does 'palaeomagnetism' prove?
It proves that new oceanic crust is created by the process of sea floor spreading at mid oceanic ridges.
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