INTEGBI N33 Lecture Notes - Lecture 23: Continental Drift, Continental Crust, Oceanic Crust
31 Mar 2018
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Document Summary
Study of the record of the earth"s magnetic field in rocks and sediment. Earth has magnetic charge with both north and south poles. Charge reverses (last reversal 780k years ago) and irregular reversals produce characteristic sequences in rocks. Once the rock hardens/lithifies when forming, magnetic particles are frozen in orientation and are aligned with poles; but, if they are not pointing/aligned with poles, this shows that continents have moved. Particles in rocks are charged and can identify polarity of rocks when it was formed. If we move the rocks from a particular point in time back to where the magnetically charged particles are aligned with the poles, that tells us where the rocks were and when the rocks formed. Shows evidence for continental drift by looking at where rocks were at a particular time relative to the poles. Outer core molten because ongoing radioactive decay in core generates heat (keeps earth warm)
