into_to_geo_4 - Plate Tectonics cont. Why Anomalies? Iron...

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Plate Tectonics cont . Why Anomalies? Iron atoms in crystals formed in the most recent past have remnant magnetism in concert with today’s global magnetic field (and are said to have normal polarity) Extra field strength derives from the alignment of all these mini-magnets with the modern dipole The same is true for all positive anomalies; they represent crystallization and cooling that took place during times when Earth’s magnetic polarity was the same as it is today Negative anomalies are derived from bodies of rock that crystallized and cooled during times when Earth’s magnetic field had a polarity opposite to today’s The iron atoms of these rocks destructively interfere with the modern dipole, weakening the observed magnetic strength Plate Tectonics Together, the evidence for sea-floor spreading and continental drift form the basis of our modern understanding of plate tectonics, the unifying theory of geology that explains the links between earthquakes, volcanism, and mountain building
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This note was uploaded on 04/08/2011 for the course GEOL 2001 taught by Professor Babaie during the Winter '09 term at University of Georgia Athens.

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into_to_geo_4 - Plate Tectonics cont. Why Anomalies? Iron...

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