Lecture 6 (September 16)

Lecture 6 (September 16) - Paleomagnetism Earths magnetic...

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Paleomagnetism Earth’s magnetic field o Dipole field o Looks like a bar magnet Magnetic field generated by flow in Earth’s molten outer core (~ 90% Fe) Magnetic poles are near the geographic poles but they don’t coincide Inclination (of the earth’s magnetic field) o (def): angle the lines of magnetic flux make relative to Earth’s surface at a point, (i.e., horizontal) o High latitudes: inclination is steep Declination o (def): angle magnetic field makes relative to geographic north pole Earth’s magnetic field o The field looks like that produced by a dopole located at the center of the earth o The field is inclined with respect to eh axis of rotation Lodestone = magnetite o Compass needles Rocks can record ancient magnetic field info (most obvious rocks that can do this: lavas) Rock Magnetism o (a) Magnetic mineral grain at a temperature above the Curie point (> 60 ° C). Magnetic domains are randomly oriented with no net magnetization
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Lecture 6 (September 16) - Paleomagnetism Earths magnetic...

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