GEOL 1020 Lecture Notes - Lecture 4: Carbon-14, Radiogenic Nuclide, Mazama Ash
7 Dec 2017
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Document Summary
Magnetostratigraphy the use of magnetic properties of rock for relative dating and correlation. Because the earth has a magnetic field resulting from motions of earth"s iron-rich, liquid outer core. Earth behaves like a giant bar magnet, with a north and a south pole. When iron rich minerals form sedimentary or igneous rocks at earth"s surface, they often align with earth"s magnetic field (like a compass does). Earth"s north & south magnetic poles occasionally switch positions! Spiny lobster, birds, sharks and many more animals use the earth"s magnetic field as a compass. Magnetic reversals are flip-flop phenomena -- they"re either normal or reversed. Today is normal polarity: lines of magnetic force at earth"s surface are directed toward the north magnetic pole and the compass needle points north. Stripes or normal and reversed polarity have developed in the oceanic crust, and have been radiometrically dated. Magnetic polarity reversals result in a global bar-code" called the.
