Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Magnetic Pole

Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_921-3

Definition

Magnetic poles are two regions on the opposite ends of a magnet, where the magnetic intensity is the highest. Due to the presence of a liquid metal core, the interior of the Earth behaves as a giant dynamo, giving the Earth a magnetic field. The Earth’s magnetic field is dipolar with an axis at a small angle to the rotational axis, making the magnetic poles slightly offset from the geographic poles.

The magnetic polarity has changed with highly variable frequency through geological history. At times, the reversals are frequent, every few hundred thousand years or less, but in the mid-Cretaceous the polarity remained constant for nearly 40 Ma. The inclination of the magnetic field is recorded by magnetic minerals in rocks and provides information about the latitude at the time the rock formed (paleomagnetism). Apparent polar wander curves are compilations of the positions of the magnetic poles as reconstructed from the minerals in strata of different ages from a single continent...

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Maison des GéosciencesLGCA, Université J. FourierSt-Martin d’HèresFrance