The earth’s magnetic field may be in the process of reversing its polarity — something which scientists believe has happened in the distant past of the planet. Although the shift was too far back for historical records to exist, geologists are able to date lava flows to periods of planetary history, and this lava (frozen molten rock) has the same value as pottery shards in fixing the direction of magnetic fields at certain periods of time. David Gubbins, an earth scientist at the University of Leeds in Britain, ties this evidence of the decline in the strength of the planet’s magnetic field to increases of patches of reverse magnetic fields.
http://thenewamerican.com/index.php/tech-mainmenu-30/environment/5835-earths-magnetic-north-pole-is-on-the-move
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