Friday, November 2, 2007

new map

"The World Digital Magnetic Anomaly Map (WDMAM) shows the variation in strength of the magnetic field after the Earth's dipole field has been removed. Earth's dipole field is generated by circulating electric currents in the planet's metal core. It varies from 35,000 nanoTesla (nT) at the Equator to 70,000 nT at the poles."

"After removal of the dipole field anomalies, the variations in the field (few hundreds of nT) are due to changes in the magnetic properties of the crustal rocks themselves.

Hot colours (reds) indicate high values; cold colours (blues) indicate low or negative values of the magnetic field strength."

So for eg. the Atlantic is striped as the plates are moving apart here and creating new rock. The earth's magnetic fields reverse periodically and this is recorded in the rock at the time it forms.

READ here



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