In the high Canadian Arctic, researchers at the University of Rochester have stripped away some of the mystery surrounding the powerhouse that drives the Earths magnetic field. The research strongly suggests that several of the characteristics of the field that were long thought to operate independently of one another, such as the fields polarity and strength, may be linked. If so, then the strength of the field, which has been waning for several thousand years, may herald a pole reversal-a time where compasses all over the Earth would point south instead of north. The findings are being published in todays issue of Proceedings of the National Academy of Sciences.
John Tarduno, professor of geophysics, took 14 students on four excursions, the most recent in the summer of 2000, far above the Arctic Circle to pitch tents near 95-million-year-old rocks on the snow-covered islands of Ellesmere and Axel Heiberg. The rocks, part of a formation called the Strand Fiord, were spewed forth from ancient volcanoes during a time when the Earths magnetic field was particularly stable. As the volcanoes lava cooled to become igneous rock, tiny crystals lined up with the Earths magnetic field and were solidified in the rock. Tarduno was seeking these crystals and the data they preserved about the magnetic field.
Tarduno wanted to find whether the crystals in this region bore evidence of brief fluctuations in the magnetic field. Several more accessible areas of the globe house such crystals, but Tarduno had to go to the edge of the "tangent cylinder"-a giant, theoretical cylinder that runs through the Earth like a pimento through an olive. This cylinder extends away from the Earths solid iron core to the north and south poles and represents an area of possible high turbulence in the molten iron of the core, stirred up by the Earths spin. Near the edge of this cylinder of turbulence scientists believe the liquid iron should be the most chaotic, twisting up the magnetic lines of force. Where this edge contacts the Earths crust high above the Arctic Circle should lie traces of the twisted magnetic field in the crystals.
Jonathan Sherwood | EurekAlert!
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