For years scientists have been arguing about the theory of the wandering West, and whether it would have been possible for plate tectonics to have moved massive chunks of the Earth's crust northward along a gigantic faultline. Now UW paleontologist Peter Ward and his collaborators report in tomorrow's Science magazine that the discovery of pearly fossil shells of an extinct mollusk on two islands off the eastern coast of Vancouver Island give clear evidence that the region was once nearly 2,000 miles to the south.
"Everything that we now recognize as coastal British Columbia was once off the coast of what is now Mexico or Southern California. It was nowhere near its present latitude," says Ward.
Ward's study was aimed at proving that traces of magnetism in rocks on the British Columbia coast were the actual relic of the Earth's ancient magnetic field. As the layered, or sedimentary, rocks were deposited under the sea, mineral crystals became magnetized, freezing the magnetic field. If the rocks had been formed at the equator, the direction of the magnetism in the formation would have been horizontal. At the poles, it would have been vertical. Thus if rocks in British Columbia show a magnetic field slightly tilted from the horizontal, the implication is they were formed far to the south.
But there is a catch. As the Earth's crust is heated, particularly by
volcanic upheavals, the mineral crystals in the rocks can become remagnetized,
leaving no trace of the earlier, ancient magnetic field. So those British
Columbia rocks may not have moved
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Contact: David Brand
dbrand@u.washington.edu
(206) 543-2580
University of Washington
11-Sep-1997