Earth's magnetic field may flip fast

摘要

Just north of a truck stop in Battle Mountain, Nev., lies evidence that the Earth's magnetic field once went haywire.rnMinerals in 15-million-year-old rocks appear to preserve a moment when the magnetic north pole was rapidly on its way to becoming the south pole, and vice versa. Such geomagnetic field reversals occur every couple hundred thousand years, normally taking about 4,000 years.rnThe Nevada rocks suggest that this switch happened much faster. Anyone carrying a compass would have seen itsrnreadings skew by about a degree a week. A paper describing the discovery is slated to appear in Geophysical Research Letters.