In the last four million years, the Earth's magnetic north and south poles have switched places at least 11 times, the most recent flip happening about 780,000 years ago. In 1993, a pair of geophysicists from Paris found a distinct "rhythm" beating within these reversals, a tantalizing discovery that apparently contradicts 30 years of statistical analysis. The first independent confirmation of this seemingly global magnetic pattern comes in a recent issue of Geophysical Research Letters. Researchers from UC Davis and the University of Hawaii reproduced this pattern: Magnetic field strength soared after a pole shift and then bounced up and down, gradually weakening until the field bottomed out before the next pole reversal. "This shows we have to take this idea seriously," geology professor Kenneth Verosub says. To test this fundamental rethinking of the behavior of the geomagnetic field, Verosub and research geophysicist Andrew Roberts, both from UC Davis, teamed up with researcher Emilio Herrero-Bervera at the University of Hawaii to reanalyze central Pacific Ocean basin core magnetic data from the two most recent pole reversals.