"We're getting stronger evidence that there's something unusual about the core-mantel boundary under Africa that could be having an important impact on the global magnetic field," says John Tardano professor of geophysics and physics and astronomy at the University of Rochester. Using new data gathered from sites in southern Africa, University of Rochester researchers have extended their record of Earth's magnetic field back thousands of years to the first millennium. The record provides historical context to help explain recent, ongoing changes in the magnetic field, most prominently in an area in the Southern Hemisphere known as the South Atlantic Anomaly. "We've known for quite some time that the magnetic field has been changing, but we didn't really know if this was unusual for this region on a longer timescale, or whether it was normal," says Vincent Hare, who recently completed a postdoctoral associate appointment in the Department of Earth and Environmental Sciences (EES) at the