Stories from Physics for 11-14 14-16
Researchers have discovered that a geomagnetic spike occurred around 1000 BCE by examining the magnetic fields in slag, a by-product of copper manufacture, smelted at the time. It is estimated that the magnitude of the Earth’s magnetic field strength doubled before falling to normal levels in the Levantine region of the Middle East. The change in field only lasted around 30 years and was confined to an area a few thousand kilometres across. The researchers speculate that the spike was caused by an intense localised equatorial patch of flux at the core-mantle boundary.