There's probably no stranger place in Earth's layered interior than where the molten iron core meets the bottom of the rocky mantle some 2900 kilometers down.
Weird things happen at the core-mantle boundary.
But to do that, the layer would have to be more electrically conductive than partially molten rock is. An explanation for such strange behavior might be a slow rain of precipitates floating to the boundary, say geophysicist Bruce Buffett of the University of British Columbia in Vancouver and colleagues. The precipitates are impurities in the liquid iron that could precipitate as the core cools, much like the salts that appear when the temperature of hot brine drops. The sandlike particles are less dense than the iron soup and would rise to the top of the core. Iron trapped in the sediment pile would provide enough conductivity to explain the nodding of Earth's rotation, Buffett and his colleagues suggest in the 17 November issue of Science , and the sediments should hold enough fluid to account for slowed seismic waves.