New Scientist’s excellent Inside Science pull-out series now includes one on the Earth’s core (Bowler, S. 2000.  Journey to the Centre of the Earth.  Inside Science #134,  New Scientist 14 October 2000).  This covers the origin and evolution of the core, how geologists can assess its composition and structure, and the link between motions in the core and the fluctuations in the Earth’s magnetic field.  Like all the Inside Science pull-outs, Sue Bowler’s treatment is at a level easily followed by non-Earth scientists but nonetheless informative and up to date.