[The Hunter of Jahanna]

AFAIK every few million years the magnetic poles of the planet swap places , or so scientist think. The evidence for this theory is found in naturaly occuring magnetic rocks. In large samples they will have alternateing bands magnetized in diffrent polarities for diffrent amounts of time. So North might be good for 10,000 years, then it flips and says that way for a few thousand years , then it flips back again. Scientists theorize that it is a rapid change because of the distinct change in the magnetic polarity. Some theorys are that as the earth tilts on its axis that every now and then it flips completely over. Another is that since the core of the earth is liquid that either the core or the surface slide around on the liquid layer.