Wandering of the Geomagnetic Poles
The Earth's magnetic poles are known to migrate over time. In fact the North Magnetic Pole has been observed to move up to 40 km in a year.
The National Geophysical Data Center has used Google Maps to trace the movement of the magnetic dip poles from 1590 to 2010. The map is based on four centuries of historical records including ship log data.
Each pole includes a marker to show the position of the dip poles at the turn of each century (1600, 1700, 1800, 1900 and 2000).