Polar shift (Pole Shift) is simply the change in magnetic field of the Earth. The origin of the magnetic field is the rotation speed difference between the inner core and the crust of the planet and the shift is the exchange of north and south poles. During this shift it is expected to have massive earthquakes, even today we are experiencing huge magnitude earthquakes especially in the pacific ocean.
During the shift continental drift is not expected but it is possible to observe climatic changes, tornados and earthquakes during the exchange. Actually what is exact North Pole today was nearly on Western Canada approximately 75.000 years ago.
Magnetic field around the Earth has the mission to protect the planet against the dangerous radiation from the Sun and outer space. During the change the magnetic field may arrive to zero point which meant whole planet will be unportected against these harmful radiation and ultraviolet rays.