I don't fully understand how the magnetic field reversal could cause a continent to travel. I do remember Graham Hancock had a dubious theory about it.
I believe there is more to it than that particular theory. For instance it's known how to make Permanent Magnets, one particular old and tried method is striking a metal repeatedly will pointing it North. (The Strikes are more Stroke like than Blows)
Admittedly now adays electromagnetic systems are used to create permanent magnets, however you could suggest that as the Molten Magma cools, it cools with a certain amount of polarity set. So the crust actually has a magnetic field, however the magma still moves around generating polar shifting.
Between the two occurances you could understand that perhaps some of the movement of tactonic plates can be magnetically manipulated. Other factors are that the crust itself isn't the same thickness all the way around the planet, this causes for bottlenecks in the magma that can push up plates (Earthquakes and mountain ranges) or cause volcanoes to errupt.
Further to that if you look at Pig Iron melting, sometimes you can have the impurities on the molten irons surface which might need a higher temperature to melt. If the iron was to be stirred then you'd see it's "Skin" fragment and shift in relationship to the movement.
As for Atlantis... It's known that it's "Mythical" and there are a number of islands and old ruins lost to the seas over time. For instance that earthquake that cause the tsunami that hit places like Thailand caused a number of "emersed" coral reefs to become "Islands" and the inverse could be said about some of the islands disappearing into the sea.
These are events that don't require global warming or polar icecaps melting to trigger.
