http://www.universetoday.com/2006/08/31/did-the-earth-flip-over-in-the-past/
Scientists have found evidence that the Earth might have flipped over in the past, completely shifting the orientation of its poles. The theory has been around for years; that a large mountain range or supervolcano might unbalance the spinning Earth. Over the course of millions of years, the Earth would change the orientation of its axis until the object was balanced at the equator again. The scientists found evidence of magnetic grains in layers of rock sediment on the ocean floor that maintain a record of the Earth’s magnetic field over millions of years. - [Universe Today]
