About 600 million years ago, the continents wandered Earth, yet to settle into their current positions. Their locations during the Ediacaran (as this time is called) have been tough for scientists to pin down. Earth's magnetic field appears to have behaved in erratic ways, and applying standard tech niques to calculate the continents' positions based on records of the magnetic field yields implausible results. In particular, scientists debate the location of an ancient continent called Baltica, which is now part of Europe. ...read more read less