Using layers of ash in lake sediments in Italy, researchers claim to have dated the last flip of the Earths magnetic field more accurately than ever before — at 786,000 years ago. The spot has unusually high resolution during the right 10,000 year era, which gives better detail on the process of this major event. Curiously the flip started with two periods of magnetic instability that spanned first 6,000 years then, later, 2,000 years. At the end of the second period, suddenly the magnetic flip occurred. It was so fast that researchers guess it was in less than 100 years.