how long ago was the last time earth's magnetic field reversed
Geomagnetic reversal The time spans of chrons are randomly distributed with most being between 0.1 and 1 million years[citation needed] with an average of 450,000 years. Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago, and may have happened very quickly, within a human lifetime.[1]