WHAT IS TRUE RATE OF REVERSALS OF EARTHS MAGNETIC FIELD

Known reversals of the Earth's magnetic field occur at a rate of five per million years. However, the methods whereby the reversal pattern has been established act as a high frequency cut-off filter and will not record two reversals as separate if they occur close to each other. It is thus probable that the true reversal rate is much greater than five per million years. By comparing the observed distribution of polarity interval lengths with a theoretical distribution it is shown that the most likely rate of reversal is close to ten per million years. © 1969.