■ GEOMAGNETIC REVERSAL
✓A geomagnetic reversal or a reversal in earth’s magnetic field is a change in a planet’s magnetic field such that the positions of magnetic north and magnetic south are interchanged.
✓Based on palaeomagnetism (is the study of the record of the Earth’s magnetic field in rocks, sediment, or archaeological materials).
✓It is observed that over the last 20 million years, magnetic north and south have flipped roughly every 200,000 to 300,000 years.
✓The reversal is not literally ‘periodic’ as it is on the sun, whose magnetic field reverses every 11 years.
✓The time between magnetic reversals on the Earth is sometimes as short as 10,000 years and sometimes as long as 25 million years.
✓And the time it takes to reverse could be about a few hundred or a few thousand years.
✓The magnetic poles emerge at odd latitudes throughout the process of the reversal.
