Past Pole Reversals
Geomagnetic reversals are not rare events. In fact, they have occurred regularly throughout Earth’s history, with the most recent reversal occurring approximately 780,000 years ago, a period known as the Brunhes-Matuyama reversal. These reversals are recorded in the magnetic alignment of rocks on the ocean floor, where molten lava cools and solidifies. The minerals within the rocks record the direction of the magnetic field at the time of formation, allowing scientists to trace past pole flips.
The Timeline of Past Reversals
- The Brunhes-Matuyama Reversal (780,000 Years Ago)
This is the most recent major geomagnetic reversal, marking the boundary between the Brunhes Chron and the Matuyama Chron. It was a significant event that scientists have studied in detail using deep-sea sediment cores and volcanic rocks. - The Gauss-Matuyama Reversal (2.58 Million Years Ago)
Another major event in Earth’s magnetic history, this reversal has been linked to the Pleistocene Epoch. This period also witnessed the onset of ice ages and other significant climatic changes. - The Reunion Event (~2.5 Million Years Ago)
This was a less-known event, a brief reversal that lasted only a few thousand years. It is believed to have been a “cryptochron,” a type of reversal that didn’t leave a lasting signature in the geological record. - The Matuyama-Brunhes Boundary
After the last reversal, Earth’s magnetic field has remained relatively stable, though occasional weaker variations in the field continue to be observed today.
Scientists have identified evidence of many more reversals dating back billions of years, with intervals between reversals ranging from tens of thousands to millions of years.