Approximately how many times has Earth's magnetic field switched in the last 10 million years?

The Earth's magnetic field has undergone numerous reversals throughout its history, where the north and south magnetic poles swap places. Geological and paleomagnetic studies indicate that during the last 10 million years, the magnetic field has reversed itself more than 40 times. This conclusion comes from the analysis of volcanic rocks and ocean floor sediments that capture the orientation of the Earth's magnetic field at the time of their formation.

The frequency of these geomagnetic reversals varies over geological time scales, with certain periods characterized by more frequent reversals. Analyzing the magnetic signatures preserved in the geological record, scientists have documented that reversals occur roughly every several hundred thousand years to a few million years, leading to the total number exceeding 40 times in the recent geological time frame.

This understanding highlights the dynamic nature of Earth's magnetic field and its relationship with geological and tectonic processes.