Earth's Switching Magnetic Field Dated with Improved Radiometric Dating

Every so often, Earth's magnetic field switches. Essentially, the north pole becomes the south pole and vice versa. Now, scientists have gotten a better sense of when this last reversal occurred, which could be huge for calculating the ages of rocks and timing events that occurred in the geologic past.

In this latest study, the researchers examined volcanic ash that was deposited immediately before the MBB, the Matuyama-Brunhes boundary. This volcanic ash contained small crystals called zircons; some of these crystals formed at the same time as the ash, which meant that radiometric dating of these zircons using the uranium-lead method provided the exact age of the ash.

In order to verify the findings, the researchers also used a different method to date sedimentary rock from the same place that was formed at the time of the MBB. The combined results revealed that the actual age of the MBB is 770.2 plus or minus 7.3 thousand years ago.

"This study is the first direct comparison of radiometric dating, dating of sediments, and the geomagnetic reversal for the Matuyama-Brunhes boundary," said Yusuke Suganuma, one of the researchers, in a news release. "Our work contributes calibrating the geological time scale, and will be extremely important in future studies of the events that occurred at this time."

The findings reveal a bit more about this time period and show a bit more about when events occurred. This is extremely important when creating a timeline of these types of events.

The findings are published in the journal Geology.

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