The study will be published in the November 2014 issue of .
The discovery comes as new evidence indicates that the intensity of Earth’s magnetic field is decreasing 10 times faster than normal, leading some geophysicists to predict a reversal within a few thousand years.
This date is far more precise than that from previous studies, which placed the reversal between 770,000 and 795,000 years ago.
Renne said: What’s incredible is that you go from reverse polarity to a field that is normal with essentially nothing in between, which means it had to have happened very quickly, probably in less than 100 years.
Image courtesy of University of California – Berkeley Earth’s magnetic field is known to have flipped many times throughout our planet’s history.
You might imagine the magnetic field is a timeless, constant aspect of life on Earth, and to some extent you would be right. Every so often – on the order of several hundred thousand years or so – the magnetic field has flipped. And when the field flips it also tends to become very weak.We’re turning to some perhaps unexpected data sources, including 700-year-old African archaeological records, to puzzle it out.Genesis of the geomagnetic field Earth’s magnetic field is created by convecting iron in our planet’s liquid outer core.Scientists at University of California, Berkeley then used argon-argon dating, a method widely used to determine the ages of rocks, whether they’re thousands or billions of years old, to determine the age of ash layers above and below the sediment layer recording the last reversal.Because the lake sediments were deposited at a high and steady rate over a 10,000-year period, the team was able to interpolate the date of the layer showing the magnetic reversal, called the Matuyama-Brunhes transition, at approximately 786,000 years ago.