Earth's Poles Were the Same in the Early Days

According to a new research, released by the paleomagnetists at the Princeton University, our planet had the same magnetic-field structure in the early days. The two-pole model of today is believed by some to be an evolution of an ancient, unstructured one, and experts on both sides have been debating this vigorously for quite some time. The new study brings this debate to a conclusion, showing that models on how the planet must have looked like millions of years ago are correct.

The new investigation bears considerable implications for understanding old continental movements, which are in turn related to the climate change over various time frames. Planetary scientists hope that they will be able to use the newly found knowledge to devise better models of the Earth's climate history. This could, in turn, lead to a better understanding of the warming period we are going through today. In their research, the Princeton experts looked at the 1.1-billion-year-old volcanic rocks located on the north shore of Lake Superior, in North America.

They determined that the planet's magnetic structure was a geocentric axial dipole, which essentially resembled a large magnet bar. This bar is centered on the Earth's core, and is aligned with the planet's spin axis, the investigators reveal. Other investigations have shown that a six-pole, or even an eight-pole structure may have existed in the past, hinting at a more complex magnetic history. If they had turned out to be correct, these studies would have invalidated all the known models of continental evolution, which rely on paleomagnetic data related to just two poles.

“In this paper, we show that Earth's magnetic field has been more stable in the past than originally believed,” paper author and Princeton Assistant Professor of Geosciences Adam Maloof explains. “For the past 30 years, scientists have feared that the geometry of Earth's field was complex and varied. Such a complex field made it very hard for people to reconstruct the ancient geography of the planet because they could not rely on a predictable field. We show that these fears were unfounded – at least for 1.1 billion years ago – and that the evidence for a complex ancient field was an artifact of the way rocks had been sampled,” he adds.