Researchers at Yale University have proposed a new model explaining the dramatic fluctuations in Earth's magnetic field during the Ediacaran Period, from 630 to 540 million years ago. Their analysis of rocks from Morocco suggests these changes followed a structured global pattern rather than random chaos. The findings, published in Science Advances, could improve reconstructions of ancient continents.
Earth's magnetic field during the Ediacaran Period exhibited unusual variability, preserving signals in rocks that fluctuated far more than in other eras. This made paleomagnetic reconstructions of continents and oceans challenging. Scientists had previously suggested causes like rapid tectonic plate movements or true polar wander, but a new study led by Yale researchers challenges those ideas. David Evans, a professor of Earth and planetary sciences at Yale, stated, 'We are proposing a new model for the Earth's magnetic field that finds structure in its variability rather than simply dismissing it as randomly chaotic.' The team developed a statistical analysis method for Ediacaran paleomagnetic data to produce robust maps of ancient geography. Focusing on volcanic rocks in Morocco's Anti-Atlas region, collaborators from Cadi Ayyad University helped identify well-preserved layers. James Pierce, the study's lead author and a Yale Ph.D. student, explained, 'We were able to determine precisely how fast the Earth's magnetic poles were changing by sampling for paleomagnetism at high stratigraphic resolution and determining precise ages for these rocks.' High-resolution data revealed shifts over thousands of years, ruling out slower processes like tectonic drift. Contributions from Dartmouth College and institutions in Switzerland and Germany refined the timelines. The poles may have shifted across the planet in an organized way, Evans noted. This framework bridges gaps in Earth's tectonic history, enabling consistent visualizations from billions of years ago to today. The National Science Foundation partly funded the research.