
Ancient Geomagnetic Reversals Were Longer and Messier Than Thought
A Newfoundland sediment core reveals two magnetic polarity reversals around 40 million years ago lasting about 18,000 and 70,000 years, far longer and more variable than the commonly cited ~10,000-year reversals. The findings suggest reversals are chaotic and driven by the Earth's geodynamo in the outer core, implying future reversals could last tens of thousands of years and may increase exposure to cosmic radiation with potential climate and biological impacts.












