Had compass-toting Boy Scouts existed around fifteen million years ago, they may have had a fun time making it through the forest. New geological research questions if the Earth's magnetic field changed, at that time, at the remarkable pace of one degree per week, leading to a particularly fast magnetic pole flip. In a paper to appear in Geophysical Research Letters, Scott Bogue and Jonathan Glen suggest that the Earth's magnetic field changed 53 degrees in one year's time, based on their study of preserved lava flows in Nevada. As the solid rock formed from cooling liquid lava, it preserved a pattern corresponding to the "super-fast" geomagnetic field reversal, the researchers believe. This is the second time that Bogue has controversially argued for the existence of such speedy flips, finding hints of a faster one in 1995.
In 1995 an ancient lava flow with an unusual magnetic pattern was discovered in Oregon. It suggested that the field at the time was moving by 6 degrees a day--at least 10,000 times faster than usual. "Not many people believed it," says Scott Bogue of Occidental College in Los Angeles. [New Scientist]
Geological recordings of the Earth's magnetic field usually indicate that these north-south magnetic somersaults only happen once every couple hundred thousand years, and they occur in slow motion, taking around 4,000 years to complete the reversal. Though scientists aren't sure what causes these flips, some point to electricity-conducting liquid iron spinning in the Earth's core, since the "geodyno" formed from the currents are thought to be responsible for the Earth's magnetic field in the first place. The new findings are likely to prompt a new wave of debate, and even Bogue notes that the rock patterns he spotted may have another explanation. The crystals in the rock that show a speedy magnetic field change may be anomalous, he told New Scientist--a "burst of rapid acceleration" in an otherwise slow and steady process. Some geologists say we're currently headed for another flip, as Science Newsreports, given the fact that the Earth's magnetic field has weakened over the last century, but even a super-fast flip might not mean much for your daily life.
But apocalyptic SyFy channel movies to the contrary, nobody should worry about waking up one morning to geomagnetic havoc, says Bogue. “To geologists a polarity reversal is a nearly instantaneous thing that changes a global feature of the Earth—it’s really a spectacular phenomenon,” he says. “But if you were alive when it was happening, it probably wouldn’t be that big a deal.” [Science News]
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Image: NASA
