Occidental College geology professor Scott Bogue's research on rapid geomagnetic field change landed on Discover magazine's "Top 100 Stories of 2010."
Bogue and colleague Jonathan Glen of the U.S. Geological Survey recently found evidence of a brief episode of rapid geomagnetic field change that was thousands of times faster than usual. The findings are significant: They may throw into question scientific knowledge about Earth's geomagnetic field reversals, when the magnetic north pole flips to the south pole, and vice versa.
Occidental is the only private liberal arts college whose research is featured in Discover's most newsworthy stories. The January-February 2011 special issue of the science and technology magazine listed the geologists' research as No. 87 on the list. Bogue and Glen's findings were originally published in November in the journal Geophysical Research Letters. Disover's other top stories include how sharks use math to hunt (No. 92), the archaeological discovery in central China of an immaculately preserved village dating back more than 2,000 years (No. 89), and the massive oil gush in the Gulf of Mexico that lasted 86 days (No. 1).
Geomagnetic field reversals happen every few hundred thousand years and take several thousand years to complete. Bogue and Glen studied 15 million year-old lava flows in a Nevada mountain range, Sheep Creek Range. In particular, they used Occidental's super-conducting rock magnetometer to analyze the magnetization of a 13-foot thick lava flow that had erupted as the geomagnetic field was reversing polarity.
They discovered that the lava flow contains two magnetic patterns acquired within about a year of each other as the lava cooled. The patterns differ in direction by 53 degrees, implying that the geomagnetic field was changing at a rate of about one degree per week.
"This rapid field movement happened toward the end of a several-thousand year long reversal," Bogue said. "Other evidence suggests that the polarity reversal is a very unsteady process, with periods of standstill as well as rapid change."
Serendipity played a role in the geologists' research. Bogue was initially interested in rocks in Argenta Rim, just southeast of Sheep Creek Range. Those rocks turned out to be a dead end. But instead of packing up his equipment and going home, Bogue decided to look at Sheep Creek Range since it was close. And that's where he and Glen eventually struck paleomagnetic gold.
Their research, funded by National Science Foundation grants, also brings more credence to a similar instance - the only other example discovered so far - found at Oregon's Steens Mountain in 1995. The researchers for the earlier study analyzed lava flows 1.2 million years older than the rock at Sheep Creek Range and found evidence of an episode of a 6-degree per day change. That rate of directional change was so high that many in the earth science found it hard to accept.
