The Spinning Magnet by Alanna Mitchell

Author:Alanna Mitchell
Language: eng
Format: epub
Publisher: Dutton
Published: 2018-01-30T05:00:00+00:00

CHAPTER 19

pharaohs, fairies, and a tar-paper shack

Inside the conference center’s auditorium in Nantes, the scientists were struggling. Not with the new findings on the inner workings of the Earth. Or with the elegant math that described them. But with the tiny font size of the print on the screen at the front of the cavernous room. Some of the conference participants were covertly bringing out binoculars. Others were taking photographs with their iPhones and then zooming in on the information using their touchscreens. This is the mind of the scientist: If there are barriers to getting data, you figure out your own way of leaping over them. It was that instinct that drove the scientific community after Brunhes’s paper on reversals in 1906. Skepticism reigned. Had the planet’s magnetic field really reversed direction? And if so, how can we be sure?

Theoretical questions hinged on whether such a dramatic perturbation of the poles was even possible. If it was, what was the mechanism? What was the purpose of a reversal? Could it have happened more than once? Could it even be a recurring feature of the planet’s magnetic landscape?

The practical questions were no less pressing. What if Brunhes’s terracotta didn’t mean what he thought it meant? Modern inquisitors might question whether Brunhes’s finding meant that the poles were stable but the European continent had rotated 180 degrees on the Earth’s surface. But at the beginning of the twentieth century, most geologists thought the continents were fixed, so they were looking for a different explanation for Brunhes’s discovery. What if scientists had a faulty understanding of the way the magnetic memory of rocks worked? What if Brunhes’s chunk of rock had merely been hit by lightning and that had shifted its dip? What if rocks could change their magnetic memory on their own, without any influence from the Earth’s poles?

It was this latter issue that dominated magnetic studies for decades after Brunhes’s paper. If a rock could spontaneously change its record of magnetic coordinates, then the whole idea that the field had reversed would be in question, as would many other aspects of rock magnetism. Before that question could be settled, other findings supporting Brunhes began trickling in from other parts of the world. Scientists had begun their meticulous job of collecting new data points. The most compelling findings were in a modest three-page paper in Proceedings of the Imperial Academy by the Japanese geologist Motonori Matuyama in 1929. A professor at Kyoto University, Matuyama also studied at the University of Chicago.

Japan is a global volcano hot spot. It sits at the juncture of four tectonic plates along what’s known as the Pacific Ring of Fire. Recently analyzed undersea marine sediments show that volcanoes have been active in the area for 10 million years and that the past 2 million years have been a period of extreme volcanic activity. In other words, the Japanese are keenly interested in what happens under the Earth’s crust, and that island nation has produced some of the world’s most eminent experts in all things inner-Earth.

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