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Jan. 15, 2015

Going to great depths to solve the Earth’s ancient mysteries

A Michigan State University faculty member and four of her students have been spending the past few weeks sailing the western Pacific Ocean.

But for them there was no time for suntans and exotic ports of call. Not when you’re trying to solve one of the Earth’s most puzzling mysteries, a mystery millions of years old.

Masako Tominaga, an assistant professor of geological sciences, and her intrepid students, including undergraduates John Greene and Tyler Ruchala, have been sailing from Hawaii to Guam on board the R/V Sikuliaq, a National Science Foundation research vessel.

Their mission: To determine that during the Earth’s Jurassic period the planet’s magnetic polarity turned around suddenly. And often. In other words, how and why the North Pole became the South Pole. And vice versa.

The last time this reversal of the Earth’s magnetic field occurred was about 780,000 years ago, Tominaga said. However, what she and her team are trying to find out is if this phenomenon took place during the Earth’s Jurassic period, a time of about 150 million years ago when dinosaurs ruled the planet.

“Ultimately we’d like to confirm that the Earth’s magnetic field had anomalously fast reversals during that period,” she said. “For a long time it was generally assumed that there were no reversals during that period of the Earth’s history.”

She said that recent research, coupled with the work she and her students are doing, is indicating that these assumptions need to be revisited.

The work is being done with the help of three magnetometers, devices that measure the strength and direction of a magnetic field. The magnetometers will measure magnetic activity at three levels – near the surface of the ocean, mid-way between the surface and the ocean floor, and along the ocean floor.

“The seafloor spreading at mid-ocean range occurred because of volcanic eruption over time,” Tominaga said. “And when this molten lava formed the seafloor, it actually recorded ambient geomagnetic data.

“So when you go from the very young ocean seafloor right next to the mid-ocean ridge to very old seafloor away from the mid-ocean ridge, data from a magnetometer unveils changes in the geomagnetic field recorded by the ocean floor for us.”

So why does this matter? If the North and South Poles are flipped, it could impact some computers and navigational systems, not to mention compasses. Also, organisms that use magnetic fields to navigate — birds, bacteria, bees — might find themselves confused.

There also is the possibility that our magnetic field will be significantly weakened during the reversal process, which would leave us — and more importantly, our atmosphere — vulnerable to the eroding effects of highly charged solar particles (solar wind).

“Earth’s geomagnetic field is a shield,” Tominaga said. “It protects us from magnetic storms – bursts from the sun – so very pervasive cosmic rays don’t harm us.

“Our research will provide data to understand how changes in the geomagnetic field have occurred over time and give us important clues to understand the planet Earth as a whole,” she said.

Other MSU students who took part in the project are Timothy Stadler, a master's student studying geological sciences, and Matthew Karl, a doctoral student in geological sciences.

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By: Tom Oswald