“This is an exciting finding,” Richard Gordon said of his research with his former student Daniel Woodworth

NEED TO KNOW

• Researchers used ancient sea level changes to track shifts in Earth’s orientation relative to its spin axis, according to a study released Oct. 1
• The study found that a major reorientation occurred roughly 48 million to 56 million years ago
• Scientists say the poles are currently moving about 10 centimeters per year

Earth’s true North and South poles are moving at a faster rate than before, according to a new study. 

Over the past 320 million years, true polar wander has occurred four times, the Smithsonian Magazine reported on Monday, Oct. 19, citing a recent study by the journal Science.

While true polar wander has proven difficult to detect with standard approaches using paleomagnetic measurements, researchers have found a new strategy that determines movement in the Mesozoic Era using reconstructions of sea level as a proxy, per the journal.

“True polar wander (TPW) is presently occurring at a rate of ~10 centimeters per year, exceeding the mean rate of differential plate motion,” the study continued, adding that it’s currently unclear whether Earth has experienced rapid TPW lasting millions of years.

“Rapid TPW will induce global sea level fluctuations associated with relative changes in centrifugal potential,” researchers said, while discussing how things have moved away from the center or axis.

Rice University’s Richard Gordon, one of the research leads, found evidence of true polar wander after being curious about deep-mantle sources of volcanoes in Hawaii.

“The debate about what movement caused this bend is quite heated,” Gordon, the W.M. Keck Foundation Professor in Geophysics, Earth, Environmental and Planetary Sciences, said in a press release published earlier this month. 

“My former student Daniel Woodworth and I were approaching it from a new angle, relying on a new paleomagnetic pole combined with a dataset that had taken us decades to collect and create,” he continued.

He and Woodworth ended up discovering proof from a surprising location, one with much lower temperatures than they’d initially expected.

“When I was a student, many geophysicists assumed that the solid Earth does not change its location relative to the spin axis,” Gordon said. “Even today, some geologists think that Earth’s orientation relative to the spin axis hasn’t significantly changed in the past 100 million years.”

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Woodworth said he and Gordon made a fascinating discovery.

“Our results indicate that around 56-48 million years ago, the entire solid Earth reoriented relative to the spin axis, which gave us the jump found in the paleomagnetic record,” he said.

“This is an exciting finding,” Gordon added. “These data indicate that contrary to some current thought, substantial true polar wander could have happened as recently as 48-56 million years ago.”

The four time points that stood out were the Oligocene to Miocene, about 20 million to 30 million years ago; the mid-Cretaceous, about 90 million to 100 million years ago; the Late Jurassic to Early Cretaceous about 140 million to 150 million years ago; and the Early Jurassic, about 190 million to 200 million years ago.

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