Posted on 10/26/2021 6:19:34 AM PDT by Red Badger
We know that true polar wander (TPW) can occasionally tilt whole planets and moons relative to their axes, but it's not entirely clear just how often this has happened to Earth.
Now a new study presents evidence of one such tilting event that occurred around 84 million years ago – when dinosaurs still walked the Earth.
Researchers analyzed limestone samples from Italy, dating back to the Late Cretaceous period (100.5 to 65.5 million years ago), looking for evidence of shifts in the magnetic record that would point towards an occurrence of TPW.
Bacteria fossils trapped in the rock, forming chains of the mineral magnetite, offer some of the most convincing evidence yet of true polar wander in the Late Cretaceous – and it may help settle a scientific debate that's been going on for decades.
How true polar wander looks. (Victor C. Tsai/Wikimedia Commons/Public Domain)
"This observation represents the most recent large-scale TPW documented and challenges the notion that the spin axis has been largely stable over the past 100 million years," the researchers explain in their paper.
Earth is made up of a solid metal inner core and a liquid metal outer core, with a solid mantle and crust (the surface) moving slowly around on top of the liquid metal. Earth's magnetic field, generated by the outer core, is recorded in rocks like the ones studied here.
True polar wander is when the geographic poles shift substantially, so the outer wrapping of Earth tilts over. Nothing actually changes in terms of Earth's magnetic field, but the shifting rocks will record different paleomagnetic data as they move.
That data reveals the distance to the North and South geographic poles, enabling researchers to plot where these poles actually are. A fully vertical field means a rock was at the pole, while a fully horizontal field indicates it was at the equator.
"Imagine looking at Earth from space," says geologist Joe Kirschvink, from the Tokyo Institute of Technology in Japan. "True polar wander would look like the Earth tipping on its side, and what's actually happening is that the whole rocky shell of the planet – the solid mantle and crust – is rotating around the liquid outer core."
Part of the extraction work. (Ross Mitchell)
According to the study, there was around a 12 degree tilt on Earth around 84 million years ago, which was corrected relatively quickly – within about 5 million years, the equivalent of a "cosmic yo-yo" in the words of the researchers.
What that means is that these rocks – and Italy itself – took a journey towards the equator before tipping back.
The team says that previous studies hinting that true polar wander didn't happen during the Late Cretaceous simply didn't gather enough data from the geological record – something that can't be said about the latest research.
"That is one reason why it is so refreshing to see this study with its abundant and beautiful paleomagnetic data," says geophysicist Richard Gordon, from Rice University in Houston, who wasn't involved in the study.
The research has been published in Nature Communications.
Mmmm-buzz-click. Roger Ramjet was one of the great cartoons.
On January 13, 2011 the north/south runway at Tampa airport was renumbered due to magnetic polar shift.
Well, you’re not wrong about public education — schools today are terrible. Heck, my niece can’t read an analog clock, and she thinks cursive is Elvish writing from Tolkien’s Middle-earth!
Even though this happened such a long time ago, it was still Trump’s fault.
It will be Perpendicular to the axial rotation orthogonal status quo....................
I would imagine anywhere on Earth would be quite an adventure........................
“Axes”-plural of “axis”
Public schools, you were saying?
Technically you are correct, though, a rotating sphere has one axis, geometrically.
At least two....................Inside and outside..................
Somehow, someway it was Trump’s.......................
Are you being Political,/s
Grant Money is forever. Wonder how many will benefit from this unprovable event.
The Magnetic Poles have always moved. They are not constant..............
Exactly...
For all of those folks that have a hard time understanding “Climate Change”, it is the tilt on the earth’s axis that causes the four seasons (just the way God designed it), and the intensity of the sun. We have had climate change for at least 4.8 billion years. Occasional fluctuations in CO2 have affected the atmosphere, but always changes, regardless of man and animal’s contributions.
Even though this happened such a long time ago, it was still Trump’s fault.
—
T-Rex’s fault
“Claiming the angular momentum of the earth is less stable than the magnetic field is bizzare.”
They didn’t claim that!
“The total angular momentum of the earth is very difficult to shift.”
A total angular momentum didn’t shift.
Note that during the time of the VIKINGS, around 1000 AD, the Magnetic Pole and True North Pole were aligned....Then, around the time of Columbus, 1500 AD, the mag Pole shifted WEST............. Like God planned it that way..............
Right.
Are you claiming crust of the earth shifting 15 degrees from where it was, did not change the total angular momentum of the earth? Nice trick.
Two sides - inside and outside.
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