October 20, 2021 14:11 GMT
The researchers note that the motion that our planet went through was 12 degrees and then returned to its initial position over the course of about five million years.
An international team of researchers has found important evidence that the Earth passed through A true polar shift In the Cretaceous period, about 84 million years ago, the Tokyo Institute of Technology announced on Tuesday in a release.
Scientists have long studied the movement of tectonic plates in the Earth’s crust. However, in this research, specialists analyzed Combined movement of the cortex and mantle Above the planet’s liquid outer core. Since the core is responsible for generating the Earth’s magnetic field, any significant change can also affect the displacement of the poles, which remain aligned with the axis of rotation.
“Imagine looking at Earth from space. A real polar shift would look as if the Earth were tilting on its side, and what actually happens is that the entire rocky layer of the planet (the solid mantle and crust) orbits around a liquid outer core,” explains one of the team, Joe Kirschvink.
For decades, the evidence for the existence of this process in Earth’s history has been controversial. To solve the question, the researchers studied crystals Magnetita On the rocks of that period chalky, About 145.5 and 65.5 million years ago, in the Apennine Mountains (Italy). The crystals of this mineral, formed by some bacteria, align according to magnetic lines “like little compass needles”, which makes it possible to understand where the magnetic north pole was at the time of its solidification.
Sample analysis showed that about 84 million years bent planet crust 12 degrees. And over the course of nearly five million years, the planet has returned to its initial position.
“This observation represents the latest large-scale documented true polar shift and casts doubt on the theory that the axis of rotation has been largely stable over the past 100 million years,” Indicates The scientists in their work published in the journal Nature Communications.
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