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The land is not always steep. About 84 million years ago, at an event called “Cosmic JoJo”, the planet’s crust turned sideways and back again.
The real name of the nucleus is the true polar layer (TPW), which is the outer layers of the planet or The moon It moves around its center, tilting the shell relative to the axis of the object. Some researchers have previously speculated that TPW may occur Earth From late Limestone period, 145 million to 66 million years ago, but this has been hotly debated, says A.J. According to researchers.
However, the new study strongly points out that TPW takes place on Earth. Researchers looked at the ancient motion of the earth’s crust and mapped it Magnetic field Data trapped in ancient fossils Bacteria. About 84 million years ago, they discovered that the planet tilted 12 degrees compared to its axis and would fully return to its original position in the next five million years.
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“This observation reflects and challenges the latest widely documented TPW [Earth’s] The axis of rotation has largely been stable over the last 100 million years, ”the researchers wrote in an article published in an online journal on June 15. Natural compounds.
Cosmic JoJo
The earth has four main layers: solid inner core, liquid outer core, shell and crust. During TPW, the entire planet appears upside down, but in fact only the outer layers have moved.
“Imagine looking at the Earth from space, the TPW would be like the Earth turning sideways,” said Joe Kirchwing, a geologist at the Tokyo Institute of Technology in Japan and a professor at Caltech. . “What’s really going on is the whole rock crust of the planet [the mantle and crust] It revolves around the outer center of the fluid. “
Some fragments of the Earth’s outer layers are constantly moving and changing Tectonic plates They collide with each other and go down; But during TPW, the outer layers move together as a unit.
As a result, the collapse of the Earth’s crust would not have caused any major tectonic activity or drastic changes in key ecosystems. On the contrary, it may have been a gradual process that did not affect me Dinosaur And other creatures roaming the surface.
Earth Electromagnetic field It would have been fixed during TPW because it was created by a fluid inner core, which would be in place. So instead of moving the magnetic poles, the geographic poles begin to browse.
Dilapidated magnet
To test whether the earth was exposed to TPW during Cretaceous, researchers have turned to magnetic ores in limestone deposits in Italy.
Sarah Slotsnica, a geographer at Dortmouth College in New Hampshire, said: “These Italian deposits prove to be very special and reliable.
Magnetite is a very magnetic form Iron– Oxide. Some bacteria can form chains of tiny magnetite crystals that, when formed, naturally conform to the Earth’s magnetic field. When this particular bacterium dies and decomposes during the TPW period, these magnetite chains are blocked.
As the Earth’s crust moved through the TPW, not its magnetic field, these magnetic fossils (which were on the planet’s surface layers) revealed how much the Earth’s crust moves over time compared to the Earth’s. The team found that the Earth’s crust moved about 25 degrees in 5 million years.
Researchers now hope that their findings will solve the question of whether TPW existed on Earth during the Cretaceous.
Richard Gordon, a geophysicist at Rice University in Houston, who was not involved in the study, said: “It is refreshing to see this study with its rich and beautiful magnetic data.
First published in Live Science.
