The Earth was tilted to one side and restored itself between 79 million and 86 million years ago, a study shows.
The Earth was tilted 12 degrees around 84 million years ago, at the end of the Cretaceous period when the tyrannosaurs and triceratops were dominating the planet then restored itself.
“Earth’s 12-degree tilt could affect latitude similarly,” Sarah Slotznick, a geobiologist at Dartmouth College and co-author of the new study, told Business Insider. With this tilt of the Earth, then almost New York City, USA, would be where Tampa, Florida, is now.
The researchers found that, between 86 and 79 million years ago, the crust and mantle rotated around the Earth’s outer core and back, causing the entire planet to tilt and then flip over itself like a flipper. play.
Scientists can piece together a picture of where tectonic plates were millions of years ago by analyzing paleogeomagnetic data.
As the lava at the junction of two tectonic plates cools, some of the rock formations contain magnetic minerals that match the orientation of the Earth’s magnetic poles at the time the rock solidified.
Even after the plates containing the rocks moved, researchers were able to study this magnetic alignment to analyze where on a global map natural magnets existed in the past. .
The team examined the magnetic alignment of ancient limestone collected in Italy and found that the Earth’s crust moves about 3 degrees every million years during its tilt and flip.
Think of the Earth like a gyroscope: If the weight of the upper part were evenly distributed, it would rotate perfectly, without wobbling. But if some mass shifts to one side or the other it will change the center of gravity of the crest, resulting in it tilting towards the heavier side while rotating.
According to researcher Slotznick, the accumulation of hot rock and magma – known as the mantle plume – from the outer core towards the crust may have played a role in changing the distribution of Earth’s mass during the Cretaceous period. late white.
Co-author Ross Mitchell, a geophysicist at the Chinese Academy of Sciences, noted that shifting tectonic plates could explain the ancient Earth’s 12-degree tilt. As hotter, less dense matter from deep within the mantle rises toward the crust, and colder, denser matter sinks toward the core, tectonic plates can collide. When a collision occurs, one array will sink below the other.
Before the Late Cretaceous , the Pacific Plate – the largest tectonic plate on Earth spanning millions of square kilometers under the Pacific Ocean – was submerged under another plate to the north. About 84 million years ago, the Pacific Plate began to sink in a different direction, under another plate to the west. This shift may have altered the balance of the Earth, according to Mitchell. Therefore, he was not surprised when the Earth reversed direction and tilted backward.
“The outer layer of the planet behaves elastically like a rubber band and will return to its original shape after deviating from the axis,” he said.