Norwegian geologists found that during the Mesozoic era, Earth’s poles shifted sharply three times. According to their calculations, such episodes occurred 190–200, 140–150, and 90–110 million years ago.
An article with these findings was published in Science; TASS reports this. The study was conducted by a team of geologists led by Associate Professor Matthew Domeier of the University of Oslo in Norway.
The authors developed a way to search for traces of sharp shifts in Earth’s geographic poles. The method is based on the fact that a change in the axis of rotation is reflected differently in the elevation of land and sea areas located closer to or farther from the old and new equator.
On this basis, the scientists analyzed how sea level and coastlines changed over the past 540 million years — from the Cambrian explosion to the present day. In these data, they identified four episodes of a sharp shift in Earth’s axis.
Three of them occurred in the Mesozoic era: about 190–200 million years ago, 140–150 million years ago, and 90–110 million years ago. The fourth episode, according to the authors’ calculations, dates to the boundary between the Oligocene and Miocene, about 20–30 million years ago, although the researchers themselves allow that it may have been weak or may not have existed at all.
According to the authors’ estimate, in each such case Earth’s axis shifted by more than 2.5 degrees per million years. They also write that the results cast doubt on the idea that the rapid movement of the supercontinent Pangaea can be explained by a gradual shift of the poles; further study of these episodes, the researchers say, will help understand their impact on the planet’s appearance and the evolution of life.
