Scientists of the University of Liverpool in the UK provided evidence of the existence of the Earth’s magnetic field cycle. The change of magnetic poles of the planet takes 200 million years. This is reported in the article published in the journal Proceedings of the National Academy of Sciences.
Researchers conducted a paleomagnetic analysis of rock samples from the ancient Lava flows in East Scotland collected over the past 80 years to measure the power of the geomagnetic field from 200 to 500 million years ago. It turned out that between 332 and 416 million years ago, the power of the geomagnetic field was less than a quarter from the modern level and was similar to the previously identified period of the low tension of the magnetic field, which began about 120 million years ago. This period is called middle-power dipole low level (MPDL).
Results support the theory that the power of the magnetic field of the Earth is cyclical and weakens every 200 million years, the idea proposed in the previous study conducted by the University of Liverpool’s Socked Group in 2012. However, at that time there was no reliable data on the field strength up to 300 million years ago.
A recent study disclosed that the mass extinction in the Devonian-coal period is associated with elevated levels of ultraviolet, which coincides with the radiation levels at MPDL. The weak magnetic field is associated with the change of magnetic poles.