Earth's magnetic field is the magnetic force flow into the northern hemisphere and out of the southern hemisphere. According to Physical Geology, Earth's magnetic field s generated within the planet's outer core by the convective movement of liquid iron.

But the magnetic field is not stable over geological time. In the past, scientists have often wondered why magnetic field delays periodically happen. Scientists have noticed magnetic field reversals in Earth's records and that their timing was regular.

Now, researchers from the University of Liverpool found new evidence that proves the 200-million-year-long cycle of the Earth's magnetic field.

 Earth's Magnetic Field Have A 200 Million-Year-Long Cycle As Found From Rock Samples in Ancient Lava
(Photo: Wikimedia Commons)
Artist's rendition of Earth's magnetosphere.

200 Million-Year-Long Cycle of Earth's Magnetic Field

Space Daily reported that the new study offers further evidence of the 200-million-year-long cycle in the strength of Earth's magnetic field. The team performed thermal and microwave techniques in analyzing the rocks from ancient lava flow in Eastern Scotland to measure the strength of the geomagnetic field in a period where no reliable data exists.

Moreover, they also analyzed all the measurements from 200 to 500 million years ago that were collected in the past decades. They found that the strength of the geomagnetic field preserved in these rocks from 332 and 416 million years ago was less than a quarter than it is today, but similar to the low magnetic field strength from 120 million years ago during the Mid-Palaeozoic Dipole low (MPDL).

The study, titled "Intensity of the Earth's Magnetic Field: Evidence for a Mid-Paleozoic Dipole Low" published in the Proceedings of the National Academy of Sciences (PNAS), supports the theory that the strength of Earth's magnetic field is cyclical and weakens every 200 million years and connects to deep Earth processes.

This idea was first proposed by researchers in 2012 but was not proven due to the limitations of time and lack of reliable field strength data available from more than 300 million years ago.

"Our findings, when considered alongside the existing datasets, support the existence of an approximately 200-million-year long cycle in the strength of the Earth's magnetic field related to deep Earth processes," Liverpool paleomagnetist Louise Hawkins said in the university's news release.

ALSO READ: Did a Magnetic Field Reversal 42,000 Years Ago Cause Climate Disaster?


Reversals Tend to Happen Every 200 Milion Years

According to Science Alert, Earth's magnetic field is due for another reversal if the cycle holds true and magnetic pole flips and reversals tend to happen every 200 million years. However, scientists are unsure yet of what will happen or its effect on all technology and gadgets at that time.

Researchers said that the more people know about the history of Earth's magnetic field, the better they could understand Earth's processes and predict the next event. The magnetic field protects the Earth from harmful solar radiation and knowing when the magnetic field will develop problems will help people prepare.

More so, the team thinks that their findings further support that a weak magnetic field is linked to pole reversals and it is generally strong during a Superchron that lasts at least 10 million years.

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