New research has revealed that the Earth’s magnetic field very nearly vanished completely 565 million years ago and that a geological process may have saved it in the end, completely reversing its demise.
The Earth’s core was once liquid, but 565 million years ago it began a slow, solidifying process, and as a natural consequence of this action the magnetic field was both strengthened and saved, as Live Science reports.
If the Earth’s magnetic field had been utterly destroyed in the end, humans would have had a very difficult time existing as this important field helps to keep the planet free from otherwise deadly radiation and solar winds.
To learn more about what the core of Earth was like this long ago, scientists first began by looking at tiny crystal minerals called plagioclase and clinopyroxene that had been formed in eastern Quebec, Canada. Contained within the samples of these minerals were magnetic needles which were so small that they only measured in at around 50 to 100 nanometers in size. These needles are particularly helpful as once inside molten rock, they point to the magnetic field.
John Tarduno, the chair of the Earth and Environmental Sciences department and a professor at the University of Rochester in New York, explained, “Those tiny magnetic particles are ideal magnetic recorders. When they cool, they lock in a record of Earth’s magnetic field that’s maintained for billions of years.”
Once scientists put these crystals inside a magnetometer, they quickly determined that 565 million years ago these particles would have had an extremely low charge. So low, in fact, that at this point in time the magnetic field of the Earth was nearly 10 times weaker than it is in 2019. This is by far the weakest measurement of the magnetic field that scientists have ever measured, and suggests that it may have even disappeared completely if something hadn’t come to its rescue.
The measurements also demonstrated that there were an alarmingly high number of reversals of both the north and south poles, which Tarduno has called “highly unusual.”
“We were at this critical point where the dynamo almost collapsed completely.”
However, the core of our planet saved us in the end. Even though the Earth’s core was once liquid, scientists have estimated that between 2.5 billion years to 500 million years ago a solid layer took root in the center of the planet as iron began to freeze and harden. As the inner core continued to grow stronger, certain elements like magnesium, silicon, and oxygen were shuffled away and into the Earth’s outer core, which in turn created the convection that helped to power the magnetic field.
Peter Driscoll, an earth and planetary scientist at the Carnegie Institution for Science in Washington, D.C., has suggested that scientists involved in this new research “present intriguing paleomagnetic measurements” which have demonstrated just how weak the Earth’s magnetic field was 565 million years ago. Driscoll further noted that “the inner core may have occurred right in the nick of time to recharge the geodynamo and save Earth’s magnetic shield.”
The new study which has demonstrated that the Earth’s magnetic field was close to disappearing 565 million years ago has been published in Nature Geoscience.