Researchers have been able to reconstruct the evolution of Earth’s deep core over hundreds of millions of years by analyzing ancient rock crystals and the magnetic records that are stored inside of them.
The solid inner core of the Earth, a hot, compact glob of iron and nickel, is sandwiched between the molten outer core. The crust that we all live on is followed by the rocky mantle, which is the thickest of all the layers. We’re talking about a distance underground of 2,900 kilometers (1,800 miles).
According to the researchers’ results, it appears that approximately 550 million years ago, Earth’s inner core was beginning to crystallize into a sizable mass. The magnetic field, which had been reduced some 15 million years ago, was restored by the crystallization, which also created the ideal conditions for a massive burst of life.
The outer core’s whirling liquid iron is what controls Earth’s magnetic field, which shields life from dangerous solar winds. However, the solid iron-nickel alloy at the center also has a crucial function to play as an energy source, as this recent study makes apparent.
According to geophysicist John Tarduno of the University of Rochester in New York, “the inner core is really essential.” The magnetic field was on the verge of collapsing just before the inner core began to expand, but as soon as it did, the field was restored.
This study emphasizes the need of having a magnetic field maintained throughout a planet’s entire lifetime—many billions of years—by something akin to a developing inner core.
Scientists rely on crystals in rock, in this example feldspar crystals in anorthosite, to measure the Earth’s core because doing so would be nearly impossible due to the vast distances and extreme temperatures. These crystals serve as extremely precise magnetism recorders.
The researchers was able to determine the shift in magnetic strength, which represents a significant return of the Earth’s magnetic field, by comparing rocks that were dated at 565 million years ago to rocks that were dated at 532 million years ago. Although the transformation took tens of millions of years, this is a short period of time in geological perspective.
According to thermal models based on the findings, the inner core’s structure altered around 450 million years ago, separating the innermost from the outermost inner core. These times also line up with changes in the mantle.
We could investigate the possibility that the current inner core is made up of two sections since we more precisely confined the inner core’s age, said Tarduno.
The inner core was indirectly impacted by plate tectonic movements on Earth’s surface, and the structure of the inner core contains traces of these movements’ past.
Understanding how the inner core changed to its current condition might help us predict how it might change again in the future and provide a benchmark for comparison when researching other planets.
To see what would have occurred if the inner core hadn’t expanded and given Earth’s magnetic field the push it needed to become powerful enough to deflect dangerous solar radiation from the surface, we simply need to look at Mars.
Over the course of billions of years, the Martian atmosphere has been stripped away by solar winds because it lacks a worldwide magnetic field to protect it. This has also removed the water and oxygen necessary for life to properly develop.
If Earth’s magnetic field hadn’t been restored, “Earth definitely would have lost considerably more water,” claims Tarduno. “The world would be significantly drier and different from the planet as it is today.”