Earth Core: Ancient Rocks Help Tell the Age of Our Planet's Guts

Earth's core could be as old as one to 1.5 billion years, according to ancient rocks studied by a group of researchers whose findings were published in the science journal Nature.

The study of the ancient rocks has allowed scientists to better guess when the Earth's inner core was formed, according to ABC News. Before, estimates ranged widely from 500 million to two billion years.

Researchers from the University of Liverpool said in the Nature study that the Earth's inner core started to become solid while it was surrounded by a molten iron outer core. The inner core is the planet's deepest player and a source of constant debate by scientists, said a university statement.

By analyzing ancient igneous rocks, the researchers found there was a sharp increase in Earth's magnetic field when the core was formed.

"This finding could change our understanding of the Earth's interior and its history," said Andy Biggin, the lead author of the study.

"The timing of the first appearance of solid iron or 'nucleation' of the inner core is highly controversial," said Biggin. "But is crucial for determining the properties and history of the Earth's interior and has strong implications for how the Earth’s magnetic field – which acts as a shield against harmful radiation from the sun, as well as a useful navigational aid – is generated."

The planet's magnetic field is generated by the liquid iron alloy's motion in the outer core. The motion happens because the core is losing heat to the overlying solid mantle that extends up to the crust, said the study.

"The results suggest that the Earth's core is cooling down less quickly than previously thought which has implications for the whole of Earth sciences," said Biggin.

The researchers' work suggests that the flow of energy from the Earth's inner core will likely provide Earth with a strong magnetic field for another one billion years or more.

Biggin said this is different from Mars, where the magnetic field appeared to have died after a half-billion years.


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