A recent study suggests that the deepest layer of the earth was formed somewhere around 1 billion to 1.5 billion years ago.
Earth’s inner core has been a topic of vigorous scientific debate for many years, which was estimated to be built around 2 billion years ago. But, a new study finds that Earth’s inner core is not as old as it was previously thought.
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The deepest layer of the Earth was formed somewhere around 1 billion to 1.5 billion years ago when the liquid iron spreading at the surface started to freeze.
Earth’s inner core is like a solid ball of iron with a radius of 1,220 kilometers, which is just larger than the dwarf planet Pluto and is surrounded by a liquid outer core.
Researchers from University of Liverpool analyzed ancient igneous rocks (formed through the cooling and solidification of magma) and found the evidence of sharply increased magnetic field between 1 and 1.5 billion years ago. The increased magnetic field is an indicator of when Earth’s innermost part started to freeze out from the cooling molten outer core.
The latest analysis is radically different and is challenging previous estimations about Earth’s interior and its history, which range from half a billion to nearly two billion years ago.
“The timing of the first appearance of solid iron or “nucleation” of the inner core is highly controversial 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,” Dr. Andy Biggin, Liverpool palaeomagnetism and lead author of the study, said.
“The result suggests that the Earth’s core is cooling down less quickly than previously thought which has implications for the whole of Earth Sciences. It also suggests an average growth rate of the solid inner core of approximately 1 mm per year which affects our understanding of the Earth’s magnetic field.”
Earth’s magnetic field is produced by the motion of liquid iron alloys in the outer core. Once the core loses heat and starts to freeze, it generates the phenomenon of convection and eventually leads to motion. The process is still continuing and working as a source of generating Earth’s magnetic field.
“The theoretical model which best fits our data indicates that the core is losing heat more slowly than at any point in the last 4.5 billion years and that this flow of energy should keep the Earth’s magnetic field going for another billion years or more.”
The study was published in Nature.