Schoolchildren have long learned that the Earth is made up of four main layers: the crust, mantle, outer core, and inner core. But a new study suggests their textbooks may be incomplete.
Researchers at the Australian National University (ANU) have discovered a mysterious new layer at the center of the planet: the “deepest inner core”.
They suspect that it contains secrets about an unknown and dramatic event in Earth’s history.
Geologists first proposed the idea of a fifth layer decades ago, but had already struggled to detect it.
The new study uncovered additional evidence by analyzing changes in seismic waves as they travel through the core of our planet.
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The team used a research algorithm to compare thousands of models of the inner core with travel time data for seismic waves.
They found changes in the structure of iron about 650 km from the center of the Earth – indicating the presence of an additional layer.
“We found evidence that could point to a change in the structure of iron, possibly suggesting two distinct cooling events in Earth’s history,” study author Joanne Stephenson said in a communicated.
The details of these events remain somewhat mysterious. But Stephenson believes that further analysis could deepen our understanding of Earth’s evolution:
This is very exciting – and it could mean that we have to rewrite the manuals!
You can read the study paper in the Geophysical Research Journal: Solid Earth.
Published March 5, 2021 – 15:53 UTC