We all learned the layers of the Earth in middle school, but it looks like the science textbooks might need a bit of a revision.
A study published in Nature Geoscience focuses on a new layer of the Earth that has remained undiscovered until now. Scientists believe the new layer is part of the lower mantle, where the rock gets three times stiffer, which researchers say could explain why slabs of Earth’s sinking tectonic plates sometimes stall and thicken when they reach 930 miles underground.
For the sake of reference, the Earth’s crust reaches just 20-30 miles down on land, and approximately four miles thick in the ocean. Below that? We kind of know what’s there (i.e. mantle, outer core, inner core), but a lot of the details remain a mystery. Here’s how Lowell Miyagi, an assistant professor of geology and geophysics at the University of Utah, explained the findings:
"The Earth has many layers, like an onion. Most layers are defined by the minerals that are present. Essentially, we have discovered a new layer in the Earth. This layer isn’t defined by the minerals present, but by the strength of these minerals.
The result was exciting. This viscosity increase is likely to cause subducting slabs to get stuck – at least temporarily – at about 930 miles underground. In fact, previous seismic images show that many slabs appear to ‘pool’ around 930 miles, including under Indonesia and South America’s Pacific coast. This observation has puzzled seismologists for quite some time, but in the last year, there is new consensus from seismologists that most slabs pool."
According to Popular Science, the team made the discovery by using a diamond anvil to apply massive amounts of pressure to rocks commonly found in the mantle. That process revealed that the strength of the rocks increased to 300 times when pressure is applied at the same levels found at the 930-mile depth.
So, yeah, be sure to go back and school your middle-school science teacher next time you get a chance.
(Via Popular Science)