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Anti-aristarchus [soylentnews.org] writes:

Maybe. Story at Extreme Tech" [extremetech.com], which is either extreme, or tech, but not both?

There are two enormous provinces of unusual rock that sit at the bottom of the mantle, just above the Earth’s core. One of them is located underneath Africa and one is under the Pacific Ocean. They’re called Large Low Shear Velocity Provinces (LLSVPs) and they may shape hotspot formation and volcanic activity across the globe.

The LLSVPs are areas where seismic shear waves propagate much more slowly. They extend laterally for thousands of miles (we think), and they may be up to 1,000km “tall.” Geologists have considered a variety of potential explanations for the origin of the LLSVPs, and now a team has put forth a new argument: The LLSVPs may represent the remains of Theia, the protoplanet thought to have smashed into the world some 4.5 billion years ago, creating the Moon. There are a number of hotspots around the world associated with the margins and boundaries of the LLSVPs:

Graphic here. Paper here [sciencemag.org]

If the LLSVPs or ultra-low-velocity zones prove to be of extraterrestrial origin, it would mean the planetesimals that helped form the Earth have continued to shape its geology ever since. It’s one thing to know the Moon was created in an impact some 4.5 billion years ago, and another to imagine that some of the core of the planetesimal that shaped our entire Earthly existence might still exist itself, trapped below an ocean of liquid rock.

One, of course, is in the Pacific, close to being between Auz and Kiwi, where being Ancient, it sleeps.

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