Blobs!

The Unsolved Mystery of the Earth Blobs

THIS LONG ARTICLE discusses two continent-sized structure found at the mantle - core boundary. These blobs, officially LLSVP or Large Low Shear Velocity Provinces, have been known since the 1970s, but although we know more about them now, we still don't know what they are, where they came from, how long they have been around, or what they do.

What lies below? A cutaway of Earth down to the liquid core shows the swirling mantle rock (dark blue). Made from a numerical convection model, the image shows mysterious structures underneath the Pacific Ocean that some researchers believe hold the clue to unlocking mysteries of Earth’s past (light blue). Credit: Mingming Li/Arizona State University

There is a lot of detail in the article and it is well worth reading.