Gigantic masses in the Earth’s mantle have existed for more than 4 billion years.

Research about the antiquity of the continental sized large low shear wave velocity provinces at the core-mantle boundary was published in Geochemistry, Geophysics, Geosystems: Primitive helium is sourced from seismically slow regions in the lowermost mantle by Curtis Williams, Sujoy Mukhopadhyay, Maxwell Rudolph and Barbara Romanowicz, and was featured in GeoSpace.