A diagram showing how Earth's crust and upper mantle (together known as the lithosphere) could be dripping into the mantle due to the Farallon slab. (Image credit: Hua et al. Nature Geoscience ...

Beneath the American Midwest, on the continent of North America, the underside of Earth's crust is dripping into the planetary interior. There, blobs of molten rock are coalescing in the upper mantle ...