Uncovering Hidden Ancient Ocean Floor in Earth's Depths.

Scientists have discovered that ultralow-velocity zones (ULVZs) at the base of Earth's mantle, where seismic waves slow significantly, may be more widespread than previously thought and could be the remains of ancient ocean floor. ULVZs are poorly understood, and their origins are debated. The researchers analyzed seismic waves traveling through Earth's interior from earthquakes happening around the globe and found ULVZs at the core-mantle boundary all over the Southern Hemisphere. The results could shed light on how ULVZs affect the movement of heat within Earth and help scientists understand why hot spots form where they do.