Changing views on earth's deep mantle

Abstract

While spacecraft travel ever farther in space, the rocky world deep below us remains mysterious. Yet, the present-day state and dynamics of Earth’s interior hold the keys to understanding the early conditions of the solid Earth and its biosphere, hydrosphere, and atmosphere, and how these have evolved to the planet we now know. Earth’s stable stratification into crust (between 5 and 70- km thick), mantle (from base of crust to ~2890-km depth), and core (2890- to 6371-km depth) has been known for half a century from seismic velocity measurements, but characterizing the heterogeneity within and the interaction between these concentric shells is a frontier of modern, cross-disciplinary research. On page 853 in this issue, Trampert et al. break new ground with compelling evidence for large-scale variations in composition in Earth’s mantle.