Steps toward understanding the Earth's dynamic interior

During the two decades following the plate tectonic revolution, cartoons of mantle convection have become more refined and based on data from geochemistry and geophysics rather than on imagination. Successive Reports from the US National Academy of Sciences have given progressively greater prominence to the study of mantle convection. It was one of 8 topics selected as high priority studies in the 1983 report on "Opportunities for Research in Geological Sciences". It was a central topic in 1987 and 1988 Reports on "Earth Materials Research" and "Mission to Planet Earth''. With recent advances in isotope and trace element geochemistry, seismic tomography, geoid studies, and computer models of convection and fluid mechanics, we may be on the verge of obtaining a three-dimensional picture of the flow pattern in the Earth's mantle. The internal dynamic history of the Earth exerts a major control on most aspects of geology. Interactions between the dynamic mantle, the lithosphere and the ocean-atmosphere-biota system are important for understanding even short-term global changes. Continuation of multiple approaches to mantle dynamics must continue to yield fundamental results