✦ Mural in the Elihu Root Hall, Carnegie Institution for Science, Washington, DC. (photo: David Keith)

Steve's past, current and future studies reflect the diversity of continental rocks, encompassing a range of studies such as continental volcanic rocks, ancient and present subduction zones, crust-mantle evolution now and in the past, the mantle keels to the continents, and rocks from the present oceanic mantle. The study of continents using the deepest-derived rocks (xenoliths in kimberlite) led to Steve's recent interest on diamonds. Diamonds and their inclusions are rare specimens that usually come from the mantle keels of continents at depths greater than 150km. But a small fraction, known as superdeep diamonds, derive from greater depths including the mantle transition zone and the top of the lower mantle. A particular contribution of Steve’s is to use patterns of diamond formation age, inclusion mineralogy, and location relative to geologic setting to extract large-scale constraints on continent evolution and mantle geodynamics.