We are engaged in field, geochronologic, geochemical, and theoretical studies of Silicic Magmatism and Volcanology--studying the life histories of the crustal magma bodies that give rise to large, explosive eruptions that spread ash continent-wide. Another focus of our research is Geoarchaeology--the application of concepts and methods of the earth sciences to archaeological problems. It provides evidence for the development, preservation, and destruction of archaeological sites, and for regional-scale environmental change and the evolution of the physical landscape, including the impact of human groups.