Geobiology is a new catch-phrase for the broad mix of science at the interface between the life and earth sciences. As with many interdisciplinary fields, it builds on a broad range of existing interdisciplinary and disciplinary research. Much of this research is microbial, exploring all of the ways that microorganisms influence the geology of the earth and how the earth influences the behavior of microbes. Bacteria "eat" rocks, they "breathe" rocks and they "make" rocks. This interaction between microbes and minerals covers such disparate topics as the early evolution of life on earth, the cycling of elements in the hydrosphere, the search for life on other planets and even novel strategies for bio-remediation! The field in its broadest context expands to cover the evolution of life at all levels and the synergies between molecular approaches to phylogeny and the richness of the fossil record. The USC program in geobiology is multi-disciplinary and although our work encompasses a vast array of research topics, there are several themes around which our program is organized: Microbial Ecology Biogeochemical Cycles Relating modern to ancient environments Biosignatures and life under adverse conditions Geobiological research by faculty within the Department of Earth Sciences occurs in all of these areas. In particular, we offer courses and provide research opportunities with a focus on BIOMASS—Biogeological Investigations Of Modern and Ancient Sedimentary Systems. We are a group with active field research programs and are currently working in: hydrothermal seep regions, alkaline lakes, anoxic marine basins, carbonate springs, polar ice, deserts, and surface ocean environments. We study rocks in China, Brazil and the western US; rocks aged 2.5 billion years old to modern sediments. We also focus on times in earth history when ‘snowball’ and ‘mass extinction’ events occurred. Students with broad interests in the biogeosciences are urged to apply. For more information about geobiology at USC, please visit the official site http://geobiology.usc.edu