Dormant endospore forming anaerobic thermophiles in permanently cold marine sediments can be used as a tool for studying lateral temporal biogeography and highlighting potential vectors for passive dispersal associated with warm, anoxic environments in the deep biosphere. This project will evaluate the presence and diversity of thermophilic Firmicutes at marine sediment sites in the North Atlantic using high temperature incubation. Knowledge gained from this study will highlight the importance of dispersal in marine microbial biogeography.