Microbial activities influence water-rock interaction processes and chemical transport between the major geochemical reservoirs and the formation/transformation of minerals and rocks, whereas geological processes and geochemical controls influence the microbial ecology in extreme environments. How biological activity influences geological processes and what role these processes played in the geological evolution of the Earth are fundamental questions. How do we recognize the ancient microbial activities in the rock record and what analytical methods do we use to document them to better...