Professor John Parnell, School of Geosciences, University of Aberdeen
Scotland has numerous fossil deposits of international importance for their contribution to understanding the evolution of life. However, the story of life on Earth is largely subsurface: only since the evolution of land plants in the last 10% of Earth’s history has the locus of biomass shifted to the planetary surface.
Over the last two decades, the life sciences community has recorded a huge body of evidence for a global subsurface biosphere extending today to several kilometres depth. Scotland offers strong potential for the study of this deep biosphere in the geological record, using a range of evidence such as organic biomarker evidence for subsurface biodegradation; isotopic evidence for microbial colonization in the subsurface; metal concentrations in red beds attributed to bacteria; and preservation of microbial filaments in fracture-fill vein minerals. We will look at examples of this evidence from Scotland, and put them in a wider context of planetary habitat.