2024 GSA PENROSE MEDAL: SVALBARD AND THE EDUCATION OF A GEOBIOLOGIST

Glacial valleys of the Svalbard Archipelago expose more than six kilometers of well-preserved Neoproterozoic sedimentary rocks, well north of the Arctic Circle. Field-based research on these rocks, first through the generosity of Brian Harland and later with Keene Sweet, provided me with invaluable on-the-job training in geobiology. Originally inspired by paleontological possibility, I found that cherts in silicified peritidal carbonates of the Akademikerbreen Group contain diverse benthic microfossils, mostly cyanobacteria, with variations among samples reflecting both taphonomy and position along an environmental gradient. Nick Butterfield, then a graduate student, added immensely to this picture, showing that shallow subtidal shales preserve a distinct fossil assemblage dominated by unicellular and simple multicellular eukaryotes; Proterozoic fossils vary in space as well as time. A chance discussion with John Hayes led to new geochemical horizons in which we demonstrated an unexpected pattern of strong carbon isotopic variation in Neoproterozoic carbonates (and, later, the absence of comparable variation during most of the preceding billion years). Further paleoenvironmental collaborations would follow. All in all, Svalbard research taught me that progress in understanding the early Earth requires the collaborative integration of paleobiology (informed by phylogeny) and geochemistry, both set within a carefully observed stratigraphic framework.