Lake Basal Ages and Origins from scientific literature, Circum-Arctic

This dataset is a compilation of 1,207 lake basal ages used to identify spatial and temporal patterns of lake formation across the high northern latitudes. Data was gathered from scientific literature descriptions of lake cores, peat cores underlain by lake sediments, and exposures within the domain of glaciation and permafrost extent during the Last Glacial Maximum. We distinguished eight classes of lake origin. Where not indicated by the author, we sought to determine lake origin from lithology, geological history and site descriptions within the text. Though most records (95%) were radiocarbon dated, we included robust dates obtained by a variety of methods including varve counting, photoluminescence, Pb/Cs, Th/U, wiggle matching and tephrochronology. We reported oldest sample ages in the majority of cases, electing not to utilize basal ages derived from age-depth models extrapolated beyond dated levels due to both their high level of uncertainty and differences between methodologies used to construct each model. We excluded dates from shallow lake cores that clearly did not reach basal lake sediments, or that were collected for the sole purpose of methods development or recent human impact studies. Records that did not include dates from lower-most cored sediments, that suffered from uncorrected reservoir effects (noted by original author) or that contained copious age reversals were also excluded. Some records provided distinct stratigraphic evidence of lake formation that allowed for exact determination of lake basal age, while other lithologies were more ambiguous. To address this uncertainty, we categorized each lake age as "minimum" or "basal" based on interpretation of contextual, geographical and lithological information.