A Tree-Ring Chronology and Paleoclimate Record for the Younger Dryas-Early Holocene Transition from Northeastern North America

Spruce and tamarack logs dating from the Younger Dryas and Early Holocene (YDEH; approx. 12.9 - 11.3k cal a BP) were found at Bell Creek in the Lake Ontario lowlands of the Great Lakes region, North America. A 211-year tree-ring chronology dates to approx. 11 755 -11 545 cal a BP, across the YDEH transition. A 23-year period of higher year-to-year ring-width variability dates to around 11 650 cal a BP, infers strong regional climatic perturbations and may represent the end of the YD. Tamarack and spruce were dominant species throughout the YD - EH interval at the site, indicating that boreal conditions persisted into the EH, in contrast to geographical regions immediately south and east of the lowlands, but consistent with the Great Lakes interior lowlands. This infers that Bell Creek was at the eastern boundary of a boreal ecotone, perhaps a result of its lower elevation and the non-analog dynamics of the Laurentide Ice Sheet. This finding suggests that the ecotone boundary extended farther east during the YD - EH transition than previously thought.