THE MINIMUM PROBLEM IN DATING DEGLACIATION: A STRATEGY FROM THE FORT MCMURRAY AREA, ALBERTBA

Radiocarbon age estimates from lake or bog bottom sediment commonly have been used to estimate the timing of deglaciation, however many studies suggest that these dates only provide a minimum age and may be one hundred to two thousand years younger than deglaciation. To reduce the minimization problem, a four-step strategy proposed using data from the Fort McMurray area aims to reduce these errors. The first step is to produce a geomorphic map of the area displaying key landforms to date deglaciation. The second step is to collect multiple sediment cores from specific sites that bracket each landform. Third, radiocarbon date multiple stratigraphic horizons within each core, radiocarbon date multiple samples at each stratigraphic level, and run Bayesian Analysis on each core. The final step to double-checking the spatial context of the data, is too create a proposed ice margin time distance diagram. This study uses 62 radiocarbon dates from 28 sites from the Fort McMurray area, Alberta. This method allows the data to be complied into five key sites and five key radiocarbon dates, which are then assigned to four distinct ice margin positions. In this case, the time distance diagram shows that the ice margin retreated approximately 100 km over a range of approximately 750-1000 radiocarbon years BP.