DATING OF GLACIAL SEQUENCES: AN EXAMPLE FROM THE
MIAMI SUBLOBE, OH109 U.S.A.
THOMAS V. LOWELL
Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221, U.S.A.
Abstract - Despite the importance of dating glacial sequences, little evidence has been available to highlight the stratigraphic issues associated with the interpretation of age analysis. A compilation of radiocarbon data from the Miami sublobe of the Laurentide ice sheet, provides a large enough data set (more than 133 dates) to identify at least two sources of error: sample and unit variability, and transportation problems. Analysis of different samples from the same stratigraphic level commonly differ by more than the reported one-sigma error, and 2,000-year differences do occur. Glacial entrainment and transportation emplace older organic material over younger in situ materials and this effect may also give age errors in the data set of up to 2,000 years. At a minimum, multiple radiocarbon ages from a sequence of units are necessary to assign a reliable age to events within a glacial sequence. However, representing multiple ages poses its own problems - a graphical representation that combines the probability of each sample appears to be one solution.