Dating Deglaciation

Plots of Age versus Latitude

Calculations for Retreat Rates

Comparisons and Speculations

The three dating methods; Bulk sediment, Macrofossil, and Cosmogenic nuclides yeilded the following retreat rates: 38 meters per year, 81 meters per year, and 31 meters per year, respectively. In order to obtain the retreat rates, I used Google Earth to measure the distance between the northern-most point and the southen-most point. For each method, I subtracted the latitude data, and also subtracted the age data in order to convert to km per year and then to meters per year. The bulk sediment rate and cosmogenic nuclide rate are similar 38m/yr and 31 m/yr and the macrofossil retreat rate is the fastest rate at 81m/yr.

Based on the readings for this lab, the cosmogenic nuclide dating method provides the best estimate for dating glaciers becuase this method dates the actual rock instead of sediments or fossils that the bulk sediment and macrofossil methods are based on. These differences could account for the differences in retreat rate. Another difference that could be accounted for is the difference in ages that were used for the southern-most points.