PRELIMINARY RADIOCARBON RETREAT CHRONOLOGY OF THE ERIE LOBE: IT MIGHT MEAN THIS

The assignment of ages to glacial retreat patterns present a number of challenges. The chaotic landscapes at ice margins are not ideal sites for the preservation of organic materials, and organic materials accumulating in basins may post-date actual deglaciation by an unknown amount. We are undertaking a brute force approach to these challenges by coring multiple basins to recover bracketing ages for deglaciation. To date we have sampled over 20 basins within a 50 km radius in southwestern Ohio. When coupled with prior work, the chronology from these new data points shows some regional consistency. For hypothesis development and testing, we consider these patterns within the context of events recorded in ice cores and marine records.

Preliminary results suggest three interesting points about these ice retreat patterns. First, the glacier margin underwent a major meltback, with apparently minor amounts of meltwater activity, during a period when the GISP2 record indicates static or slightly cooling climate conditions. Second, meltwater activity evidently increased from 16,170±97 (AA-45079) until 14,600±91 (AA-45078). This precedes the rapid rise in sea level known as Meltwater Spike 1A. Third, the ice margin retreated into the Lake Erie basin and formed the highest levels of Lake Maumee at the same time as the break-up of portions of the Laurentide Ice Sheet injected the carbonate-rich sediments associated with Heinrich 1. The overall apparent correspondence of these events deserves further consideration.