Abstract ATM-9405145 Grimm, Eric C. Illinois State Museum Title: Long Records of Paleoclimate from Florida Recent research on a continuous 50,000-year sediment record from eastern North America has revealed a striking correlation between Heinrich events (large surges in flow of ice streams feeding from the Laurentide ice sheet into the North Atlantic) and major changes in vegetation in peninsular Florida. These events are expressed at Lake Tulane, Florida, as abrupt shifts between pine-dominated and oak-dominated communities, which likely correspond with times of moist climate alternating with periods of extreme drought. Those results suggest that the Heinrich events involved important changes in ocean-atmosphere circulation, and thus forcing other than internal dynamics of the ice sheet. This award supports a research project designed with the following objectives: (1) To establish a higher-resolution AMS-radiocarbon chronology for the sediments of Lake Tulane. The record will verify whether the vegetational shifts in Florida are indeed synchronous with Heinrich events; (2) To reconstruct the history of lake-level fluctuations in Lake Tulane; (3) To extend the regional and temporal records of vegetation and climate for peninsular Florida by studying the pollen stratigraphy of new long cores (already collected) from several in-filled sinkholes. These sediments appear likely to span much more than the 50,000 years covered by the Lake Tulane record, and thus have excellent potential to produce the first record of changes in vegetation and climate spanning the last complete glacial/interglacial cycle in eastern North America.
