CHANGING PALEOHYDROLOGIC, PALEOENVIRONMENTAL, AND ISOSTATIC CONDITIONS FROM THE YOUNGER DRYAS TO MIDDLE HOLOCENE IN THE LAKE ONTARIO LOWLANDS, NEW YORK

The Bell Creek valley provides a snapshot of late Quaternary paleohydrologic conditions spanning the Younger Dryas (YD) through the middle Holocene for the southeastern Lake Ontario lowlands, New York. Basal sediments exposed along Bell Creek, southeast of Oswego, indicate the site was inundated by late glacial Lake Iroquois until about 11 ka 14C BP. At that time lake level fell with fluvial systems prograding lakeward towards a new base level. Alluvial sediments of this phase contain abundant, mature spruce logs with a few tamarack and fir, typical of a boreal-type open forest environment during the mid YD into the early Holocene. Prevailing paleohydrological conditions at the site would have changed from cold and dry to cool and moister conditions through the end of the YD. Gradually the river level fell, due at least partially to glacial isostatic adjustment, and the site transitioned into a floodplain paleowetland environment with a water table at or near the surface. The paleoenvironment changed from boreal to temperate, with the main arboreal species hemlock, elm, and beech. Paleowetland conditions appear to have ended by about 6.6 ka 14C BP as the site was slowly buried by overbank sedimentation as climate warmed and dried and isostatic adjustment continued. The paleohydrology at this site is similar to that of other sites within the formerly glaciated Northeastern US.