SEDIMENTARY ANALYSES OF SEDIMENTS IN THE EASTERN PORTION OF LAKE TONAWANDA

Following the retreat of the Ontario Lobe of the Laurentide Ice Sheet from western New York, periglacial Lake Tonawanda formed. Lake Tonawanda was situated between the Silurian Niagara escarpment and the Devonian Onondaga escarpment in western New York. The existing Batavia Moraine partly blocked and sheltered the eastern portions of the lake, which received meltwater and sediment from the ancestral Niagara River. A preliminary examination of sediments from the eastern margin of Lake Tonawanda shows a shift from a lacustrine to swamp environment.

Analyses of a 240 cm soil core included loss on ignition, percent moisture and particle size analyses. The Batavia Moraine nearly cuts the basin in half, reducing energy and allowed silts and clays to settle out in the eastern region of the basin. Particle size and loss on ignition analyses indicate a transition at 140-150 cm from lacustrine to a swamp environment. At the transition there is a shift from predominantly sands to silts and clays, with a continual increase in organic matter content upwards to nearly 20% organic matter just below the tilled surface in the modern swamp/ muckland environment. Future analysis will include additional sampling to determine the nature and timing of the lacustrine/swamp transition, as well as paleohydrologic and plaeoclimatic influences within the Tonawanda basin. With further study we hope to link a better understanding of the processes and timing of the disintegration of the Laurentide Ice sheet in eastern North America.