VARVE STRATIGRAPHY FROM WETLAND CORES, OSWEGO COUNTY, NEW YORK

Work done to correlate varve sections form Pennsylvania, Vermont, and New Hampshire have been the focus many studies to understand the last episode of deglaciation in North America. Central New York has been largely over looked as a place of study for insight into the timing and sequence of deglaciation during the Pliestocene. However, an excellent study area exists just southeast of Lake Ontario in Oswego County. The land having been shaped and sculpted by glacial outwash and sediment deposits, Oswego County provides an excellent location to study the depositional processes of small glacial lakes (now swamps and wetlands) with varve records. Therefore, a study is underway to characterize the distribution of ancient glacial lakes with varve deposits in Oswego County to make comparison with studies from other regions of the northeast US. As well, this study seeks to correlate the varve records found in the ancient glacial lakes with the timing of deglaciation and provide insight into the last cycles of glacial advance and retreat in central New York. During the dry season of 2007 and 2008, when local wetlands are accessible, vibracores were collected at several locations. The margins of the wetlands are underlain by finely stratified sand, silt with less clay. In one core, gravel was found in the sandy deposits. These materials are interpreted as proximal outwash. Cores collected tens of meters from the wetland margin contain varves with a proportion of clay and silt that is about equal. Individual silt-clay couplets range in thickness from about 2 to 10 cm. The varve deposits overlie course gravel and sand, that is most likely the ablation till that forms the bedrock cover in most of southern Oswego County. Detailed analysis of the varve stratigraphy from adjoining wetlands will be presented.