YOUNGER DRYAS TO EARLY HOLOCENE PALEOENVIRONMENTS AND PALEOINDIAN GEOARCHAEOLOGY OF STREAM VALLEYS IN THE ERIE-ONTARIO LOWLANDS, NEW YORK

The Younger Dryas is recognized as a significant cold interval that occurred at the end of Late Wisconsin glaciation. Although recognized globally, the response of hydrologic, geomorphic and ecological systems to this cold reversal in the eastern Great Lakes Region is limited. Here we present a paleoenvironmental reconstruction including geoarchaeological perspectives on Paleoindian site location for the Younger Dryas and early Holocene for stream valleys in the Erie-Ontario Lowlands (EOL), New York based upon a synthesis of multiple datasets.

The EOL was subaerially exposed once water levels in glacial Lake Iroquois dropped towards the level of early Lake Ontario. Many of the low-gradient stream valleys of the EOL are poorly drained, contain variable amounts of Late Quaternary fill, and are flanked by drumlinized uplands that preserve several known Paleoindian sites in surface and near-surface contexts. The stratigraphy of valley fill within EOL valleys preserves a landscape of actively wandering streams and poorly drained floodplains with spruce- and tamarack-dominant forested wetlands and ponds that was colonized as early as 13,000-12,900 cal yr BP, just several hundred years after subaerial exposure and roughly coeval with initial known Paleoindian presence within the region. Laurentide Ice Sheet configuration, presence of glacial lakes and other environmental factors appear to have modulated a regional “glacial lake effect” climate, with pronounced seasonality that allowed for these Southern Boreal-like forests to persist through the Younger Dryas. By the Younger Dryas-Holocene transition, closed pine and deciduous forests emerged throughout the EOL, with a clear increase in temperate species by 11,500 cal yr BP.

Geospatial mapping across New York reveals a higher density of near-surface Paleoindian archaeological sites and isolated artifact finds on the EOL versus the adjacent Allegheny Plateau. This likely reflects the attractivness of early imhabitants to (1) the extensive lakebed setting as well as (2) the shifting wetland-rich, boreal landscapes, with food/subsistence resources, fostered by changes in regional climate. Valley fill stratigraphy raises the possibility of buried Paleoindian sites beneath younger Holocene alluvium. Additional Paleoindian sites are possibly present adjacent to or overlooking valley wetlands and ponds.