PEATY AND MUCKY WETLANDS OF NORTHWESTERN PENNSYLVANIA: VESTIGES OF LATE WISCONSIN DEGLACIATION AND LOGISTICAL RESOURCES TO PALEOINDIAN HUNTER-GATHERERS

Late Wisconsin (Marine Isotope Stage 2) glaciation profoundly impacted the hydrology, ecology and landscape configuration of northwestern Pennsylvania. Using field-based geomorphic mapping, sedimentary facies analyses, soil survey information and LiDAR imagery, the spatial distribution of organic-rich wetlands (peat and muck) in Erie, Crawford and Warren counties are first analyzed in relation to paleoglaciological processes and then to the spatial distribution of surface-collected Paleoindian artifacts.

The results indicate that most peaty and mucky wetlands occur in glacially scoured valleys, often behind hummocky ice-contact landforms. An analysis of glaciogenic sediments in accessible exposures, primarily sand-and-gravel pits and roadcuts, in areas of hummocky topography indicate that they occur predominantly in areas where dead-ice down-wasted in-situ, and possibly for long periods of time, during deglaciation. A working model of peat and muck genesis suggest many have formed in the waning stages of the Late Pleistocene and the Holocene as climate warmed, the landscape became ice-free, and regional groundwater and lake levels lowered. Many of these peats and mucks are hydrologically-connected to lakes and/or have areas of open-water and wandering stream networks that would have contained vital resources for small groups of Paleoindian hunter-gatherers during the Younger Dryas and Early Holocene. A spatial analysis of Paleoindian artifacts shows that many cluster around the perimeter of or are overlooking wetlands and associated lakes, especially in the Conneaut Lake-Marsh and Pymatuning Reservoir valleys. Although no Paleoindian sites in the study area have undergone formal excavation, the fact that numerous surface finds occur in association with wetlands and lakes suggest a broad-spectrum foraging strategy for the procurement of floral and faunal resources as has been shown elsewhere in the formerly glaciated Great Lakes region.