PRELIMINARY GEOMORPHOLOGY AND GEOARCHAEOLOGY OF THE LOWER WOODCOCK CREEK VALLEY, NORTHWESTERN PENNSYLVANIA

Alluvial stratigraphy, pedology, and geomorphic mapping are used here to assess Holocene landscapes and environments near the confluence of Woodcock Creek with French Creek in northwestern Pennsylvania. Preliminary analysis of the alluvial deposits and landforms reveals significant post-glacial geomorphic activity and landscape alteration in the lower reaches of the valley. An increasing charcoal presence occurs starting in the middle part of a remnant low terrace deposit, becoming abundant and distinct around a buried A (Ab) horizon, and within younger floodplain deposits. Discovery of a fire pit containing wood charcoal, charred nuts, fire-cracked rocks, and chert flakes in the underlying Bwb horizon relate to Late Woodland occupation (1630 +/- 40 14C YBP) within the Woodcock Creek valley prior to Euro-American settlement. To date, no culturally diagnostic artifacts have been recovered from either the Ab or underlying Bwb horizons. The lower portion of the Bwb and the C horizon are culturally sterile. Pedogenesis and extensive bioturbation have obliterated any original sedimentary structures and created a cumulative soil profile. These data suggest some degree of geomorphic and hydrologic stability that would have been considered favorable for human occupation prior to site burial. However, the increase in charcoal content and coarsening grain-size upwards above the Late Woodland land surface, and the presence of abandoned and in-filled channels on the modern floodplain reflect changes in watershed hydrology and sediment supply. Cool and wet climatic conditions associated with the Dark Ages Cold Period may be responsible for floodplain aggradation and eventual site burial. Additionally, colonial settlement commencing in the late 1700s may have triggered large-scale geomorphic instability that led to rapid channel incision and migration in the recent past. Continuing radiometric dating and laboratory analysis are underway to reconstruct more fully the Holocene environmental history of this portion of northwestern Pennsylvania.