Poster 54: Understanding of long-term landscape evolution in the Champlain Valley is hindered by recent glacial modification which has eroded or buried much of the landscape that existed prior to the onset of northern hemisphere glaciation about 2.8 Myr ago. For example, it is likely that glacial and lacustrine deposits have buried ancient river valleys that once floored the Champlain Valley and obscured their relationship to the ancestral Champlain trough. To search for these paleo-channels and other clues to long-term landscape evolution, we analyzed well-log data to create a map of bedrock topography in the Champlain Valley. The well-log dataset was provided by the Vermont ANR and contains wells located by GPS, E911 addresses, and screen digitizing. Numerous mislocations and inconsistent data reporting made the dataset challenging to synthesize. To improve the quality of the analysis we incorporated NRCS soil data for the Champlain Valley to constrain areas of shallow bedrock. Using the inverse distance weighted method, we were able to create an interpolated map portraying both bedrock elevation and depth to bedrock. These maps unveiled topographic anomalies below the surface, some of which have bedrock elevations below modern sea level and comparable with the deepest points in Lake Champlain. Work is ongoing to determine the nature of these anomalies, specifically whether they represent ancient fluvial valleys, glacial scouring, or extensional faulting.
