INTEGRATING MULTIPLE GEOPHYSICAL METHODS FOR THE CHARACTERIZATION OF BEDROCK GEOMETRY, ISCHUA VALLEY, SOUTHWESTERN NEW YORK STATE

The Ischua Valley in the Southern Tier of Western New York State is a buried glacial valley that was filled in during Pleistocene glaciation. The sequence of glacial advance and retreat served to create an assortment of sediments that now fill the valley floor. The valley, which extends approximately 30 km, is a major component of the Olean Creek watershed, which acts as the primary source of recharge to the regional aquifer within the valley. Lack of well log data in the valley prohibits accurate regional scale numerical modeling for aquifer studies. Geophysical methods allow subsurface information to be collected in the Ischua Valley, most importantly, depth to bedrock and glacial stratigraphy. These methods are gravity, seismic refraction, and reflection. The integration of these tools enables an accurate depiction of the subsurface geometry in the valley. Gravity measurements, collected throughout the valley are used to collect information about variations in the bedrock topography and the stratigraphy within the valley. Seismic refraction profiles allow more accurate calculation of bedrock depths and provide a constraint on the gravity measurements. In areas of complex glacial stratigraphy, high-resolution seismic reflection is capable of discerning the small acoustic changes between the different glacial boundaries in the buried valley. Data obtained from the fieldwork allow for a cross-sectional and longitudinal map of the valley geometry, including bedrock topography and glacial stratigraphy, which will provide important parameters for modeling the regional aquifer system within the Ischua Valley.