Gravity measurements in the Connecticut Valley near Amherst, Massachusetts, delineate a narrow north-south-trending “low gravity” zone that is interpreted as a part of the pre-late-glacial drainage channel of the Connecticut River and its tributaries. These are entrenched in the Triassic Sugarloaf Arkose.
The gravity data were derived from a network of 208 stations arranged in an east-west sub-parallel array covering 42 square miles between Bull Hill at the north and the Northampton-Amherst road at the south. The reduced Bouguer values were plotted with one-half milligal intervals. Data were correlated with well logs to determine subsurface geological relationships.
The course of the buried Connecticut River in this area appears to be compatible with suggested pre-late-glacial channel locations to both the north and south of the area as determined by seismic investigations.