Several Newfoundland Appalachian terranes converge in the southwest corner of the island. The recent Lithoprobe East deep seismic reflection profiles imaged the crust along a transect across this area. In this paper, we present the gravity and magnetic data for the area and process them using shaded relief, horizontal and vertical gradient, upward continuation, and layer stripping techniques to interpret the more subtle features of the fields.Traditional two and one-half dimensional gravity and magnetic modelling is undertaken using constraints from the reflection data to develop a model of the crust in this region. The results from the processing are then used to interpret the crustal structure away from the seismic line.In general, we find that the major features on the gravity and magnetic anomaly maps can be explained by sources in the upper crust. The major faults in the area bound terranes that differ in potential field character. A minor change to the location of one terrane boundary is suggested. The rest correlate well with the geophysical data.