Gravity profiles across the St. George's Channel Basin show a marked discrepancy between the observed anomalies and the anomalies calculated using a model based upon an interpretation of seismic data. This difference may be explained in terms of salt migration away from the centre towards the flanks of the basin. Evidence for such a migration path is provided by the seismic data. An excess of salt on the SE side of the basin has intruded into a major fault giving rise to a salt wall. The gravity models suggest that the basin reaches a thickness of 10 km near its centre but that Permian and Carboniferous sediments are possibly thin or absent.