Geophysical data and information from limited drilling operations on the Newfoundland and south Labrador Shelf indicate the presence of a thick sedimentary sequence, that ranges in age from presumed Paleozoic to Tertiary. A seismically distinctive unconformity marks the base of a wedge of Mesozoic and Cenozoic sediments typical of a trailing continental margin. The underlying rocks vary in age from Precambrian to Mesozoic. Both flat-lying and tectonically disturbed sediments can be identified beneath the unconformity. In at least one area the deformation can be attributed to halokinesis. Regional uplift, the local formation of horst and graben structures, and erosion were contemporaneous with initial continental rifting. Plate separation and the onset of sea-floor spreading resulted in the rapid subsidence of the shelf and its subsequent burial by a continental terrace wedge of sediments.