This paper presents new seismic reflection, refraction, gravity, and magnetic data bearing on the nature of the crust in the vicinity of the Newfoundland Ridge and the J-anomaly Ridge, immediately south of the Grand Banks. This area experienced a complicated plate tectonic history being the focal point for interactions of the North American, African, and Iberian plates. New data have recently been published for this region and conflicting interpretations have been offered in relation to the oceanic or continental origin of the crust there. The data presented here show that the seismic structure and the most reasonable models for the magnetic anomalies are more consistent with an oceanic origin. The trends and offsets in the magnetic lineations and possible differences in subsidence, north and south of the Newfoundland Ridge, are discussed in relation to possible modes of formation of this feature. It is proposed that similar subsidence histories since mid-Cretaceous time on the Grand Banks and J-anomaly Ridge are related to a similarity in the thermal history of the lithosphere beneath these areas, as the ridge crest migrated eastwards, and do not require the same type of crust to underlie both areas.

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