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Late Paleozoic reconstructions of the North Atlantic juxtapose the eastern margin of the Grand Banks with the continental margin off Iberia. Comparison of the geology of the Grand Banks region with results from ODP Leg 103 on the Galicia margin improves our understanding of the Mesozoic-cenozoic tectonic evolution of these regions and provides new constraints on pre-drift fits.The Grand Banks region is underlain by Paleozoic and Precambrian rocks of the Appalachian Orogen, which were rifted, eroded, and buried during Mesozoic and Cenozoic tectonic episodes related to formation of the North Atlantic Ocean and the Labrador Sea. The Carson Basin along the eastern margin of the Grand Banks contains Triassic and Jurassic evaporites overlain by Jurassic and Cretaceous carbonate and clastic rocks that were deeply eroded during the mid-Cretaceous. This unconformity is overlain by a comparatively thin and undeformed sequence of Cretaceous-Tertiary fine-grained marine elastics. Since the mid-Cretaceous, the outer portion of the Carson Basin has subsided to oceanic depths and now underlies the slope-rise zone. Comparison of the seismic stratigraphy of the Carson Basin with that of the Galicia margin indicates similar tectonic histories and depositional environments from Triassic to Tertiary time. Seismic-reflection data have been used to map the minimum seaward extent of continental crust, and this boundary lies approximately along a "headland to headland" line between the Newfoundland Ridge and Flemish Cap. Regional juxtaposition of these margin segments is geologically reasonable, but the evidence for continental crust beneath the slope and rise southeast of the Grand Banks precludes fitting Galicia Bank in this zone.

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