The application of section-balancing techniques to the analysis of deep seismic sections requires account be taken of isostasy and ductile-deformation processes. Structures imaged by deep seismic reflection profiling across the southern Grand Banks, offshore eastern Canada, are analyzed in this way. Correlations of dipping events in the deep crust, interpreted as shear zones, with faults recognized in the shallow part of the section are tested by attempting to restore the sections to their undeformed state by reversing the displacements on the faults. This process tests the geometric compatibility of the interpreted fault and the structures in its hanging wall. Our models suggest that the faults bounding the Whale and Horseshoe basins detach at the Mohorovičić discontinuity. In contrast, the fault bounding the Jeanne d'Arc Basin detaches within the lower crust.