One thousand kilometres of seismic recordings have been taken to the north of the Cotentin and in the Baie de Seine. On the basis of these, a new geological map has been drawn up and additional information about the structural evolution of the region has been obtained. Among the numerous faults detected in the Jurassic areas some affect the Wealden deposits without extending into the Upper Cretaceous. This tectonic phase already noted in Dorset and at the entrance to the eastern end of the English Channel may be associated with earlier movements during the latter part of the Jurassic (Boulonnais movements). Despite the apparent continuity between the sediments of the Upper Cretaceous and of the Lower Eocene, the distribution and the structure of the Tertiary basins of the central English Channel lead us to envisage a phase of deformations with a large radius of curvature at the beginning of the Eocene period. We see there the attenuated effect of the movements detected in the western English Channel at this time. The large fractures, of markedly east-west orientation off the Cotentin, represent the post-Eocene reactivation, by compression with upthrown to the north, of important lines of weakness in the basement. These faults follow zones of subsidence recognizable in the Cretaceous.