High-resolution reflection seismic investigations carried out in the past decade by the Renard Centre of Marine Geology (State University of Ghent) have shed some new light on the tectonic setting of the offshore extension of the London-Brabant Massif.A classical view is that this Palaeozoic basement high behaved throughout post-Hercynian times as a rigid unit, unaffected by the major Mesozoic and Cenozoic deformation phases which left their scars along, its periphery.Some doubts may however be cast on this model, particularly in view of the observation of a sequence of troughs and faults in the Mesozoic and early Cenozoic cover of the Brabant Massif. These deformations can be subdivided into three main groups: the North Hinder Structures, the Gravelines Structure and the Goote-Raan Structures.The North Hinder Structures consist of a N50°E-trending alignment of synclinal troughs in the Eocene cover sediments (mainly Ypresian clays). These deformations seem to drape block-fault structures affecting the underlying Palaeocene and Cretaceous units over a total length of nearly 50 km. The amplitude of the drape deformations amounts to several tens of metres, with a local peak-to-trough maximum of about 140 m. The Gravelines Structure is a major trough with an amplitude of about 120 m, affecting Mesozoic and Cenozoic beds off Gravelines. The Goote-Raan Structures form an orthogonal set of flexures, faults and narrow, elongated synclines, of low amplitude (a few metres).Dating the above structures is at the present time still highly speculative. However, the observation of unconformities at three different stratigraphic levels and in close association with the deformation zones suggests three deformation phases: an initial Mesozoic or early Palaeocene event, a possible tectonic pulse at the Lutetian/Bartonian boundary and a main folding phase at the Eocene-Oligocene boundary.The multiplicity of tectonic phases in time does not imply that these structures would be structurally unrelated. In particular the North Hinder ...