Seismic profile P4, intersecting the Rhône canyon and a tributary of the Ardèche canyon, in two-way travel time (twt) on top, and converted in depth at the bottom. The Grand Malijac borehole is projected on the depth converted seismic profile for reference. Vp velocities obtained from the depth-processing are drawn on the section for each formation. The MES is drawn in dotted red line. See Figures 4 and 5 for stratigraphic legend and text for more details. RC: Rhône canyon; ATrC: Ardèche tributary canyon.