In the Talmondais (Vendée) the Hettangian sedimentation locally begins with fluviatil clastic deposits prior to the deposition of shallow marine carbonates. These clastics, including the footprint-bearing beds of Le Veillon (south of Talmont- Saint-Hilaire) are subject to important and frequent variations in thickness. Drilling and geophysic data indicate a tectonic control of these variations. A fault-block pattern is proposed. At a small scale, it gives an illustration of the extensional tectonic processes related to the evolution of the Biscay rift during the early Liassic
