Neogene and Quaternary flexure neotectonic in the Somme valley.

Within the context of the western Paris Basin, considered to be a region ex periencing slight uplift during Neogene and Quaternary, the ESR dating of Q uaternary deposits, together with those of Neogene age, the morphology and available geophysical data suggest that the Somme valley is an actively sub siding sector (tectonic shortening between two active inversions). The diss ymmetry of the valley tributaries and of the deposits preservation is contr olled by a flexuring above the hidden Somme fault. The record of neotectoni c events and the geophysical data demonstrate its activity and elucidate th e recent history of the Paris Basin. (C) 2000 Academie des sciences/Edition s scientifiques et medicales Elsevier SAS.