The Somme valley is a key area for the Human occupation of NW Europe and and has been intensively studied since the end of the XIXth century. In this region, Quaternary deposits are represented by a terrace system including ten alluvial sequences covered by slope deposits which formed during the last million year. Geomorphology and dating have been intensively studied and provide a consistent view of geometrical evolution of the landscape together with a solid chronological frame of events. Many sites have been excavated within these formations and have given opportunities to report on changes of climate and environments trough time. Non marine molluscs which are a good proxy for palaeoenvironmental reconstructions are regularly preserved in those deposits. In 1952 Breuil published a first detailed report of all the non-marine molluscan faunas from Quaternary deposits of the Somme and the Seine valleys. Sixty six years later after a lot of supplementary analyses have been performed, the present contribution provides a new synthesis of the history of malacological assemblages and associated palaeoenvironmental reconstruction with palaeolithic occupations since 1 Myr in the Somme valley. How climatic cycles influence composition of snail communities ? Is there a model of malacological evolution vs climatic and environmental changes ? What evolution of biodiversity can be reported ? are the main questions addressed in this talk.