The present volume brings together some of the papers presented in a session organized in the 18th World Congress of the UISPP, under the title 'Different Times? Archaeological and Environmental Data from Intra-Site and Off-Site Sequences'. A common characteristic of these papers, besides their theme broadly speaking, is their connexion with the activities of the Working Group 'Environmental and Social changes in the Past' (Changements environnementaux et sociétés dans le passé), animated in the frame of the Cluster of Excellence 'Dynamite' (Territorial and Spatial Dynamics) of the University Paris 1-Panthéon-Sorbonne. This Cluster of Excellence, funded by the French State (ANR-11-LABX-0046, Programme d'Investissements d'Avenir), was created in 2012 as part of a public policy aiming at favouring interaction between researchers and disciplines that do not usually work together-or not enough. 'DynamiTe' (http:// labex-dynamite.com/fr/) was conceived as a consortium of laboratories representing different disciplines-geography mainly, but also anthropology, history, sociology, archaeology-susceptible to investigate issues around the key-concept of Territory, in the present, past and future. The Group 'Environmental and Social changes in the Past' focuses on evidenced landscape changes that affected human societies and the perception of these changes by the same societies. Its members are mostly archaeologists and physical geographers, many of them being further specialized in analytical techniques deriving from natural sciences (zoology, paleobotany, palynology, geology, sedimentology, malacology, anthracology). This small community-ca. 65 active members at the time of the Congress-handles and/or produces every day substantial quantities of data in relation with past events in the four corners of the earth (see also Giligny and Tsirtsoni 2015). And like most of their colleagues around the world, they give particular attention to the recording of time scales and interpretation of time records. Time is indeed an essential parameter to be taken into account in any research dealing with the past, since all our hypotheses lay on that. If the reading of time is not right, if an event that we place at a time A happened actually at a time B, several years, decades or centuries after the presumed time A, all the narratives that we may build are wrong. Anyone who ever read a detective novel is aware of how important this factor is for the solution of the mystery and the arrest of the guilty! The gravity of the mistake becomes bigger as we pile up narratives or we try to combine evidence in order to explain things. Thus, if we presume causality between an environmental change and a societal event, either positive (e.g. emergence of a new way of living) or negative (e.g. shrinkage or abandonment of a settlement or settlements in a region), we have to make sure at least that