L'enregistrement des phénomènes pédo-sédimentaires et climatiques. L'exemple de la coupe des Tares (Dordogne)

Abstract

Recent detained works On coUuvial deposits in South-West France intend to build a litho- and pedostratigraphic sequence of the last interglacial-glacial climatic cycle, as paleoclimatic interpretations from cave deposits soon available were for few years called in question again. Les Tares section (Dordogne) is nowadays the most complete one and is taken there as an example. The microscopic characteristics of paleosols are used for correlating this section with theses from the northern part of France. Thus, we can clearly show : — a complex of soils «lessivés» and washed deposits, related to the Eemian interglacial and the early glacial; — gelifluction deposits correlated with the whole or a part of the weichselian pleniglacials. A permafrost, associated with eolian silts deposits, occurs during a late episode, which is probably equivalent to the upper pleniglacial. — the complexity of the superficial soil, which is affected by reworking processes in a cold environment, we consider as the last cold stage of the tardiglacial. We point out the presence of hiatus, probably of a great importance, which are due on the one hand, to intense periglacial upturns, and on the other hand, to biological activity. These processes explain that only major climatic events are recorded, in particular long stabilization soil periods or very cold stages.