La séquence magdalénienne de la Goutte Roffat (Loire). Etude géologique et implications méthodologiques

Abstract

The study of la Goutte Roffat was carried out as part of the salvage operations of the sites of Villerest. The sequence is exceptional, with nearly ten meters of deposits and six archeological levels. These are built up over three meters in thickness, from the lower Magdalenian with raclettes to the upper Magdalenian. From a dynamic standpoint, the alluvial, processes are shown to be progressively replaced by colluvial deposits. The latter shows the same rythmicity pattern four times. The climatic interpretation is supported by a simple quantified curve drawn up from counts of the gross fraction compared with the rythmicity. Finally, the chronological interpretation shows the similarity between the fluctuations we found and those described in the classic sequence, from << Laugerie » to the « Allerod ». It is likely that the Loire river began to cut into its recent alluvial deposits beginning with the « Laugerie » episode.