Abstract : Mediterranean landscape evolution (southern Luberon, Vaucluse, France) from the last glacial period
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Abstract : Mediterranean landscape evolution (southern Luberon, Vaucluse, France) from the last glacial period to the Holocene period is analysed through alluvial deposits and travertine system development linked to climate changes and human occupations. Results of geomorphological, sedimento-stratigraphical and physico-chemical analysis increased by archaeological and palaeoecological (malacology and anthracology) studies and about fifty 14C dating are the basement of a pluridisciplinary research on the links between Man and environment in Mediterranean France. Around 50 Ky BP, numerous glacis formation, made up of torrential pebbles and reworked cryoclasts, covered the southern Luberon piedmont with frequently more than thirty meters thickness. At their bases several “red-soils” and their palaeontological content show the more temperate climate conditions of isotopic stage 3 interstadials in Mediterranean region. Between the Last Glacial Maximum and the Lateglacial period (18-17 Ky cal. BP. ?), a major scale incision occurred with fastness. Since 15500 cal. BP, travertine and detrital deposits were developed. Inside this new morphogenetic tendency, travertine formations located downstream karstic re-emergence are indicative of the Postglacial warming. These carbonated deposits are the oldest testimony of the restarting of the southern France Postglacial travertine accumulation. Then, around 9000 cal. BP and 6000 cal. BP, two main incisions occurred in alternation with embankment phases. The morphogenic dynamic of the first part of postglacial period seems to be linked to the bioclimatic changes. Since the Final Neolithic, in the context of growing human occupation, ruptures (incisions) in the travertine sequences have been recorded. These ruptures, of high frequency but low amplitude, were accompanied by facies changing and strong vegetation opening determined upon palaeoecological analysis. Travertine sensitivity in accordance with climato-anthropic biotope changes is underlined. Between the XIth and the XIIIth century A.D., the decline and the dismantlement of the travertine formations became noticeable. In the same way, the major linear talweg incision (well known in southern France but poorly chronologically discerned until now) was introduced in a morphogenic dynamic only partly interrupted after the XVIIth century A.D., during the Little Ice Age, by a detrital deposit phases. Then a final incision has occurred and it’s still happening today. Combined effect of climatic oscillations and human society occupation modes above the “natural environment” seem to be the main driving force of a bustling morphogenesis during the second part of the Postglacial period. - Slides
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