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Les fluctuations environnementales des deux derniers millénaires en Afrique de l'Ouest: premiers résultats de l'étude des terrasses alluviales du ravin de Sansandé (vallée de la Falémé, Sénégal oriental)

Published inGéomorphologie, vol. 24, no. 3, no. Géomorphologie, paléoenvironnements et géoarchéologie des mondes tropicaux, p. 237-255
Publication date2018
Abstract

The aim of this paper is to present the preliminary results of the study of a Recent Holocene sedimentary sequence located in the Falémé valley in Eastern Senegal (West Africa). Geomorphological prospections and archeological excavations are performed in this area since 2011. So far the research allowed an understanding of the valley geometry and the establishment of a robust chronostratigraphical framework based on OSL and radiocarbon dating. The richness of the archeological data allows the development of a geoarcheological approach. However, the sedimentary archive of the valley constrains our research on the Pleistocene period. Since 2016, the study of a temporary affluent of the Faleme River made it possible to analyze well-preserved Recent Holocene sediments. The methodology includes field work to recognize the geomorphological forms and formations observed in the ravine during the dry season. The field and laboratory work led on the sediment of two alluvial terraces allocated to the two last ka, allow us to understand the palaeoenvironmental evolution that affect this area. They highlight morphogenesis rhythms mainly driven by climate change. Thus the population who occupied the area study during that period have been exposed to a significant environmental variability, which likely affected their practice. In turn, the sedimentary accumulation seems to have been partly controlled by the intensification of pastoral and agricultural activity in the valley. These sedimentary records provide a new milestone in the evolution of Environment/Society interactions during the Late Holocene in an area that still has few comparable studies.

Keywords
  • Alluvial terrace
  • Sedimentology
  • Geoarcheology
  • Late Holocene
  • Western Africa
Citation (ISO format)
DAVIDOUX, Sarah et al. Les fluctuations environnementales des deux derniers millénaires en Afrique de l’Ouest: premiers résultats de l’étude des terrasses alluviales du ravin de Sansandé (vallée de la Falémé, Sénégal oriental). In: Géomorphologie, 2018, vol. 24, n° 3, p. 237–255. doi: 10.4000/geomorphologie.12484
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ISSN of the journal1266-5304
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