Science et changements planétaires / Sécheresse


Chemchane, histoire d’une sebkha Volume 4, issue 1, Mars 1993

URA 1433, CNRS, Boîte 106, Jussieu 75252 Paris Cedex 05, France.
  • Page(s) : 25-30
  • Published in: 1993

Pollen studies carried out on lacustrine sediments from the Chemchane sebkha in Mauritanie (21° N-12° W) have shown that the environment of the Western Sahara changed considerably over the last 10,000 years. A Sudano-Sahelian wooded grassland expanded near the sebkha, coeval with the extension of a deep, fresh-water lake between 8 100 and 6 500 BP. This plant community was characterized by a continuous grass cover with numerous trees of Sahelian (Acacia, Balanites, Commiphora..) and Sudanian affinities (Isoberlinia, Alchornea, Anthostema, Syzygium, Zanthoxylum, Celtis, Combretaceae...). Its modern position lies southward, between 15°-16°N, in Senegal, where the mean annual rainfall reaches at least 300 to 400 mm. These results demonstrate that the Saharan desert was considerably reduced during the late-middle Holocene period.