Summary : 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.
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