Geomorphology and quaternary humid phases in the Meknassy basin (central Tunisia).

The geomorphological survey of the Meknassy basin (central Tunisia) shows the presence of five (5) Quaternary levels. The middle Pleistocene is made up of three levels materialized by encrusted pediments, or alluvial fans. The upper Pleistocene, Holocene time and Historic are especially marked by terraces. The main one (terrace 2) represents a complex cycle of sedimentation. Containing a big number of prehistoric artefacts, this cycle starts with the upper Pleistocene and terminates with the end of the ante-historic Holocene. New dating of the deposits constituting this terrace provided an age of 93,800 +/- 2,000 years B. R for the visible basis of the deposits. This agrees well with the known chronology based on prehistoric civilizations (from the Aterian to the Capsian). Geomorphological and chronological analysis permitted to advance precisions and confirmations of the quaternary humid oscillations ages in middle-southern Tunisia: five wet phases interrupted by arid ones. Only the historic terrace (Terrace 1) is assigned essentially to anthropogenic action during late antiquity rather than being the result of a wet phase.