The study area witnessed alternate paleoenviron-mental and population events influenced by glacial/ interglacial conditions. Paleosols, relict fluvial bodies, lacus-trine carbonatic deposits, sand dunes, and other features underline the severely fluctuating activity of water resources. The study region (SW Libya) provides two different data sets: (1) two stratified, dated, Middle Stone Age/Aterian sites; and (2) hundreds of surface lithic scatters rarely associated with paleoenvironmental proxies. Early/Middle Pleistocene human occupation is presumable, but the bulk of evidence is from the late Middle/Late Pleistocene. Productive environments possibly housed human groups with a Late Acheulean technology during MIS 7. Most of the MSA evidences are barely diagnostic from a techno-typological point of view. Exceptions are made for scanty but precise similarities with sub-Saharan early MSA finds, suggesting the presence of modern humans in MIS 6, and for the Aterian, an example of MIS 4 arid landscape adaptation. Although MIS 3/2 post-Aterian human presence is not demonstrable, signs of a generalized LSA technology are recognizable in the Messak, where stony raw materials could have attracted task-specific temporary occupants.