Abstract Diatoms collected at 10 cm intervals from a 6.3 m Pleistocene lacustrine diatomite section in the now arid piedmont west of Jebel Marra volcanic caldera, Darfur, western Sudan were analyzed. The lake probably formed as a result of a rhyolite lava flow damming a former river. The lake was initially shallow, but in the upper 5.3 m, diatom composition and a salinity reconstruction indicate persistent deep freshwater conditions. The diatomite is overlain by an Acheulian stone tool assemblage with a probable age range of ∼0.8 ± 0.3 Ma. The lake may be coeval with the oil palm fossils discovered ∼90 km to the southwest, which are underlain by Developed Oldowan/Early Acheulian artifacts, some in primary context, and so of Lower/Middle Pleistocene age. Both the diatomite and the oil palm fossils indicate a much wetter climate than today.