Geoarchaeological Records from the NE Saharan Region

Spatiotemporal patterns of prehistoric occupation suggest changes in the loci where people congregated, possibly as a function of changing water resource availability over time as the environment fluctuated between a habitable savanna and an inhospitable desert.

The earliest occupation is associated with the artifacts of the Acheulian tradition of the Lower Paleolithic, and these finds are commonly associated with groundwater-fed lakes, springs, and streams (wadis) with headwaters at higher elevations in the Plateaux escarpments. The chronology is inferential and not well constrained, but likely spans the period before 500 000 to 300 000 years ago, and is distinct from the Acheulian tradition of the Nile Valley.

The archaeological record of the Middle Palaeolithic is better known, and several sites contain in situ living floors and diverse faunal assemblages, which reflect favorable climatic conditions. Much of the Middle Palaeolithic chronology is relative, and is based on taxonomic comparisons with diagnostic artifacts defined in units dating from 250 000 to -38 000 BP. The two oldest units, the Mousterian and the Aterian, occur in both the Western Desert and Nile Valley, but the comparative local economic patterns are markedly different.

Lithics and faunal remains recovered from valley sites suggest reliance on fishing and Bos hunting. Alternately, in the Western Desert, hunting of large game was preferred over the capture of smaller animals. Large groundwater-supported lakes at Bir Tirfawi and Bir Sahara were favored settlement locales, although other environmental settings also were exploited and reoccupied.

Within the Western Desert, the Aterian technocomplex is associated with the latest Pleistocene wet period, which preceded a long hyperarid episode that persisted until the early Holocene. The precise duration of the hyperarid interval remains unconstrained. There is no evidence for local rainfall or spring activity in the region west of the Nile between ~40 000 and 11 000 BP, and human activity was confined to the valley, as preserved in Khormu- san variants of the latest Middle Palaeolithic and other Late Palaeolithic complexes.

The region beyond the Nile Valley was not reoccupied until the onset of suitable climate conditions -12 000 BP, when effective precipitation was enhanced due to the incursion of monsoonal rains from tropical Africa. Occasional rains created seasonal ponds and sustained vegetation that attracted game and people to a region that was otherwise desert. Savanna grasses, trees, and bushes enabled the subsistence of hares, gazelle, and a few small carnivores.

Even during the Early Holocene climatic optimum ~11 000-5500 cal BP, however, the region remained quite dry and drought prone (see Africa, South: Late Pleistocene and Early Holocene Foragers). Characteristic tools and microliths, pottery, and ostrich eggshell beads are present at wadis, springs, and small depressions known as pans and playas, places where rainwater ponded after storms. Most of the terminal Paleolithic/Neolithic assemblages are located alongside water features fed solely by rainfall.