The geo-archaeological survey in central Tadrart Acacus and surroundings. Environment and culture.

A regional survey was conducted in the area of the Tadrart Acacus and Messak Settafet mountain ranges and in the surrounding dune fields. A large part of the region herein examined was previously unknown from geoarchaeological and archaeological points of view. During the 1990-95 field seasons, more than 300 sites were identified, which document human occupation during the Pleistocene from the Acheulean up to the Mousterian and Aterian phases, as well as during all the Holocene. Paleoenvironmental reconstruction indicates a humid climate during the Middle Pleistocene, while the Middle Palaeolithic and Aterian phases are characterised by an arid environment. A hiatus in human occupation exists between the last Aterian phases, dated to more than 60,000 years BP, and the earliest Holocene archaeological evidence, dated to around 10,000 years BP. The latter consists of “Epipalaeolithic” or “Early Acacus” hunter-gatherers living in an environment wetter than the present. The evidence shows that they possessed a specialised economy, high mobility, a logistic settlement pattern and microlithic industry with a well-defined backed tool-kit. A progressively arid climatic trend, probable demographic growth and intra-group pressure seem to be at the basis of the cultural and economic transformations of the “Mesolithic” or “Late Acacus” hunter-gatherers groups. These transformations are reflected in different economic strategies, with a broadening of the spectrum of resource exploitation, an intensified use of wild cereals and a particular management of Ammotragus lervia. The material culture is characterised by the emergence of pottery, which enters the archaeological record at around 8900-8800 years BP, by large-size lithic industry on silicified sandstone, and by a notable increment of grinding equipment. The transition to a food-producing economy based on cattle and capriovid breeding, which occurred at the very end of the eighth millennium BP, is still not well defined. The paleoenvironmental indications, in particular the study of the lake sediments in the erg areas, give a quite detailed picture of the climatic changes during the Holocene, supported also by a large number of 14C datings. The earliest Pastoral occupation seems traceable to the more internal areas of the Acacus. During the middle phases of the Pastoral, an extraordinary flourishing of this culture took place, with a clear increase in the number of the sites and in their structural characteristics. The ergs were occupied by lakes and swamps and densely inhabited. The archaeological sites display organised structures and a rich material culture. The remains of domestic cattle are frequent. The transition from the sixth to fifth millennium BP reflects an important climatic change, with the intensification of aridity. Groups of shepherds exploited the areas of the alluvial plain, such as the wadi Tanezzuft, more intensely, and used the mountain areas only as refuge for sheep and goats during the dry season. The settlement pattern is therefore dominated by high mobility, as also attested by the presence of exotic objects. The material culture underwent important modifications, with a growth of undecorated pottery and plain lithic industry. Around 3500 BP, mountains and dune fields were used either for brief occupations or for short stops during transits, while marked forms of sedentism seem evident in wadi Tanezzuft, given the presence of water.