Libyan-Italian joint mission in the Jebel Gharbi (Tripolitania). The Holocene sequence of the Jifarah plain

The importance of Jebel Gharbi, the mountainous range southwest of Tripoli, like the rest of the Libyan coast, became particularly relevant during the Holocene. At that time the territory may have played a key role in the neolithization process which occurred along the southern coast of the Mediterranean. Thanks to its central location the Jebel can give an important contribution to understand the exchanges which took place along the coast from both the western regions of Maghreb and from those to the East, mediated by the Nile Delta. Another no less important theme to be explored are the relations between the Mediterranean region and the sphere of southern Libya, in the continental Sahara. Though in both regions the pre-production phase is manifest with similar modes of interaction with the environment, the Sahara has its own characteristics belonging to a complex of cultures (the Saharo-Sudanese complex) which knew both very early ceramics together with herding on cattle and caprines. After a long cycle of research aimed at the reconstruction of the chrono-stratigraphic sequence and the paleoenvironment throughout Middle and Upper Pleistocene, during the most recent campaigns the Jebel Gharbi Archaeological Mission investigated the Holocene fine sediments, and sites associated with them, which are particularly numerous at the base of the Jebel escarpment. As a matter of fact, no significant site for the Holocene occupation was encountered in the inner region of the Jebel. On the contrary, the most suited area to the study of the Holocene occupation was the plain that begins at the foot of Jebel and reaches the coast: the Jifarah. Since 2005 the Jifarah plain became the main investigation focus of the Archaeological Mission in Jebel Gharbi, while continuing survey activity also in the southernmost area, to the limits of the Hammada el Hamra. In a strip of land close to the base of the Jebel escarpment, the Jurassic sandstone bedrock is exposed in the beds of many small wadis. At several places the scarce thickness of the alluvial deposits allowed the emergence of groundwater through springs (this phenomenon may have coincided with seismic episodes). The last campaign in the field, in autumn 2010, investigated some relevant sites in Wadi Allohim and the subsequent processing of the fieldwork data has allowed us to establish a basic Neolithic sequence for the Holocene Jifarah occupation. The main problem that our research had to face is the exclusive presence of open air sites in which most of the records, especially concerning the bioarchaeological component, was not preserved. Therefore we had to develop a research methods that could overcome the limits of the archaeological record. To answer this difficulty paleoclimatic and paleoenvironmental reconstruction were emphasized at the maximum. The palaeoclimatic model of the Jifarah indicated the presence of a long phase of relative humidity between 6500 and 3500 BC, preceded and followed by two arid phases, the last of which represents the beginning of the modern aridity. The abundance of water, and the resulting wealth of vegetation, allowed for the continuity of the occupation and encouraged the process of economic change towards pastoral based organization. The Shakshuk, Wadi Bazina and El Jawsh areas appeared the most suitable territories for the survey. A transitional phase in the early Holocene (Jifarah A: Early Neolithic, 6150-5750 cal BC / 8100-7700 cal BP) might have represented a continuation of the broad spectrum exploitation economy by collectors who visited seasonally ponds and marshes. The arid trend typical of this period could have made the marsh areas more favorable locations. Not be ruled out that the economic model of these groups would include already goat breeding, which at this time is known in the Neolithic layers of Haua Fteah in Cyrenaica. During the following phase (Jifarah B: Middle Neolithic, from 4750 to 3650 cal BC / 6700 to 5700 and 5400 cal BP) the same region presents a large number of hearths and mounds. These steinplätze are clear markers of the presence of shepherds groups and a proof of their short living on the territory. Along with the steinplätze larger encampments were detected which functioned as base-camps; they are located in areas rich in vegetation where also gathering activities could be carried out such as site SJ-00-59 at Wadi Bazina or site SJ- 10-96 in the Wadi Allohim. Subsequently, after the arid interval of 3400 cal BC (Jifarah C: Late Neolithic, from 3400 to 2450 BC / 5400- 4400 cal BP) the adoption of nomadic pastoralism seems to have been the preferred solution.