Reconstructing palaeoenvironments of the last mobile hunters-gatherers in the southern Levant during the middle Epipaleolithic period, northwestern Negev dunefield, Israel

The transition from roaming/mobile hunters-gatherers to sedentary settlements in the southern Levant during the Late Epipaleolithic (Natufian) is considered a decisive point of no return in the history of mankind. While the first sedentary settlements are known predominantly from the Mediterranean area of the Levant, the reasons for this fundamental change in subsistence are deeply rooted in socio-economic adaptations of the last mobile hunters-gatherers in the region at large, and in particular, the Sinai-Negev desert. Here diverse nomadic Epipaleolithic groups left behind numerous small open-air sites along the fringe of the northwestern Negev desert dunefield (Israel). Geoarchaeological and palaeoenvironmental analysis of newly discovered Epipaleolithic sites allow better understandings of the unique socio-economic adaptations of these humans.    

The studied middle Epipaleolithic (Ramonian) open-air Ashalim-west site is situated in a unique geomorphic setting atop a slightly deflated surface upon a 3-5 m thick falling dune at the southeastern edge of the Negev dunefield. The dune is comprised of very fine sand that differs from the common vegetated linear dunes (VLD) of the Negev dunefield, dominated by fine sand. The falling dune mantles a 2^nd-order wadi slope of a ~40 m high plateau of Eocene chalk, interbedded with chert beds that probably served for lithic production. The small wadi drains into the Besor basin, the largest ephemeral stream in the northwestern Negev, and the only one that currently transverses the dunefield. Therefore, opposed to smaller basins, it was prone to damming by a wide band of encroaching dunes that may have led to extensive water bodies upstream dune dams and possibly beyond drainage divides.

Four OSL ages in the range of 16.5±0.8 – 15.5±0.8 ka from the upper ~2 m of two sections at the Ashalim-west site correlate with raw portable OSL signals, and reflect rapid aeolian deposition. This deposition, synchronous with the main sand incursion episode into the Negev dunefield during the Heinrich 1 cold event (Roskin et al., 2011), closely fits the age associated with the Ramonian character of the overlaying lithics.

The Heinrich 1 massive aeolian episode may have led to major damming of the Besor basin and widespread expansion of dune-dammed water-bodies upon the Besor floodplains. 1.5 km northeast to Ashalim-west site, remains of slightly later Middle Epipaleolithic (Geometric Kebaran) and Late Epipaleolithic (Natufian and Harifian) are sited on top of fossilized aeolian sand between synchronous seasonal dune-dammed water bodies (Goring-Morris, 1997; Vardi et al., 2018). Here OSL ages of aeolian and fluvial sand beneath the sites also date to the Heinrich 1 period. Later and less intense episodes of dune-damming in these parts of the Besor basin may have allowed for short-term camping upon dune crests and flanks adjacent to water bodies. The perched setting of Ashalim-west, overlooking the largest Besor basin, along with two other Middle Epipaleolithic (Ramonian and Mushabian) sites (Rosen, 1990; Rosen and Kolska-Horwitz, 2005) therefor differs from the abundant Epipalaeolithic open-air sites along the dunefield fringe and may indicate a local choice of high grounds during times of intense dune-damming and water body expansion.