At later times, such as late MIS 4, MIS 3 and MIS 2, marshes existed in Azraq when other records show regional dry and cold conditions.**********Transition from arid to hyper-arid environment in the southern Levant deserts as recorded by early Pleistocene cummulic Aridisol2011Rivka Amit a,*, Ori Simhai a,b, Avner Ayalon a, Yehouda Enzel b, Ari Matmon b, Onn Crouvi a,b, Naomi Porat a, Eric McDonald cThe time at which deserts established their current arid or hyper-arid conditions remains a fundamental question regarding the history of Earth. Cosmogenic isotope exposure ages of desert pavement and welded, calcicegypsicesalic Reg soils that developed on relatively flat alluvial surfaces 2 Ma ago in the Negev Desert indicate long geomorphic stability under extremely dry conditions. Over a short interval during their initial stage of development between 1e2 Ma, these cumulative soils are characterized by calcic soils reaching maximum stage III of carbonate morphology. This interval is the only period when calcic soil horizons formed on stable abandoned alluvial surfaces in the southern Negev Desert. Since 1 Ma pedogenesis changed toward more arid soil environment and the formation of gypsicesalic soil horizons that were later followed by dust accumulation. The dichotomy of only moderately-developed calcic soil (stages IIeIII) during a relatively long time interval (105e106 years) indicates an arid environment that does not support continuous development but only occasional calcic soil formation. The very low d18O and relatively high d13C values of these early pedogenic carbonates support soil formation under arid climatic conditions. Such an environment was probably characterized by rare and relatively longer duration rainstorms which occasionally allowed deeper infiltration of rainwater and longer retention of soil moisture. This, in turn enabled the growth of sparse vegetation that enhanced deposition of pedogenic carbonate. At 1 Ma these rare events of slightly wetter conditions ceased and less atmospheric moisture reached the southern Negev Desert leading to deposition of soluble salts and dust deposited in the soils. The combination of long-term hyperaridity, scarcity of vegetation and lack of bioturbation, salts cementation, dust accumulation and tight desert pavement cover, has protected the surfaces from erosion forming one of the most remarkably stable landscapes on Earth, a landscape that essentially has not eroded, but accumulated salt and dust for more than 106 yr.3. Methods The methods used in this study are aimed at characterizing thesoil properties resolving the cycles of soil formation in the cumulative-welded soil profile which are exposed for long time. We characterized the soil by its geochemical profile and particle size distribution (PSD).*******Abandonment ages of alluvial landforms in the hyperarid Negev determined by luminescence datingN. Porat a,*, R. Amit a, Y. Enzel b,c, E. Zilberman a,Y.Avni a, H. Ginat d, D. Gluck a,bIn hyperarid regions, pedoturbation is minimal and the silt andclay dust particles that are deposited on top of the surfaces do not infiltrate below the gypsic horizon (0.30.7 m). For luminescence dating, these particles can be avoided by sampling immediately below that horizon and by using only sand-size particles in analyses (Porat et al., 1996; 1997). Past moisture contents in these regions is well constrained; the