The recovery at Shi'bat Dihya 1 (SD1) of a dense Middle Paleolithic human occupation dated to 55 ka BP sheds new light on the role of the Arabian Peninsula at the time of the alleged expansion of modern humans out of Africa. SD1 is part of a complex of Middle Paleolithic sites cut by the Wadi Surdud and interstratified within an alluvial sedimentary basin in the foothills that connect the Yemeni highlands with the Tihama coastal plain. A number of environmental proxies indicate arid conditions throughout a sequence that extends between 63 and 42 ka BP. The lithic industry is geared toward the production of a variety of end products: blades, pointed blades, pointed flakes and Levallois-like flakes with long unmodified cutting edges, made from locally available rhyolite. The occasional exploitation of other local raw materials, that fulfill distinct complementary needs, highlights the multi-functional nature of the occupation. The slightly younger Shi'bat Dihya 2 (SD2) site is characterized by a less elaborate production of flakes, together with some elements (blades and pointed flakes) similar to those found at SD1, and may indicate a cultural continuity between the two sites. The technological behaviors of the SD1 toolmakers present similarities with those documented from a number of nearly contemporaneous assemblages from southern Arabia, the Levant, the Horn of Africa and North Africa. However, they do not directly conform to any of the techno-complexes typical of the late Middle Paleolithic or late Middle Stone Age from these regions. This period would have witnessed the development of local Middle Paleolithic traditions in the Arabian Peninsula, which suggests more complex settlement dynamics and possible population interactions than commonly inferred by the current models of modern human expansion out of Africa.

Archaeological investigations undertaken along a proposed highway together with the compilation of available geological and pedological data made it possible to give a first overview of the distribution of Pleistocene aeolian deposits in southwest France. A chronological framework for deposition has been obtained using both radiocarbon (n ¼ 24) and luminescence (n ¼ 26) dating. It shows that aeolian transport was very active during the Late Pleniglacial, between 15 and $23 ka, leading to sand emplacement over a 13 000-m 2 area at the centre of the basin. The Pleniglacial coversands are typified by extensive fields of small transverse to barchanoid ridges giving way to sandsheets to the east. Subsequent aeolian phases, at ca. 12 ka (Younger Dryas) and 0.8-0.2 ka (Little Ice Age), correspond to the formation of more localized and higher, mainly parabolic dunes. At the southern and eastern margins of the coversand area, aeolian dust accumulated to form loess deposits, the thickness of which reaches $3 m on the plateaus. Luminescence dates together with interglacial-ranking palaeoluvisols between the loess units clearly indicate that these accumulations built up during the last two glacial-interglacial cycles. The chronology of sand and loess deposition thus appears to be consistent with that already documented for northern Europe. This suggests that it was driven by global climate changes in the northern hemisphere. The relatively thin aeolian deposits (and particularly loess) in south-west France is thought to reflect both a supply-limited system and a moister climate than in more northern and continental regions.

International audienceNumerous periglacial features (polygons, nets, soil stripes, ice-wedge pseudomorphs and sand-wedge casts, involutions) have been recorded in France by examining bibliographical sources and aerial photographs. These data show that a large part of France was affected by permafrost during the Pleistocene and only the southern Aquitaine Basin and Languedoc seem to have been beyond its maximum extent. The first OSL ages obtained from the aeolian infill of wedge structures indicate that at least two phases of thermal contraction cracking occurred in southwestern France between ∼25 and 36 ka. Chronostratigraphical data from loess in northern France indicate that these episodes correspond to the formation of ice-wedge networks associated with tundra gleys. In the latter region, two additional permafrost episodes probably occurred during the Last Glacial, the older one corresponding to the end of Marine Isotope Stage (MIS) 4 around 60 ka and the more recent one to MIS 2 around 19-16 ka. Although stratigraphical data indicate that these episodes were relatively short (about one millennium), relict permafrost may have existed for longer periods in northern France

International audienceDetailed stratigraphic analysis and numerical dating (OSL, IRSL, ESR, 14C) of Pleistocene coversands in southwest France enable the construction of a renewed chronostratigraphic framework for sand deposition. The chronological data obtained from sandsheet units testify to the development of transgressive dunefields since at least the Middle Pleistocene (MIS 10). Three main phases of accumulation occurred during the Last Glacial. The oldest one (64–42 ka) is associated with wet sandsheet facies, histic horizons and zibar-type dune fields, which reflect deposition in a context strongly influenced by the groundwater table. The Late Pleniglacial (24–14 ka) corresponds to the main phase of coversand extension in a drier context. Silty gley horizons suggest, however, local interruptions of sand drifting during GS 2.1. Lateglacial stabilization of the coversands may not have occurred before GI-1c (Allerød), which was typified by the development of cumulic arenosols. These were covered by parabolic dunes during the Younger Dryas. The variations in extent of the emerged continental shelf during the glacial–interglacial cycles may explain the uneven geographical distribution of sand deposition through time. Because of coastline retreat up to 100 km north of 45°N during the LGM lowstand, the coversands were unable to reach the northern part of the basin. Comparison with other European regions highlights stronger affinities of the French record with Portugal than with the Netherlands and Great Britain, probably because of reduced influence of permafros

International audiencehe Land Use and Cover Area frame Statistical survey (LUCAS) database on topsoil properties inEurope was used to map aeolian deposits. The points which satisfy the grain-size criteria of coversands, loess andtransitional facies were extracted from the rasters of predicted soil texture established by kriging of the LUCAS databy Ballabio et al. (2016). A comparison with already available maps, derived from a conventional field approach,shows a good fit in most of the tested areas. The new map, however, suggests a greater extension of loess, whichseems related to the inclusion of thin loess covers, usually omitted by conventional mapping, and the presence ofpreviously unmapped areas due to lack of survey or misinterpretation. The main source of aeolian particlescorresponds to glacio-fluvial sediments at the margin of the Scandinavian and Alpine ice sheets. Coversands andloess form a broad band across northern Europe, and in the Rh^one, Rhine and Danube valleys. Large areas on theoutskirts of these deposits also received a significant loess contribution, which has been reworked in slope deposits.Conversely, southern Europe is characterized by much less loess accumulation. The Atlantic coast has transgressivedune fields that penetrate inland to varying degre

No abstract

a b s t r a c tThe Arabian Peninsula has long been considered as a region devoid of long-term human settlement until the Holocene period, as a result of drastic climatic changes throughout the Pleistocene. It might be expected that the area was deserted during hyper-arid and arid periods, and populated by new migrant groups during humid events, according to a "push and pull" phenomenon. Although this scenario may be perfectly valid for a large part of the Peninsula, a set of recent data points to the persistence of populations in several regions, which may have served as refugia for human groups who developed their own technological traditions. Such a scenario is suggested by:(1) The succession of dense human occupations under arid conditions between ca. 60 and 50 ka, in the Wadi Surdud basin, a small sedimentary basin in the foothills of the Yemeni Western Highlands. This archaeological site complex encompasses several successive human settlements characterized by a Middle Paleolithic tradition which significantly differs from the Middle Paleolithic and Middle Stone Age contemporaneous traditions from neighboring regions; (2) The regional diversity of the Middle Paleolithic throughout the Saharo-Arabian arid belt during MIS 3, expressed by an array of local techno-typological facies that likely relate to distant and disconnected source regions where populations contracted when climate worsened.Together with a set of high-resolution archaeological contexts recently discovered in the Arabian Peninsula and dated to MIS 5, these data suggest that the major human expansion waves which occurred in the region during the Upper Pleistocene are correlated with the wet phases of MIS 5, while populations probably contracted into a few refugia areas at the beginning of MIS 3.

The Shi'bat Dihya 1 site in western Yemen, dated by optically stimulated luminescence to 55 ka, provides insight into the Middle Paleolithic peopling of the Arabian Peninsula. The archaeological layer is interstratified within thick, sandy silt floodplain deposits filling a piedmont basin. Luminescence dates, lack of soil development, and gypsum precipitation indicate a high accretion rate of the floodplain during Marine Isotope Stage 3, in connection with a (semi)‐arid environment. Rapid overbank sedimentation was likely a result of the remobilization of loess material deposited on the Yemeni Great Escarpment at the periphery of the adjacent Tihama coastal sand desert or of other sources. Fabric and size analyses of the lithic artifacts, together with spatial projections, indicate site modifications by floods. Primary modifications include (1) selective accumulation of medium‐sized lithic pieces as a result of hydraulic sorting, (2) bimodal orientation of artifacts, and (3) ripple‐like arrangement of lithics and bone/tooth fragments. The overrepresentation of teeth may also be a consequence of sorting. Although floods have distorted the original site patterning, long‐distance transport of artifacts by water can be excluded, as indicated by relatively high refitting rate, close proximity of artifacts derived from the same block of raw material, and lack of abrasion of the pieces. Therefore, the site is considered “geologically” in situ because its remobilization by water occurred shortly after human abandonment. This study also stresses that the effective preservation of a site cannot be assessed without careful taphonomic study, even in a potentially favorable depositional context such as silty alluvium.