Lakeside Cemeteries in the Sahara: 5000 Years of Holocene Population and Environmental Change

Background: Approximately two hundred human burials were discovered on the edge of a paleolake in Niger that providea uniquely preserved record of human occupation in the Sahara during the Holocene (,8000 B.C.E. to the present). CalledGobero, this suite of closely spaced sites chronicles the rapid pace of biosocial change in the southern Sahara in response tosevere climatic fluctuation.Methodology/Principal Findings: Two main occupational phases are identified that correspond with humid intervals in theearly and mid-Holocene, based on 78 direct AMS radiocarbon dates on human remains, fauna and artifacts, as well as 9 OSLdates on paleodune sand. The older occupants have craniofacial dimensions that demonstrate similarities with mid-Holocene occupants of the southern Sahara and Late Pleistocene to early Holocene inhabitants of the Maghreb. Theirhyperflexed burials compose the earliest cemetery in the Sahara dating to ,7500 B.C.E. These early occupants abandon thearea under arid conditions and, when humid conditions return ,4600 B.C.E., are replaced by a more gracile people withelaborated grave goods including animal bone and ivory ornaments.Conclusions/Significance: The principal significance of Gobero lies in its extraordinary human, faunal, and archaeologicalrecord, from which we conclude the following:(1) The early Holocene occupants at Gobero (7700–6200 B.C.E.) were largely sedentary hunter-fisher-gatherers withlakeside funerary sites that include the earliest recorded cemetery in the Sahara.(2) Principal components analysis of craniometric variables closely allies the early Holocene occupants at Gobero with askeletally robust, trans-Saharan assemblage of Late Pleistocene to mid-Holocene human populations from the Maghreband southern Sahara.(3) Gobero was abandoned during a period of severe aridification possibly as long as one millennium (6200–5200 B.C.E).(4) More gracile humans arrived in the mid-Holocene (5200–2500 B.C.E.) employing a diversified subsistence economybased on clams, fish, and savanna vertebrates as well as some cattle husbandry.(5) Population replacement after a harsh arid hiatus is the most likely explanation for the occupational sequence at Gobero.(6) We are just beginnin

Submerged notches and doline sediments as evidence for Holocene subsidence

The possibility of Holocene subsidence along the northern coast of the Corinth Gulf is often mentioned in the literature; however, systematic detailed evidence that submergence (e.g. of archaeological remains) does not simply depend from eustatic sea-level rise is most often missing. In this paper, a new detailed study of submerged tidal-notch profiles along the limestone coast has shown that periods of sea-level stability are intercalated with periods of rapid subsidence or gradual relative sea-level rise. It appears that most of the sites considered, seem to have been affected by a relatively recent co-seismic subsidence of about half a meter, whereas during the longer period, by stages of relative sea-level stability and/or gradual relative sea-level rise. This evidence of subsidence is confirmed by radiocarbon dating in doline sediments, suggesting that during certain periods, a relative sea-level rise was much faster than the raising suggested by glacio-eustatic or hydro-isostatic estimations. Juxtaposing a list of known earthquakes occurred in the area shows that several earthquakes (e.g. the 1981 one for the easternmost sites considered) are potential candidates for the recent co-seismic displacements and thus supporting the geomorphological interpretations. © 2011 Elsevier Ltd

Chemical, biological and hydrological controls on the 14C content of cold seep carbonate crusts: numerical modeling and implications for convection at cold seeps

Understanding the hydrology of cold seep environments is crucial to perform accurate estimates of fluid and chemical fluxes at sedimentary wedges. Shallow convection processes may affect fluid flux estimates and could favor the destabilization of gas hydrate accumulations, increasing the sediment-ocean methane flux. Evidence for the occurrence of convection at cold seeps, however, is still limited. We use the concentration of 14C (D14C) in carbonate crusts formed at cold seeps of the eastern Mediterranean Sea as a tracer for convective recirculation of seawater-derived fluids. A numerical model is applied to investigate the controls on 14C incorporation in cold seep carbonates. Our simulations show that increased amounts of CH4 in the expelled fluids result in elevated crust D14C, while high Ca2+ and HCO3− concentrations produce the opposite effect. Convection is the only transport process that can significantly increase crust D14C. Advection, bioirrigation, eddy diffusion and bioturbation instead, have little effect on, or produce a decrease of, crust D14C. In addition, the presence of old or modern carbon (MC) in host sediments prior to cementation and the 14C-decay associated to the time needed to form the crust contribute in defining the D14C of carbonate crusts. We then use the model to reproduce the 14C content of the eastern Mediterranean Sea crusts to constrain the chemical and hydrological conditions that led to their formation. Some crusts contain relatively low amounts of 14C (−945.0<D14C ‰<−930.2) which, assuming no ageing after crust formation, can be reproduced without considering convection. Other crusts from two sites (the Amsterdam and Napoli mud volcanoes), instead, have a very high 14C-content (−899.0<D14C ‰<−838.4) which can only be reproduced by the model if convection mixes deep fluids with seawater. Order-of-magnitude calculations using the Rayleigh criterion for convection suggest that the slow seepage (about 10 cm year−1) of low salinity (20‰) fluids at the Amsterdam sites could trigger haline convection there. On the Napoli mud volcano, where high-density brines are expelled, density-driven convection cannot take place and other processes, possibly involving the rapid movement of free gas in the sediment, could be important

Radiocarbon Dating of Calcined Bones: Where Does the Carbon Come from?

Over the past decade, radiocarbon dating of the carbonate contained in the mineral fraction of calcined bones has emerged as a viable alternative to dating skeletal remains in situations where collagen is no longer present. However, anomalously low 13C values have been reported for calcined bones, suggesting that the mineral fraction of bone is altered. Therefore, exchange with other sources of carbon during heating cannot be excluded. Here, we report new results from analyses on cremated bones found in archaeological sites in Africa and the Near East, as well as the results of several experiments aiming at improving our understanding of the fate of mineral and organic carbon of bone during heating. Heating of modern bone was carried out at different temperatures, for different durations, and under natural and controlled conditions, and the evolution of several parameters (weight, color, %C, %N, 13C value, carbonate content, crystallinity indexes measured by XRD and FTIR) was monitored. Results from archaeological sites confirm that calcined bones are unreliable for paleoenvironmental and paleodietary reconstruction using stable isotopes. Experimental results suggest that the carbon remaining in bone after cremation likely comes from the original inorganic pool, highly fractionated due to rapid recrystallization. Therefore, its reliability for 14C dating should be seen as close to that of tooth enamel, due to crystallographic properties of calcined bones.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Dating the early phases under the temenos of the Qaṣr al-Bint at Petra

International audienc

Climate change and human occupation in the Southern Arabian lowlands during the last deglaciation and the Holocene

Paleohydrological and archaeological evidence from the Southern and South-Eastern Arabian Peninsula reveal strong relations between phases of human settlements and climate change linked to the Indian monsoon system. During the early to mid-Holocene, large fresh-water lakes extended in the lowland deserts of Ramlat as-Sab'atayn (Yemen) and Wahiba Sands (Oman), which were very similar to those occurring in the North, in the Rub' al-Khali (Saudi Arabia), at that time. Many archaeological sites, characterized by scattered stone artefacts, ostrich-eggshells and bones around hearths, are related to this lacustrine phase, which culminated around 10 000-8000 cal yr B.P. in the lowland deserts before the lakes progressively dried up. The last record of fresh-water bodies' extensions date back 7300 cal yr B.P. at Shabwa (Yemen) and 7500 cal yr B.P. at al-Haid (Oman). Then, fresh-water was probably available only from seasonal run-off from adjacent highlands, where paleolakes persisted into the late Holocene. Dry climate conditions in the inland desert of Yemen during the late Holocene coincide with a phase of intensive human inhabitation as testified by development of irrigation in the piedmontane areas, numerous necropolises of built collective burials and houses

Évolution paléogéographique du Ja'alan (Oman) à l'Holocène moyen : impact sur l'évolution des paléomilieux littoraux et les stratégies d'adaptation des communautés humaines

During the mid Holocene, climatic, eustatic and tectonic fluctuations characterised the east coast of Arabia. These had an effect upon the equilibrium between Neolithic peoples and the coastal environment. Geo-archaeological data from the eastern region of the Ja 'alan (Sultanate of Oman) indicate numerous variations in the dynamics of the coastal ecosystems (sea, lagoons and mangroves). These variations led the human communities to adapt to the new ecological conditions, as is reflected in the changes in the archaeological faunal spectra. Peoples of the 6th to 4th millennia mainly exploited coastal resources - collecting molluscs. The 3rd millennium Early Bronze Age cultures that followed responded to these ecological constraints by adopting a considerably more specialised marine economy - coastal and deep-sea exploitation - as well as an intensification of regional economic exchange related to the development ofpas- toralism and oasis agriculture in the foothills of the hinterland. In addition to temporary fishing settlements, there were also harbour sites that undertook long-distance exchange.Les fluctuations climatiques, eustatiques et tectoniques qui ont caractérisé la côte orientale de l'Arabie à l'Holocène moyen ont régulièrement modifié les équilibres entre les populations néolithiques et le milieu littoral. Le bilan des données géoarchéologiques de la région orientale du Ja 'alan (Sultanat d'Oman) indique de nombreuses variations dans la dynamique des écosystèmes côtiers (mer, lagunes, mangroves). Elles nécessitent de la part des communautés humaines une adaptation aux nouvelles conditions écologiques, sensible notamment dans l'évolution des spectres de ressources animales identifiées sur les sites. Alors que les populations du VIe au IVe millénaire se concentrent sur et exploitent surtout le littoral (amas coquilliers), les cultures du Bronze ancien qui leur succèdent au IIIe millénaire répondent à ces contraintes par une spécialisation marine nettement plus affirmée (prédation littorale et hauturière) et une intensification des échanges économiques à l 'échelle régionale en relation avec le développement de l'élevage et d 'une agriculture d'oasis dans les piémonts de l 'arrière-pays. Aux stations temporaires spécialisées dans la pêche viennent s 'ajouter des sites portuaires tournés vers les échanges à longue distance.Berger Jean-François, Cleuziou S., Davtian G., Cattani M., Cavulli F., Charpentier Vincent, Cremaschi M., Giraud J., Marquis P., Martin Chloé, Mery Sophie, J.-C. Plaziat, Saliège J.-F. Évolution paléogéographique du Ja'alan (Oman) à l'Holocène moyen : impact sur l'évolution des paléomilieux littoraux et les stratégies d'adaptation des communautés humaines. In: Paléorient, 2005, vol. 31, n°1. Anciennes exploitations des mers et des cours d'eau en Asie du Sud-Ouest. Approches environnementales, sous la direction de Jean Desse et Nathalie Desse-Berset. pp. 46-63