Lakes of the Edeyen Ubari and the Wadi al-Hayat

The Fazzan has evidence for the previous existence of numerous lakes at various times during the Quaternary period; attesting to periods of decreased aridity. These palaeolakes are of importance for two reasons: firstly they provide a focus for prehistoric human activity and possess a rich archaeological record; and secondly, they provide dateable evidence of previous climatic conditions, which can be correlated with similar evidence from other parts of the Sahara to reconstruct the palaeoenvironmental history of the region. The main problem limiting adequate survey of these palaeolakes is the difficulty of access to the Sand Sea of the Edeyen Ubari, coupled with the very large areas involved. Optical remote sensing provides a useful tool for discriminating and locating palaeolakes on the basis of the mineral signature (mostly calcium carbonate and gypsum) they left behind when the water evaporated. However, some important palaeolakes do not possess such a clear mineral signature, and attempts to map the palaeohydrology using only optical remote sensing systems would result in significant undersampling. It is necessary, therefore, to also utilise Synthetic Aperture Radar (SAR) remote sensing systems as well. These active systems detect palaeolakes on the basis of surface characteristics, such as roughness. Remote sensing images also provide a means of plotting navigable routes to the palaeolake sites, enabling efficient field survey. These surveys have added to our understanding of the archaeological record of the Edeyen Ubari and surrounding areas, indicating periodic activity at these sites during Achuelean, Mousterian, Aterian, earlyand mid-Holocene times. Dating of palaeolake sediments supports the archaeological chronology and confirms a growing body of evidence suggesting wetter climates associated with peaks in solar insolation in this part of the Sahara. Introduction The climate history and geoarchaeology of the Sahara are attracting increasing amounts of attention, as they complement the much more complete data from more temperate climatic zones. However, the Sahara presents numerous difficulties for conventional fieldwork, due to the aridity of the climate and the difficult terrain presented by features such as Sand Seas (Edeyen). These problems are particularly evident in Fazzan, southern Libya, where recent research has identified significant records of archaeological and palaeoenvironmental information. Present day rainfall in Fazzan is less than 20 mm per year on average, and exhibits high interannual variability (Pallas 1978). However, both archaeological remains and geomorphological evidence in Fazzan indicate that this currently hyper-arid region experienced wetter phases in the past (Drake et al. this volume). Rock carvings and other archaeological remains attest to the existence of a more benign environment during the early to mid-Holocene, when humans and large humid-climate fauna existed in currently inhospitable areas (Cremaschi and di Lernia 1998). Lake sediments and various geochemical crusts demonstrate the existence of open 1Department of Geography, University of Reading 2Department of Geography, King’s College London 3Department of Geography, University of Leicester 4School of Archaeology and Ancient History, University of Leicester 5Tyndall Centre for Climate Change Research, University of East Anglia The Libyan Desert: Natural Resources and Cultural Heritage