OF ORACLES, OASES & ISOTOPES: RECONSTRUCTING PALAEOCLIMATES AND CULTURAL HISTORIES FROM SPRINGS IN THE EGYPTIAN SAHARA

The study of modern and ancient springs is critical to the multidisciplinary investigation of the long-term environmental and archaeological history of the region west of the Nile, the present-day hyperarid core of Saharan North Africa. In areas near Kharga Oasis and Bîr Tarfawi, various carbonate fossil-spring deposits (tufa) and lacustrine sediments are in direct association with lithic tools used by Homo erectus and archaic-to-modern Homo sapiens; clearly these now-defunct alkaline spring-fed streams, lakes, and waterfalls are relict from periods of greater effective moisture. This talk will synthesize various petrologic and geochemical studies to reconstruct changing hydroclimatic conditions over the past 300 ka. Over forty uranium-series determinations and optical dates on fossil-spring carbonates and palaeolake muds provide a temporal context for periods of groundwater emergence and surface water storage, and the emplacement of dune sands during arid periods. Deuterium and tritium analyses of the modern groundwater in the Qattara and New Valley regions help us frame the regional hydroclimatic dynamics in context with global records of palaeoenvironmental and cultural change; this will advance our overall understanding of the forcing mechanisms responsible for desert expansions and contractions, as well as how climate changes may be linked to technological innovation, human speciation, and migration “out of Africa.”