Coastal prehistory in the southern Red Sea Basin, underwater archaeology, and the Farasan Islands

We explore the proposition that the Red Sea Basin was an attractive coastal habitat for human settlement in early prehistory and an important zone of cultural contact and population dispersal between Africa and Asia, rather than a barrier. We use the global record of sea-level change associated with the glacial-interglacial cycle to reconstruct the position of shorelines at different periods, taking into account isostatic and tectonic movements of the Earth's crust. We demonstrate that the Bab al-Mandab Straits would have been reduced to a shallow and narrow channel at the time of lowered sea levels that persisted for most of the glacial period, posing very little obstacle to human movement, even in the absence of watercraft. At the same time, the persistence of low sea levels means that any record of coastal settlement is mostly submerged and inaccessible without underwater exploration. Palaeolithic sites on the present-day coastline are difficult to evaluate because they are mostly surface finds of stone tools lacking stratigraphie context or absolute dates, and are in any case associated, at best, with earlier and short-lived episodes of high sea level. We have therefore begun archaeological survey and underwater exploration in the Farasan Islands. We have recorded approximately 1000 sites on land, mostly shell mounds formed during the past 6000 years. These sites are typically associated with wave-undercut coral platforms formed at the shore edge, and shallow embayments rich in molluscs and other marine life. We have shown that similar features can be found under water down to depths of at least 60 m, representing shorelines formed at periods of lower sea level, and that these features can be mapped, sampled, and photographed by diving teams using mixed gas diving technologies. Future work will be extended to the search for archaeological sites associated with these submerged features.