Africa-Eurasia connections: Human dispersals, coastal environments, tectonics and the Arabian Peninsula
Geoff Bailey, 2011.
Data copyright © Prof Geoff Bailey unless otherwise stated
This work is licensed under the ADS Terms of Use and Access.
Primary contact
Prof
Geoff
Bailey
Department of Archaeology
University of York
King's Manor
Exhibition Square
York
YO1 7EP
England
Tel: 01904 433917
Resource identifiers
- ADS Collection: 872
Overview
We set out to investigate the possibility that the Red Sea Basin was a focus for early human occupation and movement between Africa and the Arabian Peninsula.
Our work included reconstructing Quaternary shore-lines, modelling and mapping tectonic landscapes and underwater exploration. We dated archaeological sites in relation to submerged topography, palaeoenvironmental and palaeoclimatic records.
The results will be used to assess the time, depth and continuity of human occupation in coastal regions and to explore hypotheses of habitat preference and geographical constraints on migration patterns.
Six of our major findings and achievements
1. We have developed a revised chronostratigraphic framework for the Palaeolithic sequence along the Red Sea coastline of the Arabian Peninsula. Preliminary survey carried out along the southern section coast has demonstrated that:
- Some lava fields are as old as 1.3ma, while the raised coral terrace 3-5m above present sea level probably dates from the last interglacial (c. 125ka)
- At the coastal archaeological sites reported in the literature, the coral terrace is stratigraphically later than the basaltic lava flows, not earlier as previously reported.
- The artefacts associated with these features are all surface finds and therefore postdate the geological features on which they sit. Thus the Lower Palaeolithic artefacts could be as early as 1.3ma and the Middle Palaeolithic artefacts as early as 125ka, but both could also be considerably later.
2. We have produced detailed bathymetry maps of the Red Sea showing variations in the position of the coastline and the potential for human occupation and crossings of the southern end of the Red Sea. Over the last glacial cycle, substantial areas of the continental shelf would have been exposed. This would have provided easy transit routes at the northern end of the Red Sea across the dry Suez basin and the southern Sinai Peninsula, bypassing the Nile delta. At the southern end of the Red Sea, the Bab el Mandeb Strait, currently some 30 km wide, would have been reduced to a long, narrow and shallow channel.
3. We have improved our understanding of the tectonic geology of the Red Sea Basin, including rift dynamics, volcanism and salt tectonics. Tectonically induced change is of interest from two points of view.
Trimix dive in the Red Sea. Image: T JenkinsOne is the effect of rift propagation and widening of the Red Sea, which, for the earlier part of the Pleistocene back to the presumed exodus of humans from Africa about 1.8ma, may have been of greater significance.
Over the past 3.2 million years, spreading rates of 16mm per year at the southern end of the Red Sea have been estimated, equivalent to a widening of about 3km over the period of interest.
We do not know whether the rate of spreading was continuous or episodic, particularly for the last 790 thousand years of normal magnetic polarity.
We have therefore begun to analyse and date carbon, oxygen and strontium isotopes in deep sediment cores from the Red Sea, on the assumption that significant variations are associated with increased hydrothermal activity linked with seismic pulses, rather than with climate change.
Since the amplitude of eustatic sea-level change was lower in the early Pleistocene, it is arguable that the advantages of a narrower channel for human transit at glacial maxima were cancelled out by a higher sea level. But these tectonic effects on palaeogeography might be quite sensitive to variations in local topography and rates of seismic activity, and require further investigation.
Probably of greater local significance on the Farasan Islands are the effects of salt tectonics.
4. A second effect of active tectonics is to create and maintain topographically complex environments that enhance ecological diversity, trap water and sediment, and create topographic barriers that help to protect vulnerable humans from other predators and select for an emergent human ability to manipulate and capture mobile prey.
We have begun to develop mathematical and computing methods for converting SRTM (Shuttle Radar Topography Mission) data to maps of topographic 'complexity' on a continental, regional and sub-regional scale.
These provide a proxy measure of tectonic activity and can be used to predict favourable human habitats and pathways of dispersal at a variety of analytical scales.
5. We have developed methods for investigating deeply submerged cultural landscapes, using divers trained in nitrox and trimix gases, and hand-held and ROV (Remotely Operated Vehicle) video.
We carried out a preliminary exploration of underwater caves on Vladi's Reef, Gibraltar, in 2005, and commenced the underwater excavation of one of these caves.
6. During the past six months, we have undertaken a first pilot study of the Farasan Islands in the Saudi waters of the Red Sea.
At sea levels lower than about -20m, the islands would have been connected to the Arabian mainland, and have a highly convoluted shoreline and complex underwater topography, where archaeological material would be well protected from rising sea level.
We have surveyed the islands themselves, and we have identified approximately 1000 well-preserved Holocene shell middens.
We have identified the geological and topographic features associated with these sites, and have begun to map similar underwater features associated with earlier submerged shorelines.
We have received considerable local support for our work and expect to capitalise on this favourable framework of co-operation to extend our network of scientific collaboration, and to refine our mapping of underwater topography and the search for underwater archaeology
