Underwater Cave Excavation in Gibraltar

For most of human history on this planet over the past 2 million years, sea levels have been substantially lower than the present in response to the expansion of the continental ice sheets. At the maximum of the last glacial period about 20,000 years ago, sea level was 130 m below the present. For most of the period back to 125,000 years ago (the previous period of interglacial climates and high sea levels), sea level fluctuated between 40 and 60 m below the present. A similar pattern can be traced back over at least the past 1 million years.

This large drop in sea level exposed extensive areas of the continental shelf for human settlement, offering potentially more attractive and diverse coastal resources and terrestrial environments than their adjacent hinterlands. Yet, archaeological evidence for the use of coastal areas and marine resources is largely confined to short-lived periods of high sea level, and most of it to the past 6000 years of modern high sea level. This has resulted in a severely distorted view of world prehistory and a belief that marine resources such as molluscs, fish and sea mammals were largely ignored until a very late stage of human development.

Significant advances have been made in the exploration of this underwater realm over the past 20 years in shallow water and in reference to quite recent archaeological sites. But the prevailing archaeological opinion is that we would learn little from exploration of more deeply submerged coastlines that we could not discover more cheaply and with less risk of failure on dry land.

A growing number of underwater archaeological finds, the development of new technologies of underwater investigation, and the realisation that a valuable archive of archaeological evidence is being destroyed by erosion and commercial exploitation of the seabed are slowly changing attitudes. Nevertheless the costs and logistical difficulties of underwater investigation continue to pose a significant deterrent to such research, and reinforce the belief that the outcome of such investigations is too uncertain and too speculative to be worth the risk.

In this project we will undertake excavation of underwater caves offshore of Gibraltar and at a depth of 20-25 m, using a diving team trained in mixed gas diving, which allows safe and prolonged working time underwater. We will combine this with mapping of the wider area around the caves using remote sensing equipment to identify the character of the original terrestrial landscape and to place the caves into their wide landscape setting. Ongoing investigations of the famous Gibraltar cave sites on the present-day shoreline, with long sequences extending over the past 125,000 years and numerous remains of Neanderthals will provide additional context and points of reference to place the results of underwater exploration into a wider archaeological context.

We believe that these underwater caves are the only currently known features at this depth anywhere in the world that offer a good prospect of preserving and discovery archaeological deposits, and that they might therefore offer a unique window into human activities on shorelines formed when sea levels were lower than the present.

The results of this work will show whether archaeological deposits are preserved underwater in such conditions, and in what ways any archaeological data recovered from them provides new information about patterns of human occupation of coastlines and use of marine resources during periods of lowered sea level. The work will also provide experience in the development of techniques of underwater archaeological investigation and results that can be built on by other similar projects in other parts of the world.

We expect the results to be of interest to a very wide academic, scientific and public constituency interested in sea-level change and its human impact, and in the reality or otherwise of 'lost underwater civilizations'.