This site continues to provide an opportunity to study an archaeologically rich prehistoric palaeo-landscape, cost effectively and in detail. Its investigation can address key research questions and help inform decision makers when addressing the impact on comparable sites ahead of offshore development impacts. During 2013 the site was subject to extensive research as part of the Arche-Manche cross border project.
Analysis of geophysical survey data that has been collected from the seas around Europe over the past few decades has revealed a network of well-preserved pre-inundation landscapes with relict river channels, lakes and sheltered lowlands.The western Solent is an example of a pre-inundation landscape that has become accessible.
It was a resource rich valley cut by a river floodplain that proved to be suitable for occupation. Like other fluvial systems that drained the UK at the end of the last glaciation, it filled with estuarine silt as sea level rose.Today, the process of sedimentation has reversed following the formation of the Solent. This now runs perpendicular to the original channel.
As a consequence, erosion has cut a natural section through a 7m thick accumulation of brackish water silt to expose a submerged forest 11m below UK Ordnance Datum that dates to over 8,000 years old. Once exposed, erosion can be up to half a metre a year. The loss of material is unfortunate but it has provided access to the base of a palaeo-channel that would otherwise be covered by many metres of sediment.
Today, underwater at Bouldnor Cliff, a 1km long corridor of extremely well preserved landscape is exposed. Within it, four archaeological sites have been identified and two are being investigated in detail. One site is associated with a fluvial sand bar and is dominated by worked and burnt flint, while the other is a site of industrial activity with well-preserved worked timbers suggesting the construction of a log boat.
The different sites are recorded in relation to their surrounding landscape features to characterise the most attractive areas for occupation. These will be the locations with the highest archaeological potential. Characterising analogous sites prior to commercial development can help inform mitigation strategies and reduce risks of impact.
Over the last 10 years, a range of methods have been employed to excavate and record material from the palaeo-deposit. Box sampling was used for recovery of fine environmental and archaeological material while larger pieces of worked timber were raised individually. To date over a thousand pieces of worked and burnt flint have been recovered from just 9 square metres while over 600 have been recovered in the last 2 years following the natural erosion of a 8 metre wide section. Dozens of timbers, pieces of string and extensive samples of charcoal have also been recovered.
The period of occupation is late Mesolithic but the discovery of tangentially split timber and a carefully prepared bi-facial flint axe demonstrate technologies not apparent until the British Neolithic. In addition, the use of obliquely blunted blades, akin to tool types found in the ParisBasin, infer cultural links with the continent. The site brings into focus patterns of Mesolithic occupation, it queries our understanding of regional technological capabilities and raises questions about human dispersal during the final severance of Britain from mainland Europe. While inferences can be drawn from the archaeological record in adjacent lands, the archaeological material that is being discovered underwater contains unique evidence from this time of great change.