Research goals

[1] To demonstrate that ancient landscapes are preserved on the seabed of inshore coastal waters. It is likely that some exposed landscapes did not survive inundation by rising sea level, and in the case of Newfoundland, the grinding power of annual sea ice may have further limited site preservation.  There is abundant evidence, however, from submerged environments on the Atlantic shore and in the North Sea that rooted forests, undisturbed peat, and in-situ archaeological sites are preserved on the seafloor or thinly buried by marine mud.  Once located and mapped, these landscapes would be sampled to determine age, character (e.g. coastal vs. riverine) and environment (e.g. vegetation, climate).

[2] To locate and record archaeological sites and materials preserved on these submerged landscapes. Although this task may have in the past proven technologically challenging and intellectually frustrating – advancements in seabed mapping and the development of robust predictive models have made survey design more successful.

[3] To understand how early coastal environments facilitated the expansion and growth of the first populations of Ireland and Newfoundland. And how the evolving coastal landscape and marine resources may have stimulated social and cultural change across prehistoric times and into the Middle Ages.

Research plan

SLAN represents a long term research initiative, integrating graduate student education and training into an international multi-institutional, multidisciplinary research programme. Our research strategy incorporates 7 phases:

> phase_1 reconstructing sea-level history

Generate computer-modelled simulation of relative sea-level (RSL) changes, constrained by geological data, that predicts the depth of submerged coastlines at specified time intervals. The RSL simulations are continuously tested against new field data.

> phase_2 mapping coastal evolution

Submerged coastlines at specified time intervals from the model output are plotted against high-resolution digital multibeam sonar imagery of the seabed. The position of the predicted ancient coastlines are used to identify submerged shoreline features directly from the multibeam sonar data. Traditional (low-resolution) bathymetric data have insufficient resolution to permit Phase 2 analysis.

> phase_3 mapping submerged landscapes

Geomorphic mapping of the seafloor employs digital analysis (artificial illumination, shaded relief, vertical stretching etc.) of the 3-dimensional sonar data to locate submerged coastal and estuarine landforms. Subsequent targeted shall seismic reflection surveys penetrate the seabed to generate vertical sections of sub-surface stratigraphy. The acoustic character and structure of these sediments permit the identification of buried palaeo ‘land-surfaces’ (e.g. freshwater lake basins, bogs, lagoons, beaches and terraces).

> phase_4 sampling submerged landscapes

Direct sampling of surface and sub-bottom sediments will provide opportunities to ground-truth our interpretations of sonar data, and to recover dateable material for building transgression chronologies and refining the RSL model simulations.

> phase_5 3D evolutionary models of the maritime landscapes

Integration of sub-bottom seismic data with seabed palaeogeographic reconstructions are used to portray accurate, fully 3-dimensional models of landscape evolution. In this step, post-submergence deposits are digitally removed from the seabed to establish original landscape surfaces; the deposits are subsequently integrated to more accurately reflect landscape burial following transgression.

> phase_6 mapping the archaeological potential of submerged coastlines

The application of a predictive model, based on landscape attributes of archaeological sites will be used to classify the archaeological potential of reconstructed maritime landscapes (see for example Renouf and Bell, 2006). The Renouf and Bell model considers sites at four nested spatial scales. The the two smaller scales (regional and coastal settings) site locations are probably related to the distribution of coastal resources. At the larger scales (shoreline and site settings) site location preferences were likely related to resource access rather than abundance.

> phase_7 archaeological testing of high potential seabed

Finally, remote testing (e.g. geophysics, rov, drop-down-video) and direct sampling (e.g. grabs, corers, divers) of high potential sites will be undertaken by marine archaeologists.