INVESTIGATING HISTORIC COASTAL SAND INUNDATION, SHETLAND UK

Coastal sand invasions in northern Europe have been identified from prehistoric archaeological sites and are recorded in historic records from as early as the 9^th Century to the late 19^th Century. Widespread sand mobilization in this area has been particularly associated with the Little Ice Age. These large-scale movements of sand caused widespread property damage, and rendered large tracts of land unsuitable for agriculture. The study site, the Township of Broo in Quendale Links of the Shetland Isles, UK, was inundated by sand during the 17^th and 18^th centuries. This area, described as the most valuable property in Shetland in the 1660’s, was rendered useless by the 1730’s due to sand invasion. Archaeological excavations at Broo, approximately 2 km from the coast, have exposed a farmhouse and barn complex dating to the late 17^th century and, buried by up a meter of sand, with potentially other buried farmsteads in the area. Ground Penetrating Radar (GPR) was employed as a preliminary tool to measure sand extent in the area, to determine potential locations for coring stratigraphic and chronologic information, and to identify archeological sites. Unconsolidated sand depth was measured by using the unique GPR signature of the sand/Old Red Sandstone basement contact, identified by strong crossbedding and a distinctive dip to the south-southeast. Near the shoreline and in the dune areas, 100 MHz antennae provided 10m of penetration through sediments, but did not image the base of the unconsolidated sequence in all areas, suggesting a potentially thick and long record with more than period of one sand invasion at this location. As an archaeological tool, the initial GPR, results were disappointing in that existing architecture was not easily resolved within the saturated sands of the region. Future work with 500MHZ antennae and additional processing of existing lines could separate architecture from the surrounding stratigraphy.