EHG2647 - Ground Penetrating Radar surveys - around Loch of Yarrows (Swartigill Burn)

Investigative Ground Penetrating Radar surveys were carried out by CFA Archaeology in 2007 at five sites in the vicinity of Loch of Yarrows in order to assess the applicability of GPR survey on a range of different sub-surface peat formations. The survey was carried out over a single weekend to allow members of the Caithness Field Club and Yarrows Archaeological Trust to take an active part in the fieldwork. The survey was carried out at locations that were deemed the most profitable and to provide positive results within the given time frame. The site of Swartigill Burn was selected as part of the study owing to the presence of known archaeological remains within a flat area of alluvium alongside the burn of the same name. The extent of the structural remains were not known and it was hoped that the result of the GPR survey would shed light on the extent of the remains, as well as test the effectiveness of the GPR equipment over a different soil regime. A 6m by 12m GPR survey grid was laid parallel to the burn in order to include the alignment of the possible dry stone walls (Fig 8). No test pitting was carried out but a general assessment of the character of the soil was observed within the exposed stream section. The results from Swartigill Burn were mixed. While it appeared that the technique successfully defined the potential limits of the postulated site, it failed to clearly delimit individual features such as walls. Although this was likely to be a reflection of both the nature of the technique and the nature of the archaeological deposit. GPR cannot differentiate between in-situ stonework and rubble. However, other techniques, like area resistance survey can be equally ambiguous on such sites. <1>