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geophysical Survey
Meall Greigh
During the first season of geophysical work at the Meall Greigh shielings, the University of Birmingham geophysical team surveyed an area of approximately 15,000m2 in July 2003.
Targets of interest for the geophysical survey included any signatures of hearths that might be associated with the shieling structures, working areas associated with the buildings, pits, trenches, and any other features or activity areas. In addition, the team was also interested in the position of the shieling grounds within the larger Ben Lawers landscape. In order to collect sufficient data, several geophysical methods were used, including the RM15 resistance meter, FM256 fluxgate gradiometer and SIR3000 ground penetrating radar unit, magnetic susceptibility and resistivity profiling.
The results of the geophysical survey revealed information on the location of shieling structures (mostly corresponding with visible surface features) and other anomalies that may be related to the shielings and past human activity on the site. Interpreted features from the geophysical survey were used to guide the locations of excavation trenches in September 2003.
Tombreck
A geophysical survey season was conducted at Tombreck in April of 2004. A combination of ground penetrating radar (GPR), resistance, and magnetometer surveys were conducted at Tombreck. Multiple geophysical methods were employed in order to provide the most comprehensive non-invasive information on the archaeological and geological nature of the survey area.
Initial review of the three data types suggests some overlap of identified features, which will assist in developing a more intuitive approach to the interpretation and understanding of geophysical results.
Shenlarich
The infield site of Shenlarich was surveyed during the last week of October 2004 in very wet, windy and cold conditions. The geophysical survey was positioned on either side (to the east and west) of visible 19th century structural ruins. These ruins appear to correspond with one of the historic Shenlarich settlements mapped by Farquharson in 1769. The main goal of this survey was to assess the feasibility of using geophysical surveys to identify any remnants of the Farquharson-mapped structures from the mid-18th century, plus any earlier structures and possible remnants of human impact on the landscape related to these structures that are no longer visible on the ground surface.
GPR, resistivity and magnetometry surveys were conducted over the period of a week and produced a number of anomalies that may correspond to previous habitation, land use and local geology. While resistivity produced what appears to be a plan map of possible linear foundations, GPR suggests that these anomalies are located in areas where the bedrock is deeper than other areas across the site. Excavations conducted as part of the Spring 2005 Thistle Camp revealed further information on the nature of the geophysical anomalies mapped at Shenlarich.
Kiltyrie Head-dyke
Kiltyrie was surveyed during the week of 7-14 April 2005. The first three survey grids targeted visible turf structures. Preliminary review of the results from the resistivity and magnetometry surveys over these structures did not reveal significant anomalies that could be used to characterize the structure or related features such as pits, fire hearths or compacted floor surfaces.
The fourth survey grid targeted and area of approximately 80m by 40m that contained a number of visible surface features. The geophysical survey mapped a number of possible archaeological anomalies both related to the visible features and others that were not visible on the ground surface.
One 10m by 10m grid was selected over a U-shaped turf structure for intensive re-survey with greatly increased sampling rates. This area (outlined in Figures 5b and 5c) was selected based on the results from the geophysical surveys and the visible ground surface features. Results from these surveys are currently being analysed and will contribute to the assessment of the utility of geophysical surveys for the Ben Lawers Historic Landscape Project.
Meg Watters-Wilkes
