We were recently commissioned to evaluate a proposed housing development near Kirkwall in Orkney. Orkney is one of the richest archaeological landscapes in Britain and therefore there is always high potential for archaeology- with the resulting high risk for developers. Our approach in this case was to carry out a very rapid geophysical survey of the entire site followed by targeted trenching on areas of high potential as defined by the results of the geophysical survey.
The Geophysical survey in this case comprised magnetometry survey. A magnetometer is a geophysical survey instrument which can detect variations in natural magnetism in the soil. This can be caused by buried archaeology or variations in the natural geology. This is a very rapid means of investigating a site – it is possible to cover up to 3 ha per day in good terrain. Rubicon have developed a unique cart system which combines the magnetometer with a dGPS which accelerates the process further and ultimately results in significant savings for clients.
Once the geophysical anomalies have been mapped on site we move on to stage two- targeted evaluation trenches of the anomalies to determine whether they are geological or man-made. In this case we excavated 640 linear metres of trenches over a two day period. The results confirmed the presence of the geophysical anomalies which proved to be largely the result of field boundaries and a drainage system. The use of dGPS allowed us to focus in accurately on the location of these geophysical anomalies.
The net result was the evaluation of a 4.7 ha site within a couple of weeks following instruction, allowing the archaeology to be properly evaluated and the developer to move ahead with the job before the Orkney winter, when the very short working days will take hold. Luckily there was still enough light left in after work hours to enjoy some of the spectacular archaeological sites that Orkney has to offer!