Geophysical, geochemical and arable crop responses to archaeological sites in the Upper Clyde Valley, Scotland
This thesis considers the geochemical links between geophysical survey results from, and responses of barley crop growth to, the existence of plough-levelled archaeological sites. It takes as a starting point the results of magnetic and resistivity surveys undertaken at three sites in the Upper Clyde Valley, Lanarkshire, Scotland. Two of the three sites produced geophysical results that closely matched the evidence for archaeological remains recorded using oblique aerial photography. The third site was largely unresponsive to geophysical prospection techniques. These mixed responses prompted a closer examination of why barley crops respond to plough-levelled remains, and why the geophysical data gathered tend to correlate with the growth responses. To allow an examination of the growth responses, a series of pot-based growth experiments were carried out under glasshouse conditions, and these were followed up by ICP-MS analysis of the plants and the archaeological soils in which they had grown, in an attempt to link any changes in elemental compositions with the growth responses, and to the geophysical responses recorded at the soil sampling points or for the features from which the soils were taken. The results of the experimental work revealed that although soil moisture content has a role in the development of both crop marks and geophysical anomalies, other factors are also involved, including changes in elemental concentrations in soils and plant material, soil pH changes and the redox potential of the archaeological soils.