A large-scale magnetic survey in Makrygialos (Pieria), Greece

Abstract

A large-scale magnetic survey was conducted in the archaeological area of Makrygialos. The site was threatened due to the construction activities carried out in the area, as part of the national highway re-route project. Geophysical prospection contributed to the archaeological evaluation of the site, which was based mainly on the salvage excavations that took place prior to and after the geophysical survey. Magnetic prospecting was applied on a routine base, in order to cover a large area in a short period of time. Also, magnetic susceptibility was used to acquire detailed information of the stratigraphy of the ditches revealed by the excavations. The Le Borgne contrast was calculated and was used as an index of the magnitude of the magnetic anomalies. Geophysical data were processed by a number of filtering techniques, including the removal of regional trends and Hanning smoothing. Fourier transformation was applied and bandpass filtering procedure was based on the examination of the power spectrum of the data. In addition, two-dimensional inversion filtering was performed at specific parts of the data set, in an effort to rectify the significant geophysical anomalies of the site and obtain more information about their width and magnetization. The results of the geophysical survey were able to highlight a system of three curvilinear ditches, which excavation data suggested were probably dug during the Neolithic period. Various linear and geometrical anomalies, related to subsurface structures, are included among the other geophysical features encountered at the site. The geophysical prospecting techniques were able to map more than 60,000 m2 of the site, a large portion of which has now been destroyed by the construction activities for the national road. In this way, geophysical maps can be used as a valuable source of information for the future study of the site. The present case study illustrates the impact of geophysical exploration in the management of archaeological sites threatened by large-scale construction projects. © 1997 John Wiley & Sons, Ltd.