Picking Needles from a Magnet: Obstacles and (Hidden) Opportunities of Magnetic Prospection in Challenging Environments
Tuna Kalayci, Apostolos Sarris
Abstract Magnetic prospection can be considered as the main arsenal of archaeologists due to its sensitive response to anthropogenic variations. It is a rapid approach, becoming the fastest one compared to other techniques due to the multiple sensor arrays, enabling a landscape approach to archaeological problems. Nevertheless, the foundational physics behind this technique limits its use for particular conditions; e.g. magnetic clutter, magnetic contrast between background soil and material culture. Feasibility of the survey is also determined by the conditions of the study area; e.g. lack of modern features, absence of diffused archaeological material and relatively smooth topography. Complex Mediterranean landscapes, however, provides immediate challenges, both for the physics and the feasibility of magnetic prospection.
Various parameters can influence the success of a magnetic survey and a number of magnetic anomalies either remain masked or are difficult to interpret. Dense distribution of tiles in the Roman Nikopolis (Epirus) severely hindered the actual archaeological targets (roads and structural remains). The hematite ores in the vicinity of the ancient settlement of Hyettos (Boeotia) were indicative of the parent soil deposits of the area that made the magnetic survey an impossible task. In Palaepaphos, Cyprus, extreme values of vertical magnetic gradient were encountered over large patches without being able to be further verified through GPR or soil magnetic susceptibility measurements. Drawing from the examples of Naxos, Sicily and Therasia Island, Cyclades, it becomes clear that volcanic and volcano-sedimentary formations present further challenges in data collection, processing, and interpretation efforts.
This paper is a manifestation of some of the problematic situations encountered in the magnetic prospection of archaeological sites in the Mediterranean region. However, other geophysical methods are also discussed for further illumination of the magnetic prospection in magnetically enriched contexts. Results of this comparison highlight the importance of a priori information on the archaeology of sites and the employment of multi-sensor approach.
