Archaeomagnetism, methodology and applications: implementation and practice of the archaeomagnetic method in France and Bulgaria

Abstract

Recent improvements in archaeomagnetism applied to archaeological baked clay, in France and Bulgaria, are presented in this paper. After reviewing the historical development of the method in France and Bulgaria, and the principles of the method, we present sampling techniques for in situ structures (kilns and hearths) and sets of displaced materials (bricks or tiles). In the analysis protocol, we stress the importance of correcting the magnetic anisotropic effects especially for bricks. We also show how the problem of brittle specimens can be solved by induration. After a review of the published archaeomagnetic data currently available for France and Bulgaria, we present different smoothing techniques applied to data obtained in these countries. Finally, we present the usage of the variation curves of the geomagnetic elements in the past to calculate the archaeomagnetic dates. One of these techniques is based on a Bayesian approach, similar to the case of the dendro-chronological calibration of radiocarbon ages. The main goal of the paper is to highlight for the archaeologists the possibilities of archaeomagnetism for dating purposes and for other problems in archaeology, on the basis of the experience of the laboratories in France and Bulgaria. The developments of selected archaeomagnetic studies in other European countries are quoted and referenced.