New constraints on geomagnetic field intensity variations in the Balkans during the Early Byzantine period from ceramics unearthed at Thasos and Delphi, Greece (original) (raw)
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Surveys in Geophysics, 1998
The knowledge about past secular variations of the geomagnetic field is achieved on the basis of archaeomagnetic researches of which the Bulgarian studies form an extended data set. In Part I (Kovacheva and Toshkov, 1994), the methodology used in the Sofia palaeomagnetic laboratory was described and the secular variation curves for the last 2000 years were shown. In Part II (this paper), the basic characteristics of the prehistoric materials used in the archaeomagnetic studies are emphasised, particularly in the context of the rock magnetic studies used in connection with palaeointensity determinations. The results of magnetic anisotropy studies of the prehistoric ovens and other fired structures are summarised, including the anisotropy correction of the palaeointensity results for prehistoric materials, different from bricks and pottery. Curves of the direction and intensity of the geomagnetic field during the last 8000 years in Bulgaria are given. The available directional and intensity values have been used to calculate the variation curve of the virtual dipole moment (VDM) for the last 8000 years based on different time interval averages. The path of virtual geomagnetic pole (VGP) positions is discussed.
W. S. Downey, I. Liritzis, 2013
Archaeointensity results were obtained from ceramic sherds incorporated in the 'mortar' of two Rhodian Byzantine churches. Samples were analysed using a modified Thellier method with samples orientated so that the Natural Remanent Magnetization is at right angles to the applied laboratory field. Only a few samples showed high magnetic stability and an archaeointensity result was obtained from ceramic sherds (tilebrick) from the lower interior walls of the church (Afandou Ka-tholiki). Comparison with the Geomagnetic Field Variation plot indicated the probability density of possible dates between ~1000 to ~1500 AD. a date, broadly consistent with historical records.
Journal of Radioanalytical and Nuclear Chemistry, 2001
Archaeomagnetic studies in Bulgaria have a long history and the well established secular variation curves of the three elements of the ancient geomagnetic field (declination, inclination and intensity) for the last 8000 years enable the dating of archaeological features of burnt clay, independently of other methods. The determination of ancient palaeointensity is the most difficult characteristic and requires very cautious evaluation of the suitability of the burnt clay material. The present paper is an overview of the methodological progress in studying the suitability of the materials for archaeomagnetic investigations. The main rock-magnetic methods and summary of the most common results are presented involving the archaeomagnetic practice in the palaeomagnetic laboratory in Sofia. In addition, supplementary information obtained by magnetic measurements, which can be helpful for archaeology, are discussed. An example of archaeomagnetic dating procedure is also presented.