Contribution of stratigraphic constraints of Bulgarian prehistoric multilevel tells and a comparison with archaeomagnetic observations

The general aim of archaeomagnetism is to recover the behavior of the ancient geomagnetic field for a given territory using archaeological baked clay structures that have been well-dated by other independent methods. The Sofia Palaeomagnetic laboratory possesses a large data set for the three characteristic geomagnetic field parameters obtained from one and the same material and covering the last 8000 years. The database accumulated by the authors has been updated several times and the greatest difficulty arose for the prehistoric collections, most of which had no radiocarbon or other chronometric dates. Thus as well as methodological archaeomagnetism problems, the main difficulty concerning the construction of reference curves of the variation of the geomagnetic field is related to the distribution of the experimental results over the absolute time scale. This paper examines the similarity between the archaeomagnetic profiles obtained on multilevel tells from the same prehistoric epochs. It would seem that when 14C dates for multilayer tells are missing, the comparison of such archaeomagnetic stratigraphic profiles with the corresponding chrono-stratigraphic reference profile for the same epoch can be useful in verifying their assumed chronology. However, the described peculiarities connected with the multilevel sites results still show some difficulties for the overall estimation of geomagnetic field variations for a given territory.