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International audiencePublished Italian archaeomagnetic data are combined with new data from the Genève and Torino laboratories. A total of 74 directional data is presented with age estimates falling between 1300 BC to 1600 AD, including results from volcanic deposits of unquestionable age. The data set has been analysed using the Bayesian stochastic approach for curve building to produce a preliminary Italian secular variation (SV) curve. Comparison with the French SV curve shows a general agreement but some significant differences are also observed. The new Italian SV curve can be used for archaeomagnetic dating of Italian artefacts, even though caution must be paid for the period 9th­12th century AD and times older than 8th century BC, when only few data are available and error envelopes are large

S U M M A R YA catalogue has been compiled of existing published and unpublished archaeomagnetic directional data from sites in Germany. The data comprise 125 results dated mainly in the past two millennia. The stability of the natural remanent magnetization was proven for most structures with at least a Thellier viscosity test, although for the majority of the data the direction is based on the characteristic remanent magnetization obtained from demagnetization experiments. Rock magnetic experiments carried out on the samples from many of the sites reveal that the dominant magnetic carrier is magnetite, often oxidized or with impurities. For many sites the archaeological age estimate is supported by physical dating methods. While the Roman epoch (0-400 AD) and the period from medieval to modern times (800-1700 AD) are reasonably well covered with data, the time interval in between and the first millennium BC are only poorly covered. The geographical distribution of data throughout Germany shows a concentration along the Rhine valley during Roman times, with in general a better coverage to the north. Nevertheless this data set clearly shows the secular variation during the past three millennia, and it extends the European archaeomagnetic data set considerably.

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SUMMARY Extensive rock‐magnetic investigations have been carried out on baked clays from four kilns (two from Bulgaria and two from Switzerland) found in archaeological sites of different age. Knowledge of the magnetic characteristics of the grains responsible for the archaeomagnetic signal enables us to determine which baked clays have the stablest magnetization and why this is so. This is important in directional studies, but even more so in painstaking palaeointensity studies that require a very careful evaluation of the suitability of the burnt clay material. The proposed rock‐magnetic experiments enable the identification of the carriers responsible for the remanence and an adequate interpretation of the experimental results connected with the palaeointensity evaluation. The experimental methods employed are illustrated with the particular results obtained from each of the four kilns studied. The preliminary elucidation of the magnetic mineralogy of the archaeological samples helps first by obtaining a more reliable palaeointensity result, and secondly by explaining some of the discrepancies in the palaeodirectional results. Examples of successful and failed palaeointensity experiments are given in relation to the magnetic properties previously established for each oven. The burnt‐clay materials in this present study satisfy the essential condition of carrying a thermoremanence. In spite of that, it is shown that there are many factors that can produce undesirable magnetic properties and thus restrict the suitability of these materials for archaeomagnetic analysis. The most important factors influencing the magnetic behaviour during magneto‐diagnostic experiments are: the degree of heating in antiquity, the initial composition of the unbaked material and the burial conditions. The large difference in heating temperatures within a particular archaeological feature is a major cause of variation in magnetic behaviour amongst individual specimens, and so preventing a successful pre‐selection of specimens for palaeointensity experiments. Nevertheless, the study has shown a very good coincidence between the determined rock‐magnetic characteristics and the success rate in palaeointensity evaluation.

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The ophiolites, considered remnants of oceanic seafloor, provide a fruitful source of information on the physical and chemical behavior of the deeper uncored lithosphere. A study of the gabbros in a rather well‐preserved ophiolite from the western Alps (Montgenèvre, France) shows strong evidence for intraoceanic plate deformation. To characterize the different steps of deformation observed in the outcrops, a magnetic fabric study was conducted using the anisotropy of initial magnetic susceptibility (Aims) method. The main conclusions are (1) the Aims is controlled by the paramagnetic ferromagnesian minerals, such as hornblende, resulting from the ocean floor metamorphism close to the spreading ridge (partial amphibolitization) and (2) the magnetic lineation and foliation of the gabbros show a deformation path with increasing strain. A good correspondence between petrofabric and magnetic anisotropies is observed; both suggest that the deformation mechanism was simple shear.