Archeomagnetism in the use of brick dating lanos
In the laboratory the samples were cut into cylindrical specimens of standard size (diameter = 25.4 mm, height = 22 mm). In calculating the mean direction for the entire kiln the hierarchy of specimens from samples was maintained.Clearly the acquisition of new data from Italian sites is needed to enrich the Italian database and to establish a SV curve for Italy before 1640 AD, when Athanasius Kircher made the first direct measurement of both declination and inclination of the Earth's field in Rome (Cafarella 1992). Symbols: full dot = declination; open dot = apparent inclination; figures: peak-field (m T) or temperature (°C) values. Magnetic mineralogy was investigated by isothermal remanent magnetization (IRM) measurements (Fig.This paper presents 28 new directional results from archaeological sites in Italy (Fig. (c) Normalized intensity decay during AF demagnetization of specimens from the hearth at Chiesa San Francesco (UDN1- No. 4a) and thermal demagnetization of IRM components (Lowrie 1990) (Fig. In most cases saturation is reached in low fields (200–300 m T) and almost all magnetization is erased at temperatures between 520–580°C, indicating a soft, low-coercivity mineral as the dominant remanence carrier; accordingly a magnetite near mineral with impurities or maghemitization.The new Italian SV curve can be used for archaeomagnetic dating of Italian artefacts, even though caution must be paid for the period 9th–12th century AD and times older than 8th century BC, when only few data are available and error envelopes are large.During the last few decades archaeomagnetic studies have attempted to establish the variation of the Earth's magnetic field prior 16th century, when the earliest direct measurements started.During the last 2 yr, samples have been collected from three sites in southern Italy (Vagnari, Ascoli Satriano, Canosa—Nos. In the case of three of the large kilns (Massinigo and Carlino—Nos.
Although Italy has a rich archaeological heritage, Italian archaeomagnetic data are still sparse in comparison to those of other countries where the quantity and quality of archaeomagnetic data allow the construction of reliable secular variation (SV) curves; e.g.
France (Thellier 1981; Bucur 1994; Gallet 2002), Bulgaria (Kovacheva 1997), United Kingdom (Clark 1988; Tarling & Dobson 1995; Batt 1997), Hungary (Márton 1996, 2003; Márton & Ferencz 2006) and Germany (Schnepp 2004; Schnepp & Lanos 2005).
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.
Published 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.