Archaeomagnetic study of a lime kiln at Bazzano (northern Italy)

An archaeomagnetic study was carried out as part of a rescue operation on a lime kiln discovered during the exploitation of a gravel quarry at Bazzano, near Bologna (northern Italy). Based on very poor archaeological information the kiln is dated around 3rd–4th century AD but no other structures have been found in the area to support this age. A hierarchical sampling process has been followed; twelve independently oriented bricks were collected from the circular wall of the baking room from which 35 cylindrical specimens were cut and measured. Demagnetization procedures reveal a single-component, stable remanent magnetization. The dispersion of the mean direction is low, even though some deviations in the remanence direction as a function of the position of the samples in the kiln wall are observed. The archaeomagnetic age of the kiln has been obtained using recent advances on data elaboration involving Bayesian statistics and the preliminary secular variation (SV) curve of Italy. For comparison, the kiln has been also dated using the French SV curve. The ages obtained are in good agreement and suggest that the last firing of the kiln could have occurred as late as at the end of 6th century AD.