New Archaeointensity Results from the Iron Age in Southern Africa

Abstract
In this study we present new palaeointensity measurements on Iron Age (200 AD – 1840 AD) pottery from the southern Africa region, where there is only limited data available at present. Many sites only produce a single accepted palaeointensity result and we have therefore opted to focus on analysis at sample level as opposed to site level, which is more common in traditional archaeomagnetic investigations. This strategy allows a large number of locations to be included and, as we demonstrate, a chance to evaluate regional and global geomagnetic field model predictions. Some of the initial palaeointensity estimates are anomalously low (< 10 µT), but after adding more strict criteria that relate to direction statistics, the intensity estimates that are accepted fall into a narrower range consistent with geomagnetic field model predictions. Overall, we find that the new data are consistent with the limited regional data and available secular variation curves. An archaeomagnetic dating example is presented following established procedures adapted for sample level data by considering that the real uncertainty of the palaeointensity estimate is largely unknown. The modified dating approach is applied to a Botswanan site from this
study, which is dated to the mid- to late- Iron Age.