A03_P17

Variation of ¹⁴C results from different samples in an archaeological context

Seiler M¹, Svarva H¹, Rzadeczka-Juga I¹, Nadeau M¹

¹The National Laboratory for Age Determination, NTNU University Museum, Trondheim, Norway

Archaeological contexts contain different materials and pieces that can be selected for radiocarbon dating. While one tries to select short lived samples such as plant material, charred seeds, or charcoal from shorter lived tree species, the connection between the samples selected and the event to be dated might be uncertain. Financial considerations prevent the measurement of multiple samples to date single contexts such as a cooking pit or even a dwelling. The small amount of material needed by AMS often leads to the measurement of only one charcoal piece or hazelnut shell.

We analysed different pieces from large samples of mixed charcoal from archaeological excavations in Norway to assess how representative a single piece is for the sample as a whole. We found that the results for the same wood species do match well, while there is a discrepancy between different wood species, particularly older ages for longer-lived tree species, which could be explained by the ‘old wood’ effect. The magnitude of this effect varies between sites, and is more relevant for radiocarbon results with smaller uncertainties.