Dealing with radiocarbon reservoir effects in human and faunal skeletal remains
|PhD ceremony:||Mr J.P.R. (Jack) Dury|
|When:||March 18, 2021|
|Supervisors:||prof. P.D. (Peter) Jordan, PhD, prof. dr. G. Eriksson|
|Where:||Academy building RUG|
Archaeology relies on the ordering of past events to study cultural developments. This has traditionally been achieved by looking at the stratigraphic depths of materials relative to one another. In this way, chronologies/timelines of past technological progressions and stylistic changes can be built. Radiocarbon dating revolutionised archaeology, allowing for direct, numerical estimates of a sample’s age. This allowed for more detailed past chronologies than was previously possible. Radiocarbon dating utilises the radioactive decay of carbon-14 to estimate a sample's age with older samples having less carbon-14. Shortly after the emergence of radiocarbon dating, however, it was demonstrated carbon-14 is not evenly distributed globally. Typically, there is less carbon-14 in marine and freshwater systems compared to the atmosphere. This results in aquatic samples appearing older than they are, a phenomenon known as a ‘reservoir effect’. Reservoir effects have proved problematic, sometimes resulting in archaeologically incorrect chronologies/timelines being constructed. Reservoir effects can, however, be managed. This thesis demonstrates how archaeologists should interpret radiocarbon dates from aquatic samples, avoiding erroneously old age estimates. Through careful sample selection, considering complicated carbon source mixing, measuring the scale and variability of reservoir effects within a single ecosystem and using prior knowledge about a sample's age, the dating of aquatic material can be greatly improved. This thesis also details a novel method of dating teeth, reducing uncertainty. With aquatic resources being vital for human populations and across the globe and for millennia, the ability to interpret aquatic radiocarbon dates is incredibly important.