A Database for Orkney’s Legacy Radiocarbon Dates

Radiocarbon measurements have served as valuable data for Orcadian archaeologists from the early days of radiocarbon to the current era of archaeological interpretation.

Soon after the initial publication of the first radiocarbon measurements from Orkney in the 1970s (Shotton et al. 1974), interpretations of Orcadian radiocarbon data became central in seminal archaeological texts of the New Archaeology era (Renfrew 1979, 1985; Griffiths 2017). In the 1990s, Skara Brae served as a central case study in one of the first publications describing Bayesian chronological modelling methods (Buck et al. 1991), which are now widely used in Britain and are transforming archaeological interpretations globally (Bayliss 2009, 2015). Most recently, a study published this month in Antiquity by Bayliss et al. (2017) presents the most up-to-date Bayesian synthesis for chronological data from the Orcadian Neolithic. Currently, that paper is the most viewed on Antiquity’s webpage with an abstract that has been viewed over 2,000 times, demonstrating the high-influence this study will have on future work.

As this past work demonstrates, the most well-published research programs in Orcadian archaeology dealing with radiocarbon data have focused on the Neolithic. This situation has not changed much over the years and the major chronological work undertaken by the ongoing Times of Their Lives project has been exclusively Neolithic in focus. Yet, there has been robust radiocarbon dating of more recent archaeological time periods in Orkney and there is potential for similar work involving re-dating, re-evaluating, and/or modelling this data. As a Research Associate at the Scottish Universities Environmental Research Centre’s (SUERC) Radiocarbon Laboratory, I have been heavily involved with several ongoing projects focused on modelling Norse and medieval chronologies in Orkney, but there is much more Orcadian chronological data that could be revisited with contemporary techniques.

A tool for cultivating this potential future research is the topic of this blog post: Orkney14CLegacy; a database of information about legacy radiocarbon measurements from Orkney that I have been compiling as a component of the Orkney: ‘Beside the Ocean of Time’ project. Included are the radiocarbon measurements from Orkney in the Scottish Radiocarbon Database, which is described by Ashmore et al. (2000) and currently available on Canmore. Every archaeological radiocarbon measurement from Orkney published before 2006 is included in the database.

While much of the information in Orkney14CLegacy can be viewed on many separate Canmore webpages, an advantage of this new database is that it serves as a single comprehensive source for information about the legacy radiocarbon measurements from Orkney. Original sources for radiocarbon information are not provided on Canmore, but this is something included in Orkney14CLegacy so that users can easily track down publications with the referenced information.

The information on this database can enable some insight into the Deep Time of human history at Orkney. For example, Figure 1 presents a sum probability for all the calibrations of the radiocarbon measurements included in Orkney14CLegacy. Notable here, is a sizeable drop in the sum probability in the first millennium BC during the Late Bronze Age and Iron Age. Figure 2 presents an alternative way for visualising this trend, by counting through time the number of radiocarbon measurements that have calibrations with median values in different 500-year intervals. Again, there is a sizeable drop from 1250 BC–AD 250, which I suspect is because the first millennium BC has not have been of high interest for Orcadian radiocarbon dating research. Essentially, this highlights a gap in chronological understanding for Orkney’s archaeology and shows that there is much potential for future chronologically-focused research for Iron Age Orkney (dovetailing the findings of Hamilton et al. 2015 for the future potential of chronologically-focused research on the British Iron Age).

Probability graph

Figure 1. Sum probability for radiocarbon calibrations of measurements in Orkney14CLegacy using the appropriate terrestrial or marine calibration curve of Reimer et al (2013), OxCal v4.3 (Bronk Ramsey 2017), and, in the case of the marine samples, a ΔR value (−63 ± 53 years) calculated for the correction of radiocarbon measurements from marine organisms from the far north of Scotland (Russell 2011).

A histogram

Figure 2. Number of radiocarbon calibrations for measurements in Orkney14CLegacy with median values in different 500-year intervals.

While version 1 of Orkney14CLegacy is complete, there is much that could be included in future updates. Specifically, the database currently does not include radiocarbon measurements published after 2006, but the pace of radiocarbon submissions from Orkney to the SUERC Radiocarbon Laboratory have only accelerated over the past decade. I know of hundreds of radiocarbon measurements from Orkney published since 2006 (for example Bayliss et al. 2017) and it is very likely that hundreds more will be published over the next decade.

Including these more recent measurements in Orkney14CLegacy with future updates could help make the database a useful resource for archaeologists. My colleagues at SUERC focused on archaeology and radiocarbon dating are certainly interested in doing this. For example, one of our new PhD students (Kathleen McCaskill) funded by Historic Environment Scotland will be updating the database with measurements from Westray and Papa Westray as part of her PhD work.

Regardless, I hope that Orkney14CLegacy will be of some use to archaeologists in its current form. Excel spreadsheet with Orkney14CLegacy.


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