Combining Novel and Classical Methods Give Artefacts Deeper Background

The Roman bronze lamp was found from Kavastu peat bog in 1902. It was last used for illuminating in 5th–6th century AD.
The Roman bronze lamp was found from Kavastu peat bog in 1902. It was last used for illuminating in 5th–6th century AD.

A Roman bronze lamp was found in Kavastu peat bog (Estonia) in 1902.

Now, more than 110 years later archaeologists have reconstructed the provenance, possible itinerary and changing use of the lamp over half a millennium, and across thousands of kilometres[1].

One of the scientists involved, Ester Oras, researcher at Institute of Chemistry and Institute of History and Archaeology of the University of Tartu, said they combined various scientific (laboratory) methods with classical archaeological approaches like typochronology and finding a context. “We managed to combine the metallurgical analysis of artefacts with organic residue analysis to identify the fuel used in the lamp, and more importantly determine (using AMS dating) the last time during which the lamp was used for illumination purposes,” she explained and added that the latter provides them with a date after which (tpq: terminus post quem) the lamp and the bars might have been concealed in the Kavastu peat bog.

Wider View of the Journey of the Lamp

Oras says that thanks to these analyses they were able to establish that the fuel used in lamp was of plant origin, possibly olive oil (e.g. not blubber or animal fat), and that it was last used for illumination sometime around 5th–6th century AD, which is several centuries after the lamp was made (around 1st–2nd century AD). “Thus, the lamp that was made somewhere in the Mediterranean region at the turn of the era, travelled several thousands of kilometres and was concealed in Kavastu almost half a millennium later. In this part of the world and at that time the lamp was rather seen as important raw material (copper alloy) for making local jewellery and the like,” she described the journey of the lamp.

Thus, Oras explained, the wider contribution of Kavastu bronze lamp case study to archaeological research is that one has to be very source-critical when working with rare and foreign items in peripheral regions, and that it can be extremely useful to employ various scientific analytical methods in order to better reconstruct the life history of such unique artefacts, even a century after their initial discovery.

New Methods Take Us to the Molecular Level of the Past

Researchers now used AMS dating, which is widely applied all over the world in archaeology, to establish a secondary chronology of a single artefact. However, organic residue analysis as such is rather new, even though it is becoming more and more popular in archaeology, Oras explained. “It can have a very wide range of applications, since it aims to analyse various organic remains left either in or on top of very different archaeological and historical artefacts, like pots, stone tools, art objects, or in various contexts, like sediments, unidentified lumps of organic matter,” she said.

For instance, Oras’ current project at the Institute of Chemistry focuses on 800-year-old pots form burial contexts to reveal the concept of ritual food, and perhaps even food for the afterlife in conversion era North-East Estonia. “We have also analysed the earliest pots in Estonia and figured out that these were preferably used for processing aquatic products like fish and aquatic mammals. The same methods can be used for analysing visible organic residues on stone tools, or medicine pots from the modern period,” she mentioned.

So the applications of organic residue analysis are very wide ranging from early prehistoric to the contemporary period. What is more, the geographical region is not a limit either. “Going to a molecular level of analysis is something which just cannot be achieved with traditional archaeological methods. Faunal and floral remains could be used as indirect indicators of, for example, what was  eaten all those centuries ago, but with these it is also a matter of preservation, representation and availability. With organic residue analysis we can go to the direct sources—the food remains in the exact pots from which people ate and ones they used for cooking. And as the pottery is the most common archaeological find, numerous questions from very different materials from various contexts (burials, settlements, hill-forts etc.) can be asked,” Oras noted and added that the most important thing, however, is finding a good and intriguing question and problem setting.

Multidisciplinary is the Way to Go

Oras referred to continuing with organic residue analysis in Tartu in Estonia as a kind of mission, since there are very few laboratories specialising in organic residue analysis in the Baltic Sea region, and thus there is both a need and good opportunity to develop the field in our region. “We have very good facilities and instruments available here, but more importantly, we also have people from geology, chemistry and other fields, willing to collaborate with archaeologists. This is the key when staring to develop a certain field of research. Secondly, I have invested considerable time and effort into developing these specific skills, but still feel there is a lot to learn and explore. As they say—appetite comes with eating!” Oras said.

Her future plans evolve around several topics. First of all she would very much like to look deeper into combined biomolecular analysis bringing together both lipids and proteins. “This is a very new field in organic residue analysis in general, but since proteomics is a well-developed field actually available here in Tartu, this would be certainly one way to go,” Oras explained.

She admitted that she has also some infrastructural dreams—she longs for GC-C-IRMS, a specific instrument for analysing isotopes in single compounds which is one crucial instrument in organic residue analysis. At the moment she is using these facilities in the UK and Sweden.

Finally, this young and high-flying researcher said her bigger aim is bringing together different approaches like organic residue and food remains analysis, stable isotope based dietary studies, faunal and floral remains, ancient DNA. “Something truly multidisciplinary, perhaps even transdisciplinary, to answer the great questions about the past and provide better substantiated and more nuanced stories about the past, be it, say, the arrival of dairy products and beginning of extensive milk consumption, or influence of Viking Age trade and other networks in Estonia,” she underlined.

[1]Oras, E., Higham, T. F. G., Cramp, L. J. E., Bull, I. D. (2017) Archaeological science and object biography: a Roman bronze lamp from Kavastu bog (Estonia). Antiguity. Volume 91, Issue 355 pp. 124-138. DOI:

This article was funded by the European Regional Development Fund through Estonian Research Council.