International research team under Kiel leadership discovers prehistoric pigment production sites
An international working group led by the Kiel geographers and ecologists Professor Hans-Rudolf Bork, Dr Svetlana Khamnueva, Dr Andreas Mieth and Dr Stefan Dreibrodt from the Institute for Ecosystem Research at Kiel University (CAU) has investigated a recently-discovered prehistoric site for pigment production on Easter Island, and deciphered the manufacturing process of the colour pigments. The researchers thereby recorded the first evidence of pigment production on an industrial scale on the remote South Pacific island. The investigations were carried out by an international team of scientists from the fields of geoarcheology, palaeoecology, micromorphology and geochemistry from Germany, Denmark and Spain. The results were published in the latest issue of the Spanish Journal of Soil Science.
Fascinating Easter Island
Easter Island is considered to be the most remote inhabited island on earth. It was discovered by Polynesians, probably around the 8th or 9th century AD. The unique stone sculptures called moai, which were created by the inhabitants over centuries, have made the island famous all over the world, and ensure today’s significant cultural tourism. For half a century, the island has been intensively studied archaeologically. However, despite extensive research, there are often new discoveries. Thus, during geoarchaeological digs in a valley on the slope of the highest volcano on the island (Ma′unga Terevaka), the Kiel working group discovered hundreds of pits in a fluvial terrace, which are filled with a powdery reddish pigment. Extensive laboratory analyses of the pit fillings helped to decipher the manufacturing process of the pigments.
According to analyses by the geoscientist Stefan Dreibrodt, the red pigment is based on the iron oxide hematite, which the Rapa Nui produced in the pits by heating rock, which was possibly ground. Evidence of the fires comes from charred plant material, found in dark-coloured layers throughout the reddish pigment. Through radiocarbon dating of the charred material, the production of the pigments could be dated to the period of the 15th to 17th century. The Rapa Nui used large quantities of dried grasses as fuel for the pigment production. This could be proven through the analysis of phytoliths, microscopically-small silicate particles which are remnants of plant cells. The specific phytoliths, which are characteristic of certain plant groups, were analysed by Welmoed Out, palaeobotanist at the Moesgaard Museum, Aarhus, and Marco Madella from Pompeu Fabra University, Barcelona. Wood as a fuel was hardly present on Easter Island at the time of the pigment production, because the islanders had already largely cleared the forests, as shown by previous research of the Kiel working group.
The microscopic examination of the pit fillings by the micromorphologist Svetlana Khamnueva also delivered amazing results: The pit fillings are finely-layered on top of each other, making it clear that the process of pigment production occurred in numerous alternating phases of adding mineral raw materials followed by short fires - an extremely time-consuming process, which shows that the Rapa Nui society remained powerful even after the clearance of the forests, and was by no means doomed.
A paint for the stone sculptures?
It has not yet been determined what the red pigments were used for. It is clear, however, that the colour red was once considered holy on Easter Island. It stood for spiritual power, physical strength and fertility. The researchers suspect that the newly-discovered pigments could have been used for body painting, because their fine consistency makes them easy to apply to the skin. Another use could have been the decoration of stone images, or painting of the world-famous moai. The research team would like to discover more about the potential uses of the pigments, and also about where on the island the mineral raw material was obtained.
The fieldwork on Easter Island was done in cooperation with - and with the support of - the German Archaeological Institute (DAI) in Bonn. The laboratory analyses in Kiel, Aarhus and Barcelona were carried out in the respective institutes of the universities.
Original publication: Svetlana Khamnueva, Andreas Mieth, Stefan Dreibrodt, Welmoed A. Out, Marco Madella & Hans-Rudolf Bork. 2018. Interpretation of prehistoric reddish pit fillings on Easter Island: A micromorphological perspective. Spanish Journal of Soil Science 8/2, 236-257.