Interpretation of prehistoric reddish pit fillings on Easter Island: A micromorphological perspective

In the context of geoarchaeological investigations on Easter Island several hundred human-made pits filled with reddish silty material were discovered in fluvial terraces of two valleys on the southern slope of Maunga Terevaka, the highest volcano of the island. Micromorphological analysis of one representative pit filling and comparison of its geochemical and physical properties with sediments in the surrounding terrace was performed in order to reconstruct the probable formation and use of the material in the pits. A hypothesis of pigment production by heating of minerogenic iron-rich substrate with grass fuel resulting in formation of hematite is suggested. It is assumed that the pits represented the places for production and storage of the pigments, which were used by Rapa Nui for cultural and ritual purposes. The ongoing interdisciplinary research will enhance the interpretation of the pits and their fillings and contribute to a better understanding of cultural development on Easter Island.