Uncovering monumental earthworks in pristine Palau
A project to understand and map Palau’s ‘green pyramids’, monumental earthworks from thousands of years ago, is bringing attention to a largely unknown period of early construction.
Over millennia, humans have shaped and altered the natural landscape, moving millions of tonnes of earth and building terraced hillsides (ouballang), steep and high crowns, deep moats and trenches and large platforms.
It is a very early example of adaptation, with the earliest examples dating back to around 500BC.
Researchers say like Rapa Nui’s giant stone statues and Pohnpei’s Nan Madol, they are man-made displays of power through large, highly visible construction.
The research project is a collaboration between Christian Albrechts University in Germany and the Palau Resource Institute that began in 2017 and is now the subject of an important display at the Belau National Museum. It sought to understand the origin, function, chronology and cultural significance of the earthworks of Babedldaob.
The team has located 137 earthworks covering some 21 square miles, using satellite images, historical photos and knowledge from local communities, as many earthworks were invisible to the untrained eye.
Of those, 14 sites underwent detailed documentation, resulting in the creation of 3D maps. Ten were chosen for geoarcheological research to understand “how the earthworks were built, what they had been used for, how old they are and for how long they had been used”.
The team discovered that construction involved layering of volcanic rock, layers of clay and fertile garden soil, and the presence of many planting pits. All the building materials for the various sites were extracted, reworked, transported, and applied,” the team says. “Millions of tonnes of material were transported during the construction phases.”
The scale of the structures show a large population must have once been present on Babeldaob, and that they had been organised into a coordinated labour force.
The team was also surprised to discover that the earthworks had hardly been affected by erosion or landslides.
Apart from agriculture, the presence of pottery shards and burial pits showed evidence of other uses. The team posit that the shards may have played a role in drainage or to stabilise construction.
Work continues to uncover these ancient structures. Lidar laser technology is being used to visually strip away the thick tree canopy covering many sites, exposing the imposing size and diverse shapes of the monuments. Surveys with higher resolution lidar, capable of penetrating the dense forests that cloak the island’s rugged interior, are expected to uncover more sites.
And in Aimeliik State, a Memorandum of Understanding (MOU) to document and inventory monumental earthworks was signed last October.
The objectives will be accomplished through remote sensing equipment, archaeological fieldwork, and oral history.
