By: Jolie Liston
The dense tropical vegetation that has long concealed the true extent of Palau’s ancient cultural landscape on Babeldaob has been unveiled in a groundbreaking manner. The innovative laser technology known as lidar has been harnessed to visually strip away the thick tree canopy, exposing the vast extent, massive size, and diverse shapes of the island’s earth architecture. The magnitude of terraces (oblallang) revealed is staggering, with at least 21 square miles (17.4 percent) of Babeldaob currently known to be covered by these ancient Palauan-built earthworks. This figure is set to soar as surveys with higher resolution lidar, capable of penetrating the dense forests that cloak the island’s rugged interior, are finalized.
Lidar (light detection and ranging) technology creates detailed, three-dimensional maps of the ground surface using pulses of laser light released from a sensor carried on an airplane or a drone. The measurements are taken using the time the laser takes to hit a solid surface and bounce back to the sensor. While most of the millions of laser pulses emitted per second hit vegetation, enough reach the ground to map Babeldaob’s surface. With the support of the U.S. Ambassadors Fund for Cultural Preservation, Guam-based Pacific UAV Corp. (2cofly), in partnership with Bella Wings Aviation, recently carried out a drone-based lidar survey of 2,400 acres in Aimeliik to map the terraced landscape. Their work improves on Palau’s previous plane-based lidar surveys. As a drone flies much slower and lower than a plane, considerably more laser points hit the ground to reveal terracing in areas blurred in previous data sets.
Although modifications to the landscape likely began soon after Palau’s colonization about 3,500 years ago, archaeological evidence indicates that elaborate terrace construction was underway by at least 2,400 years ago. Using only simple tools such as digging sticks and baskets, hills and slopes were sculpted into the huge earth structures we still see today. This amazing human effort would continue for over 1300 years to create a remarkable cultural landscape unequaled anywhere else in the Pacific. During this time, the terraces supported the majority of community activities, being used for habitation, infrastructure, agriculture, defense, and ceremonies and rituals.
The vastness and complexity of Palau’s engineered landscape underscore its cultural significance in ancient Oceania, ranking it among the world’s most impressive monumental architecture. While Melanesia and Polynesia also boast earthworks, the Palauan achievements surpass anything else in the entire Pacific region. The terracing in Palau is unique, connecting to form up to 8 square mile clusters of earthworks. These groupings are interpreted as sociopolitical districts, their power symbolized by the immense size of their earth architecture. Step-terraces and ditches descend up to 20 feet, and the steep-sided, flat-topped high points (“crowns”) rise as much as 40 feet above the surrounding slopes, a testament to the ingenuity and skill of the ancient Palauans.
Demonstrating the ability to organize, finance, and manage the large labor force needed, monumental architecture is associated with increasing sociopolitical complexity. Palau’s earthworks were enormous in size and extent some 2000 years ago, perhaps 800 years before any other Pacific society began to produce such large structures.
Palau’s earthwork landscape is an architectural marvel, built with sophisticated cut-and-fill techniques and still standing a thousand years after its construction. This demonstrates the expertise of early Palauans in soil mechanics, hydrogeological conditions, and engineering principles. Sustaining the inland cultivation system for over a thousand years while managing the erosion and sedimentation during deforestation and terrace construction and use, is a testament to ancient Palauan effective and intensive land management strategies.
Funding for the “Preserving the Legacy of a Monumental Earthwork Landscape Project in Palau” is provided by the U.S. Ambassadors Fund for Cultural Preservation. Awarded to archaeologist Dr. Jolie Liston and the Coral Reef Research Foundation, the project aims to help preserve Palau’s heritage displayed in its earthwork landscape for future generations. This goal is being accomplished using advanced technology, archaeological research, and the collection of oral traditions, all of which include educational and capacity-building components.