Open questions

Despite the scientific research, many questions regarding Babeldaob's earthworks remain open. Firstly, the maps showing the distribution of the earthworks are incomplete due to the inaccessibility of the inland (cf. Ito 1998; Osbourne 1966, 1979). The existing maps give the impression that earthworks only occur along the coasts and along the overland road. This is in contradiction to local informants, who report that terraced hills also occur in the interior of the island and that up to 70% of Babeldaob is anthropogenically altered (personal comm. Kautechang Vince Blaiyok).

The distribution of the earthwork complexes and their topographical location has implications for the construction technique. Was material removed from natural hill flanks, has material been transported and added on, or are the earthworks built by a combination of removal and backfill? Where would applied material have come from? Where was removed material deposited? Can the transition between natural and anthropogenic relief elements be distinguished? Is there evidence for soil formation within the stratigraphies of the earthworks? To what degree did the century-long erosion effect the relief of the features? All these questions are based on the interaction of natural environmental conditions and the degree of human influence. An important question in this context is how many people were involved in the construction and maintenance of the earthworks. Today Babeldaob is very sparsely settled, predominantly in the immediate coastal area. The amount, the wide distribution, and the monumental scale of the earthworks, however, suggest that a large number of people used to live on Babeldaob. Many of them must have been involved in the construction of the complexes.

The function of the earthworks is also subject of debate. The use as settlement areas, as fortifications, for ritual or representational purposes, or agricultural use is being discussed. The interpretation that the terraces were settlements is based primarily on an abundance of surface ceramics (c.f. Lucking 1981). Rampards and ditches on and around the facilities are interpreted as fortifications. It is also discussed that due to the elevated position the crowns were used as observation points (Kaschko 1998; Liston and Tuggle 2006; Osborne 1966).

Burials have been found within some earthworks. This and the few oral traditions that state that the terraces serve as steps for the gods between the divine and the human spheres (Jolie and Miko 2011: 188) indicate a ritual function. The monumentality of the facilities and the associated display of labor availability are interpreted as a sign of a representative / political function (Liston 1999; Liston and Tuggle 1998; Wickler 2002). To prove agricultural use of the terraces, phytholith studies were carried out to a limited extent. The small amount of phytholiths, however, could not substantiate a definite use for horticultural practices (cf. Scott Cummings 1996; Lucking 1984).

Due to the numerous rescue excavations alongside the construction of the overland road and some archaeological research projects, there are a number of radiocarbon dates for the earthworks. They are the basis for the definition of different earthwork phases (see above, see Liston 2009). So far, however, there has been no evidence as to whether the earthworks are single-phase or multi-phase structures; both in the vertical and in the lateral extent.

For two of the largest and most imposing terrace systems (Ngerbuns el Bad in Aimeliik and Sisngebang in Ngeremlengui) no dates were available before our investigations. Accordingly, neither the time of construction of the largest complexes nor their diachronic development or abandonment are known. This includes the possibility that smaller earthwork systems were abandoned in favor of the larger centers.


Challenges of an Island Ecosystem
The human factor
The monumental earthworks of Babeldaob
The first contact with the outside world
Brief history and state of research
Open questions
Geoarchaeological and archaeological research
Involvement of the local population
Project data