Geometry by design: contribution of lidar to the understanding of settlement patterns of the mound villages in SW Amazonia

Abstract

Recent research has shown that the entire southern rim of Amazonia was inhabited by earth-building societies involving landscape engineering, landscape domestication and likely low-density urbanism during the Late Holocene. However, the scale, timing, and intensity of human settlement in this region remain unknown due to the dearth of archaeological work and the logistical difficulties associated with research in tropical forest environments. A case in point are the newly discovered Mound Villages (AD ~1000–1650) in the SE portion of Acre State, Brazil. Much of recent pioneering work on this new archaeological tradition has mainly focused on the excavation of single mounds within sites with little concern for the architectural layout and regional settlement patterns, thus preventing us from understanding how these societies were organised at the regional level. To address these shortcomings, we carried out the first Lidar survey with a RIEGL VUX-1 UAV Lidar sensor integrated into an MD 500 helicopter. Our novel results documented distinctive architectural features of Circular Mound Villages such as the presence of ranked, paired, cardinally oriented, sunken roads interconnecting villages, the occurrence of a diversity of mound shapes within sites, as well as the exposure the superimposition of villages. Site size distribution analysis showed no apparent signs of settlement hierarchy. At the same time, it revealed that some small groups of villages positioned along streams exhibit regular distances of 2.5–3 km and 5–6 km between sites. Our data show that after the cessation of Geoglyph construction (~AD 950), this region of SW Amazonia was not abandoned, but occupied by a flourishing regional system of Mound Villages. The results continue to call into question traditional views that portray interfluvial areas and the western sector of Amazonia as sparsely inhabited. A brief discussion of our findings in the context with pre-Columbian settlement patterns across other regions of Amazonia is conducted.