Although the researchers favor a linguistic identification with
Arawak, people of several other important language families build the round villages, too, and the current inhabitants in fact are Carib-speakers who explicitly trace descent from the ancient people who occupied their sites. The date of the prehistoric site system is late prehistoric, between about 1450 and 1000 years cal AD. Both the ancient and modern people practiced horticulture and agroforestry, and their sites have patches of anthropic black soil and extant anthropic forests, which constitute lasting human impacts on the habitat (see Sections ‘Anthropic black soils’ and ‘Anthropic forests’). These features, though less extensive than those on the major floodplains of the Amazon, nonetheless show that such impacts of occupation took place away from the main floodplains, contrary to environmental determinist theory. Fludarabine Also recognized recently, the so-called geoglyphs are quite different from the other monuments. Geoglyphs so far have been found primarily in a 250 km long area of Brazil, Bolivia, and Colombia in terra firme habitat, at both small and large rivers ( Parssinen et al., 2003, Schaan et al., 2007 and Schaan et al., 2012). Like the Ecuadorian Formative mounds, geoglyphs are artificial constructions on dry, non-flooded land, not on wetlands. Hundreds have
been found, revealed by recent deforestation for ranching. If currently forested areas nearby also have such structures, researchers suggest that a total of ten times that number. In principle, the geoglyphs could be detected within intact forest, as topographic anomalies in geophysical or remote learn more sensing surveys, but prospection is still in a preliminary stage. Unlike habitation mounds, these reflect a primarily ritual, socio-technic, and esthetic character. The name refers to their geometric iconography. The large earth constructions are in the shape of quadrangles or circles or combinations of those, surrounded by ditches and walls (Fig. 11). The circles are between 100 and 300 m across, the ditches are at least 10 m wide and 1–3 m deep,
with walls from 50 cm to a meter high. Some geoglyphs have ramps, raised roads, or paths. Because no topographic instrument maps of them have been published, their three-dimensional shapes are unclear. In view of their size from one Oxalosuccinic acid to several hectares, their rare, non-utilitarian pottery, and their ramps, geoglyphs are interpreted as places for religious or political meetings, Some have modest amounts of domestic materials as well, though they do not seem primarily refuse mounds or defensive works. Based on limited dating, most appear to be about 1200–1000 years old, but new dates take some back to the beginning of the common era. Although it had been speculated that the land might have been deforested at the time, the stable carbon isotope values for radiocarbon dated charcoal (ca. −28 per mil delta 13C) fits a closed canopy forest.