Geoarchaeological signatures of anthropogenic soils in southeastern Uruguay: Approaches to formation processes and spatial–temporal variability

Abstract

This contribution focuses on the interpretation of earthen mound formation processes in the lowlands of the Pampa biome, southeastern Uruguay, through the integrated analysis of sedimentological and archaeological data. The three analyzed mounds from the La Tapera site have different heights and radiocarbon chronologies, indicating different construction periods across the last 4000 years. In addition, soils from surrounding plains were analyzed to provide a comparative basis for geoarchaeological characterization. From granulometric, compositional, and geochemical results, we identified different soil classes and several anthropogenic layers inside the earthen structures. Mound soils stood out from the rest due to higher levels of P, soil organic matter (SOM), and micro‐artifact content, leading to their classification as hortic Anthroportic Udorthent soils or hortic‐cultural cumulic archaeo‐anthrosols. Geoarchaeological differences between mounds are inferred as variations in the formation processes and/or construction technologies, possibly related to the functionality and height of the structures. Evidence from this contribution demonstrated the existence of ancient ways to produce nutrient‐rich long‐lasting anthropogenic soils that left persistent geoarchaeological signatures on the landscape. These findings highlight the need to broaden the discussion, culturally and geographically, about the genesis and development of management practices and associated indigenous knowledge to include the lowlands of southeastern South America.

Evaluación de riesgo y vulnerabilidad de montículos indígenas en contextos de producción agropecuaria en la región de India Muerta, Uruguay

“…Este tipo de impacto tiene su origen en el manejo ganadero que utiliza los montículos como zonas elevadas de refugio frente a crecidas estacionales y como zonas arboladas de sombra. En 24 montículos se generaron impactos por los usos actuales de los residentes locales, relacionados con la extracción de tierra y/o el uso de los montículos como huertos, debido a la alta fertilidad de los sedimentos que los componen (del Puerto et al, 2021). Esta característica, vinculada a los niveles de nutrientes más elevados que los suelos naturales que los rodean, tiene un origen antropogénico, aspecto que también ha sido documentado en el Delta de Paraná (Castiñeira et al, 2014).…”

From Mounds to Villages: The Social Construction of the Landscape during the Middle and Late Holocene in the India Muerta Lowlands, Uruguay

“…This aspect makes it possible to suggest a closer relationship between the mound sites of the three zones than with those of other regions, for example, those located towards the eastern side of the sierra. If the chronologies obtained to date in the region are taken into consideration, it can be seen that there are contemporaneities between several mounds sites, as well as between mounds within the same group [24,35,36,39].…”

“…During the mid-Holocene, from ca. 4800-4500 years cal BP, the first earthen mounds appeared in the lowlands of the India Muerta region in the department of Rocha, Uruguay [24,35,36]. The mound architecture spread across a wide area ca.…”

“…In the basin of Merín lagoon, these wetlands were connected to tidal flats, paleolagoons, flood plains and abandoned watercourses [64]. The mounds continued to be inhabited and built in the region of India Muerta in those times [36].…”

Absence of bones in archaeological sites from the southeast of Uruguay: Taphonomy or human behavior?

“…Heated clay aggregates are present from the base to the top of the mound, while pottery only appears in the upper layers of LP, about 500 years ago (thermoluminescence age). Heated clay aggregates have also been described in the sediments from CH and La Tapera sites(del Puerto et al 2021), indicating the potential use of these hard, coarse aggregates as building material for the mounds.…”