Approaches to the archaeological landscape in the South American lowlands: a GIS study in the northeast of Buenos Aires (Argentina)

Abstract

Regional archaeological research focusing on landscape was developed in the southern sector of Punta Indio (northeast of Buenos Aires province, Argentina). That sector, which covers an area of 722 km² (Figure 1), had limited archaeological backgrounds. During fieldwork, systematic prospections were performed, by which four sites linked to hunter-gatherer groups were registered: Los Tres Ombúes, El Puesto, Don Enrique and Corral del Indio (Figure 2), of which the first two were excavated. By integrating the obtained data, it was made possible to understand this sector as a part of the landscape inhabited by hunter-gatherer groups in the Late Holocene (1110-260 years C14 BP; 982-1796 years cal.). This article, on the one hand, aims to present the results of several analyses performed through Geographic Information Systems (GIS), based on original spatial information obtained by an archaeological approach at the southern sector of Punta Indio, as well as its regional context. On the other hand, it focuses on discussing the contributions of this approach to the research of the Late Holocene archaeological landscape in the northeast of Buenos Aires province (Argentina).

The methodological strategy consisted of complementary GIS-based analyses: visibility, mobility, and suitability areas estimation. Three scales were defined for these analyses: the archaeological site, a local study sector and a wider area of 12.000 km² corresponding to the regional scale.

For each considered site, visibility conditions and accessibility to the immediate surroundings were analysed. Regarding visibility, results showed similarities between Los tres Ombúes and Don Enrique, both located on the Río de la Plata coastal plain. From these places, a large portion of the plain is potentially observable. In addition, the visibility conditions of the sites linked to the Samborombón river -El Puesto and Corral del Indio- encompass the watercourse and its surroundings, including the mouths of tributary streams and nearby lagoons (Figure 3). The accessibility to the last sites immediate surroundings proves there was easy access to the river in half an hour duration routes. Moreover, the sites of the Rio de la Plata coastal plain evidence immediate access to the estuarine coast, as well as to minor courses that flow here (Figure 4). According to the obtained model, the distances, easy to walk within half an hour to three hours, could imply access to neighbouring sites. The archaeological places considered for this study are separated from each other by longer distances. However, some of these show relations with others in the area. As the accessibility maps indicate, all the long-range mobility isochrones imply a wider reach than the study sector.

Also, the formulation of transit areas from the optimal routes obtained by GIS (Figures 5-6) allowed us to inquire about the sector mobility and the wider area involving the integration of obtained results with the archaeological knowledge of adjacent areas. The transit areas show the importance that the Río de la Plata estuary and the Samborombón river coastlines, as the Salado river coast, could have had for the human groups’ mobility. In addition, a multicriteria evaluation with regional scope (Figure 7, Tables 1-2) allowed us to obtain a present-day location aptitude model of the inhabited places in the landscape; consequently, it was possible to explore the environment variables possibly linked to the settlement modalities.

Even though archaeological sites are located in some of the higher altitude points in the landscape, the sample does not show a strong influence of the net altitude (Figure 8). Therefore, relative altitude regarding the close surroundings could have had a bigger influence on the site's location. The places showed good visibility conditions and good accessibility to the immediate surroundings, which imply watercourses and bodies that were possibly travelled during the inhabitants’ daily activities. They could have also been linked in mobility nets related to social interaction networks inferred for these groups, which could have mutually visited with different and multiple purposes. According to suitability areas estimation, the sector sites are related to very suitable conditions. That is also verified in the wider area, where the distribution shows a strong link with very suitable locations, near watercourses and bodies or to the Río de la Plata coastline.

As the Samborombón and Salado rivers eventually suffered water excesses, possibly the regional mobility could have had a seasonal component. Also, results suggest that the coast constituted a main route in the northeast of Buenos Aires. Even though the coastline is highly dynamic and presents an accessible and inaccessible sectors alternation, there are nearby shell ridges -longitudinal elevations that probably facilitated human movement in the past.

GIS-based methods essentially helped to understand the Late Holocene archaeological landscape in the northeast of Buenos Aires. This enabled an original interpretation of the landscape considering four factors: the characteristics of the inhabited places, the practices of the hunter-gatherer groups, the settlement modalities and the movements of those groups across the landscape. Consequently, the authors highlight their potential for hunter-gatherer research in South American lowlands contexts.