Application of Geophysical Methods and Correlation to the Archaeological Record at the Mariano Miró Site, La Pampa, Argentina

Abstract

This article focuses on the geophysical survey results from the Mariano Miró site (Chapaleufú, La Pampa, Argentina). In 1901, a settlement composed of tenant settlers existed at this location. Although the town was ephemeral, it had basic services such as blacksmiths, warehouses, hotels, hairdressers and a population of approximately 500 inhabitants. Post-abandonment, which began in 1911, the remains of the settlement were buried. Nowadays, the field under the site is used for soybean cultivation. Archaeological research at the site began in 2011, applying a fieldwork method focusing on large areas, taphonomic analysis and spatial distribution of archaeological materials. However, the detection of possible below-surface constructions remained pending. Therefore, two combined geophysical methods were employed to optimize the identification of anomalous sectors with possible buried remains. The OhmMapper technique generated a soil map by contrasting electrical resistivity, while we employed a Gradiometer to measure remnant magnetism in subsurface materials. OhmMapper measurements revealed resistive anomalies ranging from 410 to 6000 Ω. They were found in the central and western sectors of the site and possibly corresponded to the remains of construction materials. Magnetic prospecting indicated very weak anomalies, between −1 and 1.3 nT, which could be linked to accumulations of thermoaltered materials in which the signal was enhanced (tiles, bricks or pottery remains). Distributional data from the archaeological record and resistivity and magnetic anomalies were positively correlated. However, in other sectors of the site, a direct correlation between the geophysical and archaeological data has not yet been verified in the field, given the differences in accuracy between the GPS navigator and the differential GPS, used to identify the topographic points and the sectors to be excavated.