Geoelectric Signatures of Shaft Tombs in the Guachimontones Region, Western Mexico

Abstract After more than three decades of research by archaeologist Phil Weigand, the pre-Hispanic west of Mexico is now renowned for the presence of the Teuchitlán tradition, characterized by concentric circular pyramids associated with the shaft-tombs tradition. Shaft tombs are characterized by vertical shafts and horizontal chambers. This makes them potential targets for geophysical exploration. This research reviewed what had been written so far about the Teuchitlán tradition, and, considering that shaft tombs are an important element of that tradition, employed electrical resistivity tomography (ERT) to investigate these subterranean structures at the Los Guachimontones and Santa Quiteria archaeological sites. The ERT data were forward modeled and inverted. Forward modeling was carried out to enhance the understanding of these archaeological structures in real contexts. The modeled the tombs imitated the typical boot and bottle designs found in western Mexico, and they demonstrated high resistivity values. ERT data from Los Guachimontones successfully identified resistivity anomalies associated with the tombs, supported by forward-modeling results. However, at Santa Quiteria, while clear subsurface disturbances were detected, conclusive evidence of intact shaft tombs remained elusive. These findings underscore the potential of ERT for detecting shaft tombs but also highlight the challenges posed by complex geological conditions and potential site disturbance.