Can magnetometry detect sediment-filled caves? The case study of the Sierra de Atapuerca sites (Burgos, Spain)

Abstract

This work evaluates the potential of magnetometry to detect the inaccessible sediment-filled caves of the Sierra de Atapuerca karstic system. This karst consists of numerous caves filled with sediments that bear outstanding archaeo-paleontological remains from the Early and Middle Pleistocene. In order to find the continuity of the caves, the Sierra de Atapuerca sites have already been the target of ERT and GPR surveys, which have revealed their suitability for detecting different karstic features. Although our expectations were to find positive anomalies when crossing these filled conduits, the results showed a negative anomaly of the magnetic field where these sediments were expected. So far, the only explanation for this phenomenon is that these sediments were deposited in a reversed magnetic polarity period. This theory is supported by the fact that the Matuyama-Brunhes boundary is present in many of the studied caves.