Magnetic gradiometry and ground penetrating radar applied in Estearia of Penalva (MA)

In this work we present the geophysical methods magnetometry and ground penetrating radar (GPR) as tools used in finding traces of preterit occupations at the archaeological site of Otter Lake, located in the municipality of Penalva, state of Maranhão, Brazil. Because of the size of the area, of about 10,400 m², and the short geophysics campaign, magnetic measurements were performed with a gradiometer, in a sampling grid of 2.5 m. The anomalies found show a thermo-remnant magnetization from the burning of clayl, and also from sources not related to archaeological materials, such as pieces of tack and riding horseshoes, nails and hooks, among others. In locations with anomalous magnetization, 14 GPR profiles were obtained with a 400 MHz shielded antenna in order to locate and differentiate more precisely the archaeological and existing structures. The results presented in this work allowed the verification and evaluation of the potential of geophysical methods as an auxiliary tool in archaeological studies, which has been proven by the success of the indications of the targets and the subsequent excavations which revealed the presence of pottery fragments and coal related to the archaeological site.