The water people, phase II: GPR and SSS detailed image of wood stilts and ceramic materials in underwater archaeological sites in Maranhão, Eastern Amazon

Abstract

Archaeological evidences in the Amazon region are rare to be found due to the soil acidity in this large biome. The leaching of the soil, caused by torrential rains, destroys the archaeological remains. However, an unusual type of archaeological site in the region, formed by societies that built stilt houses in the middle of rivers and lakes, is very promising in terms of understanding how indigenous peoples lived in the pre-colonial period. This is because the material remains of these people were submerged in the beds of rivers and lakes and the aquatic peat, without oxygen, sealed this material as if it were a sarcophagus waiting for someone to discover it one day. Therefore, the materials are relatively well preserved. Our research, therefore, goes in this direction. Previous pioneer geophysical investigation funded by FAPESP (award number 2020/15560-5) applied Ground Penetrating Radar (GPR) to successfully locate stilts in underwater archeological sites in the maranhense wetland. The results were very promising and, therefore, served as a stimulation for continuing research. The current proposal is a continuation of this research, where the difference is related to the integration of GPR, Side Scan Sonar (SSS), Ecobathymetry, and Drone imaging. The main objective of this new research project consists of mapping in detail, through the densification of geophysical profiles, two underwater archaeological sites: Formoso and Coqueiro, which will be mapped using the geophysical methods GPR, SSS, Ecobathymetry, and Drone imaging. The GPR has demonstrated good results in guiding archaeologists to determine the best places to carry out excavations or dives. SSS is used to map the beds of rivers and lakes, and it will be able to identify patterns with anthropic structures. Ecobathymetry will be used to map the topography of the beds of rivers and lakes, and it will complement the GPR and SSS results. This research will contribute to locating underwater stilts and delimiting the extent and geometry of the pre-colonial villages, which was not possible to determine previously with GPR alone. Moreover, the results may contribute to finding archaeological artifacts and locating anthropic materials such as canoes, and even funeral urns, which is a harder objective. The integrated results of GPR, SSS, Ecobathymetry, and Drone will guide the search for archaeological materials, contributing to the preservation of archaeological heritage in the State of Maranhão, eastern Amazon region, Northeast Brazil. (AU)