Reconstruction of the water transport system associated with gold mining during the colonial period in the outskirts of Guarulhos, São Paulo, Brazil

Abstract

According to several authors, during the Brazilian colonial period, the exploitation of gold was first carried out in the regions of Guarulhos, Jaraguá, Pirapora do Bom Jesus, Sorocaba and Paranaguá. The period from 1553 to 1597 can be considered the starting point of the first gold mining cycle, which lasted approximately 200 years. In Guarulhos, gold was mainly mined from alluvial, colluvial, eluvial, saprolitic deposits, and from quartz veins associated with rocks of the Serra do Itaberaba Group, which corresponds to a Mesoproterozoic metamorphosed volcano-sedimentary sequence. Ten ducts and a tunnel, located near the city of Guarulhos, constitute archaeological gold mining structures from that time. They are spatially and temporally associated with dams, mining benches, mining fronts, channels, drains, places to wash and seek gold, gravel waste piles and remnants of stone walls. Mining caused anthropogenic changes in the landscape on several scales, due to activities related to excavation of hillsides, abandonment of mining operations and enlargement of valleys. The relation of the ten ducts and the tunnel to several other archaeological gold mining structures allowed us to characterize them as part of the water transportation system associated with the gold mining activity carried out in this period in the outskirts of Guarulhos. They are closely associated with the hydrographic basins of Guavirituba, Tomé Gonçalves, Tanque Grande, and Guaraçau streams. The ducts, located in the headwaters of river basins, upstream of small drainages, were built with the objective that the water stored in dams, which was essential to downstream exploitation of gold, flew by gravity. The function of the tunnel was to supply water for the exploitation of a mainly colluvial deposit on the hillside. The results obtained in this study are part of a larger effort to retrieve, recover, preserve and disclose records of great archaeological, mining, geological, historical and cultural value within the context of the Gold Cycle Geopark of Guarulhos. These records should be useful in the difficult task of recovering the early colonial history and first Gold Cycle in Brazil, which are usually ignored by historians.