Rio Poti canyon

A scenario of the planetary geological history of the Parnaíba Basin

Abstract

The Piauí-Ceará state boundary is marked by mountain ranges, cut by a geological fault shaping impressive scenic landscapes in an area of ​​the Caatinga biome. The Poti River, captured by faults, generates exuberant geological forms, exposing and sculpting rocks from the Canindé Group, predominantly Cabeças Formation, and from the Tianguá and Ipu formations of the Serra Grande Group. With a source in the Ceará mountains, it enters Piauí according to a geological fault that changes its course at the height of the municipality of Buriti dos Montes. With a length of 538 km, it was used as a migratory corridor between the plains of Piauí and Maranhão and the semi-arid region of Ceará, Pernambuco and Bahia, as evidenced by rock carvings by perforating rocks on its bed, constituting one of the most important complex of rock engravings in the Americas. The canyon starts at Serra dos Cariris, municipality of Quiterianópolis-CE, crosses the front of Serra da Ibiapaba and flows into the Parnaíba River, in Teresina. More resistant sedimentary lithologies conditioned the deepening of its thalweg, generating a 360 m high canyon in the contact area between the crystalline and sedimentary rocks and 60 m in the latter. The strong structural control of the drainage and the canyon reflects the influence of the Transbrasiliano and Picos-Santa Inês lineaments.