Ruiniform relief in sandstones: the examples of Vila Velha, Carboniferous of the Paraná Basin, Southern Brazil

Vila Velha is a remarkable group of natural sculptures in Palaeozoic sandstones of the Parana. Basin in Southern Brazil. The sculptures, which resemble the ruins of an old stone city, have resulted from the combination of Cenozoic weathering and erosive processes with the existing attributes of the sedimentary rocks (texture, cementing oxides, sedimentary and brittle structures). A particular geomorphologic setting with eroded inselbergs, and a differential iron and manganese cementation during lateritization phases are other factors controlling that exceptional landscape, the ruiniform relief. Despite being a natural heritage of inestimable value, Vila Velha is threatened by large-scale tourism, with severe risks for its conservation.