Vila Velha (Old Village) is the denomination of an notable group of natural sculptures of ruiniform aspect, developed in Carboniferous sandstones of the Paraná Basin. Situated approximately 80 Km WNW from Curitiba and 20 Km ESE of Ponta Grossa, for a long time Vila Velha has been pointed as a well-known touristic attraction.
    The singularity of the sculptures enforced the creation of the Vila Velha State Park by the State Law # 1292, of October 12, 1953. The park, 3,122.11 ha large, is much older than the Brazilian environmental legislation and this determined the divergence of aims of the three institutions that are responsible for its administration.
    The sandstone sculptures have received a variety of names suggested by the imagination of the visiting public: Cyclops city, camel, sphinx, ship's prow, bottle, turtle, wine-glass (the symbol of Vila Velha) and others. The heights range from a few meters to about 30 meters. The erosive forms are distributed on an area of about 10 ha, that is a notable outcrop of periglacial sandstones of non-consensual genesis, where the sculptures reflect the interrelation of various factors: lithology of the sedimentary rock, tectonic and non-tectonic structures, weathering and erosion processes, beyond others.

    The first white men who saw the Campos Gerais region were the explorers from São Paulo (named bandeirantes paulistas) of the XVI century: Aleixo Garcia in 1526, Pedro Lobo and Francisco Chaves in 1531. It is also described that the Spanish Dom Álvar Nuñez Cabeza de Vaca, Governor of Paraguay in 1541, also came to this region.
    In the XVII century, expeditions from São Paulo visited the region looking for gold and precious stones, as well to capture Indians. As told by Ferreira & Kersten (1990), this was the time of the first references to Vila Velha, because it was a natural mark for the travelers going south.
    For the tribal populations, ancient inhabitants of the region, the ruiniform sculptures of Vila Velha were explained by a variety of legends, some of them still told nowadays. The most known is the legend of ITACUERETABA, the "extinct city of stone".
    In 1876 the First Geological Commission of the Brazilian Empire visited the region of the Campos Gerais. At that time, Luthero Wagoner described the Carboniferous sandstones and Devonian fossils on underlying layers, these later named "Ponta Grossa Formation" (Formação Ponta Grossa) (Lange, 1954).
    In 1880, the Emperor of Brazil, D. Pedro II, visited the region to know the project of the Russian-German colonization, started in 1878. He stayed in the farmhouse of Domingos Pereira Pinto, the Baron of Guaraúna, in whose lands the strange rock formation was placed.

    Vila Velha is placed near the eastern border of the Paraná Basin, about 10 km westward the erosive contact of the Paleozoic sedimentary units over the Proterozoic basement (Figure 3).
    The rocks of this basement (Açungui Group of the Brazilian Cycle and post-tectonic granitic stocks) form the Primeiro Planalto Paranaense (the First Paraná Plateau), which landscape is leveled between 800 and 900 m above sea level. The Paleozoic sedimentary units of the Paraná Basin form the Segundo Planalto Paranaense (Second Paraná Plateau), which is leveled by a planation surface gently inclined towards the west, with maximum altitudes in the east at about 1,100 m. The limit between the First and Second Paraná Plateau is called the "Devonian" Escarpment, that is locally named Serra de São Luís do Purunã, a mainly erosive cliff up to 200 m high.
    In this sector of the Paraná Basin occurs the Furnas Formation (basal), that grades to the top to the Ponta Grossa Formation. The Itararé Group lies above these two units, showing clear erosive contacts.
    Vila Velha is formed by reddish sandstones of the basal portion of the Itararé Group, that also has conglomerates, diamictites, rhythmites, argillites and shales (Maack, 1946a).

    Maack (1946b), named "Vila Velha" the reddish sandstones that form the natural sculptures . Recent researchers are not unanimous about the origin, stratigraphic setting and the age of these sandstones and underlying deposits of the Itararé Group.
    França et al. (1996)  considered the Vila Velha sandstone as subaqueous lobes formed by dense gravitational flows coming from the base of coastal glaciers. Evidence of hydrodynamic flows indicates shallow water environment, with the shifting of gravitational flows and hydrodynamic processes. The sedimentary filling of the upstream subaqueous channel of the lobes of the Vila Velha Sandstone is represented by the Lapa Sandstone, which shows a linear morphology to the south of Vila Velha. The fossil content of layers included in the Lapa Sandstone permitted to date it to the Westphalian age (Upper Carboniferous). The Lagoa Azul Formation, also with an Westphalian age, is the basal unit of the ltararé Group, and comprises the deposits underlying the Vila Velha and Lapa sandstones (Milani et al., 1994) (Figure 4).

    The Vila Velha Sandstone shows a few examples of clear sedimentary structures. Incipient bedding and massive-like rocks (Maack, 1946a) and the presence of dispersed argillaceous intraclasts suggest resedimentation by gravitational flows. Ripple marks and low-dipping cross-stratification indicate the influence of hydrodynamic processes (França et al., 1996), maybe in a marine environment influenced by the tides (Canuto et al., 1997).
    The Vila Velha Sandstone is up to 50 m thick (Maack, 1946a). It overlies conglomeratic sandstones and sandy-clayey rhythmites of the Itararé Group with a concordant contact. The sandstone is a reddish quartzous sedimentary rock with variable sorting. Grain size varies from fine to coarse sand, with basal conglomerate levels. The sandstone minerals are quartz, feldspars (partly weathered to kaolin), muscovite, chlorite and garnet. (Maack, 1946a) also described the role of a thin film of iron and manganese oxides in the shape of many of the Vila Velha natural sculptures. This cementing process combined with differential erosion cause the formation of common mounds with wide tops and concave eroded basis (Maack,1946a) (Figure 5).
    Iron and manganese oxides cementation is a marked feature of the Vila Velha Sandstone, being the main cause of the colors and shapes that make up the local scenic heritage. The oxides occur as the cement that joins the quartz grains and also as veins a few centimeters thick that fill vertical and horizontal rock fractures. Cementing is clearly a secondary process, and sometimes forms pseudostratification crossing the sedimentary structure.
    Petrography analysis of samples from different levels of the natural sculptures revealed that the Vila Velha Sandstone is formed by quartz grains, with rare polycrystalline (quartzite) grains and lithic fragments of argillaceous layers, that can generate pseudomatrix (Melo & Coimbra,1996). The minerals described by Maack (1946a), such as feldspars, muscovite, chlorite and garnet should occur only in the layers below the most typical sandstones of Vila Velha.

    The grain size of the sandstones varies from fine to coarse sand, with a predomination of medium sand. Sorting is moderate to poor, and the grains are sub-rounded to rounded and occasionally sub-angular. The framework is closed, and the quartz grains show concave-convex to sutured contacts. Sometimes there is a secondary growth with euhedral development in secondary pores (Melo & Coimbra, 1996).
    Adding to the ferruginous cementing, the Vila Velha Sandstone also presents a precipitation of manganese oxide, that fills the fractures of the NE-SW and E-W systems. It forms continuous metallic veins a few centimeters thick and unequal cementing of the surrounding sandstones, as botryoidal fringes about 1 cm thick (Melo et al., 1999).

    The Vila Velha plateau is a "ruined inselberg" (AB'SÁBER 1977), that is sustained by very eroded sandstones. This contrasts with other nearby sandstone inselbergs, less destroyed by the erosion. This difference indicates that the Vila Velha plateau is in a more advanced erosion stage than the neighbouring inselbergs, giving rise to an exception landscape, marked by "the extravagance of its topographic forms, called ruiniform relief" (Ab' Sáber, op. cit., p.3).
    The top of the plateau is at 1,012 m above sea level, about the same elevation of the top-surface of the Second Paraná Plateau. The main rivers of the region (Tibagi, Guabiroba) have their riverbeds at about 785 m above sea level.
    The natural sandstone sculptures are 10 to 30 m high, corresponding to the thickness of the reddish sandstones with ferruginous cementing, that are harder and tend to support plateaux of the landscape. The height of the sculptures can be lower (a few meters), when the erosive processes have isolated them from the rockwalls and lowered their original height.
    The forms of the sculptures remember towers, sand-clocks, walls, with different ornamentations that reflect the characteristics of the rocks, the fractures and the erosive processes (Figures 5 and 6).
    The age of the eroded figures is interpreted by geomorphologic correlation. Vila Velha is placed in the Second Paraná Plateau, that is a southward extension of the Depressão Periférica Paulista. These two geomorphologic provinces are levelled by a Neogene planation surface (Soares & Landim, 1976; Melo et al. 1998). Besides, an important phase of lateritization with associated ferriferous cementing is recognised in Southeastern and Southern Brazil, in the limit Pliocene-Pleistocene (QUEIROZ NETO 1974, PENTEADO 1976, MELO et al. 1978), though the erosion of the ruiniform sculptures is post-Neogene.

    The main erosive agents in Vila Velha are rainwater, organisms (plants, animals and lichens) and the insolation.
    Rainwater that flows overland causes mechanical erosion, dissolution and reprecipitation. The mechanical erosion with associated dissolution of the cement can form lapiés-like features in the top of the plateau (Figure 6). In the cliffs they can form vertical hollows that evolve to isolated tower-like features, with enlarged tops.
    As the rainwater drains the rockwalls they also promote the excavation of superficial holes, in a process named "alveolar erosion" (Fortes, 1996). It results from the combined action of mechanical erosion and dissolution of some components (Figure 7). Otherwise, mainly in the northern rockwalls that are more exposed to the sunlight, surface waters reprecipitate a thin coat of iron oxide, which protects the sandstone from erosion. When rich in organic acids from vegetation decomposition, the superficial waters, more corrosive, can dig long and narrow furrows on the surface of the plateau.
    The rainwater that penetrate the rock massif through the fractures and pores can also give rise to strange excavation features, named "anastomosing tunnels" (Fortes, 1996). Usually such features show apertures of a few centimeters closely controlled by the horizontal fractures. Corrosion cones present in the anastomosing tunnels resemble dissolution and precipitation features (Figure 7), but in this case they must be regarded as a result of mainly mechanical erosion.

    Organic activity (tree roots, lichens, ferns, orchids, mosses, termites, swallows and "blackbirds") is co-responsible for the processes of degradation of the rocks. Lichens are abundant on the damp walls of the sculptures, which occur mainly where there is no direct sunlight. This contributes to create favorable conditions for the erosive processes, as in the formation of concave surfaces in the base of the sculptures, and in the deepening of fractures, alveolus and tunnels.
    The sun heating on the surface of the sandstone creates cracks from the phenomenon of constant expansion and contraction. This originates many of the fractures on the plateau and on the walls of its northern face. When the sandstones are uniform (massif-like) the cracks tend to form regular hexagons, which are the shapes that require less energy for rupture (Figure 8). The action of rainwater and organisms then opens and deepens the superficial fractures initiated by insolation.

    Recently, besides the natural factors that promote the erosion of the sandstone, large numbers of tourists have resulted in deep erosion of the paths, while vandals' inscriptions are destroying the rockwalls.
    There was no evidence found that eolian processes added in the elaboration of the natural sculptures in Vila Velha, but this has been told by some authors (v.g. Soares,1975; Ab'Saber, 1977). The concave bases of some of the forms are attributed to differential erosion of less resistant layers, because of different textures and cementing by iron oxide, what control water percolation and lichens growth.

    Vila Velha is not only a notable geologic/geomorphologic monument, but also an important conservation area for the ecosystems of the Campos Gerais region. The State Park comprises preserved areas of Araucaria (Paraná pine tree) woods, open fields and swampy depressions. There are at least 27 species of endemic vegetation in these ecosystems (Hatschbach & Moreira Filho,1972).
    These environments are inhabited by a number of animals menaced of extinction (such as the guará wolf - Chrysocyon brachyurus), which belong to the Guarani Fauna Province (Mello Leitão,1947).
    The following arrangements must be envisaged for improving the preservation and use of the park:

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