Geological and Paleontological Sites of Brazil - 029
Mário Sérgio de Melo 1
1 Departamento de
© Melo,M.S.; Bosetti,E.P.; Godoy,L.C.; Pilatti,F. 1999. Vila Velha. In: Schobbenhaus,C.; Campos,D.A.; Queiroz,E.T.; Winge,M.; Berbert-Born,M. (Edit.) Sítios Geológicos e Paleontológicos do Brasil. Published 18/11/1999 on Internet at the address http://www.unb.br/ig/sigep/sitio029/sitio029.htm [Actually http://sigep.cprm.gov.br/sitio029/sitio029.htm ]
(The above bibliographic reference of author copy rights is required for any use of this article in any media, being forbidden the use for any commercial purpose)
The natural sandstone sculptures of Vila Velha are an impressing
example of ruiniform relief, combining the association of erosive processes with
pre-existing attributes of the rocks. They are protected by a State Park, which has
received about 200,000 visitors/year, what causes some risks for the preservation of such
a rich natural environment.
The Vila Velha Sandstone is part of the base of the ltararé Group (Upper Carboniferous to Lower Permian of the Paraná Basin, Southern Brazil). It has a reddish coloration due to the presence of ferriferous cement. Grain size is medium to fine sand, with dispersed argillaceous intraclasts in an incipient planar to cross-bedded stratification.
The natural sculptures have an elevation of 10 to 30 m above surrounding terrain. Their tops show cracks and fracture polygons, while the walls show saliences, hollows, small anastomosing tunnels, alveolar erosive excavations, basal concave surfaces and fractures filled with iron and manganese oxides. Other structures are the sedimentary stratification, vertical and horizontal fractures and pseudo stratification formed by the cementing.
Vila Velha is a natural site with great environmental value. The large outcrop is a singular exposure of the sedimentary attributes and erosive features of the Vila Velha Sandstone. The area is appropriate for environmental study activities, not only because of the ruiniform relief but also the presence of natural preserved ecosystems, with endemic endangered species. Nevertheless, the integrity of this environment is threatened by the massive exploration of the touristic aspect, which has failed to attribute to the park its role of a preservation area.
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.
Vila Velha is situated in the Municipality of Ponta Grossa, in the Campos Gerais region, State of Paraná, Southern Brazil (Figure 1), on the geographical coordinates 25o14'09''S and 50o00'17''W. The main access is the BR-376, and important road junction that connects the shores, Curitiba (the State capital) and the North of the Paraná State.
Figure 1. Location of Vila Velha Site
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.
DESCRIPTION OF THE AREA
Vila Velha is sculptured on Carboniferous sandstones of the Paraná Basin, that is a vast intracratonic depression of South America, about 1,400,000 km2 in area, extending over Brazil (1,100,000 km2), Argentina (100,000 km2), Paraguay (100,000 km2) and Uruguay (100,000 km2) (Zalán et al., 1991; Milani et al. s.d.) (Figure 2).
The Paraná Basin Sedimentary Filling
The basin is filled by up to 8,000 m of sedimentary and volcanic rocks, the later to a maximum depth of 1,700 m (Zalán et al., 1991). The older sediments (Rio Ivaí Group) are from the Late Ordovician to Early Silurian (Assine et al., 1994; Milani et al. 1994), and the newer (Bauru and Caiuá Groups) are from the Early Cretaceous (Fernandes & Coimbra, 1994).
Figure 2 . Paraná Basin and the Vila Velha Site. V: Vila Velha; CR: Curitiba; RJ: Rio do Janeiro; BR: Brasília; BA: Buenos Aires.
Geology of Vila Velha
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).
Figure 3. Geologic map of Paraná State between Ponta Grossa and Lapa (MINEROPAR, 1989). 1: Proterozoic basement; 2: Furnas Formation (D); 3: Ponta Grossa Formation; 4: Itararé Group (C-P); 5: Rio Bonito Formation (P); diabase dykes (Mesozoic); 7: major faults; 8: Vila Velha; 9: urban areas.
Stratigraphy and Paleoenvironments
(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
Figure 4. Local Stratigraphyc chart (modified from Milani et al. s.d.)
Canuto et al. (1997) also recognized a genetic relation among the Lapa Sandstone southward, and the Vila Velha Sandstone northward, this latter at least in part underlying the former. In this alternative model the Lapa Sandstone is seen as the filling (up to 80m thick) of a subglacial tunnel-valley carved on older sedimentary rocks of the Itararé Group, and reaching the Furnas Formation (Devonian) towards the north. The Lapa Sandstone is included in the Itararé Group, but with an uncertain age. Lithosome geometry, low dipping cross-stratification and vertical and horizontal burrows suggest a tidal influenced shallow marine setting for the Vila Velha Sandstone.
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
et al., 1996), maybe in a marine environment influenced by the
(Canuto et al.,
Figure 5. Sandstone sculpture with enlarged top showing horizontal non-tectonic fractures.
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,
The Paraná Basin shows three main trends of tectonic structures (Zalán et al., 1991):
a) NE-SW parallel to the structures of the Proterozoic basement;
b) NW-SE, related to the Gondwana break-up;
c) E-W parallel to oceanic fracture zones.
These three trends of structures appear in Vila Velha, mainly as long
fractures with no or negligible displacement.
Other two sets of fractures appear in the sandstones (Melo & Coimbra, 1996):
d) subvertical fractures of non-tectonic origin, exhibiting a concentric setting parallel to the borders of the rocky plateau;
e) subhorizontal structures partially controlled by bedding and formed by relaxing stresses due to load removal.
Forms of the Landscape
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).
Figure 6. Lapiés-like features in the top of the sandstone plateau.
Erosive Processes and Features
The main erosive agents in Vila Velha are rainwater, organisms (plants,
animals and lichens) and the insolation.
Figure 7. Corrosion cones formed by anastomosed tunnels in horizontal fractures and alveolus due to superficial 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.
Figure 8. Polygonal fractures attributed to insolation associated to linear subvertical fractures.
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.
Figure 10. The
Wine-glass, sandstone natural sculpture symbol of Vila Velha.
(Photo: Mario Sergio de Melo)
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).
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