Brazilian Caves

ABSTRACT

Toca da Boa Vista, the longest known cave in the Southern Hemisphere with 84 km of mapped passages, is one of the most important speleological and palaeontological sites in Brazil. Together with the neighbouring caves of Toca da Barriguda, Toca do Calor de Cima, Toca do Pitú and Toca do Morrinho, they represent a geological site of global interest. Morphological, hydrochemical and isotopic evidence suggest that cave genesis was due to oxidation of sulphide within the Una Group dolomite bedrock. Toca da Boa Vista is the longest cave in the world known to have been generated by such a process. Radiometric dating of secondary carbonates and fossil bones have allowed the reconstruction of Quaternary palaeoclimate events in the area and suggest periods of increased precipitation at the last glacial maximum. Among the many fossil remains found in these caves, there are remarkably complete and well preserved skeletons of many extinct species, allowing a significant advance on the knowledge about these fossil groups. The remote and rural location of the caves reduces risk from anthropogenic activity, but some formal protection should be granted to the site in recognition to its exceptional technical and scientific value.

INTRODUCTION

Toca da Boa Vista is at present (1999) the longest known cave in the Southern Hemisphere and 16th longest in the world, with 84 km of mapped passages. Together with the neighbouring Toca da Barriguda, presently the second longest cave in Brazil at 19.5 km and other related caves, Toca do Calor de Cima, Toca do Pitu and Toca do Morrinho, it comprises a site of major scientific importance. With the exception of Toca do Morrinho, these caves probably represent a unified cave system now bisected by collapses and later sedimentation. The hypogene sulphuric acid speleogenetic processes responsible for the development of these caves are relatively uncommon, and result in a distinctive morphology. Secondary carbonate precipitates (speleothems) within the caves have been dated and provide an important record of late Quaternary climatic change which suggest that more humid conditions were previously present in this now semi-arid area. This is complemented by a rich and remarkably well preserved fossil fauna.

LOCATION

The Toca da Boa Vista is located in northern Bahia State, within the limits of the municipality of Campo Formoso (Fig. 1). Toca da Boa Vista (main entrance 10º09′45″S, 40º51′35″W) lies 11 km east from the small village of Laje dos Negros, the entrance being adjacent to the road that connects Laje dos Negros and Abreus. Toca da Barriguda (10º08′26″S, 40º51′08″W) and Toca do Calor de Cima (10º08′26″S, 40º50′55″W) are 2 km further to the east along the same road. Toca do Pitu (10º07′44″S, 40º50′18″W) is located in the same area, closer to the village of Barriguda. Toca do Morrinho (10º12′32″S, 40º55′05″W) lies a few kilometres south of Laje dos Negros, near the village of Casa Nova. The cave entrances are not easily located amidst the featureless local landscape, and help from locals is highly recommended. Visits to the site should be conducted with the help of experienced cavers, due to the complexity, dry atmosphere and lack of water in the caves.

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