Cavernas do Peruaçu FederalBrazil - Environmental Protection Area (APA) / Veredas Do Peruaçu State Park

Area:APA: 150.000 hectares. Including: State Park: 30.702 hectares Climate: Sub-humid to semi-arid Tropical7 with 6 month dry season temp: 24° C year average. · pluv: 850 mm total /year Altitude: +1- 455- 834 m. Geomorphology and hydrology: Pernaçu river is one of the few permanent affluents of the Sao Francisco river on its course from sub-humid tropical Cerrado's where it started, towerds the semi-arid Caatinga's of north-eastern Brazil. Its watershed is situated on poorly drained, sedimentary arenite tops of high plateau or " Chapadao". On its course northwards, acid waters and alluvial sands and gravel drilled a 20 Km tunnel in the limestone of an extensive calcareous Massif (Bambai Group). During millions of years, erosion from the river excavated the original tunnel, forming a huge gallery. Simultaneously, rain waters, infiltrating through cracks on top of the massif, corroded the upper part of the tunnel, that eventually collapsed in large sections. Large diaclasis, aven's, caves and secondary galleries appeared. The Peruaçu flows now through a deep canyon, boarded by high limestone cliffs, opened by caves, holes and secondary galleries. It is crossed by impressive limestone 'bridges' and in some stretches still flows underground, through monumental caves like the Olhos d'Agua cave 6 Km long and Janelso cave, 3.020 m long, 400 m wide and 200 m high, one of worid's largest underground " room" . Exceptional stalactite may be worid's larnest (28 m high). The whole 20 Km2 massif, sculptured in"ruins", pinnacles, caves, galleries, some 400 m wide, 70 m deep aven' s and dolina's, is far from being totally explored.