The Alfredo Jahn Cave is located four kilometers to the west of the town of Birongo, Miranda State, in the eastern sector of the Serranía Littoral (coastal mountains) of the Cordillera de la Costa (coastal range). This natural monument is found at an elevation ranging from 60 to 300 m above sea level (ASL). The semi-steep topography is formed by calcareous hills. The climate is hot and rainy with an average annual precipitation of 1,970 mm. The interior temperature of the cave oscillates between 22°C and 26°C (71-79°F) (MARNR 1992).
See Map (Source Tapiquén et al. 2004)
The Alfredo Jahn Cave is the largest cave in the central region of Venezuela, and the sixth largest in the country, with a network of horizontal passages measuring 4,292 meters, a depth of 67 meters, and 15 entrances known as “bocas” or mouths. The cave can be divided into six sectors (rough translations are given in parentheses): Galería de la Quebrada (Creek Passage), the Arrastraderro (the Crawl Way), Galería del Río (River Passage), Galería Codazzi (Codazzi Passage), Salón del Chaguaramo (Palm Chamber) or Salón de la Lluvia (Rain Chamber), Galería del Sifón del Diablo (Devil’s Siphon Passage), and Galería Henri Pittier (Henri Pittier Passage) (SVE 1973).
The Galería del Rio (River Passage) is the principal route for visitors of the cave
This geologic formation consists of calcite and calcite-dolomite marbles (Uzcátegui 1996). The perennial Cambural Creek passes through the interior of the cave, draining a sub-basin whose mineralogy consists of schists from the La Mercedes and Las Brisas formations (Urbani 1974). The cave has formed through the erosive and corrosive actions of water on the calcite and dolomite rock. In the dry season, the creek infiltrates the cave at the level of the Salón del Chaguaramo (or Salón de la Lluvia), along a 200 meter length of calcite block, forming a channel in the cave’s interior until it emerges 600 meters farther down, at Boca 1 of the cave. The waterway then continues above ground until it meets Casupal Creek. In the rainy season, infiltration through the sediments of the channel’s bed is not sufficient to capture all of the water flow. The excess flows through a channel above the cave, entering through Boca 8, and then continuing through the cave until it emerges at Boca 1 (Forti et al. 1999).
The Alfredo Jahn Cave is a relatively young cave, thus the processes of erosion and corrosion are more important in shaping the interior of the cave than the deposition of carbonates (in formations known as dripstones). The thickness of rock above the cave passages is about 30 meters. Due to the high hydrologic activity, many calcite formations, especially stalactites, decorate the cave (Forti et al. 1999). These formations exhibit their best development in the Salón de la Lluvia, where a striking column known as “El Chaguaramo” is found. This column formed through the union of a stalactite and a stalagmite and bears a striking resemblance to the palm tree of the same name.
The column known as “El Chaguaramo”
With regard to the geology of the cave, the Las Mercedes formation, dating back to the Mesozoic Era (Jurassic-Cretaceous Periods), emerges in the monument. It is a metamorphic formation principally composed of calcite schists, with zones of graphite and locally micaceous areas (PDV 1997). Calcite marbles predominate in the Birongo region (Urbani 1996). In fact, calcite is the most common mineral in caves, taking on spectacular shapes as stalactites, stalagmites, and columns.
Besides calcite, a variety of other minerals also exist in the cave. Halite, for example forms a thin layer covering the bottom walls of the Salón del Chaguaramo. Amorphous oxide-hydroxides of iron and manganese form thin, red to black layers covering the rock on the bottom of the creek that traverses this chamber. Ammonium-jarosite is also present as clear blue points, while koktaite mixed with hydroxyl-apatite and halite appears as grey points on the marble walls. Mangano-berzelite is seen as a thin layer of pink to brownish-pink covering the limestone beds of the active creeks (Urbani 1996). Ammonium-jarosite, koktaite, and mangano-berzelite have not been reported in any other cave in the world (Forti et al. 1999).