Cueva Charles Brewer

Largest quartzite cave in the world

Text: Branislav Šmída, Marek Audy, and Federico Mayoral

Photos: Marek Audy.

In the southeastern region of Venezuela, there are about 100 table mountains called tepuis, which are
commonly known as “The Lost World” (Doyle, 1912). These mesa-shaped mountains appears in such regions like towers rising from the surrounding jungle, isolated by vertical cliffs several hundred meters high, and from which long waterfalls like Salto Angel drop more than 979 meters (the highest waterfall in the world). From the geological point of view, these mountains are Proterozoic massifs (about two thousand million years old), which have been formed from subhorizontal quartzite sand deposits.
 

These tepuis are habitat for a great variety of endemic flora and fauna species, and just recently karst structures with numerous subterranean systems have been discovered. Until recently, the caves found in these sedimentary rocks were considered denuded relicts, as Cueva Autana (653 m, Brewer-Carías, 1976a), or as mega-collapses, for example wellknown Sima Mayor (-314 meters, Brewer-Carías, 1976b) on the plateau Sarisasariñama, the abyss Sima Aonda (-383 meters, Galán, 1983) or Sima Auyán-tepui Noroeste (2.950 meters / -370 meters, Bernabei et al., 1994), but in most of cases, only long crevasses with little alterations. During the year 2002, this panorama changed after the first classic great cavern system (Cueva Ojos de Cristal, 2.41 meters long) was located in Mount Roraima (Audy, Šmída, 2003; Šmída et al., 2003).

Expeditions to these mountains are very limited due to the logisticalal and access difficulties, hence, it is almost always necessary to arrange helicopter transportation.

However, in the highly broken surface of the Chimantá massif, which covers an area 1.470 km2 and is topped by some 10 individual tepuis with heights above 2,000 meters (the highest Murey-tepui with 2,698 meters), a colossal cave discovery has taken place, which complies with all the attributes of a standard cave: an underground river system, waterfalls, rock slides, and diverse speleothems. This locality is today considered the largest quartzite cave in the world, and has been baptized Cueva Charles Brewer, in honor of its discoverer Mr. Charles Brewer-Carías, the pioneer speleologist in quartzite caves, a renowned scientist, and undoubtedly the most experienced and qualified human in the Tepuy world of the Guayana Highlands.
 

Mr. Charles Brewer-Carías explored Chimantá’s surface in 1978, where he directed two multi-disciplinary natural science expeditions, and has completed more than a hundred expeditions to mountains throughout this geographical area in the following years. Flying over Chimantá in 2002 (to fix the geoposition of a crevasse of more than 250 meters high, discovered by the helicopter pilot on some of the walls of the Aprada-tepui), Brewer-Carías sighted a river coming out from a small shadow, which to him looked like the entrance to a large cave.

By the first quarter of the year 2002 Brewer-Carías had made two other reconnaissance flights to evaluate the place, and to study possible landing sites, since the only feasible way to arrive near to the cave entrance was by making very complicated and dangerous helicopter maneuvers.
 

On March 28th of 2004, a group of twelve Venezuelan scientists and nature experts were able to explore the cave for the first time. They learned that they were dealing with a really large cave that had a turbulent river, waterfalls, domes, and gigantic galleries up to 60 meters wide and some 15 to 20 meters of average height.
 

On this first expedition, they covered the first 2 km until they stopped in front of a deep lake (Lago Chayo), but they could see other galleries ahead. The participants of this unforgettable expedition were: Ch. Brewer-Carías, Ch. Brewer-Capriles, F. Mayoral, A. Tovar, L. A. Carnicero, F. Tamayo, A. Chumaceiro, E. Wallis, A. A. Chacón, C. Barrio, Prof. R. Guerrero from the Tropical Institute of Zoology of the Venezuelan Central University and Dr. F. Delascio, President of Jardín Botánico del Orinoco at Ciudad Bolívar, Venezuela; these last two were also members of the Governmental Commission for the study of the Tepuys protection.
 

Two months later, between May 28th and June 2nd of 2004, a second expedition was organized with seven members, and some first-class cavers were invited to draw the cave maps and to obtain additional photographs. The basecamp on both expeditions was set up at the cavern entrance, which is a space of approximately 100 x 120 meters. From here the team launched several exploration missions into the cave. The group also set a bivouac camp under an ample hall of 90 x 150 meters (Planetario), in order to complete the mapping of the rest of the cave. During this expedition, a detailed map of the explored sections was drawn, speleological and zoological observations were registered, and the typology of many new and strange speleothems for the science world was obtained. This second action, also led under the direction of Ch. Brewer-Carías, had the Venezuelan participants: Ch. Brewer-Capriles, F. Mayoral, L. A. Carnicero and John Brewer, accompanied by Slovak and Czech speleologists and guests B. Šmída and M. Audy.
 

The cave seems to be part a major drainage system of an extensive area of the tepui surface. During the dry season, the water volume of the river inside the cave was estimated at 200–300 l/sec. But during the torrential rains, it reaches many cubic meters/sec. During these times deep lakes reaching several hundred meters long are formed inside the cave, and the water at the entrance is dammed and hence drained through a siphon. The behavior of the water inside the cave is unpredictable due to unexpected downpours, making the cave extremely dangerous, and one must always be prepared for a possible flash flood event.
 

The cave galleries have a typical width of 40 meters and can reach up to 60 meters in places where the floor is covered with huge breakdown, some the size of buildings. The biggest space found in the cave has been Gran Galería Karen y Fanny, with a dome to 40 meters height and measuring more than 355 meters long.
 

As the walls are 70 meters apart, the volume of this area has been estimated in 400,000 m3. (The second largest space is 320,000 m3 at the Gran Galería de los Guácharos, near the entrance.) The rest of the great spaces inside the cave consists of canyons where the smallest profiles reaches 15 x 20 meters. These passages are very dynamic in terms of water movement and is where beautiful waterfalls and rapids are found. Due to this fact, these are the most hazardous segments of the cave.
One of the most interesting features of the main gallery is its straightness, showing few bends or parallel galleries.
 

The general disposition of the cave is that of being parallel to the top of the mountain and running 150 to 200 meters below the surface. Inside the cave, there are some red mud terraces, beatiful sandy beaches with ripple-marked sand, small marmits filled with quartz-polished lentils, some clean walls and others ridged with lateral ledges, columns, and rock bridges. There are also an amazing diversity of speleothems, probably of organic origin and actually alive (because of the presence of some bacteria? or fungi?): one with opal core and doll shaped (Muñecos), one ballshaped (Champignons), and others with a large dendritic shape, growing from the floor and walls, absolutely independent of stalactites.
 

The cave-fauna is represented by several troglophile-like swifts (Streptoprocne zonaris), the very strange and interesting guácharo-birds (Steatornis caripensis), a new species of huge grasshoppers, 10–12 cm long, which dives into the water when disturbed (Hydrolutos sp.), and at least two new scorpion species living deep inside and near the mouth of the cave.
 

The Cueva Charles Brewer has been surveyed and mapped up to 4.482 meters long, with a depth of 110 meters (Šmída et al., 2004), and considering the size of its galleries, its total volume is unmatched by any other quartzite cave of the planet.
 

Few of the world’s carbonate caves, even the most extensvie, likely achieve such volumes.