Other caves at Roraima

(Only tour 2003)

Text: Branislav Šmída, Lukáš Vlček, Marek Audy



Cueva del Hotel Guácharo

Within the expedition we explored also other caves in surroundings of the Cueva Ojos de Cristal. They tell us more about genesis of these caves in quartzites. The greatest among them is Cueva del Hotel Guácharos which is approximately 300 m long and with an entrance right from our bivouac. The cave had been visited by somebody before us already. The prints of footsteps there witnessed. However, the visitors got themselves just to the big step with a chamber and a waterfall. The footprints didn’t lead further. Also this cave is of subhorizontal character though its slope is much greater then in the Cueva Ojos de Cristal. It is also situated in a lower level, but the huge underground space (Sala con Catarata) with parameters 15 x 10 x 30 m occurs here as the greatest one in local caves for the time being. Neither this cave was explored by us as a whole. It ends with low corridors overflown by water or with tiny creeping branches which probably may continue further. We do not exclude also its hatch connection with the Cueva Ojos de Cristal (both they are in the same depression so their development ought to be parallel). If so, the cave system with a length of probably 4 km could develop and it would mean the longest cave in quartzites at all. This is a great challenge for another expeditions. We still found in the camp surroundings Cueva de Gilberto – two big through tunnels approximately 250 m long or Cueva Asfixiadora (Smudgy Cave). However, the both are not explored very well. 



Sektor Valle con Bosque Tepuyar

Cueva con Puente -  Propast s Mostem

Another our sphere of interest was the great fissure zone being situated east of our camp. We descended to the two of them and both were overflown by a waterflow. Cueva con Puente (Cave with bridge) represents a classical quartzite fissure abyss with a length of 250 m (it ended with narrowings at both tips).
 


Grieta de Diablitos Volantes - Trhlina lietajúcich diablikov

Grieta de Diablitos Volantes (Fissure of Flying Devilkins) is deep minimally 120 m but we suppose that its further continuance ought to flow into walls as a canyon which was seen by us from beneath a rain forest. Further to the north from the zone there is a monumental doline-like deep gorge or cauldron. We neither could make only a step to its edge because of deep yardangs, an unpenetrable area of great blocks with a primeval forest vegetation. Its diameter is around 100 m. To the east of the area we found a large ponor depression with the creek’s flowage up to 100–200 l per second still after two sunny days. We were not succeeded in getting into an underground through the huge blocks in the depression periphery. We got just up to 20 m into caverns among these blocks.



Genesis of the caves

The greatest spaces of the Cueva Ojos de Cristal developed in crossings of several corridors eventually their etages. Probably also here a principle of a mixed corrosion functions although a mechanical erosion of torrent waters against walls of cave tunnels is probably plumbless. Particularly a lateral wall is eroded and it is connected with a sedimentary structure of sandstone. The fact the caves are situated so shallow under the surface and they are subhorizontal, keeping a slope of corridors accordantly with a deposition of rock beds, may be connected  with a selective option of some of its relatively non-rigid, more permeable deposition. As the rocks we observed middle-grained sandstones. Also in the Roraima’s surface we noticed a selective effect of corrosion as to its rocks. The kind of inselbergs occure here and they emerge around 20–30 m above platforms, being intensively laterally undercut. Upon them as well as upon the cave or right in its ground there can be so-called „caps“ – it means less permeable rock depositions (we would tip tiny-grained sandstones). We still do not know, if these depositions within the particular formation repeat themselves and if there could be similar subhorizontal caves developed even with more etages one above another. Also we do not know if some from among the great fissures could within their depth profile incise similar caves. These are but hypotheses. It is evident, that a part of the Roraima’s surface has a massive subterraneous drainage. We are conservative as regards the age of the caves. The objective evidences are missing. Although it is commonly known that rocks of the Roraima’s group came under the effect of disintegration from Cretaceous time already, we do not suppose the Cueva Ojos de Cristal could be so old. Neither its protostage. Its exposed position near the massif surface, which mostly come under levelling, witness it all. In any case, supposing that the chemical dissolving of siliceous sandstone lasts for a very long time, the time interval of cave widening can be very long indeed, maybe millions of years. Within the expedition we mapped familiar ponor depression El Foso too. It is not known where does the water spring out from it. Moreover, it is not clear to us in the case of the caves discovered by us. Although we localised two stronger springs (Tuná Deutá) near the Roraima’s entry ramp, we suppose that the drainage of the Cueva Ojos de Cristal surroundings and also the whole zone around south-western meseta´s edge progresses to the north or north-western direction, into the valley between Roraima and the neighbouring tepuy Kukenan. In the case, the height gradient of hydrosystems can be from 400 up to 500 m. Nothing but a further exploration can tell what is their character and if they are developed in forms of caves also deeply in the massif.


Translated by Gabriel Lešinský, Kateřina Zemánková