Oxford University Cave Club

Caving Organisation and Discoveries

The provision of caving equipment for a speleological expedition must naturally be a matter for careful study and organisation. A compromise will in general have to be made between the maximum possible amount of equipment which could conceivably be required in the field and the available finance. The limited budget of the 1961 expedition and the extreme generosity of firms finally combined to produce enough materials to make 1500 feet of electron ladder, nylon ropes for lifelining, wire belays; and, for each member of the expedition, overalls, helmets, boots, lamps and batteries, carbide lamps and carbide and waterproof electric torches. Plane tables and other surveying equipment were kindly loaned by the Oxford University Department of Surveying and Geodesy, and an Autoset Level by Hilger and Watts Ltd. About ten pounds weight each of Fluorescein and Rhodamine B were obtained for water tracing. The chemical and geophysical equipment is described elsewhere in this report. Besides the above-mentioned and more obvious items there are many ancillary items of equipment for which the caving organiser must make provision. Among these are a generator for the recharging of batteries, caving rations, first aid equipment, and pens, pencils, paper, inks, drawing board and tee square for the plotting of surveys.

The exploration of caves and potholes in the area was generally undertaken by groups of four or five members of the expedition, and it was ensured that one or more members of the expedition were always in the vicinity of the refuge to guard the equipment and keep a check on the weather conditions. These members would generally be on cooking duty for the day, and frequently helped with surface life-lining at a pre-arranged time, also bringing hot soup or beverages for the explorers to enjoy. Surface survey and geomorphological work was generally undertaken by mobile parties of two, who often camped overnight in the mountains.

Cave survey was undertaken to Cave Research Group Grade 4 if possible, but the remoteness of some caves sometimes led to surveys of only Grade 2 standard. Surface surveys and water tracing were carried out to correlate the surface and underground features.

Experiments were made with a beam made of Dexion steel angle in the rigging of ladders for the descent of open shafts.

Three large cave systems were explored, Pozo Palomeru (P1), Cueva del Viento (C15), and Cueva de Orandi (P14).

Pozo Palomeru (P1) is entered by a shaft of 43 metres which gives access to about a mile of passages, generally of vadose characteristics, and appears to be the result of the joining of at least three separate stream passages; the Candy Cavern series, ending in the sump near the entrance shaft, the main Collander Cavern - Blue Pool Passage series, and the Far Series (see Figure 2 and Figure 3). The often abrupt changes in level of the main passage seem to indicate a complex history. At the time of exploration only a few pools were seen in the main passage, but water marks and flood debris indicated that a powerful stream must flow through this system in winter conditions, and when the snow melts on the surface. The system has several instances of high-level oxbow passages, and at least two natural bridges consisting of flakes of rock across the passage (Plate VII). An interesting feature was a swirl bank of gravel in the chamber at the foot of the 6 metre pitch which opens from the entrance pitch. The stream which formed this must sink in the eastern corner of the chamber and may be connected with the sump to the southwest of the entrance pitch. Among the gravel were found several teeth of large herbivores (probably cows) and a few canine teeth (probably wolf).

Cueva del Viento (C15) was so named from the strong air current in the constricted entrance crawl. This cave consists of a series of rift chambers and stream passages leading to a large chamber with roof series and two main radiating passages (see Figure 4). The major of these is a rift passage with fine flowstone, stalagmites and rimstone pools, and is obviously an overflow passage for the large stream which rises from a sump and shortly sinks into an impassable rift at the inner limit of exploration. The way on here would appear to be by diving the sump or blasting the small tube above. It is possible that the active stream nearer the entrance to the cave might be joined by descending the rift in the further reaches of the rift passage. Midway along the passage there is evidence of phreatic features, a low chamber connecting with quite a complex network of passages, but the main features of the rift passage indicate vadose formation. The second passage radiating from the main chamber, Muddy Passage, has two entrance branches, both scalloped and indicating flow towards the main chamber. At the junction of these two branches are a boulder-filled chamber and another muddy chamber, on different levels and connected by a scalloped passage which opens onto a ledge in the wall of the first chamber. A crawl leads beneath the second chamber to a meandering rift connecting with a north-south passage. To the north the passage slopes upwards with a floor of calcite concretions covered with mud, and to the south via an interesting 'double passage' to a more constricted section with formations and a low, loose crawl into a boulder chamber, where an air current issues from a narrow rift. The 'double passage' consists of a rounded tube-like passage running immediately above a more angular and roomy passage. The air current is towards the main chamber in all parts of Muddy Passage; the predominant angle of dip is 40 to the east, a similar value to that found in the northwestern part of the above-mentioned rift passage. In the southeastern part of the rift passage, however, the dip is to the west, and this change of dip over a comparatively short distance has yet to be explained. Cueva del Viento possibly offers more opportunities for further exploration than any other cave visited.

Cueva de Orandi (P14) is the source of the water emerging at the Shrine of Our Lady of Covadonga. The entrance is a large arch in the cliff wall of the high-level valley of Collado de Orandi, and the resurgence is some 200 metres lower down the mountainside. The expedition explored the pothole to a depth of 75 metres, under very wet conditions. Further exploration will need an extensive amount of tackle, including a dinghy for crossing the lakes which occur at the foot of some pitches, and all tackle must be carried up a very steep mountain track, an ascent of 200 metres from the only road suitable for vehicles  (see Figure 5).

Of the potholes of moderate size, four are worthy of special mention.

P9 (Figure 6) has two large open pots connected by a natural bridge. A boulder slope leads to a meandering passage of almost constant rate of descent and of progressively restricted proportions until it is finally blocked with mud and calcite-coated gravel, the whole being analogous to a funnel, as may be seen from the projected elevation of the pothole. Two features of note are a roof boulder jam consisting of a large carrot shaped boulder and several smaller ones, and a false floor in the form of an arch of calcite-cemented pebbles. A window at the foot of the shafts leads to a small rift chamber with strong air currents.

P10, situated near the southern rim of the polje Vega de Comeya, has an entrance consisting of an enlarged joint (see Figure 7) and continues to a chamber with roof pendants and a rock pillar still joining the floor and roof in one place. Open pots descend from the clint surface above. A crawl enters a rapidly descending passage which leads to an 8 metre pot, blocked at the bottom. The general direction is towards a cave in the south wall of the Vega de Comeya, C13, and a natural arch.

P11, near P10, has very little horizontal development Some 50 metres deep, it descends rapidly towards the floor of the Vega de Comeya. The entrance passages have a roof indicating a dip of 60°, which would explain the general development of the pot along this trend. Some fine rimstone pools occur where the passage begins a more rapid descent to a vadose passage. The deepest sections show down-cutting of the streamway from a bedding plane. The way on may be possible, but will need explosives or hammering. The entrances to this pothole are three in number, two open shafts and a third which may be entered by a rapidly descending grass slope and earthy gully.

C16, Cave of the Snow, situated about 1900 metres above sea level, was so called because the main chamber, some 30 metres across, was filled to a depth of about ten metres with many years' accumulation of snow, indicated by the bands of ice which also occur. The further reaches of the cave contain a loose scree. The snow has melt depressions of generally conical shape, and the whole is lit by the light from a ten metre shaft. Entrance may also be gained by a small passage with holes in the floor (see Figure 8).

A large number of smaller caves were explored and surveyed. These varied from about 50 metres in length to only a few metres. The small caves seem to be older than the large ones, and most of their formations were in decay, soft and covered with bergmilch. Cows often use them for shelter, and the shepherds use them for storing cheese.

At high altitudes many potholes were seen, some blocked by frost-shattered rock, but others open shafts, and quite deep. Some of these have been explored by expeditions in 1962 and 1963, but many remain as an attraction for further work in the area.

The hill of La Porra de Enol behind the refugio has some interesting features. Small potholes occur near the top of the hill in clint surfaces: P2 is a series of connected rift chambers, and P3 a small vadose cave now almost blocked by formations (see Figure 9). A controversial feature is a vertical stream course, dry at the time of the expedition, and called by the natives a 'fire break'. The course begins at a pocket of sandstone near the top of the hill. Such pockets of sandstone occur along with shale to a small extent in the predominantly limestone terrain. The graded fan of gravel at the foot of the course shows that it has at some time carried a stream. This probably happens only in wet weather, when the sandstone may act as a reservoir rock (Plate I).

Another controversial feature occurs at a height of about 1950 metres above sea level: the Campo de los Pozos (see Figure 1). This is an almost circular solution hollow, the floor of which is pitted by innumerable shake holes. This hollow, dry at the time of the expedition, may at some time have held a lake which drained into the shakeholes, or may even be in a waterlogged state in very wet weather. A more likely suggestion is, however, that the hollow is full of snow in wintertime, and drains through the shakeholes when it melts every spring.

A number of blocked entrances, fissures, shakeholes, etc., were catalogued by the expedition as B1, B2 etc. and in all cases these features were so designated when not considered worthy of classification as caves. Many, however, have excellent prospects as digs.

A full catalogue of the potholes, caves and blocked entrances studied by the expedition is given in Tables 5 - 7, and these should be studied in conjunction with Figure 1. The designation P for pothole is particularly appropriate as the Spanish word Pozo has the same initial letter, as is also the case for the designation C for cave or (Spanish) cueva. The system of classification is to be continued by the 1963 Oxford-Derbyshire Expedition.

It is hoped that his description of a most fascinating area will inspire others to attempt further exploration there in the near future.

 J.D. Wilcock, Kidsgrove, July 1964.

Table 5: Record of Potholes Explored

Table 6: Record of Caves Explored

Table 7: Record of Blocked Entrances Catalogued

Several of the above appear to be promising digs. In addition the 1962 expedition reports a dig with air current just to the south of the track through the Vega del Bricial near P1. 3 metre climb down through boulder choke leads to crawl blocked with stalagmite boss. This may provide an alternative entrance to P1, the survey of which proves it to be near the surface, particularly in its further reaches (see Figure 3).

The system of classification by numerals in the Picos area given in Tables 3 - 7 is to be continued for the discoveries of the Oxford-Derbyshire Speleological Expedition to North-West Spain 1963, to be published in early 1965.

Since there is no equivalent of the British National Grid in Spain, and maps are generally much inferior to the standard available in Britain, the locations of features classified in Tables 3 - 7 are necessarily vague. An attempt has been made to describe the features in such a way that they will be recognisable to subsequent expeditions, however, and Figure 1 is intended to give the best possible guide to the positions of features classified by OUENS61.