OUCC Proceedings 13 (1991)

Scientific work in the Picos de Europa

Proc. 13 Contents.

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Contents: Hydrology: Biology: Geology: Geodesy & mapping: Surface Survey


This is an outline of the hydrological work carried out by O.U.C.C. expeditions in the years '87 to '90. For a summary of previous work carried out in the area see references [1] and [4].


Two caves were explored: 1/4 to its conclusion, and 2/7. Neither cave (in the passages explored at that time) contained large streams, but dye traces were attempted in both cases. Approximately 500g of Lissamine FF was placed into the very small trickle of water present at the top of the second pitch in 1/4 and a similar quantity of Rhodamine B was added to the small stream in the shaft series of 2/7. Detectors (consisting of small bags of activated charcoal) had been placed in a number of the resurgences in the area, including Culiembro, Puente Bolin, El Hoya la Madre, and the Rio Cares at Cain and at Carmamena.

The detectors were changed prior to dye being added to the caves and again at the end of the expedition. Any adsorbed dye was eluted with ethanol/KOH solution and the samples analysed using a spectrofluorimeter. The results (Table 1) were a positive trace from 1/4 to Culiembro resurgence (Lissamine identified by its absorption and emission maxima), but a negative for 2/7 to any of the detectors.


Exploration concentrated on 2/7 and the large main stream was discovered. Two dye traces were attempted in 2/7. Approximately 100-200g of Rhodamine B was placed in the stream in the pitch series prior to the '87 limit and 1.5kg of Rhodamine was placed in the main stream. Dye detectors were placed and changed as in '87. The results (Table 1) were that a visible positive trace was seen after 1.5hrs from the '87 limit to a small inlet on the big ledge in Just Awesome and a positive trace was detected at Culiembro.

Table 1

Date         Cave              Resurgence             Throughput Time  

July 87      1/4               Culiembro              -                

July 88      2/7 '87 limit     Inlet on big ledge in  1.5 hr           
                               Just Awesome                            

July 88      2/7 (main         Culiembro              -                

July 89      2/7 (main         1) Culiembro           <52hr            

                               2) Upstream of         <7 days          


It was decided to repeat this trace and to determine a throughput time by changing the detectors regularly. Detectors were placed at Culiembro resurgence, at the upstream sump in Culiembro cave, at the Trea resurgence and 150m upstream from the Culiembro resurgence. The results (Table 2) were that dye (Lissamine FF) emerged at Culiembro resurgence in under 52hrs (but more than 6 hrs) Although the initial throughput time was short, dye continued to be detected until the end of the expedition. The detectors upstream of Culiembro were also strongly positive.

From this we can conclude that, due to the short throughput time, there is still a lot of open passage still to be found between the '89 limit in 2/7 and the resurgence. Additionally the strong positive upstream of Culiembro suggests that 2/7 may also resurge at springs upstream of Culiembro. Searches for other resurgences in this area on previous expeditions have, however, not been successful. For further details of the hydrological work carried out on the '89 expedition see [5].

Table 2

Dye placed in 2/7 stream at 6am GMT 21/7/89

Location of       Date changed      Fluorescence      Fluoresces in UV   
detector          (GMT)             (Arbitrary        light              

Culiembro         12am 21/7/89      0                 -                  

Culiembro         10am 23/7/89      151               +++                

Culiembro         27/7/89           45                +                  

Culiembro         29/7/89           105               ++                 

Culiembro         14/8/89           108               -                  

Culiembro cave,   in 24/7/89        76                ++                 
upstream sump     out 27/7/89                                            

Upstream from     27/7/89           152               ++                 

,,                29/7/89           120               ++                 

,,                14/8/89           0                 -                  

Trea resurgence   18/8/89           0                 -                  

The size of the main 2/7 streamway was estimated at 0.25 cumecs (m3s-1) by measuring water speed at a convenient location (time taken for a floating object to travel a measured distance, average of several readings) and measuring the area occupied by the stream at this point. This compares with 0.7 cumecs, the estimated flow rate of Culiembro resurgence [2]. Other known or postulated feeders of the Culiembro resurgence are Sistema Xitu [1], [3] (flow estimated at 0.05 cumecs); 1/4 (flow negligeable); and Cabeza Muxa (flow estimated at approx. 0.15-0.2 cumecs).

This provides a total of 0.45-0.5 cumecs contribution to the flow at Culiembro resurgence. Therefore, especially if some of the 2/7 water resurges upstream from Culiembro, there are more large feeders to Culiembro still to be found. However care should be taken in considering these calculations, because whilst the flow rates of 2/7 and Cabeza Muxa were measured or estimated in the same year, the flow rate for Culiembro resurgence was measured in 1983. More accurate results would be obtained if all the measurements were made in the same year at similar times, as we have experienced very variable flow rates in the caves from year to year. For example 1990 was a dry summer with very low permanent snow levels and the flow rate measured in 2/7 was less than half the '89 rate (see later).


The dye trace and flow rate measurements for 2/7 were repeated, but a more accurate value for the throughput time was determined by using an automatic water sampler set up at Culiembro resurgence by members of the Diving Expedition (Northern Pennine Club). In the event this was not needed as the 2kg of Fluorescein placed at the Primula Point (see survey) in 2/7 emerged as a visible trace in the Cares Gorge 60hrs later. Dye was also visible in the upstream sumps of Culiembro cave reducing the diver's visibility from 20+m to less than 3m. Measurements of the flow rate within the cave (carried out as in 1989) gave a value of 0.1 cumecs: less than half last year's value. This was due to the low rainfall and the much lower levels of permanent snow in 1990. Calculations suggest that the throughput time for the '89 trace was mid-way between the limits set in '89 (6) No dye was seen emerging upstream of the Culiembro resurgence indicating either i) the '89 trace was in error due to contamination of the detectors placed upstream or ii) the route to the possible upstream resurgence is a flood overflow and was not flowing in the much lower water levels experienced this year.


[1] Gale, S. (1984) Water tracing in the Western Picos Proc. Oxford Univ. Cave Club 11 33-35.

[2] Gale, S. (1984) Some measurements of discharge in the los Lagos Rio Cares area. Proc. Oxford Univ. Cave Club 11 36-38.

[3] Willis, R.G. (1981) Pozu del Xitu - 1981 Dye Tests. Proc. Oxford Univ. Cave Club 10 49-50.

[4] Winchester, H. (1986) Scientific Work 1984-85. Proc. Oxford Univ. Cave Club 12 33.

[5] Horsley, D., Roberts, S. G., Arthur, J. and Taylor R. (Eds.) (1989) Oxford University Cave Club Juracao Expedition Final Report.

[6] Lowe, G. (Ed.) (1991) OUCC Jultayu Expedition Final Report.

Dave Horsley

Some Thoughts on the Hydrology of the Ario Area

The region around the Ario Refugio contains many deep caves [1,2] including Pozu del Xitu which is over 1000m deep. However the hydrology of the region remains unclear.

The area is bounded on one side by the Cares Gorge, to which it is likely most, if not all, the caves resurge. The Cares Gorge contains only one major resurgence on its west bank - Culiembro Resurgence - which emits about 0.7cumecs under normal conditions, though this can be much reduced in dry periods (eg. summer 1990) and up to 8cumecs in flood conditions. It is likely that this is the resurgence for most of the caves in the Ario area. To date only three caves have been positively dye traced to Culiembro: Pozu del Xitu (-1135m, alt. 1652m), Pozu del Ojo de la Bruja (2/7, -810m, alt. 1860m) and Cueva de la Roca Naranja (-162m) (see above).

The resurgence is at river level and no passage can be entered. Above is an abandoned resurgence, Cueva Culiembro. This was first explored by the Swiss in the 1970s. The cave is a complex phreatic network of generally large passages which after some distance reaches a large fast flowing streamway, which emerges from a clear sump pool. This sump was dived by NPC expeditions in 1986-87 and 1990 and a large amount of new passage was found [3,4] (see survey inside back cover).

The entrance of Cueva Culiembro is believed to be at 420m with the actual resurgence at 340m. The NPC survey showed the upstream sump to be only 2m higher than the entrance, i.e. at 422m. Whether the streamway carries all the water which flows to the resurgence is not known, but the 1990 dye trace showed that the upstream sumps contain the 2/7 flow.

Pozu del Xitu is the deepest cave in the western massif at -1135m and contains two separate streams. The first sumps at -362m in the Trench Series and the second continues to the terminal sump at -1135m. The destination of the Trench series stream is not known, though it seems probable that it resurges at Culiembro, whilst the second streamway was dye tested to the Culiembro resurgence. The amount of water observed in Xitu is small and can account for only a small fraction of the Culiembro water. The rest of the Culiembro stream must be from other cave systems.

To the north of Xitu is Cabeza Muxa (alt. 1504m). This cave was explored by the SIE in 1978-84 (ref. [1] p41 and [2] pp265-267) and was finally bottomed at -906m. A large streamway is met at a depth of 600m. This extends upstream to a boulder choke and downstream to a sump which was dived by Rick Stanton in 1988 [5]. Initially the passage is at -4m for approximately 40m where a shaft drops to -24m. from here a tall rift passage was followed for a further 40m descending to a depth of -27m. At this point two ways on were possible: a small rift ascended to a blind chamber at -9m; or a steeply descending tube in the floor of the pasage which rapidly dropped to -33m and was seen to continue deeper for at least a further 15m. From the amount of water in the cave and the altitude of the final sump it seems probable that Cabeza Muxa resurges at Culiembro, though no dye trace was attempted by either NPC or the SIE. The source of the Cabexa Muxa stream is thought to be Pozu los Cuerries explored in 1986 by SIE to -575m [1] where a large streamway was met which sumped in a short distance both upstream and downstream. The source of this water is unknown, but at least some of it appears to come from Pozu los Texos (-218m) which has a streamway at the bottom.

Cabeza Muxa accounts for approx 30% of the Culiembro water whilst Pozu del Ojo de la Bruja accounts for a further 35%. The remaining 35% has not been accounted for, suggesting that a number of major cave systems remained to be discovered.

The feeders for Pozu del Ojo de la Bruja are not known, but some possibilities can be suggested.

1) Area 9 which contains La Jayada and the 306m shaft Tras La Jayada. This is a large catchment area, with (as yet) no major horizontal cave development. Also La Jayada in particular contains a very large snow plug which could account for some of the 2/7 stream. It is hoped to test this possiblity in 1991 by dye tracing.

2) The caves around the peaks near Punta Gregoriana (the Top Camp caves). OUCC have explored three major systems in the area: Sistema Conjurtao (-655m, alt. 1982m), Sistema Jorcada Blanca (-594m, alt. 1940m) and Pozu del Redondo (-582m, alt. 1937m) [6]. Close by are two caves explored by the Speleo-Klub Gliwicze, Sima del Porru de la Capilla (-863m, alt. 2200m) and Pozu de la Torre de los Traviesos (-416m, alt. 2180m) [1]. Sima del Porru Cappilla sumps reasonbly close to Sistema Conjurtao and it is possible that the large inlet which enters from a small aven near the sump in Sistema Conjurtao is the water from Capilla. The caves near Punta Gregoriana have been dye tested on a number of occassions. One possible positive trace was seen from Sistema Jorcada Blanca to the resurgence at El Hoya La Madre, but this was discounted as a second detector downstream from the main resurgence was not positive. Dye traces from the other caves have been negative even after 3-4 weeks. Therefore, considering the short throughput times from 2/7 to Culiembro it seems unlikely that the Top Camp caves supply the 2/7 water unless there is some large complicated phreatic network connecting them to retard dye flow.

A summary of the postulated hydrology of the area is shown in Fig. 1. Most of these links are awaiting confirmation by dye tracing. The confirmation of the Texos-Cueres-Muxa-Culiembro system and the determination of the source of the 2/7 stream seem to me to be particularly glaring omissions.


[1] Puch, C. (1987) Atlas de las Grandes Cavidades Espanolas. Exploraciones 11 Espeleo Club de Garcia.

[2] Courbon, P., Chabert, C., Bosted, P. and Lindsley, K. (1989) Atlas Great Caves of the World. Cave Books, St. Louis, USA.

[3] Danilewicz, C. (1987) Spain 1986 - the return trip. NPC Journal 4 5-58.

[4] CDG Newsletter 82 (1987) 2-22.

[5] CDG Newsletter 92 (1989) 25-26.

[6] Roberts, S. G. and Collie, U. (Eds) (1986) Proc. Oxford Univ. Cave Club 12.

Dave Horsley

Biological Collection

Contents: Hydrology: Biology: Geology: Geodesy & mapping: Surface Survey

In 1989 a cave adapted millipede, tentatively identified as Asturasoma fowleri (see [1] and [2] for previous collection and identification of this species), was seen in a boulder chamber above Choke Drucilla. A scheme was devised to capture specimens of this and other species during the 1990 expedition.

Bait was laid in the cave around the campsite and examined daily, but nothing was seen. The only animals seen and captured were several craneflies (Tipulids); these were found near the camp and by Pimpernel streamway, over 800m below the entrance. They do not appeared to be in any way cave adapted. This suggests that there is likely to be a lower entrance to the system, located near to the underground camp. The surface survey shows that the high level passages close to camp are within 350m of the surface.

It is planned to carry out a more extensive trapping program within the cave on the 1991 expedition, setting more bait traps in less frequently visited areas of the cave including the high level passages. It also planned to experiment with a UV lamp trap to attract cave insects, which was successfully used in Kenyan lava tubes.

Whilst exploring surface entrances a number of interesting bones were discovered. One cave (Cave of the Skulls) was littered with skeletons at the bottom of the 40m entrance pitch. These included the skulls of rebeccos (chamoix) and of the European wolf. The latter is now extinct in this region of the massif.


[1] Fowler, S. (1983) In: Proc. Oxford Univ. Cave Club 10, (J. Singleton Ed.) pp36--40.

[2] Mauries, J. P. (1982) Epigeal and cave dwelling diplopods of the Spanish Pyrenees and the Cantabrian Mountains, Spain. Astaurasoma new-genus Diplopoda Craspedosomida. Bull. Soc. Hist. Nat. Toulouse 117 162-170.

Dave Horsley


Contents: Hydrology: Biology: Geology: Geodesy & mapping: Surface Survey


A geological section through Pozu del Ojo de la Bruja and Sistema del Xitu was constructed in order to illustrate the relationship of the caves to the geological structure. The section was drawn projected onto a vertical plane perpendicular to thestrike of bedding (030° ). The section was used to demonstrate the geological controls on passage development. A summary of the geology of the area is given first to aid understanding of the cross-section.

Geological Context

The limestone massif of the Picos de Europa is made up of deformed Carboniferous limestones (circa 300 million years old), above a thin sequence of Devonian sandstone. The limestone sequence is repeated many times from south to north across the Picos de Europa by thrust faults. These are brittle fracture planes that cut across bedding at low angles. They commonly have ramp-flat geometries, being parallel to the bedding on the flats and cutting up through the beds at up to 30° or 40° on the ramps. Movement across these fractures, from north to south in the Picos, resulted in older, structurally lower rocks, being placed on top of younger, structurally higher rocks. Because the fractures are cut up through the sequence, the dip of beds in higher thrust sheets is greater than that in lower thrust sheets. In the Picos de Europa, this results in an increase in dip from gentle northerly dips in the south of the Picos to near vertical dips and even locally upsidedown beds in the vicinity of Ario (Fig. 1). The thrust faults in the Picos developed as part of a complex compression of the crust in Cantabria at the end of the Carboniferous (circa 280 million years ago). This was part of the important Hercynian mountain building event that affected a belt of rocks running through Europe and North America.

The Limestone Sequence in the Picos de Europa

The Carboniferous Limestones of the Picos de Europa can be divided into six recognisable units which are described from oldest to youngest (see Fig. 2):

1.The Griotte Limestone

This basal unit is a thin, red nodular limestone that was deposited over a considerable period of geological time. It is not seen high in the western massif but does occur in east-west bands in the Cares Gorge, near the base of the thrust sheets.

2. The Barcaliente Formation

The Griotte Limestone is overlain by the dark, banded, cherty limestones of the Barcaliente Formation. This occurs at the base of the thrust sheets where the Griotte Limestone has been faulted out in the western massif.

3.The Valdeteja Formation

The Valdeteja Formation is a grey massive limestone with occasional chert beds. The boundary between the Barcaliente and the Valdeteja Formations is transitional. The Valdeteja Formation outcrops at the top of Jultayu and in much of the area around Ario.

4.The Lower Picos de Europa Formation

The Lower Picos de Europa Formation consists of thinly bedded, occasionally bioclastic limestone. In places, the limestone contains abundant chert beds, 1-10cm thick. This formation is commonly encountered in the deeper regions of the caves in the Verdeluenga-Punta Gregoriana area.

5.The Upper Picos de Europa Formation

The Upper Picos de Europa Formation consists of more massive white or pink limestones. These are locally bioclastic. The entrance series to the Verdeluenga- Punta Gregoriana caves are developed in this Formation.

6.The Vega Huerta Carbonal Series

The youngest limestone formation consists of further tabular limestones. This does not outcrop in the current area of interest.

Pozu del Ojo de la Bruja, Sistema del Xitu Cross-Section

The cross-section (Fig. 3) has been constructed using the geological map of Farias ([1], Fig. 1) together with observations made underground. The section shows that Pozu del Ojo de la Bruja initially drops steeply through Valdeteja Formation limestone before penetrating the dark, finely laminated Barcaliente Formation in Just Awesome. The streamway and the London Underground start approximatedly parallel to the bedding in Barcaliente Formation but soon bend to north-east and cross into the overlying Valdeteja Formation in the vicinity of Choke Arnold. Downstream of the 1989 Camp, Pozu del Ojo de la Bruja crosses a major thrust fault and reenters the Barcaliente Formation. From here downstream, the bedding dips back to the south and the beds are inverted. The cave crosses back into the Valdeteja Formation upstream of Postman Pat and Choke Egbert is just short of another major thrust fault, above which the Valdeteja Formation dips to the north again near the top of the Canal de Trea.

Sistema del Xitu is entirely developed within the north dipping fault block to the north of Choke Egbert.

Geological Controls on Passage Formation

The extensive, deep, near-horizontal passages in Pozu del Ojo de la Bruja show two distinct passage trends, Nortwest-Southeast and Northeast-Southwest. The Northwest-Southeast passages are parallel to the local strike of bedding; some passages, eg the Picadilly Line and Postman Pat, are bedding chambers. The Northeast-Southwest passages define the dominant trend of Pozu del Ojo de la Bruja and are parallel to a well-developed vertical joint orientation. These joints, fractures across which there is no displacement, are easily seen on the surface and can even be confused with bedding where they are well-developed. The northwards tilting of Sistema del Xitu reflects the northerly dip of bedding.


[1] Farias P. (1982) La exstructura del sector central de los Picos de Europa. Trabajos Geologica. Univ. de Oviedo 12 63-72.

Phil Rose

Geodesy and Mapping Projects

Contents: Hydrology: Biology: Geology: Geodesy & mapping: Surface Survey

Coverage by Published Maps

The most detailed and accurate of the available topographic maps of the Picos de Cornio^0n seems to be the 1:50000 map published by the Servicio Geografico del Ejercito, Madrid (Mapa general ser. L, sheet "Beleno" 15-5). It shows the UTM grid, contours, paths, and buildings right down to the abandoned miners' cottages at Ario, but gives very few names. The scale is, however, too small to draw cave entrances onto it (up to a dozen per square cm!). Recently, a good 1:25000 tourist map of all three massifs of the Picos based on the Army maps has appeared.

The older topographic map of the Macizo de Cornion by Jose Ramon Lueje is still of value for the wealth of place names it contains, although the somewhat indiscriminate mixture of Castilian with Asturian forms, and of names in age-long use among the pastores with inventions by the 19th century cartographers, is somewhat confusing to linguistic non-experts.

A geological map at approx. 1:50000 covering the western and part of the central massif of the Picos de Europas is contained in Pedro Farias' dissertation [1], and part of this map was reproduced in [2].

Relationship Between Geographical, Grid and Magnetic Coordinates

The UTM (Universal Transverse Mercator) projection is one of several methods of mapping an idealized Earth ellipsoid into a plane. It is used primarily in the NATO countries. The mapping is locally distortion-free; at any given point the grid North-South and East-West lines intersect at right angles and use the same scale. Both the scale and the direction of grid North (the so-called meridian convergence) vary with the location, but the changes remain negligible over ranges of a few kilometres. Therefore directions and distances among grid-referenced points are easily computed. In the expedition area, the scale factor is almost equal to one (1 grid km corresponding to 1000.12m on the sea-level ellipsoid for locations near Ario, which amounts to 1000.37m real length at 1600m altitude, or 1000.42m at 1900m). Grid north is about one and a third degrees west of true north, varying mainly in the East-West direction from 1° 18' 53.3'' at Jultayu to 1° 20' 21.9'' at Pico Conjurtao. So true bearings are always slightly smaller than grid bearings.

Grid references can be converted to geographical latitudes and longitudes if desired, although the procedure is somewhat complicated.

Compasses read magnetic North: their obvious advantage is ease of use, their less obvious disadvantage the slow variation of the geomagnetic field. In the western Picos, magnetic North was about 3° 31.5' west of grid North in mid-July 1990 according to published figures (for the particular compass used in the surface surveys, the figure was 3° 16'), decreasing annually by about 9'. This is a degree and a half per decade: since Xitu was bottomed in '81, its sump has "moved' by more than 50m relative to the entrance in magnetic coordinates! Magnetic bearings thus are a bit larger than grid bearings, and will remain so for several years to come.

The Geodesy Project

Since geodesy and surveying are not taught at Oxford, a cooperation with the Geodetical Institute of the Technische Universitat Munchen had been started in 1986, with geodesy student Marcus Wandinger surveying a self-contained local network (of about 200-300m mesh width) in area F and linking the major cave entrances into it [3]. In 1987, Marcus was able to obtain UTM coordinates and itineraries of the vertices of the Spanish 3rd order network (of 10km mesh) in and around the Picos, including Pico Bricial (between Lago Enol and Lago de la Ercina), Cabezo de Llorosos, Pena Santa de Castilla, and Torre Cerredo; a finer 4th order network did not exist in this area. It was established by another student from Munich, Andi Kaab, during the 1988 expedition, using a Kern DKM2 theodolite. The 9 new vertices, forming a 2-3km mesh, are listed below. Andi was also able to tie in the Pozu del Xitu (1/5) and 2/7 entrances, as well as Marcus' older network (which thus became a 5th order refinement). This allows transferring distances and altitudes between caves near Ario and those up in area F to within a few ten centimetres, and to obtain grid references of cave entrances and any other features of interest by linking them to a nearby triangulation station. Another interesting application is correlating bedding or fault controlled cave passages to geological structures exposed on the surface, some of which can be tracked for hundreds of metres.

Results of the Geodesy Project

UTM coordinates within grid square 30TUN are given in the order Easting, Northing, Altitude; the latter denoting orthometric height in metres above the level of the Mediterranean Sea at Alicante. Longitudes are west of Greenwich.

The coordinates for the fourth order survey stations are given below. Except for the foot of the Jultayu summit cross, each of these stations is defined by the top centre of an M8 bolt. Coordinates are accurate to within +/- 0.06m relative to each other, and to PM0.1m (heights PM0.2m) with respect to the UTM frame. The coordinates of the Refugio and the cave entrances given below are accurate to within +/- 0.15m relative to the survey stations.

Cabeza Julagua: E 44 275.58 N 89 970.96 A 1721.75; 43° 14' 44.463'' N, 4° 55' 05.098'' W

Cabeza El Verde: E 44 650.58 N 89 451.70 A 1720.24; 43° 14' 27.918'' N, 4° 54' 47.952'' W

Jultayu: E 44 220.39 N 88 014.82 A 1941.53; 43° 13' 41.047'' N, 4° 55' 05.555'' W

La Rasa: E 42 549.51 N 89 073.50 A 1834.67; 43° 14' 14.097'' N, 4° 56' 20.670'' W

La Verdelluenga: E 42 333.32 N 87 815.33 A 2130.97; 43° 13' 33.173'' N, 4° 56' 28.955'' W

Top Camp reference point: E 41 742.57 N 88 012.16 A 1913.72; 43° 13' 39.105'' N, 4° 56' 55.330'' W

Pico de la Jorcada: E 41 413.53 N 87 571.64 A 2137.66; 43° 13' 24.585'' N, 4° 57' 09.452'' W

Pico Conjurtao: E 41 047.30 N 88 509.14 A 1926.06; 43° 13' 54.680'' N, 4° 57' 26.648'' W

Torre de los Traviesos: E 41 149.70 N 86 605.35 A 2388.22; 43° 12' 53.080'' N, 4° 57' 20.138'' W

Refugio Pedro Pidal, Marques de Villaviciosa, Vega de Ario (doorstep below chimney on northern side of the building): E 43 981.7 N 89 798.8 A 1630.5

Pozu del Xitu (1/5): E 43 565.2 N 89 433.1 A 1637.0

Pozu del Ojo de la Bruja (2/7): E 43 978.2 N 88 012.7 A 1848.1

Sistema Jorcada Blanca - Pozu Jorcada Blanca (F2): E 41 671.5 N 87 749.6 A 1967.0

Pozu las Perdices (F7A): E 41 552.3 N 87 977.3 A 1876.3

Pozu las Perdices (F7B): E 41 566.4 N 87 954.6 A 1881.9

Pozu las Perdices (F7C): E 41 558.5 N 87 931.5 A 1893.7

F20: E 41 290.3 N 87 889.4 A 1970.2

Sistema Conjurtao - "Ridge Cave" (F30 = 1/6): E 41 236.6 N 88 115.3 A 1916.7

Sistema Conjurtao - 2/6: E 41 166.8 N 88 020.5 A 1983.6

The Mapping Project

This was directed at creating a basis for documenting the forty-odd cave entrances and the numerous structural and morphological surface features crowding on less than a square kilometre around the Jorcada Blanca top camp. With Marcus's local network in place and being tied into a UTM grid reference frame, a full-detail grid-aligned 1:1000 map was produced by surface photogrammetry. In the course of the 1988 expedition, cartography student Sigrid Koneberg took two sets of six stereo photographs on pairs of (bloody heavy) 13 by 18cm glass plates, which were processed in two night-long lab sessions in the Ario Refugio (the second set becoming necessary since the first turned out to be underexposed, at manual shutter "speeds" of typically 15 seconds!).

Fitting points (only one of which turned out to be a sheep and walked out of the picture) were triangulated from the network with a Kern lightweight DKM1 theodolite, an excellent instrument for use in the mountains except it won't stand up to a mild force 5 Biscay breeze. After three weeks in the field, Sigrid spent many months at the stereo evaluator tracking the contours and scribing them onto the master sheet of the map. This work was accepted as the main part of her diploma thesis at the T.U.M. Cartography chair.

The limited time and eventual map size led to only the western half of area F being covered, which is conveniently shaped as a large bowl surrounded by hills and ridges. The huge cirque of the eastern half, including the slopes of La Verdelluenga and Punta Gregoriana, could become the scope of another similar project in the future. Further areas amenable to photogrammetric mapping include the Jou del Jultayu, the region between La Jayada and Cuvicente, and perhaps (parts of) the Trea and Extremero valleys.

A side effect of our walking to some rather unlikely corners of the area in search of suitable vantage points was the discovery of several further promising entrances. (See the section on Cave Entrances in Area F in these Proceedings.)

Phase Two, adding the cave entrances and geological observations to the contour map, was taken up by me in 1989. Unfortunately I was unable to come on the 1990 expedition, and much still remains to be done in the area. With four exceptions the caves known to be inside the boundaries of the map could be located, and a number of geological data entered as well. The major West-East thrust passing right through the campsite is clearly visible as a vegetation boundary. Some distinctive beds in the (younger) Picos limestone south of the thrust could be mapped, and the re-crystallized bands marking the faults along the two large gullies or "argayos" were tracked, one of which seems to control a large part of F20, while the other has not (yet) been associated with any cave passages. Misfitting beds show the displacement along the F20 fault to be of the order of at least 40m, although I am in doubt about the direction. Many smaller fractures crisscross the bedrock, sometimes intersecting and offsetting the older fault bands; they often give rise to spectacular surface rifts, but seem to have less influence on cave formation and topography on larger scales than the older ones.

Most of the time the contour map alone was sufficient to locate myself in the field to within 5 or 10 metres; occasionally a compass bearing was needed as well, and very occasionally I set up a theodolite and re-sected into the network. I was using a Jenoptik 080 kindly made available by a friend at Munich, a rather cruder and heavier but more windproof gadget than the Kern instrument. A Suunto compass can be mounted onto it (the same type as we use hand-held underground, except mine has a 400-grades scale like theodolites do) and can then be used reproducibly to 10mm (by aiming through the telescope and reading the compass and theodolite horizontal scales simultaneously at various points around the circle, and systematically combining sets of forward and backward rounds to eliminate lag effects: when mounted, friction in the compass bearing is no longer overcome by the trembling of the hand!). Of course calibration against a known grid direction is essential.

The map in its present form is found folded inside the back of these Proceedings.


It is our pleasure to thank the Professor of Geodesy, Dr Klaus Schnadelbach, and the Professor of Cartography and Reproduction Technology, Dr Rudiger Finsterwalder, along with all their staff at T.U.M. for their support and encouragement, and for providing all the know-how, equipment, and logistical support without which these projects would not have been possible. We are indebted to the Instituto Geografico Nacional in Madrid for kindly supplying the relevant data of the Spanish trigonometric network vertices. Blas and Julia were extremely helpful with turning the Refugio into a photographic lab, storing aggressive chemicals in a safe cool place between sessions, as well as protecting the drying plates from dust and reviving the yawning "processors" with strong coffee on the mornings after. And thank all of you cavers who at one time or another helped lugging precious and heavy gear around, quite apart from providing our raison dmmetre!


[1] Farias, P. (1982) La estructura del sector central de los Picos de Europa. Trabajos de Geologma, Univ. de Oviedo, 12 63-72.

[2] Kay, H. (1984) The geology of Jorcada Blanca. Proc. Oxford Univ. Cave Club 11 29-32.

[3] Wandinger, M. and Niklasch, G. (1986) Proc. Oxford Univ. Cave Club 12 p57.

Gerhard Niklasch

Surface Survey

Contents: Hydrology: Biology: Geology: Geodesy & mapping: Surface Survey

Jultayu-2/7-Green Ridge-Head of Trea Valley


On the 4th and 5th August 1990 Paul Mann and Claire Lindon carried out a surface survey along the approximate line of the cave. The objective was to locate the cave relative to the surface, with the following aims:

  1. To tie surface features in with the underlying cave passage.
  2. To find potential sites within the cave for radiolocation. This technique [1] has limits to the depths over which it will work of approximately 300-400m, therefore one aim of the survey was to determine passages in 2/7 that lie at a depth of less than 400m and would be suitable for radio-location.
  3. To focus the search for a lower entrance to the system.


Surveying was carried out using methods identical to those used for the underground survey [2]. A 30m tape, sighting compass and clinometer (Suunto type readable to a 1/2° ) were used and alternate legs were surveyed in the reverse direction ("leap-froggingmm) to reduce systematic errors. In all 90 legs were surveyed and a further three landmarks were located trigonometrically. The results were within 1% of those of Gerhard Niklasch's [3], the location of the 2/7 entrance differing by 2.6m horizontally and 1.8m vertically well within Gerhard's quoted accuracy of +/- 2.8m horizontally and +/- 4.0m vertically.

Further topographic information was taken from a 1:25,000 map of the Western Massif, Picos de Cornion [4], and magnetic North was taken as 3° 25' West of grid North to correspond to the 1989 survey of 2/7 used to compile the combined survey. Additional survey data was added from the 1990 survey.

The combined survey shows the cave to run obliquely under the cliffs on the South Eastern side of the North East ridge of Jultayu (known as the "Green Ridge"), before cutting across the head of the Trea valley. Choke Egbert is very close to (within 70m to the south of, and at a depth of 290m below,) the prominent surface collapse, Huerta del Rey. Given a general dip of 80-85° South East for geological fractures governing the cave development, it appears that these two features are related.

Points surveyed to include:

Skull Cave, which lies directly above the huge London Underground passageway, and hence has great potential of providing an alternative entrance. However, due to the vertical separation between the two, it would be foolish to predict where Skull Cave will connect with 2/7.

A strongly draughting boulder ruckle on the Green Ridge, which lies 125m to the North West of the cave;

5/10, which lies 220m distance North of the cave.

Three small caves in a rift in the North West corner of the large depression, Huerta del Rey; these unfortunately have no obvious leads.

29/5 was not included in the survey, but lies about 100m further North than 5/10.

Table 3 Shows the UTM grid locations of a number of points in the cave together with nearby surface features, and the vertical separation between the two.

Location            Eastings     Northings   Altitude     Vertical    

Egbert              344,867.8    88,667.9    1045.1       -           

Base of Huerta del   344,898.6   88,735.4    1335.0       289.9       

Brim of Huerta del  344,892.9    88,699.9    1367.6       322.5       

Nearest point on    344,910.0    88,625.0    1350.0       304.9       
Trea Path                                                             

Colostomy Climb     344,790.6    88,637.1    1044.2       -           

Trea Valley         344,750.0    88,600.0    1370.0       325.8       

White Inlets        344,660.8    88,632.4    1102.1       -           

Trea Hillside       344,660.0    88,630.0    1395.0       292.9       

Primula Point       344,506.5    88,478.4    1049.8       -           

Trea Hillside       344,625.0    88,500.0    1475.0       425.2       

Paddington Choke    344,440.5    88,469.3    1135.4       -           

Green Ridge         344,406.8    88,550.7    1611.0       475.6       

Other points                                                          
surveyed to                                                           

2/7 Entrance        343,978.2     88,012.7   1848.1                   

Skull Cave          344,177.0    88,197.6     1821.8                  

Jultayu             344,220.4    88,014.8    1941.5                   

The Primula Point campsite is at a depth of 425m. The closest the far reaches of the cave come to the surface is a depth of approximately 300m in three places: Choke Egbert, Colostomy Climb and the White Inlets in Soup Dragon. This distance may be reduced in the latter two cases by climbing. These points plus possibly Paddington Choke (at a depth of about 475m) would be suitable places for radio-location to check on, and increase the accuracy of, the cave survey.

The survey suggests that a search in the general area around Huerta del Rey may provide a lower entrance near to (or better still beyond) the present limit in 2/7. It is likely that any entrances on the slopes of Jultayu or around the Green Ridge will, if passable, connect with 2/7 whilst those in the area of the Jou de la Cistra and the Trea path up to where the path up Jultayu branches off are likely to connect with Sistema del Xitu (for example 3/5 and 12/5 [5],[6]).


[1] Macklin, R. O. (1984) In: Caving Practice and Equipment.(D. Judson, Ed.) pp175-179. David & Charles, London.

[2] Ellis, B. M. (1976) Surveying Caves BCRA, Bridgewater.

[3] Horsley, D. Roberts, S. G. Arthur, J. and Taylor, R (1989) Oxford Univ. Cave Club Juracao Expedition Final Report.

[4] Adrades, M. A. (1990) El Cornion mapa-guia del Macizo de los Picos de Europa. Oviedo

[5] Stead, W. (1986) Pozu los Caracoles (3/5): Description. Proc. Oxford Univ. Cave Club 12 11-13.

[6] Roberts, S. G. (1986) Pozu la Cistra (12/5): Description. Proc. Oxford Univ. Cave Club 12 5-8.

Paul Mann and Dave Horsley

Contents: Hydrology: Biology: Geology: Geodesy & mapping: Surface Survey