OUCC Proceedings 13 (1991)
Scientific work in the Picos de Europa
|Proc. 13 Contents.|
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 , and part of this map was reproduced in .
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.
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 . 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.
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
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!
 Farias, P. (1982) La estructura del sector central de los Picos de Europa. Trabajos de Geologma, Univ. de Oviedo, 12 63-72.
 Kay, H. (1984) The geology of Jorcada Blanca. Proc. Oxford Univ. Cave Club 11 29-32.
 Wandinger, M. and Niklasch, G. (1986) Proc. Oxford Univ. Cave Club 12 p57.