Cave exploration around the Matienzo depression during 1995

amended from an article by Juan Corrin in Caves & Caving 70

   Cavers during the 25th year of British Speleological Expeditions to Matienzo surveyed over 7km of new cave passage, taking the total of explored passage in the area to almost 188km, with about 1100 catalogued sites of speleological interest. The explorations occurred during Easter, a few days in June, a five week period in July and August. and some days in October. There were no major new discoveries this year: some loose end were explored and numerous new holes were found to enter next year. The main discoveries are listed in the table.

Torca de la Cabaña (Vera Negra)
   This high level shaft (site 36), on the southern side of La Vega, with a major level at 333m altitude, has been known since the '70s. The main level is about 130m above Stuffed Monk Passage in Cubio de la Reñada (48) and, with various holes dropping down from Cabaña, a link to the cave below had been expected for years. However, the reverse happened. A bolt route up a large aven in Stuffed Monk followed by some 50m of serious free climbing gained a hole in the floor of Cabaña which had not previously been descended. The South Vega System including Cubio de la Reñada, Torca de la Cabaña, Torca de Coterón (264) and Torca de Azpilicueta (333) is now over 24km long.

El Sistema de Cubija
   Beneath the Cubija valley, on the north side of La Vega, there are two small resurgences. The eastern cave, Fuente el Escalón (Penny‘s Cave, site 280) was explored to a small sump in 1981. The sump was passed 5 years later to a tight, miserable but draughting passage with no end in sight. The other resurgence, with a top and bottom entrance, lies 220m to the south west and was pushed last year, linking the two entrances with 2.34km of passage. One "tidying up" trip in 1995 explored 140m of new passage.
    Last year, the 14.2km Cubija System was created, with Cubio-Regaton and Torca de Mostajo being linked. Other caves nearby included Torcón (67), Picón (75), Lastrilla (427) and sites 415 and 774. In 1995, the GT Series in Torca de Regaton provided a significant extension of nearly 700m. Beyond Hedgehog Crawl, two sections totalling 285m were explored. The Cubija System now has a length of 15621m and still has potential to go in most directions!
    One hundred yards downstream from Regaton (892) lies the strongly draughting entrance to 774. This was dug in summer and pushed to 733m, over passages in Regaton, but with no connection to either that cave or Mostajo. Torcón de Cubija was pushed to a small sump immediately under passages in Mostajo.

The Four Valleys System
   In Cueva Hoyuca, four people returned to complete the exploration at the top of the 102m high Astradome aven, interrupted last year by the tragic death of Alan Box. The scaling pole was raised to enter short, choked passages in both directions along a fault.

Diving
   A number sites were dived during the year by Martin Holroyd, Rob Murgatroyd, Steve Openshaw, Phil Papard and Rupert Skorupka. Peter Plummet (239) at San Miguel de Aras was dived to a depth of 60m, with the shaft continuing down at least another 20m. It may be possible to continue with helium mixture but an attempt in October was thwarted by tight passage before the flooded shaft.
   Fuente Aguanaz (713) at Entrambasaguas stopped at a sump some 800m in. This was passed to show the large passage continuing as a swim. The cave was then explored through sump 2 to a boulder choke with some prospects. The cave was doubled in length to 1.7km, mainly swimming. (Survey)
    Cueva Llueva (114) in the Llueva valley is part of the 41km Four Valleys System. The downstream sump, some 1.4km from the Los Boyonnes (117) resurgence in Secadura, was last dived in 1977 to boulders in bad visibility. This year was a re-run, with visibility at 0.5m and no progress made in the bouldery pool.
    In Wild Mare Cave (767) near Entrambasaguas, a short dived entered more cross rifts, bringing the length to some 346m.
    Cueva de Bollón (Volvo, site 98), at the northern end of La Secada, comes very close to the western arm of Cueva Carcavueso. Sump 1 in Bollón was passed last year. This year, sump 2 was passed into 150m of passage to another sump.

Fresnedo
   Cueva de Fresnedo (841) was extended by some 244m in the complex area of Paul‘s Chamber, near the entrance. The length is now over 7km.

Cueva Valline
   Cavers from Tortosa have been exploring Cueva Valline since our initial discoveries in 1989. Good relationships have been built up over the last couple of years. This year a group camped in Matienzo and joint explorations were carried out. Nearly 3km of new passages were surveyed with a number of leads still going. Walks on the hills over the cave have produced a number of interesting sites to descend in the future. The length of Valline is about 23.6km. With a link through the hill to the South Vega System seeming inevitable, a 50km system is an excellent possibility.

Hardware and Computer Programs
   Once again, we were fortunate to be loaned a Garmin satellite positioning instrument - thanks to Tony Haigh.
    Various computer programs were used to process the raw survey data and display and plot the results. After this years expedition, data from the major sites was converted to Survex-readable format. The screen display program associated with Survex now displays all the line surveys of these 40 sites at once (total length about 130km, with 14755 stations) and allows zooming and rotation of plans and elevations instantaneously from any view point. Most impressive!
    Olly Betts and Wookey are producing this free software for PCs and Arcs with continuing upgrades.

Acknowledgements
   Thanks are due to the caving and regional authorities who provide the necessary permits, and the many friends in Matienzo and Spanish caving groups who make us so welcome.