Matienzo 1987

Cave exploration around Matienzo during 1987

amended from an original article by Juan Corrin and Steve Knights in Caves & Caving 41

The exciting extensions and connections within the 4 Valleys System the previous year was bound to produce a feellng of anti-climax during the 1987 trip. Nevertheless, a number of significant new passages were discovered and over 6km surveyed.

Four Valleys System
   The sink cave of Carcavuezo (site 81) was entered on a number of occasions in an effort to extend it and find another link into Cueva Uzueka (107). Small lengths of passage were added but the only trip through into the far end of Uzueka was through the original unstable choke - which moved again. Although the route would cut a couple of hours off a pushing trip in Trident Passages at the end of Uzueka, the risk of injury outweighs the advantages. It may be worthwhile entering Uzueka and camping in the Trident area - it is unlikely there is only one connection.
    At the western end of Carcavuezo / Llueva (114), 300m of flat-out crawl was explored and a number of people got lost in the multi-level Sewers of Doom area. This, and the enlarged joint mazes should provide more than a couple of kilometres when all routes through are surveyed.
    Cueva Riano (105) was extended by 500m in a number of places - the cave still has possibilities waiting to be pushed.
    Work was carried out in a number of other caves which could be associated with the system. At the base of the northern side of the depression is Cueva Volvo (site 98), a phreatic segment with a number of strongly draughting leads. One, near deep water, was dug and pushed over a number of trips to where it became too tight, but "getting bigger beyond" and needing chemical persuasion. The potential behind Volvo is superb. Rocabado (92), to the northeast of Volvo, was re-descended and poked about in, but no extension was made.
    The length of the Four Valleys System is now surveyed to over 33.2km.

The South Vega System
   At 20.4km, the complex at the main rising into the depression is the second major cave explored by the expeditions. This year, the extensions beyond the upstream Reņada (48) "sump" were re- entered but little new passage was discovered; a slot was passed in the streamway to the "real sump, which was at least minibus size".
    In Coteron (264), Frank‘s Passage was extended down a pitch into a dig and a crawl connected with Bootlace Passage.
    In Azpilicueta (333), a new series of pitches was entered off to the side of the main route at about 100m depth. A short climb up to a muddy traverse ended at a 15m ladder pitch. One hundred metres further on, through a sandy crawl, the passages opened to the head of a 30m pitch and at the base, another similar pitch with dodgy stal belays which was left for 1988.
    Three kilometres to the south east and at about 580m altitude lies the entrance to Torca del Hoyón (567) at Alisas. In 1985, an apparently positive, 19 day, dye test to the stream in Matienzo pointed to the water drainage through Reņada. This year, after obtaining permission and consulting the Catalans who were exploring the cave, the pot was surveyed and a small extension made. This was a dig at 100m depth into an impressive aven with a bolt climb to nowhere. At the bottom of Hoyón, 1.8km along a small streamway and at about 230m depth, the cave turns about and starts heading towards Reņada. The 350m altitude of the final chamber with sump below means that there is still a distance of over 3km and a height drop of 150m to reach the water in upstream Reņada.

North Vega
    The major caves on the northern side of the Vega arm of the depression are Mostajo (71), Rascavieja (77) and Toad-in-the-Hole (258), all with major levels at similar altitudes. Rascavieja was pushed between unstable boulders to where progress was considered too dangerous. Mostajo received some attention with small extensions. In cave 415 an attempt was made to descend a sharp, knobbly and "a right sod" 65m drop, but the major discoveries came in Toad- in-the-Hole.
    Toad was first entered in 1981 after a dig in a draughting shakehole. Over 500m of phreatic passage was entered with a large chamber at a lower level with clusters of helictites. Draughting holes in the cave were noted but left, as bigger things in Coteron were being discovered that year. The sloppy entrance to Toad was re-excavated and a team visited the two draughts at the cave end. One was abandoned as being too unpleasant; Chocolate Slice crawl progressed slowly. After three days the breakthrough came over a traverse, down a 10m pitch and into 500m of sand-floored passage. Later another 500m was discovered which passed around the west of the valley, coming very close to the surface. Another extension was made beneath the entrance drop in a series of interconnected avens to bring the length to more than 2.1 km.
    Toad- in-the-Hole is an isolated fragment of roomy tunnels in an area which has potential in all directions. One of the extensions heads south towards Arenal (35) where digging in the strongly draughting boulders by the Derbyshire contingent this year produced a conclusion - "it‘s yours if you want it".
    To the southwest lies Torca de Reguilon (46). After a report from a farmer that a group from Tortosa had been into Reguilon and reached -140m, the loose pot was redescended and pushed down two 10m pitches to a "final" depth of about 100m. The Spaniards apparently reached -140m but stopped because the pot was too loose.

    The hills of Muela and Mullir yielded a few more new entrances but only one descent of any note was made, site 635. A climb of 5m followed by pitches of 10 and 15m entered an 80 x 30m chamber with a number of blind pots in the floor. The traverse length of the hole ended at 500m with a second entrance crawl emerging at the base of a cliff.
    At Secadura, 370m to the east of Los Boyonnes (117) resurgence, El Bodego (237) was dug out and extended to 225m in small passage which split and became smaller.
    On the northern slopes of Secadura, site 122, Suviejo (wrongly called Solviejo in 1977) was quickly re- explored and 100m added to its length - in the streamway below Brain Cell Hall; the length is now 3.5km.
    The area of Cobadal, to the west of the Matienzo depression, was revisited. The apparent potential, with water draining off sandstone into the hillside, looks great, but little was discovered. Cueva Candenosa is a large remnant with several, low phreatic inlets; a nearby torca dropped 5m folbwed by an 8m pitch to a slopping floor of dead animals and an undescended pitch.

   As always, thanks must go to the locals and the Spanish caving clubs, individuals and authorities who help to make our stay in Matienzo so worthwhile. Cultural events included an invitation to the expedition by the Mayor of Ramales to show the 1986 Matienzo video. During the day chairs were set out in the town square and a public address system and televisions brought in from Laredo. After the video was shown that evening (with the Townhall picking up the meals and drinks bill) El Alcade made a speech and presented the expedition with a plaque inscribed "To the British Speleological Expeditions for their work and investigations". A similar plaque was presented to Germán‘s Bar in Matienzo; for putting up with us for the last eighteen years.