Cave exploration around Matienzo during 1991

amended from an article by Juan Corrin in Caves & Caving 55

La Sistema de Cuatro Valles
    Explorations downstream in Cueva Riaño (site 105), the northern feeder to the Four Valleys system, resulted in 1569m of surveyed passage, including old phreatic levels. In the third trip downstream since its discovery 20 years ago, the sump‘ was found to have two feet of airspace, with a strong draught blowing through. The streamway was followed down to a sump which is still a couple of hundred metres from the resurgence pools. One inlet on the north side was followed for some 700m to a restriction which may be passable. Another inlet was found which carries a river as big as the main stream. The water was badly polluted which suggests that water from Riaño village feeds into it. Further finds are likely.
    La Hoyuca (Cueva Uzueka, site 107) was extended by 713m, filling in part of the joint-orientated entrance series.
    In searching for a new connection between La Hoyuca and Cueva Carcavuezo (81), the drainage outlet from the Matienzo depression, numerous holes were catalogued and some dug, various points were radio-located and a number of trips explored likely sites in both caves; no new link was found to bypass the dangerous boulder choke route discovered in 1986.
    On an ill-fated trip into the Trident Series in Hoyuca, a group set off at 9am through the new entrance only to find the wallow (crawling on knees up to the waist in liquid mud) was now full of shit with toadstools waving in the breeze; some seven hours later while molephoning and exploring possible connections to Carcavueso, Snablet joined the Matienzo Flying Club by dropping 6m out of the roof and rendering himself unconscious for a few minutes; the group returned to the surface after an 18 hour trip and found that the car wouldn‘t start. JJ and Jonathan walked the 10km back to camp to get transport.
    The offending pool in Hoyuca was later photographed and a letter sent to the authorities. (The MFC gained five members this year; all entrants needed rest from caving, some needed hospital treatment. In Cueva de los Cantones, Andy Quin removed a section of wall which pushed him over a drop and damaged his ankle already extensively rebuilt after a fall in an Austrian cave a few years ago.)
    The north-eastern end of the valley revealed more cave with the discovery of Cueva de los Tres Niños (site 565). Although surveyed to only half a kilometre, the presence of large passage at this high altitude, over passage in Carcavuezo, seems to confirm that there may be another level of development above those already known in the Cuatro Valles system.

Sistema de la Vega
    Exploration occurred at the upstream (southwest) end of Reñada (48) where some new passage was entered and prospects remain reasonable. The upstream end of the cave was radio-located and various surface draughting digs looked at. Further explorations in the cave added 676m to its length.
    A new, higher entrance to the system was explored to join with Azpilicueta above the 4th pitch giving a slightly increased depth of 310m.
    Between the Vega system and Cueva de Codisera (39), Cueva de los Cantones (TV Mast Cave, site 865) was explored and surveyed to over 1.7km, with more extensions possible and a depth of 285m indicating that the water in the cave doesn‘t resurge into the depression but to the south or east, through the hill.

Fresnedo
    In this area to the north of Matienzo, a new cave, Cueva de Fresnedo 2 (site 841), was dug and explored through a tight choke to 1.4km of passage, including phreatic levels above the modern streamway. At the south-eastern end, a very strongly draughting dig appears to have been by-passed. The last trip into the cave stopped at a pitch into a large chamber which, according to the survey, seems to go beyond the dig. The draught and the cave‘s position indicate that kilometres of passage await discovery under the ridge towards Cueva de Suviejo (122) and the Secadura valley or even towards the Four Valleys System.

Miscellaneous
    Cueva Mostajo (71) was extended a short distance down a pitch to the east.
    Horse Trough Pot (site 875) was discovered under a boulder capping at Seldesuto and explored down a 28m entrance pitch to 135m of large passage.
    The top level in Cueva Valline (733) near Arredondo was filmed after gaining permission from the Tortosa group who have the permit. Subsequent conversations led to an invitation to dive the sump next year. (Originally explored by us in 1989 to 9.7km, the Tortosa group have extended the cave to 12km.)
    Under Enaso, Cueva del Agua (site 59) was extended by some 45m in the Rioturto inlet and a pitch was descended in the Misty Series in Torcon de la Calleja Rebollo (Toad in the Hole, site 258). Further exploration was also carried out in the shafts on Enaso and Muela.

Camargo
    These sites have nothing at all to do with the caves in our area but are included here because the British cavers at Matienzo were invited to explore and assist in recording the cave by the permit holders.
    Covachos de Peñajorao, in low level limestones near Camargo to the south of Santander, was partly explored last year after an invitation from a group of Spanish archaeologists. This year we were once more invited to continue the exploration and survey. The cave was explored for almost another 2km, the end radio-located, the resurgence explored and various specimens collected in the main cave by Carlos, one of the Spanish team. Exploration possibilities remain good. The Spanish group applied for and received a grant of five million pesetas from the local town hall to carry out research in the cave.
    Further co-operation occurred with this group when we filmed in a new , undisturbed archaeological cave near Santander. In about 200m of well decorated passage, behind a calcited, man-made wall, are bones, pottery, charcoal, flints, pieces of copper; an iron chisel and black and red dots and lines on the walls. The Spanish intend to produce a journal with an accompanying video made up from the film shot this summer.

Conclusion
    During a fiesta jointly arranged with the locals involving a band and barbeque to celebrate our 21 years in Matienzo, a plaque was presented to the British with the following inscription:

Excmo Ayuntamiento de Ruesga
A las Expediciones Britanicas a Matienzo 1970 - 1991
En agradecimiento por las Actvidades Socio-Culturales y Deportivas realizadas en nuestro Municipio.