MATIENZO CAVES PROJECT
Matienzo '89

Cave exploration around Matienzo during 1989

amended from an original article by Juan Corrin and Terry Whitaker in Caves & Caving 49


The 1989 summer expedition to Matienzo was arguably the most successful to visit the enclosed depression. Over 14.4km of new passage were explored, surveyed and photographed. The major find was Cueva Valline, above Arredondo where nearly 9km of mainly large tunnel were mapped.

Cueva de Valline
    The north-flowing river Ason, in a gorge surrounded by many spectacular systems including Cueto-Coventosa, makes a sharp right turn to flow east at Arredondo. To the west of the town, the road splits - one branch following a stream to the resurgence of Molino, then petering out at the village of Bustablado at the valley head, the other climbing the northern side of the valley until it reaches Puerto de Alisas at 600m altitude. Shortly after the road splits, a twenty minute stroll up the hill leads to a well-hidden, 15m wide gash at 410m altitude which is the entrance to Valline.
    The 5m high entrance chamber goes back 50m and is obviously a prime archaeological site. During a Matienzo visit at Easter the rear of the entrance chamber was dug out to follow a draught. After a short squeeze and crawl the excavators found themselves at the head of a 10m pitch into a large chamber, without tackle. The exploration had to wait until the summer when eager hoards explored most of the open passage in the first couple of weeks.
    At the base of the pitch a steep slope drops down to a cracked mud floor and white calcite flow. The passage turns to head east, and the cave 'takes off'. The tunnel continues, 10m wide and high, past some decaying antlers, to a 4m climb down. The route becomes larger over boulders and finally slopes down in a 20m wide and 25m high chamber. The right hand wall consists of sand and boulders and a climb up leads to a walk along the right hand wall to a fine veranda looking back down into the chamber.
    The passage continues as the Sunday Stomps for 250m, passing some crystal pools at the Glitter Run and emerging into a chamber where the ways split. To the south, the route skirts a pit and leads to a muddy 25m pitch on a corner. The passage turns to the east and becomes the superb, sandy Chunnel 10m high and wide. After 70m the floor rises to a wide, choked 15m deep pitch to the right while straight ahead the route lowers to a short climb down through boulders to a 30m pitch.
    The usual route down into the middle of the cave lies near the Glitter Run. The spacious second pitch is split into drops of 12m and 18m and lands on boulders which slope to the head of a 12m descent, passing under the 25m pitch first used to enter this series.
    At the base of the second pitch the main route continues as walking or stooping for 150m, following an inward draught and finishes at a steep slope down into a tall chamber. A climb up of 3m on the right hand wall leads to the head of the third, 13m pitch. At the base, the routes split: a slot leads directly to the remainder of the cave and will be described later; the wider route leads to the middle entrance. (Lost Pot Entrance).
    A slope and climb down of 4m passes Windy Corner and continues in varied, comparatively small going, past a number of openings, until a bouldery area is reached. It was at this point in the original explorations that a small clay beaker was found.
    The main route continues from the base of the third pitch, entering a draughting slot beneath the ladder. A maze area is entered where not all the passages have been surveyed or even explored. To the north, the maze ends at avens in a 10m wide, boulder-floored passage; the main way on lies to the east, where similar passages in the maze lead south to the large, calcite and boulder-floored Who Knows? chamber. Heading to the northeast through Road to Nowhere passage leads to a squeeze in sharp rock. A caver coming from the top entrance might now have to put on an oversuit. The route then enlarges to the Canyon.
    A tight and sharp climb down leads to a step over a short drop. A muddy climb up on the opposite side reaches the continuation of the passage, described below. In the floor of the canyon, a route out exists which is best described as tortuous and unlike most of the rest of the cave. 700m of passage links back to the Maze area in the Hole in the Wall.
    Beyond the climbs in the canyon the passage is again of reasonable size, walking with the occasional squeeze. After 80m the way splits, the northern route passes an undescended pit and then narrows to emerge in a 10m wide passage. The eastern route, the Clapham Bypass, is easier going but emerges in the same passage at a group of pleasant formations. The passage to the north of the Clapham Bypass continues up to 15m wide and l0m high in the sandy-floored Roads to Glory. To the north, the passage splits, the left hand branch gradually enlarging to a junction after some 60m.
    To the right the route becomes 20m wide and rises to the east to a large, draughting boulder choke. A northern branch slopes down to a 12m climb up, and this ends after some hundred metres at high level, unexplored passages and boulder chokes. To the left the passage has a superb flat roof and sandy floor which enters Swirl Chamber at the base of a large boulder slope. Swirl Chamber is approximately 40m in diameter and rises up on loose boulders to three passages at the western side. The northern tunnel ends at a choke after 50m, the middle line continues 50m unsurveyed and the southern one continues for 120m to an unexplored pitch. On the southern edge of Swirl chamber, a small passage enters an unsurveyed section.
    The only passage through to the rest of the cave lies to the north at the base of the boulders cascading out of Swirl chamber. A short walk over rocks emerges at the five way FN Junction. The large boulder slope to the left chokes. Six Hundred Pesetas Passage is entered on the opposite side of the junction. This passes crawls on the right after 20m and passes a 30m unexplored pitch where it turns to the west. Incompletely surveyed side passages to the north include one with '60m to a window into big stuff'. Six Hundred Pesetas Passage ends after 350m from FN Junction at a boulder choke. Just to the south of Six Hundred Pesetas Passages lies the entry to a small tunnel which passes a 4m drop after 50m and leads to the 9m deep Tuesday Pitch. At the pitch base a small passage continues low and nasty upstream while downstream it leads after 100m to the Rioja River. This is also entered via Dutch Pitch, described later.
    FN Passage to the east of FN Junction is 20m wide and 10m high but closes down after only 150m. Where FN Passage swings north, two exits lead off on the right wall. The right hand route leads to The Dutch Circle where a loop contains formations, boulders and a 20m undescended pitch. The left hand route leads to the 31 m deep Double Dutch Pitch, the normal entry point to the lower streamways.
    At the base of the pitch, the upstream route ends at an aven after 150m, while downstream the passage meets a T junction at the Rioja River. The passage upstream sumps after some 120m, after passing an unsurveyed, choked area. The downstream passage continues for about 700m.
    The passage starts with standing water and after 250m meets the inlet from the Tuesday Pitch. The water then heads off to the north along the small Where the Rioja Goes. The route continues larger to the west and after 50m meets another inlet, the Rioja Reserva entering from the south. This stream passage is of impressive dimensions for most of its 400m length. It ends where the water wells up through a choked area. The Rioja River continues west to meet a sump. This has a short bypass and the stream passage continues and enlarges for another 100m to end, after a complex boulder area, with a sump and small inlet passage. The water (in dry weather flow) has been dye tested but detectors in Molino and Comellante in Matienzo proved negative. A route through the boulders leads to a small passage heading west and a tight section where a strong draught encourages digging.
    One branch in Cueva Valline ended, over a kilometre into the cave and 100m lower, at boulders on which sat a small, clay pot. The survey indicated that the passage was heading towards the surface and so Paul Stacey & Phil Papard sat near the beaker site and hammered on the passage walls. A larger team on the surface made thefr way to the pencil dot on the map and then most dispersed across the fairly featureless hillside to various draughting holes in the vicinity. But the pencil dot was correct and hammering contact was first established through the roof. Everyone converged on the spot and found a draughting collapse nearby. The underground team then lit a small fire with bits of paper and neoprene and the very positive surface sighting showed the place to dig. Two hours later voice contact was established and after a further two hours the underground pair emerged up a 3m excavation. A most satisfactory afternoon which proved the surveying was up to standard. The lower entrance now provides a quick entry to the further reaches of the cave.
    At present, the cave has a length of nearly 9km and, most interestingly, is heading through the hill towards the back end of the South Vega System in Matienzo. The lower reaches have streams and sump bypasses which are still going. A number of leads remain to be pushed in the higher levels. When joined together the network would have a length of over 30km.

Caves at Ogarrio
    Two caves kept a number of the expedition happy for a few days. In a 'normal' expedition these caves would have been the highlight, but Valline ensured that Humo (734) and Esquimadera (739) were always second best.
    The entrance to Cueva del Humo lies in a dry valley at 345m altitude and the passage heads off into the hill side as a steeply descending boulder slope. A large, clean-washed rift continues with avens on both sides to a series of pitches, 13m, l0m, 23m, 3m, and 3m followed by walking in a strearnway to a junction. To the east is an impassable wet crawl and to the west lies the inlet of Je ne sais pas pourquoi. The passage is a tight rift with a small streamway with evidence of different stream levels. The survey stops at a large amount of calcite flow but the passage continues, becoming tighter until it becomes impassable.
    North from the junction continues to a small sandy climb and a rift to the head of a 4m pitch and a tight rift into the Coffee Shop Chamber. A number of routes lead out: the water appears to go along a wide, low crawl to the left with pebbles and flood debris. The crawl becomes tight and immature and ends in a blind sandy crawl. A 2m climb to the left drops into low, wet, draughting crawls.
    Through an eyehole and up a sandy ramp leads to walking passage in an inlet, 2m wide by 3m high. A small chamber has a number of ways off including a climb into the loose roof. The obvious way on is to the right in a dry, wide rift. This continues as high breakdown passage, steeply inclined passing through collapsed chambers. The cave finishes at nasty boulders and avens with a length of 1135m.
    The entrance to Torca de Esquimadera is situated 15m higher up the valley than Cueva del Humo. A sandy ramp degenerates to an area of loose boulders. A pitch of 8m is followed by a l0m pitch in quick succession. A loose, bouldery area leads to a 19m pitch with an unsurveyed passage with a draught. To the right a low crawl leads to a traverse to the top of a 26m pitch. From the base a very high but narrow rift leads out to pitches of 17m and 9m in clean washed streamway. A tight passage requires some traversing to an 8m pitch. A calcite-floored chamber has an obvious route to the left which ends at an aven. An insignificant crawl pops out into the streamway which has debris up the walls with boulders and sand. Fifteen metres downstream enters a large aven and continues in boulders. The stream cuts down in the floor while the caver stays at high level on the right. A fine gour pool is passed on the left and at a calcite area a ladder eases a slippery descent of some 5m.
    The stream continues in the trench with traversing above when an area of dropped roof slabs, covering the trench is met. walking over the slabs and continued traversing leads to a place where the higher level becomes impossible and tackle is necessary to reach the continuation at stream level.
    Upstream, Top of the World is a large aven with large boulders at its base. The passage narrows upstream to a large pyramid-shaped block which lies across the passage. The streamway widens, cutting a trench at this point, with debris. Routes diverge at various levels, leading to a high route with a flat ceiling and much debris. At Apache Junction two routes of significance lead off. The one to the west has excellent straws from the roof which lowers to a crawl which may continue. The passage to the east enters an area of calcite flows which close down in crawls and small chambers with avens. A small rift is impassable. There are a number of avens with good echoes. The length of Esquimadera is 700m.
    At present, the caves look likely to join - downstream Esquimadera ends at a drop down a widening traverse and upstream Humo ends in a narrow rift. The older tunnel in Esquimadera should continue into the hill above any tight connection at stream level!
    Higher up the hill, continuing the tradition of previous years, various shafts were descended in the search for the big one under Muela. All sites choked.

Carcavuezo and the Four Valleys System
    The Four Valleys System is the longest cave in our area and the second longest in Cantabria at over 38km. The system can be entered at a number of points: in Riaño village lie the entrances to Cueva Uzueka (107) and Cueva de Riaño (105); a large depression in Llueva valley encloses the small entrance to Cueva Llueva (114) and the entrance to Carcavuezo (81) is a small hole above the flood sink at the northern end of the Matienzo depression. The extensions of 1986 extended the cave to the east and linked it with Cueva Llueva; 1987 saw the system joined to Uzueka through an unstable boulder choke. In 1988 the cave was extended to the west, ending near to Cueva Bollón (site 98); 1989 was a year of 'consolidation' - the cave was photographed, avens bolted in the search for a useable link with Uzueka and other small extensions were made. Other extensions within Uzueka and cueva de Riano helped increase the length of the system to 38169m.

Toad In The Hole
    Discovered in 1981, this cave has recently been extended towards Calzadillas, heading into the unknown. Numerous leads remain unpushed in the rush for glory. This years push at the end found the cave coming back on itself. Some explorations in the middle of the cave gave a small increase in its length to 4613m. A smoke test proved that one arm comes close to the surface, the smoke pouring from a known hole with a good draught. Prospects for a bottom entrance are, however, remote.

Fuente Aguanaz
    Last year, a four hour trip in a flooded stream passage had the cave surveyed to 698m with some leads to push; the potential being excellent. This year saw a group of six with bouyancy aids making their way to the end. The sump was pushed to an airbell and a passage 5m down needing full diving gear. An inlet was surveyed for 173m.

Simon II
   
Underground water from around the Matienzo depression resurges out of the southern slopes of the Secadura valley. On the opposite side of the valley are the caves of Suviejo (site 122) length 3.5km, Torca de Simon (121) altitude 190m, length 330m and the resurgence of Churro (118) altitude 65m, length 460m explored by the 1978 Matienzo Expedition. About 200m down the hill side from Simon lay an open shaft that was unknown to us until this year.
    Expecting the shaft to choke, initial exploration was combined with SRT familiarisation. Learning the finer points of SRT were soon forgotten when the cave went - 430m that first day and another 490m on a subsequent trip. At the end of the summer, the cave consisted of large, crumbling rifts, phreatic tubes and small inlet passages, more or less on one level. On subsequent trips in October the cave was pushed for another 800m when a streamway was encountered at a lower level. When the survey was drawn up Simon II was found to be just a few metres away from the upstream sumps in Churro.

Socials
    After various health warnings and illnesses in previous years, the camp was moved out of the oak wood and nearer the bar - in fact to an open field behind the bar where there was little risk of colliding with a tree at three in the morning. With virtually no rain, the field was almost idyllic, although the sun beating on the tents at 9am did nothing for a hangover.
    Drinking injuries were scarce this year - only Toby dislocated his shoulder after falling off the bar. An associated highlight was the trip to a Rioja bodega where a coach party of thirty cavers and Matienzo locals were shown around the cellars where the wine was maturing in bottles stacked in alcoves. One of the locals decided to remove a bottle from the bottom of the pile, with predictable results. Hundreds of bottles broke as the wine flood pulsed down the cellar, and several people felt obliged to buy a litre or two as the vintage had suddenly become so rare!

Technicals
    8mm self-drilling anchors have now been generally adopted by cavers for SRT anchors. They suffer from one disadvantage - they pull out at less than 200kg. The 1989 Matienzo Expedition used Unifix In-Sit, 8mm x 55mm & 8mm x 80mm stud anchors for some rigging and 6mm x 70mm for climbing. No one felt brave enough to use 6mm x 35mm despite pull out failure exceeding the shear failure of 600kg. 8mm stud anchors are certainly a viable alternative to the self-drilling anchors, although an electric drill is necessary. Pull out and shear exceed 1200kg even when placed in the roof. Less battery power is used for drilling but the extra placement depth means they are safer in poor rock. 314 stainless steel is available for use in corrosive and wet conditions although standard zinc-coated should last for several years. They are also cheapest.
    In a couple of instances, cave passage description was spoken into a dictation machine to be transcribed later at leisure. This must be the way to gather together information from disparate groups of explorers in a large system. As usual, a BBC Master computer was used to convert survey data to x, y z coordinates and to plot line plans and elevations.
    As shown in Valline, burning wetsuits proved better than any smoke bomb in providing olfactory and visual clues to surface-underground connections.

Archaeology
    A number of caves in Matienzo have proved to be archaeological sites. Remains of many types - human, copper, bronze, stone, flint - have been found and the area is one of the best sites for Iron Age remains in Spain. Artifacts from the early Stone Age through the medieval period to the Civil War have been discovered. Finds are documented and handed over to the Museo de Prehistoria in Santander. This year, a superb stone adze from the Chalcolithic period was discovered by Lugger in a small cave below Emboscados at the northern end of the valley. The other notable discovery was the small, clay beaker found in Cueva Valline. The pot is thought to be Bronze Age.

Conclusions
    An excellent year which, once again, posed more questions and problems than it solved. There must be lim- its to the cave passage around Matienzo, but none of the major systems explored since the early 70s are finished. 1990 sees the 'official' twentieth anniversary of Matienzo Expeditions. None of these visits would have been possible without the permission of the Spanish Authorities and the goodwill and friendship of the people of Matienzo. It is unfortunate that some groups are stretching this welcome by caving without permission from the caving authorities. The summer expeditions have a caving permit for six weeks, granted annually. Other groups, unless they obtain permission from the Spaniards, are caving without a permit and could jeopardise the return of any British caving group to the area.

Acknowledgement
Thanks are due to Tony Money at Black & Decker, Blackpool; Technical Fixings Ltd., and Unifix Ltd.