Discoveries in Riano 1, Matienzo
Friday, 14 April 2006 – Friday, 21 April 2006
This was my first visit to Matienzo, and initially I felt a bit lost over where to start to try and get a feel for the area and its caves. After spending day on the surface bashing new shafts with Jim Davis, Sam Allshorn Lieberman and Paul Whindle, I was keen to get underground. So I got involved in surveying a new cave which had been explored the day before and had an undescended pitch. The cave was an opening on the track side near Riano 1, and while it did not ultimately go very far, it was apparent that there were large rifts in the hill that had not been found before. Caroline had spent the day on the surface and had found some potential new sites, and my interest in the immediate area was aroused.
Caroline and I returned the next day with the aim of photographing the new sites, and surveying Dormouse Cave, which had previously been smoke tested to a passage in Riano (from the Riano side). The description of Dormouse said it needed a hammer and bar taking to the end to enlarge the way on. Before we got into Dormouse we had taken a walk along the meadow edge and found a few more possible sites. One looked very promising, being a walk-in rift hidden in the undergrowth. We returned in caving gear to explore, but it only went a short way before getting too tight. So we started our survey of Dormouse. This was my first time on survey instruments and book, and Carolines first survey trip ever. We got some good practise surveying a few short legs up, over, under and around boulders in the entrance series before reaching a proper passage with a small stream. Unfortunately the cave gets a bit nasty beyond, and we abandoned the survey after I got myself a bit stuck with some difficult bends in the flat out crawl in the stream due to my long legs. Total surveyed length of about 18 metres!
(All the above is written up in the expedition logbook in more detail)
Speaking to Jim Davis in the bar that evening I learned a bit more Matienzo wisdom, one piece of advice being to ignore the downstream and look for upstream passages where there was a chance of breaking out into old higher level large phreatic passages. (Ironically the Cueva del Torno team returned shortly afterward having made a break through into a large, well decorated chamber via a downstream dig!). I was then directed to talk to Lank, who had been involved in the original exploration of Riano. He talked about visible high level passages not far from the entrance which nobody had climbed up into. So the next day we went to dig out the silted up entrance (Caroline Fretwell, Paul Dold, Christine and Annabelle (Danish cavers)). A good trip was had, getting to know the entrance series and nearby passages. We found some of the visible voids in the roof that Lank had told us about, but did not attempt a climb as the walls were made of mud. They looked like rock, but when you put your hand on them the crust broke and you could stick you hand into the wall several inched. Not suitable for climbing up. Looking for an easier way up, we moved on into the area I thought Lank had pointed to on the survey, only to find that there were no more voids there. So we decided to explore further into the cave. At the end of Double Barrel passage I found a low arch which the stream issued from. On the survey this was just marked as an inlet, so I pointed it out to Paul as a going lead that led off the known survey, assuming it would be flat out in water and impassable. We looked at some other nearby areas of interest, but when Paul had not returned half an hour later I thought I had better take a look.
The crawl under the arch immediately opened up into larger passage. Looking at the survey I realised this was shown as such, and the actual inlet proper was at one end of this passage (the other heading downstream as one half of Double Barrel). The inlet was actually a tight meandering rift, and after a couple of bends it pinched in so that I had to squeeze through a couple of feet off the floor where it was widest. It looked like it continued in much the Sam Allshorne way, so we decided to wait for Paul to return, and passed the time with a quick look at Cat Paw passage where we saw the very curious cat paw prints in the mud (they look just like a domestic cat has walked across an area of smooth wet mud). Paul eventually reappeared, having been away a full hour, and said the rift carried on a long way before reaching an aven where open space was visible above, but filled with hanging death boulders! He did not fancy the boulders on his own, so climbed up the aven by bridging off opposite walls, and explored an inlet passage for some way until it needed a hammer to knock off obstructions. This was supposed to be Pauls day off from digging in del Torno, and he had found more going cave!
The next day Paul was back down del Torno to push going leads in there, so I returned to Riano with Sam Allshorn Lieberman and Carmen (from the Wessex) to survey and explore the inlet. Knowing that there was open cave at the end, we surveyed from the start of the inlet, which turned out to only be really awkward for the first 50m or so. It then becomes wider, and after some more meandering turns into a narrow joint controlled passage trending in a straight line with the stream meandering from side to side at the bottom. After about 185 metres of survey, we reached the aven and boulder chamber above. The stream rift continues too tight in the floor at this point. I climbed up the aven which was quite difficult, and saw a large chamber above and across from where I was. A bold step across onto boulders enabled me to get into this space, very cautiously because the boulders hanging from the roof really did not look very unstable at all!
The ceiling of this chamber consisted of large rock pendants hanging down like giant molars (teeth). One of these had a flat underside area of about 2m x 2.5m, of clean fresh rock. The bottom 0.5m or so of its length was lying broken on the floor underneath it. Back over the stream rift we had entered via there was what appeared to be a large boulder wedged across the passage. On closer inspection it turned out not to be touching the opposite wall at all. It was only attached to one wall, and the rock had started to fracture around this join, with some pieces flaking off. Clearly it was not to be touched! Moving carefully back under the hanging death molars, a sandy slope ascended from the chamber bottom into an area of more stable looking rock. I investigated what was up this slope while Carmen and Sam Allshorn found an easier climb up from the streamway into the chamber, avoiding the worst areas of unstable boulders.
At the top of the slope the roof showed a phreatic profile of a larger diameter passage. This appeared to be choked in both directions apart from some possible holes that needed investigation. The phreatic roof also continued back across the top of the chamber, and I looked for a way up into the possible passage beyond. Crawling under a huge boulder which had once been part of the wall, I was able to climb up the back of it to the roof, where a bold traverse across the hole which was directly above the floor of the aven I had climbed from the stream let into a stooping height phreatic tunnel. This quickly became crawling height as the floor came up towards the roof, but this turned out to be a false floor. Dropping off the end of this led to a continuation of the phreatic passage which has a perfectly round roof profile and a flat floor of sand which your feet left inch deep footprints in. Classic first exploration stuff as I placed one foot after the other onto the floor leaving the first deep footprints. A few straws hanging from the roof on a bend added to the scene. Beyond these the floor came up to the ceiling again due to in fill, with only a body size tube continuing. I left this for now as I had determined there was enough passage to be worth surveying.
Back in the chamber, Carmen and Sam Allshorn had been investigating the holes at the top of the slope. At first it appeared to be a small blind chamber, but then Carmen noticed a continuation a floor level through another hole and shouted back that it was huge! Sam Allshorn and I followed into a series of larger phreatic rooms with several leads. The walls were darker rock here and covered in sparkling crystals. The ceiling looked like this was an old large phreatic tunnel about 10m in diameter. In one direction a climb up into a higher level led to a junction. The main way on was choked with sand but looked worth a dig. The other direction branched again. A steeply upward sloping passage with a calcite floor ended with a calcite blockage. The other way looped back into the passage we had entered the large chamber via. Carmen has meanwhile investigated the other main way on from the chamber and reported it was fill with sediment. Sam Allshorn checked out another obvious lead and found the Sam Allshorne. By this time it was getting late so we returned to the original chamber and surveyed up over the traverse I had explored earlier, in order to get a general trend direction for the phreatic passage in that direction.
After completing the survey of this passage, I made a quick investigation of the body sized continuation. This went for about 3m before coming out at the top of a vertical sediment bank in a chamber about 4m in diameter. A large mud funnel led to a hole in the floor which I could not see the bottom of from my position near the ceiling. There was no obvious way for me to get back up if I launched myself head first down into this chamber from the tube, so we left this an another going lead to return to. When the survey data was added to the centreline plot we confirmed this new area is in white space on the known survey, but trending parallel to the main upstream continuation of Riano towards known passages in the larger 4 valleys system. A return is planned in August 2006 to continue exploration and complete the survey.