Matienzo Caves Project 2023

News and cave exploration around Matienzo during 2023
A map with area names can be found here

Section links    • Easter  • SummerAutumn Christmas / New Year

Explorations and updates in early January are to be found in the Christmas / New Year section of the 2022 account.

January / February

   This quiet time in the caving calendar allows catching up, finishing off the old year and planning for future explorations. Phil Papard has produced a 2022 summary for the Ghar Parau Fund committee and, with Pete Smith, produced the document outlining last years finds for the Spanish authorities. The 2023 version of the "Sites to Look At" is also available. (These make good reading when viewed as a flip book through a Chrome extension - see Housekeeping below.)
   There was another flood event in mid-January where the water in La Secada rose to about 150m altitude - putting the usual Carcavuezo sinks under 10m of water and the usual cave entrance under 4m. The road was closed to ordinary traffic in both directions. This photo looking south by Sonia Ranero Alonso shows part of the flooding, with the Carcavuezo sink area and entrance off the picture to the bottom left.
   A dry afternoon in January allowed some caving. Site 0349, a small shaft below Cueva de los Emboscados (0087) was opened up enough for a "thin man" descent. At the bottom, a faint footprint was seen and it was thought that the nicely decorated chamber would be worth photographing this Easter. Quick visits were made to nearby archaeological sites 0708 and 0709. It would appear that the bone at the end of 0709 has been disturbed or broken.
   In February, a set of unexplored holes, due south and 60m above the "Vega Bar" were finally entered. Sites 1478, 1480 and 3383 turned out to be short caves before closing in. Site 1481, lower down the hillside, and previously explored in a small stream to 25m length, couldn't be found. It is likely that the entrance has been covered over.
   In February, the choke at the end of Bathtub Passage in Cueva Vallina (0733) was inspected by a Catalan team, but they thought that any dig would be a hard one. They also found extensions in Galería Pita, to be surveyed next time. A passage in the connection area where Torca Rotura (0753) joins into Vallina was also investigated, with a view to re-surveying and pushing various leads at Easter.
   The Spanish group, La Cambera, were busy exploring sites in the shared area down the southwest of Monte Llusa. Unfortunately, the shafts they found had already been documented by the MCP. (5101 = LC228, 5102, 5103, 5031 = LC233, 5035 = LC234) (Blog). Photos from Easter 2022 have been contributed by Phil Parker and Nigel Easton for sites 5035, 5060, 5102 (+ video) and 5183, all in the Cierrolinos area.
   Carlos Lamoile has contributed a few photos from a trip in Cueva Espada / Ruchana (0103)
   There are a couple of minor corrections to the Torca la Decepción (0252 / 4732) survey. Hopefully, this will be out-of-date within a couple of months!
   Pete Smith has produced a document discussing the significance of cave levels around Matienzo. Any reaction would be appreciated.
  Practical work for a new science project started in mid-February. The Speleothem Phosphate Palaeothermometer intends to provide a breakthrough in the field of temperature reconstruction by developing a new palaeothermometer using phosphate-oxygen isotopes contained within speleothems. The NERC-funded project uses Cueva-Cubío del Llanío (3234) in Riaño as the collection centre. The research team includes Peter Wynn and Ben Surridge from the Lancaster Environment Centre of Lancaster University and Andi Smith from the British Geological Survey. A short article from Peter explains the work.
  The Ghar Parau Foundation celebrated its 50th year in February by having a dinner in Tideswell, Derbyshire. Juan and Penny attended and enjoyed presentations about the Ghar Parau history and fund income and distribution. Matienzo cavers have benefited from annual grants administered through the GPF, either from the Sports Council, the Foundation for Sport and the Arts, or directly from GPF funds. The earliest record of receiving money from the GPF is for the 1979 expedition and we have received aid every year with only a couple of gaps. Although our records are not complete, it would appear that 43 years of sponsorship has brought in over £17,000. (£3.27 per cave or £17 per person or £41.80 for each kilometre of explored cave passage! Good value?)
   A MCP expeditions planning meeting was held at the YSS Headquarters, Helwith Bridge on February 18th. Over 20 people attended with about the same number sending apologies. The minutes and meeting resources can be seen here.

  Issuu, the flip book platform where all the pdfs (logbooks and scanned references) were stored, is removing free access for larger documents. So all these pdfs are now available directly from the MCP web server. Flip book functionality is available as an extension to the Chrome browser. Further details can be found here.
   What3Words is another method of locating surface positions (in a 3m square). For example, one entrance to Llanío is at or in Spanish

   Some thought is being given to adding a what3words address (in Spanish?) to each (major?) site to possibly assist any future rescue. Could this feature be useful or provide any more functionality than a Lat/Lon and / or UTM position? Any reactions would be helpful!
   Another programme which may be of use for the complete data-to-drawn-survey process is CaveRenderPro. This takes in raw data, displays it like Survex and has a complete drawing package - all in the same programme. It seems very capable and it should be possible to try it out with a new cave or two this Easter!

The list below shows links to those 19 sites which were extended or newly discovered over January and February, or which have had surveys, references or descriptions updated, photos or movie clips added, or entrances repositioned using a GPS.

Arredondo 0733 Vallina, Cueva;
Cierrolinos 5014 shaft; 5031 shaft (LC233); 5035 Llusa 3, Cueva de la (LC234); 5060 Basura, Torca de la (LC186); 5101 Cinco Cráneos, Torca de los (LC228); 5102 shaft; 5103 shaft (LC232); 5183 dig;
La Secada 0081 Carcavuezo, Cueva de; 0349 shaft; 0708 cave; 0709 cave; 4732 Decepción, Torca la (bottom entrance);
Riaño 3234 Llanío, Cueva-Cubío del;
S Vega 1478 cave; 1480 cave; 1481 cave; 3383 cave;

Juan Corrin 27/2/2023

Jan / Feb logbook

Pre-Easter Expedition

  Photos were received from Terry Whitaker, taken earlier in site 0747 at Ogarrio. Carlos Lamoille sent photos he had taken in site 0050, Torca del Serruco.
   The field above Cueva Llanío (3234) at Riaño was found with a substantial flattened pile of mixed gravel and crushed rock ready for building a honey processing plant. Only time will tell if these works will have an effect on the water monitoring project in the entrance passages directly below.
   James Carlisle has substantially re-written the description to Cueva Fresnedo 2 (0841).


    Our permit application area for 2023 is the same as in the past few years with priority searching needed in the Hazas de Cesto and Ribamontán al Monte areas as far as the N634 / A-8 motorway.

    Over 50 cavers visited Matienzo over Easter and, along with partners and children, this meant well over 60 people were visiting the area, with many camping for the first time in a few years. The weather was good with only a little rain: the dry sunny weather meant water levels were generally low and the camping field behind Bar Germán stayed in firm condition.
   During the Easter period the link between Cueva-Cubío de Llanío (3234) and Fridge Door Cave (1800) was made, bringing the length of the Four Valleys System to well over 71km.
    Forty-four new digs and caves were found and recorded. Some have been pushed, but work (pushing, digging, etc) for a number is still needed. Just over one hundred sites were visited with over 150 trips / digs made during the expedition. In total nearly 2km of new cave were fully surveyed (see table).

    The main finds this Easter were in
• Cueva Vallina (0733) where 765m of passages were added in two areas off the large passage (Sunday Stomps) from the top entrance.
• Fridge Door Cave (1800) - was linked to Cueva-Cubio del Llanio (3234) adding some 52m to the combined length
• Torca la Decepción (0252) where passages off the north part of the cave and of Shrimp Bone Inlet added over 300m to the Four Valleys System - leads remain in this area as well in the Trident Series in Cueva Hoyuca (0107) which was briefly looked at.
• El Cubillón (2538)
• Villanueva resurgence (5023)
• Torca del Dron (4669)
• A number of small old caves along the north of the N634 road at Beranga including 80m in Bus Stop Cave (2908).

Research Work
    After the gap caused by Covid 19, the bat survey work being undertaken by Jess and Martyn resumed with five species of bats identified in 13 active sites. A separate report on their work will be uploaded later.
    The work of Dr Peter Wynn of Lancaster University resumed in Cueva-Cubío del Llanío (3234). This study is looking at phosphate levels in cave seepage water (i.e., from stal, etc) and 150 litres of sample water were collected for transport back to Lancaster.
    No water tracing took place partly due to the dry weather conditions; we hope to resume this work later in the year.

S O U T H E R N   S E C T O R

Cueva Vallina (0733)
   The work in the area around Zona Blanca and Swirl Chamber continued to tie up some loose ends and confirm links. Exploration in this section of the cave is now complete.
    At the end of the Sunday Stomps - the large passage from the top entrance - the climb marked "high level" was found to have been bolted but stopped just short of where a continuation could be seen. Over three trips more than 700m of mainly large passage (Top Level Continuation) was found with some leads and digs left to be checked out.
    Nearer the entrance, a side passage off the Sunday Stomps was found. This consisted of 42m of passage with numerous gypsum flowers on the walls, and so it was named Gypsum Paradise.
    Jim Lister and Mark Smith dived upstream sump 9 to find it to be only 7m long to 120m of low then flat-out passage that is still going, but small. It has yet to be surveyed.

South Vega
   Thirty four caves were visited in this area, including 14 sites inspected as part of the Bat Project - most had active bat occupation. There were several trips into Comellantes (0040) including a Citizen Science meet, leading people (including children) in a search for bats. This proved very successful and popular with about 12 Schreiber's bent winged bats, 6 lesser horseshoe bats and 1 greater horseshoe bat located and identified.
    In Torca de Azpilicueta (0333), an attempt was made to survey the 87 Series that goes off next to the rift pitch prior to the big pitch. A start was made rigging the traverse into the series, but the passages and walls were so muddy and flaky that rigging became too problematic. It was decided the best option would be to rig and survey site 0675 that intersects this series and survey from that end.
    At Torca del Dron (4669), nearly 100m of new cave was surveyed in the His & Hers area. The "water splash" pitch was dropped followed by two more pitches then a muddy crawl to two further pitches that both entered the same chamber where there was no way on. A small slit in the chamber probably takes any water and only a slight draught was noted on a cool day. There are still a number of other leads at this site to investigate.
    Cave 3355 was pushed and surveyed to 43m. A 21m-long new site (5321) on the edge of a wood, covered in cut branches, was 10m deep to a small chamber with a short passage opening up to a clean washed aven.
    Work to tidy up the documentation of known sites included taking entrance photos and checking the grid reference of seven sites with GPS. Two small shafts were found as possible digging sites and two sites, 1481 and 2564, could not be found.

   An undescended shaft (3254) was pushed and surveyed over three trips to a depth of 89m and surveyed length of 105m. The base needs capping to make progress although it may be possible to swing into a pitch higher up. It needs checking out for draughts in hot weather to identify best prospects.
    Another shaft (5209) high on the hill was dropped into a rift for 15m to where capping is required. This also needs checking for inward draughts in hot weather. Another cave (1149) named "Oh no, I ordered a Heineken!" was found, like the beer, to offer a lot but was not impressive: a descending twin-entrance tunnel for 20m with no prospects.
    Two new shafts were found (5329 & 5330) which dropped to chokes at 5m and 25m respectively and shaft 2796 was pushed down a 30m pitch to a flat floor with no way on.
    A new dig (5331) was excavated to 1.6m with more work required. This site needs checking for draught in hot weather as, when found on a cool day, the draught was only slight. Shaft 5324 was found but not descended. This needs checking out as it may be site 1153 if the location is wrong. A depression (5322) was found but not fully checked out.
    As part of the Bat Project, Cueva del Arenal (0035) was found to have active bat presence in the right and main central cave past the pool of water.

Cubija valley and El Naso
   At the strongly draughting dig 0813, capping continued in the downward rift. The site is now best tackled by three people to make spoil removal efficient. Site 0670 was repositioned with a correct GPS reading and new photos taken. This site is a shaft on the north end of a large wooded shakehole under a 2m cliff. The shaft continues as a too narrow rift that requires moonmilk removing and possible capping to progress. It's worth a dig and check in hot weather for draughts.
    Two new sites were located - an undescended shaft (5323) about 5m deep and a worthwhile dig (5325) where stones fall a few metres. Two sites were checked out to confirm grid references, site 1961 was draughting in on a warm day and site 0525 near the valley road was checked and thought to be worth a dig.    In Torca del Mostajo (0071) there was a photo trip along the upper level.
    In Cueva del Molino (Agua) (0059) possible bats were seen, but too high up to confirm - viewing needs a very strong light! An ecological meet, well attended by cavers from across Cantabria, was held by the Cantabrian Speleological Federation looking at the different fauna in the various cave environments as you move from the entrance to the inner area with no daylight.
    At Bosmartín, cave 1892 had new photos taken around the entrance.

El Sedo and Ozana
   As part of the Bat Project, Cueva del Concebo (0012) and Cueva de Cuatribu (0013) were found to have active bat presence with four species identified in the latter cave. A photographic trip was made in Sima-Cueva del Risco (0025) to the Where are the Spiders? area as well as a families trip to Cueva de Jivero 2 (0017). The resurgence 2801 at El Camino was checked to see if access could be gained on the upstream side in the field. Water could not be heard but it is worth another listen in wet weather.

N O R T H - E A S T   S E C T O R   I N C L U D I N G   T H E   F O U R   V A L L E Y S   S Y S T E M

La Secada
   Here, the main work was in Torca la Decepción (4732) where, over six trips, the rigging bolts were replaced with stainless captive type as the previous bolts had rusted. There was a problem installing the new bolts which was later identified as a drill bit drilling undersized holes. (With through bolts, if the wedge section at the base does not easily go into the hole, then the hole is undersize, as it should only take light taps with the hammer to seat the bolt in the hole.)
    The main work was finding a bypass from the Griffins Club area to Hideous Hog as well as some side passages in the same area. Climbs in the main passage to possible higher levels need bolting.
    This entrance was then used to check for leads in Shrimp Bone Inlet, Rocky Horror and the Trident Series in Cueva Hoyuca (0107). Due to lack of caving days, the main surveying work was carried out in Shrimp Bone Inlet, where over 200m of passages were found. The route into the Trident Series was eventually found, after realising that access requires a climb up the south wall from near the start of Rocky Horror to an old "campsite" chamber. A number of leads in Trident were noted and need pushing and surveying in the summer. The north wall at the end of Rocky Horror, where a possible passage is shown on the original survey, could not be reached due to high water levels and still needs checking out. The leads in Torca la Decepción to the south of Grand Slam pitch were not looked at.
    Three digs were worked on. At Bingo (0880) solo digging continued and it was noted the shoring is now poor and needs work to make safe. A number of spoil bags remain to be lifted out of the dig. Nearby site 0874 was inspected with an endoscope which showed that a lot of capping will be needed, but worth at least a day's work. At Socks (1017) the pitch was capped to make it big enough for normal sized people and digging continued - but a lot more is needed.
    Two sites at Cruz Llorada were found: shaft 5326 is undescended under a pallet and tyres, and dig 5327 is a 0.6m-wide sandy dig.
    One of the more improbable caves was found adjacent to the main road past the river bridge on the way to the Bar la Panaderia. What looked just like an outlet for a field drain aroused enough interest for Alex to get a light and explore in his normal clothes, finding it was in fact a cave (called Vaca-Cud, site 5334). He returned with a team and surveyed the 14m-long cave. It has limited prospects, but does show that the limestone does extend to the valley floor in this area.

   Passages off the Big Bang Burger Bar area of Cueva Llueva (0114) that were first found in 2014 were examined and a number of leads pushed. A climb bolted to within about 15m of the top ran out of rope so still needs to be completed. A number of small side passages and digs were identified but more work is required.
    In the Secadura resurgence area, site 0154 - Cueva 77A - was looked at with a view to diving. Two possible prospects were noted.

   The main work was in Cueva-Cubío de Llanío (3234) where, over two trips, the dig at the end of High Pulse was pushed through into Fridge Door Cave (1800) and made large enough for normal size people. This connection extended the Four Valleys System to well over 71km. Using this route - instead of diving - the traverse above "Jaws" pitch was pushed. It closed down, but a passage below continues small, needing a lump hammer after 4m to knock off projections. A traverse line above sump 2 was installed to make access to sump 3 easier and safer. A large void was noted past the boulder choke in this area that needs bolting to access. Leads noted on the trip are shown on the map in the Easter logbook, page 49.
    A trip was made to recover 150 litres of sample water for a phosphate research project run by Dr Peter Wynn. The route to SubPhone Entrance (4536) was found to be very overgrown. This was cleared but it is likely more work will be needed in the summer if this entrance is used.
   The possible link from Fridge Door Cave to Cueva de la Espada (0103) was checked out from the downstream Espada end. There are a few possibilities and it may require digging from both ends to get the link. It would be useful to put some dye into Fridge Door Cave so it can be seen which stream in Espada is the outlet.
    At Cueva Sin Sendero (5227) digging and capping over two trips found a way on with a further 3m of passage. More work is now needed.

N O R T H W E S T   S E C T O R

   A lot of effort was put into this area with some 14 new sites found. A shaft 5328 was found a little to the east of Torca la Vaca (2889) dropping 8m and then a further 2m over farm rubbish with no way on. Digging took place at 3720 to where a boulder needs removing but, as it may hold up the roof, an alternative to capping is needed. The main entrance to shaft 3736 has been bulldozed over and a new GPS of an alternative entrance taken.
    Four new digs were found. The first, 5341, is 5m deep with a slight draught to where a boulder stops progress; 5342 is a small draughting shaft that needs capping - it may connect past the end of site 3823; site 5343 is a 2m collapse that leads to a drop that needs capping, and 5344 is a large shakehole with three draughting holes. The one on the south was dug and a boulder removed. This accessed a 10m long cave with a rift in sandstone and fractured limestone, with the way on down a 3-4m deep hole that needs more work.
    Digging was carried out at 3048. The nearby sites, 3471 and 3472, were found with a good draught - the latter being a good digging prospect.
    Two more new sites were found in the vicinity. The first is a narrow draughting slot (5350) that was opened up as a 5m ladder pitch into 4m of passage to a back wall with a side passage. This has an overall length of 9m and work is now needed on a tight section between spires / pillars. There is a good draught and stones rattle down about 7m. The second is a 2m wide undercut (5351) about 1m deep with a strongly draughting tube on the left side.
    Another new draughting entrance in long grass and bracken was noted, site 5352. This is in the same shakehole as 4182 and 3470 and is a 4m slide down into a boulder ruckle with 5m of passage and draught coming up a narrow slot from a larger space below. Near to this site, in a rock-walled, bramble-filled shakehole, a small squarish entrance (5355) was found. This is 1.5m long with small, draughting opening at the back.
    Further north is a gully with three new sites. 5359 is a square recess that seems blind. Site 5360 is a small draughting slot into a curving rift that was dug down a narrow rift for 2m. This reached a level with a small shaft that was too tight after 2m with no echo or draught. A small person is needed to progress. The most important of the three appears to be 5353, a duck-in entrance to 5m of walking passage. A 2m climb down fluted pillars and calcite reaches a dig with a good draught where stones rattled down for several metres. This dig was worked on over three days to get 5m down to the capping spoil heap. A narrow rift heads back towards the entrance and a narrow downward tube that appears to break out a metre below where stones bounce away. More work is needed to progress.
    Also found in same general area was a cliff face that yielded three entrances / rifts fitted with small dams for water collection: 5356 is probably enterable for several metres; 5357 needs work to enter, and a dig 5358 that is still to be fully looked at.

   Bus Stop Shelter Cave (2908) was surveyed to 35m with limited prospects. Fat Boy GT (0613) was checked as part of the Bat Project and found to have bats present. The end of the cave was looked at for a digging prospect. This is possible, but will need scaffolding to secure boulders - a major dig.
    The entrance to Sumidero de Cobadal (1930) was found to be passable and the route to the boulder choke above Wessex Inlet was checked out. Digging high up in this strongly draughting choke has much potential.

San Antonio
   The complex shaft system El Suto (3450) was visited on five occasions with a some resurveying of the site as well as exploring new sections, adding 77m to the total surveyed length. No way on was found at bottom of left-hand route but a traverse over the top of the big pitch is a possible way on. Some re-bolting is needed at the site.
    Cueva CTB (3012) was dug on two occasions reaching a tight bend where a low arch immediately followed by a mini-aven was seen to carry on low - it needs someone small to push. Cave 4401 was pushed 8m along a crawl to where it continues very wet. A 12m passage was found at the lower end of the depression.

   Cave 4513 was pushed to 5m. The dig 5222 was worked on but it is a poor prospect and the site closed up.

N O R T H   S E C T O R

   Cave 4132 was dug to remove a boulder and was found to be too tight after 17m and 9m depth. Shaft 4242 was dug to 5m depth and length. A shaft 5347 was found to be 3m deep but would be a major dig. Another shaft 5348 was choked with rubbish at 2.5m and so is a poor prospect.

Hazas de Cesto
   Cueva del Palomas (4004) in Riolastras was checked as part of the Bat Project and groups of greater and lesser horseshoe bats identified. At El Rincón, the resurgence 4867 was capped to allow easier access. The site now needs a thin person team to push and survey.

Five small caves were found on the south side of the N634: most seemed to be old, abandoned caves now truncated by the road cuttings. The most extensive was Bus Stop Cave (5336) that was surveyed to 80m passing under the railway. Another small cave, 5337, was partly explored and more work is needed.
    Further to the east three caves in the road cutting were explored, two requiring Juan's extension ladders to reach. The most hazardous part of the exploration was getting across the N634 with the ladder. Cave 5338 is 5m up the rock face and the 9m cave is an excavated crawl to very small hole down with one wall of what appears to be calcited gravel and so may have been part of a very old, larger system. There is a side passage to a choke that may have connected to cave 5339 at the base of the rock face. That hole is an 8m long, 3m deep, blind cave. A little to the west is another small cave (5340) high up. This is a slot in solid limestone that turns to the right to a tight rift needing a very thin person and / or capping. A hot weather draught check is required: prospects are very low if there is no draught.

Ribamontán al Monte
   This area is shared with the Club Montaña y Espeleología La Cambera.
   At the Villanueva resurgence (5023) Jim and Mark dived and pushed sump 4 and surveyed finds to add 133m to the cave - more work is needed to push this system. Covachera (5036) was dug, but first a badger's den needed to be cleared. Given it was either still active or very recent, its removal required use of masks and disinfectant. Assuming the badger does not return, more digging is required.
    Three other sites were looked at in the Villanueva area: cave 5191 was pushed 5m to a tiny sump and a sink 5345 and shakehole / collapse were located, but neither dug. At the cave 5192, a descending hole was looked at near the section "b" on the survey but found to be too tight with no draught.

   The following was carried out with the agreement of the club G.E. Pistruellos.
    At El Cubillón, 2538, five trips were made to add detail to the survey, complete work in a number of unsurveyed sections and push and survey inlets down the second pitch. An undescended pitch was found near the end of the system that appeared to go to a streamway - more work in this area is needed. In preparation for diving in the summer, Bassenthwaite Water sump was lowered to make it a duck. A sandbag dam was installed to try to prevent more gravel being washed into the sump.
    It was found possible to drive a vehicle to within 150m of the sink (4955), high up on the hill at Las Piqueras. This site is one that should be dye tested.

Easter Expedition account by Phil Papard, 9th June 2023

New surveys and survey updates
0107 Hoyuca (4VS); Trident and Shrimp Bone sketches archived (batches 23-01 - 23-04) (PF)
0252 Decepción (4VS) published (PP)
0333 Azpilicueta sketch (old.29 > 620) archived
0733 Vallina Top Level Continuation on 0733 page. Complete revision. (JC)
1149 cave published (MT & FMcD)
1800 Fridge Door (4VS) published (JC)
2538 Cubillón published (SC & DA)
2908 Bus Stop Shelter published (JC)
3234 Llanío (4VS) published (JC)
3254 shaft published (MT & FMcD)
3450 El Suto published (JC)
4669 Drone Pot published (JC)
5023 Villanueva published (JC)
5209 shaft published plan and elevation (JC)
5321 shaft published plan and elevation (JC)
5334 Vaca-Cud published (JC)
5336 Bus Stop Cave published (PP)
5338 cave published (PP)
5340 cave published (PP)

The list below shows links to those 137 sites which were extended or newly discovered around the Easter 2023 period, or which have had surveys, references or descriptions updated, photos or movie clips added, or entrances repositioned using a GPS.

Arredondo 0733 Vallina, Cueva;
Beranga 5336 Bus Stop Cave; 5337 cave; 5338 cave; 5339 cave; 5340 cave;
Bosmartín 1892 cave;
Cobadal 0613 Torcida, Cueva de; 1930 Cobadal, Sumidero de; 2908 Bus Stop Shelter hole;
Cruz Llorada 5326 shaft; 5327 dig;
Cubija 0071 Mostajo, Torca del; 0525 cave; 0670 shaft; 0813 dig; 1961 dig; 5325 dig;
El Camino 2801 resurgence; 5334 Vaca-Cud, Cueva de;
El Naso 0059 Molino, Cueva del; 0248 Cuevona, La; 5323 shaft;
El Rincón 4867 resurgence;
El Sedo 0025 Risco, Sima-Cueva del;
Fresnedo 0841 Fresnedo 2, Cueva;
Garzón 4132 cave; 4242 shaft; 5347 shaft; 5348 shaft;
Hornedo 3048 dig; 3174 Pooch Cave; 3406 shaft; 3470 shaft; 3471 dig; 3472 dig; 3720 dig; 3736 shaft; 3923 shaft; 4182 Cuba Libre, Cueva; 5328 shaft; 5341 dig; 5342 shaft; 5343 collapse; 5344 digs; 5350 dig; 5351 cave; 5352 cave; 5353 cave; 5354 rift; 5355 cave; 5356 resurgence; 5357 resurgence; 5358 resurgence; 5359 cave; 5360 shaft;
La Estrada (Anero) 5192 cave;
La Rasa 3255 cave; 5329 shaft;
La Secada 0084 Cosas, Cueva las; 0874 dig; 0880 Bingo; 1017 Socks; 4732 Decepción, Torca la (bottom entrance);
Las Piqueras 4955 sink;
Llueva 0114 Llueva, Cueva;
Moncobe 2538 Cubillón, El;
N Vega 0423 Barandas, Cueva de;
Navajeda 4513 cave; 5222 dig;
Ozana 0012 Concebo, Cueva del; 0013 Cuatribú, Cueva de; 0017 Jivero 2, Cueva de;
Riaño 0103 Espada, Cueva de la; 0107 Hoyuca, Cueva; 1800 Fridge Door Cave; 3026 dig; 3234 Llanío, Cueva-Cubío del; 4536 Sub-phone entrance; 5227 Sin Sendero, Cueva;
Riolastras 4004 Palomas, Cueva de las;
Riva 0747 cave;
S Vega 0040 Comellantes, Cueva del; 0042 Cefrales, Cueva de los; 0048 Reñada, Cueva-Cubío de la; 0050 Serruco, Torca del; 0177 Cuevuca, La; 0263 cave; 0267 Overhang Cave; 0333 Azpilicueta, Torca de; 0477 cave; 1035 cave; 1037 cave; 1042 cave; 1481 cave; 1510 cave; 1537 cave; 1538 cave; 1539 cave; 1710 dig; 1877 shaft; 1878 shaft; 2564 shaft; 2587 Walled Cave; 2682 cave; 3355 cave; 3437 cave; 4669 Dron, Torca del; 5199 rift; 5208 cave (side entrance to Cuevuca); 5321 shaft; 5332 shaft; 5333 shaft;
San Antonio 3011 shaft; 3012 CTB, Cueva; 3450 El Suto, Torca; 4401 cave; 5335 hole; 5349 cave;
Secadura 0154 77A, Cueva;
Seldesuto 0035 Arenal, Cueva del; 0056 Salamandra, Torca de la; 0491 shaft; 0546 shaft; 1149 cave; 1153 cave; 2796 shaft; 3254 shaft; 5209 shaft; 5322 depression; 5324 shaft; 5330 shaft; 5331 dig;
Villanueva 5036 Covachera, Cueva de; 5191 cave; 5345 sink; 5346 collapse;

Easter 2023 logbook


   About 46 cavers visited Matienzo, spread over five weeks. The weather was mixed with quite a few days of drizzle and light rain, but generally water levels were low. As was the case last year, a number of cavers could only spend a short time in Matienzo so, at any one time, about 25 cavers were present. It was particularly good to see some new and young cavers come to Matienzo for the first time including a group from Aberystwyth University.
   This summer was dominated by a large number of mainly smaller finds but still adding up to over two kilometres of new cave. Twenty six new digs and caves were found and recorded. Some have been pushed but work (pushing, digging etc) for a number is still needed. Some 87 sites were visited, and nearly 170 trips made during the expedition.
   The most important finds were in the Four Valley System in two areas, Riaño and Matienzo. At Fridge Door Cave (1800) a new entrance was opened up (Boob Tube, site 5000) helping further exploration. With a new cave (Vaca Bypass, site 5368) pushed and linked in at the start of sump 2, together over 900m was added to the system. When this is added to some further work in Torca la Decepción (0252 / 4732) this brings the Four Valley System up to over 72.68 km long.
    Elsewhere, high up at Alisas in the Trillos area, a number of new sites were found including Tomb of the Oil King (5369). This currently stands at over 300m long and nearly 80m deep with ongoing leads.
    Work finally started on stabilising the entrance to Giant Panda Entrance (2691) with a large tube fitted in the entrance drop. However, work is still needed inside to stabilise and make safe the top of the first pitch.

S O U T H E R N   S E C T O R

   Work continued at Cueva Vallina (0733) in the high level at the end of Sunday Stomps that was found at Easter with one passage going back above the Sunday Stomps before connecting back into the main passage. More climbing is needed in this area and it is still to be surveyed and fully pushed. The Catalan cavers organised by Espeleo Club Tortosa undertook pushing and bolt climbing work in Vallina II and found some high level passages, but the finds are still to be fully surveyed. The details of the work undertaken by the group is not reported here but will be reported on the website when available.

South Vega
   The Matienzo Bats in Caves Project continued with a number of sites being monitored including Cueva del Comellantes (0040), and Cueva-Cubio de la Reñada, with a number found in residence. In Reñada (0048), some photographic and familiarisation trips took place but no re-surveying or pushing occurred.
    A significant development was at Tablons (0242) where a comprehensive check for where the main draught comes from was made and a rift passage was pushed in the final chamber to two strongly draughting leads that need some digging work. The rift passage is tight and may need work to make it bigger to allow digging work in this key site.
   At Volcano Cave (1391) the dig in the final chamber was checked out. This "dig" had collapsed somewhat since it was last checked out over 10 years ago and to make progress, shoring and significant digging is needed, probably over a number of days. However, it is a another key site due to its strong draught and, as it lies between Reñada and Vallina, it will remain on our "to do" list.
   Elsewhere on South Vega the shaft 2081 was descended to 5.7m but found choked and the shaft 3762 was capped open but again found choked with no real prospect. Also cave 2083 was checked out but considered as having no pushing/digging prospect.

   Over seven trips in the entrance series in Torcón de la Calleja Rebollo (0258) were checked out for leads that appeared on the survey, and about 300m of previously unsurveyed passages were surveyed. This area has now been well checked out and future prospects are further into and at the end of the cave. The cave 1312 was entered after the dead cow had sufficiently decomposed but the cave closed down after 8m in small cracks. Shaft 2102 was checked and found to be well covered with limestone rocks. As it was late in the day, these were not disturbed and a return visit will be made to push the site. What was thought to be a new site was noted but on descending it was found to be Cueva del Humo (0045) and a corrected GPS was taken.

Trillos (Alisas area)
    An area and depression below the viewpoint at Alisas was examined and ten new sites were found and pushed as well as checking two known sites. The most extensive was called Tomb of the Oil King (5369) at over 300m long and 80m in vertical extent. This site is quite complicated with a number of loose and dangerous boulder areas. Work is now needed to stabilise some of the boulders to allow safer access and allow pushing at the bottom. This site is in an important area with no known cave systems within half a kilometre.
   Of the other sites found, cave 5372 was pushed to a tiny streamway with no way on and surveyed to 35m; cave 5370 was surveyed to 15m to a chamber and small sink and has bats present; cave 5371, surveyed to 20m, was pushed to a pitch head but soft rock made bolt placement difficult; cave 5374 was pushed to boulders blocking access to a pitch and so needs work to gain access. The other five new sites are less promising although a resurgence (5375) does draught well and so is worth a further look. Shaft 0539 was dropped down 19m to a choked floor with a very small sink in one corner. A dig 4082 was found to be draughting in and is worth some work. Near a barn, what looks like a capped shaft was found (5383). This will need opening up and made stock proof at a future visit.

Cubija and North Vega
   The strongly draughting dig 0813, next to the road that climbs out of the valley, was dug on a number of occasions. Good progress was made and this is a long-term promising dig. A new cave, 5384, above a pylon, is a steep scramble down to a restriction then a 1.5m climb down to a chamber with a mud floor and a 6m aven. Shaft 0670 was dug but more work is needed. Cueva de Barandas (0423) was checked for bats and two skeletons were found.
    Near Cueva del Molino (0059) a new site Cueva Dana (5387) was found by Johnny Latimer's neighbour's dog Dana and was dug down 3m to a tight section. Beyond is some boulder fill that would be an easy dig. The site draughts strongly.

El Sedo, La Colina, Cubilla and Ozana
    On Mullir the shaft 1451 was pushed down 5m to where a tight slot stopped progress. It now needs capping or hammering to continue. A chamber can be seen below but no draught was felt. At Ozana, cave 3884 was checked and may be worth a further look or dig. There was nothing found in the surrounding area.
    Cueva de Tiva (0026) was checked for draughts at a blockage. A draught was found from boulders high up and another low down on the left with a 10m difference in vertical height between them.

T H E   N O R T H - E A S T   S E C T O R   including the   F O U R   V A L L E Y S   S Y S T E M

La Secada
   Torca la Decepción (0252/4732) saw some ten visits mainly to check out Rocky Horror and Trident Passages in Cueva Hoyuca (0107) for possible leads, as well as resurvey of Rocky Horror to Duckham's Sump area where some 1.235km of resurvey were completed. In Torca la Decepción, an inlet off the east of Vienna Coup was pushed and surveyed for 142m to where it closed down. A number of climbs and possible digs were looked at in Trident as well as checking out the routes beyond Duckham's Sump. The far NE end of Rocky Horror, where the original surveyors have drawn a possible passage continuation (dotted line), is still to be examined. This may be important as the extensions in Cueva Lueva (0114) suggest this possibility may lead to higher level passages.
   Seven new sites were found and examined. Shaft 5364 was partly blocked by a tree trunk 3m down, where two further rifts can be seen dropping 3.5 m and 4.5m. Removal of the tree trunk is needed to access these rifts. Hollyoak Shaft (5363) was 3m deep to a choke with no real prospects. Shaft 5364 was choked 1m down, again with no prospects. In addition, four other sites were identified (5365, 5366, 5379 & 5380) but not dug.
   Elsewhere 16 known sites in La Secada were visited. At Cueva del Anío (0151) a tight rift not on the survey was found and this was pushed and the cave surveyed to 41m. Capping will be needed to make more progress.
   The river around the sinks at Carcavuezo have recently been cleared of debris by the local authority with the aim of reducing flooding. This work includes the overflow channel from the sinks to near the entrance to Cueva de Carcavuezo (0081 360° photos and videos are available from the 0081 page). The entrance is blocked by logs but it looks likely that it should be fairly easy to open up an alternative entrance below the end of the overflow channel. In the past, an entrance in this area had been found (3895) but subsequently blocked by flood debris.    Site 2770 was dug to 9m long but still needs more work. Extensive digging work was carried out at Apprentice Cave (2108) but it is thought that further digging work is not warranted, as prospects look poor. The nearby dig 2101 that strongly draughts - and looks a much better prospect - was worked on three occasions and progressed 5m to where a lot more rock debris needs to be removed.
    Four sites were checked for digging prospects (1505, 2752, 3054 & 3064) but none found. At La Cuvía (0086) the end was pushed until it bcame too tight. A lot of work would be needed here to progress.
   Two sites (0707, 1222) could not be found, probably due to the amount of undergrowth, but the recorded location may be an issue. Five other sites were checked for location and found (1505, 2109, 4179, 4393 & 4532). It was noted that none of these sites had a draught on the day. The yearly photo session in Cueva las Cosas (0084) was held.

   Site 2522, that should link into Cueva del Torno (2366), was dug at the bottom of the entrance shaft. It was found to need shoring to protect the digger if more work takes place. The draughting dig (2414) below the east side of the road to Solórzano was dug on two occasions and more work is needed. Shaft 2662 could not be found - it looks like it may have been filled in.

   At Fridge Door Cave (1800), the point close to the surface (Stairway to Heaven) was accessed by a team via Cueva-Cubío del Llanío (3234) and a surface team at Ron Taylor's SubPhones location point. The coordinated teams used radios, and a 1m drill bit drilled through a possible old entrance below a small rock outcrop. The underground team clearly heard the drilling and, with some digging work, located the end of the drill. With excavations at the surface and underground lasting about an hour, the underground team were able to exit and make the first through trip. The new entrance, now called Boob Tube (5000), was later stabilised with a drainage tube fitted into the opening and an unlocked lid fitted to prevent goats etc from getting in. The tube is a bit narrow and a foot-push step has been placed in the roof to provide an easier exit.
   Using the Boob Tube entrance, nearly half a kilometre of new passage was explored and surveyed heading north and east, and a new sump 4 found. The dry route to this sump requires SRT or ladders as you need to climb up to higher levels and then drop down to the sump. The route through sump 3 was checked out by Jim Lister but it was found to not be an easy option and the dry route is probably the best for pushing in 2024.
   One unexpected problem with the Boob Tube entrance is the strong cold draught it emits. It seems that cows in hot weather like this and, on one trip by a team who had not been there before, the entrance was hidden due to a cow and calf sitting on the hole! To avoid the animals, the team decided to look above the field for prospects and found a new site Vaca Bypass (5368).
    Over 5 trips this cave was pushed down a number of pitches and passages that required some traversing. Finally, an 8m pitch was dropped to a sump with a diving line belayed off, later identified as the start of Sump 2 in Fridge Door Cave, thus linking into the Four Valleys System as well as giving yet another entrance, the 18th. This new find was surveyed to just over 400m.
   The Giant Panda Entrance (2691) in Riaño had been reported to be in a dangerous state. Over four trips the majority of the scaffold and wood shoring was removed and, after trimming some rock and boulders in the walls, a large diameter tube (the same type as at SubPhone Entrance) was placed in the hole down to about 1.5m from the base with an opening in the side of the tube for access. A "lid" of close-fitting scaffold tubes protects the top and a aluminium ladder was fixed in place for the short climb down. There had been some collapse of loose spoil: this was later removed and the walls at the base of the tube blocked up with concrete blocks and foam so further collapse would not fall down and block the base. This work should make the surface entrance shaft safe, but more work is needed at the top of the first underground pitch just past the short smaller tube placed in the cave a few years ago. Some final work is needed on this entrance and this will be completed in October 2023.

N O R T H W E S T   S E C T O R   ( S A N   A N T O N I O ,   H O R N E D O ,   C O M P O S D E L A N T E ,   etc )

San Antonio
  At Fuente Aguanaz (0713), preparations were made with gear including a short ladder taken in to just prior to sump 1. Here, a drop down in full diving gear had proved awkward. On the trip to take gear through sump 1 to Sarah Jean Inlet, the line broke twice and had to be repaired and later replaced with thicker line. The opportunity was taken to check if there were any inlets in sump 1 that had been missed as the passage and water beyond seemed to be smaller. However, no inlets were found. The pushing trip by Mark Smith and Jim Lister to the end of Sarah Jean Inlet past sump 5b checked ongoing leads, but none were found going or worth continuing. The team notice green pollution coming in and saw it went to the downstream end of Sump 5b.  A survey was completed of small finds.
    The main lead to push in this area is GH Aven as other leads need too much work in this remote location.

   Two sites were checked out. At a shaft (3684) a climb of 2m met a slope down to a chamber 3m across with a pitch at its base. To progress it needs a crowbar to move three rocks to get down the pitch of about 6m. A passage can be seen at the bottom – it looks good. A chamber is visible at the draughting cave 3685, but it needs capping to make progress.

La Gatuna
  Site 3376 was reported to have collapsed further - or what was seen may be a new site. This needs to be investigated.

N O R T H   S E C T O R

Hazas de Cesto
    Eight sites (four new) were examined. The majority were in an area of heavily eroded limestone with a number of gulleys and drops mainly covered by trees. The caves here are clearly fragments of very old systems. Cueva la Centinela (4941) was dug open to a walking passage then pushed beyond a tight section to end after about a further 10m to give a 44m long cave. Gordon worked on excavating a crawl just past this new passage. A dig in an adjacent blocked passage in this site was dug but progress is slow and prospects seem low. Nearby Arch Cave 2 (5361) was explored down a 30 degree slope into a medium-sized chamber giving a cave length of 18m.
   On the east side of the road, a small ravine runs off and, after a few metres, a cave on the north wall, Ravine Cave (5381), was found. This went some 5m to a tight section on a bend and needs a very thin person or capping to continue. There is a small draught. Just to the south, another cave was discovered on the west wall that ran through the limestone to an exit with two further openings to the surface (Four Entrance Cave, 5382). This was surveyed as a 17m long walking passage. Just to the south of this cave is a small dig at the bottom of a 2.5m slope - but the prospects are low, with no draught. Other sites checked out were cave 4933 which had no draught and would need a lot of work to progress (a poor prospect); sink/cave 4936 that was pushed for 2m where a roof fall stopped any progress, and cave 3935 could not be found at its GPS location.

El Rincón
   The resurgence 4867 was pushed and surveyed following lunch at the nearby El Rincón Bar. It had been assumed only a few tens of metres would need surveying, but the team found 155m of passage, some quite small and sharp. A possible sump was found but the nature of the passage will make access a little awkward.  It is probably first worth a look with a small diving kit, i. e. 1.5lt cylinder and mask to check it is a sump that may go. There is some potential in the hills behind this resurgence for more extensive cave.

  The resurgence (4937) was checked out. This was first explored in 1977 and documented with a sketch in the logbook. The presumed entrance was found to be a dark rock face with water coming over from above. Further up the hill, a draughting hole with an old tree trunk stuck in (we assum to prevent animals falling in) was found. On looking carefully at the old sketch it seems that this is the hole found and explored in 1977. This is a site that needs looking at again but it requires a chainsaw to gain access and then some sort of stock proof cover following exploration.
   Along the main road to the west, the draughting Bus Stop Cave (5336) was dug on two occasions, but digging is now more difficult due to calcite in the fill material.

Ribamontán al Monte
   Part of this municipality is shared with the Club Montaña y Espeleología La Cambera. When we get reports or see blogs, their sites are given a number and put on our mapping system, so anybody working in this area has the relevant information to avoid duplication of work.

    The Cambera club reported that the cave Cueva del Gusnardo (5150, their number LC226) has been pushed to 455m long and 135m deep.

    Cueva de Covachera (5036) was dug on two occasions extending this cave to 15m. Now, due to bends in the passage, about three people are needed for future digging. There is still a good draught at the end.

Moncobe  (in agreement with the club G.E. Pistruellos.)
   At El Cubillón (2538) a pushing trip with a number of objectives was made - first to check Hilary Step. Access was OK but, after a couple of decorated chambers, the way on was choked with calcite. The second objective was to drop a new pitch so Mark Smith could dive the sump. However, after the duck leading to the sump no belay for the line could be found and an undercut in nil vis was too much of a risk to continue. Finally, at the bottom of the new pitch, a climb up was made into a series of chambers/passages that reached a deep rift (about 40m) with the sound of a stream below. There was some red/white marker tape on the floor of the passages but it looks like it had fallen from above as there were no foot prints. This find is still to be surveyed.
   The aim for one day was to locate cave 3754 and then from this find a nearby dig that needed looking at as it sits between El Cubillón (2538) and Fuente Aguanaz (0713). However, excessive vegetation covered the area and, despite bushwacking, the site could not be found.

Summer Expedition account by Phil Papard, 31st August 2023

New surveys and survey updates (in hand)
Description Drawn survey Survex centre line
0107 Hoyuca (resurveys) Duckham's to RH; Judgement to Duckham's (SC & DA) 0107
0151 Anío in hand (DA) 0151
0252 Decepción (4VS) published (PP) 0252
0258 Toad published (JC) 0258
0539 shaft in hand (JE & MG) 0539
0713 Aguanaz in hand (PP) 0713
1312 cave in hand (JE & MG) 1312
1391 Volcano resurvey centre line (SC & DA) 1391
1800 Fridge Door (4VS); 5000; 5368 published (JC) 1800
2082 shaft in hand (SC & DA) 2082
3762 shaft in hand (SC) 3762
4867 resurgence in hand (SC) 4867
4941 Centinela published (PP) 4941
5026 rift sketch published (PP) -
5361 Arch 2 published (PP) 5361
5368 Vaca Bypass See 1800 (JC) 1800
5369 Oil King in hand (JE & MG) 5369
5370 cave in hand (JE & MG) 5370
5371 cave in hand (JE & MG) 5371
5372 cave in hand (JE & MG) 5372 incl 5373
5374 shaft in hand (JE & MG) 5374
5381 cave published (PP) 5381
5382 cave published (PP) 5382
5384 cave published (PS) 5384

The list below shows links to those 104 sites which were extended or newly discovered around the summer expedition 2023 period, or which have had surveys, references or descriptions updated, photos or movie clips added, or entrances repositioned using a GPS.

Arredondo 0733 Vallina, Cueva; Arredondo 0733 Vallina, Cueva; 1747 Arroyo, Fuente del; 1757 Sumidero de Fuentes; 3270 Resurgence de Fuentes, Cueva; 3278 Barcena Morel, Fuente de; 4822 resurgence;
Beranga 4937 resurgence; 5336 Bus Stop Cave;
Cobadal 3684 shaft; 3685 cave;
Cubija 0670 shaft; 0813 dig; 1456 cave; 5325 rift; 5384 cave;
Cubillas 0026 Tiva, Cueva de;
El Naso 5387 Dana, Cueva de;
El Rincón 4867 resurgence;
El Suto 3232 Ruchano, Cueva del;
Fresnedo 2414 cave; 2522 dig; 2652 shaft;
Garzón 5150 Gusnardo, Cueva del (LC226);
Hazas de Cesto (west) 4933 cave; 4935 cave; 4936 sink / cave; 4941 Centinela, Cueva la; 5361 Arch Cave 2; 5367 dig; 5381 Ravine Cave; 5382 Four Entrance cave; 5385 cave;
Hornedo 3088 dig;
La Gatuna 3376 collapse;
La Secada 0081 Carcavuezo, Cueva de; 0084 Cosas, Cueva las; 0086 Cuvia, La; 0151 Anío, Cueva del; 0252 Decepción, Torca la (top entrance); 0707 shaft; 1222 shaft; 1505 cave; 2101 dig; 2108 Apprentice Cave; 2109 dig; 2752 cave; 2770 dig; 3054 dig; 3064 dig; 4179 cave; 4393 shaft; 4532 dig; 4732 Decepción, Torca la (bottom entrance); 5362 shaft; 5363 Hollyoak shaft; 5364 shaft; 5365 dig; 5366 dig; 5379 dig; 5380 Road Cave;
Moncobe 2538 Cubillón, El; 3755 shaft;
Mullir 1451 shaft; 3256 cave;
N Vega 0423 Barandas, Cueva de;
Ozana 0017 Jivero 2, Cueva de; 3884 cave;
Riaño 0103 Espada, Cueva de la; 0107 Hoyuca, Cueva; 1800 Fridge Door Cave; 2691 Giant Panda entrance; 5000 Boob Tube; 5368 Vaca Bypass;
S Vega 0040 Comellantes, Cueva del; 0048 Reñada, Cueva-Cubío de la; 0242 Tablons, Cueva de los; 1391 Volcano Cave; 2081 Muérdago, Torca del; 2082 shaft; 2083 cave; 2561 dig; 3762 shaft; 4998 shaft;
San Antonio 0713 Aguanaz, Fuente;
Seldesuto 0045 Humo, Cueva del (west entrance); 0258 Calleja Rebollo, Torcón de la; 1312 cave; 2102 shaft;
Trillos 0539 shaft; 4082 dig; 5369 Tomb of the Oil King; 5370 cave; 5371 cave; 5372 cave; 5373 cave; 5374 cave; 5375 resurgence; 5376 cave; 5377 cave; 5378 dig; 5383 dig;
Villanueva 5026 rift; 5036 Covachera, Cueva de; 5386 cave;

Summer 2023 logbook


   A very successful period for new cave found and surveyed. Over 1.3km of passages were documented and 7 new sites found by four, almost separate, groups. After thorough research, a team from the Eldon Pothole Club, discovered, surveyed, photographed and videoed over 840m of high and "main" level routes in Torca de Peña Encaramada (site 3380) while others extended the Four Valleys System by pushing at the northern and southern ends of Fridge Door Cave (#1800).
   The weather was mixed with some being summoned by Brittany Ferries to an early return crossing and others choosing to sail earlier to miss the predicted storms. The team arriving by air were diverted from Bilbao to Santander because of the strong wind. (Facebook users can view (or have viewed) various posts made by various cavers during and after the visits.)

Central & Eastern Sectors including the 4 Valleys System
   Extensions to the Four Valleys System were made in Fridge Door Cave (#1800), entering through the Boob Tube (#5000). Just inside, and to the west of that entrance, a set of crawls and rifts dropped 22m, heading back towards site 5000.
    Most effort was put in at the north end of Fridge Door Cave where a high level route over the On On passage was pushed and surveyed, allowing an easier way to the far reaches. Part way along this upper level, a small passage sets off to the north, then east, becoming progressively larger as a sandy-floored tube. The Crown Prince of Denmark's New Clothes has a number of unpushed side passages and exploration has currently stopped at a sloping chamber with a tall mud run-in. The way on continues.
    Over the p6 at the north end, a strongly draughting low passage was entered, Low in Knickers. This has several flat out crawls with a number of side passages, none pushed to conclusion. The length of the Four Valleys System grew to 72973m with these extensions totalling 291m.
   Nearly 500m to the southeast, Cueva Sin Sendero (#5227) - not yet part of the Four Valleys System - was visited, trying to forge a link to Ali Chamber in Cueva Llanío (#3234).
   The work to stabilise the entrance at Giant Panda (#2691) was completed although the section at the top of the following pitch remains dodgy.
   In the Cubija valley, trips were made into Simas del Picón for photography (#0075) and Frank's Cave, where capping is still required (#2167).
    On the southern side of El Naso, near the route up to Cubija, a large boulder came down the hill and badly damaged an outbuilding store next to the road. The rock didn't quite reach the houses on the other side of the road.

Eastern Mountains
   Good use was made of a previous drone flight over the eastern-most, high level Mullir section of the permit area. After a 5.5km walk-in, the team followed the drone path over tricky ground and damp conditions. Site 5389 is a boulder rift dropping at 45° for some forty metres where the boulders meet the roof. Site 5390 is a free-climbable, 12m deep shaft and 5391 is a 16m free hang to a choked floor.
   Down in Ozana, Pete Smith has resurveyed Cueva del Anderal 1 (#0008) with the length now at 185m, rather different from the previous estimated length of 80m.

Southern Sector
   Site 5162, a small shaft with an oscillating boulder, was inspected. It was thought that even if the boulder was capped, the open rift would still be too tight. Site 4998 was also inspected but the reported 5 second drop could not be reproduced.
   Exploration and survey in Tomb of the Oil King (#5369), a bouldery, mainly vertical mess was completed to a depth of 91m and length 365m. Further details to come about this site and other small holes in the area found in October.

West and Northwest
   During their week's stay, a team from the Eldon spent many man-hours pushing in Torca de Peña Encaramada (#3380). Over 845m were surveyed in low and higher levels with a number of leads still to look at. Nine survey batches contributed to the new length of 4931m.  Two Survex screenshots show the extent of the autumn finds - these screenshots in the usual Survex altitude shades, show the new surveyed stations as yellow dots. The entrance is shown as a green dot at the northern edge of both centre lines. An hour-long video is on YouTube.
       Site 5353 was worked at on a number of occasions with access to a promising, draughting drop improved. This hole is about 80m northwest of Cuba Libre (#4182) , an entrance to Torca la Vaca (#2889). A "tourist trip" was made into Torca la Vaca (through BigMat Calf Hole, #3916) to learn the route through to the start of Suit Wrecker Inlet. (This awkward inlet, over a mile long, brings water in from La Gatuna and may be the focus for pushing in the future.)
   Other holes visited around San Antonio included new site 5394 - a very tight resurgence; #5319, a short cave that finished at a dead-end low chamber, and #3080 - a dig in soil and rubbish.
   At Barrio de Arriba, a 10m pitch was found (#5395) but it needs work to get around the large slab and tree currently blocking the entrance.
   A couple of new holes were found high on the east side of La Gatuna, site 5392 - an excavated rift down to a draughtless low chamber, and #5393, an undescended 5m drop.

Other News
Hidden Earth took place once again after its enforced absence due to Covid and lack of a suitable venue. Chris Scaife gave the Matienzo talk about recent finds and included a tribute to Lloyd Cawthorne. Juan Corrin ran a Matienzo Caves Project stand and the display was awarded "Best Club Stand".
   A Spanish publication documents and discusses two pieces of decorated Iron Age pottery found on the nativity scene ledge in Cueva de Cofresnedo (#0065).
  Steve and Sue have produced a new set of Matienzo Caves Project garments. Details are on the MCP Facebook page.

The list below shows links to those 27 sites which were extended or newly discovered around the autumn 2023 visits, or which have had surveys, references or descriptions updated, photos or videos added, or entrances repositioned using a GPS. Note that explorations in October on the southern hillside of La Vega (including Trillos) have not yet been fully documented.

Barrio de Arriba 5395 dig;
Cubija 0075 Picón, Simas del; 2167 Frank's Cave;
El Naso 0065 Cofresnedo, Cueva de;
Hornedo 2889 Vaca, Torca La; 3080 dig; 3380 Peña Encaramada, Torca de; 5353 cave;
La Gatuna 5392 shaft; 5393 shaft;
Mullir 0418 shaft; 5389 cave; 5390 shaft; 5391 shaft;
Ozana 0008 Anderal 1, Cueva del;
Riaño 0107 Hoyuca, Cueva; 1800 Fridge Door Cave; 2691 Giant Panda entrance; 5000 Boob Tube; 5227 Sin Sendero, Cueva;
S Vega 1391 Volcano Cave; 4998 shaft; 5162 shaft;
San Antonio 5319 cave; 5394 resurgence;
Seldesuto 0258 Calleja Rebollo, Torcón de la;
Trillos 5369 Tomb of the Oil King;

Juan Corrin 8/12/2023

Autumn logbook

Christmas period

   The speleological highlights over the Christmas period were provided by Simon Cornhill and Diane Arthurs. Using the Torca la Decepción entrance in Matienzo, they surveyed more than 3200m of passages in the 4 Valleys System - all in Cueva Hoyuca, mainly resurveying in the Trident Passages, with over 1km of this length in new routes. "Days off" were spent exploring or finding smaller sites around Matienzo and Cobadal.

Central & Eastern Sectors including the 4 Valleys System
   In Cobadal, site 2099 could not be found in dense, chest-high gorse but two other holes were documented: #5396, a crawl leading to an "enlargement" (1m high x 1.5 x 1m) and #5397, a possible cave behind a tyre blockage.
   Three sites were investigated in the upper reaches of the Cubija valley. Shaft 0816 was repositioned and surveyed down to 10m, site 0814 was explored down a very tight 3m deep vertical drop into a bouldery mess, and #0670 was opened up at the base only to reach a chamber just large enough for three people to stand in.
   In the Arnilla valley to the west, shaft 0429 was re-explored and surveyed for 35m.
   In the La Secada area, Near the Bar Pot (0603) was seen to have flood debris in the roof, floor and ledges. In a depression on the hillside above, the dig at site 4214 was seen to have slumped. On the same day, in thickening vegetation and failing daylight, sites 1063, 3639 and 1064 evaded detection. The mystery surrounding #1623 was partly solved when the 1623 sketch which didn't match the description was recognised as belonging to Two Way Cave (4534). Above Two Way Cave, shaft 0229 couldn't be found - again! The open shaft at site 5362 was explored down one rift for 4m but the parallel shaft needs enlarging to reach the base. The shaft at site 1551 was found to need some enlarging. Site 0260 was relocated and is probably still a feeder to Aven Alley in Torca la Decepción (4732). Cueva de Germán (1232) was visited on one occasion, looking at the potential and taking some photos. The dig at site 1488 was cleared enough to suggest it may be a reasonable prospect. It lies over the last chamber in Cueva de Germán. Between sites 0415 and Cueva Bollón (0098), the draughting dig 1018 was worked on one occasion.
   Over a three-week period, the far reaches of Cueva Hoyuca (0107) were blitzed. The Torca la Decepción (4732) entrance in Matienzo was used on all seven trips to the now less remote area. Before these winter explorations could be carried out, the floor of the 322/1/6 Super Duck in Decepción was excavated to allow a safer passage in what was a stream rather than a trickle.
   Most time was spent in the Trident Passages, in particular the Gypsum Traverse, entered up a climb over a calcite blockage off the northern arm of the trident and heading back ENE at high level towards Rocky Horror. (This was wrongly located on earlier survey versions.) The high level chambers along here were reported as being "exceptionally well decorated".
   Resurvey work included the "stunning" Snow White (part of the Left Hand Passage) where a previously un-surveyed, smaller but amazing walking-sized, gypsum-encrusted passage eventually rejoined the main route after a climb up from a trench in the floor. Numerous cross rifts and alcoves were investigated.
   On the final, de-rigging trip, Judgement Pitch at Armageddon was equipped for SRT and the "fairly squalid" inlet off Paisley Passage was re-surveyed and pushed. After passing through 45m and 37m avens, a further thrutch, "landed us in an impressive very large, circular aven (Indomba) with a custard-coloured flat floor". The disto would only read a maximum of 62m up Indomba due to the spray from falling water - however it looked much higher than this as our powerful 3000lm aven blasting torch couldn't illuminate it to the top!" Further resurveying was carried out to check a previous survey from the summer. This trip was the longest into the system taking some 16 hours.
   By the end of the period, the length of the 4 Valleys System had increased by 1023m, taking the total to 73,996m. (The 4th longest in Cantabria, 8th longest in Spain and 41st in world ranking.)

Eastern Mountains
   Sites 1023, 1024 and 1025 on the north side of La Colina could not be found. Up the hill from these supposed positions, new site 5398 was explored: a wriggle to a sloping enlargement containing empty animal feed bags and a 1m drop to a choked floor.

Southern Sector
   South of the Piluca summit, the entrances of Sima de la Piluca (0472) and #0473 were better located and photos taken. However, site 0714 could not be found.
   The Colectivo Piezo group from Madrid have been active in Cueva de Coquisera (0039) pushing up beyond Popcorn Climb into extensive finds. Not yet surveyed, the new passages have a sketched elevation.
   Site 5162, with an oscillating boulder blocking a rift, was explored down to a tiny continuation with the sound of falling water not far away.

Other news
   In applying for a grant from the Ghar Parau Foundation in early January, Phil Papard took up the challenge of trying to calculate a meaningful figure to allow the Matienzo Caves Project to offset the annual amount of carbon dioxide produced by expedition members travelling to Cantabria and driving around the permit area. Over eight tonnes of carbon dioxide were offset by paying £56.95 to a company that supports "a Global Portfolio of Verified Carbon Reduction Projects". And there is a certificate to show the offsetting.
   As an experiment to give cavers every opportunity to complete a log of caving activities, an online logbook was available over the Xmas period. This was simply a single Google Docs document, available to everyone that had the link. This was completed in a regular fashion (mainly by Diane and Simon) and a final pdf version is archived and available online.
   For Easter 2024, the main logbook will also be online (editable with Windows, Android and Apple devices) with the link provided to all participants. A subsiduary paper logbook will also be provided for those that do not have the means to complete the online version, although the computers on the Matienzo Office network will have online access. Any entries in the paper log will be scanned and transferred into the online logbook.
   An example online Easter logbook is here - it includes a help page and anyone using this link should feel free to experiment and add / delete material. A new link to the definitive Easter online logbook will be provided in Matienzo.

New surveys and survey updates (in hand)
Description Drawn survey Survex centre line
0107 Hoyuca resurveys and surveys: Trident, Paisley, etc etc (SC & DA) 0107
0429 shaft in hand (DA, SC) 0429
0816 shaft in hand (DA, SC) 0816
1551 shaft in hand (DA, SC) 1551
5162 shaft in hand (DA, SC) 5162
5362 shaft in hand (DA, SC) 5362

The list below shows links to those 37 sites which were extended or newly discovered around the Christmas period, or which have had surveys, references or descriptions updated, photos or videos added, or entrances repositioned using a GPS.

Cobadal 2099 dig; 5396 cave; 5397 cave;
Cubija 0670 shaft; 0814 shaft; 0816 shaft;
El Naso 0059 Molino, Cueva del;
La Colina 1023 cave; 1024 cave; 1025 cave; 5398 cave;
La Secada 0084 Cosas, Cueva las; 0229 shaft; 0260 shaft; 0603 Near the Bar Pot; 1018 dig; 1063 dig; 1064 cave; 1232 Germán, Cueva de; 1488 cave; 1551 shaft; 1623 cave; 3639 dig; 4212 dig; 4213 dig; 4214 dig; 4534 Two-way Cave; 4732 Decepción, Torca la (bottom entrance); 5362 shaft;
N Vega 0429 shaft;
Piluca 0472 Piluca, Sima de la; 0473 shaft, cave; 0714 cave;
Riaño 0107 Hoyuca, Cueva;
S Vega 0039 Coquisera, Cueva de; 5162 shaft;
San Antonio 0713 Aguanaz, Fuente;

Juan Corrin 8/1; 31/1/2024

Christmas / New Year logbook