0081: Carcavuezo, Cueva de
La Secada 30T 452787 4797778 (Datum: ETRS89. Accuracy code: A) Altitude 146m
Length included in the Four Valleys System: see Cueva Hoyuca)
Area position

Updated 13 February 1998; 19th February , 18th April 1999, 12th December 1999; 16th September 2000; 21st January, 1st April, 29th April, 7th October, 26th October 2001; 25th October , 11th November 2002; 15th October 2003; 8th October 2005; 1st February,17th December 2006; 4th May, 27th September, 27th October 2007; 3rd May 2009; 16th January, 8th March, 24th June, 4th October 2010; 6th January, 12th May, 11th October 2011; 13th January, 23rd April 2012; 13th September, 18th October, 21st November 2013; 19th January, 21st May, 16th September 2014; 16th May, 13th, 25th, 28th September 2015; 7th January, 15th February, 20th April, 14th October 2016; 5th February, 8th September 2017; 30th April, 1st July 2018; 27th January, 4th August 2019; 30th October 2020; 6th March 2022


Part of the Sistema de Cuatro Valles. the Four Valleys System. (See Cueva Hoyuca for a list of the caves that form the Four valleys System). The main, cavers' entrance is often choked with flood debris. It was checked in July 2016 and found choked. However, at the end of January 2017, the overflow trench and overflow sink area and entrance top were found completely free of branches (photos), but the entrance was choked at the base of the entrance climb.

The above altitude is for the cave entrance. The altitude of the sinks is about 139m. A draughting hole above the sink was discovered in 1990 and may provide an easy entrance to the Western Series.

Cueva de Carcavuezo is the modern main feeder to the Four Valleys System (line survey) and is the major sink for water leaving the Matienzo depression. The water has been dye tested to the Los Boyones resurgence in Secadura. Information gleaned from the Dirección General de Obras Hidráulicas y Ciclo Integral del Agua in 2005 shows an average water flow into the sink over the previous 20 or so years of 295 litres per second. (A small amount of water sinks in the Orillón complex (site 0023), and this water has been traced through to a resurgence to the south of Cruz Usaño).

The sink area was surveyed in early May, 2015 when 7 sinks were observed. Over a couple of days with no rain, fewer sinks took water. More details are seen in a video and the survey which was updated in the summer 2015. In late January 2017, another sink was obvious in the form of a whirlpool and the geography of the sink area had altered. (Video). In August 2017, (suspected signal) crayfish were seen at the sink.
The fixed point for the sink area is the southeast corner of the barn on the track; that for the entrance, the southwest corner of the Mushroom Field barn. It was thought that, after the recent underground resurveys, it may be that the sinks and/or the entrance could be opened up to provide a greater capacity for the sinking water, preventing most floods. However, after surface and underground surveys around the sink area at Easter and summer 2015, the enthusiasm shown by JCFG for mining a hole in at the sinks through the boulders to meet the underground stream has waned as the survey showed a distance deemed too long and expensive to consider. The main entrance has been measured for a grid.

The 2015 work included molephoning at two locations: the short drop at the end of the narrow section in Green Cool Passage and a high point in the newly-discovered Puffin the Beaver extension. The data for these locations is found here.

The 2015 surveys also highlighted the wrong positions of the contours lines around the sink and entrance and the incorrect course of the stream (which is hidden under trees). Enough data was calculated to allow a redraw of stream course and the contours in this area. A new 140m contour line was drawn at the sink but, although these lines are now better than those on the original map, there will still be errors.

A direct and relatively straightforward route exists into Cueva Llueva (114); the route to Cueva Hoyuca (107) is through a collapsing boulder choke and should not be lightly attempted. The area of connection was entered through the sump at the end of Strangle Wanking Passage in August 2017, when orange line was encountered. The sinks in high flood lies under about 10m of water, ie water reaches the 150m contour; the earlier, lower sections of the 1986 Extensions are likely to sump up with little rain.

Cave description

The río Matienzo (also called the río Clarín) sinks into a mass of boulders and logs. A deep, excavated and normally dry trench beyond this leads to an area of boulders and flood debris. A draughting rift on the northern side of the flood sink is the main entry point - the first trip after heavy rain may  need to excavate the entrance of its logs and other flood detritus. (Photos and YouTube video). Site 3895, to the south, is also an entrance that has been surveyed through.

Route finding in the boulder strewn, descending rifts and large phreatic tubes is facilitated by the draught. At a low chamber, a stoop ahead leads to a chossy climb up into an area which could bypass the present, flood-prone route; to the left an arrow marks the usual squeeze down into a descending, bouldery rift and a short drop to a block at the top of the river passage. A straight climb down or a less exposed drop between the bouldery walls leads down to the river. More boulder chokes have to be passed before the sump pool is reached within 200 metres. This has been dived to a boulder choke and holes directly above the sump have been maypoled - there is a possible draughting continuation here. Is this the "high rift near the end of the canal that has a strong draught" and "could be bolted"? (Easter 2014).

Much poking about in the roof of the choke has also occurred.

Two ways into the major east and west extensions exist, the 1986, low level route contains rocking boulders but may need to be followed to hang a ladder down the climb for the other route.

Most cavers should follow the stream down until a ladder is noticed hanging from the roof. A climb up leads directly into the 1986 (Easterly) and 1988 (Westerly) Extensions.

The entry point to the low level route to the 1986 Extensions lies on the right of the stream and is a 3m climb down an awkward fissure to a pebbly crawl into a wide bedding and, after 20m, a rocky squeeze. A small climb to the right then drops down a rift to a small, gravel-floored chamber with a pool. A climb up to the left followed by an uphill slide through a body-sized right angle leads to a muddy climb over and between boulders and two slippery parallel drops of 4m. Either of these lands in a small, muddy passage and a straddle climb down to water. A short crawl over mud and gravel leads to the base of 30m of clean-washed rift passage. A bridging climb of 6m pops up into large passage, the start of the Afternoon Stroll in the Easterly Extensions).

After 130m of pleasant stroll in a phreatically enlarged rift a breakdown area, the Light Frigit, is met where other passages converge from the north. One, the Third Fanny heads back towards the entrance but ends at a series of choked phreatic rifts to the north and a very low bedding to the west. The Fourth Fanny heads north and back towards the Third Fanny ending in a boulder choke.

The main line continues east enlarging to 4m wide and high until a similarly-sized passage joins it from the south. Ripple marks in the sand appear to indicate water flow from the south and west heading eastwards.

The Southern Inlet continues in similar style for 100m where at a junction to the right, a narrow rift leads over a traverse to calcited boulders. At the bottom of the traverse a phreatic maze leads back to the junction. The southern end of the Southern Inlet degenerates into low crawls under the walls.

The main route continues east down a large passage with fine floors of eroded and scalloped mud. After 100m, breakdown is encountered and a very large boulder almost blocks the passage. Beyond is Red Column Chamber, a large breakdown chamber with a few small stal and a 3m long red formation in the NE corner.

Duck Passage is the route which heads east out of Red Column Chamber and is a smaller, 3m square passage. It is formed in a bed of nodular limestone which has broken down extensively to small, muddy rubble in places. After an initial rise, the passage gradually slopes downwards, becoming muddy and passing the eroded rock, The Duck, after 90m. The next 120m appear to be fault guided with a hading wall on its south side. Numerous blind phreatic rifts are present in the wall and the roof. A few small white formations brighten the drab, mud-covered passage. Passage size varies from 6m wide and 4m high but is more commonly 3m square and, progressing east, becomes more obviously phreatic with rifts and short, mud-blocked side tubes, the passage now being lower than the friable bed of nodular limestone. Eventually a muddy maze of walking, stooping and body- sized phreatic passages is entered (at least 110m of which is unsurveyed), all soon forming parts of two routes through a truncated section of large passage blocked at both ends by sediment. After an initially large segment 5m wide by 4m high, floored by dried mud the roof has collapsed from the over-lying nodular limestone beds, mainly choking the passage at Gypsum Chambers. Crawling over and under gypsum-strewn muddy boulders leads via an squeeze to an unpleasantly small, muddy tube with pools in the floor and ending at an 18cm wide connection with the Pease Pudding Passage of Cueva Llueva (114).

In 1999, opposite Straw Passage, over 500m was surveyed in Parallel Sausages. At Andy Quin's Foot, 100m of passage (Ramon Bolado) was surveyed which heads back towards the upstream sump passages in Cueva Llueva.

An impressive canyon passage leads from Red Column Chamber over large fallen blocks to a rock bridge with a metre deep pool beneath. The canyon bottom is now mud and splits to a lower passage The Rectum and a climb past a large rock pillar into Argument Passage. Above the pillar, a 4m climb give access to a 3m x 2m passage trending NE with branches and boulder blockages. One route leads back to Chase the Dragon after about 100m.

Argument Passage continues 10 - 12m high and 10m wide to end after 70m at a mud-covered boulder slope. The top of the slope has very nice red stalagmite cones up to 1m high and chokes in large boulders. Following the southern wall, a draught encourages squeezing between stalagmited boulders. This has been pushed for 20m to where the draught disappears between muddy boulders.

The Rectum is the start of Chase the Dragon and takes the strongest draught between Cueva Llueva and Carcavuezo. It is a muddy passage up to 4m wide but mainly low stooping under an arched roof. Side branches have not been surveyed or pushed. After 150m the passage narrows with potholes in the floor and soft, friable shaley rock. After a few short oxbows (not shown on the survey) the passage forks.

Keep Right For Smack is the way through to Llueva and carries the strongest draught. The route is through shallow pools and over slippery calcite mud and after about 80m pops up in the floor of Cueva Llueva, about 100m west of the Rhinoceros. ( Continuation Passage is straight across from the entry point and is a climb down in boulders. The passage continues as a small series of hands-and-knees, mazey tunnels which run around the north side of the Smack Choke but ends too tight). A panoramic photo of above Smack Choke can be viewed.

The Maze is the alternative route to The Rectum. It contains at least 100m of unsurveyed junctions and oxbows. Its limits to the west and south are not known. By following the draught a route is found through to the Abattoir, a red mineral-smeared area where a climb down drops into a river running in amongst boulders. By following the river to the west the Sewers of Doom are reached above the river and eventually the Candy Shop in Cueva Llueva. (Sewers of Doom survey below). The Candy Shop has deep red gour pools on the boulder pile.

[Most of above by Terry Whitaker. Passage development arguments in file.]

The Western Series needs writing up. (See below, October 2013). The ladder up broke in the summer 2003 and is now next to a replacement as the krab on the old one has broken.
Barn Passage
comes close to the building which Alberto was doing up. He has told Pete that there used to be a natural drainage for the cow-shit inside the shed. So it may be worthwhile re-investigating this area of the cave - or his decaying barn. There appears to an an remnant arch behind the house that is full of debris.
At Easter 2001, the sump in Ovlov Passage was dived through into a 25m rift chamber with a narrow squeeze. This was pushed in the summer with 30m of under water passage that was still going. The sump is further into the hill than the Volvo passages and is parallel to them. In October 2002, the sump became too wide over "silt dunes". It was noted that the passage is heading south towards Volvo. The dig at the entrance to the sump was also examined. It appears to be a good site as the passage is not heading straight for Volvo, rather heading west.
In the very dry summer of 2003 "the water level had gone down and there no flow from the sump so would be a good place to dam and bail; estimated time of bailing 3 hours with a bucket leaving a 'dry' sump. The first sump would take about half an hour to bail but this just leads to a rift with a sandbank and the other sump would have to be bailed. It's approximately 4-5ft deep in current conditions".

An extension at the end of the Draintester Passage in the Western series - Purgatory - was first entered in 1991(?) for about "300m". The small passage was surveyed for 248m in 1997 and is still going for at least 60m is similar passage. The lower altitude route passes below the middle arm of Trident Passages in Cueva Hoyuca (107).

Link to entry in the Cave Diving Sump Index.

The resurvey of the cave, as part of the 4 Valleys System resurvey, was started in the summer, 2013. A number of extensions and previously unsurveyed sections were entered and will be described in due course. The 2.9km of Survex survey can be seen here. The combined survey is currently on the area map and shown in Survex files below. (January 2014).
Draft drawings (early 2014) are available of the entrance area and more of the cave.
Further (re)surveying was carried out during the Easter 2014 expedition and small extensions made. Batch 14-01 is above the stream; 14-03 links through to site 3895 and batch 14-04 was a resurvey of rifts near the Western Series.
Further (re)surveying was carried out during the summer 2014 expedition and extensions made. Batch 14-06 is mainly resurvey linking the east to west series. Batch 14-07 is up a rift climb in an area of rifts and leads to a series of tubes and rifts with faint draught. A sandy crawl at the west is a dig that continues. There is a draught down at the N end which could be pushed. There were 92m of new passage surveyed here. Batches 14-08 and 14-10 are 12m and 29m of new passage in the same area. Batch 14-09 is resurvey. Batch 14-11 is a new series in the Haymarket. This goes off at the first major junction where a climb down through boulders follws the stream with a descending passage pushed through a duck to eventual deep water and a low duck. This was surveyed for 118m. The area was revisited on Aug 8th and a few hundred metres of new passage found but not surveyed. (This could be beyond the end of 14-11 but may also be at the start of the extension.)

   In the summer 2015, further resurveying took place - in Green Cool Passage (batch 0081-15-01) and Southern Inlet (batch 0081-15-02). A passage called The Afternoon Crawl (that heads back west from the The Afternoon Stroll) was also surveyed/resurveyed (batch 0081-15-03). New passages were discovered near the start of the Western Series., batches 0081-15-04, 06 and 07, described by Alex Ritchie:
   0081-15-04 A dug out choke squeeze leads into a small chamber with boulders. There is a trianglular slot above that has not been entered, appears to be too tight and enters another boulder chamber which is the likely residence of one of Ali's gloves. A crawl straight ahead up a slope is the way on. The passage appears to end here. However, an enlarged squeeze straight up leads to the continuation, up a 3m broken climb. The crawl from here leads to another easy squeeze which shortly breaks out into larger passage.
   Turning 180 degrees and climbing up reachs a crawl, part of batch 0081-15-07. This is a rift passage that goes on for about 15m until it chokes in boulders with many drafting holes. The short passage on the left part way along the rift also chokes.
   Back in the main passage, on the right of the calcite slope (batch 0081-15-07) an easy climb up leads to a chamber with a small amount of water entering, which appears to be too tight.
   Up the calcite slope in the main passage, the passage opens up onto another level. In front is a short amount of flat floored walking passage that is blocked by a large boulder. The passage continues for a little further to the right before that too is also blocked by boulders (unsurveyed).
   Continuing up higher beyond the flat floor passage eventually leads to the top of the calcite slope. (End of batch 0081-15-04)
   Batch 0081-15-06 From the top of the slope there are three ways on. Down the slope, loose passage quickly closes down in boulders in all directions, as does a forced crawl straight ahead at the top (latter unsurveyed). Above is a climb over poised boulders entering the highest passage of the exentions where the mole phone was placed. This walking passage quickly leads to a calcite blockage, where a climb up followed by a flat out crawl goes into further, decorated passage, which unfortunately terminates in a solid calcite choke.

   In October 2013, in the entrance series, passages beyond the climb into Big Chamber Somewhere near the Entrance were looked at and surveyed beyond the limit reached in the summer, these appearing to form a continuation of the chokes at the start of the Afternoon Stroll.
Big Chamber Somewhere near the Entrance was visited on two trips, the climb up being made substantially easier by the removal of two chockstones which previously made the climb pretty tight. Care is required through loose blocks up into the chamber. At the western end of the chamber, two passages were explored. One extended about 20m to a possible dig perhaps towards surface, while the more northern was pushed through a draughting dig to a further dig after 35m. Also at the western end of the chamber, a route through boulders in the floor was pushed to an undescended hole dropping to water, presumed to be the upstream sump area. (One hole was dropped at Easter 2014 to link with the stream). In the streamway in the "old" cave, the area around the upstream sump was investigated, some possible leads requiring bolts to reach.
Downstream, an oxbow towards the downstream sump was surveyed and a draughting narrow rift noted.
The complex of rifts on the north side were further surveyed up to the connection to the Western Series.
The Western Series was resurveyed as far as the start of Barn Passage and various passages beyond were revisited.
The most direct routes into the Western Series can be described as either a rigged slippery traverse in the more southern of the rift series, or following the more northern rift and following it through waist deep water until the passage ends at a slot in the floor of the Western Series.

   Strangle Wanking Passage, (first explored and surveyed from the Cueva Llueva, but now more easily reached from Carcavuezo entrance) was pushed through the terminal sump by Dave Garmin in August 2017 into a bouldery area where orange string had been left from a previous exploration near the end of Cueva Hoyuca. The sump has a line through, bolted at each end, and has been described as a 5 -6m free dive. There is a dangerous rocking boulder on the Hoyuca side which requires some attention. A video of the dive, filming and exploration into Hoyuca has been edited. The survey in the area appears quite accurate apart from the z axis.
   A number of (re)surveys were carried out in Carcavuezo/Llueva in the summer 2017. Batch 0081-17-01 is the cross over passage near Chase the Dragon; 0081-17-02 is a resurvey of keep Right for Smack; a west-heading passage off the Afternoon Stroll is batch 0081-17-03; Smack Choke corner, batch 0114-17-01; the far reaches of SW Passage, batches 0114-17-02 and 0114-17-03.
   When routes through to SW Passage were found to be too wet, further resurveying was carrying out at Easter 2018 - "loose ends" tidied up. This resulted in about 60m being surveyed for the first time. (Batches 18-01, 18-02 and 18-03).

L. Mills found a Lithobius in 1986.

Matienzo and its caves are mentioned in the Diccionario Geográfico-Estadístico-Historico de España Tomo XI, a geographical dictionary published in 1848 (Madoz Pascual, 1848). Comellantes is mentioned as the resurgence into the depression with water disappearing in La Secada and appearing in Secadura after ½ league underground. Bad flooding and poor roads are mentioned. The Cavernas y Simas de España (Puig et al, 1896) mentions various Cuevas de la Secada, of different sizes, which serve in times of heavy rainfall to absorb the excess water. This book also has a pozo nuevo taking the water.
It was around this time that a new, apparently lower road through the depression was built. It may be that the new pot was able to prevent frequent bad flooding. The previous water levels in the depression may have been generally higher and there may be old flood sinks to discover, beyond and higher than the present Carcavuezo entrance.

References: Beardmore W and Lenartowitz S, 1972; anon., 1974b (logbook); Puig et al, 1896; Madoz Pascual, 1848; Fernández Gutiérrez Juan Carlos, 1965; anon., 1974a; Cox G, 1973; Fernández Gutiérrez J C, 1975; Cope J et al, 1976; anon., 1978 (logbook); Manchester University Speleological Society, 1982 (survey); Corrin J et al, 1978; anon., 1980a (logbook); Corrin J et al, 1981b; Corrin J, 1980; Mills L D J, 1981; Mills L D J and Waltham A C, 1981 (survey); Corrin J S and Smith P, 1981; anon., 1981a (logbook); anon., 1983b (logbook); anon., 1985b (logbook); Corrin J, 1986; anon., 1986 (logbook); Corrin J, 1987 (survey and photo); Manchester University Speleological Society, 1982 (survey); material in file; anon., 1987 (logbook); Corrin J and Knights S, 1988; anon., 1988 (logbook); Davis J and Corrin J, 1989 (photo); Cawthorne R, 1987; anon., 1989 (logbook); Neill A et al, 1989; anon., 1991 (logbook); Corrin J, 1992a (survey); Corrin J, 1992b (survey); Corrin J, 1994b (survey); anon., 1996c (Christmas logbook); anon., 1997b (logbook); Corrin Juan, 1998; Fernández Ortega F, Valls Uriol and Maria del Carmen, 1998; García José León, 1997 (survey); Corrin Juan, 1997c; anon., 1999a (Easter logbook); anon., 1999c (logbook); Corrin Juan, 2000; anon., 2001a (Easter logbook); anon., 2001c (Summer logbook); Corrin Juan, 2001a; anon., 2002e (February logbook); anon., 2002c (autumn logbook); Corrin Juan, 2003a; anon., 2003c (summer logbook); Corrin Juan, 2003c; anon., 2005b (Easter & summer) ; Corrin Juan, 2005; Corrin Juan, 2006a; Corrin Juan and Smith Peter, 2007; Corrin Juan, 2010; León García José, 2010 (Volume 1 and Volume 2) (line survey and photos); anon., 2012b (Easter logbook); Corrin Juan, 2013a; anon., 2013d (summer logbook); anon., 2013e (autumn logbook); anon., 2014b (Easter logbook); anon., 2014c (summer logbook); anon., 2015b (Easter logbook); anon., 2015c (summer logbook); anon., 2016b (Easter logbook); anon., 2017a (January, February logbook); anon., 2017c (summer logbook); anon., 2018b (Easter logbook); anon., 2020d (autumn logbook)
Entrance pictures : yes, 1977, 2005 and 2009 (under water) : free-flowing sink : moderate flooding Easter 2012 : Excavating entrance 2014
Sink area, Easter & summer 2015 : Entrance Easter, summer 2016 : overflow channel and entrance January 2017 : sinks area with crayfish, summer 2017 : sink area October 2020
Underground picture(s): the sump (1977) : summer 2013 : autumn 2013 - Big Chamber Somewhere the Entrance & Western Series : Above Smack Choke panorama
Summer 2015 - Afternoon Stroll & Southern Passage
Video: stream sink   Entrance: 1  2  3  4 :
Moderate flooding Easter 2012 : New route to the Western Series, 2013 (YouTube) : Clearing the main entrance of flood debris, Easter 2014 (YouTube)
Survey of the sinks, May 2015 (YouTube) : Molephoning, summer 2015 (YouTube) : sink whirlpool, January 2017 (YouTube)
Llueva/Carcavuezo to Hoyuca dive through, 2017 (YouTube)
Detailed Survey : Original 1974 survey : Sewers of Doom: lower left and right : upper : composite
Draft portions of new survey (Easter 2014) - cave : entrance
surface survey of sink area (May - summer 2015) : cave (published Sept 2015) : entrance series : entrance series published August 2019
On Paul Fretwell's latest version of the Fours Valleys survey
Line Survey :
On area survey : 4 Valleys Survey (no details)
Survex file : yes, including sink area surface survey (after Easter 2018) : 4 Valleys System - lite and complete with other caves (after New Year 2019). (Amended magnetic declination December 2013 to align with Eur79 grid and coordinates altered to fit ETRS89 datum, April 2014.) : Loch file of the 4 Valleys System + selected surrounding caves (Paul Fretwell, April 2012) (download as a zip file)
Passage direction rose diagram: Four Valleys System