The main Matienzo Expeditions occur around Easter (3 weeks with the Easter weekend in the middle) and from the last week of July into August (4 weeks). Visits occur at other times, e.g. October / November, Christmas/New Year, February and Whit week.

New cavers to Matienzo are welcome: you may be expedition-experienced or not, but you will have your own personal clothing and equipment, insurance and will have a reasonable knowledge of caving techniques.
Fresh perspectives and enthusiasm often leads to new cave discoveries! See also this flyer.

This page gives a flavour of what happens above and below Matienzo and the surrounding area.

Contents
The Area
Permissions, Grants and Donations
Accommodation and Catering
Caving Organisation
People
Caving
Caving Areas
Publications
Cave marking
Conclusions
More information
Upcoming expeditions
Shortened Bibliography

The Area
   The 26km² enclosed depression of Matienzo has taken some 2 to 3 million years to form. The imperviously-floored valley is surrounded by limestone hills containing hundreds of kilometres of cave. Water resurges into the basin at a number of points and most of it leaves underground at the northern end.
   A major Spanish expedition took place in the summer of 1964. British-led caving expeditions and visits to Matienzo (and surrounding areas) have been occuring up to 3 or 4 times a year since the late 60‘s and the amount of known cave passage has risen from some five or six km to hundreds (over 428km, December 2024, see a summary sheet). About five to eight kilometres of cave are found each year, although in 1989 over 15km was surveyed, in 2004 some 10.7km and in 2008 over 13km. Of course, the Covid-19 pandemic severly curtailed activities in 2020 and 2021. Collaboration with Spanish caving groups often results in new cave exploration. We also have good relationships with French cavers working to the south.
    An area map shows the major caves, the Google Map below shows Casa Germán, the HQ for each expedition.


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Permissions, Grants and Donations
   Permission to cave is given by Spanish speleological authorities within both geographical (about 106km²) and time limits. We were refused permission to cave during 1990 because caving occurred outside our designated area in the previous year. Although we do not have official permission to cave beyond the current permit boundaries, Spanish groups in adjacent areas may allow exploration in systems that we have previously explored. If in doubt, consult with Phil or Juan. The exploration permit runs for the full year.
   One of the permit requirements is a report of the speleological activities over the year. For this reason and because the permit is given to the Matienzo Caves Project, all people contemplating a caving trip to the Matienzo area outside of the usual expedition periods should ensure they are included in the permit by contacting Phil Papard or Juan Corrin (see the Contacts page). Full documentation of any new exploration(s) is required, i.e. logbook account, passage description, photographs and, if appropriate, survey data, survey drawing and final survey.
  Good relations are kept with the villagers, Spanish, French and visiting caving clubs and authorities (including the Federación Cántabra de Espeleología) and the Guardia. We have had the support of the Ghar Parau Foundation. The grants recently awarded can be seen here.
   To supplement any award, the expedition asks for an annual donation from cavers aged over 25 of £3.50 a day to a limit of £35, i.e. a maximum payment for 10 days. Younger cavers (25 and under) are asked to donate £2.50 a day to a limit of £25. Sterling donations are preferred. Donations in euros will depend on the exchange rate.
   This donation covers all group equipment (ladders, rope, bolts, rescue equipment, GPS, etc), surveying and some publication and IT costs. As well as paying during an expedition, there is also the preferred facility to pay caving donations up-front. (Contact the expedition treasurer for details).
   A proportion of the donations is paid to Pablo for the use of the restaurant at Casa Germán as an expedition base and a survey / drawing up area. The cost of any approved group equipment bought by individuals will be reimbursed. (There is also a charge for camping - see below).
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Accommodation and Catering
   Tents can be erected on the field behind the bar. (Zoom into Restaurante Casa Germán on the map above). Only the south-eastern half of the field should be used and, as it is used for grass crop, vehicles should only drive on when the ground is dry and hard. 'Domestic' refuse should be disposed of in the wheelie bins found on the roadside.
    There is a toilet block in the middle of the campsite which has showers, wash basins and toilets. An outside tap is for drinking / cooking water and washing small items of personal gear and equipment. There may be a rota for giving the facilities a quick wipe over, but please leave facilities as you would wish to find them. The water has to be paid for by Pablo and should not be wasted. Therefore group tackle (ropes, ladders, etc) must be washed in the river. A room in the block acts as a tackle store and is used for charging electric cells.
    Pablo at the bar charges 5€ per adult per night for camping, up to a maximum of 100€ per stay. This will be collected by the expedition treasurer and paid to Pablo in a lump sum at the end.
    Everyone looks after themselves for catering, although alternative food arrangements can be made when long trips are likely. The tackle store has a microwave and fridge with small freezer compartment. There are supermarkets on the way to the beach or at Ramales, the nearest large town where travellers cheques can be cashed or cash cards used.
    Many oldtimers find a cool box and ice packs (re-frozen in the deep freeze at the bar or in the tackle store) a necessity to keep meat and veg edible. The restaurant, at the edge of the campsite, opened in 1994, is convenient and there are other restaurants in the area. There is often an expedition meal (or two!) at the height of the caving frenzy.
    Pablo and Anna at the bar have been very amenable about supplying late butties, up to about 10pm. Last entry to the restaurant is 10pm. The bar opens at about 10-30am (depending on the previous night's activities) and will serve an English breakfast or egg butties, etc. Bread is delivered to the bar around 10-30am. People can buy straight from the van and pay for it individually. The Bar Panadería also provides food.
    Self-catering accommodation is available in the village, eg at Cubillas (opposite the Bar Panadería) and bed and breakfast is available at the Anjana near Ramales and Casa Tomás in Ogarrio. Accommodation is also available further afield, eg at Solórzano, Lierganes and La Cavada. (See the Travel, Accommodation and Weather page). Try AirBNB for, at least, a 10-person ex-farm building over-looking Matienzo (La Cubía).
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Caving Organisation
If this is your first time in Matienzo, you should consider printing out and filling in the personal information sheet before you arrive.
   Many of the cavers who come to Matienzo are not here primarily for the sport - they are people fascinated by the potential of the area and who pit their speleological wits against the draughting holes, deep shafts and tight crawls which could lead to 'caverns measureless'.
    Caving trips occur because a number of people see the need for them and they are one of the expedition objectives. There are not many organised 'tourist trips' - the best way to see the caves is to get involved in a series of working trips - pushing, surveying, photographing, etc. Anyone can organise a trip and, apart from the specialised (e.g. diving) ventures, all trips should be open to everyone. Obviously, each team on a major push/survey will have at least one person who has been in the system before and might well be the 'system expert'. Because systems tend to be pushed over a number of years, it is better that as many people as possible get to know a cave, rather than just one team. British caving clubs count for little in Matienzo - we are the "Matienzo Caving Club"; everyone should feel part of a whole expedition and be prepared to cave with anyone of similar caving aptitude or less experienced.
   First-time expedition cavers should realise that new exploration does not finish when the trip finishes. There will be one or more of photos, logbook, surveys, passage descriptions and videos to organise / caption / store, etc, etc

   Trip Sheets can be used to aid the organisation of the various parties that are likely to set off each day. The initial details of cave, objectives, date and number of cavers required are filled in by the trip leader(s) and cavers can then sign up for whatever takes their fancy.
   A sign out/sign in board is located in the Office at the back of the restaurant and must be completed for every trip with names, cave, time in, expected time out and rescue call-out time. You must have signed off on the board or contacted Phil or Juan before the call-out time otherwise the rescue procedure will start. It is expected that call-out times will be before midnight or after 10am the next morning - so trip start times should be arranged accordingly. A WhatsApp group is also active to relay caving information.
   There is also a tackle / equipment signing out sheet.
  Every caving team pushing a new system is likely to explore new passage. Each group should survey the passages as they leave the system so that the survey can be computer-drawn later that evening, allowing the next team to concentrate on the best leads. Each team therefore has the responsibility of ensuring that the survey data is converted to co-ordinates the same day and a survey drawn over the computer centre-line print out as soon as possible. More modern technology, e.g. DistoX and TopoDroid, allows passage outline and details to drawn underground then exported to the Matienzo storage.
    An account of the new explorations (and any other speleological activities) should be entered in the online log book (a Google Doc) immediately and a description of the passage(s) should also be recorded, although the two aspects can often be combined. A network of computer laptops is available for IT requirements.
    Generally, information about new passages and sites becomes public as soon as they are found, and shared amongst the expedition members (and eventually on the web site). Anyone can then decide if they want to become involved in the exploration: the person or group that makes the find may invite people onto the next trip or you can ask!.
    There are some very rare instances where the above process may not happen. For example, cavers who found Torca la Vaca near the end of the Easter 2008 expedition were sailing from Santander the next day. Other cavers explored 1.7km in the following days but left leads for the original finders to push in the summer. The location of this site was not made public until the summer explorations had started.

   Surface prospecting and digging are also vital parts of the expedition but they need to be researched before hand and should be tied in to the expedition objectives. Maps, digital cameras and GPS should be taken into the field, most often on a smart phone. (See Publications and Cave Marking below). The Matienzo Caves Project and a number of individuals have GPS equipment for positioning entrances. The GPS coordinates database of entrances can be uploaded into (at least) Garmin and Magellan units but you may need your serial or USB lead. The prefered GPS unit is an Android phone or tablet with OruxMaps loaded (see below)
   • GPS units must be set to ETRS89 or WGS84, and UTM/UPS - the coordinate system and datum used throughout the MCP documentation.
   If the device GPS track is recorded, especially in an area that is rarely walked, the resultant file can be importyed as a layer in the QGIS map.
   Digital photos and video can be downloaded onto the network-attached storage via the expedition laptops (or your own) for future web publication and/or presentations. There is also a QGIS digital map of the area, maintained with positions of entrances and cave centre lines. It is perfectly feasible, time permitting, to enter cave centre line data, add extra entrances and print the composite map out for underground or surface activity the next day. Large paper maps have been phased out and screen shots or print outs from the digital maps are now the norm. Many cave surveys are also on the Project's computers and can be printed out (or uploaded to a device) before heading underground. Printed surveys can be scanned.
   Android tablets and phones are used (with the Orux Maps application and downloaded Matienzo maps) to aid cave finding and entrance identification on the hills. See the Orux Maps page.

   We are extremely fortunate in having the use of an area in the restaurant at Casa Germán which acts as the expedition base / headquarters / office. This houses a computer network, a small part of the Matienzo Caves Project library and archive, and survey drawing-up area. The restaurant should not be seen as a general extension to the bar as Spaniards (and English) are paying to dine out!
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People
   Some members of the Matienzo Caves Project have a general responsibility for overseeing certain major aspects. However, individuals should see themselves as being responsible for their own safety and the tackle they‘ve used (sign it out, use it, bring it back, clean it in the river, put it away and sign it back in!), completing a logbook entry, survey drawing etc.

• Phil Papard: Matienzo Caves Project expeditions organiser, permissions (with Pete Smith), web reports for the main expeditions and Federation, grants, tackle.
• Susan Martin: Matienzo Caves Project treasurer
• Juan Corrin: General coordination of the Matienzo Caves Project (with Phil and Pete): web reports outside the main expeditions, IT systems, surface maps, computer/cave surveys, library, archive, web site, tackle.
• Pete Smith: Permissions, Spanish group liaison and archaeology

   The people above can advise on areas and / or caves to push, as can other regulars. Many members of the expedition have expertise in all matters speleological. A number have been caving around Matienzo for decades and will give advice and bull shit! Contact emails are listed here.
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Caving & digging - archaeology
   Personal caving equipment is obviously the responsibility of each caver. Carbide is not provided nor used. Cells and batteries can be charged in the tackle store on the camp site. Group equipment is the responsiblity of the team using it. If a system is detackled, the detackling group should normally clean the equipment removed at the river - not at the campsite, then sign it back in.
   Everyone should remember that cave formations and deposits are to be enjoyed by all. Hence, thought must be given to minimising damage to caves and the decorations when exploring. If possible, volunteer for any conservation or restoration activities that may be taking place.
    More often than not, digging is required to enter new cave. The expedition has a good supply of digging equipment. but it must be noted that a number of caves around Matienzo are important as archaeological sites and that digging may disturb prehistoric levels.
    Pete Smith has carried out research and excavations, working with Spanish archaeologists, and has catalogued various artifacts and paintings, and authored and co-authored many papers and books about the archaeology around Matienzo and beyond. Please keep your eyes peeled, looking at the walls and floor in any site that may have been inhabited. Pottery is especially easy to miss and tread on. The most common prehistoric pottery is black or black and red when fired (Bronze Age, 2000BC - 500BC).
    The expedition does not have permission to disturb archaeological remains. The dig must stop and any artefacts should be left in situ and reported to Peter, Juan or Phil so the appropriate authorities can be informed.
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Cave Rescue
    Procedures to follow for a call-out are found in the large blue folder labelled Permit, Caver Admin, Rescue on the shelves in the "MCP HQ" at Casa Germán.
    Each individual on underground ventures is responsible for his / her own safety and should have a blanket, spare light, etc. Sensible caving procedures should be adopted, e.g. lifelines on most ladder pitches, remembering that rescue is likely to be a protracted and possibly costly affair. Rescue call-out should be via Phil, Juan or the bar and then to the Guardia, if external help is required. A number of the expedition are current or ex-CRO, UWFRA members and would organise (at least initial) rescue procedures. Except for the simplest of rescues, it is likely that Spanish rescue teams would provide the expertise and man-power. It should be noted that rescued individuals extracted from a weather-related incident by a Spanish rescue team would be asked to pay if no regard has been paid to the weather forecast.
   (Cavers who are not part of a Matienzo expedition, i.e. have not donated, and perhaps "passing through", must ring 112 to organise call-out with the rescue authorities.)
    Taking out BCA Insurance, SnowCard, Dog Tag or a similar scheme is vital for peace of mind and pocket.  
People without caving insurance are not permitted to cave.
   Details of next of kin, insurance policy number, etc. are filled in on a data collection sheet, which you may find more convenient to print out and fill in before arriving in Matienzo. Otherwise you will be asked to complete the form in Matienzo before caving.
   Procedures for storing, using and destroying data complies with the General Data Protection Regulation which came into force on 25th May 2018.
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Caving Areas
   Within our 106km² area (Sept. 2024) there are caves and shafts of all sizes. The major cave networks are the 4 Valleys System (Sistema de Cuatro Valles), the South Vega System and Cueva Vallina. Current system lengths and depths are shown on the Summary Statistics page and also details about cave systems and entrances. We have collaborated with Catalan cavers in pushing Cueva Vallina near Arredondo to the south. Pushing these systems is a priority, as is finding new caves from the surface. The area does not have a great depth potential: the maximum is about 680m.
    The area map shows the main caves, roads and rivers. The following thumbnail descriptions aim to give a general feel of the area.
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The South Vega System (survey)
   Azpilicueta (0333) and Coteron (0264) are the high level entrances which drop down to valley level and emerge at Reñada (0048). Cueva-Cubio de la Reñada contains a river which resurges into the depression to flow across La Vega; some of this water could come from Hoyon (0567). Potential lies to the south (with Cueva Vallina already hydrologically connected) and to the west. It has been postulated that the Tejuelo system (already nearly 200km in length), to the south of Arredondo, could link with Vallina / South Vega.

North Vega (survey)
   Torcón de la Calleja Rebollo (Toad in the Hole - 0258) is a system which could go anywhere: northeast to link with Mostajo (0071), north and west into the unknown or even south to link with Reñada. Mostajo (0071) could go northwest to emerge in cave 0415, or north into the unknown. The caves are mainly dry but have large quantities of mud in the lower sections.
    The Cubija / North Vega System (Cubio-Morenuca-Regaton-Mostajo) is in a prime position for extension, and is still wide-open in places.

   The area of Cobadal may also connect through Sumidero de Cobadal into the North Vega System. The resurging river of Fuente Aguanaz (0713) (survey), 7km to the north is the current (dye-tested) resurgence for Cobadal water. Torca La Vaca is another stream and fossil cave which was found over Easter 2008. A 9 sq km area centred around Ideopuerta, may also feed into a possible Regaton, Cobadal, Fuente Aguanaz system.
    The low-lying area of Hoznayo (part of the permit from 2014) has provided the Torca Cañaos-Riocueva System which still has some potential.

The Four Valleys System (survey)
   Nearly all the water in the closed Matienzo depression leaves through Carcavuezo (0081), passes through Cueva Llueva (0114), with an entrance in Llueva Valley, and resurges in Los Boyonnes (0117) in Secadura. The cave is fed from water in Cueva Hoyuca (Uzueka) (0107) which in turn is fed by water in Cueva Riaño (0105). The major caves of Hoyuca, Riaño, Llueva, Llanío and Carcavuezo have been connected to form the 4 Valleys System. Some estimates put the potential passage at more than 100km. In 2022, Torca la Decepción in Matienzo was joined into Cueva Hoyuca and a Riaño-to-Matienzo through trip undertaken. The current length of the 4VS is over almost 77km with 18 entrances.
    The Five Valleys System is a possibility with Cueva Torno at Fresnedo nearly linked.

Muela/Mullir
   This area is approximately 4 km² of high level karst with little horizontal development. There are more than 200 known shafts, by no means all explored. There is plenty of surface prospecting and underground exploration waiting to be done, although the north-eastern part of the area was removed as part of the the 2014 permit reorganisation. If an integrated drainage system exists, the resurgence could be the one below Cobrantes (0110). It seems more likely that local networks exist with water resurging at various points around the mountain, e.g. at Ogarrio, and into known systems, e.g. Llueva, Carcavuezo.
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Publications and research
   The main publication is the Matienzo Caves Project website at www.matienzocaves.org.uk. A FAQ link from the front page has answers to many Matienzo Caves questions.
   There are more than 450 references to various articles (Spanish and English) and log books; some of these are in boxes in the back room of the bar. If you are interested in a site:
 - look in the card index where all explorations and accounts are catalogued and then
 - read up the various references.
   The books likely to be of most use for general reading are listed below in a short bibliography. (Full bibliography / webography).
   The log books from 1974 to the present have all been scanned and a database built up of all entries. The database can be searched in the Matienzo Office and online to show all log book pages relating to any site. See Logbook Search. Complete logbooks can also be browsed from this page.
   Maps are available for the whole of our permit area. Sections of the QGIS area map can be printed out and accompany everyone who is surface prospecting. Plastic wallets are available for weather proofing. (see Cave Marking, below). Cave passage and known entrances are shown at any scale. (Orux Maps is recommended as a digital alternative.)
    All sites' details are kept in a card index, paper archive and computer database and written up, along with logbook details, into the web site descriptions.
    A paper publication (Matienzo Underground) used to circulate, based on cave descriptions from the web site, and people added to it or amended it. Appendices ordered the caves by length, depth and altitude. There was also a paper list of the 'unexplored' sites, a list of digs, and sites of archaeological and biological interest. This was occasionally updated in a paper version.
   Nowadays, an on-line and download-able version of the descriptions (pdf files) is regularly updated and can be downloaded as 7 volumes. The appendices and other information can be generated when required using the Cave Search facility.

• Matienzo: 50 Years of Speleology, a 320-page, full colour, dual language book (with DVD and geological map) was published in August 2010. Details can be found here. This is now out-of-print, but is available to browse as a hard copy in the Matienzo Office and is also available to browse online.

• Matienzo Caves Project 2010 - 2019 - a 518-page volume - was published at the end of 2020. It is fully illustrated with maps, cave surveys and photos. More than 30 authors and 80 photographers have contributed, providing in-depth accounts of the explorations and scientific investigations, including palaeo-climate research, cave life, cave diving and archaeology updates, personal reminiscences and a full account of the expeditions' work over the decade. Available to purchase in England and Spain. (£26; 32€)
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Cave Marking
   It is very difficult to permanently mark sites without disfiguring the limestone! Before 1994 we used cow-tags which had painted and embossed numbers. However, there is now much less need to mark caves as personal GPS equipment (without the wobble) became useable in 2000 and now WAAS-enabled devices allow accuracy to 3 or 4m. The settings / datum should be UTM/UPS and ETRS89 or WGS84 to agree with the paper and digital map grids.
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Conclusions
   There are 5445 documented sites in the area and the potential for finding new entrances and passages remains high. But please remember to record your finds (describe, photograph and survey as appropriate) so that documentation is as complete as possible - to act as an incentive for future trips or prevent wasted re-exploration!
   A summary of the expedition aims and expectations, mainly for new expedition members, can be found here. A laminated card summarising the expectations is distributed to new members when they arrive in Matienzo.
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More information
   Contacts for more information are listed here or use the FAQ page.

Upcoming expeditions
   An online Google Sheet is available for each major expedition (Easter, summer) to show when people are going to be in Matienzo. Feel free to add yourself to the sheet or email Phil Papard or Juan Corrin with the details. It helps with planning, eg expedition objectives, other people organising dates, when to set up the office in the restaurant and when to have the expedition meal, etc. The sheets show the extent of each expedition (Easter 3 weeks; summer 4 weeks); the office and tackle store will be set up for the beginning and equipment put away at the end of each expedition. Links to the major expeditions are below and on the front page.

• Easter 2025
• Summer 2025

Shortened Bibliography (mainly in English)
There are regularly updated Matienzo Underground pdf files that can be downloaded. Hard-copy articles have not been produced in recent years, rather feedback articles for the Spanish authorities. These and other recent reports, papers and presentations can be found here.

(A) Fernandez Gutierrez et al, 1966. La depresion cerrada de Matienzo, Cuadernos de Espeleologia vol 2. 107pp + surveys & photos. The account of the original Spanish explorations.
(C) Kendal Caving Club/Manchester University Speleological Society 1975. Report of the British Expedition to Matienzo. 64pp + surveys + photos. The account of the expedition which surveyed about 15km in 6 months.
(T2) Mills L.D.J., Waltham A.C., 1981. Geomorphology of the Matienzo Caves. BCRA Transactions Vol 8(2), pp 63 - 84. Some speleogenesis hypotheses.
(T3) Smith P., 1981. Prehistoric remains and engravings discovered by the British Speleological Expeditions to Matienzo. BCRA Transactions Vol 8(2), pp 85 - 86.
(Y) Smith P., 1983. Iron Age Finds in Matienzo. BCRA Transactions Vol 10(3), pp 145 - 164. More up-to-date archaeological data is found for each cave in the Matienzo Update.
(BO) Corrin J., 1992. Matienzo '91 in Caves & Caving No. 55 , Spring 1992, pp 11 - 13.
(BR) Corrin J., Quin A., 1992. Matienzo '92 in Caves & Caving No. 58 , Winter 1992, pp 2 - 6.
(BZ) Corrin J., 1994. Matienzo '93 in Caves & Caving No. 63 , Spring '94, pp 24 - 27.
(CS) Corrin J., 1994. Matienzo '94 in Caves & Caving No. 66 , Winter '94, pp 10 - 14.
Corrin J., 1995. Matienzo '95 in Caves & Caving No. 70 , Winter '95, pp 24 - 27.
Corrin J., 1997. Matienzo ('96) in Caves & Caving No. 75 , Spring ''97, pp 16- 18.
Corrin J., 1998. Matienzo 1997 in Caves & Caving No. 79 , Spring '98, pp 31- 32.
Corrin J., 1999. Matienzo ('98) in Caves & Caving No. 83 , Spring '99, pp 26- 30.
Corrin J., 2000. Matienzo '99 in Caves & Caving No. 87 , Spring/Summer 2000, pp 43- 46.
Corrin Juan, 2001. Matienzo 2000. In Caves and Caving 89, Winter 2000/2001 , pp 24 - 27.
Ruiz Cobo Jesús and Smith Peter et al, 2001. The Archaeology of the Matienzo Depression, North Spain . In BAR International Series 975 , 224 pages.
Corrin J., 2003a. Expedition Report: Matienzo, Spain 2001. In Speleology Issue 2, May 2003, pp 17 - 19.
Corrin J., 2003b. Expedition Report: Matienzo, Spain 2002. In Speleology Issue 3, Sept 2003, pp 14 - 17.
Corrin Juan, 2005. Expedition Report: Matienzo, Spain 2003. In Speleology Issue 5, December 2005 BCRA, pp 10 - 14.
Corrin Juan, 2006a. Expedition Report: Matienzo, Spain 2004. In Speleology Issue 6, April 2006 BCRA, pp 20 - 23.
Corrin Juan, 2006b. Expedition Report: Matienzo, Spain 2005. In Speleology Issue 7, August 2006 BCRA, pp 22 - 25.
Corrin Juan, 2007. Expedition Report: Matienzo, Spain 2006. In Speleology Issue 9, April 2007 BCRA, pp 16 - 21.
Corrin Juan, 2007a. Expedition Report: Matienzo, Spain 2007. In Speleology Issues 10/11, December 2007 BCRA, pp 18 -24.
Corrin Juan, 2008 Expedition Report: Matienzo 2008. In Speleology Issue 13, May 2009 BCRA, pp 18 - 23.
Corrin Juan, 2010. Expedition Report: Matienzo, Spain 2009. In Speleology Issue 16, December 2010 BCRA, pp 12 - 16.
Corrin Juan and Smith Peter (editors), 2010. Matienzo: 50 Years of Speleology, 50 años de espeleología. Matienzo Caves. 320 pages.
Corrin Juan, 2011. Expedition Report: Matienzo 2010. In Speleology Issue 17, March 2011 BCRA, pp 8 - 11.
Corrin Juan, 2013. Expedition Report: Matienzo 2012. In Speleology Issue 19, December 2013 BCRA, pp 9 - 12.

Expedition Reports: Matienzo 2011 and Matienzo 2013 are with the Editor of Speleology

The Caves & Caving / Speleology references outline the discoveries. A full bibliography / webography is also available.
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Juan Corrin, December 2024