The hills surrounding the Spanish Village of Matienzo are of Cretaceous limestone.
Flowing across the impermeable floor of the basin is a river which comes out of the
limestone at the southern end and disappears back into the ground at the northern side.
The depressions two longest caves are just where you would expect to find them, behind the
resurgence and beyond the sink. These two caves have not always been known - it was in the
early ‘70s that serious pushing and exploration was started and it was only in August
1986 that the Carcavueso sink system was really opened up.
The 1986 British Expedition built on the effort of previous groups and succeeded in
increasing our underground knowledge of the region. Some 7km of new passage was discovered
and we connected together four caves to produce a system which is now Spain‘s 4th
longest.
But first the cave complex at the southern end which has kept cavers occupied for
years, both in the cave and above it. The top entrance to the South Vega System
(Azpilicueta - site 333) lies 300m above the Vega arm of the depression and the trek can
be tedious when carrying rope to tackle up the cave. Virtually all of the holes at high
level appear to have a phreatic origin - Azpilicueta is an exception. it is a relatively
young vadose cave which is a series of pitches separated by narrow and sometimes
meandering canyons. There is a short, stream-excavated bedding section at a depth of 140m
with a few formations. Downstream leads to the cave‘s finest feature - a 100m pitch
broken by a couple of ledges. The bottom of the big pitch marks the end of the vertical
section of Azpilicueta. From the bouldery chamber a number of passages radiate. The
Reñada, valley entrance lies to the north, but major passage goes off to the east and to
the west - where it is heading towards another major system (and hopefully a connection).
Spanish cavers have been exploring this system at Alisas and they have reached a depth of
about 300m and a length of approximately 3km. This year, Giga Hall beyond sump 1 was
entered via Azpilicueta and the second sump bypassed by burrowing through a choke.
Disappointingly, only half a kilometre of passage was entered with another sump barring
further progress towards Alisas.
The South Vega System now has a length of twenty kilometres, with four entrances. The
Azpilicueta to Reñada through trip is a minor classic and deeper than any such
traverse in Britain. The potential to the west is superb and future efforts should be
concentrated at this end of the system to link with the pot at Alisas and open up the
hillside, southwards, towards Arredondo.
Seventeen years is quite a time to have a caving area laid aside by Spanish authorities
for almost purely British exploration. The situation certainly wouldn‘t happen in
Britain - there‘s no way Ingleborough would be left for the Spaniards to explore. It
might be thought that this length of time would have been enough to finish off the area
but every year something appears which firmly puts down that idea. New cave passage and
entrances are often found right next to known caves. Two hundred yards from Uzueka (site
107) is another entrance in trees which was missed until this year. The 3m wide, 5m high
gaping aperture was discovered from inside Uzueka. So we now have another entrance - this
one cuts out the tight squeeze before Quadraphenia but has its own disadvantages involving
a spot of crawling and a hands-and-knees section through half metre deep mud.
As well as underground work, exploration above ground has also been carried out. The
first problem to be overcome in "shaft bashing” is finding and getting to them
when the ground is covered with a mixture of brambles, creepers, trees and gorse. A timely
fire just before the caving season clears the area and makes finding the caves quite
straightforward. One such area, within sight of the camp and two hundred metres above
Carcavueso, held half a dozen holes, one going to a tight depth of fifty metres. Another
surface search to fill in blanks in the three dimensional mazes that surround the
depression involved Torca de Mostajo (site 71), another complicated cave which quite
probably is going to "go big” In the future. The cave heads north along the
western side of the depression. To the west and north of the cave ties territory that is
incompletely trodden. The depression of Cobadal is apparently floored with sandstone that
drains water towards Mostajo and Matienzo with very strongly draughting holes. This years
expedition saw the opening up of a couple of these but they all, disappointingly, closed
down. There will be more visits to this area in the future.
And so to the main story of the 1986 expedition - the connections in the Four Valleys
System. When Lank Mills first visited the area in 1969, the only speleological hints for a
world class cave was a river sinking at Carcavuezo, a river resurging at Secadura, 3km to
the north-east - and lots of horizontally bedded limestone in between. The straightforward
objective was to enter Carcavuezo and emerge at Secadura - the reality has been much more
complicated and has taken 17 years to explore at least some of the possible connections.
The major, present day hydrological links have been gradually uncovered over a number
of years. The river in the Matienzo depression sinks at Carcavueso (81) and drains into
Cueva Llueva (114) in Llueva Valley. The entrance to Llueva, a large opening filled with
vegetation and lined with over-hanging beds of limestone conceals a small hole which
draughts strongly. It is possible that water once resurged into the valley. The cave has
seen much activity over the last few years - divers have passed the upstream sump and
explored a number of kilometres of old, large passage heading westwards back towards
Carcavuezo and Uzueka. The water in Cueva Llueva disappears into a bouldery downstream
sump and is next seen in a short, underground heap of rocks at Secadura (site 117).
Matienzo, Llueva and Secadura are three of the valleys: the fourth valley is that of
Riaño. The two major caves here are Cueva Riaño (105) and Cueva Uzueka (107). Water in
Cueva Riaño flows westwards and resurges but there is also water in the cave which flows
to the east and links with Uzueka at a low point opened up this year. Cueva Riaño was
also extended in large, old passage which is incompletely explored. The connection with
Uzueka added 5km to Uzueka's 17km length and at the start of the 1986 expedition made it
the longest of our caves.
Uzueka is a major horizontal network. First entered in 1974, it has been extended
southeast towards Matienzo and towards Llueva - the water was dye tested to Llueva and
then to Secadura but there was no entered passage between any of these three caves. During
the last ten years much work has gone into extending passages at the end of Uzueka. The
trip of four hours, one way, is quite arduous and pushing at the end involves squeezing in
and around boulders - but the end was seen to be within a few tens of metres of Llueva.
The big push to link Uzueka and Llueva this year involved about a dozen people with the
team and circumstances providing the winning combination. A group of three in Llueva
beyond the sump pushed on through an unstable boulder choke; one of the groups in Uzueka
heard Terry Whitaker talking and the link was forged by re-positioning a few of the
unstable rocks. The Uzueka-Llueva connection brought to an end one facet that the Matienzo
expeditions have had and we would have been satisfied with that one objective achieved.
The length of the system jumped to 29km and it became possible to enter at Cueva Riaño,
pass into Uzueka and emerge at Llueva, perhaps 6 hours later after free diving the 7m long
sump.
The link and through trip is unlikely to prove popular at present. While surveying,
boulders were heard moving in the choke, apparently closing off the connection.
As often happens in caving, new faces can bring a fresh approach and enthusiasm to
looking at old caves. Carcavuezo was the place where the unexpected was uncovered. The
river at Matienzo sinks, a short distance from the campsite, into an impenetrable mess of
boulders. After heavy rain the small holes cannot drain the swollen river and so, to try
to cope with the flooding problem the locals have dug a large trench which carries the
overflow a couple of hundred metres to another sink. This is a heap of decaying logs but
on the bank to one side a small hole can be excavated of its annual debris deposits to
eventually lead down, through draughting passage, to the underground river. Carcavueso was
first dug out and entered in the early 1970's, and it takes little imagination to
visualise these slimy-walled passages, with rubbish squashed into roof cracks, full of
flood water. Andy Hall, Jim Davis and Simon Chandler on a scouting trip into the cave came
across a small drop down on the right of the river which led to a tortuous and flood-prone
route between boulders. They popped up into a roomy passage which was still open and going
when they emerged a few hours later with the good news. The next day a large team was
assembled and split into three groups to push and survey the most obvious routes. The link
through to Cueva Llueva was discovered and more open routes were noted.
The passages have obviously played a major role in the drainage of the depression and
the surrounding area in the past. There are signs of water flowing over sand and mud banks
- although it is unlikely that anyone will be able to see it. Water flowing at this level
(about l0m above the sump) would probably mean all access being cut off in the bouldery,
low level entrance grovels.
Carcavuezo was eventually linked with Cueva Llueva in three places and provides a drier
route to the far reaches of western Llueva which has major potential. With the cave being
opened up in the latter part of the expedition, the exploration and survey were carried
out hastily. There is still exploration to be undertaken in the cave and it, no doubt, has
a few more surprises to unfold. It is quite likely that the relatively easty access in
through Carcavueso will produce another Llueva-Uzueka link in the Trident Passage area.
The two caves seem to virtually overlap on the survey!
There is no doubt that the 1986 expedition has provided a climax in a series of
parallel caving explorations carried out over the last 17 years. The 32km long Four
Valleys System is now an almost integrated complex of caves where it is possible to travel
underground through to 3 of the depressions. The Llueva-Secadura connection to the
resurgence has yet to be opened up.
Acknowledgments
As usual, in a team effort spanning several years, no one person or expedition can
claim to have done everything. Each discovery builds on work carried out years before,
often by individuals not now involved. This years major connections were achieved as a
result of the searching and explorations of this and the previous expeditions.
Over the years, a great deal of generous hospitality has been shown to visiting cavers
by the inhabitants of the village especially Germán, Cuca and their family at
Germán‘s Bar. Cave entrances have been pointed out, and some joint exploration
undertaken, meals have been given, football matches played (we lost this years
international; a couple of injuries resulted in an early return to England), tasks shared
and even sick beds provided for the really ill. One major facility is the camp site. The
other asset to the work of the expeditions is Germán‘s Bar itself, not just for the
obvious but for tables, space and electricity for computing and drawing up surveys and for
charging lamps and batteries for filming and photography. (Whether gee-whizz technology
actually helps to find caves is debatable. A video camera has been used on this and the
last expedition. A film team was in Carcavueso extension before the still photographers
could get in. But computers can help the processing of survey data and its drawing up.
This year a BBC micro was setup in the back room of the bar and was used to produce
immediate printed line plans and projected sections from raw underground survey notes. The
surveys printed here (with grid north at the top) contain about 2000 survey points. At
this scale, each square being 1km, detail is non-existant. But using the computer enables
surveys to be drawn out from the same data at any scale - even life size. )
Many others have helped to generate the welcoming atmosphere including Spanish cavers
who visit Matienzo giving advice and encouragement. The groups try to repay these
kindnesses in some way. A slide show of the caves and a video of last years expedition
were shown to packed houses in Germán‘s and the Snows. This was the first time that
many of the villagers had seen what their underground scenery was really like.
Of a more practical nature, the expeditions also carry out caving jobs that are of
direct use. The only water that Matienzo and indeed other neighbouring hamlets has, comes
from underground sources and so, on a number of occasions, the expeditions have laid
plastic pipes into underground pools trying to reach a higher water level to provide as
much head for taps as possible. This years job involved diving to recover a steel pipe
from the main resurgence into the depression.
We wish to acknowledge the encouragement of the Ghar Parau Foundation which awarded
Sports Council and GPF grants to a total of £635. We are also grateful to the Diputacion
Regional de Cantabria and its Director, Luis Sellers Arana, who supplied the permit.
In July 2024, the Connections: Matienzo 1986 VHS video was digitised and put online.
Immediate bibliography:
- Matienzo ‘81 C&C 14, Nov 1981
- Matienzo 82 C&C 18, Nov 1982
- Matienzo ‘83 C&C 22, Nov 1983
- Matienzo 84 C&C 26, Nov 1984
- Matienzo ‘85 C&C 32, May 1986.
These contain area maps and references to the dozens of other articles published.
|