Cave exploration around Matienzo during Easter and summer 2000

Four Valleys System
   At Easter, a substantial length of stream passage (264m) was entered up a 15m aven at the end of Shrimpbone Inlet in Cueva Hoyuca (0107). The two long trips at the far end of Hoyuca found the passage dividing and ending at a number of avens. Some unexplored passage remains to be pushed. During the summer, work was concentrated around the entrance passages where the unexpected, low level Wildlife Series was entered down a pitch, 10m from the squeeze into the start of Quadraphenia on the main route. About 300m was surveyed here, bringing the total length of surveyed passage in the Four Valleys System to 42853m.
   Site 1496, in an interesting position over Hoyuca, is a draughting low crawl and this was partially excavated in a wide bedding.
   The main road improvements through the depression have cut back into the limestone in a number of places, exposing a number of interesting holes. The road-side dig, site 1452, was excavated at Easter to the head of a 70m pitch which dropped into Cueva Bollón (0098). Upstream exploration was attempted during both Easter and summer, but the water levels appeared too high. A prolonged period of dry weather is required to make progress through the aqueous boulder choke. This top entrance will be preferable for attempting to extend the cave rather than the old, bottom entrance route that needs diving gear to pass three small sumps.
   Just 100m up the road from 1452, "The Road Show" (site1506) was entered at the end of the Easter expedition. This 50m segment has good formations and a possible dig.
   Cave of the Six Shafts (site 0543) was finally relocated and partially re-explored after being "lost" for 23 years.

North Vega and El Naso
   Cofresnedo (site 0065), a prominent entrance and large passage on the northwest side of El Naso, has been known and probably used since humans first encountered the enclosed depression. Various artifacts and human remains have been found in the cave and Spanish archaeologists now have permission to excavate in the cave. The cave was inspected in the summer so that digging could start in the autumn.
   A fair amount of prospecting work was carried out on El Naso and various new and old holes were descended. There are some areas where complete re-exploration and re-positioning will be needed as the GPS is showing up descrepancies.
Site 1572 was first spotted while sitting outside the Vega bar looking at the southern side of El Naso. High up in cliffs above Cueva Rascavieja, the prominent entrance seemed to be rather difficult to get to. As it turned out access was via an easy climb down a stepped limestone pinnacle. The cave turned out to have a 5m high and 3m wide entrance, with phreatic passage rising to a crawl and choke after 30m. To the east, a number of small animal shelters all choked.
   Some digging was carried out in sites 0813 and 0815 where good draughts promise a link with the North Vega System below.

South Vega and Seldesuto
   Extensions in Arenal (site 0035) were surveyed and pushed beyond the Foam Dome over Easter, Whit and the summer, working with the cavers from the Catalan caving groups.
   A number of sites were explored on the South Vega hillside during Easter and a couple held exciting prospects for the summer (1338 and Torca de Papá Noel 1471). As it happened, site 1338 was tackled up but not pushed and efforts were concentrated in Papá Noel. Over 2.2km was surveyed in this 225m deep system. The entrance series lies over the hub of the South Vega System where Torca de Coteron links with Reñada and it was thought at one stage that a giant boulder choke could provide a link down into Coteron. However, the cave has headed west and is apparently very close to the Coffin Levels in Torca de Azpilicueta. The cave has some very large and impressive sections and may eventually provide a number of routes to different sections of the South Vega System. There are a number of leads to push.
   More prospecting and shaft descending was carried out during the summer. For example, site 1538 has a shaft and cave entrance into a small chamber with a descending rift that chokes. In another hole, 1542, 30m of stooping and crawling ended in a low chamber with gour pools.
   One of the draughting digs up the Azpilicueta track at Seldesuto was continued and another couple of promising roaring holes were discovered only 60m away.
   At Easter, Martin Holroyd carried out a couple of dives in upstream Vallina - breaking surface into a short canal at the end but then meeting the next sump. 230m was surveyed.
   In Cueva Coquisera (Cueva Codisera - site 0039), the top shaft entrances were finally surveyed though to the main cave, but this exposed a glaring error in one of the original (British) surveys. Cueva Abono was linked to a top entrance, 1470
Cueva Tizones (78) was "finished" at the high level, adding 156m to the length.Jivero 1 was dived through and linked to site 246.
   At Easter, Sima de la Garma de los Trillos - site 1176 or VT62 was explored and resurveyed after an invitation from the Catalans. The cave is draughting strongly and in a prime position to link into Vallina or the South Vega System. In the summer, efforts were diverted elsewhere and this site remains to be pushed.
   In Torca de Reguilon (site 0046) a bolt route was started part way down the 70m entrance pitch to a possible passage.
In Cueva Copudia (site 0265), close to Torca de Coteron, a descending rift was explored along a joint at the back of this very large fragment. At one point, a draughting, 30m deep but very narrow joint was seen. In site 311,  a draughting dig was pursued above a previously exposed 30m pitch eventually leading to the route dividing at a flake. Above site 311, site 1512 involved a crawl to a pitch into a damp chamber where the water disappears down a narrow meandering passage that needs enlarging.
   Cueva de los Cantones (site 865) was explored in 1991 with some going leads in its length of 1716m and 285m depth. This year the site was "given" to the Catalan group to explore. After tackling up the pitch down through the main, loose, bouldery chamber and returning the following day, they found that the rope had been cut by a falling rock. Enthusiasm dropped to zero and the Cantones "gift" has been returned!
   Below the Cantones depression, Cueva Adillos (site 0034) was rediscovered and explored but the new site 1514 - an old phreatic fragment - was explored through 3 entrances in 2 to 3m high and wide passages. In places throughout the 112m length, the bouldery floor deposits had been stacked on the side and fragments of old pottery were found.

Muela
   Shaft 320 has had a chequered history since 1981, from being a 90m undescended pitch to a 4m climb to a draughtless choke. Last year and this saw the site finally being pinned down, lumphammered and explored. Despite enticing noises from falling rocks, the shaft turned out to be only 27m deep.
   Various small shafts were explored and site 169 resurveyed. In two "new" areas in or near the woods a kilometre down to the east of Mullir, some interesting draughting digs were investigated. Nearby at site 1570, 40m of walking-size passage was entered, and Mistletoe Pot (1575) was explored down an 18m pitch into a 16m pitch lined with soft calcite with a low, well decorated crawl half way down.

   Once more, there were more questions raised for next year than were answered in this one.

   The Asociación EcoCulturas (http://ecoculturas.cjb.net - defunct) held a series of meetings over a fortnight involving the villagers and trying to understand and preserve cultural activities and the countryside around Matienzo. As part of their fact finding, the group asked to be shown a variety of caves. On one afternoon the group was introduced to the geomorphology of the Matienzo depression, taken through Cueva Jivero 2 with its population of crayfish and shown Cueva Molino as an example of a old and large cave sink also with a level of calcited bones. On a second afternoon a large group visited La Cuvia as an example of a cave currently being used by a farmer and as a typical Matienzo dry "tunnel"; the second site visited was Las Grajas, a site excavated by Spanish archaeologists, with pottery and charcoal in hearths.

   We were welcomed by Pablo at Bar German and the expedition is grateful for the camping facilities and the use of the restaurant for computing and drawing up.

   The list below shows links to those 232 sites which were extended or newly discovered over Easter and the summer, or which have had surveys updated, entrance photos added or entrances repositioned with a GPS.

 0016  0017  0033  0034  0035  0039  0040  0042  0046  0033  0059  0065  0068  0075  0079  0081  0083  0084  0086  0089  0091  0094  0098  0104  0105  0107  0114  0128  0168  0169  0179  0184  0207  0246  0264  0265  0266  0267  0297  0307  0308  0309  0310  0311  0320  0333  0343  0345  0351  0352  0353  0360  0387  0397  0405  0412  0413  0415  0439  0457  0458  0487  0489  0543  0561  0596  0623  0679  0715  0724  0733  0774  0813  0815  0865  0879  0885  0896  1015  1034  1106  1107  1176  1199  1216  1217  1272  1274  1275  1298  1319  1332  1338  1379  1385  1386  1387  1390  1410  1411  1440  1452  1454  1460  1461  1462  1463  1464  1465  1466  1467  1468  1469  1470  1471  1472  1473  1474  1475  1476  1477  1478  1479  1480  1481  1482  1483  1484  1485  1486  1487  1488  1489  1490  1491  1492  1493  1494  1495  1496  1497  1498  1499  1500  1501  1502  1503  1504  1505  1506  1507  1508  1509  1510  1511  1512  1513  1514  1515  1516  1517  1518  1519  1520  1521  1522  1523  1524  1525  1526  1527  1528  1529  1530  1531  1532  1533  1534  1535  1536  1537  1538  1539  1540  1541  1542  1543  1544  1545  1546  1547  1548  1549  1550  1551  1552  1553  1554  1555  1556  1557  1558  1559  1560  1561  1562  1563  1564  1565  1566  1567  1568  1569  1570  1571  1572  1573  1574  1575  1576  1577  1578  1579  1580  1581  1582  1583  1584  1585  1586  1587  1588  1589  1590  1591  1592  1593

   A quick trip in October updated or discovered the following sites:
 0058  0070  0202  0204  0224  0496  0534  0535  0536  0561  0623  0965  0966  0967  0968  1594  1595  1596  1597  1598  1599  1601  1602

   A trip in December updated or discovered the following sites:
 0059  0065  0071  0081  0085  0086  1600  1603  1604  1605  1606  1607

Juan Corrin, September, November, December 2000