OUCC Proceedings 12 (1986)

Pozu las Perdices (F7): Description

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by Ian Houghton

Location: 1° 15`39``W, 43° 13`36``N (F7c);
Altitude: 1866m
Exploration: Discovered and explored to Achilles/ Executioner 1983
Explored to Jorcada Blanca and surveyed 1984

Entrances

The three entrances are all within 40m of each other on a limestone pavement dipping at about 20° , approximately 210m distant from Top Camp on a bearing of 250° . The pavement is that leading from Pozu Jorcada Blanca down to the large scree-filled depression near Vega Aliseda. Sightings from Perdices give 113° to La Verdelluenga, and 204° to the peak of Jorcada Blanca. If you are still unable to find it, you are either encased in mist or on the wrong mountain. The entrances are painted F7a, F7b and F7c. The first entrance is a deep snow-filled gash, some 10m long and 3m wide, leading into a beautiful ice cave. The second entrance is a square shaped 3m x 3m shaft, intersecting a rift, and the third entrance is a tunnel onto a short pitch. Snow conditions may make recognition difficult

General Description

Perdices provides a second, lower, entrance to the Jorcada Blanca system; it is a 450m deep trip to reach the stream cave, entering via the Hot Tub aven. Perdices is a much easier entrance than Jorcada Blanca and gives a most enjoyable sporting trip. Attractions for the visitor are the 112m free-hanging Hot Tub pitch, the Sky at Night chamber with its huge aven and house-sized boulder, the elegant, damp, 80m Nostril pitch, and the wet and technical Bogey pitch. There is also some free-climbing, a few cascades and two short squeezes. Form the bottom of Perdices to the final sump of Joracda Blanca involves some 580m of horizontal passage and 70m of descent, with four short pitches. Jorcada Blanca does provide a few difficulties, these being the rift climb and traverse immediately after the Hot Tub, and the 20m section of cave form the Vortex squeeze (very tight) to the base of the final pitch, Armageddon, which is also tight. This whole section is very wet and draughty, and the 9m Vortex pitch is very awkward with a horizontal serrated flake half-way up in the water to snag ladders or rope. As the cave guides say, an accident here could be serious. Further details of Jorcada Blanca are in OUCC Proc. 11.

If the cave were rigged, and the route known, a fit solo caver could reach the sump in about 3 hours, and exit after a total of 7 hours. A trip to the bottom of Perdices and out would take only about 4 hours. Perdices could be rigged and derigged in a day by a small party using lightweight rope.

Cave Description

Of the three entrances to Perdices, only the higher two can be considered as normal routes into the cave. If not blocked with snow, the middle entrance (a shaft intersecting a rift) provides the easiest route, following the rift downwards, bridging over the snow. A phreatic tube entering from the right from the upper entrance is passed and, after a steep bridged climb downwards, a rock floor is reached with a squeeze at floor level providing the way on.<ql> <em><em>The upper entrance has a tunnel approach that protects it well from the snow, though in 1984 it was nearly blocked. This entrance has an 8m pitch, followed by a few metres of passage to a fork. Both routes rejoin after about 15m at a small chamber. At the far end of the chamber behind a boulder is the phreatic tube which can be crawled to the rift of the middle entrance. Below the boulder is a climb downwards in the rift for 14m that lands at the floor-level squeeze.

After the squeeze, a narrow rift is encountered. Although this can be passed by climbing up for some 5m and squeezing through, easier progress can be made in higher passage higher up in the rift. The rift emerges onto a 10m pitch (Strangeways). At this point the cave widens, and an enticing draught (upwards) is noticed. Strangeways lands on a ledge in the middle of a rift, with two ways on. Left, facing out, is the Executioner; right is Achilles.

The Executioner route involves a 3m climb downward, followed by a traverse over a 7m blind pot to a 19m free-climb into a narrow abandoned stream bed. This leads immediately to the Howler, a strongly draughting hole leading downwards to a tight squeeze, immediately followed by a pitch into the Achilles route.

The Achilles route is the more sensible choice, involving a walk over boulders until the floor disappears down a rift. The rift can be followed directly as a 13m narrow pitch using a bolt belay; alternatively, a wide traverse (easier than it looks) can be followed to the far end of the rift. The rift carries a small stream, and can be climbed upwards for 60m to a choke. Sporting climbs down the rift enable the 13m pitch to be bypassed. A 22m pitch follows, landing near the base of the Howler pitch from the other route. The landing is a small ledge with a stream. An airy traverse round the corner (bolt protection) leads to a flake belay with a tiny, but perfectly positioned ledge providing a good take-off for a superb 36m free-hanging pitch (Obelisk). At this point the cave starts to enlarge further, to approx. 5x10m.

Obelisk lands on a ledge, where once stood a 2m high rock tower. Unfortunately, attempts to belay to the tower showed it to be less solid than desired, or expected. The demise of the "obelisk' means that the next pitch (11m) is most easily rigged using a deviation on the rope above.

This drop lands on a substantial ledge, with a 2m long and m wide hole in its floor, down which the stream runs. This is the Nostril, an inclined 80m pitch that is against a smooth wall and rather dribbly and damp. The pitch becomes unpleasantly wet on hot sunny days at 3-5pm, when the snow starts to melt. The Nostril lands in a chamber / aven, the largest flat area encountered in the cave so far, measuring about 25m by 4m. A 55m pitch follows. The direct descent is both loose and wet, so a traverse round the left-hand wall, to a set of natural belays, is advisable. However, a very wet aven enters from above here, rendering this descent equally unpleasant. We used this route, although a better descent line exists between the two waterfalls.

The next pitch (26m) is followed by a tight rift, combining a crawl and squeeze, affectionately called the Bastard. This is followed by a 22m pitch in a loose but wide rift onto a large jammed boulder. Climbing down 6m to the stream leads to a rising traverse and a 23m pitch into a huge chamber, The Sky at Night. The chamber measures some 35m by 14m, but this is not its noticeable feature. Access to the chamber is almost completely blocked by a boulder, 5m high, jammed across the 4m wide rift, and it is necessary to climb under it and exit through a gap at its top. A vertical cliff is then encountered; a second, much larger, boulder, 8m high, 6m wide and 4m deep. Fortunately the chamber is 7m wide here, and it is possible to climb up past it. A huge aven enters here, and the feeling of space is such that the chamber seems outdoors. The walls rise vertically out of light range with no indication of a roof or narrowing down.

A small passage leads off to the final pitch, the Hot Tub. This is the finest in the cave, a completely free-hanging 112m drop, with a large aven above. A substantial waterfall can be made out on the far side of the pitch at the top, but it is too far distant for the spray to reach the rope even on such a long pitch. The walls disappear out of sight almost immediately, leaving the caver with no other means of judging the rate of descent other than by watching the rope. The pitch lands in the boulder chamber of Jorcada Blanca, named the Hot Tub because of the cold draught caused by the waterfall previously mentioned, which lands in a corner of the chamber. The exploration limits in Jorcada Blanca without tackle are Lago Victoria upstream and Pol Pot downstream.