Tresviso 1986

Howard McKee & Tim Nicholas

Originally appeared in Caves and Caving No. 37

This years expedition was organised by members of the previous one in a misbegotten flush of enthusiasm, after a suitable period of absence from the peculiarities. As the summer loomed however, the memories of Dossers were apparently rekindled, and by the day of reckoning there was only one of them left who unsurprisingly had not ventured far inside. Numbers in fact dwindled so rapidly that we were left with only 12 members, 1 who didn't go caving, 1 who did one trip and wisely left for a nearby expedition, the leader who had never been abroad (the old one also dropped out), 3 from ULSA, 1 from Imperial, with the remainder loosely associated with LUSS.

This size of expedition was bound to be much harder work than the previous ones, and some old ideas such as detackling in stages had to be abandoned in favour of 'grab 2 bags and exit'. On former LUSS Picos expeditions the number of cavers has frequently exceeded the requirements necessitating a queue, but we were hard pressed to check out the objectives in Dossers. The object of this year's jaunt were to check out some of the leads in Dossers, do some Dye Tracing, Photography, and generally continue with surface exploration of the area. It was realised that with the manpower available, Dossers would prove to be a major undertaking, and hence it was decided to concentrate on this, whilst pursuing the other aims in parallel from those having 'off' days, or the less able. Tackling got off to a slow beginning, the first trip failing to find it, and continued in fits and starts, with perhaps more of the fits.

As only one person had been in it before, the effort necessary to tackle the hole was underestimated and exacerbated by the need to re-rig a lot of the pitches. The 2 potential leads were at -600 and -800 metres, and it was not till the 2nd week that we were in a position to check the 1st. From the secondhand verbal description given by its finder we had hopes of an abandoned series to bypass the last drop and sump, similar to what was found in Sima 56 in 1980; but alas this was not to be, the large phreatically formed passage was pleasant and nicely decorated unlike the rest of Dossers but it proved to be an oxbow, reappearing after 100 metres at a point in the roof above Thunder Down Under. The other possible leads at the bottom always considered to be a long shot, proved to be similarly elusive, a 'possibly diggable'(!) stream sink was too small to enter, whilst another That no major system has been found since 1981 in the area would appear to indicate that the days of finding such by simply wandering about on the surface are gone, and future extensions may well necessitate the methods common to most British discoveries.

The validity or feasibility of this at any great depth should be questioned if for no other reasons than the virtual impossibility of rescuing anyone who was injured, and the time and effort that would be needed for such. An underground camp was again employed, but as so often happens no sooner than it was established than the bottom was attained, which is perhaps as well because the super efficient petrol stoves refused to function leaving us relying on a solitary alcohol cooker. Around the middle of the expedition spirits were at a low ebb, as the ancient landrover expired leaving us to make do with the dried food intended for the underground camps (hence was somewhat lacking in variety);

Dossers was a dirty word; and half the team were to return to the UK. Despite an inordinately large budget for pictures, the photographic trip gave up at the camp, and half the photos didn't appear because the camera was on the wrong setting, not that the hole was particularly photogenic though! More unfortunately however, the programme of dye tracing had to be abandoned because the stream in Dossers was literally minute, and had to serve as the supply of fresh water; and it was not till the 3rd week that we were in a position to insert the dye, leaving an insufficient period for the anticipated flow through time. An added complication was the presence in the resurgence cave, Cueva del Agua, of a diving expedition which might not have been too keen on the effects of a pulse of Rhodamine on the visibility.

The problems of a water supply in Dossers became acute as inevitably the stream came to transport undesirable substances, which could have contributed to the wide-spread incidence of debilitating 'Picos guts'. In addition to the diving team from the UK there was contact with a sizeable motley of cavers of various nationalities, largely due to the UIS congress in Barcelona. A well known antipodean SRT pioneer experienced a shallow but epic length trip in Dossers, and promptly fled. A small Alpine style Belgian team were tackling the former LUSS discovery of Sara, and much to our chagrin found a considerable length of new passage. Prompted by this, another early LUSS discovery, Mazarrasa, was retackled providing some variety but with no appreciable result. The programme of surface exploration was continued towards the limits of the presumed catchment, and produced over 40 entrances most of which were block choked and only one of which exceeded 50 metres.

Clockwork Pot (a good wind up) appeared to be going nicely but the rising optimism was abruptly deflated at the head of a further pitch by the discovery of a rusty bolt. This pitch was suspected to have been reached by another entrance, and could be one of the imprecisely documented holes discovered by a French team working in loose conjunction with LUSS in 1979. A lengthy period of poor weather hindered the search for new holes, and the expedition terminated, having failed through no fault of its own to have located a single substantial lead to return to. That the area has potential is proved by the many deep systems, and the extensive resurgence cave explored in previous years; but whether that 'Spanish Swinsto' will ever be found is the great unsolved mystery, and the prospects of success perhaps no longer justify the large and costly expeditions as in the past.

The way ahead as with Himalayan climbing would appear to lie with the lightweight small and flexible alpine style methods that are becoming more important, at least as regards prospecting; but with the disenchantment and dispersement of most of the long term head-cases this appears to mark the end of an era for LUSS in the Picos. The best prospects for further extensions to be in the careful re-examination of the early and perhaps incompletely explored shafts, and the Cueva del Agua; and the diligent continuation of surface prospecting.