Tolminski Migovec Cave Exploration

SLOVENIA

SLOVENIA

summer expedition 2000

summary

Despite adverse weather conditions, the Imperial College Migovec 2000 expedition's overall achievements were very good; around 2km of new cave was surveyed over a combined depth of 900 metres, the main system is now 11.3km long. A total of 20 people were on the mountain for between 2 and 6 weeks, with experience ranging from 1st year students to seasoned expedition cavers. Once again excellent relations were maintained with the local cavers, with two joint trips being carried out. The traditional end of expedition party, to thank the local cavers and local farmer for their invaluable help, was also very successful.

exploration

explorations in the system - level 2 and exhibition road

Of the three big pitch series remaining in Level 2, the Paradiso Series continuing below Bare Necessities (-430m, 1999) was explored via two large pitches to an impassable rift at the bottom of Hole in the Hill, -575m, while Mig Country leading to Rock and Roll (-300m, 1996) was explored via an active streamway to a series of small pitches. The streamway then bizarrely diverged and disappeared down several impassable rifts at just -330m. At the upper end of Exhibition Road the Asterix Series (-370m, 1999) had two leads; one was pushed down a short pitch to a wet impassable rift, while the other lead remains unexplored.

ncb passage

This part of the system, which is interesting because it has the most Northerly leads, has been left largely untouched since the breakthrough to Level 2. This year only two leads were explored; Leki Pot (-170m, 1999), which was quickly concluded, and Dodge City (-120m, 1996), which is more promising containing two possible leads which require hammering.

pri madoni

Pri Madoni is an impressive cave situated on the West cliffs, about 100m below the level of the ridge which runs along the edge of the plateau. It was discovered and explored by the Slovenians in April of this year and currently stands at 600m in length and 380m in depth. The key this year was finding the right route to abseil down to the entrance, as the Slovenians preferred to get to the entrance by climbing 200 metres up a gully. The full length of the cave was then surveyed and its position fixed, relative to the main system. In the cave there are a couple of good leads possibly heading back towards the system as well as an obvious continuation downwards.

gardeners' world

Gardeners' World was an exciting discovery, only looked at from the surface in previous years. The entrance is 60m below M2 (highest entrance to the system, alt 1845m) on the East side of the plateau. After a relatively tight entrance series the cave opens into an impressive fossilised rift passage and then descends very quickly through a series of big pitches. Continued exploration of this cave next year will probably require an underground camp. This year it was explored to -393m and a length of 787m. In addition the cave is not more than 100m from the main system.

plateau

Smaller discoveries on the plateau include U-bend 571, which is directly above Pri Madoni, and is currently -70m. Other surface holes were found and noted. The hope is of finding caves that may bridge the gap between the main system and other caves on the plateau.

aven climbing

There are numerous interesting leads which require aven climbing techniques. Unfortunately this year problems with our charging equipment meant the drill battery could not be recharged and this combined with a lack of thru-bolts prevented us carrying out any such exploration.

dye tracing and surface surveying

Part of the problem of the new surface discoveries was linking them into an overall 3-dimensional survey, so we knew how close the other caves were to the main system and how they were co-ordinated relative to other known caves. This required a considerable amount of surface surveying, and, in the case of Pri Madoni involved an exciting abseil into the Tolminka Valley to locate the entrance. Scientific work consisted of the on-going task of trying to pin-point the resurgence for the main system - unfortunately we were unable to get hold of optical brightner for dye-tracing before our departure. Current understanding of the cave hydrology is still sketchy, but recent information from a hydrologist contacted in Lljubjana suggests the presence of an impermeable layer dipping at a shallow angle to the North which is preventing water from the main system resurging into the Tolminka. The lack of any definite positive dye-tracing result in the Tolminka, despite repeated attempts, and the three sumps Water Hope (-970m), Pencil Sump (-967m), Good Not Grand (-959m) may testify to this. Control detectors were placed in the sources of the Savica river (see figure 1) after a positive result was recorded there in 1999. The Savica resurges 5.25km to the NE (alt 775m), and the aim was to detect any external pollutants in the water that may give a false positive result. Unfortunately bad weather ensured the detectors were quickly swept away.

conclusion

With the discovery of two new caves the focus of exploration has shifted from purely the main system, to an interest in cave development on the plateau as a whole. Meanwhile the mystery of where the water from the main system resurges has still yet to be resolved. With the success of this years expedition there is a considerable incentive to go back and continue exploration next year.

the usual suspects

Thomas Ayles(Leader), Tadej Begus(JSPDT), Colm Carroll, Bruce Drinkwater, James Evans, Mark Evans, Jan Evetts, Andrej Fratnik (JSPDT), Hilary Greaves, Clewin Griffith, Stefan Holmgren, James Hooper, Ben Johnson, Helen Jones, Andrew Jurd(Treasurer), Peter Jurd, Martin McGowan, Ben Ogborne, Martin Pattenden, Hugh Penney, Dejan Ristic(JSPDT), Mike Rogerson, Timothy Wright.