NPC Newsletter (2nd New Series) No. 45 - November 1998

Slovenia 1998: System Migovec

Over the summer five members of the NPC joined the Imperial College Caving Club (IC3) expedition to Slovenia. This is the fifth year IC3 have been to the Migovec Plateau, in the Julian Alps near Tolmin, to continue the exploration of the Migovec System which they discovered in 1994. After the previous 'this is it lads, 1000m' years this really was going to be the 'this is it' year. Well almost but not quite.

System Migovec now stands at a depth of 970m and a total surveyed length of 9.46 km. The theoretical depth potential to the probable resurgence in the Tolminka valley is ca 1200m, while the length potential is huge as the mountain appears to be a single void with slithers of rock every so often. The current deepest part of the cave comprises a series of four vadose passage/shaft systems, three of which are within the same steeply dipping fault zone and the fourth is in a parallel fault zone nearby. Unfortunately, all four passages sump at about the same depth. A similar perched sump at the same elevation is seen in the Poloska Jama cave on the other, Krn, side of the Tolminka valley, leading to the hope that the Migovec sumps are also just local perched sumps associated in some way with the fault zones. There is still hope that if deep leads can be found in other parts of the cave, out of the fault zone, and they surely exist, then there is a good probability of by-passing the sumps down to the main water table.

Dye-testing, geochemistry and physical observations (ie. temperature) were undertaken in the two rivers either side of the Migovec Plataeu. No conclusive dye-test results were obtained though it is believed, from the observed hydrology pattern, that the main resurgence is located in the Tolminka valley. The Slovenians have reported a positive dye-test to the Tolminka from the MI6 cave on the Plateau which has now been linked to System Migovec.

Considering the group the expedition is pushing hard and works very well. A significant proportion of the group each year comprises people with less than a year to 3 years experience who are often caving abroad for the first time. Several teams are usually underground at once undertaking pushing, rigging and surveying trips, with different shifts facilitated by a camp at ca -600m. This year the underground camp was pretty much cracked with sufficient gear and the right procedures to keep it dry. Additionally a tape recorder and bottle of Slivovich provided the home comforts. Over the summer the expedition is joined at weekends by cavers from the caving section of the local Tolmin Alpine Club. The Slovenians continue exploration over the winter months having to dig through the snow to the cave entrance.

A major development in the rigging this year was the installation of a steel cable tension traverse over a chamber which traditionally requires a down pitch and up pitch with tension guidelines via a rock pillar in the middle of the chamber. A length of steel cable, crimps and 'rock' bolts were bought from the hardware store and the brother of a local caver made some 'hangers'. Several trips and drill batteries later the traverse was in place. No points are scored for style and technique but it's one hell of a ride!

Jim Evans, Mark Evans, Dave Wilson, Janet Cotter-Howells and Paul Huggins

> Out of print publications list
> Indices to NPC explorations:
---> Listings by date
---> Alphabetical listing by cave
---> Index to articles by author
> Northern Pennine Club Home page