Emergence du Ressel

Mai 2011

par John Volanthen & Rick Stanton

27/5/11

Both divers passed Sumps 1 & 2 in convoy, testing various configurations for use in Spain later in the year. Lines were found to be continuous and in excellent condition. The crawl in the air space just before the bivouac chamber appears to have been dug out somewhat, allowing easy passage. On arriving in the bivouac chamber, 3 loads of equipment each were carried to Sump 3 before the divers settled down for the night. The air in the chamber was bad, with high Co2 and low O2, requiring JV to light the gas stove in a plastic bag of nitrox.

28/5/11

The divers left back mounted rebreathers for the return through S1 & S2 and went forward using side mount rebreathers, scooters and open circuit bailout (worryingly JV had less gas than RS). The second dry section
again required 3 carries each, however the air in this chamber appeared to be slightly better. Both divers arrived comfortably at the T junction, about 1000m into S5. Turning downstream (left) following Jason Mallinson's line it became clear immediatly that the passage was significant. on reaching the end of JM's line, RS Tied on and both
divers swam on into a large flooded fossil passage, which takes flow in flood. When RS ran out of line, JV tied on and RS lead.
Whilst the passage is generally very large, in several places breakdown fills the tunnel almost to the roof. There is at least one "proper" sidemount squeeze. After a total of 805m of line had been laid in a south westerly direction RS spotted an airbell where both divers surfaced. As JV had almost run out his line, a return was agreed. Passage depth is generally shallow - between 20m - 6m and the way on is open. on the return both divers collected their scooters and JV went to look at the upstream end of the cave.
The divers had planned to pack up and exit that day, however on reaching the bivouac chamber, RS convinced JV to stay another night.

29/5/11

Both divers packed up camp and made an uneventful exit, to RS's amusement JV once again proved unable to drive his ride on scooter down some of the big shafts! Surfacing at about 11am, both divers scootered down the river to arrive at the campsite in Marchillac.

The sump mapper was used to survey sump 1 to allow a comparison to be made with the existing high grade survey. The results were promising, however whilst the bearings are accurate it appears very difficult to get accurate distance results either swimming or on a ride on scooter due to flow turbulence and proximity to the diver. The answer is to use a tow behind scooter where possible - modifications are being considered.

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Whilst there is a lot of information regarding the Emergence du Ressel, there is very little description of the cave beyond sump 1. The informaton below is provided to give anyone intending to visit the farther reaches of the cave some idea of what to expect:

On ascending a series of shafts at the far side of S1, a shaft rising to -12m is reached. On the left, in the roof is a passage that takes most of the flow in normal conditions. This is the bypass to reach S2 without crossing dry land (via Lac T). This passage is not obvious, the line into it is often broken. If you follow the obvious way, you will almost certainly surface in the salle des blocks.

On surfacing at lac T, turning right (south) submerges rapidly into S2 (max depth about 12m). After about 200m a junction is reached. Turning right surfaces in a canal that leads to the Salle des blocks. Turning left (North West) following the main line upstream leads into a larger tunnel "The Metro", the passage surfaces after about 100m where the water flows over large blocks. A 10M long channel has now been dug through these to allow crawling progress without de kitting. This air space was not counted by the original explorers, so Sump 2 ends after a further shallow dive of about 80m at a boulder slope leading up into the bivouac chamber. This chamber is about 50m long and 10m high. The ground here is broken and sharp, care is needed when walking in drysuits. The air in this chamber can be bad - high Co2 and low O2, it seems to be worst at the water level on the S2 side, improving as the rocks are
climbed. All diving to date beyond this point is less than 21m deep, most is much shallower.

The lake on the far side of the chamber provides a spacious area to gear up. 50 meters of canal is passed, before encountering S3. This is very short (5m) and can be missed if scootering mid water. a further 300 - 400 meters of canal (the lac long) leads to Sump4, which is 240m long and shallow. This finishes at another boulder pile in a small sump pool.
Leaving the water, an ascending boulder slope and short walk leads to a steep scree and sand slope down to the start of sump 5, total dry distance about 35m. Entering S5 the passage trends North West and after about 300 meters an inlet is seen on the right, This has been explored by Rick Stanton for 200m. This is the only inlet noted beyond S2.
Continuing on until 1000m into S5, the way on reaches a T junction breaking into much larger passage.

Turning right (upstream / North) after 300m a maximum depth of 18m is reached before a boulder slope can be followed to surface. At the base of the slope, low and on the left, 50m of ongoing smaller passage in a NW direction leads to the terminal upstream boulder choke found by Rick Stanton and Jason Mallinson. Back at the 1000m T junction, turning left (downstream / South west) the large fossil passage continues in a South Westerly direction for about 900m, where it is possible to surface in an off route air bell. This ongoing passage is generally large with a
silty floor, but there are several sidemount squeezes over boulder collapse. this passage still takes flow, presumably in flood.