Tresviso Caves Project

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T20A: Silvestre Pot

(KJ1, TV8)
Area:Sobra Valley
East, North:360767, 4789715 (nearby)
Coordinate Quality:GPS
Long, Lat:-4.7150852041735, 43.247356941636 (map)
Elevation (m):1121
Length (m):750
Depth (m):-229
System:
Active Lead:
Survey Available:

Approach
Warning: This cave would be very dangerous in wet conditions, there are several constrictions which would be impassable and several pitches which would be virtually impossible to rig safely. The cave was bolted very sparsely (2018) and most of the pitches would benefit from some back-up.

Silvestre Pot is extremely difficult to find, someone with knowledge of the location and route to the entrance is recommended. Park in a small layby at the head of the Sobra Valley, a few hundred meters down from the Jitu de Escarandi carpark. Follow a steep logging track down into the valley (x:0360170 y:4789574 z:1261m). After following the track down the hill for ~15-20mins there is a short splitting of the track and a slightly less dense patch of woodland after the convergence. Shortly after regaining the woodland take a right-hand turn through some trees on a very faint animal trail. There may still be some flagging tape (2018) on the trees here (x:0360561 y:4789789 x:1139m). Continue through the trees, roughly perpendicular to the track, to enter a larger clearing, continue 'straight', until a steeper slope down is met. Trending slightly downhill, after passing a hole in the ground a larger stream is encountered, cross this and trend left through some trees. An elongated opening is found approx. 25m long and 2m wide along its length. This is AS1 Cueva Donga (x: 0360667 y: 4789666 z: 1150m) Once at AS1 Cueva Donga, set the GPS (x: 0360767 y: 4789715 z: 1121m) for Silvestre. When looking at Cueva Donga, the route to Silvestre is behind to the right, through a fern filled dry streamway. After this go up to the right, skirting the dip in the ground in front. Stay at this high-level round to the right, until a patch of young trees in encountered on the left, go through these young trees. There is a clearing with a decaying tree trunk in the centre, a doline beyond, and a small slit shaped pot in front approx. 2m wide and 5m long, with Silvestre written in the opposite corner to the decaying tree trunk.

Entrance
a small slit shaped pot in front approx. 2m wide and 5m long, with Silvestre written in the opposite corner to a decaying tree trunk. The 35m entrance pitch is a fairly insignificant rift,

Description
The 25m entrance pitch (Pitch 1) is a fairly insignificant rift, it is possible to rig off a rock near the head of the pitch using a 41m rope but this rock is not very secure. A 10m longer rope would be useful for a tree backup or the placement of additional bolts. One side of the rift is quite friable and the pitch is best descended one at a time. The base of the entrance pitch is a mud, rubble and bone slope, in a large descending passage.

Heading downslope reaches a large chamber with three ways on. Looking up it is possible to see the debris blocking the original open pot. Directly ahead, following the right-hand wall leads to an unexplored dry fossil inlet (2018), the other two ways are upstream and downstream passages of a streamway. <

Upstream quickly leads to a low puddle of unknown depth and length, which has not been passed(2018).

Heading downstream, (Pitch 2) a short 4m pitch and a series of climbs can be rigged with a 10m rope.Follow the water down the first clean washed stream section, on the right is a slightly drippy large inlet (unexplored)

The clear way on is to follow the stream left through the large eyelet (Pitch 3). Several re-belays provide a slightly drier 10m drop to the floor which needs a 20m rope.At floor level the stream disappears though the boulders in the floor of this large chamber. To regain the stream, follow the obvious large passageway heading down and round to the left and directly away from pitch. (several large inlets are all unexplored in this chamber, 2018).

After some large boulder navigation, the stream is regained and can be followed down a freeclimb down a large block and then to the first of two short pitches. The first (Pitch 4) is a 3m drop requiring a 6m rope and the second (Pitch 5) is an 8m drop requiring an 11m rope. The second short pitch lands you near a pool of water. Skirt and bridge several pools ignoring the large inlets on the left (unexplored), in between two pools is a climb down a distinct conglomerate block, easiest on the left.

You will soon arrive at a blank wall in front and a lower section drops on the right through a short pool forcing you to crawl for approx. 2m. Emerging from the boulder ruckle the cave quickly enlarges to a sizable rift which the water cascades down.

Keeping to the right of the stream the head of the next pitch (Pitch 6) can be gained on the right-hand wall. The 13m pitch can be rigged with an 18m rope and a single bolt backed up from a natural in the wall behind.

Electronika

At the base of the pitch a short section of lovely clean washed stream passage leads to the head of the Electronika Pitch and a very large chamber. This is a fabulous pitch with many white lines in the wall, as well as evidence of serious flood conditions. This pitch would be very dangerous in high water!

The first section (Pitch 7) is rigged with a +60m rope using series of free hangs and pendulums in an attempt to avoid the water, down to the large ledge some 40-45m below.

The water flows off to the right but the next section (Pitch 8) is gained directly over the edge using a 25m rope to reach the floor of Electronica some 17m below, which is littered with boulders and leaf mulch (which can also be seen 5m+ up the walls).

The Electronica shaft has a substantial aven entering, amongst several smaller ones and is larger than the Hall of the Mountain King in Cueva de la Marniosa.

At the base of Electronica it is possible to follow the stream, descending round to the right and then down via a 1.5m free climb where the water disappears into rift type development. The mud covered high-level passage above the stream has only been traversed a short way, and may be worth further investigation.

Continue downstream following the narrower rift development. Ducking under a ramp of calcited blocks forces a crawl at stream level, followed by traversing out to reach the head of the next two-part pitch (Pitch 9) requiring a 15m rope and entering Waterfall Junction.

Waterfall Junction contains three ways on. Two passages end in sumps via short pitches (one on the left, south west and one back underneath the waterfall).

The Wet Willy.

This short diversion begins by 'running' through the waterfall at the base of the Waterfall Junction pitch. A descending rift can be followed for approx. 10m before arriving at head of a pitch (Pitch 10). Using a 20m rope a traverse across the ceiling avoids the water and a 3m descent leads to an inlet passage directly opposite (unexplored). Descending a further 3m leads to another smaller inlet (unexplored) before the final 5m drop lands back in the stream way. Following the stream leads almost immediately to a sump.

Bob's Crusade

At Waterfall Junction, an obvious dry passage heads back under the rift developed passage above. Following this several deep pools can be avoided by the long legged and gymnasts to reach a series of climbs. All the climbs are followed by pools, reminiscent of 'marmites' in a dry canyon. All pools contain a layer of ancient leaf mulch in their base and oil on the surface, creating a very unusual appearance.

Following the passage leads to three pitches (requiring a 20m, a 15m and a 10m rope) then a sump.

In the final chamber was a fine collection of snotties and some spiders. Just above the last pitch is an open rift, and there is air movement throughout the passage above, this is worth a look. The water level here is at the same level as Marniosa and may prove to be an inlet heading up towards Andara.

Big Girls Don't Cry (or maybe The Derbyshire Digger)

Ignoring the two sumped passages, the main way on is up a devious climb directly in front. Begin climbing on the left, corkscrewing up (rigged 2018). At the top of the handline the rift continues in a northerly direction. Through some fine fossil rift passage, passed by traversing and many short climbs. After a hundred meters or so a right turn is followed by a calcite flow, with a handline and fixed traverse line leads into the continuation of the rift (rigged 2018).

A tight slot through a puddle in the floor is bypassed by a climb above, coming to Brew Chamber (not a chamber, just an enlargement in the rift). From this point, the rift takes on a more downwards trend, with 3 significant downclimbs (10m, 4m, 2m) followed by a P25 and a P20 (rigged 2018 - survey says these are P8 and P6!), all the while following the howling draught.

A striking long, straight section precedes a final 2m downclimb into Harrison chamber. At the far side, a short climb over ancient calcite leads directly into the Cueva de la Marniosa streamway. Right leads to Hall of the Mountain King and left leads downstream to the rest of the cave.

Reference
Mark Sefton (2000)
T.C.P. (2018)

Images
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