Pozo Castillo – Snow Plug

By Alistair Gott

Castillo, the snow plug “dig” and boulder chocking. I’ve heard a lot about it, after some prospecting on the surface. We kitted up, all were going light just to see what the snow plug and block in the roof looked like. Stories of three previous trips to the snow choke saw the snow plug with too much snow in it, forcing people across to the left of the passage, looking directly up at a set of 4-5 fridge sized blocks held up by fresh-air and rotting wooden stemples.

Fast forward to this year, we entered briefly to work out what the snow  plug looked like, Alistair was posted in first and reported that it looked open. The first visit saw that there were a few blocks on the left and an open pitch past the snow on the right. Lying to the left-hand side of the snow plug was a winch made mostly of wood with some added metal for the winch handle, the winch itself was approximately 6 foot in length and 1 foot wide. We decided with the addition of some rope, a drill and some bolts and hangers, we could drop the pitch today.

Kitting up further with SRT kits, drills and other paraphernalia, we re-entered the mine, and quickly found ourselves showing Joe how to put bolts in.

Joe bolted down a 3m pitch to boulder floor, with some rope rub. Pitch descends wall of chocked boulders assumed unstable. Deviation required to pull away and reduce rub. Rebelay bolted and passage through snow plug followed to RH wall, culminating in second 3m pitch. Base of pitch lands at T junction of natural passage leading to mined level, assumed recently uncovered by retreating snow. Mine explored to discover too tight phreatic heading down 60 degrees, small draught. Found several mine artefacts including woven baskets. Mine exited and Joe pressed on following RH wall to reach open hole in snow plug heading up into black void, ~50m. Alistair bolted deviation and all entered Segura 2 into sunshine. Coke at refugio and cushy disco descent to Tresviso.

Castillo Snow plug (2016)

 

Castillo snow plug (2018)

 

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Pozo Castillo

One of the secondary objectives of the expedition is to revisit the Pozo Del Castillo cave on the Andara mountain range.  This cave, and a number of interconnected caves and mines were explored initially by the French Les Speleois Dromis (LSD) club in in the early 1980’s.  The written report at the time talked of a ‘roaring sound’ at the limit of exploration but a return in 1987 by LUSS reported that part of the route through, in the early part of the cave, had collapsed with snow and rock.

The depth potential to Cueva del Nacimiento is approx. 1360m and with the encouragement of a roaring noise, possibly water or a draft, it has always been an interesting site to revisit.  A few attempts in the past year have returned with vague descriptions of ‘yes it’s blocked’ to ‘we may have been in wrong cave’, so it finally came for me to go up the hill and put my mind at rest.

A large group of us went up the hill, 3 cavers (Phil, Martin and Joe) and 4 others (Duncan, Russ, Nicola and Emma).  AS Castillo is made up of a number of entrances; Pozo Castillo, Pozo Natacha, Segura 2 and Clockwork Pot, the tentative plan was for the others to scout out, log and photograph the next entrance ready for the cavers.  My intention was that if Castillo was blocked the other entrances might provide a way in to the system that dropped beyond the collapse.

Straight away we started to hit the same problem with ‘co-ordinates’ as previous years.  Original co-ordinates from the 70’s have an error in them so can’t be fully trusted without converting and adding some degrees.  Official co-ordinates from the various official guidebooks seem to either have used the conversion (but without the additional degrees) or used a set area as the official position and used for the same cave. The most accurate way appears to be a combination of open street map inputted co-ordinates (quite possibly scraped from the expedition website anyway) and a handwritten LUSS map from the 80’s!

The Pozo Castillo entrance was found quickly, after a few detours, and is a large open shaft of about 15m.  Joe bolted down this and myself and Martin followed.

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The bottom of the shaft is still in daylight being about 15m x 8m wide with a large snow plug in the middle.  Under one wall is a crouching size hole that leads to another 15m pitch.  This was bolted and dropped to enter the start of a complex series of mine passages.  A couple of side passages were ignored as we followed the known description to a ‘crossroads’.  From this point access to 3 of the entrances could be established.  Firstly I went straight ahead, this lead through 200m of walking size mine passage to exit on the side of the hill, overlooking the Lake Depression.  This is Segura 2.  Unable to shout to the above ground team, I went back into the cave.  Right from the crossroads, leads to another junction with an old wooden miners ladder in place.  This is Pozo Natacha.  We attempt to go up here for a while to try and find the entrance to Pozo Natacha from below, but after a few dodgy climbs we started to encounter proper pitches (about 2 from the entrance proper).  Back at the junction the other route lead to a large 30m shaft (the top of which was encountered higher up when trying to climb out of Natacha.  This was interesting, draughty and the first natural cave passage encountered in the system.  A known system again, running almost parallel to Castillo, to a similar depth and similar reports of drafts at the end.

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Finally, we then took the left hand route at the crossroads and went in the Castillo system proper.  Around 200m of impressive min passage, with numerous stacked deads leads to a final flat out crawl.  The reported blockage was described as here and we quickly found it.  A small slumped passage requires a flat out crawl to a small chamber with a snow plug.  Looking up is a rather scary affair, with two car engine sized boulders perched and a bit of rotten timber and the snow plug.  The left hand side of the snow plug has started to melt and it possible to look down into the chamber further and see more of the snow plug.

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No way we were going to get through this today and some discussion was needed on whether we should even attempt it.  We exited the cave, regrouped and returned back home

Segura 2 – located and logged.  Safest and easiest way into either Pozo Castillo and Pozo Natacha.

Clockwork Pot – not located, co-ordinates inaccurate from all sources.  Would need to return and use approximation from the Castillo full survey and descriptions.

Pozo Natacha – entrance not located / confimed but enterable via Segura 2.

Pozo Castillo – still blocked, the snow is possibly melting.  Would need to check how stable the boulders are and whether it’s only the snow holding them up