Monday, 26 March 2012

A North Wales Mining Weekend

An unseasonably warm March weekend saw various cars converge on the caving/climbing hut in Tanygrisiau, the main aim being to complete the Croesor-Rhosydd through trip.

The Croesor Rhosydd Through Trip - 24/03/2012
Croseor and Rhosydd are two huge slate mines (more like quarries with a roof on top and a swimming pool at the bottom) on opposite sides of Moelwyn Mawr, above Tanygrisiau, a village near Blaenau Ffestiniog (is that the most unpronouncable sentence ever?). When the two quarries were still in use, a tunnel was driven to connect them. It is claimed that this was to settle a dispute over who had the rights to the slate in which part of the mountain, and subsequently to aid ventilation. However, in reality the tunnel was clearly driven by forward-thinking mine owners to enable mine explorers and cavers to complete an exciting through trip seventy years after the mines ceased producing slate. More background here.

The problem with entering one side of a mountain and exiting the other is that at some point you have to walk over the surfacae, so mid-morning on Saturday Kathryn, Djuke, Tony, Emma, Stuart and I had a sweaty walk over to the Croesor entrance adit, about an hour after a first wave (Becka, Tom, Tom, Olaf, Rosa, Gareth and Jess) had set off. We stomped down the large adit, past some old storehouses, and at the bottom gazed out over a vast flooded chamber, with no bottom visible beneath the vivid blue water. Cleary, the whole of the mine below this level was flooded.

We clambered up an incline past a couple of ventilation shafts above us, with a pin prick of daylight visible 100m above, and also some windows over the flooded cavern to our right. Soon we reached the first pitch (about 25m?) with a fixed rope down into another huge chamber. Apparently this chamber was once even bigger, but the bouldery floor we were clambering across was once the roof. Crossing to the far side, it became apparent that it was of truly garagntuan proportions and that the remaining roof was held up by not much more than good will. A group who had entered the mine behind us were worried about noise causing further collapses. Apparently a rock the size of a transit van had fallen out of the roof when they were last here. We didn't hang around in this chamber...

Down the next pitch (with rope protectors bolted over the sharp slate sides) we heard the group in front of us (a busy day underground!) and the distinctive sound of a pulley sliding down a steel wire...our next obstacle! We were now level with the water table once more and the zip line took us across a deep blue lake whose depth I would rather not consider. A few metres further, a wire suspension bridge had been installed across the next lake.

Now four or five metres above the level of the water, we strolled along a horizontal level in relatively stable condition, with occasional views down into flooded chambers below us, the water always electric blue when lights were shone into its depths. Falling in was really not an option, as the sides were sheer and there would be no way to get out of the water without a rope.

Soon, the passage started intersecting the flooded chambers via a series of bridges. "Bridge" is perhaps a little too generous a description of what was left in some cases... The first bridge had two parallel wooden struts left. I was glad to see that a traverse line had been installed, and that it was anchored to the ceiling rather than the bridge. The wood felt suspicsiously soft underfoot. The second bridge was non-existant, with a traverse line round the side of the chamber in its place. The third bridge, 'The Bridge of Death' was the worst. The first half consisted of a piece of tram rail balanced across to the one remaining bridge support, which was dangling unconvincingly from the ceiling. At this point we ran out of bridge completely. As the support swayed ominously under each person's weight, we had to reach up on tip toes and clip a pulley into a wire traverse line (without dropping anything into the water below) and slide across to the far side with nothing to walk on. Looking at photos from several years ago it is very noticeable how much the bridges have deteriorated. I'm not sure how long they will remain there...

The next passage was pleasant, large and in good condition. Unfortunately it stopped after 5 metres. We had now temporarily caught up with the first wave. A larger flooded chamber, "The Chamber of Horrors " required travelling by boat (or swimming with a wetsuit in Stuart's case). Some kind soul had dragged a canadian canoe into the mine and fixed it to a cord so that it could be dragged backwards and forwards across the lake. Tom was already in the boat and there was room for one more so I joined him. The trick was to abseil down (4 or 5 m) into the canoe (if you missed you'd hit the water as the sides of the chamber were sheer) and then enjoy the ride! The canoe meant we didn't need to faff around with our dinghy, although we did use bouyancy aids. The water is apparently 50m deep. As we slid surreally across the surface we could see bridge supports dangling from the ceiling several metres above us; the bridges themselves had long since vanished. Immediately after the canoe trip a short pitch led up to more horizontal workings.

We were now past the technical difficulties, and soon progressed into Rhosydd mine. After a wrong turn up an incline, we eventually found our way to a series of large daylight chambers  - where the mine broke out into a 'Twll' at the top of the mountain. However, we ignored these potential exit points and continued back down another incline to the end of the Rhosydd adit. Day light was now visible at the end of the passage, and after half a mile of easy walking we were out. Pleasantly surprised that we'd completed the trip with no hitches at all, we strolled back to the hut with a swim in the river on the way.

Here are Olaf's photos of the first group.

And here is a compilation of my video clips:

T/U 4 hours

Cwmorthin Mine - 25/03/2012

Another glorious sunny day saw most of our group engage in heinous daylight activities. However, Olaf, Becka, Tom, Tom, Rosa and I headed into Cwmorthin to attempt a round trip I'd heard was possible. We started off by heading down the impressive steps and incline that I'd been to back in January, to the water level. For several dozen metres somebody had taken the time to install scaffold bars less than a welly depth below the water level, to avoid thigh deep wading and keep dry feet - how nice! Eventually the passage dried out and we headed along horizontally deeper into the mountain, admiring various old mining artefacts as we passed them.

We had a survey, and the chambers were numbered, but most of the time we were very unsure where on earth we were. Occasionally we would find a particular artefact that was marked on the map and would, temporarily at least, not be lost. As we "navigated" our way past myriad junctions, side passages and chambers at various different levels I started to feel quite uneasy. I'd only heard about the round trip in passing, and with each junction was becoming more uncertain that I could remember the way out should we need to retrace our steps.

At one point we reached a chamber containing the rusty remains of some compressors and Becka started playing with a handle next to an old electrics box nearby. A pair of bulbs in the ceiling above us lit up, confirming that I had in fact gone mad with the stress of it all. A moment later the others noticed this too and it transpired that somebody had in fact fixed the wires and brought in some bulbs and presumably a car battery of some sort!

More confusion followed as we found ourselves on the wrong side of a taped off section of passage with a notice saying that we were trespassing and the passage led to a working mine! After climbing up a couple of levels, trying various dead ends and passing several million more junctions, we eventually decided that we were probably on the same level as the entrance. A combination of the odd bit of paint, the survey and our noses led us down more passages until, much to our relief, we suddenly recognised a bit we'd been to before - we were now only 5m from the entrance and had completed the round trip - I have no idea how! We had only been underground for 2 hours but, for all but the last 30 seconds, were very unsure as to our whereabouts, and so the trip felt a lot longer than it was!

T/U 2 hours

After another celebratory swim in the sun, some of us headed up another surface incline near the hut, to the top of another hill and pottered around the remains of Wrysgan Mine with head torches.

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