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Trip to Cwmorthin Slate Mine -- 20th Dec 2009

Group: Ian, Paul, Roger, Dave

Some of us had been in Cwmorthin before, but its such a big place there are always new areas to explore. We used the excellent maps off the Friends of Cwmorthin (FOC) website to plan a circular route going down the back vein incline (BVI) and coming up the chamber 34 incline.

An early start was made as the weather was not brilliant. After dropping Roger's car off in Mold the four of us headed along snowy roads towards Tanygrisiau and parked in the lower car park as the car wouldn't make it up the snowy slope to the upper one. We changed in bright, but cold, conditions and then headed up the track towards the lake level entrance. There was quite a bit of snow around and an icy breeze through the entrance portal. Having previously checked the lock combination with Miles, we opened the gate and headed in. There were some nice icicles hanging from the beams and some small ice stalagmites forming on the floor.

We pushed on along the main passage and took the left branch at the junction. We stopped briefly at the top of the chamber with stairs leading down and then headed on a few yards to the start of the BVI. We walked down the incline passing the remains of a wagon and a concrete dam on the RHS. Further down we came to an area with some side passages and another concrete dam complete with gate valve and pipework. There was also the remains of a couple of wagons, one jammed between the roof and the tracks and the other lying on the floor. The map showed this was at level 'B'.

One of the passages led off to a chamber with the remains of a wooden bridge. The decking was pretty well gone, but the supports looked OK, but without a lifeline it wasn't worth the risk crossing it and anyway the rest of the bridges on level 'B' were probably missing. Someone had left a OKish bit of 10mm SRT rope for those brave enough to abb down to the next level... Heading back a crawl though a hole at the side of the BVI led to a short passage with a big drop at the end. There was a chain running horizontally round the LHS edge and by peering around you could see a set of rotten planks pinned to the wall which the miners used to cross to the head of the chamber while hanging on the the aforementioned chain. Back at the BVI another passage led to the chamber with the staircase at the top which we saw initially. The flash on the camera completely failed to illuminate the scene :-( There was a passage leading downwards (parallel to the BVI) which we climbed down carefully. This was level 'C' and left was a walkway between two chambers. Looking downwards the crane on level 'E' could be seen and the chamber on this level contained a portaloo which Dennis couldn't resist modeling. High in the LHS wall of the chamber (out of camera range) the chain and planks we had seen earlier were visible.

To the right was a bridge which was pretty complete, but still dilapidated. We headed back up the passage and back to the BVI.

Heading down we came to level 'C' with passages to the left and right. The right hand passage had a chain across it and led to a collapsed bridge, while the left hand side led to the bridge we saw from the parallel passage. Dave crossed this, but one plank did move... We headed on down to level 'D', again not much to see, the bridges having disappeared. One blind passage did have an abrupt colour change on the walls caused by water staining due to the flooded workings being drained in later years from the Oakley workings. We dropped down the remainder of BVI to reach level 'E' and the water.

At the bottom of BVI there was a cubby hole which housed the pumps used to drain the lower levels. The pump is gone and all that remains is the switchgear and pipework. We headed off to the left to inspect the crane used to pull trucks up the floor 'G' incline. Sadly this area is flooded with thigh deep water, however the crane and wagons are worth seeing and Dave and Roger headed further along into the passage connecting chambers West 2-6. There isn't much to be seen in these far reaches. Interestingly the big brass valve on a main compressed air pipe still turned quite easily.

Back at the base of BVI we headed in the other direction. After a short while the water poured down a hole on the LHS into lower chambers and we could proceed more comfortably having emptied our wellies. The passage has some rails initially and a large water and compressed air pipe. We followed the passage though a lot of chambers until at the last one the passage was offset and we passed into 'level ffrench' and the Oakley workings. We headed on, inspecting a few blind passages, one of which had some small but pretty white crystals. Eventually we reached a chamber with the remains of a pump and electric motor (the latter having been smashed apart for the copper) and headed along a few passages until be reached the winding area for the chamber 34 incline.

After inspecting the winding gear and cabin we headed up the passage, complete with old lights till we reached the 1935 compressor area. The compressor had long since gone, but the tanks remain, together with the concrete base and power switch. Dave had a look inside the switchgear box to see if it was still intact and noticed the centre switch blade was mechanically connected to the external handle, but the outer pair were not. Also the centre lower bus cable was loose, none of this was the case a year ago. After closing the box and idly pulling the control lever into the 'on' position the ceiling lights (which we hadn't noticed before) came on! Er spooky. No-one else initially noticed till Dave pointed them out! Turning the breaker off extinguished the lights and a hasty examination showed a couple of thin brown wires connected to the centre switch blade assembly. A careful search showed hidden wires going up to the ceiling lights and a wire disappearing along the RHS level. Following this we came to a little water turbine fed via a syphon from a pool some distance away. Water flow was not really sufficient to make it spin very freely so we used a couple of old fishplates in the trough to direct a narrower stream onto the blades. With this done the rotor turned a bit erratically and a nearby light flashed as magnets passed a coil. We headed along the passage (complete with water channel) in the other direction and came across a couple of signs put in by the FOC forbidding access to the chambers further on (collapse, danger, trespassing etc). Did we heed them? - well mostly...

We climbed up the old stairway towards Oakley floor 1 and then crossed the Oakley 'hurdles' to old vein level 'C'. Walking along the passage we got to a sign placed by FOC warning about hanging death above the stairway. We could see some stuff on the floor, but generally it looked OK so we tip-toed up the stairs, avoiding the marked off section and then clambered up the remaining chamber to get back to the passage leading to the 'letterbox' and lake level. We exiting the portal, locking the gate and headed back to the car in a snowstorm. Changing out of caving gear was interesting to say the least, but overall this was a brilliant trip - especially with the surprise of some working lights!

Trip time about 4 hours