Last updated: 12-Mar-2022
Trefil, South Wales, U.K.
The cave is situated in the Cwar yr Ystrad quarry. From the village of Trefil proceed north along the main road through the village, until it becomes a private quarry road, shortly after The Top House (Tafarn Ty Uchaf). The road may be blocked by a barrier just after the village on evenings and weekends, and a 6 km walk may be needed from that point onwards. A bike is suggested as a means to reach the quarry, as cycling is permitted on the private road.
Follow the private road for about 5 km, which slowly swings west, in increasingly poor condition. A few dirt tracks are passed on the right before a forest is reached; all of these tracks can be ignored. The road passes through a quarry and past a few others; remain with the better quality road. After passing the remains of some quarry buildings, it swings hard left and ascends to a triangular junction. Take the right fork, then after 150 metres, take a track on the left, towards the entrance to a larger quarry. The quarry has another main entrance further along the track. Both quarry entrances are blocked to traffic. If parking here, note that this area suffers badly from car crime, so either leave someone in your car, or park somewhere out of sight.
The main part of the quarry is its central section. To get there from the entrance described above, proceed into the quarry then immediately take the right branch in front of a large rock outcrop, into the widest part of the quarry. The main long wall of the quarry runs along its length ahead-left, and the entrance to the cave is part way along that wall. First on the left is a deep depression with a pool, surrounded by tall scree slopes. A steep track soon heads down into it, with a tall scree slope on its far side. Ignore this track and head further along main level of the quarry away from the entrance. Beyond the tall scree slope is a rocky outcrop on the left side of the quarry, which rises above the surrounding scree. The cave entrance is located at the bottom of the main quarry wall opposite this outcrop, and can be a little difficult to find. There is a large depression in the quarry floor immediately in front of it, which contains an intermittent pool, and another track leads down beside the rocky outcrop to the pool. The entrance itself is about 2 to 3 metres off the surrounding quarry floor, and is usually concealed with a dry stone wall. Please replace this wall after your visit.
A short cave, Ogof Gwybedyn, is located a little further to the right, and is a slightly more obvious hole, dropping into a very tight passage. Ogof Gwybedyn's entrance is slowly being buried under scree.
There is an alternative path from the Pontsticill Reservoir dam which is about 25% shorter, but this is much steeper at the start, and takes more effort than the route suggested above.
No control is placed over access.
The cave is taped to protect its formations and mud deposits, and the club that found the cave request strict adherence to the conservation policy. Please respect the tapes. In the interest of conservation, please do not dump carbide - spent or unspent, leave cigarette ash or other litter within the cave.
The entrance opens almost immediately onto a 1.5 metre freeclimb down into the main passage. The passage is fairly typical of South Wales caves, being a few metres wide and high, with a normally rocky floor, and occasional small formations. It continues this way for 200 metres, with the taped route leading through an undercut oxbow at one point, to a larger section which swings to the right, and reaches a junction.
In the left wall of the larger section just as it swings right, about 20 metres before the junction, is a climb up above a tiny inlet into Bodengo Passage. At the main junction, the passage continuing up a slope ahead is the way to Nant Criban, while the main passage continues down the left. This descends a rocky slope with an inlet on the right. The inlet becomes too tight after 20 metres, but the main passage continues for another 300 metres, with some sandy sections, to reach a choke.
The route through the choke is fairly obvious, and reaches a climb up after about 10 metres, back into the main passage again. This enlarges quickly to its largest size, passing a blind rift up a ramp to the left, before funneling down suddenly into a narrow rift, Nant Rhymni. This soon lowers to become a flat out crawl in the stream, and lasts for about 250 metres, before becoming too low to follow. The stream has been traced to the Rhymni Risings. About 50 metres before its end, a hole up enters a series of rift passages, Ffordd Swnd, which can be followed for about 50 metres.
Bodengo Passage starts with a climb up to reach a squeeze that is only passable by the smallest of cavers. The passage beyond is almost all crawling sized. At the first junction, the way ahead soon becomes too low, while the passage to the left passes too-tight side passages to reach another junction. To the left closes down, while to the right reaches a small chamber. To the right, downstream, becomes too tight, but would connect with an earlier part of the passage. To the left is taller, passing through a crawl and down a climb, to reach Plaster Aven. Shortly beyond this, tight squeezes at floor and ceiling level unite in a continuation which abruptly ends too tight.
The way into Nant Criban begins comparatively small, requiring crawling between rocks then over sediment. In a small enlargement is a short, blind side passage to the right. Continuing ahead, a rift in the floor is the way to Nant Lwyd. The route ahead then passes some reasonable formations, and enlarges as it enters a chamber. The chamber has a dig to the left, and a small passage to the right, which is the way on. This is a fairly tight 80 metre crawl, which turns left, then slowly loops right, passing over some narrow rifts, before suddenly entering the side of a much larger stream passage; Nant Criban. This can be followed to the left for about 50 metres to reach a choked section, where the way on reaches a junction. To the right this regains the passage, which finally becomes impassable after 40 metres. To the left is a much tighter, more awkward passage. This enlarges after 50 metres when it enters an aven. All possible ways on close down after a maximum of 40 metres.
The rift to Nant Lwyd descends into an enlargement. Nant Criban's stream enters from the right, but is choked. Down to the left is a slot into an undercut, which is the way on. This follows the stream downstream to a junction with the larger passage of Nant Lwyd. To the right, the stream flows out down a climb, and the passage becomes too tight with a visible connection to the inlet in the main passage. Nant Lwyd can also be followed upstream to the left for about 50 metres, becoming a much smaller crawl after about 20 metres.
Whilst every care has been taken in the compilation of this cave description, neither the author nor his fellow cavers can accept responsibility for loss or injury arising from any errors, omissions or inaccuracies in this cave description.
This description is subject to copyright. The copyright resides with the author and some other contributors. You are welcome to download, store, retransmit, print and distribute this document PROVIDED THAT (1) you do not do so for any form of reward, financial or otherwise, and (2) all references to the author are retained or otherwise clearly acknowledged. Any infringement of these conditions is an offence in the UK and also in most other countries.
©1995-2016 MWJ
