Clydach Gorge trip 06/06/2022
Unless otherwise stated, camera, setups, lighting, edits and gallery effects by Tarquin. Modelling and lighting at various points will be Steph Andrews.
Climbing into the Main Entrance of Ogof Clogwyn, a popular cave in the gorge. The climb is always a little challenging for shorter cavers, and a good source of entertainment for spectators.
Modelling by Steph, lighting by Sol
The entrance passage, before the first corner.
Modelling by Steph, lighting by Tarquin, Sol and Steph
The early passage. An oxbow starts on the right of this picture, linking to the second entrance.
Modelling by Steph, lighting by Tarquin and Steph
The second entrance, which is too tight for most cavers, and exits part way up a cliff. As a result, it is not used.
Lighting by Tarquin and Sol
Just after the third entrance is the section with the most iconic phreatic shelves, the finest example of them in South Wales. These are characteristic of the cave, and are formed from layers of chert - fossilised sea cucumbers. They are resistant to acid corrosion, unlike the limestone, so when the acidic water dissolves the limestone, it leaves the chert behind. They are not as physically strong as the limestone, but are strong enough to walk on. In vadose caves, these are almost always destroyed by the abrasion, as they are relatively weak. That shows that this cave almost certainly formed as a phreas (which it did).
Modelling by Steph, lighting by Tarquin and Steph
Walking on the ledges.
Modelling by Steph, lighting by Tarquin and Steph
Scallops, showing water flow in the same direction as the current stream. This is of interest because the cave actually formed in the other direction. It was once the downstream end of Waterfall Cave, before the gorge was cut down, and the original location of its resurgence is not known, but must have been further down the valley. It cannot have been too far downstream, as the cave is formed in the upper Dowlais limestone, whose steep dip means that only a short distance downstream, the limestone would have been too high to allow water to flow from its source in Ogof Rhaeadr Ddu. Once the gorge cut down, splitting Waterfall Cave and Ogof Clogwyn, the water direction completely reversed, turning Ogof Clogwyn into a resurgence.
Lighting by Steph
The passage then reaches a large boulder pile, where there is a climb overhead into an oxbow called the Upper Series, which creates a round trip.
Modelling by Steph, lighting by Tarquin and Steph
Upstream from the boulder pile, the cave is narrower, and there is a choice of routes at stream level, or up on the ledges at ceiling level. On our way in, we stay at stream level.
Modelling by Steph, lighting by Tarquin and Steph
The ledges abruptly end, and the ceiling drops. There is a low crawl to othe right here, which reaches a small, static sump.
Modelling by Steph, lighting by Tarquin and Steph
Hydrophobic microbial mat on the ceiling. These are bacterial colonies that process biological waste that seeps in from the surface. Their hydrophobic quality causes water droplets to bead up, making them glisten in torch light.
Low ceiling.
Modelling by Steph, lighting by Tarquin and Steph
The upstream sump. This has been dived, but after passing some silt banks, it silts up enough to prevent progress, within about 30 metres. The source of the water is not known, but it seems to go cloudy at the same time as the main river, so it is probably sourced from a little further upstream. Somewhere in that direction, there must be a connection to the original resurgence, however.
Modelling by Steph, lighting by Tarquin and Steph
We returned downstream by traversing along the ledges. One part requires a wide gap to be crossed, or a flat out crawl along a ledge. All part of the fun.
Modelling by Steph, lighting by Tarquin and Steph
Formations at ceiling level.
Start of the Upper Series. The usual climb up is the hole in the floor.
Modelling by Steph, lighting by Tarquin and Steph
Most of the Upper Series is relatively awkward.
Modelling by Steph, lighting by Tarquin and Steph
Duplura, a tiny two pronged bristletail. They move incredibly fast for their size, and the camera is unable to focus in time.
Modelling by Greg
After passing over a hole to a lower level of the passage, the upper level gains its own floor.
Modelling by Steph, lighting by Tarquin and Steph
The passage then becomes crawling sized, passing daylight at the impenetrable Fourth Entrance, which sits in the cliff above the Main Entrance.
Lighting by Tarquin and Sol
A very light coloured European cave spider. This appears to be a standard Meta menardi, but the silver colour is really bright, and very different from those seen elsewhere in the valley.
Modelling by Gwynedd
The passage turns away from the cliff, and grows dramatically in size.
Modelling by Steph, lighting by Tarquin and Steph
Impenetrable side passage.
The largest section of Upper Series, which matches the streamway in size.
Modelling by Steph, lighting by Tarquin and Steph
The passage then abruptly ends at a dig. The hope had been that this would bypass the sump, but the digging stalled.
Lighting by Tarquin and Steph
Considering the digging tools, it is hardly surprising.
We returned to the earlier hole in the floor of Upper Series, and dropped down into a lower level, which continues underneath the upper passage.
Modelling by Steph, lighting by Tarquin and Steph
Tiny Symphyla - a "garden" centipede, which is not actually a centipede, in spite of being related to them. This is floating on a pool of water.
Modelling by Beth
And another dipura, doing the same. There were a lot of them here.
Modelling by Bob
The passage ends at a climb down to the streamway, opposite the second entrance.
Modelling by Steph, lighting by Tarquin and Steph
Crawling towards the third entrance.
Modelling by Steph, lighting by Tarquin and Steph
The passage leading to the third entrance.
Modelling by Steph, lighting by Tarquin and Steph
The reason Steph had stopped is this spider's web. There is only one way to make progress along the passage.
Modelling by Steph, lighting by Tarquin and Steph
Reaching surface.
Modelling by Steph, lighting by Sol
The dismount out of the entrance is entertaining, and often involves an unglamorous flop, but Steph managed it with some level of grace.
Modelling by Steph, lighting by Sol
Just around the cliff is the entrance to Pylon Cave.
Modelling by Steph, lighting by Sol
It starts with a crawl over soil and bat guano, into a little chamber.
Modelling by Steph, lighting by Tarquin, Sol and Steph
Tiny millipede, smaller than the bat guano pieces that it is feeding on.
Modelling by Muncher
More normally coloured Meta menardi in the chamber. Being photophobic, she instantly turned away when I tried to take her picture.
Modelling by Cerys
The slope down from the chamber into a lower chamber.
Modelling by Tarquin's glove and Steph, lighting by Tarquin and Steph
Steph reported that the lower part of the chamber was full of lesser horseshoe bats, so we left them alone and headed elsewhere.
Modelling by Steph, lighting by Tarquin and Steph
Waterfall just upstream in the gorge. We dropped down to the river via a clumsy scramble.
The gorge just downstream of Ogof Clogwyn.
Modelling by Steph
A little further down, the waterfall on the left is Waterfall Cave's resurgence. The main gorge must pass through the Llanelly Shales, which shows just how little distance the former Ogof Clogwyn resurgence could travel before it would start having to flow uphill (entirely possible, as a phreas). The shales form an almost impermiable barrier, it is extremely rare for water to flow from one to the other.
Modelling by Steph, lighting by Tarquin and Steph
The gorge, upstream of Devil's Bridge. By now, it is in the lower limestone beds.
Pwll y Cwm, the major resurgence of Agen Allwedd and Ogof Daren Cilau. Right now, the resurgence is flowing. In extreme drought, the grey river water can be seen flowing into the resurgence, joining the water that continues to flow through the caves. The pool is 14 metres deep (which feels crazy when looking at the top like this), where it breaks into the main sump of Ogof Daren Cilau, bottoming out at 19 metres depth. The story goes that the pool used to be a tiny hole, and was blasted open by the iron workers in the hopes of gaining more water flow, then filled with rubble when the flow did not increase. The rubble slowly slumped into the passage at the bottom. There are all sorts of theories suggesting that the passage could continue on the other side of the river (below the camera), into some unknown conduit, heading to some as yet undiscovered destination.
Modelling by Steph
Just a little downstream is the entrance to Elm Hole, another cave connected to the Daren Cilau sump, and the original through trip to it. The cave is an active resurgence, with the water flow visible by the plastic pipes in front of the entrance. That water always flows, even in drought, but runs clear, while the cave water is stained black from peat, and the river water is cloudy. The cave passage also has a second sump which takes water in flood. Its destination is unknown. There is something unusual happening with the water in this cave system!
Top of the Devil's Waterfall, seen from the Devil's Bridge.
The waterfall's Welsh name is Pwll Cwn, pool of the dogs. It is quite likely that the name Pwll y Cwm, pool of the valley, was a mistake, taken from the waterfall and misread by accident. It is roughly 10 metres high, perhaps a little more.
The path downstream has become very much overgrown over the years, but runs on the right bank. At one point, Bill Gascoigne fell into the waterfall's plunge pool from here, with all his camera equipment, while hoping to photograph the results of a dye trace from the caves downstream. The camera equipment is still down there in the plunge pool.
Modelling by portions of Tarquin
The regular path runs along the top of a cliff dropping all the way down to the river, but a small landslide, seen on the right here, wiped out part of the path. Continuing downstream required us to ascend the bank and make our way around a little higher, without any path.
Modelling by Steph
Fungus on a rotting log, possibly a hairy curtain crust (Stereum hirsutum).
A descent down a gully then brought us down to the river, where this narrow waterfall is on the far bank.
Distant view of the waterfall in its narrow canyon.
Crossing the river with dry feet brought us far enough to see the waterfall, but the view was still obscured.
Wading upstream was the only way to get a better view; wet knees was as bad as it gets. And while this looks like an idyllic heaven, the water is grey not just because of the rocks it flows over, but also because of the outflow from a sewage works upstream, which occasionally has overflow incidents. The smell in the river is noticeable. Such a shame.
Modelling by Steph
Scrambling the cliff gave us a much better view of the Devil's Waterfall/Pwll Cwn.
Watching the waterfall.
Modelling by Steph
The bottom of Cwm Pwca, named after Puck, the character from Shakespeare's A Midsummer Night's Dream, which was supposedly based in this valley.
Entrance to Shakespeare's Cave, with its distinctive crown shape.
Modelling by Steph, lighting by Sol and Steph
The early passage is very wide, but has been blasted into this shape, presumably to try to turn it into a showcave (a terrible idea, since it has nothing of suitable interest, and never becomes wide enough for tourists).
Modelling by Steph, lighting by Tarquin and Steph
Male European cave spider. A much more normal colour, and very different from the one in Ogof Clogwyn. His abdomen is extremely large for a male, but the palps make it very clear that this is a male.
Modelling by Geraint
A more colourful one. This might be female, since it has no palps, but it seems to have proportionately long legs, which suggests it is a juvenile male. Either way, it is a European Cave Spider..
Modelling by Eirian
The passage abruptly splits into a blind alcove, and a narrow rift, which is the way on.
Modelling by Steph, lighting by Tarquin and Steph
The narrow rift issues a stream, which fogs up the passage significantly.
Modelling by Steph, lighting by Tarquin and Steph
The narrow rift.
Modelling by Steph, lighting by Tarquin and Steph
The first duck. Going any further really needs a wetsuit. Not today.
Lighting by Tarquin and Steph
Arch at floor level in the Gellifelen railway tunnels. The purpose of this arch is not known.
The arch is full of rubble, and may be a drainage adit.
Rainclouds lifting over the Blorenge.
Sunset over the Blorenge.
Sunset over Gilwern Hill (441 metres). On the left is a 500 m high ridge of coal tips connecting Llanelly Hill and the Blorenge (the crags are called Carreg Maen Caro, but the ridge is not named), then Gilwern Hill, Mynydd Llangatwg (530 and 529 metres), Allt yr Esgair (393 metres), Mynydd Llangorse (515 metres), Pen Cerrig-calch (701 metres) in cloud, Waun Fach (811 metres), Pen y Gadair Fawr (800 metres) and the Sugar Loaf (596 metres) in cloud.
Sunset over Allt yr Esgair and Mynydd Llangors.
Wild ponies at Pwll Du. Judging by the skewbald pattern, these are partly Welsh mountain ponies, and partly gypsy cob, since the pied gene is not naturally found in Welsh mountain ponies.
Sunset and wild ponies, with an inversion at Pwll Du. What an incredible end to the day.
Climbing into the Main Entrance of Ogof Clogwyn, a popular cave in the gorge. The climb is always a little challenging for shorter cavers, and a good source of entertainment for spectators.
Modelling by Steph, lighting by Sol
The entrance passage, before the first corner.
Modelling by Steph, lighting by Tarquin, Sol and Steph
The early passage. An oxbow starts on the right of this picture, linking to the second entrance.
Modelling by Steph, lighting by Tarquin and Steph
The second entrance, which is too tight for most cavers, and exits part way up a cliff. As a result, it is not used.
Lighting by Tarquin and Sol
Just after the third entrance is the section with the most iconic phreatic shelves, the finest example of them in South Wales. These are characteristic of the cave, and are formed from layers of chert - fossilised sea cucumbers. They are resistant to acid corrosion, unlike the limestone, so when the acidic water dissolves the limestone, it leaves the chert behind. They are not as physically strong as the limestone, but are strong enough to walk on. In vadose caves, these are almost always destroyed by the abrasion, as they are relatively weak. That shows that this cave almost certainly formed as a phreas (which it did).
Modelling by Steph, lighting by Tarquin and Steph
Walking on the ledges.
Modelling by Steph, lighting by Tarquin and Steph
Scallops, showing water flow in the same direction as the current stream. This is of interest because the cave actually formed in the other direction. It was once the downstream end of Waterfall Cave, before the gorge was cut down, and the original location of its resurgence is not known, but must have been further down the valley. It cannot have been too far downstream, as the cave is formed in the upper Dowlais limestone, whose steep dip means that only a short distance downstream, the limestone would have been too high to allow water to flow from its source in Ogof Rhaeadr Ddu. Once the gorge cut down, splitting Waterfall Cave and Ogof Clogwyn, the water direction completely reversed, turning Ogof Clogwyn into a resurgence.
Lighting by Steph
The passage then reaches a large boulder pile, where there is a climb overhead into an oxbow called the Upper Series, which creates a round trip.
Modelling by Steph, lighting by Tarquin and Steph
Upstream from the boulder pile, the cave is narrower, and there is a choice of routes at stream level, or up on the ledges at ceiling level. On our way in, we stay at stream level.
Modelling by Steph, lighting by Tarquin and Steph
The ledges abruptly end, and the ceiling drops. There is a low crawl to othe right here, which reaches a small, static sump.
Modelling by Steph, lighting by Tarquin and Steph
Hydrophobic microbial mat on the ceiling. These are bacterial colonies that process biological waste that seeps in from the surface. Their hydrophobic quality causes water droplets to bead up, making them glisten in torch light.
Low ceiling.
Modelling by Steph, lighting by Tarquin and Steph
The upstream sump. This has been dived, but after passing some silt banks, it silts up enough to prevent progress, within about 30 metres. The source of the water is not known, but it seems to go cloudy at the same time as the main river, so it is probably sourced from a little further upstream. Somewhere in that direction, there must be a connection to the original resurgence, however.
Modelling by Steph, lighting by Tarquin and Steph
We returned downstream by traversing along the ledges. One part requires a wide gap to be crossed, or a flat out crawl along a ledge. All part of the fun.
Modelling by Steph, lighting by Tarquin and Steph
Formations at ceiling level.
Start of the Upper Series. The usual climb up is the hole in the floor.
Modelling by Steph, lighting by Tarquin and Steph
Most of the Upper Series is relatively awkward.
Modelling by Steph, lighting by Tarquin and Steph
Duplura, a tiny two pronged bristletail. They move incredibly fast for their size, and the camera is unable to focus in time.
Modelling by Greg
After passing over a hole to a lower level of the passage, the upper level gains its own floor.
Modelling by Steph, lighting by Tarquin and Steph
The passage then becomes crawling sized, passing daylight at the impenetrable Fourth Entrance, which sits in the cliff above the Main Entrance.
Lighting by Tarquin and Sol
A very light coloured European cave spider. This appears to be a standard Meta menardi, but the silver colour is really bright, and very different from those seen elsewhere in the valley.
Modelling by Gwynedd
The passage turns away from the cliff, and grows dramatically in size.
Modelling by Steph, lighting by Tarquin and Steph
Impenetrable side passage.
The largest section of Upper Series, which matches the streamway in size.
Modelling by Steph, lighting by Tarquin and Steph
The passage then abruptly ends at a dig. The hope had been that this would bypass the sump, but the digging stalled.
Lighting by Tarquin and Steph
Considering the digging tools, it is hardly surprising.
We returned to the earlier hole in the floor of Upper Series, and dropped down into a lower level, which continues underneath the upper passage.
Modelling by Steph, lighting by Tarquin and Steph
Tiny Symphyla - a "garden" centipede, which is not actually a centipede, in spite of being related to them. This is floating on a pool of water.
Modelling by Beth
And another dipura, doing the same. There were a lot of them here.
Modelling by Bob
The passage ends at a climb down to the streamway, opposite the second entrance.
Modelling by Steph, lighting by Tarquin and Steph
Crawling towards the third entrance.
Modelling by Steph, lighting by Tarquin and Steph
The passage leading to the third entrance.
Modelling by Steph, lighting by Tarquin and Steph
The reason Steph had stopped is this spider's web. There is only one way to make progress along the passage.
Modelling by Steph, lighting by Tarquin and Steph
Reaching surface.
Modelling by Steph, lighting by Sol
The dismount out of the entrance is entertaining, and often involves an unglamorous flop, but Steph managed it with some level of grace.
Modelling by Steph, lighting by Sol
Just around the cliff is the entrance to Pylon Cave.
Modelling by Steph, lighting by Sol
It starts with a crawl over soil and bat guano, into a little chamber.
Modelling by Steph, lighting by Tarquin, Sol and Steph
Tiny millipede, smaller than the bat guano pieces that it is feeding on.
Modelling by Muncher
More normally coloured Meta menardi in the chamber. Being photophobic, she instantly turned away when I tried to take her picture.
Modelling by Cerys
The slope down from the chamber into a lower chamber.
Modelling by Tarquin's glove and Steph, lighting by Tarquin and Steph
Steph reported that the lower part of the chamber was full of lesser horseshoe bats, so we left them alone and headed elsewhere.
Modelling by Steph, lighting by Tarquin and Steph
Waterfall just upstream in the gorge. We dropped down to the river via a clumsy scramble.
The gorge just downstream of Ogof Clogwyn.
Modelling by Steph
A little further down, the waterfall on the left is Waterfall Cave's resurgence. The main gorge must pass through the Llanelly Shales, which shows just how little distance the former Ogof Clogwyn resurgence could travel before it would start having to flow uphill (entirely possible, as a phreas). The shales form an almost impermiable barrier, it is extremely rare for water to flow from one to the other.
Modelling by Steph, lighting by Tarquin and Steph
The gorge, upstream of Devil's Bridge. By now, it is in the lower limestone beds.
Pwll y Cwm, the major resurgence of Agen Allwedd and Ogof Daren Cilau. Right now, the resurgence is flowing. In extreme drought, the grey river water can be seen flowing into the resurgence, joining the water that continues to flow through the caves. The pool is 14 metres deep (which feels crazy when looking at the top like this), where it breaks into the main sump of Ogof Daren Cilau, bottoming out at 19 metres depth. The story goes that the pool used to be a tiny hole, and was blasted open by the iron workers in the hopes of gaining more water flow, then filled with rubble when the flow did not increase. The rubble slowly slumped into the passage at the bottom. There are all sorts of theories suggesting that the passage could continue on the other side of the river (below the camera), into some unknown conduit, heading to some as yet undiscovered destination.
Modelling by Steph
Just a little downstream is the entrance to Elm Hole, another cave connected to the Daren Cilau sump, and the original through trip to it. The cave is an active resurgence, with the water flow visible by the plastic pipes in front of the entrance. That water always flows, even in drought, but runs clear, while the cave water is stained black from peat, and the river water is cloudy. The cave passage also has a second sump which takes water in flood. Its destination is unknown. There is something unusual happening with the water in this cave system!
Top of the Devil's Waterfall, seen from the Devil's Bridge.
The waterfall's Welsh name is Pwll Cwn, pool of the dogs. It is quite likely that the name Pwll y Cwm, pool of the valley, was a mistake, taken from the waterfall and misread by accident. It is roughly 10 metres high, perhaps a little more.
The path downstream has become very much overgrown over the years, but runs on the right bank. At one point, Bill Gascoigne fell into the waterfall's plunge pool from here, with all his camera equipment, while hoping to photograph the results of a dye trace from the caves downstream. The camera equipment is still down there in the plunge pool.
Modelling by portions of Tarquin
The regular path runs along the top of a cliff dropping all the way down to the river, but a small landslide, seen on the right here, wiped out part of the path. Continuing downstream required us to ascend the bank and make our way around a little higher, without any path.
Modelling by Steph
Fungus on a rotting log, possibly a hairy curtain crust (Stereum hirsutum).
A descent down a gully then brought us down to the river, where this narrow waterfall is on the far bank.
Distant view of the waterfall in its narrow canyon.
Crossing the river with dry feet brought us far enough to see the waterfall, but the view was still obscured.
Wading upstream was the only way to get a better view; wet knees was as bad as it gets. And while this looks like an idyllic heaven, the water is grey not just because of the rocks it flows over, but also because of the outflow from a sewage works upstream, which occasionally has overflow incidents. The smell in the river is noticeable. Such a shame.
Modelling by Steph
Scrambling the cliff gave us a much better view of the Devil's Waterfall/Pwll Cwn.
Watching the waterfall.
Modelling by Steph
The bottom of Cwm Pwca, named after Puck, the character from Shakespeare's A Midsummer Night's Dream, which was supposedly based in this valley.
Entrance to Shakespeare's Cave, with its distinctive crown shape.
Modelling by Steph, lighting by Sol and Steph
The early passage is very wide, but has been blasted into this shape, presumably to try to turn it into a showcave (a terrible idea, since it has nothing of suitable interest, and never becomes wide enough for tourists).
Modelling by Steph, lighting by Tarquin and Steph
Male European cave spider. A much more normal colour, and very different from the one in Ogof Clogwyn. His abdomen is extremely large for a male, but the palps make it very clear that this is a male.
Modelling by Geraint
A more colourful one. This might be female, since it has no palps, but it seems to have proportionately long legs, which suggests it is a juvenile male. Either way, it is a European Cave Spider..
Modelling by Eirian
The passage abruptly splits into a blind alcove, and a narrow rift, which is the way on.
Modelling by Steph, lighting by Tarquin and Steph
The narrow rift issues a stream, which fogs up the passage significantly.
Modelling by Steph, lighting by Tarquin and Steph
The narrow rift.
Modelling by Steph, lighting by Tarquin and Steph
The first duck. Going any further really needs a wetsuit. Not today.
Lighting by Tarquin and Steph
Arch at floor level in the Gellifelen railway tunnels. The purpose of this arch is not known.
The arch is full of rubble, and may be a drainage adit.
Rainclouds lifting over the Blorenge.
Sunset over the Blorenge.
Sunset over Gilwern Hill (441 metres). On the left is a 500 m high ridge of coal tips connecting Llanelly Hill and the Blorenge (the crags are called Carreg Maen Caro, but the ridge is not named), then Gilwern Hill, Mynydd Llangatwg (530 and 529 metres), Allt yr Esgair (393 metres), Mynydd Llangorse (515 metres), Pen Cerrig-calch (701 metres) in cloud, Waun Fach (811 metres), Pen y Gadair Fawr (800 metres) and the Sugar Loaf (596 metres) in cloud.
Sunset over Allt yr Esgair and Mynydd Llangors.
Wild ponies at Pwll Du. Judging by the skewbald pattern, these are partly Welsh mountain ponies, and partly gypsy cob, since the pied gene is not naturally found in Welsh mountain ponies.
Sunset and wild ponies, with an inversion at Pwll Du. What an incredible end to the day.