 Ogof Fawr - Cwm Cadlan |
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Overview
A large sink in a massive shakehole marks the location of Ogof Fawr, the original route into the cave followed the water down at the base of the cliffs of steeply dipping limestone. A new safer entrance on dry ground at the back of the shakehole was dug to provide a dry and more stable route into the cave after it had been discovered.Length 1300m +
Altitude 326m
Grid SN 98550 09610
History
As a large sink this site has received the attention of digging teams over many years. Unfortunately the severe winter floods washed rock in to fill the passage cleared by successive digging teams. Since 1969 digging teams from Westminster SG, Croydon Caving Club, Cwmbram Caving Club and Westminster Caving Club had all made significant digging efforts at the site, but all thwarted by the significant amount of rock moved down the stream bed to fill their efforts during the winter floods. In 2007 a new effort was made led by Tony Donovan, Paul Quill and Roy Morgan which in 2008 broke through the unstable entrance sink to intersect chambers and cave passage beyond.
Location
From Penderyn take the Cwm Cadlan Road from the junction at the Lamb Hotel. The road should be followed up onto the open moorland where you are able to park due North of the entrance shakehole. By heading 1.3km due south you will reach the valley that contains Nant Cadlan that flows to the shakehole and sink of Ogof Fawr. The dry entrance is in the base of the cliff at the back of the shakehole.Sychryd & Hepste map showing the location of Ogof Fawr.
Access
No known access restrictions.The cave is very near a National Grid gas storage facility so security is very tight if approached from the forestry to the South East.
Description
Ogof Fawr is a recently discovered cave, having being entered by the diggers after a concerted period of excavation. The site has been long known as a large stream sinks at this site and in view of the potential was named Ogof Fawr (large cave) another small site lower down the valley was called Ogof Fechan (little cave). The irony was that after prolonged digging very little cave was found at Fawr, but Fechan yielded a sizeable stream cave. This cave is formed in steeply dipping beds of limestone and is out of character with most caves in South Wales. In many ways it is similar to Ogof Fechan as the cave is extremely flood prone and most passages are covered in a thin film of mud making the cave feel very oppressive. It cannot be understated how at risk of flood this cave is, with debris found up to 2m above the cave sink after heavy rain. In wet weather the cave completely floods in large sections, this is a cave to avoid in unsettled weather.
The stream sinks in a cliff face in a very large depression, flooding causes the original entrance route through boulders to rearrange regularly, a new drier entrance has been engineered near the cliff face at the back of the depression. A descending passage following the dipping beds of limestone drops you a scaffolded shaft that leads to a further crawl and climb down in lower bedding planes. This finally drops via a short climb down into the top of a chamber, in which close by on the right hand wall by a large boulder is a rope climb down. From the bottom of the rope climb you find a small passage leading off on the right. This brings you into a second chamber where you traverse across loose boulders to descend near the right hand wall. This steeply descending passage is then followed to meet the water further down and continues to a junction with a large flat topped boulder in the centre. Ahead the water descends a narrow rift to enter a large steeply descending chamber. The water sinks in the boulders at the top of the chamber, at the bottom end of the chamber a climb down through mud covered boulders leads back to the stream which quickly disappears into a boulder choke. In wet weather water backs up here very badly, the whole chamber filling up with water, foam can be found over the flat topped boulder back at the junction. From the junction a passage leads off to the right and continues for a long distance as a linear passage cutting across the dip of the rock. The whole passage is covered in a thin film of mud and it is clear from this and damage to the conservation tapes that much of this passage floods in wet weather. A section of this passage contains fine mud covered calcite formations before the passage assumes a more phreatic tube and passes under an impressive rock bridge. From here the passage passes a through faults and more unstable rock past several squeezes to follow a hole in the floor and a low level crawl. This then enters a more phreatic section of passage after a fault is passed where the route splits several times most passages joining back together. At the end of this most open section of passage a boulder choke is passed dropping between rocks into more passage. Now the passage is more controlled by bedding planes and in places high and low level routes are possible in the same bedding plane. The cave ends in a wide low section of cave with layers of rock that have peeled off from the ceiling.
Tackle
No tackle required
References
Cambrian Cave Registry for Ogof Fawr UK Caving Wiki Entry for Ogof Fawr
Warnings
This whole cave is very unstable and extremely flood prone - treat with due care.
Disclaimer
The photographs and information of this page has been provided to help cavers planning trips. Caving can be a dangerous activity, if you are interested in exploring caves please join a caving club so you can enjoy a safe introduction to this sport. Local caving clubs are listed on the links page or you can visit try caving for more options.If you feel that any of the information is incorrect or should be updated please contact us.
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