OGOF CLOGWYN LLANELLY
NGR SO 2129 1238 A 770 feet
L 1150 feet
see page 26 for survey. VR 20 feet
From the lay-by on the Heads of the Valleys road at Black Rock, follow the road uphill for ¼ mile. About 25 yards before the electricity pylon a steep pathway leads down to the river. The cave is on the opposite bank a few feet downstream, about 20 feet above the river. A small stream usually issues from the opening. In the Dowlais limestone.
A good cave for beginners. The caves contains some fine examples of rock shelves, developed by phreatic action, cf photo on front cover. The main entrance is above a small overhang which can be ascended without much difficulty. There are two more very tight entrances to the right. The entrance leads directly to an active stream passage with fine rock shelves. The water is quite deep in a few places but can be easily traversed. The passage is followed to the sump at the end. A few feet before the main sump, a crawl low down on the right hand wall can be followed to another smaller sump.
At one of the right-angle turns in the streamway, a high level muddy passage can be followed back towards the cliff face where daylight can be seen through an impenetrable crack. The passage then turns right and becomes larger but soon ends.
The cave has been know for a long time, but the first recorded exploration was by the SWCC in 1951, inscriptions on the walls date from 1850. In 1996, Duncan Price (ChSS) dived the terminal sump, but the heavily silted and constricted end of the underwater passage means that further extension is unlikely, however work continues.
References:
ACG&AS N/L April 1964. Dived by Mike Jeanmaire for 30 feet but way on blocked by silt.
BC 22 85-86; 95-96; 25 9-16; 26 46-48; 29 70-74
CDG N/L (63) 17; (76) 17; (117) 17 dived for 60 feet;(121) 33 dived for 100 feet.
CSI p 9
CWM p 76
Descent (126) 9
HCC N/L (4) 10-12; (5) 2; (12) April 1960 sump lowered 5 inches by pumping.
Stratford p 31
SWCC N/L May 1951; Our Caves (5) 4 pp S.
see page 26 for survey