Cambrian Cave Registry

L:426 V:74	Blaen Onneu Quarry Pot, Blaen Onneu Cave No.2, Pwll Blaen Onneu NGR: SO 15887 16216 498 m.asl Powys , Northern Outcrop - East (Morlais to Abergavenny)			map using leaflet map:
			Pothole
Access	This pothole is in a disused quarry, 460m North West of the summit of the Beaufort to Llangynidr road. A gate has been installed in the passage leading to the Southern extensions.
Description	The entrance is a small hole in the quarry floor opening out into the passage below. The pitch is about 3.6 m deep and can be descended with the help of a ladder or rope. The passage entered is a high rift and can be followed to the north and to the south. To the north, the passage soon reaches a narrow pitch. Belay ladder or rope to an iron bar wedged between the walls. At the bottom of the pitch a rift passage leads to a shattered area and then to a smaller passage with several squeezes leading to a chamber. A small passage to the right leads to a narrow meander which lowers to a crawl and ends at a choke. On the other side of the chamber is a large boulder choke, this can be passed on the left to a space above the choke and a 2.2 m pitch into another chamber. On the far side a crawl leads to another chamber. To the south, from below the entrance pitch, the high rift descends over boulders before the roof lowers at a shattered area. An excavated crawl beyond the gate then leads to the Twin Peaks, a 9 m pitch. Two small passages lead northwest and southeast from the bottom of the pitch but both end within a short distance. The way on is via an excavated hole in a small chamber to the north of Twin peaks. This leads to a tight crawl and a 5 m pitch into a chamber. From here a passage runs southeast and a small stream is met and can be followed to end at a draugting aven and loose boulders....
History	SWCC 1948. Extended by Llanelly Diggers 1990
Hydrology	Spore tested to Ffynnon Gisfaen in under 6 days			Tests
Conservation	SSSI: 3159 Mynydd Llangynidr(Geological)
Gallery
^{Brendan Marris} 2009	^{Martin Laverty} 2025
Survey
BNS Journal 1, 2-3, 1959; Llanelly Diggers 1991, 1992; Pelobates 64
References
Cullingford, C.H.D. (1951) Exploring Caves,p.63
BNS Journal 1, 2-3, 1959. Discovery of extension
Descent 98, 26-27. Ashley Dickenson, Blaen Onneu Quarry Pot Grows [Northern Extensions]
Descent 106, 34-35. Ashley Dickenson, Blaen Onneu Quarry Pot [Southern Extensions]
CaC 56, p.19, 1992, Blaen Onneau Quarry Pot extended and dye traced
Caves of South Wales, Stratford, T., 1995
A Caver's View of the Clydach River (Cwmbran Caving Club, 1986), Schuurmans, T.
Pelobates 64, 1994
Brendan Marris Caves of South Wales
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Cambrian Cave Registry entry 797		Comment? Email registrar@cambriancavingcouncil.org.uk	© Caving Wales ⓗ Ogofa Cymru