Siambri Ddu, Siambre Ddu, Black Cavern

NGR: SO 25074 11516
396 m.asl

Monmouthshire , Northern Outcrop - East (Morlais to Abergavenny)
map using leaflet map:
Access On the Blaenavon to Abergavenny road, take the Pwlldu road and park 0.5 miles from the turning. Walk for about 0.5 miles to a quarry, the entrance is in the old tram track above the limestone quarry.
Description A 9m crawl leads to a very large and somewhat unstable chamber which is 36m long and 25m wide. The roof is in millstone grit.
History CCC, 1967
SSSI: 0057 Siambre Ddu (Mixed)
CCC (1967)
Wessex CC (1977)
Playford, P. (1967) The discovery of Black Cavern Pwll Ddu, CCC Jnl. 1 pp.12-14
Welsh Geological Quarterly, 4(1) pp.38-39, (1968), P.H.Playford, A cavern below the Millstone Grit near Abergavenny
BCRA Trans 1(3) p.150, Trevor M.Thomas, The South Wales Interstratal Karst (1974)
Davies, C.W. (1978) The Black Cavern, Pwll Ddu, Wessex CC Jnl.172 pp.41-46
CKS 27(3),p.130, Owen Clarke, Conditions in caves and other karst features in the Pwll Du area at the time of the Namurian trangression
Brendan Marris Caves of South Wales
Cambrian Cave Registry entry 857
© Cambrian Caving Council ⓗ 2017