History
OFD was discovered in 1946 through digging by Peter Harvey and Ian Nixon, members of the newly formed South Wales Caving Club. Exploration beyond the Boulder Chamber in 1957 revealed passages as far as the Dip Sump. Major extensions were discovered in 1967 through to Cwm Dŵr, which is now known as OFD2. The system is famous for its intricate maze-like structure and its impressive main stream passage. It is now part of the Ogof Ffynnon Ddu National Nature Reserve, which includes the ruined remains of a former brickworks, including several kilns, quarry workings and tramroad tracks. The terrace of workers' cottages is now occupied by the South Wales Caving Club. The cave has seen many minor incidents resulting from people getting lost or tired, or surprised by flooding, and various accidents such as falls which are handled by volunteer cave rescue teams who are alerted by the police. More prolonged rescues have included: In 1951, before cave rescue was well established, "two well-known members of the South Wales Caving Club, Lewis Railton and W.H.Little, made their way into the huge cave that bears the Welsh name of Ogof-Y Ffynnon Ddu (Cave of the Black Well or Stream) in South Wales...The cave system
With a depth of and a length of at least , it is the deepest cave in the UK and the second-longest in Wales. The passages and chambers of Ogof Ffynnon Ddu weave a tortuous path beneath the east side of the Tawe Valley. The stream passage cuts through black limestone producing waterfalls, rapids, deep potholes and scalloped walls. The system is divided into three parts: the lowermost (western) section is referred to as Ogof Ffynnon Ddu I (or simply OFD I), the central section as Ogof Ffynnon Ddu II (or OFD II) and the uppermost (eastern) section as Ogof Ffynnon Ddu III (or OFD III). A variety of specialised wildlife has developed underground including cave shrimps and the pale blanched trout endemic to pure underground fresh water courses with sufficient plankton. Deep cracks in the vast expanse of stony moorland above provide habitats for plant life, including theNational Nature Reserve (NNR)
The name Ogof Ffynnon Ddu has also been applied to an extensive tract of moorland, rocks and cave systems of which the eponymous cave is a part. It was designated as an NNR because of its unique geology, floristic diversity, its industrial past and its subterranean animal and plant life.References
External links
{{commons, Ogof Ffynnon Ddu National Nature Reserve