Ogof Ffynnon Ddu

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Ogof Ffynnon Ddu
LocationUpper Swansea Valley
Coordinates 51°49′27″N3°39′40″W / 51.8243°N 3.6611°W / 51.8243; -3.6611 Coordinates: 51°49′27″N3°39′40″W / 51.8243°N 3.6611°W / 51.8243; -3.6611
Depth274.5 metres (901 ft) [1]
Length59 kilometres (37 mi) [2]
DiscoverySouth Wales Caving Club 1946
Geology Limestone
Entrances3
AccessSouth Wales Caving Club—see website for details
Translationcave of the black spring(Welsh)
Cave survey Survey
Part of the interior with a terraced cascade and three standing and climbing cave explorers wearing safety equipment Inside Ogof Ffynnon Ddu.jpg
Part of the interior with a terraced cascade and three standing and climbing cave explorers wearing safety equipment

Ogof Ffynnon Ddu (Welsh for cave of the black spring), also known informally as OFD, is a cave under a hillside in the area surrounding Penwyllt in the Upper Swansea Valley in South Wales. It is the second longest cave in Wales and the deepest in the United Kingdom.

Contents

History

OFD was discovered in 1946 through digging by Peter Harvey and Ian Nixon, members of the newly formed South Wales Caving Club. [3] 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. [4]

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. [5]

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...[when] swirling water cut off their escape...a rescue party including soldiers from Senny Bridge, men of the R.A.F., and thirty miners set to work to divert the stream above the point where it goes underground...they were brought out into the open air after being trapped for fifty-nine hours..." [6]

In 2021 the cave was the site of the next longest cave rescue undertaken in the UK, after George Linnane, a 38-year-old experienced caver, fell 8 m (26 ft) [7] and sustained multiple injuries on 6 November, 500 m (1,600 ft) from the lower Cwm Dŵr entrance. Almost 250 people were involved in the rescue, which was organised by the South and Mid Wales Cave Rescue Team and involved manually hauling the casualty by stretcher, using relay teams of rescuers, to the top entrance. Linnane was rescued on the evening of 8 November, after 57 hours; the previous longest rescue was 41 hours. [8] [9] [10] [11] [12]

The cave system

With a depth of 274 m (900 ft) and a length of at least 50 kilometres (31 mi), 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. [4] 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). [13]

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. [14] Deep cracks in the vast expanse of stony moorland above provide habitats for plant life, including the lily of the valley and wood anemone, and mossy saxifrage (Saxifraga hypnoides) grows on the limestone outcrops. [5]

National 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. [15]

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OFD may refer to:

This article describes the geology of the Brecon Beacons National Park in mid/south Wales. The area gained national park status in 1957 with the designated area of 1,344 km2 (519 sq mi) including mountain massifs to both the east and west of the Brecon Beacons proper. The geology of the national park consists of a thick succession of sedimentary rocks laid down from the late Ordovician through the Silurian and Devonian to the late Carboniferous period. The rock sequence most closely associated with the park is the Old Red Sandstone from which most of its mountains are formed. The older parts of the succession, in the northwest, were folded and faulted during the Caledonian orogeny. Further faulting and folding, particularly in the south of the park is associated with the Variscan orogeny.

References

  1. ↑ "Ogof Ffynnon Ddu - Surveys". South Wales Caving Club. Retrieved 21 September 2015.
  2. ↑ "Ogof Ffynnon Ddu 1". Cambrian Cave Registry. Cambrian Caving Council. Retrieved 4 November 2019.
  3. ↑ Cave discovery anniversary marked BBC Wales - 16 September 2007
  4. 1 2 "Ogof Ffynnon Ddu 1". Caves of South Wales. Retrieved 28 April 2016.
  5. 1 2 "Ogof Ffynnon Ddu National Nature Reserve". First Nature. Retrieved 28 April 2016.
  6. ↑ Casteret, Norbert (1954). The Darkness Under the Earth. p. 109-110.
  7. ↑ "Survey data in Survex 3D format for the site of the incident" . Retrieved 10 November 2021.
  8. ↑ "Brecon Beacons: Rescuers reach caver stuck in Ogof Ffynnon Ddu since Saturday". 8 November 2021. Retrieved 8 November 2021– via www.bbc.co.uk.
  9. ↑ "Huge mission to rescue man trapped in Brecon Beacons cave for two days". the Guardian. 8 November 2021. Retrieved 8 November 2021.
  10. ↑ Davies, Gareth (8 November 2021). "Cave rescue mission as man falls 50ft leaving him trapped underground in Wales for three days" . Retrieved 8 November 2021– via www.telegraph.co.uk.
  11. ↑ "Brecon Beacons: Man rescued from cave after two days". 8 November 2021. Retrieved 8 November 2021– via www.bbc.co.uk.
  12. ↑ Humphries, Will (9 November 2021). "Wales cave rescue: injured caver joked during 57-hour ordeal". www.thetimes.co.uk. Retrieved 9 November 2021.
  13. ↑ Ogof Ffynnon Ddu, Penwyllt, Brecknockshire, cave survey published by South Wales Caving Club, 2014
  14. ↑ Ford, Trevor D. (2011). Limestones and Caves of Wales. Cambridge University Press. p. 59. ISBN   978-0-521-16913-4.
  15. ↑ "Ogof Ffynnon Ddu National Nature Reserve, near Ystradgynlais". Natural Resources Wales. Retrieved 3 September 2020.
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