Porth Yr Ogof
   HOME

TheInfoList



OR:

Porth yr Ogof is a
solutional cave A solutional cave, solution cave, or karst cave is a cave usually formed in a soluble rock like limestone (Calcium carbonate, with chemical formula ''CaCO3''). It is the most frequently occurring type of cave. It can also form in other rocks, incl ...
near the village of Ystradfellte, near the southern boundary of the
Brecon Beacons National Park Brecon Beacons National Park, officially named Bannau Brycheiniog National Park (), is a National parks of the United Kingdom, national park in Wales. It is named after the Brecon Beacons (), the mountain range at its centre. The national park ...
in
Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...
. It lies on the course of the Afon Mellte, a river whose name translates as 'lightning', commonly explained as a reference to the "flashy" nature of the river, i.e. its rising and falling rapidly in response to rainfall. In 1998 the cave's passageways had been measured as over in length. Among the cave's fifteen entrances is the largest cave entrance in Wales and one of the largest in the UK, nearly wide and high. The cave was used as a
show cave A show cave—also called tourist cave, public cave, and, in the United States, commercial cave—is a cave which has been made accessible to the public for guided visits. Definition A show cave is a cave that has been made accessible to ...
many years ago, but is not as attractive as more decorated caves such as Dan yr Ogof, and so today is more often used to introduce people to cave exploration.


Cave features

Porth yr Ogof is most often entered through the wide main entrance, either using a dry ledge on the left or by wading through the knee-deep river to the centre and right. The second most used entrance is called the Workman's or Tradesman's Entrance. A passage in the left of this entrance leads to a mud cavern. Challenging elements of the cave interior include the "Wormhole" (a curving crawl tube on the right wall of the main entrance), the "Letterbox" (a rectangular space in the passage) and the "Creek", further inside the cave. There are also two features named the "Washing Machine", both of which feature large expanses of water. Porth yr Ogof is now uncommercialised, and is used as a training cave for caving. There are two short
pothole A pothole is a pot-shaped depression in a road surface, usually asphalt pavement, where traffic has removed broken pieces of the pavement. It is usually the result of water in the underlying soil structure and traffic passing over the affecte ...
s easily accessible to amateur potholers. The cave is generally wet. White Horse Pool, named after the shape of the calcite deposit on the back wall, is several metres in depth despite the shallowness of the edges, and there are many sumps (completely flooded passageways), the majority of which exist in the portions of the cave north of the Tradesman's Entrance.


Deaths

There have been eleven deaths at Porth yr Ogof since 1957, ten of which occurred in the cold, fast-flowing and deep Resurgence Pool at the far end of the cave where the Afon Mellte resurges.


Geological and human history

'Porth yr Ogof' is Welsh, translated as 'gateway to the cave'. The cave lies in the valley of the Afon Mellte and is located in a comparatively narrow band of Carboniferous Limestone. Except after periods of heavy rain, the river bed is largely dry downstream of Ystradfellte, the river only rising to the surface again just before the cave. The cave and its many visible
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
s were mentioned in the writings of Edward Lhuyd, and in the 19th century it was mentioned again by the first pioneers of caving, notably T.A.J. Braithwaite as noted in a publication named ''Caves & Caving'' circa 1936.


References

{{reflist Tourist attractions in Powys Caves of Powys Fforest Fawr Closed show caves in the United Kingdom