Ogof Agen Allwedd or Agen Allwedd, is, at , one of the longest

cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

systems in

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

, and the longest cave system on the

Llangattock Llangattock ( cy, Llangatwg) is a village, community and electoral ward in the Brecon Beacons National Park in Powys, Wales. It lies in the Usk Valley just across the river from the town of Crickhowell. The Monmouthshire and Brecon Canal passe ...

escarpment An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations. The terms ''scarp'' and ''scarp face'' are often used interchangeably with ''escar ...

History

The cave was first investigated by Brian Price and party in 1949 and 1950, but it was not until 1957 that the Hereford Caving Club broke through the First Boulder Choke and found the main part of the cave. The cave system was further explored in 1971 by John Parker, J Phillips and others who dived through sumps and extended the known length of the cave. Further exploration in 1973 by Martyn Farr and Roger Solari resulted in a fatality when Solari failed to return from a dive. This section of cave was later named the "Remembrance Series".

The cave system

Ogof Agen Allwedd is the longest cave system on the

, with over of passages. There are several round trips that can be followed within the system, but all trips start via the short entrance series and first boulder choke. Crawling is required for the long entrance passages but most of the cave consists of large stream passages which provide easy

caving Caving – also known as spelunking in the United States and Canada and potholing in the United Kingdom and Ireland – is the recreational pastime of exploring wild cave systems (as distinguished from show caves). In contrast, speleology i ...

and no specialist equipment is required. The round trips include the Grand Circle - along Main Stream Passage, which has four

boulder choke A boulder choke is a collection of large rocks or rubble that obstructs a shaft or passage in a cave or mine. In order to progress through passages cavers often need to negotiate or clear boulder chokes. Boulder chokes can be formed by rockfall, ...

s (rock obstructed passages) in it, and Southern Stream Passage, a long, wet and tedious passage. There are also the Outer and the Inner Circles, which include Turkey Streamway; with some formations including gour pools. Each round trip takes upwards of six hours and some parts of the cave are prone to flooding. The sump at the 3rd Boulder Choke soon becomes water-filled, and in worse flood conditions it becomes impossible to negotiate the 2nd Boulder Choke and the narrow section of Turkey Streamway above Northwest Junction. Maytime and the Lower Main Stream become inaccessible under flood conditions. In general, Agen Allwedd contains few formations. Agen Allwedd is also important due to the numbers of bats that roost there. Bats are strictly protected from disturbance under the Wildlife & Countryside Act 1981, the Habitat Regulations 1994 and the EC Habitats Directive. It is a criminal offence to deliberately or recklessly disturb bats. Cavers should take care to avoid causing disturbance.

Access

Originally, the cave was accessed through the Agen Allwedd entrance, but gated access is now available through the Ogof Gam entrance. This provides a bypass to an awkward rift section and that route is now blocked with a pillar. Keys are available to people with valid permits who must sign the book on entering the cave indicating the route to be taken. No carbide is to be used in the cave and additional permits are required for camping inside, blasting or research.

References

{{DEFAULTSORT:Agen Allwedd Wild caves Limestone caves Caves of Powys Brecon Beacons