20 November 2020

Aygill Caverns warning

The CNCC has become aware of some potentially serious hydrological changes at Aygill Caverns.

A visitor to the cave has reported on the UK Caving Forum that erosion of the stream bank just downstream of the entrance to Aygill Caverns has drastically altered the local hydrology of Aygill, with serious consequences for access to the cave. The following is modified from their report:

The gill has been steadily eating away at the bank for several years now, but without significant impact on access to the cave. This has all changed in the past two months.

On the 7th October during a resurvey trip the normal dry route to the Traverse Pitch was taken. At the bottom of the pitch a significant stream was found flowing from the upstream passage, which for many years has only contributed a trickle or small stream at best. The large stream was now flowing into the short low tube which leads to the second pitch and the main cave. The tube wasn't attempted, but would likely have been 'sporting' at the very least, and the pitch would have been very serious.

On the 18th November another trip was made to check on the water below the Traverse Pitch, as it was noticed that more of the surface stream appeared to be sinking than a month earlier. On this occasion the caver was stopped 10m into the cave where a low crawl and short rift descend to a squeeze or wriggle through to an enlargement. This normally dry route was completely engulfed by a large stream issuing from the roof and falling down the rift to the squeeze. This made it inaccessable.

On the 19th November, after 24+ hrs without rain, the explorer returned to take another look at the situation. The surface stream had subsided to a moderate-to-normal flow. Once again 10m into the cave a large inlet was met and, although slightly less boisterous than the previous day, it effectively stopped any further investigation. New cavities in the roof and wall suggest that the stream has loosened a lot of boulders which will have been washed down and most likely choked up against the squeeze at the bottom of the rift.

Effectively this situation closes the cave, either until a period of much drier weather, or until an efficient dam is built around the new sink.

Keep an eye on the Aygill Caverns page on the CNCC website for further information.

Photo: Entrance to Aygill Caverns in dry conditions (prior to these changes)


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