4 minute read
Caving Phil Hendy
Caves found south of Black Down
INnormal years (not this one) the impervious sandstone summit of Black Down collects rainwater, which forms streams which flow down the hill. Over countless millennia these streams sank underground where they met the more absorbent shales and limestone and formed the swallet caves which are so popular with cavers today. Most of the Burrington caves no longer swallow surface water, except in very wet weather, although the exceptions are Read’s cavern and East Twin Brook Swallet.
Some such as Goatchurch Cavern and Pierre’s Pot have small streams flowing deep in their inner recesses.
South of the hill, the streams are larger and more persistent, and there are a number of active swallet caves south of the road from Charterhouse to Tyning’s. The largest is Charterhouse Cave, which has been proved to take the water from nearby G.B. Cave, once itself one of the largest and most impressive on Mendip.
Longwood Swallet is a long and sporting wet cave and there are several caves in the Blackmoor area of Charterhouse, although you have to go underground to find their streamways.
Between G.B. Cave and the Blackmoor swallets, there is an active stream sink in the shallow valley below a farm. Manor Farm Swallet first drew the attention of cavers from a variety of clubs as early as 1947. Initially they dug at the actual place where the water sank underground.
The shaft was very unstable and collapsed several times, until in 1966 members of the University of Bristol Speleological Society entered a small chamber at a depth of 20 metres. Once again the shaft collapsed, but spurred on by their discovery, the diggers decided to blast a shaft in solid rock a short distance away.
Work continued until July 1968, when the unprecedented storm which caused extensive flood damage to the north, as far as Bristol, caused a huge collapse which re-opened the chamber. The shaft in solid rock was then extended sideways to connect with a choked rift at the base of the collapse. The original shaft was then backfilled with rubbish.
The North Hill Association of Advanced Speleologists (NHASA), a group drawn from various Mendip clubs, then took the dig over in 1972 and entered the cave proper a year later. Below the entrance shaft, a five-metre shaft, September Rift, leads into the cave itself. It can be free-climbed, but many cavers prefer to use a ladder.
At the bottom of this pitch is the start of a larger passage, where the stream is first encountered, if it is running. The way descends to Curtain Chamber, with its impressive formation. A six-metre pitch then follows, which can be bypassed. Here an inlet passage, Upstream Passage, is met with. This has a small stream, and at around 80 metres long runs up to end quite close to the surface.
The main passage is roomy and leads past the two three-metre climbs, the Fluted Pots, to a squeeze, Albert’s Eye. Albert Francis, one of the NHASA diggers, got grit in his eye here while excavating. The squeeze can become a sump in wet weather, which then becomes the end of the cave.
In dry conditions, cavers can continue, the cave descending all the while, past false floors and inlets and a sharp bend, John Ham’s Corner. John, another NHASA stalwart, was trapped here for a while when a rock fell onto him. Eventually the cave terminates in a choke, where the stream is lost.
There are four main side passages or inlets, the longest being NHASA Gallery, reached by ascending a black calcited ledge and climbing up through a small gap between boulders. The Gallery runs above and beyond the main passage for
With PHILIP HENDY
around 100 metres. There are some fine formations.
At the end of NHASA Gallery, there is an unstable extension, Silence of the Lamb, dug into by a group calling themselves the Fat Belly Boyes in 2009. Fleet Street, another inlet, begins at Stream Junction, a short way beyond Albert’s Eye. A difficult ascent leads to a polluted stream passage.
After crawling through a muddy pool, Boulder Fall Chamber is reached. This is 12 metres high. A climb up a boulder slope and a crawl along a muddy ledge leads to two awkward passages. This inlet is a real collector’s piece, found by London cavers in 1980.
Just before NHASA Gallery the Salisbury Caving Group climbed up into Sarum Inlet in 1975. This series is difficult and like other inlets, polluted, but there are some small well-decorated grottoes.
Manor Farm Swallet is adjacent to a footpath and, at the farmer’s request, the entrance was made more secure recently by the construction of a locked blockhouse. Permission to enter (with a goodwill fee) is usually available at the farm, although in the summer months, high levels of carbon dioxide may lead to access being denied.
In any case, this interesting cave is much more sporting when a good stream is running.
