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The Discovery of St. Cuthbert’s 2

Roy Bennett

The passing of the original sump and its conversion into ‘The Duck’ by Don Coase and John Buxton in 1957 lead, not to the large extension hoped for, but to a much more formidable problem.  This second barrier, soon called just ‘The Sump’, appeared heavily silted up and no further progress was made until 1963 when Mike Thompson, Steve Wyn-Roberts, Fred Davies and John Attwood, diving and digging under very difficult conditions penetrated about 14ft. straight in.

Interest waned after this, and various alternatives were conjectured and worked on.  Further inspection of the roof of Gour Hall and Gour Rift revealed no possibilities except for a small hole which could not be reached.  Digging at the lower end of the Gour Rift appeared a logical alternative, and much work was done by John Cornwell.  This was finally defeated by water penetration, leaving as a useful memento a bypass to the Duck.

The challenge of the sump was taken up again in 1967 when Phil Kingston, Barry Lane ands Colin Priddle penetrated some 12ft. inwards by some 8ft. to the right.  This started with the ‘Great Sump Digging Weekend’, which though defeated by flood waters, was followed by a steady progress.  The divers had reached a point at which the sump appeared to be opening up, when possible success was dashed away by the ‘Great Mendip Flood’ in 1968 and the sump reverted to its primitive choked condition.

Meanwhile, buck up-cave, the Dining Room Dig, started years previously, was being dug regularly and intensively by a combined B.E.C. and S.M.C.C. team.  The ultimate objective was to bypass the Sump and much work was done by Dave Irwin, Bob Craig, Martin Webster, Brian Woodword, John Riley, Dave Turner, Derek Harding and many others revealed a completely choked passage along a fault going in the right direction.  Ultimately work on this slowed when a distance of some 150ft. had been (mainly) excavated and problems of spoil disposal were becoming acute. It was time for a reappraisal. Sufficient of the fault had been uncovered to enable an accurate projection down cave to be made, and this showed that it should intersect the know Sump passage at a point where a choked side passage pointed in the right direction.  It was decided therefore to leave the dig pro-tem and, the now rather depleted team augmented itself and transferred its attention to the Sump itself.

The plan was to implement a scheme mooted by various people and pushed by Dave Irwin to dam the stream and pump out and excavate the Sump.  Dams had already been built at the Mineries and by Bob Craig, Martin Mills, Alan Butcher, Jok Orr and others, and in the Main Stream Passage, but the crucial one in Gour rift was only just above stream level.  Work was started to make this into a strong, reliable structure as a failure would be very dangerous to any one working in the sump. The foundations were dug down to the stalagmite gours over the complete width and thickness and the dam built up using concrete throughout. This was made up using grave, sand and stones available on site.  Even though the stream levels at the bottom of the cave was very low, it was thought that the opportunities afforded by the dry summer had been missed, and the dam system would only be operated the following year.  This situation was completely altered when there occurred a stroke of luck of the kind that comes rarely.  After a dam building session, two of the team had a look at the sump, and found to their great surprise that the sump pool had disappeared, leaving the stream to flow down a gravel slope to vanish where this met the roof.  This was a most remarkable and sudden change in a sump that previously had been quite stable, even when the stream had been dammed up completely.

Two great uncertainties accompanied the opportunity.  Firstly the unusually dry weather could not be expected to continue for long (it was already the 30th of September) and secondly the change in the sump could not perhaps be permanent.  The first was countered both by continuing work on Gour Rift dam at the same time as digging the Sump, and increasing the number of trips.  Nothing could be done about the second.

The dam finally rose to some 5ft. high, tapering from 5ft. thick at the base, and to some 2ft. at the top. It was furnished with an 8in. diameter pipe in the base with a removable plug that could be used as a butterfly valve to let the water out gently.

Initial progress at the Sump dig was very rapid with the water providing no hindrance.  Late on stream flow had to be cut off to enable work to continue, firstly using a temporary dam in the Sump Passage, and later using the concrete dam as well.  The water level varied erratically, hampering work at times. The Sump refused to empty on one occasion, causing great despondency, but the soak-away gradually re-opened over the following week.  The dry weather miraculously held, however, and the team (Roy Bennett, Bob Craig, Tim Large, John Riley, Martin Mills, Martin Webster and others) pressed ahead with trips of increasing frequency and duration.  The roof of the sump sloped downwards to an arch with a slight rise beyond, and then levelled off with the stream going to the left.  All traces of the previous excavations appeared to have vanished in the 1968 Flood and nowhere was there more than a few inches of space between the gravel and roof.  The rift encountered by the second diving team was not found and it appears they went further left again, probably following the pre-flood stream course.

The diggers eventually reach a point where the roof started to lower again, and the stream disappeared in a choked-up hole in solid rock.  At this point a draught could be felt, and when the stream was cut off the water in this hole disappeared with sounds of violent bubbling and rushings or air. This was the situation on Friday evening 31st. October, when the dam building party had gone out, leaving only Martin Mills, Martin Huaun, John Riley and Roy Bennett at the dig.  To obtain more working a gravel bank on the right of the dig was cut out back to where the roof appeared to rise a little.  To the surprise of the diggers, the roof continued to slope upwards in its direction and soon Milch could say “I can see 10ft. along a bedding plane, about 30ft, into a chamber.”  Cuthbert’s 2 was open, and after a quick look at the dams the party set off moving quite rapidly.

 

The ‘chamber’ turned out to be the beginning of a high rift passage with a slippery floor obviously occupied by the stream.  Near the Sump the passage was quite wide with a ‘tide mark’ of red mud about 5ft. high. Everywhere the wall were coated with thick deposits of soft brown mud which could only have been left by standing water,  The dullness was lighted by various stalagmite deposits.  A decorated hole in the roof attracted attention because of the odd watery noises emitted, while further down the passage a stal. Barrier allowed just enough room to crawl under.  The rift was narrower further down, but remained high most of the way. A 10ft. pot was reached and climbed down, and the passage continued narrower again until a mud coated stalagmite barrier was reached.  The passage clearly continued further, but it was decided to turn back at this first check to easy progress because of the lateness of the hour and the risk of being cut off.

A much larger party entered the following day when Bob Craig, Martin Webster, Martin Mills, Brian Woodward ands others found Sump 2 a little way beyond the stal. barrier. They were joined by the rest of the Friday Team, and various things we looked at.  A very tight rift going back up cave from near Sump 1 was pushed to about 100ft. by Martin Webster.  A dig was started in a hole near this point on the left hand side of the main passage.  This was of great interest as it may well connect with the steam leaving Sump1via the soak away.  A little way downstream from the 10ft. pot, a climb was made up the right hand (W) wall to a point at which a scoop in the wall containing mud formations could be overlooked.  Nothing leading off was found, but the climb could easily be continued with some protection, and there is a good air circulation at this point.  The second sump was found to be constricted, but the level could be reduced by a little bailing.  Dave Irwin and Mike Luckwill joined the party and did a quick Grade 4 survey, which showed the passage to be heading south.  This was unexpected and suggests that the water has now left the Gour Hall fault line and is on its way to Wookey.

One further exploration trip has been done to date (15-11-69) when Brian Woodward used diving kit in Sump 2, finding it heavily mud chocked.  More progress could be made without kit by digging and bailing and the sump does not appear to be very deep.

Further exploration work was inhibited by the risk of being cut off.  Initially it was hoped to clear the sump out and lower the level sufficiently to make it a free dive, and much work was done to cut out a trench and remove the bank on the downstream side.

The inevitable end of the dry weather meant less and less time being available before the dams overflowed.  A rope had been fixed through the sump but it was still too constricted to be free dived. Trips were done by leaving one person on the near side to release the dammed water, and seal it off again to let the party out.  This procedure relied entirely on the continued functioning of the soak away, and there were some alarming underwater incidents as the stream level kept on rising.

Eventually the sump could not be drained at all and Cuthbert’s 2 was closed for a time.  This problem has been temporarily solved by conducting the stream through the sump in a pipe.  This was made possible by joining 5ft. sections of 8in. diameter fibre glass pipe with polythene sheet secured by aluminium strips.  The pipe was only got into position when the stream levels in the bottom of the cave were reduced by means of the surface dams at the Mineries Pool.  The increased water flows through the sump have caused rapid silting, and it appears unlikely that it can be kept open as a free dive.  Other alternatives are being worked on and it is hoped it will soon be possible to continue exploration, free from fear of being cut off.

The chances of further progress are fairly good with more than 100ft height difference to Wookey Hole.

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