Exploring the downstream sumps in Wigmore Swallet (1)

The following account is extracted from the Somerset Sump Index and I am grateful to Duncan Price for his help with this.


Following a 14 year dig at this site, the BEC passed a narrow entrance series to enter a main drain containing some 50 m of streamway on 12 August 1991.   Upstream and downstream sumps proved passable.   The cave is initially formed in a washed-out calcite vein in Red Marl turning to Dolomitic Conglomerate lower down and with the downstream stream running on a bed of shale.   The main stream has been dye traced to Cheddar Risings, some 9.2 km with a flow time of 42 hours.   In mid-1993 the main stream was dye traced from Attborough Swallet but a trace from Tor Hole a few months later proved negative.   There is more water in the streamway than can be accounted for by Attborough Swallet alone and it is conjectured that the remaining flow is from ground seepage.   The depth from Wigmore entrance to the bottom of Sump 3 in Goughs Cave is some 296 m (971 ft) - potentially one of the deepest caves in Great Britain.   The cave water is invariably sweetened by run-off from the farm above, particularly in winter when the cows are in the farmyard.

The Downstream Sumps

Downstream Sump 1 is 22 m long, quite roomy but with nodules and projections to catch the unwary. Easy access and egress. Permanent line.

18 August 1991    Divers: A R Jarratt, P Bolt, G Johnson, V Simmonds

The aim was to insert M C McDonald in the downstream sump. Unfortunately he was unable to pass a squeeze en route. D Bradshaw then failed to dive, not knowing there was MCM's spare wetsuit available. The diggers, prospective or retired divers, were forced to have a bash.

A reconnaissance dive was made by PB and GJ in the downstream Sump 1 for 8 m to a depth of 4 m using base-fed line and a mini bottle. Despite bad visibility this is a promising site.
CDG NL 101:18 (1991)

On the 20 August 1991, Dany Bradshaw made a tentative foray into the downstream Sump 1, finally passing it after 22 m on 20 October 1991 (no report).

27 November 1992    Diver: R K White

Aim to continue on from work carried out in the autumn of 1991 by Dany Bradshaw in the downstream section of the cave.   After preparatory carrying trips, RKW easily passed DB's downstream 22 m long Sump 1 to 18 m of stooping passage with an ascending inlet on the left. Sump 2 was soon encountered and passed, 5 m long with a small airbell. Some 10 m of passage followed to Sump 3, about 6 m long, to 24m of nice, relatively spacious passage containing a babbling cascade some 2 m high, giving a bit of light relief to the otherwise rather monotonous passage. The passage ended in a large sump pool and Sump 4, about 15 m long, surfacing in a 45 degree inclined rift some 4 m high and 0.75-1 m wide with the stream running in a 'V' slot in the floor.
CDG NL 107:38 (1993)

12 December 1992    Divers: R K White, M C McDonald

After preparatory bottle carries, the divers easily passed downstream Sumps 1 to 4 to the previous limit of 27.11.1992 using smaller bottles than hitherto due to the anticipated restrictions. MCM used 1 x 28 cu ft and 1 x 21 cu ft and RKW used 1 x 28 cu ft and 1 x 17 cu ft. In the rift beyond Sump 4, RKW was ahead so he de-kitted and went forward 10 m where the stream disappeared down a slot in the floor, a continuation of the base of the rift. A waving about of feet, fiddling, grunting and hypothesising indicated that it might go so he returned to fetch the gear. Base-fed by MCM, wearing the 17 cu ft tank and hand-holding the other, RKW slipped feet first into the orifice and after a few minutes of excellent, committed diving passed the 20 m Sump 5 to about 50 m of narrow, high, chert-infested passage to meet the inevitable Sump 6. RKW returned.

MCM then had a go, passing Sump 5 with unexpected ease. Dumping the hand-held set of gear, MCM went forward to RKW's limit at Sump 6. The end of the 50 m lofty, narrow passage beyond Sump 5 ends in a blind pool but a duck to the left leads through to a larger pool. Festering about, MCM tied on, located the continuation and passed the 4 m Sump 6 to yet more varying passage. Low, wide, half-filled with water with lots of chert pendants and nodules. Some 30-40 m of evil passage was pushed, the best method being to stick the gag in the mouth, lie flat out and punt along with the arms. A depressing contents gauge, imminent hypothermia, pressing time and a freezing partner on the right side of Sump 5 forced a retreat, surveying out. The passage continues aquatic - it's only 5 miles to Cheddar. On the return through Sump 5, MCM had difficulty in negotiating a way through the tight upstream section and had to reverse once to make a second, more calculated attempt. The divers surveyed out through sumps 5 to 1. MCM investigated the inlet on downstream left beyond Sump 1; a 45 degrees ascending 1 m wide tube some 20 m long, still going. Time: 8 hours.

Downstream Sumps 1-4 and Sump 6 are all straightforward and, although not tight, are somewhat snug. Sump 5 however must be treated with caution. The upstream section is best attempted feet first with tanks as small as possible. It is essential to stay as low as possible in the base of the rift and not to try and surface too soon on the return. A calm, unhurried approach should find the only route through. Recovery of an injured diver from beyond Sump 5 would be a very daunting prospect.

The whole affair was made even more pleasant by liquid cowsh from the farmyard above which turns the stream into a flowing cess pit. The divers found it much easier laying line from a small SRT bag daintily stuffed with line as thin as possible. All sumps had virtual reality zero visibility. Some belays are a bit suspect due to the lack of sturdy tie points. None of the sumps are deep, perhaps 4 m maximum. The cave beyond Sump 1 had bearings fluctuating between 80 and 90 degrees magnetic However, there may be a mineral vein in the area which may have distorted the compasses as the survey does not seem to make sense when compared with the master survey topside.
CDG NL 107:38 (1993)

27 December 1992    Diver: P Bolt

Sump 6 was passed to reach an obvious long duck (passed by MCM on 12/12/92) in the streamway. Running water could be heard at this point. PB chose to dive the 3-4m of ducks, lining them in the process. Following this PB de-kitted to follow the now walking sized streamway for 15 m to reach a series of cascades leading down into Sump 7. Returning with his tanks PB entered Sump 7 feet first. The sump dropped vertically at the entrance to enter a 0.3-0.5 m high silty bedding at 5-6 m depth. Feeling along the left wall a series of alcoves were searched until eventually the diver entered what felt like a passage and the way on. At this point, much to his relief, his line reel ran out with about 25 m of line laid and an exit was made.
CDG NL 110:23 (1994)

The "3-4m duck" some 20 m beyond Sump 6 varies from 3-6 m in length depending on water conditions. In wet weather the duck is sumped and requires diving but in lower water it is possible to use airspaces between roof pendants to conserve air.

6 January 1993    Divers: M C McDonald, R K White

Aim: to continue on from Pete Bolt's limit of 25 m in downstream Sump 7. Both divers reached sump 7 where RKW with most air dived to PB's limit. After tying on the diver continued for a further 40 m in "adjacent" passage to rise into a large airbell/lake chamber some 5 m in diameter chest-deep in water. Sump 8 followed immediately although the way on was not located due to low air supplies and cold. An uneventful return apart from both divers having a bit of trouble negotiating Sump 5. Sump 7 is deeper than the rest, perhaps 7 m deep, but zero visibility prevents instruments from being read. Sump 6 was re-assessed as being 2 m long. The 5-10 m series of ducks downstream of Sump 6 have been lined for ease of negotiation. Exploration is right at the limit of 28 cu ft tanks and caving wetsuits, but large tanks and diving suits are not a pleasant prospect in this cave. Rescue from beyond Sump 5 would be virtually impossible as a Kirby Morgan mask would not fit through.
CDG NL 107:39 (1993)

21 January 1993    Divers: M C McDonald, R K White

Aim: to push on beyond the lake chamber at the end of Sump 7. Both divers reached the end of sump 7 in zero visibility. Sump 8 was easily found and passed by MCM after 5 m to a long low evil airbell with a small beach. "Oh God, this is not getting any better", thought the diver. The way on was obvious, through a forest of roof pendants - Sump 9. RKW's turn so this was easily passed after 10 m. Frenzied tugging on the line indicated that he had either expired or found mega stuff, so MCM dived to join him and together they skipped excitedly down a large cascading Swildons-type canyon passage. Sixteen years of digging into the cave by numerous members of the BEC had paid off handsomely. The divers trundled down some 100 m of superb cascading passage, about 2 m wide and 5 m high, reaching up to 10 m in places, to a 2 m waterfall into a boulder chamber. A minute of rock flinging found a way down a rift to the head of a pitch estimated at 7-8 m deep with the way on visible and wide open. Due to lack of tackle and mindful of doing something silly beyond nine tightish sumps, the divers reluctantly had to retreat. Two steeply ascending muddy inlets were noted downstream right. On the return through the sumps the visibility improved to about 1 m in places for the lead diver so some depths could be gauged. MCM's lights gave out in Sump 3 so Sumps 2 and 1 were dived black. Both divers used 1 x 7 litre and 1 x 4 litre tanks each, with no fins. Due to bad visibility no lines have been belayed except in Sump 1.
CDG NL 107:39

21 February 1993    Divers: M C McDonald, P Bolt

The carry in was an epic for MCM as one of the sherpas freaked out in a squeeze near the entrance leaving MCM to carry a ridiculous amount of gear the rest of the way, arriving at base in a crumpled heap purple with rage. Both divers cruised to the last limit at the top of the pitch. The pitch resembled (was) a vertical Sump, 8 m deep with a ledge at 4 m. The passage continued for 30 m to a large boulder choke, hanging with megadeath. Half an hour of tip-toeing around the choke revealed a small hole partly blocked with a boulder. A way on could be seen through the hole into a larger cavity in the choke. This will need a bang. Water levels lower than usual. Upon exit, the divers found MCM's car had been stolen by the freaked-out sherpa - it was a long, cold slog back to The Belfry after an eventful day.
CDG NL 107:39 (1993)

4 April 1993    Divers: M C McDonald, A Gee

Aim: rather ambitiously to place dye in Attborough Swallet, to radio-locate four parts of the downstream section, place dye detectors in upstream Wigmore, survey the downstream section and to shift the problem boulder at the downstream limit. Remind me never to carry the ammo can containing the MRO Grunterphone in a cave ever again. An awkward carry of gear down the cave and through the wet bits. AG did well on his first trip down there and kept his head together admirably. Unfortunately, AG disappointingly had 50% water with his air upstream of Sump 7 and stopped for repairs, so as time was getting on for the first transmission, MCM charged through Sumps 7, 8 and 9 to begin transmission in Wigmore 10, 30 m downstream of Sump 9 under an aven, at the appointed hour. After a long while a weak voice was heard. After an even longer while, those scurrying about on the surface reckoned they got a fix to within 50 m of the exact spot - good enough for me. The cave is heading where the diving compasses say it is, almost due east and away from its known resurgence at Cheddar. Willie Stanton's theories on its route are thus probably correct. Unfortunately, as it took so long for topside to locate us, MCM had to abandon the other radio-location points, but at least one good fix was made. In any event, there were very few other dry, flat places to lay the aerial out on. We also had to abandon the boulder shifting work at the end as MCM was on his own at this point, time was getting on and AG was freezing back at 7 - next time no doubt. At least we got the radiolocation and dye chores done. MCM had fun getting back through Sump 5 with a hand-held tank in one hand and radio gear and line in the other. One dye detector was picked up by AG back at base and delivered to UBSS for analysis, the other two will be brought out in the next few days. Zero visibility once again due recent rain, although water levels generally were a bit lower and some sumps a few feet shorter.
CDG NL 108:25 (1993)

On the 24 April 1993, M C McDonald, D N Hastilow and A Gee

sought to remove the offending terminal boulder, but equipment problems en-route forced a retreat. The results of the previous trips dye test had been analysed by this time and the trace from Attborough Swallet was proved positive to upstream Wigmore, flow through time between 10 and 52 hours. The flow in the cave, however, is substantially more than Attborough can account for. Thus, on 4 June 1993, M C McDonald inserted 0.5 kg of fluorescein into Tor Hole and this proved negative to the Wigmore main drain. It is conjectured therefore that the Wigmore water is derived from seepage and Attborough Swallet only.

23 May 1993    Divers: M C McDonald, D N Hastilow, (would-be diver: A Gee)

Aim: an easy, gentle, trouble-free cruise to get rid of offending boulder in the terminal choke and hopefully skip on. Reality: chaos, this place really is jinxed. AG decided Sundays were not for diving and retired at dive base. MCM and DNH set off, only for MCM to have a high pressure explosion in Sump 4. Determined to get the show on the road, he went back to dive base to get AG's 7L tank and valve, but was unable to get a good seal (bloody DIN fits). He thus had to return to an (im)patient DNH waiting in Wigmore 5, MCM wearing his own two mounted 4 l tanks, hand-holding a third 4 l tank, with pillar valve, to stage in Wigmore 4 so as to have enough juice on the return through Sumps 4 to 1. Terminal choke eventually reached with DNH most impressed with the scenery. Boulder obliterated [ ... ]. After a hour's wait for the fumes to clear, MCM fought his way back through the smog, gardened a bit and squeezed through some dubious boulders to reach the streamway again. DNH followed and the pair worked their way up through some horrible boulders into a chamber 5 m long, 4 m wide and 4 m high to descend once again to the stream. On for a short distance and straight into another humungous boulder choke with the stream disappearing down a body-sized tube in the floor and under the choke. Both divers in turn inserted themselves for half a body length and both agreed the letter box at the end with the whole flow going through it needed an anorexic whippet with gills, or even John Cordingley. Half an hour clambering all over the choke revealed no way on. A very long term dig [ ...] is required. Mud and cowsh debris 12 ft up the wall indicates the place backs up horribly from the terminal aquatic tube. We shall not be going back there. A feature of the event was the myriad of flies and bugs which had been washed in and then hatched, getting into noses, choking throats, ears and other orifices. On the return, visibility for the lead diver was unusually excellent, no doubt because the cows are out of the farmyard and into the fields for the summer - the pair carrying a ridiculous amount of gear as the two ladders on Slime Rift had to be brought out and MCM had to pick up the stage tank in 4. Two very knackered, disappointed cavers exited after 9.5 hours - 16 years of exploration by the BEC at an end.
CDG NL 108:26 (1993)

Due to the constriction at the terminal boulder choke, the water backs up the passage for some 30 m as far as the boulder choke 30 m downstream of Slime Pitch. Flood debris was noted 4 m up the walls in this area and both boulder chokes are very muddy. The terminal area is thus probably only accessible during dry periods.

7 June 1999    Divers: J P Volanthen, M Taylor

Dive to Wigmore 6 to asses the difficulty of passing Sump 5 with equipment. Both divers passed Sumps 1-4 without difficulty. JV passed Sump 5 and continued to Sump 6. All sumps passed were adequately lined.
CDG NL 133:14 (1999)

Part Two

Created: Sat Mar 12 11:14:09 2011