Aim: To explore the short canal parallel to the main streamway for diving possibilities.
Access to the canal is gained via a roof bedding and short drop into an interesting full immersion duck. The passage becomes too narrow above water level (see Northern Caves Vol. 1, p.65), but a continuation was located below water level which revealed 25ft. of small sump passage to a junction with a cross joint to the left. Straight on was found to be low and to end in silt and boulders, but along the cross joint 10 ft. of easier going leads to a small airbell. Three ways on from the airbell were investigated but snagging of the base fed line forced a retreat.
Aim: to examine the cross joint continuation from the airbell found on 25.4.76.
From the airbell the leftmost upstream continuation was followed along the line of the cross joint and was found to be a narrow but not uncomfortable tube. Airspace was reached after 15 ft. at a large airbell with two impassably small inlets above water level each discharging a trickle of water. Diving on from here an easy 40 ft. sump was passed to an airbell with the sound of the stream coming from a low airspace continuation best negotiated below the water surface. From the tie off point a short section of canal was found to lead to a section of fast flowing streamwy which unfortunately degenerated almost immediately into a tight sideways crawl and further constricted sump.
Aim: To continue the exploration upstream.
The final upstream sump was reached without incident, although kitting up in the flat out crawl just before the sump is somewhat awkward. Entering the sump a tight descending tube led almost immediately to a boulder of small dimensions. 40 ft. of rather desperate going was found to lead to a second boulder blockage which yielded after some strategic positioning of the obstructions. After ten more feet of anxious progress yet another gardening session finally enabled the diver to reach airspace. The relief was short lived, however, as the under water passage was found to close down almost completely and the only way into the continuation of the rift type airbell was via a tight sideways squeeze above water level. At that point the diver decided he'd had enough trauma for one day and returned to base in zero visability. Sump 4 is about 60 ft. long. Total length of passage - beyond Birks Wood 1 is about 280 ft., including sumps.
Aim: To survey the extension as far as sump 4 and to push on into sump 5.
The survey was completed up to the streamway between sumps 3 and 4 when a sudden rise in the water level due to a flood pulse of muddy water, presumably caused by the rain of the previous evening, necessitated a quick retreat.
The sump lengths were measured as : Sump 1 - 11.0m (36.1ft.), Sump 2 - 4.5m (14.8ft.), Sump 3 - 15.7m (51.5ft.) with airbell after 11.0m (36.1ft.).
The unfortunate change in water conditions ruled out an attempt on Sump 5. Plan opposite page 14.
Previous exploration: See NL 40.13 (with plan), NL 41.9 (with plan).
Aim: To push on beyond the 30 ft. aven.
Apart from one or two minor problems with the lines, the sumps were passed without undue difficulty. Sump 6 was rigged with a heavy free diving line from a bolt placed by JTG in the downstream rift. When free dived from the correct point at the bolt the sump is 5 feet long and although low it is quite easy. At the top of the aven, which turned out to be 35 feet, 100 feet of walking passage was found to lead to 300 feet of hands and knees crawling in a rather chilly canal ending at yet another sump. This cave never seems to give up!!
Aim: To try and free dive Sump 7 found on 28th August.
The water leyels were back to normal after a week's heavy rain and although the first four sumps had not changed appreciably the explorers were surprised to find an extra sump and a duck before sump 6 could be reached. The first of these obstacles, a 20 foot section with low airspace, was rigged with 30 feet of guide line and the second, a complete sump between parallel rifts 2 feet apart, was found to be easily free dived without a guide line. Sump 6, a complete sump this time, was negotiated without undue difficulty. The whole of the cave between sumps 4A and 6 shows evidence of serious flooding under high water conditions. At the top of the 35 foot pitch half an hour's excavation lowered the level of the canal by about a foot and as a result sump 7 was found to be almost exactly as it had been under the drought conditions of the previous trip. RJS then donned hood and mask and took the plunge emerging from a free dive of 20ft. in a low sump pool with boulders to the right and the roar of the stream cascading down through them. JTG placed a bolt at the downstream end of the sump from which a guide line was rigged to a convenient boulder at the other side. A scramble up through the boulders enabled access to be gained to a large aven with the stream cascading down from an opening 25 feet up. Free climbing was soon found to be impossible and so a retreat was beaten back to sump 7. 1450 feet of passage was then surveyed from there to within 500 feet of sump 6. The total length of the extension is now of the order of half a mile with good prospects for more to come.
Aim: To survey the cave as far as sump 4A to BCRA grade 5.
The survey was completed without too much difficulty although the bypass passage proved to be awkward. The small inlet between sumps 2 and 3 was dug out but became too tight after only 10 feet of progress. The entrance to the cave is now a permanent 5 foot long sump since the demise of a large tree which used to lead a rather precarious existance at the top of a little cliff face outside the cave. The effect of this is to raise the water level in the main passage thus permanently sumping the short duck into the parallel canal before sump 1.
Previous exploration: NL.38:18.
R.J.S. dived and entered the rift to the right noted by C.R. Edmunds on the 11th October, 1975. A low thrutch necessitated the moling away of some shingle beneath a flake but after that the sump presented no further serious obstacles and was soon passed, after a total length of 40 ft. and maximum depth of -8 ft. Returning for J.T.G. the two then dived back through the sump and explored 100 ft of narrow rift to a pitch which looked to be about 30 ft deep.
Eager to descend the new pitch, the explorers optimistically returned with enough ladder to get down that and several more. The drop in fact turned out to be 30 ft. and J.T.G. descended through the roof of a large passage with both upstream and downstream continuations, the upstream ending after 50 ft. at a large aven down which poured the majority of the water. Downstream, 1000 ft. of mostly walkng-sized clean washed stream passage was explored, passing what must be the finest display of helictites yet discovered in this country. For about 100 ft. the upper ten feet of the walls of the 15 ft. high passage are covered with helictites up to a foot long in places and reaching an amazing profusion. Finally a ten foot climb was descended to a pitch which was rigged with our spare ladders. This turned out to be a somewhat windswept 40 ft. climb landing in the final chamber of Birks Wood Cave found on 18th September, 1976 (NL.42:10).
Aim: to photograph and fully explore the system and to recover the ladder left in Birks Wood Cave on 28.8.76.
Before descending the cave a quantity of dye was introduced into the stream flowing into Smegmire pot (see Cambridge Underground, 1976). This was next seen coming down the large aven which constitutes the main inlet to the system upstream of the 30 ft. "Red Aven" down which the Redmire Pot water enters. Unfortunately the trip had to be abandoned after only five hours underground, due to partial flooding of the system, as a result of an unforecasted downpour. The party only narrowly escaped being trapped.
The whole system is 385 ft. deep and one mile in length, and if a surface entrance for non-divers is forthcoming via Smegmire Pot it will rank amongst the most challenging caves in the country. It must be pointed out however that the sump in Redmire is most certainly not a free dive and neither are any of the sumps in Birks Wood Cave.
Aim: to survey old Redmire Pot.
R.J.S. and N.R. rigged the cave as far as the 40 ft. pitch down into the passage previously explored from Birks Wood Cave (see NL.38:18 and 45:16). N.R. traversed over the 40 ft. pitch but was unable to reach the large chamber on the opposite side of the aven. This will have to be reached by climbing from below or via a bolt traverse. On the way out the cave was surveyed from the second pitch to the surface.
Aim: to link the survey up with the passages surveyed in Birks Wood Cave on 18.9.76 (NL.42:10).
1,200 ft. of passage was surveyed from "Red Aven" down to the 20 ft. free dive of Sump 7 of Birks Wood Cave and from there to link with the survey of Vizier's Vent, the 300 ft. canal. On the way out N.R. had some difficulty with his equipment in Sump 1 and valves had to be swapped, R.J.S. making the best of a bad job. Apart from this awkward moment the derigging was uneventful.
Aim: to complete the survey. About 900 ft. of passage surveyed down to upstream end of Sump 4A. Line in Sump 4A had come adrift and was refixed more securely.
Previous exploration: NLs. 38:18, 45:16-17, 49:24.
Aim: to an inlet between the second and third pitches leading towards Birks Fell Cave. This inlet was partially explored by A. Nichols and N. Reckert on 23.6.77 (NL 45:17). They reached a lowering of air space after 30 m.
R.J.S. and J.T.G. both passed Sump 1 and a single mini-bottle was carried down to the inlet. J.T.G. led the way and found that the "lowering of airspace" was not a sump but just a low duck leading to 46 m of flat out canal passage and a climb up over poised boulders to a dry aven. The aven could not be free-climbed, as its walls were smooth and slippery. Both explorers gained the opinion that this is an overflow route for water from Smegmire Pot and has nothing to do with Birks Fell Cave.