The exploration of Blackmoor Valley, and
Summary of digging trips by period
Phase 1: 5½ years to March 1974 including exploration of the cave to the second chamber. For 20 months during 1971-73 there were two caving groups working in the cave: the MCG, and Dr Stanton's group from the Wessex Cave Club. Much of Dr Stanton's efforts were devoted to easing access in the upper cave, with the enlargement of tight and glutinous sections. In the Wessex Journal for October 1976 he concludes that the Wessex team made 191 trips during the 20 month period, with the number of diggers varying from one to seven.
Phase 2: 5½ years from March 1974 to September 1979, when MCG activities were slowed due to our cottage-building efforts.
Phase 3: from Jan 1980 to April 1985 when the attraction of a new cottage on Mendip meant that a dig at Upper Flood Swallet was sometimes even the object of enthusiasm!
The statistics are incomplete since not all working trips were recorded in the MCG log books. No fewer than one-third of the MCG membership had been active in Upper Flood at any one period, with nearly half the members during 1968-85 having participated in digging in the cave - making it truly a club dig rather than the exclusive province for a few. Combining the MCG trips with those of WCC gives an approximation of the effort involved. At least 463 trips (nearer 500 allowing for unrecorded events), and 1412 (nearer 1500) person trips, with an average of three people on each digging venture.
The initial cave was about 77m long. A further 123m was discovered by early 1974, of which up to 35 metres was "constructed from nothing.... in spite of the exceptional level of energy and enthusiasm the mean advance per trip was about 40cm". Progress was a painfully-slow series of trips attending to the result of the previous bang, inching forward, followed very occasionally by a notable breakthrough.
1974 to 1985 proved no different. Excavation amounted to 16.5m before the breakthrough into Midnight Chamber. The work involved a minimum of 118 recorded trips, perhaps nearer 150 including those un-recorded, giving an average progress of 11-14cm each working trip at a digging face of about 0.7m x 1m
Midnight Passage/Sunset Boulevard ended at an impenetrable sump, but just prior to this an awkward climb up appeared to be the beginning of a potential bypass, so it was decided to excavate onwards in the hope of avoiding the sump and dropping back into the stream. Several skips were brought down and a continuous loop used to pull the containers back and forth along the crawl. New diggers joined, among them being John Beauchamp, Alan Dougherty, Andy Scully (the sculptor) and Yvonne Ward (Rowe).
By November 1985 when the dig had progressed 4m, Malcolm Cotter made an attack on the roof of the passage. Progress with hammer and chisel was initially slow. Then, quite suddenly, a boom developed and a few blows later a hole appeared, to reveal a very low passage starting at a height of some 6cms but getting a little higher further on. An obstruction could be made out at the limit of vision some 6m ahead.
We had by August 1986 advanced a further 3.5m beyond the window and effective work required three people to get spoil back into the chamber where it was disposed of behind a wall of "deads". On Wednesday 13/08/86, Gary Pairaudeau and Alan Dougherty brought down some large slabs of calcite, leaving a small hole in the false floor which formed the dig roof. They enlarged the hole until they were able to see the boulder, which had been visible from the first hole in the roof for some months, only 3m away.
Grant Sheppard in Hannah's Grotto, photo by G Beale
Another day was spent removing a layer of stalagmite floor for 2m beyond the second window. The rock obstruction seen earlier was pushed away and a 4m crawl lead to a slope giving a view into a large passageway, Hannah's Grotto, a t-shaped passage some 5m high ending at a vertical 'cliff' after only 20m.
Upper Flood was back to revealing its secrets in small packages! It had taken 1½ years to dig 9m and gain only 25m.
The 'cliff' was climbed on the day of exploration and but no continuation was found. At the end of the passage and below the cliff was a hole formed by collapse. Extensive areas of mud-cracked floor were taped off, since owing to the lack of water we thought they were an ancient feature. This conclusion we later found to be wrong. The best examples of mud cracks occurred above the hole referred to above and they remain intact.
The day following the discovery of the new passage the hole became the site of intensive digging. Work was easy at first as it involved the removal of clean loosely packed rock, and the presence of a weak inward air current indicated that this was the way to go. By the end of the first session at the new dig we could see into a small cavity with a mud-cracked floor.
The approach to the Lavatory Trap, photo G Barton
An assault on the new dig began in May 1987. Being in solid rock, blasting was the only way to progress. Working conditions were difficult, lying flat out in cold water, removing spoil in restricted conditions. It took three sessions to clear the approach to the sump. An investigation was then made using drain rods as a probe. It was possible to thrust forward 8m. This section was later called the Lavatory Trap.
The small hole leading downwards was blocked by our working. As the hole developed we passed a thick stalagmite floor with a small void above. This was the first indication that the way was to become horizontal again. About 30 cm lower we reached the underside of the stal. On further clearing under the lip a void was reached which immediately emitted a strong outward air current. Work was pursued in an atmosphere of excitement. Lowering the floor resulted in increasing difficulty since water entering from ahead mixed with the mud which became increasingly sloppy. Eventually we were moving more water than mud.
At this stage several members tried pushing through in feet-first mode. Unfortunately the roof lowered, restricting progress. A head-first entry was needed - a nerve-testing operation since it required pushing into a sloppy mud duck with only one eye, an ear, and the nose exposed. Progress was stopped by a mass of gritty clay but it was possible to see that we were at a t-junction. The sound of trickling water was very distinct but its direction could not be discerned. Extrication from the duck was assisted by those behind.
The Lavatory Trap and Sludge Duck, sketch by M Cotter
The following week a large party successfully bailed the sump, lowering the level by several centi-metres. Vince Simmonds went in feet-first and kicked a channel through the sediments into the higher region. Vince went some 8m towards the sound of water but because there was no back-up he did not press on. At this stage of exploration the conditions were very unpleasant, the whole new passage being a flat-out crawl in ooze.
On 11/07/87 Andy Beare, John Beauchamp, Alan Dougherty, Mike Hasleden, Neil Hutchinson, John Mirriam, Vince Simmonds, Andrew and Malcolm Cotter attempted to repeat the successful bailing operation but the groove made on the previous entry acted as a channel for water to flood the workings. There was no option but to brave the sludge duck by taking advantage of a small groove in the roof, requiring almost complete submersion in black ooze of tailings slime. This part of the cave was called Sludge Duck Junction.
4m beyond Sludge Duck it was possible to crouch at a t-junction. The left (downstream) passage gradually lowered to a flat-out crawl over mud. Only 3m beyond it was necessary to dig out more tailings to progress. The way on continued low with the sound of running water and a strong outward air current.
While the downstream push was proceeding Neil Hutchinson made his way upstream and called back to 'come and have a look'. The way from the junction commenced with a very tight squeeze followed by a duck in ooze which improved to a wallow. Gradually the passage got higher improving to standing height. The way ahead was clear for 30m to an upward sloping, mud floored chamber ending at an aven. Some 4m up, more passage was found parallel to the lower passage. The aven continued upwards but was too tight to follow.
Since the upstream passage was developed along a fault in the Lower Limestone Shale it was called Shale Rift.
A serious attempt to pass the downstream obstruction from Sludge Duck Junction was made by Martin Rowe in July. He struggled to pass the downstream squeeze but safety demanded enlargement. On 02/08/87 bang was put into a shale parting above the constriction and the obstruction was passed.
Ahead, a pool of water was held back by a bank of rounded pebbles and mud, and a garden hoe proved its worth in clearing the mud. The 'pool' proved much less in extent than first reported and on return the name Puddle Lake was suggested by Pete Goddard. Ahead, the explorers entered a wide chamber formed by collapse in a fault and the stream dropped rapidly to the right. A squeeze was passed by Andrew Cotter which gave access to a small well-decorated grotto at one end of which was a hole between boulders which emitted a good air current. There were no other open possibilities. The chamber before the boulder choke contains a very fine red stained stalagmite flow and several names were tried, The Red Room being the one which seems to have survived.
Andrew's Grotto and boulder choke digs, sketch by M Cotter
Digging in late 1987 and 88 was concentrated at the lowest part of the Red Room. In 1989 digging moved to the lower end of the Red Room then to Flake Dig just beyond the original dig. Andrews Grotto was opened from below. The way on could be seen about 2m ahead but the diggers were greatly discouraged. They returned to Andrews Grotto to dig a double choke - an old one of large cemented boulders, and a newer one in the boulders which could be followed for 8m. At the end the sound of water could be heard. In the upper part of the choke above Andrew's Grotto a wall was also followed. But by the 199's all possibilities seemed to be exhausted.
|Click to continue to next page|
or jump to:
|Back to top||
Page created 06 October 2009, last updated 14 February 2010
Mendip Caving Group. UK Charity Number 270088. The object of the Group is, for the benefit of the public, the furtherance of all aspects of the exploration, scientific study and conservation of caves and related features. Membership shall be open to anyone over the age of 18 years with an interest in the objects of the Group.