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History - 9


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part 9

The exploration of Blackmoor Valley, and
history of Upper Flood Swallet 1954-2008 (part 9)

2006-2008 - Blackmoor Shaft (Stainsby's Shaft)

MCG first dug at Blackmoor Shaft (see panel 1) from 1960, to 1968 when our attention turned to Upper Flood Swallet. Over the decades several unsuccessful attempts were made to restart the dig (notably by Malcolm Cotter, Bill Headington and Kev West).

In 1984, Willie Stanton and A G Clake published a paper in UBSS Proceedings ("Cornish Miners at Charterhouse-on-Mendip"). By carefully researching references to Charterhouse in the Mining Journal during the period 1844-60 they were able to demonstrate that Blackmoor Shaft was a 19th century lead-mining shaft called Stainsby's Shaft. Even so, there seemed to be little incentive in MCG excavating the 108m deep shaft as it was so far distant from Upper Flood Swallet.

In 2006, the situation changed dramatically. The breakthrough at the Departure Lounge added some 2km to Upper Flood Swallet, and when the survey was drawn up it was soon appreciated that Stainsby's Shaft was more significant than we had realised.

To reach the new extensions in Upper Flood Swallet, a series of squeezes beginning at Andrews Grotto and ending at the Departure Lounge must be negotiated. "There are thirteen squeezes between Andrew's Grotto and the Departure Lounge. I prefer to call them The Thirteen Bastards as I struggle with each one. ....... It is the choke that makes this the most sporting trip on the Mendip Hills and I am just glad that I still fit if only just" (Richard Carey, 2008). There is no possibility of enlarging all 13 squeezes so access to the cave is restricted to thin cavers.

Phillipa Glanvill in  one of the 13 squeezes. Photo J Hesketh
Phillipa Glanvill in one of the 13 squeezes. Photo J Hesketh

Stainsby's Shaft was 38 fathoms (108m deep) when mining ended. Levels had been driven at 18 and 38 fathoms for up to 220m and a "large cavern" was encountered 55m from the shaft. The exact direction of the levels is not known - only in one section was the direction clearly recorded ("about 35 deg south of east"). However, it is possible that the 38 fathom level reached a point close to Walk The Plank in Upper Flood Swallet. There is no evidence that miners entered the far reaches of the cave, but it does create the possibility of finding a back door into the system, avoiding the 13 Squeezes.

Charterhouse mines
The Charterhouse mines. From UBSS Procs vol 17 no 1, 1984

In late 2007 the shaft was found to be open as far as the "10ft pitch" (shown on the 1968 survey) where there was a puddle containing small mammal bones and some old digging tools. In November a new fixed ladder was installed in the shaft and work recommenced. A cubic metre of spoil was removed from the head of the pitch and a mortared wall was built. Access was improved with the use of scaffolding and metal grids, and the BDCC winch from Carcass Cave was installed.

Installing the fixed ladder. Photo Biff Frith
Installing the fixed ladder. Photo Biff Frith
Installing the fixed ladder. Photos Biff Frith
Blackmoor Shaft showing the 10ft pitch. Survey T Knibbs
Extract from the 1968 survey of Blackmoor Shaft showing the 10ft pitch. Survey T Knibbs

Widening and deepening of the rift took place in December. The floor was lowered as far as the winch platform and a 1.5m x 1m high wall was built to stabilise the slope. Calcited clay mineral and rock was removed with a compressor and air chisel to make room for the winch and pulley.

The winch was finally in place by March 2008 but the bearings had rusted and needed replacing. A large pulley was installed in the roof directly above the shaft and more shaft walling was built. Lower down, the narrow rift formed by the wall and a large boulder was widened (both sides) with chiselling and Hiltis. Finally the old spoil and some new material were removed from the very bottom of the shaft. Some significant stabilisation and safety work was needed here as the old wooden shoring which holds back a lot of small fill was rotten.

Over the weekend of 05-06/04/08 we lifted over seventy drums of spoil and many netted rocks, used over fifty Hilties and installed more much-needed scaffolding.

We were now digging new ground, straight down from the "10ft pitch" in an attempt to follow the main shaft which was only metres away. Signs of mining could be seen, such as a shaped socket in the solid wall, used for the ladder staging.

In April an obstruction in the ladder pitch was chemically persuaded to remove itself, as were many boulders below. The scaffolding was almost finished and a safe cage for digging was put in place. Many buckets of spoil were then removed. The spoil appeared to be buddle washings and they were easy to dig, the drums being filled faster than the winch team could keep up with! Over one weekend we deepened the shaft by 2.7m

The dig was now making rapid progress: 3m gained on 04/05/08 and 3 cubic metres of slimes (that's over 3 tonnes in weight) removed on 10/05/08 to reveal a passage going for 4m towards the main shaft and a descending slot going for 2m.

Biff even had a go head-first with Mark Ward holding on to his feet so he could drag a large rock out (a case of dope on a rope?). This revealed a widening void, going down at 45 degrees. Progressing down and out of the slimes, the dig was now producing stones and rocks.

A large turnout at the end of May gained another 2.5m to what may be the main shaft. Unfortunately this was filled with rocks, but there was another void going left. Hiltiing another boulder regained the main rift wall and another 5.5m downwards, back along the rift to almost under the digging shaft, almost completing a full circle. After some discussion it was decided it would be safer and easier to continue going down the digging shaft. Within a metre the rift wall started undercutting and a void could be seen. The digging shaft was now nearly 12m deep and close to the 18 fathom level in big blocks of limestone.

More scaffolding was needed in June before another 1m of digging regained the rift. Biff enlarged this to about head size and he could see down another 5m. Rocks dropped down from here go a bit further.

In June we continued to make good steady progress down the shaft, gaining another 2m in one weekend.

August was spent replacing electron ladders with more fixed ladders, and with more scaffolding.

At the end of August we removed 80 drums of spoil and a large rocks in a single day, but this was bettered a week later when we removed 101 drums one day and 100 the next, as well as casting a concrete lintel in place.

At a depth of about 30m we broke through to a small chamber containing a stream, with stemples still in place on the floor, and a stemple slot cut into the wall. The stemple slot was made by the miners by hand drilling three holes close together in a horizontal line and then the rock above was chiselled out.

The good news is that its all clean washed and we can see down another 4m, the bad news is that it is horribly loose.

Installing the fixed ladder Photo B Frith
The winch in action. Photo R Porter
Wall socket, probably for a ladder or stemple. Photo B Frith
Installing the fixed ladder Photo B Frith
The winch in action. Photo R Porter
Wall socket, probably for a ladder or stemple. Photo B Frith
Scaffolding and wire grid. Photo R Porter
Looking down the shaft. Photo R Porter
Rotten timbers in the shaft at -30m. Photo B Chadwick
Scaffolding and wire grid. Photo R Porter
Looking down the shaft. Photo R Porter
Rotten timbers in the shaft at -30m. Photo B Chadwick

Work continues

Will we ever connect Stainsby's Shaft to Upper Flood Swallet? 54 years ago we commenced our endeavours in the Blackmoor valley with digs at Blackmoor Swallet and Blackmoor Shaft. For 40 years we neglected Blackmoor Shaft in favour of Upper Flood. Now we are digging at Blackmoor Shaft again.

If we can make the connection so that we can enter the system via Upper Flood Swallet and exit via Stainsby's Shaft, we may be able to say:

  • We did not cease from exploration
  • And the end of all our exploring
  • Was to arrive where we started
  • And know the place for the first time


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Page created 06 October 2009, last updated 14 February 2010

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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.