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Towards Wookey Hole

By D.J. Irwin.

The long discussions on ‘what happens’ beyond the Cuthbert’s Sump that take place at the Belfry from time to time has stimulated the author to set down some of his ideas where best to dig.  The aim of this article will first to discuss digs that will, we hope, eventually extend the cave beyond its present boundary in the hope of regaining the main stream way and secondly to discuss other possibilities within the cave system.

All the recent discoveries have been within the present boundary and up to the present only two sites show real promise of entering fresh lands; though, not forgetting ‘sods law’ that makes the final breakthrough in the most unlikely place. The two sites are the Sump and the dining room Dig.  Although these two sites have been mentioned specifically there are several other very good sites that I believe will eventually lead away from the present cave boundary.  Time is precious and the sites can only be worked at the pace governed by the available labour.  The main trouble is that there are not enough digging teams to attack all the sites, that number over 100, simultaneously.  All of these sites have been looked at recently.

1.         TERMINAL SUMP

This is the obvious point to attack and, as it is being worked at the present time there is little to say except when the sump is passed and an extension found it is unlikely to be free divable; a bypass will have to be found. Surely it is better to commence looking for a way round the sump now rather than let the divers have all the fun.

2.         DINING ROOM DIG.

Although some 400ft. to the north west and about 50ft. higher than the sump it starts at the fault line and is following roughly the same direction as the sump passage (mean bearing 2160 Grid N.).

The first section of the excavated passage is distinctly phreatic with no noticeable signs of vadose action.  Beyond the ‘Arch’ the passage rises steeply (about 6-8ft. above the entrance to the dig) and levels out into a choked passage with about 6” of airspace. The section of the passage now being dug is about 18” high and some 10-12” wide.  This rather confined space is because the diggers have not removed sufficient infilling.  The next move is to open up the excavated passage to make things easier for speedy digging.

The digging area soon becomes ‘steamed’ up making conditions very uncomfortable but it is hoped to reopen the choked passage that connects D.R. Dig with Mud Ball Dig that was opened up by Bennett and others in 1966.  The connection is too small to cave through but it will allow air to circulate through the first section of the D.R. Dig.

A close examination at the start of the dig will show some small roof pendants pointing into the dig and just beyond’ faint markings can be seen on the right hand wall which ‘looks’ as if the water flowed into the dig – perhaps some expert would like to make an inspection of this section of passage and voice his opinion for our guidance.  For all we know it might be an inlet.

3.         END OF GOUR RIFT

The end of Gour Rift, just beyond the Duck, has been of interest to the writer for some time.  The rift closes down rather abruptly and is not rounded; a well developed pothole in the breccia above the end of the rift comes from a small and heavily stal’ed inlet passage – the Bank grill.  If the water had always flowed into the Sump Passage, as it does today, the end of the Gour Rift must have been rounded - which indicates to me at least – that the water has swept under the end of the rift and the terminal wall that we see today is merely the roof of the now choked passage.

There are two further points that lead one to suspect that water went under the end wall.  These are: - a) deposits of charcoal found down to a depth of 5ft. and b) the stream way is heavily goured and stalagmited from Stal. Pitch to the ‘Duck’.  At the ‘Duck’ the gouring ends abruptly as though the passage floor dropped away rapidly; this is now badly choked.  As the Sump Dig has only dropped four feet it is possible that the end of the rift is open enough to get a caver through with only a little digging.  Just prior to the Sump digging weekend in 1967 Barry Lane and the writer closely inspected the sump passage for charcoal deposits.  For over an hour we dug and searched but no charcoal could be found.  If none is found by any one else it would be fair to assume that the Sump Passage is a recent recapture and that the cave is choking itself again.

The initial part of the Sump Passage is heavily stal’ed immediately beyond the ‘Duck’ and appears as a whole to be rather immature.  Beyond the ‘Duck’ the passage opens into a round section as a result of the fairly large inlet in the roof and then forms into a rift with well exposed chert bands to finally degenerate into a wide bedding plane at the sump.

One of the troubles of the lower section of the Cuthbert’s streamway is that the rock floor is never seen after the Everest – Main Stream Junction and so one will never know the true depth of choking at the duck or sump, but it appears to some that the Sump Passage is merely the top of a very large passage – this is only a feeling and so should not be taken too seriously.

To be continued.