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Upper Flood Swallet

Upper Flood is a conservationist’s headache.  Now read on ...

Originally known as Blackmoor Flood Swallet this cave was one of the bonuses of the 1968 flood that washed away the Forty and the road at Velvet Bottom.  The heavily choked passage was originally explored by the MCG and subsequently dug by both Willie Stanton and that club whose headquarters lie conveniently within walking distance.  Although the cave promised much, lying at the head of the Velvet Bottom catchment area near the limestone/shale boundary with a potential 700 feet of vertical range, it became clear that siege tactics were required. The once roomy ancient stream passage was choked with fill, stal obstructions and lead tailings.  It has taken nearly 17 years of digging, blasting, wall construction and back filling to gain access to the present cave.  It has paid off for the MCG who now have in their grasp potentially one of the deepest caves on Mendip, if not the country, and despite the length of the known cave the depth potential still remains.

The entrance lies on land controlled by the county council which is why access arrangements are fairly tight.  Parties of four including a MCG leader are allowed down but due to the nature of the cave overcrowding and damage to formations can be a risk if more than one or two groups are down the cave.  My interest in the cave was photographic and it must be said that it lends itself to photography magnificently.

A concrete barrel shaft drops two metres into a small chamber from which a flight of steps leads to a rift passage.  A further short drop intercepts a small stream.  Upstream can be followed for a short distance while downstream continues as a stooping or crawling size passage on a very shallow gradient.  At various points evidence of the Intensive excavations can be seen In the form of walls.  Malcolm Cotter tells me that in places the passage has been back filled to a depth of 1.5 metres or more.  Eventually after 275 metres or so the roof lowers to a muddy grovel partially full of water.  However, the enthusiasm of the explorer is more than stimulated by the draught of cold air and the sound of running water.  A wriggle up a mud covered stal slope and a squeeze through stal curtains leads to one of the most dramatic entrances on Mendip.

One stands (carefully avoiding the numerous straws above ones head) on a big stal slope in a roomy well decorated chamber.  On one's right a large stream gurgles out of the wall, crosses the chamber~ and splashes off at bottom left into the enticing darkness. This is Midnight Chamber, the breakthrough point. 

Upstream the passage is a low crawl to a sump whilst downstream the cave continues as a crawl. Here the damage to stal formations is most evident and I suspect that although this is by far the most vulnerable part of the cave that much of the destruction was caused by the excited first explorers.  This is hardly surprising because the passage consists of a crawl about 1.5 metres high and 1 metre wide along the walls of which are arranged a mass of stals on a false floor whilst the roof is studded with a forest of stalactites.  Delicate crawling in the stream leads to a boulder obstruction through which one gingerly worms into the next section.

Here the streamway widens a little but the roof remains low.  Some attractive stal bosses can be seen on ledges on the left and there is enough exposed limestone to observe the nature of the rock.  It is extremely shaly and it seems to me that the best formations can be seen in the shaly sections.  Stal formations and shale seem to go together – does anybody know why? Anyone also cannot fail to notice the black marks on many of the stalagmites.  Closer examination shows the marks to have legs and that they are the remains of dead flies.  Presumably flies hatch from eggs carried in by the stream on rotting vegetation and then die from lack of food.  Incidentally there is little evidence of flood damage to the formations which suggest the streamway can cope with large volumes of water of that the ingress of water is limited.  Now that there is an excavated entrance to the cave a repeat of the 1968 floods could destroy the decorations and the MCG have already thought in terms of constructing some kind of flood gate to the entrance.  The streamway turns a corner passing a massive stal bank on which are arranged numerous numbers of totem pole stalagmites, some at angles suggesting breakage and re-cementing.  The straws in this section are some of the best on Mendip.  Just before the stream dives into a bedding crawl one can see clumps of stal on the floor.  If one looks closely one can see straws that have been formed, broken off, and have been re-cemented before the floor they were on was broken off, and washed into the stream.  I must say that this suggests to me that the cave is pretty ancient!

Beyond the bedding crawl one enters the second largest chamber which is really a washed out shale bed. Some nice false flooring remains here. A squeeze under boulders at stream level leads to another bedding passage which suddenly develops as a rift at a corner.  Here one can walk upright for only the second time since leaving Midnight Chamber. This state of affairs doesn’t last long because another crawl looms up.  Here the roar of a waterfall can be heard but disappointment soon supervenes as the stream is found to drop 3 metres down a narrow slot into a low sumped-up crawl which has not been passed since I last visited the cave, just before Christmas.

All is not lost however for above the waterfall is a short climb into a small decorated chamber.  A low excavated crawl leads to the current terminus – a tube filled with stal false flooring and mud.  It is possible to gaze into the promised land beyond and feel the hint of a draught.  The spoil heap in the chamber has been decorated with examples of cave art ranging from the obscene to the ingenious.  At the end of the cave one is less than 30 metres below the entrance with most of the depth potential of the system unrealised.  God knows what will happen to the pretty bits if the system gets really massive – hence my initial statement.

Peter Glanville – January 1986