Digging for Mendip Caves
W. I. Stanton
(From: Studies in Speleology, Vol. IV, September 1983, 77
Reproduced here with the kind permission of Dr W. I. Stanton).
Only one-eleventh of the cave passage presently known under Mendip was accessible before 1900. Most of the remainder was discovered by digging. Of a range of possible surface digging sites, the most promising are the shale-edge sinks of Central Mendip. Underground, almost any choked passage is worth a dig, as long as cave scenery and interest are conserved. Experiences in passing boulder ruckles and disposing of tipstuff are described. Most diggers are either short-term opportunists or long-term planners. It is argued that the supply of easily-found caves and grottoes is nearing exhaustion, so that conservation of those that remain is supremely important.
The Mendip caves are hidden. Twelve out of the fourteen major systems were nameless hollows in the ground before digging revealed their existence. The importance of digging to Mendip cavers may be judged by the fact that, in the year 1900, only four of these systems were known, and one of them, Wookey Hole, had always been open. Their total passage length was 2.5 km.
By 1982, surface digging had opened the other ten major systems, underground digging (and diving) had vastly extended most of them, and the total passage length had increased to 35 km. Nor was this all. A large number of medium-sized systems (roughly defined as 120 m to 800 m long) had yielded to the spade. In 1900 only seven of this category (passage length 1.6km) had been open, but by 1982 the number was 31 (passage length 9 km).
Statistically, then, the popular Mendip sport of cave digging is amply justified by results. Every digger hopes that his work will add significantly to the length of known cave, but the main reason for digging is personal. To the experienced worker, the moment of breakthrough into unknown caves, after months or years of effort, is incomparable. In the darkness ahead lie mystery, beauty, challenge, danger, knowledge, fame - all the thrill of virgin exploration, so incongruous in exhaustively-charted Britain. There, also, new facts may be gleaned, ancient questions answered, longstanding theories proved or disproved. The unexpected is the rule.
So the speleologist strives for the excitement and the discipline of exploring new cave systems, and the months or years of digging are counted time well spent.
To some, digging is a fairly tedious chore, and they are only sustained by the hope of triumphs to come. To others, the digging operation itself is fascinating. It is seldom simple. The larger digs demand skills comparable, in their complexity, to those of the engineers who built the railways. Shafts are sunk, trenches driven, best routes chosen, solid rock blasted, boulder ruckles penetrated, unsafe ground made stable, flooding problems overcome, grottoes preserved, tip space found for tons of rubble, hoists or tramways established, and so on. It is vital to foresee potential problems and prevent them arising. A major setback, such as the collapse of a shaft, can so dishearten the digging team that the project is abandoned.
More for the specialist, but interesting, apparently, to many cavers, is the study of the sedimentary deposits dug through. Mud, sand and rocks do not accumulate haphazardly, but as the result of certain well-understood processes. By diligent observation the stratigraphy of a choke can be worked out, and, especially in surface digs, this can give clues to the history of a wide area. For example, a dig at Charterhouse provided new evidence of the way that lead slaggers operated a century ago, and of local conditions in the Pleistocene periglacial climate thousands of years before that (Stanton, 1976). Another Charterhouse "cave", Grebe Swallet, was proved by digging to be an 18th century lead mine with ore deposits still in situ.
Where to Dig.
"Caves be where you find 'em", the famous axiom first stated in the sixties by Fred Davies to express his scorn for speleological pundits, has been proved true time and again. Tyning's Barrows Cave, one of the biggest to be found recently, appeared on its own when the ground collapsed in the great rainstorm of July 10th, 1968. Little digging was required to open its full extent. No-one could have predicted the presence of Wookey Hole Cave's top entrance, a few feet beneath the grass of a featureless field, had not a diver explored it from the inside. The same diver, John Parker, discovered a vital link passage in Wookey Hole by climbing high into the roof of the Seventh Chamber, where no reasonable speleologist would have expected it. These and other caves have just turned up, against the odds, whereas dedicated diggers, toiling for years at 'promising' sites, have had to modify Fred's axiom to "caves be where you make 'em".
Be that as it may, some parts of Mendip are more likely than others to yield unknown caves. Basically it depends on how long a particular region has been subjected to cave-forming processes. Central and West Mendip are the oldest karst areas, and in East Mendip the length of time that the Carboniferous Limestone has been exposed to the elements grows shorter the further east one goes. Most of the East Mendip resurgences are immature (Barrington and Stanton, 1977, 208-209) and, unless abandoned upper levels exist, like those intercepted by Fairy Cave Quarry, the caves leading to such resurgences are likely also to be immature. The St Dunstan's Well catchment is an exception, and on present form it is wildly optimistic to look for major caves in the Gurney Slade, Ashwick, Whitehole, Finger, Cobby Wood, Seven Springs, Holwell, Hapsford and Oldford catchments.
Having chosen a favourable area, where then to apply shovel to ground? Experience shows that the biggest swallet caves are those that engulf sizable streams from the Old Red Sandstone hills. Not all of these streams break surface. At Sludge Pit, Tyning's Barrows, Cuckoo Cleeves and in Fools' Paradise in Swildon's and the August Series of Longwood Swallet, streams that enter or entered the systems not far below ground level have come direct from the Lower Limestone Shales. On this basis, any depression at the edge of the Shales could lead into an important cave.
The hundreds or thousands of simple dolines that dimple the main limestone outcrop, well away from the Shales, are different. Many have been dug, and several worthwhile caves entered (Cow Hole, Hunters Hole etc.), but only one is of major size. The reason is the tiny catchment area of each doline. Only a little water funnels down at the best of times, and its dissolving power is soon exhausted. The stream, a mere trickle, is underpowered.
It would be wrong to assume that the limestone dolines are not worth digging. The major exception to the general rule is Lamb Leer Cavern, a fossil system formed when the water table stood 150 m or more higher than now. It is genetically unrelated to any modern streamway. Several other limestone doline caves are fossil phreatic systems. I suspect that many, even most, of the limestone dolines are the points at which the ground surface, on its downward journey under the influence of dissolution, has intersected ancient high-level caves.
There is always a chance that the immature system beneath a doline will connect, fortuitously, with a major streamway. Cowsh Avens (Davies, 1975) are a classic example, with their roomy splash-carved shafts and tiny connecting creeps dropping 130m almost sheer from an infant doline to Swildon's Four.
A third class of depression is common in the Devil's Punchbowl - Wurt Pit - Wigmore area of Central Mendip. They are termed leakage hollows, because they mark the points where small streams, gathering on a surface layer of residual clays, leak through into the Dolomitic Conglomerate below (Barrington and Stanton, 1977,223). A few have been dug (e.g. Pounding Pot, Wigmore Swallet), but only at Wigmore has a small cave been found. The streams, though often larger than those of the limestone dolines, are still underpowered, and they may be incapable of clearing the masses of clay that slump into the hollows.
Summarising prospects for the hopeful digger, West and Central Mendip are more promising than East Mendip, and the shale-edge sinks are probables, the limestone dolines possibles, and the leakage hollows doubtfuls.
Inside the caves the question of where to dig is basically simple. Almost any choked hole, however narrow, may lead to an extension. The obvious continuation of a main passage is not always the best site - as in G.B. Cave, where work in the Ladder Dig creep proved more fruitful than the assault on the terminal choke of the mighty Gorge. Few digs have been pressed harder than the one at Blackmoor Flood Swallet, Charterhouse, where some 300 working visits were made by two teams in two years. The passage being followed was a major abandoned streamway, starting from a shale-edge sink, but a mere 122 m of advance was achieved. In contrast, an hours' work on the Blasted Boss, at the end of a flat-out crawl in Swildon's, opened up the St. Paul's Series, the key to several kilometres of passages and streamways.
What are the signs of a promising underground dig? The most popular preference is for a draught, the stronger the better. A current of air blowing into or out of a small hole usually means that there is a large volume of emptiness, or a way to another entrance, on the far side. (Beware, however, of the body heat convection draught, a local phenomenon created by the presence of the observer. A draught rising past you is suspicious).
The outstanding example of an obstinate Mendip cave betrayed by its draught is Reservoir Hole, which in 1950 was no more than a chink in a cliff in Cheddar Gorge, emitting a powerful gust. We blasted past the chink and two more tight places and came to a small chamber. Beyond was a vertical rift jammed full of rocks, up and down. The draught blew down at us among the rocks, so, after some unsuccessful ruckle-sapping, we blasted a 2.5 m tunnel through solid rock to enter the rift 7 m higher up. Here it was open, a chamber with a boulder floor.
How now to find the draught? Bee-keeper fashion we ignited rolls of cardboard, filling the chamber with smoke. Creeping through the murk, we located clear air zones at floor level. The draught was welling up between boulders encrusted with moonmilk like Camembert cheese. Four years' digging took us down 33 m through the boulders to a chamber. At one end was a tunnel with our friendly draught emerging over an earth choke. Months later we crawled forth from the choke into a larger gallery.
Our draught seemed lost, but one day it was noticed, much weakened, trickling out of a boulder pile that terminated an obscure alcove. A few exciting days collapsing the boulders, and we were up in a rift chamber. Delicate smoke tracing detected our draught, a mere zephyr now, wafting out of a massive boulder ruckle. Digging up vertically through the boulders, 25 m in three years, we entered Golgotha Rift, which is draughtless.
There have been provocative draughts at many other successful digs including Lionel's Hole, the Fairy Cave Quarry systems, Manor Farm Swallet and Tankard Hole, and a strange reversing one at the Blasted Boss, already mentioned.
The other fluid that enters and leaves caves is water, but it is much less meaningful than air. Even a large flow, several million gallons per day, easily traverses passages impenetrable to man. Many large streams in East Mendip arise from or enter caves so immature as to be hopeless prospects. The same may be true of springs like those of Axbridge, Ludwell and Dunnett Farm in West Mendip, but the limestone hills surrounding the lovely Winscombe valley have a history of ancient karstification that is still obscure, and surprises are possible.
Although modern water may be unhelpful, ancient streams have sometimes left us messages saying "dig here". In Gough's Cave the scalloping said "dig in the Boulder Chamber", and the message was reinforced when excavation revealed a passage full of riverborne sand that had been punched through earlier mud deposits (Stanton, 1965). Alas, the choke was found to extend below the water table. Scalloping and the sediments left by old streams can even indicate the best direction to follow through boulder ruckles
My first cave dig was in Rowberrow Cavern in 1942. Since then I have dug in 46 different Mendip caves and mines. Most were straightforward digs involving well-tried methods (Cullingford, 1969), but a few required the development of novel techniques to solve special problems.
In Reservoir Hole, the commonest obstacles were extensive ruckles of small to medium-sized boulders, clean and free of mud. The first major dig was downwards beneath Moonmilk Chamber, and we shored up the ruckle with timber and corrugated iron. Rocks kept slipping down from outside the shoring, and we tried to stabilize them by pouring in liquid cement. It worked, and suddenly a great light dawned. Forget the timbering, just use the cement!
We used limestone dust and Portland cement in a 3:1 ratio, premixed dry and dragged down to the site in car inner tubes. (These can survive falling, full, down 15 m shafts). The grout is made up with water caught from local drips to a consistency varying from porridge to "Montezuma's Revenge", depending on the depth of penetration desired. It is poured into the ruckle to form a curtain round the area to be excavated on the next visit. The setting time can be shortened by using an accelerator. We found that the grout was best applied with a small tin, to avoid pouring too much at one place by mistake. If lateral penetration round corners is required, a funnel and flexible hose can be used. Large voids should be filled with stones before applying grout. When overhanging ruckles need reinforcing, special skills are involved - the successful practitioner of the 'sweeping upward undersloosh' is a real craftsman!
In this case, grouting gave quick and easy results. No constructional skills were needed and the shaft is secured for ever, as grout does not rot or rust. In effect, it is 'instant stal', which will consolidate any clean ruckle or scree.
The next big ruckle in Reservoir Hole was beyond Topless Aven. This time we wanted to work vertically upwards through it, and we adopted a flexible sapping/building approach. By the delicate use of explosives, key rocks in the overhead ruckle were dislodged, an action that had two possible effects.
The first possibility was that a few boulders would fall, but the main mass of the ruckle would hold firm. In this case, after a decent interval for stabilization, we would break the fallen rocks with a big sledgehammer and repeat the treatment. As the roof of the boulder chamber thus formed rose, we distributed the rubble to support the walls and build up the floor. So the boulder chamber would rise through the ruckle like a giant bubble, until it burst out into the space above. Access to the chamber from below was maintained via a climbing shaft like a stone-lined well, carefully built of large rocks and extended upwards to keep level with the chamber floor. After blasting, fallen rocks might cover the top of the climbing shaft, or balance precariously on its edge, or jam part way down it. The first ascent after firing a charge was always interesting, and more than once the volunteer climber (an agile bachelor, for preference) was observed by his cynical comrades to shoot out of the shaft bottom a few inches ahead of a high-speed boulder. "Forgotten something?" they would enquire.
The second possibility was that the whole overhead ruckle would subside. When this happened, all the debris had to be removed before the next blast. Gradually, as work continued, the ruckle slid down to the blasting point like sand into the hole in an eggtimer, and when the breakthrough occurred the first explorer popped up like an ant-lion at the bottom of a highly unstable funnel. The first job then would be to make the funnel safe by building up a climbing shaft and adjusting the walls to a lower angle.
Working under the constant threat of bouncing boulders induces a state of tension, and it was no coincidence that workers in the Reservoir Hole ruckles tended to abandon them in the spring for some surface dig that was less emotionally taxing. Even when the surface dig developed into a nasty underground one it was not easy to swap (for example) the cold, wet, slimy, miserable, safe conditions of Blackmoor Flood Swallet for the warm, dry, terrifying ones of Reservoir. In fact only one injury occurred during the whole exercise, when a rock slipped and dislodged the end joint of a digger's finger. He made a fast exit from the cave, leaving a blood trail, and the wobbly digit was sewn together by a kind doctor in Cheddar.
I have mentioned elsewhere (Stanton, 1982) the value of building temporary dry stone walls to protect cave scenery from the effects of blasting. Scenery is damaged not only by flyrock (quarryman's term) but also by flymud from the tamping of plasters, which coats stal and passage walls with a messy brown film. We resorted to shothole blasting where there was a risk of this kind. A well placed shothole requires far less explosive to achieve the same result as a plaster charge, and it can often be tamped with water to avoid the mud problem. In Blackmoor Flood Swallet we tried incorporating a length of heavy steel rod in the shothole tamping to increase its inertia, and it seemed that more rock was broken. Drilling shotholes by hand is a chore that can yield proportionate rewards. We found that penetration rate was increased by angling the hole downwards and adding water very frequently. The cuttings then squirt out with every blow of the hammer - straight into your eye!
Water in a dig is a mixed blessing. It can be invaluable when there is mud or silt to be removed. In one dig we had a spoil disposal problem - lack of dumping space. But the narrow canyon leading to the working face was cut in great banks of mud. When the stream was in spate we demolished the mudbanks, allowing the floodwaters to remove them in liquid form. It took us several days of furious trampling, knee-deep in inky fluid like demented vineyard workers processing the grape harvest, but we cleared the passage of mud and made space enough for months of tipping.
In the lowest level of Reservoir Hole we cleaned up a section of disgustingly muddy passage by damming a tiny stream and sending it down a hose to a spray nozzle which removed the mud, over a long period, as slightly muddy water.
On the debit side is the difficulty of digging a choked sump that floods as soon as it is disturbed. In Blackmoor Flood Swallet we soon learned not to prod the terminal sump in the hope of draining the pool. Usually the opposite happened, and we presented a sorry spectacle as we sat on submerged upturned buckets, drilling shotholes in the stal blockage beneath which the stream seeped away. On one occasion the cave end was a deep pool and the way ahead was sumped. To pass it, four wet-suited diggers packed themselves into the pool like lead soldiers in a eureka jar, displacing an equivalent volume of water forwards, downstream. When they climbed out, water level fell enough to give a small air space in the sump, so the bravest wriggled through and removed the obstruction beyond.
All digs produce rubble that has to be dumped somewhere. The method of disposal is a measure of the diggers' expertise and imagination. At many places in Reservoir Hole we used tipstuff to build paths, as part of the routemarking that is vital to conservation. This involved carrying bucketfuls of rubble for quite long distances.
Sometimes the lack of tip space becomes critical, as in the case of Blackmoor Flood Swallet where we washed away the mudbanks. This action created a tunnel some 2m in height and width. Our strategy was to backfill it with rubble, leaving only a hands-and-knees crawl in the roof as a way out. Backfilling began at the furthest point from the working face, and for obvious reasons the gap between tip and face gradually lessened. The crunch, when the tip catches up with the face, never came for us, as we pulled out to return to the terrifying ruckles of Reservoir. This may have been why we never had trouble with bad air; in Reservoir Hole's South Passage dig, where we used the same backfilling principle, ventilation through the narrow access passage could not supply the diggers' oxygen needs and remove their CO2 and the dig was abandoned because of splitting headaches.
Characteristic of the Mendip digging scene is the infinitely variable approach of different digging groups to their subject. Some believe in mechanisation and set up tramways or cableways with motorised winches and clever automatic tipping devices. The trouble with this approach is that, because so much energy goes into the installation and maintenance of the equipment, the dig itself may suffer. Sod's Law also applies, in fact another diggers' axiom (Lawder, 1954) states "The use of elaborate apparatus automatically ensures that an impassable rift will shortly be encountered". But impassable rifts are not as terminal as they were, as was shown by the elaborately equipped excavation that laid open Rhino Rift (Audsley, 1971).
Others believe in 'getting on with the dig' and limit their equipment to the basics: pick, shovel and bar, bucket, rope and pulley, hammer, explosives and cement. Debris is removed by hand in buckets or sacks, sometimes by a human chain. Some digs need no aids at all. The clay in a passage in Lamb Leer was so sticky that it was dug by hand and formed into Hensler's Prefabricated Balls, which were passed along a human chain to the tip.
Diggers are either opportunists or planners. The opportunist thinks in terms of a dig lasting a few days. He ferrets ahead, opening a route no larger than is necessary to squeeze through. If he breaks into a cave, the gamble has paid off. If there is no breakthrough, and the dig, though still promising, becomes impossible to work because of its small size, he goes elsewhere.
The planner prepares for a long siege. The stronger the enemy, the sweeter the victory. He aims to be unstoppable, so he tries to create an appropriate working environment. Physically, there should be plenty of room, stable roof and walls, a clean dry easy approach, and reserves of tipping space and engineering ingenuity enough to challenge the most formidable obstacle. Psychologically, there should be no risk of major setbacks. An inexorable march forward, even if slow, generates confidence and enthusiasm.
Sometimes the planner is forced by circumstances to lower his standards. This happened in North Hill Swallet, where the relentlessly small dimensions of the natural passage forced the diggers to become ferrets, working in excessive discomfort: wet, muddy, oxygen-starved, in flat-out crawls, with no tip space except far away in the surface depression. They were, as luck would have it, a special breed of hard men, whose machismo and sheer stubbornness ruled out any thought of defeat. Their legendary exploits made them heroes in their own lifetimes, and a society was formed in their honour, by themselves, whereby the memory of those great years is kept forever green.
Most diggers follow a course between the extremes of planning and opportunism. The two ethics do not go well together. At Blackmoor Flood Swallet (Stanton, 1976) we dug on different days to another group who made no secret of their intention to explore all there was, if the breakthrough occurred on one of their trips. As they were given to ferreting, while we were planners, we feared that we would do most of the work and they would make most of the first explorations. Perhaps fortunately, no great breakthroughs were made, but we resolved never again to share a dig.
'Value for money' is a familiar concept, praised by all, but 'value for effort' in digging is by no means generally accepted. The planners are kept going by the conviction that if they persist long enough, the reward of the first exploration will be theirs. Some opportunists, it would seem, take care to be in the right place at the right time. The first explorers of part or all of a new cave may be persons who contributed little to the dig or the buildup, as happened at Manor Farm Swallet, Wookey 24, Charterhouse Cave, and elsewhere. Others may shrug their shoulders and say "that's life", but to planners, the injustice is distasteful. 'Reward for effort' is the planners' creed, and if a regular digger is absent on breakthrough day they will hold back, sometimes for weeks, until he can lead the way into unknown country reserved for him.
Some will argue that it doesn't matter who first enters the cave, as long as the cave is entered. They are not usually planners, or diggers of any persuasion who have ever put a great deal of effort into a dig. Few cavers will deny that the most exciting exploration is a 'first'. Certainly the cave pirate must crave a 'first' desperately, if he is prepared to steal it from his fellows.
Keeping up with the Conservationists.
The observant digger will now and then come across things that he would like to preserve for others to experience. There may be stalactites in the middle of the passage, a big exotic boulder, attractively coloured or sculpted rock walls, an ore vein, mining relics, a puddle containing cave bugs, sediments of geological or archaeological interest, a gour holding back a duck, crystals, mud formations or footprints in the floor - the possibilities are endless. Such items make a visit to the cave more interesting, but they can seriously hinder the digger.
Features of this kind can mostly be preserved and displayed, given a little determination. The immediate need is to protect them from the diggers, so face work must stop while the conservation works are carried out. First the threatened site is clearly marked so that its existence cannot be overlooked. Coloured tapes are invaluable for this job. Then a path is laid, a wall built, even a notice placed. Tapes (removable for photography) dangling beneath stalactites remind crawlers that there is something overhead to be careful of. Rather than blast away the gour, a hole can be drilled through it, or a narrow channel chiselled, that can be blocked when the dig is finished. If an object is loose, and liable to be collected, it may be walled off and a peephole left in the wall. The vital thing is to do the work at once - yourself. If it is left for someone else to do, later, the prized object will be damaged or destroyed.
It is not practically possible to preserve some things. Stalactites that must be squeezed past, sediments in the choke that has to be dug away, a crystal pool in the floor - either they are dispensed with, or the dig judders to a halt as people lose patience. All that can be done for doomed features is to photograph them, in black and white (for publication) as well as in colour.
A simple way to clean up a muddied passage is to place a bucket under a drip and sloosh the water around on every visit.
It may well be that the golden age of Mendip digging is coming to an end. Nearly all the large active shale-edge sinks of Central Mendip, and many of the minor ones and their dry equivalents, have been opened into cave systems. A few enigmatic areas remain, where in spite of much work at apparently favourable sites (e.g. the Hillgrove group of swallets) nothing much has been found.
The shale-edge sinks further east have produced only one large cave, at Thrupe Lane, but Withyhill and Shatter caves show that they exist, at least in the St Dunstan's catchment. The sites of the natural sinks on the north side of the Beacon Hill pericline are seldom obvious. Further west in Mendip the Burrington swallets, in a unique position on the inner edge of the Burrington erosional terrace, form another puzzling group whose apparent potential has yet to be realised.
The limestone dolines offer a sporting challenge, but they are rapidly being lost as farmers and others fill them with rubble and rubbish. Some, such as Tankard Hole, could have led to great things. Of the leakage hollows, the less said the better. One of them, one day, may lead to something good. Intercepted caves, as found in gorges, valleys, mines and, alas, quarries, are more promising and will produce surprises.
Wookey Hole Cave is an astonishing anomaly in the Mendip scene. It is the only large resurgence that has been penetrated and yet it is Mendip's third longest cave. There must be a comparable system at Cheddar.
Underground digging still has great potential, but inevitably the scope for ferrets and opportunists will diminish, and progress will require the prolonged efforts of the planners. Here too the divers will play an increasingly important part.
Less than a century has passed since digging for Mendip caves began. When the century is up, in 1990, the golden age will be almost over. Subsequent generations, looking back, will be amazed at how easy it was to find Mendip caves in the Twentieth Century. And how the cavers of that age squandered their finds! 'Easy come, easy go' was their attitude to the lovely fascinating places that they discovered in such profusion. The present movement towards cave conservation is born of necessity, as grottoes fade and are not replaced. When our grandchildren sink their mineshaft into Tankard Hole, bypassing the rubbish-filled depression, and plan the usual Twenty-first Century five-year-dig, they will have learned the lesson of bitter experience. Conservation of the natural wonders and beauties that they encounter will be their first priority. Or so I piously hope.
AUDSLEY, A. 1971. The history of the present dig at Rhino Rift. J. Wessex Cave Club 11, 236-240.
BARRINGTON, N. & STANTON, W.I. 1977. Mendip, the complete caves and a view of the hills. Cheddar Valley Press, Cheddar, 236pp.
CULLINGFORD, C.H.D. (Ed.) 1969. Manual of caving techniques. Routledge and Kegan Paul, London, 416pp.
DAVIES, F.J. 1975. Not now and again, but again and again and again - VI. J. Wessex Cave Club 13, 224-227.
LAWDER, R.E. 1954. Back to Shakespeare, or how now old mole. J. Wessex Cave Club 3, 6-8.
STANTON, W.I. 1965. The digging at the end of Gough's Cave. J. Wessex Cave Club 8, 277-283.
STANTON, W.I. 1976. The dig and deposits at Blackmoor Flood Swallet. J. Wessex Cave Club 14, 101-106.
STANTON, WI. 1982. Mendip - pressures on its caves and karst. Trans. Br. Cave Res. Ass. 9, 176-183.
Page Created: 11 March 2009