Part 2

To enter either of the active swallets of Eastwater or Swildon's Hole, and to follow it to its greatest depth, is to gain an insight into the action of subterranean streams such as no other method can give. The former is well illustrated by the annexed section, in which its profound depth and its labyrinth of passages may readily be understood. The difficulties and disappointments which we encountered when I conducted the operations which at last resulted in our effecting an entrance into this cavern, the existence of which was not even suspected previously, need not here be recapitulated. Altogether, what with volunteers and labourers, nearly a dozen of us were occupied ten days in the determined effort which we made, and which at last was crowned with success. From the point of view of the subsequent explorer the reader is referred to the ensuing chapter upon Eastwater Cavern, which will convey some idea of what the first explorers must undergo in any such place when to the ordinary difficulties of such an exploration is added the great uncertainty felt at every step taken, and when every boulder upon which our weight is to rest must first be carefully examined. The difficulty of our work at Eastwater is practically what must be experienced in any new work undertaken in the Mendip region, and there is much waiting to be done. If there is one thing more than another to be learned from Eastwater Cavern, it is the great importance of chokes in determining the lines of subterranean drainage. Here they are seen in every stage of formation and destruction, and the channels which have been carved by the arrested water may be readily recognised.

There is a fascination in exploration work such as that at Eastwater, where corridors, hitherto untrodden by the foot of man, open up all around as you make your way ever downwards into the heart of the hills; and even now there are many accessible passages into which as yet no one has penetrated. Reference to the section annexed will show an upper way, which terminates abruptly in a choke of stones and gravel, holding up a little water, whilst allowing a considerable quantity to pass. It is a remarkable fact that in all the labyrinths of galleries which we have explored in the profound depths of this cavern we have not yet alighted upon any portion which gives access to the continuation of this channel. There, rendered inaccessible by the barrier of débris, is, without doubt, a cavern as extensive as that which we have proved to exist in the sister watercourse hard by; and these two channels, starting from practically the same point, must diverge widely, and certainly do not unite again before the depth of 500 feet is attained.

Farther eastward in Mendip, too, are similar swallet caverns. Not far to the north-west of Stoke Lane is an interesting cavern locally known as Cox's Hole. It is situated in the Limestone forming the southern edge of the great basin in which lies the Radstock Coalfield. Owing to the existence of this coalfield, there are no deep caves accessible in this part of Mendip. Yet a good deal of water must be absorbed through the innumerable fissures into the depths of the Carboniferous Limestone underlying the coalfield, and it is by no means unlikely that this water, heated to a high point by the subterranean temperature, gives rise to the hot springs at Bath. Cox's Hole was at a remote period, when the form of the hill was very different from that presented now, an active water-channel, evidently draining towards St. Dunstan's Well. It has two distinct entrances, one, the more westerly, being a cavity of considerable size. For about 100 feet the cavern consists of a roomy gallery running more or less horizontally. Then it pinches in, until the height is less than a foot, and only those can get along who are able to compress themselves into small compass. In a few feet, however, it widens out into a good-sized passage, with fine stalactites here and there, especially at a point on the northern side where an aven opens into a chamber more than 30 feet high. Now roomy and now contracted, the passage leads on until, at a distance of 100 yards from the entrance, it becomes so small that there is considerable difficulty in proceeding. Beyond this point the cavern becomes a simple water-tunnel, of a type common in Yorkshire. At 130 yards there is a sharp descent, the floor is littered with boulders, and 20 yards farther the passage is choked with silt. A very small passage, which had water in it when I was there, is said to be passable at times, though I am inclined to doubt this. An almost vertical ascent amongst treacherous boulders, however, seems an indication of a possible route onwards, which may, I trust, with care be yet explored. The last 50 yards of the cave run to the south-east--that is, away from the direction of St. Dunstan's Well--a beautiful spring rising from the Carboniferous Limestone hard by; yet I feel sure that it must of necessity be a part of the same waterway. Either it was an inlet which received the waters of some vanished Old Red Sandstone spring, or it was a former outlet for the waters of that well. I am inclined to favour the former theory. As to the present source of the waters of St. Dunstan's Well there can be no doubt whatever. In the valley below Stoke Lane, and three-quarters of a mile distant from the well and from Cox's Hole, there is a most interesting swallet, of comparatively recent age. It is obviously certain that, not so long ago, the stream which courses down the valley flowed unchecked down its whole length, and so reached the larger stream below. Slightly retarded, in all probability, by some flood-borne silt, the water found a little joint in the western bank of the valley, and by slow degrees so enlarged it that it at last became capable of swallowing the whole. Even now a few hours' work would divert the water and cause it to resume its former course. Upstream is a mill, the owner of which has courteously given every facility for testing and for exploration. It was found that the effect of damming the mill stream entirely was to reduce the flow at St. Dunstan's Well enormously, and to render the entrance of the swallet passable. Mr. Marshall of Stratton-on-the-Fosse with his party made a successful descent, and travelled a considerable distance, mainly parallel with the valley without and to a great extent horizontally, through water-tunnels of small size. As no measurements were taken one cannot say yet how far it is passable, but he says that they did not get to the limits of possible exploration, as the time which they spent there was getting dangerously near the hour up to which it is possible to dam the water, and they most wisely beat a hasty retreat. The first opportunity will be taken by us to make use of a spell of fine weather to carry this exploration to a successful issue. Not far distant, too, is another swallet, from which the water has been diverted to be used for water-supply. This is in the vicinity of a ruined hunting lodge, and is said to lead in the same direction as the Stoke Lane Swallet. The whole of this district is likely to be very interesting, there being a series of remarkable rifts or fissures in the Dolomitic Conglomerate which deserve attention. One of these, called Fairy Slats, has been known for many years, and is indeed shown on the Ordnance map; and the fact that such fissures abound has been forcibly brought home by a disaster to a new reservoir, only recently completed by the authorities of Downside Monastery, to supply the neighbouring villages. Here a finely designed basin, having been constructed over one of these fissures, had its massive concrete bottom burst out as if it were an egg-shell the moment the water filled it, and in a single hour the whole fabric was absolutely ruined. Some measure of the extent of the concealed fissures may be gathered from the fact that 500,000 gallons of water were absolutely swallowed up without a drop coming to light in the neighbouring valley. An early visitor to the adjoining field reported that air was being ejected through the grass all around him, much to his alarm, as he was quite unaware of what had occurred. It will be a most interesting subject for inquiry, as to how far such fissures as these are the results of water action or otherwise, and it is most desirable to descend one of them at the first opportunity in search of evidence. At present I am inclined to attribute their presence to movements in the Secondary rocks, due to the intersection of the district by valleys. The Conglomerate mass has parted along the lines of the principal joints, and the rifts thus formed have become lines of drainage. This theory, in view of possible future discoveries, may have to be modified.

Above Stoke Lane Swallet, and evidently connected with it in some remote way, is a cavity without a name, the exploration of which would probably be interesting, and would be most likely to yield remains of primitive Man. Mr. Marshall also reports the existence of a fissure of considerable size, where, after a very small entrance, a point is reached with a vertical descent of great depth. All these things indicate that there is a splendid field here for further work.

Indeed there are abundant evidences of this all over Mendip. One of the most interesting problems has had further light thrown upon it by work recently done by us at Wookey Hole. The Hyæna Den and the Badger Hole are testimony that a large amount of underground action has taken place upon the east side of the ravine, yet nothing has been known hitherto of any series of dry channels upon that side. Recently, however, we have succeeded in gaining access, by way of the smallest of fissures, into what will turn out most likely to be a portion of this very series. Here is to be seen a choked-up chamber of precisely the same type as the Hyæna Den, but far deeper in the wall of the ravine. Without doubt it contains prehistoric remains, yet its excavation will entail great labour. We have already reached a distance of 80 feet from the entrance, and only a partially choked passage bars the way.

High up in the ravine at Ebbor, too, there is a very promising field for further research. This is immediately beneath a cliff on the western side of the valley, where we have already done much preliminary work. There is also a very promising little cave, slightly north of Tower Rock in the same gorge and high up in its side. Here a narrow entrance gives access to a small chamber, on the floor of which is a deep deposit of cave earth, from which I have obtained Deer bones.

At Dulcote, again, there is a series of waterways and dry caves of great interest, which in themselves bear corroborative evidence of the great antiquity of the caverns of the district. From time to time the quarrymen have broken in upon these waterways, which have been lost in subsequent operations. Not many years ago a blast blew off the top of an almost vertical shaft, carved out in the Limestone by water action and descending to a great depth. The mass of rock blown off by the charge turned over and fell down the shaft, blocking it at 30 feet from the surface. It was possible to descend to this point and throw down stones, which fell for a considerable distance; but the block was never moved, and in the process of quarrying the hole became filled, and is now lost in the general level of the quarry. Hard by, also, a cavern of considerable extent was opened, and still remains. It contains nothing of peculiar interest, though when I was first lowered into it, from a hole 60 feet above its floor, it contained very pretty coral-like splash stalagmite; and also, in the mud floor, the tubular linings of calcite, formed from the drip from above. In this quarry, too, were found a considerable quantity of the bones of Bear, Deer, Bos, Horse, etc., and these are now in the Wells Museum, where they were deposited some years since by A. F. Somerville, Esq. There are numerous other minor caves in this locality. Farther up the same valley, above Croscombe, is a small cave known locally as Betsy Camel's Hole, and it appears to have been occupied by a woman bearing that name for some years. She was, of course, carried away by the devil, according to the same popular report. It may very well have been a rock shelter at some stage of its history. Mr. Somerville informs me, too, that in Dinder Wood there is a small cave which was almost certainly a rock shelter. This also has never been explored. In fact, the whole district may be described as an unexplored field, and there is abundant room for willing helpers. The landowners, for the most part, are exceedingly kind and ready to offer every facility for scientific research.

H. E. B.

THE CHEDDAR GROUP OF CAVERNS

The great gorge of Cheddar and its caverns form a subject of surpassing interest to the student of Geology. Presenting some of the most stupendous cliff scenery in England, the great wall of rock on the southern side of the valley towers nearly 500 feet into the air, defying all attempts at mapping contour lines; and the road which traverses the ravine winds, with many a sudden turn, along the base of this noble cliff, ever upwards, until in four miles the actual summit of the Mendip downs is reached. At the entrance to the gorge, and close to the caverns owned by Gough, the hidden river bursts into the light, pouring forth a stream of great volume, which, after serving the purposes of various millers in the village, hurries on to join its sister stream from Wookey Hole, the two then flowing into the sea near Weston-super-Mare. It is strange that in all the exploration work that has been done at Cheddar, the underground channel of the stream has not once been reached. Near the entrance in Gough's Cave a fairly deep hole contains water, which changes in level along with the river itself, but no open passage leads from it. A vertical rope descent of 100 feet from the upper and practically unknown caverns belonging to Gough brings the explorer to what must be regarded as the nearest point which has yet been reached to the subterranean river of Cheddar. As this gorge is the most stupendous in the Mendip region, so is this stream the most considerable in volume. Mr. Sheldon of Wells has gauged its minimum flow to be not less than three million gallons per day, whilst its torrent at flood time must be many times as much, probably not less than eight or ten millions.

This is considerably larger than the other two great outlets of the subterranean waters of Mendip, those of Wookey Hole and Wells, each of which, however, pours forth an enormous volume. That it is the Cheddar stream which is responsible for the existence of the gorge itself no one can doubt, and it is a most interesting subject for discussion as to how this has been brought about. It is not difficult to determine what points must mark the boundaries of the catchment area, the waters of which drain to Cheddar. The road from Castle Comfort to Charterhouse on the north-east, the outcrop of Shales south of Blackdown on the north, and a line drawn from Rowberrow Farm north of Priddy to the gorge itself on the south, enclose the whole area from which the supply is obtained. This is somewhere about 12 square miles in extent. To this must be added, possibly, some water from slightly more to the eastward. It is now the commonly accepted theory that the whole of this water, or at any rate the bulk of it, found inlet into a series of caverns along the line now occupied by the gorge, and that then the processes which are so well known to be going on gradually enlarged these to the point of collapse, the falling débris being removed by the still flowing stream. It is only right to add that M. Martel, arguing from his long experience, which probably exceeds that of any man who has ever studied the subject, sees in the gorges of Cheddar, Burrington, and presumably Ebbor, the superficial channels worn by the escaping streams from the ancient Mendip plateau. He says, "The numerous dried valleys (Burrington Combe, Cheddar Cliffs, etc.), which cut through the circumference of the Mendips, witness, as everywhere, to the ancient superficial flowing off of the rivers, and to their capture by the natural wells, successively opened and enlarged in the cracks of the Limestone rock." That even small streams acting through a sufficient period of time are capable of doing enormous erosive work it would be idle to deny, but the difficulties in the way of accepting this theory as alone sufficient are too great to admit of its acceptance. It demands that the water of a very large area could find access to the eastern end of the ravine, which itself demands that the general configuration of the Mendips must have been very different from that presented now. This, from the existence of the Secondary beds in their present position, say near Harptree, was not the case; and therefore, for the theory to hold good, we must suppose that the superficial gorge was pre-Triassic. As it was not filled in, either in Triassic time or subsequently, it could not have been superficial. Of course it may be contended that the reversal of this line of argument demonstrates that the gorge is post-Liassic and may then have been a superficial channel, but I hold this to be disproved in my chapter on the antiquity of the Mendip Caves. I am, accordingly, forced to the conclusion that the Cheddar gorge was during the whole of the Secondary period a roofed-in cavern. The only difficulty which arises is a doubt as to the ability of the stream to remove so vast a bulk of falling material as must be accounted for; but when we see the process in actual operation, as at Wookey Hole, it is only necessary to demand sufficient time, and the difficulty vanishes. That a time did arrive when the rate of collapse more than kept pace with the destructive energy of the stream is indicated by the rapid rise which takes place in the road through the gorge. This favours the cave theory as opposed to the superficial channel theory, inasmuch as a superficial channel would probably have maintained a more nearly equal depth throughout.

That the portion of M. Martel's theory which explains the absence of the stream from the gorge is correct is very clear, there being obvious indications, notably at the western end of the ravine, where points of absorption might be traced beneath the high cliffs, any one of which, if excavated, would almost certainly lead to the present channel of the river beyond Gough's Caves. The Long Hole above, as pointed out in my chapter upon the antiquity of the Mendip Caves, is corroborative evidence which tends to disprove the superficial valley theory, as it is without a doubt an old cavern of absorption, which could not have existed had the ravine been a superficial valley. Everyone must lament the recent developments in the Cheddar gorge by which the northern side is being hacked to pieces to provide road metal. There are thousands of places where the same stone could be obtained, with almost equal ease; and it does seem pitiful that one of the finest places in the kingdom should be sacrificed to the most callous and sordid commercialism. The conditions under which the work is being carried on constitute also a public danger, as has now been exemplified by the collapse into the gorge of a huge mass of the rock. The dip of the Limestone is to the southward, and consequently any work done on the northern side is removing the support that holds up the great mass upon an inclined plane. Of necessity the mass above, its support gone, comes hurtling down to the roadway, and it is practically certain that, if quarrying operations continue, some day the gorge will be entirely closed by a gigantic fall.

An interesting little tributary ravine and cavern, far up the gorge, provides a perfect example of the cave theory of the formation of the gorge itself. About two miles from the village, on the southern slopes of the ravine, is an extensive fir wood. High up on the opposite side this little ravine is visible, and it may be reached with ease. Here sides that gently slope give way to precipitous walls, between which you walk. Moss-grown stones give place to new-fallen stones, and then you have before you the little ravine roofed in; you pass beneath, and find yourself in the darkness of the cavern itself, which can be followed for some distance. Here, at any rate, there can be no doubt as to the process that has been at work.

H. E. B.

ANTIQUITY OF THE CAVES OF MENDIP

When we consider the question of the age of our caverns, we are met at the outset by a mass of evidence forcing upon us the certainty that they must be credited with a very high antiquity indeed. Here measurement by years and centuries fails, and the imagination must be called in to aid us to compute the epochs that have successively elapsed since the first cave, to take one example, began to be formed at Wookey Hole. These evidences are of three kinds: historical, palæontological, and geological. In the first place, there has been obviously little change in the general configuration of our caverns since earliest historical times. The dens and caves of the earth have afforded a retreat to the persecuted of all generations, and a ready-made home when all else has failed. Here, too, with the rocky walls behind him and his protecting fires at the entrance, early man could defy the savage beasts that roamed the land in those far-off days.

At Wookey Hole it was only necessary to scratch the very surface of the accumulated débris within the mouth of the great cave to turn up fragments of Romano-British pottery and a human jaw and rib-bones. These interesting relics are in the possession of myself and Mr. Troup. From the very nature of the place, it is obvious that the tendency has been to accumulate more and more débris upon the mass of cave earth which contains these remains. Slightly deeper, yet still only in the loose earth of the cavern mouth, we found pottery of still earlier date, unwheeled and cruder. The fact is borne in upon us, that certainly for two thousand years this entrance has remained much as it is now. Perhaps a loose rock here and there has been dislodged from the overhanging cliff outside, and, crashing to the stream bed below, has there been broken up and carried away by the river. But no one can doubt that the general outline is the same now as then. And farther within the cavern an interesting sidelight is thrown on the slowness with which things change in the underworld. At the descent into the first great chamber a chalk inscription roughly made reads "E A 1769." That inscription has been there unchanged, to my knowledge, for the last twenty years, and I have no reason to doubt its authenticity. If a chalk mark remains unerased for a century and more, how long have those solid walls stood, and how long will they endure?

As I have gazed upon that inscription, the thought has come, that such a place as this would be an ideal site for national monuments. When our abbeys and cathedrals are crumbled away, these great subterranean halls will remain practically unchanged. And in the caves of Cheddar like evidences meet the eye. In the loose material in the Roman cave there, Roman and Romano-British remains have been found in abundance; and here again we are forced to the conclusion that no change has taken place since those remains were deposited.