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.

THE GREAT GORGE OF CHEDDAR.

Photo by Dawkes & Partridge, Wells.

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.