Furthermore, in the position of the entrances of many of our swallets there is corroborative evidence to the same effect. The great circular swallet on Rookham, near Wells, situated far from any existing line of drainage, yet withal one of the largest cavities on Mendip, shows that great changes have taken place since it was an active waterway. The position of the caverns of Compton Bishop and of Banwell, far removed from any stream or any line of drainage possible with the present contours, proves that the configuration of the country has utterly changed since they formed the points of engulfment of any streams. The Coral Cave (as we have called it) at Compton Bishop descends abruptly into the earth, and its outlet must have been far below the level where now the Triassic Marl forms an impervious barrier. The waters of Banwell Pond rise through the Marl, forced upwards through beds which do not yield water and ordinarily retard its passage. Doubtless the Marl when it was deposited covered some earlier outlet from the Limestone. The waters of St. Andrew's Well, at Wells, are forced upwards through Dolomitic Conglomerate and overlying Pleistocene gravel, the former of which was doubtless deposited upon what was once a free and unimpeded outlet from the Mountain Limestone, similar to that of Cheddar. The water of Rickford, near Burrington, resulting from the streams engulfed at and around Burrington, is forced up through the Secondary beds, which have been similarly deposited upon the pre-existing outlet. All these things help to demonstrate that what I contend is true, viz. that our caverns as a whole are pre-Triassic in age. The Long Hole at Cheddar, high in the cliffs above Gough's Cave, lends its evidence too. Contrary to all the other caves at Cheddar, it was a channel of intake for the water which formed it. Doubtless it is a fragment of a larger cavern, which, before the gorge of Cheddar itself was formed, existed in the mass of rock occupying the whole area. At the northern end of the Limestone defile of Ebbor, near Wells, the ravine is carved through Dolomitic Conglomerate, which has been much worked for iron ore. The fact that this Conglomerate was deposited in a depression in the land, at the head of the present ravine, yet without entering it, suggests that here was an entrance to a series of caverns, the collapse of which produced the gorge. [Illustration: THE GREAT SWALLET ON BISHOP'S LOT, PRIDDY. _Photo by Bamforth, Holmfirth_] [Illustration: ST. ANDREW'S WELL, WELLS. _Photo by H. E. Balch._]