ON THE CAE GWYN CWE. 131 



giilar talus in submerged conieis, especially where covered by clay 

 drift, has often long withstood the wind and waves, as for instance 

 on the const west of Llandulas Station, but that such a thing as the 

 few feet or inches of broken rock and interstitial debris outside Cae 

 Gwyn Cave could survive the passage of those waves is incon- 

 ceivable. 



A good deal of the force of the arguments here put forward 

 depends upon the establishment of the existence of swallow-holes 

 above the cave. This is ])roved by the opened fissures and vertical 

 cylindrical holes in the limestone. They communicated with the 

 porous re-sorted drift above, and were now open, now choked with 

 drift, or plugged by a boulder. They were filled, according to their 

 size and position in the rock-drainage system, with coarser or finer 

 material. The red clayey residuum of the decomposed limestone 

 formed an important part until the opening was enlarged to allow 

 of a free current of water carrying in material from the drift. 

 Down in the cave the action of streams was seen in the curious 

 manner in which bones and teeth were jammed into nearly hori- 

 zontal fissures where they stuck, as coarse material gets caught in a 

 sieve. Near the bottom of the last explored part of the cave, a little 

 to the right of the pick shown in fig. 3, about 20 feet from the 

 surface, where the drainage was outward to the north, a land-shell, 

 Hyalina (Zonites)^ was found in the clayey earth close to the wall of 

 the cave, just as we find them in fissured limestone everywhere. 



In other caves in this district we see clearly how the drift is 

 carried down through swallow-holes, and arranged in the wider 

 spaces in the cavernous rock below. On the opposite side of the 

 valley, in the little quarry behind the cottage, there are very good 

 exam])les of this. Here it will be seen that sometimes washings 

 from the drift (fig. 7, from a photograph by Mr. Helsby), and some- 

 times apparently masses of drift, as seen on the extreme left of the 

 same figure, have worked down into the openings as they were from 

 time to time enlarged by the chemical action of the acidulated 

 water upon the limestone. That, from the nature of the case, this 

 sort of thing must happen is obvious, but here we can see evidence 

 that it has taken place in the dragging down of the infilling deposit 

 along the walls of rock. So that the clay is pulled out, slickensided, 

 and has, when dry, almost a cleaved look, and the flat and elongated 

 stones are arranged with their longer axes parallel to the direction 

 of movement (fig. 7). The surface of the limestone shows the usual 

 fretted appearance quite different from the surface of a sea-worn 

 limestone. When large masses get detached by this chemical 

 weathering along the joints, and one cave breaks into another, or 

 the mouth of a cave breaks down, or when the drainage leads into 

 broken rock, the same process goes on among and around the great 

 angular fragments, so that there is a kind of extension of the cave 

 and cave-deposits into the talus. 



This is precisely what has taken place in the Cae Gwyn Cave, 

 where the cave-earth penetrates also the mass of angular blocks 



