92 Reports and Proceedings — Geological Society of London. 



structure is subsequently developed. He concludes by comparing 

 the pyromerides of Boulay Bay with specimens from other localities 

 described by MM. Delesse and Levy, Professor Iddings, and Miss 

 Raisin, or collected by himself, and by discussing the quartz-filled 

 cavities which occur in certain cases. These he regards as originally 

 vesicles, and not due to any subsequent decomposition. 



2. " On the Exploration of Ty Newydd Cave near Tremeirchion, 

 North Wales." B> the Rev. G. C. H. Pollen, S.J., F.G.S. 



In November, 1896, a Committee was formed, consisting of 

 Dr. H. Hicks, Dr. H. Woodward, and the author, for the purpose of 

 exploring this cavern, which is situated in the same ravine on the east 

 side of the Vale of Clwyd as the well-known caverns of Ffynnon 

 Beuno and Cae Gvvyn, explored about twelve years ago by Dr. H. 

 Hicks and Mr. E. B. Luxmoore. Grants have been made by the Royal 

 Society and by the Government Grant Committee for the purpose of 

 carrying on the explorations ; and though a considerable time must 

 elapse before the work is completed, the results already obtained are 

 of so much importance that the author has thought it advisable to 

 bring them before the Society. In the work of exploration he 

 has throughout been ably assisted by the theological students of 

 St. Beuno's College. The cavern had been in part broken into by 

 quarrying operations, but the chambers and tunnels were completely 

 filled up with more or less stratified deposits, and had remained 

 entirely untouched. 



Although the ground above the cavern is strewn over with drift 

 and erratics from the North and from the central areas of Wales, 

 not a fragment of anything but immediately local material has been 

 discovered in the cavern itself, showing clearly that the deposits in 

 the cavern had been carried in by water before the Northern and 

 Western ice had reached this area. The work has been carried on 

 almost continuously throughout the year, and most of the material 

 has been removed for a distance of over 60 feet from the entrance. 

 The height of the cavern above sea-level is 420 feet, or about 20 feet 

 above the floor of the Cae Gwyn Cave. 



The following points appear to the author to be now fully 

 established : — 



(1) The material in the Ty Newydd Cave, as in the lower parts of 

 those of Ffynnon Beuno and Cae Gwyn, is of purely local origin. 

 Of this he can speak with confidence, as the question was before 

 him from the beginning, and the gravels were examined with minute 

 care for erratics. 



(zj) This local deposit is of earlier date than the Boulder-clay with 

 Western and Northern Drift. This was proved by the finding of 

 granite- and felsite-boulders abundantly at higher levels and over 

 the cave, and in one case filling the upper part of one of the fissures 

 communicating from above with the cavern, 



(3) The occurrence of the tooth of a large mammal (BMnoceros) 

 in the lower part of the cave shows that the animal was con- 

 temporary with, or of earlier date than, the infilling of the cavern 

 by the local drift. 



