x rror: 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. l8l 



2. "The Drift Beds of the North Wales and Mid-Wales Coast." 

 By T. MeUard Reade, Esq., C.E., F.G.S. 



[Withdrawn.] 



This paper is a continuation of papers by the Author on the "Drift 

 Beds of the jST.W. of England and jN'orth Wales. The Author first 

 treats of the Moel Tryfaen and other Caernarvonshire drifts ; he 

 describes the drifts of the coast and coastal plain, connecting his 

 observations with those of the Moel Tryfaen drifts. The numerous 

 mechanical analyses of the various clays, sands, and gravels form an 

 important feature of the investigation. In all the samples but one, 

 a large proportion of extremely rounded and polished quartz-grains 

 have been found, which the Author maintains to be true erratics, and 

 a certain sign of marine action. He shows that the Moel Tryfaen 

 marine sands are in part overlain by typical till, composed almost 

 wholly of local rocks with a small percentage of clay, whereas the 

 sands and gravels are full of erratics including rocks from Scotland 

 and the Lake District, numerous flints, Carboniferous Limestone, and 

 crystalline schists. Throughout the drifts of the coastal plain he has 

 found a greater or less proportion of granite erratics, as well as, in 

 many cases, minute rolled shell-fragments. He maintains that these 

 drifts are the result of two opposing forces, one radiating from 

 Snowdonia, and the other acting from the sea to the southwards, 

 and their characteristics change as the one or the other force pre- 

 ponderated. 



The other divisions of the paper are taken up with a description 

 of the Merionethshire drift and that of Mid- Wales, numerous sections 

 being given. Attention is called to a remarkable glaciation of the 

 rocks at Barmouth. 



In a concluding part, giving inferences and suggestions, the 

 Author discusses the land-ice and submergence hypotheses, and 

 concludes that his observations distinctly strengthen the grounds 

 for believing in a submergence of the land to an extent of not less 

 than 1400 feet. 



An Appendix contains details of nineteen mechanical analyses of 

 tills, sands, and gravels, and a bibliography of papers, observations, 

 and theories of the high-level drifts of Moel Tryfaen. 



Discussion. 



Mr. Lamplugh said that it did not seem to him necessary to 

 suppose, as was often done, that the shelly gravels of Moel Tryfaen 

 had been taken up by the ice-sheet in their present form and trans- 

 ported bodily. On the East coast there was convincing evidence that 

 portions of the floor over which the ice moved had been caught up 

 and carried forward to higher levels. Masses of Secondary rocks had 

 frequently been transported in this manner, as well as portions of 

 the sea-bottom. Under these conditions it was no more surprising 

 that we should find shells intern. ingled with the detritus derived 



VOL. XLvin. n 



