A. C. RAMSAY ON THE ISLAND OF ANGLESEY. 121 



before, during, and after the Glacial epoch ; and thus it was that 

 Anglesey got separated from the mainland of North Wales by what 

 is, after all, merely a long and broad glacial groove. 



This with me is no hasty conclusion. Having at intervals been 

 much in Anglesey, and occasionally living on the banks of the Straits 

 for years, I wondered what might be their meaning. It is difficult or, 

 perhaps, impossible to look at this long narrow channel without the 

 idea entering the mind that at seme unknown but comparatively recent 

 time it may have formed part of the course of a large river flowing 

 from some unknown land now • submerged or destroyed by denuda- 

 tion ; and this hypothesis possessed me so strongly for years, that, 

 though always in doubt and in search of a better, it helped to blind 

 me to any other. Last summer, however, while looking at the 

 Straits, the whole truth of the case seemed suddenly to flash into my 

 mind. The result I have given in this paper. 



EXPLANATION OF PLATE XIV. 



Geological Map of Anglesey and the adjacent parts of North Wales, with a 

 contoured section of the form of the ground along the line A b. 



Scale of Map, 12 miles to an inch. 

 Scale of Section, 4 miles to an inch. 



Discussion. 



Mr. Hicks said he did not agree with Prof. Ramsay that the 

 Menai Straits were formed by a glacier passing over the land. The 

 hollow was made by the great changes which took place towards or 

 at the close of the Palaeozoic epoch. The great N.E. to S.W. faults 

 on both sides of the Straits dropped the Carboniferous beds against 

 the older and harder Palaeozoic rocks, and a depression containing 

 broken-up and soft beds was thereby formed at the close of the Palaeo- 

 zoic epoch. During the Glacial epoch the land here stood very much 

 higher than at present, and the present hollow formed then a valley 

 above sea-level. The separation cf Anglesey from the main land 

 occurred at a comparatively recent period, and is entirely due to the 

 gradual encroachment of the sea over a gradually subsiding area. The 

 subsidence which has taken place along the western coast, even in 

 historic times, has been considerable in extent ; and the sea is still 

 continually encroaching on the land and along the lines of valleys. 



Mr. J. F. Campbell confirmed the author's views. He had found 

 striae high up on the Snowdonian range, in Ireland, and all over 

 the British Islands, pointing in a direction towards Scandinavia, and 

 thence towards the North Pole. 



Mr. Charles Moore remarked that the Mendips were upheaved 

 before the formation of the New Bed Sandstone, which lies uncon- 

 formably upon the up-turned Coal-measures, and that the Carboni- 



