EUROPE DURIXG THE GLACIAL PERIOD. 453 



The conclusion of Professor Lewis concerning the marine 

 shells found at high elevations in glacial deposits on the 

 mountains of Wales, and which have generally been taken to 

 indicate a deep submergence during the Glacial epoch or at 

 the beginning of the second Glacial epoch, are of the greatest 

 importance, and coincide with similar discoveries recently 

 announced by Mr. Upham concerning the shells found in the 

 vicinity of Boston, and supposed to indicate a post-glacial sub- 

 sidence of considerable extent in that vicinity. These shells 

 in the British Isles, like those in the vicinity of Boston, are 

 mostly in fragments, are very thick and compact in structure, 

 and often water-worn and sometimes striated. Their eleva- 

 tion in the British Isles reaches as much as thirteen hundred 

 and tifty feet above tide. Professor Lewis thinks they 

 were plowed up by the glacier as it passed over the trough of 

 the Irish Sea, and were elevated to their present position by 

 the ice in the same manner that bowlders are seen so often to 

 have been elevated in various parts of the United States. I 

 again adopt the words of Mr. Upham in his recent comments 

 upon this theory : 



The ample descriptions of the shelly drift of these and 

 other localities of high levels, and of the lowlands of Cheshire 

 and Lancashire, recorded by English geologists, agree per- 

 fectly with the explanation given by Lewis, which indeed had 

 been before suggested, so long ago as 1874, by Belt and Good- 

 child. This removes one of the most perplexing questions 

 which glacialists have encountered, for nowhere else in the 

 British Isles is there proof of any such submergence during or 

 since the Glacial period, the maximum known being five hun- 

 dred and ten feet, near Airdrie, in Lanarkshire, Scotland. 

 At the same time the submergence on the southern coast 

 of England was only from ten to sixty feet, while no traces 

 of raised beaches or of Pleistocene marine formations above 

 the present sea-level are found in the Orkney and Shetland 

 Islands.* 



* " American Geologist," vol. ii, p. 375. 



