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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 22, 



These phsenomena so exactly accord with what is to be observed in all 

 regions of excessive temperatures, whether resulting from geographical 

 position or from altitude — they are so totally beyond the power of any 

 present agencies, that it seems absolutely necessary to call in the ope- 

 ration of cold to adequately account for them. Many considerations 

 oppose the possibility of low temperatures along the parallel of 50° 

 N.L., whence these observations have been derived, and the only 

 physical condition which I can imagine sufficient to account for 

 the fragmentary detritus generally of the whole of those areas from 

 which I have borrowed illustrations, is that of an elevation of great 

 amount, such as would place the whole of the higher portions of this 

 country in regions of excessive cold. 



It can hardly be necessary to adduce proofs from those observers 

 who have described the fragmentary disintegration of rocks, and the 

 production of vast masses of angular debris, under the influence of 

 Alpine or northern cold ; such facts are familiar to geologists, and I 

 would only refer to the observations of Professor Liebig*. 



In the cause here proposed as sufficient to account for these old 

 sub-aerial accumulations, I revert to one which I ventured to sug- 

 gest many years ago with respect to the fractured and fragmentary 

 masses to be found on the summits and upper slopes of the slate 

 districts of the West of England f. I there stated that the only 

 agent powerful enough to separate and break up the laminse was 

 that of excessive cold. This view is quite distinct from the popular 

 one subsequently proposed by M. Agassiz of a " period of cold " or 

 "glacial period." A period of great elevation, and extending over a 

 wide European area, would explain a long series of allied phsenomena, 

 about which much obscurity yet hangs, but on the consideration of 

 which we cannot enter in a communication limited to an account of 

 the superficial deposits of the English Channel. As we are forced 

 to admit that portions of the sedimentary strata of our island have 

 at times been depressed some thousands of feet beneath the sea-level, 

 at others they may have been placed as high above it. Such a sup- 

 position is in perfect accordance with all that geology teaches, far 

 more so than any imaginary secular period of cold, dependent on 

 astronomical changes. 



The time allowed for communications to our evening meetings will 

 not admit of the introduction here of those proofs by which it could 

 be shown that the sub-aerial glacial phsenomena of the whole of our 

 British islands are synchronous with this period of elevation : in ac- 

 cordance with this supposition, the period of the glaciers of Great 

 Britain and Ireland was simply one when the mountains of Wales, 

 the Cheviots and Grampians, the mountains of Wicklow and Kerry, 

 attained an Alpine elevation ; it was from such sources that the rivers 

 had their origin, which carried down the volumes of water which the 

 breadth of their former courses seem clearly to indicate. This condi- 

 tion of things was not confined to our own limited area ; many years 



* My attention was called to this reference after the reading of this paper by 

 Dr. Lyon Playfair ; the ed. is the 2nd. 

 f Trans. Geol. Soc. vol. vi. p. 437. 



