WARREN UPHAM, ESQ., ON CAUSES OP THE ICE AGE. 225 



duration since these ice sheets disappeared, it is impossible to 

 suppose that those surfaces would have remained in all their fresh- 

 ness down to the present day. 



Then as to the cause of the glaciers, I think it is exceedingly 

 interesting to observe that Lyell's view — which had been partially, 

 at any rate, eclipsed by the more attractive, and probably less 

 understood, views of Croll (because they are entirely astronomical) — 

 is now again rising to the surface, and that fresh evidences have 

 been brought to light by the deep sea dredgings. This is, I think, 

 a most valuable part of Mr. Upham's paper. He has accumulated 

 and brought into this contribution to our Society a large number of 

 instances where the valleys and fjords which dissect the various 

 mountainous ranges of Europe, Asia, and even Africa can be 

 tracked out under the ocean for a great distance ; and, as I 

 explained when reading the paper, no channel of this kind could be 

 cut under the ocean. As long as the land is under the ocean it is 

 preserved from erosion or denudation of that kind. Channels 

 running out into deep water must have been cut when the area 

 was elevated out of the ocean. This subject has been more 

 recently investigated by Professor Spencer in his papers on " The 

 Reconstruction of the Antillean Continent." 



Owing to the depths of these submerged valleys it involves 

 the supposition that the lands bordering the ocean had been 

 elevated 1,000, 2,000 or more feet at the time of these river 

 valleys being eroded. So that there is strong evidence coming 

 to light that Lyell's view, which was based on the supposition 

 of the elevation of the land surface over a large part of the 

 northern hemisphere, as accounting for the glacial period, was 

 in the main the true one. Therefore I think this contribution 

 is of great value as bearing on Lyell's original hypothesis. 



Mr. Joseph Bkown, C.B. — Although I cannot pretend for a 

 moment to be a scientific geologist, my walk in life having led me 

 in another direction, I certainly have been, I may say, an amateur 

 geologist for the last sixty years, and during many journeys on 

 the Continent I have taken every opportunity I could get of 

 observing geological phenomena, and have frequently been struck 

 by the very significant fact mentioned by Professor Hull, that 

 these stride and marks of glaciation found on the rocks in many 

 places are a great deal too fresh to admit of the supposition that 

 they were made 20,000, 30,000 or 50,000 years ago. I do not 



Q 2 



