"WARREN UPHAM, ESQ., ON CAUSES OF THE ICE AGE. 227 



occurred when the sea bottom was elevated and that they had 

 been eroded by some great rivers. 



Mr. A. Ent. Gooch, F.G-.S. — I should like to refer to paragraph 

 11 of the paper : — " Others have suggested that the sun's heat has 

 varied, and that the Ice Age was a time of diminished solar 

 radiation." It is well known that many astronomers, and those 

 who are best qualified to speak on the matter, including Sir 

 Robert Ball, admit that we know very little of the present 

 condition or past behaviour of the solar body. Supposing a 

 large portion of the body of the sun to have been gaseous, 

 his temperature would have been lower, and the radiation- 

 rate less. The other point is " Concerning the latter {i.e., the 

 earth's own internal heat) ; " it is well ascertained that during at 

 least the Mesozoic, Tertiary, and Quaternary eras, it has affected 

 the climatic average by no more than a small fraction of a degree. 

 Many of us would like to know what explanation is given for 

 that, and why such knowledge of the earth's internal heat is 

 assumed. 



Rev. John Tuckwell. — Professor Tyndall, in his book on 

 Heat a Mode of Motion, draws attention to the singular con- 

 ditions required of an Ice Age, by saying that it is often over- 

 looked that a large amount of ice accumulating on one part of the 

 earth's surface would necessitate a large amount of evaporation 

 caused by intense solar heat at another part of the earth's surface. 

 The quantity of water on the earth is limited, and if there be a 

 great accumulation of snow at some places, there must be a 

 proportional amount of evaporation at another part of the earth's 

 surface, which woidd mean very great heat. I should have liked 

 to have had some further information on that point. 



The President. — 'No doubt it implies evaporation ; but we do 

 not know what length of time that may have been spread over. 

 Therefore I do not see that we can infer that the temperature 

 must have been very great. It may have been going on slowly. 



Rev. John Tuckwell. — Would it not be that if the period of 

 the Ice Age was brief, then the temperature must have been veiy 

 great, for large accumulations of the frozen vapour to form at the 

 poles of the earth ? The shorter the period of the Ice Age, it 

 seems to me, the greater the amount of heat that must have been 

 at other portions of the earth's surface. 



The President. — No doubt, but even taking the period that 



