Jackson.] 00 [December 21, 



He would welcome any reasonable theory to account for the origin 

 and distribution of drift, since there were serious objections to all 

 theories that had thus far been proposed. 



The conditions absolutely necessary for the formation and move- 

 ment of glaciers had not been proved to have ever existed in this 

 region, or anywhere, except in mountainous countries situated in a 

 temperate climate. We require, first, that there should be a suffi- 

 ciently elevated temperature to provide for abundant evaporation of 

 water; secondly, that there should be high mountains reaching the 

 regions of perpetual snow, and such variations of temperature as 

 would secure alternate freezing and thawing, so that neve or half 

 melted snow, from which glaciers are formed, should be produced. 

 Warm valleys and high mountains were then absolutely necessary for 

 the production of glaciers. A general cooling of the globe to a tem- 

 perature below freezing could not result in the formation of any 

 glaciers, even if such a general reduction of temperature took place. 



If the earth was ever cooled to so low a temperature we must 

 naturally inquire how it ever became again heated. Astronomy 

 does not justify any such hypothesis, and geological facts seem also 

 to disprove it. We can understand the theory of Fourrier, of a 

 slowly cooling globe, and his results are that the earth is losing but a 

 small fraction of a degree of heat per century, owing to the imperfect 

 conduction of heat by the thick crust of rocks. It is also shown 

 that in the epoch immediately preceding the drift (the tertiary), 

 that a tropical temperature pervaded the now temperate regions of 

 the earth. The fossil remains of monkeys, tigers, and other inter- 

 tropical animals in the north prove this fact beyond question. 



If the earth, in our now temperate regions, was at the tertiary 

 period heated to a tropical temperature, as all the facts of geology 

 prove, how could it have been suddenly cooled to so low a degree as 

 to allow the formation of three or four thousand feet thickness of 

 ice in New England and other temperate countries? No facts or 

 principles in astronomy point to any cause for such a marvelous 

 change. Physical principles give such an assumption no support, 

 and it derives none from paleontology and fossil botany, which indi- 

 cate a higher, but not a lower, temperature than now exists in tem- 

 perate and even polar regions. Witness the abundant remains of 

 elephants in the northern Siberian soil ; Mylodons in the soil of Ore- 

 gon ; monkeys, tigers and other tropical animals in the tertiary of 

 England and other northern countries. These all indicate a warmer 



