238 WARKEN UrHAM, ESQ., ON CAUSES OF THE ICE AGE, 



pellecl to assert that the combination of low eccentricity and 

 high obliquity will promote the accumulation of glacial ice 

 in high latitudes more than any other set of circumstances 

 pertaining to the earth's orbit. It seems to me that the 

 Glacial age may be due to these conditions in combination 

 with a favourable disposition of land and water. This 

 theory implies, or rather does not exclude, simultaneous 

 glaciation in both hemispheres. It does not imply that the 

 Ice age should last only ten or twelve thousand years. . . , 

 The date at which a minimum of eccentricity last coincided 

 with a maximum of obliquity can almost certainly be deter- 

 mined. According to Stockwell, the obliquity has been 

 diminishing for the past 8,000 years, and was within 

 2] minutes of its maximum value at the beginning of that 

 time. According to Levei'rier, the eccentricity passed through 

 a minimum 40,000 years ago, the value being then about two- 

 thirds of the present one. So far as I know, the obliquity 

 has not been computed beyond 8,000. This can, of course, 

 be done for Stockwell's value of the masses of the planets, 

 or for newer and better ones. All the indications seem to be 

 that within thirty or forty thousand years conditions have 

 occurred, and have persisted for a considerable number of 

 thousand years, which would favour glaciation on the theory 

 of this paper." 

 After a careful consideration of Dr. Becker's investigation, and 

 bearing in mind the difficulty of reconciling any astronomic 

 theory with the uniqueness of the Glacial period, it seems to me 

 that the ice accumulation was due chiefly to the pre-glacial high 

 altitudes of continental areas, of which we have undeniable 

 evidence in the fjords and submerged continuations of river 

 valleys. To a less degree, as I think, the areas of glaciation were 

 probably increased, or the boundaries of the ice-sheets may at 

 times have retreated and re-advanced, because of varying astro- 

 nomic conditions. 



