THE GLACIAL PERIOD. 231 



than is now the case, for many of the regions which were 

 formerly covered with perennial snow have at present a very 

 small rainfall. It is, therefore, to say the least, not improbable 

 that during the Glacial Period the amount of heat received from 

 the sun in summer may have been as great or even greater than 

 it is now in that season ; in other words, the seasons may have 

 been more strongly contrasted than they are at present — less 

 heat reaching our latitudes in winter, but more in summer, than 

 is now the case. The summers in Central and Southern Europe 

 were probably very humid, and the abundance of snow and ice 

 upon the mountains would tend to chill the air, so that although 

 more heat may have been received directly from the sun, it is 

 doubtful whether the climate during the warm part of the year 

 would be, upon the whole, as genial as it is with us. Upon the 

 mountains and in the regions covered by the ice-sheet, a large 

 proportion of the moisture would be precipitated in the form of 

 snow. Notwithstanding this we cannot doubt that in summer 

 there would be copious rain, while enormous quantities of snow 

 would be melted, and the rivers flowing from the ice-sheet and 

 the local glaciers of the mountain-regions would be swollen to a 

 prodigious degree. We might, therefore, from such considera- 

 tions expect to find abundant traces of floods and inundations 

 over all the low grounds of Europe to which the swollen rivers 

 could find access. M. E. Collomb has made some interesting 

 calculations which serve to give one some faint idea of the 

 volume of water discharged from the glaciers of the Ice Age. 1 

 These calculations are based upon the observations of MM. 

 Dolfus and Desor on the Aar glacier in 1844 and 1854. 2 These 

 glacialists found that the amount of water discharged from this 

 glacier between 20th July and 4th August averaged 1,278,738 

 cubic metres daily — the minimum being 780,000 cubic metres, 

 and the maximum 2,100,000 cubic metres. The area occupied 

 by the glacier is estimated at 52 square kilometres. How, 

 supposing that the old glacier of the Rhone (the area of which 



1 Comptes Eendus de VAcad. des Sciences (1868), t. lxvii. p. 668 ; Cosmos, t. 

 iii. (1868) p. 407. 2 Agassiz : Nouvelles fitudes sur les Glaciers, p. 370. 



