Ch. XIIL] 



PERIOD 



2 8 i ) 



ice ever extended continuously over the whole space now 

 occupied by sea and land to about the 40th parallels of 

 latitude. 



may 



prevented the annihilation of many species of plants and 

 animals which would have perished, especially in the tropical 

 zone if they could not during the coldest phase have migrated 

 across the line into the opposite hemisphere. The number of 

 species both of plants and animals which have survived the 

 Glacial Period in temperate latitudes, is a fact warning us 

 not to exaggerate the intensity and range of the cold beyond 

 those limits which we are compelled to admit in order to 

 explain geological phenomena. 



M. Adhemar considered the antarctic ice to be so volumi- 

 nous as to draw towards it, by the force of gravitation, the 

 waters of the ocean in such a degree as to cause the submev- 



hemisphe 



Mr 



of submerg 



much 



The same 



-oil as a cause 

 in the Glacial 



Epoch, but with this difference, that he refers the excessive 

 accumulation of ice to the refrigerating effects of precession 



ft _ * * ^m m 



combined 



To do justice to this 

 question would lead me into too long a digression ; but 

 there can be no doubt that, if there was an epoch — the 



Miocene, for example 



remote in th< 

 o permanent 



even 



at the poles, and if this was succeeded by 



a long- 



period, when there were two ice-caps extending over the 

 north and south polar lands, varying perhaps from 2,000 

 to 5,000 feet in average' thickness, such piling up of ice 

 above the sea-level would affect that level in various ways 

 and the melting of a large part of the same, after the 



would, 

 former 



But in the 



present state of science, we cannot safely speculate on this 



_ * _ « A ^ _ _ _t » ft f* 1 "1 



from 



from 



decide how far the ice-cap of one hemisph 



VOL- I. 



u 



