

Ch. XIL] 



AND EXTREME OF COLD 



267 



oi 



According to the doctrine 



to cause an ocean three miles deep to replace any one 

 of the existing continents. It is quite essential to bear in 

 mind this remarkable feature in the physical geography of 

 the earth, when we are speculating on the cause of the per- 

 manence of a particular climate, or distribution of heat or 

 cold during a series of epochs, 

 of chances, it would not often happen that even one of the 

 polar regions would contain so much land as both of them do 

 at present, but great indeed would be the chances against the 

 simultaneous preponderance of such an abnormal quantity of 

 land, both in arctic and antarctic latitudes. 



The annexed maps will enable the reader to understand the 

 manner in which land, having the same proportion to the sea 



it now has, might be collected together in equatorial or 

 polar regions. Such extremes may never have occurred, but 

 we may safely conclude that there must sometimes have been 

 an approximation to them 



as 



in the course of those ages to 



which our geological records refer. A glance at these maps 

 will make it evident that in the present state of the globe we 

 are much nearer to the winter than to the summer of the 

 ' Annus magnus/ or great cycle of terrestrial climate. 







