60 Dr J. W. Dawson on the Antiquity of Man. 



reason to believe in a considerable and rapid decadence at 

 the end of the Post-pliocene and beginning of the recent 

 period. One cause which may be assigned is change of 

 climate. The climate of Europe in the time of the mammoth 

 was very cold, as indicated by the evidence of glaciers, and 

 other forms of ice action, and by the presence of the musk 

 ox. No doubt the extinction of this creature, and of the 

 mammoth and tichorhine rhinoceros as well, would fol- 

 low from the amelioration in this respect as the recent period 

 approached. This change of climate depended on geographi- 

 cal changes, modifying the distribution of land and water, 

 and the direction of ocean currents. A subsidence in Cen- 

 tral America or in Florida might restore the climate of the 

 mammoth by altering the course of the Gulf-stream ;• and 

 an elevation of land in these regions may have introduced 

 the climate of the recent period. There is abundant evi- 

 dence that much subsidence and elevation did occur while 

 these changes in organic life were in progress ; and these 

 may, more directly, by the submergence or elevation of large 

 areas in Europe itself, have tended to extinguish species, or 

 introduce them from other regions. All these points being 

 granted, and abundant evidence of them will be found given 

 by Sir C. Lyell, it remains to ask, can we convert the period 

 required for these changes into solar years ? There is but 

 one way of doing this in consistency with the principles of 

 modern geology, and this is to ascertain how long a time 

 would be occupied by agencies now in operation in effecting 

 the changes of elevation, subsidence, erosion, and deposit, 

 observed. Eeasoning on this principle, it is plain that a 

 vast lapse of time will be required, and that we may place 

 the earliest men and the latest mammoths at an almost in- 

 credible distance before the oldest historical monuments of 

 the human race. 



But can we assume any given rate for such changes ? 

 Not certainly till all the causes which may have influenced 

 them can be ascertained and weighed. We have only 

 recently learned that Scotland has risen 25 feet in 1700 

 years ; but we do not know that this elevation has been 

 uniform and continuous. There is another older sea-level at 

 44 feet above the present coast ; and there is a still higher 



