24 GEOLOGY AND HISTORY 



or ordinary land quadrupeds, but all are extinct, and 

 nearly all belong to extinct genera. In the miocene 

 there are many living genera, but no species that 

 survive to the present time. The pliocene begins to 

 show a few living species, and these are dominant in 

 the succeeding pleistocene. 



These several stages of the cenozoic were also 

 characterised by great vicissitudes of geography and 

 climate. In the early and middle portions of the 

 eocene, much of the land of the northern hemisphere 

 was under the sea or in the state of swamps and 

 marshes, and there seems to have been a very mild 

 and equable climate, insomuch that plants now 

 limited to warm temperate regions could flourish in 

 Greenland. It is further to be observed that regions 

 such as Mesopotamia, Syria and Egypt, which are 

 known to us historically as among the earliest abodes 

 of man, were at this time under the ocean, as were 

 also rocks that now appear at great elevations in the 

 highest mountains of Europe and Asia. For example, 

 the limertones through which the Nile has cut its 

 valley are marine beds of eocene age, and beds of 

 the same period holding marine remains occur at an 

 elevation of 16,000 feet in the Himalayan region. 



In the miocene the amount of land was somewhat 

 greater, though large areas of the continents were 

 still under the sea, and the climate was still mild, but 

 for reasons to be stated in the sequel it is not likely 

 that man inhabited the warm continents of this age. 

 The pliocene inaugurates what has been termed a 



