THE TERTIARY PERIOD 



439 



is represented in the mountains of Cuba, Porto Rico, and 

 southern Mexico (Antillean system). (See Fig. 44.) These 

 ranges are less conspicuous than some of the mountains on 

 the land, only because they are largely submerged. The 

 highest peaks of Cuba rise more than twenty-five thousand 

 feet above the floor of the adjacent Caribbean Sea. In the 

 old world the eastward trending mountains, from the Pyre- 



FIG. 456. Geography of the world as it is thought to have been at a time 

 early in the Tertiary period. Note the continuous land in the northern 

 hemisphere, with isolated continents in the south. 



nees in Spain, through the Alps, Caucasus, and many other 

 ranges, to the Himalayas and far beyond, belong to this 

 great belt of Tertiary mountains. Hitherto most of these 

 regions had been beneath the sea; on the site of even the 

 great Himalayas there was, up to the early part of the Ter- 

 tiary period, a broad sea, not unlike the Mediterranean 

 (Fig. 456). In this sea limestone was being quietly formed. 

 But in the Tertiary disturbance these and all older rocks 



