16 THE OCEAN FLOOR 



drift" propounded and worked out in great detail by the 

 Austrian scientist Alfred Wegener,"' although the fun- 

 damental idea had been launched a few years earlier 

 by the American Frank B. Taylor.'' According to this 

 theory the present continents are mere fragments of the 

 outermost shell of the earth's crust, supported by being 

 partly immersed in a deeper layer of higher specific 





Fig. 7. Map of the Oceans in the Eocene 



weight and greater plasticity. To these continental 

 blocks Wegener ascribed movements in both vertical 

 and horizontal directions. This idea of drifting con- 

 tinents, worked out in great detail by Wegener and his 

 followers, is supposed to explain the striking parallelism 

 between the continental borders on both sides of the 

 Atlantic Ocean, first emphasized by Taylor. Thus, the 

 Atlantic Ocean was taken to be a kind of rift between the 



