30 : The Atlantic 



run from the West European basin in the north to the Antarctic 

 basin in the south. 



Here we might round the Mid-Atlantic Ridge and coming up the 

 west side of the Atlantic we would travel over another ten basins 

 from the South Antilles basin up to the Labrador basin with a detour 

 into the Caribbean basin and Gulf. 



Thinking about this general structure of the Atlantic raises an 

 interesting point. It would seem natural to look for the deepest por- 

 tions of the ocean far away from the continental shelves and some- 

 where toward the bottom center of the great open ocean spaces. It is 

 always a bit of a surprise to find that they are in all cases close to 

 land and usually close to some curving chain of volcanic islands. 

 They are deep and they may have a considerable length particularly 

 in the Pacific but they are never wide and thus deserve the descrip- 

 tion "trench." 



The trenches should probably not be thought of as the deep parts 

 of an ordinary ocean basin but rather as a special feature of the under- 

 water landscape. Studying bathymetric charts and submarine profiles 

 it is natural to think of them as mountains in reverse or upside-down 

 mountain chains. Undoubtedly they are an evidence of some funda- 

 mental and long-established weakness in the basic shell of the earth. 

 Here the basic tectonic forces that crinkled the mountains and islands 

 upward at the same time crumpled the trenches downward. 



There is such a trench close to the north shore of the island of 

 Puerto Rico, a sort of sword cut in the bottom of the sea. Here the 

 Atlantic reaches its greatest depth of 8,750 meters or about 28,000 

 feet. Not far away and even more closely associated with the land is 

 another slot between Jamaica and the southeast coast of Cuba. This 

 is known as the Cayman Trench and reaches a depth of 7,200 meters 

 or 23,748 feet. 



How deep is the ocean? From the point of view of imaginative 

 writing of poetry or of philosophy it has been very useful to be able 

 to refer to the ocean as a realm of unknown mystery and great depth. 

 It has been an area of useful comparisons against which man could 

 express or extend his knowledge and his feelings. Long before and 

 long after Moby Dick the ocean has been set up as one of the per- 

 petual challenges of the human spirit. 



What has been a gain to poetry has, however, been a distinct loss 

 to science. From a scientific point of view, one of the most important 

 things to say about the Atlantic or any other ocean is that it is exces- 

 sively shallow. The scientist in his own work no doubt recognizes the 



