The Structure of the Atlantic : 21 



America, the long sloping shoulder of South America which termi- 

 nates in Cape San Roque and the eastern shore of South America to 

 the Horn where the continental bulwarks of the Atlantic terminate. 



South of Cape Horn and south of the Cape of Good Hope the 

 geographers supply a somewhat arbitrary limit to the Atlantic. South 

 of the Horn the Atlantic is separated from the Pacific by an imagi- 

 nary line which is the shortest one that can be drawn from the Cape 

 in longitude 70° west to the South Shetland Islands. This line is less 

 than 800 miles in length and is not entirely arbitrary for there is an 

 underwater ridge which joins South America with the Antarctic 

 continent. South of Cape Horn the line runs at 20° east until it 

 reaches the Antarctic continent, and the shores of Antarctica form 

 the extreme southern margin of the Atlantic Ocean. Thus six conti- 

 nents lend a part of their shores to form the bulwarks of land that 

 almost completely surround our ocean. 



This physical structure quite justifies the designation of the Atlan- 

 tic as the Mediterranean Ocean. 



Barents Sea, the Greenland Sea, the Norwegian Sea make up very 

 broad channels between the Arctic Sea and the Atlantic proper. The 

 channels between northern Greenland and Ellesmere Island are ex- 

 tremely narrow and the channels through the Canadian Arctic Islands 

 are many and narrow. In the Atlantic proper the S-shaped effect is 

 created by a western indentation of the east. Within this basin of land 

 lie the many and diverse bodies of water that together make the com- 

 plex Atlantic Ocean. To name and describe all the waters of the 

 Atlantic is fortunately not required here for it would be a long task. 

 It is interesting, however, to recall the main features of this Atlantic, 

 noting how varied is their character and how wide is their extent 

 about the earth. 



It will simplify matters if we first look at the Atlantic as it might 

 be seen from the air or as it does appear on a globe. Then what we 

 later see below the surface will be more easily understood. 



Evidently people expect every ocean to be round or oval or oblong 

 for they so often express surprise when they come face to face with 

 the real but highly irregular shape of the Adantic. It is always help- 

 ful to remember that the main body of the Atlantic has the general 

 shape of the letter S and even recent technical writers on the ocean 

 have found it useful to refer to this shape. It helps the accuracy of 

 our picture if we add that the S is rather broad and straight, but the 

 double curve is clearly there. Also while the letter is fairly shaped in 

 the upper or northern portion of the Atlantic, for here the continents 



