The Structure of the Atlantic : 25 



sea. The Mississippi River for example runs 120,000 cubic meters per 

 second. Even this exchange is for the most part confined to surface 

 waters. The bottom inflow is so small compared to the deep waters of 

 the Black Sea that renewal of water below ninety feet would take 

 2,500 years. Below 600 feet the Black Sea contains no oxygen at all but 

 much ill-smelling hydrogen sulphide. 



The Mediterranean proper, as we shall see, participates actively in 

 the life of the Atlantic. 



The westward extension of the Atlantic is the Caribbean-Gulf of 

 Mexico system. These two basins are now regarded as making up an 

 American Mediterranean. 



Small Mediterranean seas in the Atlantic system are the Baltic and 

 Hudson Bay, and the marginal seas are the well-known North Sea, 

 English Channel, Irish Sea and Gulf of St. Lawrence. 



The Atlantic system also contains one unique curiosity. The Sar- 

 gasso Sea is more — and less — than a legend. Even the oceanographer 

 still refers to the Sargasso Sea though it is only an area in the Atlan- 

 tic. It is a sea without earthly shores, a body of one kind of water sur- 

 rounded by walls of other kinds of water. 



How does this vast and complicated ocean system compare with 

 the other oceans? In absolute figures it is larger than the Indian 

 Ocean and much smaller than the Pacific. The area of the main Atlan- 

 tic rated in square kilometers is 82,441,000; the Indian is 73,443,000. 

 The main Pacific at 165,246,000 is almost twice the size of the Atlantic 

 in area. 



This is a statement in absolute size of the main oceans. However, 

 the interest of an ocean depends not so much on its absolute size as 

 on the supplementary waters and its relationship to the land and the 

 service it performs between continents. Here the Atlantic is in a spe- 

 cial position. The Indian has practically no adjacent seas, a mere 

 1,476,000 square kilometers; the vast Pacific 14,000,000 square kilome- 

 ters of adjacent seas; the Atlantic 24,022,000. 



The reach or extent of the Atlantic and its adjacent seas is also 

 interesting. In an east-to-west direction along a slightly bent line, say 

 such as would be followed by a ship sailing on Atlantic waters from 

 the Suez Canal to the Panama Canal, the Atlantic extends over 8,000 

 miles or the equivalent of one-third of the distance around the world 

 measured at the equator. 



In a north and south direction the axis of the Atlantic may be said 

 to lie along the 150th meridian east longitude and its extension the 



