The Meaning of the Atlantic : 6i 



of the major class: the Magdalena, the Orinoco, the Amazon and the 

 La Plata system. 



The mere listing of river names is impressive. The impression can 

 be strengthened and left as a permanent part of the reader's mental 

 equipment if he will take the slight trouble of taking a pencil and 

 following on a globe or map of the world the headwaters and the 

 continental divides of all these rivers that by one route or another 

 pour their waters into the Atlantic Ocean. In Africa, for example, 

 the line runs well to the east so that there is a very short coastal 

 plane along the Indian Ocean and only one moderate-sized river, the 

 Zambesi. Continuing in this fashion through the other continents, it 

 will be seen that the mountain systems of the world for the most part 

 lie relatively close to the non-Atlantic side of all the continents. 



The rivers of China and of India, and on the American continent 

 the Columbia, the Sacramento and the Colorado represent the total 

 of the world's major non-Atlantic rivers. Half of the land mass of the 

 world is represented in the collective Atlantic drainage basin. 



Renewal: As soon as the sea receives the waters of the river it 

 commences their restoration and renewal. The muds and silts are 

 deposited as deltas, bars and shoals. On rising coasts these will per- 

 haps emerge again as shore and finally land. The waters themselves 

 are acted on by the tides and the waves. They are churned up, aer- 

 ated, nutritive substances consumed by the many marine creatures of 

 the shore, small particles attacked by the bacteria of the sea. The 

 Atlantic performs these services for the world's widest, most produc- 

 tive, richest, busiest river valleys and coastal plains. 



Storage: In this function as in that of renewal, the Atlantic per- 

 forms the service of storage for the same major continental areas. 



Temperature: We have noted already how the oceans are the de- 

 termining factor in the earth system of winds and weather. In the 

 matter of temperature they make the earth habitable to man. Here 

 their function is that of conservation and balance. Most of the sun- 

 light that the world receives falls upon water, and fortunately water 

 and moist air absorb heat more slowly and give it up more slowly 

 than land surfaces or dry air. 



The ocean and its related waters therefore serve as a temperature 

 balance wheel modifying the shift of temperature between day and 

 night and also from season to season. 



Were it not for the oceans and the moisture-laden atmosphere 

 which they create, we should be as badly oflF as our satellite the 

 moon. Here, without moisture and widiout atmosphere, the temper- 



