CHAPTER XII 

 CLIMATIC INFLUENCES OF BODIES OF WATER 



152. Importance of lakes and oceans. When we think of 

 the earth upon which we live, most of us are likely to think 

 of the broad continents of solid land upon which we have our 

 homes. But however important the land may be to us, it 

 is the smaller part of the earth, for about three fourths of the 

 surface of the globe is covered with water. These great bodies 

 of water, the oceans and lakes, are of much interest. The 

 oceans and interior waterways are highways of travel and 

 commerce, and they greatly affect the climate ; the lakes and 

 rivers are sources of supply for the water needed by cities, 

 and too often the rivers are the channels by which wastes are 

 carried away. A great body of water, such as the ocean or a 

 large lake, can scarcely fail to have an important influence 

 upon the lives of the people who live in the surrounding 

 country. This influence may extend far from the lake or 

 ocean and may affect many people. 



153. The Great Lakes. The oceans are the greatest and 

 most important bodies of water on the earth, but they are so 

 vast that our study may better begin with a smaller body, 

 such as one of the Great Lakes. These are among the most 

 important lakes of the world and are partly surrounded by 

 populous communities. After we have secured some definite 

 information regarding the influence of one lake upon the sur- 

 rounding communities, we should be able to apply this infor- 

 mation to the explanation of the effect which other great 

 bodies of water have had in directing the course of history, 

 and the influence which they now have upon the lives and 

 industries of men in various parts of the world. 



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