200 FIRST YEAR COURSE IN GENERAL SCIENCE 



parts of mountains, high plains, or the shores of a con- 

 tinent. Sea shells have been found imbedded in rocks in 

 the high Alps of Europe hundreds of miles away from the 

 sea. The upper Mississippi basin of North America is 

 underlaid with layers of coral-limestone rock. Ocean water 

 furnished mineral matter for the food of sea animals, and 

 the skeletons of these animals helped to make the land. The 

 ocean, then, not only furnishes food for man, but has been 

 the origin of large areas of land. 



221. The Dependence of Lands upon the Ocean. If 

 there were no oceans, the earth would be nearly useless to 

 man, for the lands would be deserts. Water from the sur- 

 face of the ocean is constantly evaporating and passing into 

 the air. Vapor-laden winds from the ocean pass over the 

 continents, the vapor condenses, and rain or snow falls. As 

 soon as rain water touches the earth, its journey back to 

 the ocean begins; and as it creeps slowly through the 

 ground, it brings dissolved minerals to plants, and fills 

 springs and lakes to provide man and beast with drink. 

 During the last stage of its return journey the water, now 

 become a river, furnishes power by which work is done by 

 machines, or by which electric currents are furnished for 

 light and power. 



222. Ocean Travel. Even before the days of the Vi- 

 kings, men ventured far from land over the seas in search of 

 food, wealth, and new countries. In the last four hundred 

 years, as a result of these ventures, North and South America 

 and Australia have been peopled by Europeans, and great 

 nations have become established. We may now travel com- 

 fortably for business, pleasure, or study, completely around 

 the world, over oceans which once confined people to the 

 continents on which they were born. Where continents ob- 

 structed an ocean journey, canals have been made, as at 

 Suez and Panama, so that goods may now be carried 

 without change from Boston to Japan by the western as 



