548 LIFE AS RELATED TO PHYSICAL CONDITIONS 



from the harder rock of the old land to the softer material 

 of the coastal plain. The softer material is worn away more 

 easily than the hard material, and falls or rapids are pro- 

 duced suitable for water power. A glance at a map of 

 the southeastern United States will show that the princi- 

 pal cities lie in line nearly parallel to the coast. Of those 



PINEAPPLES 



near the coast are Norfolk, Wilmington, Charleston, Sa- 

 vannah, Jacksonville; at the fall line, Trenton, Phila- 

 delphia, Richmond, Columbia, and Augusta. 



Advantages of Harbors. The importance to mankind 

 of good harbors cannot be overestimated. The latest and 

 greatest of all wars has especially emphasized this. Thou- 

 sands and thousands of men have been sacrificed in efforts 

 to obtain or to defend harbors. 



No civilized country by its own products can supply all the 

 wants of its inhabitants. Since earliest times man has been 



