398 



FIRST YEAR SCIENCE 



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- 



PlNE APPLES. 



A valuable crop of the southern coastal plain. 



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

 near the coast are Norfolk, Wilmington, Charleston, 

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

 delphia, Richmond, Columbia and Augusta. 



Coastal plains furnish a most suitable place for the 

 boring of artesian wells. As the strata are diversified in 

 structure and all dip gently toward the sea, porous strata 

 inclosed above and below by impervious strata are readily 

 found. When the upper of these are tapped, water is forced 

 by hydraulic pressure to a height nearly equal to the 



