SUMMARY 107 



almost worthless, while the same soil near a city where 

 fertilizers can be easily procured and where early vege- 

 tables find a ready market is of great value. 



Different soils are adapted to different crops, and where 

 a soil, although not good for many crops, is adapted for 

 raising a crop which in its locality is valuable, the soil is 

 called good. Thus the soil in many parts of Florida, al- 

 though unsuited for raising most crops, is suited for 

 orange trees and early vegetables, and so is a good soil. 

 The stony soil in certain of the orange regions of Califor- 

 nia would be an exceedingly poor soil for most crops, but 

 it is good for oranges and therefore it is most valuable. 



Summary. Only a little more than a quarter of the 

 earth's surface is land, and only a little over a twentieth 

 of this land belongs to the United States. Though there 

 are depths in the ocean greater than our highest moun- 

 tains, most sea animals live near the surface, while land 

 animals are distributed -over hills and valleys. This gives 

 greater variety to life on land. 



Water is simply a compound of oxygen and hydrogen. 

 It has many valuable and interesting properties : it is prac- 

 tically incompressible; it is the greatest dissolver of sub- 

 stances that there is; it evaporates readily, giving us rain, 

 and, when put under pressure, our steam power; it has 

 great power of taking up heat, thus regulating the climate 

 of the land near which large bodies of it lie. 



The land is made up of various animal, mineral and 

 vegetable substances. But four fifths of it consists of 

 sedimentary rocks, that is, those that were deposited by 

 water, as distinguished from igneous or rocks formed from 

 melted materials within the earth, and metamorphic or 

 rocks that have been changed from sedimentary or igneous 

 rocks. 



