186 FIRST YEAR COURSE IN GENERAL SCIENCE 



pressed, the coal is hard coal, anthracite. Through the 

 middle and western states the coal is soft; this is called 

 bituminous coal. 



Ores of iron, silver, gold, and lead are reckoned of inesti- 

 mable value to a country; but they would be of little use 

 without coal, which is used as a fuel in separating the metal 

 from the ore. 



COAL FIELDS IN 

 THE UNITED STATES 



FIG. $5. COAL FIELDS IN THE UNITED STATES 



1. The coal fields of the United States occupy about one sixth of the 

 area of the country (not including Alaska). 1. In which half of the coun- 

 try is the greater supply? 2. In how many states is coal found? 3. What 

 is the importance of its wide distribution? 



Petroleum is found in many regions where coal is inacces- 

 sible. It is used to some extent as fuel in locomotive engines 

 and steamships. 



208. Rock Making at Present. When it rains, the 

 water flows down the mountain slopes, making rills which 

 combine into torrents; these join and make larger streams 

 which finally reach the ocean. This running water is at 

 work wearing away the earth's crust and making valleys. 



