436 



FIRST TEAR SCIENCE 



In mountain regions rich in ores, mining naturally be- 

 comes the chief industry, and here, if there were any 

 secluded native inhabitants, these have been replaced by 

 the energetic miners from distant places. The deep and 

 remote valleys and mountain sides have become the homes 

 of mining camps and cities. Railroads have been built 

 to these, overcoming almost impassable obstructions, and 



CRIPPLE CREEK. 

 The largest mining camp in the world. 



ore crushing and smelting works supply the places of the 

 mills and factories of the manufacturing cities. When the 

 ore fails, the army of workers moves on, and the city, 

 once thriving and booming, becomes suddenly simply an 

 aggregation of empty dwellings. 



208. Effect of Mountains on History. Not only have 

 mountains been retreats for the vanquished, but they have 

 been barriers against further conquest by the conquerors. 

 It is very difficult for an army to traverse a mountain 



