78 THE WORLD'S LUMBER ROOM. 



On the western coast of America the evidence as to 

 the way in which sea and land have changed places is even 

 more striking, and shows that the vast mountain chain, 

 variously called the Cordillera, Andes, and Rocky Moun- 

 tains, which apparently stretches in an unbroken line from 

 Tierra del Fuego to the Arctic Circle, with pinnacles here 

 and there reaching a height of 20,000 feet, has risen and 

 sunk again certainly once, and almost certainly twice, in 

 the course of its history. 



In the Uspallata range, which is separated by a narrow 

 plain from the main mass of the Cordillera, there stands 

 a group of snowy-white columns, a few feet high, which 

 have a weird, ghostly look about them, and are evidently 

 the trunks of trees which have been petrified and con- 

 verted, some into flint, and others into coarsely-crystallised 

 spar. Now, these stone fir-trees have had a wonderful 

 history. They must, of course, have grown upon dry land, 

 but below them are several thousand feet of rock, which 

 could have been formed only under water; therefore the 

 land hereabouts must gradually have sunk lower and lower, 

 until it was many thousand feet below the .surface of the 

 sea. Then, when these new beds had been formed, it rose 

 again, and when the soil had been prepared for them, a 

 beautiful group of trees sprang up and flourished on the 

 shore of the Atlantic, which then washed the foot of the 

 mountains, though it is now 700 miles away. The trees 

 grew to maturity, and then the land began to sink again ; 

 but this time it was let down to an enormous depth, much 

 greater than before, for the firs were buried under beds of 

 sediment as thick as those upon which they stood, and 



