CHAPTER VI. 



DUST-MAKERS EARTHQUAKES AND VOLCANOES. 



How Sea and Land have changed Places The History of the Petrified 

 Firs Perpetual Motion- Subterranean Heat Earthquakes and Earth- 

 quake-waves Wear and Tear Volcanoes, their Ash and Dust Heaps 

 Double Work done by Earthquakes and Volcanoes Hot Springs 

 Mammoth Springs. 



WE referred in the last chapter to the possible rise 

 of the bed of the Atlantic (p. 7 6), at some future 

 period, above the waves, and we have now to see how this 

 might be brought about. 



It is a well-known fact that sea and land have many 

 times changed places, and that by far the greater part of 

 the rocks composing the earth's crust must, from their 

 character, have been formed under water. 



It has also been ascertained by careful observation 

 that, at the present time, Norway and Sweden are quietly 

 rising higher and higher out of the German Ocean, at the 

 rate of three feet in a century ; and on the eastern coast of 

 South America there are large beds of shells which have been 

 raised, some a few feet only, others as many as three or 

 four hundred feet above the sea, in what geologists would 

 call " quite modern times ; " while at Santa Cruz a rise 

 of at least 1,400 feet has taken place since the time when 

 the great boulders with which the plains are dotted were 

 dropped by glaciers or icebergs. 



