Contents 



soft rocks are cut away from hard rocks. At one 

 coast the sea may encroach, at another it may retire. 

 Ocean currents are mainly the creation of prevailing 

 winds and of differences in density of water due to 

 variations of temperature. The sea as a disperser 

 of seeds, nuts, and woods 153 



HUXLEY, THOMAS H. 



EARTHQUAKES AND VOLCANOES 



In time the earth would be totally submerged by the 

 seas were not compensatory forces at work. An 

 earthquake in 1835 lifted a vast area of South America. 

 Earthquakes are probably confined to within thirty 

 miles of the earth's surface. Earthquakes are at 

 times accompanied by volcanic eruptions. Volcanic 

 particles are usually found on ocean floors. Vesuvius, 

 A. D. 79, overwhelmed Pompeii and Herculaneum. 

 Subterranean volcanoes sometimes create islands. 

 The increasing temperature of the earth as we descend 

 from the surface 171 



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