EARTHQUAKES 



513 



Thus a spray of hot water is intermittently ejected from the flask 

 as long as heating continues. We have here an action which re- 

 sembles that of a geyser. 



The outpouring hot water brings up with it dissolved 

 rock and as the spray falls back and cools, this is deposited, 

 forming craters of singular shape and grotesque beauty. 

 On looking into these craters a smoothly lined, irregular, 

 crooked, tubelike open- 

 ing is seen to extend 

 down into the ground. 

 It is through this that 

 the water finds its way 

 to the surface. How long 

 these tubes are nobody 

 knows, but they must 

 reach to a point where 

 the heat is sufficient to 

 raise water to its boiling 

 point. This heat is prob- 

 ably due to hot sheets of 

 lava. 



When the water in the 

 tube is heated enough to 



make it boil under the pressure to which it is subjected, 

 steam forms and some of the water is pushed out over the 

 surface. This escape of water relieves some of the pressure, 

 and more of the water far down in the tube expands into 

 steam, thus throwing more water out. Huge indeed must 

 be the reservoir to which the tube in a geyser like the Giant 

 leads, to be able to pour out such a vast quantity of water. 



Earthquakes. In mountain regions which are young 

 or still growing, earthquakes are not uncommon. These 



FAULT LINE OF AN EARTHQUAKE 



