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FIRST YEAR SCIENCE 



If the water which comes to the spring has penetrated 



below the surface far 

 enough to get away from 

 the heating effect of the 

 sun, it will be compara- 

 tively cool when it again 

 emerges, and it will form 

 a cold spring. If, how- 

 ever, in the region where 

 the spring occurs the 

 rocks are hot at the 

 depth to which the 

 water penetrated before 

 it found a crack through 



A LIMESTONE CAVE. 



which it could come to 

 the surface of the land, 

 then it will become heated and will form a hot spring. 



MONTEZUMA'S WELL. 

 This famous water hole is due to the dissolving of the underlying rock layer. 



As the crust of the earth is in many places composed 

 of rocks in layers, the rain often falls upon the top of a 



