The Interior of the Earth 



the skin of a fruit when it withers; grooves and 

 furrows appear on it, some due to a slow bending 

 of the crust, others, when a local cause acts more 

 violently, to fractures, which produce faults 

 and dislocations in the solid mass. In this 

 manner internal and external forces act together, 

 and it is their joint action that slowly ages and 

 wrinkles what Suess calls so appropriately " the 

 face of the earth/' 



None of the numerous arguments advanced 

 in favour of the internal fluidity of the globe 

 appeal so forcibly to current opinion as the ex- 

 istence of volcanoes. Nothing could be more 

 natural than to treat these volcanoes as natural 

 vents of the central liquid. It would be in- 

 judicious to accept this explanation without 

 close examination and without a knowledge of 

 the objections it has provoked. 



The admission of the internal solidity of the 

 earth requires, in order to account for the 

 expulsion of molten material and the .enormous 

 liberation of heat which occur during eruptions, 

 the intervention of some source of energy. The 

 work due to the contraction of the globe has 



been thought sufficient ; it is supposed to produce 



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