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Ch. VII.] 



OF IGNEOUS FORCES. 



119 



periods ; but if the subterranean residue after the withdrawal 

 of the heat be converted into crystalline or plutonic rock, the 



seem 



countless the ages required for its fusion and subsequent re- 



As the idea that all the granite in the earth's 



frigeration. 



siinultaneou 



of the planet, has now been universally abandoned ; so the 

 suggestion above adverted to, may put us 



on our guard 



i, namely, that 

 each large mass of granite was generated in a brief period of 



time. 



Modern writers indeed, of authority, seem more and more 

 agreed that in the case of granitic rocks, the passage from a 

 liquid or pasty to a solid and crystalline state 



mil 



extremely 



much insisted upon formerly 



line rocks, 



mica 



quartzite, 



and others were produced in the greatest abundance in the 



formation 



altogether in our own times, will be controverted in the next 



chapter. 



Gradual development of subterranean movements. — The ex- 

 treme violence of the subterranean forces in remote ages has 

 been often inferred from the facts that the older rocks are 



> fractured and dislocated than the newer. But what 

 other result could we have anticipated if the quantity of 



mor 



time 



must, in that case, multiply the derangement 



numerous 



in the ratio of their antiquity. Indeed the 



tions to the above rule which we find in nature, present at 



mi 



For the more ancient 



many 



horizontal, while in others much newer strata are curved and 



vertical. 



anom 



ular 



the volcanic and subterranean agency affect different parts of 

 the earth in succession, being often renewed again and again 

 in certain areas, while others remain during the whole time 

 at rest. 



