MINERAL VEINS AND INTRUSIVE IGNEOUS MASSES 331 



mote coastline, may upset the equilibrium of the crust, may initiate the 

 slow lateral and upward transfer of rocks, and may produce the ultimate 

 igneous intrusion with all its corollaries. 



Relations to limiting Depth and Conclusion 



The 71-mile limit of isostatic equilibrium, or any similar and more 

 accurately established limit, will then give us a fairly accurate conception 

 of the depth where these changes initiate and a much more sharply de- 

 fined range for somewhat speculative reasoning than we gain in any other 

 way. But in connection with these matters I feel myself on much less 

 stable ground than when speaking of coal basins and oil domes and am 

 driven to ask questions rather than answer them. 



