SUMMARY AND CONCLUSIONS. 1243 



deposition of ores must be interpreted in the lig-ht of the general principles 

 of geology and especially of metamorphism. It is believed that when a 

 comprehensive study of various ore-bearing districts has been made from 

 this point of view a more satisfactory treatise upon ore deposits may be 

 written than has yet appeared. 



Such a study of ore deposits must be a difficult one, involving as it 

 does a working knowledge of stratigraphy, of physical geology in its 

 broadest and most intricate aspects, of petrology, including igneous, sedi- 

 mentary, and metamorphic rocks, of mineralogy, and of modern physical 

 chemistry. Undoubtedly many ore deposits will be found to be exceedingly 

 complex and not to come fully within the scope of the principles discussed. 

 So far as any ore deposit fails to do this, it will give data upon which to 

 state a more nearly complete theory of ore deposits than that here proposed. 



