654 RECORD OF MEETINGS OF THE 



As soon, however, as we deal with the open-textured frag- 

 mental sediments and volcanic tuffs and breccias the permea- 

 bility is so enhanced as to make their leaching a comparatively 

 simple matter. Yet, so far as the available data go, they are 

 poor in the metals or else are open to the suspicion of secondary 

 impregnation. They certainly have been seldom, if ever, 

 selected by students of mining regions as the probable source 

 of the metals in the veins. 



Should the above objections to the efficiency of the meteoric 

 waters seem to be well established, or at least to have weight, 

 it follows that the arena where they are most, if not chiefly, 

 effective is the vadose region, between the surface and the level 

 of the ground-water. Undoubtedly from this section they take 

 the metals into solution and carry them down. But it is equally 

 true that they lose a large part of this burden, especially in the 

 case of copper, lead, and zinc, at or near the level of the ground- 

 water and are particularly efficient in the secondary enrichment 

 of already formed but comparatively lean ore-bodies. 



Let us now turn to the magmatic waters. That the floods of 

 lava which reach the surface are heavily charged with them, 

 there is no doubt. So heavily charged are they that Professor 

 Edouard Suess, of Vienna, and our fellow-member Professor 

 Robert T. Hill, of New York, have seen reason for the conclu- 

 sion that even the oceanic waters have in the earlier stages of 

 the earth's history been derived from volcanoes rather than, 

 in accordance with the old belief, volcanoes derive their steam 

 from downward percolating sea-water. From vents like Mont 

 Pelee, which in periods of explosive outbreaks yield no molten 

 lava, the vapors rise in such volume that cubic miles become 

 our standards of measurement. 



There is no reason to believe that many of the igneous rocks 

 which do not reach the surface are any less rich, and when they 

 rise so near to the upper world that their emissions may attain 

 the surface, we must assign to the resulting waters a very 

 important part in the underground economy. 



This general question has attracted more attention in Europe 

 in recent years as regards hot springs than in America. So 

 many health resorts and watering places are located upon them 



