204 THE PROBLEM OF THE METALLIFEROUS VEIlSrS. 



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

 sediments and volcanic tuffs and breccias the permeability 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 

 liave 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 eificiency 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 chiefl}^, 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 Avaters. That the floods of lava 

 which reach the surface are heavily charged with them there is no 

 doubt. So heavily charged are they that Prof. Edouard Suess, of 

 Vienna, and our fellow-member, Prof. Robert T. Hill, of Ncav York, 

 have seen reason for the conclusion 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 w^aters 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 that they 

 are very important foundations of local institutions and profitable 

 enterprises. Professor Suess, whom I have earlier cited, delivered an 

 address a few years ago at an anniversar}' celebration in Carlsbad, 

 Bohemia, in which he stated that Rosiwal, who had studied the Carls- 

 bad district, could not detect any agreement between the run of the 

 rainfall and the outflow of the springs, and that both the unvary- 

 ing composition and amount through wet seasons and dry were 

 opposed to a meteoric source. Water, therefore, from subterranean 



