NOVKMBEE 15, 1901.] 



SCIENCE. 



lil 



how the metal got there, and how it was 

 deposited. 



I shall not attempt to give all the evi- 

 dence that the metallic ores and gangue are 

 deposited by underground waters ; but I 

 wish to call attention to certain structures 

 of veins which seem to favor this view. 

 [A.t this point a number of lantern slides 

 w.ere used, illustrating the following state- 

 ments.] 



A massive rock may be produced by di- 

 rect igneous agencies ; sediments are ar- 

 ranged in strata and beds. But material 

 showing a comb structure — or, as Posepny 

 calls it, crustification — and the filling about 

 particles of rock, is usually produced by 

 underground water. No agent other than 

 water can penetrate between the grains 

 throughout a sandstone formation, or a 

 conglomerate formation such as that of the 

 Calumet and Heckla. or between the frag- 

 ments of a great tuflf formation such as 

 that of the San Juan district of Colorado, 

 and deposit material so as to transform 

 them to hard rocks by cementing the 

 particles. Many cracks and crevices, 

 great and small, form in the rocks by the 

 deformation to which they are subjected. 

 Igneous material can intrude the rocks in 

 a most intricate fashion and occupy these 

 openings ; yet in the great majority of in- 

 stances the extremely iutimate introdaction 

 of material is accounted for by transporta- 

 tion and deposition of material by under- 

 ground waters. Those in this audience 

 familiar with Colorado ore deposits know 

 that many of the valuable minerals are in 

 veins, many of them narrow, or between 

 very small fragments within the rocks. 

 Not only do the ores occur in the larger 

 openings, but they frequently occur for 

 some distance from the veins in the ex- 

 tremely minute, often subcapillary, open- 

 ings of the wall rocks, or even replacing 

 the individual particles of the wall rocks. 

 Bub farthar from the veins, if the metals are 



present at all, they are only in exceedingly 

 minute quantities. In the larger openings 

 and adjacent to these openings the values 

 are chiefly found. These facts are beau- 

 tifully illustrated at Cripple Creek. No 

 known agent except underground water is 

 capable of penetrating the very small, and 

 especially the subcapillary, openings, and 

 depositing material. 



My primary assumption is, therefore, that the 

 great majority of ores are deposited hy under- 

 ground waters at the places ivhere they are now 

 found. Nearly all that follows is confined to 

 this class of ores. Ores directly produced 

 by igneous processes, and those formed 

 by processes of sedimentation, are only in- 

 directly considered this evening. 



The second fundamental principle which 

 I shall try to develop is that the waters 

 derived the ores from the outer part of the 

 crust of the earth — the part which I have 

 called the zone of fracture. Even as late 

 as 1893, at the World's Fair Congress, at 

 Chicago, it was argued by Posepny that the 

 ores came from the barysphere, or heavy- 

 sphere, from well down within the earth ; 

 although even Posepny conceded that the 

 agent which transported and deposited the 

 metals at the places where they are now 

 found was underground water. Posepny's 

 theory of the derivation of the ores from 

 deep within the earth is a very attractive 

 one ; because, if it be true, the deeper a 

 mine, the richer an ore deposit is likely to 

 become. Indeed, it is the belief of 90 per 

 cent, or more of prospectors that if they 

 only could get deep enough, deposits of sur- 

 passing richness and magnitude would be 

 developed. But it seems to me that the 

 hypothesis that the ores are derived by the 

 underground waters from deep within the 

 earth has no foundation in fact. It is alike 

 opposed to the principles of physics and to 

 observations in the field. 



It must be remembered that gravity is a 

 gigantic force ever at work pulling toward 



