254 H. L. FAIRCH1LD GEOLOGY UNDER PLANETESIMAL HYPOTHESIS 



phenomena is a very striking and important fact, although generalry 

 ignored. It illustrates the repressing effect of a wrong theory when once 

 established. 



It will be seen that under the new hypothesis the geologic processes 

 are not made more simple, but instead are given greater complexity. 

 The hypogene forces are brought into present intimate connection with 

 the epigene agencies. In other words, to the complex processes opera- 

 tive on the surface of the globe, there is added a widely distributed and 

 presently active volcanism. This added complexity is only what should 

 be expected in the growth of any branch of earth science, even if not 

 wholly welcome. 



Genesis of metalliferous Deposits 



The commonly accepted explanation for the deposition of most vein 

 ores is by the work of heated ascending waters or other vapors. Under 

 the old view the water is meteoric and is made to descend against the 

 same forces that cause it to rise. The new view simplifies the process 

 by regarding the vapors as originally resident within the depths of the 

 earth, and seeking escape from the rising pressure and heat. The for- 

 mation of ore bodies is to be regarded as a part of the general process 

 of expulsion of the soluble and vaporizable materials from the earth's 

 interior by heat and pressure. 



Origin of Gypsum and Salt Deposits 



The suggestions under this topic are offered tentatively and as illus- 

 trating the radically different viewpoint of the new geology. 



The old theory holds that the sodium chloride has been produced as 

 a secondary product, resulting from decay of sodium-bearing minerals 

 and reaction with chlorides, except to the extent that it was contained 

 in the primal vapory envelopes of the molten globe. The ocean is thus 

 made the immediate source of all the sodium chloride, and the deposits 

 of rock-salt are supposed to be produced directly by evaporation of sea 

 water or derived indirectly from the ocean through diffusion in marine 

 sediments and reconcentration in salt lakes. 



Under the new hypothesis the salt and gypsum or. their constituents 

 are indigenous to the earth's mass, and at least in part are derived, like 

 the ocean itself, from the interior of the earth. They are certainly con- 

 tained in volcanic emanations, and doubtless may have the same source; 

 but we may venture another step in our theorizing, and question whether 

 some saline deposits may not be accumulated directly by the eruptive 

 processes. 



