AVtc Hypothesis of Ilarth-Origin. — Fairchild. 107 
be expected in tlic 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 w^ater 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 formation 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 vmder this topic are offered tentatively 
and as illustrating the radically different viewpoint of the new 
geology. 
The old theory holds that the sodium chloride has been pro- 
duced 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. Thev are certainly contained 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. 
It is certain, being a matter of present observable process, 
that some salt and gypsum deposits are produced by evapor- 
ation of saline waters, and it is therefore a legitimate theory 
that all similar deposits have the same origin. But some salt 
deposits are so thick and pure and so localized that no satisfac- 
tory explanation has been given of the formative conditions 
