230 University of California Publications in Geology [Vol. 8 



It thus apears that Lindgren's criticism of the brief expression of 

 my views appearing in the review of Types of Ore Deposits 27 ' has not 

 overthrown the hypothesis which I there advanced ; nor has it weakened 

 my position, which is that much of the argument in favor of magmatie 

 waters applies equally well to the hypothesis of meteoric waters, that 

 the question of the origin of contact deposits is an open one and that 

 our students shotdd know it is open. 



KEMP'S CEITICISM 



Association of Ores with Fissures. — In a recent paper 26 Professor 

 J. F. Kemp, in referring to my suggestion that meteoric waters under 

 the influence of heat given off by mtrusives may be the agency whereby 

 the ores of contact zones are formed, states that : 



' ' In general, although not invariably, the formation of the silicates seems 

 to precede that of the magnetite and the sulfids, but they all are believed to 

 belong to one process. The sulfids are irregular in distribution and so far as 

 recorded descriptions go, they do not seem to be associated with faults or other 

 nourishing waterways through which they might have entered after the contact 

 effects had been produced. ' ' 



In reply to the part of this statement which I have italicized I call 

 Professor Kemp 's attention to the ores at Butte which occur in fissures, 

 to the ores at Bingham which occur either in fissures or associated with 

 fissures, to the fissure lodes at Morenci in the porphyry, to the ores 

 of Marysville in fissures, and to the ores at Matehuala, all of which 

 are ascribed to magmatie waters, that have reached the places of 

 deposition by ample waterways. If the presence of fissures is all that 

 is needed to negative the hypothesis of magmatie waters it surely fails 

 in many cases where it has been applied. But even if fissures and other- 

 nourishing waterways were lacking, the objection is singularly feeble, 

 for if the waters from the magma can make their way through the 

 rocks and promote chemical reactions, there is no reason that I can 

 imagine why the equally hot meteoric waters should not do the same. 

 The only other objection that Professor Kemp urges against the possi- 

 bility of meteoric waters doing the work which he ascribes to magmatie 

 waters is that "the well-nigh unanimous concensus of opinion of those 

 who have studied the zones has been that the metallic minerals go 

 along with the others in method of introduction" and "despite Pro- 



23 hOC. Cit. 



26 Notes on garnet zones on the contact of intrusive rocks and limestones, 

 Annual Meeting, Toronto, 1912. 



