Transactions . that it can reasonably be attri-buted to mineralizing solutions. Under these circumstances unsupported nuclei, while theycannot be regarded as proofs of the molecular nature of the pro-cess, approach so closely to absolute proof that they render thiscriterion of great service. This is the more important as suchstructures as this are often large, easily observed and not at alluncommon. Added force is given to this criterion when the replaced rockis a sediment by the conformity of the stratification in the isolatedma-ss with that of the country rock beyond the ore—showing thatthe
Transactions . that it can reasonably be attri-buted to mineralizing solutions. Under these circumstances unsupported nuclei, while theycannot be regarded as proofs of the molecular nature of the pro-cess, approach so closely to absolute proof that they render thiscriterion of great service. This is the more important as suchstructures as this are often large, easily observed and not at alluncommon. Added force is given to this criterion when the replaced rockis a sediment by the conformity of the stratification in the isolatedma-ss with that of the country rock beyond the ore—showing thatthe mass is in its original position and has not been moved bycrystal growth or any other cause during the formation of the is in fig. 30 page 45!). Fig. 37 shows the con-ditions which would probably occur in a filled cavern, wherepieces of country rock have fallen to the floor and where thestrata in them have all angles to those of the surrounding rock. Replacement Ore Bodies—IrvingA C 459. Fig. 36.—Diagrammatic sections of hypothetical ore body in limestonebeds with comnletely unsupported nuclei of original rock entirely enclo.«*edin ore. Stratification of the Islands shows that the limestone mas^^es havenot been removed from their original position. In the second case mentioned, that is, where the isolated massof unsupported rock is of a different nature from the surroundingrock, the comparatively resistant nature of the rock material hascaused it to remain either unaffected by mineralization or onlyslightly affected.
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