This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1929 Excerpt: ...from them, in essentially the way Pumpelly had proposed. Finally, they concluded that the brines of the deep levels are probably the residues of the ancient ore-forming solutions, possibly mixed with meteoric water. The parts of these views of Van Hise, Leith, and Steidtmann that have to do with meteoric waters are discussed on page 120. The parts that deal with magmatic waters follow Smyth in large measure but go further in recognizing that the type of rock alteration contrasts entirely with that produced by weathering or by meteoric waters. If the magmatic waters came from the lava flows, there were presumably several periods of mineralization, as successive flows were in the proper condition to yield emanations. The presence of mineralized boulders of amygdaloid in what was considered immineralized conglomerate was thought to mean mineralization before conglomerate deposition and apparently strengthened the belief that the lavas rather than the intrusives were the source of the mineralizing solutions. Hore 30 appended to an excellent summary of previous literature on the district his own ideas as to the origin of the deposits. He concluded that the copper and the Keweenawan igneous rocks had a common source; that the copper is essentially a primary deposit from ascending solutions which followed the extrusion of lava so closely that the rocks were still hot, although they had already been fractured; that tilting and faulting followed copper deposition; that the copper replaced the rocks and was precipitated from chloride solutions by the reducing action of ferrous iron. These conclusions were well presented and accompanied by shrewd and pertinent observations on other features of the copper deposits. The conceptions introduced are discussed above. Woods ...
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