 | Lake Superior Mining Institute - Copper mines and mining - 1902 - 156 pages
...district was first examined by the US Geological Survey this simple explanation was applied. But detailed study shows that other factors modify the circulation...of these modifying factors is the fracturing of the iron formation which has furnished numerous trunk channels for the circulation of underground waters.... | |
 | Rukard Hurd - Iron ores - 1911 - 186 pages
...the unequally eroded rock surface or at the surface of the irregular covering of glacial drift. * * * Further study shows that other factors modify the...of these modifying factors is the fracturing of the iron formation which has furnished numerous trunk channels for the circula*Leith, CK. a summary of... | |
 | Geology - 1906 - 918 pages
...say that the underground circulation has probably concentrated the ores along these broad synclines. When the district was first examined by the US Geological...trunkchannels formed by the fracturing of the iron-formation, and, white it has probably followed the fracture-openings along synclines to a greater extent than... | |
 | Digital images - 1909 - 822 pages
...unequally eroded rock surface or at the surface of the irregular covering of glacial drift. • » » Further study shows that other factors modify the...of these modifying factors is the fracturing of the iron formation which has furnished numerous trunk channels for the circulation of underground waters.... | |
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But detailed study shows that other factors modify the circulation of water and the localization of the ore and that these secondary factors may be locally dominant. The most important of these modifying factors is the fracturing of the iron formation... 