616 THE JOURNAL OF GEOLOGY. 



could possibly exist without its presence having been revealed 

 and its course traced, with all the widespread mining and explor- 

 ing which has been conducted in this region during the past 

 seventy years. Neither can one see how the solutions could 

 traverse the intervening great thicknesses of water-soaked sand- 

 stone without becoming diffused, in great part at least. The fail- 

 ure to find such a passage and the absence of the ores in the beds 

 assumed to have been traversed, though evidence of a negative 

 character is so strong that it becomes of almost positive value 

 in support of the theory of lateral segregation. 



Dr. Jenney, in support of his position, recognizes systems of 

 fault fissures in the ore districts of both south-western and 

 south-eastern Missouri, which cross each other in different direc- 

 tions ; these, he considers, served as channels for the metal bear- 

 ing solutions, and the association of the fissures with the ore 

 bodies he adduces as evidence of such derivation. The deposits 

 of the south-western portion of the state occur almost exclusively 

 in the Mississippian or Lower Carboniferous limestone. Cross 

 fissures or fault fissures in the rocks, if they exist, are not very 

 apparent. The strata are undoubtedly very much shattered in 

 certain limited areas, and have been subjected to extensive subter- 

 ranean erosion and corrosion and great silicification. Of a sys- 

 tem of extensive or considerable faults, recent stratigraphic work 

 in this region has, however, revealed nothing. 



In the Cambrian limestones of the eastern part of the state 

 the conditions are somewhat different. Crevices and fissures are 

 there plainly developed, and evidence of considerable faulting 

 is indubitable. In Franklin County such vertical crevices have 

 supplied large quantities of ore. In that portion of the south- 

 east to which reference is especially made, however, and which 

 has produced by far the bulk of the lead, the crevices, whether 

 marking faults or not, are of insignificant dimensions, and the 

 experience has been that they contained themselves little or no 

 ore. On the contrary, the great ore masses consist of galena 

 disseminated through a thickness of the country rock, often of 

 fifty feet or more. At Bonne Terre a tract 1300 feet long bv 800 



