126 THK ^lARQUETTE IIION-BEAIMNG DISTRICT. 



Superior, Baninin, Hostciii, Spurr, Mirlii^aniiuc, and Kepiiblic mines, and 

 shows tliat in iuaii\- instances its stratifieation is unconformable with that 

 of the ores and jaspers in contact with it and below it. He publishes a 

 photograph of the contact at the Goodrich mine, which exhibits the layers 

 of the jasper abutting against the conglomerate, and the latter unconform- 

 ably upon tluim. Since this conglomerate, as well as other similar ones, 

 contains ore, chert, and jasper fragments in precisely the same conditit)n in 

 which they occur in the underlying formation, it is plain that the latter 

 had reached its present condition before the conglomerate was deposited. 

 There is thus evidently a large time break, repi-esented by this unconformity, 

 in the series of rock beds lying aljove the granites and schists and beneath 

 the Potsdam sandstone. In other words, the rock series heretofore known 

 as the Huronian in reality includes two series, one above and the other 

 below the conglomerates lying n\Hm the ore-bearing formation. 



Those [the rocks] upon the lower side of this break, in the exceedingly contorted 

 jasper, in the schistose character of its quartzites, and in the general assumption of a 

 semicrystalline character, show the evidence of profound dynamic action. In the 

 upper series, on the contrary, the folding has not been intense ; the fragmental charac- 

 ter of the slates and quartzites under the microscope is evident at a glance, and no 

 indication of great dynamic action is seen. While subsequent to the deposition of 

 the upper series the whole region has been subjected to a new folding, great enough 

 in places to give the later series a dip of 00° or 70°, as at the Goodrich, it has not 

 suffered since that time such intense dynamic movements as have produced the more 

 thoroughly crystalline and folded character of the earlier series. (P. 122.) 



These facts contirm the coirectness of the view that the two series 

 belong to fundamentally different geological epochs. 



In a footnote ^"an Hise refers to Wadsworth's anticipated objection to 

 this theory in view of the fact that the ores and jaspers are regarded by 

 him as eruptive, and states that this author's facts "indicate the eruptive 

 origin of the ore and jasper only if the schists are of sedimentary origin." 

 His own investigations show, however, that the Marquette iron-bearing 

 members " contain many schistose dikes, and also that in many cases the 

 massive greenstone knobs of the ^larquette region vary by imperceptible 

 stao-es into the schists associated with the iron ore and jasper. The schists 

 are then, in part at least, of eruptive origin. * » * This ^-iew reverses 



