APPENDIX A. 155 



great, amounting to at least 3000 or 4000 feet. The higher beds are 

 prevalently of a dark grayish or greenish color, of argillaceous and 

 arenaceous composition, and of rather fine-grained slaty or flaggy 

 structure ; the lower are prevalently brown-colored sand rocks and 

 conglomerate. The metalliferous seams are above the brown sand- 

 rock and below the gray slaty upper division, and have a much wider 

 distribution than at first was supposed. The metal-bearing beds 

 have actually been found by explorers, from Ontonagon River for 

 30 miles westward, in every locality where denudations of the rock 

 beds could be seen ; and beyond all doubt the existence of the 

 metalliferous beds is not confined to this narrow district. On the 

 other hand, it is not to be expected that the beds are everywhere 

 charged with the metal in quantities which would pay for mining 

 it : some spots may be found unusually rich, others where the 

 same strata are barren of metal. 



The silver and the copper are generally found in two separate 

 seams which are only a few feet apart. The lowest seam is charged 

 with scales and granules of metallic silver. In the upper seam 

 the copper is found in similar fine scaly particles and granules, but 

 in much greater quantities than the silver. The silver was first dis- 

 covered in the rock beds exposed on Little Iron River, at the loca- 

 tion of the Scranton mine ; and, subsequently, in the valley of Big 

 Iron River, the same strata were discovered either in natural out- 

 crops or through test-pits, so that now a half dozen mining com- 

 panies are located along Iron River valley, within the distance of a 

 few miles. 



The general direction in the dip and strike of the strata is con- 

 formable with the strike and dip of the copper range, from north- 

 east to southwest, with northwestern dip ; but this direction is 

 only ideal, deducible from the geographical extension of the rock 

 belts, while in actual field observation we find the strata dipping and 

 striking in so many directions, that every locality is governed by its 

 own rules. We find the rock bent in short curves, in synclinal or anti- 

 clinal position, or that abrupt breaks in the continuity of the strata 

 cause considerable complications in the reciprocal position of the 

 layers. In examining the bed of Iron River for two miles upward 

 from its mouth, the strike and dip of the strata were found changing 

 continually, so that for a while, in ascending the river bed, we actual- 

 ly descended into lower and lower strata, and then, in the further 



