158 LOWER PENINSULA. 



sand rock or conglomerate, and with a hanging wall of blue slaty 

 rock. 



A very interesting fault in the strata is observable in the river 

 bed, about fifty steps up stream from the Collins mine. 



At the mine the silver-bearing bed strikes diagonally across the 

 river, 25° east of north, with a dip south of east. An abrupt 

 break interrupts the strata then, and a belt of almost vertical 

 ledges of brown conglomeratic sandstones crosses the river bed in a 

 direction 25° south of west, with a dip northwestward, and on 

 the other side of this belt similar conglomeratic sand-rock ledges 

 come in contiguity to it, which strike in the direction of northwest 

 and dip northeast with moderate inclination. In the bed of Miner- 

 al River, east of Iron River, entirely similar exposures are observed. 

 A seam of sandy rock beds, which contain sometimes immense 

 quantities of fine scaly or granular metallic copper, is found quite 

 as uniformly distributed as the silver-bearing seam. It is found 

 only 6 or 8 feet above the argentiferous beds. 



The Nonesuch mine is opened in ^these cupriferous beds ; its 

 situation is in Town. 50, R. 43, Sees, i and 12. The strike of the for- 

 mation is there 50° east of north, dip south of east, at an angle of 

 30°. The hanging wall of the mine is formed by blue arenaceous 

 slates seen in a thickness of several hundred feet, exposed in the 

 bed of the creek. The ore bed is an argillaceous and partly con- 

 glomeratic, greenish-gray sand rock, densely crowded with fine 

 copper scales or coarser granules of that metal. Its thickness 

 is about 8 feet. Some few feet below the ore bed, which is natu- 

 rally exposed in the creek, another sand-rock seam is noticed which 

 can be identified with the argentiferous sand-rock seams of the 

 mines in Iron River. 



The same superposition of the two ore beds I have noticed in the 

 bed of Mineral River. At the base of the ore beds of the Nonesuch 

 location, the brown sand rock and conglomerate beds are well de- 

 nuded in the bed of the creek, in descending toward the stamp 

 works of the mine. 



The proportion of metallic copper mixed with this sand rock is 

 very great, fully as great as in the best picked specimens of the Cal- 

 umet and Heckla conglomerate, but the finely comminuted condi- 

 tion of the copper causes a great loss in the stamping and washing 

 of the rock. 



