SPECULAR OXIDE OF IRON. 

 27. 



95 



is rcpreseiiled as still in connection with the Potsdam sandstone and serpentine, but the beds 

 are tilted up to a greater angle than usual, a, is serpentine highly charged with quartz ; h, 

 h, sandstone, intimately mixed with the peroxide of iron, with which also there are rich 

 masses of ore. 



Before leaving the phenomena presented in the masses of specular ore, I will give two ad- 

 ditional diagrams, in which some diversity may still farther be seen. Thus, the diagram fig. 

 .28, shows the position of a lean red ore at Fowler. 



a, Potsdam sandstone ; 6, Red ore, with serpentine ; c, Gneiss. 



The ore at this locality is a red rock, apparently stratified, lymg between layers of gneiss, 

 over which the sandstone partially projects. The mass of ore is not, therefore, interposed 

 simply between the sandstone and gneiss ; or if an interposition exists, it is to be regarded as 

 accidental, and not a true geological position. 



But to illustrate more satisfactorily the true geological position, I will introduce a diagram 

 taken from the Tate and Policy beds in Hermon, (fig. 29,) the Potsdam sandstone being 

 absent. 



a, Serpentine ; 6, Tate bed ; c, Policy bed ; d, Gneiss. 



If now we imagine those beds to have been overlaid by sandstone at the time of the erup- 

 tion of the ore, accompanied by serpentine, we can conceive that it would have penetrated 

 into the lower layers, and have presented phenomena precisely, similar to what we now see 

 at the Parish bed, and others in Theresa ; and a partial disclosure of the mass would convey 



