GEOLOGY OF FELCH MOUJ^TAIN RAjSTGE. . 383 



direction, we intersect the same series again in an inverted order, but retaining the 

 same dip, until we liave reached again a large belt of compact quartzite ledges in close 

 contiguity with granite or also diorite, as it may happen, which latter rocks then form 

 the surface rock of large areas ou the north side of the Pelch Mountain ore formation 

 (p. 33). 



The only satisfactoiy explanation which I can give of this repetition of the rock 

 beds in an inverted order is the suggestion of a folding of the beds and the overturn 

 of the fold by a pressure acting principally from the north side. If this is the case, 

 we would have to consider the light-colored quartzite next to the granite as the most 

 recent deposits and the dark, ore-bearing, banded quartz beds as the oldest, which 

 would bring the structure of the Felch .Mountain ore formation in perfect harmony 

 with that of the Quinnesec ore range (p. 34). 



. SECTIO?^ II. GEiSTBRAL, SKETCH OF THE GEOLOGY. 



The rocks of tlae Felch Mountain range extend from the Archean to 

 the early Paleozoic. The Paleozoic is represented by the Lake Superior 

 sandstone, of supposed Upper Cambrian age, and the overlying Calciferous 

 limestone. These formations were originally laid down over the upturned 

 edges of the older rocks in flat sheets or with low initial dips, and have not 

 since suffered relative displacement to any notable degree. As has already 

 been stated, subsequent erosion has to a great extent removed this over- 

 lying blanket and laid bare the older rocks, except for the covering of 

 recent glacial deposits. The Cambrian sandstone, and to a less extent the 

 Calciferous limestone, still, however, occupy considerable outlying areas, 

 detached from one another throughout most of the district, but gradually 

 coalescing beyond the eastern end, where they completely cover the older 

 rocks and limit all further geological study of these in that direction. 



The Paleozoic rocks will not be considered further at present. On the 

 detailed Felch Mountain map (PI. XLIX) their known outcrops are repre- 

 sented by appropriate symbols, but except in the larger areas, where they 

 so completely conceal the older rocks that the distribution of these can not 

 be determined, they are assumed not to be continuous, and to be non- 

 existent, and in this respect stand upon the same footing as the Pleistocene 

 glacial covering. 



The Archean, which is here made up of granites, granitic gneisses, and 

 variotis kinds of crystalline schists, is the basement group of the region. 

 The areas in which these rocks are now exposed at the surface represent 

 the cores of the larger ra-ches which were constructed over the whole region 

 by the early manifestations of mountain-building activity, and subsequently 



