278 THE MAEQCTETTE lEOXBEARINa DISTEIOT. 



An exainiuatiou of the tliin .section.s enables one to discriminate with 

 great certainty between the schistose granites which have taken on the 

 character of kaolinic cpiartz-schists, and the conglomerates. In the most 

 mashed jjhases of the granite, the feldspars have been entirely decomposed, 

 the broken granitic qnartzes resting in a kaolinic, sericitic, and siliceous 

 background. In the conglomerates, while many of the complex fragmental 

 grains have a distinct granitic appearance and are much affected by dynamic 

 action, the waterworn character of some of them is distinct. Also the con- 

 glomerates have alternating layers of finer and coarser material, while the 

 lamina? of the granite ai-e all alike. Finally, the recomjjosed rock has 

 allowed more secondary iron oxide to enter than tlie granite. 



In the center of sec. 22 are a few outcrops of the Arehean basement, 

 which together form an oblong area. West of this area, making up the 

 larger part of a considerable ridge, are great outcrops of conglomerate. 

 The great bowlders and smaller fragments of g-ranite and gneiss are so 

 thickly set in a sparse matrix as to form a stucco. This congdomerate, as 

 seen upon the glaciated surftice, presents the most magnificent example of a 

 basal conglomerate known in the district (fig. 11, p. 259). At one place in 

 this congloinerate occurs a small exposure of the gneissoid granite which is 

 surrounded on all sides by the conglomerate. 



The fold here is again an isoclinal anticline, the strikes being about 

 northwest-southeast and the dips to the northeast. Also the fold is cross 

 folded, so that from the crest it plung-es to the northwest and to the south- 

 east. In going to the northeast or southwest from tlie center of the bluff 

 one passes to higher horizons, although the dips are continuously to the 

 northeast. The exposures to the southwest are more nearlv continuous, 

 and here the coarse conglomerate is seen to vary into fine conglomerate, 

 this into coarse feldspathic graywacke, and this into slate, there being, how- 

 ever, various interstratifications of these materials. The coarse feldspathic 

 graywacke — that is, the j^hase which is made up mainly of the constituent 

 minerals of the granite — takes on at times a gneissoid appearance which is 

 remarkably similar to that of the original gneissoid granite making the 

 ■center of sec. 22 (PI. X, fig. 1). In fact, at first they were not discriminated 

 in the field, and were regarded as the same. A study of the thin sections, 



