88 THE MAIMJFETTE IltONl'.EAIIIXG DISTKICT. 



Xenr Lake ( 'oopcr "tlic([nartzit(' t'drnuirioii f'oriiis * * * the basal 

 girdle of a luucli Iiiii'licr iiKiiintaiii ]hh\\ of dioritic rocks, wliieh occupies 

 tlie central part of the al)Ove-uaiiie(l section; and here frequent opjxirtunities 

 are offered to sec tlie intimate connection existing between tlie two groups, 

 linked together bv uninterrupted succession, and by gradations in the 

 change of tlie material of the rock l)eds"' (p. 46). Thus there is no 

 unconformitv l)etween the dioritie schists and the overlying quartzites, l)ut, 

 on the other hand, tlie rocks grade into eacli other; hence the diorites are 

 but little older tlian tlie quartzites. At the contact of the quartzites with 

 the granite the former rock is often altered. Its structure becomes schistose 

 and in composition it approaclies granite. The author quotes several 

 occurrences of this character as illustrations of "the transformation of 

 sedimentarv strata into a g-ranite-like rock" by exposure to contact with 

 eruptive granite. From tlie descri|)tions so carefully given it is clear that 

 the quartzite formation is folded into a large syuclinorium, composed of 

 numerous small syncdines and anticlines. The upper portion of the quartzite 

 is calcareous, as has been remarked. It comi)rises a series of siliceous 

 limestones and calcareous slates, which is called the "marble series." 



Conglomerates and breccias are often to be found associated with the 

 quartzites, especially when the latter are near granite. In the south half 

 of sec. 22, T. 47 N., R. 26 W., certain hills are "composed of a very coarse 

 granite breccia, inclosing blocks of large size, several feet in diameter, 

 cemented together bv an arenaceous and cliloritic interstitial mass of a lami- 

 nated, e^adently sedimentary structure, whicli exhibits itself plainly in some 

 portions of the rock, in which the rock fragments are more thinly scattei-ed 

 through the cementing groundmass. In certain portions of these knobs the 

 granite appears in solid masses, too large to be taken for fragments pertain- 

 ing to the breccia which fact induces me to suggest the nucleus of all these 

 hills to be a sidid granite mass, whose shattered surface portions are rece- 

 mented on the spot by sedimentary d(5bris washed into the interstices" 

 (p. 62). A little farther south in the same section are other conglomerates, 

 whose "inclosed waterworn grains are in part granite, in part slate frag- 

 ments." Near the southwest corner of the section are other congloraei'ates, 

 whose matrix is a slate and whose pebbles are waterworn granites. In 



