THE GNEISSOID GKAXITES. 209 



THE GNEISSOID GRANITES. 



The o-ranife <aud granitoid gneiss of the Southern Complex, hke the 

 coiTesponding rocks of the northern area, are so intimately related to each 

 other that they must be regarded as different phases of the same rock. That 

 they are intrusives in the micaceous and hornblendic schists admits of no 

 doubt, as their dikes cut the latter rocks wherever found, and, as has already 

 beeii indicated, fragments of the schists are included in the gi-anite. 



The distribution of the rocks with respect to the schists has already 

 been described. No repetition of the description is necessary. 



PETROGRAPHICAL CHARACTER. 



Macroscopicai. — As comparcd with the granite of the Northern Complex, 

 that of the southern area is less highly colored. In the east pink varie- 

 ties predominate, but toward the west, more particularly in the Lake 

 Michigamme district, a very fresh white granite takes its place, to the 

 entire exclusion of the pink variety. Porphyritic facies are less common in 

 the southern rocks, and the foliated structure which is so pronounced in the 

 northern granite is very much less marked in these. Moreover, whereas 

 in the former rocks there is always more or less biotite, in the latter rocks 

 there are frequently no bisilicates present, except a little chlorite in small 

 flakes that may have been derived from plagioclase, and in a very few 

 cases laro-er masses of the same mineral that may have come from biotite. 

 In general character, however, the rocks of the two areas are the same. In 

 the ledge the rocks are white, gray, pink, or red, according to the color and 

 abundance of the orthoclase present, but the red varieties are rare, and when 

 they do occur their shade is less brilliant than that of the red granites of 

 the Northern Complex. 



The southern rocks are always moderately coarse grained, and usually 

 are schistose. Near its northern contact with the Algonkian the granite is 

 more schistose than elsewhere, although gneissoid phases occur throughout 

 the entire o-ranite area. In some places, notably south and southeast of 

 Palmer, the granites are cut by veins of soft, yellowish-gray, sericitic schist 

 that are believed to be mashed portions of the granite itself, and in other 



MON XX VIII U 



