THE SOUTHERX COMPLEX. 10^ 



of calcite. They are of a iiiottliMl dark green color, and are more liiuhly 

 altered near the juuctiou with the overlyiug rocks than farther to the south- 

 ward. They eaii hardly be said to have any true strike and dip, hut the 

 fibers of the schist abut almost perpendicularly against the slates of the 

 Penokee series, which here as usual dip northward. In thin sections these 

 rocks are much altered, but they can perhaps best l)e named chloritic and 

 hornlilendic gneisses. A groundmass is always present, which consists of 

 finely crystalline quartz, partly decomposed tabular crystals of feldspar, 

 and areas of chlorite, with kaolin, epidote, sericite, and hornblende. Con- 

 tained in this groundmass are larger complex and simple areas of quartz, 

 many crystals of feldspar, including both orthoclase and plagioclase. Some 

 of the latter are of large size. They often have roundish outlines, and 

 include near their exteriors chlorite and magnetite. IMagnetite in numerous 

 crystals of small size, and calcite in large areas are contained as late formed 

 secondary minerals, particularly in that pai't of the exposure near the over- 

 lying sei'ies. The appearance of these rocks is such as to suggest highly 

 altered silicified porphyritic basic eiiq^tives ; but ii' they were porphyrites, 

 the series of alterations through which they have gone has been of a very 

 complicated character. 



The exposures between these last described and the West Branch of the 

 Montreal, although spax'se, are more numerous than anywhere else in the 

 area. They are essentially all of one class of rock — crystalline horn- 

 blende-gneisses, although in one or two specimens the feldspar is scant and 

 these rocks might technically be called schists. Macroscopically the rocks 

 are all dark green, fine grained, compact, yet finely schistose rocks. Their 

 schistose structure is so close that in the field no proper strike or dip is in 

 general obtainable. When examined in thin section they are seen to be as 

 completely crystalline schists as any rock can possibly be. llieir back- 

 grounds are generally in about equal quantity finely crystalline quai-tz ;ind 

 feldspar, although each in certain sections becomes preponderant. The two 

 minerals intricately interlock, both with each other and with themselves. 

 In a majority of the sections in the background are larger grains of quartz 

 and feldspar which have a roundish a})j)earance. This feature is particu- 

 larly characteristic of the quartz, although in each case the exteriors of the 



