THE SOUTHERN COMPLEX. Ill 



the feldspar tliat tlie honiblemle does. Magnetite in small areas and 

 crystals is plentiful in some of the sections. It is scattered quite uniformly 

 throughout all the minerals as though it were the earliest present. The 

 secondary minerals — epidote, sericite and chlorite — are at times in quantity. 

 The character of these hornblende-schists and gneisses gives no certain 

 clew as to their origin. With almost equal plausibility, taking the rocks of 

 this area alone, a case could be made out for their derivation from trag- 

 meutal sediments or from eruptive rocks. 



At the West Branch of the Montreal a somewhat peculiar rock occurs. 

 In thin section chlorite in an almost solid mass composes a large part of the 

 sections. Calcite and quartz, with a little magnetite, are included in tliis 

 chlorite as subordinate constituents. Actinolite is the only remaining min- 

 eral of importance. When cut pei"})eiidicular to the vertical axis or approxi- 

 mately so, it shows crystal outlines, in which case its prismatic cleavage is 

 nicely developed. Wlien cut parallel to the vertical axis eacli individual of 

 actinolite terminates in many long needle-like jjoints, which penetrate deeply 

 into the chlorite. Sometimes the actinolite lilades are clustered into sheath- 

 like forms. The perfect freshness of this mineral and its dee}) penetration 

 of the chlorite indicate that the actinolite is of a secondary character. 



The Central granite. — The granitic area east and west of the Montreal 

 river is a large one, but it has not been sufficiently traversed to tind a great 

 number of exposures. The rocks are always coarse grained and are some- 

 times massive, although more often they have the structure of granitoid 

 gneisses or coarse gneisses with a well developed foliation. The rocks here 

 included vary greatly in their chemical composition, running from granites 



to gabbros. The three chief types of rock are the granites (including one 

 microgranite), the syenites, and the gabbros. 



The granites have their large development east of tlie ]\Iontreal river. 

 They vary in exposure from massive granites to granitoid gneisses ; in tex- 

 ture they are always moderately coai'se and evenly granular; in color the}" 

 vary from almost. white to deep flesh color. Feldspar is- usually the pre- 

 ponderating constituent, although both quartz and the iron-bearing silicates 

 are often abundant. (PI. w, Fig. 1.) Under the microscope these rocks 

 are found to be in almost every j)articular like those of the Western granite 



