GEOLOGY OF THE BLUE MOUNTAIN QUADRANGLE 29 



weathering, the color change has affected the apparently fresh rock 

 to depths beyond the zone of observation. 



As regards texture and degree of foliated structure, the facies 

 of granite show practically the same kinds of variations as the 

 normal syenite already described. 



Mineralogically, the granite differs from the facies of the syenite 

 chiefly in the higher quartz content and more common occurrence 

 of microcline. Table 5 includes examples of the more common 

 variations of granite from different parts of the quadrangle. 



\^arious types of light to dark-gray Grenville gneisses occasionally 

 occur as distinct inclusions in the granite, but hmestone inclusions 

 were never noted. Where such inclusions are of sufficient abund- 

 ance to make up a considerable percentage of the mass, the rock 

 has been classed with the mixed gneisses (see below). The inclu- 

 sions are nearly always flattened and drawn out parallel to the 

 foliation of the granite almost exactly as in the case of the syenite 

 and granitic syenite. Also, as in the mixed gneisses below described, 

 many of the inclusions are sharply separated from the inclosing 

 rock, while others grade into the granite as a result of partial 

 fusion. 



Long, narrow, amphibolite (presumably Grenville) inclusions, 

 apparently like those so characteristic of the so-called '' Laurentian 

 granite " of the Thousand Islands region, also occur in some parts 

 of the granite, but are not abundant. Perhaps the best observed 

 locality for such inclusions is on the north shore of Clear pond 

 where numerous streaks or narrow layers of amphibolite are drawn 

 out parallel to the foliation of the pink granite and sometimes in 

 sharp contact with it. Such amphibolite inclusions are, however, 

 by no means characteristic of the granite since they are about as 

 commonly present in the facies of the syenite. Thus the normal 

 syenite and its basic variation on either shore of Long lake north- 

 east of Long Lake village afford excellent exhibitions of amphibolite 

 inclusions of the kind just described. The nature and frequency 

 of the inclusions therefore afford no criterion by which any possible 

 age differences between the syenite and granite could be determined. 



The absence of distinct limestone inclusions from the granite har- 

 monizes with the Thousand Islands region as described by Gushing 

 and Smyth ^ and the Haliburton-Bancroft area of eastern Ganada as 

 described by Adams and Barlow.^ According to Adams, the lenses 



1 N. Y. State Mus. Bui. 145, p. z?- iQio- 



2 Canada: Department of Mines, Geo!. Survey, Memoir 6, p. 62-114. 



