30 Canadian Record of Science. 



where a granite intrusion has caused profound chemical 

 change in dark argillitic mica schists. 



It seems to be a prevalent idea that basic magmas 

 frequently produce such metasomatosis, but that the only 

 effect of granitic intrusions, aside from insignificant 

 exhalations in the way of boron and fluorine compounds, 

 is diagenetic, It is possible that granites produce 

 chemical change less frequently than more basic intru- 

 sions, but that they do produce such change in some cases 

 is beyond all doubt when it is considered that several of 

 the articles referred to have been based on careful chemi- 

 cal investigation of the intrusive, the rock penetrated, 

 and the resulting contact zone. Hutchings 1 concludes 

 that in many such cases there has been a transfer of 

 material from the intruding rock to that which it meta- 

 morphoses, a transfer which is often large in proportion 

 to the relatively small masses of igneous rock concerned 

 in it. 



Kemp and Hollick have described an intrusion in 

 southern New York which is remarkably similar to this 

 one. They say : a " Interesting and marked changes mani- 

 fest themselves in both granite and limestone (near the 

 contact). In general it may be said that either the 

 former becomes an aggregate of light green monoclinic 

 pyroxene and scapolite, or we find a granite-like zone 

 formed between the two." " In resume 3 of these contacts it 

 may be said that the (hornblende) granite becomes richer 

 in pyroxene as they are approached. . . . Along the 

 contact is the ' scapolite zone ' consisting of coarsely 

 crystalline scapolite and malacolite. Next comes the 

 coarsely crystalline limestone charged with the aggregates 

 of silicates mentioned above" — pale pyroxene, green 

 hornblende, scapolite, titanite, etc. And finally, 4 " those 



1. " Notes on the Composition of Clays, Slates, etc., and on Some Points in their 

 Contact Metamorphism," Geol. Mag., Decade IV., Vol. I., p. 74. 



2. loc. cit., p. 644. 



3. loc. cit , p. 647. 4. p. 649. 



