354 Canadian Record of Science. 



precisely the manner described above was also observed in 

 thin sections of a granite collected by Mr. J. B. Tyrrell of 

 the Canadian Geological Survey at Rock Point, Lake St. 

 Martin, Manitoba. Mr. Tyrrell states that it is, without 

 doubt, an eruptive granite. It occurs penetrating a dark 

 green hornblende schist through which arms of the granite 

 run in all directions while the schist contains imperfectly 

 developed staurolitic minerals, the result of contact 

 metamorphism. In other similar rocks from the Lake 

 Winnipeg district, epidote occurring in these peculiar forms 

 was observed. 



Granite from Coast Ranges, British Columbia. — The third 

 rock is from the Coast Ranges of British Columbia, where 

 it forms large exposures on the Stikine River not very 

 far from its mouth. It is of medium grain, grey and 

 porphyrtic with numerous small plagioclase crystals. 

 It is composed of quartz, plagioclase, orthoclase, biotite 

 and hornblende, and should be classed either as a quartz 

 diorite or a biotite hornblende granite, according to the 

 relative amounts of plagioclase and orthoclase present 

 in the rock, amounts which can only be determined by 

 a separation of the constituents by means of heavy 

 solutions or by chemical analysis. The rock is interesting 

 from the occurrence in it of allanite in rather large brown 

 pleochroic crystals with well marked zonal structure which 

 must be rather abundant, as they were found in three of 

 the six thin sections of this rock which were prepared. 



Conclusions. — The origin of the epidote and muscovite, as 

 well as of the calcite above described, is a question of con- 

 siderable interest. We may suppose these minerals to have 

 been produced in one of three ways. They might be : — 



1. Original minerals which were crystallized from a 

 granitic magna and subsequently corroded, eaten away and 

 partially reabsorbed as in the case of the quartz phen- 

 ocrysts in quartz porphyries, or the biotite and horn- 

 blende in many volcanic rocks. 



2. Minerals which have been developed during a complete 

 re-crystallization of the original rock, owing to pressure or 



